MR differentiation of hepatocellular carcinoma from cavernous hemangioma: complementary roles of FLASH and T2 values.

Forty-two patients with hepatocellular carcinoma (hepatoma) and 18 patients with hemangioma were studied with MR imaging at 1.5 T to evaluate the efficacy of single-slice breath-hold FLASH (fast low-angle shot) images in distinguishing between the lesions and to compare with T2 differentiation using conventional spin-echo images. The difference between mean tumor-to-liver signal ratio on FLASH imaging of hepatocellular carcinoma (1.46 +/- 1.06) and hemangioma (0.86 +/- 0.45) was statistically significant (p less than .01). Fifty-one (82%) of 62 lesions were classified correctly when the borderline of tumor-to-liver signal ratio between hepatoma and hemangioma was set at 0.9. The mean T2 values of hepatomas and hemangiomas were 48 +/- 10 msec and 89 +/- 20 msec, respectively. Fifty-seven (92%) of 62 lesions were correctly diagnosed with the T2 borderline of 80 msec. The five misdiagnosed lesions with the T2 borderline were hemangiomas smaller than 2 cm with tumor-to-liver signal ratios less than 0.9. FLASH images appear promising for differentiating between hepatoma and hemangioma, and they complement T2 values in characterizing small lesions.