Acute Chest Pain — Suspected Aortic Dissection

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American College of Radiology
ACR Appropriateness Criteria®
Clinical Condition: Acute Chest Pain — Suspected Aortic Dissection
Radiologic Procedure Rating Comments RRL*
This procedure should be performed if
readily available at the bedside and if it
X-ray chest 9 does not cause delay in obtaining a CT or
MRI scan. Alternative causes of chest pain
may be discovered. This is not the
definitive test for aortic dissection.
This procedure is recommended as the ☢ ☢ ☢ ☢
CTA chest and abdomen with IV contrast 9 definitive test in most patients with
suspicion of aortic dissection.
This procedure is an alternative to CTA
for contraindication to CT (iodinated
contrast), multiple prior chest CTA for
MRA chest and abdomen without and 8 similar symptoms, and in patients showing O
with IV contrast no signs of hemodynamic instability.
Scanner availability and local expertise
limit widespread use, as there is potential
for delay in diagnosis.
US echocardiography transesophageal 8 Consider this procedure if a skilled O
operator is readily available.
This procedure is an alternative to CTA
for patients with contraindication to both
iodinated and gadolinium contrast agents,
such as in patients with renal failure,
MRA chest and abdomen without IV 7 patients with multiple prior chest CTA for O
contrast similar symptoms, and in patients showing
no signs of hemodynamic instability.
Scanner availability and local expertise
limit widespread use, as there is potential
for delay in diagnosis.
Aortography chest and abdomen 5 ☢ ☢ ☢ ☢
US echocardiography transthoracic resting 4 O
This procedure is not recommended as the
FDG-PET/CT skull base to mid-thigh 3 initial test. It may be useful for ☢ ☢ ☢ ☢
prognostication and for distinguishing
acute from chronic dissection.
Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate *Relative
Radiation Level

 

ACUTE CHEST PAIN — SUSPECTED AORTIC DISSECTION

 

Expert Panel on Cardiac Imaging: Jill E. Jacobs, MD1; Larry A. Latson Jr., MS, MD2; Suhny Abbara, MD3; Scott R. Akers, MD4; Philip A. Araoz, MD5; Kristopher W. Cummings, MD6; Ricardo C. Cury, MD7; Sharmila Dorbala, MD8; James P. Earls, MD9 ; Udo Hoffmann, MD, MPH10; Joe Y. Hsu, MD11; Faisal Khosa, MD12; James K. Min, MD13; Pamela K. Woodard, MD.14

 

Summary of Literature Review

 

Introduction/Background

 

Aortic dissection typically presents with sudden onset of excruciating, tearing, anterior, or interscapular chest pain that tends to migrate along the course of the dissection. Symptoms may be dominated by dissection-related side branch obstruction or malperfusion syndrome due to aortic obstruction by the flap. Timely diagnosis of ascending aortic dissection is crucial to permit prompt surgical management, as the early mortality rates are reported to be 1%–2% per hour after the onset of symptoms [1]. Mortality is high in untreated aortic dissection. The overall in-hospital mortality rate for acute aortic dissection is reported to be 12%–27% [2,3]. Medical management alone of type A aortic dissections is associated with a mortality rate of nearly 20% by 24 hours after presentation, 30% by 48 hours, 40%–70% by day 7 [4], and 50% by 1 month [1]. The major cause of early death is aortic rupture [5]. The presence of a patent false lumen has been associated with an increased risk of mortality [6]. Classification of aortic dissection is based on the site of the intimal tear and the extent of the dissection. The clinical presentations of these various types of dissections may be quite similar.

 

Classification of Aortic Dissection

 

In DeBakey type I and type II dissection, the entrance intimal tear is located in the ascending aorta, usually just a few centimeters above the aortic valve. In type I dissection, the intimal flap extends for a variable distance beyond the aortic arch and into the descending aorta, whereas in type II the intimal flap is confined to the ascending aorta. Type III dissection originates in the descending aorta, usually just beyond the origin of the left subclavian artery, and propagates antegrade down the descending aorta. Rarely, the entrance intimal tear occurs in an unusual location such as the abdominal aorta [5].

