The value of 99mTc-MDP bone SPECT/CT in evaluation of patients with painful knee prosthesis

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Abstract

Objective

The purpose of this study was to assess the incremental value of technetium-99m-methyl diphosphonate (99mTc-MDP) single-photon emission computed tomography/computed tomography (SPECT/CT) over 99mTc-MDP two-phase bone scan (TPBS) in the assessment of the patients with pain following knee arthroplasty.

Patients and methods

99mTc-MDP TPBS and 99mTc-MDP SPECT/CT were performed in 49 patients with knee pain after knee arthroplasty. The scans were reviewed by two readers (nuclear medicine physician and musculoskeletal radiologist). 99mTc-MDP SPECT/CT studies were interpreted in conjunction with TPBS in this retrospective study to identify the pain generator in painful knee prosthesis. The final diagnosis was established based on a combination of histopathological/cytological findings, other imaging findings (e.g. MRI, radiolabelled white scan), clinical decisions, and management outcomes (including subsequent intraoperative findings).

Results

In diagnosing infection or aseptic loosening, a definitive outcome regarding the presence/absence of aseptic loosening or periprosthetic infection was obtained in 41 patients. (a) Sensitivity of 99mTc-MDP SPECT/CT [100%; 95% confidence interval (CI): 66.4–100%] was higher than 99mTc-MDP TPBS (88.9%; 95% CI: 51.8–99.7%). (b) Specificity of 99mTc-MDP SPECT/CT (75%; 95% CI: 53.3–90.2%) was considerably higher than 99mTc-MDP TPBS (30%; 95% CI: 11.9–54.3%). Alternative diagnoses were identified in 21/49 (43%) patients on 99mTc-MDP SPECT/CT, which could not be ascertained on 99mTc-MDP TPBS alone.

Conclusion

99mTc-MDP SPECT/CT has better sensitivity and specificity compared with 99mTc-MDP TPBS in diagnosis of aseptic loosening and periprosthestic infection in patients with painful knee arthroplasty. 99mTc-MDP SPECT/CT identified alternative causes of pain in 43% of patients, which was not identified by 99mTc-MDP TPBS.

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