Back to Basics - ′Must Know′ Classical Signs in Thoracic Radiology

Abstract

There are a few signs in radiology which are based on many common objects or patterns that we come across in our routine lives. The objective behind the association between such common objects and the corresponding pathologies is to make the reader understand and remember the disease process. These signs do not necessarily indicate a particular disease, but are usually suggestive of a group of similar pathologies which will facilitate in the narrowing down of the differential diagnosis. These signs can be seen in different imaging modalities like plain radiograph and computed tomography. In this essay, we describe 24 classical radiological signs used in chest imaging, which would be extremely helpful in routine clinical practice not only for radiologists but also for chest physicians and cardiothoracic surgeons.

The spectrum of pulmonary aspergillosis

“…In simple aspergilloma, the lung parenchyma and pleura adjacent to the cavity are mostly normal. Monod's sign describes the crescent-shaped air space that separates the fungal ball from its cavity's wall [75][76][77]. It may be difficult to distinguish subacute invasive aspergillosis from CCPA on chest radiography or CT-scan.…”

“Distal bright vessel sign” – Novel radiological sign of pulmonary thromboembolism

“…“Hampton Hump” refers to a peripheral, usually wedge-shaped, pulmonary opacity on chest radiography, representing pulmonary infarction/hemorrhage. Less well known signs of PE on conventional chest radiography are the “Fleishner sign”, referring to an enlarged pulmonary artery, resulting from distension of the vessel by the clot, the "knuckle sign", which refers to the abrupt cutoff of a pulmonary artery, and their variants - “Palla sign”, which refers to enlarged right interlobar pulmonary artery, and “Chang sign” consisting of a dilated right main pulmonary artery with abrupt cutoff [3].…”

“…On CT, pulmonary infarcts can manifest as wedge-shaped, peripheral opacities, commonly with a “reverse-halo” or “atoll” appearance, consisting of central ground glass and a rim of consolidation [6]. Predictable pattern of progressive resorption of pulmonary infarcts on follow-up imaging, from outside to inside, with preservation of their overall shape, is known as the ``melting ice cube sign'' [3].…”

A Malaysian ex-smoker with cough, breathlessness and nonresolving bronchospasm

“…This can also be due to severe lung infection caused by Streptococcus pneumoniae , P. aeruginosa and S. aureus [6]. Other diseases that (less commonly) manifest a bulging fissure include pneumonia caused by L. pneumophila [7] or M. tuberculosis [1, 8], or any space-occupying process in the lung, such as pulmonary haemorrhage, lung abscess or tumour [9].…”