Noninvasive assessment of coronary atherosclerosis by multidetector-row computed tomography

Current contrast media delivery strategies for cardiac and pulmonary multidetector-row computed tomography angiography

Recent advances in multidetector-row computed tomography (MDCT) have led to substantial improvements in coverage area, acquisition speed, and temporal/spatial resolution, which have strengthened the performance of thoracic and cardiac MDCT angiography but have also imposed new challenges for optimization of contrast medium enhancement and scan acquisition strategies. Understanding contrast media dynamics is fundamental for the design of scan acquisition and injection protocols. This article examines the fundamentals of the physiological and contrast delivery factors that determine the quality of contrast enhancement, emphasizing the modifications required in contrast delivery protocols for optimizing cardiothoracic MDCT angiography with modern-era MDCT scanners.

ACR clinical statement on noninvasive cardiac imaging

Coronary artery disease and other acquired and congenital cardiac diseases are major medical and socio-economic problems. Historically, imaging has had a critical role in the diagnosis and evaluation of acquired and congenital cardiac disease. Advances in computed tomography (CT), with multidetector CT and electron beam CT technology, and magnetic resonance (MR) imaging, now make it possible to noninvasively image the coronary arteries, cardiac chambers, valves, myocardium, and pericardium and assess cardiac function, and CT and MR imaging are becoming increasingly important in the evaluation of cardiac disease. Radiologists, because of their extensive experience in CT and MR imaging, have an important role in imaging cardiac patients using these modalities. This clinical statement of the ACR discusses various technical and patient safety issues related to cardiac CT and MR imaging, and it suggests appropriate qualifications for radiologists until such time as ACR practice guidelines for the performance of cardiac CT and cardiac MR imaging are written and approved through the usual ACR process. It stresses that the interpreting physician is responsible for examining not only the cardiac structures of interest but also all the visualized noncardiac structures and must report any clinically relevant abnormalities of these adjacent structures.

Quantitative X-ray imaging of intraplaque hemorrhage in aortas of apoE(-/-)/LDL(-/-) double knockout mice

OBJECTIVES

To determine if hemorrhage into an arterial wall can be detected in CT images by virtue of the iron content.

MATERIALS AND METHODS

Aortas from male apoE(-/-)/LDL(-/-) mice (n = 31) were infused in situ with contrast agent, for micro-CT scanning and histology. Roentgen-opacities within the aortic walls were identified by histology and micro-x-ray fluorescence to be iron or calcium. Dual-energy scanning was performed at 2 energy levels using synchrotron-based micro-CT [(2 microm)(3) voxels, 16 and 20 keV] and 64-slice CT (0.4 x 0.4 x 0.6 mm voxels, 80 and 120 kVp).

RESULTS

Opacities were identified as hemorrhage-related clusters of multiple punctate deposits, containing both Fe (0.48 x 10(-12) g/voxel) and Ca (3.18 x 10(-2) g/voxel), or as isolated confluent accumulations of exclusively calcium. Subtraction of the dual-energy CT scans discriminated iron from calcium deposits.

CONCLUSION

Detection and quantification of iron deposits in hemorrhaged atherosclerotic lesions is feasible by dual-energy CT imaging.

CT angiography is here--are we expected to see a change of angiography referral pattern?

A 52-year-old asymptomatic man, with cardiac risk factors of hypertension, Type II diabetes, hypertriglyceridemia, low HDL, obesity, and positive family history for early coronary artery disease (CAD), was referred to nuclear stress test. He exercised for 14 minutes, achieved his target heart rate, without any symptoms or ECG changes. Nuclear images were entirely normal. However, the patient was still concerned and anxious so he underwent CT angiography that revealed coronary narrowings. Next, he underwent coronary angiography with similar findings. The lesions were treated with stents. We present a case report to illustrate how newer technology such as CT angiography alters the way in which we diagnose CAD and decide on whether to pursue further invasive therapy.