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(Radiology. 2000;214:447-452.)
© RSNA, 2000

Cardiac Imaging

Coronary Arterial Stent Patency: Assessment with Electron-Beam CT1

Heiko Pump, MD, Stefan Möhlenkamp, MD, Cornelia A. Sehnert, MD, Svenja S. Schimpf, MD, Armin Schmidt, MD, Raimund Erbel, MD, Dietrich H. W. Grönemeyer, MD and Rainer M. M. Seibel, MD

1 From the Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Schulstr 10, 45468 Muelheim a. d. Ruhr, Germany (H.P., C.A.S., S.S.S., A.S., R.M.M.S.); the Department of Radiology and Microtherapy, University of Witten/Herdecke, Bochum, Germany (S.M., D.H.W.G.); and the Department of Cardiology, University of Essen, Germany (S.M., R.E.). From the 1997 RSNA scientific assembly. Received July 21, 1997; revision requested October 7; final revision received April 26, 1999; accepted August 20. Address reprint requests to H.P. (e-mail: pump@mri.de).


   Abstract
TOP
 Abstract
Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
PURPOSE: To evaluate electron-beam computed tomography (CT) for stent localization and noninvasive assessment of stent patency in patients with coronary arterial stents and coronary bypass stents.

MATERIALS AND METHODS: CT in the single-section volume mode was performed in 202 patients with 321 coronary arterial stents in 221 vessels to localize the stents. Patency was evaluated in the multisection flow mode with an intravenous bolus injection of contrast material. All electron-beam CT images were reviewed by an observer who had no knowledge of the coronary angiographic results. Electron-beam CT findings were then compared with coronary angiographic findings.

RESULTS: The stents could be visualized and related to the coronary arterial segments in 216 of 221 vessels with electron-beam CT. Of the 221 vessels, 207 were correctly evaluated with electron-beam CT. Compared with coronary angiography, electron-beam CT permitted the detection of 18 of 23 high-grade stenoses (sensitivity, 78%) and correctly depicted the absence of high-grade stenoses in 189 of 193 vessels with stents (specificity, 98%). Altogether, 18 stenoses were detected correctly at electron-beam CT; the interpretation was false-positive in four vessels (positive predictive value, 82% [18/22 vessels]) and false-negative in five (negative predictive value, 97% [189/194 vessels]).

CONCLUSION: Electron-beam CT may be helpful in localizing intracoronary stents and assessing stent patency noninvasively to delay the intervals between catheterizations in an increasing number of patients.

Index terms: Computed tomography (CT), electron beam, 548.12112, 548.12119 • Coronary angiography, 548.1244 • Coronary vessels, CT, 548.12112, 548.12119 • Coronary vessels, stenosis or obstruction, 548.76 • Coronary vessels, stents and prostheses, 548.1269


   Introduction
TOP
 Abstract
 Introduction
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
High-pressure stent implantation is an important method in the treatment of stenoses in coronary arteries and grafts. Coronary arterial stents were developed to treat acute complications of balloon angioplasty (1–5). Dissections and vessel closure after angioplasty are the main indications for stent placement. The results of several studies (6–12) have demonstrated that stent placement for native coronary arterial stenoses reduces the rate of restenoses compared with balloon angioplasty alone. Nevertheless, the risk of restenoses and occlusion of vessels treated with stent placement is still in the range of 12%–47% (6–12).

The aim of this study was to evaluate the usefulness of contrast material–enhanced electron-beam computed tomography (CT) in localizing coronary arterial stents noninvasively and assessing stent patency.


   MATERIALS AND METHODS
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 References
 
Between January 1995 and December 1996, a total of 202 consecutive patients (178 men, 24 women; mean age, 62.9 years; age range, 34–82 years) were examined. All of the patients gave written informed consent to participate in the study. Palmaz-Schatz (Cordis, Johnson and Johnson, Warren, NJ) and Micro-stents (Arterial Vascular Engineering, Santa Rosa, Calif) were the most frequently (in 177 [80%] of 221 vessels) used stent types.

