Noninvasive visualization of coronary arteries using contrast-enhanced multidetector CT: influence of heart rate on image quality and stenosis detection

Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients

To evaluate image quality in the assessment of the coronary arteries during routine ECG-gated multidetector CT (MDCT) of the chest. One hundred and thirty three patients in sinus rhythm underwent an ECG-gated CT angiographic examination of the entire chest without beta-blockers with a 64-slice CT system. In 127 patients (95%), it was possible to assess the coronary arteries partially or totally; coronary artery imaging failed in six patients (5%), leading to a detailed description of the coronary arteries in 127 patients. Considering ten coronary artery segments per patient, 75% of coronary segments were assessable (948/1270 segments). When the distal segments were excluded from the analysis (i.e., seven coronary segments evaluated per patient), the percentage of assessable segments was 86% (768/889 proximal and mid coronary segments) and reached 93% (474/508) when assessing proximal segments exclusively. The mean number of assessable segments was significantly higher in patients with a heart rate < or =80 bpm (n=95) than in patients with a heart rate >80 bpm (n=38) (p<0.002). Proximal and mid-coronary segments can be adequately assessed during a whole-chest ECG-gated CT angiographic examination without administration of beta-blockers in patients with a heart rate below 80 bpm.

Coronary CT angiography with 64-MDCT: assessment of vessel visibility

OBJECTIVE

The objective of our study was to evaluate the image quality of 64-MDCT for coronary angiography.

SUBJECTS AND METHODS

Fifty consecutive CT coronary angiograms obtained on a 64-MDCT scanner were independently reviewed by two reviewers. Segments were scored as showing no motion (score of 1), minimal motion (2), moderate motion (3), respiratory motion (4), or vessel blurring (5). Opacification was graded as good (score of 1) or limited (2). Segments < 2 mm were graded as well seen; or as poorly seen or not seen. The scores for motion artifact, opacification, and visibility were combined for overall vessel assessment. Segments with a motion score of 1 or 2 that had good opacification and were well seen were judged to be assessable.

RESULTS

A total of 714 segments were analyzed in 50 patients. Seven hundred segments were assessed in all patients (segments 1-3, 11-20, 4, or 27), and a ramus intermedius segment was evaluated in 14 patients. Combining the scores for both reviewers, the average motion score was 1 for 619 segments (86.7%), the average motion score for all segments in an individual patient was 1.14 (range, 1-3.35), and the average opacification score for all segments in a patient was 1.02 (range, 1-1.38). A total of 374 segments were less than 2 mm in diameter. Combining the scores for both reviewers, an average of 36 segments (5.0% of 714) could not be identified by the reviewers, 319.5 segments (85.4%) were well seen, and 18.5 segments (4.9%) were poorly seen. Overall, an average of 637 segments (89.2%) were judged assessable by the reviewers. On a per-patient basis, 10 or more vessel segments were judged assessable in 47 patients (94%).

CONCLUSION

On 64-MDCT, 89% of coronary artery segments are assessable. Ten or more vessel segments are assessable in 94% of patients.

Diagnostic value of multislice computed tomography angiography in coronary artery disease: a meta-analysis

PURPOSE

To perform a meta-analysis of the diagnostic value of multislice CT (MSCT) angiography in the detection of coronary artery disease (CAD) when compared to conventional coronary angiography.

MATERIALS AND METHODS

A search of PubMed and MEDLINE databases for English literature was performed. Only studies with at least 10 patients comparing MSCT angiography with conventional coronary angiography in the detection of CAD were included. Diagnostic value of MSCT angiography compared to coronary angiography was compared and analyzed at segment-, vessel- and patient-based assessment.

RESULTS

47 studies (67 comparisons) met the criteria and were included in our study. Pooled overall sensitivity, specificity and 95% confidence interval for MSCT angiography in the detection of CAD were 83% (79%, 89%), 93% (91%, 96%) at segment-based analysis; 90% (87%, 94%), 87% (80%, 93%) at vessel-based analysis; and 91% (88%, 95%), 86% (81%, 92%) at patient-based analysis, respectively. Diagnostic accuracy of MSCT angiography in evaluating assessable segments was significantly improved with 64-slice scanners when compared to that with 4- and 16-slice scanners (p<0.05).

CONCLUSION

Our meta-analysis showed that MSCT angiography has potential diagnostic accuracy in the detection of CAD. Diagnostic performance of MSCT angiography has been significantly improved with the latest 64-slice CT, with resultant high qualitative and quantitative diagnostic accuracy. 16-slice CT was limited in spatial resolution which makes it difficult to perform quantitative assessment of coronary artery stenoses.

Detection of transplant coronary artery disease using multidetector computed tomography with adaptative multisegment reconstruction

OBJECTIVES

This study sought to determine whether multidetector computed tomography (MDCT) may be able to detect occlusive coronary disease in transplanted hearts.

BACKGROUND

In heart transplant recipients, asymptomatic coronary disease requiring frequent surveillance commonly develops. Recent advancements in MDCT allow for noninvasive assessment of the coronary vessels.

METHODS

Electrocardiogram-gated contrast-enhanced MDCT scans (16 x 0.75-mm detectors, 420 ms rotation, 100 ml contrast) with multisegment reconstruction were performed on 54 transplant recipients within 6 +/- 11 days of quantitative coronary angiography (QCA). Heart rate at the time of the scan was 90 +/- 11 beats/min. Coronary arterial segments >1.5 mm in diameter were analyzed by independent investigators.

RESULTS

There was a good correlation between MDCT and QCA percent stenosis (r = 0.75, p < 0.01, SEE = 15%). Of the 791 segments identified by QCA, 754 (95%) were analyzable by MDCT. The sensitivity, specificity, and positive and negative predictive values of MDCT compared with QCA for the detection of segments with significant (>50%) stenosis were 86%, 99%, 81%, and 99%, respectively. The MDCT correctly identified 15 of the 16 (94%) transplant patients classified by QCA as having occlusive coronary artery disease and 29 of the 37 patients without significant stenosis (78%). In 1 patient who received intravenous beta-blockers, transient bradycardia requiring temporary pacing developed, but there were no other complications.

CONCLUSIONS

Detection of occlusive coronary disease in heart transplant recipients with elevated resting heart rate by MDCT is feasible using multicycle reconstruction. The need for surveillance invasive coronary angiography in transplant recipients might be mitigated by use of MDCT.

Beta-blockers for cardiac CT: a primer for the radiologist

OBJECTIVE

The objective of this article is to describe a protocol for the administration of beta-blockers for cardiac CT. A low and regular heart rate is necessary for optimal visualization of the coronary arteries on CT and can be achieved by the administration of medications.

CONCLUSION

Beta-blockers can be safely given, orally or IV, to most patients to lower the heart rate for cardiac CT. A protocol can be implemented and patients can be screened for certain contraindications to allow successful administration of these medications by radiologists.

Computed tomographic coronary angiography: how many slices do you need?

While increasing the number of slices in multislice computed tomography clearly brings benefits in terms of detecting significant coronary disease, heavy calcification remains a problem, as does the high radiation burden.

Accuracy of 64-row multidetector computed tomography in detecting coronary artery disease in 134 symptomatic patients: influence of calcification

BACKGROUND

The new 64-row multidetector computed tomography (CT)-assisted angiography can now detect coronary artery disease with shorter breath-hold time and at faster heart rates for symptomatic patients. We aim to determine if the 64-row scanner can also overcome limitations due to mild to moderate calcification.

