A computerized tomography (CT) or computerized axial tomography (CAT) scan integrates data from several X-rays to create a clear image of the body’s internal structures.
CT scans generate 2-dimensional pictures of a “slice” or body part, but the data can also be used to conduct 3-dimensional images. A CT scan can be compared to looking at a whole loaf of one slice of bread.
The CT scans are used worldwide in hospitals.
What is a CT scan?
A CT scanner emits a sequence of narrow beams across the human body as it passes through an arc. This is different from an X-ray machine which sends only one beam of radiation. The CT scan provides a more accurate final image compared to an X-ray image.
X-ray detector by the CT scanner can see hundreds of different density levels. It is able to see tissues inside a solid organ.
This data is transmitted to a computer, which creates a 3-D cross-sectional representation of the body part and displays it on the screen.
A contrast dye is often used, as it can help to display certain structures more clearly.
For example, if the abdomen needs a 3-D picture, the patient may need to drink a barium meal. On the scan the barium appears white as it passes through the digestive system.
When photos are needed lower down the body, such as the rectum, a barium enema may be given to the patient. If photos of the blood vessel are the target, they can inject a contrast agent into the veins.
With the application of Spiral CT, a fairly new technology, the precision and speed of CT scans can be enhanced. During the scanning the beam follows a spiral path so it gathers continuous data with no image gaps.
CT is a valuable tool in medicine to help in diagnosis but it is a source of ionizing radiation and can potentially cause cancer.
The National Cancer Institute is suggesting that patients address with their doctors the dangers and benefits of CT scans.
It is useful for obtaining images of:
- soft tissues
- the pelvis
- blood vessels
CT is also the best way to treat other cancers such as liver cancer, lung cancer and pancreatic cancer.
The picture helps a physician to confirm a tumor’s existence and position, its size and how much it has infected surrounding tissue.
For example, a scan of the head may provide valuable brain information when there is bleeding, artery swelling, or a tumor.
A CT scan will show a tumor in the abdomen, and any inflammation or swelling in surrounding internal organs. It may exhibit spleen, kidney, or liver lacerations.
It is useful for preparing areas for radiotherapy and biopsies, since a CT scan identifies irregular tissue, which can provide important data on blood flow and other vascular conditions.
It will help a doctor determine bone disorders, bone density and the patient’s spine condition.
It may also provide the hands, feet, and other structural structures of a patient with essential data about injuries. And small bones, and their underlying tissue, are clearly evident.
CT versus MRI
The main differences between CT and MRI are:
- A CT scan uses X-rays, but an MRI uses magnets and radio waves.
- Unlike an MRI, a CT scan does not show tendons and ligaments.
- MRI is better for examining the spinal cord.
- A CT scan is better suited to cancer, pneumonia, abnormal chest x-rays, bleeding in the brain, especially after an injury.
- A brain tumor is more clearly visible on MRI.
- A CT scan shows organ tear and organ injury more quickly, so it may be more suitable for trauma cases.
- Broken bones and vertebrae are more clearly visible on a CT scan.
- CT scans provide a better image of the lungs and organs in the chest cavity between the lungs.
The patient may need to abstain from food for a limited duration before the exam, and probably drink.
On the day
The patient will have to undress in most cases, usually down to their panties, and put on a gown that will be issued by the health centre. Do not wear jewellery.
If a gown isn’t issued by the hospital, the patient will wear loose-fitting garments free of metal buttons and zippers.
Some patients will have to drink a contrast dye, or the dye may be given as an enema, or injected. This enhances the appearance of certain blood vessels or tissues.
Any patient with an allergy to the contrast material will inform the doctor in advance. Some medicines can reduce allergic reactions to materials that contrast them.
As metal interferes with the CT scanner’s working, the patient may have to remove all jewelry and metal fastenings.
During the scan
The patient will have to lie on a motorized exam table which slides into a doughnut-shaped CT scanner.
In most cases, the patient lies on the back and faces upwards. But they can need to lie face-down or sideways, often.
The couch will turn slightly after one x-ray image, and then the camera will take another image, and so forth. For the best results the patient requires to lie very still.
