GI Radiology


Case  37 :  
 

45/M chronic alcoholic with severe thoracic pain What is the diagnosis?

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Diagnosis

Hepatocellular Carcinoma with skeletal metastasis

Findings: 

Contrast CT thorax reveals destructive lesions in upper dorsal vertebra and left upper rib. In addition a large heterogeneously enhancing mass is seen in the upper sections through liver.
For characterizing the liver lesion a contrast MR of the liver was performed. On Precontrast scans a heterogeneous mass is seen in segment VIII of right lobe of liver. The mass is partly exophytic and is slightly heterogeneous on T1 and heterogeneously hyperintense on T2WI. On Arterial phase post Gd-BOPTA mass is intensely enhancing, becoming isointense to hypointense in portal venous phase. 30 min post Gd-BOPTA images mass is homogeneously hypointense whereas the normal liver shows enhancement representing the mass does not have functional hepatocytes. No scar is noted within.
A diagnosis of HCC with skeletal metastasis was given on imaging findings. Serum Alpha-fetoprotein level performed subsequently was 980 U.


Discussion

Thereare 4 classes of MR liver contrast agents
   1. Extracellular gadolinium chelates
   2. RES specific
   3. Hepatocyte specific
   4. Combined perfusional & 
       hepatocyte selective

Gd-BOPTA belongs to group 4.  Functioning hepatocyte containing lesions show enhancement on 30min post-Gd scans.

HCC

  1. Incidence rising. Doubled in last 20yrs
  2. Epidemic of Hep C on rise.
  3. 40% HCC in non-cirrhotic livers
  4. Patients with chronic liver disease—particularly cirrhosis, hepatics B or C, hemochromatosis—are at risk for HCC.

3 patterns
   1] Solitary Mass
   2] Dominant mass with smaller satellite
       lesions (i.e., multifocal HCC, 20%)
   3] Diffuse involvement more common in
       cirrhotics

  1. Highly vascular – may rarely hemorrhage spontaneously
  2. Propensity to invade vessels, vascular involvement should be carefully evaluated
  3. Most commonly, lesions are well circumscribed with appearance of well-defined  ‘‘capsule.’’

 

  1. T1 - ranges from hypointense to slightly hyperintense (fat content, copper deposition within the tumor, degree of differentiation)
  2. T2 -, most demonstrate increased signal, tend to be inhomogeneous

Contrast MR

  1. Helps in   characterizing and detecting small HCC in patients with underlying cirrhosis.
  2. T1 and T2 of the tumors may be similar to surrounding liver
  3. Underlying liver heterogeneity makes HCC detection difficult
  4. Cirrhosis & ascites,  motion artifacts obscure lesions
  5. Dynamic T1 after rapid IV GD - increased lesion conspicuity
  6. Small well diff tumors best detected  in arterial phase

 

Learning points from the case- an attempt has been made to highlight the utility of contrast MR in better characterization of liver lesions. With emergence of various types of liver specific MR contrast agents the characterization of liver lesions has reached closer to pathology. The ultimate aim being a definitive diagnosis noninvasively, which is stil some distance away.


References:
1.Body MR imaging issue of Radiological Clinics of  North America.      
2.Chapter on Liver MR in any standard MRI text.

Dr Paresh Desai Goa