Unilateral Plaquing Explanation:
The concept of bilateral calcified pleural plaquing comes from the time of chest x-rays only, prior to CT and HRCT scanning, when a definite diagnosis of pleural plaquing was made by the visualization of bilateral calcified pleural plaques compared to non-calcified chest wall thickening or other superimposed densities, such as muscle slips. Also, there was confusion by some, calling unilateral calcified diffuse pleural thickening as pleural plaquing and so to avoid that confusion, the bilateral concept was suggested. Chest x-rays as it turns out, after the advent of CT/HRCT, are notorious for being highly unreliable for the detection of plaquing, with 60% to 90% of plaques being missed. Furthermore, to make the bilateral concept confusing, one of the most common educational chest x-ray images of calcified pleural plaques is a unilateral calcified diaphragmatic plaque. With the advent of CT and HRCT in the late 70s and certainly by the early 1980s over 35 plus years ago, there was much better visualization and identification of calcified and non-calcified pleural plaquing compared to chest x-rays and differentiation from other causes of chest wall thickening. Not only was there better identification of pleural plaque formation and their calcifications, but it was discovered as noted above, that over one-third of cases of pleural plaques are unilateral.
“Plaques are usually bilateral, although they appear unilateral in up to one third of cases”, Thoracic Imaging, Pulmonary and Cardiovascular Radiology, Third Edition, page 544, W. Richard Webb and Charles B. Higgins, Wolters Kluwer publisher.
The above article is provided as a public service by Daniel Powers, M.D.: B-Reader, Board-Certified Diagnostic Radiologist, Certified by the American Board of Radiology.
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