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Published online before print April 3, 2003, 10.1148/radiol.2272011953
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(Radiology 2003;227:440-446.)
© RSNA, 2003

Cardiac Imaging

Coronary Artery Bypass Graft Patency: Assessment with True Fast Imaging with Steady-State Precession versus Gadolinium-enhanced MR Angiography1

Nicholas H. Bunce, MBBS, Christine H. Lorenz, PhD, Anna S. John, MD, John R. Lesser, MD, Raad H. Mohiaddin, MD, PhD and Dudley J. Pennell, MD

1 From the Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, Sydney St, London SW3 6NP, England (N.H.B., A.S.J., R.H.M., D.J.P.); Siemens Medical Solutions, Erlangen, Germany (C.H.L.); and Minneapolis Heart Institute, Minneapolis, Minn (J.R.L.). Received November 29, 2001; revision requested February 13, 2002; final revision received August 30; accepted October 17. Supported by CORDA, the Heart Charity, and the Welcome Trust. Address correspondence to D.J.P. (e-mail: d.pennell@ic.ac.uk).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To compare the accuracy of multisection true fast imaging with steady-state precession (FISP) with gadolinium-enhanced magnetic resonance (MR) angiography for the detection of coronary artery bypass graft patency.

MATERIALS AND METHODS: Twenty-five patients with coronary artery bypass grafts who had recently undergone conventional coronary angiography underwent MR angiography with a 1.5-T system. True FISP angiographic images were acquired in transverse and coronal planes. Coronal cardiac-gated MR angiography was performed with 0.2 mL per kilogram of body weight of gadopentetate dimeglumine injected at a rate of 2 mL/sec. With conventional angiography as the reference standard, the sensitivity, specificity, and accuracy of each technique for the detection of graft patency were determined. Image quality and duration of analysis were determined by two experienced radiologists.

RESULTS: In 25 patients, 46 of 56 venous grafts were patent and 22 of 23 arterial grafts were patent. In all grafts at true FISP angiography, sensitivity for patency was 84% (57 of 68 grafts), specificity was 45% (five of 11 grafts), and accuracy was 78% (62 of 79 grafts). At MR angiography, sensitivity was 85% (58 of 68 grafts), specificity was 73% (eight of 11 grafts), and accuracy was 84% (66 of 79 grafts) (difference not significant). Image quality scores were similar with both techniques, but duration of analysis was significantly longer with MR angiography than with true FISP angiography (29 minutes 24 seconds vs 14 minutes 6 seconds, P < .001).

CONCLUSION: Accuracy for detection of coronary artery bypass graft patency was similar with gadolinium-enhanced MR angiography and true FISP angiography, with a trend toward more false-positive findings for occlusion and reduced visualization of arterial grafts with true FISP angiography.

© RSNA, 2003

Index terms: Coronary angiography, comparative studies, 54.11, 54.121412, 54.12142 • Coronary vessels, bypass graft, 54.457 • Coronary vessels, MR, 54.121412, 54.12142 • Coronary vessels, stenosis or obstruction, 54.11, 54.121412, 54.12142, 54.457 • Magnetic resonance (MR), vascular studies, 54.121412, 54.12142


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Assessment of coronary artery bypass graft patency with cardiovascular magnetic resonance (MR) imaging has been possible for more than 10 years. Spin-echo MR techniques were used in initial attempts, and black-blood images were acquired over several minutes (1–4). Good sensitivity and specificity were obtained, although accuracy can be affected by motion artifacts, and differentiation of a graft from other vascular structures can be difficult (1). With the introduction of gradient-echo MR techniques, it became possible to produce "white-blood" images, which resulted in improved sensitivity and specificity (5–7). Results with both techniques demonstrated patency or occlusion, but the addition of phase-contrast velocity mapping was required to begin to identify stenosis or dysfunction of coronary artery bypass grafts (8,9). In addition, all three methods require considerable patient compliance because of the duration of image acquisition; thus, image quality may be reduced as a result of respiratory and patient motion (10).

