Differential Renal Function (DRF) Measured by Scintigraphy in Hydronephrotic Kidneys: Importance of Conjugate Views for Accurate Evaluation
CUA Online Library. WEHBI E. 06/25/13; 31370; MP-09.13
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Abstract
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INTRODUCTION AND OBJECTIVES:
Traditionally, a single posterior view is employed to measure DRF during nuclear renal scintigraphy.
Nevertheless, experimental data shows important variations in this measurement in the setting of significant hydronephrosis.1,2,3 To date, the impact of hydronephrosis on the accuracy of DRF determination based on varying degrees of hydronephrosis has not been specifically addressed. In this study we evaluate the hypothesis that significant hydronephrosis amplifies the discrepancy between anterior and posterior views (APV) when calculating DRF and that either single view may be a highly inaccurate estimation of the true DRF.
METHODS:
We retrospectively reviewed consecutive MAG3 renal scans performed from 2009-2011. Ultrasound examinations immediately before or after renal scans were reviewed and the degree of hydronephrosis was recorded using the antero-posterior pelvic diameter (APPD). The absolute percent difference in DRF between each view (anterior minus posterior) was calculated and correlated to the APPD. Patients were stratified into 4 groups according to APPD (<5mm, >10mm, >15mm and >25mm). Only patients having both kidneys with APPD <5mm were labelled as normal.
RESULTS:
519 scans with corresponding ultrasounds were analyzed. Median age at time of the studies was 2.26 years. Kidneys with larger APPD had a greater discrepancy in function on APV, difference that was statistically significant. Mean differences in DRF for APV in each group were 4%, 6%, 6.7% and 7%, for APPD <5mm, >10mm, >15mm and >25mm respectively. When compared to normal kidneys, there was a statistically significant difference in DRF for APPD >15mm and >25mm (p=0.03 and p=0.01 respectively), which did not reach significance for APPD >10mm (p=0.07).
CONCLUSIONS:
The discrepancy in DRF measured by subtracting the function obtained on the anterior and posterior views is increasingly impacted by APPD, becoming significant when APPD is between 10-15mm. These findings suggest that the use of single views during nuclear renography for grossly hydronephrotic kidneys is inaccurate, and conjugate views may better represent DRF.
Traditionally, a single posterior view is employed to measure DRF during nuclear renal scintigraphy.
Nevertheless, experimental data shows important variations in this measurement in the setting of significant hydronephrosis.1,2,3 To date, the impact of hydronephrosis on the accuracy of DRF determination based on varying degrees of hydronephrosis has not been specifically addressed. In this study we evaluate the hypothesis that significant hydronephrosis amplifies the discrepancy between anterior and posterior views (APV) when calculating DRF and that either single view may be a highly inaccurate estimation of the true DRF.
METHODS:
We retrospectively reviewed consecutive MAG3 renal scans performed from 2009-2011. Ultrasound examinations immediately before or after renal scans were reviewed and the degree of hydronephrosis was recorded using the antero-posterior pelvic diameter (APPD). The absolute percent difference in DRF between each view (anterior minus posterior) was calculated and correlated to the APPD. Patients were stratified into 4 groups according to APPD (<5mm, >10mm, >15mm and >25mm). Only patients having both kidneys with APPD <5mm were labelled as normal.
RESULTS:
519 scans with corresponding ultrasounds were analyzed. Median age at time of the studies was 2.26 years. Kidneys with larger APPD had a greater discrepancy in function on APV, difference that was statistically significant. Mean differences in DRF for APV in each group were 4%, 6%, 6.7% and 7%, for APPD <5mm, >10mm, >15mm and >25mm respectively. When compared to normal kidneys, there was a statistically significant difference in DRF for APPD >15mm and >25mm (p=0.03 and p=0.01 respectively), which did not reach significance for APPD >10mm (p=0.07).
CONCLUSIONS:
The discrepancy in DRF measured by subtracting the function obtained on the anterior and posterior views is increasingly impacted by APPD, becoming significant when APPD is between 10-15mm. These findings suggest that the use of single views during nuclear renography for grossly hydronephrotic kidneys is inaccurate, and conjugate views may better represent DRF.
