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Diagnostic Imaging: Appropriate and Safe Use

Brian Ford, MD
Michael Dore, MD
Paul Moullet, DO

American Family Physician. 2021;103(1):42-50.

Author disclosure: No relevant financial affiliations.

Published online November 23, 2020.

Radiation Safety and Risk

Medical Decision Support and Appropriate Use of Imaging

Reference(s)

SORT: KEY RECOMMENDATIONS FOR PRACTICE

BEST PRACTICES IN DIAGNOSTIC IMAGING

Approximate Ionizing Radiation Exposure from Common Imaging

Resources for Managing Radiation Exposure from Imaging

American College of Radiology Appropriateness Criteria Ratings for Selected Diagnostic Imaging Studies

The use of diagnostic radiography has doubled in the past two decades. Image Gently (children) and Image Wisely (adults) are multidisciplinary initiatives that seek to reduce radiation exposure by eliminating unnecessary procedures and offering best practices. Patients with an estimated glomerular filtration rate less than 30 mL per minute per 1.73 m2 may have increased risk of nephropathy when exposed to iodinated contrast media and increased risk of nephrogenic systemic fibrosis when exposed to gadolinium-based contrast agents. American College of Radiology Appropriateness Criteria can help guide specific diagnostic imaging choices. Noncontrast head computed tomography is the first-line modality when a stroke is suspected. Magnetic resonance imaging stroke protocols and computed tomography perfusion scans can augment evaluation and potentially expand pharmacologic and endovascular therapy timeframes. Imaging should be avoided in patients with uncomplicated headache syndromes unless the history or physical examination reveals red flag features. Cardiac computed tomography angiography, stress echocardiography, and myocardial perfusion scintigraphy (nuclear stress test) are appropriate for patients with chest pain and low to intermediate cardiovascular risk and have comparable sensitivity and specificity. Computed tomography pulmonary angiography is the preferred test for high-risk patients or those with a positive d-dimer test result, and ventilation-perfusion scintigraphy is reserved for patients with an estimated glomerular filtration rate less than 30 mL per minute per 1.73 m2 or a known contrast allergy. Computed tomography with intravenous contrast is preferred for evaluating adults with suspected appendicitis; however, ultrasonography should precede computed tomography in children, and definitive treatment should be initiated if positive. Ultrasonography is the first-line modality for assessing right upper quadrant pain suggestive of biliary disease. Mass size and patient age dictate surveillance recommendations for adnexal masses. Imaging should not be performed for acute (less than six weeks) low back pain unless red flag features are found on patient history. Ultrasonography should be used for the evaluation of suspicious thyroid nodules identified incidentally on computed tomography.

Estimates suggest that 30% of all U.S. health expenditures are a result of waste, with approximately $100 billion lost on overtreatment and low-value care; inappropriate radiography is a major component.1 The use of advanced imaging, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography, and nuclear medicine, has doubled in a 16-year period, accounting for 11% of allowed Medicare charges in 2018.2,3 Awareness of risks, benefits, and recommendations related to radiography enhances shared decision-making and reduces unnecessary testing.2,4

WHAT'S NEW ON THIS TOPIC

Diagnostic Imaging

The use of advanced imaging, including computed tomography, magnetic resonance imaging, ultrasonography, and nuclear medicine, has doubled in the past 16 years, accounting for 11% of 2018 allowed Medicare charges.

The Protecting Access to Medicare Act, which will be fully implemented as of January 1, 2022, requires clinicians to consult appropriate use criteria via a clinical decision support mechanism before ordering advanced diagnostic imaging services for Medicare Part B patients.

The proportion of personal radiation exposure attributed to medical sources rose from 5% in the 1980s to more than 50% by 2009, with computed tomography scans constituting 25% of all radiation exposure despite a decrease in radiation per scan.

SORT: KEY RECOMMENDATIONS FOR PRACTICE

Clinical recommendation Evidence rating Comments
Follow reduced radiation protocols from the Image Wisely (adults) and Image Gently (children) initiatives, and use American College of Radiology Appropriateness Criteria when making diagnostic imaging decisions.8–16 C Expert opinion and longitudinal cohort studies
Prophylactic isotonic crystalloid volume expansion is recommended in patients with an eGFR less than 30 mL per minute per 1.73 m2 to prevent contrast-induced nephropathy.21–28 C Large retrospective propensity-matched studies demonstrate no significant effect; expert opinion and consensus guidelines still encourage hydration in these patients
An eGFR less than 30 mL per minute per 1.73 m2 is a relative contraindication for the use of gadolinium-based contrast agents.29–31 C Expert opinion and consensus guidelines
Do not perform imaging in patients with primary headache disorders without new or progressive features who have normal neurologic examination findings.37,52,53 C Expert opinion and consensus guidelines
A clinical probability assessment tool should be used to determine pretest probability before performing imaging in patients with suspected pulmonary embolism. The Pulmonary Embolism Rule-out Criteria or d-dimer testing can be used to avoid unnecessary computed tomography pulmonary angiography in some low- or intermediate-risk patients.57–60 C Expert opinion and well-designed randomized clinical trials with disease-oriented outcomes
Do not perform plain chest radiography in asymptomatic patients for preoperative evaluations or for baseline testing during hospitalization.42,52,72,73 C Large meta-analysis of 20 trials with disease-oriented outcomes; expert opinion
Do not perform imaging in patients with acute (less than six weeks) low back pain and no red flag findings on history or physical examination.47,75,76 B Numerous randomized clinical trials and systematic reviews and meta-analyses

eGFR = estimated glomerular filtration rate.

A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to https://www.aafp.org/afpsort.

