Diagnostic Imaging Pathways - Respiratory Illness (Acute)
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This pathway provides guidance on imaging patients with acute respiratory illness and provides guidelines as to who would benefit from plain chest radiography.
Date reviewed: June 2015
Date of next review: June 2017
Published: February 2016
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The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.
| SYMBOL | RRL | EFFECTIVE DOSE RANGE |
 | None | 0 |
 | Minimal | < 1 millisieverts |
 | Low | 1-5 mSv |
 | Medium | 5-10 mSv |
 | High | >10 mSv |
Images
Image GalleryNote: These images open in a new page |
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| 1a |  |
Pneumococcal Pneumonia Images 1a and 1b (Plain Radiograph, PA and Lateral): There is widespread consolidation of the right lung with air bronchograms and bulging of the fissues (arrows) indicative of lobar pneumonia. |
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| 2 |  |
Pneumocystis Pneumonia
Image 2 (Plain Radiograph): Patchy bilateral infiltrates extending from the perihilar region is suggestive of Pneumocystis jirovecii (formely Pneumocystic carinii) infection in this immunocompromised patient. |
| 3 |  |
Tuberculous Pneumonia
Image 3 (Plain Radiograph): There is right middle and upper lobe consolidation with bilateral paratracheal lymphadenopathy (arrows). Multiple small nodules are scattered throughout the remaining lung parenchyma (arrowheads) indicative of tuberculous pneumonia with miliary spread. |
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Lung Abscess Images 4a and 4b (Plain Radiograph, PA and Lateral): A large circumscibed lesion is present in the right lower lobe with a well defined wall and an air-fluid level consistent with a lung abscess. |
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| 5a |  |
Bronchopneumonia Images 5a and 5b : Post-mortem specimen showing patchy areas of consolidation consistent with bronchopneumonia. |
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6a |
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Collapse Lung
Images 6a, 6b and 6c (Plain Radiograph): There is collapse of the right upper lobe, the left upper lobe( the Golden S sign) and the left lower lobe respectively. |
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6b |
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6c |
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Teaching Points
Teaching Points
Role of Imaging in Acute Respiratory Illness- Chest radiography is over utilized in the management of acute respiratory illness
- Certain clinical symptoms and signs can suggest a diagnosis of pneumonia but none can definitely rule in or out the diagnosis
- 5% of patients with acute respiratory illness have pneumonia from a primary care setting. This increases to 28% of patients in the accident and emergency environment
- CT is not routine in the setting of acute respiratory illness
- Lung ultrasonography (LUS) has shown to be promising in the evaluation of pneumothorax, pleural effusion and consolidations but with varying outcomes for the diagnosis of pneumonia. Therefore, an inconspicuous LUS does not exclude pneumonia and necessitates a chest radiography or chest CT scan for further evaluation
HS1
Factors That Increase The Likelihood Of A Significant Abnormality On Chest Radiograph
- The factors listed below come from two studies that attempted to develop clinical decision rules for predicting chest radiograph abnormalities
- Study 1 1
- Temp >37.8°C
- Pulse >100/min
- Crackles
- Decreased breath sounds
- Absence of asthma
- Study 2 2
- Age >60
- Temp >38°C
- Oxygen saturation < 90%
- Respiratory rate >24 breaths/min
- Haemoptysis
- Crackles
- Decreased breath sounds
- History of alcohol abuse
- History of tuberculosis
- History of thromboembolic disease
- Patients who are immunocompromised should be investigated initially with a chest radiograph if there is clinical suspicion of an acute respiratory illness. However the sensitivity of chest radiograph is too low to consider it a stand-alone technique for the evaluation of immunocompromised patients whose immune reactivity is poorer and delayed compared with immuno-competent ones, with suspected pneumonia. For these patients, an early chest CT evaluation is therefore recommended 3
- Fever and tachypnoea in children are strong indicators that a chest radiograph is needed. No single sign or symptom predicts pneumonia with a high degree of certainty in adult and geriatrics patients. Clinical utility of chest radiograph can be improved with careful clinical examination of patients before obtaining radiographs, especially in paediatric patients 4
- A number of other studies have attempted to identify which patients should have a chest radiograph but none concur on significant factors 5-9
- The absence of radiographic findings should not supersede clinical judgment and empiric treatments in patients with clinical suspicion of pneumonia 10-12
HS4
Chest Radiograph
- Patients with acute respiratory illness but without pneumonia often have unnecessary chest radiographs and these result in unnecessary cost and radiation exposure 1
