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

The utility and effectiveness of the newer generation high-resolution coronary computed tomography angiography in the evaluation of coronary in-stent restenosis

BACKGROUND

The importance of coronary computerized tomography angiography (CCTA) in detecting native coronary artery stenosis has been established. However, very few studies investigated the efficacy of CCTA in the assessment of in-stent restenosis (ISR) in symptomatic patients after percutaneous coronary intervention (PCI).

AIM OF THE STUDY

To evaluate the value of CCTA in diagnosing ISR.

METHODS

We included 102 symptomatic patients with stable angina, presented one to five years after PCI. All patients were subjected to CCTA, and the patients with significant coronary artery disease were directed for invasive coronary angiography (ICA). CCTA results were compared to ICA as the gold standard tool for detecting ISR.

RESULTS

In 88 (86.3 %) patients, CCTA could successfully exclude ISR together with the ICA (true negative), but in two cases, ICA detected an ISR which was not detected by CCTA (false negative). In eight patients, CCTA detected ISR. These were confirmed by ICA (true positive) and revascularized. In four patients (3.9 %), ISR was suspected by CCTA but excluded by ICA (false positive). In our study, according to the agreement of CCTA in detection or exclusion of ISR, sensitivity, specificity, PPV, NPV and accuracy were 80.0 %, 96.65 %, 66.67 %, 97.78 %, 94.12 %, respectively. These results were statistically significant (P < 0.001).

CONCLUSIONS

In up to 86 % of symptomatic patients with previous PCI, ISR was accurately excluded by CCTA. CCTA was demonstrated by this study as a high yielding tool for ruling out ISR, abolishing the need for more invasive and expensive diagnostic procedures.

[Evaluation of Noise Properties at Nonuniformity Area and Resolution Properties of CT Image Using Iterative Reconstruction Method]

PURPOSE

The purpose of this study was to investigate the resolution property and the noise properties at the nonuniformity area in the slice plane of iterative reconstruction (IR)-CT image.

METHODS

CT images of a phantom with nonuniformity areas including multiple contrast (medium, high, and ultra-high contrast) signals were acquired at various scan dose conditions and reconstructed with different iterative intensity levels. The noise properties at the nonuniformity and the uniformity areas were evaluated by measuring normalized noise power spectra (nNPSs) using subtracted images from sequential scanning data under the same scan conditions. We investigated the relationship between the noise properties and the resolution properties evaluated by measuring task transfer function (TTF) using multiple contrast signals before the subtraction.

RESULTS

There was a correlation between the nNPS at the nonuniformity area and the TTF because the nNPS values at high spatial frequency were increased with superior TTF (higher dose, mild iterative intensity, and higher contrast level). The differences in the high spatial frequency component of the nNPSs among each task were decreased with the inferior TTF tasks.

CONCLUSION

We conclude that the noise properties in the slice plane at the nonuniformity area and resolution properties of the IR-CT image were correlated similar to image quality properties of the linear imaging system due to the dependence of the nNPSs curve on the TTF value under each task.

Bioimpedance Sensing of Implanted Stent Occlusions: Smart Stent

Coronary artery disease is one of the most common diseases in developed countries and affects a large part of the population of developing countries. Preventing restenosis in patients with implanted stents is an important current medical problem. The purpose of this work is to analyse the viability of bioimpedance sensing to detect the formation of atheromatous plaque in an implantable stent. Simulations in COMSOL Multiphysics were performed to analyse the performance of the proposed bioimpedance sensing system, based on the Sheffield technique. Both non-pathological and pathological models (with atheromatous plaque), including the flow of blood were considered. Simulations with the non-pathological model showed a homogeneous distribution of the measured current intensity in the different electrodes, for every configuration. On the other hand, simulations with the pathological model showed a significant decrease of the measured current intensity in the electrodes close to the simulated atheromatous plaque. The presence of the atheromatous plaque can, therefore, be detected by the system with a simple algorithm, avoiding the full reconstruction of the image and the subsequent computational processing requirements.

Scoring model to predict low image quality of drug-eluting stent evaluated by computed tomography coronary angiography

Evaluation of in-stent restenosis (ISR) by computed tomography coronary angiography (CTCA) is less invasive but often impossible. We aimed to create a scoring model for predicting which drug-eluting stents (DES) cannot be evaluated with CTCA. We enrolled 757 consecutive implanted DES assessed with CTCA. Non-diagnostic evaluation was defined as poor/not evaluative by two different observers. These stents were randomly divided into a derivation (n = 379) and validation (n = 378) group. In the derivation group, we assessed predictors using logistic regression analysis and created a scoring model that would stratify non-diagnostic evaluation of DES-ISR. The validity of this scoring model was evaluated in the validation group using receiver-operating characteristic analysis. The percentage of non-diagnostic stents was 19/21% in the derivation/validation group (p = 0.71). Non-diagnostic evaluation was independently associated with implanted stent diameter (2.25-2.5. vs. 2.5-3 vs. > 3.0 mm), severe calcification, stent-in-stent lesion, and type of DES (stainless vs. CoCr vs. PtCr) in the derivation group. The predicting system of implanted DES non-diagnostic by CTCA (PIDENT) for non-diagnostic evaluation, including these four baseline factors, was derived (C-statistic = 0.86 in derivation group, cutoff: 8 points). The PIDENT score had a high predictive value for non-diagnostic DES in the validation model (C-statistic = 0.87, sensitivity 86%, specificity 74%, cutoff 8 points, p < 0.001). The PIDENT score, consisting of baseline characteristics including implanted stent diameter, severe calcification, stent-in-stent lesion, and type of DES, could identify non-diagnostic evaluation of DES-ISR with CTCA. The PIDENT score was valuable in reducing nonevaluable and meaningless CTCA for DES-ISR.

