Urinary tract

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Chapter 5 Urinary tract

Methods of imaging the urinary tract

1. Plain films
2. Excretion urography
3. Ultrasound (US)
4. Computed tomography (CT) – CT KUB, CT urography, ‘staging CT’, CT angiography
5. Magnetic resonance imaging (MRI) – MR urography, MR prostate, MR bladder, MR angiography
6. Micturating cystourethrography
7. Ascending urethrography
8. Retrograde pyeloureterography
9. Percutaneous renal puncture – nephrostomy, biopsy, antegrade pyelography, cyst puncture
10. Arteriography
11. Venography – including renal vein sampling
12. Conduitogram
13. Radionuclide imaging:

a Static
b Dynamic
c Radionuclide cystography – direct and indirect.

Further reading

Akin O., Hricak H. Imaging of prostate cancer. Radiol. Clin. North Am.. 2007;45(1):207-222.

Zhang J., Gerst S., Lefkowitz R.A., et al. Imaging of bladder cancer. Radiol. Clin. North Am.. 2007;45(1):183-205.

Zhang J., Lefkowitz R.A., Bach A. Imaging of kidney cancer. Radiol. Clin. North Am.. 2007;45(1):119-147.

Excretion Urography

Also known as intravenous urography (IVU). The technique is much less frequently used than in the past, being largely replaced by CT, MRI or US.

Indications

1. Haematuria
2. Renal colic
3. Recurrent urinary tract infection
4. Suspected urinary tract pathology.

Contraindications

See Chapter 2 – general contraindications to intravenous (i.v.) water-soluble contrast media and ionizing radiation. Pre-medication with steroids (see Chapter 2) may be considered but information regarding the renal size, presence of calcification and pelvicalyceal systems may be gained by using a combination of plain film, US, unenhanced CT and MRI.

Contrast medium

Low osmolar contrast material (LOCM) 370

Adult dose

50–100 ml

Paediatric dose

1 ml kg−1

Patient preparation

1. No food for 5 h prior to the examination. Dehydration is not necessary and does not improve image quality.
2. Patients should, preferably, be ambulant for 2 h prior to the examination to reduce bowel gas.
3. The routine administration of bowel preparation fails to improve the diagnostic quality of the examination and its use makes the examination more unpleasant for the patient.

Preliminary film

1. Supine, full-length anterior posterior (AP) of the abdomen, in inspiration. The lower border of the cassette is at the level of the symphysis pubis and the X-ray beam is centred in the mid-line at the level of the iliac crests.

If necessary, the position of overlying opacities may be further determined by:

a supine AP of the renal areas, in expiration. The X-ray beam is centred in the mid-line at the level of the lower costal margin

or

b 35° posterior oblique views

or

c tomography of the kidneys at the level of a third of the AP diameter of the patient (approx. 8–11 cm). The optimal angle of swing is 25–40°.

The examination should not proceed further until these films have been reviewed by the radiologist and deemed satisfactory.

Technique

Venous access via the median antecubital vein is the preferred injection site because flow is retarded in the cephalic vein as it pierces the clavipectoral fascia. The gauge of the cannula/needle should allow the injection to be given rapidly as a bolus to maximize the density of the nephrogram.

Upper arm or shoulder pain may be due to stasis of contrast medium in the vein. This is relieved by abduction of the arm.

Films

1. Immediate film. AP of the renal areas. This film is exposed 10–14 s after the injection (approximate arm-to-kidney time). It aims to show the nephrogram, i.e. the renal parenchyma opacified by contrast medium in the renal tubules.
2. 5-min film. AP of the renal areas. This film is taken to determine if excretion is symmetrical and is invaluable for assessing the need to modify technique, e.g. a further injection of contrast medium if there has been poor initial opacification.

A compression band is now applied around the patient’s abdomen and the balloon positioned midway between the anterior superior iliac spines, i.e. precisely over the ureters as they cross the pelvic brim. The aim is to produce better pelvicalyceal distension. Compression is contraindicated:

a after recent abdominal surgery
b after renal trauma
c if there is a large abdominal mass or aortic aneurysm
d when the 5-min film shows already distended calyces.

3. 10-min film. AP of the renal areas. There is usually adequate distension of the pelvicalyceal systems with opaque urine by this time. Tomography may be useful to improve visualization of the pelvicalyceal systems if these are obscured by bowel.
Compression is released when satisfactory demonstration of the pelvicalyceal system has been achieved.
4. Release film. Supine AP abdomen. This film is taken to show the whole urinary tract. If this film is satisfactory, the patient is asked to empty their bladder.
5. After micturition film. Based on the clinical findings and the radiological findings on the earlier films, this will be either a full-length abdominal film or a coned view of the bladder with the tube angled 15° caudad and centred 5 cm above the symphysis pubis. The aims of this film are to assess bladder emptying, to demonstrate a return to normal of dilated upper tracts with relief of bladder pressure, to aid the diagnosis of bladder tumours, to confirm ureterovesical junction calculi and, uncommonly, to demonstrate a urethral diverticulum in females.

Additional films

1. 35° posterior obliques of the kidneys, ureters or bladder
2. Tomography – when there are confusing overlying shadows
3. 30° caudad angulation of the tube for the renal area. This may throw a faecal laden transverse colon clear of the kidneys
4. Prone abdomen – may improve visualization of ureters by making them more dependent
5. Delayed films – may be necessary for up to 24 h after injection in obstructive uropathy.

ULTRASOUND OF THE URINARY TRACT IN ADULTS

Indications

1. Suspected renal mass lesion
2. Suspected renal parenchymal disease
3. Possible renal obstruction
4. Haematuria
5. Hypertension resistant to conventional medical treatment
6. Renal cystic disease
7. Renal size measurement
8. To facilitate accurate needle placement in interventional procedures
9. Prostatism
10. Bladder volume before and after micturition
11. Bladder tumour
12. Following renal transplant to assess the pelvicalyceal system and patency of vessels, and to investigate perirenal collections.

Contraindications

None.

Patient preparation

None – unless full bladder is required.

Equipment

3.5–5 MHz transducer. Contact gel. The choice of pre-set protocol and positioning of focal zones will depend upon the type of US machine.

