Urinary Tract Infection: Causes, Symptoms & Treatment


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Urinary Tract Infection: Causes, Symptoms & Treatment

A urinary tract infection, or UTI, is a bacterial infection of any part of the urinary tract, which includes the bladder, kidneys, ureters (tubes that connect the kidneys to the bladder) and the urethra (the tube that allows the bladder to be emptied). Infections of the bladder or the urethra are the most common.

In the United States, about 8.1 million people visit the doctor due to a urinary tract infection each year,according to the American Urological Association.

Most often, a UTI occurs because bacteria enter the urethra and travel up to the bladder, where they multiply.

Bladder infections are typically caused by Escherichia coli (E. coli) bacteria, which are common bacteria in the human gut, according to the Mayo Clinic. Infections of the urethra can be caused by E. coli, or by sexually transmitted infections, such as herpes or chlamydia.

Bacteria in the bladder can also move up to the kidneys and cause a kidney infection (known as pyelonephritis), which can cause permanent kidney damage. An untreated UTI in the bladder can lead to such an infection.

According to the National Institutes of Health, symptoms of a UTI include:

  • A strong and frequent urge to urinate often, even after you’ve just emptied your bladder
  • Pain or burning while urinating
  • Cloudy or bloody urine
  • Pain in the lower abdomen or back (pelvic pain for women, rectal pain for men)

Signs of a kidney infection may include:

  • Chills or night sweats
  • Fever
  • Pain in the side, back or groin area
  • Flushed or reddened skin
  • Nausea and vomiting

In older adults, mental changes or confusion are often the only signs of a UTI, according to the NIH. For this reason, UTIs in the elderly are often missed, said Dr. Ketul Shah, a urologist from The Ohio State University Wexner Medical Center. If an elderly patient comes to the hospital because they are confused and not feeling well, it’s important that doctors rule out common problems (such as UTI) first, before they start treatment for other, less common problems, Shah said.

Women are more likely than men to get a UTI. One reason for this is that women have a shorter urethra than men do, and it is closer to the anus. Both of these reasons explain why bacteria can reach the bladder more easily in women. Sexual activity also increases a woman’s risk of UTI.

The drop in estrogen levels that women experience after menopause also can make the urinary tract more vulnerable to infection, according to the Mayo Clinic.

Blockages of the urinary tract, such as those caused by a kidney stone or an enlarged prostate, can block the flow of urine and increase the risk of UTI.

People with an impaired immune system, such as those with diabetes and other conditions, have a decreased ability to fight off infections, which can increase the risk of UTI.

People who have a urinary catheter are also at increased risk for UTI.

People who hold their urine for long periods of time may also be at risk for a urinary tract infection, Shah said. Urine has a high amount of glucose and proteins, which can allow bacteria to grow, Shah said. “The bacteria has more time to multiply” when people hold their urine, Shah said.

To diagnose a UTI, doctors collect a urine sample to look for bacteria or byproducts from bacteria, such as red and white blood cells, Shah said. Doctors can also perform a urine culture — in which the urine sample is cultured in a lab to see if it grows bacteria — which takes about 24 to 48 hours, Shah said. The latter test can help doctors determine which antibiotics are most suitable to treat the infection, Shah said.

Usually, a urinary tract infection is treated with antibiotics to prevent the infection from spreading to the kidneys. Symptoms of a bladder infection usually go away within one to two days after starting antibiotics.

Patients who are prescribed antibiotics should take them exactly as it was recommended by your healthcare provider, and they should not stop taking the drug until your provider says it is safe to do so, according to theCenters for Disease Control and Prevention.

A recent opinion article published in The BMJ (British Medical Journal) hasquestioned the long-held advice of finishing a course of antibiotics even if a person is feeling better to prevent the relapse of an infection. The article suggests this advice might be contributing to an increase in antibiotic-resistant bacteria.

Women with recurrent UTIs — meaning having more than two or three UTIs in a year — may be told to take antibiotics after sexual activity to prevent infection. Longer courses of antibiotics, or stronger doses, also may be required for people with recurrent infections.

A more severe infection of the kidneys may require hospital treatment. Hospital treatment involves injecting fluids and antibiotics through a vein. Some people may need surgery if the infection is caused by a problem with the structure of the urinary tract, according to the NIH.

