Deconvolution Analysis of Renograms Obtained with Simultaneously Administered 99mTc-DTPAand 131l-Hippuran

Abstract

Seventy patients were studied with a dual radionuclide technique. The conventional renograms and the blood curve were subjected to deconvolution analysis using the matrix algorithm method, and the following curve data calculated from the retention functions: absolute and relative amplitudes, minimum time of the retention function, maximum time of the retention function and mean transit time. The findings with the two radiopharmaceuticals 99mTc-DTPA and 131l-Hippuran were compared under normal and pathological conditions. The correlations between the data with 99mTc-DTPA and those with 131l-Hippuran were highly significant (p <0.01). So was the correlation between the absolute amplitude of the retention curve and the rate of uptake based on the corresponding renogram (p <0.01). Due to the difference in the renal handling of the two tracers, longer maximum times were obtained with 99mTc-DTPA. The mean transit times were also longer with 99mTc-DTPA, except in kidneys with parenchymal insufficiency. The highest amplitudes were found in normal kidneys, while the lowest values were observed in parenchymal insufficiency. In the group with acute ureteral obstruction, the mean transit times tended to be increased. The maximum times were even more increased. With both tracers it is possible to distinguish between the three groups of renal conditions studied here: Normal, parenchymal insufficiency, and acute ureteral obstruction.

Logistic Regression Analysis

“…Only in the case of CLSRP was the MTT parameter of primary importance (see Table 3). This emphasises the usefulness of amplitude and MaxTT as deconvolution parameters in a clinical environment (8). It is evident that the five viable deconvolution methods pro duce results which have meaning in a clinical environment.…”

“…All patients had established renal conditions (8,9). The final diagnoses were based on radiological investigation (IVU and/or Estimating Diagnostic Yields • Kempi and Sutton KUB), biochemical tests (serum creatinine, serum urea and test tapes sensitive to albumin, haemoglobin and glucose), urinary microscopy and clinical follow up.…”

“…Since it can easily be shown that a subject's two kidneys demonstrate some degree of correlation (8), calculations were based on one kidney per patient. The kidney to be analyzed was randomly chosen, except in the seven patients with one function ing kidney, with the result that 43 normal kidneys, 18 kidneys with parenchyma!…”

Renogram and deconvolution parameters in diagnosis of renal artery stenosis

“…Threep atients hads ignificantb ilateral RAS. Sinceas ubject's twok idneysd emonstrate some degree of correlation (12),calculationswerebased on one kidneyper patient. The kidneyt ob ea nalysed wasr andomlychosen,exceptinthe 12 patients with unilateralR AS.…”

“…Avascularspike(5,28) on the TAC, frequentlyobservedatabout 30 sec after injec-tion,i .e., the secondc urve point,w as removedbybounding (11). TheTAC wasthen subjected to three smooths using the smoothing operator (12,17,12) (23). It can easily be shownthatthe activity in pelves is negligible up to 140seconds afterinjection.…”