ACR Appropriateness Criteria® chylothorax treatment planning.

General

Guideline Title

ACR Appropriateness Criteria® chylothorax treatment planning.

Bibliographic Source(s)

• Majdaluny BS, Murrey DA Jr, Kapoor BS, Cain TR, Ganguli S, Kent MS, Maldonado F, McBride JJ, Minocha J, Reis SP, Lorenz JM, Kalva SP, Expert Panel on Vascular Imaging and Interventional Radiology. ACR Appropriateness Criteria® chylothorax treatment planning. Reston (VA): American College of Radiology (ACR); 2016. 10 p. [52 references]

Guideline Status

This is the current release of the guideline.

This guideline meets NGC’s 2013 (revised) inclusion criteria.

Recommendations

Major Recommendations

ACR Appropriateness Criteria®

Clinical Condition: Chylothorax Treatment Planning

Variant 1: Chylothorax treatment planning: traumatic etiology.

Radiologic Procedure	Rating	Comments	RRL*
X-ray chest	8	This procedure is the initial examination to screen for pleural effusion or an alternative cause of dyspnea or chest pain.
Lymphangiography chest and abdomen	8	If further evaluation and minimally invasive treatment is warranted, this procedure is the test of choice for traumatic chylothorax and can include diagnostic and therapeutic embolization.
MRI chest and abdomen without IV contrast	6	This procedure is particularly helpful if lymphangiography does not delineate an abnormality.	O
MRI chest and abdomen without and with IV contrast	5	This procedure is particularly helpful if lymphangiography does not delineate an abnormality.	O
CT chest and abdomen without IV contrast	5
CT chest and abdomen without and with IV contrast	5
CT chest and abdomen with IV contrast	4
Tc-99m lymphoscintigraphy chest and abdomen	4
US chest and abdomen	4		O
Rating Scale : 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate			*Relative Radiation Level

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

Variant 2: Chylothorax treatment planning: nontraumatic or unknown etiology.

Radiologic Procedure	Rating	Comments	RRL*
X-ray chest	8	This procedure is the initial examination to screen for pleural effusion or an alternative cause of dyspnea or chest pain.
Lymphangiography chest and abdomen	8	This procedure is appropriate if a concomitant minimally invasive attempt at therapy is desired.
MRI chest and abdomen without IV contrast	7	This procedure is useful to visualize lymphatic vessels.	O
MRI chest and abdomen without and with IV contrast	7	This procedure is useful to visualize lymphatic vessels and exclude vascular abnormalities.	O
CT chest and abdomen with IV contrast	7	This procedure is helpful if venous thrombosis is suspected as the cause of the chylous effusion.
CT chest and abdomen without IV contrast	5
CT chest and abdomen without and with IV contrast	5
Tc-99m lymphoscintigraphy chest and abdomen	3
US chest and abdomen	3		O
Rating Scale : 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate			*Relative Radiation Level

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

Summary of Literature Review

Introduction/Background

Chyle is primarily formed in the intestines and is composed of proteins, lipids, electrolytes, and lymphocytes. A chylous pleural effusion, or chylothorax, is a highly morbid condition defined by the presence of chyle within the pleural space. Chronic chyle leak results in metabolic abnormalities, respiratory compromise, immunosuppression, malnutrition, and even death. A review of the etiology, diagnosis, and management of chylothorax is presented in addition to an evaluation of relevant imaging studies.

Etiology

Chylothoraces can be categorized etiologically as traumatic or nontraumatic. Collectively, the incidence of chylothorax is approximately 1 per 6000 admissions. Historically, nontraumatic etiologies accounted for up to 72% of cases. Most recently, the largest study reports that traumatic etiologies account for 54% of cases. The discrepancy may reflect the growth in thoracic oncologic resections or specific referral patterns.

