Purpose. The extent of acute tubular necrosis (ATN) in renal tubules may provide valuable prognostic data regarding post-transplant renal function of donor kidneys. We used a new, noninvasive, real-time imaging modality termed optical coherence tomography (OCT) to assess the degree of ATN in donor kidneys. OCT is similar to ultrasound, but uses echo delay of light, instead of sound, to produce images. It is safer than X-ray, less expensive than MRI, and gives higher resolution images than ultrasound.

Methods. Consecutive living donor kidneys, removed laparoscopically, were imaged using a hand-held OCT probe while ex-vivo (sterile UW solution on ice) and in-situ following reimplantation in recipient. 4-5 layers of uriniferous tubules and glomeruli beneath the capsule were well visualized. Ex-vivo imaging provided a holistic evaluation. After revascularization, doppler OCT detected renal blood flow in addition to morphologic features. Mannitol/lasix were given prior to cross-clamp. Post-transplant renal function (Cr) was monitored.

Results. 15 patients were imaged (average age recipients = 47.1y, donors = 43.2y). Average cold and warm ischemic times were 40.8m and 38.7m. All kidneys had excellent doppler signals in-situ. 3 had open tubules both ex-vivo and in-situ. All 3 of these patients had Cr that normalized within one week (1.1, 0.9, 0.9). One patient had closed tubules both before and after reimplantation, and the Cr never normalized, remaining at 2.69 on post-op day 7. This 53 yo donor had no significant findings on preop evaluation. The remaining 11 patients had closed tubules ex-vivo, and open tubules only in-situ with varying results at one week postop, although all currently have Cr < 2.0.

Conclusions. Donor kidneys with patent tubule lumens both prior to and following revascularization had the best post-transplant renal function. Although the n was small, when tubules appeared shrunken or lost due to ischemic damage to the lining cells (ATN), post-transplant function was not optimal. Thus far, we have focused on living donor kidneys, so there have been few marginal kidneys to study. In the future, we will extend to animal studies and cadaveric organs, and increase our understanding of how this assay can help evaluate donors. OCT is an easy technique, and may provide important prognostic information when assessing donor kidneys in the future.

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