Vessel Wall MR Imaging

Vessel Wall MR Imaging

Vessel wall MRI (VWI) is an advanced imaging technique and service available for our valued Penn patients & clinicians. Resources for this service include years of meticulously optimized cerebrovascular imaging pulse sequences/protocols, trained cerebrovascular MR technologists, and the invaluable interpretive expertise of the Penn Neuroradiologists.

Penn Vessel Wall Imaging

When & How to Order VWI

Select a clinical scenario below for guidance on when to order vessel wall MRI, the appropriate Epic examination(s), and site & scanner availability.

BRAIN VWI Stroke & Vasculopathy Brain vessel wall MRI/MRA
Clinical question

What is causing this patient’s intracranial arterial narrowing or ischemic stroke?

When to order

  • Routine CTA, MRA, or DSA shows stenoses and raises a specific diagnostic question requiring vessel wall characterization.
  • Evaluate recurrent or otherwise unexplained (cryptogenic) ischemic stroke when an intracranial vascular cause is suspected.
  • Differentiate among intracranial atherosclerosis, CNS vasculitis, intracranial dissection, RCVS, and other intracranial vasculopathies.

Guide for Ordering Indications

Review the clinical indications and guidance on when to order this examination.

View indications and when to order →

Ordering Instructions

Penn Medicine Ordering

1MR Head Vessel Wall Vasculopathy With and Without IV Contrast
2MR Head Angio Vessel Wall Vasculopathy Without IV Contrast

Must order both MRI & MRA exams, which includes VWI, DWI, FLAIR, T2-weighted imaging, and SWI.

Ordering from Outside Penn Medicine

Order:

MR Head With and Without IV Contrast

MR Head Angio Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MR Imaging for Vasculopathy”

Available sites

HUP/Pavilion (3T and 1.5T), PMC (3T), PCAM (3T), Radnor (3T), and PAH (1.5T).

Important notes

  • This is an advanced problem-solving examination, not a screening study.
  • For vasculitis work-ups, recommend starting with only a Brain VWI examination. A combined Brain and Neck VWI Vasculitis examination is lengthy and prone to motion, which may result in a nondiagnostic examination. A shorter limited protocol may be available for selected patients. Consult Neuroradiology.
BRAIN VWI Subarachnoid Hemorrhage Brain vessel wall MRI/MRA
Clinical question

Is there an occult vascular source for angiogram-negative atraumatic subarachnoid hemorrhage?

When to order

  • Angiogram-negative atraumatic SAH after CTA and DSA are negative.
  • As an adjunct to, and after, the recommended diagnostic work-up.
  • Evaluate for a blister or perforator aneurysm, dissecting aneurysm, occult AVF/AVM, or a culprit lesion when multiple aneurysms are present.

Guide for Ordering Indications

Review supporting guidance for evaluation of angiogram-negative SAH.

AHA/ASA guideline →
Diagnostic algorithm →

Ordering Instructions

Penn Medicine Ordering

1MR Head Vessel Wall (SAH) With and Without IV Contrast
2MR Head Angio Vessel Wall (SAH) Without IV Contrast

Must order both MRI & MRA exams, which includes VWI, DWI, FLAIR, T2-weighted imaging, and SWI.

Ordering from Outside Penn Medicine

Order:

MR Head With and Without IV Contrast

MR Head Angio Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MR Imaging for Subarachnoid Hemorrhage”

Available sites

HUP/Pavilion (3T and 1.5T), PMC (3T), PCAM (3T), Radnor (3T), and PAH (1.5T).

Important notes

  • Optional: MR Cervical Spine With and Without IV Contrast may be ordered for posterior fossa SAH to evaluate for cervicomedullary AVF/AVMs. This adds an approximately 30-minute MR slot.
  • DSA remains the gold standard for AVF/AVM. MR Angiogram Neck evaluates the cervical carotid and vertebral arteries and is the incorrect order for this indication.
NECK VWI Arterial Dissection Cervical carotid or vertebral artery
Clinical question

Is there a cervical carotid or vertebral artery dissection?

When to order

  • Suspected cervical carotid or vertebral artery dissection.
  • Routine CTA or MRA neck raises a specific diagnostic question requiring vessel wall characterization.
  • Clarify equivocal luminal abnormalities and differentiate arterial dissection from other vasculopathies.
  • Due to wrap artifact from the shoulders, this examination cannot reliably assess vertebral artery origin dissections.

Guide for Ordering Indications

Order when a CTA/MRA questioned an arterial dissection in the neck.

