Myocardial perfusion after angioplasty in patients suspected of having single-vessel coronary artery disease: improvement detected at rest-stress first-pass perfusion MR imaging--initial experience

Pharmacological stress cardiovascular magnetic resonance

Over the past decade, cardiovascular magnetic resonance (CMR) has evolved into a cardiac stress testing modality that can be used to diagnose myocardial ischemia using intravenous dobutamine or vasodilator perfusion agents such as adenosine or dipyridamole. Because CMR produces high-resolution tomographic images of the human heart in multiple imaging planes, it has become a highly attractive noninvasive testing modality for those suspected of having myocardial ischemia. The purpose of this article is to review the clinical, diagnostic, and prognostic utility of stress CMR testing for patients with (or suspected of having) coronary artery disease.

Inter-observer variability of visual analysis of "stress"-only adenosine first-pass myocardial perfusion imaging in relation to clinical experience and reading criteria

To assess the inter-observer agreement of adenosine “stress”-only visual analysis of perfusion MR images in relation to experience and reading criteria. 106 adenosine perfusion MR examinations out of 350, 46 consecutive positive examinations and 60 randomly selected negative examinations were visually analysed by three individual readers (two residents and a technician) with different levels of experience. Readings (blinded for any information) were compared with the reading of an expert radiologist. After a month the examinations were presented again (randomly) without knowledge regarding the first readings. This time readings were performed with the systematical use of reading criteria. Agreement with the expert reading was good for the most experienced resident (k = 0.88). Kappa was 0.48 for the least experienced, and 0.57 for the technician. After the second systematical reading inter-observer agreement increased to 0.9, 0.68 and 0.77 respectively. Overall kappa increased from 0.59 to 0.71. The use of reading criteria significantly improved the performance of the least experienced reader (P = 0.01). Visual analysis of adenosine “stress”-only first-pass perfusion MR images has moderate to very good agreement. Performance is experience related, but the systematic use of reading criteria significantly increased performance for the least experienced observer.

Combined assessment of myocardial perfusion and late gadolinium enhancement in patients after percutaneous coronary intervention or bypass grafts: a multicenter study of an integrated cardiovascular magnetic resonance protocol

OBJECTIVES

We sought to assess the accuracy of an integrated cardiac magnetic resonance (CMR) protocol for the diagnosis of relevant coronary artery or bypass graft stenosis in patients with suspected coronary artery disease (CAD) or with previously performed percutaneous coronary intervention (PCI) or coronary bypass graft surgery (CABG).

BACKGROUND

CMR is suitable for diagnosing inducible myocardial ischemia in patients with suspected CAD and has been proven to be a helpful diagnostic tool for decision of further treatment. However, little is known about its diagnostic accuracy in patients with known CAD who previously were treated by PCI or CABG.

METHODS

A total of 477 patients with suspected CAD, 236 with previous PCI, and 110 after CABG referred for coronary X-ray angiography (CXA) underwent an integrated CMR examination before CXA. Myocardial ischemia was assessed using first-pass perfusion after vasodilator stress with adenosine (140 microg/kg/min for 3 min) using gadolinium-based contrast agents (0.1 mmol/kg). Late gadolinium enhancement (LGE) was assessed 10 min after a second contrast bolus.

RESULTS

CXA demonstrated a relevant coronary vessel stenosis (> or =70% luminal reduction) in 313 (38%) patients using quantitative coronary analysis. The combination of CMR perfusion and LGE assessment for detecting a relevant coronary stenosis in patients with suspected CAD yielded sensitivity and specificity of 0.94 and 0.87, in PCI patients 0.91 and 0.90, and in CABG patients 0.79 and 0.77, respectively.

CONCLUSIONS

A combined CMR protocol for the assessment of myocardial perfusion and LGE is feasible for the detection of relevant coronary vessel stenosis even in patients who previously were treated by PCI or CAG in a routine clinical setting. However, diagnostic accuracy is reduced in patients with CABG. This could be due to different flow and perfusion kinetic. Further studies are needed to optimize the clinical protocols especially in post-surgical patients.

MR myocardial perfusion imaging with k-space and time broad-use linear acquisition speed-up technique: feasibility study

The purpose of this study was to prospectively evaluate the diagnostic accuracy of a cardiovascular magnetic resonance (MR) k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) accelerated perfusion sequence for depicting clinically relevant coronary artery disease (CAD), with use of coronary angiography as the reference standard. The local ethics committee approved this study, and informed consent was obtained from 40 patients (28 men, 12 women; mean age, 61 years +/- 8 [standard deviation]) scheduled for coronary catheterization. A balanced steady-state free precession pulse sequence (2.6 x 2.6 x 10 mm) with a net k-t acceleration factor of 3.8 (repetition time msec/echo time msec, 3.2/1.6; flip angle, 50 degrees ) was applied. Visual analysis of perfusion images and quantitative analysis of signal-time curves obtained in the myocardium were performed by using segmental myocardial upslope, peak enhancement, and their respective ratios. Visual analysis revealed sensitivity, specificity, and diagnostic accuracy of 86%, 78%, and 83%, respectively, in the detection of coronary stenoses with at least 50% luminal narrowing. Significant (P < .05) changes between ischemic and remote segments could be shown for all perfusion indexes applied. Use of myocardial perfusion imaging with k-t BLAST for accelerated data acquisition is feasible in the identification of patients with substantial CAD (coronary stenosis >or= 50%).

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/245/3/863/DC1.

Magnetic resonance first pass perfusion imaging for detecting coronary artery disease

Magnetic resonance first pass perfusion imaging can be used to detect abnormalities in myocardial blood flow. This technique involves imaging the first pass of gadolinium based contrast through the myocardium. Images are initially read qualitatively for areas of reduced signal intensity. Additionally, at our institution a quantitative method is applied that can aid both detection and diagnosis of perfusion defects. This method involves fitting the myocardial signal intensity curves and then calculates absolute myocardial blood flow. Our approach to first pass perfusion imaging will be reviewed. Magnetic resonance first pass perfusion imaging has a complimentary role with coronary angiography either non-invasively using CT or with catheterization. Perfusion imaging defines the physiology and angiography in the anatomy of coronary artery disease.