Scintigraphic Evaluation of Renal Function in Heart-Beating Brain Death Patients Using Technetium-99m Diethylenetriamine Pentaacetic Acid

Assoc. Prof. Belkis Erbas, MD, Klinikum rechts der Isar der TUM, Nuklearmedizinische Klinik, Ismaninger Strasse 22, D-W8000 München 80 (FRG) Dear Sir, There is a need to define brain death as soon as it occurs, in order to be able to salvage organs for possible transplantation. The ra-dionuclide and radiographic procedures infer brain death on the basis of demonstrated cessation of cerebral blood now [1]. However, radiographic studies cannot be performed at the bedside, are more costly and involve administration of contrast material, with its attendant risks for the patient, an in the case of potential renal transplant donors, for the viability of the transplanted kidney. Radionuclide techniques provide a non-invasive and reliable method for the diagnosis of brain death with no risk for the patients [2, 3]. Radionuclide cerebral angiography, one of the tests used to confirm brain death, can demonstrate the absence of cerebral blood flow during the firstpass study [4]. Several technetium (Tc) compounds, such as 99mTc pertnechnetate, 99mTc diethylenetriamine pentaacetic acid (DTPA) and 99mTc gluco-heptonate, can be used for this purpose. 99mTc-DTPA, used for both cerebral angiography and static brain scintigraphy, has an advantage over the other radionuclide compounds because of its ability to demostrate renal perfusion and glomerular filtration functions at the same time. During the scintigraphic evaluation of cerebral blood flow, we investigated the renal function of 19 patients with brain death confirmed using the clinical findings and brain-stem-evoked auditory potential. Following intravenous administration of 370 mBq (10 mCi) 99mTc-DTPA, cerebral angiography was performed in the first 2 min. Immediately, a gamma camera was placed under the patient to image the renal regions. Renal uptake of 99mTcDTPA was recorded in a matrix size of 256 × 256 with a total count of 500.000 per image during 20 min with 5-min intervals. The symmetry and homogenity of renal accumulation of radiotracer, visualization time of the renal pelvis, patency of the ureters and bladder were examined. Following renal imaging, anterior, posterior and lateral views of the head were recorded in order to complete the brain scan. Fifteen patients had a good function of both kidneys. Three patients showed a significant decrease in renal function bilaterally, and 1 patient had a single kidney. The kidneys of 3 patients with normal renal function who fulfilled the other criteria for renal transplantation were used for