Drug-eluting balloon: is it useful?

BACKGROUND

Coronary artery disease is one of the major issues in the medical world around the globe. The prevalence tends to increase. The use of coronary intervention is one of the ways often used in the management of coronary artery disease due to its satisfying result from earlier studies. Nowadays, there are several different techniques in coronary intervention: balloon vs stent.

MAIN BODY

The stent-based vascular interventions are increasingly being used over balloon-based coronary intervention. However, revascularization intervention using stent often have undesirable long-term effects compared to balloon. Besides, stent-based interventions are also considered more expensive, use more complicated techniques, and use more drug regimens. On the other hand, percutaneous coronary intervention techniques using balloons coated by anti-proliferation drugs have begun to be glimpsed by many interventionists. Studies have found many benefits that cannot be given by stent-based intervention therapy.

CONCLUSIONS

Angioplasty using percutaneous coronary intervention techniques reveals satisfying result compared to conservative medical treatment. The indication and technique of percutaneous coronary intervention is still evolving until now. Currently, percutaneous coronary intervention using stent, either bare-metal stent or drug-eluting stent, is preferred by interventionist. Nevertheless, recent clinical trial favors the using of drug-eluting balloon for percutaneous coronary intervention in terms of both clinical outcome and complication in several scenarios.

Health Care Monitoring and Treatment for Coronary Artery Diseases: Challenges and Issues

In-stent restenosis concerning the coronary artery refers to the blood clotting-caused re-narrowing of the blocked section of the artery, which is opened using a stent. The failure rate for stents is in the range of 10% to 15%, where they do not remain open, thereby leading to about 40% of the patients with stent implantations requiring repeat procedure within one year, despite increased risk factors and the administration of expensive medicines. Hence, today stent restenosis is a significant cause of deaths globally. Monitoring and treatment matter a lot when it comes to early diagnosis and treatment. A review of the present stent monitoring technology as well as the practical treatment for addressing stent restenosis was conducted. The problems and challenges associated with current stent monitoring technology were illustrated, along with its typical applications. Brief suggestions were given and the progress of stent implants was discussed. It was revealed that prime requisites are needed to achieve good quality implanted stent devices in terms of their size, reliability, etc. This review would positively prompt researchers to augment their efforts towards the expansion of healthcare systems. Lastly, the challenges and concerns associated with nurturing a healthcare system were deliberated with meaningful evaluations.

CT Angiography of Stented Carotid Arteries: Comparison with Doppler Ultrasonography

Purpose:

To determine whether computed tomographic angiography (CTA) is a feasible modality for assessing stented carotid arteries and whether in-stent restenosis based on CTA concurs with ultrasonography (US).

Methods:

A retrospective review was conducted of 37 follow-up CTA and US images from 27 patients (23 men; median age 70 years, range 56–77) who received 34 nitinol carotid stents. CTA and US images were compared with respect to assessability and percent stenosis. Both visual estimation (≥50% or not) and the NASCET method were used to determine percent stenosis in CTA images. For US, a determination of ≥50% stenosis was based on peak systolic velocity (≥200 cm/s) and an internal carotid artery to common carotid artery ratio ≥2.5. Percent stenosis values by CTA were also compared to values (n=7, 21%) determined by catheter angiography.

Results:

CTA and US images were “totally assessable” in 27 (73%) and 15 (41%), “totally non-assessable” in 0 (0%) and 3 (8%), and “partially assessable” in 10 (27%) and 19 (51%), respectively. Assessability of CTA images was equal to or better than that of US images in 33 (89%). The percent stenoses by CTA and US were comparable in 20 cases. CTA found ≥50% stenosis using the NASCET method in 4 of 20 stents; none of these showed ≥50% stenosis by visual estimation of CTA or by spectral Doppler US. Compared with catheter angiography, CTA overestimated percent stenosis from 34% to 66% (mean 53%). US confirmed 2 angiographically proven restenoses, but CTA identified only 1.

Conclusion:

CTA provides better image quality for stented carotid arteries than US, but it might be inferior to US in determining restenosis in assessable cases. Therefore, CTA is likely to be an alternative to US in cases of non-assessability. A large-scale study including more restenosis cases is warranted to reveal which modality is more reliable for diagnosis of restenosis.

