Differentiating brain metastasis from glioblastoma by time-dependent diffusion MRI

Background This study was designed to investigate the use of time-dependent diffusion magnetic resonance imaging (MRI) parameters in distinguishing between glioblastomas and brain metastases. Methods A retrospective study was conducted involving 65 patients with glioblastomas and 27 patients with metastases using a diffusion-weighted imaging sequence with oscillating gradient spin-echo (OGSE, 50 Hz) and a conventional pulsed gradient spin-echo (PGSE, 0 Hz) sequence. In addition to apparent diffusion coefficient (ADC) maps from two sequences (ADC 50Hz and ADC 0Hz ), we generated maps of the ADC change (cADC): ADC 50Hz − ADC 0Hz and the relative ADC change (rcADC): (ADC 50Hz − ADC 0Hz )/ ADC 0Hz × 100 (%). Results The mean and the fifth and 95th percentile values of each parameter in enhancing and peritumoral regions were compared between glioblastomas and metastases. The area under the receiver operating characteristic curve (AUC) values of the best discriminating indices were compared. In enhancing regions, none of the indices of ADC 0Hz and ADC 50Hz showed significant differences between metastases and glioblastomas. The mean cADC and rcADC values of metastases were significantly higher than those of glioblastomas (0.24 ± 0.12 × 10 −3 mm 2 /s vs. 0.14 ± 0.03 × 10 −3 mm 2 /s and 23.3 ± 9.4% vs. 14.0 ± 4.7%; all p < 0.01). In peritumoral regions, no significant difference in all ADC indices was observed between metastases and glioblastomas. The AUC values for the mean cADC (0.877) and rcADC (0.819) values in enhancing regions were significantly higher than those for ADC 0Hz 5th (0.595; all p < 0.001). Conclusions The time-dependent diffusion MRI parameters may be useful for differentiating brain metastases from glioblastomas.