METHODS

Scheduled for conventional coronary angiography, 134 symptomatic patients underwent multidetector CT-assisted angiography within 3 months. Patients were divided into those with low or high calcium score (median score 142) by modified Agatston formula: group A calcium score <142 Agatston score (68 patients, mean age 53 years, heart rate 62 beat/min) and group B calcium score > or = 142 Agatston score (66 patients, mean age 57 years, heart rate 62 beat/min). Eleven major coronary segments were evaluated.

RESULTS

In group A, 93.6% of segments were evaluable with 97.3% correlation. Segment-by-segment analyses for sensitivity, specificity, and positive and negative predictive values were 85.4%, 98.1%, 76.7%, and 99.2%, respectively. For group B, 86.9% of segments were evaluable with 90.5% correlation. Sensitivity, specificity, and positive and negative predictive values were 79.9%, 92.8%, 78.8%, and 93.5%, respectively.

CONCLUSIONS

The 64-slice multidetector CT coronary angiography can reliably detect the presence of significant coronary stenosis in symptomatic patients with mild calcification, but remains limited by moderate to heavy calcification.

The clinical value of a negative multi-detector computed tomographic angiography in patients suspected of coronary artery disease: A meta-analysis

The aim of this meta-analysis was to calculate the sensitivity of contrast-enhanced multi-detector computed tomography (MDCT) compared with coronary angiography (CAG) in incident patients suspected of coronary artery disease (CAD). We searched PubMed, Embase, bibliographies of original papers and reviews to identify original papers including > or =20 patients. Two independent reviewers selected papers and judged eligible papers on quality. Heterogeneity was assessed and homogeneous subgroups were pooled. Of the 15 included studies, ten provided moderately homogeneous patient-based analyses with absolute diagnostic numbers (n = 630 patients). Pooled sensitivity was 89% (95% confidence interval: 85-92%). Scanners with 16 detectors (n = 4) had higher sensitivities (pooled sensitivity: 91%) than four-detector scanners (n = 6; pooling not possible due to heterogeneity). Seven studies reported sensitivity for a proximal stenosis, but different definitions were used making pooling impossible; sensitivities ranged from 75 to 100%. The sensitivity of four- and 16-detector MDCT is not sufficient to rule out any stenosis in patients suspected of CAD. No conclusions can be drawn with respect to the sensitivity for clinically relevant or proximal stenoses.

Does 16-MDCT angiography scanning direction affect image quality of coronary artery bypass grafts and the native coronary arteries?

To assess the impact of scanning direction on the image quality of coronary artery bypass grafts (CABGs), native coronary arteries (NCAs) were examined by electrocardiographically (ECG) gated 16-row multidetector computed tomography (16-MDCT). Eighty-two patients with 209 grafts were studied by 16-MDCT. Forty-one patients with 111 grafts were scanned craniocaudally. Forty-one patients with 98 grafts were scanned caudocranially. CABG, native coronary arteries were examined in four (proximal, middle, distal, distal anastomoses), three (proximal, middle, distal) segments, respectively. Subjective image quality on a four-point scale was calculated for segments. Scores of groups were compared. Results Image quality scores of proximal, distal segments of the right coronary artery (RCA) were better in caudocranially scanned group (P<0.05). When we subgrouped patients according to initial heart rates (IHR) (group 1, <65 beats/min; group 2, > or =65 beats/min), there was no statistical significance between image quality scores of coronary arteries, CABG when IHR was <65 beats/min in groups regardless of scanning direction. Scores of anastomotic segment of CABG to RCA, middle segments of circumflex coronary artery, proximal and distal segments of RCA in caudocranially scanned group were better when the IHR is > or =65 beats/min compared with the craniocaudally scanned group. When the IHR of the patient is > or =65 beats/min, performing ECG-gated 16-MDCT angiography in the caudocranial direction provides better image quality for evaluation of coronary arteries and CABGs.

Optimal image reconstruction intervals for non-invasive coronary angiography with 64-slice CT

The reconstruction intervals providing best image quality for non-invasive coronary angiography with 64-slice computed tomography (CT) were evaluated. Contrast-enhanced, retrospectively electrocardiography (ECG)-gated 64-slice CT coronary angiography was performed in 80 patients (47 male, 33 female; mean age 62.1+/-10.6 years). Thirteen data sets were reconstructed in 5% increments from 20 to 80% of the R-R interval. Depending on the average heart rate during scanning, patients were grouped as < 65 bpm (n = 49) and > or = 65 bpm (n = 31). Two blinded and independent readers assessed the image quality of each coronary segment with a diameter > or = 1.5 mm using the following scores: 1, no motion artifacts; 2, minor artifacts; 3, moderate artifacts; 4, severe artifacts; and 5, not evaluative. The average heart rate was 63.3 +/- 13.1 bpm (range 38-102). Acceptable image quality (scores 1-3) was achieved in 99.1% of all coronary segments (1,162/1,172; mean image quality score 1.55 +/- 0.77) in the best reconstruction interval. Best image quality was found at 60% and 65% of the R-R interval for all patients and for each heart rate subgroup, whereas motion artifacts occurred significantly more often (P < 0.01) at other reconstruction intervals. At heart rates < 65 bpm, acceptable image quality was found in all coronary segments at 60%. At heart rates > or = 65 bpm, the whole coronary artery tree could be visualized with acceptable image quality in 87% (27/31) of the patients at 60%, while ten segments in four patients were rated as non-diagnostic (scores 4-5) at any reconstruction interval. In conclusion, 64-slice CT coronary angiography provides best overall image quality in mid-diastole. At heart rates < 65 bpm, diagnostic image quality of all coronary segments can be obtained at a single reconstruction interval of 60%.

Image Quality, Motion Artifacts, and Reconstruction Timing of 64-Slice Coronary Computed Tomography Angiography With 0.33-Second Rotation Speed

OBJECTIVES

We sought to evaluate the impact of patients' heart rate (HR) on coronary CTA image quality (IQ) and motion artifacts using a 64-slice scanner with 0.33/360 degrees rotation.

MATERIALS AND METHODS

Coronary CTA data sets of 32 patients (HR <or= 65 beats per minute [bpm], n = 15; HR > 65 bpm to <or=75 bpm, n = 10; HR > 75 bpm, n = 7) examined on a 64-slice scanner (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) with 0.33s/360 degrees gantry rotation speed were analyzed. All patients had suspicion of coronary artery disease. Data acquisition was performed using 64 x 0.6-mm collimation, and contrast enhancement was provided by injection of 80 mL of iopromide (5 mL/s + NaCl). Images were reconstructed throughout the RR interval using half-scan and dual-segment reconstruction. IQ was rated by 2 observers using a 3-point scale from excellent (1) to nondiagnostic (3) for coronary segments. Quality was correlated to the HR, time point of optimal IQ analyzed, and the benefit of dual-segment reconstruction evaluated.

