Room: AAPM ePoster Library
Purpose: is a common treatment for brain neoplasms and is used alone or in combination with other therapies. however, there are many unanswered questions regarding radiotherapy effects in the normal brain surrounding or infiltrated by tumor. Changes to the vascular and parenchyma have been documented, and more recently inflammatory mechanisms have been postulated to play a role in radiation injury. Traditional imaging techniques are often lacking in their ability to differentiate between recurrent tumor, transient treatment effects, or radiation necrosis. The primary goal of this project to commission fast post-processing technique, STAGE into the routine MRI only RT and shows it can generate qualitative images such as Susceptibility-Weighted Imaging (SWI), Quantitative Susceptibility Mapping (QSM) and apparent traverse relaxation (R2*) which are help to map out the vascular changes and neuroinflammatory components that could predict sub-acute and long-term radiation effects.
Methods: finalized MRI-only SRS planning for frameless patients using MRI-compatible Type S overlay (CIVCO) on an Aera 1.5T Siemens RT edition. Protocol: 1) field map (1 minute)—geometric correction; 2) T1 MPRAGE (5 min)—Anatomical and planning; 3) Synthetic CT sequences (6 minutes)—planning; 4) STAGE pre-contrast—generate T1-weighted, T1 map, T2-weighted, PD map, PD weighted, susceptibility weighted imaging (SWI), quantitative susceptibility mapping (QSM), T2*, R2*, FLAIR (10 minutes); 5) STAGE post-contrast Gd (4 min)—vascular imaging, simultaneous magnetic resonance angiography and venography (MRAV)—(total scanning time 26 minutes).
Results: pre- and post-processing to generate quantitative and vascular MR images provides substantial information regarding tumor location, surroundings, and extent, which improves tumor segmentation and renders more precise treatment planning
Conclusion: initially optimized the protocol on one healthy volunteer and twenty patients. Our neuroradiologic and radiation oncology team will help us further study these cases retrospectively and correlate the new tumor regions with SRS patient outcomes.