Ordering Instructions

Penn Medicine Ordering

1MR Neck Angio Vessel Wall (Dissection) With and Without IV Contrast

Ordering from Outside Penn Medicine

Order:

MR Neck Angio With and Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MRA Imaging for Dissection”

Available sites

HUP/Pavilion (3T and 1.5T), PMC (3T), PCAM (3T), Radnor (3T), and PAH (1.5T).

Important notes

  • This is an advanced problem-solving examination, not a screening study.
  • In the order comments, specify the artery (carotid versus vertebral) and segment (e.g., before or after the level of carotid bifurcation; skull base; craniocervical junction) of concern.
NECK VWI Carotid Artery Plaque Plaque characterization and carotid web
Clinical question

Could carotid plaque or a carotid web be responsible for the patient’s ischemic event?

When to order

  • Routine CTA or MRA neck has been performed and raised a specific question requiring characterization of non-calcified tissue in the carotid artery.
  • Concern for vulnerable carotid plaque, including intraplaque hemorrhage, vs carotid web vs arterial dissection in the carotid artery.

Guide for Ordering Indications

Use when a CTA or MRA questions culprit non-stenotic carotid plaque, carotid web or carotid artery dissection.

Ordering Instructions

Penn Medicine Ordering

1MR Neck Angio Vessel Wall (Plaque) With and Without IV Contrast

Ordering from Outside Penn Medicine

Order:

MR Neck Angio With and Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MRA Imaging for Carotid Plaque”

Available sites

HUP/Pavilion (3T and 1.5T), PMC (3T), PCAM (3T), Radnor (3T), and PAH (1.5T).

Important notes

  • This is an advanced problem-solving examination, not a screening study, and is intended for targeted carotid plaque or carotid web characterization after a routine CTA or MRA neck.
NECK VWI Vasculitis Extracranial carotid or vertebral arteries
Clinical question

Is there inflammatory disease involving the extracranial carotid or vertebral arteries?

When to order

  • Concern for carotid or vertebral artery vasculitis.
  • Concern for TIPIC syndrome (carotidynia).
  • Routine CTA or MRA neck has been performed and raised a specific question.

Guide for Ordering Indications

Use when CTA or MRA questions extracranial arterial vessel wall inflammation.

Ordering Instructions

Penn Medicine Ordering

1MR Neck Angio Vessel Wall (Vasculitis) With and Without IV Contrast

Ordering from Outside Penn Medicine

Order:

MR Neck Angio With and Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MRA Imaging for Vasculitis”

Available sites

HUP/Pavilion (3T and 1.5T), PMC (3T), PCAM (3T), Radnor (3T), and PAH (1.5T).

Important notes

  • This is an advanced problem-solving examination, not a screening study. Please do not order Brain VWI and Neck VWI Vasculitis together during the initial evaluation, as the combined examination length may lead to motion. Discuss with neuroradiology; a shorter limited protocol may be available for selected patients.
GCA VWI Giant Cell Arteritis Temporal and occipital arteries of the scalp
Clinical question

Are there imaging findings of giant cell arteritis involving the temporal or occipital arteries in a patient over 50 years of age?

When to order

  • Suspected giant cell arteritis involving the temporal or occipital arteries.
  • Negative or equivocal temporal artery biopsy despite persistent clinical suspicion.
  • Need for noninvasive evaluation of cranial artery inflammation, including in suspected relapse.
  • Appropriate for outpatient evaluation in clinically stable patients.

Guide for Ordering Indications

Review patient selection, exclusions, and guidance on when to order GCA VWI/MRA.

View indications and when to order → 2021 American College of Rheumatology Guidelines (see p. 1353) →

Ordering Instructions

Penn Medicine Ordering

1MR Head Angio Giant Cell Arteritis With and Without IV Contrast

Ordering from Outside Penn Medicine

Order:

MR Head Angio With and Without IV Contrast

In the comments/order indication, write:

“Vessel Wall MR Imaging for Giant Cell Arteritis”

Available sites

HUP/Pavilion, PMC, PCAM, and Radnor.GCA VWI/MRA is performed only on 3T scanners.

Important notes

  • GCA VWI must be performed on a 3T scanner to achieve the required spatial resolution. Patients with a contraindication to 3T cannot undergo this examination.
  • To promote resource stewardship, ordering of both temporal artery biopsy and GCA VWI concurrently are not recommended.
  • If a temporal artery biopsy is performed, await the biopsy results before ordering GCA VWI.
  • The 2021 American College of Rheumatology guidelines conditionally recommend temporal artery biopsy over MR for establishing a definitive diagnosis of GCA (see p. 1353).
  • MR Brain/Rapid Stroke may be ordered if there is concern for stroke. Routine MR Orbits may be ordered if visual deficits are present.

