Consider non-contrasted if GFR <30 mL/min, acute kidney injury, or if the patient has a severe gadolinium contrast allergy. LINK: MUSC POLICIES WEBSITE (click “Documents” then “Search”)
If considering contrast in the above scenarios and there’s no alternative imaging evaluation (like for myocardial fibrosis/viability, amyloidosis, fibrosis to evaluate source of ectopy), make sure all teams are on board (primary, nephrology, etc)
“Viability” protocol is the basis of almost all cardiac MR protocols and consists of the following acquisition phases:
Pre-Contrast
Overview of chest with SSFP, HASTE, and 2/3/4 chamber cine
High TI (inversion recovery-based sequence, most helpful for clot detection)
at 1.5T it’s around 600 msec, and has to be longer for 3T (around 800 msec)
Nulled TI
TI is again higher for stronger (3T) magnet
Flow
If you want to add flow across a valve, then type the name of the protocol you want and add “+ [Valve Name] Flow”. For example, if you wanted a viability protocol and flow across the aortic valve then you would type “Viability + Aortic Valve Flow” into the protocol box
If HOCM suspected, add “flow without/with valsalva” (in plane 3 chamber and through plane LVOT)
If looking for ventricular septal defect or any kind of shunt, aorta and main pulmonary artery flow are needed. MRI/MRA chest can be helpful as defects/shunts usually are associated with other anomalies
If special sequences such as T1 mapping (extracellular infiltrate/fibrosis), T2 mapping (edema/inflammation), or T2* mapping (iron quantification) are required or requested by provider, be sure and type them in the protocol box
T2: mainly in research studies, sometimes helpful
T2*: report quantification in the septum
Checking Cardiac MR Studies
For acute issues (i.e. weekends, call, etc.):
high TI sequence–> thrombus
post contrast VIBE–> pulmonary embolism
delayed enhancement–> MI/fibrosis (can be a source of life-threatening arrhythmia)
If flow artifact present on SSFP–> tell tech to add flow across that valve
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVD)
Indications: Arrhythmias/PVCs, cardiac mass
Acquisition Phases
Viability as above + axial cine stack (for right ventricular function)
If to assess cardiac mass, add “extend SA slices through atria”
Chest Angiography (MRA Chest)
Indications:
Severe iodinated contrast allergy AND
Suspected Acute Aortic Pathology
Pulmonary Embolism
Notes
Usually performed with contrast (helps with PE detection sensitivity and identifying other associated vascular malformations)
Decision for contrast should not delay imaging, as any acute aortic pathology and large central PEs can be seen without contrast
For acute pathology, type “add CINE images through the aortic root and ascending aorta” in protocol box
Congenital
Indications
Congenital heart disease
Suspected shunt
Notes
MRI heart and MRA chest with (preferred) or without contrast
Flow: Main pulmonary artery and aorta +/- left and right pulmonary arteries
Pericarditis
Indication: Restrictive vs constrictive process
Acquisition Phases
Viability as above + tagged cine (for pericardial tethering) + realtime deep inspiration cine (for ventricular interdependence)
Specify to “repeat high TI after nulled delay images” (better pericardial enhancement detection)
Viability
Indications
Cardiac Thrombus
Stroke
Suspected or known ischemic heart disease
Amyloid
Unknown cardiomyopathy
Valve Disease
Hypertrophic Obstructive Cardiomyopathy (HOCM)
Sickle Cell (Iron Overload)
Notes
If valve disease or HOCM:
Always do main pulmonary artery and aortic flow
If sick valve, perform flow across it
If HOCM, add inplane flow in the 3 chamber view and through plane flow in the LVOT without and with valsalva
If looking for iron overload:
Perform viability with T2* mapping OR non-contrasted cardiac MRI with T2* mapping. Either one should be done in 4 chamber and mid-ventricular short axis views
Try and catch liver if you can
Report the average T2* in septum
>20ms= Normal, 10-20ms= Mild, <10ms= Severe iron deposition
High TI images
Assess for hypointense regions which can represent clot
Can also be seen with MVO, calcification, some masses, and focal fatty infiltration (india ink artifact can give a focal dark region)
Delayed Enhancement: Determine infarct extent and transmurality
Describe in terms of location (apical, mid, basal), circumferential/laterality descriptor (like apical anterior, mid inferolateral, etc), and % myocardial thickness involved (never say 50% involvement, rather give an estimate less than or greater than 50%)
Goal is to determine whether stenting a vascular territory will improve function (hence viable <50% or nonviable >50%)
NOTE: proximal territory may be nonviable/transmural, but distal could still be viable
Sarcoid
Indication: Cardiac sarcoid
Acquisition Phases
Viability as above with more images of the entire chest
Diffusion
Notes
Look for patchy delayed enhancement in the heart and active inflammation in lymph nodes and lungs
Stress Perfusion
Indication: Suspected stress inducible ischemia
Note
Cardiology fellow should always be present
Performed with Lexiscan or Regadenoson
How to manage artifacts
Spatial aliasing/Wraparound–> increase FOV, phase FOV, or phase oversampling
Off resonance artifacts–> frequency scout
Too much flow or susceptibility artifact on phase–> increase bandwidth, change from SSFP to a spoiled GRE
Spatial aliasing on flows–> increase VENC (technically no limit, but above 400 is already severe)
Difficulties with triggering/EKG problems–> can trigger using pulse ox, can also usually be circumvented using free breathing sequences
If arrhythmias–> switch to prospective triggering, conventional GRE, or use multiple averages (NEX = 4)
Radiology Protocols 