Diagnosis

Chylothorax most commonly presents with dyspnea, although chest pain, fever, and fatigue may also occur. Chyle is odorless, alkaline, sterile, and milky in appearance, although the appearance may vary based on the nutritional status of the patient. Increasing fatty intake increases the volume and can change the color of the fluid and has been described for the diagnosis of a chyle leak. The hallmark of chylous effusion is the presence of chylomicrons in the fluid. Objective diagnostic criteria include a pleural fluid triglyceride level >110 mg/dL and a ratio of pleural fluid to serum triglyceride level of >1.0. A ratio of pleural fluid to serum cholesterol level of <1.0 distinguishes chylothorax from cholesterol pleural effusions, which may present similarly.

Management

The diagnosis is confirmed by draining the fluid for studies; this is also palliative. After replacing fluid and protein losses, a decision about conservative versus invasive therapies can be made. If the chylothorax reaccumulates, treatment is guided by daily outputs, with higher outputs warranting a more aggressive approach.

Conservative measures include management of the underlying disease, thoracentesis, and dietary modifications such as total parenteral nutrition or a nonfat diet to reduce production of chyle and consequently flow through the thoracic duct. Adjunctive therapy may include somatostatin, etilefrine, or nitric oxide, with the underlying etiology determining the efficacy, although the evidence remains scarce. The success of conservative therapy approaches 50% in nonmalignant etiologies but is only minimally beneficial in neoplastic etiologies.

Exact criteria for the implementation of invasive treatment are not well defined, but several authors advocate its use if conservative treatment has not resolved the chylothorax after 2 weeks, in higher-output chylothoraces, and in underlying neoplastic etiologies. Invasive treatments include surgical thoracic duct ligation, pleurodesis, and thoracic duct embolization (TDE). Less commonly, tunneled drains or pleural shunt procedures are performed, although prolonged drainage is not recommended as a long-term option because of increased risk of complications. Although the technical success of direct surgical ligation is high, these debilitated patients are at increased risk for postoperative adhesions, infection, and poor wound healing. Reported postoperative mortality rates for patients who have failed conservative management range from 4.5% to as high as 50%.

TDE is a percutaneous alternative to thoracic duct ligation. TDE allows for direct embolization (Type I) or needle disruption of the thoracic duct (Type II). Whereas the former directly treats the focus of injury, the latter is purported to create a controlled leak and inflammatory reaction in the retroperitoneum, which collateralizes and diverts flow from the thoracic duct. Over several successive publications, one research group defined the technique and reported its feasibility. The initial series of 42 patients by these researchers revealed effective percutaneous treatment in >70% of cases. In 109 patients with traumatic thoracic duct leak, another group reported 90% clinical resolution postembolization and 72% clinical resolution of the chyle leak with thoracic duct disruption. A subsequent study reported that TDE for nontraumatic chylous effusions in 34 patients was primarily successful if there was thoracic duct occlusion and extravasation. Another study reported 85% technical success and 64% clinical success in 105 patients with all-cause chylous leaks. Additional series have yielded similar results. Collectively, TDE has higher clinical success treating traumatic compared with nontraumatic chyle leaks and with TDE compared with thoracic duct disruption. Overall, acute complications associated with TDE are minor and generally self-limited and are estimated at 2% to 6%. Long-term complications may be seen in up to 14% of patients and may include leg swelling, abdominal swelling, or chronic diarrhea.

Overview of Imaging Modalities

Different imaging studies serve different purposes in the evaluation and treatment of chylothorax.

Chest Radiography

Chest radiographs are routine examinations to evaluate dyspnea, particularly in postoperative scenarios and in patients who require intensive care. Radiographs can reliably detect pleural effusions or alternative diagnoses and monitor the position of support lines and tubes. Although there is a high sensitivity for pleural effusions, this technique cannot reliably characterize the type of effusion.

Ultrasound

Ultrasound (US) is sensitive for the detection of pleural fluid but cannot definitively discriminate between the types of pleural effusion. US is now commonly used to help guide thoracentesis. Similarly, US can be used to facilitate intranodal lymphangiography, which is becoming a more accepted technique. Beyond facilitating these procedures, the role of US is limited with regard to the evaluation and management of chylothorax.