UTIs in children can be serious because the infection can sometimes affect the growth of the kidneys, Shah said. Children who have had a UTI may require further testing to make sure their urine is not traveling back up into the kidneys, Shah said.

Ways to help prevent UTIs include drinking plenty of water to dilute urine and flush out bacteria, and urinating after intercourse. Women who’ve gone through menopause may use estrogen cream around the vagina to reduce the risk of infections, the NIH says.

A 2012 review suggested that cranberries may help prevent UTIs, according to the University of Maryland Medical Center. Cranberries may interfere with the way bacteria attach to urinary tract cells.

The idea that cranberry juice can prevent UTIs is controversial, because although some studies show a benefit, other studies find little evidence of a benefit, or suggest that the benefit is a placebo effect, Shah said. Still, because cranberry juice is safe and not very expensive, Shah said he does recommend it as a way to help prevent UTI.

Additional reporting by Cari Nierenberg, Live Science Contributor.

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience,Facebook & Google+.

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How a CT Scan of an Olive Led to Man’s Diagnosis of Crohn’s Disease


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How a CT Scan of an Olive Led to Man’s Diagnosis of Crohn’s Disease

The image on the left shows a scan of the man’s abdomen. The blue and white arrow points to the olive in the man’s small intestine, which appears as a small white oval. The image on the right shows an olive and its pit; the inset image is a scan of a single black olive, which is similar in appearance to the olive in the man’s gut.

Credit: The BMJ

When a 24-year-old man in Belgium went to the hospital because he had belly pain, doctors found an olive stuck in his small intestine — and soon after, diagnosed him with Crohn’s disease.

The man had sudden and severe abdominal pain for two days before he went to the doctor, according to a report of the man’s case, published Aug. 9 in the journal BMJ Case Reports. The incident took place about six months ago.

The doctors performed a CT scan of the man’s abdomen to see if they could spot the reason for his pain. They found that a portion of the wall of the small intestine was thickened, and within that thickened tissue, they discovered an odd-looking spot that turned out to be a black olive. [Here’s a Giant List of the Strangest Medical Cases We’ve Covered]

Olives were one of the man’s favorite foods, and he had accidentally swallowed the olive whole, pit included, said lead author Dr. Halil Yildiz, an internal-medicine physician at University Hospital Saint-Luc in Belgium who treated the man.

To confirm that the spot on the scan was an olive, however, the doctors did something that had never been done: They performed another CT scan — a scan of a single fresh olive. “This is the first time that CT acquisition of a fresh olive has been compared with patient images,” the doctors wrote in the report.

The olive scan did its part: It confirmed that the small fruit really was lodged in the man’s bowels, Yildiz told Live Science.

No surgery was required to remove the olive; instead, the man was given steroids to reduce the inflammation in his gut, and eventually, the olive passed out of his body in his feces, Yildiz said.

In most cases when a person swallows a “foreign body” — in other words, something they shouldn’t have swallowed — it passes safely through the gastrointestinal tract and out the other end, according to the report. Occasionally, something may get stuck, but “this complication is very rare with olives,” the authors wrote.

Indeed, it turns out that there was another factor at play that made it much more likely for the olive to get stuck in the man’s gut, Yildiz said: He had a type of inflammatory bowel disease called Crohn’s disease.

But neither the man nor the doctors knew that the patient had Crohn’s disease until after the olive had passed out of his body and the patient returned for a follow-up colonoscopy, according to the report. It was during that exam that the doctors diagnosed the man with Crohn’s disease.

“If there was no bowel disease,” the olive wouldn’t have caused a problem, Yildiz said. “Crohn’s disease [made] the obstruction more likely.”

Originally published on Live Science.

Woman Born Without a Vagina Speaks Out About Rare Condition


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Woman Born Without a Vagina Speaks Out About Rare Condition

Kaylee Moats, 22, was born with a rare condition that affects the female reproductive organs.

Credit: YouTube Screengrab/Barcroft TV

A woman in Arizona who was born without a vagina — the result of a rare condition — is speaking out about her condition, and raising money for a surgery to treat it.

