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CT scans use ionizing radiation to create images of internal organs. Millions of CT scans are done every year to help detect diseases such as strokes. A stroke occurs when the blood supply to all or part of the brain is interrupted.

Strokes are commonly caused by atherosclerosis, dissections and vasculitis. A dissection is the tearing of the wall of the artery. This creates a false channel and can slow blood flow through the normal channel. Vasculitis is inflammation of the vessel wall which can also slow or stop blood flow.

Many small strokes can be "silent" and not noticed or detected by a physical exam. Some strokes quickly resolve on their own and the patient has no neurological deficits. These are called TIAs (transient ischemic attacks). Many strokes are devastating leaving patients with weakness, paralysis, and difficulties with speech and daily living activities.

Stroke symptoms can include:

• Weakness
• Slurred speech
• Tingling/numbness
• Droopy face
• Dizziness/vertigo

The first line in diagnosing a stroke is the physical exam ususally done in the ER by an ER physician and sometimes a Neurologist. Stroke patients may then get a CT scan of the Brain (Head) to confirm the diagnosis or look for other causes of the symptoms (such as a bleed or tumor).

A CT scan of the brain is a very good and vital tool in early diagnosis of strokes. The test is fast and accurate. That said, very early strokes or tiny strokes might not be seen by CT. In these cases, an MRI is much more sensitive. MRI scans though take a long time to do and there is limited availability particularly in the middle of the night. In stroke diagnosis and treatment time is of the essence.

There are new types of CT scanners which can give even more accurate information regarding strokes. These scanners can do what are called "perfusion studies". That is they can tell what parts of the brain have reduced blood flow and are at risk for a larger stroke. However, these scans do require IV dye and deliver higher doses of radiation.

Medical technology plays an important role in stroke diagnosis. But the key to stroke treatment is recognizing the signs and symptoms of a stroke and getting to an ER as fast as possible for treatment.

Please leave your comments below.

CT stands for Computed Tomography. CT scans (aka CAT scans) are medical imaging tests that are used to discover, treat, and monitor disease. They use ionizing radiation and computers to create images of internal organs.

Although a relatively new technology, CT has rapidly advanced along with computing power. There are tens of millions of CT scans done every year. As CT has advanced its importance in detecting disease such as appendicitis, strokes and tumors has increased and so has utilization. It is estimated that CT scan use is growing at about 10% per year.

In fact, at this time there is concern that CT scans are overused and delivering unnecessary high doses of radiation. There have been recent reports in the media regarding high dose CT scan injuries.

What are the side effects of radiation?

There are potentially many side effects, here are the most common:

• Burns
• Nausea, vomiting, diarrhea
• Weakness
• Hair loss
• Dizziness, headache
• Low blood counts
• Organ failure
• Gene mutations and cancer

How much radiation will I get from a CT scan compared to an xray?

Radiation is meaured a variety of ways. One of the units of measurement is Sieverts (Sv). This meaures the effect of radiation on the body. We are naturally exposed to radiation from many different sources such as the earth, atmosphere and space. Below is a short list comparing radiation sources (mSV is milliSieverts which is .001 Sv).

• Background radiation at sea level: 3 mSv per year
• Denver residents get: 6 mSv per year
• Cross country flight: 0.02 mSv
• X ray Chest: 0.06 mSv
• CT Head: 3 mSv
• CT Chest: 5 mSv (equivalent to 100 chest xrays)
• CT Abdomen: 5-10 mSv

Some experts believe that actual radiation doses may be higher for a CT scan of the abdomen and closer to 10-20 mSv. This occurs as multiple scans are made through the organs after IV dye is given. These passes are called "phases" and are done to see to detect subtle changes in tissue characteristics when exposed to the dye. For example, some malignant tumors will take up the dye right away and benign tumors take up dye much slowly. Multiple phases are needed to see this difference.

Experts believe that above 50 mSv there is a slight increase in risk of cancer. Given that some patients get multiple CT scans during a hospitalization or over their lifetime this number could easily be exceeded. In one highly publicized case a young child received 151 scans in the same area of the head (this test has usually 25-30 images spread over the whole head). The child ultimately developed facial burns. Other similar though less dramatic cases have been reported as well.

There are currently attempts to regulate and reduce CT scan radiation exposure. A law was recently passed in California which will require Radiology reports to include the total radiation dose delivered during a CT scan.

Although the medical community is working to reduce CT radiation exposure, patients should be aware and ask questions about the amount of radiation involved in a CT scan.  Ask if there are ways to reduce the dose or select another type of test if possible.

