Gastrointestinal tract

1 Holemans J.A., Matson M.B., Hughes J.A., et al. A comparison of air, carbon dioxide and air/carbon dioxide mixture as insufflation agents for double contrast barium enema. Eur. Radiol.. 1998;8:274-276.

Gellett L.R., Farrow R., Bloor C., et al. Pain after small bowel meal and pneumocolon: a randomized controlled trial of carbon dioxide versus air insufflation. Clin. Radiol.. 1999;54:381-383.

Pharmacological Agents

Glucagon

This polypeptide hormone produced by the alpha cells of the islets of Langerhans in the pancreas has a predominantly hyperglycaemic effect but also causes smooth muscle relaxation.

Adult dose

0.3 mg i.v. for barium meal

1.0 mg i.v. for barium enema.

Advantages

1. It is a more potent smooth muscle relaxant than Buscopan

2. Short duration of action (approx. 15 min)

3. It does not interfere with the small-bowel transit time.

Disadvantages

1. Hypersensitivity reactions are possible, as it is a protein molecule

2. Relatively long onset of action (1 min)

3. Cost.

Contraindications

1. Phaeochromocytoma. Glucagon can cause the tumour to release catecholamines, resulting in sudden and marked hypertension; 5–10 mg phentolamine mesilate may be administered i.v. in an attempt to control the blood pressure.

2. Caution is advised in the following conditions:¹

a Insulinoma: an initial increase in blood glucose may be followed by severe hypoglycaemia

b Glucagonoma.

Side-effects

1. Nausea and vomiting

2. Abdominal pain

3. Hypokalaemia

4. Hypotension

5. Rarely hypersensitivity reactions.

1 British National Formulary. 2007;54.

General points

In all barium work a high-kV technique is used (90–110 kV).

As in all radiological procedures, the ALARP (As Low As Reasonably Practicable) principle should be adhered to.

As regards women of child-bearing age, the ‘10-day rule’ is generally applied for both upper and lower gastrointestinal investigations.

Barium has superior contrast qualities and, unless there are specific contraindications, its use (rather than water-soluble agents) is preferred. The barium swallow is often done in conjunction with a barium meal.

CONTRAST SWALLOW

Indications – suspected oesophageal pathology

1. Dysphagia

2. Anaemia

3. Pain

4. Assessment of tracheo-oesophageal fistulae

5. Assessment of the site of perforation.

Contraindications

1. E-Z HD 200–250% 100 ml (or more, as required)

Contrast medium

2. Iodide-based contrast agent if perforation is suspected (e.g. Conray, Gastrografin)

3. LOCM (approx. 300 mg I ml⁻¹).

N.B.

1. Gastrografin should NOT be used for the investigation of a tracheo-oesophageal fistula or when aspiration is a possibility.

2. Barium should NOT be used if perforation is suspected.

Equipment

Rapid serial radiography (6 frames per s) or video recording may be required for assessment of the laryngopharynx and upper oesophagus during deglutition.

Patient preparation

None (but as for barium meal if the stomach is also to be examined – see p. 57).

Preliminary film

A control film is advised prior to a water-soluble study if perforation is suspected.

Technique

1. The patient is in the erect, right anterior oblique (RAO) position to throw the oesophagus clear of the spine. An ample mouthful of barium is swallowed, and spot films of the upper and lower oesophagus are taken. Oesophageal varices are better seen in the prone, right posterior oblique (RPO) position, as they will be more distended.

2. If rapid serial radiography is required, it may be performed in the right anterior oblique (RAO) and posterior anterior (PA) positions.

Modification of technique

To demonstrate a tracheo-oesophageal fistula in infants, a ‘pull back’ nasogastric tube oeosophogram may be performed. A nasogastric tube is introduced to the level of the mid-oesophagus, and the contrast agent (barium or LOCM) is syringed in to distend the oesophagus. This will force the contrast medium through any small fistula which may be present. It is important to take radiographs in the lateral projection during simultaneous injection of the contrast medium and withdrawal of the tube. Although some authors recommend that the infant be examined in the prone position whilst lying on the footstep of a vertical tilting table, satisfactory results are possible with children on their side on a horizontal table. It is important to watch for any possibility of aspiration into the airway from overspill. Overspill may lead to the incorrect diagnosis of tracheo-oesophageal fistula if it is not possible to determine whether contrast medium in the bronchi is due to a small fistula which is difficult to see or to aspiration.

Recently, it has been proposed that pull-back studies are not necessary in the majority of children, as tracheo-oesophageal fistulas can usually be demonstrated on standard contrast swallow examination, providing the oesophagus is distended well with contrast media.¹ Pull-back studies are still necessary for intubated patients, or those who are at high risk of aspiration. It is important to remember that fistulas are usually quite high, and the orifice can be occluded by an endotracheal tube. This can prevent the fistula being opacified. This can be rectified by altering the patients position, or slightly withdrawing the ET tube.

Aftercare

1. Leakage of barium from an unsuspected perforation

Complications

2. Aspiration.

1 Laffan E.E., Daneman A., Ein S.H., et al. Tracheoesophageal fistula without esophageal atresia: are pull-back tube esophagograms needed for diagnosis. Pediatr. Radiol.. 2006;36:1141-1147.

Barium Meal

Methods

1. Double contrast – the method of choice to demonstrate mucosal pattern.

2. Single contrast – uses:

a children – since it usually is not necessary to demonstrate mucosal pattern

b to demonstrate gross pathology only.

Indications

1. Failed upper gastrointestinal endosocpy

2. Dyspepsia

3. Weight loss

4. Upper abdominal mass

5. Gastrointestinal haemorrhage (or unexplained iron-deficiency anaemia)

6. Partial obstruction

7. Assessment of site of perforation – it is essential that a water-soluble contrast medium, e.g. Gastrografin or LOCM, is used.

Contraindications

Complete large-bowel obstruction.

Contrast medium

1. E-Z HD 250% w/v 135 ml

2. Carbex granules (double contrast technique).

Patient preparation

1. Nil orally for 6 h prior to the examination

2. It should be ensured that there are no contraindications to the pharmacological agents used.

Preliminary film

The double contrast method (Fig. 3.1):

Technique

1. A gas-producing agent is swallowed.

2. The patient then drinks the barium while lying on the left side, supported by the elbow. This position prevents the barium from reaching the duodenum too quickly and so obscuring the greater curve of the stomach.

3. The patient then lies supine and slightly on the right side, to bring the barium up against the gastro-oesophageal junction. This manoeuvre is screened to check for reflux, which may be revealed by asking the patient to cough or to swallow water while in this position. The significance of reflux produced by tipping the patient’s head down is debatable, as this is an unphysiological position. If reflux is observed, spot films are taken to record the level to which it ascends.

4. An i.v. injection of a smooth muscle relaxant (Buscopan 20 mg or glucagon 0.3 mg) is given. The administration of Buscopan has been shown not to affect the detection of gastro-oesophageal reflux or hiatus hernia.

5. The patient is asked to roll onto the right side and then quickly over in a complete circle, to finish in an RAO position. This roll is performed to coat the gastric mucosa with barium. Good coating has been achieved if the areae gastricae in the antrum are visible.

