Coronary CT angiography: Diagnostic value and clinical challenges

Proposing Multiregional Diagnostic Reference Levels for Common CT Angiography Examinations in Saudi Arabia

OBJECTIVES

Diagnostic reference levels (DRLs) are crucial tools for optimizing radiation exposure during different radiological examinations. This study aimed to establish preliminary DRLs for commonly performed computed tomographic angiography (CTA) examinations in Saudi Arabia.

METHODS

Data for three types of CTA examinations (cerebral, pulmonary, and lower-extremity) were collected from six medical cities across Saudi Arabia. Data sets related to 723 CTAs with a mean patient weight of 75 kg were analysed in detail. The DRL values were determined based on the 75th, median, and 25th CT dose index volume (CTDIvol) and dose length product (DLP) values.

RESULTS

The established DRLs were 1221 mGy cm for cerebral CTAs, 475 mGy cm for pulmonary CTAs, and 1040 mGy cm for lower-extremity CTAs. These values were comparable to those reported in other studies.

CONCLUSIONS

This study provides preliminary DRLs for three common CTA procedures in Saudi Arabia. The widespread implementation of a low kVp and a high level of image reconstruction (IR) presents an opportunity for further dose reduction. These findings can serve as a foundation for future nationwide DRL surveys and the optimization of CTA imaging protocols in Saudi Arabia.

Radiation dose analysis of computed tomography coronary angiography in Children with Kawasaki disease

BACKGROUND

There is evolving role of computed tomography coronary angiography (CTCA) in non-invasive evaluation of coronary artery abnormalities in children with Kawasaki disease (KD). Despite this, there is lack of data on radiation dose in this group of children undergoing CTCA.

AIM

To audit the radiation dose of CTCA in children with KD.

METHODS

Study (December 2013-February 2018) was performed on dual source CT scanner using adaptive prospective electrocardiography-triggering. The dose length product (DLP in milligray-centimeters-mGy.cm) was recorded. Effective radiation dose (millisieverts-mSv) was calculated by applying appropriate age adjusted conversion factors as per recommendations of International Commission on Radiological Protection. Radiation dose was compared across the groups (0-1, 1-5, 5-10, and > 10 years).

RESULTS

Eighty-five children (71 boys, 14 girls) with KD underwent CTCA. The median age was 5 years (range, 2 mo-11 years). Median DLP and effective dose was 21 mGy.cm, interquartile ranges (IQR) = 15 (13, 28) and 0.83 mSv, IQR = 0.33 (0.68, 1.01) respectively. Mean DLP increased significantly across the age groups. Mean effective dose in infants (0.63 mSv) was significantly lower than the other age groups (1-5 years 0.85 mSv, 5-10 years 1.04 mSv, and > 10 years 1.38 mSv) (P < 0.05). There was no significant difference in the effective dose between the other groups of children. All the CTCA studies were of diagnostic quality. No child required a repeat examination.

CONCLUSION

CTCA is feasible with submillisievert radiation dose in most children with KD. Thus, CTCA has the potential to be an important adjunctive imaging modality in children with KD.

An Egyptian study to assess the accuracy and reliability of CAD-RADS CT coronary angiography algorithm in the evaluation of coronary artery disease

Background

Multidetector computed tomography angiography (MDCT) is a non-invasive examination for coronary artery disease. Coronary artery disease reporting and data system (CAD-RADS) is a structured reporting system that successfully facilitated communication with clinicians. Our study aimed to assess the accuracy as well as the agreement of the CAD-RADS system with the conventional angiography results.