What are your thoughts on CT scan radiation? Please leave your comments below.

CT scans are used to detect and monitor many types of diseases. CT Angiograms are a specific type of CT scan that uses dye injected a high rate to evaluate the arteries of your body.

This CT scan uses special software to create realistic 3D images and gives the Radiologist interpreting the test the ability to look around and inside the vessels. The picture to the right is a 3D rendition from a CT angiogram of the heart. The wavy yellow lines are the coronary arteries. The large cylinder like vessel at the top is part of the aorta coming out of the heart.

CT angiograms are typically ordered for the evaluation of the arteries of the body to look for blockages caused by atherosclerosis, dissections (tears), and aneurysms.  Symptoms related to atherosclerosis disease include:

• strokes
• chest pain
• high blood pressure
• pulsing abdominal mass
• poor circulation to the legs
• sudden sharp neck, chest or abdominal pain

CT Angiograms can diagnose:

Plaque - CT Angiograms of can detect soft and hard plaque deposits that overtime narrow the opening of the vessel leading to reduced blood flow. This can lead to stroke, heart attack or loss of tissue.

Dissection - This refers to a tear in the wall of the vessel. Think of it as a tear of the inner lining of the sleeve of a jacket. If you filled the inner lining of your jacket with down it would block the real opening for your arm.  In the artery the blood goes into the opening of the tear of the dissection, expands the false channel, potentially blocking the flow of blood of blood. Dissections can occur in nearly any large to medium sized vessel in the body leading to impaired or blocked blood flow.

Aneurysms and Vascular Tumors - Aneurysms are ballooning of the vessels that can either disturb normal blood flow or by their shape and size press on nearby tissues and cause related symptoms such as pain, pressure, nerve blockage, etc. Vascular tumors may be picked as the vessels that feed them are large enough to be seen on a CT angiogram.

A CT Angiogram can evaluate:

Vessels of the Neck and Brain

The carotid and vertebral vessels arise from the aorta in the chest and travel up the neck along both sides. The supply blood to the neck, face and brain.

Vessels of the Chest and Heart

The aorta is the main artery in your body which arises from the heart. Smaller vessels branch off the aorta to supply different parts of the body. The coronary arteries which supply your heart are one of first arterial branches of the aorta.

Vessels of the Abdomen

Vessels of the Legs

The abdominal aorta ultimately divides into two major vessels (the iliac arteries) which supply your pelvis and and legs all the way down to the feet.

Your CT Angiogram:

This CT scan generally takes about 15 minutes or so to set up and complete. This test is always done with IV MRI contrast. Keep in mind that the dye is injected at a much higher rate than a standard CT. Therefore a larger IV is used for this test. Many patients feel sudden flashes of heat and a metallic taste in their mouth. You may also feel sudden warmth in your bladder.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an CT Angiogram of the carotids, you can use our website to look up CT Angiogram costs.

Have you had a CT Angiogram scan? What was it like? Please leave your comments below.

X-rays are frequently used to evaluate the bones of the shoulder. If you've injured your shoulder, have chronic shoulder pain, or are going to have shoulder surgery, your doctor will probably order an x-ray. On your doctor's order for the X-ray you might see:

"r/o fracture" -  a fracture is a break in the bone.

"r/o tendinitis"- tendinitis refers to inflammation or injury to the ligaments and tendons around your shoulder.

"r/o djd" - djd is short for degenerative joint disease. It is a generic term that is used to describe bone spurs, joint narrowing, etc.

(FYI - "r/o" is short for "rule out")

An X-ray  of the shoulder will evaluate:

Bones

A shoulder X-ray will include the shoulder joint which includes the humerus bone, scapula, and the clavicle. Parts of the chest are also seen in a shoulder x-ray. An x-ray can detect bone fractures, tumors, infection and evaluate post-surgical changes. The x-ray can also determine the extent of degenerative changes (arthritis) and be used for pre-operative planning for surgery.

Soft Tissues

X-rays are not very good at evaluating the soft tissues around your shoulder in detail. For example an x-ray will not be able to look at the tendons and ligaments that make up the rotator cuff. However, it can pick up indirect signs of tendon injury such as calcium deposits.

Your Shoulder X-ray

A shoulder X-ray generally takes about 5-10 minutes or so to complete. You'll probably be asked to change into a gown. If you are going for one, wear loose comfortable clothing and remember to remove all metal near your shoulder (eg necklaces) before going into the X-ray room.  Shoulder x-rays may include views which require you to move your arm. X-rays do not require preauthorization from your insurance company but you do need a valid doctor's prescription.