Figure 3.1 Barium meal sequence. Please note in a, b, c and d, the patient position is depicted as if the operator were standing at the end of the screening table looking towards the patient’s head. = Barium

Films

There is a great variation in views recommended, and the following is only the scheme used in our departments. In some departments fewer films are taken to reduce the cost and radiation dose:

1. Spot films of the stomach (lying):

a RAO – to demonstrate the antrum and greater curve

b Supine – to demonstrate the antrum and body

c LAO – to demonstrate the lesser curve en face

d Left lateral tilted, head up 45° – to demonstrate the fundus.

From the left lateral position the patient returns to a supine position and then rolls onto the left side and over into a prone position. This sequence of movements is required to avoid barium flooding into the duodenal loop, which would occur if the patient were to roll onto the right side to achieve a prone position.

2. Spot film of the duodenal loop (lying):

a Prone – the patient lies on a compression pad to prevent barium from flooding into the duodenum.

An additional view to demonstrate the anterior wall of the duodenal loop may be taken in an RAO position.

3. Spot films of the duodenal cap (lying):

a Prone

b RAO – the patient attains this position from the prone position by rolling first onto the left side, for the reasons mentioned above

c Supine

d LAO.

4. Additional views of the fundus in an erect position may be taken at this stage, if there is suspicion of a fundal lesion.

5. Spot films of the oesophagus are taken, while barium is being swallowed, to complete the examination.

Modification of technique for young children

The main indication will be to identify a cause for vomiting. The examination is modified to identify the three major causes of vomiting – gastro-oesophageal reflux, pyloric obstruction and malrotation, and it is essential that the position of the duodeno-jejunal flexure is demonstrated:

1. Single contrast technique using 30% w/v barium sulphate and no paralytic agent.

2. A relatively small volume of barium – enough to just fill the fundus – is given to the infant in the supine position. A film of the distended oesophagus is exposed.

3. The child is turned semi-prone into a LPO or RAO position. A film is exposed as barium passes through the pylorus. The pylorus is shown to even better advantage if 20–40° caudocranial angulation can be employed with an overhead screening unit. Gastric emptying is prolonged if the child is upset. A dummy coated with glycerine is a useful pacifier.

4. Once barium enters the duodenum, the infant is returned to the supine position, and with the child perfectly straight a second film is exposed as barium passes around the duodenojejunal flexure.

5. Once malrotation has been diagnosed or excluded, a further volume of barium is administered until the stomach is reasonably full and barium lies against the gastro-oesophageal junction. The child is gently rotated through 180° in an attempt to elicit gastro-oesophageal reflux.

In newborn infants with upper intestinal obstruction, e.g. duodenal atresia, the diagnosis may be confirmed if 20 ml of air is injected down the nasogastric tube (which will almost certainly have already been introduced by the medical staff). If the diagnosis remains in doubt, it can be replaced by a positive contrast agent (dilute barium or LOCM if the risk of aspiration is high).

Aftercare

1. The patient should be warned that his bowel motions will be white for a few days after the examination and may be difficult to flush away.

2. The patient should be advised to eat and drink normally to avoid barium impaction. Laxatives may be taken if required.

3. The patient must not leave the department until any blurring of vision produced by the Buscopan has resolved.

Complications

1. Leakage of barium from an unsuspected perforation

2. Aspiration of stomach contents due to the Buscopan

3. Conversion of a partial large bowel obstruction into a complete obstruction by the impaction of barium

4. Barium appendicitis, if barium impacts in the appendix (exceedingly rare)

5. Side-effects of the pharmacological agents used.

N.B. It must be emphasized that there are many variations in technique, according to individual preference, and that the best way of becoming familiar with the sequence of positioning is actually to perform the procedure oneself.

BARIUM FOLLOW-THROUGH

Methods

1. Single contrast

2. With the addition of an effervescent agent

3. With the addition of a pneumocolon technique.

Indications

1. Pain

2. Diarrhoea

3. Anaemia/gastrointestinal bleeding

4. Partial obstruction

5. Malabsorption

6. Abdominal mass.

Contraindications

1. Complete obstruction. This may not be an absolute contraindication if the surgical team are aware of this.

2. Suspected perforation (unless a water-soluble contrast medium is used).

Contrast medium

E-Z Paque 100% w/v 300 ml usually given in 10–15-min increments, although some radiologists give the full 300 ml at once. The transit time through the small bowel has been shown to be reduced by the addition of 10 ml of Gastrografin to the barium. In children, 3–4 ml kg⁻¹ is a suitable volume.

In situations where barium is contraindicated, non-ionic water-soluble solutions have been shown to be a satisfactory alternative.¹

Patient preparation

Metoclopramide 20 mg orally may be given before or during the examination.

Preliminary film

Plain abdominal film is used if small bowel obstruction is thought possible.

Technique

The aim is to deliver a single column of barium into the small bowel. This is achieved by laying the patient on his right side after the barium has been ingested. Metoclopramide enhances the rate of gastric emptying. If the transit time through the small bowel is found to be slow, the addition of an osmotic water-soluble contrast agent may help to speed it up. If a follow-through examination is combined with a barium meal, glucagon is used for the duodenal cap views rather than Buscopan because it has a short length of action and does not interfere with the small-bowel transit time.

Films

1. Prone PA films of the abdomen are taken every 15–20 min during the first hour, and subsequently every 20–30 min until the colon is reached. The prone position is used because the pressure on the abdomen helps to separate the loops of small bowel.

2. Spot films of the terminal ileum are taken supine, using a compression pad.

Aftercare

As for barium meal.

Complications

As for barium meal.

1 Jobling C., Halligan S., Bartram C. The use of water-soluble contrast agents for small bowel follow-through examinations. Eur. Radiol.. 1999;9:706-710.

Ha H.K., Shin J.H., Rha S.E., et al. Modified small bowel follow through: use of methylcellulose to improve bowel transradiance and prepare barium suspension. Radiology. 1999;211:197-201.

Summers D.S., Roger M.D., Allan P.L., et al. Accelerating the transit time of barium sulphate suspensions in small bowel examinations. Eur. J. Radiol.. 2007;62(1):122-125.

Small-Bowel Enema

Advantage

This procedure gives better visualization of the proximal small bowel than that achieved by a barium follow-through because rapid infusion of a large, continuous column of contrast medium directly into the jejunum provides better distension of the proximal small bowel. This is less effective in the ileum.

Disadvantages

1. Intubation may be unpleasant for the patient, and may occasionally prove difficult.

2. It is more time-consuming for the radiologist.

3. There is a higher radiation dose to the patient (screening the tube into position).

Indications and Contraindications

These are the same as for a barium follow-through. In some departments it is only performed in the case of an equivocal follow-through.

Contrast medium

1. E-Z Paque 70% w/v diluted

2. Dilute Baritop

3. 600 ml of 0.5% methylcellulose after 500 ml of 70% w/v barium.¹

It may be difficult to obtain good distension and double-contrast effect of the distal small bowel and terminal ileum.

Equipment

A choice of tubes is available:

1. Bilbao-Dotter tube with a guidewire (the tube is longer than the wire so that there is reduced risk of perforation when introducing the wire).

2. Silk tube (E. Merck Ltd). This is a 10-F, 140-cm long tube. It is made of polyurethane and the stylet and the internal lumen of the tube are coated with a water-activated lubricant to facilitate the smooth removal of the stylet after insertion.