RESULTS

Overall mean IQ was 1.31 +/- 0.32 for all HR, with IQ being 1.08 +/- 0.12 for HR <or= 65 bpm, 1.62 +/- 0.27 for HR > 65 bpm <or= 75 bpm and 1.36 +/- 0.31 for HR > 75 bpm (P = 0.0003). Dual-segment reconstruction did not significantly improve IQ in any HR group (P = NS). Mean IQ was significantly better for LAD than for RCA (P < 0.0001) and LCX (P < 0.01). A total of 3.5% (11/318) of coronary artery segments were rated nondiagnostic by at least one reader based on motion artifacts. Although in HR < 65 bpm, the best IQ was predominately in diastole (93%), in HR > 75 bpm, the best IQ shifted to systole in most cases (86%).

CONCLUSIONS

Temporal resolution at 0.33-second rotation allows for diagnostic IQ within a wide range of HR using half-scan reconstruction. With increasing HR the time point of best IQ shifts from mid-diastole to systole.

Eight-Row Multidetector Computed Tomography Coronary Angiography Evaluation of Significant Coronary Artery Disease in Patients with Severe Aortic Valve Stenosis

BACKGROUND

The aim of this study was to evaluate whether 8-row multidetector computed tomography coronary angiography (MDCT-CA) could replace invasive conventional coronary angiography (CCA) in patients with acquired severe aortic valve stenosis (AS). Coronary artery disease (CAD) diagnosis should be obtained with a noninvasive method in patients with AS undergoing valvular replacement. We evaluated the diagnostic accuracy of MDCT-CA in detecting high-grade (> or =50%) stenoses in the main coronary arteries in patients with AS.

METHODS

Twenty-three patients with acquired severe AS underwent both CCA and MDCT-CA. We calculated the total and volumetric calcium scores and evaluated the image quality of each coronary segment as assessable or nonassessable for stenosis. The images of the arteries were evaluated for the occurrence of artifacts and the presence of high-grade stenoses (> or =50%) by visual estimation and comparison with that of CCA.

RESULTS

Of the 322 segments screened 224 were assessable for stenosis. Heavy calcium load rendered 37 (38%) of the 98 coronary segments nonassessable. Compared to CCA, MDCT-CA had a sensitivity of 63%, a specificity of 96%, a positive predictive value of 52%, and a negative predictive value of 98% for > or =50% stenoses in the main coronary arteries.

CONCLUSIONS

Eight-row MDCT-CA revealed a low sensitivity in detecting significant coronary artery disease in patients with acquired severe AS. High calcium burden decreased visualization of the lumen and complicated most often a correct assessment. In this patient group, CCA should still remain the primary pre-surgical test to rule out coronary lesions requiring revascularization.

A model for temporal resolution of multidetector computed tomography of coronary arteries in relation to rotation time, heart rate and reconstruction algorithm

A model is presented that describes the image quality of coronary arteries with multidetector computer tomography. The results are discussed in the context of rotation time of the scanner, heart rate, and number of sectors used in the acquisition process. The blurring of the coronary arteries was calculated for heart rates between 50 and 100 bpm for rotation times of 420, 370, and 330 ms, and one-, two-, three-, and four-sector acquisition modes and irregular coronary artery movement is included. The model predicts optimal timing within the RR cycle of 45+/-3% (RCA), 44+/-4% and 74+/-6% (LCX), and 35+/-4% and 76+/-5% (LAD). The optimal timing shows a negative linear dependency on heart rate and increases with the number of sectors used. The RCA blurring decreases from 0.98 cm for 420 ms, one-sector mode to 0.27 cm for 330 ms, four-sector mode. The corresponding values are 0.81 cm and 0.29 cm for LCX and 0.42 cm and 0.17 cm for LAD. The number of sectors used in a multisector reconstruction and the timing within the cardiac cycle should be adjusted to the specific coronary artery that has to be imaged. Irregular coronary artery movement of 1.5 mm justifies the statement that no more than two sectors should be used in multisector acquisition processes in order to improve temporal resolution in cardiac MDCT.

Atherosclerotic Plaque Characterization by Multidetector Row Computed Tomography Angiography

Multidetector row computed tomography angiography (MDCTA) is seen as a potential alternative to current imaging methods for the assessment of vessel anatomy and atherosclerotic plaque composition/morphology in a great variety of arterial beds. Recent advances represented by the increase in gantry speed to <500 ms per rotation and in the number of detector rows from 4 to 64, in addition to the decrease in slice thickness to submillimetric levels, brought significant improvement in diagnostic accuracy by coronary MDCTA. In general, it has a good correlation with both intravascular ultrasound (IVUS) and histopathology for discrimination between soft, intermediate, and calcified plaques. Plaque area and volume tend to be underestimated by 12-detector row MDCTA and overestimated by 16-detector row MDCTA, but the number of patients studied so far is relatively small. However, it seems that 64-detector row MDCTA can measure plaque area and volume with greater accuracy. Plaque remodeling is overestimated in small vessels by 12-detector row MDCTA, whereas 16- and 64-detector row MDCTA show a good correlation with IVUS. Although still under development, the potential of MDCTA to characterize atherosclerotic plaque composition as well as to precisely determine plaque area, volume, and remodeling in the future is quite promising.

Initial experience with 64-slice cardiac CT: non-invasive visualization of coronary artery bypass grafts

AIMS

The aim of this study was to evaluate the diagnostic accuracy in the assessment of coronary artery bypass grafts using 64-slice computed tomography (CT) technology.

METHODS AND RESULTS

CT coronary angiography was performed for 96 bypasses in 31 patients with suspected coronary artery disease using a Siemens Sensation 64-slice CT-scanner and compared with invasive coronary angiography (ICA). Patients with an irregular or fast heart rate despite beta-blocker administration were not excluded from the study. All bypass grafts and 94% of the distal bypass anastomoses could be visualized by CT, non-evaluable distal arterial anastomoses were either due to clip material or calcification artefacts. Forty-two bypass graft occlusions and three significant stenoses were detected by CT and confirmed by ICA. Two venous grafts were missed and one arterial graft was not evaluable with ICA, but both were clearly depicted by multi-slice CT. One false negative and two false positive CT-findings resulted in a sensitivity of 97.8%, a specificity of 89.3%, a positive predictive value of 90%, and a negative predictive value of 97.7%.

CONCLUSION

State-of-the-art 64-slice CT coronary angiography demonstrates high diagnostic accuracy in the assessment of arterial and venous bypass graft stenoses.

Contrast-enhanced coronary artery visualization by dual-source computed tomography—Initial experience

Multi-detector computed tomography (CT) scanners, by virtue of their high temporal and spatial resolution, permit imaging of the coronary arteries. However, motion artifacts, especially in patients with higher heart rates, can impair image quality. We thus evaluated the performance of a new dual-source CT (DSCT) with a heart rate independent temporal resolution of 83 ms for the visualization of the coronary arteries in 14 consecutive patients.

METHODS

Fourteen patients (mean age 61 years, mean heart rate 71 min(-1)) were studied by DSCT. The system combines two arrays of an X-ray tube plus detector (64 slices) mounted on a single gantry at an angle of 90 degrees With a rotation speed of 330 ms, a temporal resolution of 83 ms (one-quarter rotation) can be achieved independent of heart rate. For data acquisition, intraveous contrast agent was injected at a rate of 5 ml/s. Images were reconstructed with 0.75 slice thickness and 0.5 mm increment. The data sets were evaluated concerning visibility of the coronary arteries and occurrence of motion artifact.

