Improved MR imaging for patients with implanted cardiac devices

Modified wideband late gadolinium enhancement (LGE) cardiac MRI eliminates hyperintensity artifacts caused by implanted cardiac devices and enables the use of the technique in patients with the devices, according to a study published in the January 2014 issue of Radiology.

Though LGE MRI is important in both the diagnosis and treatment of myocardial diseases, many patients do not undergo cardiac MRI because of safety and image artifact issues that accompany previously implanted cardiac devices. “It has been estimated that up to 75 percent of patients who could benefit from LGE MR imaging are recipients of cardiac devices, such as implantable cardioverter defibrillators (ICDs) and cardiac pacemakers,” wrote the study’s lead author, Shams Rashid, PhD, of the University of California-Los Angeles, and colleagues.

Rashid and colleagues proposed the use of a modified wideband LGE MR imaging technique to overcome hyperintensity image artifacts caused by implanted cardiac devices and tested its viability in their study. The researchers modified the conventional LGE MRI pule sequence through the replacement of the nonselective inversion pulse with a wideband inversion pulse. This modified LGE sequence and the conventional one were evaluated in 12 patients with ICDs who were referred for cardiac MRI.

The researchers found that the ICD catalyzes a two to six kHz frequency shift five to ten centimeters away from the device. Because the off-resonance occurs outside of the typical spectral bandwidth of the nonselective inversion pulse used in conventional LGE, a hyperintensity artifact is produced. When the conventional LGE technique was used, severe and undistinguishable hyperintensity artifacts were created in the anterior and lateral portions of the left ventricular wall. However, these artifacts were eliminated when the wideband LGE sequence was used, in turn allowing for evaluation of myocardial viability.

“Our feasibility study suggests that the technique may enable the successful use of LGE MR imaging in patients with cardiac devices who would otherwise be inaccessible to diagnosis,” wrote the study’s authors. “Further clinical studies are warranted to validate the reliability of the wideband technique in routine clinical practice and to determine whether most or all patients with ICDs who require cardiac MR imaging may now be imaged successfully.”

LGE MRI was also recently shown to stratify risk for patients with non-ischemic cardiomyopathy and potentially provide more information when selecting patients in need of ICDs. To learn more, click here.