Top Line: Do more sensitive MRI sequences reduce the risk of requiring salvage whole brain RT in patients treated with SRS for brain metastases?
The Study: Thin slice, 3D T1 plus contrast MRI images are the standard method for identifying and delineating brain metastases for SRS. MPRAGE (magnetization prepared rapid gradient echo) is one of the dominant techniques for generating 3D T1 images. SPACE (sampling perfection with application-optimized contrasts by using different flip angle evolutions) is another sequence used to generate 3D images, and it has been shown to be better at detecting brain metastases. CYBER-SPACE was a phase 2 trial where 202 patients with 1-10 brain metastases were randomized to receive SRS based on either MPRAGE or SPACE MRI sequences. All patients were treated on CyberKnife using a 1 mm PTV margin with dose prescribed to the 70% isodose line. Lesions <2 cm received 20 Gy in 1 fraction, 2-3 cm lesions received 18 Gy in 1 fraction, and 3-4 cm lesions received 30 Gy in 5 fractions. SRS was repeated as long as there were fewer than 10 lesions per recurrence and no leptomeningeal disease. The primary outcome was freedom from whole brain radiation. Using the SPACE sequence did not significantly improve the rate of WBRT-free survival at 12 months (78.5% v 76%) or 24 months (73.5% v 71%). The most common reasons for WBRT were >10 mets (65%), leptomeningeal disease (22.5%), or both (12.5%). The rate of neurologic death was 10%.
TBL: In this trial, the more sensitive SPACE sequence did not significantly reduce the rate of salvage whole brain radiation in patients initially treated with SRS for 1-10 brain metastases. | El Shafie, Neuro Oncol 2024
The Study: Thin slice, 3D T1 plus contrast MRI images are the standard method for identifying and delineating brain metastases for SRS. MPRAGE (magnetization prepared rapid gradient echo) is one of the dominant techniques for generating 3D T1 images. SPACE (sampling perfection with application-optimized contrasts by using different flip angle evolutions) is another sequence used to generate 3D images, and it has been shown to be better at detecting brain metastases. CYBER-SPACE was a phase 2 trial where 202 patients with 1-10 brain metastases were randomized to receive SRS based on either MPRAGE or SPACE MRI sequences. All patients were treated on CyberKnife using a 1 mm PTV margin with dose prescribed to the 70% isodose line. Lesions <2 cm received 20 Gy in 1 fraction, 2-3 cm lesions received 18 Gy in 1 fraction, and 3-4 cm lesions received 30 Gy in 5 fractions. SRS was repeated as long as there were fewer than 10 lesions per recurrence and no leptomeningeal disease. The primary outcome was freedom from whole brain radiation. Using the SPACE sequence did not significantly improve the rate of WBRT-free survival at 12 months (78.5% v 76%) or 24 months (73.5% v 71%). The most common reasons for WBRT were >10 mets (65%), leptomeningeal disease (22.5%), or both (12.5%). The rate of neurologic death was 10%.
TBL: In this trial, the more sensitive SPACE sequence did not significantly reduce the rate of salvage whole brain radiation in patients initially treated with SRS for 1-10 brain metastases. | El Shafie, Neuro Oncol 2024