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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 findings	Diagnostic study	Sensitivity	100%	54.7% prevalence of PE 10 patients not referred on a ?PE basis
			Specificity	95.8%
Goodman LR et al, 1995, USA	20 ?PE patients with nondiagnostic VQ scan results AND normal Doppler leg scans	Diagnostic study	Sensitivity	63.6%	55% prevalence PE suggests high risk population
			Specificity	88.8%
Teigen CL et al, 1995, USA	60 patients referred for pulmonary angiography	Diagnostic study	Sensitivity	81.8%	Patients referred for pulmonary angiography only
			Specificity	93.7%
van Rossum AB et al, 1996, Holland	149 patients with nondiagnostic VQ scan results	Diagnostic study	Observer 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 angiography	Diagnostic study	Sensitivity	97.5%	61.5% prevalence PE reflects the high risk population referred for pulmonary angiography
			Specificity	100%
Sostman HD et al, 1996, USA	28 ?PE patients	Diagnostic study	Average of experienced radiologists Sensitivity	71%	257 patients excluded
			Average of experienced radiologists Specificity	93.5%
Ferretti GR et al, 1997, France	113 patients with nondiagnostic VQ scans and normal Doppler leg scans and negative CTPAs	Management 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 year	Diagnostic study	Sensitivity	92.3%	Unusually high prevalence PE – 60%
			Specificity	100%
Mayo JR et al, 1997, Canada & France	135 patients referred for diagnostic imaging ?PE in two centres (different countries)	Diagnostic study	Sensitivity	88.9%	Only 16% patients were outpatients CTPA results used in the diagnostic protocol
			Specificity	97.8%
Drucker EA et al, 1998, USA	47 patients referred for pulmonary angiography	Diagnostic study	Sensitivity	Inexperienced reader 60% Experienced 81%	111 excluded Looked only at patients referred for pulmonary angiography – selective population
			Specificity	Inexperienced reader 53% Experienced 97%
Garg K et al, 1998, USA	24 patients with nondiagnostic VQ scans	Diagnostic study	Sensitivity	66.6%	Small cohort
			Specificity	100%
Kim KI et al, 1999, Canada	103 patients referred for CTPA	Diagnostic study	Sensitivity	92%	Only 28% were outpatients CTPA results used in the diagnostic protocol
			Specificity	96.2%
Blanchere H, 2000, France	174 ?PE patients	Diagnostic study	Sensitivity	92.7%	Only 15% outpatients CTPA used in the diagnostic protocol
			Specificity	97.1%
Qanadli SD et al, 2000, France	151 patients referred for radiological investigation of PE	Diagnostic study	Sensitivity	95%
			Specificity	97%
Goodman LR et al, 2000, USA	198 patients with negative CTPAs	Management 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 ?PE	Diagnostic study	Sensitivity	70%
			Specificity	91.2%
Ost D et al, 2001, USA	71 patients with nondiagnostic VQ scans, normal Doppler scans and negative CTPAs	Management 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% outpatients	Management 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 CTPA	Management 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% outpatients	Management 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 hospitals	Management 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.