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

Diagnostic and prognostic value of non-invasive imaging in known or suspected coronary artery disease

The role of non-invasive imaging techniques in the evaluation of patients with suspected or known coronary artery disease (CAD) has increased exponentially over the past decade. The traditionally available imaging modalities, including nuclear imaging, stress echocardiography and magnetic resonance imaging (MRI), have relied on detection of CAD by visualisation of its functional consequences (i.e. ischaemia). However, extensive research is being invested in the development of non-invasive anatomical imaging using computed tomography or MRI to allow detection of (significant) atherosclerosis, eventually at a preclinical stage. In addition to establishing the presence of or excluding CAD, identification of patients at high risk for cardiac events is of paramount importance to determine post-test management, and the majority of non-invasive imaging tests can also be used for this purpose. The aim of this review is to provide an overview of the available non-invasive imaging modalities and their merits for the diagnostic and prognostic work-up in patients with suspected or known CAD.

Noninvasive Assessment of Plaque Morphology and Composition in Culprit and Stable Lesions in Acute Coronary Syndrome and Stable Lesions in Stable Angina by Multidetector Computed Tomography

OBJECTIVES

The purpose of this study was to assess morphology and composition of culprit and stable coronary lesions by multidetector computed tomography (MDCT).

BACKGROUND

Noninvasive identification of culprit lesions has the potential to improve noninvasive risk stratification in patients with acute chest pain.

METHODS

Thirty-seven patients with acute coronary syndrome (ACS) or stable angina underwent coronary 16-slice MDCT and invasive selective angiography. In all significant coronary lesions two observers measured the degree of stenosis, plaque area at stenosis, and remodeling index and assessed plaque composition. Differences between culprit lesions in patients with ACS and stable lesions in patients with ACS or stable angina were determined.

RESULTS

We analyzed 40 lesions with excellent image quality in 14 patients with ACS and 9 patients with stable angina. Culprit lesions in patients with ACS (n = 14) had significantly greater plaque area and a higher remodeling index than both stable lesions in patients with ACS (n = 13) and in patients with stable angina (n = 13) (17.5 +/- 5.9 mm2 vs. 9.1 +/- 4.8 mm2 vs. 13.5 +/- 10.7 mm2, p = 0.02; and 1.4 +/- 0.3 vs. 1.0 +/- 0.4 vs. 1.2 +/- 0.3, p = 0.04, respectively). The prevalence of non-calcified plaque was 100%, 62%, and 77%, respectively, and the prevalence of calcified plaque was 71%, 92%, and 85%, respectively, in culprit lesions in patients with ACS and in stable lesions in patients with ACS or stable angina.

CONCLUSIONS

We introduce the concept of noninvasive detection and characterization of coronary atherosclerotic lesions in patients with ACS by MDCT. We identified differences in lesion morphology and plaque composition between culprit lesions in ACS and stable lesions in ACS or stable angina, consistent with previous intravascular ultrasound studies.

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.

CT angiography in highly calcified arteries: 2D manual vs. modified automated 3D approach to identify coronary stenoses

BACKGROUND

Two-dimensional axial and manually-oriented reformatted images are traditionally used to analyze coronary data provided by multidetector-row computed tomography angiography (MDCTA). While apparently more accurate in evaluating calcified vessels, 2D methods are time-consuming compared with automated 3D approaches. The purpose of this study was to evaluate the performance of a modified automated 3D approach (using manual vessel isolation and different window and level settings) in a population with high calcium scores who underwent coronary half-millimeter 16-detector-row CT angiography (16 x 0.5-MDCTA).

METHODS

ECG-gated 16 x 0.5-MDCTA (16 x 0.5 mm cross-sections, 0.35 x 0.35 x 0.35 mm3 isotropic voxels, 400 ms rotation) was performed after injection of iopamidol (120-ml, 300 mg/ml) in 19 consecutive patients (11 male, 62+/-10 years-old). Native arteries were independently evaluated for >or=50%-stenoses using both manual 2D and modified automated 3D approaches. Stents and bypass grafts were excluded. Conventional coronary angiography was visually analyzed by 2 observers.

RESULTS

Median Agatston calcium score was 434. Sensitivities, specificities, positive and negative predictive values for detection of >or=50% coronary stenoses using the 2D and modified 3D approaches were, respectively: 74%/63%, 76%/80%, 45%/34%, and 91%/93% (p=NS for all comparisons). Overall diagnostic accuracies were 75 and 78%, respectively (p=NS). Uninterpretable vessels were, respectively: 37% (77/209) and 35% (73/209) - p=NS. Time to analyze a single study was 160+/-23 and 53+/-11 min, respectively (p<0.01).

CONCLUSIONS

This modified automated 3D approach is equivalent to and significantly less time consuming than the traditional manual 2D method for evaluation of >or=50%-stenoses by 16 x 0.5-MDCTA in native coronary arteries of patients with high calcium scores.

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.

