Head-to-head comparison of adaptive statistical and model-based iterative reconstruction algorithms for submillisievert coronary CT angiography.

Aims: Iterative reconstruction (IR) algorithms allow for a significant reduction in radiation dose of coronary computed tomography angiography (CCTA). We performed a head-to-head comparison of adaptive statistical IR (ASiR) and model-based IR (MBIR) algorithms to assess their impact on quantitative image parameters and diagnostic accuracy for submillisievert CCTA. Methods and results: CCTA datasets of 91 patients were reconstructed using filtered back projection (FBP), increasing contributions of ASiR (20, 40, 60, 80, and 100%), and MBIR. Signal and noise were measured in the aortic root to calculate signal-to-noise ratio (SNR). In a subgroup of 36 patients, diagnostic accuracy of ASiR 40%, ASiR 100%, and MBIR for diagnosis of coronary artery disease (CAD) was compared with invasive coronary angiography. Median radiation dose was 0.21 mSv for CCTA. While increasing levels of ASiR gradually reduced image noise compared with FBP (up to - 48%, P < 0.001), MBIR provided largest noise reduction (-79% compared with FBP) outperforming ASiR (-59% compared with ASiR 100%; P < 0.001). Increased noise and lower SNR with ASiR 40% and ASiR 100% resulted in substantially lower diagnostic accuracy to detect CAD as diagnosed by invasive coronary angiography compared with MBIR: sensitivity and specificity were 100 and 37%, 100 and 57%, and 100 and 74% for ASiR 40%, ASiR 100%, and MBIR, respectively. Conclusion: MBIR offers substantial noise reduction with increased SNR, paving the way for implementation of submillisievert CCTA protocols in clinical routine. In contrast, inferior noise reduction by ASiR negatively affects diagnostic accuracy of submillisievert CCTA for CAD detection.

Histologically Proven Myocardial Carcinoid Metastases: The Value of Multimodality Imaging.

We present a case of a patient with intramyocardial metastases from a carcinoid tumor. These findings were detected using cardiovascular magnetic resonance imaging, with functional metabolic activity analyzed using nuclear imaging and confirmed by histologic findings at surgical biopsy. This case highlights the value of cardiovascular magnetic resonance imaging and the importance of multimodality imaging.

Lipoprotein(a) in patients with aortic stenosis: Insights from cardiovascular magnetic resonance.

BACKGROUND: Aortic stenosis is the most common age-related valvular pathology. Patients with aortic stenosis and myocardial fibrosis have worse outcome but the underlying mechanism is unclear. Lipoprotein(a) is associated with adverse cardiovascular risk and is elevated in patients with aortic stenosis. Although mechanistic pathways could link Lipoprotein(a) with myocardial fibrosis, whether the two are related has not been previously explored. In this study, we investigated whether elevated Lipoprotein(a) was associated with the presence of myocardial replacement fibrosis. METHODS: A total of 110 patients with mild, moderate and severe aortic stenosis were assessed by late gadolinium enhancement (LGE) cardiovascular magnetic resonance to identify fibrosis. Mann Whitney U tests were used to assess for evidence of an association between Lp(a) and the presence or absence of myocardial fibrosis and aortic stenosis severity and compared to controls. Univariable and multivariable linear regression analysis were undertaken to identify possible predictors of Lp(a). RESULTS: Thirty-six patients (32.7%) had no LGE enhancement, 38 (34.6%) had midwall enhancement suggestive of midwall fibrosis and 36 (32.7%) patients had subendocardial myocardial fibrosis, typical of infarction. The aortic stenosis patients had higher Lp(a) values than controls, however, there was no significant difference between the Lp(a) level in mild, moderate or severe aortic stenosis. No association was observed between midwall or infarction pattern fibrosis and Lipoprotein(a), in the mild/moderate stenosis (p = 0.91) or severe stenosis patients (p = 0.42). CONCLUSION: There is no evidence to suggest that higher Lipoprotein(a) leads to increased myocardial midwall or infarction pattern fibrosis in patients with aortic stenosis.

