HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kuzo, R. S. Articles by Gerber, T. C. Search for Related Content PubMed PubMed Citation Articles by Kuzo, R. S. Articles by Gerber, T. C. Social Bookmarking                      What's this?

Measurement of Caval Blood Flow with MRI During Respiratory Maneuvers: Implications for Vascular Contrast Opacification on Pulmonary CT Angiographic Studies

¹ Department of Radiology, Mayo Clinic, 4500 San Pablo Rd., Jacksonville, FL 32224.
² Biostatistics Unit, Mayo Clinic, Jacksonville, FL 32224.
³ Division of Cardiovascular Diseases, Mayo Clinic, Jacksonville, FL 32224.

OBJECTIVE. Transient interruption of the contrast bolus has been described as a physiologic artifact that can sometimes result in poor opacification of the pulmonary arteries on pulmonary CT angiographic studies. To better understand the mechanism underlying this artifact, we used velocity-encoded cine MRI to measure flow in the inferior vena cava (IVC) and superior vena cava (SVC) during respiratory maneuvers.

SUBJECTS AND METHODS. Quantitative measurements of SVC and IVC flow per R-R interval were performed on 10 healthy volunteers (six men, four women; median age, 30 years; range, 25-55 years) with a retrospectively ECG-gated velocity-encoded gradient-echo cine sequence on a 1.5-T MRI unit with axial slices at the level of the diaphragm and just below the azygous vein confluence during free breathing, continuous inspiration, breath-hold at end inspiration, Valsalva maneuver, and breath-hold at end expiration.

RESULTS. Median flow during free breathing was 38.9 mL in the SVC and 74.3 mL in the IVC, during continuous inspiration was 43.9 mL in the SVC and 113.7 mL in the IVC, during breath-hold at end inspiration was 31.0 mL in the SVC and 56.1 mL in the IVC, during a Valsalva maneuver was 28.9 mL in the SVC and 53.9 mL in the IVC, and during breath-hold at end expiration was 35.3 mL in the SVC and 61.2 mL in the IVC.

CONCLUSION. MRI measurements showed a significant increase in caval flow during inspiration and a greater relative increase in blood flow in the IVC than in the SVC. For thoracic CT performed with IV contrast enhancement, deep inspiration before scanning leads to a large influx of IVC blood that does not contain contrast medium and dilutes the contrast bolus, causing poor vascular opacification. Avoiding initial inspiration before scanning is suggested as a way to limit the transient interruption of the contrast bolus artifact.

Keywords: cardiopulmonary imaging • contrast media • CT angiography • MRI

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?