Cardiac magnetic resonance imaging and computed tomography in ischemic cardiomyopathy: an update

Ischemic cardiomyopathy is one of the major health problems worldwide, representing a significant part of mortality in the general population nowadays. Cardiac magnetic resonance imaging (CMRI) and cardiac computed tomography (CCT) are noninvasive imaging methods that serve as useful tools in the diagnosis of coronary artery disease and may also help in screening individuals with risk factors for developing this illness. Technological developments of CMRI and CCT have contributed to the rise of several clinical indications of these imaging methods complementarily to other investigation methods, particularly in cases where they are inconclusive. In terms of accuracy, CMRI and CCT are similar to the other imaging methods, with few absolute contraindications and minimal risks of adverse side-effects. This fact strengthens these methods as powerful and safe tools in the management of patients. The present study is aimed at describing the role played by CMRI and CCT in the diagnosis of ischemic cardiomyopathies.

[Coronary stent evaluation with cardiac CT: Literature review]

Since the introduction of the 64-generation scanners, the accuracy and robustness of the diagnosis of coronary artery disease has progressed. The main advantage of cardiac CT is the exclusion of coronary artery disease by its excellent negative predictive value. Currently, cardiac CT applications extend thanks to innovations both in terms of technological development systems scanner or stents implanted. This is a literature review of stent evaluation with cardiac CT.

Multidetector computed tomography angiography to evaluate the subscapular arterial tree

OBJECTIVE

The subscapular artery has an important place in reconstructive surgery. The major pedicles of several different flaps used widely in reconstructive surgery take their roots from this arterial tree. This study aimed to provide anatomical data relating to these vessels through the use of multidetector computed tomography angiography (MDCTA) and to evaluate the clinical utility of MDCTA tool prior to surgery.

METHODS AND MATERIALS

A radiological evaluation using a MDCTA was made of the bilateral subscapular arteries and branches measuring >0.5 mm in diameter that could be sufficiently identified as vascular structures in 92 patients (44 men and 48 women) with pneumonia, pleural effusion, lung masses, or nodules for which a thoracic MDCTA was requested for the purpose of diagnosis.

RESULTS

The mean diameter of the subscapular artery origin was 3.86 ± 0.60 mm on the left and 3.93 ± 0.62 mm on the right. The mean diameter of the circumflex scapular artery origin was 2.41 ± 0.37 mm on the left and 2.44 ± 0.39 mm on the right. The mean diameter of the thoracodorsal artery origin was 2.29 ± 0.27 mm on the left and 2.31 ± 0.29 mm on the right. Mean length of the circumflex scapular artery was 46.34 ± 9.41 mm on the left and 46.10 ± 8.81 mm on the right. Mean length of the latissimus dorsi branch of the thoracodorsal artery from the origin of the subscapular artery was 110.11 ± 17.42 mm on the left and 112.21 ± 14.60 mm on the right. Mean length of the serratus anterior branch was 124.25 ± 19.00 mm on the left and 120.84 ± 15.67 mm on the right. No differences were detected between the left and right sides or between sexes. Doubled circumflex scapular arteries were found in 4.3% of patients, and the circumflex scapular artery branched directly off the axillary artery in 3.2% of patients.

CONCLUSION

This study showed that MDCTA is a highly valuable, non-invasive imaging tool for studying vascular anatomy and detecting variations in vascular structure during preoperative planning, thus enhancing surgical safety.

Comparative analysis between 64- and 320-slice spiral computed tomography in the display of coronary artery stents and diagnosis of in-stent restenosis

The aim of the present study was to compare the accuracy of 64-multi-slice spiral computed tomography (64-MSCT) and 320-MSCT in the display of coronary artery stents and diagnosis of in-stent restenosis. The data collected from the 64- and 320-MSCT coronary angiography of 93 patients following coronary artery stent implantation were retrospectively analyzed. The 64-MSCT group comprised 30 cases with 57 stents and the 320-MSCT group comprised 63 cases with 93 stents. The image quality, heart rate of the patients and the radiation effective dose (ED) they were subjected to, were compared. Furthermore, the diagnostic abilities of 64-and 320-MSCT coronary angiography for in-stent restenosis were evaluated using invasive coronary angiography results as the gold standards. Statistically significant differences were observed in the heart rate and ED of the patients from the two groups (P<0.05), but no significant difference was identified in the accuracy index (P>0.05). The sensitivity, specificity, positive and negative predictive value and accuracy of the 64-MSCT group were found to be 100% (7/7), 93.94% (31/33), 77.78% (7/9), 100% (31/31) and 95% (38/40), respectively, and those in the 320-MSCT group were found to be 100% (16/16), 95.89% (70/73), 84.21% (16/19), 100% (70/70) and 96.63% (86/89), respectively. The present findings suggest that both 64-MSCT and 320-MSCT can be used for follow-up and curative effect evaluation following coronary stent implantation; however, 320-MSCT has fewer requirements of the patients' heart rate and uses a lower radiation dose.