All except for the patient will be leaving the room during the exam. An intercom will allow bidirectional communication between the radiograph and the patient.
If the patient is a child, a parent or adult will be allowed to stand or sit nearby but they may need to wear a lead apron to avoid exposure to radiation.
A CT scan will require a low, focused radiation dose.
Such levels of radiation have not proved dangerous, particularly in people who have undergone several scans.
The risk of developing cancer is believed to be less than 1 in 2,000 as a result of a CT scan.
It is calculated that the amount of radiation involved is about the same as a person would be exposed to natural exposure in the atmosphere over a period of between several months and several years.
A scan is only given if the medical reason for doing so is valid. The findings can lead to treatment for otherwise severe conditions. When the decision to conduct a scan is made, doctors must make sure the benefits outweigh the harm.
Problems which may arise from exposure to radiation include cancer and thyroid problems.
This is extremely unlikely in adults, and rare in children too. However, they are more vulnerable to radiation effects. This does not mean that there would be health complications but any CT scans should be noted on the medical record of the infant.
In certain cases, the necessary results can only be seen on a CT scan. An ultrasonic or MRI may be necessary for certain circumstances.
Can I have a CT scan if I am pregnant?
Any woman who thinks that she might be pregnant should inform her doctor in advance, because there is a risk that the x-rays could damage the fetus.
The American Pregnancy Association (APA), citing the American College of Radiography, points out that “No single diagnostic x-ray has a radiation dose sufficiently large to cause adverse effects in a developing embryo or fetus.” However, the APA states that CT scans are not recommended for pregnant women, “Unless the benefits clearly outweigh the risk.”
CT scans and breastfeeding
When, in comparison, a lactating or breastfeeding mother requires an iodinated intravenous dye, she should stop breastfeeding for about 24 hours as the breast milk can pass through.
I have claustrophobia: Can I have a CT scan?
A patient who has claustrophobia should inform their doctor or x-ray in advance. Before the exam, the patient can get an injection or tablet to calm them down.
Finding a radiologist
Your health care professional should usually be able to suggest a appropriate scan location. Through visiting the American College of Radiology website, you can verify if a radiologist is certified.
What’s to know about amniotic fluid?
Amniotic fluid is a clear, yellow fluid that is present within the amniotic sac during the first 12 days after conception. It encircles the growing baby in the uterus.
Amniotic fluid has several essential functions and is vital for healthy fetal development. However, if there is too little or too great an amount of amniotic fluid inside the uterus, complications can occur.
This article discusses the various roles of amniotic fluid, and what happens when amniotic fluid levels are either too high or too low.
Important facts about amniotic fluid
- At first, amniotic fluid consists of water from the mother’s body, but gradually, the larger proportion is made up of the baby’s urine.
- It also contains important nutrients, hormones, and antibodies and it helps protect the baby from bumps and injury.
- If the levels of amniotic fluid levels are too low or too high, this can pose a problem.
What is amniotic fluid?
While a baby is in the womb, it is inside the amniotic sac, a bag consisting of two membranes, the amnion and the chorion. Within this sac the fetus grows and develops, surrounded by an amniotic fluid.
Initially the fluid is made up of mother-generated water. However this is completely replaced by fetal urine by about 20 weeks gestation, when the fetus swallows and excretes the fluid.
Amniotic fluid as well contains vital components, such as nutrients, hormones, and infection-fighting antibodies.
It means that when amniotic fluid is green or brown the baby has absorbed meconium before birth. The term for the first bowel movement is Meconium.
Meconium can be problematic in the fluid. It may cause meconium aspiration syndrome, a breathing issue that happens when the meconium reaches the lungs. Babies can in some cases need treatment after birth.
Amniotic fluid is responsible for:
- Protecting the fetus: The fluid cushions the baby from outside pressures, acting as a shock absorber.
- Temperature control: The fluid insulates the baby, keeping it warm and maintaining a regular temperature.
- Infection control: The amniotic fluid contains antibodies.
- Lung and digestive system development: By breathing and swallowing the amniotic fluid, the baby practices using the muscles of these systems as they grow.
