Conventional radiograph

In a typical case, the liver shadow is located under the diaphragm on the right side on the conventional abdominal radiograph. (Figure 2) .

Figure 2.: Hepatomegaly, native abdominal X-ray

Since it is a parenchymal organ, a sort of circumscribed radiographic abnormality can be only seen on its projection, if the beam absorbance or the beam transmission of the abnormality is notably different. An Echinococcus cyst bearing with a calcified wall, a calcified gall stone, or possibly a porcelain gallbladder can appear as such a beam absorbing lesion. The beam

transmitting gas bubbles can refer to gas inside the biliary ducts (normal postoperative

situation or pathologic abnormality, eg. in case of gallstone ileus) and probably to gas bubbles inside a liver abscess due to their shapes, locations and amounts.

14.1.1.2. Ultrasound

Using an accurately set and good resolution ultrasound (US) device, it is considered as a very sensitive imaging method. However, it is a non-specific and – similarly to other US

examinations – very operator-depending method.

The specificity of the contrast enhanced US examinations is relatively similar to that of CT and non hepatocyte-specific contrast enhanced MRI.

It is important to note that using a top category device, a better qualified radiologist, who has a better imaging experience, can gain significantly more additional information in case of a repeated US examination of a certain intrahepatic lesion (accordingly, CT is definitely not the next step…!). This special, unknown and unadopted way of the progressive patient care would be essential to consider.

The US examination is an indefinitely repeatable, easily accessible, relatively cheap method.

The value of the standard examination (2D, real-time US) can be advanced notably by color duplex US. In case of nodal liver diseases and pathologic circulation circumstances, the specificity can be raised especially by contrast enhanced US examination. The flow direction (color) and intensity (doppler spectrum) can be determined accurately in certain diseases considering the intrahepatic arteries and veins.

In the report of a liver US, its size, shape, echo structure, shape variation, possible focal lesions and obviously, the adjacent lesions around the liver must be declared as well.

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The echogenicity of the normal liver tissue is mildly hyperechoic (Figure 3) due to the intrahepatic connecting tissue structures, small veins, arteries and bile ducts (its echogenicity is principally comparable with the adjacent normal right kidney cortex, the liver has a bit hyperechoic structure than the right kidney, and its echogenecity is principally the same as the spleen's).

Figure 3: Normal liver, 2D US image

The portal vein and its branches have hyperechoic walls which can be easily differenciated in the liver structure. The walls of the hepatic vein branches have remarkable less echogenecity.

The normal diameter intrahepatic bile ducts and the smaller liver arteries cannot be imaged and observed. The wall of the hepatic ducts and the main biliary duct (ductus choledochus) is also moderately hyperechoic. The hepatic hilum consists of the „double barrel‖ configuration (main biliary duct – portal vein, inbetween the cross-sectional view of the hepatic artery trunk) in the typical anatomical location, using an appropriate longitudinal plane.

The complex abdominal US examination is performed by a 3-5 MHz convex ultrasound probe, usually starting with the US imaging of the liver from subcostal direction in deep inspiration. In case of anatomical variations, upward displacement of the diaphragm, unappropriate breathing cooperation and postoperatively (eg., upper abdominal drain), the intercostalis imaging can be very important.

The anatomical structural unit of liver, bile ducts and the gallbladder will be adjudged and reported afterwards.

14.1.1.3. CT

Nowadays, CT is a basically important method amongst the modern diagnostic imaging services. (Figure 4) By the application of the multidetector CTs a chance is given to perform multiphase (without contrast, arterial, portal and late phase) CT scans, which provide

important additional information because of the different hemodynamics of certain

intrahepatic nodules. Multiplanar (sagittal, coronal, oblique) and 3D reconstructions can be adopted from the axial plane CT slices. Due to CT angiographic techniques, excellent spatial resolutional 3D reconstructional images can be performed both on the arterial (hepatic artery) and the venous sides (portal vein, hepatic veins, collateral veins in case of portal hypertension, CT control of transjugular portosystemic shunts)..

173 Figure 4. Liver, contrast enhanced CT, venous phase

14.1.1.4. MRI

In multiple cases if the exact diagnosis could not be made by US and CT, MRI examination can be necessary. (Figure 5)

Figure 5: Liver, T2 weighted MRI

MRI can be applied especially in children and young adults – also in order to replace the CT scans due to its unneglectable radiation exposure. Following US examination, in case of a known contrast allergy, pregnancy or denial of intravenous contrast administration additional imaging information can be gained by MRI. However it is important to note that biopsy usually precedes (correctly) the MRI. Nowadays, MRI scans of the abdominal parenchymal organs are infrequently performed only in dedicated cases due to the above mentioned reasons in foreign large diagnostic centres (unless in case of scientific motivation).

Good news that MR cholangiopancreatography (MRCP – Figure 6) plays an increasingly more important role in the biliary duct imaging since MRCP provides nearly the same image quality as ERCP. In addition, it is extremely important to note that the non-invasive MRCP does not accompany with complications such as pancreatitis or cholangitis which occur in an unneglectible percentage during the ERCP.

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Figure 6: MRCP (Magnetic resonance cholangiopancreatography)

14.1.1.5. Angiography

The CT-angiography and MR-angiography methods take nowadays over from the diagnostic selective catether hepatic angiographies. The catheter angiographies are performed in case of therapeutic (TAE – Figure 7, TACE, chemoperfusion) interventions and the traumatic liver injuries (selective embolisation) on these fields.

Figure 7: TAE (Transarterial Embolisation) of the liver with Lipiodol 14.1.1.6. Endoscopic retrograde cholangiography, cholangiopancreatography (ERC, ERCP)

This method implies the retrograde contrast filling of the biliary and pancreatic ducts from the papilla of Vater performed usually by gastroenterologists under a fluoroscopy guidance.

(Figure 8)

175 Figure 8: ERCP (Endoscopic retrograde cholangiopancreatography)

It is very important to note that bacteria can ascend to the basically sterile biliary ducts from the duodenum during the retrograde contrast administration developing cholangitis, therefore, the intervention must be always performed with antibiotic protection. Following the contrast administration, specific radiographic images must be performed in different projections in order to image the possible filling excesses, filling defects or biliary duct stenoses properly. In 5-15% following the procedure, mild or severe pancreatitis can also develop. Thus, ERCP must be handled as studiously invasive intervention and it should be only performed in case of an established clinical decision. Directly following the diagnostic procedure, therapeutic interventions can be also performed through the working canal of the endoscopic device in necessary situations (papillotomy, stone extraction, mechanic stone comminution, biliary duct stent implantation).