Novel CZT-based digital SPECT - Preliminary Results from a Prototype System

1750 Objectives CZT-based digital gamma cameras provide greater sensitivity, thereby allowing faster acquisitions and / or reduced administered dose compared to the widely used scintillator-based analog (Anger) systems. Evaluation of clinical feasibility, image quality, and diagnostic performance of a novel CZT-based digital SPECT camera was performed. Methods The digital SPECT system (Valiance X12 prototype, Molecular Dynamics, Hamilton, Bermuda) is equipped with CZT-based detection units, fitted with a high-sensitivity collimator and mounted on a ring shaped gantry. The detection units are capable of independent motion to acquire data from multiple angular views. Data are reconstructed using an iterative reconstruction algorithm. The flexible architecture also enables focusing the detection units on a specific region of interest to obtain enhanced images of a specific target. Eleven Tc-99m MDP digital SPECT studies were acquired in 8 patients (6M, age 27-66yrs) immediately following analog (Anger) camera scans including SPECT of knees (n=5), lumbar spine/pelvis/hips (n=4) and feet (n=2). Images were compared to analog SPECT images by experienced Nuclear Medicine physicians and were graded on a scale of 1 (poor) to 4 (very good) for sharpness, contrast, overall quality and diagnostic confidence,. Focused CZT digital SPECT scans were additionally performed on 2 regions of interest (1 knees, 1 pelvis). Results Overall image quality and diagnostic confidence of digital CZT vs. analog Anger SPECT were comparable. Mean grades for digital SPECT images exceeded those of analog SPECT images for sharpness (3.6 vs. 3.1), and contrast (3.9 vs. 3.4). Focused CZT digital SPECT further increased both sharpness and contrast when compared to analog SPECT. Conclusions These preliminary findings show promising results for CZT digital bone SPECT. Further research will assess other general nuclear medicine applications, as well as the contribution of focused imaging, a unique capability of this CZT-based digital SPECT system.