BEST PRACTICES IN DIAGNOSTIC IMAGING

Recommendations from the Choosing Wisely Campaign
RecommendationSponsoring organization
Avoid using CT as the first-line imaging modality in the evaluation of suspected appendicitis in children. Ultrasonography should be performed first, with CT or magnetic resonance imaging considered in equivocal cases.American Academy of Pediatrics
Do not perform CT for evaluation of suspected appendicitis in children until after ultrasonography has been considered as an option.American College of Radiology
CT scans are not necessary in the routine evaluation of abdominal pain.American Academy of Pediatrics
Avoid CT scans of the head in emergency department patients with minor head injury who are at low risk based on validated decision rules.American College of Emergency Physicians
CT scans are not necessary in the evaluation of minor head injuries.American Academy of Pediatrics
Do not routinely obtain CT scans in children with mild head injuries.American Association of Neurological Surgeons and Congress of Neurological Surgeons

CT = computed tomography.

Source: For more information on the Choosing Wisely Campaign, see https://www.choosingwisely.org. For supporting citations and to search Choosing Wisely recommendations relevant to primary care, see https://www.aafp.org/afp/recommendations/search.htm.

The 2014 Protecting Access to Medicare Act (PAMA) requires clinicians to consult appropriate use criteria via a clinical decision support tool before ordering advanced diagnostic imaging services for Medicare Part B patients.5 Appropriate use criteria have been employed since 2018 as part of PAMA, but on January 1, 2020, the year-long education and operations testing period began. During this period, imaging orders that do not include use of a clinician decision support will still be performed and covered without payment consequences, although consultation with a clinical decision support mechanism is recommended. The Centers for Medicare and Medicaid Services extended this trial period for another year, until December 2021.6 The list of qualifying clinical decision support mechanisms was recently updated.6

PAMA will initially focus on eight areas: suspected or diagnosed coronary artery disease; suspected pulmonary embolism; traumatic and nontraumatic headache; hip pain; low back pain; shoulder pain, including suspected rotator cuff injury; suspected or diagnosed lung cancer (primary or metastatic); and neck pain. The program will be fully implemented as of January 1, 2022, after which payment consequences could result from failure to employ appropriate use criteria.5,7

Reduced radiation protocols from the Image Wisely (adults) and Image Gently (children) initiatives and American College of Radiology (ACR) Appropriateness Criteria should be used when making diagnostic imaging decisions.8–16 ACR Appropriateness Criteria cover 193 diagnostic imaging and interventional radiology topics, with 942 clinical variants and more than 1,680 clinical scenarios.17

Radiation Safety and Risk

Most data on cumulative ionizing radiation exposure and cancer incidence come from survivors of atomic tragedies and those working in the nuclear industry, reinforcing a dose response relative to cancer risk.8–10

Radiation dose can be measured in grays (Gy; a measure of absorbed dose) or sieverts (Sv; a measure of equivalent dose). Ionizing radiation exposure varies by type of imaging study (Table 1).18,19 The proportion of radiation exposures in the United States that is attributed to medical sources has risen from 5% in the 1980s to more than 50% in 2009, with CT scans constituting 25% of all exposures despite a decrease in radiation per scan.20 The estimated lifetime relative risk of developing cancer is 5% per Sv of radiation.12 Based on this, the U.S. Food and Drug Administration estimates that the risk of developing a fatal malignancy associated with one CT scan is approximately one out of 2,000.13 This risk is reliant on the patient's age at exposure, the organs exposed, the patient's sex, and other variables.

TABLE 1. Approximate Ionizing Radiation Exposure from Common Imaging

Imaging modalityRadiation dose (mSv)Number of posteroanterior chest radiographs for equivalent exposureHours of commercial air travel for equivalent exposure
Plain radiography
 Chest (posteroanterior view)0.0216.7
 Lumbar spine (three views)1.575500
 Upper gastrointestinal series63002,000
Cardiac catheterization (diagnostic/stent)7/15350/7502,300/5,000
Computed tomography
 Head2100650
 Cervical spine31501,000
 Chest73502,300
 Virtual colonoscopy105003,300
 Abdomen/pelvis147004,650
 Pulmonary embolism protocol157505,000
 Cardiac angiography168005,300
Dual energy x-ray absorptiometry (with computed tomography)0.04213
Mammography0.420130
Nuclear stress test (thallium)40.72,03513,550
Nuclear stress test (sestamibi one-day)9.44703,100
Panoramic dental radiography0.010.53.3

mSv = millisieverts.

Information from references 18 and 19.

According to the Biological Effects of Ionizing Radiations (BEIR) VII report, there is no single radiation dose at which harm begins to occur. Instead, there are small linear increases in risk as exposure increases.16 The risk seems to be most significant for children, in which estimates suggest 1.9 new cases of leukemia for every 10,000 head CT scans.14 Within the radiographic community, there have been concerns about the overestimation of cancer risk based on flawed analyses in BEIR VII, and several population-based studies do not corroborate the anticipated incidence of malignancy attributable to medical imaging.15

Assuming a sex and age distribution similar to that of the United States population, the BEIR VII lifetime risk model predicts that approximately one in 100 individuals would develop cancer (solid cancer or leukemia) from a single 100-mSv dose of radiation (roughly that of a contrast-enhanced CT scan of the chest, abdomen, and pelvis), whereas 42 of these 100 individuals would be expected to develop malignancy from other causes. Risk is dose-dependent in this model.16

The risks of imaging are balanced against a potential inability to formulate definitive diagnoses and treatment plans without imaging. Table 2 includes resources for radiation reduction, including cumulative radiation calculators.

