Focal uptake at the rotator interval or inferior capsule of shoulder on18F-FDG PET/CT is associated with adhesive capsulitis.
OBJECTIVE
To determine if focal increased uptake at the rotator interval (RI) and/or inferior capsule (IC) on18F-FDG PET/CT ("positive PET") predicts the presence of adhesive capsulitis (AC).


METHODS
Three populations were retrospectively examined. Group 1 included 1,137 consecutive18F-FDG PET/CT studies and was used to determine the prevalence of focal uptake at the RI or IC. Group 2 included 361 cases from a 10-year period with18F-FDG PET/CT and MRI of shoulder performed within 45 days of each other and was used to enrich the study group. Group 3 included 109 randomly selected patients from the same time frame as groups 1 and 2 and was used to generate the control group. The study group consisted of 15 cases from the three groups, which had positive PET findings. PET/CT images were assessed in consensus by two musculoskeletal radiologists. The reference standard for a diagnosis of AC was clinical and was made by review of the medical record by a pain medicine physician.


RESULTS
The prevalence of focal activity at either the RI or IC ("positive PET") was 0.53%. Nine patients had a clinical diagnosis of AC and 15 patients had a positive PET. The sensitivity and specificity of PET for detection of AC was 56% and 87%, respectively. PET/CT had a positive likelihood ratio for AC of 6.3 (95% CI: 2.8-14.6).


CONCLUSIONS
Increased uptake at the RI or IC on PET/CT confers a moderate increase in the likelihood of AC.
Department of Diagnostic Imaging, Universiti Kebangsaan Malaysia Medical Centre, JalanYaacob Latif, Cheras, 56000, Kuala Lumpur, Malaysia.
Radhika
R
Sridharan
Department of Pain Medicine, The University of Texas M.D. Anderson Cancer Center, 1400 Pressler, Unit 0409, Houston, TX, 77030, USA.
Mitchell Philip
MP
Engle
Department of Diagnostic Imaging, The University of Texas M.D. Anderson Cancer Center, 1400 Pressler, Unit 1475, Houston, TX, 77030, USA.
Naveen
N
Garg
Department of Biostatistics, The University of Texas M.D. Anderson Cancer Center, 1400 Pressler, Unit 1411, Houston, TX, 77030, USA.
Wei
W
Wei
Department of Biostatistics, The University of Texas M.D. Anderson Cancer Center, 1400 Pressler, Unit 1411, Houston, TX, 77030, USA. bamini@mdanderson.org.
Behrang
http://orcid.org/0000-0002-4962-3466
B
Amini
D002062:Bursitis / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000000981:diagnostic imaging*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Adhesive capsulitis; FDG PET/CT; Inferior capsule; Rotator interval