- Poster presentation
- Open Access
4D flow for accurate assessment of complex flow distribution
© Meadows et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Left Subclavian Artery
- Left Vertebral Artery
- Branch Pulmonary Artery
- Gradient Echo Pulse Sequence
- Blood Flow Analysis
To demonstrate that 4D flow can provide fast, accurate, and complete data sets to determine differential blood flow in patients with complex distributions of flow.
Patients with abnormal vasculature, particularly those with congenital heart disease, often have complex distribution of flow. This distribution of flow is often clinically relavent. The choice of 2D phase contrast flow planes is often difficult and labor intensive. As a result, studies may be completed without collection of the data necessary to determine flow distribution. 4D flow techniques permit the collection of temporally-resolved 3D data sets of the central systemic and pulmonary vasculature in a single acquisition. Complete data acquisition is guaranteed and appropriate planes can be chosen during post processing.
Employed was a temporally-resolved, 3D-phase contrast technique (4D flow), optimized for blood flow analysis in the thoracic vasculature. Data was acquired using an RF-spoiled 3D gradient echo pulse sequence with velocity encoding in 3 spatial directions. All measurements were performed on a 1.5 T clinical scanner (Signa CV/I, GE, Milwaukee, WI) using an 8-channel cardiac coil. Scan parameters were as follows: VENC = 160–200 cm/s; fractional FOV = 300 × 270 mm2, slab thickness = 78 mm, and matrix = 256 × 192 × 30 yielding a spatial resolution of 1.17 × 1.56 × 2.60 mm3. Within each cardiac cycle, the in-plane phase encode value was held constant while 4 slice-encoding phase encodes are acquired to encode all flow directions. Parallel imaging (GRAPPA) with an acceleration factor of 2 was used. Scan times ranged from 12–16 minutes depending on heart rate. Retrospective EKG gating was used to resolve 20 time frames through the cardiac cycle yielding a temporal resolution of 50–80 msec. Respiratory compensation was employed. The raw data was reconfigured for EnSight visualization (CEI Inc., Apex, NC). Navigation within the 3D data set allows retrospective placement of 2D planes perpendicular to the vessel of interest. One normal control subject and 3 subjects with complex anatomy were enrolled. For each subject, a 4D flow data set was obtained.
4D flow provides fast, accurate and complete assessment differential blood flow in patients with complex anatomy and physiology. Navigation within the 4D flow data set allows retrospective placement of cut planes without being hindered by the prospective prescription of traditional 2D flow techniques.
This article is published under license to BioMed Central Ltd.