TABLE 2. Resources for Managing Radiation Exposure from Imaging

OrganizationDescriptionWebsite
ACR Appropriateness CriteriaEvidence-based guidelines to assist clinicians in making appropriate imaging decisionshttps://www.acr.org/Clinical-Resources/ACR-Appropriateness-Criteria
American Society of Radiologic TechnologistsRadiation risk calculatorhttps://www.xrayrisk.com/calculator/calculator.php
Image GentlyProvides information and free educational materials to reduce unnecessary imaging studies in childrenhttps://www.imagegently.org
Image WiselyEncourages clinicians to optimize the amount of radiation used in medically necessary imaging studies and to eliminate unnecessary procedures in adultshttps://www.imagewisely.org
Radiologyinfo.orgPatient-centered website through the ACR that gives radiation doses of conventional imaging studieshttps://www.radiologyinfo.org/en/info.cfm?pg=safety-xray#safety-effective-dose-adults
University of California San Diego Department of RadiologyRadiation risk calculator; ideal for principal investigators and informed consent in research trialshttps://ehs.ucsd.edu/Radiation_Risk/request/home

ACR = American College of Radiology.

CONTRAST-INDUCED NEPHROPATHY

Contrast-induced nephropathy is a proposed mechanism of postcontrast acute kidney injury, presuming a direct nephrotoxic effect of iodinated CT contrast media.21,22 The data support only an association between contrast media and acute kidney injury, although the diagnostic criteria for postcontrast acute kidney injury is well-defined as at least one of the following occurring within 48 hours of contrast administration: (1) absolute increase in serum creatinine level of 0.3 mg per dL (26.52 μmol per L) or more from baseline, (2) a relative increase in serum creatinine level of 50% or more from baseline, and (3) a urine output reduced to 0.5 mL per kg per hour or less for at least six hours.23

A meta-analysis of nonrandomized studies including 25,000 patients showed no increased risk of acute kidney injury with contrast (6.4%) vs. no contrast (6.5%).24 Subsequently, two propensity-matched studies of 21,000 patients with normal renal function and 12,500 patients with preexisting renal dysfunction demonstrated no increased risk of acute kidney injury following the use of contrast media.25,26 A similar propensity-matched study showed no increased risk of contrast-induced nephropathy in patients with normal renal function, but it did show an increased risk in patients with a serum creatinine level greater than 1.2 mg per dL (106.08 μmol per L) or an estimated glomerular filtration rate (eGFR) less than 30 mL per minute per 1.73 m2.27

Based on the evidence, and in accordance with a recent consensus statement, intravenous contrast is not independently nephrotoxic in patients with a stable baseline eGFR of 45 mL per minute per 1.73 m2 or greater, and it is not nephrotoxic (or rarely so) in patients with an eGFR of 30 to 44 mL per minute per 1.73 m2.23,28 Studies are mixed for patients with an eGFR less than 30 mL per minute per 1.73 m2; therefore, the ACR continues to recommend prophylactic isotonic crystalloid volume expansion (numerous volume and time-based protocols exist, with no one preferred regimen).21–28

NEPHROGENIC SYSTEMIC FIBROSIS

Nephrogenic systemic fibrosis involves thickening of the skin and subcutaneous tissue and can be rapidly progressive, leading to contractures, joint immobility, and rarely death.29 It is presumed to occur after exposure to gadolinium-based contrast agents (e.g., with contrast-enhanced MRI). It typically occurs within days to months but has been reported years after contrast exposure.30 In patients with an eGFR less than 30 mL per minute per 1.73 m2, the risk of nephrogenic systemic fibrosis is 1% to 7% per exposure to older gadolinium-based contrast agents.31 This risk is inversely proportional to eGFR level and increases with higher doses of contrast or repeated exposures. There are no reported cases of nephrogenic systemic fibrosis in patients with normal renal function (eGFR greater than 60 mL per minute per 1.73 m2), and the risk is low with standard doses of modern gadolinium-based contrast.23

MRI CONTRAINDICATIONS

Many contraindications to MRI are dependent on the machine, patient history, and presence of indwelling devices.32 Absolute contraindications include the presence of metallic foreign bodies in the eye, contact lenses that monitor intraocular pressure and include portions of metal, some insulin pumps (internal and external), and temporary external transvenous pacemaker leads. The presence of an implantable loop recorder, an implantable cardiac defibrillator, a reflux management system, or a pacemaker requires someone experienced in managing these devices and the potential complications if a device fails.32,33 Although manufacturers label many devices as compatible with MRI, imaging requires careful consideration and coordination with the implanting specialty and radiology team. Information about the safety of these devices during imaging is available from manufacturers and from other sources, such as http://www.MRISafety.com/List.html.

Medical Decision Support and Appropriate Use of Imaging

The American Academy of Family Physicians (AAFP) position paper on radiology encourages judicious use of diagnostic radiography to reduce adverse effects and avoid overuse.34 The AAFP recommends using evidence-based criteria, such as ACR Appropriateness Criteria, to assist in clinical decision-making.34 The ACR Appropriateness Criteria rank imaging tests for the evaluation of various conditions from 1 (least recommended) to nine (most recommended), with a relative radiation score.35 ACR Appropriateness Criteria scores for selected clinical scenarios are presented in Table 3.36–47

TABLE 3. American College of Radiology Appropriateness Criteria Ratings for Selected Diagnostic Imaging Studies

