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Accuracy of CT pulmonary angiogram in the diagnosis of of pulmonary embolism.

Three Part Question

In [a patient with symptoms and signs of pulmonary embolism] what is the [diagnostic utility] of a [CT pulmonary angiography]?

Clinical Scenario

You have reviewed a 48 year old man who presents with isolated pleuritic chest pain on the left side. His fingers are nicotine stained. He tells you he regularly coughs up yellow phlegm in the morning. His PaO2, PaCO2 are normal and D-dimers elevated. You would like to discharge him to the care of his GP if you are able to rule out pulmonary embolus. Would a CT pulmonary angiogram allow you to do this?

Search Strategy

Medline 1966-05/03 using the OVID interface.
[Exp Tomography, X-ray Computed, OR CT.mp OR Computed tomograph$.mp] AND [exp pulmonary embolism OR pulmonary embol$.mp. OR PE.mp. OR exp thromboembolism OR pulmonary infarct$.mp] LIMIT to human AND English.

Search Outcome

2291 papers were found. 47 addressed the question. Six were excluded on the grounds of weak reference standard. Four were excluded because they used highly selected patient populations, not representative of patients in the emergency department. One study looked specifically at chronic PE. Six studies used a retrospective methodology. One study used a theoretical approach. All meta-analysis were excluded.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Remy–Jardin M et al,
1992,
France
32 patients ?PE and 10 patients with unexplained chest X-ray findingsDiagnostic studySensitivity100%54.7% prevalence of PE 10 patients not referred on a ?PE basis
Specificity95.8%
Goodman LR et al,
1995,
USA
20 ?PE patients with nondiagnostic VQ scan results AND normal Doppler leg scansDiagnostic studySensitivity63.6%55% prevalence PE suggests high risk population
Specificity88.8%
Teigen CL et al,
1995,
USA
60 patients referred for pulmonary angiographyDiagnostic studySensitivity81.8%Patients referred for pulmonary angiography only
Specificity93.7%
van Rossum AB et al,
1996,
Holland
149 patients with nondiagnostic VQ scan resultsDiagnostic studyObserver 1
Sensitivity
Specificity


94%
96%
45.6% prevalence PE CTPA results used in diagnostic protocol
Observer 2
Sensitivity
Specificity


82%
93%
Remy–Jardin M et al,
1996,
France
65 patients referred for pulmonary angiographyDiagnostic studySensitivity97.5%61.5% prevalence PE reflects the high risk population referred for pulmonary angiography
Specificity100%
Sostman HD et al,
1996,
USA
28 ?PE patientsDiagnostic studyAverage of experienced radiologists Sensitivity71%257 patients excluded
Average of experienced radiologists Specificity93.5%
Ferretti GR et al,
1997,
France
113 patients with nondiagnostic VQ scans and normal Doppler leg scans and negative CTPAsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)7%Excluded all patients with positive Doppler scans
Boonbaichaiyapruck S et al,
1997,
Thailand
20 patients ?PE presenting to one hospital over a yearDiagnostic studySensitivity92.3%Unusually high prevalence PE – 60%
Specificity100%
Mayo JR et al,
1997,
Canada & France
135 patients referred for diagnostic imaging ?PE in two centres (different countries)Diagnostic studySensitivity88.9%Only 16% patients were outpatients CTPA results used in the diagnostic protocol
Specificity97.8%
Drucker EA et al,
1998,
USA
47 patients referred for pulmonary angiographyDiagnostic studySensitivityInexperienced reader 60%
Experienced 81%
111 excluded Looked only at patients referred for pulmonary angiography – selective population
SpecificityInexperienced reader 53%
Experienced 97%
Garg K et al,
1998,
USA
24 patients with nondiagnostic VQ scansDiagnostic studySensitivity66.6%Small cohort
Specificity100%
Kim KI et al,
1999,
Canada
103 patients referred for CTPADiagnostic studySensitivity92%Only 28% were outpatients CTPA results used in the diagnostic protocol
Specificity96.2%
Blanchere H,
2000,
France
174 ?PE patientsDiagnostic studySensitivity92.7%Only 15% outpatients CTPA used in the diagnostic protocol
Specificity97.1%
Qanadli SD et al,
2000,
France
151 patients referred for radiological investigation of PEDiagnostic studySensitivity95%
Specificity97%
Goodman LR et al,
2000,
USA
198 patients with negative CTPAsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)1%34 died during follow up - only 12 post mortems42% of study population also had Dopplers Study excluded any of these patients with a positive Doppler! Unable to calculate numbers
Perrier A et al,
2001,
Switzerland
287 emergency patients ?PEDiagnostic studySensitivity70%
Specificity91.2%
Ost D et al,
2001,
USA
71 patients with nondiagnostic VQ scans, normal Doppler scans and negative CTPAsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)4.2%Patients had all had a negative Doppler scan
Musset D et al,
2002,
France
14 hospitals with 632 ?PE patients with negative CTPAs, 76.9% outpatientsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)10%
Remy-Jardin M et al,
2002,
France
259 patients with negative CTPAManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)4.2%18% outpatientsFollow up period only looked for recurrent PE and not DVT
Tillie-Leblond I et al,
2002,
France
199 patients with normal CTPAs within one hospital over 3 year period 85.4% outpatientsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)9.5%73% had chronic respiratory disease
van Stijen MJ,
2003,
Holland
378 ?PE patients with normal CTPAs in 3 hospitalsManagement study% diagnosed with DVT or PE in follow up period (minimum 3 months)1%

Comment(s)

The studies vary in quality and patient demographics. Only one study, Perrier et al (17) looked at unselected emergency department patients and is probably the most relevant study with a robust methodology. In the study by Qandil et al (13) 87% patients were outpatients making the study relevant and they used an excellent gold standard (pulmonary angiography). The management studies tended to exclude any patient diagnosed with a DVT immediately following negative CTPA – I have included these as false negative patients, wherever possible. This may overestimate prevalence of PE, however is generally accepted as a common reference standard for PE. Almost all of these studies used single detector CT scanners. These are being replaced across the UK with multiscanners of superior quality. No study looked at the diagnostic accuracy of the combination of CTPA and D-dimer.

Clinical Bottom Line

CT pulmonary angiogram is not accurate enough to be used as a stand alone diagnostic tool for PE, but appears to perform well in combination with other tests such as Doppler or VQ scan.

References

  1. Remy-Jardin M, Remy J, Wattinne L, et al. Central pulmonary thromboembolism: diagnosis with spiral volumetric CT with the single-breath-hold technique--comparison with pulmonary angiography. Radiology 1992;185:381-7.
  2. Goodman LR, Curtin JJ, Mewissen MW, et al. Detection of pulmonary embolism in patients with unresolved clinical and scintigraphic diagnosis: helical CT versus angiography. American Journal of Roentgenology 1995;164:1369-74.
  3. Teigen CL, Maus TP, Sheedy PF, et al. Pulmonary embolism: diagnosis with contrast-enhanced electron-beam CT and comparison with pulmonary angiography Radiology 1995;194:313-9.
  4. van Rossum AB, Pattynama PM, Ton ER, et al. Pulmonary embolism: validation of spiral CT angiography in 149 patients. Radiology 1996;201:467-70.
  5. Remy-Jardin M, Remy J, Deschildre F, et al. Diagnosis of pulmonary embolism with spiral CT: comparison with pulmonary angiography and scintigraphy. Radiology 1996;200:699-706.
  6. Sostman HD, Layish DT, Tapson VF, et al. Prospective comparison of helical CT and MR imaging in clinically suspected acute pulmonary embolism. Journal of Magnetic Resonance Imaging 1996;6:275-81.
  7. Ferretti GR, Bosson JL, Buffaz PD, et al. Acute pulmonary embolism: role of helical CT in 164 patients with intermediate probability at ventilation-perfusion scintigraphy and normal results at duplex US of the legs. Radiology 1997;205:453-8.
  8. Boonbaichaiyapruck S, Panpunnang S, Siripornpitak S Utilization of electron beam CT scan in diagnosis of pulmonary embolism. Journal of the Medical Association of Thailand. 1997;80:527-33.
  9. Mayo JR, Remy-Jardin M, Muller NL, et al. Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy. Radiology 1997;205:447-52.
  10. Drucker EA, Rivitz SM, Shepard JA et al. Acute pulmonary embolism: assessment of helical CT for diagnosis. Radiology 1998;209:235-41.
  11. Garg K, Welsh CH, Feyerabend AJ, et al. Pulmonary embolism: diagnosis with spiral CT and ventilation-perfusion scanning--correlation with pulmonary angiographic results or clinical outcome. Radiology 1998;208:201-8.
  12. Kim KI, Muller NL, Mayo JR. Clinically suspected pulmonary embolism: utility of spiral CT. Radiology 1999;210:693-7.
  13. Blachere H, Latrabe V, Montaudon M, et al. Pulmonary embolism revealed on helical CT angiography: comparison with ventilation-perfusion radionuclide lung scanning. American Journal of Roentgenology 2000;174:1041-7.
  14. Qanadli SD, Hajjam ME, Mesurolle B et al, Pulmonary embolism detection: prospective evaluation of dual-section helical CT versus selective pulmonary arteriography in 157 patients. Radiology 2000;217:447-55.
  15. Goodman LR, Lipchik RJ, Kuzo RS, et al. Subsequent pulmonary embolism: risk after a negative helical CT pulmonary angiogram--prospective comparison with scintigraphy. Radiology 2000;215:535-42.
  16. Perrier A, Howarth N, Didier D, et al. Performance of helical computed tomography in unselected outpatients with suspected pulmonary embolism. Annals of Internal Medicine 2001;135:88-97.
  17. Ost D, Rozenshtein A, Saffran L, et al. The negative predictive value of spiral computed tomography for the diagnosis of pulmonary embolism in patients with nondiagnostic ventilation-perfusion scans. American Journal of Medicine 2001;110:16-21.
  18. Musset D, Parent F, Meyer G, et al. Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study. Lancet 2002;360:1914-20.
  19. Remy-Jardin M, Tillie-Leblond I, Szapiro D, et al. CT angiography of pulmonary embolism in patients with underlying respiratory disease: impact of multislice CT on image quality and negative predictive value. European Radiology 2002;12:1971-8.
  20. Tillie-Leblond I, Mastora I, Radenne F, et al. Risk of pulmonary embolism after a negative spiral CT angiogram in patients with pulmonary disease: 1-year clinical follow-up study. Radiology 2002;223:461-7.
  21. van Strijen MJ, de Monye W, Schiereck J, et al. Single-detector helical computed tomography as the primary diagnostic test in suspected pulmonary embolism: a multicenter clinical management study of 510 patients. Annals of Internal Medicine 2003;138:307-14.