The patient population was divided in two groups. The patients in the first group (n = 162) were examined 3 days ± 2 (SD) (range, 1–6 days) after stent placement. All patients in this group were examined for clinical indications (ie, atypical or nonischemic chest pain) after coronary arterial stent placement. The previously performed coronary angiographic examination served as the standard-of-reference method because repeat coronary angiography was not required in any of these patients.

The patients in the second group (n = 40) were examined after a routine follow-up period of 6 months. These patients required a subsequent coronary angiographic examination 1 or 2 days after the electron-beam CT examination. Recatheterization was necessary for different reasons. In 22 of 40 patients, at electron-beam CT, we suspected restenosis of the segment in which a stent was placed. In the other 18 patients, we performed angiography despite a negative finding at electron-beam CT. Of these 18 patients, 15 had either persistent clinical symptoms that pointed toward restenosis or positive stress test results; in the remaining three patients, the electron-beam CT study was not of sufficient quality to assess stent patency. The findings at recatheterization served as the standard-of-reference results, which were compared with the electron-beam CT findings.

Interpretation of Electron-Beam CT Findings
Electron-beam CT in the single-section mode was performed in each patient with an Evolution Scanner C 150 unit (Siemens, Erlangen, Germany), beginning at the pulmonary trunk, with 30–45 contiguous 3-mm sections triggered at 80% of the RR interval and by using a 100-msec acquisition time. A multisection flow study followed the evaluation of the circulation time, which was performed with a bolus injection of 20 mL of iopromide (370 mg of iodine per milliliter) (Ultravist; Schering, Erlangen, Germany). In the multisection flow study, one or two bolus injections of 50 mL of iopromide (370 mg of iodine per milliliter) with an injection rate of 7–10 mL/sec were performed. The multisection flow study protocol consisted of 8-mm sections, eight levels, 10 times per level, electrocardiogram triggered at 80% of the RR interval on every second heart beat, and a 50-msec acquisition time.

Every CT study was analyzed in three steps. First, we localized the stents (Fig 1) and determined the calcium score of the coronary arteries by using the Agatston method (13). Vessel segments in which a stent was placed were excluded from calcium scoring, because calcifications in the area of stent placement could not be reliably differentiated from stent struts. The localization of the stent and of the calcified plaques was essential for the planning of the contrast-enhanced studies. The table position was adjusted so that the stent was positioned between the scanning planes and images could be obtained proximal and distal to the stent. In addition, an incorrect attenuation measurement on the contrast studies caused by calcified plaques could be avoided.



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  		Figure 1a. (a) Transverse electron-beam CT scan obtained in a 60-year-old man shows a Micro-stent (straight arrow) in the proximal region of the left anterior descending artery (curved arrow). Calcified plaques in the left main coronary artery (arrowhead) also are seen. (b) Coronary angiogram obtained in the same patient as in a shows the stent (arrow).

 


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  		Figure 1b. (a) Transverse electron-beam CT scan obtained in a 60-year-old man shows a Micro-stent (straight arrow) in the proximal region of the left anterior descending artery (curved arrow). Calcified plaques in the left main coronary artery (arrowhead) also are seen. (b) Coronary angiogram obtained in the same patient as in a shows the stent (arrow).

 
In the second step, the multisection flow study results were analyzed with integrated scanner software (Imatron, San Francisco, Calif). Ten recorded images obtained at each level were combined in a cineloop for qualitative assessment based on the examiner's visual inspection of the images. The precontrast phase, contrast-enhanced phase, and washout of the contrast material in the coronary arteries, heart chambers, aorta, and pulmonary arteries were assessed by the examiner.

In the third step, integrated scanner software (Imatron) was used for densitometric evaluations in a time-attenuation analysis of the contrast-enhanced studies with a gamma variate fit curve. The attenuation changes (in Hounsfield units) in a region of interest in the vessel following contrast material administration were calculated by using a specific exponential function as the gamma variate curve. The gamma variate curve of the coronary arteries was compared with that of the ascending aorta.