Patient preparation

1. NBM after midnight

2. If the patient is taking any antispasmodic drugs, they must be stopped 1 day prior to the examination

3. Tetracaine lozenge 30 mg, 30 min before the examination.

Immediately before the examination the pharynx is anaesthetized with lidocaine spray.

Preliminary film

Plain abdominal film is used if a small bowel obstruction is suspected.

Technique

1. The patient sits on the edge of the X-ray table. The pharynx is thoroughly anaesthetized with lidocaine spray. If a per nasal approach is planned, the patency of the nasal passages is checked by asking the patient to sniff with one nostril occluded. The silk tube should be passed with the guidewire pre-lubricated and fully within the tube, whereas for the Bilbao-Dotter tube it may be more comfortable to introduce the guidewire after the tube tip is in the stomach.

2. The tube is then passed through the nose or the mouth, and brief lateral screening of the neck may be helpful in negotiating the epiglottic region. The patient is asked to swallow with the neck flexed, as the tube is passed through the pharynx. The tube is then advanced into the gastric antrum.

3. The patient then lies down and the tube is passed into the duodenum. Various manoeuvres may be used alone or in combination, to help this part of the procedure, which may be difficult:

a Lay the patient on his left side so that the gastric air bubble rises to the antrum, thus straightening out the stomach.

b Advance the tube whilst applying clockwise rotational motion (as viewed from the head of the patient looking towards the feet).

c In the case of the Bilbao-Dotter tube, introduce the guidewire.

d Get the patient to sit up, to try to overcome the tendency of the tube to coil in the fundus of the stomach.

e Metoclopramide (20 mg i.v.) may help.

4. When the tip of the tube has been passed through the pylorus, the guidewire tip is maintained at the pylorus as the tube is passed over it along the duodenum to the level of the ligament of Treitz. Clockwise torque applied to the tube may again help in getting past the junction of the first and second parts of the duodenum. The tube is passed beyond the duodenojejunal flexure to diminish the risk of aspiration due to reflux of barium into the stomach.

5. Barium is then run in quickly, and spot films are taken of the barium column and its leading edge at the regions of interest, until the colon is reached. If methylcellulose is used, it is infused continuously, after an initial bolus of 500 ml of barium, until the barium has reached the colon.

6. The tube is then withdrawn, aspirating any residual fluid in the stomach. Again, this is to decrease the risk of aspiration.

7. Finally, prone and supine abdominal films are taken.

Modification of technique

In patients with malabsorption, especially if an excess of fluid has been shown on the preliminary film, the volume of barium should be increased (240–260 ml). Compression views of bowel loops should be obtained before obtaining double contrast. Flocculation is likely to occur early. If it is important to obtain images of the duodenum, the catheter tip should be sited proximal to the ligament of Trietz.

Aftercare

The patient should be warned that diarrhoea may occur as a result of the large volume of fluid given.

Complications

1. Aspiration

2. Perforation of the bowel owing to manipulation of the guidewire (very rare).

1 Ha H.K., Park K.B., Kim P.N., et al. Use of methylcellulose in small bowel follow through examination: comparison with conventional series in normal subjects. Abdom. Imaging. 1998;23:281-285.

Cirillo L.C., Camera L., Della Noce M., et al. Accuracy of enteroclysis in Crohn’s disease of the small bowel: a retrospective study. Eur. Radiol.. 2000;10(12):1894-1898.

Minordi L.M., Vecchioli A., Guidi L., et al. Multidetector CT enteroclysis versus barium enteroclysis with methylcellulose in patients with suspected small bowel disease. Eur. Radiol.. 2006;16(7):1527-1536.

Nolan D.J. The true yield of the small intestinal barium study. Endoscopy. 1997;29:447-453.

Barium Enema

Methods

1. Double contrast – the method of choice to demonstrate mucosal pattern.

2. Single contrast – uses:

a children – since it is usually not necessary to demonstrate mucosal pattern

b reduction of an intussusception (see p. 71)

c localization of an obstructing colonic lesion.

Indication

Suspected large bowel pathology.

N.B. If a tight stricture is demonstrated, only run a small volume of barium proximally to define the upper margin, as otherwise the barium may impact.

Contrast medium

1. Polibar 115% w/v 500 ml (or more, as required)

2. Air.

Equipment

Miller disposable enema tube.

Technique

The double-contrast method (Fig. 3.2):

1. The patient lies on their left side, and the catheter is inserted gently into the rectum. It is taped firmly in position. Connections are made to the barium reservoir and the hand pump for injecting air.

2. An i.v. injection of Buscopan (20 mg) or glucagon (1 mg) is given. Some radiologists choose to give the muscle relaxant half way through the procedure.

3. The infusion of barium is commenced. Intermittent screening is required to check the progress of the barium. The infusion is terminated when the barium reaches the hepatic flexure. The column of barium within the sigmoid colon is run back out by either lowering the infusion bag to the floor or tilting the table to the erect position.

4. Air is gently pumped into the bowel, forcing the column of barium round towards the caecum, and producing the double-contrast effect. Some centres use CO₂ as the negative contrast agent as it has been shown to reduce the incidence of severe, post-double-contrast enema pain.³

Figure 3.2 Barium enema sequence. Please note in a, b and f the patient position is depicted as if the operator were standing at the end of the screening table looking towards the patient’s head.

Aftercare

1. Patients should be warned that their bowel motions will be white for a few days after the examination, and to eat and drink normally to avoid barium impaction.

2. The patient must not leave the department until any blurring of vision produced by the Buscopan has resolved.

1 Marion J.F., Present D.H. The modern medical management of acute severe ulcerative colitis. Eur. J. Gastroenterol. Hepatol.. 1997;9:831-835.

2 Low V.H. What is the current recommended waiting time for performance of a gastrointestinal barium study after endoscopic biopsy of the upper or lower gastrointestinal tract? Am. J. Roentgenol.. 1998;170:1104-1105.

3 Taylor P.N., Beckly D.E. Use of air in double contrast barium enema: is it still acceptable? Clin. Radiol.. 1991;44:183-184.

Cittadini G., Sardanelli F., De Cicco E., et al. Bowel preparation for the double contrast barium enema: how to maintain coating with cleansing? Clin. Radiol.. 1999;54:216-220.

Ferrucci J.T. Double-contrast barium enema: use in practice and implications for CT colonography. Am. J. Roentgenol.. 2006;187(1):170-173.

Martin C.J. A review of factors affecting patient doses for barium enemas and meals. Br. J. Radiol.. 2004;77(922):864-868.

Rollandi G.A., Biscaldi E., DeCicco E. Double contrast barium enema: technique, indications, results and limitations of a conventional imaging methodology in the MDCT virtual endoscopy era. Eur. J. Radiol.. 2007;61(3):382. –327

The ‘Instant’ Enema

REDUCTION OF AN INTUSSUSCEPTION

This procedure should only be attempted in full consultation with the surgeon in charge of the case and when an anaesthetist with adequate paediatric training and experience, and with paediatric anaesthetic equipment, is available.^1,²

Methods

1. Using air and fluoroscopy ³ – barium is no longer used in the majority of centres as air reduction has the following advantages:

a more rapid reduction, because the low viscosity of air permits rapid filling of the colon

b reduced radiation dose because of the above

c more effective reduction

d in the presence of a perforation, air in the peritoneal cavity is preferable to barium, and gut organisms are not washed into the peritoneal cavity

e there is more accurate control of intraluminal pressure

f less mess, and a dry infant will not lose heat

g less expensive.

