In the modern era, the use of imaging techniques supports the diagnosis of diseases to a great extent. These techniques include, but are not limited to, X-rays, ultrasounds, PET scans, fluoroscopy, CT scans, and MRI scans. These provide images of the inner body parts, without the need to surgically open it up. These imaging techniques frequently aid in treatment and also help track the progress of diseases.
CT scans, short for “computed tomography” scans, use X-rays to build cross-sectional pictures of the body. These are used for taking images of tumors and observing its response to treatment, bone fractures, and damage to organs. CT scans use technology similar to X-rays, but with radiations in higher amounts.
MRI stands for “Magnetic resonance imaging” and, as the name suggests, uses magnetic and radio waves to create images. There are no radiations in an MRI scan.
These scans are used to take detailed images of soft tissues, organs such as the heart, brain, and blood vessels, and some bones and joints.
Both methods require the person to lie down on a bed, which moves into a scanner. They need to remain very still for clear images. They can talk to the technician via an intercom, who is mostly in the next room during the procedure. MRI machines are noisier than the CT machines, and the patient may require earplugs.
Due to the use of radiations, CT scans and x-rays are not safe in pregnancy and must be avoided. MRI scans and ultrasounds do not use radiations and are generally acceptable in such cases. On the other hand, MRI scans use magnetic fields, which can interfere with metallic particulars, such as pacemakers, insulin pumps, artificial joints, intrauterine devices, and eye/ear implants. The doctor keeps these conditions in mind before sending the patient for imaging.
There are various types of CT scans and MRI scans defined by the part of the body under inspection, such as CT scan head, CT scan pelvis, CT scan chest, MRI brain, Cardiac MRI, and MRI spine.
In both imaging techniques, contrast dyes are sometimes given orally or injected into the blood vessel of patient to get more detailed images. For example, in CT-abdomen with oral contrast, the contrast dye is given orally to examine the stomach and intestines; in CT angiogram, the contrast dye is injected to outline the blood vessel network of the heart; MRA (Magnetic resonance angiography) and MRV (Magnetic resonance venography) also use intravenous contrast to show the blood vessels of any specific organ like brain.
In a nutshell, CT scans are less expensive, less detailed, and cover more area of the body, while MRI scans are more expensive, more focused, and give detailed images.
For any patient, the doctor decides the method and type of imaging keeping in view the requirements and the specific history of the patient.