Have you had a Shoulder X-ray? What was it like? Please leave your comments below.

CT scans are frequently used to evaluate the temporal bones.  Temporal bone CTs, also known as mastoid bone CTs are typically ordered to evaluate the outer ear, bones of the ear and inner ear structures for infection, tumor, injury or congenital or acquired hearing disorders.  Below are a few common diagnoses that a CT scan of the temporal bones detect.

Mastoiditis - This is an infection of the air filled parts of the temporal bone, located just behind your ear. The infection can be aggressive and erode the bone. Symptoms include dizziness, hearing loss, and pain for example. In extreme cases the infection can extend to the nearby brain. This can cause seizures.

Tumors - Tumors can be from the temporal bone itself or arise in and around the ear structures. These tumors can be either benign or malignant. Some tumors that affect this area include basal cell carcinoma, cholesteotomas, schwannomas, neuromas, and cholesterol granulomas. Symptoms vary but can include pain, hearing loss, and dizziness.

Trauma - In severe head injuries, the temporal bone can fracture and injure the bones of the ear, the nerves that carry sound or damage the facial nerve (and cause facial paralysis). 

An CT scan of the temporal bones will evaluate:

External ear

The outer ear, nearby tissues and the ear canal are well seen and part of the evaluation of the temporal bones. A temporal bone CT can evaluate a severe swimmer's ear infection - otitis externa. Surfer's also develop a bony growth in the ear which can lead to hearing impairment. This is called Surfer's ear.

Middle ear

This includes the ear bones (ossicles) and bone cavities that are involved in transmitting sound. Otitis media is an infection centered in the middle ear.

Inner ear

Sinuses

Portions of the sinuses are seen in a temporal bone CT and sinus disease may be detected.

Skull base

The skull base is a complex set of bones that protect and surround parts of important vessels and nerves. Erosion or injury to the bone can damage these structures. The carotid arteries which feed parts of your brain travel through the skull base.

Your Temporal Bone CT Scan

A temporal bone CT scan generally takes about 5 to 10 minutes or to complete. If you are going for one remember to remove hair pins, nearby piercings, earrings and necklaces as these metallic objects can interfere with the scan. These scans are done without IV contrast.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an CT scan of the brain, you can use our website to look up CT scan costs and then purchase with your credit card.

Have you had a Temporal Bone CT scan? What was it like? Please leave your comments below.

CT scans are frequently used to evaluate the brain (head).  Brain CTs are typically ordered for many different symptoms such as headaches, weakness, seizures, confusion, etc to exclude a tumor, aneurysm or infection.  They are also used as a follow up test for patients with strokes, bleeds or surgery. Below are a few common diagnoses that a CT scan of the brain detect.

Aneurysm - Aneurysms are ballooning of vessels that risk rupturing. If blood leaks from the aneurysm patients describe the headache as a thunderclap and sharp/shooting pains. Patients can also have stroke-like symptoms with weakness, slurred speech and confusion. A Brain CT scan is the first test done to evaluate for a bleed.

Tumors - Tumors can be primary (from brain tissue) or secondary (from other sites, eg breast cancer). These typically present with headaches, weakness, and seizures. Head CT scans can be done without or with IV contrast to detect tumors.

Bleeding - Hemorrhage, aka bleeding, in the brain can be from trauma, ruptured aneurysms or tumors that bleed. CT scans are very sensitive to recent bleeds (especially within a few hours).

Stroke - Also known as a "brain attack", stroke refers to a blocked artery that deprives a part of the brain of blood (and therefore oxygen). This part of the brain loses it function and patients present with weakness, slurred speech, difficulty walking and on occasion, headaches. Head CT scans are a good first test to detect a stroke or determine if the symptoms are caused by another factor such as a bleed or a tumor.

An CT scan of the brain will evaluate:

Sinuses

A CT scan of the brain will include parts of the sinuses. Though not used to primarily look for sinus disease, the brain CT can pick up thickening of the sinus tissue (mucosa) or fluid in the sinuses.

Orbits

Brain CT scans can include parts of the orbits. It can pick up injury to the orbit and  diseases of the orbits such as large tumors, bleeds, inflammation, etc.

Bones

Brain matter

The white and gray matter of the brain are well seen. CT can detect tumors, infection, bleeds, stroke and congenital defects. Part of the pituitary gland, optic nerves and upper brainstem are also evaluated. A "routine" head CT is done without contrast.

