Fig 1.
Flow diagram of participants in this study.
TFCC, triangular fibrocartilage complex; SPECT/CT, single-photon-emission computed tomography/computed tomography.
Fig 2.
Diagnostic process of ulnar impaction syndrome (UIS).
MR, magnetic resonance; UIS, ulnar impaction syndrome.
Fig 3.
How the volume of interest (VOI) was drawn.
A spherical VOI was designed to cover the sigmoid notch of the radius, ulnar fovea, ulnocarpal collateral ligament, and lunate–triquetrum in place in three dimensions on CT. The maximum SUV (SUVmax) of the illustrated VOI was calculated for analysis (SUVmax = 9.07 for this case).
Table 1.
Patient characteristics.
Table 2.
Comparison of SUVmax.
Fig 4.
Receiver operating characteristic analyses of the semiquantitative parameters for bone lesions of ulnar-sided wrist pain.
Maximum standard uptake values (SUVmax) had an AUC of 0.801 (95% CI, 0.582 to 0.932; p = 0.039). When the SUVmax cutoff value for UIS was 4.09, sensitivity of 67% and specificity of 82% were obtained.
Fig 5.
Examples of clinical applications of the maximum standard uptake values (SUVmax).
(a) Images of a 47-year-old man. Plain radiography shows a positive ulnar variance. Magnetic resonance imaging (MRI) suggests central and foveal tear of the triangular fibrocartilage complex (TFCC), but there is no evidence of bone bruises or cystic change of the lunate. The semiquantitative SPECT/CT shows a 7.51 SUVmax for the ulnar-sided wrist, indicating active ulnar impaction syndrome (UIS). This patient could be diagnosed with UIS. (b) Images of a 22-year-old man. Plain radiography shows a positive ulnar variance. TFCC of the MRI suggested tear of the ulnar styloid and foveal attachment. There were no typical findings of the UIS between the carpal bones and distal ulna. The semiquantitative SPECT/CT shows mild uptake of the ulnar-side wrist and SUVmax of 1.74 for the ulnar-sided wrist that is lower than the cutoff value of 4.09 for UIS. This patient could be diagnosed with a TFCC tear without UIS.
Fig 6.
Ulnar-sided wrist pain assessment protocol.