Contrast-enhanced MRI better detected hepatocellular carcinomas than diffusion-weighted MRI, but the two in combination slightly increased detection rates in a recent study.
In the single-center retrospective study, researchers evaluated 52 patients with cirrhosis who had received diffusion-weighted magnetic resonance imaging (DWI) and contrast-enhanced T1-weighted imaging (CET1WI) within 90 days of liver transplantation. Two independent radiologists evaluated the resulting images for detection of hepatocellular carcinoma (HCC) over three sessions — DWI images, CET1WI images, and all images together — and calculated sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively), per-patient accuracy and per-lesion PPV for each set of images.
Seventy-two HCCs were detected in 33 patients, with a mean size of 1.5 cm. The total included 24 well-differentiated, 36 moderately differentiated and 12 poorly differentiated tumors. The CET1WI set of images had significantly higher per-patient sensitivity (87.9% vs. 75.8%, P=.02), and NPV (79.5% vs. 66%, P=.03) compared with the DWI set according to pooled data from both observers.
Per-lesion sensitivity also was significantly greater in the CET1WI set (59.0% compared with 43.8%, P=.008), but the difference remained statistically significant only for lesions between 1 cm and 2 cm when stratified by lesion size (74% CET1WI compared with 42.0% DWI, P=.001). Sensitivity was low using both methods for lesions less than 1 cm (31.8% CET1WI vs. 25.8% DWI, P=.44), and was high for lesions more than 2 cm (96.4% CET1WI vs. 89.3% DWI, P=.43). Other evaluated factors were equivalent between the two methods.
The addition of DWI to CET1WI did not significantly improve diagnostic sensitivity per patient for either observer, but did improve sensitivity per lesion for the more experienced radiologist (62.5% in CET1WI set compared with 72.2% in combined set, P=.02).
“We have demonstrated that DWI is outperformed by CET1WI for the detection of HCC on a per-patient and per-lesion basis,” the researchers wrote, “but represents a reasonable alternative to CET1WI for detection of HCCs [greater than] 2 cm. We have also demonstrated that the addition of DWI to CET1WI slightly increases the detection rate. Therefore, we believe that DWI should be added to routine [magnetic resonance] protocols tailored toward HCC detection, but cannot replace contrast-enhanced MRI at this point