Review of Criteria Appropriate for a Very Low Probability of Pulmonary Embolism on Ventilation-Perfusion Lung Scans: A Position Paper1
Paul D. Stein, MD and
Alexander Gottschalk, MD
1 From the Henry Ford Heart and Vascular Institute, Detroit, Mich (P.D.S.), and Michigan State University, East Lansing (A.G.). Received July 31, 1998; revision requested February 8, 1999 and final revision received May 17; accepted May 17. Address reprint requests to P.D.S., Henry Ford Cardiac Wellness Center, 6525 Second Ave, Detroit, MI 48202-3006.
View larger version (117K):
[in a new window]
|
Figure 1a. Nonsegmental perfusion abnormality. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows a prominent right hilum. (b) Posterior and right posterior oblique (RPO) images from a perfusion lung scan show enlargement of the right hilum (arrowheads).
|
|
View larger version (74K):
[in a new window]
|
Figure 1b. Nonsegmental perfusion abnormality. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows a prominent right hilum. (b) Posterior and right posterior oblique (RPO) images from a perfusion lung scan show enlargement of the right hilum (arrowheads).
|
|
View larger version (111K):
[in a new window]
|
Figure 2a. Perfusion defect smaller than a corresponding radiographic defect. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows a retrocardiac area of increased opacity with faint depiction of air bronchograms. (b) Anterior and posterior images from a perfusion scan only vaguely suggest a perfusion defect in the left lung base. No ventilation scan was performed in this case.
|
|
View larger version (66K):
[in a new window]
|
Figure 2b. Perfusion defect smaller than a corresponding radiographic defect. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows a retrocardiac area of increased opacity with faint depiction of air bronchograms. (b) Anterior and posterior images from a perfusion scan only vaguely suggest a perfusion defect in the left lung base. No ventilation scan was performed in this case.
|
|
View larger version (92K):
[in a new window]
|
Figure 3a. Matched ventilation-perfusion scan defects. No areas of increased opacity were seen at chest radiography, and pulmonary angiography showed no pulmonary embolism. (a) Left posterior oblique (LPO) and posterior images from a perfusion scan show multiple areas of diminished perfusion that are especially prominent in the lung bases. Note the irregular lung margins; these are not artifactual but represent diminished perfusion. (b) Images from a xenon-133 ventilation scan demonstrate matched ventilation-perfusion defects in all three zones of both lungs. The equilibrium image was obtained over a 2-minute period at the end of the 4-minute equilibration period. Note the relatively sharp lung margins (especially at the bases) compared with the perfusion scan (cf a). The posterior image was obtained over a 45-second period that ended 90 seconds after the start of washout. Procurement of the left posterior oblique (LPO) image ended 180 seconds after the start of washout. The focal areas of increased activity represent abnormal ventilation (slow washout). Matched basilar perfusion and ventilation abnormalities are particularly well visualized on left posterior oblique images.
|
|
View larger version (65K):
[in a new window]
|
Figure 3b. Matched ventilation-perfusion scan defects. No areas of increased opacity were seen at chest radiography, and pulmonary angiography showed no pulmonary embolism. (a) Left posterior oblique (LPO) and posterior images from a perfusion scan show multiple areas of diminished perfusion that are especially prominent in the lung bases. Note the irregular lung margins; these are not artifactual but represent diminished perfusion. (b) Images from a xenon-133 ventilation scan demonstrate matched ventilation-perfusion defects in all three zones of both lungs. The equilibrium image was obtained over a 2-minute period at the end of the 4-minute equilibration period. Note the relatively sharp lung margins (especially at the bases) compared with the perfusion scan (cf a). The posterior image was obtained over a 45-second period that ended 90 seconds after the start of washout. Procurement of the left posterior oblique (LPO) image ended 180 seconds after the start of washout. The focal areas of increased activity represent abnormal ventilation (slow washout). Matched basilar perfusion and ventilation abnormalities are particularly well visualized on left posterior oblique images.
|
|
View larger version (139K):
[in a new window]
|
Figure 4. One to three small segmental perfusion defects. Pulmonary angiography showed no pulmonary embolism. Posterior image from a perfusion scan shows small, round lesions in the left apex (top arrow) and retrocardiac left lung base (bottom arrow). (Reprinted, with permission, from reference 12.)
|
|
View larger version (124K):
[in a new window]
|
Figure 5a. Triple matched defect in the right midlung zone. Pulmonary angiography showed no pulmonary embolism. (a) Portable chest radiograph shows an area of increased opacity in the right midlung. The right lung base is not well visualized. (b) Posterior single-breath (left) and equilibrium (right) images from a xenon-133 ventilation scan show a ventilation defect in the right midlung zone. (c) Posterior (left) and right posterior oblique (right) images from a perfusion scan show a perfusion defect in the right midlung zone in the apical segment of the right lower lobe (arrows).
|
|
View larger version (99K):
[in a new window]
|
Figure 5b. Triple matched defect in the right midlung zone. Pulmonary angiography showed no pulmonary embolism. (a) Portable chest radiograph shows an area of increased opacity in the right midlung. The right lung base is not well visualized. (b) Posterior single-breath (left) and equilibrium (right) images from a xenon-133 ventilation scan show a ventilation defect in the right midlung zone. (c) Posterior (left) and right posterior oblique (right) images from a perfusion scan show a perfusion defect in the right midlung zone in the apical segment of the right lower lobe (arrows).
|
|
View larger version (70K):
[in a new window]
|
Figure 5c. Triple matched defect in the right midlung zone. Pulmonary angiography showed no pulmonary embolism. (a) Portable chest radiograph shows an area of increased opacity in the right midlung. The right lung base is not well visualized. (b) Posterior single-breath (left) and equilibrium (right) images from a xenon-133 ventilation scan show a ventilation defect in the right midlung zone. (c) Posterior (left) and right posterior oblique (right) images from a perfusion scan show a perfusion defect in the right midlung zone in the apical segment of the right lower lobe (arrows).
|
|
View larger version (131K):
[in a new window]
|
Figure 6a. Stripe sign. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows no area of increased opacity in the right midlung zone. The right midlung demonstrated normal findings on a xenon-133 ventilation scan. (b) Posterior (left) and right posterior oblique (right) images from a perfusion scan demonstrate a possible perfusion mismatch in the apical segment of the right lower lobe (posterior image) and a peripheral rim of increased activity, or stripe sign (arrows on right posterior oblique image). The stripe sign indicates a very low probability that this lesion was caused by pulmonary embolism.
|
|
View larger version (66K):
[in a new window]
|
Figure 6b. Stripe sign. Pulmonary angiography showed no pulmonary embolism. (a) Chest radiograph shows no area of increased opacity in the right midlung zone. The right midlung demonstrated normal findings on a xenon-133 ventilation scan. (b) Posterior (left) and right posterior oblique (right) images from a perfusion scan demonstrate a possible perfusion mismatch in the apical segment of the right lower lobe (posterior image) and a peripheral rim of increased activity, or stripe sign (arrows on right posterior oblique image). The stripe sign indicates a very low probability that this lesion was caused by pulmonary embolism.
|
|
Copyright © 2000 by the Radiological Society of North America.
