Fabian Moselewski

Detection of Calcified and Noncalcified Coronary Atherosclerotic Plaque by Contrast-Enhanced, Submillimeter Multidetector Spiral Computed Tomography A Segment-Based Comparison With Intravascular Ultrasound

Background—We investigated the ability of multidetector spiral computed tomography (MDCT) to detect atherosclerotic plaque in nonstenotic coronary arteries. Methods and Results—In 22 patients without significant coronary stenoses, contrast-enhanced MDCT (0.75-mm collimation, 420-ms rotation) and intravascular ultrasound (IVUS) of one coronary artery were performed. A total of 83 coronary segments were imaged by IVUS (left main, 19; left anterior descending, 51; left circumflex, 4; right coronary, 9). MDCT data sets were evaluated for the presence and volume of plaque in the coronary artery segments. Results were compared with IVUS in a blinded fashion. For the detection of segments with any plaque, MDCT had a sensitivity of 82% (41 of 50) and specificity of 88% (29 of 33). For calcified plaque, sensitivity was 94% (33 of 36) and specificity 94% (45 of 47). Coronary segments containing noncalcified plaque were detected with a sensitivity of 78% (35 of 45) and specificity of 87% (33 of 38), but presence of exclusively noncalcified plaque was detected with only 53% sensitivity (8 of 15). If analysis was limited to the 41 proximal segments (segments 1, 5, 6, and 11 according to American Heart Association classification), sensitivity and specificity were 92% and 88% for any plaque, 95% and 91% for calcified plaque, and 91% and 89% for noncalcified plaque. MDCT substantially underestimated plaque volume per segment as compared with IVUS (24±35 mm3 versus 43±60 mm3, P <0.001). Conclusions—The results indicate the potential of MDCT to detect coronary atherosclerotic plaque in patients without significant coronary stenoses. However, further improvements in image quality will be necessary to achieve reliable assessment, especially of noncalcified plaque throughout the coronary tree.

In Vivo Characterization of Coronary Atherosclerotic Plaque by Use of Optical Coherence Tomography

Background—The current understanding of the pathophysiology of coronary artery disease is based largely on postmortem studies. Optical coherence tomography (OCT) is a high-resolution (≈10 μm), catheter-based imaging modality capable of investigating detailed coronary plaque morphology in vivo. Methods and Results—Patients undergoing cardiac catheterization were enrolled and categorized according to their clinical presentation: recent acute myocardial infarction (AMI), acute coronary syndromes (ACS) constituting non–ST-segment elevation AMI and unstable angina, or stable angina pectoris (SAP). OCT imaging was performed with a 3.2F catheter. Two observers independently analyzed the images using the previously validated criteria for plaque characterization. Of 69 patients enrolled, 57 patients (20 with AMI, 20 with ACS, and 17 with SAP) had analyzable images. In the AMI, ACS, and SAP groups, lipid-rich plaque (defined by lipid occupying ≥2 quadrants of the cross-sectional area) was observed in 90%, 75%, and 59%, respectively (P=0.09). The median value of the minimum thickness of the fibrous cap was 47.0, 53.8, and 102.6 μm, respectively (P=0.034). The frequency of thin-cap fibroatheroma (defined by lipid-rich plaque with cap thickness ≤65 μm) was 72% in the AMI group, 50% in the ACS group, and 20% in the SAP group (P=0.012). No procedure-related complications occurred. Conclusions—OCT is a safe and effective modality for characterizing coronary atherosclerotic plaques in vivo. Thin-cap fibroatheroma was more frequently observed in patients with AMI or ACS than SAP. This is the first study to compare detailed in vivo plaque morphology in patients with different clinical presentations.

