Are there bigger MRI machines?

MRI (magnetic resonance imaging) machines come in a variety of sizes to accommodate different needs. While a traditional MRI machine has a bore size (open circular area) of around 60 cm, there are larger options available for patients who need more space.

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Why are there size variations in MRI machines?

MRI machines are designed with different bore sizes to accommodate the needs of different patients. Some key factors that influence MRI bore size include:

Patient size – Larger patients may not fit comfortably in a standard 60 cm bore and may require a larger 70 cm, 80 cm or more bore for imaging.

Claustrophobia – Up to 5% of patients experience claustrophobia during MRI exams. A larger bore can help patients feel less confined.
Obesity – With rising obesity rates, there is a need for larger MRI bores to accommodate this population.
Additional equipment – Certain exams like breast MRI may require additional equipment inside the bore, necessitating a larger space.

Pediatric imaging – Children are often imaged with additional equipment like anesthesia masks. A 70 cm bore allows more room for kids and medical equipment.

By offering different bore sizes beyond the standard 60 cm, MRI facilities can meet the needs of more patients and ensure their comfort and safety throughout the scanning process.

What are the typical MRI bore sizes?

Here are some of the most common MRI bore sizes:

60 cm bore – This is the standard size found in most MRI scanners and can accommodate most average-sized patients.
70 cm bore – This provides an extra 10 cm (4 inches) of space and is well-suited for larger patients, those with claustrophobia, and pediatric imaging.
80-85 cm bore – These extra-large bores allow enough room for obese patients who need special accommodation.

Wide-bore – Some MRI machines are specially designed with a shorter but wider bore, such as 70 cm wide by 60 cm high. These can be beneficial for patients who feel confined by narrow bore openings.

Open MRI systems are also available with very large bores exceeding 100 cm. However, image quality in open MRIs is lower, so they are not used as often as closed bore systems.

What are the largest MRI bore sizes available?

Here are some extra-large MRI bore sizes at the higher end of the range:

90 cm – There are a limited number of MRI scanners made with 90 cm bores to accommodate bariatric patients.
100 cm – Philips and Siemens both offer MRI systems with 100 cm bores, providing ample space for obese patients up to 550 lbs.
110 cm – Hitachi’s Altaire MRI is currently the MRI scanner with the largest bore, measuring 110 cm for maximum patient accommodation.

Additionally, some other MRI bore specifications at the larger end include:

GE Optima MR430s – 70 cm wide bore
Philips Panorama High Field Open – 103 cm x 193 cm elliptical bore

Hitachi Oasis – 71 cm wide bore

These ultra wide-bore and high-field open MRIs give patients an exceptional amount of space. However, they are far less common than standard 60-70 cm bores due to much higher costs and some imaging limitations.

What are the benefits of a larger MRI bore?

There are several advantages to having a larger MRI bore size:

Patient comfort – More space allows larger patients to fit and helps minimize anxiety and claustrophobic reactions.
Accommodating equipment – Additional coils, anesthesia masks and other medical gear can be used more easily.
Versatility – A larger bore allows the MRI to be used on a wider range of patients.

Higher tolerance – Patients are more likely to complete longer exam times without feeling confined.
Less restraining – There is less need to restrain claustrophobic patients.
Accessibility – Obese and disabled patients can be more readily accommodated.

Maximizing patient comfort, safety and accessibility are the biggest advantages of larger MRI bores.

What are the downsides of a larger bore?

There are some disadvantages associated with extra-large MRI bore sizes:

Higher cost – Larger MRI systems have a higher base price, with costs rising significantly for bores exceeding 70 cm.

Higher siting costs – Larger, heavier MRI units require more site preparation and potential construction costs.
Increased complexity – Additional coils are needed to maintain image quality in a larger bore.
Decreased image quality – There can be some reduction in image quality, tissue contrast and spatial resolution.

Higher energy consumption – Larger magnets require more electricity to power.
Lower availability – Not all manufacturers make large-bore systems, so there are fewer options to choose from.

