Willem B. Meijboom

Multislice Spiral Computed Tomography for the Evaluation of Stent Patency After Left Main Coronary Artery Stenting A Comparison With Conventional Coronary Angiography and Intravascular Ultrasound

Background— Surveillance conventional coronary angiography (CCA) is recommended 2 to 6 months after stent-supported left main coronary artery (LMCA) percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR), with its attendant risks. Multislice computed tomography (MSCT) is a promising technique for noninvasive coronary evaluation. We evaluated the diagnostic performance of high-resolution MSCT to detect ISR after stenting of the LMCA. Methods and Results— Seventy-four patients were prospectively identified from a consecutive patient population scheduled for follow-up CCA after LMCA stenting and underwent MSCT before CCA. Until August 2004, a 16-slice scanner was used (n=27), but we switched to the 64-slice scanner after that period (n=43). Patients with initial heart rates >65 bpm received β-blockers, which resulted in a mean periscan heart rate of 57±7 bpm. Among patients with technically adequate scans (n=70), MSCT correctly identified all patients with ISR (10 of 70) but misclassified 5 patients without ISR (false-positives). Overall, the accuracy of MSCT for detection of angiographic ISR was 93%. The sensitivity, specificity, and positive and negative predictive values were 100%, 91%, 67%, and 100%, respectively. When analysis was restricted to patients with stenting of the LMCA with or without extension into a single major side branch, accuracy was 98%. When both branches of the LMCA bifurcation were stented, accuracy was 83%. For the assessment of stent diameter and area, MSCT showed good correlation with intravascular ultrasound (r=0.78 and 0.73, respectively). An intravascular ultrasound threshold value ≥1 mm was identified to reliably detect in-stent neointima hyperplasia with MSCT. Conclusions— Current MSCT technology, in combination with optimal heart rate control, allows reliable noninvasive evaluation of selected patients after LMCA stenting. MSCT is safe to exclude left main ISR and may therefore be an acceptable first-line alternative to CCA.

Dual source coronary computed tomography angiography for detecting in-stent restenosis

Objective: To evaluate the performance of dual source CT coronary angiography (DSCT-CA) in the detection of in-stent restenosis (⩾50% luminal narrowing) in symptomatic patients referred for conventional angiography (CA). Design/patients: 100 patients (78 males, age 62 (SD 10)) with chest pain were prospectively evaluated after coronary stenting. DSCT-CA was performed before CA. Setting: Many patients undergo coronary artery stenting; availability of a non-invasive modality to detect in-stent restenosis would be desirable. Results: Average heart rate (HR) was 67 (SD 12) (range 46–106) bpm. There were 178 stented lesions. The interval between stenting and inclusion in the study was 35 (SD 41) (range 3–140) months. 39/100 (39%) patients had angiographically proven restenosis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of DSCT-CA, calculated in all stents, were 94%, 92%, 77% and 98%, respectively. Diagnostic performance at HR <70 bpm (n = 69; mean 58 bpm) was similar to that at HR ⩾70 bpm (n = 31; mean 78 bpm); diagnostic performance in single stents (n = 95) was similar to that in overlapping stents and bifurcations (n = 83). In stents ⩾3.5 mm (n = 78), sensitivity, specificity, PPV, NPV were 100%; in 3 mm stents (n = 59), sensitivity and NPV were 100%, specificity 97%, PPV 91%; in stents ⩽2.75 mm (n = 41), sensitivity was 84%, specificity 64%, PPV 52%, NPV 90%. Nine stents ⩽2.75 mm were uninterpretable. Specificity of DSCT-CA in stents ⩾3.5 mm was significantly higher than in stents ⩽2.75 mm (OR  = 6.14; 99%CI: 1.52 to 9.79). Conclusion: DSCT-CA performs well in the detection of in-stent restenosis. Although DSCT-CA leads to frequent false positive findings in smaller stents (⩽2.75 mm), it reliably rules out in-stent restenosis irrespective of stent size.