RESULTS

Visualization of the coronary arteries was successful in all patients. Most frequently, image reconstruction at 70% of the cardiac cycle provided for optimal image quality (50% of patients). Of a total of 226 coronary artery segments, 222 (98%) were visualized free of motion artifact. In summary, DSCT constitutes a promising new concept for cardiac CT. High and heart rate independent temporal resolution permits imaging of the coronary arteries without motion artifacts in a substantially increased number of patients as compared to earlier scanner generations. Larger and appropriately designed studies will need to determine the method's accuracy for detection of coronary artery stenoses.

Detection of coronary complications after the arterial switch operation for transposition of the great arteries: First experience with multislice computed tomography in children

OBJECTIVE

The main cause of long-term morbidity and mortality after a successful arterial switch operation for transposition of the great arteries is complications at the ostial segments, proximal segments, or both of the retransferred coronary arteries. The purpose of this study was to investigate the clinical usefulness of multislice computed tomographic angiography in detecting ostial and proximal coronary lesions in children having undergone the arterial switch operation for transposition of the great arteries.

METHODS

Forty-nine children (aged 8.5 +/- 3.9 years) operated on for transposition of the great arteries with the arterial switch operation (follow-up, 8.3 +/- 3.6 years) underwent systematic selective conventional and multislice computed tomographic angiography. The ability of multislice computed tomography in detecting stenosis and other modifications of the coronary arteries' course was analyzed by 2 independent investigators.

RESULTS

Multislice computed tomography, as compared with selective conventional coronary angiography, permitted assessment of ostial and proximal coronary segments in every patient. It correctly detected the 4 (8.1%) patients with significant coronary lesions (1 with ostial and 3 with proximal coronary stenosis) that had been identified by means of conventional angiography. Multislice computed tomography clearly showed an abnormal course of the coronary artery between the great arteries with compression of the ostial (1 patient) and proximal (3 patients) segments of the retransferred coronary arteries.

CONCLUSION

These results indicate that multislice computed tomographic angiography is fully accurate in detecting ostial coronary artery stenoses, proximal coronary artery stenoses, or both in pediatric patients having undergone the arterial switch operation for transposition of the great arteries. Our results suggest that multislice computed tomography could be used as a screening technique for detecting coronary complications in the follow-up of the arterial switch operation before having recourse to conventional angiography.

Quantitative parameters of image quality in 64-slice computed tomography angiography of the coronary arteries

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rate < or = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate > 65 bpm (p < 0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.

Effect of the Reconstruction Window Obtained at the Isovolumic Relaxation Period on the Image Quality in Electrocardiographic-Gated 16-Multidetector-Row Computed Tomography Coronary Angiography Studies

OBJECTIVE

To evaluate whether images obtained during the reconstruction window responding to the isovolumic relaxation period could be used for rapid and easy postprocessing.

METHODS

One hundred ten consecutive patients with suspected coronary artery disease who had previously had a multidetector computed tomography (MDCT) scan for imaging coronary arteries were enrolled in this study. The age of the patients was 59 +/- 13 years (range: 33-78 years), and 77 (70%) were male. Multidetector computed tomography was performed on a 16-detector-row computed tomography scanner during 1 breath hold (16-24 seconds). Seven different sets of images reconstructed at every 10% of the R-R interval from 30% to 90% for contrast-enhanced scans at levels containing the first several centimeters of the left and right coronary arteries were analyzed. The best of these reconstruction windows were then compared with the images reconstructed at the isovolumic relaxation period, which is the last portion of the T wave at the end of the systole, where there is not any change in ventricular volume, which causes stepladder artifacts. The step artifact was classified as excellent, good, or poor. Image quality was assessed by 2 radiologists who were not aware of each other's interpretation.

RESULTS

According to the routinely used reconstructions, there were 76 patients with excellent image quality, 28 with good image quality, and 6 with poor image quality. For the period of isovolumic relaxation, there were 74 patients with excellent image quality, 25 with good image quality, and 11 with poor image quality.

CONCLUSION

If one begins image analysis with the isovolumic relaxation period reconstruction window, spending less time for postprocessing analyses, good image quality can be obtained such as with other good reconstruction windows.

Multidetector computed tomography for the diagnosis of coronary artery disease: a systematic review

PURPOSE

The study's purpose was to determine the sensitivity and specificity of contrast-enhanced multidetector computed tomography (CT) for the detection of coronary artery disease.

SUBJECTS AND METHODS

A search of the literature in all languages was performed incorporating both electronic and manual components. Manual reference checks of recent reviews and all original investigations supplemented the electronic searches.

RESULTS

Average sensitivity for patient-based detection of significant (>50% or > or =50%) stenosis was 61 of 64 (95%) with 4-slice CT, 276 of 292 (95%) with 16-slice CT, and 47 of 47 (100%) with 64-slice CT. Average specificity was 84% for 4-slice CT, 84% for 16-slice CT, and 100% for 64-slice CT. The sensitivity for a significant stenosis in evaluable segments was 307 of 372 (83%) with 4-slice CT, 1023 of 1160 (88%) with 16-slice CT, and 165 of 176 (94%) with 64-slice CT. Average specificity was 93% or greater with all multidetector CT. Seventy-eight percent of segments were evaluable with 4-slice CT, 91% with 16-slice CT, and 100% with 64-slice CT. Stenoses in proximal and mid-segments were shown with a higher sensitivity than distal segments. Left main stenosis was identified with high sensitivity with all multidetector CT, but sensitivity in other vessels increased with an increasing number of detectors.

CONCLUSION

Multidetector CT has the potential to be used as a screening test in appropriate patients. Contrast-enhanced 16-slice CT seems to be reasonably sensitive and specific for the detection of significant coronary artery disease but has shortcomings. Preliminary data with 64-slice CT suggest that it is more sensitive and specific.

Non-invasive coronary angiography with 16-slice spiral computed tomography: image quality in patients with high heart rates

The purpose of this study was to assess segment image quality at high heart rates using 16-slice computed tomography and differential reconstruction for major coronary vessels. According to the following protocol, 16-slice CT coronary angiography in 46 patients with a mean heart rate of 86.3+/-11.8 was reconstructed. At three transverse planes, preview series were obtained and motion artifacts evaluated in 5% increments from 0-95% within the cardiac cycle. Relying on image quality in the previews, reconstructions were performed at three z-positions for each patient. Segment image quality was assessed in terms of artifacts and visibility. The effects of heart rate and trigger delay on image quality were analyzed. Optimal image quality was achieved at 25 to 35% of the cardiac cycle for the left circumflex (CX) and right coronary artery (RCA) or 30 to 40% for the left main (LM) and left anterior descending artery (LAD). Sixteen-slice CT and differential reconstruction produced good image quality with a low percentage of motion-degraded proximal and middle segments (8.8%). Grades were 1.5 for the LM, 1.9 for the LAD, 2.0 for the CX and 2.3 for the RCA. At high heart rates, good image quality of the coronary arteries is achieved by 16-slice CT and a sophisticated reconstruction strategy at peak to late systole.

Noninvasive analysis of coronary artery disease with combination of MDCT and functional MRI

RATIONALE AND OBJECTIVES

We evaluated the diagnostic accuracy of an eight-row multidetector computed tomography coronary angiography (MDCT-CA) in detecting high-grade (>50%) stenoses in the three main coronary arteries in patients with coronary artery disease (CAD). Side branches were excluded. We correlated magnetic resonance imaging (MRI) findings of the myocardium with MDCT-CA of the coronary arteries.