Improved vessel morphology measurements in contrast-enhanced multi-detector computed tomography coronary angiography with non-linear post-processing

Multi-detector computed tomography (MDCT) permits detection of coronary plaque. However, noise and blurring impair accuracy and precision of plaque measurements. The aim of the study was to evaluate MDCT post-processing based on non-linear image deblurring and edge-preserving noise suppression for measurements of plaque size. Contrast-enhanced MDCT coronary angiography was performed in four subjects (mean age 55 +/- 5 years, mean heart rate 54 +/- 5 bpm) using a 16-slice scanner (Siemens Sensation 16, collimation 16 x 0.75 mm, gantry rotation 420 ms, tube voltage 120 kV, tube current 550 mAs, 80 mL of contrast). Intravascular ultrasound (IVUS; 40 MHz probe) was performed in one vessel in each patient and served as a reference standard. MDCT vessel cross-sectional images (1 mm thickness) were created perpendicular to centerline and aligned with corresponding IVUS images. MDCT images were processed using a deblurring and edge-preserving noise suppression algorithm. Then, three independent blinded observers segmented lumen and outer vessel boundaries in each modality to obtain vessel cross-sectional area and wall area in the unprocessed MDCT cross-sections, post-processed MDCT cross-sections and corresponding IVUS. The wall area measurement difference for unprocessed and post-processed MDCT images relative to IVUS was 0.4 +/- 3.8 mm2 and -0.2 +/- 2.2 mm2 (p < 0.05), respectively. Similarly, Bland-Altman analysis of vessel cross-sectional area from unprocessed and post-processed MDCT images relative to IVUS showed a measurement difference of 1.0 +/- 4.4 and 0.6 +/- 4.8 mm2, respectively. In conclusion, MDCT permitted accurate in vivo measurement of wall area and vessel cross-sectional area as compared to IVUS. Post-processing to reduce blurring and noise reduced variability of wall area measurements and reduced measurement bias for both wall area and vessel cross-sectional area.

Correlation between image noise and body weight in coronary CTA with 16-row MDCT

RATIONALE AND OBJECTIVES

To evaluate the correlation between image noise and body weight (BW) or body mass index (BMI) in coronary computed tomography angiography (CTA) as a potential parameter for reducing radiation dose in coronary CTA.

MATERIALS AND METHODS

Thirty-six patients who underwent electrocardiogram-gated cardiac CT were analyzed in this study. The patients included 26 men and 10 women with a mean age of 60 years (range 43-79 years). All patients were imaged on a 16-row multidetector CT scanner. Mean value of BW and BMI was 83.5 kg and 28.1, respectively. Image noise was defined as standard deviation (SD) of the attenuation values measured by using 1 cm2 circular region of interest in the ascending aorta at the level of the right main pulmonary artery. The SD values were plotted against BW and BMI. The correlations were examined using a linear regression method. A P value of less than .05 was considered significant.

RESULTS

The r value of linear regression between noise and BW was 0.90 (P < .001). The r value of linear regression between noise and BMI was 0.74 (P = .015).

CONCLUSIONS

Excellent correlation was observed between noise and BW in coronary CTA. These data may be used as potential parameters for customized radiation dose modification to reduce radiation dose in coronary CT examinations.

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.

Accuracy of 16-slice multi-detector CT to quantify the degree of coronary artery stenosis: Assessment of cross-sectional and longitudinal vessel reconstructions

BACKGROUND

Sixteen-slice multi-detector computed tomography (MDCT) permits reliable noninvasive detection of significant coronary stenosis based on qualitative visual assessment. The purpose of this study was to determine the accuracy of MDCT to quantify the degree of coronary stenosis as compared to quantitative coronary angiography (QCA) using two different reconstruction methods.

METHODS

We studied 69 coronary artery lesions from 38 consecutive patients that underwent 16-slice MDCT as a part of research study, which enrolled consecutive subjects scheduled for clinically indicated invasive coronary angiography. Nine coronary artery lesions with motion artifacts, heavily calcified plaques or stents were excluded from the analysis. The degree of stenosis was calculated by two independent readers non-blinded to the location of the stenosis, but blinded to the results of the QCA. MDCT luminal diameters were measured in cross-sectional multi-planar reformatted (CS-MPR) images created perpendicular to the centerline of the vessel and in 5 mm thin-slab maximum intensity projections (MIP) parallel to the long axis of the vessel. Both MDCT methods were compared against QCA.

RESULTS

The mean degree of stenosis as measured by MDCT was closely correlated to QCA for both methods (CS-MPR versus QCA: 61 +/- 23% versus 64 +/- 29%; r2 = 0.83, p < 0.001 and MIP versus QCA: 64 +/- 22% versus 64 +/- 29%; r2 = 0.84, p < 0.001 for MIP. Bland-Altman analysis demonstrated a negative bias of the degree of stenosis of -2.8 +/- 12% using CS-MPR and a minimally positive bias of 0.6 +/- 12% for MIP. In stratified analysis for lesion severity (mild, 0-40%; moderate, 41-70% or severe, > 70%) the agreement between both CS-MPR and MIP was high when compared to QCA (kappa = 0.74 and 0.71, respectively).

CONCLUSION

Multi-detector spiral CT permits accurate quantitative assessment of the degree of coronary stenosis in selected data sets of sufficient quality using both cross-sectional and longitudinal vessel reconstructions.

New imaging techniques for diagnosing coronary artery disease

New tomographic cardiovascular imaging tests, such as intravascular ultrasonography (IVUS), coronary computed tomography (CT) angiography and magnetic resonance imaging (MRI), can be used to assess atherosclerotic plaques for the characterization and early staging of coronary artery disease (CAD). Although IVUS images have very high resolution capable of revealing very early preclinical CAD, it is an invasive technique used clinically only in conjunction with a coronary intervention. Multiple-slice coronary CT angiography, which is noninvasive, shows promise as a diagnostic method for CAD. New 64-slice cardiac CT technology has high accuracy for the detection of lesions obstructing more than 50% of the lumen, with sensitivity, specificity, and positive and negative predictive values all better than 90% in patients without known CAD. Cardiac MRI is also improving accuracy in coronary plaque detection and offers a better opportunity for plaque characterization. With further advances in tomographic imaging of coronary atheromas, the goal will be to detect plaques earlier in the development of CAD and to characterize the plaques most likely to generate a clinical event.