ConditionImaging studyRating*
Head and neck
Suspected acute stroke36 Head CT without contrast9
Diffusion-weighted brain MRI8
CT perfusion of the head (which includes CT angiography)6
Headache37 Head CT without contrast> 7
Brain MRI with or without contrast> 7
Thyroid or parotid nodule38 Ultrasonography> 7
Palpable neck mass away from thyroid or parotid glands38 Neck CT with intravenous contrast> 7
Neck MRI with intravenous contrast> 7
Cardiopulmonary
Suspected pulmonary embolism39 Chest CT pulmonary angiography9
Ventilation-perfusion scintigraphy7
Duplex ultrasonography of legs7
Asymptomatic with an intermediate risk of coronary artery disease40 CT for coronary artery calcium scoring8
Asymptomatic with a high risk of coronary artery disease40 CT for coronary artery calcium scoring3
Chronic chest pain in patients with low to intermediate risk of acute coronary syndrome41 CT coronary angiography> 7
Myocardial perfusion scintigraphy (nuclear stress test)> 7
Stress echocardiography> 7
Resting echocardiography5
Preoperative clearance and hospital admission42 Chest radiography3
Abdominal and pelvic imaging
Suspected appendicitis in children with intermediate risk43 Ultrasonography (child)> 7
Right lower quadrant pain with suspicion for appendicitis44 CT with intravenous contrast> 7
Right upper quadrant pain with suspicion for biliary pathology 45 Ultrasonography> 7
Abdominal MRI with or without magnetic resonance cholangiopancreatography after nondiagnostic ultrasonography> 7
Abdominal CT with intravenous contrast after nondiagnostic ultrasonography> 7
Pelvic pain (patients of reproductive age)46 Transabdominal and transvaginal pelvic ultrasonography9
Low back pain after six weeks of ineffective conservative therapy 47 Lumbar spine MRI without contrast8

CT = computed tomography; MRI = magnetic resonance imaging.

*—1 to 3 = study is usually not appropriate; 4 to 6 = may be appropriate; 7 to 9 = usually appropriate.

Information from references 36–47.

HEAD AND NECK

Suspected Acute Stroke. Noncontrast head CT should be performed in any patient with suspected stroke because it is required to determine the need for thrombolysis.48 The choice of additional imaging modalities varies depending on patient presentation, medical institution, and previous management decisions. Through advanced imaging protocols, typical symptomatic treatment windows can be expanded based on imaging characteristics of ischemic lesions.49

Diffusion-weighted MRI increases the sensitivity of stroke detection to greater than 95% in the first three hours.36 Fluid-attenuated inversion recovery is an MRI protocol that peaks in intensity six to 24 hours after ischemia. When fluid-attenuated inversion recovery is contrasted with concomitant diffusion-weighted imaging, it helps to determine stroke duration, which can guide treatment decisions such as initiating pharmacologic thrombolysis or endovascular therapy. CT perfusion is another modality to help guide consideration for endovascular therapy based on the ratio of infarcted tissue to penumbral tissue in specific vascular distributions.50

Headache. Imaging should be performed in patients with headache and abnormal findings on neurologic examination or new symptoms, or progressive symptoms in those with chronic headaches. Red flag features also require consideration for imaging and include recent head trauma, exertional exacerbation of pain, known or suspected cancer, immunocompromised state, pregnancy, thunderclap onset (i.e., severe and acute, reaches peak intensity in less than one minute, and lasts for more than five minutes), and age older than 50 years.51 Imaging is not required in patients with primary headache disorders (i.e., migraine, tension-type, and trigeminal autonomic cephalalgias) that do not meet the previously mentioned criteria.37,52,53

In emergencies, a noncontrast head CT is sensitive enough to rule out new intracranial hemorrhage, mass effect, or normal-pressure hydrocephalus.37 An MRI with or without contrast is more sensitive for pathologies involving a neoplasm, vascular disease, the posterior fossa, or cervicomedullary lesions and for high and low intracranial pressure disorders. MRI is therefore preferable in evaluating headaches in a nonemergency setting.53

Palpable Neck Anomalies. Imaging assessment of palpable thyroid or parotid lesions (e.g., thyroid nodules) begins with ultrasonography.38,54 For other neck masses, contrast-enhanced studies can demonstrate vascular associations and more associated local anatomy. CT or MRI can also be used in the evaluation of neck masses. A CT scan of the neck with intravenous contrast is usually the preferred first study in adults with neck masses outside of the thyroid or parotid glands because of its increased availability and the risk of malignancy.55 Ultrasonography is the preferred imaging modality in children, regardless of mass location.38

CARDIOPULMONARY IMAGING

Suspected Pulmonary Embolism. A clinical probability assessment tool, such as the Geneva score or Wells score, should be used to determine pretest probability before performing imaging in patients with suspected pulmonary embolism. These tools help stratify patient risk as low (approximate 10% chance of pulmonary embolism), intermediate (30% chance), or high (65% chance).56 The Pulmonary Embolism Rule-out Criteria (https://www.mdcalc.com/perc-rule-pulmonary-embolism) have a 97% sensitivity and greater than 99% negative predictive value for ruling out pulmonary embolism in patients in the emergency department who have a low pretest probability.57 For patients who have low to intermediate risk using the Wells criteria (https://www.mdcalc.com/wells-criteria-pulmonary-embolism) or the Geneva score (https://www.mdcalc.com/geneva-score-revised-pulmonary-embolism [original]; https://www.mdapp.co/geneva-score-for-pulmonary-embolism-calculator-115/ [simplified]), a d-dimer test with an age-adjusted cutoff is recommended.58 CT pulmonary angiography is the preferred test for high-risk patients or those with a positive d-dimer test result. This test has a sensitivity of 83%, specificity of 96%, and positive predictive value of 96% when used with clinical probability algorithms.59,60 A 2019 large prospective trial showed potential for changing d-dimer cutoffs used for proceeding with imaging based on clinical pretest probability, although no updated guidelines have advocated this position.61

