MR flow measurements for assessment of the pulmonary, systemic and bronchosystemic circulation: Impact of different ECG gating methods and breathing schema
Received 15 May 2006; received in revised form 24 August 2006; accepted 28 August 2006.
Abstract
Purpose
Different ECG gating techniques are available for MR phase-contrast (PC) flow measurements. Until now no study has reported the impact of different ECG gating techniques on quantitative flow parameters. The goal was to evaluate the impact of the gating method and the breathing schema on the pulmonary, systemic and bronchosystemic circulation.
Material and methods
Twenty volunteers were examined (1.5T) with free breathing phase-contrast flow (PC-flow) measurements with prospective (free-prospective) and retrospective (free-retrospective) ECG gating. Additionally, expiratory breath-hold retrospective ECG gated measurements (bh-retrospective) were performed. Blood flow per minute; peak velocity and time to peak velocity were compared. The clinically important difference between the systemic and pulmonary circulation (bronchosystemic shunt) was calculated.
Results
Blood flow per minute was lowest for free-prospective (6l/min, pulmonary trunc) and highest for bh-retrospective measurements (6.9l/min, pulmonary trunc). No clinically significant difference in peak velocity was assessed (82–83cm/s pulmonary trunc, 109–113cm/s aorta). Time to peak velocity was shorter for retro-gated free-retrospective and bh-retrospective than for pro-gated free-prospective. The difference between systemic and pulmonary measurements was least for the free-retrospective technique.
Conclusion
The type of gating has a significant impact on flow measurements. Therefore, it is important to use the same ECG gating method, especially for follow-up examinations. Retrospective ECG gated free breathing measurements allow for the most precise assessment of the bronchosystemic blood flow and should be used in clinical routine.
aDepartment of Pediatric Radiology, Children's Hospital University Heidelberg, Im Neuenheimer Feld 153, 69120 Heidelberg, Germany
bRadiology-E010, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
cDepartment of Radiology, University Hospital Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany
dDepartment of Radiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
eDepartment of Pulmonology, Thoraxklinik Heidelberg, Germany
Corresponding author at: Department of Radiology (E010), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. Tel.: +49 6221 422494; fax: +49 6221 422464.
ABSTRACT