Usefulness of multidetector row spiral computed tomography with 64- x 0.6-mm collimation and 330-ms rotation for the noninvasive detection of significant coronary artery stenoses

Eighty-four patients with suspected coronary artery disease were studied to determine the accuracy of noninvasive coronary angiography using a multidetector computed tomographic scanner with 64- x 0.6-mm collimation and 330-ms gantry rotation. All coronary artery segments with a diameter >1.5 mm were assessed with respect to stenoses >50% decreased diameter. Results were compared with quantitative coronary angiographic findings. After exclusion of unevaluable coronary segments (4%), multidetector computed tomography demonstrated a sensitivity of 93%, a specificity of 97%, and a negative predictive value of 100% in a per-segment analysis. In a per-artery analysis, 15 of 336 arteries (4%) were unevaluable. Sensitivity and specificity in evaluable arteries were 95% and 93%, respectively. In a per-patient analysis (81 of 84 patients included), sensitivity and specificity were 96% and 91%, respectively.

Meta-analysis of comparative diagnostic performance of magnetic resonance imaging and multislice computed tomography for noninvasive coronary angiography

BACKGROUND

Magnetic resonance imaging (MRI) and multislice computed tomography (MSCT) have emerged as potential noninvasive coronary imaging techniques. The objective of the present study was to clarify the current accuracy of both modalities in the detection of significant coronary artery lesions (compared to conventional angiography as the gold standard) by means of a comprehensive meta-analysis of the presently available literature.

METHODS

A total of 51 studies on the detection of significant coronary artery stenoses (> or = 50% diameter stenosis) and comparing results with conventional angiography were identified by means of a MEDLINE search. Weighted sensitivities, specificities, and predictive values, all with 95% CIs, as well as summary odds ratios, were calculated for both techniques. In addition, the relationship between diagnostic specificity and disease prevalence was determined using metaregression analysis.

RESULTS

A comparison of sensitivities and specificities revealed significantly higher values for MSCT (weighted average 85% [95% CI 86%-88%] and 95% [95% CI 95%]) as compared with MRI (weighted average 72%, 95% CI 69%-75% and 87%, 95% CI 86%-88%). A significantly higher odds ratio (16.9-fold) for the presence of significant stenosis was observed for MSCT as compared with MRI (6.4-fold) (P < .0001). Linear regression analysis revealed a better specificity for MSCT versus MRI in lower disease prevalence populations (P = .056).

CONCLUSION

Meta-analysis of the available studies with MRI and MSCT for noninvasive coronary angiography indicates that MSCT has currently a significantly higher accuracy to detect or exclude significant coronary artery disease.

Computed Tomographic Angiography of the Coronary Arteries: Techniques and Applications

Computed tomographic coronary angiography (CT-CA) is a direct but minimally invasive method of visualizing coronary arteries. Multidetector-row computed tomography (MDCT) is currently the CT modality most commonly used for coronary artery imaging. MDCT has been successfully used to detect stenoses in coronary arteries and coronary artery bypass grafts and to assess congenital coronary anomalies. Patients should not undergo CT-CA with MDCT if they have an irregular heart rhythm, a heart rate greater than 70 beats/min, and contraindications to pharmacologic agents for heart rate control, or if they have severe coronary artery disease or are likely to require revascularization.

Non-invasive detection of significant coronary artery disease with multi-section computed tomography angiography in patients with suspected coronary artery disease

AIM

The objective of this prospective study was to compare the accuracy of multi-section computed tomography (MSCT) coronary angiography with invasive selective coronary angiography in the detection of significant coronary stenosis (> or =50% lumen diameter narrowing).

METHODS

Thirty consecutive patients (mean age 59+/-10 years) with suspected coronary artery disease underwent both invasive coronary angiography and MSCT using a 40-section multidetector row machine with temporal resolution of 53ms. Reconstruction images were performed in eight phases of the cardiac cycle. Images of MSCT and invasive coronary angiography were analysed using the 16-segment model of the American Heart Association.

RESULTS

A total of 480 segments from 30 patients were evaluated. Coronary segments distal to a vessel occlusion and segments with coronary stent were not considered for analysis (20 segments in total). Ninety-four (20.4%) segments showed significant (> or =50%) stenosis by invasive coronary angiogram. The accuracy of coronary MSCT was computed on a per segment basis. Average sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 99, 98, 94, and 99%, respectively.

CONCLUSION

This study demonstrated that MSCT is as reliable as coronary angiography at detecting significant obstructive coronary artery disease. In selected groups of patients, it may replace the more invasive and potentially more dangerous conventional coronary angiography.

Pictorial review: electron beam computed tomography and multislice spiral computed tomography for cardiac imaging

Electron beam computed tomography (EBCT) revolutionized cardiac imaging by combining a constant high temporal resolution with prospective ECG triggering. For years, EBCT was the primary technique for some non-invasive diagnostic cardiac procedures such as calcium scoring and non-invasive angiography of the coronary arteries. Multislice spiral computed tomography (MSCT) on the other hand significantly advanced cardiac imaging through high volume coverage, improved spatial resolution and retrospective ECG gating. This pictorial review will illustrate the basic differences between both modalities with special emphasis to their image quality. Several experimental and clinical examples demonstrate the strengths and limitations of both imaging modalities in an intraindividual comparison for a broad range of diagnostic applications such as coronary artery calcium scoring, coronary angiography including stent visualization as well as functional assessment of the cardiac ventricles and valves. In general, our examples indicate that EBCT suffers from a number of shortcomings such as limited spatial resolution and a low contrast-to-noise ratio. Thus, EBCT should now only be used in selected cases where a constant high temporal resolution is a crucial issue, such as dynamic (cine) imaging. Due to isotropic submillimeter spatial resolution and retrospective data selection MSCT seems to be the non-invasive method of choice for cardiac imaging in general, and for assessment of the coronary arteries in particular. However, technical developments are still needed to further improve the temporal resolution in MSCT and to reduce the substantial radiation exposure.