INTRODUCTION AND OBJECTIVES:
Traditionally, a single posterior view is employed to measure DRF during nuclear renal scintigraphy.
Nevertheless, experimental data shows important variations in this measurement in the setting of significant hydronephrosis.1,2,3 To date, the impact of hydronephrosis on the accuracy of DRF determination based on varying degrees of hydronephrosis has not been specifically addressed. In this study we evaluate the hypothesis that significant hydronephrosis amplifies the discrepancy between anterior and posterior views (APV) when calculating DRF and that either single view may be a highly inaccurate estimation of the true DRF.
METHODS:
We retrospectively reviewed consecutive MAG3 renal scans performed from 2009-2011. Ultrasound examinations immediately before or after renal scans were reviewed and the degree of hydronephrosis was recorded using the antero-posterior pelvic diameter (APPD). The absolute percent difference in DRF between each view (anterior minus posterior) was calculated and correlated to the APPD. Patients were stratified into 4 groups according to APPD (<5mm, >10mm, >15mm and >25mm). Only patients having both kidneys with APPD <5mm were labelled as normal.
RESULTS:
519 scans with corresponding ultrasounds were analyzed. Median age at time of the studies was 2.26 years. Kidneys with larger APPD had a greater discrepancy in function on APV, difference that was statistically significant. Mean differences in DRF for APV in each group were 4%, 6%, 6.7% and 7%, for APPD <5mm, >10mm, >15mm and >25mm respectively. When compared to normal kidneys, there was a statistically significant difference in DRF for APPD >15mm and >25mm (p=0.03 and p=0.01 respectively), which did not reach significance for APPD >10mm (p=0.07).
CONCLUSIONS:
The discrepancy in DRF measured by subtracting the function obtained on the anterior and posterior views is increasingly impacted by APPD, becoming significant when APPD is between 10-15mm. These findings suggest that the use of single views during nuclear renography for grossly hydronephrotic kidneys is inaccurate, and conjugate views may better represent DRF.
Traditionally, a single posterior view is employed to measure DRF during nuclear renal scintigraphy.
Nevertheless, experimental data shows important variations in this measurement in the setting of significant hydronephrosis.1,2,3 To date, the impact of hydronephrosis on the accuracy of DRF determination based on varying degrees of hydronephrosis has not been specifically addressed. In this study we evaluate the hypothesis that significant hydronephrosis amplifies the discrepancy between anterior and posterior views (APV) when calculating DRF and that either single view may be a highly inaccurate estimation of the true DRF.
METHODS:
We retrospectively reviewed consecutive MAG3 renal scans performed from 2009-2011. Ultrasound examinations immediately before or after renal scans were reviewed and the degree of hydronephrosis was recorded using the antero-posterior pelvic diameter (APPD). The absolute percent difference in DRF between each view (anterior minus posterior) was calculated and correlated to the APPD. Patients were stratified into 4 groups according to APPD (<5mm, >10mm, >15mm and >25mm). Only patients having both kidneys with APPD <5mm were labelled as normal.
RESULTS:
519 scans with corresponding ultrasounds were analyzed. Median age at time of the studies was 2.26 years. Kidneys with larger APPD had a greater discrepancy in function on APV, difference that was statistically significant. Mean differences in DRF for APV in each group were 4%, 6%, 6.7% and 7%, for APPD <5mm, >10mm, >15mm and >25mm respectively. When compared to normal kidneys, there was a statistically significant difference in DRF for APPD >15mm and >25mm (p=0.03 and p=0.01 respectively), which did not reach significance for APPD >10mm (p=0.07).
CONCLUSIONS:
The discrepancy in DRF measured by subtracting the function obtained on the anterior and posterior views is increasingly impacted by APPD, becoming significant when APPD is between 10-15mm. These findings suggest that the use of single views during nuclear renography for grossly hydronephrotic kidneys is inaccurate, and conjugate views may better represent DRF.
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