- For Patients

Patient-Friendly Summaries of ACR Appropriateness Criteria

The ACR Appropriateness Criteria (AC) are the largest body of evidence-based guidelines in medical imaging. For over 20 years, the AC have aided physicians and other providers with resources for appropriate utilization of medical imaging. As patients become increasingly involved in their medical care, they have begun to read and interpret the AC. The summaries below follow the titles of individual AC and are designed to be easily understood by patients and the lay public. By making the AC understandable to patients, we hope to improve communication between patients and their physicians about imaging exams.

Acute Chest Pain – Suspected Pulmonary Embolism

Imaging tests are not necessary for many patients suspected of having a blood clot in the lungs known as a pulmonary embolism (PE). For medically stable patients, the risk of a PE should be assessed first by asking standard questions about the patient and his or her symptoms. If the answers to the questions result in a low risk score, no further testing is required.

If the answers indicate the possibility of PE, a blood test (d-dimer) to check for a substance released when a blood clot breaks up is recommended. If the test comes back negative, no further testing is required. The d-dimer test should not be used for anybody expected to have blood clots due to other things, such as recent surgery or trauma, or for pregnant women.

If the answers to the standard questions indicate a high risk of PE and the d-dimer test is positive, in most cases a pulmonary CT angiography (CTA)—a CT scan to look at the blood vessels in the lungs—is the next step. For people with symptoms of a blood clot in the lower legs, especially for pregnant women, an ultrasound Doppler of the legs is often the first choice to reduce radiation exposure. Eighty percent of PEs are associated with blood clots in the lower legs. In addition, a chest x-ray may be performed to rule out other causes such as pneumonia or fluid in the lungs. Ventilation and perfusion nuclear medicine scans are sometimes used in place of CTA.

Acute Nonlocalized Abdominal Pain

Stomach pain occurs for various reasons. Imaging may help identify the source of pain. CT with contrast in the vein is the preferred examination for stomach pain with or without a fever. Contrast by mouth can be substituted in the event of poor kidney health or allergy to intravenous (IV) contrast materials. Pain with a fever may indicate infection or an abscess. CT is useful if an abscess is suspected because the doctor can drain the abscess at the same time. MRI may be helpful in distinguishing infected versus noninfected fluid. PET is useful if previous CT imaging did not find the source of the pain.

CT with contrast is the preferred scan for stomach pain after surgery. A complementary fluoroscopic study may be useful in evaluating postsurgical leaks. PET is not useful for stomach pain after surgery because it could lead to false-positive results.

CT is appropriate for stomach pain in people with weak immune systems. For patients unable to undergo CT, MRI may be helpful. MR enterography (special MRI with IV and swallowed contrast) can be used for stable patients with a history of inflammatory bowel disease. PET can also be useful if previous CT imaging did not find the source of pain.

Pregnant patients with stomach pain may receive an MRI or an ultrasound to diagnose urinary tract infection, bladder stones, ectopic pregnancy, ovarian torsion, adnexal masses, placental abnormalities, acute cholecystitis, pancreatitis, or inflammatory bowel disease.

Acute Onset Flank Pain – Suspicion of Stone Disease (Urolithiasis)

Kidney stones form from salts in urine and can travel through or block the ureter, the tube that carries urine from the kidney to the bladder. Stones can cause sharp pain on one or both side(s) of the body between the upper belly area and the back, often called flank pain. Flank pain can also be caused by other things such as appendicitis or diverticulitis (inflamed pouches of the bowel).

The best imaging test to identify a kidney stone and possible blockage in the ureter is a CT scan. The CT scan can identify the size and location of the stone, which can predict the likelihood that a stone will pass on its own, with larger stones less likely to do so.

A CT scan with contrast fluid injected intravenously into the blood vessels may be needed to differentiate between a stone and a phlebolith, a calcification in a vein, or to determine other causes of flank or abdominal pain not seen on the initial CT scan.

