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).
The radiation exposure in this consecutive series of patients is low in general but patient selection for CTCA imaging appears to be paramount. Patients with a high BMI and especially with high heart rate receive a higher dose of radiation.
Heart, Lung and Circulation 2011;20S:S156-S251 perfusion CMR positive for ischaemia, 266 (73%) were negative. Of the 266 negative CMR, MACE was encountered in only six (2%) patients (five PCI and one death due to heart failure). Accordingly a negative stress CMR afforded a freedom from MACE of 98%. Conclusion: In patients at intermediate risk for cardiovascular events, a negative stress perfusion CMR is associated with an excellent prognosis.Background: Coronary CT Angiography (CCTA) for the evaluation of disease in coronary artery bypass grafts (CABG) is classified as "uncertain" with a score of 5 in the 2010 Appropriate Use Criteria. A significant limitation is the high radiation dose, due to the large z-axis to cover the entire heart and CABG vessels. We proposed that using a prospectively gated "step-and-shoot" technique there would be significant reductions in radiation, with preservation of diagnostic image quality.Method: Patients undergoing CCTA for CABG patency using a Siemens dual-source scanner were retrospectively reviewed. Prospectively gated studies (group 1, n = 29) were compared to retrospective tube-current-modulated "min-dose" studies (group 2, n = 229), and to a historical cohort of "auto-dose" non-modulated studies (group 3, n = 73). z-Axis scan range was from the diaphragm to the left subclavian artery. Effective radiation dose (mSv) was calculated, and diagnostic image quality assessed by two expert observers.Results: Effective dose in prospectively gated studies was significantly lower (5.5 ± 1.9 mSv, p < 0.01) compared to tube-current-modulated studies (10.8 ± 5.6 mSv), and dramatically lower than full-dose (21.4 ± 10.7 mSv). Image quality was similar in all groups, with no difference in number of non-diagnostic segments. Prospectively gated studies could not assess LV function, a limitation of this technique. Heart rate in group 1 (54 ± 5 bpm) was significantly lower than in groups 2 and 3 (64 ± 9, 65 ± 11 bpm), reflecting the choice of acquisition technique for individual patients.Conclusions: Prospectively gated "step-and-shoot" CCTA is suitable for CABG patients, with dramatic reductions in radiation dose. This is suitable for selected patients with low and stable heart rates, and can be recommended in appropriate patients for the non-invasive evaluation of CABG graft patency.Background: Radiation exposure from invasive coronary angiography was similar or lower than that received from CT coronary angiography (CTCA). The new generation CT scanners are believed to deliver significantly ABSTRACTS Heart, Lung and Circulation Abstracts S189 2011;20S:S156-S251
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