Workup of Pleural Effusion or Pleural Disease

New 2023

ACR Appropriateness Criteria

1 Workup of Pleural Effusion or Pleural Disease

American College of Radiology

ACR Appropriateness Criteria

Workup of Pleural Effusion or Pleural Disease

Variant 1: Recent pneumonia with suspected parapneumonic effusion or empyema. Initial imaging.

Procedure Appropriateness Category Relative Radiation Level

Radiography chest Usually Appropriate

☢

CT chest with IV contrast Usually Appropriate

☢☢☢

US chest May Be Appropriate (Disagreement)

CT chest without IV contrast May Be Appropriate

☢☢☢

MRI chest without and with IV contrast Usually Not Appropriate

MRI chest without IV contrast Usually Not Appropriate

CT chest without and with IV contrast Usually Not Appropriate

☢☢☢

CTA chest with IV contrast Usually Not Appropriate

☢☢☢

Variant 2: Recent minor blunt trauma with suspected pleural effusion. Initial imaging.

Procedure Appropriateness Category Relative Radiation Level

Radiography chest Usually Appropriate

☢

CT chest with IV contrast Usually Appropriate

☢☢☢

US chest May Be Appropriate (Disagreement)

CT chest without IV contrast May Be Appropriate

☢☢☢

CTA chest with IV contrast May Be Appropriate (Disagreement)

☢☢☢

Image-guided aspiration chest Usually Not Appropriate Varies

MRI chest without and with IV contrast Usually Not Appropriate

MRI chest without IV contrast Usually Not Appropriate

CT chest without and with IV contrast Usually Not Appropriate

☢☢☢

Variant 3: Dyspnea, cough, or chest pain with suspected pleural effusion, noninfectious. Initial imaging.

Procedure Appropriateness Category Relative Radiation Level

Radiography chest Usually Appropriate

☢

CT chest with IV contrast Usually Appropriate

☢☢☢

US chest May Be Appropriate (Disagreement)

CT chest without IV contrast May Be Appropriate

☢☢☢

MRI chest without and with IV contrast Usually Not Appropriate

MRI chest without IV contrast Usually Not Appropriate

CT chest without and with IV contrast Usually Not Appropriate

☢☢☢

CTA chest with IV contrast Usually Not Appropriate

☢☢☢

ACR Appropriateness Criteria

2 Workup of Pleural Effusion or Pleural Disease

Variant 4: Pleural effusion incidentally detected on incomplete thoracic imaging study. Next imaging

study.

Procedure Appropriateness Category Relative Radiation Level

US chest May Be Appropriate (Disagreement)

Radiography chest May Be Appropriate (Disagreement)

☢

CT chest with IV contrast May Be Appropriate (Disagreement)

☢☢☢

MRI chest without and with IV contrast Usually Not Appropriate

MRI chest without IV contrast Usually Not Appropriate

CT chest without and with IV contrast Usually Not Appropriate

☢☢☢

CT chest without IV contrast Usually Not Appropriate

☢☢☢

CTA chest with IV contrast Usually Not Appropriate

☢☢☢

ACR Appropriateness Criteria

3 Workup of Pleural Effusion or Pleural Disease

WORKUP OF PLEURAL EFFUSION OR PLEURAL DISEASE

Expert Panel on Thoracic Imaging: Michael F. Morris, MD

; Travis S. Henry, MD

; Constantine A. Raptis, MD

;

Alpesh N. Amin, MD, MBA

; William F. Auffermann, MD, PhD

; Benjamin W. Hatten, MD, MPH

;

Aine Marie Kelly, MBBCh

; Andrew R. Lai, MD, MPH

; Maria D. Martin, MD

; Kim L. Sandler, MD

;

Arlene Sirajuddin, MD

; Devaki Shilpa Surasi, MD

; Jonathan H. Chung, MD.

Summary of Literature Review

Introduction/Background

Under normal circumstances, approximately 0.1 to 0.2 mL/kg body weight of pleural fluid resides in the pleural

space [1]. Abnormal accumulation of pleural fluid is the most common clinical manifestation of pleural disease [2],

typically caused by increased pulmonary capillary pressure, increased pleural membrane permeability, decreased

oncotic pressure, or lymphatic obstruction [3]. Pleural effusions are categorized as transudative or exudative [4],

with transudative effusions usually reflecting the sequala of a systemic etiology and exudative effusions usually

resulting from a process localized to the pleura [5]. Common causes of transudative pleural effusions include

congestive heart failure, cirrhosis, and renal failure, whereas exudative effusions are typically due to infection,

malignancy, or autoimmune disorders [6], emphasizing the importance of prompt diagnosis to aid in patient

management [7]. In general, physical examination findings have a lower positive likelihood ratio for detection of

pleural effusions [8], supporting the use of imaging to aid in identification of clinically significant pleural effusions.

When imaging pleural effusions, chest radiographs can typically detect >75 mL on the lateral view and >175 mL

on the frontal view [9]. Thoracic ultrasound (US) can detect >20 mL of pleural fluid [10]. Chest CT can detect >10

mL of pleural fluid, and is considered the reference standard for imaging [11].

Special Imaging Considerations

For the purposes of distinguishing between CT and CT angiography (CTA), ACR Appropriateness Criteria topics

use the definition in the

ACR–NASCI–SIR–SPR Practice Parameter for the Performance and Interpretation of Body

Computed Tomography Angiography (CTA) [12]:

“CTA uses a thin-section CT acquisition that is timed to coincide with peak arterial and/or venous

enhancement, depending on the vascular structures to be analyzed. The resultant volumetric data

set is interpreted using primary transverse reconstructions as well as multiplanar reformations and

3-D renderings.”

All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with

contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a

required element. This corresponds to the definitions that the CMS has applied to the Current Procedural

Terminology codes.

Initial Imaging Definition

Initial imaging is defined as imaging at the beginning of the care episode for the medical condition defined by the

variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when:

• There are procedures that are equivalent alternatives (ie, only one procedure will be ordered to

provide the clinical information to effectively manage the patient’s care)

University of Arizona College of Medicine, Tucson, Arizona.

Panel Chair, Duke University, Durham, North Carolina.

Panel Vice-Chair, Mallinckrodt

Institute of Radiology, Saint Louis, Missouri.

University of California Irvine, Irvine, California; American College of Physicians.

University of Utah, Salt

Lake City, Utah.

University of Colorado School of Medicine Anschutz Medical Campus, Aurora, Colorado; American College of Emergency Physicians.

Emory University Hospital, Atlanta, Georgia.

University of California San Francisco, San Francisco, California, Hospitalist.

University of Wisconsin School

of Medicine and Public Health, Madison, Wisconsin.

Vanderbilt University Medical Center, Nashville, Tennessee.

National Institutes of Health, Bethesda,

Maryland.

The University of Texas MD Anderson Cancer Center, Houston, Texas; Commission on Nuclear Medicine and Molecular Imaging.

Specialty

Chair, University of Chicago, Chicago, Illinois.

The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness

Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final

document by individual contributors or their respective organization.

Reprint requests to: pub[email protected]

ACR Appropriateness Criteria

4 Workup of Pleural Effusion or Pleural Disease

• There are complementary procedures (ie, more than one procedure is ordered as a set or

simultaneously where each procedure provides unique clinical information to effectively manage

the patient’s care).

Discussion of Procedures by Variant

Variant 1: Recent pneumonia with suspected parapneumonic effusion or empyema. Initial imaging.

CT Chest With IV Contrast

Current American Association for Thoracic Surgery consensus guidelines recommend CT chest with intravenous

(IV) contrast in cases of suspected parapneumonic effusion (class IIa) [13]. A recent meta-analysis reported 5 chest

CT findings most commonly associated with the diagnosis of empyema: pleural enhancement (sensitivity 84%,

95% confidence interval [CI], 62%-94%; specificity 83%, 95% CI, 75%-89%), pleural thickening (sensitivity 68%,

95% CI, 56%-77%; specificity 87%, 95% CI, 80%-92%), loculation (sensitivity 52%, 95% CI, 44%-59%;

specificity 89%; 95% CI, 82%-94%), extrapleural fat proliferation (sensitivity 53%, 95% CI, 47%-60%; specificity

91%, 95% CI, 82%-96%), and increased attenuation of the extrapleural fat (sensitivity 39%, 95% CI, 32%-48%;

specificity 97%, 95% CI, 94%-98%) [14]. Of note, these pooled sensitivities and specificities include CT chest with

IV contrast or CT chest without IV contrast. Pleural enhancement has the highest area under curve for the diagnosis

of empyema (0.86) and for distinguishing between simple parapneumonic effusion and empyema (0.83) [14]. In a

secondary analysis of the Multi-centre Intra-pleural Sepsis Trial (MIST) 2 trial of patients with laboratory proven

pleural infection, the combination of parietal pleural enhancement and pleural thickening was seen in 98.7% of

patients (95% CI, 92.8%-99.8%) on pleural-phase contrast-enhanced CT [15]. The presence of pleural enhancement

with pleural gas/microbubbles [16] or larger pleural effusion size [17] also boosts the accuracy for identifying

parapneumonic effusions requiring thoracentesis [16,17]. Parapneumonic effusions <2.5 cm in anteroposterior (AP)

dimension can often be managed without thoracentesis [18]. From a technical perspective, acquiring the CT scan

60 seconds after the IV contrast bolus optimizes visualization of the pleura [19,20].

CT Chest Without and With IV Contrast

There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging of

recent pneumonia with suspected parapneumonic effusion or empyema.

CT Chest Without IV Contrast

There is no relevant literature to support the use of CT chest without IV contrast in the initial imaging of recent

pneumonia with suspected parapneumonic effusion or empyema. If a noncontrast CT is obtained, 4 out of 5 chest

CT findings most commonly associated with the diagnosis of empyema in a recent meta-analysis may be ascertained

without IV contrast: pleural thickening (sensitivity 68%, 95% CI, 56%-77%; specificity 87%; 95% CI, 80%-92%),

loculation (sensitivity 52%, 95% CI, 44%-59%; specificity 89%; 95% CI, 82%-94%), fat thickening (sensitivity

53%, 95% CI, 47%-60%; specificity 91%; 95% CI, 82%-96%), and fat stranding (sensitivity 39%, 95% CI, 32%-

48%; specificity 97%; 95% CI, 94%-98%) [14]. Of note, these pooled sensitivities and specificities include CT

chest with IV contrast or CT chest without IV contrast. Gas in the pleural space is another specific marker for

complicated parapneumonic effusion, with specificities ranging from 81% (95% CI, 73%-87%) to 96% (95% CI,

86%-99%) [16,17]. Parapneumonic effusions <2.5 cm in AP dimension can often be managed without thoracentesis

[18].

CTA Chest With IV Contrast

There is no relevant literature to support the use of CTA chest with IV contrast in the initial imaging of recent

pneumonia with suspected parapneumonic effusion or empyema. Note that CTA often employs contrast timing that

is earlier than 60 seconds and therefore does not allow sufficient time for pleural enhancement.

MRI Chest Without and With IV Contrast

There is no relevant literature to support the use of MRI chest without and with IV contrast in the initial imaging of

recent pneumonia with suspected parapneumonic effusion or empyema in adults. In case reports, MRI chest without

and with IV contrast has been used as an adjunctive modality for the diagnosis of empyema necessitans [21]. In

pediatric patients, limited data suggests MRI is noninferior to CT chest with IV contrast for the diagnosis of

empyema [22-24].

MRI Chest Without IV Contrast

There is no relevant literature to support the use of MRI chest without IV contrast in the initial imaging of recent

pneumonia with suspected parapneumonic effusion or empyema. In small studies, diffusion weighted imaging [25]

ACR Appropriateness Criteria

5 Workup of Pleural Effusion or Pleural Disease

and T1 mapping [26] have shown promise in distinguishing exudative from transudative pleural effusions without

contrast material.

Radiography Chest

Consensus recommendations endorse chest radiography as the initial imaging modality for patients with recent

pneumonia and suspected pleural effusion [27,28]; however, there are limited empiric data to support these

recommendations. Posteroanterior (PA) and lateral radiographs have a significantly greater sensitivity for the

detection of parapneumonic effusions than single-view AP radiographs. In a retrospective analysis of patients from

the Community-Acquired Pneumonia Organization international cohort study, PA and lateral radiographs had a

sensitivity of 83.9% versus 67.3% for AP radiographs when using CT as the reference standard [29]. Single-view

PA, single lateral view, or single-view AP radiographs have been shown to have statistically equivalent sensitivities

for detection of parapneumonic effusions [30], with most missed parapneumonic effusions occurring in patients

with coexistent lower lobe consolidation [30]. The specificity of chest radiography for the detection of complicated

parapneumonic effusions, defined as those requiring thoracentesis, is modest. For example, in a retrospective study

of 66 patients undergoing thoracentesis for parapneumonic effusions, chest radiography had a specificity of 60%

for the detection of complicated parapneumonic effusions [31].

US Chest

Identification of a pleural effusion for possible US-guided thoracentesis is currently the primary reason for chest

US [32]. Current American Association for Thoracic Surgery consensus guidelines recommend thoracic US for the

diagnostic evaluation of pleural space infection (class I), typically occurring in patients with prior imaging

documenting the presence of a pleural effusion [13]. US findings of septations [33,34], increased echogenicity of

the pleural effusion [31,35], pleural thickening [36], and microbubbles [37] are associated with parapneumonic

effusion/empyema. A retrospective study of 66 patients with suspected parapneumonic effusion found that US chest

had a significantly higher specificity (90%, 95% CI, 76.3%-97.2%) and a nonsignificant difference in sensitivity

(69.2%, 95% CI, 48.2%-87.7%) compared with CT chest for the diagnosis of complicated parapneumonic effusion

[31]. A retrospective comparison of US chest and CT chest in pediatric patients found similar accuracy for the

detection of parapneumonic effusion [38].

Variant 2: Recent minor blunt trauma with suspected pleural effusion. Initial imaging.

The definition of minor blunt trauma involves isolated minor injury to the chest (eg, abrasions, contusion, or

ecchymoses) and/or no more than 2 rib fractures without flail chest [39,40]. For patients with major blunt trauma

please refer to the ACR Appropriateness Criteria

topic on “Major Blunt Trauma” [41].

CT Chest With IV Contrast

CT chest with IV contrast or CTA chest with IV contrast is regarded as the reference standard for the noninvasive

assessment of thoracic injury in patients with chest trauma, regardless of severity, and a clinical indication for

imaging [42]. The goal of CT chest with IV contrast is to identify hemothorax and contrast extravasation. The

incidence of pleural effusion on chest CT in minor blunt trauma is unknown; however, in a retrospective study of

2,440 multiple trauma patients undergoing whole body CT with IV contrast, 2.2% had an incidental pleural effusion

[43]. In a secondary analysis of the prospective observational NEXUS Chest and NEXUS Chest CT studies of

patients with major or minor blunt trauma, 1.8% of patients had a hemothorax on CTA chest with IV contrast [44].

CT Chest Without and With IV Contrast

There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging of

recent minor blunt trauma with suspected pleural effusion.

CT Chest Without IV Contrast

In patients with blunt trauma, regardless of severity and suspected pleural effusion, CT chest without IV contrast is

generally reserved for patients with renal dysfunction, risk factors for contrast nephropathy, or known contrast

allergy [45]. The incidence of pleural effusion on chest CT without IV contrast in minor blunt trauma is unknown.

On CT chest without IV contrast, a pleural effusion threshold of ≥15.6 Hounsfield units (HU) (sensitivity 86.8%,

specificity 97.4%) and HU ratio of pleural fluid to aortic blood of ≥30% (sensitivity 94.7%, specificity 83.3%) were

best able to discriminate hemothorax from pleural effusion after blunt chest trauma [45].

CTA Chest With IV Contrast

CTA chest with IV contrast or CT chest with IV contrast is regarded as the reference standard for the noninvasive

assessment of thoracic injury in patients with chest trauma and a clinical indication for imaging [42]. The goal of

ACR Appropriateness Criteria

6 Workup of Pleural Effusion or Pleural Disease

CTA chest with IV contrast is to identify hemothorax and contrast extravasation. The incidence of pleural effusion

on chest CT in minor blunt trauma is unknown; however, in a retrospective study of 2,440 multiple trauma patients

undergoing whole body CT with IV contrast, 2.2% had an incidental pleural effusion [43]. In a secondary analysis

of the prospective observational NEXUS Chest and NEXUS Chest CT studies of patients with major or minor blunt

trauma, 1.8% of patients had a hemothorax on CTA chest with IV contrast [44].

Image-Guided Aspiration Chest

There is no relevant literature to support the use of image-guided aspiration chest in the initial imaging of recent

minor blunt trauma with suspected pleural effusion.

MRI Chest Without and With IV Contrast

There is no relevant literature to support the use of MRI chest without and with IV contrast in the initial imaging of

recent minor blunt trauma with suspected pleural effusion.

MRI Chest Without IV Contrast

There is no relevant literature to support the use of MRI chest without IV contrast in the initial imaging of recent

minor blunt trauma with suspected pleural effusion.

Radiography Chest

Chest radiography is considered a first-line imaging test for patients with chest trauma and a clinical indication for

imaging [46]. In the prospective NEXUS Chest CT trial, blunt trauma patients without an abnormal chest radiograph

and 6 clinical criteria could avoid an unnecessary chest CT (sensitivity 99.2%; 95% CI, 95.4%-100%, specificity

20.8%; 95% CI, 19.2%-22.4%) [47]. A meta-analysis of the pooled sensitivity and specificity of chest radiographs

for the detection of hemothorax in patients with chest trauma was 54% (95% CI, 33%-75%) and 99% (95% CI,

94%-100%), respectively, when using chest CT as the reference standard [48]. A study of 24 patients using only

PA radiographs found a similar sensitivity of 62.5% and specificity of 100% for the detection of pleural effusions

in patients with chest trauma [49]. In 2 prospective series of patients with minor blunt thoracic trauma and an initial

normal chest radiograph, 7.4% to 11.8% had a pleural effusion on follow-up radiography within 2 weeks, clinically

ascribed as a delayed hemothorax [39,40]. A delayed hemothorax on chest radiographs after minor blunt thoracic

trauma was significantly more likely in patients with at least 1 fracture between the third and ninth ribs [50].

US Chest

The sensitivity and specificity of chest US for only minor blunt trauma has not been reported. Identification of a

hemothorax for possible US-guided thoracentesis is the primary reason for chest US [32]. A recent meta-analysis

reported chest US had a 60% sensitivity (95% CI, 31%-86%) and a 98% specificity (95% CI, 94%-99%) for

traumatic hemothorax [51].

Variant 3: Dyspnea, cough, or chest pain with suspected pleural effusion, noninfectious. Initial imaging.

CT Chest With IV Contrast

In patients with suspected malignant pleural effusion or suspected unilateral pleural effusion with an increased

pretest probability of malignancy, CT chest with IV contrast is recommended [52,53], although this is not limited

to patients with dyspnea, cough, or chest pain. Acquiring the CT scan 60 seconds after the contrast bolus improves

visualization of pleural abnormalities associated with malignancy [19].

CT Chest Without and With IV Contrast

There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging of

dyspnea, cough, or chest pain with suspected noninfectious pleural effusion.

CT Chest Without IV Contrast

There is no relevant literature to support the use of CT chest without IV contrast in the initial imaging of dyspnea,

cough, or chest pain with suspected noninfectious pleural effusion. Heart failure, liver failure, and renal failure are

common noninfectious causes of pleural effusion, and these patients may present with dyspnea, cough, or chest

pain and undergo CT chest without IV contrast as part of their diagnostic workup [54,55].

CTA Chest With IV Contrast

In patients with dyspnea, cough, or chest pain and suspected noninfectious pleural effusion, CTA chest with IV

contrast is typically performed when there is clinical concern for pulmonary embolism [56] or aortopathy [57].

Pleural effusions in these patients are usually small and not associated with adverse clinical outcomes [57,58].

ACR Appropriateness Criteria

7 Workup of Pleural Effusion or Pleural Disease

MRI Chest Without and With IV Contrast

There is no relevant literature to support the use of MRI chest without and with IV contrast in the initial imaging of

dyspnea, cough, or chest pain with suspected noninfectious pleural effusion. Incidental pleural effusions have been

reported in a minority of patients undergoing MRI with contrast for dyspnea, cough, or chest pain. For example,

6.6% (34/514) of patients had a moderate or large pleural effusion on contrast-enhanced MRA ordered for

pulmonary embolism evaluation [59], and 4.3% (17/399) patients had a pleural effusion on stress cardiac MRI for

possible acute coronary syndrome [60].

MRI Chest Without IV Contrast

There is no relevant literature to support the use of MRI chest without IV contrast in the initial imaging of dyspnea,

cough, or chest pain with suspected noninfectious pleural effusion.

Radiography Chest

Consensus recommendations endorse chest radiography as the initial imaging modality for patients with suspected

noninfectious pleural effusion [7,61]; however, there are limited empiric data to support these recommendations.

US Chest

Identification of a pleural effusion for possible US-guided thoracentesis is currently the primary reason for chest

US [32]. Chest US is increasingly used as part of the diagnostic pathway for patients in the emergency department

[62] and in the intensive care setting [63]. A recent meta-analysis found that chest US had a pooled sensitivity of

91% (95% CI, 83%-96%) and specificity of 92% (95% CI, 82%-97%) using CT as the reference standard for

identification of pleural effusion in patients in the intensive care unit [63]. Adding chest US to the conventional

diagnostic pathway has been shown to reduce the time to final diagnosis in the emergency department in patients

with infectious and noninfectious causes of dyspnea [64].

Variant 4: Pleural effusion incidentally detected on incomplete thoracic imaging study. Next imaging study.

The frequency of an incidental pleural effusion detected on an incomplete thoracic imaging study including neck,

spine, and abdomen varies based on the indication and type of imaging modality, in the range of 1% to 5% [65-71].

The clinical significance of these incidental pleural effusions is variable. In a retrospective study of patients

undergoing run-off CTA, 4.2% (9/214) had an incidental pleural effusion, leading to the diagnosis of pneumonia in

22% (2/9) and optimization of heart failure therapy in 44% (4/9) [72]. However, in a study of 352 patients

undergoing MRA of the abdomen, pelvis, and lower extremities, 2.9% had an incidental pleural effusion, and no

patients required follow-up diagnostic testing or change in therapy.

CT Chest With IV Contrast

There is no relevant literature to support the use of CT chest with IV contrast as the next imaging study following

a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-up CT chest

with IV contrast should be based on clinical assessment (eg, clinical suspicion of malignancy).

CT Chest Without and With IV Contrast

There is no relevant literature to support the use of CT chest without and with IV contrast as the next imaging study

following a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-

up CT chest without and with IV contrast should be based on clinical assessment.

CT Chest Without IV Contrast

There is no relevant literature to support the use of CT chest without IV contrast as the next imaging study following

a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-up CT chest

without IV contrast should be based on clinical assessment (eg, clinical suspicion of malignancy).

CTA Chest With IV Contrast

There is no relevant literature to support the use of CTA chest with IV contrast as the next imaging study following

a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-up CTA

chest with IV contrast should be based on clinical assessment.

MRI Chest Without and With IV Contrast

There is no relevant literature to support the use of MRI chest without and with IV contrast as the next imaging

study following a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a

follow-up MRI chest without and with IV contrast should be based on clinical assessment.

ACR Appropriateness Criteria

8 Workup of Pleural Effusion or Pleural Disease

MRI Chest Without IV Contrast

There is no relevant literature to support the use of MRI chest without IV contrast as the next imaging study

following a pleural effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-

up MRI chest without IV contrast should be based on clinical assessment.

Radiography Chest

There is no relevant literature to support the use of chest radiography as the next imaging study following a pleural

effusion incidentally detected on prior abdominal imaging. The recommendation for a follow-up chest radiograph

should be based on clinical assessment (eg, clinical suspicion of malignancy).

US Chest

There is no relevant literature to support the use of US chest as the next imaging study following a pleural effusion

incidentally detected on prior abdominal imaging. The recommendation for a follow-up US chest should be based

on clinical assessment.

Summary of Recommendations

• Variant 1: Radiography chest or CT chest with IV contrast is usually appropriate for the initial imaging for

patients with recent pneumonia with suspected parapneumonic effusion or empyema. These procedures are

equivalent alternatives (ie, only one procedure will be ordered to provide the clinical information to effectively

manage the patient’s care). If CT chest with IV contrast is performed, acquiring the CT scan 60 seconds after

the IV contrast bolus optimizes visualization of the pleura. The panel did not agree on recommending US chest

for patients with recent pneumonia with suspected parapneumonic effusion or empyema. There is insufficient

medical literature to conclude whether or not these patients would benefit from this modality. Imaging in this

patient population is controversial but may be appropriate.

• Variant 2: Radiography chest or CT chest with IV contrast is usually appropriate for the initial imaging for

patients with recent minor blunt trauma with suspected pleural effusion. These procedures are equivalent

alternatives (ie, only one procedure will be ordered to provide the clinical information to effectively manage

the patient’s care). The panel did not agree on recommending US chest or CTA chest with IV contrast for

patients’ with recent minor blunt trauma with suspected pleural effusion. There is insufficient medical

literature to conclude whether or not these patients would benefit from these modalities. Imaging in this patient

population is controversial but may be appropriate.

• Variant 3: Radiography chest or CT chest with IV contrast is usually appropriate for the initial imaging for

patients with dyspnea, cough, or chest pain with suspected pleural effusion with suspected noninfectious

pleural effusion. These procedures are equivalent alternatives (ie, only one procedure will be ordered to

provide the clinical information to effectively manage the patient’s care). If CT chest with IV contrast is

performed, acquiring the CT scan 60 seconds after the IV contrast bolus optimizes visualization of the pleura.

The panel did not agree on recommending US chest for patients’ with dyspnea, cough, or chest pain with

suspected noninfectious pleural effusion. There is insufficient medical literature to conclude whether or not

these patients would benefit from this modality. Imaging in this patient population is controversial but may be

appropriate.

• Variant 4: The panel did not agree on recommending US chest, radiography chest or CT chest with IV contrast

for patients’ with pleural effusion incidentally detected on incomplete thoracic imaging study. There is

insufficient medical literature to conclude whether or not these patients would benefit from these modalities.

Imaging in this patient population is controversial but may be appropriate.

Supporting Documents

The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list

. The

appendix includes the strength of evidence assessment and the final rating round tabulations for each

recommendation.

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

www.acr.org/ac

ACR Appropriateness Criteria

9 Workup of Pleural Effusion or Pleural Disease

Appropriateness Category Names and Definitions

Appropriateness Category Name

Appropriateness

Rating

Appropriateness Category Definition

Usually Appropriate 7, 8, or 9

The imaging procedure or treatment is indicated in the

specified clinical scenarios at a favorable risk-benefit

ratio for patients.

May Be Appropriate 4, 5, or 6

The imaging procedure or treatment may be indicated

in the specified clinical scenarios as an alternative to

imaging procedures or treatments with a more

favorable risk-benefit ratio, or the risk-benefit ratio for

patients is equivocal.

May Be Appropriate

(Disagreement)

The individual ratings are too dispersed from the panel

median. The different label provides transparency

regarding the panel’s recommendation. “May be

appropriate” is the rating category and a rating of 5 is

assigned.

Usually Not Appropriate 1, 2, or 3

The imaging procedure or treatment is unlikely to be

indicated in the specified clinical scenarios, or the

risk-benefit ratio for patients is likely to be

unfavorable.

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, because of both 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 with 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 [73].

Relative Radiation Level Designations

Relative Radiation Level*

Adult Effective Dose Estimate

Range

Pediatric Effective Dose Estimate

Range

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.”

References

1. Rahman NM, Chapman SJ, Davies RJ. Pleural effusion: a structured approach to care. Br Med Bull 2004;72:31-

47.

2. Kruger D. Evaluating the adult with new-onset pleural effusion. JAAPA 2013;26:20-7.

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10 Workup of Pleural Effusion or Pleural Disease

3. Maskell NA, Butland RJ, Pleural Diseases Group SoCCBTS. BTS guidelines for the investigation of a unilateral

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ACR Appropriateness Criteria

13 Workup of Pleural Effusion or Pleural Disease

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.