Accuracies of Chemical Shift In/Opposed Phase and Chemical Shift Encoded Magnetic Resonance Imaging to Detect Intratumoral Fat in Hepatocellular Carcinoma

Background Magnetic Resonance Imaging ( MRI) being a noninvasive modality may help in preoperative evaluation of intratumoral fat in hepatocellular carcinoma (HCC) using chemical shift encoded (CSE) MRI and in‐/opposed‐phase (IOP) imaging sequences. Purpose To compare the diagnostic accuracy of chemical shift encoded fat fraction at three different flip angles (FAs) using quantitative chemical shift encoded MRI (CSE‐MRI) with in‐/opposed phase (IOP) imaging to evaluate intratumoral fat in HCC. Study Type Retrospective. Population Eighty‐six patients with 87 pathology proven HCCs. Field Strength/Sequence IOP (LAVA‐Flex) and CSE‐MRI (IDEAL IQ) a three‐dimensional spoiled gradient‐echo pulse sequences acquired at 3 T. Assessment Regions of interest (ROIs) were manually drawn by two observers in the tumors to measure mean fat fractions. Surgical specimens were reassessed for intratumoral fat content. Signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) were assessed for CSE‐MRI sequence at FA 3°, 8°, and 9°. Statistical Tests Intraclass correlation coefficient (ICC) was expressed in terms of inter‐ and intra‐observer agreements. Receiver operating characteristic curve analysis was performed for the diagnostic performance followed by combined metric of both. SNR/CNR were analyzed by Kruskal–Wallis test. Results Excellent inter‐ and intra‐observer agreements (ICC >0.95, P < 0.001) were observed for both IOP and CSE‐MRI. IOP (86.4%) showed higher sensitivity than CSE‐MRI at FA 3° (72.5%), FA 8° (76.4%) and FA 9° (76.3%). In contrast, the specificity for CSE‐MRI at FA 3° (86%), FA 8° (87%), and FA 9° (87%) were greater than IOP (72%). A combined metric of IOP and CSE‐MRI derived fat fractions at FA 8° gave highest AUC of 87% and accuracy of 86%. SNR and CNR for CSE‐MRI were significantly higher at FA 8° and FA 9° than FA 3° ( P < 0.05). Data Conclusion IOP and quantitative CSE‐MRI are both feasible methods to detect intratumoral fat in HCC with higher accuracy and SNR for CSE‐MRI at FA 8° and 9°. Level of Evidence 3 Technical Efficacy Stage 2