Abstract
PURPOSE: Accurate MRI-based detection of brain metastases (BM) is essential for planning stereotactic radiosurgery (SRS). Although spin-echo (SE) sequences such as T1-SPACE have shown superior lesion detectability compared with gradient-recalled echo (GRE)-based T1-MPRAGE, direct dosimetric comparisons and evaluations of clinical impact are lacking. This study aimed to quantitatively and qualitatively compare T1-SPACE and T1-MPRAGE sequences for SRS planning, focusing on lesion detectability, target volume delineation, dosimetric effects, and oncological outcomes. METHODS: Quantitative, qualitative, and dosimetric analyses were performed in 51 patients who underwent MRI with T1-SPACE and T1-MPRAGE sequences prior to SRS (SPACE group). An experienced neuroradiologist identified BM on both sequences as the reference standard. For outcome evaluation, distant brain metastasis-free survival (DBMFS) and overall survival (OS) were compared between the SPACE group and a matched control group (n = 51) planned exclusively on the T1-MPRAGE sequence. RESULTS: A senior resident identified significantly more BM on T1-SPACE (94.7%) than on T1-MPRAGE (82.4%). T1-SPACE also demonstrated significantly higher contrast and contrast-to-noise ratios (p < 0.001). Dosimetrically, T1-SPACE-based plans showed smaller planning target volumes (p = 0.008) and modest but significant reductions in irradiated brain volumes (V12Gy and V10Gy, both p < 0.05). Patients planned with T1-SPACE had longer DBMFS (10.4 vs. 5.2 months, p = 0.024) and better OS (p = 0.049) compared with the control group. CONCLUSION: The T1-SPACE sequence offers superior lesion detectability, more accurate target delineation, and favorable dosimetric and clinical outcomes in patients with BM. These findings support the implementation of T1-SPACE as a standard imaging sequence for SRS planning in patients with BM. CLINICAL TRIAL NUMBER: Not applicable.