Hi All, Just wondering if anyone here has been diagnosed with MS with a clear mri and on what other basis were you diagnosed? From the information I’ve read, around 5% of people have been diagnosed with a clear mri, which if around 100000 people in the UK have MS makes 5000 people which is a significant amount. I’ve recently got my mri results back which were quite vague and brief but say there is no indication of inflammation. They have put me on the waiting list for a lumbar puncture and further blood tests - GP did a lot of blood tests at same time as referral to Neurologist and it came back as slightly low in Vitamin D but others fine. I know having a clear mri should be good news, but my symptoms having been going on since beginning of September 16 (and neurologist believes I had a previous episode in March) and caused me to take time off work on a few occasions at previous job. I started a new job and managed to attend for 6 weeks, however I’ve had to take the last week off due to a flare up, which obviously is not ideal as I’m still on the probation period. I really need to know whats going on so I can get medication if required, and also if it is MS hopefully get some adjustments/protection at work. Im struggling with everyday activities and it’s getting so frustrating not having an answer. I’m gobsmacked that the MRI hasn’t found anything, as at the time I started feeling unwell I also started getting bladder problems. I’ve never had a bladder infection in my life and tests came back negative for infection, was sent for an ultrasound which showed I’m having problems fully draining my bladder, and I’ve been reffered to urology. I find it impossible to believe this isn’t linked especially as GP thinks it is linked. Also when I first started getting symptoms, I brushed them off, but when other people such as a few colleagues pointed out problems with my walking and my left arm, I decided to visit the GP. Since then symtptoms have increased, and I also can’t move toes on left foot anymore. I just don’t understand how the MRI is clear when there is obviously something wrong. If anyone could give me advice about MRI results and about coping at work before a diagnosis I would be very grateful. I’m scared I’m going to lose my job before I get any answers from Neurology. Thanks for your time.
Hiya,
Rzzo is ‘she who must be obeyed’ is the Guru on MRIs. See A brief beginner's guide to the brain and MRI - New diagnosis and before diagnosis - MS Society UK | Forum
She also sent me a PM about them that makes very interesting reading; in your case could explain why lesion/s have not shown.
Quote: The last T2 FLAIR scan I did of my brain used 70 slices (on a 3T scanner). The one I had done today - 13 (on a 1.5T scanner). THIRTEEN. THIRTEEN!!!
Thankfully I wrote it out the voxels/T2 reply in Word before posting - to avoid the dreaded time-out! So here it is…
A MRI image typically consists of voxels (3D pixels). Slice thickness is one dimension (on the z-axis if you think of maths). The images you see on the CD show you the other two dimensions (on the x- and y-axes). You can set the voxel size to anything you want, in any dimension; all that happens is that it changes the time the scan takes to run (and therefore, of course, how much it costs). The smallest voxel size used in everyday MRI is typically 1mm x 1mm x 1mm. The “off the shelf” scan that I used to use for this size of voxel had 176 slices. The voxels (and slices) cover the whole brain irrespective of what the voxel size is – nothing is missed out (but see later).
If a standard T2 sequence is used for the scan, white matter gives off a poor signal and shows up as dark whereas lesions (which are full of fluid) give a strong signal and show up as bright.
However, the brightness of a voxel depends on the average of the response from the matter represented by that voxel. So a voxel that is 1mm x 1mm x 4mm will show the signal generated by all matter located in that 4mm3 cube. That is, if the voxel only contains white matter it will be dark in the image, if it only contains fluid it will be bright, but if it contains a mix of white matter and fluid it will look somewhere between dark and bright, depending on the proportion of the different matter types.
So if you have a large voxel (say 4x4x4) and a small lesion (say 1x1x1), the overall signal in the voxel will only be slightly higher than one without a lesion (and therefore look only slightly brighter, and therefore may be overlooked). [NB Small lesions would also not always be completely contained within one large voxel – it is more likely that it would be partially in at least two. So this makes it worse.]
But if you have small voxels and a large lesion, then you will get several very bright voxels (where the matter is all fluid), some intermediate voxels (where there is a mix of fluid and white matter), and some vaguely brighter voxels (that contain predominantly white matter).
In other words, small voxels are much better for detecting lesions.
So, can lesions be missed if you use thick slices? Basically, yes. It is entirely feasible. However, they would have to be much smaller than the slice thickness because if they are closer in size, they would contribute sufficient signal to make the voxels significantly brighter than the surrounding voxels and would (should!) be picked up by a decent radiologist. Saying that, it is possible that it might be missed if a small lesion, by chance, spans lots of voxels (e.g. if it is centred on where four voxels meet on that slice) and the signal is lost by the averaging with the white matter signal in those voxels.
However, there are new “pulse sequences” (the settings that programme the scanner) that are particularly sensitive to fluid. If you use one of these rather than a standard T2 sequence, you will be able to use bigger voxels and still be able to detect lesions relatively easily. And the power of the scanner makes a big difference too. A 3T scanner is much better than a 1.5T scanner.
So, if a hospital has a 1.5T scanner and a neuro is ordering a standard T2 scan, then he should be asking for a high resolution (i.e. small voxel size).
If the hospital has a 3T scanner and the neuro is ordering a FLAIR or another new type of pulse sequence that’s good for fluid, then he can get away with a lower resolution.
[NB A related point: it is possible to set gaps between slices. For example, the MRI may capture signal from 0-4mm, 8-12mm, 16-20mm etc rather than 0-4mm, 4-8mm, 8-12mm etc. This would DEFINITELY miss lesions!]
So the trick to not missing lesions is not so much about the number of slices, but about the voxel size, whether or not the slices cover the whole brain without any gaps, the power of the scanner and the choice of pulse sequence.
No; it should not be possible to diagnose without at least one lesion showing on MRI; or the mcdonald criteria says there should be one.
George
Rizzo has retired from forums. She feels a lot more relaxed.just her real world friends to not argue with. Forums are really addictive. She knows more than anyone I’ve met. Respeck Rizzo. You helped so many people here.
I believe that an unfortunate Lumber Puncture result can satisfy the McDonald criteria in the absence of any suggested, MRI derived evidence.
There have been cases where clear MRIs have been presented in those with myriad symptoms. The opposite is true as well, with multiple lesions being present in a patient with few or mild symptoms.
I am infinitely grateful for my being in the latter group at the moment. And long may that remain the case!
I regard my disease upon the basis of how i feel and what i can still do. Consequently i tell my neurologist that i have absolutely no interest in hearing what pretty pictures the noisy tube produces.
Hi snugbug,
One other matter that may affect a lesion not showing is where it is. The Spinal Column is just a thin; flexible; bony tube containing billions of specialised neural cells; millions of axons plenty of places for a lesion to hide.
The brain (especially mine) is more or less a wide open space.
Here is a map of the spine and just like a break anything below that lesion/break may/will be affected. http://www.electrotwist.com/wp-content/uploads/nerve_chart.jpg If there are lesion/s in the brain they are controlling cognitive functions.
George