Cardiac CT expands boundaries

Lisa Fratt, Editor, Health Imaging

Since its early days, cardiac CT has served physicians and patients quite well. But some patients have been left off the table. However, recent research might trim the pool of excluded patients.

Take pediatric patients, who can be problematic for a number of reasons, particularly radiosensitivity and high heart rates that can make it difficult to obtain a diagnostic quality CT scan. However, alternatives to cardiac CT for pediatric patients are far from perfect.

Coronary CT angiography (CCTA) is invasive, requires sedation and exposes children to a radiation dose of approximately 3.5 to 5.6 mSv. Similarly, cardiac MR also comes with its fair share of challenges for pint-sized patients. Resolution is lower; and scans may take longer and cost more. In addition, cardiac MR interpretation skills are not widely available.

A recent study suggests cardiac CT may be a viable option. B. Kelly Han, MD, of Children’s Heart Clinic in Minneapolis, and colleagues completed a retrospective analysis of coronary CT exams and found that dual-source CCTA with beta-blockers delivered diagnostic quality images at a median effective age-adjusted radiation dose of 0.97 mSv.

“Our study shows [CCTA] maintained image quality and diagnostic confidence for multiple indications in a pediatric population with a high prevalence of pathology, while further decreasing the radiation dose over previous generation CT scanners,” concluded Han et al.  

Diffuse myocardial fibrosis, which is associated with cardiomyopathies and heart failure, also has presented its share of imaging challenges.

Advances in cardiac MR have delivered the capability to assess diffuse interstitial myocardial fibrosis. However, the exam is not universally available and may be contraindicated among some patients in the target populations, particularly those with pacemakers and implantable cardiac defibrillators.

Thus, Marcelo Souto Nacif, MD, PhD, of the National Institutes of Health in Bethesda, Md., and colleagues developed and tested a cardiac CT method to calculate extracellular volume (ECV) fraction, which is increased in association with diffuse myocardial fibrosis.

The researchers compared the method to cardiac MR-derived measures of ECV and reported good reproducibility of cardiac CT and correlation with cardiac MR ECV values. The findings might open the door to the use of cardiac CT to assess these patients, once again expanding the modality’s boundaries and boosting its value.

How might these results impact your practice? Let us know.

Lisa Fratt, editor
lfratt@trimedmedia.com