Depiction of each stent and of calcifications with respect to their location was based on typical landmarks, and the analysis was limited to that of major coronary arteries (ie, proximal, middle, and distal segments) and major side branches (ie, first diagonal and/or marginal branches). The electron-beam CT studies were evaluated retrospectively by one of three examiners (H.P., C.A.S., or S.S.S.) who had no knowledge of the coronary angiographic findings. The stent type, number of stents, exact segmental location, and pathologic findings of the other coronary vessels were unknown to the examiner.

A vessel in which a stent was placed was considered to be patent if the examiner visualized the hyperattenuating vessel proximal and distal to the stent compared with the location of the other coronary arteries in the cineloop. Hyperattenuation proximal and distal in the cineloop plus a gamma variate curve distal to the stent, or hyperattenuation in the cineloop and a gamma variate curve proximal and distal to the stent were the criteria for patency (Fig 2).



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  		Figure 2a. (a) Right anterior oblique coronary angiogram obtained in a 59-year-old man shows a patent stent in the left anterior descending artery. The arrows indicate the end of the Powergrip stent (Cordis). (b) Transverse CT scan (multisection mode) obtained in the same patient as in a shows the patent stent (arrows). A time-attenuation measurement was obtained proximal to the stent (B). (c) Graph that corresponds with b illustrates a comparison of the deposited regions of interest. The gamma variate curve of the left anterior descending artery proximal to the stent (B) is compared with the aortic curve (A). The mean transit time in the aorta was 8.08 seconds; that in the proximal left anterior descending artery was 8.61 seconds. The peak enhancement time in the aorta was 6.5 seconds; that in the proximal left anterior descending artery was 6.6 seconds. (d) On another transverse CT scan (multisection mode) obtained in the same patient as in a and b, the region of interest (ROI) distal to the stent (B) is seen. LAD = left anterior descending artery. (e) Time-attenuation measurement graph that corresponds with d. The gamma variate curve distal to the patent stent (B) is compared with the aortic curve (A). The mean transit time in the left anterior descending artery was 10.01 seconds, and the peak enhancement time was 7.8 seconds.

 


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  		Figure 2b. (a) Right anterior oblique coronary angiogram obtained in a 59-year-old man shows a patent stent in the left anterior descending artery. The arrows indicate the end of the Powergrip stent (Cordis). (b) Transverse CT scan (multisection mode) obtained in the same patient as in a shows the patent stent (arrows). A time-attenuation measurement was obtained proximal to the stent (B). (c) Graph that corresponds with b illustrates a comparison of the deposited regions of interest. The gamma variate curve of the left anterior descending artery proximal to the stent (B) is compared with the aortic curve (A). The mean transit time in the aorta was 8.08 seconds; that in the proximal left anterior descending artery was 8.61 seconds. The peak enhancement time in the aorta was 6.5 seconds; that in the proximal left anterior descending artery was 6.6 seconds. (d) On another transverse CT scan (multisection mode) obtained in the same patient as in a and b, the region of interest (ROI) distal to the stent (B) is seen. LAD = left anterior descending artery. (e) Time-attenuation measurement graph that corresponds with d. The gamma variate curve distal to the patent stent (B) is compared with the aortic curve (A). The mean transit time in the left anterior descending artery was 10.01 seconds, and the peak enhancement time was 7.8 seconds.

