SERVICES: DIAGNOSTIC IMAGING PROCEDURES
MRI (Magnetic Resonance Imaging)
Advanced MRI & CT of Escondido utilizes GE's 1.5 Tesla LX High-Field MRI in a relaxed non-claustrophobic atmosphere. The MRI is a non-invasive procedure (No Pain) that uses a powerful magnet and radio waves produce pictures of the body.
Unlike conventional radiography and Computed Tomographic (CT) imaging, which make use of X-rays, MRI imaging is based on the magnetic properties of atoms. A powerful magnet generates a magnetic field roughly 10,000 times stronger than the natural background magnetism from the earth. A very small percentage of hydrogen atoms within a human body will align with this field.
When focused radio wave pulses are broadcast towards the aligned hydrogen atoms in tissues of interest, they will return a signal. The subtle differences in that signal from various body tissues enables MRI to differentiate organs, and potentially contrast benign and malignant tissue.
Any imaging plane (or "slice") can be projected, stored in a computer, or printed on film. MRI can easily be performed through clothing. However, certain types of metal in the area of interest can cause significant errors in the reconstructed images.
How the Test is Performed
Since MRI makes use of radio waves very close in frequency to those of ordinary FM radio stations, the scanner must be located within a specially shielded room to avoid outside interference. The patient will be asked to lie on a narrow table which slides into a short tube within the scanner.
In addition, small devices may be placed around the head, arm, or leg, or adjacent to other areas to be studied. These are special imaging coils which send and receive the radio wave pulses, and are designed to improve the quality of the images. If contrast is to be administered, an IV will be placed, usually in a small vein of the hand or forearm.
No preparatory tests, diets, or medications are usually needed. An MRI can be performed immediately after other imaging studies. Depending on the area of interest, the patient may be asked to fast for 4 to 6 hours prior to the scan.
How to Prepare for the Test
- Because of the strong magnets, certain metallic objects are not allowed into the room.
- Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
- Pins, hairpins, metal zippers, and similar metallic items can distort the images.
- Removable dental work should be taken out just prior to the scan.
- Pens, pocketknives, and eyeglasses can become dangerous projectiles when the magnet is activated and should not accompany the patient into the scanner area.
- Because the strong magnetic fields can displace or disrupt the action of implanted metallic objects, people with cardiac pacemakers cannot be scanned and should not enter the MRI area.
- Inner ear (cochlear) implants
- Brain aneurysm clips
- Some artificial heart valves
- Older vascular stents
- Recently placed artificial joints
- Sheet metal workers, or persons with similar potential exposure to small metal fragments, will first be screened for metal shards within the eyes with X-rays of the skull.
- The patient will be asked to sign a consent form confirming that none of the above issues apply before the study will be performed.
CT Scan
Utilizing GE's High-Resolution CT, Computed Tomography System, Advanced MRI & CT of Escondido's CAT Scans, provides rapid, detailed cross-sectional imaging of the patient which can then be reconstructed into three-dimensional models, as needed. The x-rays are painless. The primary discomfort may be from the need to lie still on the table.Computed tomography (CT) a method of body imaging in which a thin x-ray beam rotates around the patient. Small detectors measure the amount of x-rays that make it through the patient or particular area of interest.
A computer analyzes the data to construct a cross-sectional image. These images can be stored, viewed on a monitor, or printed on film. In addition, three-dimensional models of organs can be created by stacking the individual images, or "slices."
How the Test is Performed
The patient will be asked to lie on a narrow table (gantry) that slides into the center of the scanner. Depending on the study being performed, the patient may need to lie on his/her stomach, back, or side. If contrast media (dye) is to be administered, an IV will be placed in a small vein of a hand or arm.
Much like standard photographic cameras, subject motion causes blurred images in CT. Therefore, the technologist operating the scanner and supervising the patient will give instructions through an intercom when to hold one's breath and not move.
As the exam takes place, the gantry will advance small intervals through the scanner. Modern "spiral" scanners can perform the examination in one continuous motion of the gantry. Generally, complete scans will only take a few minutes, however, additional contrast-enhanced or higher-resolution scans will add to the scan time.
How to Prepare for the Test
The patient may be asked to drink oral contrast either immediately prior to, or 4 to 6 hours before, the CT scan. The contrast may be composed of non-reactive (inert) chalky-tasting barium sulfate, which will eventually pass in the stools, or absorbable clear Gastrografin solution. The health care provider may also advise fasting (no solids or liquids) for 4 to 6 hours if contrast dye is to be used.
The CT scanner has a weight limit to prevent damage to the mechanized gantry. Have the health care provider contact the scanner operator if you weigh more than 300 pounds.
Since metal is very, very dense, the x-ray beam has difficulty passing through it and results in errors in the involved constructed slices (artifact). Therefore, the patient will be asked to remove jewelry and wear a hospital gown during the study.