Short tau inversion recovery (STIR) after intravenous contrast agent administration obscures bone marrow edema-like signal on forefoot MRI.

OBJECTIVE: Short tau or short TI inversion recovery (STIR) MRI sequences are considered a robust fat suppression technique. However, STIR also suppresses signals from other tissues with similar T1 relaxation times. This study investigates the in vivo effect of intravenous gadolinium-based T1-shortening contrast agent on STIR signal. MATERIALS AND METHODS: Institutional board approval and informed consent was obtained. MRI examinations (1.5-T or 3-T) of 31 prospectively included patients were analyzed by two readers. Signal intensity of degenerative bone marrow edema-like signal at the Lisfranc joint on precontrast STIR images and on STIR images acquired after intravenous contrast agent administration (gadoteric acid, gadolinium: 0.5 mmol/ml, 15 ml) was measured. The medial cuneiform bone without observable bone marrow edema-like signal was considered a healthy tissue and served as a reference. Relative changes in signal intensity between precontrast and postcontrast images were calculated for the two tissues. Wilcoxon signed-rank test served for statistical analyses. RESULTS: In bone marrow edema-like signal, both readers observed a median signal change of -35% (interquartile range (IQR) 24) and -34% (IQR 21), respectively, on postcontrast STIR images compared to precontrast STIR. In healthy tissue, the signal remained constant on postcontrast STIR images (median change -2%, IQR 15, and 0%, IQR 17) respectively. For both readers, postcontrast signal change in bone marrow edema-like signal differed from that in healthy tissue (p < 0.001). CONCLUSION: Intravenous gadolinium-based contrast agent causes a significant reduction of signal intensity in bone marrow edema-like signal on routine STIR images. Thus, pathological MRI findings may be obscured.

MRI study of changes in knee bone marrow edema-like signal in asymptomatic amateur marathon runners before and after half-marathon running.

OBJECTIVE: To evaluate the incidence of knee bone marrow edema-like signal and its changes before and after running a half marathon running in asymptomatic amateur marathon runners to explore the impact of the half marathon on knee bone marrow edema-like signal. METHODS: 50 asymptomatic amateur marathon runners (30 males, 20 females) were recruited. T1-weighted imaging (T1WI), fat-suppressed protein density weighted imaging (fs-PDWI) and three-dimensional double-echo steady-state (3D-DESS) sequence on the right knee were performed before and within 3 h after a half-marathon running. 20 healthy volunteers were recruited as control. According to the whole-organ magnetic resonance imaging score (WORMS) system, the involvement of bone marrow edema-like signal in 15 regions of knee was graded from 0 to 3. The results were classified and Mann Whitney U test was used for comparison between groups. RESULTS: The total incidence of bone marrow edema-like signal in amateur marathon group was 62%. Among them, the incidence of grade 1-3 was 48% (24/50), 12% (6/50), 2% (1/50), respectively, which was statistically significant compared with the controls (P = 0.007). There was no significant difference between gender before running (P = 0.172) and after running (P = 0.162). There was no significant difference before and after running (P > 0.05). However, 3 subjects showed new lesions, 8 subjects showed progression and 4 subjects showed decreased signal. CONCLUSION: The occurrence of knee bone marrow edema-like signal in amateur marathon runners is more common. The lesions of bone marrow edema-like signal will show aggravation or improvement in a certain extent after the half marathon.