ORIGINAL ARTICLE Are renal volumes measured by magnetic resonance imaging and three-dimensional ultrasound in the term neonate comparable? Alison L. Kent & Rajeev Jyoti & Cameron Robertson & Lisa Gonsalves & Sandra Meskell & Bruce Shadbolt & Michael C. Falk Received: 25 August 2009 / Revised: 23 October 2009 / Accepted: 25 November 2009 / Published online: 19 January 2010 # IPNA 2010 Abstract Renal volume, but not renal length, has been shown to be positively correlated with renal function. Three-dimensional (3D) ultrasound and magnetic resonance imaging (MRI) are two modalities used to assess renal volume. The aim of our study was to determine whether 3D ultrasound measurements of renal volume in the neonate are comparable to those of MRI measurements. Preterm and term neonates had an MRI and 3D ultrasound to determine renal volume at the same time as they had an MRI brain scan for other clinical conditions. The preterm neonates were all term corrected age, and the term neonates were 1–4 weeks of age. None of the kidneys examined were abnormal. There were no significant differences in the weight or length of the preterm and term infants at the time of their MRI scan. The left renal length was significantly longer according to MRI measurements than according to 3D ultrasound measurements (p =0.02). Renal volumes of both the left and right kidney were greater when measured by MRI than by 3D ultrasound (p <0.0001, respectively). Total volumes of the kidneys were greater when measured by MRI than by 3D ultrasound (p =0.008). Renal volume in neonates was significantly less when evaluated by 3D ultrasound than by MRI. These results demonstrate that MRI and 3D ultrasound renal volumes are not comparable in the neonatal population and, therefore, the same radiological modality should be used if repeat volume measurements are to be performed. Keywords Magnetic resonance imaging . Neonate . Renal . Three-dimensional ultrasound . Volume Introduction Renal length is usually measured using ultrasound, with normal values available for neonates and children [1–5]. However, renal length is not an accurate predictor of renal function, whereas renal volume has been shown to correlate with function [6, 7]. Three-dimensional (3D) ultrasound is a standard radiological modality used to evaluate a variety of renal conditions in children, including renal cysts, hydro- nephrosis, tumours and vascular anomalies [8]. An assess- ment of renal volume by 2D and 3D ultrasound using a number of different methods has provided some informa- tion on renal volumes in neonates and children [9–11]. In one study, the accuracy of 2D and 3D ultrasound renal volume measurements was assessed by comparing the 2D and 3D ultrasound results with measurements of water displacement in adult cadaver specimens [12]. The results A. L. Kent (*) Department of Neonatology, Canberra Hospital, PO Box 11, Woden 2606 ACT, Australia e-mail: Alison.kent@act.gov.au A. L. Kent : B. Shadbolt Australian National University Medical School, Canberra, ACT, Australia R. Jyoti : C. Robertson : L. Gonsalves Department of Medical Imaging, Canberra Hospital, Woden, ACT, Australia S. Meskell Centre for Newborn Care, Canberra Hospital, Woden, ACT, Australia B. Shadbolt Clinical Epidemiology Unit, Canberra Hospital, Woden, ACT, Australia M. C. Falk Department of Nephrology, Canberra Hospital, Woden, ACT, Australia Pediatr Nephrol (2010) 25:913–918 DOI 10.1007/s00467-009-1414-4