- Muscle and bone development: As the baby floats inside the amniotic sac, it has the freedom to move about, giving muscles and bones the opportunity to develop properly.
- Lubrication Amniotic fluid prevents parts of the body such as the fingers and toes from growing together; webbing can occur if amniotic fluid levels are low.
- Umbilical cord support: Fluid in the uterus prevents the umbilical cord from being compressed. This cord transports food and oxygen from the placenta to the growing fetus.
Normally, the level of amniotic fluid is at its highest around 36 of pregnancy, measuring around 1 quart. As birth nears, this level decreases.
The amniotic sac gets tears when the waters break. The amniotic fluid inside the sac then starts flowing out of the cervix and vagina.
Usually the waters split at the end of the first labor stage. Only about 15 percent of waters break upon the onset of labor, according to Today ‘s Parent. It is time to contact the healthcare professional when this happens, as delivery can be imminent.
Some conditions can cause amniotic fluid to be more or less than the normal amounts.
Oligohydramnios is when there is too little amniotic fluid.
Polyhydramnios, also referred to as hydramnios or amniotic fluid disorder, is when there is too much fluid.
Low levels of amniotic fluid, or oligohydramnios, occur in 4% of all pregnancies, and 12% of post-date pregnancies.
This can be evident when leaking fluid from a tear in the amniotic membranes, measuring small for a certain stage of pregnancy, or when the fetus does not move as much as expected.
For mothers with a history of any of the following medical conditions, this may also happen:
- prior growth-restricted pregnancies
- chronic high blood pressure (hypertension)
- problems with the placenta, for example, abruption
- multiple pregnancies, for example twins or triplets
- birth defects, such as kidney abnormalities
- delivering past the due date
- other unknown reasons, known as idiopathic
Oligohydramnios can occur during any trimester but during the first 6 months of pregnancy it is more of a concern. There is a greater chance of birth defects, loss of pregnancy, premature birth or neonatal loss of life during that period.
If fluid levels are low in the last trimester, the risks include:
- slow fetal growth
- labor complications
- the need for a Cesarean delivery
The rest of the pregnancy will be monitored closely to ensure normal development is taking place.
Doctors may use the following tests:
- Nonstress tests: This is to check the baby’s heartbeat when it is resting and when it is moving.
- Biophysical profiling: An ultrasound scan can detect the baby’s movements, muscle tone, breathing and amniotic fluid levels. This may be followed up with a nonstress test.
- Fetal kick counts: This is to time how long it takes for the baby to kick a certain number of times.
- Doppler studies: These use sound waves to check the flow of blood in the baby.
For certain cases , doctors may agree that to protect the mother or the infant, labor may need to be induced. Amnioinfusion (saline infusion into the uterus), an increase in maternal fluids, and bed rest may also be needed.
Due to the risk of umbilical cord compression, there is a greater chance of labor complications. During labor, amnioinfusion can be required. In certain cases it may be appropriate to offer a cesarian delivery.
This is called polyhydramnios, when there is too much amniotic fluid. It happens in 1 percent of all births, according to the American Pregnancy Association.
Polyhydramnios occurs when the AFI reaches 24 centimeters (cm) and the MVP measures more than 8 cm.
Fetal disorders that can lead to polyhydramnios include:
- gastrointestinal disorders, including duodenal or esophageal atresia, gastroschisis, and diaphragmatic hernia
- brain or nervous system disorders, such as anencephaly or myotonic dystrophy
- achondroplasia, a bone growth disorder
- fetal heart rate problems
- Beckwith-Wiedemann syndrome, which is a congenital growth disorder
- fetal lung abnormalities
- hydrops fetalis, in which an abnormal level of water builds up inside multiple body areas of a fetus
- twin-to-twin transfusion syndrome, where one child gets more blood flow than the other
- mismatched blood between mother and child, for example Rh incompatibility or Kell diseases
Poorly controlled maternal diabetes increases risks as well.
During multiple pregnancies too much fluid may also be created when the mother carries more than one fetus.
Maternal symptoms can include abdominal pain, and breathing problems due to uterine enlargement.
