Normal intrahepatic ducts are visualized with modern scanners. Intrahepatic ducts are dilated if their diameter is more than 40% of the accompanying portal vein branch. There is normally acoustic enhancement posterior to dilated ducts but not portal veins. Dilated ducts have a beaded branching appearance.

Extrahepatic bile ducts

1. The patient is supine or in a lateral position.

2. The upper common duct is demonstrated on a longitudinal oblique, subcostal or intercostal scan running anterior to the portal vein. The right hepatic artery is often seen crossing transversely between the two.

3. The common duct may be followed downwards along its length through the head of the pancreas to the ampulla and, when visualized, transverse scans should also be performed to improve detection of intraduct stones. However, gas in the duodenum often impedes the view of the lower duct.

The segment of bile duct proximal to the junction with the cystic duct (the common hepatic duct) is 4 mm or less in a normal adult; 5 mm is borderline and 6 mm is considered dilated. The lower bile duct (common bile duct) is normally 6 mm or less. Distinction of the common hepatic duct from the common bile duct depends on identification of the junction with the cystic duct. This is usually not possible with US. Colour-flow Doppler enables quick distinction of bile duct from ectatic hepatic artery. In less than one-fifth of patients the artery lies anterior to the bile duct.

Post-cholecystectomy

There is disagreement as to whether the normal common duct dilates after cholecystectomy. Symptomatic patients and those with abnormal liver function tests should have further investigations if the common duct measures more than 6 mm.

Further Reading

Foley, WD, Quiroz, FA. The role of sonography in imaging of the biliary tract. Ultrasound Q. 2007; 23(2):123–135.

Ultrasound of the pancreas

Indications

1. Suspected pancreatic tumour

2. Pancreatitis or its complications

3. Epigastric mass

4. Epigastric pain

5. Jaundice

6. To facilitate guided biopsy and/or drainage.

Contraindications

None.

Patient preparation

Nil by mouth, preferably overnight.

Equipment

Technique

1. The patient is supine.

2. The body of the pancreas is located anterior to the splenic vein in a transverse epigastric scan.

3. The transducer is angled transversely and obliquely to visualize the head and tail.

4. The tail may be demonstrated from a left intercostal view using the spleen as an acoustic window.

5. Longitudinal epigastric scans may be useful.

6. The pancreatic parenchyma increases in reflectivity with age, being equal to liver reflectivity in young adults.

7. Gastric or colonic gas may prevent complete visualization. This may be overcome by left and right oblique decubitus scans or by scanning with the patient erect. Water may be drunk to improve the window through the stomach and the scans repeated in all positions. One cup is usually sufficient. Degassed water is preferable.

The pancreatic duct should not measure more than 3 mm in the head or 2 mm in the body.

Endoscopic US (see p. 78) and intraoperative US are useful adjuncts to transabdominal US. EUS may be used to further characterize and biopsy pancreatic solid and cystic lesions. Intraoperative US is used to localize small lesions (e.g. islet cell tumours prior to resection).

Further Reading

Dumonceau, JM, Polkowski, M, Larghi, A, et al. Indications, results, and clinical impact of endoscopic ultrasound (EUS)-guided sampling in gastroenterology: European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline. Endoscopy. 2011; 43(10):897–912.

Computed tomography of the liver and biliary tree

Indications

1. Suspected focal or diffuse liver lesion

2. Staging known primary or secondary malignancy

3. Abnormal liver-function tests

4. Right upper-quadrant pain or mass

5. Hepatomegaly

6. Suspected portal hypertension

7. Characterization of liver lesion

8. Pyrexia of unknown origin

9. To facilitate the placement of needles for biopsy, etc.

10. Assessment of portal vein, hepatic artery or hepatic veins

11. Assessment of patients with surgical shunts or transjugular intrahepatic portosystemic shunt (TIPS) procedures

12. Follow-up after surgical resection or liver transplant.

Contraindications

1. Pregnancy

2. Contraindication to iodinated intravenous (i.v.) contrast medium (contrast-enhanced computed tomography (CECT)) – see Chapter 2.

Technique

Single-phase (portal phase) contrast-enhanced CT

This is the technique for the majority of routine liver CT imaging. The liver is imaged during the peak of parenchymal enhancement, i.e. when contrast-medium-laden portal venous blood is perfusing the liver. This begins about 60–70 s after the start of a bolus injection. Oral contrast may be given but is not necessary if only the liver is being investigated. Slice thickness will depend upon the CT scanner specification but should be 5 mm or less.

Multiphasic contrast-enhanced CT

The fast imaging times of helical/multislice CT enable the liver to be scanned multiple times after a single bolus injection of contrast medium. Most primary liver tumours receive their blood supply from the hepatic artery, unlike normal hepatic parenchyma, which receives 80% of its blood supply from the portal vein. Liver tumours (particularly hypervascular tumours) will therefore enhance strongly during the arterial phase (beginning 20–25 s after the start of a bolus injection) but are of similar or lower density to enhanced normal parenchyma during the portal venous phase (washout). Some tumours are most conspicuous during early-phase arterial scanning (25 s after the start of a bolus injection), others later, during the late arterial phase 35 s after the start of a bolus injection. Thus a patient who is likely to have hypervascular primary or secondary liver tumours should have an arterial phase scan as well as a portal venous phase CT scan (see above). Early and late arterial phase with portal venous phase is appropriate for patients with suspected hepatocellular cancer (triple phase). In general, late arterial and portal venous scans are appropriate to investigate suspected hypervascular metastases. Some centres, however, also use a ‘delayed’ or ‘equilibrium’ phase scan at 180 seconds to help identify and characterize primary liver tumours (quadruple phase). Terminology may be potentially confusing as some centres may consider a triple phase scan to include arterial, portal and delayed scans. Non-contrast examinations have limited usefulness.