 


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  		Figure 2c. (a) Right anterior oblique coronary angiogram obtained in a 59-year-old man shows a patent stent in the left anterior descending artery. The arrows indicate the end of the Powergrip stent (Cordis). (b) Transverse CT scan (multisection mode) obtained in the same patient as in a shows the patent stent (arrows). A time-attenuation measurement was obtained proximal to the stent (B). (c) Graph that corresponds with b illustrates a comparison of the deposited regions of interest. The gamma variate curve of the left anterior descending artery proximal to the stent (B) is compared with the aortic curve (A). The mean transit time in the aorta was 8.08 seconds; that in the proximal left anterior descending artery was 8.61 seconds. The peak enhancement time in the aorta was 6.5 seconds; that in the proximal left anterior descending artery was 6.6 seconds. (d) On another transverse CT scan (multisection mode) obtained in the same patient as in a and b, the region of interest (ROI) distal to the stent (B) is seen. LAD = left anterior descending artery. (e) Time-attenuation measurement graph that corresponds with d. The gamma variate curve distal to the patent stent (B) is compared with the aortic curve (A). The mean transit time in the left anterior descending artery was 10.01 seconds, and the peak enhancement time was 7.8 seconds.

 


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  		Figure 2d. (a) Right anterior oblique coronary angiogram obtained in a 59-year-old man shows a patent stent in the left anterior descending artery. The arrows indicate the end of the Powergrip stent (Cordis). (b) Transverse CT scan (multisection mode) obtained in the same patient as in a shows the patent stent (arrows). A time-attenuation measurement was obtained proximal to the stent (B). (c) Graph that corresponds with b illustrates a comparison of the deposited regions of interest. The gamma variate curve of the left anterior descending artery proximal to the stent (B) is compared with the aortic curve (A). The mean transit time in the aorta was 8.08 seconds; that in the proximal left anterior descending artery was 8.61 seconds. The peak enhancement time in the aorta was 6.5 seconds; that in the proximal left anterior descending artery was 6.6 seconds. (d) On another transverse CT scan (multisection mode) obtained in the same patient as in a and b, the region of interest (ROI) distal to the stent (B) is seen. LAD = left anterior descending artery. (e) Time-attenuation measurement graph that corresponds with d. The gamma variate curve distal to the patent stent (B) is compared with the aortic curve (A). The mean transit time in the left anterior descending artery was 10.01 seconds, and the peak enhancement time was 7.8 seconds.

 


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  		Figure 2e. (a) Right anterior oblique coronary angiogram obtained in a 59-year-old man shows a patent stent in the left anterior descending artery. The arrows indicate the end of the Powergrip stent (Cordis). (b) Transverse CT scan (multisection mode) obtained in the same patient as in a shows the patent stent (arrows). A time-attenuation measurement was obtained proximal to the stent (B). (c) Graph that corresponds with b illustrates a comparison of the deposited regions of interest. The gamma variate curve of the left anterior descending artery proximal to the stent (B) is compared with the aortic curve (A). The mean transit time in the aorta was 8.08 seconds; that in the proximal left anterior descending artery was 8.61 seconds. The peak enhancement time in the aorta was 6.5 seconds; that in the proximal left anterior descending artery was 6.6 seconds. (d) On another transverse CT scan (multisection mode) obtained in the same patient as in a and b, the region of interest (ROI) distal to the stent (B) is seen. LAD = left anterior descending artery. (e) Time-attenuation measurement graph that corresponds with d. The gamma variate curve distal to the patent stent (B) is compared with the aortic curve (A). The mean transit time in the left anterior descending artery was 10.01 seconds, and the peak enhancement time was 7.8 seconds.

 
The criteria of absence of hyperattenua-tion distal to the stent in the cineloop or hyperattenuation proximal to the stent but weak contrast enhancement distally and no fitted gamma variate curve raised the suspicion of luminal narrowing or vessel occlusion (Fig 3). Attenuation curves were an important additional method used to confirm that the structure in question was hyperattenuating immediately after the aortic root hyperattenuation.



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  		Figure 3a. (a) Transverse CT scan (multisection mode) obtained in a 63-year-old man shows a high-grade left anterior descending arterial stenosis distal to the stent. The region of interest is placed in a hypoattenuating distal vessel region (arrow). (b) Time-attenuation measurement graph that corresponds with a. The unconnected dots below the 100-HU mark (B) indicate the region of interest placed in the hypoattenuating distal vessel region. A = gamma variate curve of the ascending aorta.