Predictive Value of 16-Slice Multidetector Spiral Computed Tomography to Detect Significant Obstructive Coronary Artery Disease in Patients at High Risk for Coronary Artery Disease Patient- Versus Segment-Based Analysis

Background—In this study, we investigated the diagnostic value and limitations of multidetector computed tomography (MDCT)–based noninvasive detection of significant obstructive coronary artery disease (CAD) in a consecutive high-risk patient population with inclusion of all coronary segments. Methods and Results—In a prospective, blinded, standard cross-sectional technology assessment, a cohort of 33 consecutive patients with a positive stress test result underwent 16-slice MDCT and selective coronary angiography for the detection of significant obstructive CAD. We assessed the diagnostic accuracy of MDCT in a segment-based and a patient-based model and determined the impact of stenosis location and the presence of calcification on diagnostic accuracy in both models. Analysis of all 530 coronary segments demonstrated moderate sensitivity (63%) and excellent specificity (96%) with a moderate positive predictive value of 64% and an excellent negative predictive value (NPV) of 96% for the detection of significant coronary stenoses. Assessment restricted to either proximal coronary segments or segments with excellent image quality (83% of all segments) led to an increase in sensitivity (70% and 82%, respectively), and high specificities were maintained (94% and 93%, respectively). In a patient-based model, the NPV of MDCT for significant CAD was limited to 75%. Coronary calcification was the major cause of false-positive findings (94%). Conclusions—For all coronary segments included, 16-slice MDCT has moderate diagnostic value for the detection of significant obstructive coronary artery stenosis in a population with a high prevalence of CAD. The moderate NPV of patient-based detection of CAD suggests a limited impact on clinical decision-making in high-risk populations.

Coronary Multidetector Computed Tomography in the Assessment of Patients With Acute Chest Pain

Background— Noninvasive assessment of coronary atherosclerotic plaque and significant stenosis by coronary multidetector computed tomography (MDCT) may improve early and accurate triage of patients presenting with acute chest pain to the emergency department. Methods and Results— We conducted a blinded, prospective study in patients presenting with acute chest pain to the emergency department between May and July 2005 who were admitted to the hospital to rule out acute coronary syndrome (ACS) with no ischemic ECG changes and negative initial biomarkers. Contrast-enhanced 64-slice MDCT coronary angiography was performed immediately before admission, and data sets were evaluated for the presence of coronary atherosclerotic plaque and significant coronary artery stenosis. All providers were blinded to MDCT results. An expert panel, blinded to the MDCT data, determined the presence or absence of ACS on the basis of all data accrued during the index hospitalization and 5-month follow-up. Among 103 consecutive patients (40% female; mean age, 54±12 years), 14 patients had ACS. Both the absence of significant coronary artery stenosis (73 of 103 patients) and nonsignificant coronary atherosclerotic plaque (41 of 103 patients) accurately predicted the absence of ACS (negative predictive values, 100%). Multivariate logistic regression analyses demonstrated that adding the extent of plaque significantly improved the initial models containing only traditional risk factors or clinical estimates of the probability of ACS (c statistic, 0.73 to 0.89 and 0.61 to 0.86, respectively). Conclusions— Noninvasive assessment of coronary artery disease by MDCT has good performance characteristics for ruling out ACS in subjects presenting with possible myocardial ischemia to the emergency department and may be useful for improving early triage.

Comparison of anthropometric, area- and volume-based assessment of abdominal subcutaneous and visceral adipose tissue volumes using multi-detector computed tomography

Purpose:Cross-sectional imaging may enable accurate localization and quantification of subcutaneous and visceral adipose tissue. The reproducibility of multi-detector computed tomography (MDCT)-based volumetric quantification of abdominal adipose tissue and the ability to depict age- and gender-related characteristics of adipose tissue deposition have not been reported.Methods:We evaluated a random subset of 100 Caucasian subjects (age range: 37–83 years; 49% women) of the Framingham Heart Study offspring cohort who underwent MDCT scanning. Two readers measured subcutaneous and visceral adipose tissue volumes (SAV and VAV; cm3) and areas (SAA and VAA; cm2) as well as abdominal sagital diameter (SD) and waist circumference (WC).Results:Inter-reader reproducibility was excellent (relative difference: −0.34±0.52% for SAV and 0.59±0.93% for VAV, intra-class correlation (ICC)=0.99 each). The mean SAA/VAA ratio was significantly different from the mean SAV/VAV ratio (2.0±1.2 vs 1.7±0.9; P<0.001). The ratio of SAV/VAV was only weakly inversely associated with SD (ICC=−0.32, P=0.01) and not significantly associated with WC (ICC=−0.14, P=0.14) or body mass index (ICC=−0.17, P=0.09). The mean SAV/VAV ratio was significantly different between participants <60 vs >60 years (1.9±1.0 vs 1.5±0.7; P<0.001) and between men and women (1.2±0.5 vs 2.2±0.9; P<0.001).Conclusion:This study demonstrates that MDCT-based volumetric quantification of abdominal adipose tissue is highly reproducible. In addition, our results suggest that volumetric measurements can depict age- and gender-related differences of visceral and subcutaneous abdominal adipose tissue deposition. Further research is warranted to assess whether volumetric measurements may substantially improve the predictive value of obesity measures for insulin resistance, type 2 diabetes mellitus and other diseases.