Haemangiomas often show a characteristic peripheral nodular enhancement and progressive centripetal ‘fill-in’. After the initial dual- or triple-phase protocol, delayed images at 5 and 10 min are obtained through the lesion.

Computed tomographic cholangiography

Magnetic resonance (MR) cholangiography is non-invasive but sometimes fails to display the normal intrahepatic ducts. Multidetector CT cholangiography can be useful in this instance. With this technique the biliary tree is opacified using an i.v. cholangiographic agent. Isotropic data from 0.625 mm section thickness slices can be reconstructed to provide high-resolution three-dimensional images. Insufficient opacification may be seen with excessively dilated ducts.

Contraindications

Allergy to iodinated contrast agents.

Indications

1. Screening for cholelithiasis

2. Pre-operative screening of anatomy

3. Suspected traumatic bile-duct injury

4. Other biliary abnormalities, e.g. cholesterol polyps, adenomyomatosis and congenital abnormalities.

Technique

1. Patient fasted for at least 6 h.

2. 100 ml i.v. cholangiographic agent, e.g. meglumine iotroxate (biliscopin R) infused for 50 min as a biliary contrast ¹ or iodipamide meglumine 52% – 20 ml diluted with 80 ml of normal saline infused over 30 min.²

3. CT scan should be obtained at least 35 min after infusion of contrast agent.

References

1. Hyodo, T, Kumano, S, Kushihata, F, et al. CT and MR cholangiography: advantages and pitfalls in perioperative evaluation of biliary tree. Br J Radiol. 2012; 85(1015):887–896.

2. Schindera, ST, Nelson, RC, Paulson, EK, et al. Assessment of the optimal temporal window for intravenous CT cholangiography. Eur Radiol. 2007; 17(10):2531–2537.

Further Reading

Francis, IR, Cohan, RH, McNulty, NJ, et al. Multidetector CT of the liver and hepatic neoplasms: effect of multiphasic imaging on tumor conspicuity and vascular enhancement. Am J Roentgenol. 2003; 180(5):1217–1224.

Oto, A, Tamm, EP, Szklaruk, J. Multidetector row CT of the liver. Radiol Clin North Am. 2005; 43(5):827–848.

Computed tomography of the pancreas

Indications

1. Epigastric pain

2. Obstructive jaundice

3. Suspected pancreatic malignancy

4. Acute pancreatitis and its complications

5. Chronic pancreatitis and its complications.

Contraindications

1. Pregnancy

2. Contraindication to iodinated intravenous contrast medium – see Chapter 2.

Technique

1. Negative (e.g. water) oral contrast is generally preferred but positive (e.g. iodinated) may be given if necessary to opacify distal bowel loops. Positive oral contrast agent is contraindicated if CT angiography is to be performed. Volume and timing of oral contrast agent will depend upon whether opacification of distal bowel loops is required.

2. Venous access is obtained.

3. The patient is scanned supine and a scout view is obtained.

4. A non-contrast-enhanced examination can be performed initially if detection of subtle calcification is required.

5. The volume of i.v. contrast used will depend upon the type of scanner. Faster acquisition will allow a smaller volume of contrast, generally 100 ml or less. The timing of the scan in relation to i.v. contrast will depend upon the clinical question. Pancreatic phase enhancement (40 s after commencement of bolus injection) is necessary for optimum contrast differences between pancreatic adenocarcinoma and normal pancreatic tissue, with portal venous phase scans included in the protocol to investigate hepatic metastatic disease. Islet cell tumours and their metastases may show avid enhancement on arterial phase scans and become isodense with normal pancreatic tissue on portal phase scans. A portal phase scan is generally necessary to investigate flow and the relationship of the tumour to the portal vein.

6. The volume and strength of the i.v. contrast will depend upon the speed of the scanner.

7. Slice thickness should be 3 mm or less.

Further Reading

Fletcher, JG, Wiersema, MJ, Farrell, MA, et al. Pancreatic malignancy: value of arterial, pancreatic, and hepatic phase imaging with multi-detector row CT. Radiology. 2003; 229(1):81–90.

Goshima, S, Kanematsu, M, Kondo, H, et al. Pancreas: optimal scan delay for contrast-enhanced multi-detector row CT. Radiology. 2006; 241(1):167–174.

Magnetic resonance imaging of the liver

Indications

1. Lesion characterization following detection by CT or US

2. Lesion detection, particularly prior to hepatic resection for hepatic metastatic disease.

Magnetic resonance imaging (MRI) is rapidly emerging as the imaging modality of choice for detection and characterization of liver lesions. There is high specificity with optimal lesion-to-liver contrast and characteristic appearances on differing sequences and after contrast agents. Focal lesions may be identified on most pulse sequences. Most metastases are hypo- to isointense on T1 and iso- to hyperintense on T2-weighted images. However, multiple sequences are usually necessary for confident tissue characterization. The timing, degree and nature of tumour vascularity form the basis for liver lesion characterization based on enhancement properties. Liver metastases may be hypo- or hyper-vascular.

Magnetic resonance imaging pulse sequences

Common pulse sequences are:

1. T1-weighted spoiled gradient echo (GRE). This has replaced the conventional spin-echo sequence. In and out of phase scans are used to investigate patients with suspected fatty liver.