Optimal Electrocardiographic Pulsing Windows and Heart Rate : Effect on Image Quality and Radiation Exposure at Dual-Source Coronary CT Angiography

PURPOSE To determine the optimal width and timing of the electrocardiographic (ECG) pulsing window within the cardiac cycle in relation to heart rate (HR), image quality, and radiation exposure in patients who are suspected of having coronary artery disease. MATERIALS AND METHODS The institutional review board approved the study, and all patients gave informed consent. Dual-source computed tomography (CT) was performed in 301 patients (mean HR, 70.1 beats per minute +/- 13.3 [standard deviation]; range, 43-112 beats per minute) by using a wide ECG pulsing window (25%-70% of the R-R interval). Data sets were reconstructed in 5% steps from 20%-75% of R-R interval. Image quality was assessed by two observers on a per-segment level and was classified as good or impaired. High-quality data sets were those in which each segment was of good quality. The width and timing of the image reconstruction window was calculated. On the basis of these findings, an optimal HR-dependent ECG pulsing protocol was designed, and the potential dose-saving effect on effective dose (in millisieverts) was calculated. RESULTS At low HR (< or = 65 beats per minute), high-quality data sets were obtained during end diastole (ED); at high HR (> or = 80 beats per minute), they were obtained during end systole (ES); and at intermediate HR (66-79 beats per minute), they were obtained during both ES and ED. Optimal ECG pulsing windows for low, intermediate, and high HR were at 60%-76%, 30%-77%, and 31%-47% of the R-R interval, respectively, and with these levels, the effective dose was decreased at low HR from 18.7 to 6.8 mSv, at intermediate HR from 14.7 to 13.4 mSv, and at high HR from 11.3 to 4.2 mSv. CONCLUSION With optimal ECG pulsing, radiation exposure to patients, particularly those with low or high HR, can be reduced with preservation of image quality.

64-Slice CT coronary angiography in patients with non-ST elevation acute coronary syndrome

Background: A high diagnostic accuracy of 64-slice CT coronary angiography (CTCA) has been reported in selected patients with stable angina pectoris, but only scant information is available in patients with non-ST elevation acute coronary syndrome (ACS). Objectives: To study the diagnostic performance of 64-slice CTCA in patients with non-ST elevation ACS. Patients and methods: 64-slice CTCA was performed in 104 patients (mean (SD) age 59 (9) years) with non-ST elevation ACS. Two independent, blinded observers assessed all coronary arteries for stenosis, using conventional quantitative angiography as a reference. Coronary lesions with ⩾50% luminal narrowing were classified as significant. Results: Conventional coronary angiography demonstrated the absence of significant disease in 15% (16/104) of patients, and the presence of single-vessel disease in 40% (42/104) and multivessel disease in 44% (46/104) of patients. Sensitivity for detecting significant coronary stenoses on a patient-by-patient analysis was 100% (88/88; 95% CI 95 to 100), specificity 75% (12/16; 95% CI 47 to 92), and positive and negative predictive values were 96% (88/92; 95% CI 89 to 99) and 100% (12/12; 95% CI 70 to 100), respectively. Conclusion: 64-slice CTCA has a high sensitivity to detect significant coronary stenoses, and is reliable to exclude the presence of significant coronary artery disease in patients who present with a non-ST elevation ACS.

Impact of Heart Rate Frequency and Variability on Radiation Exposure, Image Quality, and Diagnostic Performance in Dual-Source Spiral CT Coronary Angiography