2. Using a water-soluble contrast medium and US.

Contraindications

1. Peritonitis or perforation

2. The pneumatic method should probably not be used in children over 4 years of age as there is a higher incidence of significant lead points which may be missed ⁴

3. Successful reduction is less likely in patients with prolonged symptoms or radiographic signs of obstruction, but this does not preclude an attempt at reduction if the patient is well hydrated and stable.⁵

Patient preparation

1. Sedation is of questionable value, but analgesia is important (e.g. morphine 50 μg kg⁻¹ if <1 year or 50–100 μg kg⁻¹ if >1 year).

2. Some institutions perform the examination under general anaesthesia. This has the advantages of greater muscle relaxation, which may increase the likelihood of successful reduction, and also enables the child to go to surgery quickly in the event of a failed radiological reduction.

3. Correction of fluid and electrolyte imbalance. The child has an i.v. line in-situ.

4. Antibiotic cover is not routine.

Preliminary investigations

1. Plain abdominal film – to assess bowel distension and to exclude perforation. A right-side-up decubitus film is often helpful in confirming the diagnosis by showing a failure of caecal filling with bowel gas because of the presence of the soft-tissue mass of the intussusception. Normal plain films do not exclude the diagnosis, and the clinical findings and/or history should be sufficient indications.

2. US – should confirm or exclude the diagnosis. Absence of blood flow within the intussusceptum on colour-flow Doppler should lead to cautious reduction.⁶ US may identify a lead point; if so, even attempted reduction (to facilitate surgery) should be followed by surgery. If US identifies fluid trapped between the intussusceptum and intussuscipiens, the success rate is significantly reduced.⁷

Contrast medium

1. Air

2. Barium sulphate 100% w/v (now rarely used)

3. Water-soluble contrast, e.g. LOCM 150 or dilute Gastrografin (1 part Gastrografin to 4 or 5 parts water).

Technique

A 16–22-F balloon catheter is inserted into the rectum and the buttocks taped tightly together to provide a seal. It may be necessary to inflate the balloon but if this is done it should be performed under fluoroscopic control so that the rectum is not over distended.

Pneumatic reduction

1. The child is placed in the prone position so that it is easier to maintain the catheter in the rectum and the child is disturbed as little as possible during the procedure.

2. Air is instilled by a hand or mechanical pump and the intussusception is pushed back by a sustained pressure of up to 80 mmHg. If this fails, the pressure may be increased to 120 mmHg. Pressure should be monitored at all times and there should be a pressure release valve in the system to ensure that excessive pressures are not delivered.

3. Reduction is successful when there is free flow of air into the distal ileum.

4. If the intussusception does not move after 3 min of sustained pressure, the pressure is reduced and the child rested for 3 min. If, after three similar attempts, the intussusception is still immovable it is considered irreducible and arrangements are made for surgery.

5. The intussusception is only considered completely reduced when the terminal ileum is filled with air. However, it is not uncommon for there to be a persisting filling defect in the caecum at the end of the procedure, with or without reflux of air into the terminal ileum. This is often due to an oedematous ileocaecal valve. In the presence of a soft-tissue caecal mass, a clinically well and stable child should be returned to the ward to await a further attempt at reduction after a period of 2–8 h rather than proceed to surgery. A second enema is often successful at complete reduction or showing resolution of the oedematous ileocaecal valve.⁸

6. When air (or barium) dissects between the two layers of the intussusception – the dissection sign – reduction is less likely.⁹

Barium reduction: now rarely used

1. Patient positioning is as for the pneumatic method.

2. The bag containing barium is raised 100 cm above the table top and barium run in under hydrostatic pressure. Progress of the column of barium is monitored by intermittent fluoroscopy.

3. If the intussusception does not move after 3 min of sustained pressure, the bag of barium is lowered to table-top height and the child rested for 3 min. If, after three similar attempts, the intussusception is still immovable it is considered irreducible and arrangements are made for surgery.

4. The points regarding failed or incomplete reduction discussed above also apply to hydrostatic reduction.

Ultrasound reduction

1. To facilitate scanning the child must be supine.

2. The intussusception can be identified with US. The contrast medium is run as far as the obstruction and its passage around the colon and the reducing head of the intussusception monitored by US.

3. The points regarding failed or incomplete reduction discussed above also apply to this technique.

Films

1. Spot films as required

2. Post-reduction film.

Aftercare

Observation in hospital for 24 h.

Complications

Perforation. For the pneumatic method, if a pump is used without a pressure-monitoring valve, perforation may result in a tension pneumoperitoneum, resulting in respiratory embarrassment. Puncture of the peritoneal cavity with a ‘green’ 23-G needle may be life-saving.

1 The Royal College of Anaesthetists. Guidelines for the Provision of Anaesthetic Services. Guidance on the Provision of Paediatric Anaesthesia. London: Royal, 1999;24-26.

2 The British Association of Paediatric Surgeons. revised 1995. A Guide for Purchasers and Providers of Paediatric Surgeons. London: British Association of Paediatric Surgeons; 1994.

3 Kirks D.R. Air intussusception reduction: ‘The winds of change’. Pediatr. Radiol.. 1995;25:89-91.

4 Stringer D.A., Ein S.H. Pneumatic reduction: advantages, risks and indications. Pediatr. Radiol.. 1990;20:475-477.

5 Daneman A., Navarro O. Intussusception Part 2: An update on the evolution of management. Paediatr. Radiol.. 2004;34:97-108.

6 Lim H.K., Bae S.H., Lee K.H., et al. Assessment of reducibility of ileocolic intussusception in children: usefulness of color Doppler sonography. Radiology. 1994;191:781-785.

7 Britton I., Wilkinson A.G. Ultrasound features of intussusception predicting outcome of air enema. Pediatr. Radiol.. 1999;29:705-710.

8 Gorenstein A., Raucher A., Serour F., et al. Intussusception in children: reduction with repeated, delayed air enema. Radiology. 1998;206:721-724.

9 Barr L.L., Stansberry S.D., Swischuk L.E. Significance of age, duration, obstruction and the dissection sign in intussusception. Pediatr. Radiol.. 1990;20:454-456.

Contrast Enema in Neonatal Low Intestinal Obstruction

The differential diagnosis of low intestinal obstruction in the newborn consists of five conditions which comprise nearly all causes. Three involve the colon: Hirschsprung’s disease, functional immaturity of the colon (small left colon syndrome, meconium plug syndrome) and colonic atresia. Two involve the distal ileum: meconium ileus and ileal atresia. All infants with low intestinal obstruction require a contrast enema.

Contraindications

Perforation.

Patient preparation

The baby should already have i.v. access and be well hydrated prior to the procedure.