2. Magnetization-prepared T1-weighted GRE. A further breath-hold technique with very short sequential image acquisition.

3. T1-W GRE fat-suppressed volume acquisition. This sequence can be obtained rapidly following i.v. gadolinium.

4. T2-weighted spin echo (SE). T2-weighted fast spin-echo (FSE; General Electric) or turbo spin-echo (TSE; Siemens).

Compared with conventional T2-weighted SE images, FSE/TSE images show:

1. Fat with higher signal intensity

2. Reduced magnetic susceptibility effects which are of advantage in patients with embolization coils, IVC filters, etc., but disadvantageous after injection of superparamagnetic oxide contrast agent

3. Increased magnetization transfer which may lower signal intensity for solid liver tumours. These sequences may be obtained with fat suppression.

Fat suppression:

1. Decreases the motion artifact from subcutaneous and intra-abdominal fat

2. Increases the dynamic range of the image

3. Improves signal-to-noise and contrast-to-noise ratios of focal liver lesions.

Very heavily T2-weighted sequences can be used to show water content in bile ducts, cysts and some focal lesions. These may be obtained as:

1. Gradient echo breath-hold sequences (e.g. fast imaging with steady state precession (FISP), fast imaging employing steady state acquisition (FIESTA)) or

2. breath-hold very fast spin echo, e.g. half Fourier acquisition single-shot turbo spin echo (HASTE) or

3. non-breath-hold respiratory gated sequences used for magnetic resonance cholangiopancreatography (MRCP).

Fat suppression is also used to allow better delineation of fluid-containing structures.

Short tau inversion recovery (STIR) also suppresses fat, which has a short T1 relaxation time. Other tissues with short T1 relaxation (haemorrhage, metastases and melanoma) are also suppressed.

Diffusion weighted imaging

This very rapidly acquired sequence forms an image based on the microscopic motion of water molecules and may potentially help to detect extra liver lesions and help better characterize them in conjunction with other sequences.

Contrast-enhanced magnetic resonance liver imaging

Gadolinium-enhanced T1-weighted MRI

These probably do not increase sensitivity for focal abnormalities but may help in tissue characterization. When used in conjunction with spoiled GRE sequences it is possible to obtain images during the arterial phase (ideal for metastatic disease and hepatocellular carcinoma), portal phase (hypovascular malignancies) and equilibrium phase (cholangiocarcinoma, slow-flow haemangiomas and fibrosis). Hepatic arterial phase and fast spin-echo T2-weighted sequences are the most sensitive sequences for the detection of hepatic metastases of neuroendocrine tumours.

Liver-specific contrast agents

Standard gadolinium extracellular agents are commonly used for liver MRI as described above, but other contrast agents have been developed to enhance the distinction between normal liver and lesions, especially malignant lesions. These are mostly used in patients who are potentially suitable for major liver surgery, e.g. resection or transplantation:

1. Hepato-biliary agents (e.g. Gadoxetic acid (Primovist®); gadobenate dimeglumine (Multihance®)) are taken up by normal hepatocytes and excreted by normal liver into the bile. The normal liver shows increased signal on T1-weighted sequences for a prolonged period which varies according to the particular agent. Metastases, and other lesions not containing normal-functioning hepatocytes, show as a lower signal than the background liver. Lesions containing hepatocytes will enhance to varying extents. High signal contrast can be seen in the bile ducts which has clinical usefulness. These agents are also excreted by the kidneys. Further details cany be found in Chapter 2.

2. Reticuloendothelial (RE) cell agents (also called super paramagnetic iron oxides, SPIO) are not currently available as they have been withdrawn from the market for commercial reasons. They are taken up by the RE or Kuppfer cells in normal liver giving a decrease in signal on T2- and especially T2*-weighted sequences. They can also be used with T1-weighted sequences for characterization. On T2*-weighted images, malignant lesions without RE cells show as higher signal than the background normal liver. Examination with a SPIO agent may be combined with dynamic gadolinium enhancement in order to maximize the detection and characterization of metastases (and benign lesions) in a patient being considered for surgical resection of metastases. The same combination can be used in a patient with cirrhosis to maximize diagnosis and characterization of HCC vs dysplastic or regenerative nodules.

Magnetic resonance angiography

Contrast-enhanced spoiled GRE images may be obtained to give information with respect to the hepatic artery, portal vein and hepatic venous system.

Magnetic resonance cholangiopancreatography (MRCP)

Indications

1. Investigation of obstructive jaundice

2. Suspected biliary colic/bile duct stones

3. Suspected chronic pancreatitis

4. Suspected sclerosing cholangitis

5. Investigation of jaundice or cholangitis in patients who have undergone biliary enteric anastomosis

6. Prior to ERCP/PTC.

Contraindications

Those that apply to MRI – see Chapter 1.

Technique

MRCP is a non-invasive technique which uses heavily T2-weighted images to demonstrate the intra- and extrahepatic biliary tree and pancreatic duct. Most commonly used to demonstrate the presence of stones and the level and cause of obstruction, especially combined with cross-sectional MRI, in cases of tumour or suspected tumour.

Magnetic resonance imaging of the pancreas

Indications

1. Staging of pancreatic tumours

2. Suspected islet cell tumour

3. Other indications are similar to CT, although CT is generally preferred because of availability, cost and time implications.

Technique

Typical sequences in the axial plane include:

1. T1-weighted fat-suppressed gradient-echo. Normal pancreas hyperintense to normal liver.

2. T1-weighted spoiled gradient-echo (SPGR, GE Medical Systems; fast low-angle shot (FLASH), Siemens). Normal pancreas isointense to normal liver.

