Renal blood flow: measurement in vivo with rapid spiral MR imaging

To assess the ability of three cine phase-contrast magnetic resonance (MR) imaging techniques to measure normal human renal blood flow (RBF) in vivo.

Eighteen healthy volunteers were studied with three cine phase-contrast MR imaging techniques: breath-hold, segmented k-space, two-dimensional, Fourier transform technique (ie, time-resolved imaging with automatic data segmentation, or TRIADS); a breath-hold rapid spiral acquisition; and a non-breath-hold rapid spiral acquisition that allowed resolution of both cardiac and respiratory cycles. In each case, total arterial RBF and blood flow per unit of renal volume were calculated. For each subject, RBF was measured with a standard technique of p-aminohippuric acid (PAH)-clearance hematocrit on the same day as the MR imaging examination was performed.

The range of agreement (2 standard deviations, or 95% confidence interval) between RBF measurements obtained with the PAH-clearance hematocrit technique and the various cine phase-contrast techniques varied from +/- 17.6% to +/- 26.5%. The best agreement was obtained with non-breath-hold rapid spiral data, by using data from the end-expiratory phase of respiration.

Findings with cine phase-contrast MR imaging employing rapid spiral acquisition are in good agreement with measurements made with PAH-clearance hematocrit and give the promise of clinical measurements of RBF.