Kaylee Moats, who is 22, first learned she did not have a vagina when she was 18 and had never had a menstrual period, according to a video about Moats’ case, made by Barcroft TV. An ultrasound performed at her doctor’s office revealed that she did not have a uterus, cervix or vagina.

“It makes me feel less of a woman,” Moats said in the video. “I’m still trying to accept myself, accept what I have and not dwell on it.”

Moats was diagnosed with Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, a condition that affects about 1 in every 4,500 newborn girls, according to the National Institutes of Health. It happens when, during embryonic development, the female reproductive organs (including the uterus, cervix and vagina) do not develop properly. As a result, the uterus and vagina may be underdeveloped or absent entirely, the NIH said. [7 Facts Women (And Men) Should Know About the Vagina]

People with this condition are genetically female (meaning they have two Xchromosomes), and have normally functioning ovaries. They also have normal external genitalia, and so the condition is usually discovered only when women do not get their period, as was the case for Moats.

In some cases, the condition can be treated without surgery, by using vaginal “dilators” to create a vagina or enlarge an existing vagina, according to the National Organization for Rare Diseases (NORD). Vaginal dilators are specially designed plastic tubes that can be used to stretch and widen the small amount of vaginal tissue that is typically present (sometimes referred to as a vaginal “dimple”), according to NORD.

The condition can also be treated with surgery to create a vagina, which is called a vaginoplasty.

Researchers have created vaginas in a lab dish, by taking a patient’s own cells and growing them on a scaffold to form a vaginal shape. In 2014, researchers announced they had implanted these vaginas in four teenage girls, and the treatment was successful. However, the treatment is still experimental.

For Moats, the next step is to have reconstructive surgery to create a vagina, she said. However, the surgery costs $15,000 and is not covered by her insurance.

“They consider it a cosmetic surgery or a gender reassignment,” Moats said. “It’s very hurtful” to not have this surgery covered by insurance, she said.

Moats’ sister, Amanda Moats, started a GoFundMe page to raise money for the surgery. As of today (Aug. 17), she had raised $16,997, exceeding the goal of $15,000.

“Getting the surgery will help me feel normal and have all the right body parts as any other girl,” Moats told Barcoft TV.

Moats has a boyfriend, Robbie Limmer, whom she met as a senior in college. Moats said Limmer has been supportive of her, and does not focus on the sexual side of their relationship.

“Knowing that he accepts me for who I am, and doesn’t see me as less of a person or less of a woman, makes me feel loved,” Moats said.

Moats hopes to have children someday. Because she has functioning ovaries, she can, in theory, use a gestational surrogate to carry her child.

Original article on Live Science.

Kidney Stones: Causes, Symptoms & Treatment


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Kidney Stones: Causes, Symptoms & Treatment

Kidney stones are hard masses that form in the kidneys when there is not enough liquid to dilute waste chemicals in the urine.

Credit: remik44992 | Shutterstock

A kidney stone is a hard mass that forms in one or both kidneys from minerals in the urine, and if large enough, can cause severe pain. In the United States, kidney stones send more than 500,000 people to the emergency room each year, according to the National Kidney Foundation.

Kidney stones form when there is not enough liquid in the urine to dilute out waste chemicals, such ascalcium, oxalate and phosphorous. These waste chemicals become concentrated, and crystals begin to form, according to the National Kidney Foundation.

The most common type of kidney stones are calcium oxalate stones.

Kidney stones can vary in size, with some as small as a grain of sand, and others as large as a pea or even a golf ball, according to the National Institutes of Health (NIH).

Small stones may pass down the urinary tract and be excreted without causing symptoms. Larger stones may get stuck in the urinary tract and block the flow of urine, which can cause severe pain or bleeding, the NIH says.

People with kidney stones often seek medical care because they have severe pain in their flank (the area between the mid-back and the ribs) on one side of the body, and this pain can extend to the lower abdomen, said Dr. Michael F. Michelis, director of the division of nephrology at Lenox Hill Hospital in New York. “Stone pain is very profound,” Michelis said.

Other symptoms of kidney stones can include pain while urinating, blood in the urine, and nausea and vomiting, according to the NIH. People who think they have a kidney stone, or who have serious symptoms such as extreme pain that won’t go away, fever, chills and vomiting, should see their doctor, the NIH says.