The Frequency and Determinants of Calcification in Intracranial Arteries in Chinese Patients Who Underwent Computed Tomography Examinations

BACKGROUND

Intracranial artery calcification is common but the prevalence and determinants are not well established. We aim to describe the prevalence and location of calcification in intracranial arteries according to brain multi-detector-row computed tomography (MDCT) images, and to investigate its correlation with potential risk factors.

METHODS

We studied consecutive men and women referred for brain CT in December 2004. All patients received a questionnaire regarding their medical history related to atherosclerosis, including traditional risk factors of atherosclerosis, serum chemistry values and inflammatory markers. All CT examinations were done with a 16-slice MDCT and the severity of intracranial artery calcification was categorized.

RESULTS

Four hundred and ninety patients aged 1.4-101 years (62.92+/-19.04; mean+/-SD) were included in our study. There were 340 patients (69.4%) who had intracranial artery calcification. The highest prevalence of intracranial artery calcification was seen in the internal carotid artery (60%), followed by vertebral artery (20%), middle cerebral artery (5%) and basilar artery (5%). Patients with calcification were significantly older than those without calcification (p<0.001). A significantly higher prevalence of calcification was present among patients with hypertension (p<0.001), diabetes (p<0.001), renal failure (p<0.05), atrial fibrillation (p<0.05), smoking (p<0.05), hyperlipidemia (p<0.001), ischemic heart disease (p<0.05) and ischemic stroke (p<0.001). Mean values of serum phosphate, serum urea and CRP level were also significantly higher in patients with intracranial artery calcification (p<0.05, respectively), and there was a trend that patients with intracranial calcification had a higher white blood cell count (p=0.070). Stepwise multiple logistic regression showed age (RR=2.795 per 10 years), a history of ischemic stroke (RR=3.915), and white blood cell count (RR=1.107) to be independently associated with intracranial artery calcification.

CONCLUSIONS

Calcification of the intracranial arteries is associated with age, history of ischemic stroke and white blood cell count. Further prospective studies to investigate the clinical significance of intracranial artery calcification are needed.

Clinical utility of coronary CT angiography: Coronary stenosis detection and prognosis in ambulatory patients

INTRODUCTION

Multislice CT coronary angiography (MSCTA) accurately detects stenosis in patients undergoing coronary arteriography, but its accuracy in clinical outpatients is less certain. This study retrospectively analyzed MSCTA performance in a large outpatient cohort and examined 6-month clinical follow-up in those without invasive CA.

METHODS

Patients underwent MSCTA for clinical indications including symptoms or noninvasive results being either equivocal or suspected as incorrect by referring clinicians. Standard 16-slice CT scanner techniques were used, and results were analyzed on the basis of both patient and vessel. Patients were treated medically or sent to invasive angiography on the basis of MSCTA results and judgment of referring clinicians. All invasive angiograms were analyzed using quantitative coronary angiography. Six-month clinical follow-up was determined in patients without CA.

RESULTS

One thousand fifty-three consecutive patients were referred for MSCTA, resulting in 994 interpretable scans. Mean age was 58+/-13 years, 55% were male, 50% had prior noninvasive testing, and 90% had symptoms. Invasive angiography was performed in 160 patients, with significant stenoses present in 69%. MSCTA demonstrated 87% and 89% accuracy by patient- and vessel-based analysis, respectively, and was most accurate in the left main and right coronary arteries. Only two patients not referred for angiography had significant stenosis in those undergoing 6-month follow-up.

CONCLUSIONS

MSCTA accurately detects obstructive coronary stenosis in clinical patients with possible cardiac symptoms, and effectively triages them for invasive angiography. Negative results are highly accurate in ruling out obstructive disease. Six-month prognosis is excellent in patients without significant disease determined by MSCT.

Non-invasive multislice computed tomography coronary angiography for imaging coronary arteries, stents and bypass grafts

Abstract Multislice computed tomography (MSCT) is evolving rapidly and available data suggest that MSCT coronary angiography may be a reliable and accurate non-invasive imaging modality of coronary arteries. Current generations of MSCT scanners have high sensitivity and specificity for diagnosing native coronary artery disease and coronary bypass graft occlusion. The performance of MSCT in the evaluation of stent patency is still being assessed. In comparison with conventional selective coronary angiography (SCA), MSCT is non-invasive, cheaper and it has the advantages of imaging plaque compositions as well as assessment of luminal patency. Nevertheless, the role of MSCT in the management of coronary artery disease is yet to be fully defined.

Novel Method of Displaying Coronary CT Angiography Angiographic View

Background A method of displaying coronary computed tomography (CT) angiography, which enables evaluation of coronary artery disease (CAD) with fewer images and is understandable to the third person, is preferable. Methods and Results A maximum intensity projection image was created in which contrast media in the ventricles is eliminated, enabling an overview of CAD in a single 3-dimensional (D) image that can be rotated to be viewed at various angles and is easily understood by a third person. Conclusions A novel method of displaying coronary CT angiography in a single 3-D image has been developed and we believe it should become available for many workstations.