Geographic miss with aorto-ostial coronary stent implantation: insights from high-resolution coronary computed tomography angiography

AIMS

Accurate positioning of aorto-ostial coronary stents is challenging. Coronary CT angiography (CCTA) allows detailed imaging of the coronary sinuses and implanted stents. We utilised CCTA to evaluate the accuracy of aorto-ostial stenting and to assess the efficacy of conventional angiography for guiding these procedures.

METHODS AND RESULTS

We analysed 256-row CCTA scans in 23 patients who had undergone aorto-ostial stenting. Optimal stent positioning was defined as presence of the entire circumference of the proximal stent edge within an aorto-ostial landing zone (AOLZ), located within 1 mm of the aorto-ostial plane. Geographic miss was diagnosed when at least a section of the proximal stent edge was located proximal or distal to the AOLZ. CCTA findings were compared with review of the conventional two-dimensional implantation angiogram (two experienced operators). By CCTA, the entire circumference of the proximal stent edge was located within the AOLZ in only three (13%) cases, with geographic miss in the remainder. Conversely, conventional coronary angiography suggested complete lesion coverage to be present in 95% of cases and optimal location of the proximal stent edge within the AOLZ in 76%.

CONCLUSIONS

Geographic miss was common in aorto-ostial stenting and was underestimated by conventional two-dimensional angiography.

[Cardiac CT: new applications]

Since the introduction of the 64-generation scanners, the accuracy and robustness of the diagnosis of coronary artery disease has progressed. The main advantage of cardiac CT is the exclusion of coronary artery disease by its excellent negative predictive value. Currently, cardiac CT applications extend thanks to innovations both in terms of technological development systems scanner or stents implanted, that the evolution of surgical procedures such as TAVI.

Multidetector-row computed tomography for noninvasive coronary imaging

Computed tomography (CT) permits cross-sectional imaging of the heart. Temporal and spatial resolutions of the technique have been insufficient to cover the heart without motion artefacts until the recent advent of multidetector systems with more than 16 detector rows. The modality is now suited for noninvasive imaging of the coronary arteries, producing detailed morphologic images of the entire coronary tree with upto 0.4 mm of spatial resolution, within a single short breath-hold duration. CT imaging goes beyond the delineation of the coronary lumen as provided by selective invasive angiography; the plaque burden of the coronary artery wall can be visualized directly, utilizing soft-tissue contrast and a high sensitivity even for the small calcifications that are present in hard plaque formations. Therefore, CT combines elements of catheterization angiography for lumen imaging and of intravascular ultrasound imaging for coronary wall imaging. However current CT technology is not yet able to compete with the temporal or spatial resolution of catheterization angiography nor does it provide the detailed spatial or contrast resolution of intravascular ultrasound imaging. At present, its use is therefore restricted to complementing the invasive modalities in appropriate indications. Although CT entails significantly less risk than the invasive procedures, the risks of radiation dose exposure and contrast agent application are not negligible. In the foreseeable future, if the current rate of technological advancement continues, CT may replace the invasive modalities in routine care for diagnostic purposes.

Advances in the noninvasive evaluation of coronary artery disease with multislice computed tomography

Current noninvasive detection of coronary artery disease (CAD) is based on the demonstration of ischemia using stress-rest imaging, which is an indirect way of identifying CAD by demonstration of the hemodynamic consequences, rather than direct visualization of the obstructive lesions in the coronary arteries. Multislice computed tomography (MSCT) has recently emerged as an extremely rapidly developing noninvasive imaging modality, which allows anatomical imaging of the coronary arteries or noninvasive coronary angiography. In addition, total plaque burden, plaque morphology and (to some extent) plaque constitution can be assessed by MSCT. The technique also provides information on resting left ventricular systolic function, and possibly resting perfusion. Ideally, stress function and perfusion should also be evaluated, since this would allow detection of ischemia and would complete the picture of CAD. However, this is not routinely performed, since sequential acquisitions are associated with high radiation doses and thus pose a limitation for cardiovascular applications of MSCT. It is anticipated that, with a reduction in radiation, MSCT may become an important player in the diagnostic and prognostic work-up of patients with known or suspected CAD.

CT Imaging of Coronary Stents: Past, Present, and Future

Coronary stenting became a mainstay in coronary revascularization therapy. Despite tremendous advances in therapy, in-stent restenosis (ISR) remains a key problem after coronary stenting. Coronary CT angiography evolved as a valuable tool in the diagnostic workup of patients after coronary revascularization therapy. It has a negative predictive value in the range of 98% for ruling out significant ISR. As CT imaging of coronary stents depends on patient and stent characteristics, patient selection is crucial for success. Ideal candidates have stents with a diameter of 3 mm and more. Nevertheless, even with most recent CT scanners, about 8% of stents are not accessible mostly due to blooming or motion artifacts. While the diagnosis of ISR is currently based on the visual assessment of the stent lumen, functional information on the hemodynamic significance of in-stent stenosis became available with the most recent generation of dual source CT scanners. This paper provides a comprehensive overview on previous developments, current techniques, and clinical evidence for cardiac CT in patients with coronary artery stents.