Men are more likely to develop kidney stones than women. People are also at increased risk for kidney stones if they’ve had a stone in the past, or a member of their family has had a stone.

Other risk factors include not drinking enough water, eating a diet high in protein, sodium and sugar, being obese, or undergoing gastric bypass surgery, according to the Mayo Clinic.

The most common time to develop kidney stones is between ages 20 and 60, according to information from The Johns Hopkins Hospital.

Kidney stones broken into smaller pieces after lithotripsy.
Kidney stones broken into smaller pieces after lithotripsy.

Credit: Atelier_A Shutterstock

Kidney stones can be diagnosed from a patient’s symptoms and a CT scan (that combines X-rays to create a 3D image), which is usually performed in the emergency room, Michelis said.

Small kidney stones don’t usually need treatment, but an individual may need to take pain medication, according to the NIH. Patients with kidney stones should also drink lots of fluids, which can help the stone to pass. Most kidney stones do not require invasive treatment, according to the Mayo Clinic.

Large kidney stones, or stones blocking the urinary tract, may need other treatments. One treatment is called shock wave lithotripsy, during which a doctor uses a machine that produces strong vibrations known as shock waves to break the stone into small pieces so it can pass through the urinary tract.

Another treatment, called ureteroscopy, uses a special tool called a ureteroscope to view the kidney stone in the ureter — the tube that connects the kidneys to the bladder. A doctor can then remove the stone or use laser energy to break it up.

Very large stones may need surgery to remove them, Michelis said.

Many issues of kidney stones “can be avoided by moderation of the diet and a high fluid intake,” Michelis said. The NIH recommends drinking about 2 to 3 liters, or 2 to 3 quarts, of fluid each day.

Determining the type of stone a person had — by catching the stone as it passes and having it analyzed by a lab — can help doctors understand what caused the stone, and make recommendations to prevent the condition. If a patient is not able to catch the kidney stone, doctors can still perform urine testing (by asking a patient to collect his or her urine for a 24-hour period), and take a diet history, to determine what might be causing the stone, Michelis said.

For people who’ve had stones made of calcium oxalate, doctors may recommend that they avoid foods high in oxalate, such as spinach, rhubarb, nuts and wheat bran, the NIH says.

To prevent stones made of uric acid, doctors may ask patients to reduce their protein intake, because protein is associated with the formation of uric acid in the body, Michelis said.

Reducing salt intake may also lower a person’s risk of several types of kidney stones, including calcium stones. Eating too much sodium can increase the amount of calcium in the urine, Michelis said. Patients should also eat the recommended daily amount of calcium, but not an excessive amount, Michelis said.

Some drugs can help prevent kidney stones, but these drugs are typically used only if a change in diet is not effective, Michelis said. These include diuretic drugs to prevent calcium stones and drugs to reduce the production of uric acid to prevent uric acid stones, Michelis said. Some drugs can also reduce the acidity of the urine, Michelis said, because too much acid in the urine is a risk factor for stones made of uric acid.

This article is for informational purposes only, and is not meant to offer medical advice. 

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience,FacebookGoogle+.

Additional reporting by Cari Nierenberg, Live Science Contributor

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Opioid Crisis Is a ‘National Emergency’: What Happens Now?


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Opioid Crisis Is a ‘National Emergency’: What Happens Now?

Credit: Steve Heap/Shutterstock

President Donald Trump has declared the opioid epidemic a “national emergency,” but what happens now, and could this declaration really help address the crisis?

On Thursday (Aug. 10), Trump told reporters that the opioid epidemic is a national emergency. “We’re going to spend a lot of time, a lot of effort and a lot of money on the opioid crisis,” he said.

In a statement, the White House said Trump had ” instructed his administration to use all appropriate emergency and other authorities to respond to the crisis caused by the opioid epidemic.”

The declaration follows a recommendation from Trump’s commission on the opioid crisis, which urged the president to declare a national emergency over the issue.

Experts said that the declaration was encouraging, but it’s uncertain how big of an impact it will have on the opioid crisis.

