Biomedical subjects

David Foxall

Publications and source records attributed to David Foxall.

2 recordsLinked to original sources

PubMed2003

Inflow effect in first-pass cardiac and renal MRI.

PURPOSE: To estimate the effect of the inflow effect on the arterial input function in vivo in cardiac and renal MR perfusion imaging using fast gradient echo (GRE) sequences and contrast media. MATERIALS AND METHODS: The MR exam protocol was designed to acquire images at different phases of the cardiac cycle. The arterial input was thus influenced by various blood flow velocities. RESULTS: It was found that the inflow effect was negligible in the left ventricle of the heart, while it was significantly higher in the aorta for the kidney perfusion measurement. This was principally due to the higher through-the-plane component of the blood flow velocity in the aorta than in the left ventricle. CONCLUSION: The inflow effect can be neglected in the heart cavity, but should be taken into account in renal perfusion.

Aorta↗

PubMed2003

Inflow effect correction in fast gradient-echo perfusion imaging.

The purposes of this study were to assess the extent of the inflow effect on signal intensity (SI) for fast gradient-recalled-echo (GRE) sequences used to observe first-pass perfusion, and to develop and validate a correction method for this effect. A phantom experiment with a flow apparatus was performed to determine SI as a function of Gd-DTPA concentration for various velocities. Subsequently a flow-sensitive calibration method was developed, and validated on bolus injections into an open-circuit flow apparatus and in vivo. It is shown that calibration methods based on static phantoms are not appropriate for accurate signal-to-concentration conversion in images affected by high flow. The flow-corrected calibration method presented here can be used to improve the accuracy and robustness of the arterial input function (AIF) determination for tissue perfusion quantification using MRI and contrast media.

Blood Flow Velocity↗