3. T2 weighted turbo-spin echo.

4. Gadolinium-enhanced T1-weighted fat-suppressed spoiled gradient echo (GRE). Images are obtained immediately after the injection of contrast medium, after 45 s, after 90 s and after 10 min. Normal pancreas hyperintense to normal liver and adjacent fat on early images, fading on later images.

5. The polypeptide hormone secretin may be given slowly i.v. over one minute to temporarily distend the pancreatic ducts. This can help better assess pancreatic ductal anomalies and also provide information about the exocrine function of the gland.

Further Reading

Bartolozzi, C, Battaglia, V, Bargellini, I, et al. Contrast-enhanced magnetic resonance imaging of 102 nodules in cirrhosis: correlation with histological findings on explanted livers. Abdom Imaging. 2013; 38(2):290–296.

Catalano, OA, Sahani, DV, Kalva, SP, et al. MR imaging of the gallbladder: a pictorial essay. Radiographics. 2008; 28(1):135–155.

Kele, PG, van der Jagt, EJ. Diffusion weighted imaging in the liver. World J Gastroenterol. 2010; 16(13):1567–1576.

Lee, NK, Kim, S, Lee, JW, et al. Biliary MR imaging with Gd-EOB-DTPA and its clinical applications. Radiographics. 2009; 29(6):1707–1724.

Sandrasegaran, K, Lin, C, Akisik, FM, et al. State-of-the-art pancreatic MRI. Am J Roentgenol. 2010; 195(1):42–53.

Ward, J, Robinson, PJ, Guthrie, JA, et al. Liver metastases in candidates for hepatic resection: comparison of helical CT and gadolinium – and SPIO-enhanced MR imaging. Radiology. 2005; 237(1):170–180.

Endoscopic retrograde cholangiopancreatography

Diagnostic endoscopic retrograde cholangiopancreatography (ERCP) has been largely replaced by non-invasive investigations, e.g. CT, MRI supplemented by endoscopic ultrasound. With the advances in non-invasive imaging of the biliary tree and pancreas, over 90% of ERCP procedures are performed with therapeutic (interventional) intent. ERCP is performed by physicians most commonly, but surgeons and radiologists do perform this procedure.

Indications

1. Management of bile duct stones

2. Management of benign and malignant biliary strictures

3. Evaluation of ampullary lesions

4. Diagnostic cholangiography in patients unsuitable/intolerant of MRCP and in whom endoscopic ultrasound is inconclusive or unavailable

5. Treatment and evaluation of chronic pancreatitis

6. Investigation of diffuse biliary disease, e.g. sclerosing cholangitis

7. Post-cholecystectomy syndrome.

Contraindications

1. Oesophageal obstruction; pyloric stenosis/gastric or duodenal obstruction

2. Previous gastric surgery that prevents access to the duodenum

3. Severe cardiac/respiratory disease.

Contrast medium

Pancreas

LOCM 240/300 mg I ml^–1.

Bile ducts

LOCM 150 mg I ml^–1; dilute contrast medium ensures that calculi will not be obscured.

Equipment

1. Side-viewing endoscope

2. Polythene catheters

3. Fluoroscopic unit with spot film facilities.

Patient preparation

1. Nil orally for 4–6 h prior to procedure

2. Premedication (see Chapter 18)

3. Antibiotic cover for patients with biliary obstruction, pseudocyst or high risk of endocarditis.

Preliminary image

Prone AP and left anterior oblique (LAO) of the upper abdomen, to check for opaque gallstones and pancreatic calcification/calculi.

Technique

The patient is sedated until conscious sedation is achieved. The pharynx may also be anaesthetized with 50–100 mg Xylocaine spray. The patient then lies in the left/prone position and the endoscope is introduced. The ampulla of Vater is located and a polythene catheter prefilled with contrast medium is inserted into the ampulla, having ensured that all air bubbles are excluded. A small test injection of contrast under fluoroscopic control is made to determine the position of the cannula. It is important to avoid over-filling of the pancreatic duct. If it is desirable both to opacify the biliary tree and the pancreatic duct, the latter should be cannulated first. If there is evidence of biliary obstruction, a sample of bile should be sent for culture and sensitivity.

Images

Pancreas (using fine focal spot)

Prone, both posterior obliques.

Bile ducts

1. Early filling images to show calculi:

(a) Prone – straight and posterior obliques

(b) Supine – straight, both obliques; Trendelenburg to fill intrahepatic ducts; semi-erect to fill lower end of common bile duct and gallbladder

2. Images following removal of the endoscope, which may obscure the duct

3. Delayed images to assess the gallbladder and emptying of the common bile duct.

Aftercare

1. Nil orally until conscious and sensation has returned to the pharynx (usually <1 hour)

2. Pulse, temperature and blood pressure half-hourly for 6 h

3. Maintain antibiotics if there is biliary or pancreatic obstruction

4. Serum/urinary amylase if pancreatitis is suspected.

Complications

Due to the contrast medium

1. Acute pancreatitis – more likely with large volumes, high-pressure injections

2. Allergic reactions – rare.

Due to the technique

Local

Damage by the endoscope, e.g. rupture of the oesophagus, damage to the ampulla, proximal pancreatic duct and distal common duct.

Distant

Bacteraemia, septicaemia, aspiration pneumonitis, hyperamylasaemia (approximately 70%). Acute pancreatitis (0.7–7.4%).

Intra-operative cholangiography

Indications

During cholecystectomy or bile duct surgery, to avoid surgical exploration of the common bile duct. This technique has been replaced in some centres by pre-operative MRCP and/or EUS.

Contraindications

None.

