[Septal delineation using a 20 % diluted contrast chaser bolus in coronary CT angiography: a comparison of 64-slice and dual source CT]. / Abgrenzbarkeit des interventrikulären Septums mit einem 20 % Kontrastmittelspülbolus in der CT-Koronarangiografie: Ein Vergleich von 64-Schicht- und Dual-Source-CT.

PURPOSE: Due to the technical advance of multislice cardiac CT and the recently introduced dual source CT, the acquisition times for cardiac CT exams are < 10 sec. At the same time the assessment of left ventricular function is possible. However, in many patients a complete right ventricular outwash is noted, leading to insufficient septal delineation. Studies were able to demonstrate that contrast media (CM) mixed in the saline chaser bolus is sufficient for significantly better visualization of septal structures. The aim of this study was to investigate whether this dual flow concept works as well for 64-slice and dual source CT angiography using only 20 % CM in the saline chaser bolus. MATERIALS AND METHODS: 97 patients were included in this prospective study. 47 patients underwent 64-slice CT coronary angiography. 80 cc were administered at 5 cc/sec as the main bolus followed by a 50 cc saline chaser bolus containing 20 % contrast media. The other 50 patients were examined using dual source CT. They received a CM protocol adapted for the scan time with the identical saline/CM chaser bolus. The datasets were quantitatively examined in defined ROIs along the septum and in the right ventricle with respect to the density. The septal delineation was qualitatively analyzed and both groups were compared. In a final step the density was measured in the proximal and distal RCA as well as in the LAD and also compared. RESULTS: Using the protocol adapted for the scan time, significantly less CM was used. No significant difference was able to be found regarding the septal delineation or coronary enhancement. CONCLUSION: The study shows that the dual flow concept allows for robust septal delineation regardless of the CM injection protocol used as long as a 20 % saline chaser bolus is used. A CM protocol adapted for the scan time also leads to significant CM reduction at equal image quality.

[Initial experience with prospectively triggered, sequential CT coronary angiography on a 128-slice scanner]. / Erste Erfahrungen mit der sequenziellen, prospektiv getriggerten CT-Koronarangiografie an einem 128-Schicht-Computertomografen.

PURPOSE: Spiral CT angiography (CTA) of the coronaries using low-pitch scanning and ECG-gated image reconstruction is a robust method for detecting or excluding relevant coronary plaque. However, the resulting dose exposure is considerable. The aim of the present study was to evaluate image quality and artifacts as well as to record dose values for sequential coronary CTA using a 128-slice scanner with a temporal resolution of 150 ms. MATERIALS AND METHODS: 20 patients with a regular heart rate and without contraindications for oral/I.V. beta blockers, who were referred for CTA of the coronaries for exclusion or detection of relevant plaques, were examined by sequential CTA with the following parameters: 120 kV, 200 ref mAs, collimation 2 x 64 x 0.6, table feed of 34.5 mm at a detector width of 38.4 mm. A total acquisition time of 380 ms per table position allowed for mild shifting of the reconstruction window within the cardiac cycle of +/- 5 %. 50 ml of contrast agent were injected at 5 ml/s followed by a 50 ml split bolus (20 % contrast). The individual start delay was determined by a test bolus scan (10 ml contrast + 50 ml saline flush at 5 ml/s). The image quality for each segment, coronary artery, and patient was determined on a 4-point scale. Dose values were estimated based on the individual dose length product as provided by the scanner's patient protocol. Artifacts were evaluated to determine the cause (calcium vs. motion). RESULTS: All patients received beta blocker pretreatment. The mean heart rate was 62 +/- 5 beats/min. 5 % (13 / 286) of all segments in 5 / 20 patients were rated as non-diagnostic. The mean dose length product was 213 mGy x cm, and the mean effective dose was 3.6 mSv. Calcifications were the major cause of non-diagnostic images. However breathing or other motion artifacts occurred as well. CONCLUSION: In select patients with effective heart rate control and thorough instruction for breath hold compliance, sequential CTA of the coronaries using a 128-slice scanner with a temporal resolution of 150 ms is technically feasible. The resulting effective dose values are clearly below those of spiral coronary CT scans.