The development of MR angiography with the T1-shortening effects of gadolinium-based contrast agents, which enables the acquisition of a complete three-dimensional data set within one breath hold, has resulted in acquisition of high-quality anatomic road maps of coronary artery bypass grafts that are comparable to conventional coronary angiograms (11–14). In these studies, good sensitivity and specificity are reported for the detection of graft patency. However, the three-dimensional acquisition still requires considerable breath-hold duration, typically 20–30 seconds. In addition, accurate coordination of the arterial bolus with acquisition of the center of k space is important to ensure optimal contrast between the coronary artery bypass graft and surrounding structures.

True fast imaging with steady-state precession (FISP) is used to produce white-blood images. Because of short repetition and echo times, it is possible to obtain a multisection or multiphase image within a short breath hold. Because true FISP sequences provide excellent contrast between blood and surrounding structures, they have been used in ventricular function studies to produce MR images of the heart with high temporal and spatial resolution without the need for a contrast agent (15–17). To our knowledge, however, this sequence has not been assessed for the detection of graft patency. Therefore, the purpose of our study was to compare the accuracy of multisection true FISP angiography with that of gadolinium-enhanced MR angiography for the detection of coronary artery bypass graft patency.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Patients
Fifty-five consecutive patients (eight women and 47 men) with a history of coronary artery bypass graft placement who had recently (<9 months) undergone conventional coronary angiography at our institution for the investigation of angina were invited to undergo cardiovascular MR imaging. From those who responded and agreed to participate in the study (35 patients [one woman and 34 men]), we were able to include 25 patients (all men; mean age, 63 years; age range, 39–84 years) who had no contraindication to cardiovascular MR imaging. Of the other 10 patients, three men and one woman did not undergo cardiovascular MR imaging, while six men could not be scheduled within the time period of our study. The mean delay between surgery and conventional coronary angiography was 6.7 years (range, 3 months to 20 years). The exclusion criteria were an inability to give informed consent, the presence of an implanted permanent pacemaker, defibrillator, or intracranial clip; and clinically important claustrophobia or bronchial asthma. The study protocol was approved by our hospital ethics committee, and informed written consent was obtained from each patient.

Cardiovascular MR Imaging Protocol
MR imaging was performed with a 1.5-T system (Sonata; Siemens Medical Systems, Erlangen, Germany), with the patient in a supine position and a surface coil centered over the precordium.

For true FISP angiography, coronal, transverse, and sagittal pilot images were obtained to determine the position of the heart and ascending aorta. Transverse and coronal breath-hold multisection MR images were then acquired from the base of the heart to the subclavian vessels (Fig 1a), with the following parameters: repetition time msec/echo time msec of 3.49/1.75, flip angle of 60°, eight sections per breath hold, section thickness of 4 mm, voxel size of 2.7 x 1.4 x 4.0 mm, temporal resolution of 336 msec, and electrocardiographic gating to early diastole. Breath-hold duration was 8–12 seconds, according to patient heart rate.



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  		Figure 1a. (a) Left: Coronal multisection true FISP angiographic image. Right: Transverse multisection true FISP angiographic image. (b) Left: Coronal MR angiographic slab includes the internal mammary vessels and heart. Right: Transverse MR angiographic slab.

 


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  		Figure 1b. (a) Left: Coronal multisection true FISP angiographic image. Right: Transverse multisection true FISP angiographic image. (b) Left: Coronal MR angiographic slab includes the internal mammary vessels and heart. Right: Transverse MR angiographic slab.

 
For gadolinium-enhanced MR angiography, coronal, transverse, and sagittal pilot images were obtained to determine the position of the heart and ascending aorta. A coronal three-dimensional spoiled gradient-echo MR imaging slab was positioned to include the heart and ascending aorta (Fig 1b), and images were acquired with the following parameters: 2.86/1.04, flip angle of 25°, 32 sections per slab, section thickness of 2 mm, voxel size of 1.6 x 1.6 x 2.0 mm, temporal resolution of 440 msec, and electrocardiographic gating to early diastole. Breath holding was performed during inspiration, and the duration was between 18 and 24 seconds, according to patient heart rate. A precontrast acquisition was performed to enable subsequent image subtraction. Then, a timing sequence was performed to determine the onset of peak gadolinium enhancement in the ascending aorta and the duration of arterial enhancement. For this, a saturation-recovery sequence was used, with one image acquired per second during power injection (Spectris; Medrad, Indianola, Pa) of 2 mL of gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) at a rate of 2 mL/sec into the antecubital vein, followed by a 10-mL normal saline flush at a rate of 2 mL/sec. Then, the coronal three-dimensional sequence was repeated during power injection of 0.2 mL per kilogram of body weight of gadopentetate dimeglumine, followed by a 30-mL normal saline flush at a rate of 2 mL/sec. With this sequence, k space is acquired centrally and is coordinated with peak arterial enhancement, according to the equation by Prince (18).

