Radiation Exposure in a Consecutive Series of Patients in Computed Tomography Coronary Angiography Using a Dual Source 128-Slice Computed Tomography Scanner

Abstract

Abstracts coronary calcium is unknown. We sought to assess and quantify coronary calcium by high-field MRI and highdefinition CT in comparison with histology findings.Methods: Three ex vivo human hearts were studied. CT imaging was performed on a 64-detector scanner with spatial resolution of 0.23 mm. MRI imaging was conducted on a 9.4T system with spatial resolution of 0.25 mm, utilising T1 and UTE sequences (TE = 20 s). Cross sectional images were co-registered to histopathology. Patterns of calcification (micro, spotty, sheet) and calcific dimensions (area, diameters) were measured.Results: Twenty-eight cross sections with 38 calcific deposits were studied. The overestimation of calcific area by MRI was mild (117%) compared to CT (200%). MRI failed to identify 4/38 deposits -all micro-calcification. The missed lesions on MRI were significantly smaller (0.07 mm 2 v 0.40 mm 2 ; p = 0.024). CT failed to identify 17/38 deposits, consisting of micro and spotty calcification. Similarly, the missed lesions had smaller calcific area (0.16 mm 2 v 0.39 mm 2 ; p = 0.0395). There were no false positives for either MRI or CT. Conclusion: Assessment and quantification of calcium in ex vivo coronary arteries is feasible utilising high-field MRI and UTE sequence. Its performance was relatively better than high-definition CT.http://dx.Background: Computed tomography coronary angiography (CTCA) has developed to significant modality for diagnostic imaging of coronary artery disease. However, concerns have risen due to the possible high radiation burden of CTCA.Aim: To outline the radiation exposure in a series of consecutive patients in Western Sydney, having a CTCA using a dual-source 128-slice scanner and determine factors influencing this.Methods: Radiation doses and demographics were collected from 586 outpatients referred for a CTCA between January and November 2011.Results: Of the 586 patients, 271 (46.2%) were women. Mean age was 58.3 ± 12.2(SD) years. Mean total radiation was 4.77 ± 3.45 mSv (range 0.64-31.34). The mean radiation dose in men was 4.99 ± 3.51 mSv and for women 4.62 ± 3.38 mSv (p = 0.09). In a multivariable model including age, male gender, heart rate and body mass index, all were independent predictors of increased radiation exposure (see table).