Contrast medium

Dilute ionic contrast medium as is used for cystography, e.g. Urografin 150. This has the advantage of not provoking large fluid shifts and being dense enough to provide satisfactory images. Non-ionic contrast media and barium offer no advantages and the latter is contraindicated with perforation as a possibility. Infants with meconium ileus or functional immaturity will benefit from a water-soluble contrast enema and so their therapeutic enema commences with the diagnostic study. The non-operative treatment of meconium ileus was first described using the hypertonic agent Gastrografin, which dislodged the sticky meconium by drawing water into the bowel lumen. However, most paediatric radiologists now believe that a hypertonic agent is not necessary for successful treatment.¹

Technique

If the enema demonstrates that the entire colon is small (a microcolon; <1 cm in diameter) then the diagnosis is likely to be meconium ileus or ileal atresia. (The microcolon of prematurity and total colonic Hirschsprung’s disease are alternative rare diagnoses.) For the treatment of meconium ileus, the aim is to run the water-soluble contrast medium into the small bowel to surround the meconium. An attempt should be made to get the contrast medium back into dilated small bowel. If successful, meconium should be passed in the next hour. If no result is seen and the infant’s condition deteriorates then surgical intervention will be necessary. If the passage of meconium is incomplete and the clinical condition remains stable, multiple enemas over the succeeding few days will be necessary to ensure complete resolution of the obstruction.

Overall success rate is approximately 50–60%, with a perforation rate of 2%.¹

1 Kao S.C.S., Franken E.A.Jr. Nonoperative treatment of simple meconium ileus: a survey of the Society for Pediatric Radiology. Pediatr. Radiol.. 1995;25:97-100.

Sinogram

1. A water-soluble contrast medium should be used.

2. A preliminary film is taken to exclude the presence of a radio-opaque foreign body.

3. An appropriate-size Foley catheter is then inserted into the orifice of the sinus and the balloon inflated to prevent retrograde flow.

4. The contrast medium is injected carefully under fluoroscopic control.

5. Spot films are taken as required, including tangential views.

RETROGRADE ILEOGRAM

Indications

To demonstrate anatomy of small bowel in patients with an ileostomy.

Technique

1. Cannulate the ileostomy with an appropriate (16–22-F) Foley catheter. Carefully inflate the balloon.

2. Inject contrast. Dilute barium (Baritop) can be used as a single contrast or as double contrast with either air or water/methyl cellulose (see small bowel enema). Water-soluble contrast media may be used.

COLOSTOMY ENEMA

Indications

To demonstrate proximal colon following resection of the rectum.

Technique

1. Cannulate colostomy with a 22–26-F Foley catheter and gently inflate balloon.

2. Infuse barium as for a barium enema.

LOOPOGRAM

Indications

Appropriate in patients following bladder resection to demonstrate anatomy of ileal conduit, ureters, and renal pelvicalyceal systems.

Contrast

Low concentration water-soluble contrast agent (150 mg/ml⁻¹).

Technique

Cannulate ileal conduit with 14–18-F Foley catheter and gently inflate balloon. Inject contrast into ileal conduit.

HERNIOGRAM

Indications

1. History suggestive of a hernia with a normal/inconclusive physical examination.

2. Undiagnosed groin pain.

Contraindications

1. Infancy

2. Pregnancy

3. Intestinal obstruction

4. Allergy to contrast medium.

Patient preparation

The patient is asked to empty their bladder just prior to the examination.

Contrast medium

50–100 ml water-soluble medium (e.g. Omnipaque 300).

Technique

1. The patient lies supine on the X-ray table.

2. An aseptic technique is employed.

3. 5–10 ml of 1% lidocaine is injected into the skin, subcutaneous tissues and peritoneum. The injection site varies between operators; the midline just below the umbilicus is most common, the midpoint of the left lateral rectus muscle is one variation.

4. A 18G spinal needle is introduced into the peritoneal cavity and used to inject contrast into the peritoneal cavity.

Films

1. Prone

2. Erect films: frontal, obliques, lateral.

The patient is asked to cough and perform the Valsalva manoeuvre while these are taken. The tube may be angled 25° caudally.

Complications

These are uncommon, and patient admission for observation is all that is usually required:

1. Pain

2. Visceral puncture

3. Vascular puncture

4. Injection into the abdominal wall

5. Haematoma at the injection site

6. Allergy to contrast medium.

Ekberg O. Inguinal herniography in adults: technique, normal anatomy, and diagnostic criteria for hernias. Radiology. 1981;138:31-36.

Ekberg O. Complications after herniography in adults. Am. J. Roentgenol.. 1983;140:490-495.

Garner J.P., Patel S., Glaves J., et al. Is herniography useful. Hernia. 2006;10(1):66-69.

Gwanmesia I.I., Walsh S., Bury R., et al. Unexplained groin pain: safety and reliability of herniography for the diagnosis of occult hernias. Postgrad. Med. J.. 2001;77(906):250-251.

Evacuating Proctogram

Indications

1. Constipation

2. Suspected pelvic floor weakness – posterior (rectocoele/enterocoele/rectal intussuception)

3. Anorectal incontinence – anal manometry and anal US preferred.

Contraindications

Pregnancy.

Contrast medium

Thick barium paste (although commercial pastes are available, this may be satisfactorily prepared with barium powder and cereal, e.g. Readibrek).

Technique

1. One can of Baritop or equivalent given orally 1 hour prior to examination to opacify small bowel

2. For female patients, approximately 20–30 ml of water-soluble contrast mixed with US gel are introduced into the vagina through a Foley catheter

3. Approximately 120 ml of barium paste (or enough to fill the rectum) are instilled via a bladder syringe.

Films

1. These are taken in a lateral projection with the patient sitting on a commode

2. Video-recording at rest and during the Valsalva manoeuvre and during pelvic floor contractions

3. Video-recording during defecation using a maximum of 1- min screening time to minimize patient dose.

Dobben A.C., Wiersma T.G., Janssen L.W., et al. Prospective assessment of interobserver agreement for defecography in fecal incontinence. Am. J. Roentgenol.. 2005;185(5):1166-1172.

Jones H.J., Swift R.I., Blake H. A prospective audit of the usefulness of evacuating proctography. Ann. R. Coll. Surg. Engl.. 1998;80(1):40-45.

Kelvin F.M., Maglinte D.D., Hornback J.A., et al. Pelvic prolapse: assessment with evacuation proctography (defecography). Radiology. 1992;184:547-551.

Coeliac Axis, Superior Mesenteric and Inferior Mesenteric Arteriography

Indications

1. Gastrointestinal haemorrhage

2. Staging tumours prior to intervention (surgical or radiological)

3. Gastrointestinal ischaemia

4. Portal venography. (This is rarely needed except prior to intervention as CT/MR shows PV system well.)

Contrast medium

LOCM 280 to 370.

Equipment

1. Digital fluoroscopy with angiography facility

2. Pump injector

3. Catheter – selective femorovisceral, sidewinder or cobra catheter.

Technique

1. Femoral artery puncture – Seldinger technique

2. Bowel movement causing subtraction artifact can be reduced by using a smooth-muscle relaxant (e.g. Buscopan 10–20 mg) and abdominal compression

3. When performed for gastrointestinal bleeding, provided that the patient is actively bleeding at the time, a blood loss of 0.5–0.6 ml min⁻¹ can be demonstrated. The site of active bleeding is revealed by extravasated contrast medium remaining in the bowel on the late films, when intravascular contrast has cleared. Vascular malformations, tumours and varices may be demonstrated.

Coeliac axis

Patient supine; 25–36 ml contrast medium at 5–6 ml s⁻¹.

