MRI, MRA, MRV: What’s the Difference?

If your health­care provider has ordered an MRI, MRA or MRV of your head, the sim­i­lar-sound­ing acronyms can be con­fus­ing. All three exams use mag­net­ic res­o­nance tech­nol­o­gy, but each is designed to show dif­fer­ent structures.

A brain MRI pri­mar­i­ly eval­u­ates the brain and sur­round­ing tis­sues. An MRA focus­es on arter­ies, while an MRV focus­es on veins. Depend­ing on your symp­toms and what your provider needs to eval­u­ate, more than one of these exams may be per­formed dur­ing the same appointment.

What is the dif­fer­ence between an MRI, MRA and MRV?

MRI, MRA and MRV all use a strong mag­net­ic field, radio waves and a com­put­er to cre­ate detailed images. Unlike X‑rays and CT scans, these exams do not use ion­iz­ing radiation.

What is a brain MRI?

Mag­net­ic res­o­nance imag­ing, or MRI, is the broad term for an imag­ing exam that uses a pow­er­ful mag­net­ic field, radio waves and com­put­er tech­nol­o­gy to cre­ate detailed images of struc­tures inside the body.

A brain MRI pro­duces detailed images of the brain and sur­round­ing tis­sues. Unlike the orig­i­nal descrip­tion of MRI as a gen­er­al scan of the ​“entire head,” the exact area and image sequences are select­ed accord­ing to the symp­toms or con­di­tion your provider is evaluating.

A brain MRI may help evaluate:

• Headaches, dizzi­ness or unex­plained weakness
• Stroke or bleed­ing in the brain
• Brain tumors
• Mul­ti­ple scle­ro­sis and oth­er inflam­ma­to­ry conditions
• Seizures
• Infec­tions
• Trau­mat­ic brain injuries
• Pitu­itary gland disorders
• Changes involv­ing the eyes or inner ears
• Mem­o­ry loss, con­fu­sion or oth­er neu­ro­log­i­cal symptoms

Some brain MRI exams are per­formed with­out con­trast. Oth­ers use a gadolin­i­um-based con­trast agent to make cer­tain tis­sues, blood ves­sels or areas of inflam­ma­tion eas­i­er to see. Your provider and radi­ol­o­gy team deter­mine the appro­pri­ate pro­to­col based on the rea­son for your exam.

What is an MRA?

Mag­net­ic res­o­nance angiog­ra­phy, or MRA, is a type of mag­net­ic res­o­nance exam designed to eval­u­ate blood ves­sels, par­tic­u­lar­ly arteries.

An MRA cre­ates detailed images of arter­ies and blood flow while reduc­ing the visu­al empha­sis on sur­round­ing tis­sues. An MRA of the head or neck may be used to look for:

• A brain aneurysm
• Nar­rowed or blocked arteries
• Abnor­mal con­nec­tions between blood vessels
• Changes that may affect blood flow to the brain
• Cer­tain caus­es of stroke or tran­sient ischemic attack

An MRA may be per­formed with or with­out con­trast. Many MRA exams of the brain use a tech­nique that can show flow­ing blood with­out an injec­tion. Oth­er exams may use con­trast to improve the appear­ance of par­tic­u­lar blood vessels.

What is an MRV?

Mag­net­ic res­o­nance venog­ra­phy, or MRV, is a type of mag­net­ic res­o­nance exam that focus­es on veins and the flow of blood back toward the heart.

An MRV of the head may be ordered when a provider needs to exam­ine the brain’s veins and venous sinus­es. It may help evaluate:

• Cere­bral venous sinus throm­bo­sis, a blood clot in the brain’s venous drainage system
• Nar­row­ing or block­age of a vein
• Abnor­mal venous anatomy
• Changes in venous blood flow
• Cer­tain caus­es of headaches, swelling or increased pres­sure around the brain

An MRV does not always require con­trast. Some tech­niques use the move­ment of blood to pro­duce images with­out an injec­tion, while oth­er MRV pro­to­cols use con­trast to make the veins more vis­i­ble. The radi­ol­o­gist selects the tech­nique best suit­ed to the clin­i­cal question.

Why might your provider order more than one exam?

MRI, MRA and MRV pro­vide com­ple­men­tary infor­ma­tion. Your provider may order more than one because brain tis­sue, arter­ies and veins can each play a dif­fer­ent role in your symptoms.