 


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  		Figure 3b. (a) Transverse CT scan (multisection mode) obtained in a 63-year-old man shows a high-grade left anterior descending arterial stenosis distal to the stent. The region of interest is placed in a hypoattenuating distal vessel region (arrow). (b) Time-attenuation measurement graph that corresponds with a. The unconnected dots below the 100-HU mark (B) indicate the region of interest placed in the hypoattenuating distal vessel region. A = gamma variate curve of the ascending aorta.

 
Interpretation of Coronary Angiographic Findings
Coronary angiography was performed by using the Judkins technique. A minimum of four views in the left coronary arterial system and two views in the right coronary artery were obtained by using the HICOR system (Siemens). The coronary arterial system in 15 coronary segments was evaluated (14).

Normal segments were defined as those without any wall irregularities; hemodynamically insignificant stenosis, as luminal diameter narrowing of less than 50%; intermediate stenosis, as luminal diameter narrowing of 50%–74%; and hemodynamically significant (ie, high-grade) stenosis, as luminal diameter narrowing of 75% or greater. Off-line caliper measurements (Medis, Reiber, the Netherlands) were used to confirm the categorizations of the lesions. As part of the procedure, all angiograms were interpreted by one of several experienced observers (including S.M. and R.E.) without knowledge of the electron-beam CT results.

Comparison of Electron-Beam CT and Coronary Angiographic Findings
The results of electron-beam CT were compared retrospectively with the findings on the digitally stored images obtained at coronary angiography. After the observers were no longer blinded, two of them (H.P., S.M.) reevaluated the vessels by consensus to assess any discrepancies between the conventional angiographic and electron-beam CT findings.

For a comparison of electron-beam CT versus coronary angiographic findings, standard estimates of sensitivity, specificity, and positive and negative predictive values were obtained by using two-by-two contingency tables.


   RESULTS
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 References
 
Two hundred two patients were examined. Altogether, 221 vessels were treated with 321 stents. Most of the stents were localized in the proximal and middle regions of the left anterior descending (94 vessels) and right coronary (63 vessels) arteries. Stents were less commonly seen in the left circumflex coronary artery (34 vessels), left main coronary artery (three vessels), and coronary bypass grafts (27 vessels).

Compared with coronary angiography, in which all 221 of the vessels could be seen and related to coronary segments, with electron-beam CT, stents could be visualized and related to the coronary segments in 216 (98%) of the 221 vessels. Differentiation between stent and extensive calcifications was not possible with electron-beam CT in two (1%) of the 221 vessels. Wiktor stents (MedTronic, Kerkrade, the Netherlands) produced artifacts in five (2%) of 221 vessels. These artifacts, caused by the tantalum struts of the Wiktor stents, did not impair the evaluation of patency because they did not disturb the cineloop evaluation and time-attenuation analysis of the proximal or distal vessel segments. All of the other examined stents were made of stainless steel, which produces no artifacts. Electron-beam CT evaluation was not possible in three (1%) of the 221 vessels due to technical procedural problems or insufficient patient compliance.

On coronary angiograms, 198 (90%) of the 221 vessels in which stents were placed were patent without high-grade stenoses. According to contrast-enhanced electron-beam CT criteria, 189 (95%) of the 198 vessels were patent. Twenty-three (10%) of the 221 vessels with stents had high-grade stenosis at coronary angiography. These stenoses were correctly identified by using electron-beam CT in 18 of 23 cases (sensitivity, 78%), whereas electron-beam CT yielded a false-negative result in five (22%) of 23 cases. Thus, 207 (94%) of 221 vessels with stents were correctly classified by using electron-beam CT. False-positive interpretations were made in four (2%) of 221 vessels by using electron-beam CT.

Cineloop evaluation was possible in 213 (96%) of the 221 vessels with stents. Time-attenuation analysis with gamma variate curve fitting was feasible in 118 (53%) of the 221 vessels.

