Role of 3-phase bone scintigraphy [[Unsupported ANSI Character - ]]• FDG-PET to monitor hyperbaric oxygen therapy for several types of refractory osteomyelitis.

Objectives: Osteomyelitis of the jaw is one of the most complicated inflammatory conditions in oral and maxillofacial region. It is very difficult to correctly evaluate the degree and extent of necrosis,inflammation & infection. This refractory osteomyelitis often needs extended surgery, leading to impaired quality-of-life. We have performed hyperbaric oxygen therapy (HBO) combined with conservative surgery for advanced cases. Nevertheless, no study has ever demonstrated the quantitative anti- inflammatory effect of HBO to osteomyelitis of the jaw. We appraised the effect of HBO to osteomyelitis by using the maximum standardized uptake value(SUVmax) of FDG-PET & the accumulation area of 3-phase bone scintigraphy. Thus, the aim of this study was to evaluate 3 types of osteomyelitis .Three types of osteomyelitis are Medication-related osteonecrosis of the jaw: MRONJ, osteoradionecrosis: ORN, & Odontogenic osteomyelitis: Odont.

Methods: Patients:16 cases (M/F: 6/10, Median (range) age: 73(50-81)) with Osteomyelitis. Each type of osteomyelitis were ORN in 8 cases, Odont in 4 cases, MRONJ in 4 cases. The treatment protocol includes 20 times of pre-operative HBO, conservative surgery, then 10 times of post-operative HBO. Each patient underwent FDG-PET and 3-phase bone scintigraphic studies prior to & after the pre-operative HBO. SUVmax was calculated for quantitative analysis of FDG uptake in the lesions. Each image of 3-phase bone scan (perfusion, pool, static) was analyzed using a rectangular region of interest (ROI).A symmetrical ROI was then placed over the contralateral normal region as the control, another ROI was placed on the frontal bone as the background by using ImageJ.The uptake ratio of was calculated using the mean count, the lesion (l), the contralateral normal area (n) and the background (b) and modified Jacobsson’s method{Uptake ratio=[count(l)-count(b)]/[count(n)-count(b)]}.

Results: FDG-PET detected the focal area of inflammation in all osteomyelitis cases. SUVmax after HBO (average 3.38±2.1, range 1.47-4.76) was lower than those of before HBO (average 4.26±1.91range 1.97-8.7) ,but there were no significant differences. Treatment effect was low in cases ORN and Odont cases, but it was highly effective in all MRONJ cases showed decreased SUVmax. The 3 phase static and pool bone images did not change. However, perfusion image (before HBO: 1.84±0.53, after HBO: 1.44±0.5, p=0.03) showed remarkable response to HBO for all osteomyelitis.

Conclusions: These preliminary results indicate that 3 phase perfusion is useful for monitoring the effect of HBO for osteomyelitis. HBO combined with minor conservative surgery may hold a promise for treatment strategy in patients with refractory osteomyelitis.

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