AJR Get Involved! Great Benefits! Join ARRS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mühlenbruch, G.
Right arrow Articles by Koos, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mühlenbruch, G.
Right arrow Articles by Koos, R.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?
DOI:10.2214/AJR.06.0120
AJR 2007; 188:361-369
© American Roentgen Ray Society

Original Research

Evaluation of Aortocoronary Bypass Stents with Cardiac MDCT Compared with Conventional Catheter Angiography

Georg Mühlenbruch1, Andreas H. Mahnken1,2, Marco Das1, Rüdiger Blindt3, Christian Hohl1, Joachim E. Wildberger1, Rolf W. Günther1, Harald P. Kühl3 and Ralf Koos3

1 Department of Diagnostic Radiology, University Hospital (RWTH) Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany.
2 Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany.
3 Department of Cardiology, University Hospital (RWTH) Aachen, 52057 Aachen, Germany.

Received January 22, 2006; accepted after revision May 30, 2006.

 
Address correspondence to G. Mühlenbruch (gmuehlen{at}rad.rwth-aachen.de).


Abstract
Top
 Abstract
Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
OBJECTIVE. The objective of our study was to determine the accuracy of 16-MDCT for evaluation of stent patency and in-stent stenosis in venous coronary bypass grafts.

SUBJECTS AND METHODS. Fourteen patients who had previous stent placements in stenosed venous coronary bypass grafts underwent contrast-enhanced MDCT of the heart (collimation, 16 x 0.75 mm; 120 kV; 550 mAseff) and invasive coronary angiography. A total of 20 stents were evaluated: Vessel and stent diameters proximal to, distal to, and at various sites inside the stent were measured on both techniques, and Bland-Altman plots and correlations were calculated. Image noise and image quality were also assessed applying a Student's t test for data comparison of image noise.

RESULTS. All 20 bypass stents were correctly classified as patent. Vessel diameters outside the stent showed an excellent correlation (r = 0.90) and in-stent diameters showed a good correlation (r = 0.72), with lower values for MDCT due to blooming artifacts. All significant in-stent stenoses were correctly classified.

CONCLUSION. In patients suspected of bypass in-stent stenosis, 16-MDCT may be considered as a valuable alternative to conventional angiography for evaluating bypass patency and in-stent stenosis.

Keywords: cardiac imaging • catheter angiography • conventional angiography • coronary artery disease • CT angiography • heart • MDCT • stents


Introduction
Top
 Abstract
 Introduction
Subjects and Methods
 Results
 Discussion
 References
 
The diagnostic value of coronary CT angiography (CTA) using ECG-gated MDCT in the diagnostic workup of coronary artery disease has been shown by many studies. With the use of 16-MDCT scanners, a reasonable degree of sensitivity and specificity for the detection of high-grade coronary artery stenosis can be achieved [1-5]. In certain cases, CTA has been proven to be a safe alternative to conventional coronary angiography, an invasive procedure that still poses a small risk of mortality and morbidity [6]. For the latest generation of CT scanners, even better results can be expected and have already been published [7-9]. Besides imaging of the coronary arteries, MDCT also allows evaluation of coronary bypass grafts. High levels of sensitivity and specificity for the evaluation of bypass patency and degree of stenosis have been reported by several groups [10-12].

Although the results are promising for the detection of coronary artery disease using retrospectively ECG-gated MDCT of the heart, evaluation of coronary artery stents is still limited [13-15]. Discouraging results were reported from in vivo and in vitro studies using a 4-MDCT scanner, with artificial lumen narrowing ranging from 62% to 100% depending on the stent type [16, 17]. More recent in vitro and in vivo studies performed using later-generation scanners showed more promising results and even allowed the detection of coronary in-stent stenosis with moderate accuracy [18-22]. However, imaging of coronary artery stents is an important issue in cardiology because stenting is the predominant form of myocardial revascularization, with an estimated 664,000 angioplasty procedures having been performed in the United States in 2003 [23].

Surgically placed coronary bypass grafts have only a limited lifetime with a high rate of stenosis or even of occlusion. Especially for these patients with stenosis of coronary bypass grafts, catheter-based stent placement is one of the last options to improve their cardiac blood supply. In drug-eluting stents, a 6-month instent stenosis rate of 0% was reported in initial studies [24, 25]. However, in non-drug-eluting stents, in-stent restenosis is a major clinical problem, with a 6-month restenosis rate ranging from 11% to 46% [26]. These patients might benefit from a noninvasive follow-up for early detection of in-stent stenosis. In vitro studies using MDCT for the assessment of coronary artery stent lumen showed that the use of a dedicated convolution kernel is crucial to reducing beam-hardening artifacts caused by the stent struts [18, 20].


