MRI-based reference range for the renal pelvis anterior-posterior diameter in children ages 0-19 years.
OBJECTIVE
To determine the mean and normal range of anteroposterior diameter (APD) of the renal pelves in children.


METHODS
Patients aged 0-19 years with normal spinal MRIs were identified after institutional review board approval. Those with dilating uropathy or abdominal surgery/radiation were excluded. The maximum APD was measured. A mixed linear model was fit to determine the relationship between APD and age, adjusted for bladder distention. The left and right kidneys were treated independently.


RESULTS
283 left and 285 right renal units were included. For the left, a 3.5% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.5 mm (95th percentile: 7.2 mm) and 4.6 mm (13.4 mm), respectively. For the right, a 3.9% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.8 mm (8.4 mm) and 5.5 mm (16.6 mm), respectively. Compared with a non-distended bladder, a distended bladder increased the predicted APD between 23% (right) and 38% (left) (p = 0.01 and p < 0.0001, respectively).


CONCLUSIONS
The mean and normal ranges of APD measured by MRI in children are provided. APD increases with age and bladder distension and is greater on the left. Advances in knowledge: This article establishes normative ranges for APD, a critical component of genitourinary tract evaluation, and does so using the most precise imaging modality for this condition.
1 Department of Urology, Boston Children's Hospital, Boston, MA, USA.
Anthony J
AJ
Schaeffer
1 Department of Urology, Boston Children's Hospital, Boston, MA, USA.
Michael P
http://orcid.org/0000-0003-4246-8421
MP
Kurtz
2 Clinical Research Program, Boston Children's Hospital, Boston, MA, USA.
Tanya
T
Logvinenko
3 Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Michael T
MT
McCartin
3 Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Sanjay P
SP
Prabhu
1 Department of Urology, Boston Children's Hospital, Boston, MA, USA.
Caleb P
CP
Nelson
3 Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Jeanne S
JS
Chow
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007682:Kidney Pelvis / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D055815:Young Adult