Laurent Huwart MD, Presenter: Nothing to Disclose

Arnaud Mejean MD, Abstract Co-Author: Nothing to Disclose

Lori Bridal PhD, Abstract Co-Author: Nothing to Disclose

Natacha Patey-Mariaud MD, Abstract Co-Author: Nothing to Disclose

Olivier Helenon MD, Abstract Co-Author: Nothing to Disclose

Jean-Michel Correas MD,PhD, Abstract Co-Author: Nothing to Disclose

To evaluate the impact of imaging settings and region-of-interest (ROI) location on the quantification of renal cortical blood flow using an isolated perfused kidney model using contrast-enhanced ultrasonography (CE-US).

After approval by the animal ethics committee, 4 pig kidneys were explanted and connected to an ex-vivo perfusion phantom. A fifty percent diluted solution of SonoVue® (Bracco, Italy) was infused in the venous side of the circuit at 0.5 mL/min. CE-US was performed with an HDI 5000 system (Philips US, USA) using a linear transducer (L7-4) and pulse inversion imaging. Imaging parameters such as mechanical index (MI) and gain were varied (IM: 0.06, 0.09 and 0.12; Gain: 50 and 59). Each kidney was perfused with Celsior® liquid (Imtix Sangstat, France) at different flow rates (30, 50, 70 and 90 mL/min). For each flow rate, destruction – reperfusion kinetics was performed and transferred to a PC through an Ethernet connection. Three different ROIs were set on the anterior and posterior cortex, and on the whole kidney. Signal intensity measurements were performed in linear units using HDI Lab (Philips US, USA). Curve fitting was performed after normalisation of the post-destruction frames using the usual mathematical model y=A(1-e(-Bt)), with A estimated blood volume and B estimated microbubble velocity, and A x B estimated ultrasonic blood flow (EBL). Statistical analysis was performed using an analysis of variance.

A linear relationship was found between the input flow rate defined by the pump outflow and the EBL as determined by CE-US for the posterior and whole kidney ROIs. EBL increased with mechanical index (p<0.05). No significant correlation was found between EBL and the gain values. The replenishment curve obtained from the anterior ROI was not properly fit to the mathematical model, with oversaturation of the signals.

Renal cortical blood flow can be estimated using CE-US. The local acoustic power should be standardized in order to allow appropriated measurements. The location of the ROI has a critical impact on the generation of the replenishment curves, which must be standardised.

J.C.: Dr JM Correas is a consultant for Altana France.

Huwart, L, Mejean, A, Bridal, L, Patey-Mariaud, N, Helenon, O, Correas, J, Quantification of Renal Cortical Perfusion Using Contrast-enhanced Ultrasound: Impact of Imaging Parameters.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4418584.html