Conventional Angiography
Conventional coronary and graft angiography was performed in all subjects by using the standard Judkins technique, with selective catheterization of the graft vessels and additional aortography performed at the discretion of the radiologist. The mean delay between cardiovascular MR imaging and conventional coronary angiography was 109 days (range, 4–246 days), and no important cardiac event (myocardial infarction, unstable angina) occurred between the two imaging procedures.

Data Analysis
The standard of reference for detection of patency was conventional coronary angiography. Each image was assessed by an experienced angiographer (J.R.L.), who was aware of the surgery each patient had undergone but who had not performed the angiographic examination. The patency of each bypass graft was determined on the basis of the classification system of the American Heart Association (19).

The cardiovascular true FISP and MR angiographic images were transferred to an off-line personal computer (Dell Computer, Bracknell, UK) and analyzed with software (CMRtools; Imperial College, London, England). The true FISP angiographic images were assessed directly (Fig 2), but the MR angiographic images were reviewed after postprocessing with maximum intensity projection, multiplanar reformation, and volume rendering of the raw data (Fig 3).



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  		Figure 2. Top: Transverse true FISP angiographic image. Bottom: Graphic representation of image. Patent grafts can be seen in their typical anatomic positions: 1 = venous graft to right coronary artery or posterior descending artery, 2 = right internal mammary artery without a graft, 3 = arterial graft from left internal mammary artery to left anterior descending artery, 4 = venous graft to left anterior descending artery or diagonal vessels, and 5 = venous graft to the circumflex artery or obtuse marginal vessels.

 


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  		Figure 3. Top: Three-dimensional volume-rendered image from a coronal MR angiographic data set. Bottom: Graphic representation of image. Patent grafts are seen in their typical anatomic positions: 1 = venous graft to right coronary artery or posterior descending artery, 2 = venous graft to left anterior descending coronary artery or diagonal vessels, and 3 = venous graft to the circumflex or obtuse marginal vessels. Internal mammary arteries are located more anteriorly and are not depicted.

 
Each image was assessed independently by two experienced radiologists (A.S.J., N.H.B.), who were aware of the surgical procedure each patient had undergone but were blinded to the results at conventional coronary angiography. In cases of disagreement, a consensus diagnosis was obtained with a third observer (R.H.M.) as the arbiter. Each graft was visually determined to be patent or occluded. Overall image quality (ie, the presence of blurring and artifacts) was determined with the following scale: score 0, very poor (images insufficient for analysis of graft patency because of blurring or major artifacts); score 1, poor (grafts could barely be detected on the images); score 2, adequate (images sufficient for analysis but with major blurring or artifacts); score 3, good (images sufficient for analysis but with minor blurring or artifacts); and score 4, excellent (no blurring and no artifacts) (14). In addition, the time (in minutes) required for reprocessing and subsequent analysis was determined for both techniques.

Statistical Analysis
Conventional coronary angiography was considered the reference standard. For each cardiovascular MR technique, the sensitivity, specificity, accuracy, and positive and negative predictive values were determined, and 95% CIs were calculated. In addition, the visual scores and duration of analysis were compared by means of the Wilcoxon signed rank test. A P value of less than .05 was considered to indicate a statistically significant difference.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
DISCUSSION
 REFERENCES
 
At surgery, the 25 patients received 56 saphenous vein grafts and 23 arterial grafts (left internal mammary arteries to left anterior descending coronary artery [n = 19], right internal mammary arteries to the first obtuse marginal branch of the circumflex artery [n = 2], right inferior mammary artery to the posterior descending artery [n = 1], and radial artery to the second obtuse marginal branch of the circumflex artery [n = 1]).