Three Cases of Iatrogenic Coronary Ostial Stenosis After Aortic Valve Replacement

BACKGROUND

Iatrogenic coronary ostial stenosis (ICOS) is a rare but potentially life-threatening complication of aortic valve replacement (AVR). This complication is usually diagnosed by angiography and treated with aortocoronary bypass surgery.

CASE REPORTS

In the present 3 cases pre-operative coronary angiography confirmed normal coronary arteries and they underwent uncomplicated AVR. Coronary lesions were clinically manifest within 4 months after surgery, and repeat coronary angiography demonstrated bilateral ostial stenosis in 1 patient and left main trunk stenosis in the other 2. Two cases were detected by multidetector computed tomography (MDCT) before angiography. MDCT and Virtual Histology suggested fibrous tissue formation in the lesions. All 3 patients were successfully underwent percutaneous coronary intervention (PCI) and stenting. The post-procedure clinical course has been uneventful, except for elective stenting of a recurrent lesion in 1 asymptomatic patient.

CONCLUSIONS

The incidence of ICOS after AVR is low. Noninvasive MDCT is useful for early diagnosis and PCI is a possible alternative treatment. ICOS may be caused by fibrous tissue formation, and therefore be distinct from conventional atherosclerosis.

Risk factors associated with soft coronary artery plaques in Japanese, as determined by 16 slice multidetector-row computed tomography

PURPOSE

The acute coronary syndrome is often caused by the rupture of plaques and thrombus formation even without significant stenosis, and patients with soft plaques, but without significant stenosis evidenced by coronary angiography (CAG), often develop an acute coronary syndrome. To address this discrepancy, a qualitative diagnosis of coronary plaques using a 16 slice multidetector-row CT was conducted.

METHODS AND RESULTS

Volume rendering and cross-sectional MPR images were obtained. Based on the CT values, plaques on the coronary artery wall were classified as lipid-rich soft plaques (CT value<50 HU) and non-soft plaques (>50 HU).A significant correlation was observed between the percent stenosis determined in cross-sectional MPR images and those determined by CAG (r=+0.92, p<0.01). Diffuse plaques with CT values of less than 50 HU often caused stenosis at level of 75% or less, which were not indicated by percutaneous transluminal coronary angioplasty.

CONCLUSIONS

Although diffuse soft plaques with CT values less than 50 HU are not an indication of intervention, a risk of an acute coronary syndrome exists, due to rupture. These soft plaques must be stabilized by treatment even when they do not cause significant stenosis, and MDCT is considered to be useful for their evaluation.

Visualization of a large ventricular aneurysm in a young man by 16-slice multi-detector row spiral computed tomography before successful surgical treatment

Left ventricular (LV) aneurysm after myocardial infarction without any clinical symptoms is a rare complication of coronary artery disease. In most cases, especially in young people, this complication is diagnosed too late, after rupture into the pericardial cavity has occurred. Here we present the successful surgical repair of a large LV aneurysm in a 35-year-old man. We could visualize this aneurysm and the coronary arteries non-invasively by contrast-enhanced 16-slice multi-detector row spiral computed tomography (MDCT).

Non-invasive half millimetre 32 detector row computed tomography angiography accurately excludes significant stenoses in patients with advanced coronary artery disease and high calcium scores

OBJECTIVE

To show an overall diagnostic accuracy > or = 90% for detection of > or = 50% stenoses by coronary half millimetre 32 detector row computed tomography angiography (32 x 0.5-MDCTA) in patients with advanced coronary artery disease (CAD) and a high likelihood of raised calcium scores.

METHODS

ECG gated 32 x 0.5-MDCTA (32 x 0.5 mm cross sections, 0.35 x 0.35 x 0.35 mm3 isotropic voxels, 400 ms rotation) was performed after injection of iodixanol (120 ml, 320 mg/ml) in 30 consecutive patients (25 men, mean (SD) age 59 (13) years, body mass index 26.2 (4.9) kg/m2). Native arteries, including > or = 1.5 mm branches, and bypass grafts were screened for > or = 50% stenoses. Stents were excluded. Conventional coronary angiography (performed 18 (12) days before 32 x 0.5-MDCTA) was analysed by quantitative coronary angiography.

RESULTS

Median Agatston calcium score was 510 (range 3-5066). Sensitivity, specificity, and positive and negative predictive values for detection of > or = 50% stenoses in native arteries were 76% (29 of 38), 94% (190 of 202), 71% (29 of 41), and 96% (190 of 199), respectively. Overall diagnostic accuracy was 91% (219 of 240). Due to the following artefacts 20% (69 of 352) of the vessels were excluded: motion, noise, and low contrast enhancement isolated or in combination (45 of 69 (65%)); image distortion by implantable cardioverter-defibrillator or pacemaker leads (18 of 69 (26%)); and blooming secondary to severe calcification (6 of 69 (9%)).

CONCLUSIONS

Coronary 32 x 0.5-MDCTA accurately excludes > or = 50% stenoses in patients with advanced CAD and high calcium scores with an overall diagnostic accuracy of 91%.

Multidetector CT coronary angiography: have we found the holy grail of non-invasive coronary imaging?

Is technology about to deliver on the long awaited goal of effective non-invasive methods for visualising and assessing coronary arteries?

Assessment of left ventricular myocardial function using 16-slice multidetector-row computed tomography: comparison with magnetic resonance imaging and echocardiography

OBJECTIVE

To assess functional parameters using multidetector-row computed tomography (MDCT) and echocardiography and to compare the results with magnetic resonance imaging (MRI).