Ventilation-perfusion scintigraphy (V/Q scan) is preferable for patients with an eGFR less than 30 mL per minute per 1.73 m2 or a known contrast allergy.56,62,63 A V/Q scan produces a 65 to 250 times lower radiation dose to the breasts/chest than CT angiography and can be considered in young or pregnant patients, although institutional protocols and availability may limit its use.60 Studies suggest V/Q scans have a sensitivity of 77% and specificity of 97% but a high percentage (25%) of inconclusive results.62 In patients who are pregnant, documentation of a deep venous thrombosis on duplex ultrasonography can obviate the need for ionizing radiation.39

Evaluation of Coronary Arteries. For asymptomatic patients at intermediate risk of coronary artery disease (as determined by the Framingham Risk Score or American College of Cardiology/American Heart Association Pooled Cohort Equation), a Multi-Ethnic Study of Atherosclerosis score can be calculated using information from a coronary artery calcium test and routine laboratory tests to further stratify patient risk.64 Despite the U.S. Preventive Services Task Force finding insufficient evidence to recommend coronary artery calcium testing and concerns about harms from the test, nonzero coronary artery calcium scores appear to enhance patient adherence to therapeutic plans for cardiovascular prevention.65–67

For patients with acute or chronic chest pain, the appropriateness of imaging depends on patient risk calculated using one of many risk scores (e.g., HEART [history, electrocardiogram, age, risk factors, troponin], TIMI [thrombolysis in myocardial infarction]). CT coronary angiography, stress echocardiography, and myocardial perfusion scintigraphy (nuclear stress test) are appropriate tests for patients with chest pain who have low to intermediate cardiovascular risk.41,68–70

CT coronary angiography has a more than 95% negative predictive value, which is comparable with myocardial perfusion scintigraphy and stress echocardiography.71 However, CT coronary angiography offers no physiologic data because it involves administration of iodinated contrast only to highlight marked stenosis. Conversely, in myocardial perfusion scintigraphy, a radiotracer is taken up avidly in healthy tissue after stress is induced (i.e., from exercise or a vasodilator). Ischemic tissue takes up only a fixed amount of radiotracer, therefore demonstrating anatomic areas of reduced cardiac function and impaired blood flow. Transthoracic echocardiography demonstrates wall motion abnormalities and potential ischemic complications during episodes of chest pain.41

Plain Chest Radiography. The Choosing Wisely campaign discourages performing plain chest radiography in asymptomatic patients for preoperative evaluations or for baseline testing during hospitalization.42,52,72,73

ABDOMINAL AND PELVIC IMAGING

Right Lower Quadrant Pain. For adults, an abdominal CT scan with intravenous contrast is the preferred imaging technique for acute right lower quadrant pain when appendicitis is suspected.44 Oral contrast does not increase sensitivity or specificity in the evaluation of suspected acute appendicitis.74 Ultrasonography should precede CT in children, and definitive treatment should be initiated if results are positive.52

Right Upper Quadrant Pain. Ultrasonography is the initial imaging choice for suspected biliary disease in patients with right upper quadrant pain. For nondiagnostic ultrasound findings, an abdominal MRI with magnetic resonance cholangiopancreatography is a helpful next step. Magnetic resonance cholangiopancreatography can reveal signs of ductal dilatation and acute and chronic cholecystitis. CT with intravenous contrast does not outperform MRI in the diagnostic assessment of right upper quadrant pain and lacks sensitivity in assessing for stones in the common bile duct, although it can effectively identify other pathologies. Cholescintigraphy (e.g., hepatobiliary iminodiacetic acid scan) is a superior study for acalculous cholecystitis if initial ultrasonography is inconclusive.45

Adnexal Imaging. Transvaginal pelvic ultrasonography is the preferred imaging modality for patients with abnormal vaginal bleeding and pelvic pain (acute and chronic). Follow-up is not needed in premenopausal patients with simple cysts or corpus luteum cysts less than 5 cm in size or in postmenopausal patients with simple cysts or corpus luteum cysts less than 1 cm in size.52

LOW BACK PAIN

Imaging should be avoided in patients with acute (less than six weeks) low back pain and no red flag findings on history or physical examination.47,75,76 If red flags are present or six weeks of conservative therapy (e.g., physical therapy) is ineffective, lumbar spine MRI without contrast should be performed in patients with low back pain.47 Findings on low back imaging are common and are of questionable clinical significance. In one study of asymptomatic adults, MRI showed a herniated disk at one spinal level in 64% of patients and on multiple levels in 38% of patients.76

INCIDENTALOMAS

Abnormal radiographic findings discovered in studies performed for unrelated reasons (e.g., an adrenal mass identified during a CT scan to rule out appendicitis) occur in 20% to 50% of imaging studies.77 These incidentalomas can present a significant challenge in balancing perceived low-risk findings with potential frequent radiographic follow-up.78 The ACR provides clinical guidance for the follow-up of patients with incidentalomas.79

Follow-up is indicated for all suspicious thyroid nodules (evidence of localized invasion or pathologic adenopathy) found incidentally on CT. Nonsuspicious nodules should be further characterized with ultrasonography in patients younger than 35 years if the nodule is 1 cm or larger and in patients 35 years and older if the nodule is 1.5 cm or larger.52 Comprehensive standards for follow-up are organ-based and beyond the scope of this article.

