Bone scan index of the jaw: a new approach for evaluating early-stage anti-resorptive agents-related osteonecrosis

Abstract

Objective

A computer-aided diagnosis of bone scintigraphy using a bone scan index (BSI) has not been applied to a diagnosis of anti-resorptive agents-related osteonecrosis of the jaw (ARONJ). The aim of this study was to validate a diagnostic ability of BSI for early-stage ARONJ.

Methods

A total of 44 cancer patients treated with anti-resorptive drugs were evaluated retrospectively. All patients underwent bone scintigraphy and the tracer uptakes were analyzed by BSI. The software BONENAVI (FUJIFILM RI Pharma; EXINIbone, EXINI Diagnostics) could automatically detect abnormal intensities and calculate each regional BSI (rBSI). Among the rBSIs, the largest one in the jaw was manually selected and defined as maximum BSI of the jaw (BSIJmax). Uptake ratio (UR) between the maximum jaw count-to-average forehead count was also calculated. Screening accuracy of ARONJ based on 2 parameters was compared. Receiver operating characteristic analysis and Fisher's exact test were performed.

Results

The BSIJmax was significantly higher in patients who developed ARONJ than in those who did not, 3 months before the diagnosis of stage 2 ARONJ (p < 0.0001 and p = 0.02 in the maxilla and mandible, respectively). Using the cutoff values of 0.09% in the maxilla and 0.06% in the mandible, BSIJmax for predicting stage 2 ARONJ showed sensitivity and specificity of 88 and 96%, respectively, in the maxilla and 64 and 89%, respectively, in the mandible at 3 months before the diagnosis. The BSIJmax >0.09% and BSIJmax >0.06% in the maxilla and mandible, respectively, were much more frequently observed in patients who subsequently developed stage 2 ARONJ 3 months after the bone scintigraphy than in those who did not (p < 0.0001 and odds ratio = 182 in the maxilla and p < 0.005 and odds ratio = 14 in the mandible). The UR showed comparable diagnostic ability.

Conclusion

The BSIJ provided a new index for evaluating ARONJ. For predicting occurrence of ARONJ, the thresholds of BSIJmax = 0.09 and 0.06% in the maxilla and mandible, respectively, may be used in patients treated with anti-resorptive drugs, and a differential diagnosis including ARONJ is recommended.

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