Magnetic Resonance Imaging (MRI) is well recognized as a reliable technology for tissue imaging, and has become an essential tool for noninvasive cancer diagnostics.
However, conventional MRI is expensive, requires a special room with shielding, and limits its accessibility to patients. To date, MRI is exclusively used by radiologists, in dedicated rooms, outside the Operating Room, which creates a significant time gap between sample preparation and analysis.
Diffusion-weighted Magnetic Resonance Imaging (DW-MRI)
DW-MRI is a well established form of MR imaging, capable to visualize and/or quantify the Brownian motion of water molecules in specific tissues. Many histological properties influence water diffusion, but in particular mobility of extracellular fluids is a valuable source of differentiation between normal and abnormal tissue in a given imaging volume. In general densely cellular tissues or those with cellular swelling exhibit more restricted diffusion than other tissues, allowing detection of various cancer types, ischemic swelling and other abnormalities without contrast agents.
The quantitative magnetic resonance value measured in diffusion-weighted scans is called T2*. In essence T2* reflects how fast the signal echoed from tissue excited with an certain sequence of radio frequency (RF) pulses decays due to water molecules changing location within the magnetic field of the scanner. In order to make interpretation easier T2* can be transformed into the apparent diffusion coefficient (ADC), if the other magnetic properties of the tissues under investigation are known. ADC is in principle directly comparable to diffusion measured with other methods.
Usually DW-MRI is performed on MR scanner with strong, very homogenous magnetic fields as well as strong gradients. Such high-end systems are expensive and not suitable for intra-operative use due to size and supporting infrastructure requirements. In an unprecedented engineering breakthrough ClearCut Medical has succeeded in miniaturizing the MR technology such that diffusion-weighted imaging for tissue characterization is now available in a mobile system, perfectly attuned to the Operating Room environment. The ClearSight MR scanner is performing T2* measurements on the surface of excised tissue, in order to allow the surgeon to identify regions containing tissue with abnormal diffusion properties as compared to the neighboring tissue on the surface of a freshly excised specimen.