(Angiography of the pancreas is best achieved by selective injection into the splenic, dorsal pancreatic and gastroduodenal arteries.)

Superior mesenteric artery

Patient supine; 25–42 ml contrast medium at 5–7 ml s⁻¹.

Late-phase visceral arteriography

Patient slightly RPO.

When selective catheterization of the coeliac or SMA has been achieved, delayed venous-phase films will show the portal vein.

N.B. If splenic vein opacification is required, then a late-phase splenic arteriogram is necessary.

Inferior mesenteric artery

If the inferior mesenteric artery is to be examined as part of a procedure which will examine the superior mesenteric artery or coeliac axis as well, e.g. to find the source of gastrointestinal bleeding, then the inferior mesenteric artery should be examined first so that contrast medium in the bladder will not obscure its terminal branches.

Patient 30° LPO (to open the sigmoid loop); 10–20 ml at 4 ml s⁻¹.

ULTRASOUND OF THE GASTROINTESTINAL TRACT

ENDOLUMINAL EXAMINATION OF THE OESOPHAGUS AND STOMACH

Indications

1. Staging of primary malignant disease of the upper gastrointestinal tract or mediastinal pathology, such as suspected lymphadenopathy or mass

2. US-guided biopsy of primary tumours or suspected nodal disease.

Equipment

Echoendoscope with 5.0–10-MHz 360° rotary transducer.

Patient preparation

Conscious sedation is usually required.

Technique

Monitoring with a pulse oximeter is recommended. If the stomach is to be examined, this may be filled with de-aerated water through the working channel before the patient is examined in a left lateral decubitus position. The echo-endoscope is passed during endoscopy, either combined with direct vision or blind by an experienced endoscopist. A 360° rotary transducer will provide transverse scans with respect to the long axis of the tube.

Aftercare

The patient should be observed by experienced nursing staff until the effects of any sedation have worn off, in the same manner as for other endoscopic procedures.

Botet J.F., Lightdale C. Endoscopic ultrasonography of the upper gastrointestinal tract. Radiol. Clin. North Am.. 1992;30:1067-1083.

Weber W.A., Ott K. Imaging of esophageal and gastric cancer. Semin. Oncol.. 2004;31(4):530-541.

Transabdominal Examination of the Lower Oesophagus and Stomach

Indications

Not routinely indicated in adults.

HYPERTROPHIC PYLORIC STENOSIS

The typical patient is a 6-week-old male infant with non-bilious projectile vomiting.

Equipment

5–7.5-MHz linear or sector transducer.

Technique

1. The right upper quadrant is scanned with the patient supine. If the stomach is very distended, the pylorus will be displaced posteriorly and the stomach should be decompressed with a nasogastric tube. If the stomach is collapsed, the introduction of some dextrose, by mouth or via a nasogastric tube, will distend the antrum and differentiate it from the pylorus.

2. The pylorus is scanned in its longitudinal and transverse planes and images will resemble an olive and a doughnut, respectively. The poorly echogenic muscle is easily differentiated from the bright mucosa. Antral peristalsis can be seen and the volume of fluid passing through the pylorus with each antral wave can be assessed.

3. A number of measurements can be made. These include muscle thickness, canal length, pyloric volume and muscle thickness/wall diameter ratio, but there is no universal agreement as to which is the most discriminating parameter.

King S.J. Ultrasound of the hollow gastrointestinal tract in children. Eur. Radiol.. 1997;7:559-565.

Misra D., Akhter A., Potts S.R., et al. Pyloric stenosis. Is over reliance on ultrasound scans leading to negative explorations. Eur. J. Ped. Surg.. 1997;7:328-330.

Small Bowel

Brown J.J. Acute appendicitis the radiologist’s role. Radiology. 1991;180:13-14.

Simonovský V. Sonographic detection of normal and abnormal appendix. Clin. Radiol.. 1999;54:533-539.

Large Bowel

Indications

At present, colonoscopy, CT or barium examinations are first-line imaging investigations, but large-bowel masses can be visualized by US during a routine abdominal scan.

Beynon J., Feifel G.A., Hildebrandt U., et al. An Atlas of Rectal Endosonography. Berlin: Springer-Verlag, 1991.

CT of the Gastrointestinal Tract

Indications

1. Abdominal mass

2. Tumour staging

3. Appendicitis – focused appendiceal CT (FACT)

4. Large and small bowel obstruction

5. Altered bowel habit in the elderly and infirm.

Oral and i.v. contrast media are usually employed. Oral contrast should be given at least 24 and perhaps 48 h before the examination to opacify the large bowel. Iodinated or barium-based oral contrast may not be necessary with multi-slice CT scanners.

Oral contrast is not necessary and may be contraindicated in patients with suspected intestinal obstruction. Fluid within dilated bowel will act as a negative contrast agent and allow definition of the transition point. Scans are usually obtained in portal venous phase following i.v. contrast. Slice thickness will depend upon the specification of the CT scanner. Viewing images in coronal and sagittal as well as axial planes may be helpful.

N.B. CT gives a high radiation dose (see Appendix II).

Boudiaf M., Soyer P., Terem C., et al. CT evaluation of small bowel obstruction. Radiographics. 2001;21(3):613-624.

Domjan J., Blaquiere R., Odurny A. Is minimal preparation CT comparable with barium enema in elderly patients with colonic symptoms. Clin. Radiol.. 1998;53:894-898.

Peck J.J., Milleson T., Phelan J. The role of computed tomography with contrast and small bowel follow-through in the management of small bowel obstruction. Am. J. Surg.. 1999;177:375-378.

Rao P.M., Boland G.W. Imaging of acute right lower abdominal quadrant pain. Clin. Radiol.. 1998;53:639-649.

Wittenberg J., Harisinghani M.G., Jhaveri K., et al. Algorithmic approach to CT diagnosis of the abnormal bowel wall. Radiographics. 2002;22(5):1093-1107.

Computed Tomographic Colonography

Indications

1. Incomplete colonoscopy – can be performed the same day with no further preparation

2. Patients at risk or who have aversion to colonoscopy

3. Patients with an obstructing lesion preventing full colonoscopy who require full evaluation of the colon

4. Other indications are controversial and include screening for colorectal cancer, and evaluation of colorectal cancer and colonic polyps.

Technique

1. Large-bowel preparation as for barium enema (see above). Diabetic patients may need to be admitted onto the ward for the duration of the bowel preparation

2. Patient to go to toilet immediately before procedure

3. Intravenous access obtained

4. Patient positioned on their side and Foley catheter placed in rectum and air insufflated. Alternatively an empty enema bag is filled with air. The rectal catheter is inserted into the rectum and gentle pressure on the enema bag is used to introduce air via the rectal tube to distend the large bowel. A CO₂ machine may be used to insufflate the colon, 20–25 psi to be maintained throughout the examination (4 l CO₂ initially maintained at 20–25 psi)

5. Patient turned into supine or prone position during gas insufflation

6. 20 mg i.v. Buscopan or 1 mg i.v. glucagon given during insufflation

7. CT scout performed to check satisfactory gaseous distension of large bowel

8. CT parameters will depend upon the type of CT scanner available. CT scans may be performed using a low-dose technique (e.g. 80 mA) without i.v. contrast, or i.v. iodinated contrast may be given and scans performed in portal phase (70 s delay) using usual diagnostic CT parameters

9. Patients may be scanned initially in a supine position using low dose and then turned prone; further insufflation may be needed (e.g. 2 l CO₂) and a further low-dose scan performed.

