Diffusion-Weighted Imaging of Surgically Resected Hepatocellular Carcinoma: Imaging Characteristics and Relationship Among Signal Intensity, Apparent Diffusion Coefficient, and Histopathologic Grade
July 21st, 2009 Posted by: admin
OBJECTIVE. The objective of our study was to determine the
relationship between the signal intensity of hepatocellular carcinoma (HCC)
assessed with diffusion-weighted imaging (DWI) and T2-weighted imaging and the
apparent diffusion coefficient (ADC) with the histopathologic grade of each
nodule.
MATERIALS AND METHODS. MR examinations including DWI and T2-weighted
imaging of 125 surgically resected hypervascular HCCs in 99 patients were
retrospectively reviewed. Pathologic examinations revealed 25 well-, 61
moderately, and 39 poorly differentiated HCCs. Two radiologists reviewed the
images and classified the signal intensity of each tumor on DWI and
T2-weighted imaging by mutual agreement. The incidence of each signal
intensity and the relationship between signal intensity and histopathologic
grade were assessed for each sequence. The relationship between the ADC and
histopathologic grade was also evaluated.
RESULTS. On DWI, 11 of 125 HCCs appeared hypo- to isointense, 27
tumors appeared slightly hyperintense, and the remaining 87 tumors appeared
obviously hyperintense to the surrounding liver. Overall, 91.2% (114/125) of
HCCs showed hyperintensity to the surrounding hepatic parenchyma. Statistical
analysis showed that this rate on DWI was significantly higher than that on T2
turbo spin-echo (TSE) imaging (p < 0.001). On DWI, the tumors
tended to show a brighter signal with rising histopathologic grade (p
= 0.031), but this trend was not observed on T2-weighted imaging. ADC
measurements revealed that the mean ADCs of well-, moderately, and poorly
differentiated HCCs were approximately 1.45, 1.46, and 1.36 x
10–3 mm2/s, respectively. There was no significant
correlation between ADC and histopathologic grade.
CONCLUSION. The histopathologic grade of HCC had no correlation with
the ADC, but HCC tumors tended to show a higher signal on DWI as the
histopathologic grade rose. However, predicting the correct histopathologic
grade of each HCC before surgery on the basis of DWI findings was difficult
because of the large overlap among histopathologic grades.