In summary, compared with coronary angiography, electron-beam CT had a sensitivity of 78% (18 of 23 vessels) in the detection of high-grade stenoses, a specificity of 98% (189 of 193 vessels) in the detection of patent vessels with stents, a positive predictive value of 82% (18 of 22 vessels), and a negative predictive value of 97% (189 of 194 vessels).


   DISCUSSION
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
References
 
The recurrence of stenosis after stent placement remains a clinical problem; restenosis rates range from 12% to 47% (6–12). In most of our patients, we perform electron-beam CT for the evaluation of chest pain after coronary stent placement to exclude subacute stent stenosis or occlusion.

Jeremias et al (15) found that almost 50% of patients experience chest pain after coronary arterial stent placement, but only a minority of them have signs of ischemia. In this setting, noninvasive measures should prove to be valuable in identifying those patients who truly have subacute restenosis. Bicycle stress testing after a brief interval following coronary arterial stent placement should be performed with caution, if at all, especially if there was femoral access to the coronary arteries during the procedure.

The results of preliminary reports (16–19) have shown the potential of contrast-enhanced electron-beam CT for the evaluation of coronary vessels and bypass grafts. The multisection mode and integrated software, especially with cineloop evaluation and time-attenuation analysis, allow the assessment of flow and patency with sensitivities between 94% and 96% and specificities between 86% and 100% for the determination of patency.

Our group previously found electron-beam CT to be feasible and useful in the noninvasive assessment of the patency of vessel segments with stents (20,21). Schmermund et al (21) in 1996 reported on their assessment of coronary Palmaz-Schatz stents in 22 patients. At that time, 20 (91%) of 22 patients could be analyzed by using cineloop evaluation, and in 17 (85%) of these 20 patients, a gamma variate curve was fitted to the segment distal to the stent. In the present study, 202 patients with different stent types were examined, and compared with the evaluations in the study by Schmermund et al, a higher rate of cineloop evaluations (96% vs 91%) and a lower rate of gamma variate curve evaluations (53% vs 85%) were obtained. Similar time-attenuation results were estimated, independent of the vessel in which a stent was placed and of stent localization (22).

In most cases, the cineloop evaluation was sufficient to confirm stent patency. A comparison with the other coronary arteries usually led to the correct diagnosis. The time-attenuation analysis and gamma variate curve application were important additional elements in confirming the obstruction in cases in which there was weak contrast enhancement distal to the stent. Prolonged circulation time with insufficient contrast enhancement, arrhythmia, inadequate breath holding, and calcifications in distal segments were frequent reasons for the small number of gamma variate curves that were successfully fitted. When these factors were present, there was no densitometric measurement and no exact determination of intravascular deposition in a region of interest.

Electron-beam CT enabled stenosis to be correctly detected in 18 of 23 patients, whereas it yielded a false-negative result in five patients with high-grade stenoses. In these five patients, the investigators had false interpretations in the cineloop evaluation and time-attenuation analysis. The examiners observed a weak area of attenuation in all five stenoses distal to the stent in the cineloop. In these cases, even though high-grade stenoses existed, a gamma variate curve could be fitted. The recapitulation of the time-attenuation analysis, especially the direct comparison of the fitted curves proximal and distal to the stent, demonstrated substantial differences. All fitted curves distal to the stent had a peak attenuation of less than 100 HU and a fit error of greater than 15%. The region of interest was not exactly deposited in the vessel over the 10 recorded times, so some lower attenuation values of the epicardiac fat or lung were included in the calculation. The baseline value of these curves was typically below 50–70 HU, the attenuation of coronary vessels. In all five cases, a gamma variate curve could not be fitted after the correct redeposition of the region of interest in the coronary vessel segment distal to the stent.

The false-positive results in four vessels were due to reduced ejection fractions with prolonged transit times; this resulted in insufficient contrast enhancement, which precluded densitometric evaluation. Although the stents were patent, we observed only weak contrast enhancement distal to the stent. A gamma variate curve could not be fitted in these four cases.