Technique

1. Patient supine, right (RAO) and left anterior oblique (LAO) positions or prone for kidneys. The kidneys are scanned longitudinally and transversely. The right kidney may be scanned through the liver and posteriorly in the right loin. The left kidney is harder to visualize anteriorly unless the spleen is large, but can be visualized from the left loin.
2. The length of the kidney measured by US is smaller than that measured at excretion urography because there is no geometric magnification and no change in size related to contrast-induced osmotic diuresis. With US measurement, care must be taken to ensure that the true longitudinal diameter is scanned. The mean length of the normal adult right kidney is 10.7 cm and the left 11.1 cm (range 9–12 cm).
3. The bladder is scanned suprapubically in transverse and longitudinal planes. Measurements taken of three diameters before and after micturition enable an approximate volume to be calculated.
4. Colour flow and duplex Doppler may be used to examine the renal arteries and veins.
5. Renal transplants are usually located in the right or left iliac fossa. These usually lie fairly superficially. Attention should be paid to the pelvicalyceal system and renal vessels.

ULTRASOUND OF THE URINARY TRACT IN CHILDREN

The availability of high-resolution real-time US has revolutionized the investigation of paediatric renal disease. It demonstrates anatomy without the necessity for adequate renal function but, because it gives no functional information, it is the ideal complement to nuclear medicine imaging. It should be stressed that the technique is only as good as the effort put in to obtain the images.

Indications (after Lebowitz, 1985)1

1. Urinary tract infection – to document scarring, elicit signs of acute upper tract infection and to exclude an underlying structural abnormality.
2. An abdominal or pelvic mass. Ultrasonography will demonstrate the relationship of the mass to other organs, its possible site of origin and its characteristics, i.e. solid or cystic and the presence of calcification.
3. Renal failure – to differentiate medical from surgical causes.
4. Abnormal antenatal US – to confirm or refute an antenatal diagnosis of hydronephrosis or multicystic dysplasia. The role of US should be to help in the efficient planning of the postnatal management before infection occurs and plasma creatinine rises, rather than to provoke antenatal intervention. It must be remembered that, because urine output falls rapidly after birth when compared with in utero, US on day 1 may show considerably less pelvicalyceal dilatation than was observed on the antenatal scans. Further follow-up scans are mandatory.
5. Conditions associated with a high likelihood of renal abnormalities, e.g. imperforate anus and genital anomalies. The most frequently found abnormalities are a single or ectopic kidney.
6. Genetic conditions, such as Beckwith–Wiedemann, which predispose to >5% risk of developing Wilms’ tumour.2 US surveillance should be performed every 3–4 months.
7. Screening of family members for genetically linked renal diseases, e.g. dominant polycystic renal disease.
8. Periodic follow-up of kidneys which are at risk of deterioration, e.g. children with myelomeningocele or urinary diversion. Patients on chronic dialysis have a high incidence of acquired cystic disease and may develop adenomas or adenocarcinomas.
9. To assess the patency of the IVC and renal vein in patients with Wilms’ tumour.
10. To assess residual bladder volume.
11. To facilitate the accurate placement of needles for renal biopsy, antegrade pyelography, percutaneous nephrostomy, cyst aspiration and drainage of perinephric collections.

When assessing possible renal disease by ultrasonography, a number of normal ‘variants’ may be confused with disease. These include increased parenchymal echogenicity in the neonatal period, echo-poor papillae which may mimic dilated calyces and persistent fetal lobulation, hepatic and splenic impressions, and parenchymal junctional lines, which may mimic scarring.

Equipment

3.5–7.5 MHz transducer – dependent on age.

Patient preparation

Full bladder. Patients with an indwelling catheter should have this clamped 1 h before the examination is scheduled.

Technique

1. Begin by examining the bladder, because contact of the transducer and jelly against the skin may promote bladder emptying. You may have only one chance to image the bladder.
2. It may be necessary to examine uncooperative children while they sit on a carer’s lap. Otherwise the technique is as for adults.
3. If possible the kidneys are examined in full inspiration or with the child being asked to ‘push the tummy out’.

References

1 Lebowitz R.L. Pediatric uroradiology. Pediatr. Clin. North Am.. 1985;32:1353-1362.

2 Scott R.H., Walker L., Olsen Ø.E., et al. Surveillance for Wilms tumour in at-risk children: pragmatic recommendations for best practice. Arch. Dis. Child.. 2006;91:995-999.

Computed Tomography of the Urinary Tract

Indications

1. Renal colic/suspected renal stone disease
2. Suspected renal tumour
3. Suspected renal/perirenal collection
4. Loin mass
5. Staging and follow-up of renal, transitional cell or prostatic cancer. Local staging of prostatic cancer is performed using high-resolution MRI or endorectal US. Local staging of bladder cancer may be performed using MRI or CT
6. Investigation of obstructive uropathy
7. CT angiography may be used to assess renal vessels for suspected renal artery stenosis or arterio-venous fistula or malformation.

Technique

Computed tomography of kidneys, ureters and bladder

CT KUB (non-contrast enhanced CT of kidneys, ureters and bladder) is useful to determine the number and location of urinary tract calculi. It is used in some centres as the primary investigation of renal colic:

1. The patient lies in prone position on CT scanner table.
2. A scout view is obtained.
3. A low-radiation-dose technique is used to scan from the top of the kidneys to include the bladder base with a slice thickness of 5 mm or less, as determined by CT scanner. An i.v. contrast is not given.

CT urogram

This technique uses a combination of unenhanced, nephrographic and delayed scans following i.v. contrast to allow examination of renal parenchyma and collecting systems. This is one suggested method:

1. Venous access is obtained
2. Patient lies in supine position
3. Scanogram is obtained
4. Initial low-dose unenhanced scans of urinary tract if renal stone disease is suspected
5. Low osmolar contrast material (LOCM) 300 (100–150 ml) is given as bolus intravenously
6. 3 mm or less thickness scans are obtained from diaphragm to lower poles of kidneys during nephrographic/parenchymal enhancement phase (100–120 s following start of bolus injection)
7. If possible, the patient is then encouraged to walk freely within the scan room or department for a few minutes
8. 3 mm or less thickness scans are obtained from upper pole of kidneys to bladder base 10 min after contrast injection, to examine collecting systems and ureters
9. Reconstructions can then be made of the pelvi-calyceal systems and ureters in appropriate planes.

‘Staging CT’

This technique is used to stage and follow-up known renal-tract malignancy or to investigate more non-specific signs attributed to the renal tract. Examination of the thorax in addition to the abdomen and pelvis is often appropriate in conditions where pulmonary metastatic disease or mediastinal nodal spread is a possibility:

1. Venous access is obtained
2. Patient lies supine on the scanner
3. Scanogram of chest, abdomen and pelvis as appropriate
4. 100 ml i.v. LOCM given
5. Scans obtained approximately 70 s after i.v. contrast at 5 mm slice thickness or less, depending upon scanner. Arterial phase scans of the liver (20–25 s after i.v. contrast) may be appropriate in those patients with suspected metastatic renal cancer who may have hypervascular liver metastases.