Ventricles

These are the fluid filled structures inside the brain that help circulate cerberospinal fluid. Tumors and bleeds can extend into these structures and cause blockage which can lead to headaches, confusion and problems with walking for example. 

Your Brain CT Scan

A brain CT scan generally takes about 5 minutes or so to complete. If you are going for one remember to remove hair pins, piercings, earrings and necklaces as these metallic objects can interfere with the scan. Most scans are done without IV contrast. But if your doctor is looking for a tumor or infection this may be done with contrast.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an CT scan of the brain, you can use our website to look up CT scan costs and then purchase with your credit card.

Have you had a Brain CT scan? What was it like? Please leave your comments below.

CT scans are frequently used to evaluate the chest. A chest CT scan is frequently ordered to look at the lungs, heart and nearby tissues. It may be ordered after a chest x-ray shows a lung nodule or to evaluate pneumonia and other lung diseases such as emphysema. Some chest CT scans are tailored to look for heart disease, aneurysms of the aorta or pulmonary emboli. Chest CT scans are also used to look for the spread or recurrence of cancer.

If you've been in an accident, a chest CT scan can detect a pneumothorax (air leak), fractures of the bones of the chest or bleeding.

A CT scan of the chest will evaluate:

Lungs

A chest CT scan will detect pneumonia, emphysema, lung scarring, pleural effusion (fluid on the lungs), pneumothorax (air leak), and lung cancer.

Mediastinum

The mediastinum refers to the part of the chest that contains your heart, vessels and the esophagus.  The chest CT will detect lymph nodes, tumors in the chest, heart disease, pericardial effusion (fluid around the heart), aneurysms of the aorta and pulmonary emboli (these cause sudden shortness of breath). It can also detect tumors or inflammation of the esophagus.

Bones

Your chest is protected by your ribs, sternum and the spine. A chest CT scan can detect fractures of these bones, tumors, infection or degenerative changes.

Other structures

A chest CT scan also includes parts of the upper abdomen and can pick up abnormalities of the liver, spleen and stomach.

Your Chest CT Scan

A chest CT generally takes about 5 minutes or so to complete.  Many chest CT scans are done with IV contrast.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured use our website to look up Chest CT scan costs, find a certified imaging center and buy your test with a credit card.

Have you had a Chest CT scan? What was it like? Please leave your comments below.

MRA stands for Magnetic Resonance Angiography. It is an MRI technique that specifically evaluates vessels such as arteries. Renal artery MRAs evaluate the vessels that supply blood to the kidneys to look for narrowing and blockage of the vessels, evaluate a suspected aneurysm, or look at the the blood supply of a kidney tumor.

(FYI: "renal" is another word for kidney).

Renal MRAs are typically ordered for the evaluation of hypertension and kidney failure that can be caused by blockages and narrowing of the arteries. If a kidney receives less blood flow it may "act" as if there is not enough blood in the body and release hormones that try to raise the blood pressure. If one or both kidneys has low flow, over time the kidney tissue becomes damaged and is unable to function leading to renal failure.

Renal MRAs can diagnose:

Plaque - Renal MRAs can detect plaque deposits that overtime can narrow the vessel leading to reduced blood flow to the kidneys. Some plaque can abruptly "tear" off sending bits of plaque into the kidneys, blocking vessels and causing a "stroke" of the kidneys. This can lead to kidney scarring.

Dissection - This refers to a tear in the wall of the vessel. Think of it as a tear of the inner lining of the sleeve of a jacket. If you filled the inner lining of your jacket with down it would block the real opening for your arm.  In the artery the blood goes into the opening of the tear of the dissection, expands the false channel, potentially blocking the flow of blood to the kidney and resulting in low flow to the kidney and damage to the tissue.

Aneurysms and Vascular Tumors - Aneurysms are ballooning of the vessels that can either disturb normal blood flow, press on nearby tissue or rupture. Renal vascular tumors may be picked as the vessels that feed them are large enough to be seen on the MRA.

An MRA of the renal arteries will evaluate:

Renal arteries

Each kidney has between 1 to 2 arteries that come off the sides of the abdominal aorta (see the picture to the right). These short and relatively small vessels can be narrowed by plaque, become inflamed or be affected by dissections and aneurysms.

Abdominal Aorta

The abdominal aorta is the main feeding artery for your body below your diaphragm. A renal MRA will include this vessel and can detect major abnormalities like aneurysms, dissection, plaque and blockages.