This article updates a previous article on this topic by Crownover and Bepko.80

Data Sources: The following evidence-based medicine resources were searched: Essential Evidence Plus, the Agency for Healthcare Research and Quality evidence reports, Clinical Evidence, the Cochrane database, PubMed, and the Trip database. Key words were diagnostic imaging, radiation risk, ionizing radiation, nephrogenic systemic fibrosis, diffusion-weighted imaging, headache, chest pain, right upper quadrant abdominal pain, right lower quadrant abdominal pain, adnexal masses, suspected stroke, and back pain. Search date: January 15, 2020, and August 28, 2020.

The views expressed in this article are those of the authors and do not reflect the official policy of the U.S. Navy, the U.S. Department of Defense, or the U.S. government.

BRIAN FORD, MD, FAAFP, is an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences, Bethesda, Md. At the time this article was written, he was a faculty physician at Naval Hospital Camp Pendleton, Calif.

MICHAEL DORE, MD, is a staff physician at Naval Hospital Bremerton, Wash.

PAUL MOULLET, DO, is a staff physician at Naval Health Clinic Lemoore, Calif.

Address correspondence to Brian Ford, MD, FAAFP, 4301 Jones Bridge Road, Bethesda, MD 20814 (email: brian.ford@usuhs.edu). Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.