Contrast medium

High osmolar contrast material (HOCM) or low osmolar contrast material (LOCM) 150, i.e. low iodine content so as not to obscure any calculi; 20 ml.

Equipment

1. Operating table with CR/DR available or a film cassette tunnel

2. Mobile X-ray machine.

Patient preparation

As for surgery.

Technique

The surgeon cannulates the cystic duct with a fine catheter. This is prefilled with contrast medium to exclude air bubbles which might simulate calculi.

Images

1. After 5 ml have been injected

2. After 20 ml have been injected. Contrast medium should flow freely into the duodenum. Spasm of the sphincter of Oddi is a fairly frequent occurrence and may be due to anaesthetic agents or surgical manipulation. It can be relieved by glucagon, propantheline or amyl nitrite.

The criteria for a normal operative choledochogram were given by Le Quesne¹ as:

1. Common bile duct width not greater than 12 mm

2. Free flow of contrast medium into the duodenum

3. The terminal narrow segment of the duct is clearly seen

4. There are no filling defects

5. There is no excess retrograde filling of the hepatic ducts.

Postoperative (T-tube) cholangiography

Indications

1. To exclude biliary tract calculi where (a) operative cholangiography was not performed, or (b) the results of operative cholangiography are not satisfactory or are suspect

2. Assessment of biliary leaks following biliary surgery.

Contraindications

None.

Contrast medium

HOCM or LOCM 150 mg I ml^–1; 20–30 ml.

Equipment

Fluoroscopy unit with spot film device.

Patient preparation

Antibiotics may be considered if previous cholangitis or if immunosuppressed (e.g. liver transplant).

Preliminary image

Coned supine PA of the right side of the abdomen.

Technique

1. The examination is performed on or about the 10th postoperative day, prior to removing the T-tube.

2. The patient lies supine on the X-ray table. The drainage tube is clamped off near to the patient and cleaned thoroughly with antiseptic.

3. A 23G needle, extension tubing and 20 ml syringe are assembled and filled with contrast medium (e.g. a butterfly needle). After all air bubbles have been expelled the needle is inserted into the tubing between the patient and the clamp. The injection is made under fluoroscopic control, the total volume depending on duct filling. In the case of recent biliary anastomosis (i.e. liver transplant) only a small volume of contrast (approximately 10 ml), gently injected, is required.

Images

Fluoroscopic ‘grab’ images during filling are frequently useful. PA and oblique exposures when satisfactory opacification of biliary system.

Aftercare

None.

Complications

Due to the contrast medium

The biliary ducts do absorb contrast medium and cholangiovenous reflux can occur with high injection pressures. Adverse reactions are, therefore, possible, but the incidence is small.

Due to the technique

Injection of contrast medium under high pressure into an obstructed biliary tract can produce septicaemia.

Percutaneous transhepatic cholangiography

Indications

1. Prior to therapeutic intervention, e.g. biliary drainage procedure to relieve obstructive jaundice, or to drain infected bile

2. Place a percutaneous biliary stent

3. Dilate a postoperative stricture

4. Stone removal (see below)

5. To facilitate ERCP by rendezvous technique

6. Rarely for diagnostic purposes only.

Contraindications

1. Bleeding tendency:

(a) Platelets less than 100 × 10⁹ l^–1

(b) Prothrombin time >2 s more than control.

If patient requires urgent procedure then platelet transfusion and FFP can be used to correct. Vitamin K will correct abnormal prothrombin time due to biliary obstruction.

2. Biliary tract sepsis except to control the infection by drainage.

Contrast medium

LOCM 150 mg I ml^–1; 20–60 ml.

Equipment

1. Fluoroscopy unit with digital spot film device (tilting table optional)

2. Chiba needle (a fine, flexible 22G needle, 15–20-cm long)

3. Appropriate catheters and wire for drainage or interventional procedure planned.

Patient preparation

1. Haemoglobin, prothrombin time and platelets are checked, and corrected if necessary

2. Prophylactic antibiotics, e.g. ciprofloxacin 500–750 mg oral before and after procedure

3. Nil by mouth or clear fluids only for 4 h prior to the procedure

4. Ensure patient well hydrated, by i.v. fluids if necessary

5. Sedation (i.v.) and analgesia with oxygen and monitoring.

Preliminary imaging

US to confirm position of liver and dilated ducts.

Technique

1. The patient lies supine. Using US a spot is marked over the right or left lobe of the liver as appropriate. On the right side this is usually intercostal between mid and anterior axillary lines. For the left lobe this is usually subcostal to the left side of the xiphisternum in the epigastrium.

2. Using aseptic technique the skin, deeper tissues and liver capsule are anaesthetized at the site of the mark.

3. During suspended respiration the Chiba needle is inserted into the liver, but once it is within the liver parenchyma the patient is allowed shallow respirations. It is advanced into the liver with real-time US or fluoroscopy control.

4. The stilette is withdrawn and the needle connected to a syringe and extension tubing prefilled with contrast medium. Contrast medium is injected under fluoroscopic control while the needle is slowly withdrawn. If a duct is not entered at the first attempt, the needle tip is withdrawn to approximately 2–3 cm from the liver capsule and further passes are made, directing the needle tip more cranially, caudally, anteriorly or posteriorly until a duct is entered. The incidence of complications is not related to the number of passes within the liver itself and the likelihood of success is directly related to the degree of duct dilatation and the number of passes made.

5. Excessive parenchymal injection should be avoided and when it does occur it results in opacification of intrahepatic lymphatics. Injection of contrast medium into a vein or artery is followed by rapid dispersion.

