Comparison of in-phase and out-of-phase gradient recalled echo T1-weightedpulse sequence for MR imaging of malignant liver masses following administration of paramagnetic gadolinium-chelate

Background: The purpose of this study was to compare the performance of in- phase and out-of-phase gradient recalled echo (GRE) pulse sequences on para magnetic contrast-enhanced magnetic resonance (MR) imaging of malignant liv er lesions. Methods: Fifty patients (27 women, 23 men; mean age 50 +/- 27 years) with k nown or suspected focal liver lesions, nine of whom had a fatty liver, were examined at 1.5 T before and 60 min after injection of gadobenate dimeglum ine at a dose of 0.05 or 0.1 mmol/kg using two GRE techniques: echo time of 2.3 ms (out-of-phase) or 4.6 ms (in-phase). Liver signal-to-noise ratio (S NR) and lesion-liver contrast-to-noise ratio (CNR) were calculated. Results: In patients with a nonfatty liver, liver SNR increased from 26 +/- 9 to 41 +/- 17 on in-phase images and from 28 +/- 8 to 45 +/- 14 on out-of -phase images. In patients with a fatty liver, in-phase images provided sig nificantly higher (p < 0.01) liver SNR than did out-of-phase images predose (34 +/- 8 on in-phase vs. 21 +/- 8 on out-of-phase) and postdose (44 +/- 1 3 on in-phase vs. 33 +/- 14 on out-of-phase). In patients with a nonfatty l iver, lesion-liver CNR was similar on in-phase and out-of-phase images, pre dose and postdose. In patients with fatty liver, lesion-liver CNR was signi ficantly (p < 0.01) lower on out-of-phase images on predose and postdose im ages. Conclusion: In-phase GRE imaging is recommended for imaging focal liver les ions on paramagnetic contrast-enhanced MR imaging in patients with fatty in filtration of the liver.