CT angiography

Indications

1. Renal artery stenosis
2. Renal artery aneurysm, arteriovenous malformation, dissection or thrombosis
3. Delineation of vascular anatomy prior to laparoscopic surgery, e.g. nephrectomy
4. Renal vein thrombosis or renal vein/IVC tumour.

Technique

1. No oral iodinated contrast used.
2. Localize the renal hilum accurately using non-enhanced images.
3. Use narrow collimation (1–3 mm).
4. 100–150 ml i.v. contrast medium (LOCM 300) injected at 3–4 ml s−1.
5. Use of bolus triggering devices is recommended to ensure appropriate timing. Otherwise scans are initiated after a preset empiric delay of 20–25 s from start of contrast material injection.
6. Examination of the inferior vena cava requires scanning at a later time (90–120 s delay).

Further reading

Kluner C., Hein P.A., Gralla O., et al. Does ultra-low-dose CT with a radiation dose equivalent to that of KUB suffice to detect renal and ureteral calculi? J. Comput. Assist. Tomogr.. 2006;30(1):44-50.

Van Der Molen A.J., Cowan N.C., Mueller-Lisse U.G., et alCT Urography Working Group of the European Society of Urogenital Radiology (ESUR). CT urography: definition, indications and techniques. A guideline for clinical practice. Eur. Radiol.. 2008;18(1):4-17.

Magnetic Resonance Imaging of the Urinary Tract

Indications

1. Local staging of prostatic cancer
2. Local staging of bladder cancer
3. Staging of pelvic lymph nodes
4. Suspected renal mass
5. Screening of patients with von Hippel–Lindau disease or their relatives
6. Suspected renal obstruction in patients with poor renal function
7. MR angiography: of potential living related donors, suspected renal artery stenosis.

Technique

Technique will be tailored to the clinical question with MR urography used to investigate the renal tract as a whole. MRI of the abdomen and pelvis can be obtained to assess retroperitoneal adenopathy as part of the staging investigations for patients with bladder and prostate cancer, but CT is often used for this purpose with MRI used for local staging.

MAGNETIC RESONANCE UROGRAPHY

The two most common MR urographic techniques are:

1. static (fluid-filled) urography using heavily T2-weighted MRI techniques to display fluid-filled structures in a similar fashion to magnetic resonance cholangiopancreatography (MRCP) (see Chapter 4)
2. excretory MR urography using T1-weighted gadolinium enhanced scans.

In and out of phase T1-weighted gradient echo scans can be performed to characterize adrenal mass lesions or identify lipid within angiomyolipomas and clear cell carcinoma of the kidney.

Indications

1. To demonstrate the collecting system/determine level of obstruction in a poorly functioning/obstructed kidney
2. Urinary tract obstruction unrelated to urolithiasis. Suspected renal colic from calculus is probably better imaged with CT KUB/ IVU
3. Congenital anomalies
4. Potential renal transplant donors (combined with MR angiography and standard MR imaging of renal parenchyma).

Technique

1. The patient is supine with an empty bladder.
2. Scout views are obtained.
3. Static MR urography may be performed prior to excretory urography.

Thick-slab, single-shot, fast-spin echo or a similar thin-section technique, e.g. half-Fourier rapid acquisition with relaxation enhancement; single-shot, fast-spin echo; single-shot, turbo-spin echo. Three-dimensional respiratory triggered sequences may be used to obtain thin-section data sets that may be further manipulated.

The use of hydration, compression or diuretics may be used to improve visualization of non-dilated collecting systems.

4. Diuretic administration (e.g. 5–10 mg furosemide for adults) given prior to i.v. contrast, can improve the distension of the collecting system and dilute the contrast within the collecting system improving the quality. This may be omitted in patients shown to have obstruction on static MR urography.
5. Excretory MR urography uses pre- and post-contrast scans in the same position. A gadolinium-based contrast agent is administered i.v. using a dose of 0.1 mmol gadolinium/kg body weight. The collecting systems are imaged during the excretory phase using a breath-hold, three-dimensional gradient echo, T1-weighted sequence. Nephrographic phase images may be obtained to image renal parenchyma. Fat suppression will improve the conspicuity of the ureters. Sequences, such as VIBE (volumetric interpolated breath-hold examination) or LAVA (liver acquisition with volume acceleration) can be used. T2* effects from a sufficient concentration of contrast agent may reduce the signal intensity of urine and potentially obscure small masses within the collecting system. This can be overcome, to a certain extent, by using lower concentration of i.v. contrast (e.g. 0.01 mmol kg) but this technique will not distend the collecting system and may compromise soft-tissue imaging. The optimum concentration of contrast has not been established as yet.

Further reading

Leyendecker J.R., Barnes C.E., Zagoria R.J. MR urography: techniques and clinical applications. Radiographics. 2008;28(1):23-46. discussion 4647

Nikken J.J., Krestin G.P. MRI of the kidney – state of the art. Eur. Radiol.. 2007;17(11):2780-2793.

Takahashi N., Kawashima A., Glockner J.F., et al. Small (<2-cm) upper-tract urothelial carcinoma: evaluation with gadolinium-enhanced three-dimensional spoiled gradient-recalled echo MR urography. Radiology. 2008;247(2):451-457.

Magnetic Resonance Imaging of the Prostate

Technique

1. Patient supine
2. Scout views
3. High-resolution T2-weighted spin echo (SE) scans in axial sagittal and coronal plane orthogonal to the prostate
4. T2 and /or T1-weighted scans are performed to evaluate pelvic nodes if these have not been staged with CT.

Further reading

Ramchandai P. Prostate imaging. Radiol. Clin. North Am.. 44(5), 2006. (The entire issue is dedicated to prostate imaging.)

Magnetic Resonance Imaging of the Bladder

Technique

1. Patient supine with bladder not emptied before scan and any urinary catheter clamped
2. Scout views
3. High-resolution T2-weighted SE scans in axial sagittal and coronal plane orthogonal to the bladder
4. T2 and /or T1-weighted scans are performed to evaluate pelvic/abdominal nodes if these have not been staged with CT.

MAGNETIC RESONANCE RENAL ANGIOGRAPHY

TECHNIQUE

Three-dimensional spoiled gradient echo sequences are performed before and following i.v. injection (2 ml/s) of 0.1 mmol/kg gadolinium. A saline flush (20 ml) at the same rate is given. Accurate timing of injection is determined by bolus tracking with ROI (region of interest) positioned over abdominal aorta. The scan is triggered when signal intensity at the ROI reaches a preset value.

