MRI‐based synthetic CT shows equivalence to conventional CT for the morphological assessment of the hip joint. Issue 4 (12th July 2021)

• Record Type: Journal Article
• Authors: Florkow, Mateusz C.; Willemsen, Koen; Zijlstra, Frank; Foppen, Wouter; van der Wal, Bart C. H.; van der Voort van Zyp, Jochem R. N.; Viergever, Max A.; Castelein, René M.; Weinans, Harrie; van Stralen, Marijn; Sakkers, Ralph J. B.; Seevinck, Peter R.
• Is Part Of: Journal of orthopaedic research. Volume 40:Issue 4(2022)
• Page Start: 954
• Page End: 964
• Publication Date: 2021-07-12
• Subjects: CT -- diagnostic imaging -- hip -- MRI -- synthetic CT; Orthopedics -- Periodicals; Musculoskeletal system -- Periodicals; 616.7
• DOI: 10.1002/jor.25127
• Languages: English
• ISSNs: 0736-0266

Abstract

Abstract: This study evaluated the accuracy of synthetic computed tomography (sCT), as compared to CT, for the 3D assessment of the hip morphology. Thirty male patients with asymptomatic hips, referred for magnetic resonance (MR) imaging and CT, were included in this retrospective study. sCT images were generated from three‐dimensional radiofrequency‐spoiled T1‐weighted multi‐echo gradient‐echo MR images using a commercially available deep learning‐enabled software and were compared with CT images through mean error and surface distance computation and by means of eight clinical morphometric parameters relevant for hip care. Parameters included center‐edge angle (CEA), sharp angle, acetabular index, extrusion index, femoral head center‐to‐midline distance, acetabular version (AV), and anterior and posterior acetabular sector angles. They were measured by two senior orthopedic surgeons and a radiologist in‐training on CT and sCT images. The reliability and agreement of CT‐ and sCT‐based measurements were assessed using intraclass correlation coefficients (ICCs) for absolute agreement, Bland–Altman plots, and two one‐sided tests for equivalence. The surface distance between CT‐ and sCT‐based bone models were on average submillimeter. CT‐ and sCT‐based measurements showed moderate to excellent interobserver and intraobserver correlation (0.56 < ICC < 0.99). In particular, the inter/intraobserver agreements were good for AV (ICC > 0.75). For CEA, the intraobserver agreement was good (ICC > 0.75) and the interobserver agreement was moderate (ICC > 0.69). Limits of agreements were similar between intraobserver CT and intermodal measurements. All measurements were found statistically equivalent, with average intermodal differences within the intraobserver limits of agreement. In conclusion, sCT and CT were equivalent for the assessment of the hip joint bone morphology. Abstract : This study compared magnetic resonance imaging‐based synthetic computed tomography (sCT) to conventional CT for the morphological assessment of the hip joint. The sCT generation technique reconstructed radiodensity contrast accurately, providing bone models within a submillimeter accuracy to CT‐based bone models. CT and sCT images were found statistically equivalent for measuring eight morphometric parameters clinically relevant in hip care. For both modalities, moderate to excellent interobserver and intraobserver reliability were obtained. This provides new possibilities in the radiation‐free diagnosis and surgical planning.