Abdominalimaging

Functional MR Renography / Urography Project

Clinical background:

Children with congenital renal malformations require morphologic and functional assessment of the kidneys and urinary tracts for diagnosis, treatment decisions and follow-up. Imaging evaluation usually consists of several studies, including ultrasound, voiding cystourethrography, magnetic resonance (MR) imaging for assessing the anatomy, and scintigraphy for assessing renal function and obstruction of the urinary tracts. MRI has the potential to provide all required dynamic and morphologic information in a single, non-invasive and radiation free study, which would be very desirable in neonates and children. Morphologic assessment is already routinely performed with standard MR sequences (T1w – SE, heavily T2w -2D or 3D FSE). Renal function and drainage of the urinary tracts can be assessed by visualizing the passage of Gadolinium-based contrast material through the kidneys with dynamic acquisition of 3D gradient echo sequences. Segmentation of the kidney in its different components is a valuable tool to assess the anatomy. Analysis of the contrast concentration by measuring signal intensities in renal tissues over time and using tracer kinetic modelling can provide functional parameters such as split renal function, glomerular filtration rate, and renal transit time.

Purpose:

To implement and validate functional MR renography / urography software as diagnostic tool in children.

Tasks:

1) Development / improvement of postprocessing software, which allows:

• 3D segmentation of kidneys (cortex, medulla, collecting system)
  • Histogram analysis, region growing, etc…
• compensation of respiratory motion
  • cross correlation, spatial points in a temporal referential
• measurement of signal intensity curves over time
  • with semi-automatic region drawing, correction for baseline
• compartmentalization of the kidney to accurately assess renal
  function and excretion
  • 2-compartment, 3-compartment or Patlak model
• calculation of functional parameters with different methods
  • statistical analysis and decision

2) Compare the in house developed software to existing softwares for postprocessing our LAVA data, compare MR results (split renal function) to scintigraphy results

3) Prospective clinical evaluation of functional MR renography / urography in comparison to MAG 3 scintigraphy

4) Improvement of dynamic 3D GE acquisition

• Temporal resolution < 5s
• Spatial resolution (submillimeter at acquisition with high SNR)
  
• Reduction of artefacts (motion, susceptibility, etc..)
• validation of the linearity of signal intensity for expected Gad  concentrations

Contacts:

Christian Kellenberger, MD
Chief Diagnostic Imaging Department
christian.kellenbergerkispi.uzh.ch

Malek I. Makki, PhD
MRI physicist
malek.makkikispi.uzh.ch

Diagnostic Imaging Department
Kinderspital Zurich
Steinweisstrasse, 75
8032 – Zurich
Switzerland