 

The more commonly used Stanford classification comprises 2 categories. Type A refers to any dissection involving the ascending aorta, and therefore is equivalent to DeBakey type I and type II. Type B dissection is confined to the aorta distal to the left subclavian artery and may extend to the abdominal aorta. Stanford type B dissection is therefore equivalent to DeBakey type III. Approximately two- thirds of dissections involve the ascending aorta (type A) [7]. Differentiation of the types of dissection is done by identifying the location of the intimal flap and is crucial because patients with a type A dissection of the aorta typically require surgical correction or stenting. Type B dissection is often managed medically unless the aorta is excessively dilated or there is mesenteric/limb ischemia [5].

 

Both the Stanford and DeBakey classifications are ambiguous with regard to dissections involving the descending aorta and aortic arch but spare the ascending aorta proximal to the innominate artery. Such lesions are best described as Stanford type B or DeBakey type III with arch involvement to provide surgeons and cardiologists with the information needed to make appropriate management decisions. Reoperations after surgical repair in patients with type I and type II dissections are necessary in up to 10% of patients at 5 years and 40% of patients at 10 years [5].

 

An aortic intramural hematoma is considered a variant of classic dissection. The etiology is uncertain, but postulates include rupture of the vasa vasorum in the medial layer of the aorta. This may provoke a secondary tear and communication with the aortic lumen, converting to a dissection in 28%–47% of patients [5]. Intramural

hematomas may extend along the aorta or may progress, regress, or reabsorb. The prevalence of intramural hematoma in patients with suspected aortic dissection is in the range of 21%–30% [1]. Involvement of the ascending aorta is generally considered an indication for urgent surgery because the potential complications are similar to that of dissection in this location. [8]. Penetrating aortic ulcer is another aortic condition properly considered separately from true aortic dissection, as both the pathophysiology (aortic wall disruption originating in an atherosclerotic plaque) and epidemiology (patients tend to be older, with extensive aortic atherosclerosis and a lesser degree of hypertension) differ from those of aortic dissection.

 

Overview of Imaging

 

Imaging studies in the evaluation of suspected thoracic aortic dissection should be directed toward confirming its presence; classifying the dissection as Stanford type A or B (and/or DeBakey types I, II, or III); identifying entry and reentry sites; evaluating the patency of the false lumen; detecting the presence or absence of aortic branch involvement, assessing involvement of the coronary ostia; evaluating aortic valve competency; and determining the presence or absence of extravasated blood in mediastinal, pleural, or pericardial spaces. In addition, imaging should help distinguish classic aortic dissection from other causes of “acute aortic syndrome” such as acute intramural hematoma and penetrating aortic ulcer.

 

Radiography

 

The primary role of chest radiography in patients with suspected acute aortic dissection is to rule out other thoracic pathology. Although a chest radiograph is recommended in patients presenting with acute chest pain, including those suspected of having aortic dissection, a substantial portion of patients with dissection may have negative chest radiograph findings. Therefore, further imaging should be pursued despite a normal chest radiograph in cases of suspected aortic dissection. In most cases of dissection, the positive findings on a chest radiograph are nonspecific and, when studied in conjunction with the clinical history, can be significant and provide supporting evidence for dissection [9]. Widening of the superior mediastinum, among other signs of dissection, is seen in up to 61% of patients [10]. However, mediastinal widening may be difficult to accurately evaluate, especially with portable radiography, which tends to magnify the aorta more compared to the standard posteroanterior view [11]. Displacement of aortic wall calcification is a finding of limited value and may be misleading. Therefore, most patients with acute chest pain and suspicion of dissection will need further noninvasive imaging despite having either a negative or positive chest radiograph.

