Ferumoxytol (Frx) is an MRI contrast media with no toxicity concerning gadolinium-based contrast in ptns with progressive kidney disease.
Ferumoxytol
(Frx)-enhanced
MRI for planning hemodialysis (HDX) AV
access (Oct 2020)
Ferumoxytol (Frx) is an MRI
contrast media with no toxicity concerning gadolinium-based
contrast in ptns with progressive kidney disease. Study: imaging
the vasculature of 59 ptns before HDX A/V
fistula development, Frx-enhanced MRI identified
15 central venous lesions
& significantly more arterial partition
that are not amenable for AV fistula
creation as compared with US (37 vs
26 %). The simultaneous evaluation of central & peripheral
venous anatomical details with FE-MRI
was more comprehensive for the AV
fistula longevity than using peripheral venous assessment alone or via using US. According to the conclusions of this study,
FE-MRI seems to be more beneficial for ptns with:
1) Prior
access failure.
2) Borderline vasculature via duplex US, or
3) Associated
risk for central venous stenosis or PVD.
Ferumoxytol (Frx)-enhanced imaging
Frx is composed of ultra-small paramagnetic Fe oxide embedded in a CHO coating
& got the approval of the US FDA as a therapeutic iron supplement.
It is cleared from the circulation via the reticuloendothelial
system macrophages of the liver, spleen,
& bone marrow. Considering its iron content, Frx can be used as a contrast medium for
the MRI testing ("off label"). Frx has prolonged ½ -life
(15 h.) that permits the imaging of both venous &
arterial vasculature with no need for
bolus timing, with excellent imaging results
for peripheral & central veino-arterial
system.
The introduction of Frx-enhanced MR for vascular
assessment prior to AV access development has been reported. Study:
59 ptns, 51 AV fistulas were developed,
of which 24 (47
%) succeeded. 15
central venous lesions were not reported before
were recognized. Frx- MR angiography &
duplex US
recognized the same number of peripheral venous partitions unsuitable for fistula development; however, Frx-enhanced MR
recognized more unsuitable arterial partitions
(37 vs 26 %). Accuracy of imaging for predicting
AV fistula development success was
identified according to:
1)
Age, sex, & US reports
2)
Frx-MR angiography of peripheral vasculature alone.
3)
Frx-MR angiography of central & peripheral vasculature.
Among the 3 models studied, Frx -enhanced angiography
of the central & peripheral vasculature predicted AV fistula longevity is the best. The
inter-reader agreement for measurements of the arterial diameter, venous
diameter, and vein depth from skin surface was quite
excellent. Frx is safe for MRI of ptns who had not yet commencing DX, with no concerns
about toxicity related to iodinated or
gadolinium-content contrast media.
However, some allergic reactions may occur. Frx should not be administrated to ptn with allergic history to any IV iron agent.
Despite more costly as compared to US, Frx-enhanced MR angiography seems
to be more beneficial to ptns with borderline
vessels via duplex US or prior access failure, and with the risky central
veins for stenosis or PVD.
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