“To me it’s an important step, [but] there need to be many steps after this,” said Dr. Bradley Stein, a psychiatrist and senior physician policy researcher at the RAND Corporation, a nonprofit research organization. Stein noted that the opioid epidemic has evolved over decades and is not something that can be solved overnight. “There’s not really a silver bullet here — there’s not really a single policy that’s going to solve this. We as a country need to attack it at multiple fronts,” Stein told Live Science. [America’s Opioid-Use Epidemic: 5 Startling Facts]

Since 1999, the number of people who have died from overdoses of eitherprescription opioids or heroin has nearly quadrupled in the United States, according to the Centers for Disease Control and Prevention (CDC). Currently, about 1,000 Americans die per week from drug overdose (not just from opioids), according to a statement from Trump’s opioid commission. And in 2015, opioids (prescription and heroin) killed more than 33,000 people, more than in any other year on record, according to the CDC.

Declaring a national emergency does bring attention to the issue, Stein said. “It certainly sends a signal about the level of federal commitment to addressing this crisis,” he said.

The declaration could also open up more resources for addressing the epidemic. But exactly which resources become available will depend upon which path the administration takes for this emergency declaration.

The administration can declare an emergency in two ways: through the Stafford Act or through the Public Health Service Act, and each of these laws could help in different ways, Stein said.

A declaration through the Stafford Act would trigger the same type of aid that is available to areas after a natural disaster. This means money from the federal disaster-relief fund could be used to bolster efforts to treat opioid addiction or prevent misuse of these drugs, Stein said.

However, money from the disaster-relief fund would be limited; in total, there is currently $1.4 billion available through the fund for aiding disasters over the rest of the year. This could be enough to get some efforts started in the short term, but ultimately, a more long-term investment would be needed, Stein said.

A declaration through the Public Health Service Act could help increase access to opioid treatment in underserved areas by making it easier for doctors to practice medicine in different states, Stein said. Rather than having to go through a lengthy process to obtain a medical license in a different state, a doctor moving to an underserved area would have some of these requirements waived.

A particularly promising benefit of the “national emergency” declaration (regardless of which act is invoked) could be to allow states more flexibility in using funds from Medicaid for treating opioid disorders. For example, currently, Medicaid can’t be used to reimburse treatments at psychiatric facilities, where some people with opioid disorder receive treatment, Stein said. But this barrier could be waived using either the Stafford Act or the Public Health Service Act.

“That would open up more resources [and] more facilities to be able to treat opioid disorders,” Stein said.

As for next steps, Stein said there should be a focus on not only increasing access to treatment for opioid disorders, but also making sure the treatment is of high quality. In addition, more efforts are needed to reduce access to these powerful drugs, through both prescriptions and illegal markets, he said.

“Neither of those things happen[s] overnight … but we can make progress” over the long term, Stein said.

Finally, when new policies are put into place to address the opioid epidemic, it’s important to revisit these policies from time to time to make sure they are working and not having unintended consequences, Stein said. For example, in recent years, the Food and Drug Administration approved newer formulations of opioids that were harder to abuse, but as a result, some people shifted to using heroin instead, Stein said.

“We can’t put things in place and walk away,” Stein said. “We may need to modify some of our responses” to the epidemic.

Original article on Live Science.

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Can a Solar Eclipse Really Blind You?


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Can a Solar Eclipse Really Blind You?

A tourist watches a solar eclipse through eclipse-viewing glasses in 2009 in Varanasi, India.

Credit: Pete Niesen / Shutterstock.com

People across the United States will have the chance to see a total solar eclipse on Aug. 21, the first time the spectacle was viewable from the continental U.S. since 1979. While it may be tempting to brush off warnings about looking up at this eclipse bare-eyed, don’t: The light of an eclipse really can damage your eyes — though warnings of total blindness may be overstated.

The condition is called solar retinopathy, and it occurs when bright light from the sun floods the retina on the back of the eyeball. The retina is home to the light-sensing cells that make vision possible. When they’re over-stimulated by sunlight, they release a flood of communication chemicals that can damage the retina. This damage is often painless, so people don’t realize what they’re doing to their vision.

