MRI IN CHARACTERIZATION OF FOCAL LIVER-LESIONS - COMPARISON OF T2 WEIGHTING BY CONVENTIONAL SPIN-ECHO AND TURBO SPIN-ECHO SEQUENCES

Forty-one patients with 61 proved focal liver lesions underwent MRI of the liver at 1.0 T, with the aim of evaluating the usefulness of turb o spin-echo (TSE) sequences in characterizing focal liver lesions, by comparing them with conventional spin-echo (CSE) sequences, Two differ ent TSE protocols were employed, with constant echo time and varying r epetition time: TSE-S (3000 msec) and TSE-L (5100 msec), All images we re evaluated quantitatively (signal-to-noise ratio 'SNR') and qualitat ively: because benign lesions were all liquid (12 cysts and 10 hemangi omas), they were well characterized morphologically on the basis of si gnal intensity, Mean SNR was significantly different between metastase s and benign lesions (P < .0001) with all T2 sequences, Among the sing le T2 sequences tested, logistic regression analysis showed TSE-L to h ave the best predictive ability of the nature of focal lesions, with a G value of 42.02, compared to 29.87 of TSE-S and 25.55 of CSE second echo (SE II), The combination of TSE-L with TSE-S did not modify these results, whereas the combination of TSE-L with CSE only resulted in s light improvement (G = 46.95), Comparison of the receiver operating ch aracteristic (ROC) curves showed only SE II (area under the ROC curve of .8312) to be significantly inferior to the best single sequence, or TSE-L (area under the ROC curve of .9176; P = .027), All sequences we re equivalent in qualitative evaluation, with good reproducibility, se nsitivity ranging from .94 to 1.0, and specificity ranging from .86 to .93, This study confirms the value of TSE sequences in characterizati on of focal liver lesions, Time of acquisition is strongly reduced wit h these sequences, whereas results are fairly similar to those obtaine d with CSE, TSE sequences could therefore replace CSE for the study of focal liver lesions.