CZT検出器搭載型小動物用SPECT装置における適切なコリメータの検討

摘要

Objective: Almost all small animal SPECT is performed with pinhole collimators (PH), including single-PH (SPH) and multi-PH (MPH). In the clinical study, not only PH but also parallel-hole collimator (PAH) is often used in planar and SPECT imaging. However, there have been no comparative studies on image quality with various collimators on the small animal imaging. This study compared the basic characteristics of PH and PAH in small animal imaging. Methods: Performance of planar and SPECT images was evaluated using 99mTcO4 - and SPH, MPH and PAH with low energy and high resolution on the SPECT/CT scanner FX3200. We measured sensitivity, resolution, concentration linearity and uniformity. Planar imaging of mice with 99mTc-labeled mercaptoacetyltriglycine (99mTc-MAG3) was performed using SPH and PAH. SPECT imaging with 99mTc-methylene diphosphonate (99mTc-MDP) was performed using all collimators. Results: With SPH, MPH and PAH, sensitivity was 43.5, 211.2 and 926.5 cps/MBq, respectively, and spatial resolution was 0.60/0.56, non/0.96, 5.20/5.34 mm full-width half maximum (planar/SPECT), respectively. There were marked correlations between the radioactivity counts on images and radioactivity with all collimators. Values of % standard deviation on planar imaging showed small differences between the SPH and PAH, while the values were the smallest on SPECT imaging with MPH. On imaging of mice, SPH yielded high-quality 99mTc-MAG3-planar images when compared with PAH. MPH yielded sharper 99mTc-MDP-SPECT images than SPH and PAH. Conclusions: The characteristics of PH and PAH differed on small animal imaging. Although sensitivity was higher with PAH, PH showed higher resolution. Among the PH collimators, SPH was more appropriate for planar imaging, and MPH was more suitable for SPECT imaging in a small animal imaging scanner with CZT detector. © 2013 The Japanese Society of Nuclear Medicine.