There a few different methods of obtaining medical diagnostic images. Each method or type is known as a modality. In particular, MRI scans and CT scans bring a great deal to the field of medicine. Doctors use both modalities to help them provide accurate information about their patient in order to accurately diagnose what is wrong with them. There are differences between the two, with each providing its own advantages and disadvantages. This article acts as a guide to explaining the main differences between these two important and effective types of scan. Read on to find out more. The acronym CT, used with in the term CT scan, is an abbreviation of computed tomography. This modality uses x-rays which is a type of ionizing radiation to produce images of the body's interior. This makes it particularly good at investigating tissue that is more dense than the tissue that surrounds it. A good example of this is bone compared to muscle and the soft tissue and cells encasing it. In order to gain more clarity when using a CT scan, the medical personnel may administer what is known as a contrast agent. To get the most from this, the substance used may be more dense than the part of the body being investigated. This makes iodine or barium good substances to use. For example, for those of us who have had x-rays, the term barium meal may be familiar. The acronym MRI is an abbreviation of the term magnetic resonance imaging. Unlike CT and x-ray systems, MRI does not use ionizing radiation. Instead it uses radio waves sent through a magnetic field to acquire its images. This makes it ideal for investigating non-calcified tissue, i.e. other than bones and teeth. That is not to say it cannot be used for this purpose, it is just better suited for looking at softer tissue, organs and cells in the body. A contrast agent can also be used when carrying out an MRI scan: gadolinium or manganese are the most appropriate types as they have paramagnetic properties, and of course MRI makes use of magnetic fields. Although both CT and MRI scans produce two dimensional images of tissue and three dimensional reconstructions are created from this, MRI scans have greater image contrast capabilities. By varying an array of scanning parameters, different features of the body can be detected more easily. An MRI is generally considered to be more accurate when it comes to detecting tumors or problems in the brain, although a CT scan is better at detecting solid tumors in the abdomen or chest. A CT scan is cheaper than carrying out an MRI scan and is also more widely available so is usually the preferred route to take by doctors. An MRI scan tends to be used only when they have exhausted the other options and need further information still. A CT scan is also much quicker than an MRI scan. Both mri scans and CT scans are important tools used by a doctor to facilitate accurate diagnoses of serious illnesses such as heart disease and cancer. When used in imaging in oncology, these modalities are particularly vital. By combining scanned images over time they allow information to be obtained such as how much the cancerous cells have spread and at what rate they are growing. This means patients can receive updates on whether their treatment is working and whether the cancer shrinking rather than growing in size. PET CT software in particular is vital for providing valuable oncological information such as this. Very different but equally as important as one another, CT scans, and MRI scans as well, play an important role in modern medicine. Kathryn Dawson writes articles for Mirada Medical Limited, a developer of medical imaging analysis applications which are used across nuclear medicine, diagnostic radiology, radiation and medical oncology and neurology. Their powerful XD3 application is a leader in diagnostic use of images gained from mri scans and pet ct software. Mirada Medical’s flagship product allows advanced diagnostic use of imaging in oncology.