 

Computed Tomography

 

Computed tomography (CT) with contrast injection is indicated in the diagnosis of aortic dissection. CT was the most common initial diagnostic test performed in patients enrolled in the International Registry of Acute Aortic Dissection [12]. It is minimally invasive as well as faster, safer, cheaper, and less resource-intensive than catheter aortography. Most hospitals now have in-house CT technologists available 24 hours a day for emergency studies. CT angiography (CTA) affords high-quality thin axial sections that demonstrate intimal flaps, aortic atherosclerotic plaque, branch vessel involvement, entry and reentry sites; patency of the false lumen, extravascular pathologic conditions that may cause mediastinal widening or chest symptoms, and the spatial relationships and status of adjacent organs and pericardial and pleural spaces. Precontrast images are often utilized in CTA protocols for suspected aortic dissection to identify aortic calcification and intramural hematoma [13], and are also 71%–94% sensitive for the detection of acute dissection [14].

 

A significant advantage of CT is that alternative causes of chest pain have been reported in up to 21% of cases scanned for suspected aortic dissection [15]. Electrocardiographic (ECG) gating is a useful technique to reduce motion artifacts as discussed in further detail later in this document. Factors reducing the diagnostic accuracy of CTA include poor opacification of the aorta due to inadequate contrast injection or improper bolus timing, failure to identify the intimal flap because of motion artifacts, and misinterpretation of streak artifacts or motion artifacts as an intimal flap. When the false lumen does not opacify, differentiation among a thrombus-filled atherosclerotic aneurysm, thrombosed dissection, or intramural hematoma may be difficult. Other disadvantages of CT include the need for intravenous administration of iodinated contrast material and the use of ionizing radiation.

 

Numerous older studies evaluating the efficacy of CT in diagnosing aortic dissection have demonstrated sensitivities of 90%–100% but lower specificities ranging from 87% to 100% [16-19]. However these studies evaluated conventional CT, which has largely been supplanted by faster multidetector helical CT (MDCT). More recent MDCT studies enrolling up to 57 patients have reported sensitivities and specificities of 100% [13]. The multidetector arrays in MDCT allow accurate imaging of a large anatomic area with high resolution and a short

 

acquisition time. MDCT permits short volumetric acquisition, facilitating patient breath-holding and thereby eliminating ventilatory misregistration. Narrow collimation results in improved resolution with improved visualization of vascular structures as compared with conventional CT. Shorter imaging times also improve bolus tracking and image acquisition during peak contrast enhancement, resulting in improved visualization of vascular structures compared with conventional CT. CTA provides exquisite detail of the aortic anatomy, branch vessel involvement, and associated visceral pathology (ischemia/infarction). ECG gating has proven particularly valuable for minimizing ascending aortic motion artifacts that can mimic dissection without significantly increasing imaging time [20- 22]. In addition, ECG gating allows for qualitative assessment of aortic insufficiency and evaluation of coronary artery involvement. Type A dissection is reported to involve the coronaries in approximately 15% of patients undergoing surgery for acute type A dissection [23].

 

The rapid, large-volume acquisition that can be obtained with MDCT allows imaging of both the thoracic and abdominal components of the dissection and assessment of extension of the dissection into abdominal and pelvic branch vessels with one injection of a reasonable volume of contrast. Postprocessing of the volumetric dataset using multiplanar reformatting and 3- D volume rendering facilitates evaluation of the location and course of the intimal flap [24], branch vessel, and visceral organ involvement. Recent studies show similar sensitivities for CTA, transesophageal echocardiography (TEE), and magnetic resonance imaging (MRI) in detecting aortic dissection [12,15,19,25]. Evaluation of the relative accuracy of these modalities is confounded by the fact that technical improvements in CT, MRI, and TEE have outpaced our ability to perform necessary research trials. To date, there have been no large studies comparing MDCT, MRI, and TEE.

