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Angiography - Peripheral magnetic resonance angiography (MRA)

a) SCMR official document standardized acquisition guidelines – relevant extract

1. Peripheral vascular coil, or combination of coils, as available. Venous compression cuffs (placed on the thighs, and inflated to sub-diastolic pressure) are helpful, if available.
2. Transaxial, low-resolution, vessel scouting with timeof-flight MRA or SSFP.
3. Gadolinium timing
   a. Option 1 -Transaxial test bolus at level of distal abdominal aorta. 2 ml injection of gadolinium, followed by 20ml saline. Determine time to peak enhancement following injection using a single-shot bolus tracking sequence.
   b. Option 2 – Bolus trigger technique to time start of scan
4. Stepping-table, gadolinium-enhanced MRA performed in the coronal projection from the mid abdominal aorta to the feet.
   a. Two volumetric acquisitions – one pre-contrast (for subtraction) and one during contrast administration.
   b. Gadolinium injected in 2 phases to minimize venous contamination followed by saline bolus.
   c. Slice thickness 1–1.5 mm; acquired spatial resolution in-plane 0.8–1.5 mm.
   d. Slices – typically 60–80, as needed to accommodate vessels of interest.
   e. Volumes obtained of abdomen/pelvis and thighs may be coarser spatial resolution (larger vessels), while those of the legs preferably are sub-millimeter spatial resolution. The former acquisitions typically require 15–20 seconds, while the leg acquisition may take 60–90 seconds for increased spatial resolution. Elliptical centric k-space acquisition is advantageous for the legs. If available, timeresolved acquisitions are preferred for the legs.
   f. Parallel acquisition recommended (multichannel surface coil needed)
5. Analysis
   a. 3D reconstructions may be helpful for an initial overview and visualizing the vasculature tree, but generally should not be used for primary decision making.
   b. Primary diagnoses are made by scrolling through source images (typically coronal and/or sagittal), and using selected thin slab MIP and MPR reconstructions in optimized orthogonal and oblique views for each station. The presence, number, and degree of stenoses are evaluated qualitatively. Alternative: dual injection protocol
   1. Single dose of gadolinium: time-resolved MRA of the calf and foot vessels
   2. Single dose of gadolinium: abdominal and thigh vessels
   

b) SCMR official document reporting recommendations – relevant extract

Peripheral arterial disease (2 recommended, 1 optional):

a)  Vessel location and orientation.  Descriptions of each territory are required  when the study is ordered to examine the respective site (recommended).  When severe stenoses or vessel occlusions are identified, common collateral pathways should be described. 
• Arch vessels
• Carotid bifurcation 
• Celiac trunk
• Proximal SMA
• Renal arteries and their accessory vessels
• Common and external iliac
• Femoral, brachial or other more peripheral arteries.
  b)  Quantitation of luminal narrowings or stenoses (recommended)  SCMR recommends that the CMR practitioner avoid descriptive  terms such as “mild” or “moderate” stenosis, but rather adopt a semi- quantitative method that scores the severity of luminal occlusion. Accordingly, stenosis severity should be reported in 25% increments  (i.e., <25%, 26% - 50%, 51% - 75%, and >75%) or, in cases with high  spatial resolution, finer increments of 10% may be employed.Descriptive terms may convey the wrong impression to the clinical importance of occlusive disease (e.g. a series of “moderate” stenoses in the diabetic patient with poor wound healing of the lower extremity may be clinically significant)
c)Optional functional measures of the vascular system may also be reported, including:
i.) flow measurements in the forms of milliliters or liters per minute, and 
ii.) measures of vascular stiffness: aortic distensibility, or pulse wave velocity. 
When functional measures are provided it is recommended that the vascular territories be specified and values provided at the specific location of acquisition.

c) Standardized web based images

None currently

d) Case of the Week example(s)

None currently

e) Expert opinion – ‘How we do’

None currently

f) Relevant Online Talks

Free talks

Vascular: Aorta and pulmonary circulation
By Raad Mohiaddin
Recorded at EuroCMR 2008

Angiography
By Georg Bongartz
Recorded at EuroCMR 2008

CE MRA
By Daniel Thomas
Recorded at SCMR 2008: Technicians Workshop

Members only talks - general

Optimizing MR Angiography
By Martin Prince - Cornell and Columbia Universities
Recorded at SCMR 2010

Arterial sclerosis and endothelial function
By F Alpendurada
Recorded at EuroCMR 2008

Members only talks - cutting edge

Low Dose Gadolinium MRA
By J Paul Finn - David Geffen School of Medicine at UCLA
Recorded at SCMR 2009 Nephrogenic Systemic Fibrosis Era - Contrast enhanced vs Non-contrast enhanced

NSF - Is this an overblown risk?
By Brett Elicker - UCSF Medical Centre
Recorded at SCMR 2009 Nephrogenic Systemic Fibrosis Era - Contrast enhanced vs Non-contrast enhanced

Non-contrast MRA - Abdominal Aora, Renal Arteries and Peripheral
By Robert Edelman - Evanston Hospital
Recorded at SCMR 2009 Nephrogenic Systemic Fibrosis Era - Contrast enhanced vs Non-contrast enhanced

Time Resolved Contrast-Enhanced MRA
By James Carr - Northwestern Memorial Hospital
Recorded at SCMR 2009 Nephrogenic Systemic Fibrosis Era - Contrast enhanced vs Non-contrast enhanced

 

g) Relevant papers (starting point):

Berry E, Kelly S, Westwood ME et al. The cost-effectivenss of magnetic resonance angiography for carotid artery stenosis and peripheral vascular disease: a systematic review. Health Tech Assess 2002;6:1–165.