How to Interpret VWI

Select an examination below for the protocol, principal interpretation tasks, practical pearls, and available teaching resources.

BRAIN VWI Stroke & Vasculopathy Intracranial vessel wall MRI/MRA
Interpretation task

Characterize the distribution and morphology of intracranial vessel wall thickening and enhancement, and integrate the findings with the luminal abnormality and infarct pattern.

Protocol

  • Pre- and postcontrast vessel wall imaging
  • TOF MRA
  • DWI, SWI, high-resolution T2-weighted TSE, and FLAIR
  • Limited option: pre/post VWI, T2-weighted imaging, and SWI

Interpretation pearls

  • Compare pre- and postcontrast VWI directly before assigning enhancement.
  • Use high-resolution T2-weighted imaging and VWI together to assess eccentric versus concentric wall thickening.
  • Correlate the wall abnormality with the TOF MRA and the vascular territory of ischemia.
  • Avoid interpreting enhancement in isolation; morphology, distribution, and clinical context matter.

Brain VWI/MRA Interpretation Resources

Start with the fundamentals video for a stepwise approach, then use the interpretation summary as a point-of-care reference.

ASNR 2021: VWI Interpretation Fundamentals

Open the interpretation summary →
BRAIN VWI Subarachnoid Hemorrhage Angiogram-negative SAH evaluation
Interpretation task

Identify a potential occult culprit lesion and determine whether the vessel wall and hemorrhage pattern localize to a plausible source.

Protocol

  • Pre- and postcontrast vessel wall imaging
  • TOF MRA
  • DWI, SWI or 3D T2*, high-resolution T2-weighted TSE, and FLAIR
  • Optional limited cervical spine: sagittal pre/post T1-weighted and sagittal T2-weighted imaging

Interpretation pearls

  • Use pre/post VWI to assess focal wall enhancement, wall irregularity, enhancing clot, or a subtle dissecting lesion.
  • Use SWI or T2* imaging to identify the epicenter and distribution of hemorrhage.
  • When a limited cervical spine examination is obtained, evaluate for serpiginous flow voids and cord edema suggesting a cervicomedullary AVF/AVM.
  • VWI is an adjunct; DSA remains the reference standard for AVF/AVM evaluation.

Interpretation resource

Use the SAH interpretation guide for a structured approach to angiogram-negative subarachnoid hemorrhage.

Open the VWI-SAH interpretation guide →
NECK VWI Neck VWI Options Dissection, carotid plaque, and vasculitis
Interpretation task

Apply the indication-specific sequence to characterize mural hematoma, intraplaque hemorrhage, or inflammatory wall edema and enhancement.

Core protocol

  • Pre- and postcontrast coronal vessel wall imaging
  • Postcontrast MRA
  • Indication-specific sequence selected according to the clinical question

Indication-specific approach

  • Dissection: axial precontrast T1-weighted TSE with fat suppression for mural hematoma.
  • Carotid plaque: coronal precontrast T1-weighted MPRAGE with fat suppression for intraplaque hemorrhage.
  • Vasculitis: axial STIR for vessel wall edema, interpreted with postcontrast wall enhancement.
  • Correlate the wall finding with the luminal abnormality and the precise artery and segment identified in the order.

Interpretation resource

Neck VWI interpretation guide is in development.

GCA VWI Giant Cell Arteritis Temporal and occipital arteries of the scalp
Interpretation task

Evaluate the temporal and occipital arteries for abnormal wall enhancement while confirming that the enhancing structure corresponds to an artery on the TOF MRA.

Protocol

  • TOF MRA of the scalp arteries
  • Postcontrast high-resolution vessel wall imaging
  • Performed on a 3T scanner for the required spatial resolution

Interpretation pearls

  • Evaluate the superficial temporal and occipital arterial territories systematically and bilaterally.
  • Confirm the vessel on TOF MRA before attributing enhancement to an artery rather than an adjacent vein.
  • Assess the distribution, conspicuity, and symmetry of arterial wall enhancement.
  • Interpret imaging findings in the context of symptoms, inflammatory markers, treatment timing, and biopsy results when available.

Interpretation resource

Use the scalp VWI guide for a structured approach to temporal & occipital artery assessment.

See also Teaching Case #5.

Open the GCA interpretation guide →