Optimization of multidetector array CT acquisition parameters for CT colonography

Background: Multidetector array computed tomography technology has increased the number of acquisition parameters that a user must select. This article examines the criteria by which detector collimation, reconstructed scan width, reconstruction scan interval, pitch, image noise, and patient dose can be optimized. Methods: A water phantom containing tissue-equivalent polyps in an air-filled tube was scanned using multiple acquisition parameter combinations. X-ray tube current was changed to independently match dose and noise to a single-detector array technique. Images were assessed in axial and three-dimensional formats. Results: All polyps were visible in axial and three-dimensional images for all scans. Helical artifacts were noted at higher table speed values. The 5-mm-wide scans spaced at 3-mm intervals allowed visualization of the smallest polyps: 5 × 5 or 7 × 3 (diameter × height; mm). Conclusion: Our results indicate that thin-scan and low-noise techniques need not be used to visualize polyps of clinically relevant sizes.