At conventional coronary angiography, there were 46 (82%) patent saphenous vein grafts and 22 (96%) patent arterial grafts (Table 1). All 25 patients completed the cardiovascular MR imaging protocol with a mean total imaging time of 37 minutes (range, 30–45 minutes), and there were no adverse events. The mean duration of analysis for true FISP angiographic images was 14.1 minutes, and that for MR angiographic images (including postprocessing time) was 29.4 minutes (P < .001). The mean visual score for true FISP MR images was 2.9, which was reduced as a result of flow artifacts, particularly in patients with aortic valve disease. The mean visual score for MR angiographic images was 3.0 (difference not significant), which was reduced as a result of respiratory artifacts.


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  		TABLE 1. Results of Conventional Angiography in the 25 Patients

 
With true FISP angiography, 41 of 46 saphenous vein grafts and 16 of 22 arterial grafts were correctly identified as patent, and four of 10 saphenous vein grafts and one of one arterial grafts were correctly identified as occluded. With MR angiography, sensitivity was 91% (95% CI: 72%, 99%) and specificity was 100% (95% CI: 3%, 100%) for the detection of arterial graft occlusion and patency. For detection of graft patency, this produced an overall sensitivity of 84% (95% CI: 73%, 92%), specificity of 45% (95% CI: 17%, 77%), and accuracy of 78% (95% CI, 68%, 87%) (Table 2). With MR angiography, 38 of 46 saphenous vein grafts and 20 of 22 arterial grafts were correctly identified as patent, and seven of 10 saphenous vein and one of one arterial grafts were correctly identified as occluded. For the detection of graft patency, this produced an overall sensitivity of 85% (95% CI: 75%, 93%), specificity of 73% (95% CI: 39%, 94%), and accuracy of 84% (95% CI: 74%, 91%) (Table 2). With true FISP and MR angiographic techniques, the positive predictive value for both venous and arterial grafts was high (range, 87–100) (Table 2). There was no significant difference in the accuracy of true FISP angiography and MR angiography ({chi}2 = 0.38, P = .54). Sample images are shown in Figures 4–7.


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  		TABLE 2. Diagnostic Accuracy for True FISP Angiography and MR Angiography for Detection of Patency of Coronary Artery Bypass Grafts

 


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  		Figure 4. Left: Curved multiplanar reformation of an MR angiographic data set shows a patent left internal mammary graft (arrow). Right: Corresponding conventional angiogram confirms patency (arrow).

 


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  		Figure 5a. (a) Top: Transverse three-dimensional rendered MR angiographic image shows a patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery. Bottom: Coronal maximum intensity projection confirms patent graft (arrow). Distal insertion is not demonstrated. (b) Top: Transverse true FISP angiographic image shows corresponding patent saphenous Y graft (arrow). Bottom: Lower transverse true FISP angiographic image shows proximal segments of patent grafts (arrows). (c) Conventional angiogram confirms patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery.

 


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  		Figure 5b. (a) Top: Transverse three-dimensional rendered MR angiographic image shows a patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery. Bottom: Coronal maximum intensity projection confirms patent graft (arrow). Distal insertion is not demonstrated. (b) Top: Transverse true FISP angiographic image shows corresponding patent saphenous Y graft (arrow). Bottom: Lower transverse true FISP angiographic image shows proximal segments of patent grafts (arrows). (c) Conventional angiogram confirms patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery.

 


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  		Figure 5c. (a) Top: Transverse three-dimensional rendered MR angiographic image shows a patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery. Bottom: Coronal maximum intensity projection confirms patent graft (arrow). Distal insertion is not demonstrated. (b) Top: Transverse true FISP angiographic image shows corresponding patent saphenous Y graft (arrow). Bottom: Lower transverse true FISP angiographic image shows proximal segments of patent grafts (arrows). (c) Conventional angiogram confirms patent saphenous Y graft (arrow) to obtuse marginal vessels 1 and 2 of the circumflex artery.

 


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  		Figure 6a. (a) Three-dimensional reconstructions. Left: Surface rendering of MR angiographic data set demonstrates dilated patent venous graft (arrow). Right: Maximum intensity projection also shows the graft (arrow). (b) Three-dimensional rendering of true FISP multisection angiographic data set displays the origin, course, and insertion of the graft (arrow). (c) Conventional coronary angiogram confirms a dilated patent graft (arrow) to the left anterior descending artery.