A systematic review of radiation dose associated with different generations of multidetector CT coronary angiography

The purpose of this paper is to perform a systematic review on radiation dose reduction in coronary computed tomography (CT) angiography that is done using different generations of multidetector CT (MDCT) scanners ranging from four-slice to 320-slice CTs, and have different dose-saving techniques. The method followed was to search for references on coronary CT angiography (CTA) that had been published in English between 1998 and February 2011. The effective radiation dose reported in each study based on different generations of MDCT scanners was analysed and compared between the types of scanners, gender, exposure factors and scanning protocols. Sixty-six studies were eligible for inclusion in this analysis. The mean effective dose (ED) for MDCT angiography with retrospective electrocardiogram (ECG) gating without use of any dose-saving protocol was 6.0 ± 2.8, 10.4 ± 4.90 and 11.8 ± 5.9 mSv for four-slice, 16-slice and 64-slice CTs, respectively. More dose-saving strategies were applied in recent CT generations including prospective ECG-gating protocols, application of lower tube voltage and tube current modulation to achieve a noteworthy dose reduction. Prospective ECG-gating protocol was increasingly used in 64, 125, 256 and 320 slices with corresponding ED of 4.1 ± 1.7, 3.6 ± 0.4, 3.0 ± 1.9 and 7.6 ± 1.6 mSv, respectively. Lower tube voltage and tube current modulation were widely applied in 64-slice CT and resulted in significant dose reduction (P < 0.05). This analysis has shown that dose-saving strategies can substantially reduce the radiation dose in CT coronary angiography. The fact that more and more clinicians are opting for dose-saving strategies in CT coronary angiography indicates an increased awareness of risks associated with high radiation doses among them.

Recurrent angina after coronary angioplasty: mechanisms, diagnostic and therapeutic options

Recurrent angina in patients who underwent percutaneous coronary intervention is defined as recurrence of chest pain or chest discomfort. Careful assessment is recommended to differentiate between non-cardiac and cardiac causes. In the case of the latter, recurrent angina occurrence can be related to structural ('stretch pain', in-stent restenosis, in-stent thrombosis, incomplete revascularization, progression of coronary atherosclerosis) or functional (coronary micro-vascular dysfunction, epicardial coronary spasm) causes. Even though a complete diagnostic algorithm has not been validated, ECG exercise testing, stress imaging and invasive assessment of coronary blood flow and coronary vaso-motion (i.e. coronary flow reserve, provocation testing for coronary spasm) may be required. When repeated coronary revascularization is not indicated, therapeutic approaches should aim at targeting the underlying mechanism for the patient's symptoms using a variety of drugs currently available such as beta-blockers, calcium-channel blockers, ivabradine or ranolazine.

Integrative computed tomographic imaging of cardiac structure, function, perfusion, and viability

Recent advances in multidetector-row computed tomography (MDCT) technology have created new opportunities in cardiac imaging and provided new insights into a variety of disease states. Use of 64-slice coronary computed tomography angiography has been validated for the evaluation of clinically relevant coronary artery stenosis with high negative predictive values for ruling out significant obstructive disease. This technology has also advanced the care of patients with acute chest pain by simultaneous assessment of acute coronary syndrome, pulmonary embolism, and acute aortic syndrome ("triple rule out"). Although MDCT has been instrumental in the advancement of cardiac imaging, there are still limitations in patients with high or irregular heart rates. Newer MDCT scanner generations hold promise to improve some of these limitations for noninvasive cardiac imaging. The evaluation of coronary artery stenosis remains the primary clinical indication for cardiac computed tomography angiography. However, the use of MDCT for simultaneous assessment of coronary artery stenosis, atherosclerotic plaque formation, ventricular function, myocardial perfusion, and viability with a single modality is under intense investigation. Recent technical developments hold promise for accomplishing this goal and establishing MDCT as a comprehensive stand-alone test for integrative imaging of coronary heart disease.

In vivo evaluation of stent patency by 64-slice multidetector CT coronary angiography: shall we do it or not?

The diagnostic performance of in-stent restenosis (ISR) by 64-slice multidetector CT coronary angiography (CTCA) has been reported to be influenced by multiple factors. We evaluated individual factors (stent diameter, material and strut thickness) and therefore determined the proper population for follow-up by using this modality. A total of 171 stents were evaluated in 83 consecutive patients with stents imaged with CTCA and conventional coronary angiography. The stent diameter ranged from 2.25 mm to 4.5 mm. 2 models of stainless steel (Taxus Liberte (Boston Scientific, US), 56 stents and Cypher Select (Cordis, US), 34 stents) and 2 models of cobalt alloy (Endeavor (Medtronic, US), 33 stents and Firebird2 (MicroPort, China), 48 stents) were included. By comparing to conventional coronary angiography, the image quality and diagnostic accuracy for ISR were evaluated. The image quality of Taxus, Endeavor and Firebird are markedly better than Cypher in large caliber group (≧3.0 mm) (P < 0.001). Except for Cypher, all other stents with diameter ≧3.0 mm showed excellent diagnostic accuracy (sensitivity 100%, specificity 94.4-96% whereas stents with diameter <3.0 mm had poor diagnostic accuracy (sensitivity 100%, specificity 33.3-70%). Cypher is the stent with thickest strut in our study, and showed reduced image quality and diagnostic accuracy in all stent size, due to large number of unassessable stents. Among 16 binary ISR, 12 lesions were correctly diagnosed by CTCA while the other 4 lesions were unassessable. The main reason for low specificity in small caliber group is the large number of unassessable stents. CTCA has high diagnostic accuracy to identify ISR in selected stents with a diameter of ≧3.0 mm.