Conventional Lymphangiography

Lymphangiography has historically been used to opacify lymphatic vessels, detect lymph nodes and metastatic lesions, and evaluate lymphatic flow. Technological improvements in alternative diagnostic modalities led to an abandonment of this technique for oncologic purposes because it was technically challenging and time intensive, provided less information, and was more invasive. Although proficiency and training in the performance of lymphangiograms decreased, the utility of lymphangiography to demonstrate lymphatic leak became an established indication.

Traditionally, lymphangiography is performed from a pedal approach with the patient in a supine position. In this technique, a dye such as methylene blue that stains the lymphatics is injected into the web spaces between the toes. After the lymphatic vessel fills with the dye, the tissue overlying the lymphatic vessel is incised vertically, the lymphatic vessel is carefully skeletonized, and a 30-gauge lymphangiography needle is used to access the vessel. After securing the lymphatic access, 6 to 8 mL of ethiodized oil is instilled at a rate of 4 to 10 mL/h. Serial spot radiographs from the foot to the chest are acquired approximately every 10 to 15 minutes to follow the progression of the ethiodized oil as it ascends.

More recently, an interest in nodal lymphangiography has developed. In this alternative approach, an inguinal lymph node is targeted with a 25- to 26-gauge spinal needle under US guidance. The needle is positioned between the hilum and cortex of a lymph node. Hand injection of ethiodized oil at a rate of 1 mL per 5 to 7 minutes is then initiated for a total volume of 6 to 10 mL. Serial spot radiographs of the pelvis, abdomen, and thorax are then acquired to follow the progression of ethiodized oil. Intranodal lymphangiography appears to decrease procedure time, is less technically challenging, and decreases the risk of wound infection when compared to pedal lymphangiography.

Lymphangiography is able to define the site of the leak, diagnose alternative lymphatic vessel diseases, and prevent unnecessary procedures. Several authors have documented the therapeutic benefit of lymphangiography to occlude the site of leakage in 37% to 70% of patients without additional procedure. Moreover, as detailed earlier, lymphangiography is intrinsic to the performance of TDE and guides the transabdominal access to the cisterna chyli and thoracic duct.

Nuclear Lymphoscintigraphy

Nuclear lymphoscintigraphy images the pathways of lymphatic flow and lymph nodes and is most commonly used to identify draining lymph nodes proximal to neoplasms. A few reports of lymphoscintigraphy with technetium (Tc)-99m–labeled radiotracers or orally administered iodine I-123-labeled 15-(4-iodophenyl)-3(R,S)-methylpentadecanoic acid are present and demonstrate the potential to visualize the anatomic configuration of the thoracic duct, reveal abnormal lymphatic drainage patterns, and potentially detect leaks. However, aside from a few small series, little is present in the literature to support its routine use in the diagnosis or treatment of chylothorax.

Magnetic Resonance Imaging Chest and Abdomen

Visualization of the cisterna chyli, thoracic duct, and tributary lymphatic vessels with magnetic resonance imaging (MRI) was described in healthy volunteers as early as 1999. Initial MR lymphangiography technique involved unenhanced thin-collimated axial and coronal sequences similar to magnetic resonance cholangiopancreatography. Further refinements of sequences, particularly heavily T2-weighted sequences with and without and fat suppression, combined with 3-dimensional (3-D) techniques, maximum-intensity projections, and higher magnetic fields, increased the reliability and quality of MR lymphangiography. Morphological features of the cisterna chyli and thoracic duct can be noted with identification of these structures in over 90% of preoperative patients, potentially providing valuable information and decreasing their risk of lymphatic leak.

The vast majority of studies are performed with unenhanced techniques, although delayed-phase cisterna chyli enhancement has been noted. Respiratory gating and further technical refinements have the potential to better elucidate minor lymphatic vessels and lymphatic vessels in antidependent areas, which may not be seen through conventional lymphangiography. Recent studies are beginning to document the feasibility of using gadolinium-based contrast material injection within groin lymph nodes or in the web spaces between toes. Following the contrast material injection, patients are imaged with MRI. High image quality of lymph nodes, central lymphatics, and flow patterns within the lymphatics has been described, but these are preliminary research experiences and are not widely available.

Computed Tomography Chest and Abdomen

Older studies noted that noncontrast computed tomography (CT) visualizes the cisterna chyli in 1.7% of cases and could differentiate this from adjacent anatomy by its low attenuation, continuity with the thoracic duct, and tubular nature. At least some portion of the thoracic duct was visualized in 55% of patients in a different series.

Although MRI more reliably visualized more segments of the thoracic duct than CT, the addition of CT increased the number of visualized segments. More recent studies with 1-mm collimation and multiplanar reformation were able to identify the thoracic duct and cisterna chyli in nearly 100% of CT scans with normal anatomy. Older reports using a combination of lymphangiography and CT did not find any additional value of CT in diagnosing the lymphatic injury, although in a more recent series, a combination of CT and unilateral pedal lymphangiography was able to identify the cause and locate the leak in 75% of idiopathic chylothoraces after failure of thoracic duct ligation. Moreover, in this series of 24 patients, the lack of thoracic duct leakage was managed with nonoperative therapy with higher success rates. No evidence is present to suggest a role for intravenous contrast material.

When the underlying etiology of chylothorax is unknown or nontraumatic, the speed, sensitivity, and specificity of CT imaging can narrow the broader differential diagnosis.

Discussion of the Imaging Modalities by Variant

Variant 1: Chylothorax Treatment Planning: Traumatic Etiology

Traumatic chylothoraces are a result of direct injury to thoracic lymphatics. Iatrogenic traumatic chylothorax complicates up to 4% of esophageal resections. Lung cancer resections, cardiovascular surgeries, and spinal surgeries can also be complicated by chylothorax, although at a lesser rate. Noniatrogenic causes of traumatic chylothorax include penetrating trauma, fracture-dislocation of the spine, and hyperflexion injuries. Generally, the causative etiology is known in the traumatic setting. Sampling the pleural effusion confirms the diagnosis of chylothorax. Imaging a patient with a known traumatic chylothorax serves only to confirm the diagnosis and assist in therapeutic planning.

Chest Radiography

In the setting of a traumatic injury to the thoracic duct, most commonly postoperative or mechanical trauma, chest radiographs can confirm the presence of pleural fluid and lateralize the process and are routinely acquired in the daily evaluation of supportive lines and tubes.

Ultrasound

US can be helpful in the guidance of thoracentesis and intranodal injection during lymphangiography. Otherwise, US has little, if any, diagnostic role in the setting of a known traumatic chylothorax.

Conventional Lymphangiography

Conventional lymphangiography is the gold standard for visualization of lymph nodes, lymphatic vessels, cisterna chyli, the thoracic duct, and sites of injury. Lymphangiography alone has been shown to be therapeutic in a small percentage of patients, irrespective of attempts at TDE or disruption. When performed as a prelude to TDE, the combination is particularly effective in treating traumatic chylothorax, with technical and clinical success rates approaching 90%.

Nuclear Lymphoscintigraphy

Although nuclear lymphoscintigraphy may be able to confirm a lymphatic leak and identify the site, little evidence is present to support its routine use. Moreover, this adds little to the clinical care of a patient as the traumatic etiology is usually known and any information gained would be redundant if conventional lymphangiography was performed as part of TDE.

Magnetic Resonance Imaging Chest and Abdomen

The diagnostic benefit of MRI is negated in the setting of traumatic chylothoraces. However, the ability of MRI to map the lymphatic system can be of benefit in select cases where identifying the cisterna chyli and/or thoracic duct is difficult or conventional lymphangiography is unsuccessful.

Computed Tomography Chest and Abdomen

CT imaging is able to visualize portions of lymphatic system but provides less anatomic detail than MRI. If the etiology is known, CT of the chest and abdomen, with or without intravenous contrast material, has little value in that it does not help guide therapy directed at chylothorax in most cases.

Variant 2: Chylothorax Treatment Planning: Nontraumatic or Unknown Etiology

Nontraumatic chylothorax accounts for approximately 46% of chylothoraces and can be subcategorized as resulting from malignancy, as occurs in 18% of all chylothoraces, or nonmalignant etiologies, which account for 28% of all chylothoraces. Of the malignant etiologies, lymphoma is the leading cause, accounting for 75% of all malignant chylothoraces. Nonmalignant, nontraumatic chylothorax has been described in lymphangioleiomyomatosis, sarcoidosis, cirrhosis, heart failure, nephrotic syndrome, venous thrombosis, filariasis, venolymphatic malformations, and a variety of other congenital, idiopathic, and systemic diseases. Approximately 9% of all chylous effusions are idiopathic. Imaging a patient with either a nontraumatic chylothorax or a chylothorax of unknown etiology serves to narrow the differential diagnosis, further characterize the underlying cause and its severity, and assist in treatment planning.

Most patients with nontraumatic chylothoraces or chylothoraces of unknown etiologies present with acute respiratory illness (ARI), which consists of 1 or more of the following: cough, sputum production, chest pain, or dyspnea (with or without fever). The evaluation of ARI has been addressed by the American College of Radiology (ACR), and the imaging evaluation includes chest radiography and chest CT. The consistent finding of chylothorax on initial imaging is the presence of a pleural effusion, which is a common medical problem with more than 50 recognized causes. Pleural fluid studies are necessary for definitive diagnosis and to narrow the cause etiology of chylothorax.

Chest Radiography

Chest radiographs are routine examinations to evaluate dyspnea and have been designated as “usually appropriate” in the workup of ARI. Radiographs can reliably detect pleural effusions or alternative diagnoses and monitor the position of support lines and tubes. This technique cannot reliably characterize the type of effusion.

Ultrasound

US reliably detects pleural fluid but cannot definitively discriminate between the types of pleural effusion and provides minimal additional information to narrow the differential diagnosis. US can be helpful in the guidance of thoracentesis and intranodal injection during lymphangiography.

Conventional Lymphangiography

Conventional lymphangiography is the gold standard for visualization of lymph nodes, lymphatic vessels, cisterna chyli, and the thoracic duct and for detection of lymphatic leakage. In a nontraumatic or idiopathic chylothorax, conventional lymphangiography may help diagnose lymphatic vessel diseases and anatomic abnormalities and prevent unnecessary procedures. However, compared with traumatic chylothorax and particularly in the setting of a systemic disease, conventional lymphangiography does not always elucidate the underlying etiology. Additionally, TDE is less clinically effective in a nontraumatic chylothorax unless thoracic duct occlusion or extravasation is present.

Nuclear Lymphoscintigraphy

Nuclear lymphoscintigraphy has only a few reports that suggest it may be able to localize the site of chylous leak, particularly if used with 3-D single-photon emission CT/CT techniques. Scintigraphic imaging alone provides limited localizing information and would not reliably narrow the differential diagnosis.

Magnetic Resonance Imaging Chest and Abdomen

MRI accurately visualizes lymphatic structures without intravenous contrast material, depicting abnormal lymphatic malformations. With the addition of contrast material, MRI can characterize mediastinal masses, pleural-based lesions, and chest wall pathology. However, thoracic MRI has limited utility for parenchymal lung pathology.

Computed Tomography Chest and Abdomen

Although CT imaging is inferior to MRI in visualizing lymphatics, it is a highly sensitive and specific examination to narrow a broader differential diagnosis of thoracic and abdominal pathology Moreover, it is a rapid examination that is easily tolerated by a supine patient. Intravenous contrast material accurately defines vascular and mediastinal structures and provides information on enhancement characteristics, which is a consideration when the etiology of chylothorax is unknown.