Further reading

Soulez G., Pasowicz M., Benea G., et al. Renal artery stenosis evaluation: diagnostic performance of gadobenate dimeglumine-enhanced MR angiography – comparison with DSA. Radiology. 2008;247(1):273-285.

Willmann J.K., Wildermuth S., Pfammatter T., et al. Aortoiliac and renal arteries: prospective intraindividual comparison of contrast-enhanced three-dimensional MR angiography and multi-detector row CT angiography. Radiology. 2003;226(3):798-811.

Micturating Cystourethrography

Indications

1. Vesicoureteric reflux
2. Study of the urethra during micturition
3. Abnormalities of the bladder
4. Stress incontinence.

Contraindications

Acute urinary tract infection.

Contrast medium

High osmolar contrast material (HOCM) or LOCM 150.

Equipment

1. Fluoroscopy unit with spot film device and tilting table
2. Video recorder
3. Jaques or Foley catheter. In small infants a fine (5–7-F) feeding tube is adequate.

Patient preparation

The patient micturates prior to the examination.

Preliminary film

Coned view of the bladder, using the undercouch tube.

Technique

To demonstrate vesico-ureteric reflux

1. This indication is almost exclusively confined to children.
2. The patient lies supine on the X-ray table. Using aseptic technique a catheter, lubricated with a sterile gel containing a local anaesthetic and antiseptic, is introduced into the bladder. Residual urine is drained. Contrast medium is slowly dripped in and bladder filling is observed by intermittent fluoroscopy. It is important that initial filling is monitored by fluoroscopy in case the catheter is in the distal ureter (thereby mimicking vesico-ureteric reflux) or vagina. It is also important to look for a ureterocele at this stage, as it may be masked by contrast media when the bladder is full.
3. Any reflux is recorded on spot films.
4. The catheter should not be removed until the radiologist is convinced that the patient will micturate or until no more contrast medium will drip into the bladder. The examination is expedited if the catheter remains in situ until micturition commences and then is quickly withdrawn. Small feeding tubes do not obstruct micturition.
5. Older children and adults are given a urine receiver but smaller children should be allowed to micturate onto absorbent pads on which they can lie. Children can lie on the table but adults will probably find it easier to micturate while standing erect.
6. In infants and children with a neuropathic bladder, micturition may be accomplished by suprapubic pressure.
7. Spot films are taken during micturition and any reflux recorded. A video recording may be useful. The lower ureter is best seen in the anterior oblique position of that side. Boys should micturate in an oblique or lateral projection, so that spot films can be taken of the entire urethra.
8. Finally, a full-length view of the abdomen is taken to demonstrate any reflux of contrast medium that might have occurred unnoticed into the kidneys and to record the post-micturition residue.

To demonstrate a vesico-vaginal or recto-vesical fistula

As above, but films are taken in the lateral position.

To demonstrate stress incontinence

Initially the technique is as for demonstrating vesico-ureteric reflux. However, the catheter is left in situ until the patient is in the erect position.

Films

These should include sacrum and symphysis pubis because bony landmarks are used to assess bladder neck descent:

1. Lateral bladder
2. Lateral bladder, straining – the catheter is then removed
3. Lateral bladder during micturition.

Aftercare

1. No special aftercare is necessary, but patients and parents of children should be warned that dysuria, possibly leading to retention of urine, may rarely be experienced. In such cases a simple analgesic is helpful and children may be helped by allowing them to micturate in a warm bath.
2. Most children will already be receiving antibiotics for their recent urinary tract infection. However, if reflux is demonstrated in a child who is not receiving antibiotics, they should be prescribed.

Complications

Due to the contrast medium

1. Adverse reactions may result from absorption of contrast medium by the bladder mucosa. The risk is small when compared with excretion urography.
2. Contrast medium-induced cystitis.

Due to the technique

1. Acute urinary tract infection
2. Catheter trauma – may produce dysuria, frequency, haematuria and urinary retention
3. Complications of bladder filling, e.g. perforation from overdistension – prevented by using a non-retaining catheter, e.g. Jaques
4. Catheterization of vagina or an ectopic ureteral orifice
5. Retention of a Foley catheter.

ASCENDING URETHROGRAPHY IN THE MALE

Indications

1. Strictures
2. Urethral tears
3. Congenital abnormalities
4. Periurethral or prostatic abscess
5. Fistulae or false passages.

Contraindications

1. Acute urinary tract infection
2. Recent instrumentation.

Contrast medium

HOCM or LOCM 200–300, 20 ml. Pre-warming the contrast medium will help reduce the incidence of spasm of the external sphincter.

Equipment

1. Tilting radiography table with fluoroscopy unit and spot film device
2. Foley catheter 8-F.

Patient preparation

Consent.

Preliminary film

Coned supine postero-anterior (PA) of bladder base and urethra.

Technique

1. The patient lies supine on the X-ray table.
2. Using aseptic technique the tip of the catheter is inserted so that the balloon lies in the fossa navicularis and its balloon is inflated with 1–2 ml of water. Contrast medium is injected under fluoroscopic control and films are taken in the following positions:

a 30° LAO, with right leg abducted and knee flexed
b supine PA
c 30° RAO, with left leg abducted and knee flexed.

3. Ascending urethrography should be followed by micturating cystourethrography or excretory micturating cystourethrography to demonstrate the proximal urethra. Occasionally, a urethral fistula or periurethral abscess is seen only on the voiding examination; reflux of contrast medium into dilated prostatic ducts is also better seen during micturition.

Aftercare

None.

Complications

Due to the contrast medium

Adverse reactions are rare.

Due to the technique

1. Acute urinary tract infection
2. Urethral trauma
3. Intravasation of contrast medium, especially if excessive pressure is used to overcome a stricture.

Further reading

McCallum R.W. The adult male urethra: normal anatomy, pathology and method of urethrography. Radiol. Clin. North Am.. 1979;17(2):227-244.

Retrograde Pyeloureterography

Indications

1. Demonstration of the site, length, lower limit and, if possible, the nature of an obstructive lesion.
2. Demonstration of the pelvicalyceal system after an unsatisfactory excretion urogram. Seldom necessary with modern imaging methods.

Contraindications

Acute urinary tract infection.

Contrast medium

HOCM or LOCM 150–200, i.e. not too dense to obscure small lesions, 10 ml.

Equipment

Fluoroscopy unit.

Patient preparation

As for surgery.

Preliminary film

Full-length supine anterior posterior (AP) abdomen when the examination is performed in the X-ray department.