Strategies for dose-optimized imaging in pediatric cardiac dual source CT.

PURPOSE: As a result of rapid advances in CT technology, including dual source CT, cardiac CT exams at high heart rates are feasible, making pediatric cardiac CT in congenital heart disease possible. Dose concerns and patient size variability make general recommendations difficult. The aim of this study was to investigate which scanner settings are suitable for multiple weight groups to provide dose-optimized scanning. MATERIALS AND METHODS: All 12 patients underwent a contrast-enhanced gated dual source CT exam. A maximum of 2 ml/kg body weight or 60 ml contrast was applied. Scanner settings at 80 and 120 kV, as well as weight-adapted mAs settings were used in an iterative fashion. Datasets were assessed for image quality and dose-optimized scan parameters were established via class comparison. In a final step a table was created as a recommendation for cardiac CT in children corresponding to their body weight. Strategies for optimized contrast application with hand vs. manual injection were explored. RESULTS: In all children diagnostic image quality was obtained. In children < 60 kg, 80 kV can be used, in all others 100 kV is sufficient. The eff. mAs varied from 362 mAs to 30 mAs depending on body weight. Retrospectively a significant dose reduction would have been possible in 6 / 12 patients. Cardiac CT can be performed between 0.6 and 3.2 mSv in a pediatric population. CONCLUSION: The present study shows that dual source cardiac CT is a potential diagnostic alternative in children with congenital heart disease without excessive radiation exposure or contrast media application.

[Dual-source CT: in vitro characterization of gallstones using dual energy analysis]. / Dual-Source-CT: In-vitro-Charakterisierung von Gallensteinen mittels Dual-Energy-Analyse.

PURPOSE: Despite clinically available high-resolution CT, the detection and classification of gallstones remains a challenge in some cases. This pilot study examines whether noninvasive characterization of gallstones in vitro is possible using dual-energy analysis (DECT) of dual source CT datasets. MATERIALS AND METHODS: A total of 43 gallstones (0.4 - 1.5 cm) were examined at 80 kV, 140 kV and in the dual-energy mode. The monoenergetic datasets were examined by two independent examiners and classified as calcium, cholesterol or pigment stones. The results were compared with the pathological classification as the clinical gold standard. After creating reference images for each group via dual-energy analysis, the classification was repeated and compared with the gold standard again. RESULTS: Using the monoenergetic analysis at 80 kV, the sensitivity and specificity were 100 / 84 % and 100 / 88 % for calcium stones. For cholesterol stones the values were 54 / 89 % and 54 / 85 % and for pigment stones 70 / 80 % for both examiners. At 140 kV, the sensitivity and specificity for calcium stones were 100 / 84 % for both examiners, 46 / 92 % for cholesterol stones for both examiners and the sensitivity and specificity were 80 / 75 % and 80 / 80 % for pigment stones. Using the reference images established by DECT, both examiners were able to correctly classify all gallstones. CONCLUSION: The present data indicates that DECT is able to correctly classify Gallstones according to the clinical gold standard in vitro. Clinical studies have to demonstrate whether these results lead to optimized clinical decision making.

Stereolithographic reproduction of complex cardiac morphology based on high spatial resolution imaging.

BACKGROUND: Precise knowledge of cardiac anatomy is mandatory for diagnosis and treatment of congenital heart disease. Modern imaging techniques allow high resolution three-dimensional (3D) imaging of the heart and great vessels. In this study stereolithography was evaluated for 3D reconstructions of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) data. METHODS: A plastinated heart specimen was scanned with MDCT and after segmentation a stereolithographic (STL) model was produced with laser sinter technique. After scanning the STL model with MDCT these data were compared with those of the original specimen after rigid registration using the iterative closest points algorithm (ICP). The two surfaces of the original specimen and STL model were matched and the symmetric mean distance was calculated. Additionally, the heart and great vessels of patients (age range 41 days-21 years) with congenital heart anomalies were imaged with MDCT (n=2) or free breathing steady, state free-precession MRI (n=3). STL models were produced from these datasets and the cardiac segments were analyzed by two independent observers. RESULTS: All cardiac structures of the heart specimen were reconstructed as a STL model within sub-millimeter resolution (mean surface distance 0.27+/-0.76 mm). Cardiac segments of the STL patient models were correctly analyzed by two independent observers compared to the original 3D datasets, echocardiography (n=5), x-ray angiography (n=5), and surgery (n=4). CONCLUSIONS: High resolution MDCT or MRI 3D datasets can be accurately reconstructed using laser sinter technique. Teaching, research and preoperative planning may be facilitated in the future using this technique.

