Single Photon Emission Computed Tomography (SPECT)

[lwptoc]

WHAT IS SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY?

The single-photon emission computed tomography (SPECT) is a scanning test that monitors the flow rate of blood into the organs and tissues in the body. 

It can also be abbreviated as SPET and it is similar to positron emission tomography (PET) as they both utilize radioactive tracer with the disparity in emission. The SPECT radioactive tracer emits gamma rays while the PET emits a positron.

The single-photon emission computed tomography involves the use of both nuclear materials and computed tomography to obtain an accurate 3D image of the blood flow into the organs and tissues. 

Scintigraphy which involves the use of a gamma camera and a radioactive tracer is used to perform this operation. According to research, the single-photon emission computed tomography might be preferable to even the MRI or CT scan as it detects reduced blood flow from injured regions in the brain.

WHY IS IT DONE?

The single-photon emission computed tomography mainly monitors the flow of blood in the brain using the arteries and veins as a medium. The single-photon emission computed tomography can be performed also for other various reasons and these reasons are listed below:

1. Monitor blood flow into the organs and tissues. 
2. Monitor patient’s response to treatment administered. 
3. It aids with diagnosing conditions related to psychological issues like schizophrenia. 
4. It is performed to check for signs of cancer and fractures in the bone.
5. It helps to deduce the causes of seizures and epilepsy. 
6. It aids in the detection of gall bladder disease. 
7. It provides information about stroke or transient ischaemic attack (TIA).
8. The SPECT helps in obtaining the cause of brain death.
9. It observes the liver or kidney for cancer.
10. It also monitors the heart in cases of clogging of arteries.

ELIGIBILITY 

The single-photon emission computed tomography can be performed on anyone except for patients that are sensitive to nuclear and radioactive materials i.e use of x-rays. Also, women that are breastfeeding and pregnant are expected to follow the specifications prescribed by the doctor before conducting the test.

HOW TO PREPARE

The preparation for the SPECT test is dependent on the patient’s medical condition but generally, comfortable clothes should be worn and jewelry should not be worn. 

Other preparations to be made for the single-photon emission computed tomography for specific conditions must be noted and they are expressed below:

1. Diabetic patients are expected to take a lesser dosage according to the doctor’s prescriptions.
2. All medications and supplements taken by the patients should be brought to the doctor. 
3. Relate to the doctor of any history of the nuclear scan, have allergies to substances like iodine.
4. Patients that are pregnant or breastfeeding must inform the doctor.
5. It is expected of the patient to fast just 6 hours before the SPECT scan is to be conducted. 
6. Avoid smoking or drinking alcohol within 24 hours before undergoing the scan.
7. Consent will be needed to be signed after the process and risks have been outlined to the patient. 

PROCEDURE FOR SPECT

The procedures associated with the single-photon emission computed tomography are grouped into the before, during, and after stages. These stages are explained below:

• Before the Scan,

A small dose of a radioactive tracer is always injected with the aid of an intravenous (IV) infusion into the arms in which a warm feeling follows suit. Afterward, the patient is to relax for about 30 minutes or more for the tracer to circulate the whole body.

• During the Scan,

After the tracer has been induced, the SPECT scan is done through the machine. It contains a gamma camera that previews and captures the images by tracing the radioactive tracer in the internal organs and tissues. The pictures are then sent to a computer producing 3-D images of the body.

• After the Scan,

The radioactive tracer leaves the body through excretion by defecating on urinating after few hours. It is advisable to drink a large quantity of water or juice. After a few days, the tracers will completely be broken down.

RESULTS

After the scan, the results are sent to a radiologist for examination and after thorough analysis, the report is sent to the doctor showing which part of the system absorbed more of the tracer. Colors are used for indicating the regions where the tracer absorbed more.

DURATION 

The duration of the scan can last for 2-3 hours depending on the amount of time taken for the tracer to circulate the patient’s body. The output of the result depends on the doctor and radiologist conducting the investigation.

RISKS

Succeeding cases of allergies after undergoing the single-photon emission computed tomography are rare. 

The following are side effects that might be observed after the single-photon emission computed tomography scan.

1. Nuclear imaging has few risks involved i.e the use of  X-rays tends to be the greatest risk as allergies to the radioactive tracers are rare.
2. Other risks involved can be the radioactive tracers possibly affecting mothers who are still breastfeeding as the tracers can flow to the breast but prescriptions followed by the doctor can curb this after-effect.
3. Some patients tend to have swelling in the region where the radioactive tracer was injected through. But rubbing an ointment gently to the arm can ease the swelling with time.
4. The chance of damages to the tissue or cell is feasible but the advantages of the test outweigh the risks involved. 
5. The radioactive tracer can be excreted through urination or defecation in a day, therefore, the toilet is to be flushed properly and hands must be washed properly with water and soap. 

SPECIALTY 

The single-photon emission computed tomography can be conducted by a well-trained nuclear medicine technologist or a professional radiologist. The scan must be performed in the nuclear medicine department in the hospital or ambulatory imaging center. 

COST

The single-photon emission computed tomography is expensive for a startup diagnostic checkup, the cost-effectiveness makes it expensive.  The cost of the single-photon emission computed tomography ranges from $5000 to $21000 in the U.S, all depending on the diagnosis. 

FAQs

• What is the difference between positron emission tomography and single-photon emission computed tomography?

The PET and SPECT differ in the final emission as the former emits positron while the latter emits gamma rays.

• What is the accuracy for the single-photon emission computed tomography?

The Single Photon Emission Computed Tomography has an accuracy rate of 83% making it extremely effective for usage.

• Is the Positron emission tomography better than the single-photon emission computed tomography?

The SPECT is better than the PET in terms of the timeline for the usage of the imaging as the half-lives of the radioactive tracer of the SPECT can last up to 6 hours while the PET lasts for just 75 seconds which is not enough time. Also, the SPECT is cheaper in equipment and tracer than the PET.

• Can a SPECT scan diagnose dementia?

The single-photon emission computed tomography can be used for brain scans thereby taking cognizance of the presence of dementia. Therefore, it can be used to diagnose dementia.

• Can a SPECT detect depression?

Without doubts, the activities of the brain can be monitored by the single-photon emission computed tomography but the symptoms portraying depression can also mean another process occurring in the brain. Therefore,  it can not be said with full assurance that the SPECT can detect depression.

• Is it advisable to eat and drink before undergoing the SPECT scan?

This depends solely on the doctor as it will be prescribed to the patient depending on the conditions surrounding the patient but the patient is to avoid drinking alcohol for 24 hours before the operation commences.

• Should the scan be done more than once?

The test is done once except for cases where the patient is diagnosed, then follow-up scans are performed to identify the problem, and solutions are proffered by the doctor.