For exam­ple:

• An MRI can show whether brain tis­sue has been affect­ed by a stroke, while an MRA can eval­u­ate the arter­ies sup­ply­ing that area.
• An MRI can eval­u­ate the brain for struc­tur­al caus­es of a headache, while an MRV can look for a blood clot or nar­row­ing in the venous system.
• An MRI can eval­u­ate a mass or abnor­mal area, while an MRA or MRV can show its rela­tion­ship to near­by blood vessels.

Even when mul­ti­ple exams are ordered, they may be com­plet­ed dur­ing one imag­ing ses­sion. Your appoint­ment length will depend on the num­ber of images need­ed and whether con­trast is used.

Will you need MRI contrast?

Con­trast is not auto­mat­i­cal­ly required for an MRI, MRA or MRV. Whether it is used depends on the part of the body being exam­ined, the imag­ing tech­nique and the con­di­tion your provider is investigating.

When need­ed, a gadolin­i­um-based con­trast agent is usu­al­ly inject­ed into a vein. It can improve the vis­i­bil­i­ty of cer­tain tis­sues, blood ves­sels, tumors, inflam­ma­tion or areas where the blood-brain bar­ri­er has been disrupted.

Before receiv­ing con­trast, tell your care team if you:

• Have kid­ney dis­ease or reduced kid­ney function
• Have pre­vi­ous­ly had a reac­tion to MRI contrast
• Are preg­nant or think you may be pregnant
• Are breast­feed­ing
• Have recent­ly received a gadolin­i­um-based con­trast agent

The ben­e­fits and risks of gadolin­i­um-based con­trast agents are con­sid­ered before they are admin­is­tered. Your radi­ol­o­gy team will use con­trast only when it is expect­ed to pro­vide use­ful diag­nos­tic information.

How should you pre­pare for an MRI, MRA or MRV?

Because MRI uses a pow­er­ful mag­net­ic field, your imag­ing team must review your health his­to­ry and any met­al or elec­tron­ic devices in or on your body.

Before your appoint­ment, tell the imag­ing team if you have:

• A pace­mak­er, defib­ril­la­tor or implant­ed heart monitor
• A cochlear implant
• Aneurysm clips
• An insulin pump or con­tin­u­ous glu­cose monitor
• A neu­rostim­u­la­tor or oth­er implant­ed elec­tron­ic device
• Met­al frag­ments, shrap­nel or a his­to­ry of metalworking
• Arti­fi­cial joints, plates, screws or oth­er implants
• Preg­nan­cy or a pos­si­bil­i­ty of pregnancy
• Claus­tro­pho­bia or dif­fi­cul­ty remain­ing still

Many mod­ern med­ical implants can be scanned safe­ly under spe­cif­ic con­di­tions, but the imag­ing team needs the device’s exact type and mod­el. Bring your implant iden­ti­fi­ca­tion card when available.

Jew­el­ry, watch­es, hear­ing aids, remov­able den­tal work, phones and oth­er met­al or elec­tron­ic items must remain out­side the MRI room. Fol­low any eat­ing, drink­ing or med­ica­tion instruc­tions pro­vid­ed when your appoint­ment is scheduled.

What hap­pens dur­ing the exam?

Dur­ing the exam, you will lie on a padded table that moves into the MRI scan­ner. A device called a coil is placed around your head to help cre­ate the images. The coil does not pro­duce radi­a­tion and should not touch your face.

The scan­ner makes loud tap­ping, knock­ing or buzzing sounds as it col­lects images. You will receive ear pro­tec­tion, and the tech­nol­o­gist will be able to see, hear and com­mu­ni­cate with you through­out the exam.

It is impor­tant to remain as still as pos­si­ble because move­ment can blur the images. You may be asked to hold still for sev­er­al min­utes at a time while dif­fer­ent image sequences are completed.

If con­trast is need­ed, an intra­venous line will be placed in your hand or arm. Most peo­ple can resume their usu­al activ­i­ties after the exam unless they received med­ica­tion to help them relax.

Are MRI, MRA and MRV safe?

MRI does not use ion­iz­ing radi­a­tion. For most patients, it is a safe and non­in­va­sive exam when appro­pri­ate screen­ing and safe­ty pro­ce­dures are followed.

The mag­net­ic field can inter­act with cer­tain devices or met­al objects, which is why the safe­ty ques­tion­naire is essen­tial. Nev­er enter an MRI room with an item that has not been cleared by the technologist.

