MR urography in children. Part 1: how we do the F0 technique

Abstract

MR urography (MRU) has been widely accepted as a substitute to intravenous urography for investigating children with a dilated urinary tract after preliminary assessment by US and voiding cystourethrography. Hydronephrosis is by far the main indication for MRU because upper tract dilatation is a frequent condition in infants and children. Recent advances in technology have allowed MR to go beyond morphology and to assess renal function parameters such as split renal function and drainage. In this article we report our routine practice of the F0 MRU technique. The main advantages of our protocol are no requirement for general anaesthesia, no bladder catheterization, use of low-dose gadolinium-based contrast agent (0.05-0.1 mmol/kg) and total acquisition time of 30 min or less.

Neonatal Imaging Evaluation of Common Prenatally Diagnosed Genitourinary Abnormalities

“…Moreover, MRU is becoming a powerful alternative diagnostic tool that allows concurrent anatomical and functional evaluation without the use of ionizing radiation. 10,11 Compared with MAG-3 scanning, MRU also has superior intrinsic contrast and spatiotemporal resolution, allowing multiplanar 3-dimensional reconstructions that may potentially provide superior information regarding complex morphology. 26 MRU can provide essential information for differential diagnosis and surgical planning.…”

“…For these reasons, functional imaging is typically delayed until the age of 3 months. 6,9,10 If functional imaging is required, as in the case of a nonfunctioning kidney, the results of functional analyses performed in the early weeks of life need to be interpreted with caution owing to underdeveloped renal function. Functional information is commonly evaluated using mercaptoacetyltriglycine (MAG-3) scans.…”

“…5,6 However, the use of functional magnetic resonance (MR) urography (MRU) has increased, as it may permit simultaneous anatomical and functional evaluation without the use of ionizing radiation. [10][11][12] US is the first-line modality in neonatal GU tract imaging owing to its combination of excellent anatomical delineation, lack of ionizing radiation, widespread availability, capability for dynamic evaluation, decreased need for sedation, and low cost. The findings obtained with US usually direct further evaluations.…”

The Holy Grail of anatomic and functional MR urography in children

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These three recent technical innovation papers [1][2][3] will (must) contribute to the discussion around how to properly perform MR urography (MRU) in children.While the contribution of MRU to the anatomical evaluation of uropathies is well accepted, its contribution to functional evaluation remains controversial as there is no complete consensus on how to perform functional MRU, what sequences to use or what and when to inject.Both teams have done a great job trying to explain, standardize and promote their methods, with both approaches having pros and cons.MR urography is a great imaging method; it has many indications and large potential in children. Yet, any risk should be made as small as possible.

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“…These three recent technical innovation papers [1][2][3] will (must) contribute to the discussion around how to properly perform MR urography (MRU) in children.…”