Results

48 patients were enrolled in this prospective study, all patients underwent MDCT coronary angiography and conventional coronary artery angiography. An excellent inter method agreement between coronary CT angiography (CCTA) and conventional coronary angiography was noted for the left main trunk (LMT) with k = 1 (p < 0.001). An excellent inter method agreement was found for the proximal, mid- and distal segments of the left anterior descending artery (LAD) and the second diagonal segment, with k = 1, 0.842 0.886 and 0.886, respectively (p < 0.001). A good agreement was noted at the first diagonal segment with k = 0.765 (p < 0.001). An excellent inter-method agreement was found for the proximal, mid- and distal segments of the left circumflex artery (LCx) and the obtuse marginal branch, with k = 0.838, 0.846, 1 and 0.846, respectively (p < 0.001). An excellent agreement was found for the proximal and mid-segments of the right coronary artery (RCA) and the posterior descending artery, with k = 1 for all segments (p < 0.001), yet a good agreement was noted at its distal segment with k = 0.782 (p < 0.001). The overall per-patient sensitivity, specificity and accuracy of the CT coronary angiography were 92.9%, 90% and 91.7% respectively.

Conclusions

The CAD-RADS algorithm and invasive coronary angiography agreed perfectly; thus, CT coronary angiography can be used as the first screening test and the invasive coronary angiography can be spared for cases requiring intervention.

Coronary arterial abnormalities detected in children over 10 years following initial Kawasaki disease using cardiac computed tomography

OBJECTIVE

To evaluate whether Kawasaki disease predisposes to premature atherosclerosis and to assess status of coronary artery abnormalities at least 10 years after diagnosis.

MATERIAL AND METHODS

A prospective study was carried out on 21 patients who were diagnosed with Kawasaki disease at least 10 years back and are on regular follow-up. The study was conducted on 128 Slice Dual Source computed tomography scanner with electrocardiography-triggered radiation optimised protocols for assessment of coronary artery abnormalities and calcifications.

RESULTS

Study cohort had 21 subjects - 15 males and 6 females (age range: 11-23 years; mean: 15.76 + 3.72 years). Mean age at time of diagnosis was 3.21 + 2.48 years. Mean time interval from diagnosis of Kawasaki disease to computed tomography coronary angiography was 12.59 + 2.89 years. Four children had evidence of coronary artery abnormalities on transthoracic echocardiography at time of diagnosis. Of these, two had persistent abnormalities on computed tomography coronary angiography. One subject (4.76%) had coronary calcification that was localised to abnormal coronary artery segment. Four coronary artery abnormalities (one saccular; three fusiform aneurysms) were noted in two subjects.

CONCLUSION

Prevalence of coronary artery calcification is low and, if present, is localised to abnormal segments. This calcification is likely dystrophic rather than atherosclerotic. It appears that coronary artery abnormalities can persist for several years after acute episode of Kawasaki disease. Periodic follow-up by computed tomography coronary angiography is now a feasible non-invasive imaging modality for long term surveillance of patients with Kawasaki disease who had coronary artery abnormalities at time of diagnosis.

Comparison on radiation effective dose and image quality of right coronary artery on prospective ECG-gated method between 320 row CT and 2nd generation (128-slice) dual source CT

This retrospective study was to compare the image quality of right coronary artery (RCA) and effective radiation dose on prospective ECG‐gated method between 320 row computed tomography (CT) and 2nd generation (128‐slice) dual source CT. A total of 215 candidates underwent CT coronary angiography using prospective ECG‐gated method, 120 patients enrolled in 320 row CT group, and 95 patients in dual source CT group. We divided RCA image quality scores as 1/2/3/4, which means excellent/good/adequate/not assessable and heart rates were considered, as well as the radiation dose. There is no statistically significant difference of RCA image quality of Score 1/2 between 320 row CT and 2nd generation dual source CT, but lower heart rate (<70/min) improved RCA image quality. Meanwhile, the 2nd generation dual source CT scan have significant lower radiation dose. For patients with high level heart rate variation, both prospective ECG‐gated method of 320 row CT scan (Toshiba) and 2nd generation dual source CT scan (Siemens) basically provided good image quality on RCA. There is an advantage of effective radiation dose reduction in prospective ECG‐gated method using the 2nd generation dual source CT scan. After the iodine contrast agent was injected into elbow vein, the threshold triggering method was used to carry out prospective gated scanning, and the acquired fault image was reconstructed by the standard post‐processing software of each manufacturer. The radiation dose value is obtained through the dose report automatically generated after each scan.

