Effects of Dose Reduction on Diagnostic Image Quality of Coronary Computed Tomography Angiography in Children Using a Third-Generation Dual-Source Computed Tomography Scanner

Utility of cardiac CT in infants with congenital heart disease: Diagnostic performance and impact on management

BACKGROUND

Advances in cardiac CT (CCT) scanner technology allow imaging without anesthesia, and with low radiation dose, making it an attractive technique in infants with congenital heart disease. However, the utility of CCT using a dual-source scanner with respect to diagnostic performance and impact on management has not been systematically studied in this population.

METHODS

Retrospective review of infants who underwent CCT to determine the utility of CCT with respect to the following: answering the primary diagnostic question, providing new diagnostic information, prompting a change in management, and concordance with catheterization or surgical inspection.

RESULTS

A total of 156 infants underwent 172 scans at a median age of 64 days, (IQR 4-188) from Jan 2016-Dec 2019. The most frequent diagnostic question was related to the pulmonary arteries (43%), followed by the aortic arch (30%), pulmonary veins (26%), coronary arteries (17%), patent ductus arteriosus (10%) and others (9%). A high-pitch spiral scan was frequently used (90%). The median effective radiation dose was low (0.66 ​mSv) and general anesthesia was used infrequently (23%). CCT answered the primary diagnostic question in 168/172 (98%) and added to the diagnostic information already available by echocardiography in 161/172 (96%) scans. CCT led to a change in management following 78/172 (53%) scans and had an impact on management following 167/172 (97%) scans. On follow-up, after 107/172 (62%) scans, subjects underwent cardiac surgery, and after 55/172 (32%) scans, they had cardiac catheterization. CCT findings were concordant with catheterization and/or surgical inspection in 156/159 (98%) scans.

CONCLUSIONS

In infants with complex congenital heart disease, CCT was accurate, answered the diagnostic questions in nearly all cases, and frequently added diagnostic information that impacted management. Radiation exposure was low, and anesthesia was needed infrequently.

Projection-based dynamic tomography

Objective. This paper proposes a 4D dynamic tomography framework that allows a moving sample to be imaged in a tomograph as well as the associated space-time kinematics to be measured with nothing more than a single conventional x-ray scan.Approach. The method exploits the consistency of the projection/reconstruction operations through a multi-scale procedure. The procedure is composed of two main parts solved alternatively: a motion-compensated reconstruction algorithm and a projection-based measurement procedure that estimates the displacement field directly on each projection.Main results. The method is applied to two studies: a numerical simulation of breathing from chest computed tomography (4D-CT) and a clinical cone-beam CT of a breathing patient acquired for image guidance of radiotherapy. The reconstructed volume, initially blurred by the motion, is cleaned from motion artifacts.Significance. Applying the proposed approach results in an improved reconstruction quality showing sharper edges and finer details.

Comparison of coronary artery measurements between echocardiograms and cardiac CT in Kawasaki disease patients with aneurysms

BACKGROUND

American Heart Association (AHA) guidelines for management of Kawasaki disease (KD) rely on coronary artery (CA) z-scores from echocardiograms. Compared with echocardiography, cardiac CT (CCT) offers better visualization of distal segments and evaluation for thrombosis and stenosis. Despite increasing use of CCT in KD, CA z-scores for CCT are not available and measurement concordance between imaging modalities is a critical knowledge gap.

METHODS

We retrospectively reviewed KD patients with CA aneurysms who had concurrent echocardiography and CCT between 2016 and 2020. Patients were included if they had history of CA z-scores of ≥3 on echocardiography during their clinical course. Agreement between CCT and echocardiography was assessed using Bland-Altman analysis.

RESULTS

Paired CCT and echocardiography studies were available in 18 patients (21 studies). The largest CA aneurysms were large/giant (z-score ≥10) in 14 studies, medium (z-score ≥5, <10) in 3 studies, and small (z score ≥2.5, <5) in 2 studies. Intra- and inter-observer reliability for CCT measurements were high for all CA segments (ICC 99.7% and 98.6%). For the LMCA, proximal LAD and proximal and distal RCA there was high correlation between echocardiogram and CCT absolute measurements with wider variation between modalities for the distal LAD and circumflex. Overall, CCT measurements tended to be smaller than echocardiogram measurements, and led to a lower AHA z-score risk classification in 24% of studies.

CONCLUSION

CCT and echocardiography have high agreement for absolute measurements of proximal CA segments, but more measurement discrepancy exists for distal CA segments with bias toward lower dimensions on CCT.