MR Velocity Mapping Measurement of Renal Artery Blood Flow in Patients with Impaired Kidney Function

Abstract

Renal blood flow (RBF) was measured in 9 patients with chronic impaired kidney function using MR velocity mapping and compared to PAH clearance and 99mTc-DTPA scintigraphy. An image plane suitable for flow measurement perpendicular to the renal arteries was chosen from 2-dimensional MR angiography. MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated by 99mTc-DTPA scintigraphy. A reduction of RBF was found, and there was a significant correlation between PAH clearance multiplied by 1/(1-hematocrit) and RBF determined by MR velocity mapping. Furthermore, a significant correlation between the distribution of renal function and the percent distribution of RBF was found.

Evaluation of Renal Blood Flow and Oxygenation in CKD Using Magnetic Resonance Imaging

“…Our finding of reduced total renal blood flow in CKD is in accordance with previous studies, 20,23,24 but shrinkage of the kidneys means that renal artery blood flow per kidney volume is preserved. However, such a correction may be partly erroneous because regional perfusion varies considerably and cortical and medullary tissue may not necessarily lose volume to the same degree.…”

Renal arterial blood flow measurement by breath-held MRI: Accuracy in phantom scans and reproducibility in healthy subjects

“…Generally good correlation was shown of MRI with “gold standard” methods for measurement of total or single-kidney RBF, including para-amino hippurate clearance 11,12,14,16,18 , Doppler ultrasound flow probe measurements 13 , or 99m Tc-DTPA scintigraphy 18 . A comprehensive overview, however, of the reliability of current technique for breath-held renal blood flow measurement by MRI, including all above-mentioned technological improvements, is not available in the literature.…”

“…Furthermore, SNR has improved greatly by use of phased-array receiver coil technology, and vector electro-cardiographic techniques 10 greatly improved synchronization of the scans with the cardiac cycle. Where just over a decade ago bilateral RBF imaging alone required 45-130 minutes 12,18 , it currently requires only about 10-15 minutes including flow plane scouting, comfortably allowing inclusion of RBF measurements in 1-hour scan slots. Alternative methods for RBF measurement by MRI are concurrently being explored including quantification of first-pass Gd-contrast perfusion 19 , but these technologies is still under development.…”

“…Validation studies for RBF measurement by phase velocity MRI have been reported at various stages of technological maturity 11-18,20,21 , highlighting the importance of several technical advancements. Generally good correlation was shown of MRI with “gold standard” methods for measurement of total or single-kidney RBF, including para-amino hippurate clearance 11,12,14,16,18 , Doppler ultrasound flow probe measurements 13 , or 99m Tc-DTPA scintigraphy 18 .…”

Renal artery blood flow: quantification with breath-hold or respiratory triggered phase-contrast MR imaging

“…Several published reports show reliable flow measurements using MR techniques without respiratory synchronization [19,21,24,25], whereas others identify respiratory motion as a significant potential source of error in quantitative flow assessment in the renal arteries [20,22,23]. This contrast could be related to differences in the location of the parasagittal imaging plane with respect to the aorta, since respiration is likely to have a more significant influence on motion of the renal vessels in the periphery than in their central segment.…”