Other imaging tests like ultrasound (US) and MRI do not use radiation, but both tests can miss smaller stones. For pregnant women, US is the best initial test. For patients with a history of kidney stones, younger patients, or follow-up imaging to see if a stone has moved or passed out of the body, an MRI or a combination of a US and x-ray test may be used to reduce radiation exposure. For more information, see the Kidney and Bladder Stones page.

Adnexal Cyst Follow-Up

An adnexal cyst is a fluid-containing lump in the area of the pelvis around the uterus. This includes the ovaries, fallopian tubes, and surrounding tissues. Simple ovarian cysts frequently form during the normal menstrual cycle and are not considered to be a problem. In addition, ovarian cysts will form in approximately 20% of postmenopausal women.

Adnexal cysts can be categorized as simple or complex depending on their characteristics seen on the ultrasound. Most women with simple adnexal cysts do not need additional imaging tests after an initial transvaginal ultrasound. Ovarian cancer is unlikely to arise from these benign-appearing cysts. However, women experiencing severe pain or worsening symptoms should be re-evaluated.

In women of reproductive age, simple cysts larger than 5 cm may require some form of additional imaging and annual ultrasound imaging follow-up. In postmenopausal women, follow-up is recommended for simple cysts larger than 1 cm in greatest diameter. Additional imaging is also indicated for complex adnexal masses having both fluid and solid parts on ultrasound in both pre- and postmenopausal women. Depending on the size and location of the cyst, transabdominal ultrasound may be used in addition to transvaginal ultrasound for initial evaluation. Color Doppler ultrasound imaging is used to evaluate the solid parts of a complex cyst and to look for blood vessel characteristics that may suggest a cancer is present.

An MRI or a CT scan is recommended when the ultrasound test does not provide enough information to tell whether cancer might be present.

Asymptomatic Patient at Risk for Coronary Artery Disease

There are many imaging tests that can detect the signs of early heart disease in people without any symptoms. Finding heart disease early can help doctors and patients treat it and may prevent future events. These imaging tests are usually not appropriate for patients if they have low risk scores on common heart risk assessment tests like the Framingham risk score or the Systematic Coronary Risk Evaluation.

For low-risk patients who don't have any symptoms but have strong family histories of heart disease, it may be helpful to use CT to determine the coronary artery calcium score (CACS). The CACS is a measure of the calcium buildup on the walls of the arteries around the heart and has been found to be a good indicator of future cardiac events such as heart attacks. For intermediate-risk patients without symptoms, measuring the CACS is usually appropriate because it helps find people who are at higher risk than suggested by their calculated heart risk assessment scores. For more information, see the Cardiac CT for Calcium Scoring page.

There are several imaging tests that may be appropriate for people at high risk who don't have any symptoms. This group includes people with type 2 diabetes, who have a higher risk for heart disease than people without diabetes. These tests include coronary CT angiography, a test that can detect blockages in the arteries around the heart, a heart stress test using MRI, myocardial perfusion imaging (a nuclear medicine test), and echocardiography, a type of ultrasound test of the heart. For more information, see the Cardiac (Heart) Screening page.

Breast Implant Evaluation

Breast implants are made of saline, silicone, or both. Some complications that may occur with implants include the implant bursting (rupture), unexplained swollen lymph nodes in the armpits, or a rare blood cancer called anaplastic large-cell lymphoma that may occur a year after surgery. Patients with implants and without symptoms should continue routine breast screening.

A saline-implant rupture is often diagnosed with a physical examination. If imaging is needed, ultrasound (US) should be used for people under 30. For people 30 to 39 years old, a mammogram, digital breast tomosynthesis (DBT), or US may be used. A mammogram or DBT is the best test for people 40 and older.

MRI without contrast is the best test for diagnosing a silicone-implant rupture, especially when the silicone is still contained by the outer shell (majority of ruptures). Mammography and DBT are not recommended for contained ruptures.

For ruptures outside the shell, in addition to MRI without contrast, US may be used in people under the age of 30. Mammography, DBT, and US may be used for people over 30. For people with prior silicone implants, results may show leftover silicone, not a rupture of new implants, making it important to compare with prior tests.

