Purpose or Case Report: This study compares the performance of a single free-breathing GRASP sequence to a full C-MRE protocol in pediatric small bowel CD. The high k-trans of affected bowel in CD may allow high spatiotemporal GRASP dynamic contrast-enhanced technique to provide comprehensive diagnostic value in CD, especially in patients with limited breath-hold capacity.
Methods & Materials: 24 patients with known or suspected CD and available endoscopic biopsy results were evaluated over a 25-month period (September 2017 to September 2019) using a standard C-MRE protocol with the addition of GRASP imaging. Two radiologists, blinded to clinical data and C-MRE results, reviewed the GRASP studies on a 3D workstation and scored standard reporting elements of CD. Discrepant reporting elements were resolved by consensus. The consensus read was compared to C-MRE results and biopsy. Cohen’s Kappa coefficients were calculated for the following: 1) Agreement between the consensus GRASP and clinical C-MRE, 2) inter-rater reliability for GRASP, 3) agreement between GRASP and biopsy, and 4) agreement between clinical C-MRE and biopsy. Subjective image quality, radial artifact, and motion artifact were scored on a Likert scale with 5 as the best rating.
Results: GRASP had moderate agreement for terminal ileal involvement when compared to C-MRE (k 0.58), and inter-reader agreement for GRASP was moderate (k 0.6). When compared to biopsy within 30 days, GRASP agreement with biopsy results was fair (k 0.31), and clinical C-MRE agreement with biopsy was moderate (k 0.56). 5 GRASP discrepancies from clinical read for ileal involvement included 3 false positives and 2 false negatives, with 1 false negative GRASP being concordant with biopsy, and the remaining biopsy results favoring the C-MRE. Mean image quality scores for 2 readers were 3.71/5 for overall image quality, 3.73/5 for radial artifact, and 3.75/5 for motion artifact.
Conclusions: The lower diagnostic accuracy of GRASP when compared to C-MRE for pediatric CD favors use as a supplement rather than an alternative to the full C-MRE protocol, but GRASP may become an essential part of the workup in patients with limited breath-hold capacity given its favorable image quality ratings and free-breathing technique.