MRE cut offs for liver fibrosis assessment
Seeing the images from an MRE exam - called an elastogram - can be a significant moment for patients battling liver disease.
"Seeing my liver and the state of disease for the first time was a very powerful, emotional moment - it left me speechless," recalled Deb Sobel, who was diagnosed with Primary Biliary Cholangitis (PSC) in 1998.
"MRE painted a true picture of the PBC progression. I used to be mad at my liver, but then I felt bad for it and decided to protect and take care of it as much as possible."
While "seeing" liver fibrosis via MRE can often help patients understand their disease better, the actual stiffness value - expressed in kPa - can help determine the actual stage of liver disease. Further, this result is used by clinicians to help reliably track either treatment response or disease progression.
MRE has been extensively studied against liver histology and the figures below indicate those that correlate best with the METAVIR stages of fibrosis. The chart below also shows how the colors on the MRE images that match kPa results.
These figures are standardized across all MRI vendors (GE, Siemens, Philips) and across MR scanner field strengths (1.5T or 3T systems).
Notably for patients, these cut offs are different from the kPa scale used by ultrasound-based elastography techniques, which use a slightly different way to measure tissue stiffness. For instance, a 6.4 kPa MRE exam would correlate with cirrhosis, while a 6.4 kPa result using transient elastography is quite low and would be helpful for ruling out cirrhosis.
They are also the same no matter the underlying liver disease (e.g., NASH, HCV), unlike ultrasound-based exams which have different cut offs depending on etiology.
Cut offs (for determining fibrosis stage)
< 2.5 = normal
2.5 to 2.9 = Normal or Inflammation
2.9 to 3.5 = Stage 1 to 2
3.5 to 4.0 = Stage 2 to 3
4.0 to 5.0 = Stage 3 to 4
> 5.0 = Stage 4