Interobserver variability impairs radiologic grading of primary graft dysfunction after lung transplantation.

OBJECTIVES: The current score for primary graft dysfunction after lung transplantation relies heavily on chest radiographs, and radiologic judgment can make the difference between the lowest (primary graft dysfunction 0) and the highest (primary graft dysfunction 3) grade. This study aimed to evaluate interobserver variability of the scoring of postoperative chest radiographs and its impact on primary graft dysfunction grades in a large single-center cohort. METHODS: We retrospectively analyzed 497 lung transplantations performed between January 2010 and July 2016 at the Medical University of Vienna. Five trained thoracic radiologists were asked to independently examine postoperative chest radiographs performed at 0 to 6 hours, 24 hours, 48 hours, and 72 hours after arrival at the intensive care unit. Interobserver variability was calculated using Fleiss' kappa (κ) statistics. RESULTS: A total of 1988 chest radiographs were evaluated. Consensus among all 5 radiologists was found in only 826 cases (43.0%). At 0 to 6 hours and 24 hours, only a moderate agreement was found among the 5 radiologists (κ = 0.456 and 0.456, respectively), and agreement was even worse at 48 and 72 hours (κ = 0.405 and κ = 0.409). On the basis of this high interobserver variability, best and worst case scenarios were calculated leading to primary graft dysfunction 3 rates of 8.4% versus 28.4% at 0 to 6 hours, 1.8% versus 4.8% at 24 hours, 2.0% versus 5.3% at 48 hours, and 0.2% versus 3.1% at 72 hours. A high recipient body mass index and size-reduced transplants were found to be factors associated with higher rates of interobserver variability. CONCLUSIONS: The substantial interobserver variability found in this retrospective analysis underlines the difficulty to adequately grade post-transplant organ function. Future revisions of the primary graft dysfunction grading should take this problem into consideration.

Respiratory motion artifacts during arterial phase imaging with gadoxetic acid: Can the injection protocol minimize this drawback?

PURPOSE: To determine which of three gadoxetic acid injection techniques best reduced the contrast-related arterial-phase motion artifacts. MATERIALS AND METHODS: This Institutional Review Board (IRB)-approved, retrospective study included a cohort of 78 consecutive patients who each had serial gadoxetic acid-enhanced 3.0T magnetic resonance imaging (MRI) of the liver (0.025 mmol/kg body weight) performed with at least two of three injection techniques: M1 test bolus, undiluted, power-injected 1 mL/s; M2 test bolus, diluted 50% with saline, power-injected 1 mL/s; M3 fixed delay, undiluted, manually injected. Blinded to the injection method, three readers independently rated the randomized images for arterial-phase motion artifacts, arterial-phase timing, and arterial-phase lesion visibility using a four-point Likert scale. RESULTS: Regarding respiratory artifacts, gadoxetic acid arterial-phase images were judged better with M3 (2.7 ± 0.7) and were significantly less than those with M1 (2.1 ± 1.1) (P = 0.0001). Arterial-phase M2 (2.50 ± 0.89) images were rated significantly better than arterial-phase M1 images (P = 0.012), but the difference between arterial-phase images with M3 and M2 scores was not statistically significant (P = 0.49). Arterial-phase timing was significantly better for M1 compared to M3, and for M2 compared to M3 (P < 0.0001 for both). The area under the curve was 0.59-0.68. However, there was no significant difference between M1 and M2 (P = 0.35). With regard to arterial-phase lesion visibility, there was no significant difference in the ratings between any of the three injection techniques (P = 0.29-0.72). Interreader agreement was moderate to substantial (κ = 0.41-0.62). CONCLUSION: A diluted, power-injected protocol (M2) seems to provide good timing and minimize artifacts compared with two other injection methods. No significant difference was found in lesion visibility between these three methods. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1107-1114.