PURPOSE To investigate the effect of heart rate frequency (HRF) and heart rate variability (HRV) on radiation exposure, image quality, and diagnostic performance to help detect significant stenosis (> or =50% lumen diameter reduction) by using adaptive electrocardiographic (ECG) pulsing at dual-source (DS) spiral computed tomographic (CT) coronary angiography. MATERIALS AND METHODS Institutional review committee approval and informed consent were obtained. No prescan beta-blockers were applied. Unenhanced CT and CT coronary angiography with adaptive ECG pulsing were performed in 927 consecutive patients (600 men, 327 women; mean age, 60.3 years +/- 11.0 [standard deviation]) divided in three HRF groups: low, intermediate, and high (< or =65, 66-79, and > or =80 beats/min, respectively), and four HRV groups given mean interbeat difference (IBD) during CT coronary angiography: normal, minor, moderate, and severe (IBDs of 0-1, 2-3, 4-10, and >10, respectively). Radiation exposure and image quality were also evaluated. In 444 of these, diagnostic performance was presented as sensitivity, specificity, positive predictive values (PPVs), and negative predictive values and likelihood ratios with corresponding 95% confidence intervals by using quantitative coronary angiography as the reference standard. RESULTS CT coronary angiography yielded good image quality in 98% of patients and no significant differences in image quality were found among HRF and HRV groups. Radiation exposure was significantly higher in patients with low versus high HRF and in patients with severe versus normal HRV. No significant differences among HRF and HRV groups in image quality and diagnostic performance were found. A nonsignificant trend was found toward a lower specificity and PPV in patients with a high HRF or severe HRV when compared with low HRF or normal HRV in patients with a low calcium score (Agatston score <100). CONCLUSION DS spiral CT coronary angiography performed with adaptive ECG pulsing results in preserved diagnostic image quality and performance independent of HRF or HRV at the cost of limited dose reduction in arrhythmic patients.

Diagnostic performance of coronary CT angiography by using different generations of multisection scanners: single-center experience.

PURPOSE To retrospectively compare sensitivity and specificity of four generations of multidetector computed tomographic (CT) scanners for diagnosing significant (>or=50%) coronary artery stenosis, with quantitative conventional coronary angiography as reference standard. MATERIALS AND METHODS The institutional review board approved this study. All patients consented to undergo CT studies prior to conventional coronary angiography, after they were informed of the additional radiation dose, and to the use of their data for future retrospective research. Two hundred four patients (157 men, 47 women; mean age, 58 years +/- 11 [standard deviation]), classified in four groups of 51 patients each, underwent coronary CT angiography with four-section, first- and second-generation 16-section, and 64-section CT scanners. Patients in sinus rhythm scheduled for conventional coronary angiography (stable angina, atypical chest pain) were included. Patients with bypass grafts and stents were excluded. Two readers unaware of results of conventional coronary angiography evaluated CT scans. Coronary artery segments of 2 mm or larger in diameter were included for comparative evaluation with quantitative coronary angiography. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of significant stenoses (>or=50% luminal diameter reduction) were calculated. RESULTS Image quality was rated poor for the following percentages of coronary artery segments: 33.1% at four-section CT, 14.4% at first-generation 16-section CT, 6.3% at second-generation 16-section CT, and 2.6% at 64-section CT. Sensitivity, specificity, PPV, and NPV, respectively, were as follows: 57%, 91%, 60%, and 90% at four-section CT; 90%, 93%, 65%, and 99% at first-generation 16-section CT; 97%, 98%, 87%, and 100% at second-generation 16-section CT; and 99%, 96%, 80%, and 100% at 64-section CT. Diagnostic performance of four-section CT was significantly poorer than that of second-generation 16-section CT (odds ratio = 4.57) and 64-section CT (odds ratio = 2.89). CONCLUSION Diagnostic performance of coronary CT angiography varies among scanners of different generations. Earlier-generation scanners (four sections) had significantly poorer performance; performance of 16- compared with 64-section CT scanners showed progressive, although not significant, improvement.

Learning Curve for Coronary CT Angiography: What Constitutes Sufficient Training?