For unexplained swollen lymph nodes in the armpits, US should be used for patients under the age of 30. For people over 30, mammography, DBT, or US should be used. If the person is suspected to have anaplastic large-cell lymphoma, US is recommended.

Colorectal Cancer Screening

Cancer in the bowel (colon) can be deadly. It is recommended that everyone over the age of 50 have a screening test to identify early-stage colon cancer and precancerous lumps called polyps. Over time, some polyps can develop into cancer. Available screening tests include colonoscopy, CT colonography(also known as virtual colonoscopy), double contrast barium enema, and stool-based tests like the fecal occult blood test, which looks for blood in the stool. Colonoscopy, CT colonography, and double contrast barium enema screen for both polyps and cancer, but stool-based tests screen only for cancer. CT colonography and barium enema expose the patient to ionizing radiation but do not require sedation and carry less risk of accidentally piercing the colon wall compared with colonoscopy. During colonoscopy, the physician can remove polyps and get biopsies of suspicious areas. All of the tests that visualize the colon require pretest bowel cleansing to remove stool from the colon.

People may be at average risk, moderate risk, or high risk for colon cancer based on family history and pre-existing conditions such as ulcerative colitis, Crohn's colitis, or Lynch syndrome. For average- and moderate-risk adults, the appropriate imaging screening test is CT colonography every 5 years. Double contrast barium enema is less commonly used. If suspicious polyps are seen on a CT colonography, a colonoscopy is recommended to get a biopsy. For high-risk adults, imaging screening tests are not recommended because often there is the need to do a biopsy. In these individuals, colonoscopy is the recommended test. The CT colonography test is appropriate after a positive fecal occult blood test or an incomplete colonoscopy.

For more information, see the Colorectal Cancer Screening page.

CT for Adult Minor Head Trauma

A closed head injury results from hitting your head on something. Even a small minor blow to the head can be dangerous and should be evaluated by a doctor for a possible concussion, bleeding on the brain, or skull fracture. Most minor head injuries do not require imaging tests.

A test called the Glasgow Coma Scale helps assess a person's level of consciousness after a minor or mild closed head injury. If the test result is equal to or more than 13, additional guidelines are used to see if an imaging test is recommended. A CT scan without contrast is used if the guidelines say a test is needed to find out the seriousness of the head injury. People with moderate or severe closed head injuries are also recommended to have a CT scan without contrast.

The results of a noncontrast head CT may read as normal despite an existing brain injury. Follow-up imaging tests are recommended for people whose brain injury symptoms are not getting better or are getting worse. CT without contrast is usually the best test for follow-up. MRI is used in cases of chronic (ongoing) suspected traumatic brain injury. If blood vessel injury is suspected then CT angiography or MR angiography is used for arterial injury and CTV or MRV for vein injuries.

CT scans expose people to radiation. MRI tests do not. For more information, see the Head Injury page.


Identifying the type and cause of most headaches can be done with a medical history and a physical examination, without the need for imaging tests. Unnecessary imaging tests can lead to incidental findings—things that are not associated with the reason for the test. This can lead to patients' getting unnecessary treatments and exposure to radiation.

If someone has a new headache with the following complications, he or she might benefit from imaging studies:

  • Recent head or neck injury
  • A sudden or suddenly worsening headache
  • "Thunderclap" headache—a headache that takes seconds or minutes to go from nothing to maximum pain intensity
  • Headache due to the trigeminal nerve (which runs from the face to the brain)—often cluster headaches
  • Positional headache—severe headache on one side of the head that gets worse with certain head positions
  • Headache located on one side, especially in young patients
  • Headache that starts, or gets worse, with coughing, exercise, or sexual activity
  • Headache that may be due to sinus or dental complications
  • Suspected meningitis (infection of the brain lining) or encephalitis (inflammation of the brain)
  • New headache with pain in the temples in older patients
  • Pregnancy
  • Compromised immune systems (e.g., HIV positive)
  • Treatment for cancer
  • Conditions affecting blood clotting
  • Chronic headaches with new symptoms

In most cases, the recommended initial imaging test is MRI with and without intravenous contrast. For some conditions, CT or CT with angiography, either with or without contrast, is recommended. For more information, see the Headache page.