64-slice computed tomography assessment of coronary artery stents: a phantom study.

PURPOSE: To compare the use of a new 64-slice computed tomography (CT) scanner with 16-slice CT in the visualization of coronary artery stent lumen. MATERIAL AND METHODS: Eight different coronary artery stents, each with a diameter of 3 mm, were placed in a static chest phantom. The phantom was positioned in the CT gantry at an angle of 0 degrees and 45 degrees towards the z-axis and examined with both a 64-slice and a 16-slice CT scanner. Effective slice thickness was 0.6 mm with 64-slice CT and 1 mm with 16-slice CT. A reconstruction increment of 0.3 mm was applied in both scanners. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using paired Wilcoxon tests. RESULTS: Artificial lumen reduction was significantly less with 64-slice than with 16-slice CT. Average visible stent lumen was 53.4% using 64-slice CT and 47.5% with 16-slice MSCT. Most severe artifacts were seen in stents with radiopaque markers. Using 64-slice CT, image noise increased by approximately 30% due to thinner slice thickness. CONCLUSION: Improved spatial resolution of 64-slice CT resulted in superior assessment of coronary artery stent lumen compared to 16-slice CT. However, a relevant part of the stent lumen is still not assessable with multi-slice CT.

Image quality and diagnostic accuracy of 16-slice multidetector computed tomography for the detection of coronary artery disease in obese patients.

BACKGROUND: Cardiac multislice spiral computed tomography (MSCT) scanners permit visualization of the coronary arteries with an overall good sensitivity (sens) and specificity (spec). However, in obese patients (pts), who are at higher risk to develop coronary artery disease (CAD), image quality of MSCT is supposed to be limited. At present, there are no data whether the accuracy of MSCT depends on the body mass index (BMI). Thus, we compared the catheter-controlled MSCT results from normal weight and obese pts in a cohort of 117 pts with regard to sens, spec, positive predictive value (PPV), negative predictive value (NPV) and image quality. METHODS AND MATERIAL: In all, 21 normal weight pts (group I: BMI<25, 64.6+/-11.1 years, number of risk factors 2.1+/-1.1), 60 pts with mild overweight (group II: BMI 25-30, 64.6+/-8.9 years, number of risk factors 3.4+/-1.0) and 36 obese pts (group III: BMI >30, 63.0+/-8.5 years, number of risk factors 3.4+/-0.9) were examined by MSCT (Sensation 16 Speed 4 D((R)), Siemens, Germany, gantry rotation time 375 ms) and invasive coronary angiography. MSCT results were compared blinded to the results of the coronary angiography with regard to the presence or absence of a significant stenosis (>50%) in a modified AHA 13 segment (sgt) model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (insufficient image quality) for each sgt. RESULTS: Sens, spec, PPV and NPV were statistically not different in all three groups (I: 0.88/0.97/0.91/0.96, II: 0.83/0.97/0.88/0.95, III: 0.87/0.99/0.96/0.96). 3 pts (group I 1, group II 2) had to be excluded from analysis due to technical problems. Group I had significantly less risk factors (P < 0.001) and image quality was significantly better than in group II and III (P < 0.05). Group II and III did not differ with regard to risk factors or image quality. CONCLUSIONS: Overweight and obesity have an impact on MSCT image quality but did not hamper the diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out CAD also in pts with higher BMI. These retrospective data have to be confirmed in larger prospective trials.

