PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of thijTexas Heart Institute JournalSee also Cardiovascular Diseases Journal in PMCSubscribeSubmissionsTHI Journal Website
 
Tex Heart Inst J. 2010; 37(3): 316–318.
PMCID: PMC2879211

Cardiovascular Magnetic Resonance Imaging and Computed Tomography

Over the past decade, cardiovascular magnetic resonance imaging (MRI) has emerged as the gold standard for the evaluation of ventricular systolic function, as well as for evaluation and tissue characterization in ischemic and nonischemic cardiomyopathy.1 Cardiovascular MRI is reproducible, having a high spatial resolution, a relatively high temporal resolution, and no geometric assumption. Consequential to advances in both hardware and software, the imaging time is now considerably shorter than ever before.

Delayed-Enhancement MRI

Recently, the introduction of delayed-enhancement (DE) MRI provided physicians with a simple technique for visualizing myocardial scarring and fibrosis with an accuracy and resolution unmatched by other current noninvasive imaging techniques (Fig. 1). Furthermore, DE-MRI does not necessitate the use of pharmacologic stress or ionizing radiation. Various researchers have demonstrated that the extent of DE predicts myocardial functional recovery after revascularization, thereby providing cardiologists and cardiovascular surgeons with a valuable tool in selecting appropriate patients for revascularization. Our group recently demonstrated that after adjustment for important traditional prognosticators, such as ejection fraction and age, the presence and the degree of DE (the higher the degree, the worse) is an independent predictor of all-cause death in patients with and without coronary artery disease.2 Future prospective studies will be required to determine whether DE-MRI can be used as a novel risk-stratification tool for patients with either ischemic or nonischemic cardiomyopathy.

figure 12FF1
Fig. 1 Delayed-enhancement magnetic resonance image from a patient with a history of coronary artery disease and coronary artery bypass surgery who presented with increasing dyspnea on exertion. A predominantly transmural scar (arrowhead) is evident in ...

Cardiovascular MRI versus SPECT and PET

Single-photon-emission computed tomography (SPECT) and positron-emission tomography (PET) are widely used in the clinical assessment of myocardial perfusion and ischemia. In evaluating myocardial perfusion, cardiovascular MRI has the advantage of offering a relatively high in-plane spatial resolution (2–3 × 2–3 mm) that allows physicians to distinguish between subendocardial and transmural perfusion defects (Fig. 2). The recently reported multicenter, multivendor MR-IMPACT trial (Magnetic Resonance Imaging for Myocardial Perfusion Assessment in Coronary Artery Disease) showed that at experienced centers (using a gadolinium dose of 0.1 mmol/kg), cardiovascular MRI performs favorably in comparison with SPECT.3 Because cardiovascular MRI can provide additional ventricular functional and myocardial viability information in the same session, this approach is an attractive “one-stop–service” technique in the evaluation of coronary artery disease.

figure 12FF2
Fig. 2 Adenosine myocardial perfusion images from the same patient as in Figure 1, during adenosine stress (A) and at rest (B). Myocardial perfusion studies at the mid-ventricular level show reversible ischemia (arrowheads) that spares the inferior wall, ...

Multislice Computed Tomography

The past decade has seen a remarkable advance in multislice computed tomography (MSCT), which has evolved from a single-source to a dual-source technique. With the latest 320-slice MSCT, physicians can scan the entire heart in a single heartbeat. Coronary artery calcification (CAC) can be quantified by MSCT. Because CAC indicates the presence of atherosclerosis, even in asymptomatic patients, and predicts future cardiovascular events,4 the evaluation of CAC can identify patients who are at increased risk and can provide further risk stratification (in addition to the Framingham risk score). Multiple studies have consistently shown that MSCT has a high specificity and negative predictive value in the evaluation of coronary artery stenosis, thereby providing an important tool for ruling out obstructive coronary artery disease. However, the presence of anatomic stenosis does not necessarily imply significant functional stenosis. This fact was well illustrated by Meijboom and coworkers5 in a study that compared MSCT with intracoronary fractional-flow-reserve (FFR) analysis. Using an FFR of <0.75 to define a significant stenosis, the researchers found that the sensitivity, specificity, and diagnostic accuracy of quantitative MSCT were 50%, 75%, and 71%, respectively. The presence of intermediate lesions on MSCT frequently necessitates further functional testing. Nevertheless, multiple studies have shown that appropriately selected patients—those who presented at the emergency department and underwent MSCT that showed no obstructive disease—could safely be discharged, which reduced hospital length of stay and costs.

Recent studies have shown that prognostic information can also be obtained from MSCT. Like invasive angiography, MSCT can indicate the extent of underlying arterial stenosis, as well as the number of vessels involved.6 These data are predictive of all-cause death, in addition to cumulative cardiac events. Using state-of-the-art scanners, investigators have also begun to explore, with encouraging results, the role of MSCT in the assessment of myocardial perfusion and myocardial viability.

Footnotes

Address for reprints: Benjamin Y.C. Cheong, MD, Advanced Cardiovascular Imaging, Department of Radiology, MC 2–270, Texas Heart Institute at St. Luke's Episcopal Hospital, 6720 Bertner Ave., Houston, TX 77030

E-mail: moc.hels@gnoehcb

Presented at the 9th Texas Update in Cardiovascular Advancements; Houston, Texas; 4–5 December 2009

Program Director: James T. Willerson, MD

References

1. Pennell DJ, Sechtem UP, Higgins CB, Manning WJ, Pohost GM, Rademakers FE, et al. Clinical indications for cardiovascular magnetic resonance (CMR): Consensus Panel report. Eur Heart J 2004;25(21):1940–65. [PubMed]
2. Cheong BY, Muthupillai R, Wilson JM, Sung A, Huber S, Amin S, et al. Prognostic significance of delayed-enhancement magnetic resonance imaging: survival of 857 patients with and without left ventricular dysfunction. Circulation 2009;120(21):2069–76. [PubMed]
3. Schwitter J, Wacker CM, van Rossum AC, Lombardi M, Al-Saadi N, Ahlstrom H, et al. MR-IMPACT: comparison of perfusion-cardiac magnetic resonance with single-photon emission computed tomography for the detection of coronary artery disease in a multicentre, multivendor, randomized trial. Eur Heart J 2008;29(4):480–9. [PubMed]
4. Shaw LJ, Raggi P, Schisterman E, Berman DS, Callister TQ. Prognostic value of cardiac risk factors and coronary artery calcium screening for all-cause mortality. Radiology 2003; 228(3):826–33. [PubMed]
5. Meijboom WB, Van Mieghem CA, van Pelt N, Weustink A, Pugliese F, Mollet NR, et al. Comprehensive assessment of coronary artery stenoses: computed tomography coronary angiography versus conventional coronary angiography and correlation with fractional flow reserve in patients with stable angina. J Am Coll Cardiol 2008;52(8):636–43. [PubMed]
6. Min JK, Shaw LJ, Devereux RB, Okin PM, Weinsaft JW, Russo DJ, et al. Prognostic value of multidetector coronary computed tomographic angiography for prediction of all-cause mortality. J Am Coll Cardiol 2007;50(12):1161–70. [PubMed]

Articles from Texas Heart Institute Journal are provided here courtesy of Texas Heart Institute