ABSTRACT
OBJECTIVES: To determine the feasibility and diagnostic accuracy of fast whole-body magnetic resonance imaging (WB-MRI) compared to whole-body computed tomography (WB-CT) in detecting injuries of slightly to moderately injured trauma patients. MATERIALS AND METHODS: In a prospective single-center approach, trauma patients from convenience sampling with an expected Abbreviated Injury Scale (AIS) score ≤ 3 at admission, received an indicated contrast-enhanced WB-CT (reference standard) and a plain WB-MRI (index test) voluntarily up to five days after trauma. Two radiologists, blinded to the WB-CT findings, evaluated the absence or presence of injuries with WB-MRI in four body regions: head, torso, axial skeleton, and upper extremity. Diagnostic accuracy was determined using sensitivity, specificity, positive predictive value, and negative predictive value by body region. RESULTS: Between June 2019 and July 2021, 40 patients were assessed for eligibility of whom 35 (median age (interquartile range): 50 (32.5) years; 26 men) received WB-MRI. Of 140 body regions (35 patients × 4 regions), 31 true positive, 6 false positive, 94 true negative, and 9 false negative findings were documented with WB-MRI. Thus, plain WB-MRI achieved a total sensitivity of 77.5% (95%-confidence interval (CI): (61.6-89.2%)), specificity of 94% (95%-CI: (87.4-97.8%)), and diagnostic accuracy of 89.3% (95%-CI: (82.9-93.9%)). Across the four regions sensitivity and specificity varied: head (66.7%/93.1%), torso (62.5%/96.3%), axial skeleton (91.3%/75%), upper extremity (33.3%/100%). Both radiologists showed substantial agreement on the WB-MRI reading (Cohen's Kappa: 0.66, 95%-CI: (0.51-0.81)). CONCLUSION: Regarding injury detection, WB-MRI is feasible in slightly to moderately injured trauma patients, especially in the axial skeleton. CLINICAL RELEVANCE STATEMENT: Besides offering a radiation-free approach, whole-body MRI detects injuries almost identically to whole-body CT in slightly to moderately injured trauma patients, who comprise a relevant share of all trauma patients. KEY POINTS: Whole-body MRI could offer radiation-free injury detection in slightly to moderately injured trauma patients. Whole-body MRI detected injuries almost identically compared to whole-body CT in this population. Whole-body MRI could be a radiation-free approach for slightly to moderately injured young trauma patients.
ABSTRACT
PURPOSE: Currently, there is an intense debate on variations in intra-cerebral radiosensitivity and relative biological effectiveness (RBE) in proton therapy of primary brain tumours. Here, both effects were retrospectively investigated using late radiation-induced brain injuries (RIBI) observed in follow-up after proton therapy of patients with diagnosed glioma. METHODS: In total, 42 WHO grade 2-3 glioma patients out of a consecutive patient cohort having received (adjuvant) proton radio(chemo)therapy between 2014 and 2017 were eligible for analysis. RIBI lesions (symptomatic or clinically asymptomatic) were diagnosed and delineated on contrast-enhanced T1-weighted magnetic resonance imaging scans obtained in the first two years of follow-up. Correlation of RIBI location and occurrence with dose (D), proton dose-averaged linear energy transfer (LET) and variable RBE dose parameters were tested in voxel- and in patient-wise logistic regression analyses. Additionally, anatomical and clinical parameters were considered. Model performance was estimated through cross-validated area-under-the-curve (AUC) values. RESULTS: In total, 64 RIBI lesions were diagnosed in 21 patients. The median time between start of proton radio(chemo)therapy and RIBI appearance was 10.2 months. Median distances of the RIBI volume centres to the cerebral ventricles and to the clinical target volume border were 2.1 mm and 1.3 mm, respectively. In voxel-wise regression, the multivariable model with D, D × LET and periventricular region (PVR) revealed the highest AUC of 0.90 (95 % confidence interval: 0.89-0.91) while the corresponding model without D × LET revealed a value of 0.84 (0.83-0.86). In patient-level analysis, the equivalent uniform dose (EUD11, a = 11) in the PVR using a variable RBE was the most prominent predictor for RIBI with an AUC of 0.63 (0.32-0.90). CONCLUSIONS: In this glioma cohort, an increased radiosensitivity within the PVR was observed as well as a spatial correlation of RIBI with an increased RBE. Both need to be considered when delivering radio(chemo)therapy using proton beams.