Image quality and diagnostic accuracy of non-invasive coronary imaging with 16 detector slice spiral computed tomography with 188 ms temporal resolution.

OBJECTIVE: To evaluate image quality and clinical accuracy in detecting coronary artery lesions with a new multidetector spiral computed tomography (MDCT) generation with 16 detector slices and a temporal resolution of 188 ms. METHODS: 124 consecutive patients scheduled for invasive coronary angiography (ICA) were additionally studied by MDCT (Sensation 16 Speed 4D). MDCTs were analysed with regard to image quality and presence of coronary artery lesions. The results were compared with ICA. RESULTS: 120 of 124 scans were successful. The image quality of all remaining 120 scans was sufficient (mean (SD) heart rate 64.2 (9.8) beats/min, range 43-95). The mean calcium mass was 167 (223) mg (range 0-1038). Thirteen coronary segments were evaluated for each patient (1560 segments in total). Image quality was graded as follows: excellent, 422 (27.1%) segments; good, 540 (34.6%) segments; moderate, 277 (17.7%) segments; heavily calcified, 215 (13.8%) segments; and blurred, 106 (6.8%) segments. ICA detected 359 lesions with a diameter stenosis > 50% and MDCT detected 304 of 359 (85%). Sensitivity, specificity, and positive and negative predictive values were 85%, 98%, 91%, and 96%, respectively. The correct clinical diagnosis (presence or absence of at least one stenosis > 50%) was obtained for 110 of 120 (92%) patients. CONCLUSIONS: MDCT image quality can be further improved with 16 slices and faster gantry rotation time. These results in an unselected population underline the potential of MDCT to become a non-invasive diagnostic alternative, especially for the exclusion of coronary artery disease, in the near future.

Clinical use of multislice spiral computed tomography in 210 highly preselected patients: experience with 4 and 16 slice technology.

OBJECTIVE: To report an initial experience with multislice spiral computed tomography (MSCT) coronary imaging, as well as differences in diagnostic accuracy between 4 slice and 16 slice MSCT technology. METHODS AND RESULTS: 210 patients underwent MSCT coronary angiography (4 slices, n = 120; 16 slices, n = 90; suspicion of coronary artery disease, n = 158; suspicion of restenosis, n = 52). Recommendations for further diagnostic tests were based on the MSCT results. Patients were interviewed by telephone after a mean (SD) of 449 (169) days to evaluate their further clinical course. MSCT detected significant lesions in 90 of 210 (43%) patients and invasive coronary angiography (ICA) was recommended. MSCT excluded significant lesions in 120 of 210 (57%) patients. ICA was actually performed in 44 of 210 (21%) patients (corresponding results, 27 of 44 (61%); false positive, 11 of 44 (25%); false negative, 6 of 44 (14%)). No significant differences were found between 4 and 16 slice imaging. No major cardiac event occurred during follow up. CONCLUSIONS: MSCT was found to be useful to evaluate the need for invasive diagnostic procedures. However, the false negative results underline that further improvements of image quality are required before MSCT can replace ICA in carefully selected patients.

Non-invasive evaluation of atherosclerosis with contrast enhanced 16 slice spiral computed tomography: results of ex vivo investigations.

OBJECTIVE: To evaluate the diagnostic accuracy of 16 slice computed tomography (CT) in determining plaque morphology and composition in an experimental setting. The results were compared with histopathological analysis as the reference standard. METHODS: Nine human popliteal arteries derived from amputations because of atherosclerotic disease were investigated with multislice spiral CT (MSCT). Atherosclerotic lesions were morphologically classified (completely or partially occlusive, concentric, eccentric), and tissue densities were determined within these plaques. In addition, vessel dimensions were quantitatively measured. RESULTS: The results were compared with histological analysis. The concordance index kappa for morphological classification was 0.88. Plaque density (n = 51 lesions) was significantly different (p < 0.0001) between lipid rich, fibrotic, and calcified lesions (Stary stage III: n = 2, 58 (8) Hounsfield units (HU); Stary V: n = 11, 50 (21) HU; Stary VI: n = 14, 96 (42) HU; Stary VII: n = 6, 858 (263) HU; Stary VIII: n = 18, 126 (99) HU). The concordance index kappa for the classification of plaques based on density was 0.51. Vessel dimensions had a good correlation (r = 0.98). CONCLUSIONS: 16 slice CT was found to be a reliable non-invasive imaging technique for assessing atherosclerotic plaque morphology and composition. Although calcified lesions can be differentiated from non-calcified lesions, the diagnostic accuracy in further subclassifying non-calcified plaques as lipid rich and fibrotic is low, even under experimental conditions.

