Non-invasive assessment of cartilage loss
Imatx JX (Joint Assessment) provides fully automated, non-invasive, quantitative imaging methods for determining cartilage loss and assessing arthritis.
JX provides the end-user with the ability to:
- determine the severity of the disease
- monitor progression of disease
- assess therapeutic effectiveness
We are continuously developing our MRI based imaging markers products. Currently we have a suite of software tools for extracting and measuring cartilage tissue regions from MRI scans. We have performed a series of studies to demonstrate feasibility of our technology for targeted volume measurements using MRI with standard clinical protocols and spatial resolutions.
Imatx' software brings together recent developments in separate areas such as pattern recognition, image processing and magnetic resonance imaging (MRI) to provide new diagnostic tests to examine articular cartilage morphology. These tests include enhanced imaging techniques to reconstruct the thickness of the articular cartilage in three dimensions and methods for targeted measurements of the knee joint.
Summary of capabilities
- General joint cartilage measurements from MRI scans
- Qualitative, semi-quantitative, and quantitative parameters
- Targeted cartilage defect characterization
- Accuracy: +/- 13 cubic mm
- precision: an average of 6%
- reproducibility: average R-square of 0.95
- maximum volumes of ~500 cubic millimeters (0.5cc)
- minimum volumes of ~30 cubic mm (0.03cc)
- Non-Invasive, in vivo assessment of changes
- Disease progression
- Treatment effects
- Feasibility studies with in-vivo and in-vitro samples
Advances in Quantization of Cartilage Loss and Limitations of Current Technology
Changes to the articular cartilage in osteoarthritis can be described in biological, mechanical and morphological terms. From a morphological viewpoint there has been substantial progress in our ability to study cartilage using magnetic resonance imaging (MRI). The application of advanced quantitative imaging methods greatly enhances our ability to evaluate patients with arthritis. The ability to consistently and automatically locate cartilage defects or areas of cartilage thinning and quantize the corresponding cartilage loss is extremely valuable in evaluating factors influencing the progression of osteoarthritis of the knee joint. Therefore, quantitative image processing and analysis techniques play an increasingly important role in evaluating cartilage loss and monitoring response to medical or surgical therapy.
The key problem with most current techniques for estimating cartilage loss is that global cartilage volume is measured, i.e. the entire cartilage covering the femoral condyles or the patella or the tibial plateau, rather than measuring only the cartilage defect. If the average reproducibility error of this technique is 5-10% based on these studies and the total cartilage volume over the femoral condyles is approximately 20cc, the volume of a new cartilage defect must be at least 1.0-2.0cc in order to be detectable. Cartilage defects are, however, often limited to a focal area with a volume less than 0.5cc. For this reason, other, more sensitive, techniques like the ones offered by Imaging Therapeutics, Inc., are needed in order to detect subtle loss in articular cartilage volume between baseline and follow-up MR imaging studies.
Advantages of MRI for OA Biomarker measurements
- No radiation
- Direct visualization of cartilage (as opposed to x-ray)
- Well established and validated imaging techniques
- Three-dimensional images allow for a variety of parameters to be measured
The Need for Automated Image Analysis for Osteoarthritis
Changes to the articular cartilage in osteoarthritis can be described in biological, mechanical and morphological terms. From a morphological viewpoint there has been substantial progress in our ability to study cartilage using magnetic resonance imaging (MRI). However, current MRI techniques rely on subjective, visual rather than fully automated quantitative analysis. Furthermore, current tests are limited in determining the prognosis of arthritis patients and in monitoring progression of cartilage loss or response to therapeutic intervention. The application of advanced quantitative imaging methods could greatly enhance our ability to evaluate patients with arthritis. Clearly, the ability to consistently and automatically locate cartilage defects or areas of cartilage thinning and quantize the corresponding cartilage loss would be extremely valuable in evaluating factors influencing the progression of osteoarthritis of the knee joint.
The approach for local cartilage defect estimation is based on the reconstruction of the envelope surface representing the boundary of the missing cartilage (see Figure). The missing cartilage surface envelope is estimated from the underlying subchondral bone surface and the cartilage surface surrounding the defect.
The contrast for the boundary between subchondral bone and cartilage is usually high and results in smooth surface segmentations. Together with surrounding cartilage surface information the subchondral bone surface is used to reconstruct the missing cartilage surface envelope information.
ImaTx JX is currently available in the US for investigational use only. Research organizations interested in using ImaTx JX are encouraged to contact ImaTx for more information.