MATERIALS AND METHODS

Fourteen CAD patients underwent conventional coronary angiography (CCA), MDCT-CA, and MRI. We determined the calcium burden with non-enhanced MDCT scan. Then MDCT-CA was performed after intravenous contrast injection during a single breathhold. The left ventricular (LV) MR cine imaging was assessed at rest and perfusion defects were observed during pharmacologic stress after contrast administration. Delayed contrast-enhanced MRI was performed to picture infarctions.

RESULTS

MDCT-CA had sensitivity 82%, specificity 94%, positive predictive value 79%, and negative predictive value 95% of stenoses of more than 50% in the main coronary arteries when compared with CCA. LV wall dysfunction, perfusion defects, and infarctions were detected in 50%-78% of sectors assigned to calcifications or stenoses, but also in sectors supplied by normally perfused coronary arteries.

CONCLUSIONS

CCA and MDCT-CA revealed comparable results in evaluating stenotic lesions above 50% in the main subepicardial coronary branches. There were no significant correlations between the degree of stenosis or calcification at MDCT-CA and the MR findings, but the combined information of MDCT-CA and MRI showed the variability of myocardial changes in regions perfused by significantly stenosed, calcified, and normal main coronary arteries.

Evidence for lower variability of coronary artery calcium mineral mass measurements by multi-detector computed tomography in a community-based cohort--consequences for progression studies

PURPOSE

To compare the measurement variability for coronary artery calcium (CAC) measurements using mineral mass compared with a modified Agatston score (AS) or volume score (VS) with multi-detector CT (MDCT) scanning, and to estimate the potential impact of these methods on the design of CAC progression studies.

MATERIALS AND METHODS

We studied 162 consecutive subjects (83 women, 79 men, mean age 51 +/- 11 years) from a general Caucasian community-based cohort (Framingham Heart Study) with duplicate runs of prospective electrocardiographically-triggered MDCT scanning. Each scan was independently evaluated for the presence of CAC by four experienced observers who determined a "modified" AS, VS and mineral mass.

RESULTS

Of the 162 subjects, CAC was detected in both scans in 69 (42%) and no CAC was detected in either scan in 72 (45%). Calcium scores were low in the 21/162 subjects (12%) for whom CAC was present in one but not the other scan (modified AS < 20 in 20/21 subjects, mean AS 4.6 +/- 1.9). For all three quantification algorithms, the inter- and intraobserver correlation were excellent (r > 0.96). However, the mean interscan variability was significantly different between mineral mass, modified AS, and VS (coefficient of variation 26 +/- 19%, 41 +/- 28% and 34 +/- 25%, respectively; p < 0.04), with significantly smaller mean differences in pair-wise comparisons for mineral mass compared with modified AS (p < 0.002) or with VS (p < 0.03). The amount of CAC but not heart rate was an independent predictor of interscan variability (r = -0.638, -0.614 and -0.577 for AS, VS, and mineral mass, respectively; all p < 0.0001). The decreased interscan variability of mineral mass would allow a sample size reduction of 5.5% compared with modified AS for observational studies of CAC progression and for randomized clinical trials.

CONCLUSION

There is significantly reduced interscan variability of CAC measurements with mineral mass compared with the modified AS or VS. However, the measurement variability of all quantification methods is predicted by the amount of CAC and is inversely correlated to the extent of partial volume artifacts. Moreover, the improvement of measurement reproducibility leads to a modest reduction in sample size for observational epidemiological studies or randomized clinical trials to assess the progression of CAC.

Multidetector row computed tomography: imaging congenital coronary artery anomalies in adults

The quality of the imaging of the main coronary arteries and side branches provided by multidetector row computed tomography (MDCT) may have importance when assessing congenital coronary artery anomalies. This review discusses the rationale for using MDCT for this indication and examines the advantages and disadvantages of the technique. Examples of MDCT imaging of congenital coronary artery anomalies are presented. These images provide persuasive evidence to support clinical use of MDCT cardiac imaging in the context of suspected congenital coronary artery anomalies as a first line investigation.

Multi-detector row computed tomography: imaging in acute aortic syndrome

Acute aortic syndromes (AAS) encompass a spectrum of emergencies. These include those non-traumatic disease entities of the aorta namely, penetrating atherosclerotic ulcer, intramural haematoma, dissection and aneurysm rupture. The various types of AAS cannot be reliably differentiated on clinical grounds alone. Acute thoracic aortic injury is usually included in this group even though clinical presentation is different, i.e., in the context of trauma, the imaging features are very similar. Differentiation of AAS from acute coronary syndrome (ACS) is important, however, it must be remembered that ACS may occur as a result of AAS. Now electrocardiogram (ECG)-gating technology is widely available, ECG-gated multi-detector row computed tomography (MDCT) is a powerful clinical tool in the acute emergency setting, which enables rapid and specific diagnosis of aortic pathology. ECG-gated MDCT significantly reduces motion artefact, avoids potential pitfalls in diagnosis and often provides diagnostic information about the coronary arteries. It should be used as a first-line imaging technique. This article examines the role of MDCT imaging and cardiac gating in the assessment of AAS and discusses the differentiation of this spectrum of aortic diseases with reference to the key imaging findings as obtained by experience in our institution.

Coronary vessel visualization using true 16-row multi-slice computed tomography technology

BACKGROUND

Multi-slice computed tomography (MSCT) scanners with retrospective ECG-gating permit visualization of the coronary arteries. Limited spatial and temporal resolution as well as breathing artefacts due to the scan time can cause poor distal vessel segment and side branch visualization. The latest MSCT generation with true 16-detector slices (Sensation 16), Siemens, Forchheim, Germany) provides furthermore improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality we conducted the following study.

METHODS AND MATERIAL

Sixty-two consecutive patients (33 male, 29 female, mean age 63+/-8 [47-79] years, heart rate after beta-blockade 63+/-7 [45-86] bpm) with suspicion of coronary artery disease (CAD) were examined by cardiac MSCT. Parameter settings were: 0.75 mm collimation, 2.8mm table feed/rotation, caudocranial scan direction, 80 cc contrast media biphasic injection protocol, gantry rotation time 375 ms, temporal resolution 188 ms). Thirteen coronary segments (sgts) were evaluated in each patient (total number: 806 sgts). Image quality of each segment was determined as: excellent--free of motion artefacts, good--mild motion artefacts, relevant artefacts--still diagnostic value, severe calcification and insufficient image quality--not visualized segment.

RESULTS

301/806 (37%) sgts showed excellent and 294/806 (36%) sgts good image quality. Relevant artefacts were seen in 107/806 (13%) sgts, calcifications in 41/806 (5%) sgts. 63/806 (8%) sgts could not be visualized (34 of them (54%) either segment 9 or 10). Diagnostic image quality was achieved in 702/806 (87%) sgts.

CONCLUSIONS

Due to true 16-slice technology and faster gantry rotation time MSCT image quality could be improved and allows a visualization of the entire coronary tree. Larger, randomized, catheter-controlled studies have to be conducted to determine, whether this improved visualization also translates into better diagnostic accuracy.

Multi–Detector Row CT Coronary Angiography: Influence of Reconstruction Technique and Heart Rate on Image Quality

PURPOSE

To prospectively evaluate to what extent image quality in 16-detector row computed tomographic (CT) coronary angiography is a function of the heart rate and the image reconstruction technique used.

