Non-invasive measurement of coronary plaque from coronary CT angiography and its clinical implications

Coronary CT angiography (CTA) is increasingly used worldwide for direct, non-invasive evaluation of the coronary arteries. Advances in computed tomography (CT) technology over the last decade have enabled such reliable imaging of the coronary arteries. Beyond arterial stenosis, coronary CTA also permits assessment of atherosclerotic plaque (including plaque burden) and coronary artery remodeling, previously only achievable through invasive means. It has been shown that coronary plaque volumes for non-calcified and mixed plaques and the arterial remodeling index, correlate closely with invasive intravascular ultrasound. Several studies have also shown a strong relationship of adverse plaque features imaged by coronary CTA with acute coronary syndrome, all-cause death, major adverse cardiovascular events and myocardial ischemia. The aim of this review is to summarize current methods for quantitative measurement of atherosclerotic plaque features from coronary CTA and to discuss their clinical implications.     

Coronary Artery Thrombosis Developing during Angiography

ABSTRACT A case of coronary thrombosis developing during coronary arteriography is described. In spite of obstruction of a main coronary artery, only a small myocardial infarction developed. Increased coagulability probably contributed to the thrombus formation.     

Magnetic resonance angiography (MRA) of the circle of Willis: a prospective comparison with conventional angiography in 54 subjects

We prospectively correlated the findings of magnetic resonance angiography (MRA) with those of transfemoral four-vessel angiography in 54 patients to investigate the direction of flow within the circle of Willis. Our primary goal was to assess the direction of flow using the size of the vessel and signal intensity, without saturation techniques. Analysis of the circle of Willis, especially the communicating arteries, was performed double-blind by two groups of two radiologists. Three types of arteries were identified: high flow or cross-cerebral circulation, patent and nonvisualised arteries. Cerebral angiography was the standard for comparison between the two methods. MRA did not reveal any arteries invisible on angiography, thus providing a specificity of 100%. The sensitivity of MRA was 89.2% for the anterior and 81.3% for the posterior communicating arteries, and 100% for the anterior, middle and posterior cerebral arteries. MRA was shown to be a useful technique for the assessment of patency of the circle of Willis.     

颅内血管性病变的磁共振时间飞跃法血流成像

报告了３０例颅内血管性病变的磁共振时间飞跃法（ＴＯＦ）血流成像资料，包括动脉瘤８例、动静脉畸形１３例和血管闭塞９例。其中２１例作了与ＤＳＡ的对照。结果发现，ＴＯＦ血流成像方法无创伤、危险小、检查时间短，对颅底动脉环和动脉瘤显示较好，可显示动静脉畸形（ＡＶＭ）的供血动脉和引流静脉，大血管的闭塞诊断准确。缺点是图像欠清晰、伪迹较多。三维成像分辨力高、图像对比好，但对慢血流不敏感。笔者认为ＭＲＴＯＦ血流成像具有明显的临床实用价值。     

冠心病的电影摄影诊断：附23例报告

本文分析２３例冠心病患者的电影摄影所见，着重分析室壁瘤形成与冠状动脉狭窄的程度，部位，数目，仙支血管形成和临床病性等因素的关系，此外，对冠心病中继发二尖瓣返流的成因和机理进行了探讨。讨论中提出以下三点：（１）室壁瘤的发生与冠状动脉主要分支的严重狭窄关系最密切；（２）侧支循环能防止心肌梗塞范围扩大及室壁瘤形成；（３）二尖瓣返流与主要冠状动脉病变的狭窄程序及室壁瘤的存在有关，并对影响侧支循环显示的因素     

Coronary arteries

Conventional coronary angiography (CA) is the standard of excellence for the evaluation of coronary artery disease. However, non-invasive imaging modalities have developed that can play an important clinical role in the diagnosis. Magnetic resonance imaging (MRI) can offer a comprehensive evaluation of the heart and the coronary arteries by virtue of its high soft tissue contrast capabilities, double-oblique tomographic sections and the possibility of quantifying physiological parameters without need of ionizing radiation. Magnetic resonance coronary arteriography (MRCA) using breath-hold and free-breathing techniques has been investigated but is still in the experimental phase; its precise role for the assessment of coronary stenosis must still be identified. Nonetheless, MRCA has proven clinically relevant in determining the course of anomalous coronary arteries and the patency of coronary artery bypass grafts. Novel intravascular contrast agents promise faster coverage of the cardiac anatomy and may provide a long-awaited boost for MRCA. Contrast-enhanced electron-beam computed tomography (EBT), another competing imaging modality, is now being subjected to widespread evaluation following initially encouraging results. Received 16 February 1998; Accepted 24 February 1998     

