Keywords : Apparent Diffusion Coefficient (ADC)
Diffusion Weighted MRI in Evaluation of Focal Liver Lesions
European Journal of Molecular & Clinical Medicine,
2022, Volume 9, Issue 6, Pages 1459-1468
Background: The present study was undertaken to determine the role of noncontrast MRI and diffusion weighted imaging in particular along with the corresponding ADC values in the identification and characterization of the focal liver lesions. The study proposes to set forth a cut off ADC value for quickly differentiating between benign and malignant hepatic focal lesions.
Materials and Methods: 70 patients who were referred to our department with strong clinical suspicion of focal liver lesion and those diagnosed by ultrasonography followed by multiphasic contrast enhanced CT underwent non-contrast Magnetic Resonance Imaging evaluation of abdomen using 1.5 T 8 channel MRI. The MRI scans were then reviewed and various focal liver lesions were identified.
Results: The MRI and DWI picked up more focal lesions compared to both USG and Multiphasic CT alone. Ultrasonography shows a sensitivity of 73% though its specificity was a good 88% in predicting malignancy. Multi phasicCT shows a sensitivity of 88% and specificity of 93% in differentiating benign from malignant focal lesion. DWI and ADC values have very good sensitivity and NPV of 97% and 98% respectively for malignant focal liver lesions. The drop in specificity and PPV of ADC values when compared to combined MRI findings of 93% and 91% is mainly due to the low ADC values obtained for abscess. A cut off ADC value of 1.4 x 10-3 mm2/s is considered for differentiating benign from malignant lesions. Difference in mean ADC values of malignant and nonmalignant lesions is highly significant.[P=0.00001].
Conclusion: The sensitivity of noncontrast MRI with DWI and ADC values was very high and more than both USG and contrast enhanced Multiphasic CT. The specificity of MRI was comparable to that of CE- Multiphasic CT in diagnosing malignant focal liver lesions. A cut off ADC value of 1.4 x 10-3 mm2/s was found to be a superior, noninvasive tool for differentiating malignant from benign lesions without the risk of radiation, contrast media and invasiveness. Hence, MRI with DWI in particular is a very valuable noninvasive tool for the identification and characterization of focal liver lesions.