Solar retinopathy can be caused by staring at the sun (regardless of its phase), but few people can stand to look directly at our nearest star for very long without pain. It does happen occasionally — medical journals record cases in which people high on drugs have stared at the sun for long periods of time, causing serious damage. Adherents of sun-worshipping religious sects are also victims. In 1988, for example, Italian ophthalmologists treated 66 people for solar retinopathy after a sun-staring ritual. [Gallery: Our Amazing Sun]

But during a solar eclipse, more people are at risk. With the sun almost covered, it’s comfortable to stare, and protective reflexes like blinking and pupil contraction are a lot less likely to kick in than on a normal day. Even pets are vulnerable to eye damage from looking at an eclipse, though they don’t tend to look directly at the sun. Even so, if they’re with you during your eclipse outing, your furry friends should wear protective glasses as well.

Early observers of astronomy sometimes found out about solar retinopathy the hard way. Thomas Harriot, who observed sunspots in 1610 but did not publish his discovery, wrote in 1612 that after viewing the sun his “sight was dim for an hour.” Oxford astronomer John Greaves was once quoted as saying that after sun observations, he saw afterimages that looked like a flock of crows in his vision. In the most famous case of all, Isaac Newton tried looking at the sun in a mirror, essentially blinding himself for three days and experiencing afterimages for months.

Scientists don’t have a good bead on the prevalence of eye damage after a solar eclipse. In one study, conducted in 1999 after a solar eclipse visible in Europe, 45 patients with possible solar retinopathy showed up at an eye clinic in Leicester in the United Kingdom after viewing the eclipse. Forty were confirmed to have some sort of damage or symptoms of damage; five of those had visible changes in their retina.

Twenty of the patients reported eye pain, while another 20 reported problems with vision. Of the latter group, 12 reported that their sight had returned to normal seven months later, but four could still see the ghosts of the damage in their visual field, such as a crescent-shaped spot visible in dim light. [If the Sun Is 93 Million Miles Away, Why Can’t We Look Directly at It?]

“Our series demonstrates that, contrary to popular belief, the majority of people with eclipse retinopathy are not totally blinded,” the researchers wrote in 2001 in the journal The Lancet. However, they warned, earlier post-eclipse studies had turned up more severe problems in patients, suggesting that widespread media warnings not to look at the eclipsing sun may have prevented more damage during recent eclipses.

Research also suggests that while a lot of the damage may heal, some may be permanent. One 1995 study followed 58 patients who sustained eye damage after viewing a 1976 eclipse in Turkey. Healing occurred during the first month after the eclipse, the researchers reported in the journal Graefe’s Archive for Clinical and Experimental Ophthalmology, but by 18 months, whatever damage remained was permanent up to 15 years later.

So, while it might be tough to go totally blind by looking at an eclipse, doing so without proper protection could leave a long-lasting stain on your vision. The only safe way to view an eclipse, according to NASA, is to use specially designed sun filters, often available at telescope stores, or to wear No. 14 welder’s glasses, available at welding specialty stores. Pinhole viewers — essentially a hole in a piece of cardboard or paper — can also be used to view the eclipse indirectly by casting a shadow of the sun on the ground or on a screen. [How to Build a Solar Eclipse Viewer: Photos]

REMEMBER: Looking directly at the sun, even when it is partially covered by the moon, can cause serious eye damage or blindness. NEVER look at a partial solar eclipse without proper eye protection. Our sister site Space.com has a complete guide for how to view an eclipse safely.

Editor’s Note: This article was first published in 2012 and updated for the Great American Eclipse in 2017.

Originally published on Live Science.

What is an MRI (Magnetic Resonance Imaging)?


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What is an MRI (Magnetic Resonance Imaging)?

MRIs are medical imaging systems used to diagnose health conditions.

Credit: MRI scan via Shutterstock

Magnetic resonance imaging (MRI), also known as nuclear magnetic resonance imaging, is a scanning technique for creating detailed images of the human body.

The scan uses a strong magnetic field and radio waves to generate images of parts of the body that can’t be seen as well with X-rays, CT scans or ultrasound. For example, it can help doctors to see inside joints, cartilage, ligaments, muscles and tendons, which makes it helpful for detecting various sports injuries.

MRI is also used to examine internal body structures and diagnose a variety of disorders, such as strokes, tumors, aneurysms, spinal cord injuries, multiple sclerosis and eye or inner ear problems, according to the Mayo Clinic. It is also widely used in research to measure brain structure and function, among other things.

