Abstract
Purpose. The purpose of this study was to evaluate the technical and diagnostic performance of sub-milliSievert ultralow-dose (ULD) CT colonograpy (CTC) in the detection of colonic and extracolonic lesions.
Materials and Methods. CTC with standard dose (SD) and ULD acquisitions of 64 matched patients, half of them with colonic findings, were reconstructed with filtered back projection (FBP), hybrid (HIR) and iterative model reconstruction techniques (IMR).
Image noise in six colonic segments, in the left psoas muscle and aorta were measured. linage quality of the left adrenal gland and of the colon in the endoscopic and 2D view was rated on a five point Likert scale by two. observers, who also completed the reading of CTC for colonic and extracolonic findings. Results.
The mean radiation dose estimate was 4.1 +/- 1.4 mSv for SD and 0.86 +/- 0.17 mSv for ULD for both positions (p = 10 mm) colonic lesions that were classified as sessile polyps (n = 38), flat lesions (n = 3), or as a mass (n = 3), Per patient sensitivity and specificity were 0.82 and 0.93 for ULD-FBP, 0.97 and 0.97p for ULD-HIR, 0.97 and 1.0 for ULD-IMR. Per polyp sensitivity was 0.84 for ULD-FBP, 0 98 ULD-HIR, 0.98 for ULD-IMR.
Significantly less extracolonic findings were detected in ULD-FBP and ULD-HIR, but in the E4 category by C-BADS (potentially important findings), the detection was similar. Conclusion.
Both HIR and IMR are suitable for sub-milliSievert ULD CTC with out sacrificing diagnostic performance of the study.