Assessment of peripheral arterial occlusive disease: comparison of multislice-CT angiography (MS-CTA) and intraarterial digital subtraction angiography (IA-DSA).

PURPOSE: The aim of the study was to assess the arterial vascular system of the lower extremities in patients with peripheral arterial occlusive disease using Multislice-CT angiography (MS-CTA) and to compare the results with the standard of reference, intraarterial digital subtraction angiography (IA-DSA). MATERIALS AND METHODS: MS-CTA and IA-DSA of the lower extremities were carried out on 23 patients with peripheral arterial occlusive disease (Fontain Stage IIb: 18, III: 3, IV: 2). MS-CTA comprised a 4 x 2.5 mm collimation, 15 mm table feed/rotation, 0.5 sec rotation time and 3 mm slice thickness (1.5 mm reconstruction increment). Delay time was determined by bolus tracking. 150 ml of contrast media were injected intravenously at a flow rate of 3 ml/sec. Maximum intensity projection (MIP) reformations were performed using a semi-automatic vessel tracking program. MS-CTA (axial and MIP-reformatted images) and IA-DSA were reviewed by two radiologists. The grade of vascular stenosis as well as occlusion were rated on a scale of 0 to 3 (0=0-50% stenosis, 1 = 51-75% stenosis, 2 = 76-99% stenosis, 3 = occlusion). RESULTS: For MS-CTA, the mean delay time was 30.2 s (23-40 s), mean scan time was 37.4 (33-42 s). Data analysis was based upon a total of 1136 vascular segments for both methods (568 each). A comparison of all the evaluated segments in both techniques revealed a MS-CTA / IA-DSA 86.3% match. Out of 442 segments proximal the trifurcation, 386 were correctly assessed in MS-CTA (87.3%) and distal the trifurcation, 101 out of 126 segments were rated correctly (80.2%). In MS-CTA, an overall confidence interval of 95% can be achieved in 83.2% to 89.0% for correctly rated stenosis grading. CONCLUSIONS: In patients with peripheral arterial occlusive disease, MS-CTA of the lower extremity is a promising minimal-invasive method for detection of relevant arterial stenoses. However, the technique was limited to routine diagnostic purposes due to severe calcifications and time consuming reconstruction procedures.

Non-invasive coronary angiography with high resolution multidetector-row computed tomography. Results in 102 patients.

AIMS: A new generation of multidetector-row CT (MDCT) scanners allows complete coronary coverage using retrospective ECG gating and 1mm slices. The purpose of this study was to investigate the potential of high resolution MDCT angiography with retrospective gating for detection of coronary artery stenoses. METHODS AND RESULTS: A total of 102 patients underwent both conventional and MDCT coronary angiography. After intravenous injection of a non-ionic contrast medium the entire heart was scanned within a single breath hold using 1mm slices. All MDCT data sets were reconstructed with retrospective gating at 20% to 80% in increments of 10% relative to the cardiac cycle. Two blinded independent reviewers analysed image quality for segments 1-4 (right coronary artery), 5-8 (left main, left anterior descending), and 11, 12 (left circumflex). These segments were evaluated for the presence or absence of significant (>or=50%) stenoses. The results were compared with those of invasive coronary angiography in a blinded fashion. Overall sensitivity for the detection of significant stenoses (>or=50%) were 0.86 (reader 1) and 0.93 (reader 2), specificity 0.96 (reader 1) and 0.97 (reader 2), negative predictive value 0.98 (reader 1) and 0.99 (reader 2). CONCLUSIONS: High resolution MDCT angiography with retrospective gating permits the non-invasive detection of coronary artery stenoses with high accuracy if image quality is optimized for each of the three major coronary arteries.

