Types of MRI Explained: Which One is Right for You?

Not all types of MRI are made the same. In fact, every MRI type is custom made to image specific medical patient criteria.

Is the patient immobile? Portable MRI can be delivered to the patient bedside.

Is the patient in a remote area? Mobile MRI units can be transported same day to meet patient imaging needs.

Whether it is closed MRI with a 1.5T MRI, or open MRI with a 1.0T MRI this article provides in-depth details to the advantages to each type of MRI to help add a little clarity for your medical imaging experience.

MRI is a powerful diagnostic tool offering various types of MRI tailored to meet specific patient imaging needs. From the more widely available closed MRI machines to open MRI or upright MRI models, each MRI type serves a distinct purpose, making them uniquely ideal in different diagnostic cases.

Additionally, there are different types of MRI scans, such as functional MRI (fMRI), diffusion-weighted imaging (DWI), and magnetic resonance angiography (MRA). Each MRI scan type is designed to highlight specific tissues or physiological processes. Understanding these different MRI machine types and scan methods is essential for accurate diagnosis and patient care.

Types of MRI Machines

1. Closed MRI

Closed MRI is the most widely used type of MRI in clinical practice. These systems feature a cylindrical design that house a superconductive magnet. To maintain the ultra-low temperatures required for optimal performance, the MRI scanner vessel contains liquid helium. This uniquely inert cryogen helps to keep the Niobium-Titanium magnet core supercooled 24 hours a day,

Advantages of Closed MRI

1. Higher Magnetic Field strength enables higher resolution imaging for more detailed diagnostic results.
2. Superior Image Clarity: The enclosed design of closed MRI provides higher signal to noise ratios when compared to open MRI designs, leading to higher definition images.

2. Open MRI

The Open MRI machine features a pillared design that allows for maximum patient visibility during MRI scans. Open MRI systems have a lower magnetic field when compared to Closed MRI designs. Open MRI systems range in magnetic field strengths from 0.3 Tesla to 1.0 Tesla, whereas Closed MRI designs range from 1.0 Tesla up to 7 Tesla in magnetic field strengths.

Advantages of Open MRI

Related article: Open MRI Pros and Cons & Closed MRI vs Open MRI

3. Stand-up MRI

Stand-up MRI may be a misnomer, as typically the patient is in a seated position. The more commonly used term is upright MRI. You can think of an upright MRI as flipping an Open MRI on its side and seating the patient in the center. It offers a comfortable patient scan experience and is ideal for musculoskeletal imaging that does not require higher magnetic fields.

Advantages of Open MRI

Patient can see in front of them maximum visibility

Comfortable patient scanning experience

less noisy than a 3T MRI or Mobile MRI,

4. Silent MRI

Is silent MRI truly silent? Unfortunately this is another misnomer that is based on the name of a specific MRI scanner design. While silent MRI designs significantly reduce noise by up to 20%, it is by no means silent. Patients must still be outfitted with hearing protection to ensure hearing damage does not occur.

Silent MRI scan sounds can reach maximum levels of 103 decibels, compared to traditional MRI design reaching maximum levels of 129 decibels

Advantages of Silent MRI

Noticeably quieter MRI sounds during exams.

Helps to reduce chance of long-term hearing damage during an MRI scan.

5. Portable MRI

Portable MRI is a compact, can be transported to patient bedside, ultra low field MRI scanner that is ideal when treating non-ambulatory patients. Design variations allow for specific targeting of anatomy. Most common designs are tailored to image extremities. It is ideally used in high volume hospital settings to supplement other imaging methods in a comprehensive diagnostic plan.

Advantages of Portable MRI

Can be transported to patient rooms

Fast, effective imaging using ultra-low field MRI

6. Mobile MRI

A mobile MRI unit is a transportable medical imaging trailer that contains a full-sized MRI. Though most mobile MRI systems are limited to 1.5 Tesla due to material constraints, mobile MRI is a reliable imaging choice that brings world-class medical resources to remote, underserved, or high-demand areas.

