Use of radionuclide imaging in the early diagnosis and treatment of renal allograft rejection

Nephrography with radioactive hippuran in transplanted kidneys: interpretation, limitations, and usefulness

A total of 485 nephrographies (NGs) performed on 95 patients in 1982 were analyzed statistically. The different modes of orthoiodine-hippuran (OIH) handling by the transplanted kidneys are summarized by six different basic curve patterns. The formation of these patterns is an effect of the prolongation of the time to the curve maximum, the time to 75% of the maximum, and the time until the intersection of the bladder and kidney curves. Also, intraparenchymal retention of activity leads to changes in the OIH curves. The basic curve patterns were correlated with the increase of serum creatinine levels, and thus, OIH-NG has to be interpreted as a differentiated marker of renal function. Renal-transplant rejection does not produce a specific pattern of OIH curve, as seen from comparison of the curve-type distribution in rejection and non rejection periods (chi 2 = 0.0866). The diagnostic values of the OIH is limited to purely functional statements, allowing only an indirect diagnosis of renal-transplant rejections without permitting the differential diagnosis of other causes of renal disturbance. OIH-NG is useful for monitoring renal function because it resolves different function levels very sensitively even at identical creatinine values. Furthermore, it makes it possible to estimate the prognosis of renal functional improvement when creatinine levels are elevated.

Histologic correlation of transplant rejection diagnosed by computer-assisted sulfur colloid scan

Sulfur colloid scanning has been suggested as a means of early detection of renal transplant rejection. Visual interpretation of increased uptake by the allograft as opposed to surrounding pelvic structures was taken to signify rejection. In an attempt to increase the accuracy of these scans we programmed a computer to do differential counts between graft and surrounding pelvis and to then calculate a ratio. Hopefully this mathematical determination of increased uptake would be more accurate. These scans were compared with simultaneously obtained biopsy material. Unfortunately, the false negative and false positive rates were too high to make sulfur colloid useful in predicting graft rejection. Finally, our data showed that an early positive scan did not predict long-term outcome as had been suggested by others.

A co-operative study on the clinical value of dynamic renal scanning with deconvolution analysis

An international project was set up to study the clinical usefulness of intrarenal transit times derived from the renogram by deconvolution. A common data sheet, to collect clinical, biochemical, radiological and isotopic information, was completed by the centres. Five hundred and ninety-one patients were studied and the results analysed. The mean transit time (MTT) in normal kidneys was found to be 3.6 +/- 1.1 min. If the MTT is greater than 7.6 min, a kidney is likely to be obstructed. In vesico-ureteric reflux, the transit times are prolonged, but they are normal in infection, hypertension, parenchymal disease and minimally irradiated kidneys. In transplantation, when the kidney is normal, the transit times are shorter than in the natural kidney; in acute rejection, transit time are prolonged.

Diagnosis of impaired renal function after kidney transplantation using renal scintigraphy, renal plasma flow and urinary excretion of hippurate

The use of 131I-orthiodohippurate (OIH) scintigraphy combined with the estimated renal plasma flow (ERPF) and excretion index (EI) has been beneficial in separating impaired renal function due to graft rejection from acute tubular necrosis, ureteral obstruction, urinary extravasation and in some instances renal artery occlusion. The radionuclide data accurately identified acute and chronic rejection, confirmed by the clinical course, increase in BUN and serum creatinine and on occasion renal biopsy. Reversible and irreversible acute tubular necrosis (ATN) were clearly differentiated from acute rejection. When the ERPF and EI were plotted on a graph, multiple sequential radionuclide studies accurately predicted graft survival when chronic rejection existed. The limitation of this technique was the inability to discriminate between renal artery stenosis, ureteral obstruction and inflammatory disease. Scintigraphic studies did not distinguish between renal artery stenosis and chronic rejection. In these circumstances arteriography was the diagnostic procedure of choice. Although ureteral obstruction often can be correctly diagnosed by scintigrams, the ERPF, EI and intravenous pyelogram remained the most accurate diagnostic procedures. Recurrent glomerulonephritis, gram negative septicemia and generalized viral illness (herpes zoster or cytomegalovirus) simulated acute rejection and had to be separated by renal biopsy or the clinical course. The most valuable features of the radionuclide technique included: 1) the noninvasive method, 2) the simplicity, 3) the rapidity and 4) the reproducibility.

Urography and isotope renography following renal transplantation

The clinical yield from routine urography following renal transplantation was compared with that from isotope renography. In 50 recipients of renal transplants, 59 urograms and 55 renograms were studied. The most common pathologic finding at urography was renal papillary necrosis (in 6 patients). This condition had no obvious correlation with the further fate of the transplant. There were no other significant pathologic changes. It is concluded that isotope renography can be regarded as sufficient for routine follow-up. One baseline urogram is useful, but additional urographies should be carried out only when clinically indicated.