Differentiation of hepatocellular carcinoma and hepatic metastasis from cysts and hemangiomas with calculated T2 relaxation times and the T1/T2 relaxation times ratio.

Purpose: To determine the diagnostic capability of the T1 and T2 relaxation times and the T1/T2 relaxation times ratio generated with the mixed turbo spin echo (mixed-TSE) pulse sequence, in order to discriminate between hepatocellular carcinoma (HCC)/metastases and hemangiomas/cysts.

Materials And Methods: A retrospective review of 36 MR examinations implementing the mixed-TSE pulse sequence demonstrated 70 focal hepatic lesions. Quantitative MR algorithms were used to generate T1 and T2 relaxation times, and the T1/T2 relaxation times ratio for each lesion. A two-sample t-test compared mean T1 and T2 relaxation times, and the T1/T2 relaxation times ratio, by lesion type: carcinoma/metastases and hemangiomas/cysts. Sensitivity and specificity for discriminating carcinoma/metastases from hemangiomas/cysts with T2 relaxation time thresholds of 112 and 125 msec, as well as a ratio of T1/T2 relaxation times of 5.8, were calculated.

Results: Using a T2 relaxation time threshold of 112 msec, 92% sensitivity and 100% specificity discriminating cysts/hemangiomas from HCC/liver metastasis was demonstrated. With a threshold of 125 msec, 96% sensitivity and 98% specificity was demonstrated. There was no correlation between calculated T1 relaxation times and type of lesion. Using a T1/T2 relaxation times ratio of 5.8, 100% sensitivity and specificity were demonstrated.

Conclusion: Although there is high sensitivity and specificity associated with the use of T2 relaxation times alone to discriminate carcinoma/metastases from hemangiomas/cysts, using the T1/T2 relaxation times ratio threshold of 5.8 allowed proper classification of all lesions.