Diagnostic accuracy of 320-row multidetector computed tomography coronary angiography to noninvasively assess in-stent restenosis

OBJECTIVES

Percutaneous coronary intervention with stent implantation is routinely performed to treat patients with obstructive coronary artery disease. However, thus far, noninvasive assessment of in-stent restenosis has been challenging. Recently, 320-row multidetector computed tomography coronary angiography (CTA) was introduced, allowing volumetric image acquisition of the heart in a single heart beat or gantry rotation. The aim of this study was to evaluate the diagnostic performance of 320-row CTA in the evaluation of significant in-stent restenosis. Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach.

MATERIALS AND METHODS

The population consisted of patients with previous coronary stent implantation who were clinically referred for cardiac evaluation because of recurrent chest pain and who underwent both CTA and ICA. CTA studies were performed using a 320-row CTA scanner with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 350 milliseconds. Tube voltage and current were adapted to body mass index and thoracic anatomy. The entire heart was imaged in a single heart beat, with a maximum of 16-cm craniocaudal coverage. During the scan, the ECG was registered simultaneously for prospective triggering of the data. First, CTA stent image quality was assessed using a 3-point grading scale: (1) good image quality, (2) moderate image quality, and (3) poor image quality. Subsequently, the presence of in-stent restenosis was determined on a stent and patient basis by a blinded observer. Significant in-stent restenosis was defined as >or=50% luminal narrowing in the stent lumen or the presence of significant stent edge stenosis. Overlapping stents were considered to represent a single stent. Results were compared with ICA using quantitative coronary angiography. In addition, CTA stent image quality and diagnostic accuracy were related to stent characteristics and heart rate during CTA image acquisition.

RESULTS

The population consisted of 53 patients (37 men, mean age: 65 +/- 13 years) with a total of 89 stents available for evaluation. ICA identified 12 stents (13%) with significant in-stent restenosis. A total of 7 stents (8%) were of nondiagnostic CTA stent image quality, and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 92%, 83%, 46%, and 98%, respectively on a stent basis. Five CTA studies (9%) were of nondiagnostic quality for the evaluation of in-stent restenosis and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 100%, 81%, 58%, and 100%, respectively on a patient level. Stent diameter <3 mm as well as stent strut thickness >or=140 mum were associated with decreased CTA stent image quality and diagnostic accuracy. Heart rate during CTA acquisition and stent overlap were not associated with image degradation.

CONCLUSIONS

The present results show that 320-row CTA allows accurate noninvasive assessment of significant in-stent restenosis. However, stents with a large diameter and thin struts allowed better in-stent visualization than stents with a small diameter or thick struts. Consequently, noninvasive assessment of in-stent restenosis using CTA may be an attractive and feasible alternative particularly in carefully selected patients.

Diagnostic accuracy of 64-slice computed tomography coronary angiography for the detection of in-stent restenosis: a meta-analysis

BACKGROUND

We sought to evaluate the diagnostic accuracy of 64-slice multi-detector row computed tomography (MDCT) compared with invasive coronary angiography for in-stent restenosis (ISR) detection.

METHODS

MEDLINE, Cochrane library, and BioMed Central database searches were performed until April 2009 for original articles. Inclusion criteria were (1) 64-MDCT was used as a diagnostic test for ISR, with >50% diameter stenosis selected as the cut-off criterion for significant ISR, using invasive coronary angiography and quantitative coronary angiography as the standard of reference; (2) absolute numbers of true positive, false positive, true negative, and false negative results could be derived. Standard meta-analytic methods were applied.

RESULTS

Nine studies with a total of 598 patients with 978 stents included were considered eligible. On average, 9% of stents were unassessable (range 0-42%). Accuracy tests with 95% confidence intervals (CIs) comparing 64-MDCT vs invasive coronary angiography showed that pooled sensitivity, specificity, positive and negative likelihood ratio (random effect model) values were: 86% (95% CI 80-91%), 93% (95% CI 91-95%), 12.32 (95% CI 7.26-20.92), 0.18 (95% CI 0.12-0.28) for binary ISR detection. The symmetric area under the curve value was 0.94, indicating good agreement between 64-MDCT and invasive coronary angiography.

CONCLUSIONS

64-MDCT has a good diagnostic accuracy for ISR detection with a particularly high negative predictive value. However, still a relatively large proportion of stents remains uninterpretable. Accordingly, only in selected patients, 64-MDCT may serve as a potential alternative noninvasive method to rule out ISR.