Virtual coronary angioscopy using multislice computed tomography.

BACKGROUND: With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualisation of human coronary arteries with diagnostic image quality. In addition to conventional axial slices, virtual coronary angioscopies (VCA) can be reconstructed using MSCT datasets. OBJECTIVE: To evaluate the feasibility of reconstructing VCA and to determine the clinical value of this new application in detecting atherosclerotic coronary artery lesions. METHODS: Datasets obtained by contrast enhanced non-invasive coronary angiography using MSCT (Somatom VZ) were analysed from 14 consecutive patients. VCA were simulated in 14 coronary arteries (left anterior descending, n = 7; right coronary, n = 7). Lesion detection was undertaken on conventional contrast enhanced axial slices, as well as by VCA. Intracoronary ultrasound (ICUS) was used as the gold standard for in vivo plaque detection. RESULTS: 38 lesions were detected both on ICUS and on axial slices: 14 severe target lesions of > 75% area stenosis (11 calcified, three non-calcified), and 24 intermediate lesions of < or = 75% area stenosis (seven calcified, 17 non-calcified). Using VCA, all severe lesions (n = 14) and all calcified intermediate plaques (n = 7) could clearly be identified. However, non-calcified intermediate lesions (n = 17) could not be accurately distinguished from the vessel wall; they were recognised as vessel wall alterations without significant luminal narrowing. CONCLUSIONS: Current MSCT technology allows reconstruction of VCA with good image quality. Despite a more anatomical view of heart and coronary vessels on three dimensional reconstruction, conventional axial slices were found to be superior for detecting coronary lesions. Thus further technical innovations are required before VCA can become a useful technique in clinical cardiology.

Coronary arteries: retrospectively ECG-gated multi-detector row CT angiography with selective optimization of the image reconstruction window.

PURPOSE: To investigate how the technique of retrospective gating can be used to optimize reconstruction of multi-detector row computed tomographic (CT) images for each of the three major coronary arteries during the cardiac cycle. MATERIALS AND METHODS: Multi-detector row coronary CT angiograms obtained in 50 patients were reconstructed at 20%-80% of the cardiac cycle in increments of 10%. Two blinded independent reviewers assessed the image quality, in terms of artifacts and visibility, obtained with three-dimensional postprocessing for segments 1-3 (right coronary artery), segments 5-8 (left main and left anterior descending coronary arteries), and segments 11 and 12 (left circumflex artery). The following grades were assigned: 1, very poor; 2, poor; 3, fair; 4, good; and 5, excellent. RESULTS: The left anterior descending artery was best visualized in middiastole at 60%-70% of the cardiac cycle, and the left circumflex artery was best visualized at 50%. The optimal reconstruction window for the right coronary artery was significantly different at 40% (P < .05). Although there was good agreement (kappa = 0.75) between the two reviewers, there was a high degree of variation in the patient population. CONCLUSION: The image reconstruction window for CT angiography of the coronary arteries should be adapted to each coronary artery. The use of one fixed time point in the cardiac cycle for image reconstruction does not provide optimal image quality.

Accuracy of density measurements within plaques located in artificial coronary arteries by X-ray multislice CT: results of a phantom study.