Advantages of Mobile MRI

The main advantage of a mobile MRI is accessibility. Mobile MRI units are the best imaging option to supplement underserved areas, or medical imaging facilities that require immediate imaging capabilities.

7. 3T MRI

A 3T MRI is a magnetic resonance imaging magnet with a magnetic field strength of 30,000 gauss. Why is this important? The higher magnetic field allows MRI scan machines to produce even more clear images than a 1.5T and 1T MRI. Additionally, the MRI operates at a resonant frequency of 128 MHz, which means the molecules within the magnetic field are spinning at a precession rate of 128,000,000 times per second! Which also means in order to interact with the molecules, the RF amplifies must produce sound waves that match the Larmor frequency of the molecules. This is the most common MRI system in clinical research settings.

Advantages of Open MRI

Related Article: GE MRI scanner models

8. 1.5T MRI

1.5T MRI has a magnetic field strength of 15,000 gauss and operates at larmor frequency of 63.86 MHz. This is the most commonly used MRI system in clinical diagnostic settings. 1.5T MRI systems are closed MRI designs that enables high resolution imaging across the entire body. 1.5T MRI is considered the standard of magnetic resonance imaging, however imaging capabilities vary by scanner model.

Advantages of 1.5T MRI

Widely available

Right mix of price and imaging capabilities suitable for most diagnostic imaging exams

9. 1.0T MRI

Allows for high resolution imaging in confined ferromagnetic environments though it offer considerably less imaging resolution and signal to noise ratios when compared to higher magnetic field strength MRIs.. Commonly found in outpatient imaging centers and mobile MRI units. Less common than closed and open MRI systems in clinical practice.

Advantages of 1.0T MRI

Cost-effectiveness

Better image resolution with metal

Safer for patients with medical imaging implants

Less local heating (SAR)

10. Ultra low field MRI

Ultra low field MRI are magnets with less than 0.3 Tesla in magnetic force. They are typically in the open MRI configuration but are distinctly smaller in height and often contain rare earth metals at the core of the magnet to help produce images. These are permanent magnets and are rarely used in clinical diagnostic settings.

Types of MRI Scans by Anatomy

Each type of MRI scan procedure is tailored to the anatomy of the patient. This includes MRI coil selection, patient positioning, comfort pad placement, and imaging protocol options. Click to learn more about each individual procedure with the list of MRI scan below. Links to helpful resources provided below (where available).

Types of MRI Scan Techniques

MRI with Contrast

Utilizes MRI contrast medium, such as gadolinium, to enhance visualization of blood vessels, tissues, and anomalous areas regions in the anatomy.

Functional MRI (fMRI)

Functional MRI, commonly shortened to fMRI, measures brain activity by mapping out the functional areas of increased blood flow.

MR Angiography (MRA)

MR Angiography helps to visualize blood vessels. MRA is especially useful to asses conditions like deep vein thrombosis or venous malformations.

Diffusion-Weighted Imaging (DWI)

DWI MRI detects the movement of water molecules (Brownian motion) to visualize soft tissue. It is especially useful for assessing strokes, monitor MS, and damaged soft tissue.

Diffusion Tensor Imaging (DTI)

DTI MRI is a technique that visualizes white matter tracts in the brain. It is especially useful when studying brain connectivity and neural pathways.

Perfusion MRI

Assesses blood flow in tissue by measuring how blood perfuses through an organ or tissue. Especially useful when evaluating tumors, stroke, or ischemia.

Spectroscopy MRI

Analyzes the chemical composition of the tissue within the scan field of view. It helps to visualize metabolic activity over time and is especially useful when monitoring tumors or brain activity.

MRI Types FAQ

What is the most common MRI?

1.5T Closed MRI is the most common type of MRI machine in clinical use.

What is the best MRI for claustrophobic people

Open MRI is the the best MRI for claustrophobic patients. The wide open MRI design allows for maximum visibility during the MRI scan procedure.

Additional helpful resources available below. Don’t forget to check out the MRIPETCTSOURCE YouTube Channel for helpful videos, including MRI scan sounds and expert insights into MRI scan procedures. Make sure to subscribe to stay up to date when we release new content.

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