Other complications include:
- preterm labor
- premature rupture of membranes
- placental abruption
- postpartum hemorrhage
- fetal malposition
- cord prolapse
Maternal diabetes testing can be recommended, and regular ultrasounds are obtained to monitor the amniotic fluid levels in the uterus.
Mild cases of polyhydramnios typically resolve untreated.
For more serious cases, either amniocentesis or a medication called indomethacin may need to minimize the fluid. Which reduces the amount of urine released by the infant.
Leaking amniotic fluid
Fluid leaks sometimes before waters break. Only 1 in 10 women will feel a rapid flood of fluid as the waters break, according to the American Pregnancy Association. It’ll start as a trickle, or leak, for most.
Occasionally, since the uterus is pulling on the bladder, what appears like fluid leaking is actually urine.
If there is no color and no smell in the fluid, it will be amniotic fluid, and you should contact a health care provider as work normally starts soon.
This may suggest the existence of meconium or an infection if the fluid is green, brownish-green or foul-smelling. Medical advice should be sought.
Premature rupture of membranes
If leakage or rupture occurs before 37 weeks this is called premature membrane rupture (PROM). It can have serious consequences for the mother and the unborn child, depending on how early that happens. Around 2 in 100 pregnancies are affected.
It is known as premature preterm rupture, but premature rupture is also possible on term. That is when 37 weeks of pregnancy or more are complete, but labor does not start spontaneously within 6 hours of the rupture of the membrane.
As this may lead to an infection, it is necessary to seek medical attention as soon as possible and to stop having intercourse or putting something into the vagina.
Someone who concerns about leakage or amniotic fluid levels during pregnancy should discuss this with their health care provider.
What is a PET scan, and are there risks?
A positron emission tomography, also known as a PET scan, uses radiation to reveal cellular activity within the body.
This is most commonly used in cancer therapy, neurology, and cardiology.
Combined with a CT or MRI scan, a PET scan can produce multidimensional, color images of the human body’s inner workings.
It not only reveals what an organ looks like but how it functions.
A PET scan is used to identify certain disorders of health, to schedule care, to assess how an current disease progresses and to see how successful a medication is.
Important facts about PET scans
- PET scans are often used to diagnose a condition or to track how it is developing.
- Used alongside a CT or MRI scan, it can show how a part of the body is working.
- PET scans are often used to investigate epilepsy, Alzheimer’s disease, cancer, and heart disease
- A scan is not painful, but patients should not consume any food for at least 4 to 6 hours before a scan. They should drink plenty of water.
How it works
A computer measures radiation, released by a radiotracer, in a PET scan.
A radiotracer consists of radioactive material which, like glucose, is attached to a natural chemical.
This radiotracer is injected into the body, where it travels to energy-consuming cells consuming glucose.
The more energy a group of cells requires, the more the radiotracer at that position can build up. This will show up on computer-reconstructed images.
The cells, or activity, will show as “hot spots” or “cold spots.” On a PET scan the active areas are bright.
These are known as “hot spots.” Where cells need less energy, the areas would be less bright. They are “cold spots.”
Cancer cells are very involved in the use of glucose relative to normal cells, and a glucose-made radiotracer light up areas of cancer.
The image created on the screen will be analyzed by a radiologist and a doctor will report the findings.
Fluorodoxyglucose (FDG) is an example of a glucose dependent radiotracer. In FDG, molecules of radioactive fluoride are labelled to create a radiotracer by glucose. FDG is the most commonly used radiotracer today.
Oxygen can be used, rather than glucose.
PET scans are also combined with CT or MRI scans to help make a diagnosis or to collect more details about a health condition and any medical progress.
PET scans are widely used to study different conditions.
Epilepsy: It will show which part of the brain causes epilepsy.
It can help doctors determine which care is most suitable, and it can be useful if surgery is required.
Alzheimer’s disease: PET scans may help identify Alzheimer’s disease through assessing sugar intake in different brain regions.
Brain cells that have Alzheimer’s affect appear to use glucose more slowly than normal cells.