Technique

In the operating theatre

The surgeon catheterizes the ureter via a cystoscope and advances the ureteric catheter to the desired level. Contrast medium is injected under fluoroscopic control and spot films are exposed.

In the X-ray department

1. With ureteric catheter(s) in situ, the patient is transferred from the operating theatre to the X-ray department.
2. Urine is aspirated and, under fluoroscopic control, contrast medium is slowly injected. About 3–5 ml are usually enough to fill the pelvis but the injection should be terminated before this if the patient complains of pain or fullness in the loin.
3. If there is pelviureteric junction obstruction, the contrast medium in the pelvis is aspirated. The films are examined and, if satisfactory, the catheter is withdrawn, first to 10 cm below the renal pelvis, and then to lie just above the ureteric orifice.

About 2 ml of contrast medium are injected at each of these levels and films taken.

Films

Using the undercouch tube:

1. supine PA of the ureter
2. both 35° anterior obliques of the ureter.

N.B. The catheter may be left in the renal pelvis to drain a pelviureteric obstruction. In this case withdrawal ureterograms are not possible.

Aftercare

1. Post-anaesthetic observations
2. Prophylactic antibiotics may be used.

Complications

Due to the anaesthetic

Complications of general anaesthesia.

Due to the contrast medium

1. Contrast medium can be absorbed from the intact renal pelvis, giving rise to adverse reactions. However, the risks are much less than with excretion urography.
2. Chemical pyelitis – if there is stasis of contrast medium.
3. Extravasation due to overdistension of the pelvis. This is usually asymptomatic, but may result in pain, fever and rigors.

Due to the technique

1. Introduction of infection.
2. Mucosal damage to the ureter.
3. Perforation of the ureter or pelvis by the catheter.

PERCUTANEOUS NEPHROSTOMY

The introduction of a drainage catheter into the collecting system of the kidney.

Indications

1. Obstructive uropathy
2. Pyonephrosis
3. Prior to percutaneous nephrolithotomy
4. Ureteric fistulae; external drainage may allow closure.

Contraindications

Uncontrolled bleeding diathesis.

Contrast medium

As for percutaneous renal puncture.

Equipment

1. Puncturing needle: coaxial needle/catheter set or sheathed 18G needle.
2. Drainage catheter: at least 7-F pigtail with multiple side holes.
3. Guidewires: conventional angiographic ± stiff wire.
4. US and/or fluoroscopy.

Patient preparation

1. Fasting for 4 h
2. Premedication
3. Prophylactic antibiotic
4. Surgical backup in view of clinical workup, possible complications and further management.

Technique

Patient position

With the patient lying in the prone position on the fluoroscopic table, a foam pad or non-opaque pillow is placed under the abdomen so that the kidney lies in a fixed posterior position. An oblique position with the side to be punctured raised is often used.

Identifying the collecting system

1. US may be used to identify the renal collecting system for antegrade pyelography and to determine the plane of definitive puncture of the collecting system. Freehand or with a biopsy needle attachment, US may be used to guide the puncturing needle into the collecting system. US guidance is the most common method for localizing the kidney and guiding the initial needle puncture.
2. Excretion urography, if adequate residual function.
3. Antegrade pyelography.

Site/plane of puncture

A point on the posterior axillary line is chosen below the twelfth rib. Having identified the mid/lower pole calyces with US or contrast, the plane of puncture is determined. This will be via the soft tissues and renal parenchyma, so that vessels around the renal pelvis will be avoided and the drainage catheter will gain some purchase on the renal parenchyma. The drainage catheter is also more comfortable for the patient in this position, and is less likely to be kinked when he/she lies supine.

Techniques of puncture, catheterization

The skin and soft tissues are infiltrated with local anaesthetic using a spinal needle. Puncture may then be made using one of the following systems (depending on preference):

1. An 18G sheathed needle, a cyst puncture or a Longdwell needle or Kellett needle, in conjunction with the Seldinger technique for catheterization. Upon successful puncture a J guidewire is inserted and coiled within the collecting system; the sheath is then pushed over the wire, which may be exchanged for a stiffer wire. If possible the guidewire is manipulated into the ureter. Dilatation is then performed to 1-F greater than the size of the drainage catheter, which is then inserted. During all manipulation, care must be taken not to kink the guidewire within the soft tissues. A substantial amount of guidewire should be maintained within the collecting system so that position is not lost and if kinking does occur, then the kinked portion of the wire can be withdrawn outside the skin.
2. Coaxial needle puncture systems, e.g. Neff or Accustik, using a 22/21G puncturing needle that takes a special 0.018 guidewire. This affords a single puncture with a fine needle, with insertion of a 3-part coaxial system to allow insertion of 0.035 guidewire and then proceed as in 1 above.
3. The trocar-cannula system, in which direct puncture of the collecting system is made with the drainage catheter already assembled over a trocar. On removal of the trocar the drainage catheter is pushed further into the collecting system.

Having successfully introduced a catheter, the latter is securely fixed to the skin and drainage commenced.

Aftercare

1. Bed rest for 6 h
2. Pulse, blood pressure and temperature half-hourly for 6 h
3. Urine cultures and sensitivity.

Complications

1. Septicaemia
2. Haemorrhage
3. Perforation of the collecting system with urine leak
4. Unsuccessful drainage
5. Later catheter dislodgement.

PERCUTANEOUS RENAL PUNCTURE AND BIOPSY

Indications

1. Diagnostic biopsy: unexplained renal failure, mass, etc.
2. Renal cyst puncture to relieve local symptoms attributable to a cyst
3. Antegrade pyelography:

a When other less invasive imaging modalities fail to delineate the cause and/or level of an obstruction
b When retrograde pyelography is unsuccessful or not possible, e.g. internal ureteral diversion
c Prior to, or as part of percutaneous nephrostomy (see p. 150).

Contraindications

1. As for water-soluble contrast medium in the radiographic method (see tables 2.3 and 2.4)
2. Bleeding diathesis
3. The possibility of renal hydatid disease.

Contrast medium

US guidance is generally used for preliminary visualization of the kidneys:

1. To outline the pelvicalyceal system or renal cyst by direct injection into the collecting system – any HOCM or LOCM 200. Volume is dependent on the size of the cyst or collecting system.
2. Indirect opacification of pelvicalyceal system by intravenous injection – LOCM 370 50 ml.

Equipment

1. Fluoroscopy unit, US machine or CT scanner
2. Overcouch tube
3. 22G needle, e.g. Chiba or Greenburg or core biopsy needle.

Patient preparation

1. Confirm normal blood coagulation
2. Nervous patients may need sedation; children will need general anaesthesia.

Preliminary film

Supine AP of the renal area for the radiographic method.

