Abstract 1776: Effect of Radiation Dose-Reduction Strategies for Cardiovascular Computed Tomography Scans of Aortic Coarctation
Background: Cardiovascular computed tomography (CCT) accurately displays the anatomy and surrounding structures in patients with coarctation of the aorta (CoA). Late onset complications are of concern in these patients and thus require lifelong serial monitoring.
Objective: To implement a radiation reduction protocol for CoA imaging with CCT that decreases the effective dose without compromising image quality or diagnostic accuracy.
Methods: Twenty-two consecutive patients with a history of CoA were evaluated. The first eleven patients were scanned using a traditional tube voltage of 120kVp. The next eleven patients had scans using a new protocol, using a reduced tube voltage of 100kVp. Electrocardiographic tube current modulation was used in all studies. Quantitative and qualitative image parameters were used to evaluate both groups blinded to technique.
Results: The average age was 32±10 years. The mean tube output for the 120- and 100-kVp group was 792±37 mAs vs. 605±42 mAs, respectively. Patients in the 100 kVp arm had borderline lower BMI: 24.5 vs. 27.8 kg/m2 (p=.07). This resulted in mean dose-length product of 1219 mGy·cm vs. 534 mGy·cm. The average effective radiation doses for the 120kVp and 100kVp groups were 17.1 mSv and 7.61 mSv, respectively (p<0.001). There was higher noise in the 100kVp group, 38 vs. 29 HU (p=0.01). However, the signal-to-noise and contrast-to-noise ratios were comparable. Qualititative image evaluation indicated all cardiovascular structures were adequately visualized in all patients regardless of radiation dose.
Conclusions: Implementation of a low-dose protocol significantly reduces radiation without affecting image quality in young adults with CoA undergoing CCT. As such patients often require serial imaging with ionizing radiation to evaluate their anatomy; this protocol should be considered for routine use in this population.