Diagnostic Value of SPECT Versus SPECT/CT in Femoral Avascular Necrosis: Preliminary Results

Objective: With the advent of single-photon emission computer tomography/computed tomography (SPECT/CT), its applications and indications have to be evaluated clinically for a more efficient and cost-effective use in patient management. This retrospective study investigated the clinical value of conventional Tc MDP SPECT against SPECT/CT in diagnosing hip avascular necrosis (AVN).

Methods: This retrospective study evaluated all patients who underwent SPECT/CT during the period from 1 March 2008 to 31 July 2009 for possible femoral AVN for which MRI was contraindicated. The SPECT and SPECT/CT images were reviewed separately by two radiologists with different levels of experience in a double-blinded manner. The likelihood of AVN for each symptomatic hip was graded according to the level of confidence. Clinical outcome was considered as the gold standard. The sensitivity, specificity, and accuracy for SPECT and SPECT/CT by each radiologist was obtained and compared with the gold standard. The corresponding receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate the diagnostic power of SPECT against SPECT/CT.

Results: A total of 22 patients and 24 symptomatic hips were analyzed. Seven hips (29%) were confirmed to have AVN. The AUCs obtained from ROC for trainee radiologist for SPECT vs. SPECT/CT were 0.828 and 0.916, respectively. The AUC for specialist radiologist increased from 0.916 to 0.941 with CT.

Conclusion: We concluded that SPECT/CT is beneficial for the improvement of AUC in ROC on the diagnostic of hip AVN compared with SPECT alone.