- Many patients with acute respiratory illness receive a chest radiograph, usually to diagnose or exclude pneumonia 13
- Approximately 5% of patients who present to their primary care physician with an acute respiratory illness will have pneumonia 14 as chest radiography was not very useful for diagnosing pneumonia in patients with a low clinical probability of pneumonia 15
- Of patients with an acute respiratory illness who present to an Emergency Department, as many as 28% will have pneumonia 5
- Admission radiographs lacks sensitivity and may not demonstrate parenchymal opacifications in 21% of patients. Moreover, greater than half of patients admitted with a negative chest radiograph will develop radiographic infiltrates within 48 hours. 16,17 Because of the low sensitivity and inter-observer variability, some of the infiltrates can be missed 17
- Routine short-term follow-up chest radiographs (<28 days) of hospitalized patients with severe community acquired pneumonia (CAP) seem to provide no additional clinical value while a delay of at least 8–12 weeks after an episode of CAP seems to be reasonable 18
- Patients with acute asthma occasionally have significant abnormalities on chest radiography and may only require imaging if there is suspected pneumonia or pneumothorax 19,20
- More than 10% of para-pneumonic effusions are missed on chest radiographs (lateral, PA and AP) with the majority presenting effusions missed in each view were on films with lower lobe consolidation in which clinicians should consider obtaining a lung ultrasound 21
HS5
Chest Computed Tomography (CT)
- CT is not routine in the setting of an acute respiratory illness. Indications for CT include
- Infiltrate, opacity, collapse, or consolidation on plain chest radiograph that does not resolve after treatment for infection, or fit with the clinical picture
- Non-resolving infection, or recurring infections in the same location
- Suspected empyema
- Suspected bronchiectasis
- Immunocompromised patients with fever of unknown origin and a potential chest source even if plain chest radiography is normal
HS6
Lung Ultrasonography (LUS)
- In comparison with chest radiography, especially in the emergency and critical care setting, lung ultrasonography (LUS) has shown to be promising with excellent sensitivity 93-94%, specificity 95-96% and diagnostic accuracy 94% in the evaluation of pneumothorax, pleural effusion and consolidations 22,26
- LUS have varying outcomes for the diagnosis of pneumonia 22-25,27
- Despite this, a recent systematic review and meta-analysis revealed encouraging results to support the use of lung ultrasonography for the diagnosis of pneumonia 28
- About 8% of pneumonic lesions are not detectable by LUS; therefore, an inconspicuous LUS does not exclude pneumonia. Chest radiography or chest CT scan is necessary in cases with negative ultrasound results or if other differential diagnoses are considered or if complications occur 27
- Advantages of LUS 28,29
- No ionising radiation; hence is preferred in pregnant or presumed pregnant patients and children
- Can be utilized as point-of-care imaging in severely ill, frail and bedridden patients at the bedside
- The evaluation is easy and fast to perform
- Due to its high negative predictive value (NPV), LUS's value as a standard rule-out (SnNout) examination in patients with respiratory symptoms should be considered 26,30
References
References
Date of literature search: June 2015
The search methodology is available on request. Email
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Heckerling PS, Tape TG, Wigton RS, et al. Clinical prediction rule for pulmonary infiltrates. Ann Intern Med. 1990;113:664-70. (Level II evidence). View the reference
- Rothrock SG, Green SM, Costanzo KA, et al. High yield criteria for obtaining non-trauma chest radiography in the adult emergency department population. J Emerg Med. 2002;23:117-24. (Level II evidence). View the reference
- Cereser L, Zuiani C, Graziani G, Girometti R, Como G, Zaja F, et al. Impact of clinical data on chest radiography sensitivity in detecting pulmonary abnormalities in immunocompromised patients with suspected pneumonia. Radiol Med. 2010;115(2):205-14. (Level III evidence). View the reference
- Wilkins TR, Wilkins RL. Clinical and radiographic evidence of pneumonia. Radiol Technol. 2005;77(2):106-10. (Review article). View the reference
- Heckerling PS. The need for chest roentgenograms in adults with acute respiratory illness: clinical predictors. Arch Intern Med. 1986;146:1321-4. (Level IV evidence). View the reference
- Butcher BL, Nichol KL, Parenti CM. High yield of chest radiography in walk-in clinic patients with chest symptoms. J Gen Intern Med. 1993;8:115-9. (Level III evidence). View the reference
- Benacerraf BR, McLoud TC, Rhea JT, et al. An assessment of the contribution of chest radiography in outpatients with acute complaints: a prospective study. Radiology. 1981;138:293-9. (Level IV evidence). View the reference