These downsides mean large-bore MRIs are less readily available and more expensive for healthcare institutions to acquire and operate.

How much does bore size affect image quality?

When evaluating large-bore MRI systems, an important consideration is the impact on image quality. There are a few key factors:

Field strength – Image quality is more strongly influenced by field strength (1.5T vs 3T) than bore size alone.
Signal-to-noise ratio (SNR) – Larger bores have slightly lower SNR but modern scanners can compensate for this.

Homogeneity – Special gradients and dedicated coils are used to preserve homogeneity in larger bores.
Overall impact – Enlarging the bore from 60cm to 70cm has a minor effect on quality. Going above 80-90cm causes more significant decline in quality.

Experienced MRI providers indicate bore sizes up to around 70-80 cm can maintain excellent image quality as long as appropriate coils and sequences are used. Ultra wide-bore systems may have lower resolution but imaging is still fully diagnostic.

What is the process for getting an MRI in an enlarged bore?

Getting an MRI in a larger bore machine generally involves the following process:

The referring physician submits an order for an MRI, noting that an enlarged bore is needed.
The imaging facility reviews the request and schedules the patient for a large-bore system.

If needed, the patient has a consultation at the MRI center to discuss requirements like sedation.
On the exam day, the patient is set up and brought into the MRI room with the wider bore.
Technologists assist the patient in getting comfortably positioned within the machine.

The technologist exits the room and begins image acquisition using specialized protocols.
After the scan, the patient leaves the MRI room and the technologist processes the images.
The radiologist interprets the images and sends a report back to the referring physician.

The enlarged bore allows the exam to be completed safely and efficiently for the patient’s specific needs.

What types of patients need larger bores?

Here are the most common patients that require larger MRI bores due to their body habitus or medical situation:

Obese patients – Individuals with a BMI over 35 often need at least a 70 cm bore and occasionally up to 90 cm if severely obese.

Claustrophobics – Up to 5% of patients have claustrophobic symptoms, with enlarged bores helpful for managing anxiety.
Tall patients – A 70 cm bore may be needed for men over 6’5″ and women over 6’2″ to fit comfortably.
Football, rugby players – Their large frames may require 70-80 cm bores.

Pregnant women – Enlarged uterus and maternal habitus necessitate more room.
Pediatric patients – Children receive imaging with medical equipment like respiration monitors.
Trauma patients – Additional room needed for tubes, monitors and medical personnel.

MRIs with bore sizes up to 70 cm can meet most patient needs. Open MRIs with even larger bores exceeding 80 cm provide an option for the most challenging cases like morbid obesity.

How much does a large-bore MRI system cost?

MRI scanners with larger bore sizes have a higher base system cost. Some examples of large-bore MRI prices include:

Bore Size	Cost
60 cm	$1.2 million average cost
70 cm	$1.4 million average cost
80-85 cm	$1.6 – $1.8 million range
90+ cm	Over $2 million for ultra wide-bore systems

Besides the scanner itself, healthcare facilities need to budget for increased siting costs and higher energy use for running large magnets. Larger, heavier units often require specialized foundations and more extensive installation work.

Conclusion

MRI scanners are now available in a range of bore sizes to meet diverse patient needs. Widening the bore from the standard 60 cm up to 70 cm provides significantly enhanced accommodation at moderate additional cost. Bores of 70-80 cm are sufficient for the vast majority of patient cases. Open MRI systems with massive bores exceeding 100 cm enable imaging almost any patient, but have major limitations in availability and imaging performance.

Healthcare providers aiming to maximize access to MRI should consider investing in 70-80 cm wide-bore systems as a flexible solution suitable for most patients. For facilities treating populations with very high obesity rates, large 90+ cm bores may be justified despite much higher costs. By offering enlarged MRI bores alongside traditional 60 cm systems, hospitals and clinics can make MRI exams possible for more patients while maintaining exceptional image quality.