Diffusion and Perfusion MRI Predicts Response Preceding and Shortly After Radiosurgery to Brain Metastases: A Pilot Study

Abstract

To determine the ability of diffusion-weighted imaging (DWI) and dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) to predict long-term response of brain metastases prior to and within 72 hours of stereotactic radiosurgery (SRS). METHODS: In this prospective pilot study, multiple b-value DWI and T1-weighted DCE-MRI were performed in patients with brain metastases before and within 72 hours following SRS. Diffusion-weighted images were analyzed using the monoexponential and intravoxel incoherent motion (IVIM) models. DCE-MRI data were analyzed using the extended Tofts pharmacokinetic model. The parameters obtained with these methods were correlated with brain metastasis outcomes according to modified Response Assessment in Neuro-Oncology Brain Metastases criteria. RESULTS: We included 25 lesions from 16 patients; 16 patients underwent pre-SRS MRI and 12 of 16 patients underwent both pre-and early (within 72 hours) post-SRS MRI. The perfusion fraction (f) derived from IVIM early post-SRS was higher in lesions demonstrating progressive disease than in lesions demonstrating stable disease, partial response, or complete response (q = .041). Pre-SRS extracellular extravascular volume fraction, v e , and volume transfer coefficient, K trans , derived from DCE-MRI were higher in nonresponders versus responders (q = .041). CONCLUSIONS: Quantitative DWI and DCE-MRI are feasible imaging methods in the pre-and early (within 72 hours) post-SRS evaluation of brain metastases. DWI-and DCE-MRI-derived parameters demonstrated physiologic changes (tumor cellularity and vascularity) and offer potentially useful biomarkers that can predict treatment response. This allows for initiation of alternate therapies within an effective time window that may help prevent disease progression.

Analysis of Key Clinical Variables and Radiological Manifestations Associated with the Treatment Response of Patients with Brain Metastases to Stereotactic Radiosurgery

“…In this study, almost all the BM before SRS treatment showed hyper-intensity on DWI sequence, which may relate to the growth pattern of highly infiltrating tumor cells. After treatment, most tumors showed iso-intensity or hypo-intensity on DWI sequences, regardless of whether they were in the IG or PG, which may relate to tumor cell necrosis caused by radiation [ 41 ]. Therefore, there was no statistically significant difference in DWI sequence signals between the IG and PG.…”

An interdisciplinary consensus on the management of brain metastases in patients with renal cell carcinoma

“…With conventional MRI of the brain, no discrimination between pseudoprogression and true progression can be made. Advanced imaging techniques can be deployed (see Table 3), [38][39][40][41][42][43][44] but it remains uncertain whether any of these provide sufficient information to discriminate between tumor progression and therapy-related abnormalities.…”

Brain metastases: the role of clinical imaging

“…On DWI, ADC is usually low in tumour tissue and high in RN, although this distinction is not universal. 73 Using MRS, Cho/Cr-ratio and Cho/N-acetyl-aspartate (NAA)-ratio were found to be higher in tumour than in RN. 74 In MET-PET, uptake is usually higher in progressive BMs than in RN; FDOPA- and FET-PET have also shown a potential discriminating ability in smaller studies.…”