6. If the intrahepatic ducts are seen to be dilated, bile should be aspirated and sent for microbiological examination. (The incidence of infected bile is high in such cases.)

7. Contrast medium is injected to outline the duct system and allow access for a guidewire or selection of an appropriate duct for drainage.

8. Care should be taken not to overfill an obstructed duct system because septic shock may be precipitated.

9. For diagnostic PTC only the needle is removed after suitable images have been recorded.

Images

Contrast medium is denser than bile and the sequence of duct opacification is, therefore, gravity-dependent and determined by the site of injection and the position of the patient.

Using the undercouch tube with the patient horizontal:

1. PA

2. LAO

3. RAO

4. If on a non-tilting table, rolling the patient onto the left side will fill the left ducts and common duct above an obstruction.

When the above images have shown an obstruction at the level of the porta hepatis, a further image after the patient has been tilted towards the erect position for 30 min may show the level of obstruction to be lower than originally thought.

Delayed images

Images taken after several hours, or the next day, may show contrast medium in the gallbladder if this was not achieved during the initial part of the investigation.

Aftercare

Bed rest, pulse and blood pressure measurement half-hourly for 6 h.

Complications

Morbidity approximately 3%; mortality less than 0.1%.

Due to the contrast medium

Allergic/idiosyncratic reactions – very uncommon.

Due to the technique

Local

1. Puncture of extrahepatic structures – usually no serious sequelae

2. Intrathoracic injection

3. Cholangitis

4. Bile leakage – may lead to biliary peritonitis (incidence 0.5%). More likely if the ducts are under pressure and if there are multiple puncture attempts. Less likely if a drainage catheter is left in situ. (See ‘Biliary drainage’ below)

5. Subphrenic abscess

6. Haemorrhage

7. Shock – owing to injection into the region of the coeliac plexus.

Generalized

Bacteraemia, septicaemia and endotoxic shock. The likelihood of sepsis is greatest in the presence of choledocholithiasis because of the higher incidence of pre-existing infected bile.

Reference

1. Patey, DH, Le Quesne, LP, Whiteside, CG, et al. Discussion on cholangiography. Proc R Soc Med. 1960; 53:851–860.

Further Reading

Canlas, KR, Branch, MS. Role of endoscopic retrograde cholangiopancreatography in acute pancreatitis. World J Gastroenterol. 2007; 13(47):6314–6320.

External biliary drainage

This is achieved following transhepatic cannulation of the biliary tree as described above. The procedure may be performed to improve jaundice or sepsis prior to surgery or as a further percutaneous intervention.

Internal biliary drainage

This can be achieved following transhepatic (as above) or endoscopic cannulation of the biliary tree. A percutaneous drainage catheter may allow internal or external drainage with sideholes above and below the point of obstruction. At ERCP an endoprosthesis or stent is placed to drain bile from above a stricture or to prevent obstruction by a stone in the duct.

Indications

1. Malignant biliary stricture

2. Benign stricture following balloon dilatation.

Contraindications

As for percutaneous transhepatic cholangiography (PTC).

Contrast media

LOCM 200 mg I ml^–1; 20–60 ml.

Equipment

1. Wide-channelled endoscope for introduction of endoprosthesis by ERCP

2. A biplane fluoroscope facility is useful but not essential for transhepatic puncture

3. Set including guidewires, dilators and endoprosthesis.

Patient preparation

See percutaneous transhepatic cholangiography above.

Technique

Transhepatic

1. A percutaneous transhepatic cholangiogram is performed.

2. A duct in the right lobe of the liver that has a horizontal or caudal course to the porta hepatis is usually chosen. This duct is studied on US to judge its depth and then a 22G Chiba needle is inserted into the duct under US or fluoroscopic guidance. A coaxial introducer system is used over a 0.018 guidewire to allow 0.035 wire and catheter access into the bile ducts. If the duct is not successfully punctured, the Chiba needle is withdrawn but remains within the liver capsule allowing a further puncture attempt. Once a 0.035 wire is established in the bile duct a sheath can be inserted, e.g. 7-F. Bile can be drained through the side arm of the sheath while a catheter is manipulated over the wire. For internal drainage or stent insertion the wire and catheter must be passed through the stricture into the duodenum or postoperative jejunal loop. For external drainage, a suitable catheter can be inserted over the wire after the sheath is withdrawn. A variety of wires and catheters may be needed to cross difficult strictures. Failing this, external drainage is instituted and a further attempt is made to pass the stricture a few days later.

3. An internal/external catheter may be placed across the stricture and secured to the skin with sutures.

4. A metal biliary stent may be positioned and deployed across a malignant stricture to facilitate internal drainage of bile. Balloon dilatation may be required before or after stent deployment in some cases. A temporary external drainage tube may be left in place for 24–48 h.

Endoscopic

1. Cholangiography following cannulation of the biliary tree

2. Endoscopic sphincterotomy

3. A guidewire is placed via the channel of the endoscope through the sphincter and pushed past the stricture using fluoroscopy to monitor progress

4. Following dilatation of the stricture the endoprosthesis (plastic stent) is pushed over the guidewire and sited with its side-holes above and below the stricture. Metal biliary stents can also be placed at ERCP when appropriate.

Aftercare

1. As for percutaneous transhepatic cholangiography

2. Antibiotics for at least 3 days

3. An externally draining catheter should be regularly flushed through with normal saline and exchanged at 3-monthly intervals. (It is rare to leave a drain in situ for such a long period.)

