CT or MRI? Not Up for Debate Says New Study

CT or MRI? If you’re planning a reverse total shoulder arthroplasty, a new study says there is no debate—it’s MRI all the way.

In the study, “CT versus MRI planning for reverse geometry total shoulder arthroplasty,” which was published in the November/December 2021 issue of the Journal of Orthopedics, a team of researchers analyzed the effectiveness of both CT and MRI images when used for glenoid implant sizing for reverse geometry total shoulder arthroplasty.

The study team examined CT or MRI images for patients undergoing reverse total shoulder arthroplasty at a tertiary referral center from October 2017 to February 2020.

Two blinded senior authors independently predicted glenosphere width and baseplate central screw length. The researchers also performed a sub-group analysis between trauma and non-trauma CT cases.

Overall, 71 data sets from 69 patients were analyzed including 31 CT predictions and 40 MRI predictions. The researchers found that 61.3% of CT measured glenosphere predictions were accurate compared to 82.5% of MRI predictions (p = 0.045).

Baseplate central screw length predictions were 77.4% and 70% accurate for CT and MRI, respectively. There was no significant difference in sub-group analysis for trauma vs. elective CT accuracy of baseplate central screw length or glenosphere measurements.

“MRI imaging may be superior to CT for predicting glenosphere width and no less accurate than CT for predicting baseline central screw length in the elective setting. No difference in CT measurement accuracy was seen between trauma and elective settings. While simultaneously clearly defining shoulder soft tissue anatomy, MRI may also be the preferred modality for bony measurements during pre-operative planning for elective reverse total shoulder arthroplasty,” the authors wrote.

The study authors were Colton J. Bohonos of the University College Cork, South Infirmary Victoria University Hospital and Cork University Hospital of Cork, Ireland, Shane P. Russell of University College Cork, South Infirmary Victoria University Hospital, Royal College of Surgeons in Dublin, Ireland, and David I. Morrissey of the University College Cork, South Infirmary Victoria University and Cork University Hospital in Cork and the Royal College of Surgeons in Dublin, Ireland.