Focal liver lesions: Breathhold gradient- and spin-echo T2-weighted imaging for detection and characterization

Purpose: To evaluate breathhold gradient- and spin-echo (GRASE) T2-weighted imaging for the detection and characterization of focal liver lesions. Materials and Methods: Two GRASE sequences with different echo times (75 and 90 msec, GRASE₇₅ and GRASE₉₀) were compared with respiratory-triggered fast spin-echo (SE) and breathhold fast SE in 64 patients with 103 malignant and 51 benign lesions. Compared with respiratory-triggered and breathhold fast SE, GRASE reduced scan time by 77% to 82% and 21% to 27%, respectively. Two independent readers evaluated image quality and reviewed 504 liver segments on a segment-by-segment basis. Observer performance was evaluated with receiver operating characteristic (ROC) curve analysis. The signal-to-noise ratio (SNR) of liver and spleen, and lesion-to-liver contrast-to-noise ratio (CNR) were also measured. Results: The overall quality of the GRASE images was higher than that of the respiratory-triggered and breathhold fast SE images, although signal inhomogeneities were more frequently observed with GRASE. No significant difference in the values of the area under the ROC curve (Az) for malignant lesion detection was found. The mean SNR and CNR were highest for respiratory-triggered fast SE. Conclusion: T2-weighted breathhold GRASE has the potential to provide faster liver imaging.