Noninvasive evaluation of cardiac veins with 16-MDCT angiography.

OBJECTIVE Anatomic mapping of the cardiac veins is important to guide transvenous therapeutic procedures such as biventricular pacing. As an alternative to invasive venography, we studied the feasibility of MDCT of the cardiac venous anatomy. CONCLUSION Cardiac venous anatomy is variable. MDCT is a noninvasive method that allows detailed imaging of the cardiac venous anatomy, including small cardiac veins and thebesian valves. Therefore, cardiac MDCT may be a valuable tool for guiding procedures that involve the cardiac venous system.

Calcium Concentration of Individual Coronary Calcified Plaques as Measured by Multidetector Row Computed Tomography

Background—Characteristics of individual calcified plaques, especially calcium concentration (CC), may provide incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and evaluation of therapeutic intervention. In this study, therefore, we assessed the characteristics of individual calcified plaques and their relationship to other parameters derived from CT analysis of coronary calcium in a community-based cross-sectional cohort. Methods and Results—Coronary artery calcium (CAC) was analyzed in 612 participants of the Framingham Heart Study (third-generation and offspring cohorts) using prospectively ECG-triggered multidetector CT. We determined the CC, Agatston score, calcified volume, and mineral mass of individual calcified plaques in each subject. Heterogeneity of CC was defined as the standard deviation of CC of all individual calcified plaques in a subject. CAC was detected in 274 of 605 subjects. After excluding 57 subjects (21%) because of motion artifacts, we identified a total of 956 calcified coronary plaques in 217 subjects (74 women, 143 men; mean age, 57.1±10.8 years) with detectable CAC and no image artifacts. CC of individual calcified plaques was independent of subject age (P=0.76) and sex (197.8±74.8 versus 183.6±52.8 mg/cm3 for men versus women; P=0.21). Among a subgroup of 125 subjects with multiple (≥3) individual calcified plaques, CC was heterogeneous within individual subjects (mean SD of CC, 43.6±23.1 mg/cm3). The degree of heterogeneity of CC in these subjects was independent of age (P=0.60), sex (P=0.99), and number of plaques (P=0.06). Conclusions—The CC of individual calcified plaques is independent of age and sex but heterogeneous within a subject, which may reflect that the pathological process of calcified plaque formation and progression is the same in men and women regardless of age. CC may have incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and the evaluation of therapeutic intervention. Further studies are warranted to confirm that individual plaque analysis is preferable to global CAC scores to evaluate progression of atherosclerosis and to assess whether individual plaque analysis may be complementary to global CAC measures to assess coronary event risk.

Clinical results of minimally invasive coronary angiography using computed tomography

Fast, high-resolution CT techniques, such as EBCT and MDCT permit imaging of the coronary arteries. Continuous improvements in the capabilities of both technologies for visualization of the coronary lumen and detection of coronary artery stenoses are being made. Image quality currently is not robust enough in all patients to consider non-invasive coronary angiography by EBCT and MDCT a routine clinical tool. In selected patients and carefully performed, however, they show promise as means to exclude the presence of coronary artery stenoses in a non-invasive fashion. This may become a beneficial and important application of these technologies. Other possible applications pertain to smaller patient subsets, such as patients with anomalous coronary arteries, fistulas or aneurysms. The development of techniques to visualize non-calcified plaque is interesting with respect to assessment of coronary risk, but this requires further investigation.

Response to Letter Regarding Article, “Coronary Multidetector Computed Tomography in the Assessment of Patients With Acute Chest Pain”

We thank Dr Hamon and colleagues1 for their interest in our work. We agree that our data demonstrate that both the absence of coronary artery plaque or stenosis on noninvasive coronary multidetector computed tomography (MDCT) angiography has high negative predictive value for the subsequent diagnosis of acute coronary syndrome. However, as …