MATERIALS AND METHODS

End-diastolic-volume (EDV), end-systolic-volume (ESV), stroke-volume (SV), ejection-fraction (EF), and myocardial mass (MM) were calculated based on CT data sets from 52 patients. Echocardiography was performed in 24 of the 52 patients. The results from MDCT and echocardiography were compared with MRI.

RESULTS

A strong correlation between MDCT and MRI (r=0.66-0.90) was found for all parameters. Echocardiography revealed a low or moderate correlation (0.05-0.59). Compared to MRI the average differences with MDCT were for EDV 15.1 ml, ESV 10.6 ml, SV 4.5 ml, EF 1.8%, and MM 8.2 g, for EDV determined by echocardiography 36.2 ml, ESV 6.8 ml, and EF 13.9%. Bland-Altman analysis revealed acceptable limits of agreement between MRI and MDCT.

CONCLUSIONS

MDCT enables reliable quantification of left ventricular function. Echocardiography was found to have only a moderate agreement of functional parameters with MRI.

Diagnosis of Coronary In-Stent Restenosis With Multidetector Row Spiral Computed Tomography

OBJECTIVES

The purpose of this study was to assess the accuracy of a new generation spiral multidetector computed tomography (MDCT) scanner (Brilliance 40, Philips Medical Systems, Cleveland, Ohio) in the diagnosis of coronary in-stent restenosis (ISR).

BACKGROUND

Noninvasive imaging of ISR would be clinically useful, but artifacts caused by metallic stent struts have limited the role of early generation MDCT scanners.

METHODS

We examined 65 patients (age 63 +/- 12 years, 48 [73.8%] men) with 111 implanted coronary stents who were referred for repeat invasive coronary angiography (ICA). Patients underwent 40-slice MDCT one to three days before scheduled ICA, using intravenous contrast enhancement. Images were reconstructed in multiple formats using retrospective electrocardiographic gating. Stents were viewed in their long and short axes and luminal contrast attenuation graded from MDCT grade 1 (minimal restenosis) to 4 (severe restenosis) by consensus of two observers.

RESULTS

In-stent restenosis (>/=60% luminal narrowing by quantitative coronary angiography) was found on ICA in 18 (16.2%) of the stented segments and in 16 (24.6%) patients. The MDCT findings correlated with ICA restenosis, with restenosis in only 1 of 59 (1.6%) MDCT grade 1 segments, but in more than three-quarters (12 of 15, 80%) of MDCT grade 4 segments (sensitivity 72.2%, specificity 92.5%, positive predictive value [PPV] 65.0%, negative predictive value [NPV] 94.5% [five stents not assessable by MDCT considered as restenosis]). Using MDCT grades 3 or 4 combined for restenosis, sensitivity of MDCT was 88.9%, specificity 80.6%, PPV 47.1%, and NPV 97.4%.

CONCLUSIONS

In-stent restenosis can be diagnosed with moderate sensitivity using a new generation 40-slice MDCT scanner. The high NPV implies a significant role for MDCT in excluding ISR.

Comparison of the degree of coronary stenoses by multidetector computed tomography versus by quantitative coronary angiography

Sixteen-slice multidetector computed tomography (MDCT) and quantitative coronary angiography (QCA) were performed in 29 patients. Quantification of the degree of luminal narrowing and lesion length measurements were performed independently on MDCT and QCA at 42 sites with sufficient computed tomographic image quality. The correlation between MDCT and QCA for quantifying the degree of stenosis was excellent (r2 = 0.93), although a systematic overestimation was observed by MDCT (bias 4% +/- 8%). The correlation between MDCT and QCA was moderate with respect to lesion length (r2 = 0.54). In the absence of severe calcifications or motion artifacts, MDCT permits noninvasive quantification of coronary stenosis.

Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography

OBJECTIVES

The aim of our study was to evaluate the diagnostic accuracy of multislice computed tomography (MSCT) coronary angiography using a new 64-slice scanner.

BACKGROUND

The new 64-slice MSCT scanner has improved spatial resolution of 0.4 mm and a faster rotation time (330 ms) compared to prior MSCT scanners.

METHODS

We studied 70 consecutive patients undergoing elective invasive coronary angiography. Patients were excluded for atrial fibrillation, but not for high heart rate, coronary calcification, or obesity. All vessels were analyzed, including those <1.5 mm in diameter; MSCT lesions were analyzed quantitatively as well as by a qualitative scale and compared to quantitative coronary angiography (QCA). Results were also analyzed for significant coronary stenoses (over 50% luminal narrowing) by segment, by artery, and by patient.

RESULTS

All scans showed diagnostic image quality. Of 1,065 segments, 935 (88%) could be evaluated, and 773 of 935 (83%) could be assessed quantitatively by both MSCT and QCA. The Spearman correlation coefficient between MSCT and QCA was 0.76 (p < 0.0001). Bland-Altman analysis demonstrated a mean difference in percent stenosis of 1.3 +/- 14.2%. A total of 26% of patients had calcium scores above 400 Agatston U, 25% had heart rates >70 beats/min, and 50% were obese. Specificity, sensitivity, and positive and negative predictive values for the presence of significant stenoses were: by segment (n = 935), 86%, 95%, 66%, and 98%, respectively; by artery (n = 279), 91%, 92%, 80%, and 97%, respectively; by patient (n = 70), 95%, 90%, 93%, and 93%, respectively.