Technique

RENAL CYST PUNCTURE OR BIOPSY

Insertion of the needle can be controlled by either fluoroscopy after i.v. contrast, ultrasonography or CT:

1. The patient is placed in the prone position. A radiolucent pad is placed under the abdomen to limit anterior movement of the kidney.
2. The mass or cyst is located directly with US or CT or indirectly after opacification of the kidneys with i.v. contrast medium. The optimum site for puncture is marked on the skin.
3. The skin and subcutaneous tissues are infiltrated with 1% lidocaine.
4. The needle is passed directly into the lesion during suspended respiration. US or CT, or intermittent fluoroscopy, is used to monitor the path of the needle. The needle may be deflected around the cyst or mass and, if this happens, it will be necessary to advance it into the cyst or mass with a quick thrust.
5. For cyst puncture the stilette is removed. The cyst contents are aspirated and examined. For biopsy the biopsy needle is ‘fired’ with due consideration given to the length of throw of the needle biopsy system and adjacent structures.

If no fluid can be aspirated, the position of the needle can be confirmed with US or CT, and adjustment of position made. If the procedure is performed with fluoroscopy only, the needle is withdrawn until fluid is obtained. If that is unsuccessful, a further attempt at puncture is made.

ANTEGRADE PYELOGRAPHY

1. The needle is introduced as for cyst puncture but directed through the renal parenchyma into a minor calyx, posterior lower pole preferred. This reduces the risk of laceration of the pelvis and extravasation of urine.
2. Contrast medium is introduced until the level of obstruction is outlined.

Films

1. AP
2. both 35° posterior obliques.

This is generally followed by drainage with nephrostomy tube insertion if the system is found to be obstructed. This allows contrast medium to be removed from an obstructed pelvis to prevent the development of chemical pyelitis.

PERCUTANEOUS NEPHROLITHOTOMY

This is the removal of renal calculi through a nephrostomy tract. It is often reserved for large complicated calculi which are unsuitable for extracorporeal shock-wave lithotripsy.

Indications

1. Removal of renal calculi
2. Disintegration of large renal calculi.

Contraindications

Uncontrolled bleeding diathesis.

Contrast medium

As for percutaneous renal puncture.

Equipment

1. Puncturing needle (18G): Kellett (15–20 cm length) or equivalent
2. Guidewires, including hydrophilic (Terumo) and superstiff Amplatz
3. Tract dilating equipment; Teflon dilators (from 7–30-F), metal coaxial dilators or a special angioplasty type balloon catheter
4. US machine
5. Fluoroscopy facilities with rotating C arm if possible.

Patient preparation

1. Full discussion between radiologist/urologist concerning indications, etc.
2. Imaging (IVU, CT KUB, CTU) to demonstrate position of calculus and relationship to calyces
3. Admission on the day prior to the procedure – general anaesthetic is usually required
4. Coagulation screen
5. Two units of blood cross matched
6. Antibiotic cover
7. Premedication
8. Bladder catheterization, as large volumes of irrigation fluid will pass down the ureter during a prolonged procedure.

Technique

Patient position

As for a percutaneous nephrostomy, usually prone (see p. 150).

Methods of opacification of the collecting system

1. Retrograde ureteric catheterization; distension of the collecting system may be achieved. In addition, a retrograde occlusion balloon catheter in the ureter will prevent large fragments of stone passing down the ureter
2. Excretion urography
3. Antegrade pyelography; this also enables distension of the collecting system.

Puncture of the collecting system

A lower pole posterior calyx is ideally chosen if the calculus is situated in the renal pelvis. Otherwise the calyx in which the calculus is situated must be punctured. Special care must be taken if puncturing above the twelfth rib because of the risk of perforating the diaphragm and pleura. Puncture is in an oblique plane from the posterior axillary line through the renal parenchyma. Puncture of the selected calyx is made using a combination of US and a rotating C-arm fluoroscopic facility. On successful puncture a guidewire is inserted through the cannula and as much wire as possible is guided into the collecting system. The cannula is then exchanged for an angled catheter and the wire and catheter are manipulated into the distal ureter. At this stage full dilatation may be performed (single stage) or a nephrostomy tube left in situ with dilatation later (two-stage procedure).

Dilatation

This is carried out under general anaesthesia. It is performed using Teflon dilators from 7-F to 30-F, which are introduced over the guidewire. Alternatively, metal coaxial dilators or a special angioplasty balloon (10 cm long) are used. A sheath is inserted over the largest dilator or balloon through which the nephroscope is passed followed by removal of the calculus or disintegration.

Removal/disintegration

Removal of calculi of less than 1 cm is possible using a nephroscope and forceps. Larger calculi must be disintegrated using an ultrasonic or electrohydraulic disintegrator.

Aftercare

1. Usually determined by the anaesthetist/urologist
2. Plain radiograph of renal area to ensure that all calculi/fragments have been removed.

Complications

Immediate

1. Failure of access, dilatation or removal
2. Perforation of the renal pelvis on dilatation
3. Inadvertent access to renal vein and IVC
4. Haemorrhage. Less than 3% of procedures should require transfusion. Rarely, balloon tamponade of the tract or embolization may be required
5. Damage to surrounding structures, i.e. diaphragm, colon, spleen and liver
6. Problems related to the irrigating fluid, i.e. haemolysis.

Delayed

1. Pseudo-aneurysm of an intrarenal artery
2. Arterio-venous fistula.

RENAL ARTERIOGRAPHY

INDICATIONS

1. Renal artery stenosis prior to angioplasty or stent placement. Diagnostic arteriography has been replaced generally by MR or CT angiography (MRA or CTA (see p 140))
2. Renal tumour prior to embolization
3. Assessment of living related renal transplant donors – replaced generally by MRA
4. Haematuria particularly following trauma, including biopsy or other intervention when vascular trauma is possible. This may precede embolization.

Contrast medium

Selective renal artery injection

LOCM 300, 10 ml at 5 ml s−1, or by hand injection – consider use of Visipaque.

Flush aortic

LOCM 300/320, 45 ml at 15 ml s−1.

Equipment

1. Digital fluoroscopy unit
2. Pump injector
3. Catheters:

a Selective injection – Sidewinder or Cobra
b Flush aortic injection – pigtail 4-F.

Technique

Flush aortography

Femoral artery puncture. The catheter is placed proximal to the renal vessels (i.e. approx. T12) and AP and oblique runs are performed (the oblique run demonstrating the renal origins). Selective catheterization may overlook a stenosis at the origin of the renal artery or convert a stenosis into an occlusion, but is occasionally required to define the renal vasculature better.

