Dynamic analysis of technetium-99m HMDP accumulation and its effect on regional bone metabolism and bone blood flow in bisphosphonate-related osteonecrosis of the jaw

Bone scintigraphy is reported to be useful for detecting bisphosphonate-related osteonecrosis of the jaw (BRONJ). In this clinical study, we employed a mathematical analysis of dynamic bone scintigraphy to evaluate bone disorders in BRONJ. Osteomyelitis (OM) and osteoradionecrosis (ORN) were analyzed for comparison. Forty patients who underwent bone scintigraphy with Tc-99m-labeled hydroxymethylene diphosphonate (Tc-99m HMDP) for diagnosis of bone disorders were entered into the study. The patients comprised 6 BRONJ patients, 6 ORN patients, and 28 mandibular OM patients; 90 normal control subjects without any bone diseases of the jaw were enrolled for comparison. The observed time-activity data for Tc-99m in regions of interest were fitted to a multicompartment model. K and lambda ratios reflecting bone blood flow and regional bone metabolism, respectively, were calculated. The ratios of affected disease side to normal side were obtained. The K-ratios (mean +/- A SD) were 1.25 +/- A 0.15 in BRONJ, 1.20 +/- A 0.19 in OM, 1.09 +/- A 0.11 in ORN, and 0.99 +/- A 0.04 in normal subjects. The lambda-ratios were 1.84 +/- A 0.45 in BRONJ, 2.37 +/- A 0.73 in OM, 1.52 +/- A 0.34 in ORN, and 1.03 +/- A 0.10 in normal subjects. The K-ratio in BRONJ was significantly higher than that in normal subjects, but did not differ from that in OM. The lambda-ratio in BRONJ was low compared with OM, but increased compared with normal subjects. There were similarities in both ratios between BRONJ and ORN. Dynamic analyses using a multicompartment model may help toward understanding and evaluation of bone disorders in BRONJ.