“What makes MRI so powerful is, you have really exquisite soft tissue, and anatomic, detail,” said Dr. Christopher Filippi, a diagnostic radiologist at North Shore University Hospital, Manhasset, New York. The biggest benefit of MRI compared with other imaging techniques (such as CT scans and x-rays) is, there’s no risk of being exposed to radiation, Filippi told Live Science.

During an MRI, a person will be asked to lie on a movable table that will slide into a doughnut-shaped opening of the machine to scan a specific portion of your body. The machine itself will generate a strong magnetic field around the person and radio waves will be directed at the body, according to the Mayo Clinic.

A person will not feel the magnetic field or radio waves, so the procedure itself is painless. However, there may be a lot of loud thumping or tapping noises during the scan (it may sound like a sledgehammer!), so people are often given headphones to listen to music or earplugs to help block the sound. A technician may also give instructions to you during the test.

Some people may be given a contrast solution by intravenous, a liquid dye that can highlight specific problems that might not show up otherwise on the scan.

Young children as well as people who feel claustrophobic in enclosed places may be given sedating medication to help them relax or fall asleep during the scan because it is important to stay as still as possible to get clear images. Movement can blur the images.

Some hospitals might have an open MRI machine that is open on the sides rather than the tunnel-like tube found in a traditional machine. This may be a helpful alternative for people who feel afraid of confined spaces.

The scan itself may take 30 to 60 minutes, on average, according to the American Academy of Family Physicians.

A radiologist will look at the images and send a report to your doctor with your test results.

The human body is mostly water. Water molecules (H2O) contain hydrogen nuclei (protons), which become aligned in a magnetic field. An MRI scanner applies a very strong magnetic field (about 0.2 to 3 teslas, or roughly a thousand times the strength of a typical fridge magnet), which aligns the proton “spins.”

The scanner also produces a radio frequency current that creates a varying magnetic field. The protons absorb the energy from the magnetic field and flip their spins. When the field is turned off, the protons gradually return to their normal spin, a process called precession. The return process produces a radio signal that can be measured by receivers in the scanner and made into an image, Filippi explained.

An MRI scan reveals the gross anatomical structure of the human brain.

An MRI scan reveals the gross anatomical structure of the human brain.

Credit: Courtesy FONAR Corporation

Protons in different body tissues return to their normal spins at different rates, so the scanner can distinguish among various types of tissue. The scanner settings can be adjusted to produce contrasts between different body tissues. Additional magnetic fields are used to produce 3-dimensional images that may be viewed from different angles. There are many forms of MRI, but diffusion MRI and functional MRI (fMRI) are two of the most common.

This form of MRI measures how water molecules diffuse through body tissues. Certain disease processes — such as a stroke or tumor — can restrict this diffusion, so this method is often used to diagnose them, Filippi said. Diffusion MRI has only been around for about 15 to 20 years, he added.

In addition to structural imaging, MRI can also be used to visualize functional activity in the brain. Functional MRI, or fMRI, measures changes in blood flow to different parts of the brain.

It is used to observe brain structures and to determine which parts of the brain are handling critical functions. Functional MRI may also be used to evaluate damage from a head injury or Alzheimer’s disease. fMRI has been especially useful in neuroscience — “It has really revolutionized how we study the brain,” Filippi told Live Science.

Unlike other imaging forms like X-rays or CT scans, MRI doesn’t use ionizing radiation. MRI is increasingly being used to image fetuses during pregnancy, and no adverse effects on the fetus have been demonstrated, Filippi said.

Still, the procedure can have risks, and medical societies don’t recommend using MRI as the first stage of diagnosis.

Because MRI uses strong magnets, any kind of metal implant, such as a pacemaker, artificial joints, artificial heart valves, cochlear implants or metal plates, screws or rods, pose a hazard. The implant can move or heat up in the magnetic field.

Several patients with pacemakers who underwent MRI scans have died, patients should always be asked about any implants before getting scanned. Many implants today are “MR-safe,” however, Filippi said.

The constant flipping of magnetic fields can produce loud clicking or beeping noises, so ear protection is necessary during the scan.

Cari Nierenberg contributed to this article.