Aschoff A.J., Ernst A.S., Brambs H.J. CT colonography: an update. Eur. Radiol.. 2008;18(3):429-437.

Blachar A., Sosna J. CT colonography (virtual colonoscopy): technique, indications and performance. Digestion. 2007;76(1):34-41.

Geenen R.W., Hussain S.M., Cademartiri F., et al. CT and MR colonography: scanning techniques, post processing, and emphasis on polyp detection. Radiographics. 2004;24(1):e18.

Mang T., Maier A., Plank C., et al. Pitfalls in multi-detector row CT colonography: a systematic approach. Radiographics. 2007;27(2):431-454.

Tolan D.J., Armstrong E.M., Chapman A.H. Replacing barium enema with CT colonography in patients older than 70 years: the importance of detecting extracolonic abnormalities. Am. J. Roentgenol.. 2007;189(5):1104-1111.

Magnetic Resonance Imaging of the Gastrointestinal Tract

Indications

1. Suspected perianal fistula

2. Local staging of rectal cancer

3. Evaluation of inflammatory bowel disease.

Contraindications

1. Standard MRI contraindications – see Chapter 1

2. Some gadolinium-based contrast agents are contraindicated in patients with known or suspected renal dysfunction – see Chapter 2.

Contrast agents

Contrast agents that can be used to alter the signal intensity within the bowel can be classified as positive contrast agents (high signal on T1-weighting) or negative agents (low signal on T2-weighting) or biphasic (e.g. Klean-Prep). However, air itself (within bowel) is a natural contrast agent and the addition of expensive contrast agents is not often necessary.

Motion artifacts

The time taken to obtain a scan can be in the order of several minutes if spin echo sequences are used. Consequently, it is important to minimize peristalsis and respiration artifacts. Glucagon or buscopan should be used to try and minimize peristalsis. A prone position or a compression band can be used to help reduce respiratory motion of the anterior abdominal wall. The artifact, which is propagated from the anterior abdominal wall during respiration, is also due to the high signal from fat. Consequently, fat suppression sequences can help to minimize this.

Pulse sequences

The sequences used for imaging the abdomen and gastrointestinal tract will depend on the nature of the clinical problem. Very fast sequences such as breath-hold gradient echo (GE) and single-shot fast-spin echo (SE) sequences may be used to minimize any movement artifact. However, they do suffer from relatively poor contrast resolution. Standard fast-spin echo T1-weighted and T2-weighted sequences (with gadolinium and fat suppression added as necessary) are often used as baseline sequences, but on occasion suffer from movement artifact. The plane of the sequences will depend on the clinical problem but axial scans are frequently used in the first instance with orthogonal planes (coronal or sagittal) as required.

Techniques

Suspected peri-anal fistula

1. No patient preparation required

2. Patient supine in MRI scanner

3. Axial and coronal high-resolution scans using T1W SE, T2W SE (with fat saturation) or short tau inversion recovery (STIR). Scans following intravenous gadolinium using T1W with fat saturation may be obtained to demonstrate active inflammatory change.

Local staging of colorectal cancer

1. Patient supine

2. Sagittal T2 -weighted SE sequence of central pelvic structures. Use this scan to plan orthogonal, high-resolution axial and coronal T2 W, e.g. (TR 6270 TE122) voxel size 0.9×0.9×3 mm. SE 3 mm contiguous slices FOV 240 phase FOV 100%, phase resolution 256.

Small-bowel magnetic resonance enterography

1. Drink oral MR contrast (1.5 l)

2. Obtain venous access

3. Give Buscopan 20 mg i.v.

4. Obtain sequences in coronal and axial planes using HASTE, FISP sequences or other manufacturer’s equivalent

5. Give gadolinium-based contrast agent i.v.

6. Obtain fast 3D T1W fat suppressed (e.g. VIBE) sequences.

Berman L., Israel G.M., McCarthy S.M., et al. Utility of magnetic resonance imaging in anorectal disease. World J. Gastroenterol.. 2007;13(23):3153-3158.

Buchanan G.N., Halligan S., Bartram C.I., et al. Clinical examination, endosonography, and MR imaging in preoperative assessment of fistula in ano: comparison with outcome-based reference standard. Radiology. 2004;233:674-681.

Fidler J. MR imaging of the small bowel. Radiol. Clin. North Am.. 2007;45(2):317-331.

Halligan S., Stoker J. Imaging of fistula in ano. Radiology. 2006;239:18-33.

Schreyer A.G., Geissler A., Albrich H., et al. Abdominal MRI after enteroclysis or with oral contrast in patients with suspected or proven Crohn’s disease. Clin. Gastroenterol. Hepatol.. 2004;2(6):491-497.

Radionuclide Gastro-Oesophageal Reflux Study

Indications

Diagnosis and quantification of suspected gastro-oesophageal reflux.

Contraindications

^99mTc-colloid or ^99mTc-DTPA mixed with:

Radiopharmaceuticals

1. Adults and older children: 150–300 ml orange juice acidified with an equal volume of 0.1 M hydrochloric acid.

2. Infants and young children: normal milk feed.

Typical adult dose is 10–20 MBq, max. 40 MBq (0.9 mSv ED).

Equipment

1. Gamma-camera

2. Low-energy general purpose collimator

3. Abdominal binder for compression test.

Patient preparation

Nil by mouth for 4–6 h. Infants may be studied at normal feed times.

Technique

Physiological test ¹ – adults and older children

1. The liquid containing the tracer is given and washed down with unlabelled liquid to clear residual activity from the oesophagus.

2. The patient lies semi-recumbent with the camera centred over the stomach and lower oesophagus.

3. Dynamic imaging is commenced with 5-s 64×64 frames for 30–60 min.

Milk scan ¹ – infants and younger children

1. The milk feed is divided into two parts and one mixed with the tracer.

2. The radiolabelled milk is given and washed down with the remaining unlabelled milk.

3. After eructation, the child is placed either supine or prone, according to natural behaviour (although reflux appears to occur more readily in the supine position), with the camera anterior over stomach and oesophagus.

4. Dynamic imaging is commenced with 5-s 64×64 frames for 30–60 min.

5. If pulmonary aspiration of feed is suspected, later imaging at 4 h may be performed. The test is specific but not very sensitive for this purpose.

Provocation with abdominal compression ² – adults and older children

1. The abdominal binder is placed around the upper abdomen.

2. The radiolabelled liquid is given as above.

3. The patient lies supine with the camera centred over the stomach and lower oesophagus.

4. A 30-s image is taken.

5. The pressure in the binder is increased in steps of 20 mmHg up to 100 mmHg, being maintained at each step for 30 s while an image is taken.

6. The test is terminated as soon as significant reflux is seen.

Analysis

1. For dynamic studies, regions are drawn round the stomach and lower, middle and upper oesophagus.

2. Time–activity curves of these regions are produced, from which may be calculated the size, extent, frequency and duration of any reflux episodes.