PURPOSE: Clinical studies indicate that coronary plaque morphology might be differentiated noninvasively using multislice CT by determining tissue density within the lesions. The aim of the present experimental study was to evaluate factors that influence density measurements within small vessels. METHOD: A coronary phantom model was developed, consisting of silicon tubes (lumen diameter 4 mm) with two plaques of known density inside, simulating soft and intermediate lesions (Plaque 1: -39 HU; Plaque 2: 72 HU). Density measurement were conducted in three different contrast medium concentrations (1:30, 1:40, 1:50) and two different slice widths (4 x 2.5 mm, 4 x 1 mm). All scans were performed on a Somatom Volume Zoom (Siemens, Forchheim, Germany). Experimental results were compared with calculated data based on computer simulation. RESULTS: The two plaques could be clearly differentiated from each other on both collimations (4 x 2.5 mm: Plaque 1, 85 +/- 61 HU vs. Plaque 2, 119 +/- 26 HU, p < 0.0001; 4 x 1 mm: Plaque 1, 50 +/- 54 HU vs. Plaque 2, 91 +/- 17 HU, p < 0.0001). Significantly lower and more accurate results were achieved with 1.0 mm collimation (p < 0.0001). Contrast medium concentration contributed significantly to the measurements (p < 0.001). The experimental findings were confirmed by computer simulation, which revealed even more accurate results when using a 0.5 mm collimation (Plaque 1, 0.5 mm: -9 HU vs. 4 x 1 mm: 14 HU, Plaque 2, 4 x 0.5 mm: 83 HU vs. 4 x 1 mm: 93 HU). CONCLUSION: Density measurements were found to be highly dependent on slice width and surrounding contrast enhancement. Our results indicate that standardization of methodology is required before the noninvasive differentiation of human plaque morphology by multislice CT can be applied in the clinical setting as a screening test for coronary soft plaques.

Non-invasive characterisation of coronary lesion morphology and composition by multislice CT: first results in comparison with intracoronary ultrasound.

The reliable non-invasive detection of coronary artery disease (CAD) is a prime goal for future developments in clinical cardiology. In addition to the documentation of high-grade stenoses, the detection of vulnerable plaques is of major importance for risk stratification and early treatment to prevent plaque rupture. Recently, a new generation of fast spiral CT has been introduced using a multi-slice technique (MSCT), which is the first real quantum leap in CT since the introduction of spiral CT in the early 1990s. We report on non-invasive differentiation of coronary plaque morphology by MSCT in patients with lesions in the proximal left anterior descending artery (LAD). The results were compared with the findings of intracoronary ultrasound (ICUS). The ICUS and MSCT scans were analysed in 6 patients scheduled for ICUS-guided PTCA. One target lesion was selected in each patient. On ICUS, two lesions were classified as soft, two as intermediate and two as calcified according to established criteria based on echogenicity. By multislice CT, density measurements (expressed in Hounsfield Units, HU) were performed at 16 randomly selected areas within the plaques. The two soft plaques showed a mean density of 6+/-28 and -5+/-25 HU, the two intermediate plaques of 83+/-17 and 51+/-19 HU, and the two calcified plaques of 489+/-372 and 423+/-111 HU. To our knowledge, this is the first report on non-invasive characterisation of coronary lesions by MSCT. Plaque composition could be clearly differentiated and classified according to the ICUS results by determining tissue density within the lesions. Thus, this new technology holds promise for non-invasive risk assessment in patients with known or suspected CAD since also rupture-prone soft coronary lesions can be detected by use of this new technique.

Noninvasive detection of coronary lesions by multislice computed tomography: results of the New Age pilot trial.

The reliable noninvasive assessment of coronary artery disease would constitute an important step forward in clinical cardiology. The aim of the New Age pilot trial was to evaluate the diagnostic accuracy of multislice computed tomography (MSCT) in determining coronary lesions. As a gold standard for in vivo plaque detection, intracoronary ultrasound (ICUS) was used. Forty plaques were detected by ICUS in 15 target vessels (LAD, n = 8; RCA, n = 7) in patients assigned for ICUS-guided PTCA. Preinterventional MSCT was performed in all patients and the results were compared to ICUS with regard to lesion detection and quantification. According to ICUS results, the 40 plaques were divided into three groups: group I, mild lesions < 50% (n = 14; 44.36% +/- 5.77%); group II, intermediate lesions 50%-75% (n = 12; 59.18% +/- 9.39%); and group III, severe lesions > 75% (n = 14; 91.47% +/- 3.68%). All MSCT scans showed sufficient image quality for analysis. Thirty of 40 (75%) plaques were detected by MSCT in a first blinded session. After unblinding the ICUS results, the remaining 10 (25%) plaques could be identified. Lesion severity was classified correctly in 34 of 40 (85%) plaques. Plaque calcifications were diagnosed correctly in 16 of 19 (84.2%) plaques. Quantification of vessel size revealed a good correlation to the ICUS results (r(2) 0.68; P = 0.004). Noninvasive MSCT angiography showed good diagnostic accuracy with regard to lesion detection and quantification of vessel size. The overall good image quality, makes this new technology a promising modality, which might become an alternative diagnostic approach in patients with known or suspected coronary artery disease. Cathet Cardiovasc Intervent 2001;53:352-358.

