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Better evaluation of stenosis in steady state with Ablavar

Case Study
Maki, Jeffrey, M.D., Ph.D. University of Washington • USA

Patient history

A 70-year-old male with hypertension and hyperlipidemia presented with a non-healing left great toe ulcer. In order to better define his vascular anatomy and plan possible revascularization, a peripheral MRA was done with Achieva 1.5T at the Puget Sound VA HCS, Seattle, USA.

MR examination

Achieva 1.5T was used with the 12-channel Peripheral Vascular Coil.

A blood-pool agent was used. Single injection moving table pMRA using 10 mL Ablavar (gadofosveset, Lantheus Medical) injected 5 mL at 1mL/sec and 5 mL at 0.6 mL/sec followed by a 25 mL saline flush at 0.6 mL/sec. 

 

First pass was triggered at the aortic bifurcation using BolusTrak, with

- upper station:  voxels 1.2 x 2.0 x 2.2 mm, scan time 13 sec

- middle station: voxels 1.2 x 1.8 x 1.8 mm, scan time 13 sec

- lower station: voxels 1.1 x 1.1 x 1.1 mm, scan time 70 sec 

 

Sub-diastolic thigh BP cuffs (60 mm Hg) were applied for the mask and first pass only.

Steady state high resolution imaging was performed in all 3 stations (from lower to upper), with

- lower station: voxels 0.8 x 0.65 x 0.65 mm, scan time 5:00 min

- middle station: voxels 1.0 x 0.8 x 0.8 mm, scan time 2:47 min

- upper station: voxels 1.0 x 0.9 x 0.9 mm, scan time 4:47 min


ExamCard used:

Images

MIP first pass, 3 stations
MIP first pass, 3 stations


In the fused 3-station MIP of the first pass pMRA using Ablavar, image quality is good in all three stations, without venous contamination. There is bilateral iliac arterial ectasia with right external iliac stenosis and bilateral SFA occlusion.

First pass Coronal source <br>
1.2 x 2.0 x 2.2 mm voxelsFirst pass Sagittal reformat <br>
1.2 x 2.0 x 2.2 mm voxels
First pass
First pass
Coronal source
1.2 x 2.0 x 2.2 mm voxels
Sagittal reformat
1.2 x 2.0 x 2.2 mm voxels
Steady state Coronal source <br>
1.0 x 0.9 x 0.9 mm voxelsSteady state Sagittal reformat <br>
1.0 x 0.9 x 0.9 mm voxels
Steady state
Steady state
Coronal source
1.0 x 0.9 x 0.9 mm voxels
Sagittal reformat
1.0 x 0.9 x 0.9 mm voxels
First pass Zoomed MIPSteady state Subvolume MIP
First pass
Steady state
Zoomed MIP
Subvolume MIP


In the first pass coronal source and sagittal reformatted images of the right external iliac stenosis are seen.

Similar steady state images demonstrate significant improvement in anatomic depiction of the external iliac stenosis (arrows) and extensive plaque.


The zoomed MIP of the first pass left popliteal region shows poor filling of the distal popliteal artery(white arrows, corresponding to inferior dashed box). In such cases, it is often a perplexing challenge to determine if this represents slow filling artifact, edge of coil artifact, or true disease. The steady state subvolume MIP through the distal left popliteal artery shows it to be definitively disease free (black arrows), meaning the first pass appearance represents artifact.

Diagnosis

Iliac disease with high grade right EIA stenosis and bilateral SFA occlusion. 
Artifactual poor filling of the distal left popliteal artery.

Impact of Ablavar Steady State imaging

This case demonstrates the benefit of steady state images for improving depiction of stenoses in aortioiliac MRA.  First pass imaging, as performed here as part of a 3-station pMRA study, has sub-optimal resolution to accurately resolve the degree of right external iliac stenosis – a common problem with first pass CE-MRA. 

Steady state imaging, however, provides much better anatomic detail of this high grade stenosis – not only of the lumen, but also of the plaque. Furthermore, poor opacification of the distal left popliteal artery is determined by steady state to merely represent underfilling due to early timing, rather than true disease. Such determinations may prevent additional imaging using DSA to clarify the anatomy.



Related reading:



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Nov 10, 2011

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Case Study
Achieva 1.5T
Release 2
ablavar, stenosis, Vascular
 

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