The Spectrum of Parenchymal Changes in Kidneys Affected by Intrarenal Reflux, Diagnosed by Contrast-Enhanced Voiding Urosonography and DMSA Scan

Abstract

PurposeTo describe the parenchymal defects in kidneys with intrarenal reflux (IRR) diagnosed using contrast-enhanced voiding urosonography (ceVUS) and 99mTc-DMSA scintigraphy (DMSA scan).Materials and MethodsA group of 186 uretero-renal units (URUs) was analyzed using ceVUS and DMSA scans: 47 without vesicoureteral reflux (VUR) (group A) and 139 with VURs, comprising 73 VURs without (group B), and 66 with IRR (group C). VURs included non-dilating (grades I–II), mildly non-dilating (grade III), and non-dilating (grades IV–V) grades. The parenchymal changes were analyzed using a DMSA scan.ResultsThe median age for VUR diagnosis was 16.5 months in girls, and 8.5 months in boys (Z = 3.9; p = 0.001). IRR occurred in 51.4% of boys and in 25.9% of girls (χ2 = 12.4; p < 0.001). The non-dilating VUR occurred in 44% of boys and 24.1% of girls (χ2 = 7.7; p = 0.005). IRRs characterized upper and lower renal segments (81.8 and 63.6%) and middle segments (33.3%). Both incidence and increase in IRR correlated with the grade of VUR (p < 0.001). The incidence of reduced DMSA signal was statistically different among groups A + B and C, but not between groups A and B (χ2 = 32.2; p < 0.001). No statistically significant relationship existed between the reduced DMSA signal and the grade of VUR in group C. The reduced DMSA signal appeared in 9.9% positions in kidneys from group A, 14% from group B, and 32% from group C. Out of all 118 IRRs, 38.1% had reduced and 61.9% had normal DMSA signal. Among 11 parenchymal scars found in all three groups, 2 belonged to group B, 9 to group C, while group A had no scars.ConclusionThe parenchymal changes are the most prominent in the group with IRR, but they do not significantly differ among kidneys with different grades of VUR. VURs of higher grades are associated with a higher incidence of IRR and early clinical presentation. Scars can also appear in lower-grade VURs accompanied by IRR. Boys with VUR have earlier clinical presentation than girls, as they have significantly higher grades of VUR with a higher proportion of IRRs. Therefore, we suggest a subdivision of VURs into those with IRR and abundant parenchymal damage, and those without IRR and less parenchymal damage.

The Intrarenal Reflux Diagnosed by Contrast-Enhanced Voiding Urosonography (ceVUS): A Reason for the Reclassification of Vesicoureteral Reflux and New Therapeutic Approach?

“…Since the VURs of grade II were highly represented in that study, they accounted for 21% of all diagnosed IRRs [10]. The existence of IRRs in the group of non-dilated VURs was also noticed in some other similar studies [9,10,55,64], while another group of studies reported the opposite results [62,63,65,66]. We believe that such differences regarding the percentage of IRRs in the group of non-dilating VURs might be explained by a small number of cases in some studies, deficiencies in diagnostic procedures, or differences in the used equipment.…”

“…The procedures are followed by observing doctors and technicians during the filling and voiding phases, and all phases are documented and recorded. The main difference between those two methods is that VCUG bears radiation for the patient, while ce-VUS is radiation-free [6][7][8][9][10][11][12][13][14]. The VUR can be classified into five grades by both MCUG and ceVUS techniques.…”

“…Nowadays, the diagnosis of VUR, as well as the diagnosis of IRR, is possible without radiation burden by using the ceVUS method, especially with the second generation of contrast media [9,10,55,[62][63][64][65][66]. The use of ceVUS opened new possibilities for the diagnosis of IRR, showing that the incidence of IRR appeared in a range between 11.9 and 61.5% out of all diagnosed VURs [9,10,55,[64][65][66]. The study by Simičić A. et al showed that 100% of VURs grade IV and V and 83.8% of VURs grade III had IRR.…”

“…VUR may be the cause of reflux nephropathy in approximately 12.5% of all patients and 25% of children with end-stage renal disease (ESRD). The presence of VUR can be accompanied by renal parenchymal defects, diagnosed by intravenous urography (IVU) in the past or present by 99mTc dimercaptosuccinic acid scan (DMSA scan) according to the protocols [7,9,[27][28][29][30][31][32][33][34][35][36][37].…”

“…The DMSA findings sometimes are not easy to interpret due to the possible interobserver variabilities in interpretation. Therefore, before the establishment of firm diagnostic standards for the interpretation of DMSA scans, it would be good if the findings were interpreted by at least two independent nuclear medicine specialists [7,9,37,43].…”