 

Because the differential diagnosis for patients presenting with an acute chest pain syndrome is broad and often includes multiple etiologies including coronary artery disease, pulmonary embolism, and aortic dissection, triple-rule-out CT protocols are increasingly being used so that all 3 of these potentially fatal possibilities can be evaluated in a single examination [10,26]. Although details of protocols vary between institutions, the general technique involves intravenous administration of iodinated contrast, the timing of which allows for assessment of both the pulmonary arteries and the aorta. The pulmonary arteries are evaluated on the initial nongated study, and the aorta, aortic root, and the coronary arteries are evaluated on the ECG-gated examination. Various techniques, such as prospective ECG triggering and tube current modulation, can be used to reduce radiation exposure. It has been reported that triple-rule-out CT can safely eliminate further diagnostic testing in over 75% of patients in the appropriate patient population [27]. However, a recent randomized study found that the triple -rule-out protocol, though having similar diagnostic yield, did not reduce the length of stay in the emergency room, the rate of subsequent testing, or costs compared to either a dedicated coronary CTA, a dedicated CT pulmonary embolism study, or a dedicated CT dissection study [28].

 

Compared to a dedicated CTA performed specifically for assessing aortic dissection, the major disadvantages of the triple- rule-out protocol are increased contrast and radiation doses, thus limiting its applicability to the unique subset of patients in whom pulmonary embolism, aortic dissection, and acute coronary syndrome cannot be reliably clinically differentiated based on patient symptomatology. Moreover, most triple-rule-out protocols exclude the noncontrast phase of a dedicated aortic CTA, thus rendering evaluation for intramural hematoma more difficult. Most triple-rule-out protocols also exclude the abdominal aorta, and as descending dissections often extend to involve the abdominal aorta, the full extent of a descending aortic dissection may not be visualized. With the introduction of newer high-pitch CT acquisition techniques, imaging times are becoming fast enough to allow for at least limited assessment of the proximal coronary arteries without ECG-gating, further reducing radiation dose [29]. Continued clinical research is necessary to confirm appropriate utilization of the triple-rule-out examination [28,30-32].

 

Although precontrast images are recommended for identifying calcification and intramural hematoma, such a sequence may not be necessary with the advent of dual-source dual-energy multidetector CT (DECT), which enables generation of virtual noncontrast images from a single dual-energy data acquisition. However, the use of these virtual noncontrast images remains controversial [33-35]. Advantages of DECT include reduction in the number of acquisition sequences performed, thereby reducing patient radiation dose [36]. In addition, due to increased photoelectric absorption at 80 kVp, DECT may allow for a smaller volume of contrast material to be administered [34,35]. Further outcomes studies are needed to assess the performance of DECT in the acute setting.

 

Magnetic Resonance Angiography

 

MRA allows the noninvasive visualization of the thoracic and abdominal aorta in multiple projections without the use of ionizing radiation. Patients can also be imaged without the use of contrast agents if they are contraindicated. A variety of pulse sequences are available. ECG -triggered black-blood or white-blood images provide exquisite anatomic detail of the heart and aorta. Cine MRI and other fast-gradient-echo techniques allow visualization of flowing blood, facilitating the differentiation of slow-flowing blood and clot and determination of the presence of aortic insufficiency. The true and false lumen and intimal flap are readily identified [17]. Functional cardiac information such as aortic regurgitation and left ventricular function can be assessed. Newer gadolinium contrast-enhanced 3-D contrast-enhanced MRA (CE-MRA) techniques permit rapid acquisition of MR angiograms of the thoracic and abdominal aorta and their branch vessels. These techniques allow coverage of large volumes with and without breath-holding, and 3-D datasets may be reconstructed. 3-D CE-MRA permits easy identification of both the true and false lumen and enables identification of the type of dissection and assessment of patency of the false lumen [37,38]. A unique advantage of gated white-blood MRI techniques is that these can demonstrate whether the intimal flap is causing organ ischemia by occluding the flow of blood to a branch vessel during the cardiac cycle (usually systole).

 

MRI is considered a very accurate technique for diagnosing aortic dissection [17- 19,25,37,39,40]. Both the sensitivity and specificity of MRI for diagnosing aortic dissection have recently been reported to be 100%. For identifying the site of entry, sensitivity was 85% and specificity 100%, and for identifying thrombus and the presence of a pericardial effusion, sensitivity and specificity were both 100%. Excellent sensitivity (92%–98%) and specificity (100%) have been documented for CE-MRA in acute and chronic aortic dissection [10]. Limitations of MRI are longer examination times compared with MDCT and more limited scanner availability on an emergency basis. Studies in uncooperative patients and patients who are unable to hold their breath can result in nondiagnostic images. The use of cardiac gating may be limited in the presence of cardiac arrhythmias. Further, patients with cardiac pacemakers, ferromagnetic aneurysm clips, and other MRI -incompatible devices cannot undergo MRI. Newer “MR conditional” pacemakers are being developed, but these have not yet reached widespread use [41].

 

Monitoring and treatment of very ill patients are also more difficult in the MRI environment compared with CT. Faster MRI techniques are being explored, and as the newer generations of faster scanners are developed, the feasibility of scanning these patients emergently is expected to improve [42]. Importantly, gadolinium-based contrast agents are contraindicated in patients with severe renal insufficiency due to the risk of nephrogenic systemic fibrosis [43]. In patients with renal insufficiency, in whom both iodinated CT contrast agents and gadolinium-based MR contrast agents may be contraindicated, noncontrast MR using sequences such as ECG-gated cine true-fast imaging with steady state precession and respiratory-gated 3-D steady state free precession have been shown to be as accurate as contrast-enhanced MRA in the diagnosis of acute aortic syndromes [42,44,45].

 

Echocardiography

 

In the diagnosis of aortic dissection, echocardiography has the advantages of being widely available and suitable for use at the bedside in hemodynamically unstable patients. Transthoracic echocardiography (TTE) has been found to have a sensitivity of 59%–85% and a specificity of 93%–96% [39,40,46,47]. It is useful in the diagnosis of dissection involving the ascending aorta and can diagnose the hemodynamic significance of pericardial effusions, the degree of aortic regurgitation, and left ventricular function [18]. TTE is of marginal value in diagnosing distal dissections because of the limited availability of ultrasound (US) windows [10]. Although the sensitivity of TTE in detecting descending aortic dissections was previously reported to be lower (31%–80%) than contrast-enhanced CT and MRI, recent technical innovations such as harmonic imaging and microbubble contrast enhancement have been demonstrated to improve the sensitivity of TTE in detecting descending dissections to 84% [48].

 

TEE overcomes many of the limitations of TTE and can image almost the entire thoracic aorta with limited visualization of the distal ascending aorta and arch vessels. TEE has sensitivity similar to that of MRI and CT for detecting aortic dissection, and it is also useful for detecting associated coronary artery involvement.

 

Multiplanar TEE can accurately diagnose aortic dissection with sensitivity, specificity, and negative predictive values of up to 100% [40,47,49,50]. Principal limitations of TEE are its dependence on a high degree of operator skill and blind areas in the distal ascending aorta and proximal transverse arch that are obscured by the air-

 

containing trachea and left main bronchus. Diagnostic problems may also be encountered in the ascending aorta where reverberation artifacts can result in false-positive diagnosis of dissection [51]. Additional limitations include inability to visualize the distal extent of the dissection in the abdomen. Nonetheless, in most cases of acute dissection, TEE provides immediate, sufficient information to determine whether surgical intervention is indicated. Additionally, in hemodynamically unstable individuals, TEE typically can be safely performed with topical anesthetic alone. In descending aortic dissection, angiography, CT, and MRI are preferable because they allow evaluation of branch vessel involvement and assessment of the distal extension of the dissection.

 

Intravascular US has been explored for evaluating aortic dissection [52-54]. However, it is an invasive procedure, and its use has been limited to intraoperative or postoperative evaluation of aortic dissection. Presently, intravascular US has no role in the immediate evaluation of suspected acute aortic syndrome.

 

Angiography

 

Angiography has historically been considered the gold standard for diagnosing aortic dissection with sensitivity, specificity, positive predictive value, and negative predictive value of 88%, 94%, 96%, and 84%, respectively [55].

 

The diagnostic accuracy of digital subtraction angiography approaches 98% in some series. Angiography permits management of critically ill patients, and aortic regurgitation and aortic branch vessel involvement (including the coronary arteries) can be assessed [56]. High frame rates facilitate identification of the intimal tear and the degree of aortic insufficiency. False-negative arteriograms may occur when the false lumen is not opacified, when there is simultaneous opacification of the true and false lumen, and when the intimal flap is not displayed in profile.

 

Disadvantages of angiography are that it is invasive, iodinated contrast material is required, and angiography has limited ability to assess the surrounding structures for involvement (eg, for the presence of mediastinal hemorrhage), which is readily detected by CT. Although angiography provides good visualization of the thoracic and abdominal branch vessels and flow patterns, it is now rarely used in the evaluation and management of acute aortic dissection except where definitive coronary evaluation is required. In recent years, it has been largely replaced by minimally invasive TEE and noninvasive CT and MRI [1]. More recently, with the development of so-called “hybrid” operating rooms, which are fully-equipped operating rooms that also include the capability for performing both diagnostic angiographic and therapeutic endovascular procedures, preoperative angiographic assessment of the coronary arteries and sites of visceral malperfusion is feasible without adding a large time delay between angiography and definitive therapy [57].

 

18F-Flourodeoxyglucose Positron Emission Tomography/Computed Tomography

18F-Flourodeoxyglucose positron emission tomography (FDG-PET)/CT has recently been explored for evaluation of aortic dissection and has been shown to be of value in distinguishing acute from chronic dissection [58- 60]. In addition, several studies have also shown that elevated FDG uptake of mean standardized uptake value in the region of the dissection flap is predictive of poor outcome [58,59].

 

Several studies reported that increased FDG avidity in the atherosclerotic vascular wall correlated with dense infiltrations of macrophages and the number of macrophages in the plaque [52,61,62]. These results support the hypothesis that the uptake of FDG is predictive of elevated concentrations of macrophages and serves as a marker of atherosclerotic inflammation within the aortic wall. Other studies have demonstrated a relationship between the degree of inflammation (as measured by serum C-reactive protein levels) and vascular complications and/or poor outcome in patients with acute aortic dissection [63,64].

 

A significant disadvantage of FDG-PET/CT is the prolonged scan time, thus obviating its applicability in the acute setting. In addition, as the available data are limited to small studies, this modality has limited value until results from larger studies become available. Potentially, FDG -PET/CT may play a role in prognosticating the outcome in individuals diagnosed with aortic dissection. Further investigation is warranted.

 

Summary

 

Because patients with acute dissection are critically ill and potentially in need of emergency operation, the selection of a given modality will depend on clinical circumstances and availability.

Current experience suggests that the accuracies of TEE (performed by a skilled operator and reader), MDCT, and MRI are very similar.

 

CTA is likely to be more rapidly available on a 24-hour basis and is associated with less patient discomfort. It can provide information on branch vessel involvement and ancillary significant findings and has the advantage of evaluating the aorta, branch vessels, and visceral organs in their entirety. Although it does not provide information regarding aortic insufficiency, this information can be obtained with TTE or TEE, if needed, while the operating room is being prepared.

 

In selected centers where experienced cardiologists are readily available to perform TEE in the emergency room, or in instances where hemodynamic or other clinical factors preclude CTA, TEE may be the preferred first-line imaging study because it can provide sufficient information to determine whether emergency surgery is needed.

 

When information about branch vessel involvement is required by the surgeon and not provided by CTA (a rare occurrence with MDCT units), angiography may be useful. Coronary angiography may still be required if definitive preoperative coronary evaluation is needed and was suboptimally assessed on the prior MDCT, MRI, or TTE examination.

 

MRA may be sufficient to replace angiography in stable patients and in patients with chronic dissection or uncertain diagnoses. In selected centers, MRA may readily be offered as the first line of imaging on an emergent basis. Faster imaging sequences may enable its use in less stable patients. In patients with renal insufficiency who cannot receive either iodinated or gadolinium-based contrast agents, the development of newer ECG- and respiratory-gated noncontrast MRA sequences can provide detailed diagnostic evaluation of the aorta comparable to that of contrast-enhanced MRA.

Image postprocessing of CT and MRI data using multiplanar image reformatting and 3-D volume rendering may provide additional useful information for treatment planning.

Relative Radiation Level Information

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, both because of organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared to those specified for adults (see Table below). Additional information regarding radiation dose assessment for imaging examinations can be found in the ACR Appropriateness Criteria® Radiation Dose Assessment Introduction document.

Relative Radiation Level Designations

 

Relative Radiation Level* Adult Effective Dose Estimate Pediatric Effective Dose Estimate
Range Range
O 0 mSv 0 mSv
<0.1 mSv <0.03 mSv
☢ ☢ 0.1-1 mSv 0.03-0.3 mSv
☢ ☢ ☢ 1-10 mSv 0.3-3 mSv
☢ ☢ ☢ ☢ 10-30 mSv 3-10 mSv
☢ ☢ ☢ ☢ ☢ 30-100 mSv 10-30 mSv

 

*RRL assignments for some of the examinations cannot be made, because the actual patient doses in these procedures vary as a function of a number of factors (eg, region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as “Varies”.

Supporting Documents

For additional information on the Appropriateness Criteria methodology and other supporting documents go to

www.acr.org/ac.

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The ACR Committee on Appropriateness Criteria and its expert panels have developed criteria for determining appropriate imaging examinations for diagnosis and treatment of specified medical condition(s). These criteria are intended to guide radiologists, radiation oncologists and referring physicians in making decisions regarding radiologic imaging and treatment. Generally, the complexity and severity of a patient’s clinical condition should dictate the selection of appropriate imaging procedures or treatments. Only those examinations generally used for evaluation of the patient’s condition are ranked. Other imaging studies necessary to evaluate other co-existent diseases or other medical consequences of this condition are not considered in this document. The availability of equipment or personnel may influence the selection of appropriate imaging procedures or treatments. Imaging techniques classified as investigational by the FDA have not been considered in developing these criteria; however, study of new equipment and applications should be encouraged. The ultimate decision regarding the appropriateness of any specific radiologic examination or treatment must be made by the referring physician and radiologist in light of all the circumstances presented in an individual examination.

1Principal Author, New York University Medical Center, New York, New York. 2Research Author, New York University Medical Center, New York, New York. 3Panel Vice-chair, UT Southwestern Medical Center, Dallas, Texas. 4VA Medical Center, Philadelphia, Pennsylvania. 5Mayo Clinic, Rochester, Minnesota. 6Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, Missouri. 7Baptist Hospital of Miami, Kendall, Florida. 8Brigham and Women’s Hospital, Boston, Massachusetts, Society of Nuclear Medicine and Molecular Imaging. 9Fairfax Radiological Consultants, Fairfax, Virginia. 10 Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. 11Kaiser Permanente, Los Angeles, California. 12Emory University, Atlanta, Georgia. 13Cedars Sinai Medical Center, Los Angeles, California, American College of Cardiology. 14Panel Chair, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, Missouri.

The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document.

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