Detection of coronary artery calcifications predicting coronary heart disease: comparison of fluoroscopy and spiral CT

The aim of this study was to evaluate the clinical relevance of coronary artery calcifications detected by spiral CT, congruence with fluoroscopy (FS) and coronary angiography, and comparison with studies reporting on application of double-helical CT and ultrafast CT. Forty patients underwent spiral CT (2-mm slice thickness, table feed 3 mm/s), coronary angiography, and FS (performed in the usual manner). Stenosis and calcifications were evaluated semiquantitatively. Nineteen patients suffering from a stenosis ≥ 75 % were verified at coronary angiography. All had coronary artery calcification on spiral CT. Fluoroscopy did not detect 8 of 19 patients with a stenosis ≥ 75 % (1 vessel: n = 1; 2 vessels: n = 3; 3 vessels: n = 4). In spiral CT sensitivity was 100 % and specificity was 33 % (FS: 58 and 48 %). Positive predictive value was 83 % for spiral CT (FS: 50 %), and negative predictive value was 100 % (FS: 56 %). A significant linear increase in the calcification score was found for increasing maximal stenosis (p < 0.005). Spiral CT is more sensitive than FS in the recognition of hemodynamic relevant stenoses using the detection of coronary artery calcifications. Statistical parameters are comparable to ultrafast-CT. Spiral CT is a suitable non-invasive diagnostic technique in coronary heart disease. Coronary calcifications found incidentally in symptomatic patients at chest CT should be reported to the referring physician for further cardiological workup. Received 14 July 1997; Revision received 29 December 1997; Accepted 5 January 1998     

Carotid stenosis: a comparison between MR and spiral CT angiography

We performed a preliminary study comparing three-dimensional time-of-flight (3 D TOF) magnetic resonance angiography (MRA) and spiral CT angiography (SCTA) in the detection and assessment of internal carotid artery stenosis. Digital subtraction angiography (DSA) was the reference examination. We examined 20 patients with signs of cerebrovascular insufficiency, who underwent MRA, SCTA and DSA within a 3 day period. Both internal carotid arteries were assessed by three blinded readers for degree of stenosis at two different levels (bulb and remaining section) giving a total of 80 assessments. Interobserver variability, sensitivity, specificity, diagnostic accuracy, concordance, overestimation and underestimation were assessed. Interobserver variability was not statistically significant. MRA showed higher sensitivity, specificity, diagnostic accuracy and concordance than SCTA (92.0 % vs 80.8 %, 98.2 % vs 96.4 %, 96.3 % vs 91.3 % and 96.0 % vs 88.0 %, respectively). MRA gave rise to a 5.0 % overestimation rate, whereas SCTA occasioned a 7.5 % underestimation rate. These differences are not statistically significant. These results suggest that MRA is a more useful, noninvasive modality for assessment of the internal carotid artery with a more than 70 % stenosis. Received: 8 August 1997 Accepted: 10 October 1997     

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 ± 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3–0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 ± 0.12 cm vs 1.09 ± 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients. Received 15 July 1997; Revision received 30 September 1997; Accepted 5 November 1997     

Intracranial vascular stenosis and occlusion: comparison of 3D time-of-flight and 3D phase-contrast MR angiography

We compared the value of 3D time-of-flight (TOF) and phase-contrast (PC) MR angiography (MRA) for detection and grading of intracranial vascular steno-occlusive disease. Unenhanced 3D-TOF MRA and 3D-PC MRA (30–60 cm/s velocity encoding) were performed at the level of the circle of Willis in 18 patients, mean age 56 ± 10 years. Postprocessed images using a maximum-intensity projection reconstruction with multiple targetted projections were analysed. A total of 126 vessels was assessed by PC MRA and 143 by TOF MRA, with digital subtraction angiography (DSA) in 15 patients and/or transcranial Doppler sonography (TCD) in 18 as a standard. Two blinded readers reviewed the MRA, DSA and TCD examinations retrospectively. On DSA and/or TCD the two observers found 32 and 28 steno-occlusive lesions. 3D-TOF MRA was more sensitive than 3D-PC MRA (87 % and 86 % vs. 65 % and 60 %) and had a higher negative predictive value (96 % vs. 89 %). Correct grading of stenoses was achieved in 78 % by 3D-TOF and 65 % by 3D-PC MRA. Received: 24 September 1997 Accepted: 27 February 1998