Abdominal Aorta branch arteries

In addition to seeing the renal arteries, the MRA will also see the other branch vessels which include the celiac artery, superior mesenteric artery and inferior mesenteric artery among others. These vessels supply other organs including the liver, gallbladder, pancreas, spleen, adrenals, stomach, etc.

Your Renal artery MRA Scan

A Renal artery MRA generally takes about 15-30 minutes or so to complete. If you are going for one, wear loose comfortable clothing and remember to remove all metal (jewelry, phones, rings, etc) before going into the MRI scan room.  This test is occasionally done with IV MRI contrast.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an MRA scan of the renal arteries, you can use our website to look up MRA scan costs and then purchase with your credit card.

Have you had a Renal MRA scan? What was it like? Please leave your comments below.

MRI scans are frequently used to evaluate the internal structures of the ankle (you can read more about MRI here). A variety of trends have increased the use of MRI in evaluating our joints - more sports activity, increase in obesity rates, diabetes, and we've remained much more active into our later years than previous generations.

If you've injured your ankle or have ankle pain, your doctor will probably first order an x-ray. After an x-ray, an MRI may be needed to evaluate the tendons, ligaments and bones of the ankle. On your doctor's order for the MRI you might see:

"r/o stress fracture" - this refers to a "hairline" fracture of a bone that is not seen on an x-ray.

"r/o ligament injury"- there are many tendons and ligaments which pass through the ankle area and can be injured or degenerate.

"r/o osteochondral defect" - this is a defect of the bone and cartilage that can cause chronic pain.

(FYI - "r/o" is short for "rule out")

An MRI of the ankle will evaluate:

Bones

An ankle MRI will include parts of the lower tibia, lower fibula and the ankle bones which include the talus, calcaneus and some of the forefooot bones. An ankle MRI can detect bone bruises, fractures, cysts, tumors, infection and dislocations. An MRI can also determine the extent of arthritis and assist in pre-operative planning.

Cartilage

Ankle MRIs are very good at looking at the cartilage. MRI can detect cartilage fraying (like frayed edges of jeans), fissuring (cracks, similar to a dry river bed), and defects (the cartilage is missing). Damaged cartilage can lead to chronic pain and arthritis.

Tendons and Ligaments

Your ankle has a complex set of tendons and ligaments that an MRI can evaluate. The Achilles tendon is the large tendon at the back of your ankle. This can develop internal tears and cause pain. Tendons along the sides of your ankle can also develop tears and cause pain and a flattened arch for example. Ligaments like the deltoid ligament help suport your ankle. Any of these tendons and ligaments can be injured and the injury may only be seen on MRI.

Soft Tissues

This refers to the muscles and tissues around your ankle. An ankle MRI scan will show parts of the lower leg and foot muscles. An MRI can detect muscle tears, strains, tumors and infection. It can also detect fluid collections in the joints.

Your Ankle MRI Scan

An ankle MRI generally takes about 30 minutes or so to complete. If you are going for one, wear loose comfortable clothing and remember to remove all metal (jewelry, phones, rings, etc) before going into the MRI scan room. If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an MRI scan of the ankle, you can use our website. Click here to see MRI scan costs.

Have you had an Ankle MRI scan? What was it like? Please leave your comments below.

X-rays are frequently used to evalaute the bones of the knee (you can read more about X-rays here). If you've injured your knee or have chronic knee pain, your doctor will probably order an X-ray.  On your doctor's order for the X-ray you might see:

"r/o fracture" - a fracture is a break in the bone.

"r/o DJD"- DJD short for degnerative joint disease. Your doctor is looking for joint narrowing, bone spurs and fluid on the knee.

(FYI - "r/o" is short for "rule out")

An X-ray of the knee will evaluate:

Bones

A knee X-ray will include parts of the lower femur, upper tibia, upper fibula and the patella. The knee X-ray can detect bone fractures, cysts, tumors, infection and dislocations. An X-ray can also determine the extent of arthritis and assist in pre-operative planning. X-rays are frequently done to evaluate knee replacement hardware as well.

Soft Tissues

This refers to the muscles and tissues around your knee. A knee X-ray scan will show parts of the thigh muscles and muscles of the upper calf area. The X-ray can see foreign bodies (for example metal) that are in the skin or large tumors and joint effusions.

Your Knee X-ray

A knee X-ray generally takes about 5 to 10 minutes or so to complete. If you are going for one, wear loose comfortable pants or shorts. If you're uninsured expect to pay between $75-$250 for an x-ray. Prices vary depending on location and number of images taken.

Have you had a Knee Xray? What was it like? Please leave your comments below.