Figure 1
View larger version (98K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1A —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. MDCT images show examples for planning individually adapted planes orthogonal to vessel course outside and inside stent.

 


Figure 2
View larger version (96K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1B —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. MDCT images show examples for planning individually adapted planes orthogonal to vessel course outside and inside stent.

 
The aim of our study was to determine the accuracy of 16-MDCT for the evaluation of coronary bypass graft stents compared with the gold standard, invasive catheter-based coronary angiography. If high accuracy is shown, less invasive CTA of bypass graft stents may be an alternative to invasive angiography.


Subjects and Methods
Top
 Abstract
 Introduction
 Subjects and Methods
Results
 Discussion
 References
 
Patient Population
Fourteen consecutive patients (12 men and two women; mean age ± SD, 66.3 ± 10.2 years) with status postcoronary bypass graft surgery and subsequent stent placement in at least one bypass vessel, who presented with progressive symptoms of coronary artery disease, were included in this prospective study. The study was approved by the institutional review board, and informed consent of all patients was obtained before the examinations. A total of 20 bypass graft stents were evaluated.

CT Scanning
Throughout CT scanning, the ECG signal was digitally recorded and the mean heart rate during scanning was 67.5 ± 11.7 beats per minute. All patients were in sinus rhythm throughout scanning. Image acquisition was performed in a craniocaudal direction using a 16-MDCT scanner (Somatom Sensation 16, Siemens Medical Solutions) during a single breath-hold of 26.0 ± 2.0 seconds (mean ± SD). The cranial edge of the scan volume was set at the level of the aortic arch to include the proximal anastomoses of the bypass grafts in the scan volume. The examination protocol included a tube voltage of 120 kV, an effective tube current-time product of 550 mAseff, a collimation of 16 x 0.75 mm, a table feed of 3.4 mm per rotation, and a gantry rotation time of 420 milliseconds. No ECG pulsing, dose modulation, or weight-adapted scanning protocols were applied.

Contrast material was administered via the right cubital vein. The scan delay was determined using the bolus-tracking technique: When a threshold of 140 H was reached in the ascending aorta at the level of the origin of the coronary arteries, a delay of 8 seconds was applied before scanning was initiated. A biphasic contrast injection protocol optimized for imaging of coronary bypass grafts, with injection of 30 mL of nonionic contrast material (iopromide [Ultravist 370, Schering]) at a flow rate of 4 mL/s followed by 70 mL at a flow rate of 3 mL/s, was used. A saline chaser bolus of 50 mL injected at a flow rate of 3 mL/s was applied immediately after the contrast material injection was finished.

Axial images were reconstructed at 60% of the R-R interval using a field of view of 180 x 180 mm2, a 512 x 512 matrix, and a slice thickness of 1 mm with an increment of 0.6 mm. If images at 60% of the R-R interval showed motion artifacts, additional image series at different phases were reconstructed. A dedicated sharp heart view convolution kernel (B46f) that has been proven to be superior for imaging of stent lumen was applied [18, 20].

To keep the results of our study comparable with those of previous studies, we used window settings with a center of 200 H and a width of 700 H for image evaluation, as has been described elsewhere [16, 18]. All CT images were assessed by an experienced radiologist. The artifacts outside the stent lumen were evaluated with a 5-point grading scale as follows: 1, no visible artifacts; 2, small streak artifacts; 3, moderate streak artifacts, vicinity of the stent evaluable without degradation of image quality; 4, severe streak artifacts, vicinity of the stent evaluable with degraded image quality; and 5, massive streak artifacts, vicinity of the stent not assessable.

Measurements were performed on enlarged images using the electronic measurement tool provided with the CT scanner on a commercially available interactive 3D multiplanar reformation software platform (Syngo 3D, Siemens Medical Solutions). The maximum and minimum diameters of the contrast material-filled bypass and stent lumen at the following positions were measured: 1 cm proximal to the stent, right at the beginning of the stent, 1 cm inside the stent, right at the end of the stent, and 1 cm distal of the stent. In some cases, not all measurements could be performed—for example, due to stent placement close to the proximal or distal anastomoses of the graft (n = 15 measurement positions), close relationship to a second stent in the same bypass graft (n = 4), or a stent length below or equal to 1 cm (n = 9). Furthermore, attenuation values within the bypass stent lumen were measured with an individually adapted region of interest (ROI) in the transverse section at the exact same positions mentioned earlier; the SD of these measurements was used to estimate image noise. An example of the measurement planning and data acquisition is given in Figure 1A, 1B.