  1. 1.Shrank WH, Rogstad TL, Parekh N. Waste in the US health care system. JAMA. 2019;322(15):1501-1509.
  2. 2.Smith-Bindman R, Kwan ML, Marlow EC, et al. Trends in use of medical imaging in US health care systems and in Ontario, Canada, 2000–2016. JAMA. 2019;322(9):843-856.
  3. 3.Medpac. Report to the Congress: Medicare payment policy. March 2020. Accessed April 5, 2020. http://medpac.gov/docs/default-source/reports/mar20_entirereport_sec.pdf
  4. 4.Caverly TJ, Prochazka AV, Cook-Shimanek M, et al. Weighing the potential harms of computed tomography: patient survey. JAMA Intern Med. 2013;173(7):588-590.
  5. 5.Centers for Medicare and Medicaid Services. Appropriate use criteria program. Updated January 10, 2020. Accessed July 6, 2020. https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/Appropriate-Use-Criteria-Program
  6. 6.Centers for Medicare and Medicaid Services. Clinical decision support mechanisms. Accessed August 28, 2020. https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/Appropriate-Use-Criteria-Program/CDSM
  7. 7.American College of Radiology. How the Medicare AUC program affects imaging orders. Accessed April 5, 2020. https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Clinical-Decision-Support/AUC-program-flyer-web_March2020_F.pdf
  8. 8.Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiat Res. 2000;154(2):178-186.
  9. 9.Preston DL, Ron E, Tokuoka S, et al. Solid cancer incidence in atomic bomb survivors: 1958–1998. Radiat Res. 2007;168(1):1-64.
  10. 10.Cardis E, Vrijheid M, Blettner M, et al. The 15-country collaborative study of cancer risk among radiation workers in the nuclear industry. Radiat Res. 2007;167(4):396-416.
  11. 11.Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med. 2009;169(22):2078-2086.
  12. 12.Lin EC. Radiation risk from medical imaging. Mayo Clin Proc. 2010;85(12):1142-1146.
  13. 13.U.S. Food and Drug Administration. What are the radiation risks from CT? Accessed November 20, 2019. https://www.fda.gov/radiation-emitting-products/medical-x-ray-imaging/what-are-radiation-risks-ct
  14. 14.Miglioretti DL, Johnson E, Williams A, et al. The use of computed tomography in pediatrics and the associated radiation exposure and estimated cancer risk. JAMA Pediatr. 2013;167(8):700-707.
  15. 15.Siegel JA, Greenspan BS, Maurer AH, et al. The BEIR VII estimates of low-dose radiation health risks are based on faulty assumptions and data analyses: a call for reassessment. J Nucl Med. 2018;59(7):1017-1019.
  16. 16.National Research Council. Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2. National Academies Press; 2006:422.
  17. 17.American College of Radiology. ACR Appropriateness Criteria. Accessed December 21, 2019. https://www.acr.org/Clinical-Resources/ACR-Appropriateness-Criteria
  18. 18.Mettler FA, Huda W, Yoshizumi TT, et al. Effective doses in radiology and diagnostic nuclear medicine. Radiology. 2008;248(1):254-263.
  19. 19.Health Physics Society. Radiation exposure during commercial airline flights. Accessed October 30, 2020. https://hps.org/publicinformation/ate/faqs/commercialflights.html
  20. 20.Schauer DA, Linton OW. NCRP report no. 160, ionizing radiation exposure of the population of the United States, medical exposure. Health Phys. 2009;97(1):1-5.
  21. 21.Wichmann JL, Katzberg RW, Litwin SE, et al. Contrast-induced nephropathy. Circulation. 2015;132(20):1931-1936.
  22. 22.Lakhal K, Ehrmann S, Chaari A, et al. Acute Kidney Injury Network definition of contrast-induced nephropathy in the critically ill: incidence and outcome. J Crit Care. 2011;26(6):593-599.
  23. 23.American College of Radiology. Manual on contrast media. 2020. Accessed October 6, 2020. https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf
  24. 24.McDonald JS, McDonald RJ, Comin J, et al. Frequency of acute kidney injury following intravenous contrast medium administration: a systematic review and meta-analysis. Radiology. 2013;267(1):119-128.
  25. 25.McDonald RJ, McDonald JS, Carter RE, et al. Intravenous contrast material exposure is not an independent risk factor for dialysis or mortality. Radiology. 2014;273(3):714-725.
  26. 26.McDonald JS, McDonald RJ, Carter RE, et al. Risk of intravenous contrast material-mediated acute kidney injury. Radiology. 2014;271(1):65-73.
  27. 27.Davenport MS, Khalatbari S, Cohan RH, et al. Contrast material-induced nephrotoxicity and intravenous low-osmolality iodinated contrast material: risk stratification by using estimated glomerular filtration rate. Radiology. 2013;268(3):719-728.
  28. 28.Davenport MS, Perazella MA, Yee J, et al. Use of intravenous iodinated contrast media in patients with kidney disease: consensus statements from the American College of Radiology and the National Kidney Foundation. Radiology. 2020;294(3):660-668.
  29. 29.Kaewlai R, Abujudeh H. Nephrogenic systemic fibrosis. AJR Am J Roentgenol. 2012;199(1):W17-W23.
  30. 30.Larson KN, Gagnon AL, Darling MD, et al. Nephrogenic systemic fibrosis manifesting a decade after exposure to gadolinium. JAMA Dermatol. 2015;151(10):1117-1120.
  31. 31.Collidge TA, Thomson PC, Mark PB, et al. Gadolinium-enhanced MR imaging and nephrogenic systemic fibrosis: retrospective study of a renal replacement therapy cohort [published correction in Radiology. 2010;255(1):308]. Radiology. 2007;245(1):168-175.
  32. 32.Kanal E, Barkovich AJ, Bell C, et al.; Expert Panel on MR Safety. ACR guidance document on MR safe practices: 2013. J Magn Reson Imaging. 2013;37(3):501-530.
  33. 33.Sammet S. Magnetic resonance safety. Abdom Radiol (NY). 2016;41(3):444-451.
  34. 34.American Academy of Family Physicians. Radiology (position paper). Accessed July 6, 2020. https://www.aafp.org/about/policies/all/radiology.html#ii
  35. 35.Jordan DW, Becker M, Brady S, et al. ACR Appropriateness Criteria. Radiation dose assessment introduction. Updated February 2020. Accessed April 5, 2020. https://www.acr.org/-/media/ACR/Files/Appropriateness-Criteria/RadiationDoseAssessmentIntro.pdf
  36. 36.Salmela MB, Mortazavi S, Jagadeesan BD, et al. ACR Appropriateness Criteria cerebrovascular disease. J Am Coll Radiol. 2017;14(5S):S34-S61.
  37. 37.Whitehead MT, Cardenas AM, Corey AS, et al. ACR Appropriateness Criteria headache. J Am Coll Radiol. 2019;16(11S):S364-S377.
  38. 38.Aulino JM, Kirsch CFE, Burns J, et al. ACR Appropriateness Criteria neck mass-adenopathy. J Am Coll Radiol. 2019;16(5S):S150-S160.
  39. 39.Kirsch J, Brown RKJ, Henry TS, et al. ACR Appropriateness Criteria acute chest pain-suspected pulmonary embolism. J Am Coll Radiol. 2017;14(5S):S2-S12.
  40. 40.Earls JP, Woodard PK, Abbara S, et al. ACR Appropriateness Criteria asymptomatic patient at risk for coronary artery disease. J Am Coll Radiol. 2014;11(1):12-19.
