الفهرس 
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Abstract
Geometric mean method in defferential renal estimation is considered as effective as of posterior view method; further more it is more effective than the later in measureing DRF in abnormally located and pathologic kidneys. However, the posterior technique is still routinely used to assess DRF. Geometric mean images from anterior and posterior views are much less affected by renal depth and may offer a more accurate estimate of DRF. There is no difference in the duration of the examination, cost or radiation exposure using the geometric mean calculation.
Even in the adult population the depth correction that the geometricmean provides may be necessary in only a small number of patients, especially those being evaluated for donor nephrectomy and those with renal anomalies.
Most validity of geometric mean in our study regarding pathology is found mainly to be attributed to ectopic, horse-shoe, renal cyst mass and hydronephrosis, thus detailed studies of different renal presenations would be an index of geometric mean specificity.
Recommendation
Recommendations:
Further studies on a larger study are needed to show if results would be improved by increasing the number of cases and from different centers to include variability in study results regarding pathology and demographic destribution.
Body mass index and using a standard group of normal cases is also recommended to be used in further studies to validate results acurrately.
Further stduies is recommended to discuss more specified renal pathologies to strengthen specific benefits from geometric mean, like the forementioned studies of Wehbi et al as well as Aktasand Sarıkaya et al which discussed geometric mean in hydronephrosis.
Summary
Summary
Evaluation of the urinary tract was one of the first experimental applications of radiology and contrast administration. More than 100 years later, imaging has developed into a fundamental part of the evaluation of nephrology and urology patients using advanced ultrasonography, MRI, modern computed tomogaphy and renal scitigraphy.
However, this medical imaging technique could be performed with several radiopharmaceuticals such as technetium-99m dimercaptosuccinic acid (99mTc-DMSA), technetium-99m diethylenetriaminepentaacetic acid (99mTc-DTPA), technetium-99m mercaptoacetyltriglycine (99mTc MAG3), iodine 131 orthoiodohippurate (OIH ), and more recently technetium-99m ethylenedicysteine (99mTc-EC) [2]. In fact, the use of the DMSA as a static renal agent could be considered as the highest predictable method in order to evaluate the relative renal function.
The tracer is preferentially taken up by the proximal renal tubule and the first part of Henle’s loop and accumulates in the renal cortex.
The relative 99mTc-DMSA renal uptake may be used as an index of the renal function and to evaluate the change in renal function at follow up. Quantification can be performed using a couple of methods: 1) evaluation based on the posterior view only, with or without compensation for kidney depth; 2) evaluation based on both anterior and posterior views using their geometric mean to compensate for kidney depth. The latter method is used more often and it is also usually considered as more valid.
The aim of this study was to evaluate the occurrence of remarkable differences in the results from quantification of the relative renal function obtained using the geometric mean and those obtained using the posterior counts only. Moreover, we evaluated multiple factors, like gender, pathology and to what extent the patient age influenced these differences.
Geometric mean method in defferential renal estimation is considered as effective as of posterior view method; further more it is more effective than the later in measureing DRF in abnormally located and pathologic kidneys. However, the posterior technique is still routinely used to assess DRF.
Geometric mean images from anterior and posterior views are much less affected by renal depth and may offer a more accurate estimate of DRF. There is no difference in the duration of the examination, cost or radiation exposure using the geometric mean calculation. Even in the adult population the depth correction that the geometricmean provides may be necessary in only a small number of patients, especially those being evaluated for donor nephrectomy and those with renal anomalies.
Most validity of geometric mean in our study regarding pathology is found mainly to be attributed to ectopic, horse-shoe, renal cyst mass and hydronephrosis, thus detailed studies of different renal presenations would be an index of geometric mean specificity.
In our study, about 2/3 (70%) of cases were adults; 18years or more, while 67% were males and 33% were females.
Collectively, the mean andstandard deviation of posterior view and geometric mean method was measured for all patients as followed:
-Mean and standard deviation of posterior to geometric mean methods in the left side 0.134±5.045, with insignificant P. value: 0.755.
-Mean and standard deviation of posterior to geometric mean methods in the right side 0.134±5.045, with insignificant P. value: 0.755.
-Mean and standard deviation of difference between posterior to geometric mean methods 1.01±8.99, with insignificant P. value: 0.189.
Many other previous studies supported these findings, in view of normally located kidneys and pediatric population in consern.
The DMSA scans with a difference between both methods more than 5% were reviewed by different studies to see whether there was any obvious anatomical cause to account for any large differences found.
Our results showed a significant difference between the two methods regarding the criteria of >5% variance rate with different renal pathologies (P.value 0.004).
And finally we conducted a study to find a relationship between the patient’s age and the difference between the two previous methods for calculating the relative renal function, whether with or without the rate of differential difference (5%) between both sides in the two methods; we found an association between differences in relative function value (DRF) of both kidneys with increasing age, with P.value: 0.005.