Woke up Sunday with what is now being catagorized as Bell’s Palsey, much better than the stroke they originally thought I was having. Stroke was ruled out by a CAT scan. I’ve now got an MRI scheduled for tomorrow. What will the MRI see that the CAT did not?
I believe MRIs are better at imaging soft tissue in detail. CAT scans are x-ray based and while the multiple-axis viewing can create a good picture, it can miss soft-tissue details.
Ah, thanks she said put he side of her mouth.
MRI also has different modalities to examine perfusion (blood blow) to the brain which can identify stroke. You can google Diffusion Weighted Imaging if you want the technical details.
CT is better at seeing blood, is quicker, more readily available and cheaper so it should be used first line in evaluation of stroke.
That being said, Bell’s palsy should be readily differentiated from stroke in all but the most borderline of cases, especially in someone otherwise young and healthy.
NHS Choices tells me that Bell’s Palsy usually gets better on its own. treatment is most effective if it’s started quickly, within 72 hours of symptoms developing and Prednisolone (a corticosteroid which works by helping to reduce inflammation) is recommended as the most effective treatment.
More details about diagnosis, symptoms, causes, treatment and complications here
Yes, Bell’s usually clears up on its own, but based on the experience of people I have known with it, it does take some time to recover. So don’t expect an instant fix.
Ooog… You have my sympathies. My husband has had a couple bouts with Bell’s Palsy over the years.
Early intervention with prednisone (steroidal anti-inflammatory) and valtrex (antiviral) is key. You’re still in “early” now, so I’m hoping your doctor has started these meds. Unless there’s some compelling reason not to take them, there’s not much harm to taking them in the odd chance that what you have isn’t Bell’s. The greater harm is in delaying treatment. There also seems to be some indication that hitting it early and hard will reduce the chance and/or severity of a return.
Your plan for the week as I see it is:
Get the meds and rest. Stress and lack of sleep can be triggers for recurrences of Bell’s and they certainly will not help in treating it.
X-rays differentiate tissue based upon how much they absorb X-rays. This depends upon the mix of elements that make up the tissue. Heavier elements adsorb more (so calcium in bones is differentiated from soft tissue trivially) ranging down to water (blood, fluids) and then air (within lungs, gut, etc) at the other end. The wavelength of X-Rays can be changed (by changing the voltage on the X-Ray tube) to better target some tissues over others. But in the end, it is all about differentiating tissue by X-Ray absorption.
MRI looks for the manner in which hydrogen nuclei (there are machines that can target other elements but protons is by far the most useful) react. Nuclei have a magnetic moment, and when placed in a magnetic field they form a resonant system. Hit them with a radio pulse and they ring out, and in doing so you get a radio frequency pulse back. The precise shape, phase, and frequency of the pulse - and the manner in which it relates to the shape and frequency of the pulse you hit it with is highly dependant upon the precise surrounding of the proton. If it is in a water molecule it behaves differently to being bound in some other compound, and with creativity it is possible to work out all sorts of ways of differentiating soft tissues. Further, the time it takes to get the pulse back is relatively long, and if the proton is moving about during this time the signal is scrambled out and lost. So moving fluids have essentially no return signal - thus you can very easily differentiate flowing blood.
X-Ray CT and MRI are a useful pair. They overlap in some areas, but are different enough that you would always have both machines.
Intracranial detail is seen far better w/ MRI than w/ CT because the skull absorbs a lot of the radiation in CTs. CTs are worthless for looking at pituitary glands, for example, which are are almost entirely surrounded by bone.
OTOH, unstable patients can have a CT done which will show active bleeding very clearly in a fraction of the time an MRI would take. Time is an important difference for a patient in shock.
Simplistically, if you’re looking for something obvious, go with CT. If you’re looking for something subtle, an MRI is more likely to answer your question.
MRIs, by measuring movement of hydrogen ions (in blood) define problems related to blood flow and fluids, whereas CT are radiation based and detect masses and collections. MRIs used to be called Nuclear Magnetic Resonance imaging or NMR but in the 80s Americans didn’t like mentioning anything nuclear so GE (the company with which I’m familiar) changed the nomenclature. I used to have an NMR mug from GE- much of the research was done in the Schenectady NY R&D facility, and my father, and Pete Rohmer, were project engineers. Dad and Pete are who you thank that you don’t spend hours in that tiny tube, as the last thing Dad patented before he retired was an improved timer for the MRI machine. (He said, after having an MRI at age 83, that if he’d realized they made that much noise he’d have done something about it).
7th cranial nerve paralysis (Bell’s palsy) has a variable course depending on the individual. IMO treat early, and treat hard. The antivirals are debatable but side effects are rare and minimal IME and prednisone is such a potent anti inflammatory you may feel like a pup again. Best to you 
CT provides you with a nice dose of ionizing radiation (which ups your cancer risk down the line) while MRI doesn’t. So avoid CT if you can.
