Quantitative bone SPECT/CT useful for selecting medical or surgery treatment in heterotopic ossification.

OBJECTIVE: Mature lamellar bone formation in extra-skeletal soft tissue is termed heterotopic ossification (HO). Surgical resection of HO is performed to preserve joint mobility, though timing is very important, as resection prior to HO maturation very often results in incomplete or inadequate excision, leading to recurrence. The present study was conducted to evaluate whether standardized uptake values (SUV) derived from quantitative bone single-photon emission computed tomography/computed tomography (SPECT/CT) are useful for assessing HO maturity and determining the appropriate timing of surgical resection. SUBJECTS AND METHODS: Eleven quantitative bone SPECT/CT scans from six patients with HO were analyzed. RESULTS: Four of the patients with a total of 10 lesions received medical treatment (bisphosphonates), and their mean SUVmax, SUVpeak, SUVmean, metabolic bone volume (MBV), and total bone uptake (TBU) values were 13.12±12.39 (range 4.41-44.35), 11.81±11.27 (4.12-40.53), 7.64±7.16 (3.02-26.05), 81.83±111.02 (15.68-290.64), and 781.30±1,301.78 (61.87-3,301.87), respectively. The two patients who underwent surgery had a total of two lesions and those mean values in those cases were 3.21±1.67 (2.03, 4.39), 2.99±1.65 (1.82, 4.15), 2.22±1.27 (1.32, 3.11), 6.77±2.21 (5.2, 8.33), and 16.39±13.46 (6.87, 25.9), respectively. Two who were evaluated with use of serial bone SPECT/CT scanning for assessment of medical treatment response showed a gradual decrease in SUV, reflecting the effectiveness of bisphosphonate therapy (SUVmax 9.01-8.94-6.11-5.37 and 6.93-5.93-4.41, respectively). CONCLUSION: Standardized uptake value derived from quantitative bone SPECT/CT scanning is useful for monitoring HO metabolic activity and determining the appropriate timing of surgical resection.