A 6 year-old girl presented with a recurrent urinary tract infection (UTI) had an abdominal ultrasonography (US) which revealed an enlarged left duplex kidney with a mildly prominent lower moiety collecting system. Voiding cystourethrography was normal without post voiding residual urine. She was referred for the radionuclide renography to see the drainage pattern of the left kidney.
Tc-99m mercaptoacetyltriglycine (MAG3) renal scintigraphy was performed according to F -15 protocol (5
). Oral hydration (10 ml/kg) started 30 minutes before the study and intravenous furosemide (2 mg) was given 15 minutes before the intravenous administration of 1 mCi (37 MBq) of MAG3. Imaging was performed from posterior projection using GE XRT gamma camera equipped with a low energy parallel-hole general purpose collimator at 140 keV energy peak with a 20% symmetrical energy window. Dynamic acquisition at 64x64 matrix was acquired 1 second per frame for 1 minute for the renal perfusion and 60 seconds per frame for 29 minutes for the renal function. An Entegra (GE medical systems) workstation was used for image processing. The dynamic planar images of MAG3 renal scintigraphy showed more prominent activity in lower moiety than upper (). The region of interests and the time activity curves are shown in and , respectively. The time to peak parenchymal uptake of upper and lower moieties of left renal duplex system was at 2.5 minutes for each and at about the third minute both curves showed a gradual decline indicating the beginning of excretion and patency of the collecting systems (). At the fifth minute, the slope of the activity curve of upper moiety increased, indicating a more rapid excretion followed by a focal rise of activity in lower moiety until the 10.5th
minute (). Diuretic was injected before the study, intravenous line was washed with saline just after the injection of radiopharmaceutical and there was not any patient motion, so the increase of the activity in the lower moiety was explained by “yo-yo” reflux. The drainage of both moieties was complete until the end of the study excluding the presence of an obstruction.
Figure 1 One minute dynamic planar images. The activity in lower moietystarts to increase by 8[ref:th]th[/ref] minute, becoming more prominent at 11[ref:th]th[/ref] minuteand than starts decreasing. Only a single left ureter is visible. Note the slightincrease (more ...)
The summed function images (2-3 min) from posterior projectiondemonstrating the regions of interest drawn to upper moiety (UM), lowermoiety (LM) and background regions (bcg 1 and bcg 2 respectively)
Figure 3 The time-activity curves of upper moiety (continuous trace) andlower moiety (dotted trace) of the left kidney. As the decline of activity inupper moiety was more prominent starting at fifth minute, a sharp inclineof activity on lower moiety was observed (more ...)
The patient is well after the last episode of UTI that was treated with antibiotics, on regular follow up. Also a long term suppression antibiotherapy was given. Proper wiping technique following the toilet use and frequent urination were advised for conservative management. Surgical treatment was not indicated.