FLAIR-HASTE Sequence in Differential Diagnosis of Focal Hepatic Lesions

Kim, Yong Jae; Kim, Tae Kyoung; Bae, In Young; Kim, Pyo Nyun; Ha, Hyun Kwon; Kim, Ah Young; Lee, Moon Gyu

Abstract

PURPOSE: To assess the feasibility of using the FLAIR (fluid-attenuated inversion recovery)-HASTE (half-fourier acquisition single-shot turbo spin-echo) sequence for the differential diagnosis of focal hepatic lesions.
MATERIALS AND METHODS
During a 12-month period, 80 patients with 127 focal hepatic lesions [hemangiomas (n=60), hepatocellular carcinomas (HCC) (n=27), cysts (n=25), and metastases (n=15)] underwent MR imaging using a 1.5-T scanner. Verification of the diagnosis was based on the findings of pathology (n=11), of angiography and clinical investigation (n=17), or of dynamic contrast-enhanced MR imaging (n=99). MR sequences included T2-weighted HASTE (TE, 134 ms; echo space, 4.4 ms), FLAIR-HASTE (TE, 64 ms; echo space, 4.4 ms; inversion time, 2000 ms; number of slices, 5 -9; acquisition time, 13 -20 s), and dynamic gadolinium-enhanced T1-weighted FLASH (TR, 131 ms; TE, 4 ms). FLAIR-HASTE imaging was of any focal lesions seen on T2-weighted HASTE images was performed in the liver area, and their signal intensity was classified in one of five ways: very high (higher than the spleen), moderately high (similar to the spleen), slightly high (higher than the liver and lower than the spleen), intermediate (similar to the liver), or low (lower than the liver).
RESULTS
The signal intensity of the 25 cysts, as determined by FLAIR-HASTE, was low in 21 cases (84%), intermediate in three (12%), and very high in one (4%), which was diagnosed as a complicated cyst in which ultrasound revealed internal septa. At FLAIR-HASTE, all 60 hemangiomas showed either very high (n=50, 83%) or moderately high (n=10, 17%) signal intensity, while that of 42 hepatic malignant tumors was very high in 14 cases (33%), moderately high in 8 (19%), slightly high in 18 (43%), intermediate in one (2.5%), and low in one (2.5%).
CONCLUSION
FLAIR-HASTE showed that the signal intensity of the majority of hepatic cysts was low, while that of most hemangiomas and solid liver tumors was high. For the differentiatial diagnosis of cystic and non-cystic liver lesions, FLAIR-HASTE is an easily applicable MR imaging sequence.