Complications

1. As for PTC, ERCP and sphincterotomy

2. Sepsis – particularly common with long-term, externally draining catheters

3. Dislodgement of catheters, endoprostheses

4. Blockage of catheters/endoprostheses

5. Perforation of bile duct above the stricture on passage of guidewires.

Percutaneous extraction of retained biliary calculi (burhenne technique)

Indications

Retained biliary calculi seen on the T-tube cholangiogram (incidence 3%).

Contraindications

1. Small T-tube (<12-F)

2. Tortuous T-tube course in soft tissues

3. Acute pancreatitis

4. Drain in situ (cross connections exist between the drain tract and the T-tube tract).

Contrast medium

HOCM or LOCM 150 mg I ml^–1 (low-density contrast medium is used to avoid obscuring the calculus).

Equipment

1. Fluoroscopy unit with spot film device

2. Steerable catheter system with wire baskets.

Patient preparation

1. Admission to hospital on the day prior to the procedure

2. Prophylactic antibiotics and pre-medication 1 h prior to the procedure

3. Analgesia during the procedure.

Technique

1. The patient lies supine on the X-ray table. A PTC is performed if a biliary drainage catheter is not already in situ.

2. The drainage catheter is removed over a guidewire and a sheath inserted in to the ducts (7 or 8-F).

3. Contrast is injected to identify stones and strictures.

4. If there is a stricture, advance a biliary manipulation catheter and guidewire (0.035) across it. Commence balloon dilatation over the guidewire (e.g. 8, 10 and possibly 12 mm).

5. Attempt to dislodge stones with balloons into the Roux loop.

6. If this is unsuccessful pass Dormier basket through sheath and attempt to catch the stone in the basket.

7. Advance the basket into the Roux loop and release the stone into the loop.

8. Remove the basket.

9. Pass the guidewire, remove the sheath and place the biliary drainage catheter.

10. Intermittently inject the contrast media to clarify the position of the stones.

Aftercare

1. Pulse and blood pressure half-hourly for 6 h

2. Bed rest for 4–6 h.

Complications

Due to the contrast medium

1. Allergic reactions – rare

2. Pancreatitis.

Due to the technique

1. Fever

2. Perforation of the T-tube tract.

Further Reading

Complications

Burke, DR, Lewis, CA, Cardella, JF, et al. Society of Interventional Radiology Standards of Practice Committee: Quality improvement guidelines for percutaneous transhepatic cholangiography and biliary drainage. J Vasc Interv Radiol. 2003; 14(9 Pt 2):S243–S246.

Uberoi, R, Das, N, Moss, J, et al. British Society of Interventional Radiology: Biliary Drainage and Stenting Registry (BDSR). Cardiovasc Intervent Radiol. 2012; 35(1):127–138.

Angiography

Coeliac axis and superior mesenteric

Indications

1. Suspected haemorrhage/haemobilia prior to intervention (embolization of bleeding point or aneurysm)

2. Prior to embolization and intervention, e.g. embolization, chemo-embolization, radio-embolization of tumours

3. Suspected polyarteritis nodosa

4. Demonstration of portal venous system (when cross-sectional imaging is insufficient). This indication is rare with modern imaging.

Technique

See Chapter 3, page 77.

Radionuclide imaging of liver and spleen

Indications

1. To assess liver for space-occupying lesions – essentially no longer performed because of greater utility of CT, MR and US

2. To characterize a focal liver lesion as possible focal nodular hyperplasia (these lesions contain Kupffer cells and hence take up colloid; other liver masses will be manifest as photopenic lesions)

3. To detect splenunculi (ectopic splenic tissue)

4. Assessment of liver function (displacement of activity of spleen and bone marrow).

Contraindications

None.

Radiopharmaceuticals

^99mTc tin or sulphur colloid 80 MBq (ED 1 mSv), for SPECT 200 MBq (ED 2 mSv). Cleared by phagocytosis into the reticuloendothelial cells, where it is retained. Spleen is demonstrated as well as liver.

Equipment

1. Gamma-camera

2. Low-energy general purpose collimator.

Patient preparation

None.

Technique

1. Patient lies supine

2. Image at 20 min post injection

3. Images anterior with costal margin markers, posterior, left and right laterals.

500 kilocounts are used for each view. SPECT can be used when necessary.

An additional technique is first-pass dynamic flow study, which may occasionally be performed to improve differential diagnosis of liver masses.

Aftercare

None.

Complications

None.

Alternative investigative imaging modalities

1. Multidetector CT

2. MRI with reticuloendothelial contrast agent

3. ¹⁸FDG-PET for investigation of primary or secondary malignancy (see Chapter 11)

4. Platelet or denatured red-cell scan for splenunculi.

Further Reading

Harding, LK, Notghi, A. Gastrointestinal tract and liver. In: Sharp PF, Gemmell HG, Murray AD, eds. Practical Nuclear Medicine. 3rd ed. London: Springer-Verlag; 2005:273–304.

Radionuclide hepatobiliary and gallbladder radionuclide imaging

Indications

1. Suspected acute cholecystitis

2. Assessment of gallbladder, common bile duct and sphincter of Oddi function 1,2

3. Assessment of neonatal jaundice where biliary atresia is considered

4. Suspected bile leaks after trauma or surgery ³

5. Investigation of biliary drainage.

Contraindications

None.

Radiopharmaceuticals

^99mTc-trimethylbromo-iminodiacetic acid (TBIDA) or other iminodiacetic acid (IDA) derivative; 80 MBq typical (1 mSv ED), 150 MBq max (2 mSv ED). ^99mTc-pertechnetate 10 MBq (0.13 mSv ED) to demonstrate stomach outline.