Accuracy and reliability of quantitative measurements in coronary arteries by multi-slice computed tomography: experimental and initial clinical results.

AIM: To evaluate the accuracy of non-invasive measurements within coronary arteries by multi-slice computed tomography (MSCT). We present experimental as well as clinical data. MATERIALS AND METHODS: Silicon tubes simulating coronary arteries (outer diameter 6 mm, lumen diameter within stenotic area 2 mm) were used for experimental studies. Clinical data were derived from 15 patients in whom vessel diameters were assessed by MSCT, intracoronary ultrasound (ICUS) and quantitative coronary angiography (QCA). MSCT were performed in a Somatom Volume Zoom(trade mark)CT system (Siemens, Forchheim, Germany) at 2 collimated slice widths (2.5 mm, 1.0 mm). RESULTS: Outer silicon tube diameters were overestimated by MSCT (6.56 mm +/- 0.32 mm). All measurements revealed significantly better results on 1.0 collimation compared to 2.5 mm collimation (outer diameter: 6.36 mm +/- 0.22 mm vs 6.76 mm +/- 0.27 mm, P < 0.0001; lumen diameters: 1.83 mm +/- 0.14 mm vs 1.51 mm +/- 0.19 mm, P < 0.0001). The comparison of vessel diameters within human coronary arteries revealed comparable results between ICUS and MSCT (4.89 mm +/- 0.67 mm vs 4.91 mm +/- 0.71 mm, P = 0.79, r = 0.79, P < 0.0001). QCA-measurements showed significantly lower results (3.67 +/- 0.71, P < 0.0001, r = 0.62, P < 0.001). CONCLUSIONS: Experimental as well as initial clinical results indicate acceptable reliability and accuracy of quantitative measurements by MSCT, when using thin collimated slice widths. Partial volume effects lead to a systematic overestimation of vessel size. MSCT has the potential to become an important non-invasive diagnostic tool in patients with coronary artery disease.

Self-rated health and clinical status after PTCA: results of a 4-year follow-up in 500 patients.

Background: Data on the clinical long-term outcome of patients with coronary artery disease in the years following percutaneous interventions are rare. We therefore decided to conduct a study to: (1) analyze the efficiency of a retrospective inquiry using a questionnaire and (2) perform a clinical long-term follow-up of our patients. Methods and results: Some 45+/-7 months after PTCA, a questionnaire was sent to 549 patients who had been treated at our institution from July 1, 1989, to June 30, 1991. The response rate was 91.1%, with 49 patients (8.9%) lost to follow-up. A total of 115/500 patients (23%) had reinterventions due to severe angina (69 patients (13.8%) undergoing re-PTCA and 46 (9.2%) CABG). Sixteen patients (3.2%) had a myocardial infarction and 35 patients (7.0%) died. Multivariate analysis revealed that patients who were asymptomatic 3 months after PTCA were likely to have a good long-term outcome. This was not found when comparing the clinical status immediately after PTCA to follow-up. Medical therapy with beta-blockers/aspirin/lipid-lowering drugs decreased from 75.2/82.2/35.4% at hospital discharge to 54.6/76.7/25.2% at follow-up. Conclusions: The present study provided important quality data for our institution. The response rate to the questionnaire was surprisingly high (91.1%), indicating that retrospective inquiries may also be efficient. The rate of reinterventions during long-term follow-up (23%) was acceptably low. Good self-rated health 3 months after the intervention turned out to be a strong predictor for a good clinical long-term outcome. Furthermore, we observed an underuse of cardiac medication, something that will be the subject of further quality improvement measures.