Efficacy and safety of the computed tomography coronary angiography based approach for patients with acute chest pain at an emergency department: one month clinical follow-up study

To evaluate the safety and efficacy of the computed tomography coronary angiography (CTCA) for evaluation of acute chest pain in real world population, we prospectively enrolled 296 patients with acute chest pain at emergency department (ED) from November 2005 to February 2007. The patients were grouped based on the clinical information and CTCA result. The patients with a low risk profile and no significant coronary stenosis (>50%) in CTCA were discharged immediately (Group 1, n=103). On the other hand, the patients with an intermediate risk profile without significant stenosis were observed in ED for 24 hr (Group 2, n=104). The patients with significant stenosis underwent further coronary evaluation and management accordingly (Group 3, n=89). While no false negative case was found in Group 1, seven cases (6.73%) were found in Group 2, mostly during the observation period. In Group 3, there were 54 (60.67%) cases of acute coronary syndrome including 10 myocardial infarctions. The overall accuracy of CTCA for acute coronary syndrome was 88.5% (sensitivity), 85.1% (specificity), 60.7% (positive predictive value) and 96.6% (negative predictive value). In conclusion, clinical decision based on CTCA is safe and effective for low risk patients. Further validation is needed in patients with intermediate risk profile.

Noninvasive quantitative evaluation of coronary artery stent patency using 64-row multidetector computed tomography

BACKGROUND

Many studies have used multidetector computed tomography (MDCT) angiography to evaluate coronary stents qualitatively but not quantitatively.

OBJECTIVES

This study sought to validate a method of quantitatively evaluating stent patency by using 64-row compared with invasive coronary angiography (ICA) and to evaluate the stent size threshold of MDCT in detecting stent patency.

METHODS

Stented lesions (n=122) in 55 patients (age, 65+/-10 years; 90% men) who underwent both 64-row MDCT and ICA were studied. Density measurements in Hounsfield units (HUs) and stent diameters in millimeters were recorded in the stented segments, with the density of the ascending aorta (AO) taken as a reference. The ratio of the average of stent's proximal, middle, and distal densities to mean AO density was defined as the AS/AO HU. Threshold values for the detection of stent patency were examined by using receiver operator characteristic (ROC) curve analysis.

RESULTS

One hundred six of 122 stents were interpretable. By ICA, 24 stents were found to have in-stent restenosis (22 interpretable and 2 noninterpretable with MDCT). The ROC curve showed that the optimal cutoff value of AS/AO HU to predict stent patency on MDCT was 0.81 with sensitivity of 90.9%, specificity of 95.2%, and the optimal stent diameter cutoff value was > or = 2.5 mm with a sensitivity of 91.8% and a specificity of 93.8%.

CONCLUSION

With 64-row MDCT, coronary stent patency can be evaluated quantitatively with high sensitivity and specificity and with adequate diagnostic accuracy in stents > or = 2.5 mm in diameter.

Transitioning from 16-slice to 64-slice multidetector computed tomography for the assessment of coronary artery disease: are we really making progress?

BACKGROUND

Multidetector computed tomography (MDCT) has demonstrated promise in the noninvasive evaluation of coronary artery disease.

OBJECTIVE

To systematically review the literature regarding the improved diagnostic accuracy of 64-slice MDCT.

METHODS

An EMBASE, OVID, PubMed and Cochrane Library database search was performed using the key words 'computed tomography' matched with the terms 'coronary artery' or 'coronary angiography' to identify English-language articles examining MDCT cardiac imaging. Studies that compared 16-slice or 64-slice MDCT with catheter-based coronary angiography for the detection of coronary artery disease in nonrevascularized, poststent and post-coronary artery bypass graft patients were included. Data were pooled to obtain a weighted sensitivity, specificity and diagnostic accuracy for MDCT. Negative and positive predictive values, and likelihood ratios were calculated based on sensitivity and specificity.

RESULTS

Currently, 15 studies involving 1008 patients have examined the efficacy of 64-slice MDCT in the assessment of coronary artery stenosis (more than 50% luminal narrowing). In these studies, 64-slice MDCT has demonstrated a sensitivity (89%), specificity (96%) and diagnostic accuracy (95%) similar to that of 16-slice MDCT. However, 64-slice MDCT was able to assess 5% more coronary artery segments than 16-slice MDCT. In revascularized patients, MDCT can accurately assess both bypass graft occlusion and stenosis. The 64-slice MDCT is also capable of adequately detecting in-stent restenosis. Improvements in spatial and temporal resolution with 64-slice technology have decreased the occurrence of high attenuation and motion artefacts that plagued the previous generation of MDCT scanners.

CONCLUSION

MDCT offers an accurate assessment of the coronary arteries, stented arteries and bypass grafts. The improved accuracy and safety of MDCT may reduce the need for catheter-based coronary angiography.