CONDUITOGRAM

Indications

1. Suspected stricture at anastomosis of ureter and urinary conduit
2. Suspected narrowing of conduit.

Contrast

LOCM or HOCM 150

Technique

The conduit is catheterized using a sterile technique with a 18–20-F Foley catheter. The catheter balloon is inflated and minimal traction applied to the catheter to occlude the stoma. Contrast is gently hand injected under fluoroscopic control into the lumen of the conduit. The aim is to visualize the conduit and ureters.

STATIC RENAL SCINTIGRAPHY

Indications

1. Assessment of individual renal function
2. Investigation of urinary tract infections, particularly in children
3. Assessment of reflux nephropathy
4. Investigation of horseshoe, solitary or ectopic kidney
5. Space-occupying lesions.

99mTc-dimercaptosuccinic acid (DMSA) gives the best morphological images of any renal radiopharmaceutical and is used for assessment of scarring, and the most accurate assessment of differential renal function.

Contraindications

None.

Radiopharmaceuticals

99mTc-dimercaptosuccinic acid (DMSA), 80 MBq max (0.7 mSv ED), which is bound to plasma proteins and cleared by tubular absorption. DMSA is retained in the renal cortex, with an uptake of 40–65% of the injected dose within 2 h, and no significant excretion during the imaging period.

Equipment

1. Gamma-camera
2. Low-energy high-resolution collimator.

Patient preparation

None.

Technique

1. The radiopharmaceutical is administered i.v.
2. Images are acquired at any time 1–6 h later. Imaging in the first hour is to be avoided because of free 99mTc in the urine.

Images

1. Posterior, right (RPO) and left posterior oblique (LPO) views, 256×256 resolution, 300–500 000 counts
2. Zoomed or pinhole views may be useful in children.

Additional images

Anterior images may be taken in cases of suspected pelvic or horseshoe kidney and severe scoliosis, or if relative function is to be calculated by geometric mean method.

Analysis

1. Relative function is best calculated from the geometric mean of posterior and anterior computer images. A single posterior view is often used, but this requires assumptions about kidney depth, unless depth information is available to enable attenuation correction.
2. Absolute uptake can be estimated if required with additional information on patient and kidney size from lateral images.

Additional techniques

1. Single photon emission computed tomography (SPECT) – in the assessment of scarring and renal masses/‘pseudotumours’.
2. 99mTc-mercaptoacetyltriglycine (MAG-3) (max. 100 MBq, 0.7 mSv ED) may be considered as a possible alternative to DMSA; it gives inferior kidney visualization, but has the advantage of additional dynamic assessment of excretion in the same study and a lower radiation dose.
3. Fast dynamic frames with motion correction may be useful to reduce movement artefact, particularly in young children.

Aftercare

None.

Complications

None.

Further reading

Blaufox M.D. Procedures of choice in renal nuclear medicine. J. Nucl. Med.. 1991;32:1301-1309.

Cosgriff P.S. The urinary tract. In: Sharp P.F., Gemmell H.G., Murray A.D., editors. Practical Nuclear Medicine. 3rd edn. London: Springer-Verlag; 2005:205-229.

Hilson A.J. Functional renal imaging with nuclear medicine. Abdom. Imaging. 2003;28:176-179.

Dynamic Renal Scintigraphy

Indications1

1. Diagnosis of obstructed v non-obstructed dilatation
2. Diagnosis of renal artery stenosis2
3. Assessment of perfusion in acute native or transplant renal failure
4. Assessment of renal function following drainage procedures to the urinary tract
5. Demonstration of vesicoureteric reflux
6. Assessment of renal transplantation
7. Renal trauma.

Contraindications

None.

Radiopharmaceuticals

1. 99mTc-MAG-3 (mercaptoacetyltriglycine), 100 MBq max (0.7 mSv ED); (200 MBq max (1 mSv ED) for first-pass blood flow imaging). Highly protein-bound, so mainly cleared by tubular secretion (80%), but with around 20% glomerular filtration (mean normal clearance is approx. 370 ml min−1). Good-quality images due to fast clearance and greater kidney/background ratio than 99mTc-diethylene triamine pentacetic acid (DTPA), therefore better for poor renal function although more expensive. It is now the radiopharmaceutical of choice owing to its providing the best image quality.
2. 99mTc-DTPA, 150 MBq typical (1 mSv ED), 300 MBq max (2 mSv ED); (800 MBq max (5 mSv ED) for first-pass blood flow imaging). Cleared by glomerular filtration (mean normal clearance is approx. 120 ml min−1). There is a lower kidney/background ratio than MAG-3 or hippuran, and so a poorer image quality and noisier clearance curves. However, it is cheap and widely available.
3. 123I-orthoiodohippurate (hippuran), 20 MBq max (0.2 mSv ED). Almost entirely cleared by tubular secretion (mean normal clearance is approx. 500 ml min−1). High kidney/background ratio, but image quality is limited by the recommended maximum activity. For many years it has been the gold standard, but there is a high cost and limited availability due to 123I being a cyclotron product.

Equipment

1. Gamma-camera
2. Low-energy general purpose collimator.

Patient preparation

1. The patient should be well hydrated with around 500 ml of fluid immediately before administration of tracer
2. The bladder should be voided before injection.

Technique

1. The patient lies supine or sits reclining with their back against the camera.
2. The radiopharmaceutical is injected i.v. and image acquisition is started simultaneously.
3. Perform dynamic 128×128 acquisition with 10–15 s frames for 30–40 min. (For quantitative perfusion studies, e.g. in the transplanted kidney, 1–2-s frames over the 1st minute are acquired.)
4. If poor excretion is seen from one or both kidneys after 10–20 min, a diuretic (furosemide 40 mg) is administered slowly during imaging. Imaging should be continued for at least a further 15 min. Since maximum diuresis does not occur until 15 min after administration of furosemide, as an alternative it may be given 15 min before the radiopharmaceutical (the so-called ‘F − 15’ renogram), which can be useful after equivocal standard ‘F + 20’ studies.
5. If significant retention in the kidneys is apparent at the end of the imaging period, ask the patient to void and walk around for a minute, then take a further short image.