Figure 3
View larger version (77K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1C —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. Images illustrate how vessel and stent diameters and attenuation values were determined using MDCT.

 


Figure 4
View larger version (75K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1D —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. Images illustrate how vessel and stent diameters and attenuation values were determined using MDCT.

 


Figure 5
View larger version (88K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1E —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. Images illustrate how vessel and stent diameters and attenuation values were determined using MDCT.

 


Figure 6
View larger version (87K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 1F —55-year-old man with coronary artery disease. Stent had been placed in middle part of venous right coronary artery bypass graft. Min/Max = minimum and maximum diameters, measured in millimeters. Images illustrate how vessel and stent diameters and attenuation values were determined using MDCT.

 
Conventional Coronary Angiography
Invasive coronary angiography was performed by an experienced cardiologist via a femoral access including selective catheterization of the grafts. At least two orthogonal views were obtained for each bypass vessel. No nitroglycerine was applied for assessment of venous bypass grafts. The coronary angiograms were stored digitally (ACOM V 3.0, Siemens Medical Solutions) and were analyzed at a separate workstation. Vessel diameters were measured after catheter-based image calibration (QuantCor, CASS II, Siemens Medical Solutions) by the same cardiologist. Identical measurement positions as described in the CT Scanning section were applied (Fig. 2A, 2B, 2C). The catheter was always centered and assessed in the middle of the view in all patients; thus, variations were minimized.


Figure 7
View larger version (131K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 2A —Quantitative measurements of vessel and stent diameters in 74-year-old man with coronary artery disease. Invasive coronary angiography images show measurements corresponding to MDCT (not shown).

 

Figure 8
View larger version (131K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 2B —Quantitative measurements of vessel and stent diameters in 74-year-old man with coronary artery disease. Invasive coronary angiography images show measurements corresponding to MDCT (not shown).

 

Figure 9
View larger version (127K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 2C —Quantitative measurements of vessel and stent diameters in 74-year-old man with coronary artery disease. Invasive coronary angiography images show measurements corresponding to MDCT (not shown).

 

Assessment of Cardiovascular Risk Factors
Cardiovascular risk factors were identified from the patient chart. In addition to patient age, smoking habits, hypertension (antihypertensive medication or blood pressure at rest > 160/90 mm Hg), diabetes (use of insulin, use of oral hypoglycemic agents, or elevated fasting serum glucose concentration > 126 mg/dL) and hypercholesterolemia (total fasting serum cholesterol > 200 mg/dL or use of cholesterol-lowering medication) were evaluated. Patients were considered overweight if the body mass index (body weight/body length [2]) was > 25 kg/cm2.

Data Analysis
Both reviewers were blinded to the results of the other technique. Statistical analysis was performed using MedCalc software (version 8.1.1.0, Mariakerke). The mean of the maximum and minimum lumen diameters at the various measurement sites was taken. The mean vessel diameters at the various measurement sites inside and outside the stents of the two imaging techniques, angiography and MDCT, were compared using the method described by Bland and Altman [27], and a correlation was calculated. Image noise and CT attenuation values, measured in Hounsfield units, are given as mean ± SD of inside and outside stent measurements. Potential differences of image noise and CT values inside and outside the stent were analyzed applying a paired Student's t test with a significance level of 5%.


Results
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
Discussion
 References
 
Both the conventional angiography and MDCT procedures were successfully completed in all patients within 2.6 ± 2.6 days. Demographic data about the study participants and the stent parameters are given in Tables 1 and 2. The mean number of stents per patient was 1.4 ± 0.5, and the stent lumen size ranged from 2.5 to 4.5 mm, with a mean stent length of 15.2 ± 3.8 mm and a mean stent diameter of 3.65 ± 0.56 mm. The stents had been placed in bypass grafts that fed all major vessel territories of the heart; no differences in interpretation between bypass graft stents in respect to the different vessel territories have been observed. The mean time between bypass stent placement and the reevaluation by catheter angiography and MDCT was 17.1 ± 19.6 months.


