Comparison of Effusions over Time |
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Fig. 5.1c Portable |
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semi-erect AP projection |
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(c) demonstrates a slightly |
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larger left effusion on the |
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same patient, next day. Note |
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that the left hemidiaphragm is |
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now totally obliterated, with a |
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larger meniscus (arrows) |
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Fig. 5.1d Axial CT |
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(d) of same patient |
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showing left pleural |
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effusion (eff), along |
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with associated |
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atelectasis (atel). The |
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descending aorta is seen |
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as “A” |
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Case 5.2
See Fig. 5.2 for example of a positionally dependent effusion that is verified on the right side down (side down-side seen) decubitus projection (Fig. 5.2c).
Comparison of Effusions over Time
Optimally, portable images are obtained at similar angles each day, even if not erect, to allow accurate comparisons and assessment of change. To achieve this consistency, the technologist attempts the most upright projection, balanced with patient condition and ability to achieve this often impossible task. It is well documented that portable radiography of the chest is inconsistent and often inadequate [1, 2].
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Fig. 5.2a PA projection demonstrating blunting of costophrenic angle with associated opaque area (dashed circle), with fluid tracking up both minor fissure (thin arrow) and major fissure (wide arrow)
Fig. 5.2b Left side down decubitus view fails to demonstrate layering of effusion in the left hemithorax. Any layering of the right effusion is not well demonstrated due to overlying mediastinum
Fig. 5.2c This right side down decubitus projection verifies that the right effusion is positionally dependent. This also helps to see the extent of effusion since much of the fluid seen on upright projections is behind the hemidiaphragm. One can remember that with effusions and what decubitus view to get: “side down-side seen”
5 Abnormalities Involving the Pleura
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Comparison of Effusions over Time |
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Evaluating the severity of effusions over time can be challenging, especially in the ICU, where exams on different days are at different inclinations (some supine, some nearly upright). The same effusion can look dramatically different in these two opposing positions.
Although devices have been used for years to attempt to demonstrate upright inclination, these only discern supine versus upright. A new device is being evaluated at NIH called the X-Clometer, that can quantify the degree of inclination (how upright is the projection?) to readily display the inclination [3].
See Fig. 5.3 for diagrams demonstrating how the simple X-Clometer works
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Fig. 5.3 This shows design and implementation of the X-Clometer with more accuracy than current markers. The arrows indicate the direction of the X-rays and the device is seen in profile (from the side of the cassette) and plan view (as seen on X-ray). These show the marker at 90° (upright, a), 45° (b), and 0° (supine, c)