[Determination of the renal blood flow in macro- and microcirculation by means of pulse inversion imaging].
OBJECTIVE
To evaluate whether real-time and intermittent pulse inversion technology (PI) allows the analysis of blood flow in renal macro- and microcirculation.


METHODS
The experiments were performed in a kidney perfusion phantom as an experimental model for the assessment of contrast replenishment in vascular regions of high flow velocity (medulla) and low flow velocity (cortex). During continuous infusion (0.03 ml/min) of Optison, contrast replenishment kinetics were assessed with intermittent PI at high emission power (MI: 1.3, with increasing trigger intervals) and with real-time PI at low emission power (MI: 0.09) at variable renal arterial blood flow (15 - 65 ml/min), using an HDI-5000 ultrasound unit (Philips Medical Systems). Regions of interest were placed in the major arteries of the medulla and the renal cortex to obtain replenishment curves of the macro- and microcirculation. Non-linear curve fitting was performed using the mathematical model y = A (1-e (-beta t)) with A as the parameter describing blood volume and beta as the parameter describing the speed of contrast replenishment.


RESULTS
Replenishment curves could be obtained in all analyzed renal segments. For intermittent and real-time PI a strong linear correlation was found between renal arterial blood flow and A*beta (intermittent PI: cortex: R = 0.97; medulla: R = 0.98; real-time PI: cortex: R = 0.99; medulla: R = 0.96). The differences between the slopes of the regression lines (cortex: high power vs. low power, p = 0.844; medulla: high power vs. low power, p = 0.444) were not significant.


CONCLUSIONS
Intermittent and real-time PI allows the assessment of renal blood flow in different vessel compartments.
Schlosser
T
T
Institut für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Essen. thomas.schlosser@uni-essen.de
Veltmann
C
C
Lohmaier
S
S
Ehlgen
A
A
Kuntz-Hehner
S
S
Tiemann
K
K
Becher
H
H
D000418:Albumins; D000818:Animals; D001783:Blood Flow Velocity; D003287:Contrast Media; D005466:Fluorocarbons; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging*; D007672:Kidney Cortex / Q000098:blood supply / Q000000981:diagnostic imaging; D007679:Kidney Medulla / Q000098:blood supply / Q000000981:diagnostic imaging; D007700:Kinetics; D017078:Laser-Doppler Flowmetry; D008833:Microcirculation; D008863:Microspheres; D008954:Models, Biological; D019047:Phantoms, Imaging; D012079:Renal Circulation; D013552:Swine; D013997:Time Factors; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons