Usefulness of clearance parametric images in detection of regional renal parenchyma dysfunction.

BACKGROUND: The aim of the study was to examine whether parametric clearance images (PAR) enhance diagnostic potential of a dynamic renal scintigraphy with detection of local dysfunction of kidneys, on a model of kidneys after treatment with extracorporeal shock wave lithotripsy (ESWL), MATERIAL AND METHODS: Kidneys after ESWL were accepted as a proper model for the implementation of this objective because of the previously proven damaging effect of a shock wave on renal parenchyma and known region of ESWL application. Forty patients (23 males and 17 females) at the age of 37 to 70 years (mean value 54) with untreated earlier single, one-sided nephrolithiasis, currently treated with ESWL, underwent a study. A dynamic renal 99mTc-EC scintigraphy was performed three times: before ESWL, a week and a month after this therapeutic intervention. PAR images generated with use of an in-house developed software were compared with summation (SUM) of images obtained from radiopharmaceutical uptake phase and quantitative global function parameters (GFP) of each kidney, like split function, MTT - mean transit time and PTT - parenchymal transit time.

RESULTS: PAR and SUM images of all 40 kidneys before ESWL were normal. PAR images revealed local or diffused defects a week and a month after therapeutic intervention in statistically significantly larger numbers of kidneys than SUM images (19 vs. 6, p = 0.002 and 16 vs. 5, p = 0.003, respectively). A week after ESWL, when defects in PAR images were observed in about a half of all renal segments (29/57 - 51%) all GFP values were significantly worse than in kidneys without defects. A month after ESWL defects in PAR images could be observed in ab. 1/3 (17/48 - 35%) of segments and were less extensive, whereas GFP values did not differ significantly from values in kidneys without clearance function impairment in the PAR images.

CONCLUSIONS: PAR images enhance diagnostic potential of a dynamic renal scintigraphy with detection of local function defects. These images allow to detect more local renal function defects than SUM images.