MRI techniques at different radiology facilities

Question

MRI done at different center but brought CD for comparison. Radiologist reports that "examination techniques are so significantly different comparison is not possible." If neurologist can read both scans, why can't radiologist make comparison?

COBOB · Accepted Answer

They can read them as individual studies, but they are not valid comparisons.  I ran into this.  My first MRI was done with 5mm slices and my second was done with 3mm slices.  There were more lesions seen on the second study that may have been on the first but missed.  It can mess up the "dissemination is time."   Radiologists are trained to only compare two studies that are similar in excitation, relaxation and Tau.  So they can not compare a T1 Proton Spin Echo to a T1 Small Tip Angle Gradient Echo (STAGE).  

Keep in mind that MRI images are not like XRAY.  They are "computer derived images": more like a radar images and ultrasound.  Things are not actually where they appear to be on the image.  MRI uses a magnetic field to excite dipole molecules and then when the field relaxes, it listens for the signals the protons of the molecules produce (PSE or Proton Spin Echo.)  In standard MRI, most sequences listen for water protons and gadolinium protons on post contract sequences. For proton MRS uses this information to determine the concentration of metabolites (such as lipids, lactate, N-acetylaspartate (NAA), glutamate/glutamine (Glx), creatine (Cr), choline (Cho), and myo-inositol (mI).  

The key idea here is that different T1 and T2 Sequence Techniques make the protons spin differently and you loos the ability to compare between different sequence types.  Is isn't just the weighting where T1 (more water in whiter) and T2 (less water is whiter.) It is also the letters after the Weighting and the ET:, RT: and TAU values in the lower left hand corner of images. 

Very technical stuff, and Neuro are looking for lesions.  Neuro-radiologists are looking at the whole study.  Different specialties, objectives and clinical rules.

Bob

COBOB · Answer

By the way, the 2009 recommended MS MRI Protocol can be found at: 
http://www.mscare.org/cmsc/images/pdf/mriprotocol2009.pdf

Bob

johnniebear · Answer

I'm  not sure, but they have not done as many slices that the Radiologist might like,  however he should still at least consider the report. Plus was the MRI'S  done W/O contrast?

If you have a good MS. Specialist he/she may not even want the reports & will look at the MRI themselves.


take care

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