[Clinical applications of computed tomography coronary angiography]

The clinical applications of computed tomography coronary angiography (CTCA) are constantly evolving. Initially employed to quantify coronary artery calcification, multidetector CT also makes it possible to evaluate the anatomy and anatomical variations of coronary circulation, rule out coronary disease, and follow up surgical and percutaneous revascularization procedures. Moreover, CTCA may potentially be useful to quantify ventricular function, characterize non-calcified atherosclerotic plaques, and analyze myocardial perfusion and viability, providing anatomical, morphological, and functional information in patients with suspected ischemic heart disease.

Comparison of feasibility and diagnostic accuracy of 64-slice multidetector computed tomographic coronary angiography versus invasive coronary angiography versus intravascular ultrasound for evaluation of in-stent restenosis

Noninvasive assessment of coronary in-stent restenosis (ISR) is clinically useful but 4- and 16-slice multidetector computed tomography is limited due to stent strut artifacts. We evaluated the feasibility and accuracy of 64-slice multidetector computed tomography in the diagnosis of ISR to validate its accuracy in ISR quantification and identify factors that may affect stent patency evaluability. One hundred patients with previously implanted coronary stents (n = 179) underwent 64-slice multidetector computed tomography followed by invasive coronary angiography. After multidetector computed tomography, each stent was classified as "evaluable" or "unevaluable." Obstructive ISR was visually and quantitatively determined in evaluable stents. Correlations between quantitative multidetector computed tomography and quantitative coronary angiography were estimated. In a subgroup, multidetector computed tomographic and intravascular ultrasound measurements were correlated. Feasibility of stent visualization was 95%. Thirty-four of 39 ISRs (87%) were correctly detected and localized by multidetector computed tomography. ISR was correctly ruled out for 77% (128 of 131) of remaining stented lesions. Sensitivity, specificity, and positive and negative predictive values of multidetector computed tomography for ISR identification were 87%, 98%, 92%, and 96%, respectively. There was good correlation between percent stenosis evaluated by multidetector computed tomography versus quantitative coronary angiography and intravascular ultrasound (r = 0.794, p <0.001, and r = 0.943, p <0.0001, respectively) and good reproducibility of multidetector computed tomographic measurements (interobserver coefficient k 0.81 for diameter and 0.79 for area). Heart rate, complexity of stenting procedure, stent diameter, and strut thickness were factors limiting feasibility and accuracy. In conclusion, 64-slice multidetector computed tomography provides reliable and reproducible noninvasive evaluation of coronary stent patency and quantification of ISR.

Coronary artery stent evaluation using a vascular model at 64-detector row CT: comparison between prospective and retrospective ECG-gated axial scans

Objective

We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans.

Materials and Methods

As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen.

Results

The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error.

Conclusion

The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Impact of 64-slice multidetector computed tomography on other diagnostic studies for coronary artery disease

BACKGROUND

The clinical role of cardiovascular multidetector computed tomography (CT) remains in evolution, and application varies widely. Understanding its impact on the utilization of other cardiovascular diagnostic modalities could help define best practices.

METHODS

Utilization of diagnostic testing was examined for the initial 1053 consecutive patients who underwent cardiovascular multidetector CT examinations after scanner installation in 2005. Yearly procedural volumes in the invasive catheterization and noninvasive stress laboratories were assessed before and after the introduction of multidetector CT.

RESULTS

Ninety-one patients (8.6%) of the 1053 required invasive diagnostic catheterization; of these, nearly half subsequently underwent percutaneous or surgical intervention. Diagnostic catheterization and interventional volumes maintained their previous rates of annual increase, while the volume of stress testing decreased once multidetector CT became available.

CONCLUSIONS

The major impact of multidetector CT in initial cardiovascular practice is on the need and frequency of stress testing, with far less impact on utilization of cardiac catheterization and coronary interventions.

Noninvasive assessment of coronary in-stent restenosis by dual-source computed tomography

Assessment of coronary artery stents using computed tomographic angiography has been challenging. The technology of dual-source computed tomography (DSCT) provides higher temporal resolution that may allow more accurate evaluation of coronary stents. This study evaluated the accuracy of DSCT for the assessment of coronary artery in-stent restenosis. A total of 112 patients with 150 previously implanted coronary stents (diameter > or = 3.0 mm) were examined using DSCT (Definition; Siemens Medical Solutions, Forchheim, Germany) before conventional coronary angiography. Each stent was classified as assessable or not assessable. All assessable stents were further classified for the absence or presence of in-stent restenosis (>50% diameter reduction) using DSCT, and results were compared with those using quantitative coronary angiography. Mean stent diameter was 3.27 +/- 0.35 mm. Fifteen of 80 stents (19%) with a diameter of 3.0 mm were not assessable, and all 70 stents >3.0 mm were assessable. DSCT correctly identified 16 of 19 in-stent restenoses in 135 assessable stents, as well as the absence of in-stent restenosis in 110 of 116 stents (sensitivity 84%, specificity 95%, positive predictive value 73%, and negative predictive value 97% in assessable stents). In conclusion, DSCT may be useful to noninvasively detect in-stent restenosis, especially in stents with a relatively large diameter.