The low specificity of postoperative perfusion lung scan defects

Area of Science:

• Radiology
• Pulmonary Medicine
• Diagnostic Imaging

Background:

• Ventilation-perfusion (V/Q) lung scans are utilized for diagnosing pulmonary embolism.
• Assessing the diagnostic accuracy of V/Q scans in the postoperative setting is crucial.

Purpose of the Study:

• To evaluate the incidence and significance of perfusion lung scan abnormalities in the postoperative period.
• To determine if postoperative V/Q scan findings are reliable indicators of pulmonary embolism.

Main Methods:

• 169 patients underwent preoperative and postoperative V/Q lung scans.
• Scans were blindly classified using predefined criteria.
• Correlation with clinical evidence and venous thrombosis was assessed.

Main Results:

• Postoperative perfusion scan abnormalities were observed in 25% of patients, with 38% identical to preoperative scans.
• High-probability defects for pulmonary embolism were noted in 10 postoperative scans, but clinical evidence was absent in these cases.
• Venous thrombosis was present in 12 patients, including 4 with definite pulmonary embolism on V/Q scans.

Conclusions:

• Postoperative perfusion lung scan defects can be misleading, even when extensive.
• The interpretation of postoperative V/Q scans requires careful consideration of preoperative findings and clinical context.
• V/Q scan abnormalities alone may not definitively indicate postoperative pulmonary embolism.