Long-term outcome prediction by functional parameters derived from coronary computed tomography angiography.

BACKGROUND: Estimation of hemodynamic relevance of a coronary stenosis from coronary computed angiography (CCTA) has raised substantial interest. Recently, the corrected coronary opacification (CCO) decrease and the transluminal attenuation gradient (TAG) have been suggested as faster alternatives to the FFRCT. The aim of the study was to evaluate whether the diagnostic accuracy of CCO decrease and TAG translates into an added prognostic value in patients evaluated for coronary artery disease (CAD). METHODS: This retrospective study consists of 162 consecutive patients referred for evaluation of known or suspected CAD by CCTA. CCO decrease was defined as difference of mean luminal coronary attenuation normalized to aorta attenuation proximal-distal of a stenosis. To calculate TAG, mean attenuation was measured at 5-mm intervals from the ostium to a distal segment with a minimal cross-sectional area of 2.0mm2. Death, myocardial infarction, unstable angina requiring hospitalization, and coronary revascularization were defined as major adverse cardiac events (MACE). Multivariate analysis included covariates age, sex, ≥3 cardiovascular risk factors and stenosis severity. RESULTS: Follow-up was completed in 154 patients, CAD was found in 72. During median follow-up of 6.1years (interquartile range, 5.8-6.9years), 55 patients experienced a MACE. Among CAD patients, the presence of an abnormal CCO decrease (p<0.05) but not TAG (p=0.894) was associated with a worse MACE-free survival. In multivariate analysis, CCO decrease was an independent predictor of MACE (HR, 2.27; 95% CI, 1.14-4.52; p=0.02) while TAG was not predictive (p=0.895). CONCLUSION: In CAD patients, CCO decrease adds long-term prognostic value over clinical characteristics and stenosis severity while TAG does not.

Diastolic stress echocardiography in the young: a study in nonathletic and endurance-trained healthy subjects.

BACKGROUND: The response of diastolic Doppler indices to exercise is not well defined for young subjects. The aims of this study were to evaluate this in nonathletic and endurance-trained probands and to correlate echocardiographic data with maximal oxygen consumption. METHODS: In this prospective study, Doppler echocardiography was performed at rest and after exercise in 40 nonathletes (NAs) and 20 endurance-trained athletes (ETs) aged < 40 years, matched for age and gender. Diastolic function was assessed by mitral inflow and early diastolic velocities of the septal (e' septal) and lateral (e' lateral) mitral annulus. Maximal oxygen consumption quantification was performed simultaneously. RESULTS: All cardiac chambers were larger in ETs than NAs. ETs had higher e' lateral at rest (18.1 ± 2.7 vs 16.3 ± 3.3 cm/sec, P = .02) and higher mitral E (141 ± 15 vs 132 ± 15 cm/sec, P = .02) and e' lateral (23.5 ± 2.5 vs 21.4 ± 3.0 cm/sec, P = .01) with exercise than NAs. There was a slight increase in E/e' septal (overall, from 6.8 ± 1.3 to 7.2 ± 1.2; P = .02) and E/e' lateral (overall, from 5.0 ± 0.8 to 6.2 ± 0.9; P < .0001) with exercise. Changes in diastolic parameters with exercise were similar in ETs and NAs. Percentage of predicted maximal oxygen consumption was correlated with exertional E (r = 0.28, P = .03) and e' lateral (r = 0.32, P = .01), but the strongest predictor was indexed left ventricular end-diastolic volume (r = 0.66, P < .0001). CONCLUSIONS: During exercise, E/e' increases but remains within normal ranges in healthy young subjects, and the response to exercise does not differ between ETs and NAs. These data help define the normal diastolic stress echocardiographic response in the young. Exercise capacity shows a correlation with enhanced exertional early diastolic velocities but is more closely related to cardiac structural adaption to endurance training.