PURPOSE To prospectively evaluate the effect of experience with coronary computed tomographic (CT) angiography on the capability to detect coronary stenoses of 50% or more. MATERIALS AND METHODS The institutional review board approved the study protocol. All patients gave consent to undergo CT angiography before conventional coronary angiography after being informed of the additional radiation dose. They also consented to the use of their data for future research. Three radiologists and one cardiologist inexperienced with coronary CT angiography attended this institutions cardiac CT unit for a 1-year fellowship. Fellows were involved in the acquisition and reading of 12-15 coronary CT angiograms per week (about 600 per year). To assess the progression in diagnostic performance, fellows (readers) independently read 50 CT angiographic test cases in patients who also underwent conventional coronary angiography. Cases were repeatedly assigned in random order at baseline and at 4, 8, 26, and 52 weeks. The same cases were examined by two experts in consensus. Sensitivity, specificity, and diagnostic odds ratios (DORs) were calculated and compared with conventional coronary angiography as the reference standard. RESULTS Respective reader ranges for sensitivity, specificity, and DOR were 33%-72%, 70%-94%, and 3.8-8.1 at baseline; 43%-80%, 71%-88%, and 8.8-15.2 after 6 months; and 66%-75%, 87%-92%, and 14.7-25.8 after 1 year. For expert physicians, respective results were 95%, 93%, and 255.9. Between baseline and 6 months, readers 1-3 showed nonsignificantly improved sensitivities, while specificities remained similar. Reader 4 showed significantly improved specificity, while sensitivity remained similar; all readers nonsignificantly improved DORs. Between baseline and 1 year: readers 1 and 2 significantly improved sensitivity but not specificity; reader 4 significantly improved specificity but not sensitivity; readers 1, 2, and 4 improved DOR significantly; reader 3 nonsignificantly improved sensitivity, specificity, and DOR. CONCLUSION Increasing experience with coronary CT angiography improved the diagnostic performance of inexperienced physicians. However, acquiring expertise in coronary CT angiography was slow and may take more than 1 year.

Plaque and shear stress distribution in human coronary bifurcations: a multislice computed tomography study

AIMS Early atherosclerosis is located in low wall shear-stress (WSS) regions, however plaques are also found in the high WSS sensing flow divider walls of coronary bifurcations. We assessed the plaque distribution and morphology near bifurcations non-invasively with 64-slice computed tomography in relation to the WSS distribution. METHODS AND RESULTS We inspected 65 cross-sections near coronary bifurcations for the presence of plaque. Cross-sections were divided into four equal parts, which we numbered according to expected levels of WSS, with part I the lowest WSS (outer wall) and increasing WSSs in part II (inner bend), III (outer bend) and IV (flow divider). Of the cross-sections 88% had plaque. Of all parts I, 72% contained plaque. This was 62%, 38% and 31% in parts II, III and IV. In cross-sections with only 1 or 2 parts inflicted, plaque was found in part I and/or II in 94%. In 93% of the cross-sections with the flow divider inflicted, parts I and/or II were also inflicted. Plaque was never found exclusively in the flow divider part IV. CONCLUSIONS We demonstrated that plaque is mostly present in low WSS regions, whereas plaque in high WSS regions is accompanied by plaque in adjacent low WSS regions. It is therefore plausible that plaque grows from the outer wall (low WSS) of the bifurcation towards the flow divider (high WSS).

64-slice Computed Tomography Coronary Angiography in Patients with Non-ST Elevation Acute Coronary Syndrome

Background: A high diagnostic accuracy of 64-slice CT coronary angiography (CTCA) has been reported in selected patients with stable angina pectoris, but only scant information is available in patients with non-ST elevation acute coronary syndrome (ACS). Objectives: To study the diagnostic performance of 64-slice CTCA in patients with non-ST elevation ACS. Patients and methods: 64-slice CTCA was performed in 104 patients (mean (SD) age 59 (9) years) with non-ST elevation ACS. Two independent, blinded observers assessed all coronary arteries for stenosis, using conventional quantitative angiography as a reference. Coronary lesions with ⩾50% luminal narrowing were classified as significant. Results: Conventional coronary angiography demonstrated the absence of significant disease in 15% (16/104) of patients, and the presence of single-vessel disease in 40% (42/104) and multivessel disease in 44% (46/104) of patients. Sensitivity for detecting significant coronary stenoses on a patient-by-patient analysis was 100% (88/88; 95% CI 95 to 100), specificity 75% (12/16; 95% CI 47 to 92), and positive and negative predictive values were 96% (88/92; 95% CI 89 to 99) and 100% (12/12; 95% CI 70 to 100), respectively. Conclusion: 64-slice CTCA has a high sensitivity to detect significant coronary stenoses, and is reliable to exclude the presence of significant coronary artery disease in patients who present with a non-ST elevation ACS.