MATERIALS AND METHODS

A total of 70 patients (49 men, 21 women; mean age, 59.1 years +/- 5.8 [standard deviation]) consecutively underwent multi-detector row CT coronary angiography; 49 patients additionally underwent coronary angiography. Image reconstruction was based on both relative and absolute timing. A total of 20 equidistant relative and absolute image reconstructed intervals were assessed by applying a four-step grading scale. Cluster and discrimination analysis, Spearman correlation analysis, and Wilcoxon and chi2 tests were used for statistical analysis. Institutional review board approval and written informed consent were obtained.

RESULTS

Though significantly (P < .001) better image quality was observed for image reconstruction based on absolute timing and in patients with lower heart rates, influence on diagnostic accuracy was not significant. Irrespective of the reconstruction technique used, best image quality was observed in patients with a low heart rate for middiastolic reconstruction intervals (starting points: 61% of R-R interval [range, 40%-75%] and 599.3 msec after R [range, 450-840 msec]) and in patients with a high heart rate for end-systolic or early-diastolic intervals (starting points: 27.3% of R-R interval [range, 10%-45%] and 202.3 msec after R [range, 82-336 msec]). With regard to the vessel section and reconstruction technique, cutoff heart rates of the intervals were 64.0-68.5 beats per minute. Patients with stenoses of more than 50% were identified with 86% sensitivity and specificity, and there was no significant difference between relative and absolute timing (P = .99).

CONCLUSION

In multi-detector row CT coronary angiography, image quality depends on the choice of a suited reconstruction interval. In patients with high heart rates, the best image quality can be obtained with end-systolic and early-diastolic intervals; in patients with low heart rates, the best results are achieved with middiastolic intervals.

Different Reconstruction Intervals for Exclusion of Coronary Artery Calcifications by Retrospectively Gated MDCT

OBJECTIVE

Exclusion of coronary artery calcifications has a high negative predictive value for the diagnosis of coronary artery disease. However, it is known that significant differences in calcium scoring can occur because of the ECG trigger interval. Thus, the aim of the study was to evaluate the influence of different reconstruction intervals on detection of any coronary calcium by using MDCT and retrospective cardiac gating.

CONCLUSION

For a true exclusion of coronary artery calcifications, different reconstruction intervals have to be evaluated.

Non-invasive evaluation of coronary artery bypass grafts using 16-row multi-slice computed tomography with 188 ms temporal resolution

BACKGROUND

Cardiac multi-slice computed tomography (MSCT) scanners permit visualization of the coronary arteries and coronary artery bypass grafts. The latest MSCT generation with true 16-detector slices (Sensation 16 Speed 4 D, Siemens, Forchheim, Germany) provides improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality and accuracy of MSCT diagnosis in patients with previous coronary artery bypass graft (CABG) surgery the following study was conducted.

METHODS AND MATERIAL

Thirteen consecutive patients (pts) (10 male, 3 female, mean age 62 +/- 6.4 [55-73] years, heart rate 68 +/- 11 [52-88] bpm) and a total number of 43 coronary bypass grafts (11 arterial, 32 venous grafts) were examined by MSCT (gantry rotation time 375 ms). In addition to the analysis of coronary bypass grafts, 13 coronary segments (sgts) were evaluated in each patient (n = 169 sgts). MSCT results were compared with coronary angiography.

RESULTS

Forty-one of 43 bypass grafts (95%) were analyzable by MSCT. In conventional angiography 16 of 43 (37%) grafts were occluded. Sixteen of them were correctly diagnosed by MSCT (sensitivity 100%). One graft showed a 50% anastomosis stenosis which was also detected. Twenty-five of 27 grafts without severe lesion showed no significant stenosis in MSCT (specificity 93%, positive predictive value (PPV) 89%, negative predictive value (NPV) 100%). Ninety of 108 (83%) high-grade stenosis (>70%) of the native coronary vessels were correctly detected (sensitivity 83%, PPV 78%). From the 61 sgts without high grade stenosis 36 were correctly classified (specificity 59%, NPV 67%). If sgts number 8, 9 and 10, which are normally not target for revascularization, are excluded sensitivity rises to 89%, specificity to 71%, PPV to 87% and NPV to 75%. The correct clinical diagnosis (absence or presence of a high grade stenosis of at least one bypass graft) was achieved in all patients.

CONCLUSIONS

True 16-slice MSCT with faster gantry rotation time allows detection of lesions in coronary artery bypass grafts with high sensitivity and specificity. The evaluation of native vessels in pts with known CAD remains a diagnostic challenge. However, the correct clinical diagnosis was achieved in all pts. MSCT is a non-invasive tool to assess coronary artery bypass grafts.

Contrast enhancement in electron beam tomography of the heart: comparison of a monomeric and a dimeric iodinated contrast agent in 59 patients

RATIONALE AND OBJECTIVES

The aim of the study is to determine whether intravascular time-density course and visualization of the coronary arteries differ with use of a hyperosmolar monomeric versus an iso-osmolar dimeric contrast agent in electron beam tomography (EBT) of the heart.

MATERIALS AND METHODS

Fifty-nine patients underwent EBT of the coronary arteries using the monomeric ioversol or the dimeric iodixanol at the same concentration of 320 mg I/mL. Contrast volume was determined relative to body surface area and injected over 40 seconds. Intravascular time-density curves were created for quantitative analysis. For qualitative assessment, visualization of coronary arteries on axial scans and three-dimensional reconstructions was scored. Patients were matched for contrast flow, transit time, and mean pulse rate for statistical analysis.

RESULTS

Ioversol produced a significantly greater increase in intravascular density for up to 30 seconds after injection (P < .01) compared with iodixanol. No difference between the two contrast media was seen in the qualitative assessment.

CONCLUSION

Monomeric and dimeric contrast media differ in their time-density curves at coronary EBT, a reason for which is not apparent. Qualitative evaluation of coronary arteries is not affected by this difference.

A novel model to test accuracy and reproducibility of MDCT scan protocols for coronary calcium in vivo

OBJECTIVES

We compared the accuracy and reliability of prospectively triggered, retrospectively ECG gated, and non-gated CT image reconstruction for measurements of coronary artery calcification (CAC) in vivo using a novel animal model.

MATERIALS AND METHODS

In six Yorkshire farm pigs, prefabricated chains of cortical bone fragments were sutured over the epicardial bed of the major coronary arteries. Using a 4-slice MDCT scanner, each animal was imaged with two different protocols: sequential acquisition with prospective ECG triggering, and spiral acquisition with retrospectively ECG gated image reconstruction- non-gated reconstructions were also generated from these latter scans. Two independent observers measured the 'Agatston score' (AS), the calcified volume (CV), and mineral mass (MM). To calculate accuracy of MM measurements the ash weight of the burned bone fragments was compared to MDCT derived MM.

RESULTS

Six pigs successfully underwent surgery and CT imaging (mean heart rate: 86+/-12 bpm). MM measurements from prospectively ECG triggered CT sequential scans were more accurate (p<0.02) and reproducible (p=0.05) than sequential CT scans without ECG triggering or spiral acquisition using retrospective ECG gating.

CONCLUSIONS

At high heart rates prospective ECG triggered image reconstruction is more accurate and reproducible for CAC scoring than retrospective ECG gated reconstruction and non-gated reconstruction.

