MR imaging of kidneys: functional evaluation using F-15 perfusion imaging.
BACKGROUND
Children with hydronephrosis are typically investigated by a combination of diuretic renal scintigraphy, ultrasound, and voiding cystourethrography. Unfortunately, there is no gold standard to assess obstruction.


OBJECTIVE
The purpose of our study was to evaluate the utility of dynamic contrast enhanced MR urography in the investigation of children with hydronephrosis to define urinary tract anatomy, to calculate differential renal function and to assess urinary tract obstruction.


METHODS
Dynamic contrast-enhanced MR imaging was performed in 40 children with unilateral hydronephrosis. There were 14 girls and 26 boys with an age range of 1 month to 14 years (mean 1.4 years). The information from traditional imaging modalities was compared to the information obtained from the single MR study.


RESULTS
The anatomic imaging with MR urography was superior to other modalities. The split renal function was estimated with MR urography by calculating the volume of enhancing renal parenchyma and was comparable to renal scintigraphy ( r=0.98). By using surgery versus non-surgery as the decision point, with MR urography the sensitivity was 100%, specificity 71%, positive predictive value 86%, negative predictive value 100%, and diagnostic efficiency 90%. For renal scintigraphy the sensitivity was 96%, the specificity 56%, positive predictive value 76%, negative predictive value 90%, and diagnostic efficiency 79%.


CONCLUSIONS
Dynamic contrast-enhanced MR urography provides superior anatomic and functional information when compared with ultrasound and diuretic renal scintigraphy. The information is gathered in a single study that does not use ionizing radiation. It is likely that MR urography will replace renal scintigraphy in the evaluation of hydronephrosis in children.
Grattan-Smith
J Damien
JD
Department of Pediatric Radiology, Children's Healthcare of Atlanta, Emory University School of Medicine, 1001 Johnson Ferry Road, GA 30342, Atlanta, USA. damien.grattan-smith@choa.org
Perez-Bayfield
Marcos R
MR
Jones
Richard A
RA
Little
Stephen
S
Broecker
Bruce
B
Smith
Edwin A
EA
Scherz
Hal C
HC
Kirsch
Andrew J
AJ
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D004232:Diuretics / Q000008:administration & dosage; D005260:Female; D005665:Furosemide / Q000008:administration & dosage; D019786:Gadolinium DTPA; D006801:Humans; D006869:Hydronephrosis / Q000175:diagnosis* / Q000503:physiopathology; D007223:Infant; D007668:Kidney / Q000473:pathology* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010477:Perfusion
D003287:Contrast Media; D004232:Diuretics; D005665:Furosemide; D019786:Gadolinium DTPA