Summary of Recommendations

• In traumatic chylothorax, chest radiographs are useful to confirm the presence of pleural fluid, lateralize the process, and monitor the position of support lines and tubes. If further evaluation is warranted, lymphangiography can precisely define the leak and offer therapeutic benefit, particularly if paired with TDE. MRI and CT imaging are reserved for cases when lymphangiography is not diagnostic.
• Nontraumatic chylothorax can arise from a variety of disorders and may be a diagnostic dilemma. Chest radiographs are useful to confirm the presence of pleural fluid and lateralize the process. MRI and CT imaging are useful to narrow the differential diagnosis. Lymphangiography is helpful if a minimally invasive approach to treatment is desired.

Abbreviations

• CT, computed tomography
• IV, intravenous
• MRI, magnetic resonance imaging
• Tc-99m, technetium-99 metastable
• US, ultrasound

Relative Radiation Level Designations

Relative Radiation Level*	Adult Effective Dose Estimate Range	Pediatric Effective Dose Estimate 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 (e.g., region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as "Varies."

Clinical Algorithm(s)

Algorithms were not developed from criteria guidelines.

Scope

Disease/Condition(s)

Chylothorax

Guideline Category

• Evaluation
• Management
• Treatment

Clinical Specialty

• Family Practice
• Internal Medicine
• Nuclear Medicine
• Pulmonary Medicine
• Radiology
• Thoracic Surgery

Intended Users

• Advanced Practice Nurses
• Health Care Providers
• Health Plans
• Hospitals
• Physician Assistants
• Physicians
• Students
• Utilization Management

Guideline Objective(s)

To evaluate the appropriateness of imaging procedures for treatment planning for chylothorax

Target Population

Patients with chylothorax of traumatic or nontraumatic or unknown etiology

Interventions and Practices Considered

1. X-ray, chest
2. Lymphangiography, chest and abdomen
3. Magnetic resonance imaging (MRI), chest and abdomen * Without intravenous (IV) contrast * Without and with IV contrast
4. Computed tomography (CT), chest and abdomen * Without intravenous (IV) contrast * Without and with IV contrast * With IV contrast
5. Technetium-99 metastable (Tc-99m) lymphoscintigraphy, chest and abdomen
6. Ultrasound (US), chest and abdomen

Major Outcomes Considered

• Utility of imaging procedures in treatment planning for chylothorax
• Sensitivity, specificity, and accuracy of imaging procedures in treatment planning of chylothorax

Methodology

Methods Used to Collect/Select the Evidence

• Hand-searches of Published Literature (Primary Sources)
• Hand-searches of Published Literature (Secondary Sources)
• Searches of Electronic Databases

Description of Methods Used to Collect/Select the Evidence

Literature Search Summary

A literature search was conducted in March 2015 to identify evidence for the ACR Appropriateness Criteria ® Chylothorax Treatment Planning topic. Using the search strategy described in the literature search companion (see the “Availability of Companion Documents” field), 117 articles were found. Forty articles were used in the topic. The remaining articles were not used due to either poor study design, the articles were not relevant or generalizable to the topic, or the results were unclear or biased.

The author added 12 citations from bibliographies, Web sites, or books that were not found in the literature search.

See also the American College of Radiology (ACR) Appropriateness Criteria® literature search process document (see the “Availability of Companion Documents” field) for further information.

Number of Source Documents

The literature search conducted in March 2015 identified 40 articles that were used in the topic. The author added 12 citations from bibliographies, Web sites, or books that were not found in the literature search.

Methods Used to Assess the Quality and Strength of the Evidence

• Weighting According to a Rating Scheme (Scheme Given)

Rating Scheme for the Strength of the Evidence

Definitions of Study Quality Categories

Category 1 - The study is well-designed and accounts for common biases.

Category 2 - The study is moderately well-designed and accounts for most common biases.

Category 3 - The study has important study design limitations.

Category 4 - The study or source is not useful as primary evidence. The article may not be a clinical study, the study design is invalid, or conclusions are based on expert consensus.

The study does not meet the criteria for or is not a hypothesis-based clinical study (e.g., a book chapter or case report or case series description);

Or

The study may synthesize and draw conclusions about several studies such as a literature review article or book chapter but is not primary evidence;

Or

The study is an expert opinion or consensus document.

Category M - Meta-analysis studies are not rated for study quality using the study element method because the method is designed to evaluate individual studies only. An "M" for the study quality will indicate that the study quality has not been evaluated for the meta-analysis study.

Methods Used to Analyze the Evidence

• Systematic Review with Evidence Tables

Description of the Methods Used to Analyze the Evidence

The topic author assesses the literature then drafts or revises the narrative summarizing the evidence found in the literature. American College of Radiology (ACR) staff drafts an evidence table based on the analysis of the selected literature. These tables rate the study quality for each article included in the narrative.

The expert panel reviews the narrative, evidence table and the supporting literature for each of the topic-variant combinations and assigns an appropriateness rating for each procedure listed in the variant table(s). Each individual panel member assigns a rating 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).

Methods Used to Formulate the Recommendations

• Expert Consensus (Delphi)

Description of Methods Used to Formulate the Recommendations

Rating Appropriateness

The American College of Radiology (ACR) Appropriateness Criteria (AC) methodology is based on the RAND Appropriateness Method. The appropriateness ratings for each of the procedures or treatments included in the AC topics are determined using a modified Delphi method. A series of surveys are conducted to elicit each panelist’s expert interpretation of the evidence, based on the available data, regarding the appropriateness of an imaging or therapeutic procedure for a specific clinical scenario. The expert panel members review the evidence presented and assess the risks or harms of doing the procedure balanced with the benefits of performing the procedure. The direct or indirect costs of a procedure are not considered as a risk or harm when determining appropriateness. When the evidence for a specific topic and variant is uncertain or incomplete, expert opinion may supplement the available evidence or may be the sole source for assessing the appropriateness.

The appropriateness is represented on an ordinal scale that uses integers from 1 to 9 grouped into three categories: 1, 2, or 3 are in the category “usually not appropriate” where the harms of doing the procedure outweigh the benefits; and 7, 8, or 9 are in the category “usually appropriate” where the benefits of doing a procedure outweigh the harms or risks. The middle category, designated “may be appropriate,” is represented by 4, 5, or 6 on the scale. The middle category is when the risks and benefits are equivocal or unclear, the dispersion of the individual ratings from the group median rating is too large (i.e., disagreement), the evidence is contradictory or unclear, or there are special circumstances or subpopulations which could influence the risks or benefits that are embedded in the variant.

The ratings assigned by each panel member are presented in a table displaying the frequency distribution of the ratings without identifying which members provided any particular rating. To determine the panel’s recommendation, the rating category that contains the median group rating without disagreement is selected. This may be determined after either the first or second rating round. If there is disagreement after the first rating round, a conference call is scheduled to discuss the evidence and, if needed, clarify the variant or procedure description. If there is disagreement after the second rating round, the recommendation is “May be appropriate.”

This modified Delphi method enables each panelist to articulate his or her individual interpretations of the evidence or expert opinion without excessive influence from fellow panelists in a simple, standardized, and economical process. For additional information on the ratings process see the Rating Round Information document.

Additional methodology documents, including a more detailed explanation of the complete topic development process and all ACR AC topics can be found on the ACR Web site (see also the “Availability of Companion Documents” field).

Rating Scheme for the Strength of the Recommendations

Not applicable

Cost Analysis

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

Method of Guideline Validation

• Internal Peer Review

Description of Method of Guideline Validation

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

Evidence Supporting the Recommendations

Type of Evidence Supporting the Recommendations

The recommendations are based on analysis of the current medical evidence literature and the application of the RAND/UCLA appropriateness method and expert panel consensus.

Summary of Evidence

Of the 52 references cited in the ACR Appropriateness Criteria ® Chylothorax Treatment Planning document, 22 are categorized as therapeutic references, including 6 good-quality studies and 8 quality studies that may have design limitations. Additionally, 30 references are categorized as diagnostic references, including 3 good-quality studies and 5 quality studies that may have design limitations. There are 30 references that may not be useful as primary evidence.

Although there are references that report on studies with design limitations, 9 good-quality studies provide good evidence.

Benefits/Harms of Implementing the Guideline Recommendations

Potential Benefits

Selection of appropriate imaging modalities for chylothorax treatment planning

Potential Harms

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. 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).

Qualifying Statements

Qualifying Statements

• 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 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 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.
• ACR 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 society endorsement of the final document.

Implementation of the Guideline

Description of Implementation Strategy

An implementation strategy was not provided.

Institute of Medicine (IOM) National Healthcare Quality Report Categories

IOM Care Need

• Getting Better

IOM Domain

• Effectiveness

Identifying Information and Availability

Bibliographic Source(s)

• Majdaluny BS, Murrey DA Jr, Kapoor BS, Cain TR, Ganguli S, Kent MS, Maldonado F, McBride JJ, Minocha J, Reis SP, Lorenz JM, Kalva SP, Expert Panel on Vascular Imaging and Interventional Radiology. ACR Appropriateness Criteria® chylothorax treatment planning. Reston (VA): American College of Radiology (ACR); 2016. 10 p. [52 references]

Adaptation

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

Date Released

2016

Guideline Developer(s)

• American College of Radiology - Medical Specialty Society

Source(s) of Funding

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

Guideline Committee

Committee on Appropriateness Criteria, Expert Panel on Vascular Imaging and Interventional Radiology

Composition of Group That Authored the Guideline

Panel Members : Bill S. Majdalany, MD ( Principal Author and Panel Vice-chair, Vascular Imaging ); Douglas A. Murrey Jr, MD, MS ( Research Author ); Baljendra S. Kapoor, MD ( Panel Chair, Interventional Radiology ); Thomas R. Cain, MD; Suvranu Ganguli, MD; Michael S. Kent, MD; Fabien Maldonado, MD; Joseph J. McBride, MD; Jeet Minocha, MD; Stephen P. Reis, MD; Jonathan M. Lorenz, MD ( Specialty Chair, Interventional Radiology ); Sanjeeva P. Kalva, MD ( Panel Chair, Vascular Imaging )

Financial Disclosures/Conflicts of Interest

Not stated

Guideline Status

This is the current release of the guideline.

This guideline meets NGC’s 2013 (revised) inclusion criteria.

Guideline Availability

Available from the American College of Radiology (ACR) Web site.

Availability of Companion Documents

The following are available:

• ACR Appropriateness Criteria®. Overview. Reston (VA): American College of Radiology; 2015 Oct. 3 p. Available from the American College of Radiology (ACR) Web site.
• ACR Appropriateness Criteria®. Literature search process. Reston (VA): American College of Radiology; 2015 Feb. 1 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Evidence table development. Reston (VA): American College of Radiology; 2015 Nov. 5 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Topic development process. Reston (VA): American College of Radiology; 2015 Nov. 2 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Rating round information. Reston (VA): American College of Radiology; 2015 Apr. 5 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Radiation dose assessment introduction. Reston (VA): American College of Radiology; 2016. 4 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Manual on contrast media. Reston (VA): American College of Radiology; 2016. 128 p. Available from the ACR Web site.
• ACR Appropriateness Criteria®. Procedure information. Reston (VA): American College of Radiology; 2016 May. 2 p. Available from the ACR Web site.
• ACR Appropriateness Criteria® chylothorax treatment planning. Evidence table. Reston (VA): American College of Radiology; 2016. 21 p. Available from the ACR Web site.
• ACR Appropriateness Criteria® chylothorax treatment planning. Literature search. Reston (VA): American College of Radiology; 2016. 1 p. Available from the ACR Web site.

Patient Resources

None available

NGC Status

This NGC summary was completed on March 17, 2017.

Copyright Statement

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

Disclaimer

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