Intra-individual comparison of image contrast in SPIO-enhanced liver MRI at 1.5T and 3.0T.

The purpose of the study was to examine if the higher susceptibility at 3.0 Tesla (T) compared to 1.5 T will affect the contrast in MR imaging of the liver after application of superparamagnetic iron oxide particles (SPIO). The study was approved by our institutional review board and informed consent was obtained. Seventeen healthy volunteers were examined in a prospective, intra-individual comparative study within one day on a 1.5 T and a 3.0 T MRI system. T2 weighted TSE sequences were acquired after bolus injection of a SPIO contrast agent. Image contrast and signal to noise ratio (SNR) were compared between the field strengths. Image contrast was calculated between the liver tissue and the kidneys / spleen / muscles and fluids. The students'T-test was used for statistical analysis. No influence of the higher field strength could be observed on image contrast except for the liver / muscle contrast. This was due to a distinct SNR increase of the muscle tissue at 3.0 T as a result of their relaxation properties. The higher susceptibility at 3.0 T compared to 1.5 T does not translate into a stronger signal attenuation of the SPIO enhanced liver parenchyma.

High-field-strength MR imaging of the liver at 3.0 T: intraindividual comparative study with MR imaging at 1.5 T.

PURPOSE: To prospectively evaluate whether magnetic resonance (MR) imaging of the liver at 3.0 T is comparable to that at 1.5 T with respect to image artifacts, image quality, and diagnostic utility in terms of detection and characterization of focal liver lesions in patients with these lesions. MATERIALS AND METHODS: Patients provided informed consent after the study had been explained, and the institutional review board approved the study protocol. An intraindividual comparative study was performed in 21 patients (12 men and nine women; mean age, 58.7 years; range, 36-76 years) with a total of 79 focal liver lesions (benign and malignant) who were examined at 1.5- and 3.0-T MR imaging within 1 week. The imaging protocol consisted of T2-weighted turbo spin-echo (SE) sequences with or without fat suppression, as well as T1-weighted gradient-echo (GRE) sequences with or without gadolinium-based contrast agent. All images were rated independently by two radiologists with respect to types of artifacts (susceptibility, motion, pulsation, image homogeneity, and electrodynamic effects) and in regard to detectability and characterization of focal liver lesions. A modified sign test was used for statistical analysis (alpha < .2). RESULTS: Motion artifacts were significantly more pronounced in non-fat-suppressed T2-weighted turbo SE images at 3.0 T (P = .03), whereas pulsation artifacts were more pronounced (P = .19) in precontrast T1-weighted GRE 1.5-T images. No statistically significant differences (P < .2) were observed for the remaining artifacts and sequences. Of the 79 index lesions, a total of 76 were prospectively identified at 1.5-T imaging and a total of 77 were identified at 3.0-T imaging. CONCLUSION: MR imaging of the liver at 3.0 T, compared with that at 1.5 T, is feasible with equivalent image quality and diagnostic utility in terms of detection and characterization of focal liver lesions.