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.

Imaging of the Cardiac Venous System: Comparison of MDCT and Conventional Angiography

OBJECTIVE

Diagnostic and therapeutic strategies in electrophysiology and interventional cardiology include the coronary venous system. The purpose of this study was to compare MDCT angiography with conventional coronary sinus angiography in terms of detailed anatomic display of the coronary veins.

CONCLUSION

MDCT angiography is a reliable alternative to conventional coronary sinus angiography for detailed anatomic display of the coronary veins.

Image Quality and Diagnostic Accuracy of 16-Slice Multidetector Spiral Computed Tomography for the Detection of Coronary Artery Disease in Elderly Patients

OBJECTIVES

To determine the image quality and diagnostic accuracy of cardiac multislice spiral computed tomography (MSCT) in elderly patients (>65 years old) in comparison to younger patients, this retrospective analysis was performed.

METHODS

The catheter-controlled MSCT results from patients older than 65 years of age were compared with the results of younger patients in a cohort of 117 patients with regard to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and image quality. Fifty-three patients were older than 65 years of age (group 1: 31 men, age range: 72.2 +/- 4.1 years, number of risk factors: 2.6 +/- 1.3, Agatston score: 866 +/- 1090) and 64 were younger (group 2: 45 men, age range: 57.4 +/- 6.1 years, number of risk factors: 2.6 +/- 1.0, Agatston score: 765 +/- 1013). All patients were examined by MSCT (Sensation 16 Speed 4 D; Siemens, Forchheim, Germany, with a gantry rotation time of 375 milliseconds) and invasive coronary angiography. The MSCT results were compared blinded with the results of the coronary angiography with regard to the presence or absence of significant stenosis (>50%) in a 13-segment model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (insufficient image quality) for each segment.

RESULTS

Sensitivity, specificity, PPV, and NPP were not different statistically in both groups (group 1: 0.80/0.96/0.89/0.93 and group 2: 0.89/0.98/0.93/0.97). Three patients (all <65 years old) had to be excluded from analysis because of technical problems. Image quality was significantly better in group 2. Gender, body mass index, number of risk factors, and mean heart rate were not significantly different in either group.

CONCLUSIONS

Age has an impact on MSCT image quality but did not hamper diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out coronary artery disease independently of age. These retrospective data have to be confirmed in larger prospective trials.

[Multislice computed tomography to detect coronary stenosis among asymptomatic patients with cardiovascular risk factors and equivocal prior stress test: preliminary study]

Multislice computed tomography (MSCT) is a non-invasive and validated technique to detect coronary stenoses. Some questions remain about its accuracy to detect coronary stenoses (CS), especially for asymptomatic patients (P) when a prior stress test isn't conclusive.

METHODS

MSCT was performed among 45 asymptomatic men (mean age: 58,3 +/- 16), with a high ten year risk of fatal cardiovascular disease (SCORE 2003 data for low-risk regions of Europe), without any previous coronary history and with previous non conclusive exercise testing. When significant (> 50%) CS was suspected at MSCT, an angiocoronarography (AC) was done.

RESULTS

Eighteen MSCT were normal, unsignificant CS (< 50%) were detected on 14 MSCT and significant coronary stenoses (SCS) for 13 P. Among this 13 P, 19 SCS were identified: 2 SCS of left main coronary artery (CA), 9 of the left descending CA, 6 of the right CA and 2 of the left circumflex CA. 13 CS were confirmed at AC. Finally, because of critical angiographic lesions +/- ischemia at nuclear tomoscintigraphy (NT), 9 P had coronary revascularization (7 catheter based, 2 surgical bypass), 4 P had medical treatment.

DISCUSSION

Benefits of this preliminary study are obvious: 9 coronary revascularization/45 P. However, the place of MSCT for the screening of CS is uncertain, but may be usefull as a complement for the screening of coronary arterial disease.

Two-phase reconstruction for the assessment of left ventricular volume and function using retrospective ECG-gated MDCT: comparison with echocardiography

OBJECTIVE

The aims of our study were to investigate the clinical feasibility of a two-phase reconstruction method based on ECG to evaluate left ventricular (LV) volume and function using cardiac MDCT and to compare these results with those from echocardiography.

SUBJECTS AND METHODS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction were measured using two different methods of cardiac MDCT in 19 patients who had undergone cardiac MDCT and echocardiography. The first was a two-phase reconstruction method based on retrospective ECG-triggering: The end-systolic phase was reconstructed when the reconstruction window was located halfway in the ascending T wave on ECG, and the end-diastolic phase was reconstructed when the reconstruction window was located at the starting point of the QRS complex on ECG. The second was a multiphase reconstruction method: 20 series of images were reconstructed at every 5% throughout the cardiac cycle. The LV volumes and function determined by the two reconstruction methods were compared. The results measured by cardiac MDCT were compared with those obtained by echocardiography.

RESULTS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction measured by the two-phase reconstruction method correlated well with those measured by the multiphase reconstruction method (r = 0.984, 0.978, 0.969, 0.969, respectively). There were no significant differences between the results of the two different reconstruction methods (p > 0.05). The LV volumes showed moderate to good correlation between cardiac MDCT and echocardiography (0.766 < r < 0.940). Ejection fraction measured by cardiac MDCT yielded a significant overestimation of 2.9% +/- 8.7% (mean +/- SD) compared with that measured by echocardiography.

CONCLUSION

A two-phase reconstruction method on cardiac MDCT is relatively simple and can provide an objective standard for reconstructing the appropriate image sets for end-diastole and end-systole without the need to review serial preview images.

Impact of Multidetector CT on 3D CT Angiography

3D Computed Tomographic Angiography (CTA) is a noninvasive volumetric imaging technique increasingly used for evaluation of vascular system. The introduction of Multidetector CT (MDCT) has increased scanning speed, allowing shorter acquisition time, greater volume coverage and decreased contrast requirement while diminishing respiratory motion artifacts. Thin-slice collimation protocols are routinely used which generate isotropic 3D voxels that improve image quality. The ideal CTA study requires scanning at peak vascular enhancement for optimal opacification of arteries with separation of arteries and veins. MDCT has enabled complete lower extremity inflow and runoff studies with a single injection, as well as thin-section CTA covering the entirety of the Carotid arteries and Circle of Willis. Sixteen row MDCT has increased scanning speed further facilitating the development of novel applications such as coronary CTA. CTA when perfomed with MDCT offers a "one scan - many views" option useful in imaging vascular diseases. CTA has important advantages over conventional angiography, such as reduced risk, diminished time and better patient acceptance. With MDCT, 3D CTA is crossing vessel tortuosity and evaluation of vessel fragility.

Multidetector-row computed tomography vs. angiography and intravascular ultrasound for the evaluation of the diameter of proximal coronary arteries

BACKGROUND

Multidetector-row computed tomography has evolved as a promising method for noninvasive visualization of coronary arteries and detection of coronary artery calcification. We determined the accuracy of computed tomography for measurement of coronary artery lumen diameters in comparison to quantitative coronary angiography and intravascular ultrasound (IVUS).

METHODS

Eighteen patients (4 female, age 62+/-8 years) with known or suspected coronary artery disease were investigated by computer tomography (4x1 mm collimation, rotation time: 500 ms, table feed: 1.5 mm/rotation). Coronary angiography and IVUS were performed in the left anterior descending, left circumflex and right coronary artery according to common standards. Lumen diameters were measured at the origin of the coronary artery and 10, 30 and 50 mm distally. Results of all three techniques were compared.

