Pulmonary emphysema refers to destruction of alveolar spaces without fibrosis and occurs in several patterns. Centrilobular emphysema develops at the centre of the secondary pulmonary lobule and is the most common form seen in smokers. Panlobular emphysema refers to alveolar destruction throughout the secondary pulmonary lobule and is typical of alpha-1-antitrypsin deficiency. Paraseptal emphysema occurs along the interlobular septae and particularly the pleural margin. Often all patterns can be seen in the same lung, as with this HRCT example.
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Polycystic ovaries - an important description of ovarian morphology on ultrasound which forms one of the diagnostic criteria for polycystic ovarian syndrome; the others being oligo- or anovulation and hyperandrogenism. It is defined by the presence of many small follicles (12 or more less than 10mm in diameter) or by an ovarian volume greater than 10ml. This later criterion means that a ‘polycystic ovary’ may in fact contain no follicles! When present, the follicles are typically peripheral with a ‘sting of pearls’ appearance.
Puff of smoke sign - describes the characteristic angiographic appearance of tiny abnormal intracranial collateral vessel networks in moya moya disease. Progressive narrowing of the supraclinoid internal carotid arteries and circle of Willis vessels results in extensive small collateral arterial networks evolving from the lenticulostriate and choroidal arteries. When viewed angiographically, the abnormal collaterals simulate smoke emanating away from the major arteries.