Image quality and focal lesion detection on T2-weighted MR imaging of the liver: comparison of two high-resolution free-breathing imaging techniques with two breath-hold imaging techniques

Abstract

Purpose: To evaluate image quality and accuracy for the detection of focal hepatic lesions depicted on T2-weighted images obtained with two high-resolution free-breathing techniques (navigator-triggered turbo spin-echo [TSE] and respiratory-triggered TSE) and two standard-resolution breath-hold techniques (breath-hold TSE with restore pulse and half-Fourier acquisition single-shot TSE [HASTE]).

Materials and methods: Our institutional review board approved this study, and written informed consent was obtained from all patients. Two readers independently reviewed 200 T2-weighted imaging sets obtained with four sequences in 50 patients. Both readers identified all focal lesions in session 1 and only solid lesions in session 2. The readers' confidence was graded using a scale of 1-4 (1 <or= 50%; 4 >or= 95%). The diagnostic accuracies of the four MR sequences were evaluated using the free-response receiver operating characteristic (ROC) method. Region-of-interest (ROI) measurements were performed for the mean signal intensity (SI) in the liver, spleen, hepatic lesions, and background noise.

Results: The accuracy of navigator-triggered TSE and respiratory-triggered TSE was superior to that of breath-hold TSE with restore pulse and HASTE for the detection of all focal or solid hepatic lesions. The mean lesion-to-liver contrast-to-noise ratio (CNR) of solid lesions in navigator-triggered (P < 0.001) and respiratory-triggered TSE (P < 0.005) was significantly higher than that in HASTE.

Conclusion: High-resolution, free-breathing, T2-weighted MRI techniques can significantly improve the detectability of focal hepatic lesions and provide higher lesion-to-liver contrast of solid lesions compared to breath-hold techniques.