ayo Clinic College of MedicineRochester MN 55902 Thomas Jefferson University Philadelphia PA 19107 Liver Fibrosis Introduction Obtaining liver stiffnessmeasurements LSM on an MR elastogram is ID: 942270
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Measuring Liver Stiffness on Magnetic Resonance Elastography (MRE)Christopher L. Welle, MD; Flavius F. Guglielmo, MD; Sudhakar K. Venkatesh, MD ayo Clinic College of Medicine,Rochester, MN 55902, Thomas Jefferson University. Philadelphia, PA 19107 Liver Fibrosis Introduction Obtaining liver stiffnessmeasurements (LSM) on an MR elastogram is a multistep process that interpreting radiologistshould be comfortable performing. By understanding the MR sequences, General Instructions When placing an ROI, either geographic or oval ROIs can be usedeographic ROIs provide the advantage of a greater volume of sampling and more accurate representation of liver stiffness (LS). Only areas withgood waveforms should be sampled. ROIs should not be placed within onehalf wavelength(or approximately 1cm) of the liver edge. Additionally, the gallbladder fossa, large vessels, and Elastogram without 95% confidence map. Measuring LS on an MRE without a confidence map requires attention to make sure good waves are being sampled. raw an ROI on the magnitude image, avoiding theliver edge and large vascular structures as described above. opy this ROI to the wave image, with modificationif needed, to exclude areas with artifact or poor waveforms. opy theROI (with modifications if any) to the color or grey scale elastogram to obtain the LSM. Elastogram with 95% confidence map To measureLS on an MRE with a 95% confidence mapOn the confidence map, drawan ROI on the nonhashed out region representing the region of valid LSM. Copy this ROI to the magnitude image, where adjustments can be made to exclude the liver edge, large vessels, etc. ransferthemodifiedROIto the color wave image to ensure the confidence map includeonly good quality waves. 4) C opy the ROI to the grey scale elastogram to obtain the LSM. Obtaining the The above process is repeated for all four slices of the MREas shown below. The overall mean liver stiffness is the weighted arithmetic meanwhich reflects the relative contribution of the area of the liver measured in each sliceReport the weighted arithmetic mean alongwith the range of values (all rounded to the nearest tenth decimal). A generic formula for calculating the weighted arithmetic mean of the mean liver stiffness values (“m”) obtained from the ROIs drawn in 4 slices, each having a region of interest size of “w” pixels would be: Weighted arithmetic mean = (m1w1m2w2m3w3 References: Venkatesh SK,Yin M,Ehman RL. Magnetic resonance elastography of liver: technique, analysis, and clinical applications. Cole PE, Ehman RL, et a. QIBA MRE Biomarker Committee. Magnetic Resonance Elastography of the Liver, Quantitative Imaging Bi Stage: Consensus. QIBA, May 2, 2018. Interpretation of MRE Results . Mean LSM : 2.5 kPa = Normal3.0 kPa = Normal or inflammationcreased liver stiffness, inthe appropriate clinical setting, is compatible with liver fibrosis as below:.5 kPa = Stage 12 fibrosis3.5 to 4.0 kPa = Stage 23 fibrosis4.0 to 5.0 kPa = Stage 3fibrosis&#x-2.4;&#x 000;5.0 kPa= Stage 4 fibrosis or cirrhosis