Investigation of the minimum uptake time for quantitative jawbone SPECT.

Background: The range of imaging times recommended for bone scintigraphy is wide, and uptake times vary across facilities. In our previous quantitative evaluation of jawbone SPECT using [^99mTc] Tc-HMDP, we reported that standardized uptake values at the 2-hour uptake time were comparable to those at the 3-hour uptake time. A reduction in the uptake time is of particular benefit to patients with poor general health conditions, such as those suffering from cancer. This study aimed to conduct additional research based on the hypothesis that further reduction of uptake time may be possible.

Methods: Forty patients scheduled for jawbone SPECT at our hospital's Department of Dentistry and Oral Surgery were enrolled in this study and assigned to two groups. The 1.0-hour uptake time group was imaged at two time points, 1.0 and 2.0 h, and the 1.5-hour uptake time group was imaged at two time points, 1.5 and 2.0 h, for jawbone lesions and parietal bone. We investigated statistically significant differences by comparing the maximum standardized uptake values (SUVmax) for each of the two groups using quantitative SPECT software.

Results: When the SUVmax of the 1.0-hour uptake time group was compared, the median SUVmax of the parietal bone was not significantly different. In contrast, the median SUVmax of jawbone lesions significantly increased to 6.40 and 8.10, respectively (p < 0.001). Similarly, in the 1.5-hour uptake time group, the median SUVmax of the parietal bone was not significantly different. The median SUVmax of the jawbone lesions increased to 7.22 and 8.03, respectively, with a statistically significant difference (p < 0.001).

Conclusions: The uptake time required for quantitative SPECT evaluation of jawbone lesions using [^99mTc] Tc-HMDP could not be further reduced from 2 h in 30-minute increments, and the shortest acceptable acquisition time for quantitative jawbone SPECT was 2 h.