047 Time-Resolved Imaging with Interleaved Stochastic Trajectories (Twist) Improves Magnetic Resonance Angiography in Pediatric Patients

Abstract

BACKGROUND: High spatial resolution contrast-enhanced magnetic resonance angiography (CEMRA) is routinely used to assess vascular morphology. In children, however, faster heart rates and variable arterial-to-venous transit times may produce venous contrast contamination and make CEMRA of the pulmonary artery (PA) and aorta (Ao) difficult using a single dose of gadolinium contrast. A newer technique, known as time-resolved imaging with interleaved stochastic trajectories (TWIST), allows rapid dynamic vascular imaging and may be used to determine optimal contrast arrival time in the great arteries for conventional CEMRA. The aim of this study is to assess TWIST bolus timing for optimizing CEMRA of the great arteries using a single dose of contrast in pediatric patients with congenital heart disease (CHD). METHODS/RESULTS: Patients underwent clinically indicated angiographyonaSiemensAvanto1.5Tsystem.TWISTwasperformed using a 4 mL (2 mmol) test bolus of gadopentetate. TWIST parameterswere:TR,2.3ms;TE,0.8ms;flipangle, 20°; rectangularfieldof view (rFOV), 300 320 mm; matrix, 120 128; 36 partitions; voxel size 2.5 2.5 3.5 mm^3; acceleration factor, 6; measurements, 24; temporal resolution per measurement, 1 second. Test bolus duration, acquisition time, and time to peak signal intensity in the PA and Ao were derived from TWIST datasets and used to perform twosequential conventionalCEMRAacquisitions in thegreatarteries following a single 0.1 mmol/kg contrast bolus. CEMRA parameters were: TR, 3.03 ms; TE, 1.11 ms; flip angle, 25°; rFOV, 332 380 mm;matrix,236 512;120partitions; voxel size0.99 0.99 1.0 mm^3; acceleration factor, 3. TWIST and CEMRA were evaluated for image quality and degree of separation of arterial and venous phases using a 4 point scale. To date, 3 patients (13 1 years; 53 11 kg, heart rate 69 20 / min) have been studied. TWIST yielded separate venous and arterial phases but with a greater degree of vessel-margin blurring. Two sequential CEMRA acquisitions based on TWIST bolus timing resulted in visualization of the great arteries with a distinct PA and Ao phase and without contrast contamination (Figure 1). CONCLUSION: TWIST bolus timing may be used to determine optimal contrast arrival time. This dynamic information allows sequential acquisition of conventional high spatial resolution CEMRA images of the PA and Ao using a single contrast bolus. This technique is valuable in performing angiography in pediatric patients with CHD. 048 THE IMPACT OF FETAL DIAGNOSIS ON DUCT-DEPENDENT CONGENITAL HEART LESIONS