 


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  		Figure 6b. (a) Three-dimensional reconstructions. Left: Surface rendering of MR angiographic data set demonstrates dilated patent venous graft (arrow). Right: Maximum intensity projection also shows the graft (arrow). (b) Three-dimensional rendering of true FISP multisection angiographic data set displays the origin, course, and insertion of the graft (arrow). (c) Conventional coronary angiogram confirms a dilated patent graft (arrow) to the left anterior descending artery.

 


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  		Figure 6c. (a) Three-dimensional reconstructions. Left: Surface rendering of MR angiographic data set demonstrates dilated patent venous graft (arrow). Right: Maximum intensity projection also shows the graft (arrow). (b) Three-dimensional rendering of true FISP multisection angiographic data set displays the origin, course, and insertion of the graft (arrow). (c) Conventional coronary angiogram confirms a dilated patent graft (arrow) to the left anterior descending artery.

 


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  		Figure 7a. (a) Three-dimensional reconstruction. Rendering of MR angiographic data set shows a patent graft (white arrow) to the posterior descending coronary artery and the native right coronary artery (black arrow). (b) Left: Conventional coronary angiogram shows a patent but diseased native right coronary artery (arrow). Right: Conventional coronary angiogram shows a patent graft (arrow) to the posterior descending coronary artery.

 


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  		Figure 7b. (a) Three-dimensional reconstruction. Rendering of MR angiographic data set shows a patent graft (white arrow) to the posterior descending coronary artery and the native right coronary artery (black arrow). (b) Left: Conventional coronary angiogram shows a patent but diseased native right coronary artery (arrow). Right: Conventional coronary angiogram shows a patent graft (arrow) to the posterior descending coronary artery.

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
REFERENCES
 
Surgical placement of a coronary artery bypass graft is an effective intervention for patients with coronary artery stenoses; the procedure results in reduced angina symptoms and cardiovascular mortality (20–27). However, the 10-year patency rate for saphenous vein grafts is only 40%–60% as a result of a combination of early thrombosis, intimal hyperplasia, and accelerated atherosclerosis (28–30). For mammary artery to internal thoracic artery grafts, survival is better; up to 90% of grafts are patent at 10 years. For an accurate assessment of graft and native vessel patency in patients who at a second presentation have angina, conventional angiography is commonly performed. In this population, because of the altered vascular anatomy and additional vessels to be imaged, there is increased exposure to ionizing radiation and increased toxic reactions (in the kidneys) to contrast agents, which may contribute to the mortality and morbidity risks of the procedure (19,31). A noninvasive accurate method of assessing graft patency may reduce the number of conventional angiographic examinations performed, which would benefit the patient and reduce the overall expenditure.

MR imaging has been used to noninvasively assess coronary artery bypass graft patency with several techniques. Initial investigators used spin-echo sequences to image grafts, with black-blood imaging to detect graft patency. High sensitivities (90%–98%) and lower specificities (72%–90%) are reported (1–4). With spin-echo imaging, it can be difficult to distinguish grafts from native vessels, metal hemostatic clips, bands of mediastinal fibrosis or thickened pericardium, and pericardial collections of air and fluid (1). In addition, it is not possible to identify a graft with stenosis.

With the development of gradient-echo techniques with non–breath-hold two-dimensional sequences with relatively long repetition and echo times that produce white-blood images of patent grafts, sensitivity improved to 88%–98% and specificity improved to 86%–100% (5–7). However, metallic clip artifacts remain a problem, particularly when the internal mammary vessels are assessed and stenosis cannot be assessed. Flow quantification may provide information about vessel dysfunction, stenosis, and graft occlusion, and it has been added in several studies. Hoogendoorn et al documented five occluded grafts that produced high signal intensity on standard gradient-echo MR images and were incorrectly interpreted as patent; with phase-contrast flow mapping, however, all were correctly identified (8). They also noted a biphasic flow pattern in patent grafts and suggested a flow cutoff value of not more than 20 mL/min to determine normal function. Miller et al suggested that flow mapping might overcome some of the problems with metallic clip artifacts associated with mammary artery grafts to enable detection of graft patency (9).

