Breath-Hold MR Imaging of Focal Hepatic Lesions: Clinical Usefulness of Breath-Hold TSE T2WI Combined by Fast Low-Angle Shot (FLASH) MR Imaging

Abstract

PURPOSE: To compare the image quality and diagnostic efficacy of turbo spin-echo (TSE) T2WI with breath-holdturbo SE T2WI and to evaluate the clinical usefulness combined breath-hold turbo SE T2WI with FLASH(fast low-angleshot) MR imaging for the evaluation of focal hepatic lesions. MATERIALS AND METHODS: A total of 47 patients with known or suspected hepatic mass were prospectively evaluated using a commercially available 1.5-T MR system. All patients were examined with conventional spin-echo T1WI, TSE T2WI, breath-hold TSE T2WI, and T1-weighted FLASHwith and without Gd-DTPA. The images were compared quantitatively (liver-lesion C/N ; CNR [contrast-to-noiseratio] and lesion detectability) and qualitatively (sharpness of anatomic structure, artifact, and overall imagequality). RESULTS: A total of 69 hepatic lesions were detected in 47 patients. Sixty-seven lesions (97.1%) were detected with Gd-FLASH, 66 (95.7%) with TSE T2WI, 65 (94.2%) with breath-hold TSE T2WI, 62 (89.9%) withnon-enhanced FLASH, and 55 (79.7%) with conventional SE T1WI. The CNR of cysts and hemangiomas was significantly greater on turbo SE T2WI and breath-hold TSE T2WI than on other sequences, but there was no significant difference between turbo SE T2WI and breath-hold TSE T2WI. For solid lesions, CNR was greatest on turbo SE T2WI and was similar on breath-hold TSE T2WI and Gd-FLASH without statistical significance, but was significantly higher than conventional SE T1WI. Breath-hold TSE T2WI and Gd-FLASH were qualitatively superior to other sequences except the vascular pulsation artifact of FLASH. Non-enhanced FLASH was also superior to conventional T1WI for CNR, lesion detectability, sharpness, respiratory motion artifact, and overall image quality. CONCLUSION: Breath-hold TSET2WI may replace turbo SE T2WI, and as well as conventional SE T1WI, FLASH with or without Gd-DTPA may be used for the evaluation of focal hepatic lesions. The combination of FLASH and breath-hold TSE T2WI may be an excellent technique that can be used to rapidly evaluate liver lesions, and at the same time offer superior overall imagequality.