Diagnostic accuracy of 64-slice computed tomography coronary angiography in a large population of patients without revascularisation: registry data and review of multicentre trials.

PurposeThis study was undertaken to evaluate the diagnostic accuracy of computed tomography coronary angiography (CT-CA) for the detection of significant coronary artery stenosis (≥50% lumen reduction) compared with conventional coronary angiography (CCA) in a registry and to review major multicentre trials.Materials and methodsA total of 1,372 patients (882 men, 490 women; mean age 59.3±11.9 years) in sinus rhythm were studied with CT-CA (64-slice technology) and CCA. The diagnostic accuracy of CT-CA was evaluated against quantitative CCA as a reference standard for coronary artery stenosis. Positive and negative likelihood ratios and inter- and intraobserver agreement were calculated.ResultsThe prevalence of disease was 53%. CCA demonstrated the absence of significant coronary artery disease in 46.6% (639/1372), single-vessel disease in 24.7% (337/1372) and multivessel disease in 28.9% (396/1372) of patients. In per-patient analysis sensitivity, specificity and positive and negative predictive value of CT-CA were 99% [confidence interval (CI) 97–99], 92% (CI 89–94), 94% (CI 91–95) and 99% (CI 97–99), respectively. Per-patient and per-segment likelihood ratios (LR+=12.4 and LR−=0.011; LR+=18.3 and LR−=0.064, respectively), were good. Inter- and intraobserver variability was 0.78 and 0.85, respectively.ConclusionsCT-CA is a reliable diagnostic modality both in terms of sensitivity and negative predictive value. Differences in trial results are also due to the different parameters used for patient inclusion.RiassuntoObiettivoObiettivo di questo lavoro è stato valutare l’accuratezza diagnostica dell’angiografia coronarica non invasiva con tomografia computerizzata (CT-CA) a 64 strati nell’individuazione delle stenosi coronariche significative (riduzione del lume coronarico ≥50%) confrontata con la coronarografia convenzionale (CAG) in un registro e revisionare i risultati dei trials multicentrici.Materiali e metodiSono stati studiati 1372 pazienti (882 uomini, 490 donne, età media 59,3±11,9 anni) in ritmo cardiaco sinusale con CT-CA (tecnologia 64 strati) e CAG. La CT-CA è stata eseguita secondo i protocolli comunemente utilizzati. L’accuratezza diagnostica è stata calcolata utilizzando la CAG come standard di riferimento. Sono state calcolate l’accuratezza diagnostica, i likelihood ratio positivo e negativo (LR+ e LR−) e la variabilità inter- ed intra-osservatore.RisultatiLa prevalenza di malattia nella popolazione era del 53%. Il 46,6% (639/1372) mostravano coronarie indenni o con lesioni che determinavano stenosi <50%, il 24,7% (337/1372) mostrano malattia critica di un solo vaso, ed il 28,9% (396/1372) dei pazienti mostrava coronaropatia critica multivasale. Nell’analisi per paziente la sensibilità, specificità, valore predittivo positivo e negativo della CT-CA sono risultati 99% (intervallo di confidenza [IC] 97–99), 92% (IC 89–94), 94% (IC 91–95), 99% (IC 97–99), rispettivamente. I likelihood ratio per paziente (LR+=12,4 e LR−=0,011) e per segmento (LR+=18,3 e LR−=0,064), sono risultati ottimali. Le variabilità inter- ed intra-osservatore sono risultate 0,78 e 0,85, rispettivamente.ConclusioniLa CT-CA è una metodica diagnostica affidabile sia per l’elevata sensibilità che per l’elevato valore predittivo negativo. I risultati dei trials sono variabili anche alla luce dei parametri principali di inclusione utilizzati.