Cancer: PET scans will reveal a cancer’s existence and stage, demonstrate whether and where it has spread and help doctors decide on the treatment.
Heart disease: A PET scan can help detect weakened or scarred parts of the heart, and can help identify circulation problems in the heart’s function.
Such knowledge can aid in the planning of heart disease treatment options.
Medical research: Scientists can learn valuable information using PET scans, in particular about brain functioning.
Differences between PET, CT, and MRI scans
A CT or MRI scan can determine the size and shape of body organs and tissue, but can’t measure how these work.
A PET scan will demonstrate how an organ functions but it can be difficult to determine the exact position of activity inside the body without a CT or MRI image.
A PET scan combined with a CT scan will provide a more detailed image of the patient’s situation
In general, a PET scan is an outpatient treatment.
The patient does not usually eat any food for at least 4 to 6 hours before the scan but should drink plenty of water. They may need to stop coffeine at least 24 hours before scanning.
First, a small volume of radiotracer would be administered into a vein by the doctor Also, the tracer may be breathed in as a gas, taken by mouth or directly injected into an organ.
Depending on which organ is involved, it may take the radiotracer 30-90 minutes to reach the targeted body part.
Meanwhile, the patient is usually told to stay quiet and not speak. Some patients can receive calming medication.
The patient is likely to need to wear a robe, and will need to remove jewelry.
When the patient is ready for the scan, they are taken to a different room scan. They’ll lie on a cushioned test table.
The table slides into a large hole to encircle the patient.
Patient will stay as calm as possible. They may be able to listen to the music.
The computer takes pictures during the scan.
This will take about 30 minutes depending on which part of the body is being scanned.
It’s not even uncomfortable. If the patient feels unwell, they may press a buzzer to alert the workers.
During the scan a professional doctor must look at the patient.
Usually, the whole testing process takes about 2 hours. Most patients are permitted to go home once the scan is complete.
Patients can eat plenty of water to wash the toxic substances out of their body quicker. The radiotracers would have left the body in 3 to 4 hours, absolutely.
Exposure to radiation runs a risk.
The benefits of getting a PET scan, for most people, outweigh the risks.
However, it is not appropriate for everyone since a PET contains radioactive material.
A pregnant woman does not usually have a PET scan, because the radioactive material may affect the fetus or the baby.
If a woman is breastfeeding, she will follow directions for breast milk pumping and discarding, and ask the doctor when it is appropriate to restart breastfeeding based on the test completed.
Any woman who is pregnant or breast-feeding will immediately inform her doctor before getting a PET scan.
A patient may be advised to remain away from pregnant women, babies, and young children for a few hours after a PET scan, as the radioactivity presents a slight risk.
An individual can very rarely have an allergic reaction to the tracer.
How do ultrasound scans work?
An ultrasonic scan uses sound waves of high frequency to produce images of the body’s inside. Good for use during pregnancy.
Ultrasound scans, or sonography, are safe because, instead of radiation, they use sound waves or echos to create an image.
Ultrasound scans are used to determine fetal growth, and they can detect liver, heart, kidney or abdominal problems. Also, they can help with other forms of biopsy.
The created image is called a sonogram.
Important facts about ultrasound scans
- Ultrasound scans are safe and widely used.
- They are often used to check the progress of a pregnancy.
- They are used for diagnosis or treatment.
- No special preparation is normally necessary before an ultrasound scan.
The individual doing an ultrasound scan is called a sonograph, so radiologists, cardiologists, or other experts interpret the images.
Typically the sonographer carries a transducer, a handheld instrument, like a wand which is positioned on the skin of the patient.
Ultrasound is a sound moving through soft tissue and fluids, but it bounces backwards, or echoes, off denser surfaces. So it creates a image.
The term “ultrasound” refers to sound at a frequency which can not be heard by humans.
Typically the ultrasound for diagnostic uses varies between 2 and 18 megahertz (MHz).
Higher frequencies provide better images of quality, but are more readily absorbed by the skin and other tissues, so they can not penetrate as deeply as lower frequencies.
Higher frequencies penetrate deeper, but inferior in image quality.
How does it capture an image?
