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Liver Cancer
Contrast-enhanced Magnetic Resonance Imaging – A Method with Prospects
Satellite Symposium: ‘Our Innovative, Comprehensive and Targeted Approach to Focal Liver Lesions’
Held at the 43rd Annual Meeting of the European Association for the Study of the Liver (EASL) on 24 April 2008, Milan
Convenor: Bayer Schering Pharma, Berlin
The Clinical Management of Liver Tumours as an high rate of false-positive findings and the relative imprecision with
Interdisciplinary Task which small lesions (<1cm) are displayed are seen as significant
At the 43rd annual meeting of the European Association for the Study disadvantages of this technique. The imaging modality that now
of the Liver (EASL),
1
gastroenterologist Professor Peter Malfertheiner provides the most sensitive and specific information is MRI. When used
expressed the view that the clinical management of focal liver lesions in combination with tissue-specific contrast agents it permits soft-
requires close co-operation between clinicians and radiologists. He felt tissue diagnosis in the various haemodynamic phases of tissue
that of the imaging methods currently available, magnetic resonance perfusion: arterial, portal venous and in equilibrium. In hepatocyte-
imaging (MRI) with the liver-specific gadolinium ethoxybenzyl specific contrast agents such as Gd-EOB-DTPA, gadolinium is bound to
diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-containing a chelate with both hydrophilic and lipophilic properties. Once in the
contrast agent Primovist
®
provides the most precise detection, liver, it is actively taken up by hepatocytes to an extent of 50%, and is
localisation and characterisation of focal liver lesions and permits subsequently excreted in equal amounts in the bile and urine.
effective planning of treatment.
Native T1- and T2-weighted MRIs obtained before intravenous bolus
Many focal liver lesions remain undiscovered throughout the patient’s administration of Gd-EOB-DTPA provide important information on the
life and are an incidental finding in over 50% of autopsies. Most organ structure of the liver such as the proportions of fat and water
common are haemangiomas (20%), followed by focal nodular (see Figure 1). During the vascular phase, healthy liver tissue, which is
hyperplasia (3%), according to Professor Claudio De Angelis. approximately 75% perfused via the portal vein, can be distinguished
Furthermore, he emphasised that given the multiplicity of benign, from tumours, which are 80–95% perfused via the hepatic artery. For
malignant and infectious changes that can occur, the precise example, hepatocellular carcinomas are hypervascularised and show
localisation and characterisation of focal liver lesions requires a great high enhancement during the vascular phase. Similarly,
deal of diagnostic intuition. In this regard, imaging techniques are an haemangiomas and focal nodular lesions show typical enhancement
important instrument for confirming a clinical suspicion. Most focal patterns during the various phases. Professor Lennart Blomqvist
liver lesions are incidental findings, especially during ultrasound explained that in the hepatocellular phase the liver parenchyma
examinations performed as part of the follow-up of tumour patients or appears bright after taking up the contrast agent as a result of the
in screening programmes for liver cirrhosis. increased signal intensity, whereas lesions without functional
hepatocytes remain dark.
In the experience of Professor De Angelis, small lesions of less than
15mm in asymptomatic patients are generally benign, even in patients Superior Performance Profile
with a history of tumours. On the other hand, suspicion is called for in Use of Gd-EOB-DTPA makes it possible to distinguish benign lesions
patients with advanced cirrhosis. A recent study by an Italian working such as focal nodular hyperplasia from malignant lesions such as
group found that about 50% of lesions initially thought to be hepatocellular carcinoma, cholangiocarcinoma and metastases of
haemangiomas proved to be hepatocellular carcinomas. Other other primary tumours on the basis of the phase-specific signal
primary tumours are relatively rare. However, the liver is a preferred site distribution, without the need for liver biopsies. It also provides
of metastasis of other tumours, particularly gastrointestinal tumours. important information about functional parameters such as the extent
and haemodynamics of liver perfusion, for example, the rate of
What Comes After Ultrasound? transfer between the various compartments (blood, hepatocytes, bile)
The quality of ultrasound findings varies with the experience of the and the functional status of the hepatocytes.
examiner and the quality of the equipment. Contrast-enhanced
ultrasound (CEUS) is generally the preserve of specialised centres. In the clinical setting, CEMRI can produce images for about 30 minutes.
According to the EASL Barcelona guidelines, in this situation a Professor Blomqvist concluded that thanks to its superior performance
computed tomography (CT) scan or a contrast-enhanced (CE)-MRI profile, CEMRI has now superseded CT as the preferred imaging method
scan should also be performed before consideration is given to for the differential diagnosis of local hepatic lesions, although he
performing a liver biopsy. According to Professor De Angelis, “A conceded that this will not always be achievable in routine clinical
biopsy is the diagnostic method of last choice.” practice. Nevertheless, he felt that in view of the ever closer ties that are
developing between the work of oncologists, hepatologists and
CT, especially multidetector CT, provides significantly better diagnosis (interventional) radiologists, preference should be given to a method that
of abdominal lesions. However, in addition to radiation exposure a also opens up the best possibilities in terms of subsequent treatment.
© TOUCH BRIEFINGS 2008 77
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