History
A 41-year-old woman attended hospital for an ultrasound appointment requested by her general practitioner (GP). She had undergone a laparoscopic cholecystectomy 4 months previously and had recovered well, but over the last 3 weeks she had been complaining of increasing pain in the right upper quadrant and occasional itching. She denied any weight loss or jaundice, and reported normal appearances to her stool and urine. She is a non-drinker with no other notable medical history.
Examination
On examination she had slightly icteric sclera. She was comfortable at rest but had scratch marks on her upper arms from recent itching. The cardiovascular and respiratory examinations were normal, and her
abdomen was soft with slight ten- derness of the right upper quadrant on deep palpation. There was no organomegaly.
Investigations showed a normal full blood count and renal function, but liver function showed an elevated bilirubin and alkaline phosphatase with normal transaminases and albumin levels. Her amylase was normal.
She was referred for an abdominal ultrasound to assess her liver paren- chyma (Figures 14.1 and 14.2).
Questions
• What does the ultrasound demonstrate?
• What procedure is performed in Figure 14.2?
• What is interventional radiology?
Figure 14.1 Abdominal ultrasound.
ANSWER 14
Figure 14.1 is a single ultrasound image of the left lobe of the liver obtained with a curvilinear transducer (C5–2) in a longitudinal orientation. The liver appears of normal echogenicity and echo texture with a smooth capsular contour. No focal lesion is seen on this image. There are anechoic linear structures seen which extend to the periphery with a maximal diameter of 4 mm, and colour Doppler assessment in Figure 14.2 demonstrates no flow within them. This is in keeping with intrahepatic biliary duct dilatation, and the remainder of the study did not demonstrate an obstructing lesion although the common bile duct (CBD) was 7 mm in diameter, which is within normal limits for a patient post cholecystectomy. The patient was referred for a liver magnetic resonance imaging (MRI) scan for further characterization. The liver function tests of raised bilirubin and alkaline phosphatase with normal transaminases and albumin suggest obstruction with normal cellular and synthetic function.
Figure 14.3 is a coronal maximal intensity projection (MIP) image of the same patient acquired from heavily T2-weighted sequences. It confirms moderate intrahepatic biliary duct dilatation and also demonstrates a focal tapered stenosis at the level of the common hepatic duct. There is no intraductal filling defect or stenosing soft tissue mass lesion, and the CBD and pancreatic duct are of normal calibre. The appearances suggest a stricture of the common hepatic duct which may be ischaemic, post inflammatory or neoplastic in nature. Endoscopic retrograde cholangiopancreatography (ERCP) was advised to obtain cytology brushings, attempt to correct the obstruction and decompress the intrahepatic ducts, but a stent could not be inserted. The patient was therefore referred to the inter- ventional radiology department for a percutaneous transhepatic cholangiogram (PTC). The single image of the PTC (Figure 14.4) was acquired by opacifying the intrahepatic ducts with radiographic contrast during a fluoroscopy procedure. The dilated ducts of the left system were punctured under ultrasound guidance, and a guidewire was then manipulated across the hilar stricture and down into the duodenum. A sheath (8F) was inserted to stabilize the position, and contrast was injected through this to perform the cholangiogram. A stent can be passed over the wire and placed across the stenosis to relieve the obstruction and improve patient symptoms. This procedure is performed by the interventional radiology department.
Interventional radiology (IR) is an expanding subspeciality of radiology that uses imaging guidance and minimally invasive techniques to diagnose and treat a patient. A trained radiologist uses their experience in ultrasound, computed tomography (CT) and fluoros- copy to guide the passage of a needle or catheter to a site of interest and perform a task that would otherwise be surgically difficult and involve significant morbidity in the form of an open operation. Interventional radiology consultants can use the veins, arteries and biliary ducts to access deep or distal lesions, vessels or organs, often leaving only a pin- hole size scar at the site of puncture (often the groin) as a sign of recent treatment. This allows tissue conservation, reduced morbidity and faster recovery for patients. The scope of the speciality is too broad to be effectively covered in this answer, but the procedures used include the following:
• Angiography: A vein or artery can be punctured with ultrasound guidance, and con- trast is injected mapping the vessel anatomy under fluoroscopy. Stenoses and occlu- sions can be characterized and an expandable balloon is used to improve blood flow. This is termed ‘angioplasty’.
Figure 14.3 Coronal maximal intensity projection image.
Figure 14.4 Percutaneous transhepatic cholangiogram.
• Biopsy: Ultrasound (superficial lesions) and CT (complicated or deep lesions) can help to guide a needle accurately to a lesion of interest for core biopsy and histological characterization.
• Drainage: Inserting a drain can offer a conduit for decompression of infected collec- tions or uncomfortable ascites. Optimal and accurate placement is obtained by imag- ing guidance.
• Stenting: Expandable stents can be inserted into a vessel or duct to act as ‘scaffolding’ and can exert radial force to maintain patency in atherosclerosis or tumour stenosis. • Line insertion: Patients on long-term therapy (e.g. dialysis, antibiotics, chemotherapy)
require definitive vascular access (e.g. Hickman line, portacath) to avoid the discom- fort of recurrent peripheral cannulation and thrombophlebitis.
• Embolization: Instilling an embolic agent (coils, particles or glue) into a selectively cannulated vessel can control active haemorrhage, prevent aneurismal rupture or infarct a tumour (e.g. uterine fibroid). An adjunct to this is chemoembolization, where a chemotherapy agent is instilled directly to a tumour and then the blood vessel is embolized to cause tumour infarction.
KEY POINTS
• Ultrasound is excellent for the assessment of the liver and has a high sensitivity for detecting intrahepatic biliary duct dilatation.
• Biliary obstruction can be circumvented by stent insertion either via ERCP or PTC. • Interventional radiology is a subspeciality of radiology that uses image guidance to
perform minimally invasive techniques.
• Radiofrequency ablation: Small malignant lesions can be cauterized via a specialized electrical probe that is inserted under image guidance for accurate placement.
• Vertebroplasty: Guiding the infusion of inert cement into a collapsed spinal vertebra can provide stability in cases of osteoporotic or metastatic collapse.