Mallee CT vs MRI scaphoid

Comparison of CT and MRI for diagnosis of suspected scaphoid fractures

Mallee W, Doornberg JN, Ring D, et al. The Journal of bone and joint surgery. American volume 2011 · PMID 21209265 · doi:10.2106/jbjs.i.01523

Question

How do CT and MRI compare in diagnostic performance for clinically suspected scaphoid fractures with normal radiographs?

Design

Prospective diagnostic accuracy study in which each patient had both CT and MRI within ten days of injury, read blinded by a consensus panel, with six-week radiographs as the reference standard.

Patients

Consecutive patients with scaphoid tenderness and normal radiographs after a fall on the outstretched hand.

Intervention

CT of the wrist

Comparison

MRI of the wrist

Primary outcome

Sensitivity, specificity and accuracy for true scaphoid fracture

Key result

CT and MRI performed comparably with no significant difference in sensitivity, specificity or accuracy; both were better at excluding than confirming a fracture, and MRI produced more false positives.

Limitations

Small sample and an imperfect reference standard, because there is no true gold standard for occult scaphoid fracture.

Impact on practice

Shows that CT is a reasonable alternative where MRI access is limited, and reminds clinicians that a low pre-test probability means positive advanced imaging may be a false positive.