  41. 41.American College of Radiology. ACR Appropriateness Criteria. Chronic chest pain-noncardiac etiology unlikely. Accessed October 29, 2020. https://acsearch.acr.org/docs/69337/Narrative/
  42. 42.McComb BL, Chung JH, Crabtree TD, et al. ACR Appropriateness Criteria routine chest radiography. J Thorac Imaging. 2016;31(2):W13-W15.
  43. 43.Koberlein GC, Trout AT, Rigsby CK, et al. ACR Appropriateness Criteria® suspected appendicitis–child. J Am Coll Radiol. 2019;16(5S):S252-S263.
  44. 44.Garcia EM, Camacho MA, Karolyi DR, et al. ACR Appropriateness Criteria right lower quadrant pain-suspected appendicitis. J Am Coll Radiol. 2018;15(11S):S373-S387.
  45. 45.Peterson CM, McNamara MM, Kamel IR, et al. ACR Appropriateness Criteria ® right upper quadrant pain. J Am Coll Radiol. 2019;16(5S):S235-S243.
  46. 46.Bhosale PR, Javitt MC, Atri M, et al. ACR Appropriateness Criteria® acute pelvic pain in the reproductive age group. Ultrasound Q. 2016;32(2):108-115.
  47. 47.Patel ND, Broderick DF, Burns J, et al. ACR Appropriateness Criteria low back pain. J Am Coll Radiol. 2016;13(9):1069-1078.
  48. 48.Powers WJ, Rabinstein AA, Ackerson T, et al.; American Heart Association/American Stroke Association. 2018 guidelines for the early management of patients with acute ischemic stroke [published corrections appear in Stroke. 2018;49(3):e138 and Stroke. 2018;49(6):e233–e234]. Stroke. 2018;49(3):e46-e110.
  49. 49.Thomalla G, Simonsen CZ, Boutitie F, et al. MRI-guided thrombolysis for stroke with unknown time of onset. N Engl J Med. 2018;379(7):611-622.
  50. 50.Albers GW, Marks MP, Kemp S, et al.; DEFUSE 3 Investigators. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. N Engl J Med. 2018;378(8):708-718.
  51. 51.Hainer BL, Matheson EM. Approach to acute headache in adults. Am Fam Physician. 2013;87(10):682-687. Accessed July 6, 2020. https://www.aafp.org/afp/2013/0515/p682.html
  52. 52.Choosing Wisely. Ten things physicians and patients should question. April 4, 2012. Updated June 29, 2017. Accessed April 5, 2020. https://www.choosingwisely.org/societies/american-college-of-radiology/
  53. 53.Loder E, Weizenbaum E, Frishberg B, et al. Choosing wisely in headache medicine. Headache. 2013;53(10):1651-1659.
  54. 54.Knox MA. Thyroid nodules. Am Fam Physician. 2013;88(3):193-196. Accessed July 6, 2020. https://www.aafp.org/afp/2013/0801/p193.html
  55. 55.Haynes J, Arnold KR, Aguirre-Oskins C, et al. Evaluation of neck masses in adults. Am Fam Physician. 2015;91(10):698-706. Accessed July 6, 2020. https://www.aafp.org/afp/2015/0515/p698.html
  56. 56.Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543-603.
  57. 57.Kline JA, Mitchell AM, Kabrhel C, et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost. 2004;2(8):1247-1255.
  58. 58.Raja AS, Greenberg JO, Qaseem A, et al. Evaluation of patients with suspected acute pulmonary embolism. Ann Intern Med. 2015;163(9):701-711.
  59. 59.Stein PD, Fowler SE, Goodman LR, et al.; PIOPED II Investigators. Multidetector computed tomography for acute pulmonary embolism. N Engl J Med. 2006;354(22):2317-2327.
  60. 60.Moore AJE, Wachsmann J, Chamarthy MR, et al. Imaging of acute pulmonary embolism. Cardiovasc Diagn Ther. 2018;8(3):225-243.
  61. 61.Kearon C, de Wit K, Parpia S, et al.; PEGeD Study Investigators. Diagnosis of pulmonary embolism with D-dimer adjusted to clinical probability. N Engl J Med. 2019;381(22):2125-2134.
  62. 62.Sostman HD, Stein PD, Gottschalk A, et al. Acute pulmonary embolism: sensitivity and specificity of ventilation-perfusion scintigraphy in PIOPED II study. Radiology. 2008;246(3):941-946.
  63. 63.Waxman AD, Bajc M, Brown M, et al. Appropriate use criteria for ventilation-perfusion imaging in pulmonary embolism: summary and excerpts. J Nucl Med. 2017;58(5):13N-15N.
  64. 64.Greenland P, Blaha MJ, Budoff MJ, et al. Coronary calcium score and cardiovascular risk. J Am Coll Cardiol. 2018;72(4):434-447.
  65. 65.Curry SJ, Krist AH, Owens DK, et al. Risk assessment for cardiovascular disease with nontraditional risk factors: US Preventive Services Task Force recommendation statement. JAMA. 2018;320(3):272-280.
  66. 66.Mandrola J, Foy A. The case against coronary artery calcium scoring for cardiovascular disease risk assessment. Am Fam Physician. 2019;100(12):734-735. Accessed July 6, 2020. https://www.aafp.org/afp/2019/1215/p734.html
  67. 67.Gupta A, Lau E, Varshney R, et al. The identification of calcified coronary plaque is associated with initiation and continuation of pharmacological and lifestyle preventive therapies: a systematic review and meta-analysis. JACC Cardiovasc Imaging. 2017;10(8):833-842.
  68. 68.Batlle JC, Kirsch J, Bolen MA, et al. ACR Appropriateness Criteria® chest pain–possible acute coronary syndrome. J Am Coll Radiol. 2020;17(5S):S55-S69.
  69. 69.Shah AB, Kirsch J, Bolen MA, et al. ACR Appropriateness Criteria ® chronic chest pain–noncardiac etiology unlikely–low to intermediate probability of coronary artery disease. J Am Coll Radiol. 2018;15(11S):S283-S290.
  70. 70.Akers SR, Panchal V, Ho VB, et al.; Expert Panel on Cardiac Imaging. ACR Appropriateness Criteria ® chronic chest pain–high probability of coronary artery disease. J Am Coll Radiol. 2017;14(5S):S71-S80.
  71. 71.Romero J, Husain SA, Holmes AA, et al. Non-invasive assessment of low risk acute chest pain in the emergency department: a comparative meta-analysis of prospective studies. Int J Cardiol. 2015;187:565-580.
  72. 72.Gómez-Gil E, Trilla A, Corbella B, et al. Lack of clinical relevance of routine chest radiography in acute psychiatric admissions. Gen Hosp Psychiatry. 2002;24(2):110-113.
  73. 73.Archer C, Levy AR, McGregor M. Value of routine preoperative chest x-rays: a meta-analysis. Can J Anaesth. 1993;40(11):1022-1027.
  74. 74.Rud B, Vejborg TS, Rappeport ED, et al. Computed tomography for diagnosis of acute appendicitis in adults. Cochrane Database Syst Rev. 2019(11):CD009977.
  75. 75.Chou R, Fu R, Carrino JA, et al. Imaging strategies for low-back pain: systematic review and meta-analysis. Lancet. 2009;373(9662):463-472.
  76. 76.Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med. 1994;331(2):69-73.
  77. 77.O'Sullivan JW, Muntinga T, Grigg S, et al. Prevalence and outcomes of incidental imaging findings: umbrella review. BMJ. 2018;361:k2387.
  78. 78.Hitzeman N, Cotton E. Incidentalomas. Am Fam Physician. 2014;90(11):784-789. Accessed July 6, 2020. https://www.aafp.org/afp/2014/1201/p784.html
  79. 79.American College of Radiology. Incidental findings. Accessed April 5, 2020. https://www.acr.org/Clinical-Resources/Incidental-Findings
  80. 80.Crownover BK, Bepko JL. Appropriate and safe use of diagnostic imaging. Am Fam Physician. 2013;87(7):494-501. Accessed July 6, 2020. https://www.aafp.org/afp/2013/0401/p494.html
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