Ultrasound, for example, passes through blood in the heart cavity, but if it reaches a heart valve, it returns, or bounces back.
If there are no gallstones, it will pass straight into the gallbladder but if there are stones, it will bounce back from them.
The denser the target hits the scanner, the more it bounces back.
This bouncing back, or echo, gives its features to the ultrasonic picture. Increasing shades of grey represent increasing densities.
The transducer, or wand, is usually mounted on the patient’s body surface but certain kinds are mounted internally.
This will include photos which are simpler and more detailed.
- an endovaginal transducer, for use in the vagina
- an endorectal transducer, for use in the rectum
- a transesophageal transducer, passed down the patient’s throat for use in the esophagus
Some very small transducers can be placed on a catheter’s end and inserted into the blood vessels to examine the blood vessel walls.
Ultrasound is commonly used during procedures such as biopsies, for diagnosis, treatment and guidance.
It may be used to analyze internal organs including the liver and kidneys, the pancreas, the thyroid gland, the testes among ovaries, and others.
It can help to diagnose soft tissue disorders, muscles, blood vessels, tendons, and joints. A frozen shoulder, tennis elbow, carpal tunnel syndrome and others are examined.
Ultrasound Doppler can measure blood flow in a vessel or blood pressure. It can assess blood flow rate and any obstructions.
One example of Doppler ultrasound is an echocardiogram (ECG). It can be used to construct cardiovascular system images, and at different points to measure blood flow and cardiac tissue movement.
An ultrasound from Doppler can determine the function and condition of cardiac valve areas, any heart defects, valvular regurgitation, or blood leakage from valves, and it can demonstrate how well the heart pumps out blood.
It can also be used to:
- examine the walls of blood vessels
- check for DVT or an aneurysm
- check fetal heart and heartbeat
- evaluate for plaque buildup and clots
- assess for blockages or narrowing of arteries
A carotid duplex is a type of carotid ultrasonography which may include an ultrasonic Doppler. This will demonstrate how blood cells pass through the arteries of the carotid.
Ultrasound in anesthesiology
Ultrasound is commonly used by anesthetists to direct a needle past nerves with anesthetic solutions.
An ultrasound can be performed in a doctor’s office, in an ambulatory clinic, or in a hospital.
Most scans take 20 to 60 minutes to complete. Usually, it’s not uncomfortable, and no noise.
No special planning is required in most cases, but patients may want to wear loose-fitting and comfortable clothing.
If the liver or gallbladder is affected, the patient can have to either run for several hours before the operation, or eat nothing.
The patient should drink plenty of water for a scan during pregnancy, and especially early pregnancy, and try to avoid urinating for some time before the test.
The scan provides a better image of the uterus when the bladder is full.
The scan normally takes place inside a hospital’s radiology department. The test is carried out by a doctor or a specially trained sonographer.
The sonographer places a lubricating gel on the skin of the patient, and puts a transducer above the lubricated surface.
The transducer is placed over the body part which needs to be checked. Examples include ultrasonic tests of the heart of a patient or a fetus in the uterus.
The patient should not be feeling pain or discomfort. They are just going to feel the transducer over the skin.
The full bladder can cause slight discomfort during pregnancy.
If it is appropriate to examine the internal reproductive organs or urinary system, the transducer can be positioned in a man’s rectum or in a woman’s vagina.
For example, an endoscope can be used to examine any portion of the digestive system, the esophagus, chest lymph nodes, or the stomach.
At the end of the endoscope, which was placed into the patient’s body, a light and an ultrasound tool was connected, normally through the mouth.
Patients are given drugs prior to the operation to reduce any discomfort.
Internal ultrasonic scans are less convenient than external ones, and the chance of internal bleeding is small.
Most types of ultrasound are noninvasive, and do not involve exposure to ionizing radiation. It’s believed the procedure is very healthy.
Nonetheless, unnecessary “keepsake” scans during pregnancy are not recommended because the long-term risks are not known. Ultrasound is recommended only when medically needed during pregnancy.
Anyone who’s allergic to latex will Inform their doctor not to use a latex-covered probe.