CONCLUSIONS

Our results indicate high quantitative and qualitative diagnostic accuracy of 64-slice MSCT in comparison to QCA in a broad spectrum of patients.

Left ventricular function studied with MDCT

Accurate determination of left ventricular (LV) myocardial function is fundamental for clinical diagnosis, risk stratification, and estimation of prognosis in patients with ischemic and nonischemic cardiomyopathy. Primarily, multi-detector-row spiral CT (MDCT) of the heart aimed at detecting coronary artery obstruction and cardiac morphology. Multiple studies have demonstrated that retrospectively, ECG-gated MDCT determination of LV volumes and consequently global LV function parameters is feasible in good agreement with established imaging modalities such as cineventriculography, echocardiography, and cine magnetic resonance imaging (CMR). Post-processing tools allow fast and semi-automatic determination of LV function parameters from MDCT data in analogy to known CMR evaluation approaches. Although MDCT is not considered to be first-line modality for LV function assessment, this technique provides accessory dynamic information in patients undergoing MDCT coronary angiography, contributing to combined assessment of cardiac morphology and function without need of additional radiation exposure. MDCT regional LV wall motion analysis at rest is feasible, but further improvement in temporal resolution seems mandatory to match results obtained from competing modalities. This paper will discuss the diagnostic potential of MDCT for assessment of LV function with regards to accuracy and clinical applications, as well as limitations, particularly in comparison with CMR as modality of reference.

Diagnostic accuracy of multislice computed tomography coronary angiography is improved at low heart rates

PURPOSE

Assess the effect of heart rate on diagnostic accuracy for the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT).

MATERIAL AND METHODS

About 120 patients (105 males; 59+/-11 years) with suspected coronary artery disease who underwent conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA (Sensation 16, Siemens, Germany), with the following protocol: collimation 16 x 0.75 mm, gantry rotation time 420 ms, feed/rotation 3.0 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol (Visipaque 320 mg l/ml, Amersham, UK) at 4 ml/s and the delay was defined with a bolus tracking technique. In all patients the mean heart rate (HR) during the scan was used as a criteria to divide the population in two groups of 60 patients each. In one group (Low HR) the 60 patients with lower heart rates, and in the other group (High HR) the patients with higher heart rates. In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (>or=50% lumen reduction) was evaluated in vessels >or=2 mm of diameter using quantitative CA as reference standard. The difference in diagnostic accuracy were compared with a Chi(2) test and a p<0.05 was considered significant.

RESULTS

There was no significant difference between the two groups regarding age, gender, weight, mean intravascular attenuation, and calcium score. Overall 1,310 (652 for Low HR and 658 for High HR) segments with 219 (105 for Low HR and 114 for High HR) significant lesions were available for the analysis. The average heart rate was 52+/-4 HU and 63+/-5 HU for Low HR and High HR, respectively (p<0.001). The sensitivity and specificity were 92 and 96% for Low HR and 90 and 92% for High HR (p<0.05). There were 22 vs. 44 false positives, and 8 vs. 12 false negatives in the Low HR and High HR, respectively.

CONCLUSION

Increasing HR significantly deteriorates diagnostic accuracy in MSCT-CA.

Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound

OBJECTIVES

The aim of the present study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) to identify and quantify atherosclerotic coronary lesions in comparison with catheter-based angiography and intravascular ultrasound (IVUS).

BACKGROUND

Currently, the ability of multislice CT to quantify the degree of coronary artery stenosis and dimensions of coronary plaques has not been evaluated.

METHODS

We included 59 patients scheduled for coronary angiography due to stable angina pectoris. A contrast-enhanced 64-slice CT (Senation 64, Siemens Medical Solutions, Forchheim, Germany) was performed before the invasive angiogram. In a subset of 18 patients, IVUS of 32 vessels was part of the catheterization procedure.

RESULTS

In 55 of 59 patients, 64-slice CT enabled the visualization of the entire coronary tree with diagnostic image quality (American Heart Association 15-segment model). The overall correlation between the degree of stenosis detected by quantitative coronary angiography compared with 64-slice CT was r = 0.54. Sensitivity for the detection of stenosis <50%, stenosis >50%, and stenosis >75% was 79%, 73%, and 80%, respectively, and specificity was 97%. In comparison with IVUS, 46 of 55 (84%) lesions were identified correctly. The mean plaque areas and the percentage of vessel obstruction measured by IVUS and 64-slice CT were 8.1 mm2 versus 7.3 mm2 (p < 0.03, r = 0.73) and 50.4% versus 41.1% (p < 0.001, r = 0.61), respectively.

CONCLUSIONS

Contrast-enhanced 64-slice CT is a clinically robust modality that allows the identification of proximal coronary lesions with excellent accuracy. Measurements of plaque and lumen areas derived by CT correlated well with IVUS. A major limitation is the insufficient ability of CT to exactly quantify the degree of stenosis.

Potential Indications for Coronary Angiography by Computed Tomography

Recent advances in computed tomography technology have made possible angiographic images of relatively small, moving vascular structures such as the coronary arteries. Computed tomographic coronary angiography is an exciting modality which has several obvious advantages over invasive catheterization, such as its relatively noninvasive nature and rapid speed of acquisition. However, significant drawbacks still exist, including limitations of spatial and temporal resolution and radiation exposure. Computed tomographic coronary angiography appears best suited as a diagnostic modality for the patient population with a low-to-moderate pretest probability of coronary artery disease, and for specific indications such as the imaging of coronary anomalies and bypass grafts and before biventricular pacemaker placement and atrial fibrillation ablation.