RESULTS

Only measuring points evaluated by all measuring techniques were included. Thus, 50 diameters could be analyzed. The correlation R between computed tomography and angiography measures was 0.909 (p<0.05) at the origin of the artery, 0.907 (p<0.05) at 10, 0.841 (p<0.05) at 30 and 0.780 (p<0.05) at 50 mm distally. The correlation R between computed tomography and IVUS was 0.934 at the origin (p<0.05), 0.867 at 10 (p<0.05), 0.880 at 30 (p<0.05) and 0.727 at 50 mm (p<0.05).

CONCLUSIONS

Multidetector-row computed tomography is a promising tool to measure the proximal coronary artery diameters with a good correlation to angiographic and IVUS measurements. Multidetector-row computed tomography might become more feasible with improvement of technology, e.g. with 16 row scanners.

Multi-detector row computed tomography: imaging the coronary arteries

Over the last 2 years, multi-detector row computed tomographic (MDCT) cardiac imaging has continued to rapidly develop and evolve from the experimental research setting to become a useful clinical tool. The increasing availability of MDCT presents today's clinicians with an additional non-invasive diagnostic cardiac imaging method, in particular for the coronary arteries. With the advent and increasing clinical use of 16-detector row machines, and now with the imminent clinical emergence of 64-channel machines, the improvements in spatial and temporal resolution and sophisticated ECG-gating are allowing motion-free, fast, accurate, detailed, contrast-enhanced cardiac imaging that begins to approach the accuracy of traditional invasive diagnostic techniques. Additional diagnostic information may also be provided.

Comparison of lumens of intermediate coronary stenosis using 16-slice computed tomography versus intravascular ultrasound

We aimed to quantify ambiguous coronary stenosis using the minimal lumen area with 16-slice computed tomography compared with intravascular ultrasound. The sensitivity, specificity, and accuracy for significant lesion classification was 68%, 86%, and 78%, respectively. The correlation between intravascular ultrasound and CT minimal lumen area was r = 0.73 (p <0.001), and the 95% confidence interval for CT measurement was -72% to +56%.

A review of the complementary information available with cardiac magnetic resonance imaging and multi-slice computed tomography (CT) during the study of congenital heart disease

The incidence of congenital heart disease is approximately 4-6 per 1000 new births; however, the number of people living with congenital heart disease (CHD) is increasing, because of improved diagnosis, medical, and surgical management. While echocardiography continues to be the mainstay of non-invasive imaging, cardiac MRI (cMRI) and computed tomography (CT) have taken on increasing roles in the diagnosis of congenital heart disease in infants, children, and importantly, adults who may have limited echocardiographic windows, especially if post-operative. Cardiac MRI and multi-slice CT can complement the diagnostic information obtained by echocardiography and invasive cardiac catheterization. Post-operative imaging of CHD is especially enhanced by the spin echo MRI techniques, while gradient cine echo MRI imaging allows functional information that is not encumbered by geometric assumptions. Phase contrast (velocity encoding) cardiac MRI data can provide information about flow, allowing accurate determination of regurgitation and shunt volume. Gadolinium enhanced cMRI or three-dimensional reconstructed images from multi-slice CT angiography allow excellent delineation of vascular structures in complex heart disease. Coronary imaging, while possible with both modalities, appears more facile with fast CT imaging. This article reviews the literature to provide an assessment of the special techniques and considerations needed during the conduct of cardiac MRI/MRA and multi-slice CT examinations during the diagnosis of congenital heart disease in pediatric and adult patients.

Limited diagnostic yield of non-invasive coronary angiography by 16-slice multi-detector spiral computed tomography in routine patients referred for evaluation of coronary artery disease

AIMS

Multislice spiral computed tomography (MSCT) is a promising non-invasive method to diagnose coronary artery disease (CAD). As no detailed comparative evaluation in consecutive patients referred for evaluation of CAD has been reported, this prospective study evaluating 2384 coronary segments in 149 consecutive patients was performed.

METHODS AND RESULTS

The coronary artery tree was analysed in 16 segments both for coronary angiography (CA) and MSCT; a luminal narrowing > or = 50% based on visual assessment was considered significant. By MSCT, 77% of 2110 angiographically assessable segments could be evaluated, 94% per patient in proximal and 70% in distal segments (P<0.001). Sensitivity of MSCT to detect significant stenoses was 30% in all, but only 10% in peripheral segments. The main limitations were calcifications in 34% of segments and motion artefacts in 24% of patients. Overall diagnostic sensitivity for the presence of significant CAD was 86% but specificity was only 49%.

CONCLUSION

When compared with invasive CA, 16-slice MSCT is of limited diagnostic value for the diagnosis of CAD in consecutive patients. Despite a clinically useful sensitivity for the overall diagnosis of significant CAD, specificity is low. Thus, relevant decisions regarding the need of and suitability for possible revascularization procedures cannot be based on MSCT findings alone.

ECG-gated multi-detector row spiral CT in the assessment of myocardial infarction: correlation with non-invasive angiographic findings

Our objective was to retrospectively evaluate the ability of multidetector-row computed tomography (MDCT) to detect previous myocardial infarctions (MIs) and to correlate necrosis with the status of coronary arteries supplying the infarcted territory. After having clinically evaluated 187 patients referred for ECG-gated MDCT of the coronary arteries, 30 previous MIs were identified in 29 patients (9 recent and 21 chronic). MDCT data were evaluated qualitatively and quantitatively by measuring attenuation values and wall thickness within the infarcted region and normal adjacent myocardium. Each MI was also assigned to the distribution territory of a coronary vessel, and morphological data were combined with MDCT angiographic findings. MDCT was able to detect 25/30 MIs showing an overall sensitivity and specificity of 83 and 91%, respectively. Quantitative analysis revealed a statistically significant difference in attenuation values between normal and infarcted regions (38.9+/-14 HU vs. 104.0+/-16 HU). Regional wall thinning was observed in chronic MIs (4.1+/-2 mm vs. 10.5+/-3.8 mm), and not in patients with recent event (7.9+/-1.6 mm vs 9.1+/-4 mm). In 22/25 cases, MDCT angiographic findings showed the presence of suspicious critical lumen narrowing (n=3), previous coronary stenting (n=14) and surgical revascularization (n=5) in the infarct-related coronary. During a single examination, MDCT might provide comprehensive imaging of MI offering a combined morphological and angiographic assessment.

Multislice Spiral Computed Tomography of the Heart: Technique, Current Applications, and Perspective

Multislice spiral computed tomography (MSCT) is a rapidly evolving, noninvasive technique for cardiac imaging. Knowledge of the principle of electrocardiogram-gated MSCT and its limitations in clinical routine are needed to optimize image quality. Therefore, the basic technical principle including essentials of image postprocessing is described. Cardiac MSCT imaging was initially focused on coronary calcium scoring, MSCT coronary angiography, and analysis of left ventricular function. Recent studies also evaluated the ability of cardiac MSCT to visualize myocardial infarction and assess valvular morphology. In combination with experimental approaches toward the assessment of aortic valve function and myocardial viability, cardiac MSCT holds the potential for a comprehensive examination of the heart using one single examination technique.