View this table:
[in this window]
[in a new window]

  		TABLE 1: Demographic Data

 

View this table:
[in this window]
[in a new window]

  		TABLE 2: Stent Parameters

 

In all 20 bypass stents that MDCT results classified as "patent," patency was confirmed by angiography; none of the stents was totally occluded. Comparing the angiography and MDCT diameter measurements, the mean diameter measurements outside the stent (1 cm proximal and 1 cm distal to the stent) showed a correlation (r) of 0.90 (p < 0.0001), with an average of 0.46 mm (15.9%) higher values for MDCT (Fig. 3A). Comparing the mean diameters inside the stents, a correlation (r) of 0.72 (p < 0.0001), with an average of 0.23 mm (10.8%) higher values for angiography (Fig. 3B), was revealed. Figure 4 displays the mean diameter measurements of angiography and MDCT in comparison to the actual mechanical stent diameter at all measurement sites in the 20 stents evaluated. In two patients, angiography revealed a significant instent stenosis, which in both cases was detected on MDCT (Fig. 5A, 5B, 5C, 5D).


Figure 10
View larger version (9K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 3A —Bland-Altman plots of mean vessel diameters, all of which were measured in millimeters. Mean vessel diameters outside (A) and inside (B) stent show level of agreement of conventional angiography and cardiac MDCT angiography. No systematic deviation of data was observed. Solid lines show means, and dashed lines show SDs.

 

Figure 11
View larger version (11K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 3B —Bland-Altman plots of mean vessel diameters, all of which were measured in millimeters. Mean vessel diameters outside (A) and inside (B) stent show level of agreement of conventional angiography and cardiac MDCT angiography. No systematic deviation of data was observed. Solid lines show means, and dashed lines show SDs.

 

Figure 12
View larger version (16K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 4 —Graph shows mean diameter measurements of angiography ({blacksquare}) and MDCT ({blacktriangleup}) compared with mechanical diameter ({diamondsuit}) for each stent. In all 20 stents, 51 positions of in-stent measurements were achievable.

 

Figure 13
View larger version (70K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 5A —61-year-old man after bypass stent placement 4 years earlier who presented with atypical chest pain. MDCT angiography images reveal lumen narrowing in distal part of bypass graft stent (arrows).

 

Figure 14
View larger version (91K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 5B —61-year-old man after bypass stent placement 4 years earlier who presented with atypical chest pain. MDCT angiography images reveal lumen narrowing in distal part of bypass graft stent (arrows).

 

Figure 15
View larger version (155K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 5C —61-year-old man after bypass stent placement 4 years earlier who presented with atypical chest pain. Lumen narrowing shown in A and B was confirmed as in-stent stenosis (arrows) on conventional angiography. Due to small stent caliber (3 mm), quality of CT images is hampered right before coronary anastomosis of bypass graft.

 

Figure 16
View larger version (143K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 5D —61-year-old man after bypass stent placement 4 years earlier who presented with atypical chest pain. Lumen narrowing shown in A and B was confirmed as in-stent stenosis (arrows) on conventional angiography. Due to small stent caliber (3 mm), quality of CT images is hampered right before coronary anastomosis of bypass graft.

 
Comparing image noise measurements proximal, inside, and distal to the stent, significantly higher values were measured inside the stent, with a mean of 44.7 ± 18.6 H, with respect to 26.3 ± 14.8 H proximal and 27.6 ± 8.4 H distal to the stent (p = 0.0004 and 0.0018, respectively) (Fig. 6A). CT attenuation values also revealed significantly higher results inside the stent lumen, with a mean of 337 ± 101 H, with respect to 276 ± 148 H pre and 289 ± 149 H post the stent (p = 0.0108 and 0.0099, respectively) (Fig. 6B).


Figure 17
View larger version (8K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 6A —Bar graphs show image noise and CT attenuation values outside and inside stent. Image noise (A) and CT attenuation (B) values were 1 cm before (pre) and 1 cm after (post), and inside stent. Paired Student's t tests were applied.

 

Figure 18
View larger version (10K):
[in this window]
[in a new window]
[as a PowerPoint slide]
  		Fig. 6B —Bar graphs show image noise and CT attenuation values outside and inside stent. Image noise (A) and CT attenuation (B) values were 1 cm before (pre) and 1 cm after (post), and inside stent. Paired Student's t tests were applied.

