One of the greatest benefits of MRI scans is their safety. Unlike PET, X-ray, CT and most other scans, MRIs use the properties of body tissues in magnetic fields to produce an image. The MRI machine produces a powerful magnetic field which interacts with body tissues to produce radio waves, which are in turn interpreted by a computer to determine the ...
Some new pacemakers are MRI compatible (). Of those, some have an exclusion zone where the body may not be scanned. I wouldn't be surprised if, in a few years, all new pacemakers and ICDs will be MRI compatible. Older pacemakers still won't be, however. The following quote from , lists problems MRI fields may cause with pacemakers:
Heating at the lead ...
First of all, your "main question" contains a lot of small other questions, which I think are difficult to answer as we are not your sister's neurologist (we haven't seen the MRI, we haven't examined her,etc...) But I will try to address some of your concerns:
What are arachnoid cysts?
Arachnoid cysts (AC) are a collection of cerebrospinal fluid (CSF) ...
There are no units for MRI intensity.
A Comparison of Five Methods for Signal Intensity Standardization in MRI (CEUR-WS.org):
A major problem in magnetic resonance imaging (MRI) is the lack of a
pulse sequence dependent standardized intensity scale like the
Hounsfield units in computed tomography.
MRI sequences (Radiopedia):
When describing most ...
If you are going to have a Magnetic Resonance Neurography (MRN), also known as MR Imaging of Peripheral Nerves (PNI) (UCSF), a doctor will likely tell you in advance, at least because the investigation may not be covered by your insurance (Neurography Institute).
The MRI and MRN procedures are similar, only that MRN requires more powerful scanners that are ...
Have a look at this publication of Sein et al., 'Reliability of MRI assessment of supraspinatus tendinopathy.' (PMID 17289860)
Sein ML et al. Reliability of MRI assessment of supraspinatus tendinopathy. Br J Sports Med. 2007 Aug;41(8):e9. Epub 2007 Feb 8. https://dx.doi.org/10.1136%2Fbjsm.2006.034421
There is no consistency within the industry on the terminology. For example, GE calls them MR systems, Philips calls them both MR system and MRI system, Toshiba calls them both MRI system and MR system, and Siemens calls them MRI scanners.
The amounts of radiation in today's machines is low enough that there is no negative impact to be expected.
X-Rays: A chest X-ray gives you about 10 mrem
MRIs measure the reaction time of molecules (in the body) to changes of outside magnetic fields. No radiation or radioactivity is involved at all.
A chest CT scan clocks in at ...
Neurodegenerative diseases are diagnosed on the basis of clinical symptoms (memory impairment for Alzheimer Disease/ bradykinesia, tremor and rigor for Parkinson Disease) +/- neuropsychological tests.
The current role of neuroimaging in the diagnosis of neurogenerative diseases such as Parkinson Disease or Alzheimer Disease is mainly supportive, it can be ...
[TLDR: The gradient coils.]
That is a great question. There are three parts to an MRI machine: main magnetic field (1.5 Tesla, 3 Tesla etc), gradient coil system and radio-frequency coil.
The main magnetic field is static, meaning is doesn't change. Once the technician has "ramped up" the scanner, it will not change. It doesn't get shut down at all. ...
Diffusion of water.
Osmosis is movement of water across a membrane due to solute changes. In the case of diffusion tensor MRI, the whole point is that there is more diffusion along the same axis as white matter axons are traveling (either within or outside, but not across, those membranes), compared to a perpendicular axis. There isn't any net flow, it's ...
Nothing is more helpful than a comprehensive physical examination by an expert and the clinical course of the disease, for ruling out the ACL rupture. Evidence supports that
The accuracy of the clinical examination and MRI evaluation was equal
for diagnosing meniscal tears and ACL ruptures
the Lachman test has great efficacy ...
In the US, medical device sales are regulated by the FDA much like drugs.
Like drugs, some items are permitted for over-the-counter (OTC) sale to the public (for example, bandages and thermometers). Others can only be sold to medical professionals. Diagnostic devices that require a professional to interpret are very unlikely to be available OTC.
Magnetic Resonance Imaging is an umbrella term for any medical imaging technique that makes use of the phenomenon of nuclear magnetic resonance. There are many variants depending on how the scanner is configured and analysed, but all are considered MRI.
The basis for the different types of MRI scanning
Much of the following is adapted from MRI Basics.
