ABSTRACT
The aim of this study was to assess the usefulness of clinical features in risk assessment of renal cortical scarring and to determine the sensitivity of renal ultrasound in defection of renal scars in relation to DMSA scan. Ninety-six children [192 kidneys] with bacteriologically proven UTI were included in the study. All patients underwent ultrasonography using Siemens Negra multiprobe machine and DMSA scan. The latter imaging was performed 3 hours after IV injection of Tc99m-DMSA, using a dual head ADAC vertex plus Gamma camera with high-resolution collimator. The dose was calculated according to the child's weight using the equation: child dose = child weight x 5 / 70. Planar images were acquired in anterior, posterior, right posterior and left posterior oblique projections for 500 K counts each. If ectopic or ptosed kidney was detected, anterior oblique projections were added. Studies were reported by a nuclear medicine consultant and a scan was reported as positive for the presence of cortical scar[s] if there was distortion [depression] in the normal kidney contour or focal or diffuse reduction in cortical tracer uptake. Split renal function was calculated and normal differential function was regarded in the range of 45-55%. The results showed that, out of our patient population, 84 were girls [87.5%] and 12 were boys [12.5%]. They were divided according to their age into two groups: preschool age group [1-4 years old] [24 children; 25%] and school age group [72 children, 75%]. Sixteen children were found to have focal or diffuse renal scarring by DMSA study [16.6%], however Ultrasonography detected 8 cases [8.3%] with renal scars out of these 16 cases i,e. the ultrasound sensitivity was 50% of that of DMSA. Eight of these 16 cases had bilateral abnormalities and 8 with unilateral abnormality [24 kidneys; 12.5%]. Twelve were in the school age group and 4 were of the preschool age group. All 16 children with scars had symptoms of upper VTI. Loin pain was more consistent with renal scarring than fever. Nevertheless, many children [44] with upper UTI symptoms did not develop renal scarring. None of the 36 children with no symptoms suggesting the presence of upper UTI [i.e. only lower UTI] had renal scarring on DMSA study
Conclusion: we concluded that patients with only lower UTI are much less prone to development of renal scarring, and that ultrasonography sensitivity is not good enough in detecting renal scars and at the present time should not replace DMSA in evaluation of renal scarring