Iliac Artery Occlusive Disease

Iliac artery occlusive disease is blockage of the large arteries supplying blood to the pelvis and legs. Risk factors include diabetes, high blood pressure, and smoking. This blockage is treated differently depending on whether it developed slowly (progressive) or suddenly (acute). The typical symptoms of progressive disease are pain, numbness, and tiredness in the legs when walking and standing, which worsens with time and improves with rest. Typical symptoms of acute disease are sudden leg pain and weak pulse in the groin. The leg may turn cold or blue.

For patients with worsening symptoms, diagnosis is made by physical examination, including blood pressure difference between the leg and arm, blood test to measure fat (lipid) content, and an ultrasound scan of the leg. If the tests show decreased blood flow to the legs, a CT or MRI with intravenous contrast material designed to show blood vessels (CT angiography or MR angiography) is used to find the blood vessel that is blocked and to figure out the size of the blockage.

Acute patients should be imaged with CT angiography. For patients that are allergic to the contrast material, results of the blood pressure testing and ultrasound are used for diagnosis.

Acute patients should be treated immediately with blood thinners. For both acute and progressive patients, CT angiography and MR angiography are used to decide between placing a catheter inside the artery near the blockage and dissolving it or surgically removing or bypassing it. Treatment may include medications that interfere with clot formation to prevent blockage from coming back. For more information, see the Peripheral Artery Disease page.

Imaging of Deep Inferior Epigastric Arteries for Surgical Planning (Breast Reconstruction Surgery)

Breast cancer is the most common cancer in women in the United States. Breast reconstruction surgery is commonly part of breast cancer treatment when a woman has a mastectomy.

One possible approach to breast reconstruction surgery is to use the skin and the tissue just beneath it from the woman's own abdominal wall to reconstruct her breast. This procedure is called deep inferior epigastric perforator (DIEP) flap breast reconstruction. To prepare for reconstruction surgery, the surgeon orders imaging tests to identify the location, size, and position of the arterial branches that supply the DIEP flap with blood. The blood supply is essential to map before surgery because that blood supply must also be moved to the chest to keep the reconstructed tissue alive. The main artery is called the deep inferior epigastric artery; the size and location of this artery normally varies between women.

The preferred imaging test to map the blood supply is CT angiography (CTA; a scan that shows the blood vessels), with intravenous (IV) contrast, of the abdomen and pelvis. The excellent detail improves outcomes and reduces complications by contributing to the best surgical planning. MR angiography (MRA), with and without IV contrast, of the abdomen and pelvis is an alternative to CTA. MRA of the abdomen and pelvis without IV contrast may also be appropriate. CTA exposes patients to radiation; MRA does not.

Low Back Pain

Most people who go to the doctor with recent low back pain do not need to have x-rays or MRIs or other types of imaging tests. If the pain persists for more than 6 weeks despite physical therapy, exercise, and medication (conservative treatment), then some form of imaging test may be needed.

Imaging tests should also be considered for patients who have symptoms (red flags) that may mean there is a serious condition causing the pain. These may include a fracture, cancer, compressed nerves, or infection. Many different ways of imaging the spine are available to physicians to request on behalf of their patients. The one to use depends on what is suspected to be the cause of the pain, the urgency of the problem, and other patient medical conditions. If a fracture of the lower part of the spine (lumbar spine) is suspected, a CT scan is recommended. Patients that continue to have pain after 6 weeks of conservative treatment and have persisting issues with nerves not working properly resulting in pain, weakness, numbness, or difficulty controlling specific muscles may want to have an MRI. Patients that have severe or worsening problems with their nerves not working properly should be evaluated with MRI.

Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer

When a patient has a confirmed diagnosis of invasive breast cancer, the patient may receive chemotherapy ahead of surgery. This is called neoadjuvant therapy and is used to shrink tumors before they are removed surgically. It also treats cancer that has spread (metastasized). Imaging tests before and during neoadjuvant treatment can help guide treatment decisions.

  • Mammography, digital breast tomosynthesis (DBT), and breast ultrasound (US) are used together to determine tumor size at the beginning of neoadjuvant treatment, changes in tumor size during treatment, and at the end of treatment. US is more accurate than mammography and DBT at determining tumor size after treatment, especially if the remaining tumor is larger than 7 mm. US is also used to determine if cancer cells have spread to the lymph nodes near the breast (the axilla). During and after neoadjuvant treatment, US can be used to see if cancer in the lymph nodes is responding to chemotherapy.
  • MRI without and with intravenous contrast media is used before treatment to evaluate for multiple tumors in dense breast tissue and to evaluate response to neoadjuvant chemotherapy. MRI can also assess for tumor-containing lymph nodes in the chest.
  • Fluorodeoxyglucose PET with CT or CT of the chest, abdomen, and pelvis with intravenous contrast and a bone scan are used when there is suspicion that cancer has spread outside the chest.

For more information, see the Breast Cancer Treatment page.

Ovarian Cancer Screening

Ovarian cancer is usually found at a late stage because there are no current screening tests that have been able to find the cancer at an earlier stage or to reduce the number of ovarian cancer deaths. Women at a high risk of ovarian cancer due to certain risks factors may benefit from screening.

Pre- and postmenopausal women are considered to have a high risk of ovarian cancer if they have a personal or family history of ovarian cancer, have or are suspected to have BRCA1 or BRCA2 genetic mutations, or have an elevated CA-125 level (antigen 125—a protein elevated in cancer tumor cells) as measured by a blood test. These women may decide to get screened.

The recommended imaging test to screen for ovarian cancer is ultrasound (US) to visualize the ovaries. These tests include transvaginal US (preferred), transabdominal US (in women who are not good candidates for transvaginal US), and US color Doppler (allows for visualization of blood flow). US does not use any radiation.

Pre- and postmenopausal women with no personal or family history of ovarian cancer, who do not have BRCA1 or BRCA2 genetic mutations, and who do not have an elevated CA-125 level are considered to have an average risk of ovarian cancer. It is not recommended that these women have imaging tests to screen them for ovarian cancer.

CT and MRI are usually not appropriate for women with either average or high risk of ovarian cancer. For more information, see the Ovarian Cancer page.

Routine Chest Radiography

Getting a chest x-ray before going into the hospital for an operation or for something routine is not needed unless a patient has heart or lung disease or symptoms of a heart or lung condition. The x-ray does not add information that would change treatment after getting information about the patient's medical history and symptoms and performing the physical examination. Chest x-rays should not be used routinely for the evaluation of patients with high blood pressure unless some type of heart disease is suspected. Chest x-rays are not recommended for routine physical examinations or for lung cancer screening.

For patients older than 70 years, patients with heart or lung disease or who have had heart or lung disease in the past, or if the medical history is not available, having a chest x-ray before an operation or when admitted to the hospital may be appropriate. Also, if a patient is undergoing a high-risk operation, such as emergency surgery, it may be appropriate to have a chest x-ray. However, having a chest x-ray before an operation does not mean that after the operation, during the recovery process, the patient will not have issues with lung function.

Chest x-rays expose patients to radiation. They also can show things that are not associated with the reason for the x-ray, called incidental findings. Sometimes these findings can lead to more tests or treatments that are not really needed. For more information, see the Chest X-ray page.

Sinonasal Disease

Most people who have rhinosinusitis, a runny nose, or a stuffed up feeling in their sinuses don't need imaging tests. The patient's symptoms are used to determine the type of rhinosinusitis. If the symptoms are acute and limited to the nose and last less than 4 weeks, no imaging is recommended.

