Imaging manifestations of brain metastases in ultra-long delay-enhanced MRI > 60 min

To compare the imaging manifestations of BM at 3-min and > 60-min delayed-enhanced MRI and explore their imaging characteristics and changing patterns in ultra-long delayed-enhanced MRI > 60 min.

Twenty-six participants with BM were prospectively enrolled from May to October 2019. Contrast-enhanced (CE) T1-weighted imaging (T1WI) was performed for 3 min and > 60 min after contrast injection. BM were defined as regions of interest (ROI_-3min and ROI_-60min). The two ROIs were fused (ROI_-total); the additional display area of the lesion at 3-min (ROI_-A) and > 60-min (ROI_-B) was determined. Signal intensity (SI), volume, and shape differences between ROIs and brain white matter were compared; the imaging characteristics of BM on ultra-long delayed-enhanced MRI were analyzed.

12 males (age: 37-72 [median: 62] years) and 14 females (age: 41-79 [median: 61] years) were included. BM were divided into disappeared (n = 79, 38.0 %) and non-disappeared (n = 129, 62.0 %) groups. The average volume of the two groups at 3-min was 0.18 ± 0.25 and 3.53 ± 10.47 cm³ (p < .05). At > 60-min, BM in the non-disappeared group had four imaging manifestations: adduction (95.3 %), abduction (72.7 %), signal reversal (10.1 %), and filling (38 %) effects. In the non-disappeared group, ROI_-3min, ROI_-60min, ROI_-total, ROI_-A, and ROI_-B volumes averaged 3.53 ± 10.47, 3.72 ± 11.51, 4.06 ± 11.76, 0.36 ± 0.54, and 0.54 ± 1.48 cm³ (p < .05). The DSC obtained from ROI_-3min compared to ROI_-60min was largest in the > 5 cm³ group.

BM changed significantly in > 60-min delayed CE T1WI; no consistent regularity was observed.