Dedicated SRS imaging improves brain metastases detection and reduces the intracranial relapse risk
OC-0928
Abstract
Dedicated SRS imaging improves brain metastases detection and reduces the intracranial relapse risk
Authors: Rupesh Kotecha1, Tugce Kutuk2, Kevin Jay Abrams3, Martin C Tom2, Haley Appel2, Matthew D Hall2, Ranjini Tolakanahalli2, D Jay J Wieczorek2, Michael W McDermott4, Manmeet S Ahluwalia5, Minesh P Mehta2
1Miami Cancer Institute, Baptist Health South Florida, Radiation Oncology, Miami , USA; 2Miami Cancer Institute, Baptist Health South Florida, Radiation Oncology, Miami, USA; 3Miami Cancer Institute, Baptist Health South Florida, Diagnostic Radiology, Neuroradiology, Miami, USA; 4Miami Cancer Institute, Baptist Health South Florida, Neurosurgery, Miami, USA; 5Miami Cancer Institute, Baptist Health South Florida, Medical Oncology, Miami, USA
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Purpose or Objective
Primary stereotactic radiosurgery (SRS) is increasingly being utilized for patients with brain metastasis, yet the risk of distant intracranial failure continues to be the principal disadvantage of this focal therapeutic approach. The objective of this study was to determine if advanced dedicated treatment planning images at the time of SRS would improve individual lesion detection and consequentially reduce the perceived rate of intracranial relapse.
Material and Methods
Patients treated with SRS for brain metastasis at a single tertiary care institution underwent dedicated treatment planning MRIs including a high-resolution three-dimensional (3D) magnetization-prepared rapid acquisition with gradient echo (MPRAGE) sequence as well as an optimized 3D fast/turbo SE sequence (sampling perfection with application-optimized contrasts using different flip angle evolutions [SPACE]) from 2020-2021. Distant intracranial failure was calculated using the Kaplan-Meier method and comparisons were made to a retrospective cohort of patients treated with MPRAGE images alone for treatment planning.
Results
134 patients underwent 170 courses of SRS for 821 brain metastases imaged with both dedicated treatment planning sequences from 02/20 to 01/21. Only 679 (82.7%) lesions were detected by neuro-radiologists on MPRAGE imaging alone; with both MPRAGE and SPACE sequences, this improved to 787 (95.9%), a 15.9% improvement in detection rate; an additional 34 lesions, 4.1% were confirmed by multi-disciplinary review of both imaging sequences with neuro-radiology, neurosurgery, and radiation oncology at the time of treatment. For the 142 (17.3%) lesions not detected on MPRAGE alone, the median metastasis size was 2.8 mm (Range: 0.7-6.6 mm). These were categorized into 5 classifications: 57 (40.1%) were located on a gyrus; 51 (35.9%) were located within 3 mm of a cortical vessel; 29 (20.4%) were within 5 mm of the external brain contour; 23 (16.2%) were within 3 mm of a venous sinus; and 23 (16.2%) were within 3 mm of enhancing dura. On comparison to a cohort of consecutive historical patients (103 patients, 133 SRS courses, 479 brain metastases) treated between 02/19 and 01/20 with SRS based on planning using MPRAGE sequences only, patients treated using MPRAGE with SPACE images had improved median time to distant intracranial failure (13.5 vs. 5.1 months, p<0.005). The benefit was even more pronounced for patients treated for their first course of SRS (18.4 vs. 6.3 months, p<0.001).
Conclusion
Multi-disciplinary peer review with dedicated SRS imaging sequences substantially improved detection of small brain metastases, which were primarily located in regions in proximity to areas of normal contrast uptake. This approach was associated with a clinically and statistically significant prolongation to distant intracranial failure and decreased need for salvage therapies, especially for patients undergoing their first course of SRS.