Medical Diagnostic Tests: ECG, Glucometer, MRI, EEG, X-Rays, PET, Ultrasound
Electrocardiogram (ECG)
An electrocardiogram is a painless test that records the electrical activity of the heart. You will be asked to lie down while a healthcare provider attaches small electrodes to your chest. These electrodes are connected by wires to a machine that turns the heart’s electrical signals into wavy lines, which are printed on paper.
These signals show three parameters: P wave, QRS complex, and ST segment. The size of these parameters and the distance between them can reflect:
- Damage to the heart.
- How fast your heart is beating and if it is beating normally.
Glucometer
A glucometer is a machine used for determining the amount of glucose in the blood. The process consists of pricking the skin with a lancet and putting the blood sample onto a test strip, which measures the glucose in mg/dL. It is commonly used by people with diabetes or hypoglycemia.
Depending on the concentration of glucose, the membrane of the test strip produces stronger or weaker electrical signals. These signals are interpreted by the glucometer, which displays the concentration of glucose in the blood sample. It can be used by anyone, except for people with hemophilia.
Magnetic Resonance Imaging (MRI)
A magnetic resonance imaging (MRI) is an imaging test that uses powerful magnets and radio waves to create images of the body. No radiation (X-rays) is used.
The patient lies on a narrow table, which slides into a large tunnel-like tube. A dye rich in gadolinium (Gd) is often administered intravenously (IV) in your hand or forearm before the test. This dye will be magnetized by the magnets of the machine, and its movements will be detected and processed into images called “cuts” that will be stored in the computer or shown on a screen.
It is used to find anomalies such as tumors or infections inside the body with accuracy and image quality.
Electroencephalogram (EEG)
An electroencephalogram (EEG) is a test that detects electrical activity in your brain using electrodes that are attached to your scalp. You need to lie still during the test because movement can affect the results. Your brain cells communicate via electrical impulses and are active all the time, even when you’re asleep. This activity shows up as wavy lines on an EEG recording.
An EEG is one of the main diagnostic tests for epilepsy and may also help to diagnose head injuries or sleep disorders.
X-Rays
X-rays involve the emission of high-energy rays (electromagnetic waves) that can pass through certain body tissues and create an image.
The machine is composed of a tube that releases the radiation. The patient is positioned between the machine and a radiographic film. This way, the radiation passes through the patient’s body and is absorbed by the tissues. Depending on the density of the tissue, a different amount of energy will be absorbed. Bones absorb x-rays the most and appear white on the radiographic film, soft tissues absorb less and look grey, and air absorbs the least, so it looks black. That is how an image is formed.
It is used for detecting tumors and traumas. It cannot be used on pregnant women.
Positron Emission Tomography (PET)
PET is a non-invasive tomography method to identify carcinogenic activity. This method works by introducing a radioactive marker in a substance, for example, glucose, which is given to the patient. Because of the high activity of the cancer cells, they metabolize more glucose with this marker than other cells, so tumors emit a more intense radioactive light.
A tomograph then detects gamma rays emitted by the patients. If the amount of rays is elevated, the patient may be suffering from cancer. Although PET is a safe test, it is not recommended for pregnant women.
Ultrasound
Ultrasound is a sound with a higher frequency than humans can hear.
In medicine, ultrasound devices are used to visualize internal parts of our body, especially fetuses in pregnant women and muscles.
Images are produced by sending an ultrasound pulse through the skin using a hand-held device, while a receptor records and displays the echoes that are produced, and a computer generates the images.