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Research Papers

Real-time assessment of in vivo renal ischemia using laser autofluorescence imaging

[+] Author Affiliations
Jason T. Fitzgerald, Andromachi Michalopoulou, Christopher D. Pivetti

University of California, Davis Medical Center, Department of Surgery, Sacramento, California 95817

Rajesh N. Raman

University of California, Davis, Department of Applied Science, Davis, California

Christoph Troppmann

University of California, Davis Medical Center, Department of Surgery, Sacramento, California 95817

Stavros G. Demos

Lawrence-Livermore National Laboratory, Livermore, California and University of California, Davis Medical Center, Department of Urology, Sacramento, California 95817

J. Biomed. Opt. 10(4), 044018 (August 18, 2005). doi:10.1117/1.1993327
History: Received July 21, 2004; Revised January 30, 2005; Accepted March 30, 2005; Published August 18, 2005
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Potentially transplantable kidneys experience warm ischemia, and this injury is difficult to quantify. We investigate optical spectroscopic methods for evaluating, in real time, warm ischemic kidney injury and reperfusion. Vascular pedicles of rat kidneys are clamped unilaterally for 18 or 85min, followed by 18 or 35min of reperfusion, respectively. Contralateral, uninjured kidneys serve as controls. Autofluorescence and cross-polarized light scattering images are acquired every 15s using 335nm laser excitation (autofluorescence) and 650±20nm linearly polarized illumination (light scattering). We analyze changes of injured-to-normal kidney autofluorescence intensity ratios during ischemia and reperfusion phases. The effect of excitation with 260nm is also explored. Average injured-to-normal intensity ratios under 335nm excitation decrease from 1.0 to 0.78 at 18min of ischemia, with a return to baseline during 18min of reperfusion. However, during 85min of warm ischemia, average intensity ratios level off at 0.65 after 50min, with no significant change during 35min of reperfusion. 260nm excitation results in no autofluorescence changes with ischemia. Cross-polarized light scattering images at 650nm suggest that changes in hemoglobin absorption are not related to observed temporal behavior of the autofluorescence signal. Real-time detection of kidney tissue changes associated with warm ischemia and reperfusion using laser spectroscopy is feasible. Normalizing autofluorescence changes under 335nm using the autofluorescence measured under 260nm excitation may eliminate the need for a control kidney.

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© 2005 Society of Photo-Optical Instrumentation Engineers

Citation

Jason T. Fitzgerald ; Andromachi Michalopoulou ; Christopher D. Pivetti ; Rajesh N. Raman ; Christoph Troppmann, et al.
"Real-time assessment of in vivo renal ischemia using laser autofluorescence imaging", J. Biomed. Opt. 10(4), 044018 (August 18, 2005). ; http://dx.doi.org/10.1117/1.1993327


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