Seri­ous reac­tions to gadolin­i­um-based con­trast agents are uncom­mon, but no med­ica­tion is risk-free. Your care team will review your med­ical his­to­ry and deter­mine whether con­trast is appropriate.

Who reviews your images?

An MRI tech­nol­o­gist per­forms the exam, but a radi­ol­o­gist — a physi­cian who spe­cial­izes in med­ical imag­ing — reviews and inter­prets the images. The radi­ol­o­gist then pre­pares a diag­nos­tic report for the provider who ordered the exam.

The report com­mon­ly includes the rea­son for the exam, the imag­ing tech­nique, rel­e­vant find­ings and the radiologist’s over­all impres­sion. Your order­ing provider will explain how the find­ings relate to your symp­toms and care plan.

MRI and advanced imag­ing at Duly Health and Care

Duly Health and Care offers advanced diag­nos­tic imag­ing in safe, com­fort­able loca­tions across Chicago’s sub­urbs. Our sub­ur­ban-based com­pre­hen­sive care net­work con­nects radi­ol­o­gy with pri­ma­ry and spe­cial­ty care, help­ing your providers coor­di­nate imag­ing, results and next steps.

Duly uses state-of-the-art High-Field MRI scan­ners rang­ing from 1.5T to 3.0T. These scan­ners pro­duce detailed images that help board-cer­ti­fied radi­ol­o­gists iden­ti­fy and char­ac­ter­ize abnor­mal­i­ties and pro­vide your order­ing provider with infor­ma­tion to guide your care.

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Fre­quent­ly asked questions

Is an MRA the same as an MRI?

An MRA is a spe­cial­ized type of MRI. A stan­dard brain MRI pri­mar­i­ly eval­u­ates brain tis­sue and sur­round­ing struc­tures, while an MRA is designed to eval­u­ate arter­ies and blood flow.

Is an MRV the same as an MRA?

No. An MRA gen­er­al­ly focus­es on arter­ies, which car­ry blood away from the heart. An MRV focus­es on veins, which return blood toward the heart. In the head, an MRV also eval­u­ates the venous sinus­es that drain blood from the brain.

Does an MRA always require contrast?

No. Many head MRA exams can pro­duce detailed pic­tures of blood ves­sels with­out con­trast. Oth­er MRA tech­niques use con­trast, depend­ing on the ves­sels being exam­ined and the infor­ma­tion the radi­ol­o­gist needs.

Does an MRV always require contrast?

No. MRV can be per­formed with or with­out con­trast. The pro­to­col depends on the clin­i­cal con­cern, the blood ves­sels being eval­u­at­ed and the imag­ing tech­nol­o­gy used.

Can MRI, MRA and MRV be com­plet­ed at the same appointment?

Often, yes. Because they use the same MRI scan­ner, mul­ti­ple exams may be com­plet­ed dur­ing one appoint­ment. The ses­sion may take longer because each exam requires its own set of images.

How long does an MRI of the head take?

The length of the exam varies based on the num­ber of image sequences, whether con­trast is used and whether an MRA or MRV is per­formed at the same time. Your sched­ul­ing team can pro­vide an esti­mat­ed appoint­ment length based on the exams ordered.

What should I do if I am claustrophobic?

Tell your order­ing provider and the imag­ing team before your appoint­ment. They can explain the scan­ner, dis­cuss com­fort mea­sures and deter­mine whether med­ica­tion is appro­pri­ate. If med­ica­tion is pre­scribed for anx­i­ety, you may need some­one to dri­ve you home.

When will I receive my MRI results?

A radi­ol­o­gist must review the images and send a report to the provider who ordered the exam. Tim­ing can vary depend­ing on the type and urgency of the study. Con­tact your order­ing provider if you have ques­tions about when and how your results will be shared.

Care at Duly Health and Care

MRI, MRA and MRV exams use the same mag­net­ic res­o­nance tech­nol­o­gy but pro­vide dif­fer­ent infor­ma­tion. An MRI focus­es pri­mar­i­ly on brain tis­sue, an MRA eval­u­ates arter­ies and an MRV exam­ines veins.

Your provider and radi­ol­o­gy team will deter­mine which exam — or com­bi­na­tion of exams — can best answer the clin­i­cal ques­tion. They will also decide whether con­trast is need­ed based on your symp­toms, med­ical his­to­ry and the struc­tures being examined.

At Duly, advanced MRI tech­nol­o­gy and board-cer­ti­fied radi­ol­o­gists work togeth­er with your refer­ring provider to deliv­er clear answers and help guide the next step in your care.

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