Additional techniques

Oesophageal transit

The reflux study may be combined with a bolus transport investigation by fast-frame (0.2–0.5 s) dynamic imaging during swallowing and the generation of a functional compressed image incorporating information from each frame.

Aftercare

Complications

1 Guillet J., Basse-Cathalinat B., Christophe E., et al. Routine studies of swallowed radionuclide transit in paediatrics: experience with 400 patients. Eur. J. Nucl. Med.. 1984;9:86-90.

2 Martins J.C., Isaacs P.E., Sladen G.E., et al. Gastro-oesophageal reflux scintigraphy compared with pH probe monitoring. Nucl. Med. Commun.. 1984;5:201-204.

Heyman S. Paediatric gastrointestinal motility studies. Semin. Nucl. Med.. 1995;25:339-347.

Kjellén G., Brudin L., Håkansson H.O. Is scintigraphy of value in the diagnosis of gastro-oesophageal reflux disease? Scand. J. Gastroenterol.. 1991;26:425-430.

Radionuclide Gastric-Emptying Study

Indications

1. Investigation of symptoms suggestive of gastroparesis

2. Before or after gastric surgery

3. Investigation of the effects of gastric motility-altering drugs.

Contraindications

High probability of vomiting.

Radiopharmaceuticals

Many radiolabelled meals have been designed for gastric-emptying studies, but as yet no standard has emerged. Emptying rate measured by radiolabelling is influenced by many factors, for example meal bulk, fat content, calorie content, patient position during imaging and labelling stability in vivo. For this reason, so-called ‘normal’ emptying times need to be taken in the context of the particular meal and protocol used to generate them. It is important that the meal used is physiological and reproducible. For centres new to the technique it is better to use a meal for which published data exist, rather than create yet another formulation with inherently different behaviour.

Both liquid and solid studies may be performed, separately or simultaneously, as a dual isotope study. Liquids have generally shorter emptying times than solids, and tend to follow an exponential emptying pattern. Solids tend to empty linearly after a lag phase. Prolonged solid emptying is highly correlated with prolonged liquid emptying, and there is debate, therefore, as to whether both studies are routinely necessary.¹ Examples of meals used are:

1. Liquid meal: Max. 12 MBq ^99mTc-tin colloid (0.3 mSv ED) mixed with 200 ml orange juice, or with milk or formula feed for infants.

2. Solid meal: Scrambled egg prepared with max. 12 MBq ^99mTc-colloid (0.3 mSv ED) or ^99mTc-DTPA. Bulk is made up with other non-labelled foods such as bread and milk.

3. Dual isotope combined liquid and solid meal:

a Liquid: 12 MBq ^99mTc-colloid (0.3 mSv ED) mixed with 200 ml orange juice.

b Solid: 2 MBq ¹¹¹In-labelled resin beads (0.7 mSv ED) incorporated into a pancake containing 27 g fat, 18 g protein, 625 calories. Bulk is made up with other non-labelled foods. Only 2 MBq of ¹¹¹In is suggested (ARSAC max. is 12 MBq, 4 mSv ED) in order to minimize the downscatter into the ^99mTc energy window.

Equipment

1. Gamma-camera, preferably dual-headed

2. Low-energy general purpose collimator for ^99mTc, medium energy for ¹¹¹In/^99mTc.

Patient preparation

1. Nil by mouth for 8 h

2. No smoking or alcohol from midnight before test

3. Where practical, stop medications affecting gastric motility such as dopaminergic agonists (e.g. metoclopramide, domperidone), cholinergic agonists (e.g. bethanechol), tricyclic antidepressants and anticholinergics for 24 h or more prior to the study, depending upon their biological half-life.

Technique

Imaging from a single projection can cause significant errors due to movement of the meal anteriorly as it transfers to the antrum, thereby altering the amount of tissue attenuation of gamma-photons. The problem is likely to be exacerbated in obese patients. This can largely be overcome by taking pairs of opposing views and calculating the geometric, mean stomach activity in each pair:

1. The patient ingests the meal as quickly as they comfortably can. (If dumping syndrome is suspected, the meal should be eaten in front of the camera with a fast-frame dynamic acquisition running, or the dumping episode may be missed.)

2. The patient is positioned standing.

3. Every 5 min a pair of 1-min anterior and posterior 128×128 images is obtained.

4. The patient sits and relaxes between images.

5. A liquid study should be continued for up to 60 min and a solid study for up to 90 min. If it can be seen that the majority of the meal has emptied inside this time, the study may be terminated.

6. If emptying is very slow, later pairs of images may be acquired at intervals of 30–60 min.

Analysis

1. Stomach region of interest is drawn.

2. Stomach time-activity curve is produced, using geometric mean if anterior and posterior imaging performed.

3. Half-emptying time is calculated.

4. Other parameters may be calculated, e.g. lag-phase duration for solid studies, or percentage left in the stomach at various time points.

Additional techniques

1. The small-bowel transit time (SBTT) can be ascertained by continuing imaging at intervals until the caecum is seen. Since the position of the caecum is often not obvious and may be overlain by small bowel, a 12–24 h image can be useful to determine the position of the large bowel.

2. Frequency analysis of fast dynamic scans (1-s frame time) can be used to characterize antral contraction patterns.²

Aftercare

Complications

1 Siegel J.A., Krevsky B., Maurer A.H., et al. Scintigraphic evaluation of gastric emptying: are radiolabelled solids necessary? Clin. Nucl. Med.. 1989;14:40-46.

2 Urbain J-L., Charkes N.D. Recent advances in gastric emptying scintigraphy. Semin. Nucl. Med.. 1995;25:318-325.

Maughan R.J., Leiper J.B. Methods for the assessment of gastric emptying in humans: an overview. Diabet. Med.. 1996;13(suppl 5):S6-10.

Radionuclide Meckel’s Diverticulum Scan

Indications

Detection of a Meckel’s diverticulum as a cause for gastrointestinal bleeding, obstruction or abdominal pain.

Contraindications

1. Barium study in previous 2–3 days (barium causes significant attenuation of gamma photons and may mask a diverticulum).

2. In-vivo, labelled red blood cell study in previous few days (due to likelihood of pertechnetate adhering to red cells).

3. Precautions and contraindications to any pre-administered drugs should be observed.

Radiopharmaceuticals

^99mTc-pertechnetate, 200 MBq typical (2.5 mSv ED), 400 MBq max (5 mSv ED). Injected ^99mTc-pertechnetate localizes in ectopic gastric mucosa within a diverticulum.

Equipment

1. Gamma-camera

2. Low-energy general purpose collimator.

Patient preparation

1. Nil by mouth for 6 h, unless emergency

2. It may be possible to enhance detection by prior administration of drugs, e.g. pentagastrin, cimetidine or ranitidine aimed at increasing the uptake of ^99mTc-pertechnetate into gastric mucosa and inhibiting its release into the lumen of the stomach and progression into the bowel.

Technique

1. The bladder is emptied – a full bladder may obscure the diverticulum

2. The patient lies supine with the camera over the abdomen and pelvis. The stomach must be included in the field of view because diagnosis is dependent on demonstrating uptake of radionuclide in the diverticulum concurrent with uptake by gastric mucosa

3. Pertechnetate is administered i.v.

4. Dynamic imaging

5. Posterior and lateral images as required.

Aftercare

Pre-administered drug sensitivity and side-effects.

Complications