About Me.
Important Notice: Potential Underestimation of Liver Stiffness on Certain Philips MRE Systems
Resoundant has identified a software issue that may affect Magnetic Resonance Elastography (MRE) liver stiffness measurements on certain Philips MRI systems using specific versions of the MRE processing software.
Under certain imaging settings, the reported liver stiffness may be lower than the patient’s actual stiffness value.
What is the Issue?
Multi-model direct inversion (MMDI) is the algorithm used to create standard contrasts – stiffness, wave, and confidence. Stiffness of a pixel is estimated using data in a small, circular kernel. In MMDI versions 3.0.x and 3.1.x, stiffness is calculated using a fixed 11-pixel kernel. Because the kernel size is defined in pixels rather than millimeters, changes in image pixel size (caused by changes in field of view or matrix resolution) alter the effective physical size of the kernel.
This means the liver may appear softer than it actually is.
Which Systems Are Affected?
This issue applies to:
-
Philips MRI systems
-
MMDI software versions 3.0.x and 3.1.x
The issue does NOT affect MRE systems from:
-
GE
-
Siemens
-
Canon
-
United Imaging
The issue has been corrected for all systems, including Philips systems, using MMDI version 3.2 and later.
Possible Clinical Impact
When smaller pixel sizes are used with the affected software versions:
-
Liver stiffness measurements may be systematically underestimated
-
In some cases, this could lead to classification of a patient at a lower fibrosis stage
-
This could potentially influence clinical decisions or treatment planning
Importantly:
-
The elastography images still appear normal and high quality
-
The error cannot be detected by visual inspection of the images
How to Check if Your System Is Affected
The issue can be identified by reviewing:
-
Pixel Size
-
Found in the DICOM tag Pixel Spacing (0028,0030). Pixel size should be ≥1.65mm.
-
-
MRE Software Version
-
Displayed on the MRE images
-
Recommended Actions
If you are using MMDI versions 3.0.x or 3.1.x, we recommend the following:
1. Verify imaging protocol settings
Use the validated protocol settings:
-
Field of View (FOV): 420 mm
-
Matrix: 256 × 256
-
This produces the recommended ≥1.65 mm pixel size
2. Update software if possible
-
Upgrade to MMDI version 3.2 or later
-
The MRE software is typically updated as part of an MRI system software update
3. Confirm pixel size during acquisition
-
Ensure pixel spacing remains ≥1.65 mm
For the latest acquisition standards, please refer to www.resoundant.com/qiba
Summary
When using affected software versions with smaller pixel sizes:
-
Liver stiffness values may be reported lower than the true value
-
The issue is not visible on the elastography images
-
The issue can be corrected by protocol adjustments or a software update
For complete information, access the official Advisory here.
Questions or Support
If you have questions about this advisory or need assistance reviewing your imaging protocols, please contact:
Resoundant Support
