(a, b) A 3-year-old child with a urinary tract infection episode. Having acquired the control of urination, a renal scintigraphy with IRC was performed. The scintigraphic study showed a left kidney slightly smaller than the contralateral one with a normal renal function and a low-grade reflux on the left side. As the child had a unilateral low-grade VUR without nephropathy, he was followed on surveillance by periodic urinalysis and ultrasonography scans, and he is currently asymptomatic. In general, in fact, low-grade refluxes (Grades I–II) have high rates of spontaneous resolution (usually more than 80 %) in young children. By the qualitative assessment of scintigraphic images, both kidneys are located in their own proper sides with regular perfusion. Left kidney is slightly smaller than the contralateral one, even if both kidneys show normal morphology, renal uptake, and urinary excretion. (a) Both renogram curves show normal slope of parenchymal phase and regular elimination of tracer from the kidneys (left curve is slightly less wide in relation to the size of the kidney). The split renal function is sufficiently symmetric (b). (c, d) During bladder voiding (regular and complete), a synchronous radiourine reflux limited to left ureter is observed (Grade I) (c). This scintigraphic finding is confirmed by time-activity curve of the left ureter without radioactivity increment corresponding to homolateral kidney (d)

By qualitative assessment of scintigraphic images, both kidneys are located in their own proper sides with synchronous but asymmetrical perfusion (reduced on the left side). Left kidney is small with a slightly irregular morphology; left renal uptake is preserved, and urinary excretion is normal. Right kidney shows an intense concentration of tracer in the renal parenchyma and a rapid washout (a). Left renogram curve (less wide than the contralateral one) shows preserved slope of parenchymal phase and regular elimination of tracer. The shape of the right renogram curve is normal in all phases. The split renal function is slightly asymmetric (relatively reduced on the left) (b). (c, d) IRC images show a complete and regular bladder voiding. During bladder voiding, a synchronous radiourine reflux is present on the left side that reaches the renal pelvis without dilatation (Grade II) (c). Time-activity curves of bladder and kidneys reveal a regular and complete bladder voiding, with a radioactivity increment corresponding to left ureter and kidney (d)

(a) At 8 months of life, a DMSA scan shows a double bilateral system with good uptake of the radiopharmaceutical in both kidneys; tracer concentration is regular in the upper systems, while a nonhomogeneous distribution is detected in the lower systems due to focal cortical defects (more marked scars on the left). No evidence of parenchymal defects is observed in the upper systems.(b, c) At 26 months of life, a MAG3 renal scan is performed showing a good function of the right kidney (both systems) and a double left kidney district with hypofunction and scars of the lower system. Bilaterally, urinary excretion is slow with evidence of moderate stasis of radiourine (in the lower systems and in the left upper one) which tended to resolve itself and to further improve after orthostatism, excluding the presence of lower or upper pole pelviureteric junction obstruction in duplicated collecting systems (b). Both renogram curves show normal slope of parenchymal phase and mildly slow elimination of tracer from the kidneys. Overall, the split renal function is sufficiently symmetric. (d, e) IRC study (qualitative images and time-activity curves) shows irregular but complete bladder emptying: for three times, a sudden interruption of urination is observed with bilateral VUR and subsequent refilling of the bladder. Time-activity curves of ureters and kidneys reveal a bilateral radioactivity increment corresponding to the bilateral ureter and kidney (reaching up the renal pelvis with a mild dilatation, these kinds of VUR are classified as II–III scintigraphic grade)

(a) At 2 months of life, a DMSA scan is performed after recurrent pyelonephritis. Scintigraphic imaging shows radiopharmaceutical uptake preserved in the left kidney and markedly reduced in the right one. Bilaterally, tracer distribution is not homogeneous due to multiple focal cortical defects with greater impairment of the right kidney (split renal function of right kidney was 29 %). Background signal is increased as for global insufficient renal function. At 18 months of life, a MAG3 renal scan confirms bilateral renal scars with preserved parenchymal function in the left kidney and severe hypofunction in the right one. Urinary excretion is mildly delayed in the left kidney, delayed and slow on the right, with evidence of radiotracer stasis which tended to resolve itself (b) and to further improve after orthostatism (gravity-assisted drainage test-1, d). Bilateral tracer accumulation is observed in the ureters, but both ureterograms show nonobstructive pattern. (e). Left renogram curve shows preserved slope of parenchymal phase and mildly slow elimination of tracer. Right renogram curve has a low width, showing reduced slope of parenchymal phase, delayed transit, and slow urinary excretion (c). The basic renogram shows a poor right split renal function, steady if compared to the previous DMSA scan. (f–g) IRC study is obtained only after several attempts, with a high filling bladder: performing an IRC study can sometimes be difficult due to poor child cooperation, but it is of crucial importance. In the IRC images, in fact, we can observe a regular and complete bladder emptying with bilateral VUR, more severe on the right side (f). Time-activity curves of kidneys reveal a bilateral radioactivity increment, synchronous with the bladder emptying, especially on the right (II–III scintigraphic grades on the left and III scintigraphic grade on the right) (g)

(a, b) By qualitative assessment of scintigraphic images, left kidney is smaller than normal with a slightly reduced renal uptake. Transit and urinary excretion of radiotracer from the kidney are slightly delayed and slow with evidence of mild pelvic stasis which tends to resolve itself during basal study. Right kidney shows an intense concentration of tracer in the renal parenchyma and a rapid washout (a). Left renogram curve (less wide than the contralateral one) shows preserved slope of parenchymal phase, transit slightly prolonged, and elimination of tracer from the kidney mildly slow. The shape of the right renogram curve is normal in all phases. The split renal function is slightly asymmetric (mildly reduced on the left) (b). (c, d) In order to obtain a diagnostic examination with improving sensitivity, IRC study was performed after oral hydration awaiting a better filling bladder and a further left pelvic stasis resolution. In the IRC images, we can observe persistence of left pelvic stasis, which slightly decreases and increases before bladder emptying. After a regular but incomplete bladder emptying (about 15 % of residual postvoiding activity), a high-grade VUR was detected on the left side (c). Time-activity curves of kidneys confirm a left radioactivity increment previously and synchronous with bladder emptying (passive and active VUR, II and III scintigraphic grades, respectively) (d). A good technical IRC performing is crucial to avoid false-negative findings or movement artifacts (especially when residual urine stasis is present)