 

Discussion
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
References
 
The purpose of this study was to evaluate the use of 16-MDCT for the detection of in-stent stenosis of coronary bypass stents. Because up to 46% of coronary artery stents show in-stent stenosis during the first 6 months after stent placement, follow-up of coronary artery stents is an important issue in cardiology. Patients with stenting of a stenosed coronary bypass graft have already undergone at least two invasive catheter-based angiography procedures and one major surgical procedure with all the associated risks and comorbidities. This patient population, in particular, may welcome and benefit from a noninvasive method for determining patency and potential in-stent stenosis of bypass stents.

Noninvasive techniques, such as electron beam tomography and MR angiography, have not revealed promising results for the detection of in-stent stenosis in previous studies. Electron beam tomography does not allow direct visualization of the stent lumen, and in stents made from stainless steel, MR angiography causes susceptibility artifacts with a signal loss, which makes evaluation of the stent lumen impossible [28, 29]. Retrospectively ECG-gated MDCT has shown promising results in the assessment of the coronary arteries [2, 8, 30]. As has already been shown for the assessment of patency of nonstented bypass grafts, our study results confirm the high potential of MDCT for the assessment of bypass stent patency [10-12]. In all 20 stents evaluated with MDCT, patency was confirmed on angiography.

However, MDCT of the coronary artery stent lumen in vitro and in vivo still suffers from some limitations [16-19]. Excessive radiopacity of implanted metal stents causes blooming, which results in impaired image quality due to an artificial increase in the width of the stent struts. Stent blooming obscures part of the stent lumen and increases the apparent external diameter of the stent, an effect that is also shown in our study with all mean diameters inside the stent being smaller than the actual technical stent diameter. The use of a dedicated edge-enhancing convolution kernel, as used in our study, reduces the effect of artificial lumen narrowing but increases image noise [18]. Comparing the vessel diameter measurements of MDCT and angiography inside the stent blooming may also explain why MDCT underestimates the mean patent vessel diameter by 10.8% inside the stent compared with angiography (Fig. 2B). Outside the stent, angiography revealed smaller mean vessel diameters than MDCT. Because catheter-based angiography, even when performed in different projections, is a 2D projection method, potential underestimation of the actual maximum vessel diameter is immanent.

Comparing MDCT measurements of image noise and attenuation values inside and outside the stent, we found higher values for both parameters inside the stent. As we described earlier, a dedicated convolution kernel for visualization of coronary stents was applied. In this kernel, the modulation transfer function is optimized to reduce blurring that typically occurs close to borders with high attenuation differences, leading to sharper delineation of the stent. However, stent blooming still leads to artificial lumen narrowing of the stent lumen, and the combination of beam-hardening effects and partial volume effects explains why significantly higher attenuation values were measured inside the stent than outside it. The SD of the attenuation values measured inside the stent also revealed higher values, indicating heightened image noise. This is caused by both the use of the edge-enhancing convolution kernel and again by beam-hardening effects of the metallic stent struts. The findings of our study concerning attenuation values and image noise are in accordance with other in vitro findings [18].

The good diagnostic value of MDCT for the detection of coronary in-stent stenosis has just recently been shown in a patient study [19]. Our study focused solely on coronary bypass stents. With relatively large calibers and little movement during the cardiac cycle in comparison with the native coronary vessels, bypass stents were assessable even using a 16-MDCT scanner. The introduction of 64-MDCT scanners with rotation times as low as 330 milliseconds led to a further increase in both spatial and temporal resolution [31]. The use of dual tube-detector systems will boost the increase, particularly in temporal resolution, even more [32]. In the future, this capability will lead to improved cardiac imaging using MDCT, including more accurate evaluation of coronary stents. A further increase in spatial resolution and more sophisticated reconstruction algorithms or convolution kernels may also help to diminish blooming artifacts [20].

Limitations of the study include the fact that only a selected cohort of patients with clinical suspicion for in-stent stenosis and only a low number of in-stent stenoses were examined. However, recruiting symptomatic patients with a bypass stent is not easy because the prevalence of this setting is not high. Examination of an asymptomatic bypass stent population may yield different results; nevertheless, it is in symptomatic patients that MDCT should prove to be valuable as a potential substitute for invasive diagnostic catheter-based angiography.