Multislice spiral computed tomographic angiography of coronary arteries in patients with suspected coronary artery disease: an effective filter before catheter angiography?

BACKGROUND

Despite impressive image quality, it is unclear if noninvasive coronary angiography with multislice spiral computed tomography (CT) is powerful enough to act as a filter before invasive angiography (INV-A) in symptomatic patients.

METHODS AND RESULTS

We therefore studied 133 consecutive symptomatic patients with suspected coronary artery disease (CAD) and an indication for INV-A (chest pain and signs of ischemia in conventional stress tests). Patients with known CAD, acute coronary syndrome, or a calcium volume score >1000 were excluded. In all patients, both INV-A and multislice CT angiography (MSCT-A) (Philips MX 8000 multislice spiral CT, scan time 250 milliseconds, slice thickness 1.3 mm, 120 mL of contrast agent, 4 mL/s, retrospective gating) were directly compared by 2 independent investigators using the American Heart Association 15-segment model. Altogether, we studied 1596 segments, 74% had diagnostic image quality. Multislice CT angiography correctly identified 68 significant stenoses of the 75 stenoses seen with INV-A (sensitivity 91%). In 945 of 1185 diagnostic segments, stenosis could correctly be ruled out with MSCT-A. There were 3 times more stenoses seen with MSCT-A compared with INV-A (positive predictive value 29%) mainly because of misclassification of nonobstructive plaques as stenosis. The per-patient analysis allowed to exclude significant CAD in 42 (32%) of 133 patients. In only 6 of 53 patients, MSCT-A failed to detect significant stenosis, 4 of those were in small segments not requiring intervention. Calcium scoring alone was less suited as a filter before angiography: 25 patients (18% of study group) had a calcium score = 0, and 8 of these patients turned out to have significant stenoses.

CONCLUSION

Multislice CT angiography, but not calcium scoring alone, offers promise to reduce the number of INV-A in symptomatic patients with suspected CAD by up to one third with minimal risk for the patient.

Detection of coronary artery stenoses using multi-detector CT with 16 x 0.75 collimation and 375 ms rotation

AIMS

Insufficient spatial and temporal resolutions have limited image quality and accuracy of multi-detector CT (MDCT) for coronary artery visualization and detection of stenoses. We assessed the accuracy of a new 16-slice scanner with 370 ms rotation and 0.75 mm collimation for detection of coronary stenoses using an analysis approach based on coronary artery segments.

METHODS AND RESULTS

Fifty consecutive patients scheduled for diagnostic coronary angiography in stable clinical condition and sinus rhythm were enrolled. All patients with a heart rate > 60 b.p.m. received 100 mg atenolol p.o. and up to four doses of 5 mg metoprolol i.v. before the scan. MDCT was performed using 16 x 0.75 mm collimation, 120 kV, and ECG-gated tube current modulation. Ninety millilitres of contrast agent was injected intravenously. MDCT images were visually analysed using the 16-segment coronary artery model of the American Heart Association and compared with invasive, quantitative coronary angiography in a blinded fashion. A significant stenosis was assumed if the diameter reduction was > or = 50%. Mean heart rate was 58 b.p.m. during MDCT. After exclusion of two patients with not fully evaluable data sets, MDCT correctly identified at least one coronary stenosis in all 25 patients with significant coronary lesions in angiography and correctly demonstrated the absence of stenoses in 19/23 patients (sensitivity 100%, specificity 83%). Sensitivity and specificity for all 50 patients were 93 and 83%, respectively. On a per-segment basis, nine coronary segments distal of total occlusions and 128 coronary segments with a reference diameter < 1.5 mm were excluded from the analysis. Twenty-eight of the included 663 segments (4%) were unevaluable due to calcification or motion artefact. In the remaining 635 segments, 50/53 stenoses were detected by MDCT (sensitivity 94%, specificity 96%, negative predictive value 99%, positive predictive value 69%).

CONCLUSION

Increasing temporal and spatial resolutions of MDCT lead to improved evaluation and diagnostic accuracy for detection of coronary stenoses.

Diagnostic modalities for the evaluation of anomalous left main coronary arteries

Anomalous coronary arteries are rare and usually identified as an incidental finding during cardiac catheterization. The particular difficulty with cardiac catheterization techniques is not necessarily the presence of the anomalous coronary artery, but its anatomic course. Oftentimes, surgical intervention is necessary once these anomalies are discovered. The identification and anatomic characterization of anomalous coronary arteries has been significantly advanced with the use of current diagnostic noninvasive imaging modalities. We present 3 cases of an anomalous left main coronary artery that arises from the right sinus of Valsalva. Noninvasive imaging methods provided a clear anatomic course of the anomalous vessel.

Nuclear Cardiology

Nuclear cardiology has shown double digit growth yearly over the last few years and remains the second most commonly performed noninvasive cardiac imaging investigation of choice. Approximately 9 million studies performed yearly in the U.S. alone. As cardiovascular disease remains the largest healthcare problem around the world despite increasing healthcare spending there is growing interest to enhance the use of cost effective diagnostic tools, such as nuclear cardiology. Recent development of technology has seen the addition of hybrid imaging tools such PET/CT and SPECT/CT into the armorial. More data is expected to become available on this subject within the next few years, and we also expect several molecular imaging tests to become available for clinical use. Despite easy availability of these diagnostic tools, cardiac mortality and morbidity in patients with long term diabetes and also in the postoperative setting remains unexpectedly high and emergency department physician are still being sued after patients being discharged with undiagnosed chest pain. The value of the use of nuclear cardiology studies is briefly reviewed in these clinical settings.