- Okimoto N, Yamato K, Kurihara T, Honda Y, Osaki K, Asaoka N, et al. Clinical predictors for the detection of community-acquired pneumonia in adults as a guide to ordering chest radiographs. Respirology. 2006;11(3):322-4. (Level III evidence). View the reference
- O'Brien WT, Sr., Rohweder DA, Lattin GE, Jr., Thornton JA, Dutton JP, Ebert-Long DL, et al. Clinical indicators of radiographic findings in patients with suspected community-acquired pneumonia: who needs a chest x-ray? J Am Coll Radiol. 2006;3(9):703-6. (Level II evidence). View the reference
- van Vugt SF, Verheij TJ, de Jong PA, Butler CC, Hood K, Coenen S, et al. Diagnosing pneumonia in patients with acute cough: clinical judgment compared to chest radiography. Eur Respir J. 2013;42(4):1076-82. (Level II evidence). View the reference
- Basi SK, Marrie TJ, Huang JQ, Majumdar SR. Patients admitted to hospital with suspected pneumonia and normal chest radiographs: epidemiology, microbiology, and outcomes. Am J Med. 2004;117(5):305-11. (Level III evidence). View the reference
- Cao AM, Choy JP, Mohanakrishnan LN, Bain RF, van Driel ML. Chest radiographs for acute lower respiratory tract infections. Cochrane Database Syst Rev. 2013;12:CD009119. (Level II evidence). View the reference
- Simpson JCG, Hulse P, Taylor PM, Woodhead M. Do radiographic features of acute infection influence management of lower respiratory tract infections in the community? Eur Respir J. 1998;12:1384-7. (Level IV evidence). View the reference
- Metlay JP, Kapoor WN, Fine MJ. Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination. JAMA. 1997;278:1440-5. (Review article). View the reference
- Speets AM, Hoes AW, van der Graaf Y, Kalmijn S, Sachs AP, Mali WP. Chest radiography and pneumonia in primary care: diagnostic yield and consequences for patient management. Eur Respir J. 2006;28(5):933-8. (Level II/III evidence). View the reference
- Graffelman AW, Willemssen FE, Zonderland HM, Neven AK, Kroes AC, van den Broek PJ. Limited value of chest radiography in predicting aetiology of lower respiratory tract infection in general practice. Br J Gen Pract. 2008;58(547):93-7. (Level II/III evidence). View the reference
- Hagaman JT, Rouan GW, Shipley RT, Panos RJ. Admission chest radiograph lacks sensitivity in the diagnosis of community-acquired pneumonia. Am J Med Sci. 2009;337(4):236-40. (Level III evidence). View the reference
- Bruns AH, Oosterheert JJ, Prokop M, Lammers JW, Hak E, Hoepelman AI. Patterns of resolution of chest radiograph abnormalities in adults hospitalized with severe community-acquired pneumonia. Clin Infect Dis. 2007;45(8):983-91. (Level III evidence). View the reference
- Aronson S, Gennis P, Kelly D, et al. The value of routine admission chest radiographs in adult asthmatics. Ann Emerg Med. 1989;18:1206-8. (Level IV evidence). View the reference
- Findley LJ, Sahn SA. The value of chest roentgenograms in acute asthma in adults. Chest. 1981;80:535-6. (Level IV evidence). View the reference
- Brixey AG, Luo Y, Skouras V, Awdankiewicz A, Light RW. The efficacy of chest radiographs in detecting parapneumonic effusions. Respirology. 2011;16(6):1000-4. (Level III evidence). View the reference
- Corradi F, Brusasco C, Garlaschi A, Paparo F, Ball L, Santori G, et al. Quantitative analysis of lung ultrasonography for the detection of community-acquired pneumonia: a pilot study. Biomed Res Int. 2015;2015:868707. (Level II evidence). View the reference
- Reissig A, Copetti R. Lung ultrasound in community-acquired pneumonia and in interstitial lung diseases. Respiration. 2014;87(3):179-89. (Review article). View the reference
- Turner JP, Dankoff J. Thoracic ultrasound. Emerg Med Clin North Am. 2012;30(2):451-73, ix. (Review article). View the reference
- Lichtenstein DA, Meziere GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest. 2008 Jul;134(1):117-25. View the reference
- Volpicelli G, Caramello V, Cardinale L, Cravino M. Diagnosis of radio-occult pulmonary conditions by real-time chest ultrasonography in patients with pleuritic pain. Ultrasound Med Biol. 2008;34(11):1717-23. (Level II/III evidence). View the reference
- Reissig A, Copetti R, Mathis G, Mempel C, Schuler A, Zechner P, et al. Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: a prospective, multicenter, diagnostic accuracy study. Chest. 2012;142(4):965-72. (Level II evidence). View the reference
- Chavez MA, Shams N, Ellington LE, Naithani N, Gilman RH, Steinhoff MC, et al. Lung ultrasound for the diagnosis of pneumonia in adults: a systematic review and meta-analysis. Respir Res. 2014;15:50. (Level I evidence). View the reference
- Zanobetti M, Poggioni C, Pini R. Can chest ultrasonography replace standard chest radiography for evaluation of acute dyspnea in the ed? Chest. 2011;139(5):1140-7. (Level II evidence). View the reference
- Laursen CB, Sloth E, Lambrechtsen J, Lassen AT, Madsen PH, Henriksen DP, et al. Focused sonography of the heart, lungs, and deep veins identifies missed life-threatening conditions in admitted patients with acute respiratory symptoms. Chest. 2013;144(6):1868-75. (Level II evidence). View the reference
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