%0 Journal Article
%T Accurate, repeatable, and geometrically precise diffusion-weighted imaging on a 0.35 T magnetic resonance imaging-guided linear accelerator.
%A Weygand J
%A Armstrong T
%A Bryant JM
%A Andreozzi JM
%A Oraiqat IM
%A Nichols S
%A Liveringhouse CL
%A Latifi K
%A Yamoah K
%A Costello JR
%A Frakes JM
%A Moros EG
%A El Naqa IM
%A Naghavi AO
%A Rosenberg SA
%A Redler G
%J Phys Imaging Radiat Oncol
%V 28
%N 0
%D 2023 Oct
%M 38045642
暂无%R 10.1016/j.phro.2023.100505
%X <B>UNASSIGNED: </B>Diffusion weighted imaging (DWI) allows for the interrogation of tissue cellularity, which is a surrogate for cellular proliferation. Previous attempts to incorporate DWI into the workflow of a 0.35 T MR-linac (MRL) have lacked quantitative accuracy. In this study, accuracy, repeatability, and geometric precision of apparent diffusion coefficient (ADC) maps produced using an echo planar imaging (EPI)-based DWI protocol on the MRL system is illustrated, and in vivo potential for longitudinal patient imaging is demonstrated.<BR><B>UNASSIGNED: </B>Accuracy and repeatability were assessed by measuring ADC values in a diffusion phantom at three timepoints and comparing to reference ADC values. System-dependent geometric distortion was quantified by measuring the distance between 93 pairs of phantom features on ADC maps acquired on a 0.35 T MRL and a 3.0 T diagnostic scanner and comparing to spatially precise CT images. Additionally, for five sarcoma patients receiving radiotherapy on the MRL, same-day in vivo ADC maps were acquired on both systems, one of which at multiple timepoints.<BR><B>UNASSIGNED: </B>Phantom ADC quantification was accurate on the 0.35 T MRL with significant discrepancies only seen at high ADC. Average geometric distortions were 0.35 (±0.02) mm and 0.85 (±0.02) mm in the central slice and 0.66 (±0.04) mm and 2.14 (±0.07) mm at 5.4 cm off-center for the MRL and diagnostic system, respectively. In the sarcoma patients, a mean pretreatment ADC of 910x10-6 (±100x10-6) mm2/s was measured on the MRL.<BR><B>UNASSIGNED: </B>The acquisition of accurate, repeatable, and geometrically precise ADC maps is possible at 0.35 T with an EPI approach.