Currently, exact quantification of stenosis is possible only with coronary angiography. In the present study, time-attenuation analysis allowed only the differentiation between a patent vessel with a stent, high-grade stenosis of a vessel with a stent, and stent occlusion, but no exact quantification of the coronary arterial flow. Compared with selective coronary angiography, however, electron-beam CT is less invasive, involves a much shorter overall investigation time, and requires a markedly lower radiation dose (23,24).

There have been more recent reports of other approaches to coronary arterial investigations. The results of studies by Moshage et al (25) and Achenbach et al (26,27) showed that electron-beam CT enables the noninvasive visualization of the coronary vessel anatomy. They visualized occlusions and stenoses of coronary bypass grafts and coronary arteries with three-dimensional and multiplanar reconstructions. Electron-beam CT has the advantage of being a three-dimensional technique. In postprocessing, views from any desired angle can be generated from the same three-dimensional data set (Fig 4).



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  		Figure 4. Curved multiplanar electron-beam CT reconstruction of a patent left anterior descending arterial stent (straight arrow) in a 53-year-old man. The vessel region distal to the stent is hyperattenuating. The left main coronary artery (curved arrow) and left anterior descending artery (arrowhead) are seen.

 
Our study results demonstrated that contrast-enhanced electron-beam CT can be a helpful method of noninvasively assessing coronary arterial stent patency and thus of value in the treatment of an increasing number of patients.


   Footnotes
 
Author contributions: Guarantors of integrity of entire study, all authors; study concepts and design, all authors; definition of intellectual content, all authors; literature research, H.P.; clinical studies, S.M.; data acquisition, H.P., S.M.; data and statistical analyses, H.P.; manuscript preparation, H.P.; manuscript editing, H.P., S.M., R.M.M.S., R.E.; manuscript review, H.P., S.M.


   References
TOP
 Abstract
 Introduction
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