CT scans use ionizing radiation. It's safe to get a CT scan for a medical purpose: the marginal risks of the scan are outweighed by the diagnostic benefits. However, repeated CT scans can potentially raise the risk of cancer. Monitoring ones progress in a fitness program can easily be done with other methods that do not cause cancer. I would consider it ...
Regarding United States, quote from "Copy Fees and Patients’ Rights to Obtain a Copy of Their Medical Records: From Law to Reality" (2005):
Patients have a legal right under HIPAA to a copy of their medical records. Personal life-long medical records rely on patients’ ability to exercise this right inexpensively and in a timely manner. We surveyed 73 ...
You most definitely do not want to be in an MRI machine during an earthquake. The superconducting magnets in an MRI scanner are cooled by liquid helium. If the cooling system is damaged and there is a leak, this could be very bad for you.
I have not seen what is in the yellow folder, but earthquakes present a particularly dangerous situation for MRI ...
Do nothing, stay inside the MRI machine.
I never performed MRI scan in the past but I had experience of several quite big earthquakes within the last 10 years. So I provide my thought on this for your reference.
I have to say that you probably already in the safest place during an earth quake in a building for two reasons:
1) rooms for big scanners are ...
Toxicity of gadolinium-based contrast agents can generally be classified as acute (short term) and chronic (longer term) and include¹:
Acute allergic-like reactions
Acute physiologic reaction
Chronic kidney injury (called nephrogenic systemic fibrosis)
Additionally, there is evidence that a small amount of contrast agent is retained in various tissues of ...
As far as I know MRI scans are mainly used to assess the location and extent of crohn's disease manifestations and crohn's associated complications (strictures, fistulas, wall thinkening). MRI is usefull to determine the phenotype of someones crohn's (e.g. localized terminal ileitis, perianal disease).
An MRI of course is not suitable as sole instrument to ...
Worldwide, there are approximately 36,000 MR machines. At present,
about 2,500 MR imaging units are sold worldwide every year
This CDC link shows the amount per country.
If you take this to be a good reference then this could be answer.
A higher Tesla magnet generally equates to a higher quality image. Closed (the traditional round-shaped magnet bore) or oval MRIs generally produce a higher quality image than open MRIs, so avoid an open MRI unless you're severely claustrophobic. A newer MRI machine would be preferable to one installed, say, 15 or 20 years ago, all other factors being equal. ...
I think it is mainly due to the evidence indicating poor accuracy (sensitivity and specificity) of conventional MRI. It means that false-positive or false-negative findings may be detected in MRI of elbow (1):
MR arthrography is more accurate than conventional MRI of the elbow at 3 T.
[In 54 out of 79 patients, the diagnoses made on MRI and MR ...
Via the UCLA Brain Mapping Center, in the event of (emphasis and formatting added):
Non-Fire Facility Emergencies
Unscheduled Power Shutdowns
Magnet Quench (catastrophic boil-off of helium)
Foreign Metal Objects in the Magnet
Perform a routine electrical shutdown, or if circumstances ...
It's indeed the same "big magnet" machine as for normal MRI, but in WB-MRI (ideally) multiple coils are placed on the patient's body, e.g.:
The process does indeed last 30-60 minutes (as Carey noted) as multiple scans passes are made. (More technical details in the article linked.)
There's a bit of history and/or variation in WB-MRI techniques
Brain Imaging Data Structure (BIDS) is a simple and intuitive way to organize and describe neuroimaging and behavioral data. You can find it on bids.neuroimaging.io.
BIDS is heavily inspired by the format used internally by the OpenfMRI repository (now known as OpenNeuro.org). While working on BIDS we consulted many neuroscientists to make sure it covers ...
So far I have found Dilated Virchow-Robin (VR) Spaces (a.k.a dilated perivascular spaces) which are not necessarily malign and have pretty much the exact aspect on T1 and T2. Ref: https://pubs.rsna.org/doi/full/10.1148/rg.274065722
An xray is one image. Sometimes they might take a few more. CT and MRI scans are many more images. What's more, they aren't all taken from the same place, so you have to be moved into position a few times or the equipment needs to move around you or both.
If contrast is needed, the whole thing needs to be done twice - once without and once with contrast. (Or ...
I called the radiology office and the technician I talked with said that the numbers should denote the series and frame in which the (in this case) lesions can be found. He said that these numbers would normally be accompanied with markup such as "series 14, image 8" or the like and that this abbreviated form is non-standard.
So for "14/8" I needed to go to ...