Medical imaging
Because CT and MRI are sensitive to different tissue properties, the appearances of the images obtained with the two techniques differ markedly. In CT, X-rays must be blocked by some form of dense tissue to create an image, so the image quality when looking at soft tissues will be poor. In MRI, while any nucleus with a net nuclear spin can be used, the proton of the hydrogen atom remains the most widely used, especially in the clinical setting, because it is so ubiquitous and returns a large signal. This nucleus, present in water molecules, allows the excellent soft-tissue contrast achievable with MRI.
Synthetic MRI
Creating a synthetic contrast weighted image is very quick and the scanner setting parameters can be changed interactively. This is different from acquiring the images directly on the MRI scanner with a pulse sequence where it might take several minutes to get new images with different settings. Synthetic MRI also enables the possibility to create new image contrast weightings after the scan has been completed and the patient has left the hospital. A prospective multi-reader, multi-case, multi-center clinical trial of overall image quality of synthetic MRI compared to conventional MRI in a general neuroimaging population has shown that synthetic MRI is non-inferior to conventional imaging.
Synthetic MRI is based on parametric maps. These maps are generated by using the MR scanner not to acquire an image, but to measure magnetic properties in the tissue.