Films

1. All posterior
2. Hard copy: 2–5-min images for duration of study.

Analysis

The following information is produced using standard computer analysis:

1. Kidney time-activity (‘renogram’) curves, background-subtracted
2. Relative function figures.

Additional figures are sometimes calculated:

3. Perfusion index, especially in renal transplant assessment
4. Parenchymal and whole kidney transit times.

Additional techniques

1. Pre- and 1 h post-captopril (25–50 mg) study for diagnosis of renal artery stenosis (RAS). Radionuclide techniques have the advantage of showing the functional effect of a stenotic renal artery, as opposed to the anatomical demonstration as provided by angiographic techniques. This, therefore, helps identify patients in whom RAS is the cause of hypertension (renovascular). The patient should, ideally, stop diuretic and ACE inhibitor medication 3–5 days prior to the test.2
2. Indirect micturating cystography following renography to demonstrate vesicoureteric reflux. The bladder must not have been emptied and the kidneys should be reasonably clear of activity. Continuous dynamic 5-s images are acquired for 2 min before and up to 3 min after micturition, with generation of bladder and kidney time–activity curves.
3. Glomerular filtration rate (GFR) measurement and individual kidney GFR with DTPA studies by taking blood samples for counting. Similarly, effective renal plasma flow (ERPF) measurement with hippuran and a MAG-3 clearance index may be obtained.3
4. The images obtained with MAG-3 can be analysed for the presence of renal scarring and there is good correlation with the results obtained with DMSA (MAG-3 is 80% tubular secreted). DMSA remains the gold standard for cortical scarring because of the higher information density and ability to obtain multiple projections, but simultaneous renal clearance information can be gained with MAG-3.4
5. With the appropriate computer software and fast-frame acquisition, compressed images may be generated to demonstrate and quantify ureteric peristalsis and show reflux (best with MAG-3 or hippuran), although the technique has not yet found a widely accepted clinical role.

Aftercare

1. The patient is warned that the effects of diuresis may last a couple of hours. The patient may feel faint because of hypotension when standing erect at the end of the procedure.
2. After captopril administration, blood pressure monitoring should be carried out until back to normal.
3. Normal radiation safety precautions (see Chapter 1).

Complications

None, except after captopril, when care must be taken in patients with severe vascular disease to avoid hypotension and renal failure.

References

1 Woolfson R.G., Neild G.H. The true clinical significance of renography in nephro-urology. Eur. J. Nucl. Med.. 1997;24:557-570.

2 Taylor A., Nally J., Aurell M., et al. Consensus report on ACE inhibitor renography for detecting renovascular hypertension. J. Nucl. Med.. 1996;37:1876-1882.

3 Blaufox M.D., Aurell M., Bubeck B., et al. Report of the Radionuclides in Nephrourology Committee on renal clearance. J. Nucl. Med.. 1996;37:1883-1890.

.

4 Pickworth F.E., Vivian G.C., Franklin K., et al. 99Tcm-mercapto acetyl triglycine in paediatric renal tract disease. Br. J. Radiol.. 1992;65:21-29.

Further reading

Blaufox M.D. Procedures of choice in renal nuclear medicine. J. Nucl. Med.. 1991;32:1301-1309.

Cosgriff P.S. The urinary tract. In: Sharp P.F., Gemmell H.G., Murray A.D., editors. Practical Nuclear Medicine. 3rd edn. London: Springer-Verlag; 2005:205-229.

Hilson A.J. Functional renal imaging with nuclear medicine. Abdom. Imaging. 2003;28:176-179.

Direct Radionuclide Micturating Cystography

Indications

Vesicoureteric reflux.

Contraindications

Acute urinary tract infection.

Radiopharmaceuticals

99mTc-pertechnetate, 25 MBq max (0.3 mSv ED), administered into the bladder. Some pertechnetate is absorbed in the urinary tract and gastric activity may be seen.

Equipment

1. Gamma-camera
2. Low-energy general purpose collimator
3. Sterile saline infusion
4. Commode or plastic urinal
5. Screens for patient privacy.

Patient preparation

The patient micturates prior to the investigation.

Technique1

This examination is most frequently performed on children. Direct radionuclide cystography is considered to be at least as sensitive as conventional X-ray micturating cystourethrography (MCU) for the detection of vesicoureteric reflux.1 The examination enables continuous imaging and quantification of bladder, ureter and kidney activity to be performed and delivers a much smaller radiation dose than conventional cystography.

The technique requires catheterization and is similar to that for MCU except that:

1. 99mTc-pertechnetate is administered using one of two methods:

a Diluted in 500 ml sterile saline solution at body temperature and then infused into the bladder via the catheter
b Injected directly into the bladder via the catheter and continuously diluted with sterile saline solution infusion at body temperature.

2. During infusion, the patient lies supine with the gamma-camera posterior. Ensure that both of the kidneys and the ureters and bladder are in the field of view for all imaging. Dynamic image acquisition is performed for the duration of bladder filling at 5–10 s per frame with a 128×128 matrix size to demonstrate any reflux during this phase.
3. When the bladder is as full as tolerable, the infusion is stopped, but imaging is continued for a further 30 s. The patient then sits in front of the gamma-camera on a commode or child’s plastic urinal.
4. Dynamic imaging with 5–10-s frames is performed during micturition, continuing for 2–5 min after to evaluate bladder re-filling. If the patient is capable, the embarrassment of the procedure may be reduced by giving them a remote control to start computer acquisition just before they micturate, and leaving them in private.

Analysis

1. Time–activity curves are produced from regions over the bladder, kidneys and ureters.
2. If the voided volume is measured, residual and reflux volumes can be calculated.
3. Viewing the image set cinematically may aid identification of reflux.
4. Images may be summed to highlight any reflux episodes.

Additional techniques

1. If vesico-ureteric reflux is not seen during a single filling and voiding cycle, the sensitivity of the test may be improved by immediately repeating the procedure.2 The first voiding is performed, if possible, without removing the catheter, and re-filling is commenced shortly after.
2. Indirect radionuclide cystography may be performed after conventional radionuclide renography (see Dynamic renal scintigraphy, p. 160).
3. Intrarenal reflux has been investigated with delayed imaging of radiocolloid reflux at 5 and 20 h.

Aftercare

As for conventional cystography.

Complications

As for conventional cystography.

References

1 Mandell G.A., Eggli D.F., Gilday D.L., et al. Procedure guideline for radionuclide cystography in children. J. Nucl. Med.. 1997;38:1650-1654.

2 Fettich J.J., Kenda R.B. Cyclic direct radionuclide voiding cystography: increasing reliability in detecting vesicoureteral reflux in children. Pediatr. Radiol.. 1992;22:337-338.

Further reading

Treves S.T., Gelfand M., Willi U.V., et al. Vesicoureteric reflux and radionuclide cystography. In: Treves S.T., editor. Pediatric Nuclear Medicine. 2nd edn. New York: Springer-Verlag; 1995:411-429.

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