case studies

Renal MRA

Introduction
MRI is a good diagnostic tool to rule out renal stenosis without of the use of invasive procedures such as conventional angiography, which would require a hospital stay due to the invasive nature of catheterisation of the renal vessels via a femoral artery cut down. Renal MRA is a minimally invasive diagnostic imaging technique that can be used to investigate the renal vessels for those patients who are hypotensive, or for investigation of most other renal pathologies that require visualisation of the renal arterial supply.

Patient History
A 50 year old male with a long history of hypotension was referred for a renal MR Angiogram with Gadolinium enhancement.

Methodology
The images were required on a 1.5 T IGE LX Signa Horizon unit. An axial T2 Single Shot Fast Spin Echo was used for the localiser, in order to demonstrate the renal vessels and to allow for precise positioning of the coronal acquisition.

The MRA was acquired in using the coronal 3 D vascular SPGR sequence, and images were acquired both pre and post Gadolinium, using a breath hold technique.

As part of the preparation for examination the patient had placed in situ a 21 gauge needle and a 150 cm connection tube, attached to a syringe with 25mls of Gadolinium.

Once the images were acquired they were post-processed using a maximum intensity projection algorithm, so the 3D volume data could be visualised from different directions.

Radiologist’s Report
The MRI confirms the ultrasound findings of a small left kidney. The MRA demonstrated the renal arteries completely, with no evidence of renal artery stenosis. An accessory artery is visible on the right, rising from the abdominal aorta just above the bifurcation (figs. 1 and 2)

Conclusion
Gadolinium enhanced MRA has been successfully utilised in this examination to demonstrate that the patient had no significant renal pathology to account for his hypotension. This had been achieved through a minimally invasive diagnostic technique, with significantly reduced chances of complications due to infection, unexpected haemorrhage and aneurysms secondary to the catheterisation.

It should also be noted that the MRI studies allow for visualisation of renal function (fig. 3) where the renal cortex and calyceal pattern is demonstrated.

This means that in one minimally invasive examination a comprehensive investigation of the kidneys, including angiography and renal function, can be achieved in less than 30 minutes.

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