The Impact Of Renal Depth、ROIs And Depth & ROIs Corrected By CT On GFR In Patients With Hydronephrosis

Objective:Using two sample of ^99mTc-DTPA plasma clearance as the reference standard, evaluate the accuracy of GFR valued by Renal dynamic imaging with four methods（Gates、CT depth correction、area correction、depth&area correction）.Methods:47 patients with hydronephrosis were studied（20M, 27 F, age range21-59）. All the patients were diagnosed hydronephrosis according to the ultrasound. 35 of them with unilateral hydronephrosis and 12 of them with Bilateral hydronephrosis. All the subjects were accepted the conventional diuretic renal dynamic imaging, injected ^99mTc-DTPA（185MBq）, collected renal scintigraphic images immediately, and injected furosemide（40mg） after 15 min. After renal dynamic imaging, acceped CT acanning immediately.The images were processed according to standard procedure（Gates method） to abtain GFR（g GFR）; Measured renal depth in CT images and abtained GFR（d GFR）; Draw the outline of renal in every CT pictures and superposited to get the maxmim ROI area as the corrected ROI area, applied this corrected ROI to the Gates procedure, and abtained GFR（a GFR）; applied both the corrected renal depth and corrected ROI to the Gates procedure to abtain GFR（ad GFR）. Collected blood sample（5ml） at 120 min and 240 min after post injection respectively and centrifuged 10 min to obtain serum（1ml） and measured their radioactive counts and calculated by two plasma method formula to abtain GFR（t GFR）. According to t GFR, all the subjects were divided into 3 groups by the chronic renal disease definition of the American CKD.（1）patients with normal renal function: GFR≥90 ml/min×1.73m²;（2）patients with mild renal function damage: 60≤GFR<90 ml/min×1.73m²;（3）patients with moderately and severe renal function damage: GFR<60 ml/min×1.73m². All the data were demonstrated in x±s. Using the paired-samples t-test、 Bland-Altman、 ICC and the ROC curve to analysis the statistics. The conclution was P<0.05 which means that the result has statistical significance.Results:1. GFR≥90 ml/min×1.73m²:There was no significant difference when g GFR、a GFR compared with t GFR respectively（t g GFR =-0.611, P g GFR =0.56, t a GFR =0.376, P a GFR =0.716）,whereas d GFR、ad GFR is significantly greater than t GFR（t d GFR =-5.292, P d GFR =0.001, t ad GFR =-4.979, P ad GFR =0.002）; g GFR、d GFR、a GFR、ad GFR both have good consistency with t GFR（ICC respectively are 0.79、0.67、0.91、0.7）. 2. 60≤GFR<90 ml/min×1.73m²:There was no significant difference when g GFR、a GFR compared with t GFR respectively（tg GFR=-0.635,Pg GFR =0.531, t= a GFR =0.993,P a GFR =0.33）, whereas d GFR、ad GFR is significantly greater than t GFR（t d GFR =-6.184,P d GFR <0.001, t ad GFR =-6.787,P ad GFR <0.001）;g GFR、d GFR、a GFR、ad GFR both have consistency with t GFR（ICC respectively are 0.58、0.54、0.78、068）.3. GFR<60 ml/min×1.73m²:Only a GFR has no significant difference with t GFR（ta GFR=-2.091,Pa GFR =0.061）. Both g GFR、d GFR、ad GFR are significantly greater than t GFR（t g GFR =-3.081,P g GFR =0.01, t d GFR =-6.029,P d GFR <0.001, t ad GFR =-5.721,P ad GFR <0.001）. All of them have have good c o n s i s t en c y w i t h t GF R（ IC C r e s p e c t i v el y a r e 0. 9 4 、 0.8 9 、 0. 9 6 、 0. 91）.Conclusion:1.For patients with normal renal function, the Gates and CT area ROI correction methods both have a good correlation with two plasma sample methods,moreover, the area correction method has a better correlation with plasma sample methods. 2.For patients with poor renal function,the CT area ROI correction method is more accurate than other three methods when evaluate GFR..