Karsten Pohle

Detection of Coronary Artery Stenoses With Thin-Slice Multi-Detector Row Spiral Computed Tomography and Multiplanar Reconstruction

Background—We analyzed the accuracy of multi-detector row spiral computed tomography (MDCT) using a 16-slice CT scanner with improved spatial and temporal resolution, as well as routine premedication with &bgr;-blockers for detection of coronary stenoses. Methods and Results—Seventy-seven patients with suspected coronary disease were studied by MDCT (12×0.75-mm cross-sections, 420 ms rotation, 100 mL contrast agent IV at 5 mL/s). Patients with a heart rate above 60/min received 50 mg atenolol before the scan. In axial MDCT images and multiplanar reconstructions, all coronary arteries and side branches with a diameter of 1.5 mm or more were assessed for the presence of stenoses exceeding 50% diameter reduction. In comparison to invasive coronary angiography, MDCT correctly classified 35 of 41 patients (85%) as having at least 1 coronary stenosis and correctly detected 57 of 78 coronary lesions (73%). After excluding 38 of 308 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery in 77 patients) classified as unevaluable by MDCT (12%), 57 of 62 lesions were detected, and absence of stenosis was correctly identified in 194 of 208 arteries (sensitivity: 92%; specificity: 93%; accuracy: 93%; positive and negative predictive values: 79% and 97%). Conclusions—MDCT coronary angiography with improved spatial resolution and premedication with oral &bgr;-blockade permits detection of coronary artery stenoses with high accuracy and a low rate of unevaluable arteries.

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.

Association of Cardiovascular Risk Factors to Aortic Valve Calcification as Quantified by Electron Beam Computed Tomography

OBJECTIVE To analyze the association among aortic valve calcification, cardiovascular risk factors, and coronary artery calcification using electron beam computed tomography (EBCT). PATIENTS AND METHODS We analyzed cardiac EBCT data obtained for coronary calcium detection in 1000 consecutively enrolled patients (mean +/- SD age, 57.1 +/- 10 years; 69% men) between January 1, 1998, and July 23, 2001. In all patients, atherosclerotic risk factors (hyperlipidemia, hypertension, diabetes, smoking, and family history of coronary artery disease) were documented. With EBCT, the amount of coronary calcification was determined using the Agatston score, and the amount of aortic valve calcification was measured using a volumetric score. RESULTS Aortic valve calcification was detected in 177 (17.7%) of the total patient group and was found more frequently in patients with coronary calcification (20.5% in patients with coronary calcium vs 3.8% in patients without coronary calcium; P < .001), hyperlipidemia (19.5% vs 6.5%; P < .001), hypertension (21.7% vs 13.9%; P = .01), or diabetes (30.7% vs 16.6%; P = .002). The volume of aortic valve calcification was significantly higher in patients with vs without hyperlipidemia (P < .001), hypertension (P = .002), and diabetes (P = .001). In a multivariable logistic regression analysis, adjusted for age and sex, hyperlipidemia (P = .001) and the presence of coronary calcification (P < .001) were significant predictors of aortic valve calcification. CONCLUSION A significant association exists among atherosclerotic risk factors, coronary calcification, and the presence and amount of aortic valve calcification.

Noninvasive coronary angiography by magnetic resonance imaging, electron-beam computed tomography, and multislice computed tomography

In recent years, several techniques for noninvasive imaging of the coronary artery lumen (noninvasive coronary angiography) have been developed. These techniques include magnetic resonance imaging, electron-beam computed tomography, and, most recently, multislice computed tomography. Each of these techniques has specific advantages and disadvantages. Currently, EBCT seems to permit the most robust coronary artery imaging. In the future, imaging modalities will have to be further improved and validated in order to define specific areas for potential clinical applications.

Overlapping cross-sections significantly improve the reproducibility of coronary calcium measurements by electron beam tomography: a phantom study.

Purpose We conducted phantom studies to investigate whether overlapping cross-sections and volumetric scoring would significantly improve interscan reproducibility of electron beam tomography (EBT) for coronary artery calcium quantification. Method Fifteen phantoms simulating various amounts of coronary calcification were scanned in five different positions with a slice thickness of 3.0 mm and a table feed of 3.0, 2.5, and 2.0 mm. For the conventional “Agatston score” and a “volume score” (total volume of calcified lesions), interscan variabilities were compared between the three image acquisition protocols. Results Agatston score variability was significantly lower for the 2.0 mm table feed than for the 3.0 or 2.5 mm table feed (3.0 mm: 22.9 ± 10.3%; 2.5 mm: 13.6 ± 8.2%; 2.0 mm: 8.9 ± 5.5%). Volume score variability was significantly lower for 2.5 and 2.0 mm table feed than for 3.0 mm table feed (3.0 mm: 21.7 ± 11.0%; 2.5 mm: 10.9 ± 5.9%; 2.0 mm: 9.8 ± 5.9%). Conclusion Overlapping cross-sections, especially in combination with volumetric scoring, significantly improved interscan reproducibility of EBT calcium quantification in a phantom study.

Quantification of aortic valve calcification with electron beam tomography: A histomorphometric validation study

Rationale and Objectives:The exact quantification of the amount of calcification in aortic valves may be useful for the identification of risk factors for the progression of aortic valve calcification and to evaluate new therapeutic approaches for aortic valve disease. Electron beam tomography (EBT) allows the in vivo detection of calcifications in coronary vessels and in the aortic valve. The aim of this study was to validate the quantification of aortic valve calcification by EBT with in vivo and in vitro investigations. Methods:In 15 patients (aortic stenosis in 13, aortic regurgitation in 2 cases), EBT was performed before aortic valve replacement (40 cross sections, 3-mm slice thickness, matrix 512 × 512, field of view 28 cm, ECG trigger at 40% of the cardiac cycle). EBT was repeated on the explanted aortic valve using the same protocol. In both data sets, the amount of aortic valve calcification was determined using a volumetric score. In serial cuts of the explanted valve (distance 1 mm), the calcified volume was determined by an independent investigator using histomorphometric analysis. Results:The mean calcified volume of the aortic valves as quantified by EBT was 1650.0 ± 1401.0 mmł in vivo (EBT1) and 1544.4 ± 1266.5 mmł in vitro (EBT2). Histomorphometric analysis showed a mean calcified volume of 1555.7 ± 1272.5 mmł. The mean difference between EBT1 and EBT2 was 4.2 ± 14.7%, between EBT1 and histomorphometry 3.6 ± 12.1%, and between EBT2 and histomorphometry −0.5 ± 5.9%. Conclusion:EBT allows accurate in vivo quantification of aortic valve calcifications.

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.