Clinical evaluation of magnetic resonance imaging in coronary heart disease: the CE-MARC study

Abstract

Background: Several investigations are currently available to establish the diagnosis of coronary heart disease (CHD). Of these, cardiovascular magnetic resonance (CMR) offers the greatest information from a single test, allowing the assessment of myocardial function, perfusion, viability and coronary artery anatomy. However, data from large scale studies that prospectively evaluate the diagnostic accuracy of multi-parametric CMR for the detection of CHD in unselected populations are lacking, and there are few data on the performance of CMR compared with current diagnostic tests, its prognostic value and cost-effectiveness.

Methods/design: This is a prospective diagnostic accuracy cohort study of 750 patients referred to a cardiologist with suspected CHD. Exercise tolerance testing (ETT) will be preformed if patients are physically able. Recruited patients will then undergo CMR and single photon emission tomography (SPECT) followed in all patients by invasive X-ray coronary angiography. The order of the CMR and SPECT tests will be randomised. The CMR study will comprise rest and adenosine stress perfusion, cine imaging, late gadolinium enhancement and whole-heart MR coronary angiography. SPECT will use a gated stress/rest protocol. The primary objective of the study is to determine the diagnostic accuracy of CMR in detecting significant coronary stenosis, as defined by X-ray coronary angiography. Secondary objectives include an assessment of the prognostic value of CMR imaging, a comparison of its diagnostic accuracy against SPECT and ETT, and an assessment of cost-effectiveness.

Discussion: The CE-MARC study is a prospective, diagnostic accuracy cohort study of 750 patients assessing the performance of a multi-parametric CMR study in detecting CHD using invasive X-ray coronary angiography as the reference standard and comparing it with ETT and SPECT.

Trial registration: Current Controlled Trials ISRCTN77246133.

Figure 1

Sample cardiac MR images. A) Standard four chamber SSFP view of the heart LV showing both atria and ventricles. B) Vertical long axis late gadolinium enhancement view of the LV showing infarction of the anteroapical wall (arrow). C) Short axis view of the LV showing a perfusion defect in the inferior wall (arrow). D) Typical MR angiogram of a right coronary artery.

Figure 2

CE-MARC cardiac magnetic resonance protocol. The protocol commences with a low-resolution survey scan and localisers. Intravenous adenosine is then administered for approximately 4 minutes at 140 mcg/kg/min, following which first pass stress perfusion imaging is undertaken after the injection of 0.05 mmol/kg dimeglumine gadopentetate. Three dimensional whole heart MR coronary angiography follows the low resolution coronary survey and free-breathing 4 chamber cine (used to assess slice coverage and diastolic coronary rest period respectively). Rest perfusion imaging is undertaken a minimum of 15 minutes following stress perfusion, with a further injection of 0.05 mmol/kg dimeglumine gadopentetate. A final injection of 0.1 mmol/kg dimeglumine gadopentetate is given following this sequence, bringing the overall gadolinium dose to 0.2 mmol/kg. Resting left ventricular function is then assessed, initially for three slices planned identically to the perfusion slices, and then for the entire left ventricle using contiguous slices. A modified Look-Locker inversion time scout is performed prior to late gadolinium enhancement imaging in short axis, vertical long axis and horizontal long axis orientations. Times indicated on the diagram are approximate and sequence blocks are not drawn to scale.