With improvements in MR imager technology, it has become feasible to perform three-dimensional acquisitions with respiratory navigator echoes (32) or during a single breath hold with gadolinium-based contrast agents (11–14). Acquisition of a three-dimensional data set enables postprocessing with multiplanar reformation and maximum intensity projection to identify the grafts. With gadolinium-enhanced MR angiography, it has been possible to assess graft patency with high sensitivity (94%–97%) and good specificity (67%–93%) (11,12), and recently this technique has been used in many centers (11–14).

True FISP is a gradient-echo MR technique that is used to produce white-blood images. Blood pool contrast is significantly improved with it, which allows rapid and accurate acquisition of ventricular function images. To our knowledge, however, it has not been used to assess coronary artery bypass graft patency. Therefore, in this study, we compared true FISP angiography with cardiac-gated three-dimensional gadolinium-enhanced MR angiography. We found that true FISP multisection imaging was a rapid and simple method for assessment of coronary artery bypass graft patency. In addition, the true FISP angiographic images were significantly faster to analyze (14 minutes 6 seconds) than were the MR angiographic images (29 minutes 24 seconds), although the latter includes the postprocessing time for maximum intensity projection, multiplanar reformation, and volume rendering. This additional postprocessing time varies according to the type of reconstruction software used, the experience of the radiologist, and the complexity of the case. With true FISP angiography, 84% of the grafts were correctly identified as patent and 45% were correctly identified as occluded. Image quality was affected by flow-related artifacts, which tended to obscure the origin of the venous grafts in patients with aortic valve disease. In addition, identification of arterial graft patency was low (73%), which may be related to the tortuosity and small size of these vessels. Identification of patency may also be reduced with metallic clip–related artifacts.

Gadolinium-enhanced MR angiography was also simple to perform, although for optimal image quality, it was important that the sequence was coordinated with arrival of the contrast agent bolus into the aorta and that the patients could adequately hold their breath. With MR angiography, 85% of the grafts were correctly identified as patent and 80% were correctly identified as occluded. In particular, MR angiography performed well for the assessment of arterial grafts, which can sometimes be difficult to assess with conventional coronary angiography. Despite use of a cardiac-gated sequence, however, we were unable to reliably assess graft stenosis or stenosis within the distal native vessels. In addition, the gadolinium-based contrast agent used during the MR angiographic examination costs about $150 per patient.

In this study, we found that neither MR angiography nor true FISP angiography by themselves could be considered suitable alternatives to conventional coronary angiography for the investigation of angina in patients with a coronary artery bypass graft. It is possible that the addition of gradient-echo phase-contrast MR imaging may improve the diagnostic accuracy of both techniques, and this should be investigated in future studies. Both true FISP angiography and MR angiography may form part of a combined noninvasive imaging strategy. An initial approach could involve use of transverse and coronal multisection true FISP angiography to obtain pilot images of the grafts, which would allow accurate positioning of the MR angiographic slab. Then, gadolinium-enhanced MR angiography could be performed to obtain an anatomic road map of the grafts and, possibly, the native vessels. Any potential stenoses could be assessed with gradient-echo phase-contrast MR imaging. To be able to identify graft and native vessel stenoses, however, improved temporal and spatial resolution need to be achieved.

This study was performed with volunteer patients who responded to a written invitation to participate in cardiovascular MR research; therefore, the sample population was not randomly selected. In particular, in the invited population, only 15% were women, and in fact no women participated in cardiovascular MR imaging. Therefore, this protocol should be assessed in a larger population that includes patients of both sexes.

In conclusion, overall outcomes with gadolinium-enhanced MR angiography and multisection true FISP angiography were similar in the assessment of coronary artery bypass graft patency. However, results with true FISP angiography included false-positive findings for occlusions and reduced visualization of arterial grafts.


   ACKNOWLEDGMENTS
 
Statistical support was provided by Catey Bunce, DSc, Medical Statistician, Moorfields Eye Hospital, London.