These ^99mTc-labelled IDA derivatives are rapidly cleared from the circulation by hepatocytes and secreted into bile in a similar way to bilirubin;⁴ this allows the assessment of biliary drainage and gallbladder function. A number have been developed with similar kinetics, but the later ones, such as TBIDA, have high hepatic uptake and low urinary excretion, giving better visualization of the biliary tract at high bilirubin levels than the early agents.

Equipment

1. Gamma-camera

2. Low-energy general purpose collimator.

Patient preparation

1. Nil by mouth for 4–6 h

2. For the investigation of biliary atresia, infants are given phenobarbital orally 5 mg kg^–1 day^–1 in two divided doses for 3–5 days prior to the study to enhance hepatic excretion of radiopharmaceutical.

Technique

The imaging protocol depends upon the clinical question being asked. A dynamic study should be performed where it is important to visualize the progress of the bile in detail, e.g. post-surgery:

1. The patient lies supine with the camera anterior and liver at the top of the field of view.

2. The radiopharmaceutical is injected i.v.

Images

1. 1-min 128 × 128 dynamic images are acquired for 45 min after injection.

2. 30–45 min post-injection when the gallbladder is well visualized, a liquid fatty meal (e.g. 300 ml full cream milk) is given through a straw to stimulate gallbladder contraction and imaging continued for a further 45 min. A gallbladder ejection fraction can be calculated.

3. If the gallbladder and duodenum are not seen, static images are obtained at intervals of up to 4–6 h.

4. If images are suggestive of reflux, 100–200 ml of water is given through a straw to diffuse any activity in the stomach and thereby differentiate it from nearby bowel activity. Four min before the end of imaging, 100 ml of water containing 10 MBq ^99mTc-pertechnetate may be given to delineate the stomach.

5. If no bowel activity is seen by 4–6 h and it is important to detect any flow of bile at all, e.g. in suspected biliary atresia, a 24-h image should be taken.

Additional techniques

Cholecystokinin (CCK) and morphine provocation ¹

Pharmacological intervention can be used in combination with TBIDA scanning to improve diagnosis of diseases affecting the gallbladder, common bile duct or sphincter of Oddi. CCK causes gallbladder contraction and sphincter of Oddi relaxation. An i.v. infusion of CCK is given over 2–3 min when the gallbladder is visualized 30–45 min after TBIDA administration. Dynamic imaging is continued for a further 30–40 min.

Quantitative measures of gallbladder ejection fraction and emptying rate can be calculated. It has been suggested that a slow CCK infusion over 30–60 min may improve specificity.⁵

Morphine causes sphincter of Oddi contraction. In a clinical setting of suspected acute cholecystitis, if the gallbladder is not observed by 60 min, an infusion of 0.04 mg kg^–1 over 1 min can be given and imaging continued for a further 30 min. Continued non-visualization of the gallbladder up to 90 min is considered to confirm the diagnosis. Morphine provocation has also found success in diagnosis of elevated sphincter of Oddi basal pressure.²

Quantitative analysis

Some investigators have calculated liver function parameters from dynamic studies, e.g. in order to attempt to differentiate between transplant rejection and hepatocyte dysfunction.

Aftercare

None.

Complications

Monitor for adverse reactions to CCK and morphine.

References

1. Krishnamurthy, S, Krishnamurthy, GT. Cholecystokinin and morphine pharmacological intervention during ^99mTc-HIDA cholescintigraphy: a rational approach. Semin Nucl Med. 1996; 26(1):16–24.

2. Thomas, PD, Turner, JG, Dobbs, BR, et al. Use of ^99mTc-DISIDA biliary scanning with morphine provocation for the detection of elevated sphincter of Oddi basal pressure. Gut. 2000; 46(6):838–841.

3. Rayter, Z, Tonge, C, Bennett, C, et al. Ultrasound and HIDA: scanning in evaluating bile leaks after cholecystectomy. Nucl Med Commun. 1991; 12(3):197–202.

4. Krishnamurthy, GT, Turner, FE. Pharmacokinetics and clinical application of technetium 99m-labeled hepatobiliary agents. Semin Nucl Med. 1990; 20(2):130–149.

5. Ziessman, HA. Cholecystokinin cholescintigraphy: victim of its own success? Q J Nucl Med. 1999; 40(12):2038–2042.

Further Reading

Harding, LK, Notghi, A. Gastrointestinal tract and liver. In: Sharp PF, Gemmell HG, Murray AD, eds. Practical Nuclear Medicine. 3rd ed. London: Springer-Verlag; 2005:273–304.

Investigation of specific clinical problems

The investigation of liver tumours

Investigation

This falls into three stages:

1. Detection

2. Characterization of the tumour

3. Assessment for surgical resection or staging for chemotherapy.

The clinical context and proposed management course usually determine the extent of investigation. Liver metastases are much commoner than primary liver cancers. Benign haemangiomas are also common, being present in 5–10% of the population. Other benign liver lesions, except cysts, are less common.

The clinical data correlated with the radiological investigations usually enable the character of a liver tumour to be determined with a high degree of probability. This can be confirmed with image-guided or surgical biopsy when appropriate. Many surgeons are averse to pre-operative biopsy in a patient with a potentially resectable/curable lesion because of the small risk of disseminating malignant cells and the possibility of misleading sampling error. If biopsy is performed, it is sometimes important to sample the ‘normal’ liver as well as the lesion. The presence of cirrhosis may have a major impact on management. Hepatic resection is an established procedure for the management of selected hepatic metastases and primary liver tumours. Imaging is used to assess the number and location of tumours.