Cortical blood-flow in the porcine kidney

Poulsen, E. U.; Jørgensen, Jens Otto Lunde; Madsen, Frank; Djurhuus, J. C.

doi:10.1007/bf00256048

Cited by 11 publications

(5 citation statements)

References 11 publications

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“…were found in the same range as values reported in the literature (0.02-0.05 mL Á mL À1 Á s À1 ) (20). This linear dependence was observed systematically and is consistent with the BHT model.…”

supporting

confidence: 89%

Non‐invasive determination of tissue thermal parameters from high intensity focused ultrasound treatment monitored by volumetric MRI thermometry

Dragonu¹,

Oliveira²,

Laurent

et al. 2009

NMR in Biomedicine

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A method is proposed for estimating the perfusion rate, thermal diffusivity, and the absorption coefficient that influence the local temperature during high intensity focused ultrasound (HIFU) thermotherapy procedures. For this purpose, HIFU heating experiments (N = 100) were performed ex vivo on perfused porcine kidney (N = 5) under different flow conditions. The resulting spatio-temporal temperature variations were measured non-invasively by rapid volumetric MR-temperature imaging. The bio-heat transfer (BHT) model was adapted to describe the spatio-temporal evolution of tissue temperature in the cortex. Absorption and perfusion coefficients were determined by fitting the integrated thermal load (spatial integration of the thermal maps) curves in time with an analytical solution of the BHT equation proposed for single point HIFU heating. Thermal diffusivity was determined independently by analyzing the spatial spread of the temperature in time during the cooling period. Absorption coefficient and thermal diffusivity were found to be independent of flow, with mean and average values of 11.0 +/- 1.85 mm(3) x K x J(-1) and 0.172 +/- 0.003 mm(2) x s(-1), respectively. A linear dependence of the calculated perfusion rate with flow was observed with a slope of 9.20 +/- 0.75 mm(-3). The perfusion was found to act as a scaling term with respect to temperature but with no effect on the spatial spread of temperature which only depends on the thermal diffusivity. All results were in excellent agreement with the BHT model, indicating that this model is suitable to predict the evolution of temperature in perfused organs. This quantitative approach allows for determination of tissue thermal parameters with excellent precision (within 10%) and may thus help in quantifying the influence of perfusion during MR guided high intensity focused ultrasound (MRgHIFU).

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supporting

confidence: 89%

Non‐invasive determination of tissue thermal parameters from high intensity focused ultrasound treatment monitored by volumetric MRI thermometry

Dragonu¹,

Oliveira²,

Laurent

et al. 2009

NMR in Biomedicine

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show abstract

“…This effect can be attributed to the limited spatial coverage of the selected regions of interest for analysis (see Figs 3b and 5b, at later times), which were intentionally restricted to the kidney, although the adjacent tissues contribute to heat evacuation mainly through thermal diffusion. The mean value of the perfusion rate in the renal cortex obtained in vivo without obstruction of the flow was 0.06 mL À1 mL s À1 , in the same range as the values reported in vivo in the literature using a radiotracer (0.02-0.05 mL À1 mL s À1 ) (28). With obstruction of the aorta, the perfusion rate was decreased significantly by 84%, with an estimated average value of 0.009 mL À1 mL s…”

Section: Discussionsupporting

confidence: 50%

In vivo characterization of tissue thermal properties of the kidney during local hyperthermia induced by MR‐guided high‐intensity focused ultrasound

et al. 2010

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The purpose of this study was to evaluate quantitatively in vivo the tissue thermal properties during high-intensity focused ultrasound (HIFU) heating. For this purpose, a total of 52 localized sonications were performed in the kidneys of six pigs with HIFU monitored in real time by volumetric MR thermometry. The kidney perfusion was modified by modulation of the flow in the aorta by insertion of an inflatable angioplasty balloon. The resulting temperature data were analyzed using the bio-heat transfer model in order to validate the model under in vivo conditions and to estimate quantitatively the absorption (α), thermal diffusivity (D) and perfusion (w(b)) of renal tissue. An excellent correspondence was observed between the bio-heat transfer model and the experimental data. The absorption and thermal diffusivity were independent of the flow, with mean values (± standard deviation) of 20.7 ± 5.1 mm(3) K J(-1) and 0.23 ± 0.11 mm(2) s(-1), respectively, whereas the perfusion decreased significantly by 84% (p < 0.01) with arterial flow (mean values of w(b) of 0.06 ± 0.02 and 0.008 ± 0.007 mL(-1) mL s(-1)), as predicted by the model. The quantitative analysis of the volumetric temperature distribution during nondestructive HIFU sonication allows the determination of the thermal parameters, and may therefore improve the quality of the planning of noninvasive therapy with MR-guided HIFU.

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“…Measurements in renal polar areas were avoided because previous experimental investigations using radiolabeled microspheres have documented a significantly lower cortical blood flow in these zones compared with the rest of the cortex in porcine kidneys. Mechanisms responsible for this flow difference could not be defined by the authors (21). Correct probe localization was proved by stable measurement of local tissue temperature and tissue conductivity.…”

Section: Living-related Donor Grafts Versus Cadaveric Graftsmentioning

confidence: 99%

Assessment of renal graft function by perioperative monitoring of cortical microcirculation in kidney transplantation.1

et al. 2003

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Thermodiffusion could be clinically applicable for the perioperative monitoring of renal graft perfusion. Intraoperative reduction of cortical microcirculation has a high predictive value with respect to detection of delayed renal function. Postoperatively, impaired renal microperfusion is associated with acute tubular necrosis. Living-related donor grafts show less microcirculatory alteration than cadaveric kidneys.

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Cortical blood-flow in the porcine kidney

Cited by 11 publications

References 11 publications

Non‐invasive determination of tissue thermal parameters from high intensity focused ultrasound treatment monitored by volumetric MRI thermometry

Non‐invasive determination of tissue thermal parameters from high intensity focused ultrasound treatment monitored by volumetric MRI thermometry

In vivo characterization of tissue thermal properties of the kidney during local hyperthermia induced by MR‐guided high‐intensity focused ultrasound

Assessment of renal graft function by perioperative monitoring of cortical microcirculation in kidney transplantation.1

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