   FOOTNOTES
 
Abbreviation: FISP = fast imaging with steady-state precession

Author contributions: Guarantors of integrity of entire study, N.H.B., D.J.P.; study concepts and design, N.H.B., C.H.L., D.J.P.; literature research, N.H.B., J.R.L.; clinical and experimental studies, N.H.B., C.H.L., R.H.M.; data acquisition, N.H.B., J.R.L., A.S.J.; data analysis/interpretation, N.H.B., C.H.L., A.S.J., J.R.L.; statistical analysis, N.H.B.; manuscript preparation and revision/review, N.H.B., C.H.L., D.J.P.; manuscript definition of intellectual content, N.H.B., R.H.M., C.H.L., D.J.P.; manuscript editing and final version approval, N.H.B., C.H.L.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 

  1. White RD, Caputo GR, Mark AS, Modin GW, Higgins CB. Coronary artery bypass graft patency: noninvasive evaluation with MR imaging. Radiology 1987; 164:681-686.[Abstract/Free Full Text]
  2. Rubinstein RI, Askenase AD, Thickman D, Feldman MS, Agarwal JB, Helfant RH. Magnetic resonance imaging to evaluate patency of aortocoronary bypass grafts. Circulation 1987; 76:786-791.[Abstract/Free Full Text]
  3. Jenkins JPR, Love HG, Foster CJ, Isherwood I, Rowlands DJ. Detection of coronary artery bypass graft patency as assessed by magnetic resonance imaging. Br J Radiol 1988; 61:2-4.[Abstract]
  4. Frija G, Schouman-Claeys E, Lacombe P, Bismuth V, Ollivier JP. A study of coronary artery bypass graft patency using MR imaging. J Comput Assist Tomogr 1989; 13:226-232.[Medline]
  5. White RD, Pflugfelder PW, Lipton MJ, Higgins CB. Coronary artery bypass grafts: evaluation of patency with cine MR imaging. AJR Am J Roentgenol 1988; 150:1271-1274.[Abstract/Free Full Text]
  6. Aurigemma GP, Reichek N, Axel L, Schiebler M, Harris C, Kressel HY. Noninvasive determination of coronary artery bypass graft patency by cine magnetic resonance imaging. Circulation 1989; 80:1595-1602.[Abstract/Free Full Text]
  7. Galjee MA, van Rossum AC, Doesburg T, van Eenige MJ, Visser CA. Value of magnetic resonance imaging in assessing patency and function of coronary artery bypass grafts. Circulation 1996; 93:660-666.[Abstract/Free Full Text]
  8. Hoogendoorn LI, Pattynama PMT, Buis B, van der Geest RJ, van der Wall EE, de Roos A. Non-invasive evaluation of aortocoronary bypass grafts with magnetic resonance flow mapping. Am J Cardiol 1995; 75:845-848.[CrossRef][Medline]
  9. Miller S, Scheule AM, Hahn U, et al. MR angiography and flow quantification of the internal mammary artery graft after minimally invasive direct coronary artery bypass. AJR Am J Roentgenol 1999; 172:1365-1369.[Abstract/Free Full Text]
  10. Taylor AM, Jhooti P, Wiesmann F, Keegan J, Firmin DN, Pennell DJ. MR navigator-echo monitoring of temporal changes in diaphragm position: implications for MR coronary angiography. J Magn Reson Imaging 1997; 7:629-636.[Medline]
  11. Wintersperger BJ, Engelmann MG, Von Smekal A, et al. Patency of coronary bypass grafts: assessment with breath-hold contrast-enhanced MR angiography—value of a non-electrocardiographically triggered technique. Radiology 1998; 208:345-351.[Abstract/Free Full Text]
  12. Vrachliotis TG, Bis KG, Aliabadi D, Shetty AN, Safian R, Simonetti O. Contrast-enhanced breath-hold MR angiography for evaluating patency of coronary artery bypass grafts. AJR Am J Roentgenol 1997; 168:1073-1080.[Abstract/Free Full Text]
  13. Brenner P, Wintersperger B, Von Smekal A, et al. Detection of coronary artery bypass graft patency by contrast enhanced magnetic resonance angiography. Eur J Cardiothorac Surg 1999; 15:389-393.
  14. Kalden P, Kreitner KF, Wittlinger T, et al. Assessment of coronary artery bypass grafts: value of different breath-hold MR imaging techniques. AJR Am J Roentgenol 1999; 172:1359-1364.[Abstract/Free Full Text]