As a Registered CT/MRI Tech, I agree with all of the above. BUT…its VERY hard to see/detect smallish and or early strokes with CT, even with fast-bolus X-ray contrast injections. It can be hard to see stroke effects evn on MRI if done really soon after event, IME. I’ve done MANY such scans at Level 1 Trauma Center, mainly to r/o subdurals, C1/C2 fx’s or such - then patient, if cleared of other more-threatening injury, went straight to MR suite. Often the neuros were standing over my shoulder as images were coming on-screen so they could make the immediate decision of where patient was to go and if absolute restraint of mmovement was warranted (C1 fx’s kill easily if head is ‘manipulatd’ while positioning for scan) after images seen. We talked a lot of what happened, etc, fwiw, to ‘make the call’, so to speak.
ETA - Boomer is totally right about pituatary gland visualization. Usually the only differentiation of pit gland from surrounding tissues, other than calcifications within pit gland itself (not too uncommon, IME).
Often, a person has fallen to ground during their stroke (if stroke significant enpugh to have serious sudden symptoms), and the neuros wanted to make sure there were not any fractures/obvious bleeds of calvarium, cervical spine etc, that needed to be addressed concurrent with imaging process/steps. “First things first” is what I almost always saw if patient was not cognitive to tell if they hit head/neck, etc, or if they’ve fallen down at all. A head and neck thin-slice CT-spiral scan (w/ IV contrast) took me maybe 3-4 minutes after patient hit my scan table from stretcher, and images came out in around two minutes after, and I could have the 3D recons done a couple minutes afterwards. The toughest, most-demanding Trauma director I have ever seen demanded such performance, and that person always demanded that I was one to handle the Trauma/ASAP stuff. I got rather good at 'em.
Mild-stroke symptomatic patients usually went right to MRI if patient was alert enough to tell of symptoms and affectedness. Level of seriousness was a deciding point if CT was involved, due to CT Depts/Radiologists high-level of “is this really an appropriate exam for this person?” to limit rad exposure at ALL times. ALARA is term for the standard of ‘as low as reasonably possible’, fwiw.
I must compliment you on your screen name. 
Get better. I hate hearing about people here in sickness, although I’m sure not as much as those people themselves think about being sick.
Like you, I like taking the opportunity, if I’m able, to use the opportunities to talk in SD and ask about new things I find interesting about tech, medicine, whatever.
If that helps.
Get better.
On the other hand, if, like my spouse, you have a leg full of hardware from a prior injury you can’t use the MRI, so opt for CT.
I had some X-rays of my knee a few weeks back, and an MRI on New Year’s Eve day. The X-rays show the condition of the bone (some arthritis, normal at my age). On the MRI, you can clearly see the tear in the meniscus. Have to get it scoped.
It was kinda a nickname given to me by the Level 1 Trauma Director one day jokingly, and more than few residents/attendings picked it up and carried it. “Hey, get that Ionizer guy on notice we are on our way”, etc.
I gotta say I have not been ‘in the field’ for around 6-7 years, so I should’ve said former Registerred Tech. Did all imaging modalities (US/CT/MRI/NucMed/Diag X-ray for over 20 years, including total oversight of NucMed labs, etc. Been there/done that in a wide set of imaging 'skills/experiences. Also have done lots of lab stuff/microscopy-stuff as I often worked a part-time job in smaller clinic/hosps that used the Lab Tech as X-ray as a single job concurrently as many of my full-time positions were 40-hr weekends at major Regional Trauma Centers. Had entire workweek to make money to restore the 71 Charger I was restoring 
I worked loooong hours and saw/dealt with a huge range of problems, etc.
Too many times, I had to point out to the newbie Radioligist residents serious things they missed due to their high-load of images to be read from many sources. They only had a few moments to look at an exam and move on, unfortunately, and the attending would review all the exms for accuracy hours/days later. The Trauma folk were quick to come to me /if/when they saw something ‘odd’. I am proud of how good I got at holding the “Excellent care no mater what” mission I carried out. I do miss the environment a lot at times.
I did in fact have a stroke, went to the hospital and had a CT scan - which found nothing. I walked out and went home and went to my doctor the next day, who immediately sent me for an MRI which confirmed the stroke. I believe his head hit the ceiling when he heard they let me go home, but it was midnight by then and spending the night wide awake in discomfort at the hospital would have been a far worse choice than sleeping in my own bed.
So, yes, an MRI can see much more than a CT scan.
So what’s up with this new GE CT scanner? Besides the new gruesomeness.
ETA to above: it’s probably on this page (the “new” one?) at the GE Healthcare Radiography sales page.