For comparison of vessel and in-stent diameters, the mean of the minimum and maximum diameters at each position measured were taken to compare data from angiography with that from MDCT. As we described earlier, angiography with 2D projections tends to lead to overestimation of the minimum diameter and underestimation of the maximum diameter of a vessel. On MDCT, minimum and maximum diameters are measured in an individually planned image plane orthogonal to the vessel course. To overcome these discrepancies, which are inherent to both techniques, the mean vessel diameter was taken; moreover, the mean diameter showed the best correlation in a previous study [33]. Another limitation is that MDCT measurements were performed by only one reviewer.

Summarizing the results of this study, we can state that assessment of coronary bypass stents using dedicated ECG-gated cardiac 16-MDCT angiography is technically and practicably feasible and shows a good correlation with current gold-standard invasive angiography. In patients in whom bypass in-stent stenosis is suspected, MDCT may be considered as a valuable alternative to conventional angiography to evaluate bypass patency and in-stent stenosis.


References
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 

  1. Ropers D, Baum U, Pohle K, et al. Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction. Circulation2003; 107:664 -666[Abstract/Free Full Text]
  2. Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama PM, de Feyter PJ. Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography. Circulation2002; 106:2051 -2054[Abstract/Free Full Text]
  3. Kuettner A, Kopp AF, Schroeder S, et al. Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with angiographically proven coronary artery disease. J Am Coll Cardiol 2004; 43:831 -839[Abstract/Free Full Text]
  4. Heuschmid M, Kuettner A, Schroeder S, et al. ECG-gated 16-MDCT of the coronary arteries: assessment of image quality and accuracy in detecting stenoses. AJR 2005;184 : 1413-1419[Abstract/Free Full Text]
  5. Ghersin E, Litmanovich D, Dragu R, et al. 16-MDCT coronary angiography versus invasive coronary angiography in acute chest pain syndrome: a blinded prospective study. AJR 2006;186 : 177-184[Abstract/Free Full Text]
  6. Kennedy JW. Complications associated with cardiac catheterization and angiography. Cathet Cardiovasc Diagn1982; 8:5 -11[Medline]
  7. Vrtiska TJ, Fletcher JG, McCollough CH. State-of- the-art imaging with 64-channel multidetector CT angiography. Perspect Vasc Surg Endovasc Ther 2005; 17:3 -10[Abstract/Free Full Text]
  8. Leschka S, Alkadhi H, Plass A, et al. Accuracy of MDCT coronary angiography with 64-slice technology: first experience. Eur Heart J 2005; 26:1482 -1487[Abstract/Free Full Text]
  9. Mollet NR, Cademartiri F, van Mieghem CA, et al. High-resolution spiral computed tomography coronary angiography in patients referred for diagnostic conventional coronary angiography. Circulation 2005;112 : 2318-2323[Abstract/Free Full Text]
  10. Ropers D, Ulzheimer S, Wenkel E, et al. Investigation of aortocoronary artery bypass grafts by multislice spiral computed tomography with electrocardiographic-gated image reconstruction. Am J Cardiol 2001; 88:792 -795[CrossRef][Medline]
  11. Gurevitch J, Gaspar T, Orlov B, et al. Noninvasive evaluation of arterial grafts with newly released multidetector computed tomography. Ann Thorac Surg 2003;76 : 1523-1527[Abstract/Free Full Text]
  12. Schlosser T, Konorza T, Hunold P, Kuhl H, Schmermund A, Barkhausen J. Noninvasive visualization of coronary artery bypass grafts using 16-detector row computed tomography. J Am Coll Cardiol2004; 44:1224 -1229[Abstract/Free Full Text]
  13. Knollmann FD, Moller J, Gebert A, Bethge C, Felix R. Assessment of coronary artery stent patency by electron-beam CT. Eur Radiol 2004; 14:1341 -1347[Medline]
  14. Funabashi N, Komiyama N, Yanagawa N, Mayama T, Yoshida K, Komuro I. Images in cardiovascular medicine: coronary artery patency after metallic stent implantation evaluated by multislice computed tomography. Circulation 2003;107 : 147-148[Free Full Text]