Sensitivity, specificity, and interobserver variability of survey thoracic radiography for the detection of heart base masses in dogs

OBJECTIVE To determine the sensitivity, specificity, and interobserver variability of survey thoracic radiography (STR) for the detection of heart base masses (HBMs) in dogs. DESIGN Retrospective case-control study. ANIMALS 30 dogs with an HBM and 120 breed-matched control dogs (60 healthy dogs and 60 dogs with heart disease and no HBM). PROCEDURES In a blinded manner, 2 observers (designated as A and B) evaluated STR views from each dog for a mass-like opacity cranial to the heart, tracheal deviation, cardiomegaly, findings suggestive of pericardial effusion or right-sided congestive heart failure, and soft tissue opacities suggestive of pulmonary metastases. Investigators subsequently provided a final interpretation of each dog's HBM status (definitely affected, equivocal, or definitely not affected). RESULTS Considering equivocal interpretation as negative or positive for an HBM, the sensitivity of STR for diagnosis of an HBM was 40.0% (95% confidence interval [CI], 22.5% to 57.5%) and 56.7% (95% CI, 38.9% to 74.4%), respectively, for observer A and 63% (95% CI, 46.1% to 80.6%) and 80.0% (95% CI, 65.7% to 94.3%), respectively, for observer B. The corresponding specificity was 96.7% (95% CI, 93.5% to 99.9%) and 92.5% (95% CI, 87.8% to 97.2%), respectively, for observer A and 99.2% (95% CI, 97.5% to 100%) and 92.5% (95% CI, 87.8% to 97.2%), respectively, for observer B. The presence of a mass-like opacity cranial to the heart or tracheal deviation, or both, was significantly associated with a true diagnosis of HBM. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that STR is a highly specific but not a highly sensitive predictor of HBM in dogs.

Fractional flow reserve based on computed tomography: an overview

Computed tomography coronary angiography (CTCA) is a technique proved to provide high sensitivity and negative predictive value for the identification of anatomically significant coronary artery disease (CAD) when compared with invasive X-ray coronary angiography. While the CTCA limitation of a ionizing radiation dose delivered to patients is substantially overcome by recent technical innovations, a relevant limitation remains the only anatomical assessment of coronary stenoses in the absence of evaluation of their functional haemodynamic significance. This limitation is highly important for those stenosis graded as intermediate at the anatomical assessment. Recently, non-invasive methods based on computational fluid dynamics were developed to calculate vessel-specific fractional flow reserve (FFR) using data routinely acquired by CTCA [computed tomographic fractional flow reserve (CT-FFR)]. Here we summarize methods for CT-FFR and review the evidence available in the literature up to June 26, 2016, including 16 original articles and one meta-analysis. The perspective of CT-FFR may greatly impact on CAD diagnosis, prognostic evaluation, and treatment decision-making. The aim of this review is to describe technical characteristics and clinical applications of CT-FFR, also in comparison with catheter-based invasive FFR, in order to make a cost-benefit balance in terms of clinical management and patient's health.

Intracranial Aneurysms: Wall Motion Analysis for Prediction of Rupture

Intracranial aneurysms are a common pathologic condition with a potential severe complication: rupture. Effective treatment options exist, neurosurgical clipping and endovascular techniques, but guidelines for treatment are unclear and focus mainly on patient age, aneurysm size, and localization. New criteria to define the risk of rupture are needed to refine these guidelines. One potential candidate is aneurysm wall motion, known to be associated with rupture but difficult to detect and quantify. We review what is known about the association between aneurysm wall motion and rupture, which structural changes may explain wall motion patterns, and available imaging techniques able to analyze wall motion.