Expert Opinion Computed Tomography versus Magnetic Resonance Imaging for Young Adults With Congenital Heart Disease Phillip M. Boiselle, MD, Jens Bremerich, MD, Albert de Roos, MD, S. Bruce Greenberg, MD, and Karen Ordovas, MD Advances in cardiac computed tomography (CT) and magnetic resonance imaging (MRI) have expanded the noninvasive diagnostic imaging capabilities for evaluating a wide variety of congenital and acquired cardiac disorders. Young adults with congenital heart disease represent an important subgroup of cardiac patients with a relatively unique set of indications for cross-sectional imaging. The decision of whether to pursue CT or MRI in these patients can be challenging. We thus asked leading experts in the ﬁeld to answer the following question:
“Which test is better for evaluating congenital heart disease in young adults—CT or MRI?” Strengths of CT are submillimeter resolution, fast acquisition in emergencies and in patients with limited capacity to cooperate, availability 24/7 in many institutions, high sensitivity/speciﬁcity for calciﬁcations and visibility of extracardiac shunts or conduits. Radiation exposure is an issue of decreasing relevance, since low-dose CT protocols are now available. MRI, on the other hand, provides relevant information on cardiac physiology such as myocardial function, perfusion, pulmonary circulation and ﬂow. A patient with palliated pulmonary atresia arriving at 2 am in the emergency room with acute worsening of cyanosis needs CT. The same patient presenting with gradual worsening of shortness of breath needs MRI to assess ventricular function and pulmonary circulation for therapy planning. There is no “better” test—CT and MRI are complementary modalities.
Jens Bremerich, MD Basel, Switzerland The indications for CT and MRI in patients with congenital heart disease are evolving. A primary concern is to avoid radiation dose as much as possible. Although CT technology allows for lowering radiation dose consistently, MRI will be preferred depending on the clinical question to be answered, patient age and requirements for sedation. CT allows volume coverage with higher spatial resolution than MRI, fast speed and anatomic information on airways, lungs and extracardiac vasculature. MRI techniques allow volume coverage similar to CT, but are more versatile than those oﬀered by CT (e.g. ﬂow and 4D dynamics). MRI is preferred owing to lack of radiation exposure, need for follow-up, providing ﬂow and dynamic information.
Albert de Roos, MD Leiden, Netherlands The ability to evaluate both morphology and function makes MRI the preferred imaging modality. The most common reason for imaging young adults in my practice is the follow-up of previously treated congenital heart disease and the most common indication is repaired tetralogy of Fallot. Pulmonary valve regurgitation secondary to prior pulmonary stenosis surgery or angioplasty is also common. Both require evaluation of cardiac function and ventricular volume quantiﬁcation as well as morphology. Aortic valvular disease and coarctation are also common indications that beneﬁt from ﬂow analysis. Finally, the utility of MRI to evaluate cardiomyopathies is of increasing importance. A recent study showing DNA breaks associated with MRI imaging suggests that the lack of ionizing radiation is no longer a clear advantage for MRI.
S. Bruce Greenberg, MD Little Rock, AR, USA Most young patients with congenital heart disease are imaged for assessment of postoperative complications, hemodynamic impact of residual lesions and identiﬁcation of prognostic indicators. MRI is ideal to delineate postoperative anatomy, quantify ventricular volumes and function, and residual shunts. Flow quantiﬁcation allows for detecting and monitoring valvular regurgitation, and measuring pulmonary-to-systemic ﬂow ratios, not feasible with CT. MRI is particularly suitable for imaging young adults who need serial imaging, given the absence of radiation. CT is an alternate imaging method most applicable for anatomic delineation. When CT is used for ventricular function quantiﬁcation, retrospective cardiac gating must be used, which increases the radiation exposure signiﬁcantly. CT is preferable when there is contraindication for MRI, or if there is a speciﬁc concern for in-stent stenosis.
Karen Ordovas, MD San Francisco, CA, USA The authors declare no conﬂicts of interest. Copyright r 2013 by Lippincott Williams & Wilkins
J Thorac Imaging
Volume 28, Number 6, November 2013