  15. Bloomer TN, Plein S, Radjenovic A, et al. Cine MRI using steady state free precession in the radial long axis orientation is a fast accurate method for obtaining volumetric data of the left ventricle. J Magn Reson Imaging 2001; 14:685-692.[CrossRef][Medline]
  16. Barkhausen J, Ruehm SG, Goyen M, Buck T, Laub G, Debatin JF. MR evaluation of ventricular function: true fast imaging with steady-state precession versus fast low-angle shot cine MR imaging: feasibility study. Radiology 2001; 219:264-269.[Abstract/Free Full Text]
  17. Lee VS, Resnick D, Bundy JM, Simonetti OP, Lee P, Weinreb JC. Cardiac function: MR evaluation in one breath hold with real-time true fast imaging with steady-state precession. Radiology 2002; 222:835-842.[Abstract/Free Full Text]
  18. Prince MR. Gadolinium-enhanced MR aortography. Radiology 1994; 191:155-164.[Abstract/Free Full Text]
  19. Scanlon PJ, Faxon DP, Audet AM, et al. ACC/AHA guidelines for coronary angiography: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Coronary Angiography). J Am Coll Cardiol 1999; 33:1756-1782.[Free Full Text]
  20. Gersh BJ, Kronmal RA, Frye RL, et al. Coronary arteriography and coronary artery bypass surgery: morbidity and mortality in patients ages 65 years or older—a report from the Coronary Artery Surgery Study. Circulation 1983; 67:483-491.[Abstract/Free Full Text]
  21. Saldanha RF, Raman J, Esmore DS, et al. Myocardial revascularisation in patients over seventy five years. J Cardiovasc Surg (Torino) 1988; 29:624-628.[Medline]
  22. Bounous EP, Mark DB, Pollock BG, et al. Surgical survival benefits for coronary disease patients with left ventricular dysfunction. Circulation 1988; 78(3 pt 2):I151-Il57.
  23. Proudfit WL, Kramer JR, Goormastic M, Loop FD. Survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment. Br Heart J 1988; 59:641-647.[Abstract/Free Full Text]
  24. Proudfit WL, Kramer JR, Goormastic M, Loop FD. Ten-year survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment. Am Heart J 1990; 119:942-948.[CrossRef][Medline]
  25. Elefteriades JA, Tolis G, Jr, Levi E, Mills LK, Zaret BL. Coronary artery bypass grafting in severe left ventricular dysfunction: excellent survival with improved ejection fraction and functional state. J Am Coll Cardiol 1993; 22:1411-1417.[Abstract]
  26. Chino M, Satoh T, Kusuhara M, et al. Improvement in long-term prognosis by coronary bypass surgery in patients with 3-vessel coronary disease: a matched case control study. Jpn Circ J 1992; 56:1124-1129.[Medline]
  27. Myers WO, Blackstone EH, Davis K, Foster ED, Kaiser GC. CASS Registry long term surgical survival: Coronary Artery Surgery Study. J Am Coll Cardiol 1999; 33:488-498.[Abstract/Free Full Text]
  28. Kitamura S, Kawachi K, Taniguchi S, et al. Long-term benefits of internal thoracic artery-coronary artery bypass in Japanese patients. Jpn J Thorac Cardiovasc Surg 1998; 46:1-10.
  29. Kitamura S, Kawachi K, Kawata T, et al. Ten-year survival and cardiac event-free rates in Japanese patients with the left anterior descending artery revascularized with internal thoracic artery or saphenous vein graft: a comparative study. Nippon Geka Gakkai Zasshi 1996; 97:202-209. [Japanese].[Medline]
  30. Goldman S, Copeland J, Moritz T, et al. Long-term graft patency (3 years) after coronary artery surgery: effects of aspirin—results of a VA cooperative study. Circulation 1994; 89:1138-1143.[Abstract/Free Full Text]
  31. Chandrasekar B, Doucet S, Bilodeau L, et al. Complications of cardiac catheterization in the current era: a single-center experience. Catheter Cardiovasc Interv 2001; 52:296-297.[CrossRef][Medline]
  32. Kessler W, Achenbach S, Moshage W, et al. Usefulness of respiratory gated magnetic resonance coronary angiography in assessing narrowings > or = 50% in diameter in native coronary arteries and in aortocoronary bypass conduits. Am J Cardiol 1997; 80:989-993.[CrossRef][Medline]



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