Aims and objectives
Renal artery stenosis is a treatable cause of hypertension.
Aprox.
90% is caused by atherosclerosis and it affects mostly the ostium and proximal part of the artery.
The aim of this study is to verify the correlation between computed tomography angiography (CTA) and Time-of-Flight magnetic resonance angiography (TOF-MRA) in the evaluation of renal arteries stenosis,
in order to prove the reliability of unenhanced MRA and the possibility of replacing the CTA.
Even thought new unenhanced MR angiographic sequences have emerged,
TOF is available in most...
Methods and materials
This is a board–approved,
double-blinded review.
Patient demographics,
CTA and MR imaging findings,
were retrospectively obtained from the electronic medical records.
MRI were carried out in a 1.5T Symphony Tim (Siemens,
Erlangen,
Germany),
using a 6-channel body coil.
The 3D TOF sequence was acquired during free-breathing,
with a total acquisition time of 6min,
and the following imaging parameters: water excitation,
excitation FA=25º,
axial-oriented slab consisting of 92 partitions of 0.9mm thickness distributed in 3 blocks,
in-plane FOV=271x406 mm2,
Matrix=179x384,
TR/TE=36/4.6 ms,
BW=70 Hz/px,
phase-encoding (PE)...
Results
In our study,
there is a good agreement between both techniques for the degree of stenosis in the ostium/proximal part of the renal arteries (kappa: 0.79).
Sensitivity,
specificity,
positive predictive value and negative predictive value are 89%,
99%,
89% and 99%,
respectively.
The evaluation of the distal part of the artery is limited with the ARM-TOF (sensitivity,
specificity,
positive predictive value and negative predictive value are 66,7%,
98,18%,
50% and 99%,
respectively).
When the stenosis is < 60%,
there is a small difference between both...
Conclusion
TOF-MRA is a reliable technique (but not 100% precise) for excluding clinically relevant stenosis of the proximal portion of the main renal arteries.
A negative test may exclude stenosis and patients can benefit from the absence of radiation and contrast media.
A positive test could be confirmed with other imaging technics because there are some limitations that may cause a false positive image.
TOF-MRA could be considered an alternative in patients with contraindications for contrast media (allergy or renal insufficiency).
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