SOMATOM Definition Dual Source Scanning

Authors: Suzu Kanzaki MD, Masahiro Higashi MD, Hiroaki Naito MD PhD
Department of Radiology, National Cardiovascular Center, Osaka, Japan

History

This 15-month-old girl had first been referred to the pediatric cardiology department of our center as a newborn with low birth weight (1906 g) and cyanose. She was diagnosed with pulmonary atresia with ventricular septal defect (VSD) and patent ductus arteriosus. Using a synthetic vessel prothesis, a modified Blalock-Taussig shunt was implanted 3 months after birth. An intracardiac corrective surgery and pulmonary arterial reconstruction were performed when the patient was 15 months old. After the surgery, a Dual Source CT scan was taken for follow-up. The patient was lightly sedated by oral medication before the scan and a bolus of 18 ml iodinated contrast agent (370 mgI/ml) was injected. The patient's height was 70 cm, body weight was 6.5 kg, and mean heart rate was 99 bpm (93-101 bpm) during the scan.

Diagnosis

The right ventricular outflow tract was reconstructed using a synthetic vessel graft. The VSD and modified Blalock-Taussig shunt were closed. In the post-surgical follow-up DSCT images, stenoses were detected at the origins of both pulmonary arteries. At the origin of the right pulmonary artery, the images also revealed a flap-like structure. Based on these findings, a catheter intervention was performed 3 months after surgery for both pulmonary stenoses.

Comments

Acceleration of blood flow was observed by Doppler echocardiography in both pulmonary arteries at the anastomosis. Since stenoses were a concern, a CT scan was taken in the early postoperative period. This time, the CT scan was performed with ECG gating to suppress vessel motion artifacts and to allow a precise morphologic evaluation. The Dual Source CT images were of good diagnostic quality. This scan was performed shortly after installation of the Dual Source CT at our center: with more experience, we are now able to reduce the dose for similar scans of pediatric patients by about 2/3.

Fig 1: Left pulmonary artery, reconstructed vessel at right ventrical outflow tract and anastomosis.
Fig 2: Right pulmonary artery, reconstructed vessel at right ventrical outflow tract and anastomosis. A non-contrast enhanced flap-like structure was seen (arrow).

Fig 3 and 4: The morphologies of the stenoses were clearly revealed by DSCT.