  15. Storto ML, Marano R, Maddestra N, Caputo M, Zimarino M, Bonomo L. Images in cardiovascular medicine: multislice spiral computed tomography for in-stent restenosis. Circulation 2002;105 : 2005[Free Full Text]
  16. Maintz D, Juergens KU, Wichter T, Grude M, Heindel W, Fischbach R. Imaging of coronary artery stents using multislice computed tomography: in vitro evaluation. Eur Radiol 2003;13 : 830-835[Medline]
  17. Kruger S, Mahnken AH, Sinha AM, et al. Multislice spiral computed tomography for the detection of coronary stent restenosis and patency. Int J Cardiol 2003;89 : 167-172[Medline]
  18. Mahnken AH, Buecker A, Wildberger JE, et al. Coronary artery stents in multislice computed tomography: in vitro artifact evaluation. Invest Radiol 2004;39 : 27-33[CrossRef][Medline]
  19. Gaspar T, Halon DA, Lewis BS, et al. Diagnosis of coronary in-stent restenosis with multidetector row spiral computed tomography. J Am Coll Cardiol 2005; 46:1573 -1579[Abstract/Free Full Text]
  20. Mahnken AH, Seyfarth T, Flohr T, et al. Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography. Invest Radiol 2005;40 : 8-13[Medline]
  21. Maintz D, Seifarth H, Raupach R, et al. 64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents. Eur Radiol 2006;16 : 818-826[CrossRef][Medline]
  22. Seifarth H, Ozgun M, Raupach R, et al. 64-versus 16-slice CT angiography for coronary artery stent assessment: in vitro experience. Invest Radiol 2006;41 : 22-27[CrossRef][Medline]
  23. Thom T, Haase N, Rosamond W, et al. Heart disease and stroke statistics—2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation; 113:e85 -e151 (Epub ahead of print)
  24. Regar E, Serruys PW, Bode C, et al.; RAVEL Study Group. Angiographic findings of the multicenter Randomized Study With the Sirolimus-Eluting Bx Velocity Balloon-Expandable Stent (RAVEL): sirolimus-eluting stents inhibit restenosis irrespective of the vessel size. Circulation 2002;106 : 1949-1956[Abstract/Free Full Text]
  25. Grube E, Silber S, Hauptmann KE, et al. TAXUS I: six- and twelve-month results from a randomized, double-blind trial on a slow-release paclitaxel-eluting stent for de novo coronary lesions. Circulation 2003;107 : 38-42[Abstract/Free Full Text]
  26. Antoniucci D, Valenti R, Santoro GM, et al. Restenosis after coronary stenting in current clinical practice. Am Heart J 1998; 135:510 -518[CrossRef][Medline]
  27. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet1986; 1:307 -310[CrossRef][Medline]
  28. Pump H, Mohlenkamp S, Sehnert CA, et al. Coronary arterial stent patency: assessment with electron-beam CT. Radiology2000; 214:447 -452[Abstract/Free Full Text]
  29. Hug J, Nagel E, Bornstedt A, Schnackenburg B, Oswald H, Fleck E. Coronary arterial stents: safety and artifacts during MR imaging. Radiology 2000;216 : 781-787[Abstract/Free Full Text]
  30. Kuettner A, Beck T, Drosch T, et al. Diagnostic accuracy of noninvasive coronary imaging using 16-detector slice spiral computed tomography with 188 ms temporal resolution. J Am Coll Cardiol 2005; 45:123 -127[Abstract/Free Full Text]
  31. Flohr T, Stierstorfer K, Raupach R, Ulzheimer S, Bruder H. Performance evaluation of a 64-slice CT system with z-flying focal spot. Rofo 2004; 176:1803 -1810[Medline]
  32. Flohr TG, McCollough CH, Bruder H, et al. First performance evaluation of a dual-source CT (DSCT) system. Eur Radiol 2006; 16:256 -268[CrossRef][Medline]
  33. Mahnken AH, Wildberger JE, Sinha AM, et al. Value of 3D-volume rendering in the assessment of coronary arteries with retrospectively ECG-gated multislice spiral CT. Acta Radiol2003; 44:302 -309[CrossRef][Medline]

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 Am. J. Roentgenol.Home page
C. Plumhans, G. Muhlenbruch, A. Rapaee, K.-H. Sim, T. Seyfarth, R. W. Gunther, and A. H. Mahnken
Assessment of Global Right Ventricular Function on 64-MDCT Compared with MRI
Am. J. Roentgenol., May 1, 2008; 190(5): 1358 - 1361.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mühlenbruch, G.
Right arrow Articles by Koos, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mühlenbruch, G.
Right arrow Articles by Koos, R.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS