Note: This guideline has been updated. The National Guideline Clearinghouse (NGC) is working to update this summary.

Adrenal mass

To evaluate the appropriateness of radiologic procedures for the evaluation of an incidentally discovered adrenal mass

Patients with adrenal mass

Note: This diagnostic appropriateness discussion is limited to patients with masses detected incidentally during computed tomography, ultrasound, or magnetic resonance imaging evaluation.

Utility of radiologic procedures in the evaluation of patients with adrenal mass

Literature Search Procedure

The Medline literature search is based on keywords provided by the topic author. The two general classes of keywords are those related to the condition (e.g., ankle pain, fever) and those that describe the diagnostic or therapeutic intervention of interest (e.g., mammography, MRI).

The search terms and parameters are manipulated to produce the most relevant, current evidence to address the American College of Radiology Appropriateness Criteria (ACR AC) topic being reviewed or developed. Combining the clinical conditions and diagnostic modalities or therapeutic procedures narrows the search to be relevant to the topic. Exploding the term "diagnostic imaging" captures relevant results for diagnostic topics.

The following criteria/limits are used in the searches.

1. Articles that have abstracts available and are concerned with humans.
2. Restrict the search to the year prior to the last topic update or in some cases the author of the topic may specify which year range to use in the search. For new topics, the year range is restricted to the last 5 years unless the topic author provides other instructions.
3. May restrict the search to Adults only or Pediatrics only.
4. Articles consisting of only summaries or case reports are often excluded from final results.

The search strategy may be revised to improve the output as needed.

The total number of source documents identified as the result of the literature search is not known.

Strength of Evidence Key

Category 1 - The conclusions of the study are valid and strongly supported by study design, analysis, and results.

Category 2 - The conclusions of the study are likely valid, but study design does not permit certainty.

Category 3 - The conclusions of the study may be valid, but the evidence supporting the conclusions is inconclusive or equivocal.

Category 4 - The conclusions of the study may not be valid because the evidence may not be reliable given the study design or analysis.

The topic author drafts or revises the narrative text summarizing the evidence found in the literature. American College of Radiology (ACR) staff draft an evidence table based on the analysis of the selected literature. These tables rate the strength of the evidence for all articles included in the narrative text.

The expert panel reviews the narrative text, evidence table, and the supporting literature for each of the topic-variant combinations and assigns an appropriateness rating for each procedure listed in the table. Each individual panel member forms his/her own opinion based on his/her interpretation of the available evidence.

More information about the evidence table development process can be found in the ACR Appropriateness Criteria® Evidence Table Development document (see the "Availability of Companion Documents" field).

Modified Delphi Technique

When the data available from existing scientific studies are insufficient, the American College of Radiology Appropriateness Criteria (ACR AC) employs systematic consensus techniques to determine appropriateness. The ACR AC panels use a modified Delphi technique to determine the rating for a specific procedure. A series of surveys are conducted to elicit each individual panelist's expert opinion of the appropriateness of an imaging or therapeutic procedure for a specific clinical scenario based on the available data. ACR staff distributes surveys to the panelists along with the evidence table and narrative. Each panelist interprets the available evidence and rates each procedure. Voting surveys are completed by panelists without consulting other panelists. The ratings are integers on a scale between 1 and 9, where 1 means the panel member feels the procedure is "least appropriate" and 9 means the panel member feels the procedure is "most appropriate." Each panel member has one vote per round to assign a rating. The surveys are collected and de-identified and the results are tabulated and redistributed after each round. A maximum of three rounds are conducted. The modified Delphi technique enables each panelist to express individual interpretations of the evidence and his or her expert opinion without excessive bias from fellow panelists in a simple, standardized, and economical process.

Consensus among the panel members must be achieved to determine the final rating for each procedure. If eighty percent (80%) of the panel members agree on a single rating or one of two consecutive ratings, the final rating is determined by the rating that is closest to the median of all the ratings. Up to three voting rounds are conducted to achieve consensus.

If consensus is not reached through the modified Delphi technique, the panel is convened by conference call. The strengths and weaknesses of each imaging examination or procedure are discussed and a final rating is proposed. If the panelists on the call agree, the rating is accepted as the panel's consensus. The document is circulated to all the panelists to make the final determination. If consensus cannot be reached, "No consensus" appears in the rating column and the reasons for this decision are added to the comment sections.

Not applicable

A formal cost analysis was not performed and published cost analyses were not reviewed.

Criteria developed by the Expert Panels are reviewed by the American College of Radiology (ACR) Committee on Appropriateness Criteria.

Note: This guideline has been updated. The National Guideline Clearinghouse (NGC) is working to update this summary. The recommendations that follow are based on the previous version of the guideline.

Note from the American College of Radiology (ACR) and the National Guideline Clearinghouse (NGC): ACR has updated its Relative Radiation Level categories and Rating Scale. The Rating Scale now includes categories (1,2,3 = Usually not appropriate; 4,5,6 = May be appropriate; 7,8,9 = Usually appropriate). See the original guideline document for details.

ACR Appropriateness Criteria®

Clinical Condition: Incidentally Discovered Adrenal Mass

Variant 1: No history of malignancy; mass 1 to 4 cm in diameter. Initial evaluation.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: No history of malignancy; mass 1 to 4 cm in diameter. Follow-up evaluation in 12 months.

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Variant 3: No history of malignancy; mass >4 cm in diameter. (If not typical for adenoma, myelolipoma, hemorrhage, or simple cyst, consider resection.)

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Variant 4: History of malignancy; mass <4 cm in diameter. Initial evaluation.

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Variant 5: History of malignancy; mass >4 cm in diameter.

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Summary of Literature Review

The adrenal "incidentaloma" is an unsuspected and asymptomatic mass, usually detected on computed tomography (CT) obtained for other purposes. Incidentally discovered adrenal masses can be of varying sizes, but in general, the larger the lesion the more likely it is to be symptomatic. The majority of incidentalomas are benign and most often represent adenomas. The prevalence of adenomas in the general population, as summarized by one group of researchers, ranges from 1% to 2%, although autopsy studies have shown rates as high as 6.6% to 8.7% depending on the age distribution of the patient sample. The risk of primary adrenal cortical carcinoma in this population is quite small, on the order of 0.06%; however, among patients with adrenal masses the risk is reported to be as high as 4.7%. Other adrenal malignancies include angiosarcomas, lymphomas, and pheochromocytomas. These are diminishingly rare in the general population.

Metastatic disease without a known history of primary malignancy is also unusual. In a recent study of 1,049 incidental adrenal masses in patients with no known history of cancer, none were malignant lesions. The majority of lesions were adrenal adenomas, myelolipomas and cysts.

The situation is different for patients with a known history of malignancy. In this setting, the rate of metastatic disease has been reported to be as high as 25% to 72% depending on the size and type of the primary lesion. For instance, bronchogenic and renal carcinomas and melanoma have a relatively higher rate of adrenal metastases than other epithelial malignancies. Despite this, a report found that even in patients with non-small cell lung cancer, adenomas were more common than metastases.

The guidelines suggested here apply to masses detected incidentally during CT, ultrasound (US), or magnetic resonance imaging (MRI) evaluation. The patient is free of symptoms, although the mass may later prove to be functional (i.e., Cushing's or Conn's adenoma or pheochromocytoma). The appropriateness of performing additional studies to ascertain whether the mass is more likely benign or malignant is discussed here.

Size

Size is an important variable in predicting malignancy of an incidentally discovered adrenal mass. Smaller lesions are usually benign. Conversely, larger lesions, because they have already demonstrated the potential for growth, are often malignant. However, it is important to distinguish between populations with and without a history of malignancy. One group of researchers studying 342 patients without a history of malignancy found only a 1.5% rate of malignancy in the adrenal, and all malignant lesions were >5 cm. Another study found 3 of 23 incidental lesions to be malignant, and all were >3 cm. In contrast, in patients with a history of malignancy, one study found that 87% of lesions <3 cm were benign and that more than 95% of lesions >3 cm were malignant. In a similar population, another group found that only 79% of lesions <2.5 cm were benign. Another study in a mixed population showed that a threshold of 3.1 cm discriminated 93% of lesions. Thus, size predicts benignity much better in a population without known malignancy. Size is an important variable in a population with a known malignancy, but there is more overlap for a given threshold diameter. Overall, size is considered too unreliable to be used alone as a criterion for malignancy, although in general, currently a 4-cm cut-off is used to make decisions regarding surgery for lesions which do not have diagnostic imaging features such as can be seen in myelolipoma.

Endocrinologic Function

Even though incidentally discovered adrenal masses are by definition asymptomatic, a proportion will show subclinical function. One group of researchers found that 23% of patients who had an adrenal mass but no history of malignancy had detectable secretion of aldosterone, cortisol, or catecholamines. A similar study found that percentage to be 12%. Routine endocrinologic screening of patients with incidentalomas has been recommended for lesions larger than 4 cm. The Swedish Cooperative Study of 388 patients with adrenal incidentalomas found that 5% of them were hypersecreting and included pheochromocytomas (70%) and functional cortical adenomas (30%). Thus, testing for subclinical hyperfunction may be warranted in selected cases. Two recent series have found a much higher percentage of pheochromocytomas discovered incidentally (29% to 59%) than previously thought.

Computed Tomography

CT not only detects incidentally discovered adrenal masses but also offers one of the best means of differentiating the benign from the malignant masses. There are no data for CT accuracy in characterizing adrenal masses which are under 1 cm in size. So anecdotally many believe that masses in this size range do not require imaging workup. Some benign lesions such as cysts and myelolipomas are readily characterized by CT by their imaging features. Adrenal adenomas contain lipid to varying degrees, and this lowers their attenuation coefficient on non–contrast-enhanced CT. One group of researchers showed that when 0 Hounsfield units (HU) was used as a threshold value, the sensitivity for adenomas was 48% without any false positives. If the threshold was increased to 10 HU, the sensitivity was 56% with a 4% false positive rate. This has been confirmed by another study; however, a similar study found that no false positives were seen up to a threshold of 16.5 HU. One group has shown that there is some variability in the density measurements on different CT scanners. A threshold value of 10 HU is generally accepted as a cut-off value for the diagnosis of a lipid-rich adenoma, as the 10 HU threshold has a 71% sensitivity and specificity of 98% for adenomas in one meta-analysis study.

Another study has demonstrated that using histograms of pixel values rather than the average value of the region of interest allows more adenomas to be identified while preserving a high specificity. If 5% or more of the pixels of a lesion are less than 0 HU, the lesion is very likely to be an adenoma. This is of particular relevance after contrast media has been given. Although sensitivity is reduced compared to nonenhanced CT, the use of histogram analysis can improve the sensitivity for adenoma from 10% to 36% if >5% of pixels are negative. However, another study of 208 pathologically proven adrenal masses showed that negative pixels were seen in metastases, adrenal carcinomas, and pheochromocytomas. In addition, the authors noted that using a 5% negative pixel threshold improved specificity for adenoma diagnosis; however, the low sensitivity precluded clinical usefulness. A group of researchers has recently shown that histogram analysis is superior to density measurements for the diagnosis of lipid-poor adenomas. However, histogram analysis has not been extensively or rigorously tested to currently justify its routine clinical use.

Unenhanced CT is a relatively inexpensive yet highly specific test for differentiating adenomas and some benign nonadenomas from malignant lesions, and histogram analysis may further improve its sensitivity. One group of researchers has shown that delayed enhanced CT and use of washout percentages are better able to distinguish adenomas from metastases. Both lipid-rich and lipid-poor adenomas tend to wash out faster after intravenous contrast. This may result from the increased "leakiness" of malignant vessels compared with benign lesions. These researchers also showed that following a delay of 15 minutes after the administration of intravenous contrast, the sensitivity and specificity of CT could be greatly improved (sensitivity >95%, specificity >97%). Another study had similar results using 30-minute delay times (sensitivity 97%, specificity 100%). The accuracy of washout values was validated in another study of 166 adrenal masses, accurate characterization being achieved in 96% of masses. Thus, this technique is the main tool that is used at many institutions for distinguishing between adenomas and nonadenomas and is superior to nonenhanced CT.

Magnetic Resonance Imaging

Qualitative and quantitative MRI methods have been used to attempt to distinguish between adenomas and nonadenomas. Chemical shift MRI (CSI), introduced by Leroy-Willig et al in 1989, relies on differentiating lesions by their relative lipid content, malignant lesions having virtually no lipid. Another study showed that CSI was correct in 96% of cases, and another study showed that the technique was 100% correct when using a slight variation. Unfortunately, all of these studies were performed in a mixed population of patients with regard to the history of malignancy, so results may not be directly applicable to populations either with or without known malignancy (patient mix will greatly influence results).

Since then, several authors have shown excellent results in a relevant population using simpler CSI techniques. Analytic methods have also varied from simple visual assessment of signal loss on out-of-phase (OOP) imaging compared to in-phase (IP) imaging to quantitative measures of signal loss. One group of researchers concluded that a signal intensity index (IP-OOP/IP) was superior to other methods that normalized signal to spleen, liver, or muscle.

Another study demonstrated substantial advantages to applying CSI imaging in cases where the CT density measurement was between 10 and 30 HU (i.e., indeterminate by CT). For instance, in adenomas with densities between 10 and 30 HU, 89% of the lesions were correctly characterized by CSI. Similar results have been obtained by another group, who concluded that up to 60% of lesions misclassified by unenhanced CT density units can be correctly characterized as adenomas by CSI. One other study has demonstrated that even heterogeneous loss of signal is evidence of a benign lesion. Thus, CSI may have better sensitivity and specificity than nonenhanced CT. However, in another study with a small sample size that compared delayed enhanced CT and CSI, the authors showed that delayed enhanced CT was slightly superior to CSI in characterizing adrenal masses measuring more than 10 HU on unenhanced CT.

Adrenal Biopsy

Biopsy of the incidental adrenal mass has been performed under CT guidance for over 20 years. Most studies on the efficacy of adrenal biopsy have been performed in a mixed population of patients. Biopsy samples insufficient to make a diagnosis are obtained in 4% to 19% (mean = 15%) of cases. When sufficient material is obtained, the accuracy of biopsy is 96% to 100% for malignant lesions. Biopsy interpretation is more difficult in benign processes. Complication rates range from 8% to 12% and consist of bleeding, pneumothorax, infection, and anecdotes of tumor tracking. Several deaths have been reported after an adrenal biopsy of a pheochromocytoma. One group of researchers demonstrated that when biopsy was compared to CT and MRI it had the highest combination of sensitivity and specificity (83% and 100%, respectively). Thus, biopsy is better suited to a population with a high risk of malignant lesions and is most useful when noninvasive studies are negative or inconclusive. The role of adrenal biopsy has evolved, and it is now performed to exclude the presence of metastases when noninvasive tests are inconclusive, or in enlarging adrenal masses seen at follow-up imaging or to confirm the presence of an adrenal metastasis.

Radionuclide Studies

Iodocholesterol (NP 59) scans are rarely used in the United States and are confined to a few major centers. NP 59 studies will detect any lesion with functioning adrenal tissue. Thus, hyperfunctional adenomas (Conn's and Cushing's adenomas) and many nonhyperfunctioning adenomas will bind this agent. When the CT and NP 59 scan are concordant, the lesion is benign in all cases. One group of researchers studying a population of patients with a history of tumor showed that most (82%) lesions with discordant uptake were metastatic; 11% were indeterminate. Thus, radionuclide studies are very useful if concordant but overlap significantly if they are discordant with the CT findings.

Metaiodobenzylguanidine (MIBG) studies are useful in patients suspected of a pheochromocytoma, but this is rarely the case in the incidentally detected adrenal mass.

Fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-labeled for positron emission tomography (PET) can be used to identify metastases in oncologic patients with various cancers. FDG-PET is sensitive to metabolically active lesions, and metastases usually show greater uptake than benign lesions. In several studies, there have been few false positives with FDG-PET, and excellent sensitivity has been achieved. False negative scans have occurred in renal cell carcinoma metastases. Specific uptake values (SUV) are typically greater for metastatic disease. Recently, a new tracer for PET, 11-C metomidate, has been found to localize in adrenocortical tumors and it is useful to determine that the tumor is of adrenocortical origin; however, it cannot distinguish between benign and malignant tumors.

Summary and Workup Algorithm

For patients with no history of malignancy, most small (<4 cm) incidentally discovered adrenal masses are benign, and an extensive and costly workup is usually not justified. If a mass of any size has typical features of a benign lesion such as a lipid-rich adenoma or myelolipoma, no additional workup or follow-up imaging is needed. In those with nondiagnostic imaging features, if prior imaging is available and the lesion is stable for at least 1 year, it can be deemed benign with no additional imaging follow-up. But if the lesion is enlarging, then it may be prudent to proceed to an adrenal biopsy or resection. If there are no prior comparison CT or magnetic resonance (MR) exams, and if the lesion has benign imaging features, a diagnosis of a benign lesion can be made and one may consider a follow-up unenhanced CT or CSI exam in 12 months. However if there are suspicious imaging features then one should proceed with an unenhanced CT or CSI and from there proceed to an adrenal CT protocol with washout calculations. If the lesion does not have imaging and washout features of a benign lesion, then a biopsy may be appropriate. If imaging features are not diagnostic for a benign lesion and there is a prior history of cancer and no prior imaging, one can consider PET imaging or an unenhanced CT or CSI. If the lesion does not behave like a typical adenoma, then one should proceed to adrenal CT with washout. If the lesion does not show washout features of an adenoma or findings of an adenoma on PET imaging, then a biopsy should be considered. In patients with no history of cancer and an adrenal mass >4 cm in size, one may consider resection. But if there is a history of prior cancer, one may consider a PET scan or a biopsy.

Endocrinologic evaluation may be considered, as subclinical hyperfunction has been reported to be present in 5% of adrenal incidentalomas, and as per the recommendations of the National Institute of Health (NIH) consensus conference on adrenal incidentalomas.s

• Lesions >4 cm and which do not possess imaging features diagnostic of benign lesions, such as adenoma or myelolipoma, in general are removed in most centers due to the higher risk of malignancy.
• For patients with a history of malignancy, it is important to exclude from further evaluation any patient with widespread nonadrenal metastases since, in this setting, the presence or absence of adrenal metastases is unlikely to influence the patient's outcome. The unenhanced CT and delayed enhanced CT can be used in this setting. If these are inconclusive, FDG-PET, CSI, or biopsy could be considered. Adrenal biopsy should be reserved for cases where the noninvasive techniques are equivocal and to confirm the presence of metastases. In patients suspected of having a functional lesion, iodocholesterol, or 11-C metomidate or MIBG studies may be useful.
• Radiography and US have a very limited role in assessing adrenal lesions.

Anticipated Exceptions

Patients with pheochromocytoma should not have adrenal biopsy unless properly pretreated. This diagnosis should be excluded prior to biopsy with urinary or plasma catecholamine levels. In equivocal cases, a glucagon stimulation test should be done before biopsy of a potential pheochromocytoma.

Nephrogenic systemic fibrosis (NSF) is a disorder with a scleroderma-like presentation and a spectrum of manifestations that can range from limited clinical sequelae to fatality. It appears to be related to both underlying severe renal dysfunction and the administration of gadolinium-based contrast agents. It has occurred primarily in patients on dialysis, rarely in patients with very limited glomerular filtration rate (GFR) (i.e., <30 mL/min/1.73 m²), and almost never in other patients. There is growing literature regarding NSF. Although some controversy and lack of clarity remain, there is a consensus that it is advisable to avoid all gadolinium-based contrast agents in dialysis-dependent patients unless the possible benefits clearly outweigh the risk, and to limit the type and amount in patients with estimated GFR rates <30 mL/min/1.73 m². For more information, please see the ACR Manual on Contrast Media (see the "Availability of Companion Documents" field).

Abbreviations

• CT, computed tomography
• FDG-PET, fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography
• HU, Hounsfield units
• Med, medium
• MIBG, metaiodobenzylguanidine
• MR, magnetic resonance
• MRI, magnetic resonance imaging
• NS, not specified
• US, ultrasound

Algorithms were not developed from criteria guidelines.

The recommendations are based on analysis of the current literature and expert panel consensus.

Selection of appropriate radiologic imaging procedures for the evaluation of patients with adrenal mass

Complication rates of adrenal biopsy range from 8% to 12% and consist of bleeding, pneumothorax, infection, and anecdotes of tumor tracking. Several deaths have been reported after an adrenal biopsy of a pheochromocytoma.

Gadolinium-based Contrast Agents

Nephrogenic systemic fibrosis (NSF) is a disorder with a scleroderma-like presentation and a spectrum of manifestations that can range from limited clinical sequelae to fatality. It appears to be related to both underlying severe renal dysfunction and the administration of gadolinium-based contrast agents. It has occurred primarily in patients on dialysis, rarely in patients with very limited glomerular filtration rate (GFR) (i.e., <30 mL/min/1.73 m²), and almost never in other patients. Although some controversy and lack of clarity remain, there is a consensus that it is advisable to avoid all gadolinium-based contrast agents in dialysis-dependent patients unless the possible benefits clearly outweigh the risk, and to limit the type and amount in patients with estimated GFR rates <30 mL/min/1.73 m². For more information, please see the American College of Radiology (ACR) Manual on Contrast Media (see the "Availability of Companion Documents" field).

Relative Radiation Level (RRL)

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, an 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. Additional information regarding radiation dose assessment for imaging examinations can be found in the American College of Radiology (ACR) Appropriateness Criteria® Radiation Dose Assessment Introduction document (see the "Availability of Companion Documents" field).

Patients with pheochromocytoma should not have adrenal biopsy unless properly pretreated. This diagnosis should be excluded prior to biopsy with urinary or plasma catecholamine levels.

The American College of Radiology (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 exams 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 U.S. Food and Drug Administration (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.

An implementation strategy was not provided.

Not applicable: The guideline was not adapted from another source.

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Urologic Imaging

Panel Members: Isaac R. Francis, MD (Principal Author and Panel Chair); David D. Casalino, MD (Panel Vice-Chair); Ronald S. Arellano, MD; Deborah A. Baumgarten, MD, MPH; Nancy S. Curry, MD; Manjiri Dighe, MD; Pat Fulgham, MD; Gary M. Israel, MD; John R. Leyendecker, MD; Nicholas Papanicolaou, MD; Srinivasa Prasad, MD; Parvati Ramchandani, MD; Erick M. Remer, MD; Sheila Sheth, MD

Not stated

Note: This guideline has been updated. The National Guideline Clearinghouse (NGC) is working to update this summary.

Electronic copies of the updated guideline: Available in Portable Document Format (PDF) from the American College of Radiology (ACR) Web site.

Print copies: Available from the American College of Radiology, 1891 Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

The following are available:

• ACR Appropriateness Criteria®. Overview. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the American College of Radiology (ACR) Web site.
• ACR Appropriateness Criteria®. Literature search process. Reston (VA): American College of Radiology; 1 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Evidence table development. Reston (VA): American College of Radiology; 4 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Radiation dose assessment introduction. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria® Manual on contrast media. Reston (VA): American College of Radiology; 90 p. Electronic copies: Available in PDF from the ACR Web site.

None available

This NGC summary was completed by ECRI on February 10, 2006. This NGC summary was updated by ECRI Institute on November 16, 2007. This NGC summary was updated by ECRI Institute on June 4, 2010.

Instructions for downloading, use, and reproduction of the American College of Radiology (ACR) Appropriateness Criteria® may be found on the ACR Web site .