  1. Sigwart U, Puel J, Mirkovitch V, Joffre F, Kappenberger L. Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty. N Engl J Med 1987; 316:701-706.[Abstract]
  2. Haude M, Erbel R, Straub U, Dietz U, Schatz R, Meyer J. Results on intracoronary stents for management of coronary dissection after balloon angioplasty. Am J Cardiol 1991; 67:691-969.[Medline]
  3. Roubin GS, Cannon AD, Agrawal SK, et al. Intracoronary stenting for acute and threatened closure complicating percutaneous transluminal coronary angioplasty. Circulation 1992; 85:916-927.[Abstract/Free Full Text]
  4. De Feyter PJ, De Scheerder I, van den Brand M, Laarman GJ, Suryarpranata H, Serrruys PW. Emergency stenting for refractory acute coronary artery occlusion during coronary angioplasty. Am J Cardiol 1990; 66:1147-1150.[Medline]
  5. Herman HC, Buchbinder M, Cleman MW, et al. Emergent use of balloon-expandable coronary artery stenting for failed percutaneous transluminal coronary angioplasty. Circulation 1992; 86:812-819.[Abstract/Free Full Text]
  6. Fischman DL, Leon MB, Baim DS, et al. A randomized comparison of coronary-stent placement and balloon angioplasty in patients with coronary artery disease: Stent Restenosis Study Investigators. N Engl J Med 1994; 331:496-501.[Abstract/Free Full Text]
  7. Serruys PW, de Jaegere P, Kiemeneji I, et al. A comparison of balloon-expandable stent implantation with balloon angioplasty in patients with coronary artery disease: Benestent Study Group. N Engl J Med 1994; 331:489-495.[Abstract/Free Full Text]
  8. Serruys PW, Emanuelsson H, van der Giessen W, et al. Heparin-coated Palmaz-Schatz stents in human coronary arteries: early outcome of the Benestent-II pilot study. Circulation 1996; 93:412-422.[Abstract/Free Full Text]
  9. Erbel R, Haude M, Höpp HW, et al. Coronary-artery stenting compared with balloon angioplasty for restenosis after initial balloon angioplasty: Restenosis Stent (REST) Study Group. N Engl J Med 1998; 339:1672-1678.[Abstract/Free Full Text]
  10. Antoniucci D, Valenti R, Santoro GM, et al. Restenosis after coronary stenting in current clinical practice. Am Heart J 1998; 135:510-518.[Medline]
  11. DiMario C, Reimers B, Almagor Y, et al. Procedural and follow-up results with a new balloon expandable stent in unselected lesions. Heart 1998; 79:234-241.[Abstract/Free Full Text]
  12. De Gregorio J, Kobayashi Y, Albiero R, et al. Coronary artery stenting in the elderly: short-term outcome and long-term angiographic and clinical follow-up. J Am Coll Cardiol 1998; 32:577-583.[Abstract/Free Full Text]
  13. Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M, Detrano R. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol 1990; 15:827-832.[Abstract]
  14. Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease: report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association. Circulation 1975; 51(suppl 4):5-40.[Medline]
  15. Jeremias A, Kutscher S, Haude M, et al. Nonischemic chest pain induced by coronary interventions. Circulation 1998; 98:2656-2658.[Abstract/Free Full Text]
  16. Stanford W, Brundage BH, MacMillan R, et al. Sensitivity and specificity of assessing coronary bypass graft patency with ultrafast computed tomography: results of a multicenter study. J Am Coll Cardiol 1988; 12:1-7.[Abstract]
  17. Bateman TM, Gray RJ, Whiting JS, et al. Prospective evaluation of ultrafast cardiac computed tomography for determination of coronary bypass graft patency. Circulation 1987; 75:1018-1024.[Abstract/Free Full Text]
  18. Stanford W, Rooholamini SA, Rumberger J, et al. Evaluation of coronary bypass graft patency by ultrafast computed tomography. J Thorac Imaging 1988; 3:52-55.[Medline]
  19. Nyman M, Schwartz R, Breen J, Garratt K, Holmes D. Ultrafast computed tomographic scanning to assess patency of coronary artery stents in bypass grafts. Mayo Clin Proc 1993; 68:1021-1023.[Medline]
  20. Schimpf S, Sehnert C, Schmermund A, Erbel R, Seibel R, Groenemeyer D. Noninvasive perfusion measurements in stents in coronary arteries with electron beam tomography (abstr). Radiology 1996; 201(P):207.[Abstract/Free Full Text]
  21. Schmermund A, Haude M, Baumgart D, et al. Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography. Eur Heart J 1996; 17:1546-1553.[Abstract/Free Full Text]
  22. Pump H, Schimpf S, Moehlenkamp S, et al. Assessment of stent patency in coronary arteries using electron beam computed tomography (abstr). Radiology 1997; 205(P):460.
  23. Rumberger JA. Limitations of ultrafast computed tomography. In: Stanford W, Rumberger JA, eds. Ultrafast computed tomography in cardiac imaging: principles and practice. Mt Kisco, NY: Futura, 1992; 337-340.
  24. Stanford W, Krachmer J, Galvin JR. Ultrafast computed tomography in assessing coronary bypass grafts. Am J Cardiac Imaging 1991; 5:21-28.[Medline]
  25. Moshage EL, Achenbach S, Seese B, Bachmann K, Kirchgeorg M. Coronary artery stenoses: three-dimensional imaging with electrocardiographically triggered contrast agent–enhanced, electron-beam CT. Radiology 1995; 196:707-714.[Abstract/Free Full Text]
  26. Achenbach S, Moshage W, Bachmann K. Detection of high-grade restenosis after PTCA using contrast-enhanced electron beam CT. Circulation 1997; 96:2785-2788.[Abstract/Free Full Text]
  27. Achenbach S, Moshage W, Ropers D, Nossen J, Daniel WG. Value of electron beam computed tomography for the noninvasive detection of high-grade coronary artery stenoses and occlusions. N Engl J Med 1998; 339:1964-1971.[Abstract/Free Full Text]



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