Ventilation-Perfusion Lung Scanning and the Diagnosis of Pulmonary Embolism: Improvement of Observer Agreement by the Use of a Lung Segment Reference Chart

Summary

Objective. To test the hypothesis that the systematic use of a lung segment reference chart can improve the inter- and intra-observer agreement for the interpretation of ventilation-perfusion lung scans.

Design. A randomized trial.

Study population. Ventilation-perfusion lung scans were obtained in a series of 220 consecutive patients with clinically suspected pulmonary embolism.

Intervention. Ventilation-perfusion scans were randomly allocated to one of two series each consisting of 110 ventilation-perfusion lung scans. The first series of lung scans was interpreted according to the routine diagnostic approach, and the second series was interpreted with the mandatory use of a lung segment reference chart on which observed ventilation and perfusion defects were drawn. The two nuclear medicine physicians agreed a priori on the diagnostic criteria of the classification scheme.

Measurements. Lung scans were classified as normal, non-high probability, or high probability for pulmonary embolism. The extent of disagreement between the nuclear medicine physicians (inter-observer disagreement) and the lack of internal consistency of each nuclear medicine physician (intra-observer disagreement) was assessed by the percentage disagreement and by kappa statistic.

Results. Inter-observer disagreement which was 20% in the first series, decreased significantly in the second series to 7%; P = 0.003. Intra-observer disagreement for the first series was 10% and 22% for the nuclear medicine physicians, respectively. Intra-observer disagreement for the second series of lung scans decreased significantly for one nuclear medicine physician (intra-observer disagreement, 0%; P <0.01), whereas intra-observer disagreement was reduced to 10% for the other nuclear medicine physician (P = 0.09).

Conclusion. Inter- and intra-observer disagreement were significantly reduced when two nuclear medicine specialists interpreted ventilation-perfusion lung scans according to the routine diagnostic approach plus the use of a lung segment reference chart. The use of the lung segment reference chart for the interpretation of lung scans is likely to improve the management of patients with clinically suspected pulmonary embolism.

• References

• 1 McNeil BJ. Ventilation-perfusion studies and the diagnosis of pulmonary embolism: concise communication. J Nucl Med 1980; 21: 319-323
• 2 Hull RD, Hirsh J, Carter CJ. et al Diagnostic value of ventilation-perfusion lung scanning in patients with suspected pulmonary embolism. Chest 1985; 88: 819-828
• 3 Dalen JE, Brooks HL, Meister SG. et al Pulmonary angiography in acute pulmonary embolism: indications, techniques and results in 367 patients. Am Heart J 1971; 81: 175-179
• 4 Biello DR, Mattar AG, McKnight RC. et al Ventilation-perfusion studies in suspected pulmonary embolism. Am J Radiol 1979; 133: 1033-1037
• 5 Biello DR. Radiological (scintigraphic) evaluation of patients with suspected pulmonary embolism. JAMA 1987; 257: 3257-3259
• 6 Moser KM. Venous thromboembolism. Am Rev Respir Dis 1990; 141: 235-249
• 7 Kipper MS, Moser KM, Kortman KE, Ashburn WL. Long-term follow-up of patients with suspected pulmonary embolism and a normal lung scan. Chest 1982; 82: 411-415
• 8 Hull RD, Raskob GE, Coates G. et al A new noninvasive management strategy for patients with suspected pulmonary embolism. Arch Intern Med 1989; 149: 2549-2555
• 9 The PIOPED investigators Value of the ventilation/perfusion scan in acute pulmonary embolism. JAMA 1990; 263: 2753-2759
• 10 Hull RD, Raskob GE. Low-probability lung scan findings: a need for change. Ann Intern Med 1991; 114: 142-143
• 11 Kelley MA, Carson JL, Palevsky HI, Schwartz JS. Diagnosing pulmonary embolism: new facts and strategies. Ann Intern Med 1991; 114: 300-306
• 12 Koran LM. The reliability of clinical methods, data and judgements. N Engl J Med 1975; 642-646
• 13 Carter WD, Brady TM, Keyes Jr JW. et al Relative accuracy of two diagnostic schemes for detection of pulmonary emblism by ventilation-perfusion scintigraphy. Radiology 1982; 145: 447-451
• 14 Bateman NT, Coakley AJ, Croft DN, Lyall JR. Ventilaton-perfusion lung scans for pulmonary emboli. Eur J Nucl Med 1977; 2: 201-203
• 15 Hoey JR, Farrer PA, Rosenthall LJ, Spengler RF. Inter-observer variability in lung scan reading in suspected pulmonary embolism. Clin Nucl Med 1980; 5: 508-513
• 16 Sullivan DC, Coleman RE, Mills SR. et al Lung scan interpretation: effect of different observer and different criteria. Radiology 1983; 149: 803-807
• 17 Lensing AWA, van Beek EJR, Mingiardi A et al. Ventilation-perfusion lung scanning and the diagnosis of pulmonary embolism: improvement of observer agreement by the use of a lung segment reference chart. Thromb Haemostas 1991; 65: 1171 (abstr)
• 18 Hull R, Hirsh J, Carter C. et al Pulmonary angiography, ventilation lung scanning, and venography for clinically suspected pulmonary embolism with abnormal perfusion lung scan. Ann Intern Med 1983; 98: 891-899
• 19 Sackett DL, Haynes RB, Tugwell P. The interpretation of diagnostic data. In: Clinical Epidemiology, A Basic Science for Clinical Medicine. Sackett DL, Haynes RB, Tugwell P. eds Little, Brown, Boston/Toronto: 1983. pp 059-138
• 20 Kramer MS, Feinstein AR. Clinical biostatistics: LIV. The biostatistics of concordance. Clin Pharmacol Ther 1981; 29: 111-123