If acute rhinosinusitis comes back more than four times a year, it is considered recurrent acute rhinosinusitis. If the symptoms persist for more than 12 weeks and include mucus draining, pain in the face, stuffy nose, congestion, and a diminished sense of smell, chronic rhinosinusitis is probable. There may also be polyps or a fungus in the nose. In these cases patients may benefit from surgery, and imaging with either CT or cone-beam CT without intravenous contrast is recommended.

If symptoms of acute rhinosinusitis include symptoms pointing to infection in the eye cavity or the brain, MRI with and without intravenous contrast is recommended. If the patient can't undergo MRI, a CT scan with contrast is recommended.

If a blockage or mass is suspected because of persistent pain, blocked nasal passages, or bleeding from the nose, both MRI with and without contrast and CT without contrast are recommended.

If a fungal invasion is suspected in the mucus tissues, blood vessels, and/or bones, both CT without contrast and MRI with and without contrast of the sinuses, nearby brain tissues, and eye sockets are recommended.

Transcatheter Aortic Valve Replacement

A common cause of heart disease is buildup of calcium in the aorta that causes narrowing and stiffness of the aortic heart valve (aortic stenosis). Transcatheter aortic valve replacement (TAVR) is a procedure to replace the aortic heart valve by going through an individual's larger blood vessels (for example, arteries located in the groin or neck or under the clavicle). It is an alternative for people that might do poorly if they have open heart surgery.

When planning for TAVR, precise measurements of the dimensions of the person's aorta, at the location of the heart valve, are important for picking the right size and shape of the artificial valve. Measurements of the aorta and connected arteries are also important to figure out if blood vessels are big enough for the artificial valve to go through and to select the path with lowest risk. CT angiography (CTA) with intravenous contrast is recommended to show blood vessels of the chest, abdomen, and pelvis. CTA data reduce the chance of complications with the procedure.

CTA without contrast is not good enough for planning TAVR. In people with CT contrast allergy, ultrasound (echocardiography) of the heart can measure the size of the aorta but is not good enough for planning the TAVR. For these individuals, MR angiography (MRA) with contrast is a better alternative. MRA is limited in showing the amount of calcium and cannot be used in people with some implants, claustrophobia, or irregular heart rhythms.

Trauma Head Child

Head injuries in children can be dangerous and should be evaluated by a doctor. The Glasgow Coma Scale test helps determine if imaging tests are needed. In children with Glasgow scores less than 13 or with Glasgow scores greater than or equal to 13 with no symptoms of an injury, imaging is often not needed. If the test is equal to or more than 13 and the child has symptoms of a possible injury or if the score is less than 13, a CT scan without contrast is recommended. A CT scan helps identify bleeding, brain tissue damage, fluid in the brain, or skull fractures. The main risk to a child having a CT scan is exposure to radiation.

MRI does not use radiation and is better at finding areas of traumatic damage in the brain than a CT test. MRIs need the child to stay still for a long time, so the doctor may give the child calming medication. MRI is often used to follow up if the symptoms do not go away or if there are new symptoms.

A CT scan of the head is the preferred test when child abuse is suspected. An MRI can be done if the CT scan does not show anything. MRI is better than a CT scan at evaluating areas of brain injury that are more likely in child abuse. An MRI of the top of the spine should also be considered in these cases because there is often damage in this area as well.

For more information, see the Head Injury page.

This page was reviewed on August 21, 2018

Do you have a personal story about radiology?

Submit Your Patient Story Share your patient story here

Sponsored by

Please note is not a medical facility. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.

This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. Discuss the fees associated with your prescribed procedure with your doctor, the medical facility staff and/or your insurance provider to get a better understanding of the possible charges you will incur.

Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America (RSNA) and the American College of Radiology (ACR), comprising physicians with expertise in several radiologic areas.

Outside links: For the convenience of our users, provides links to relevant websites., RSNA and ACR are not responsible for the content contained on the web pages found at these links.