False Consolidation

Introduction

Identification of consolidation on chest images is a useful skill for radiographers. Care must be taken to avoid declaring every lung opacity a consolidation. There are a variety of causes of lung opacity and a number of known false signs. This page looks at some of the other consolidation-like appearances.

False RML Collapse/Consolidation in Patients with Pectus Excavatum

This patient presented for chest radiography with a history of recent facial nerve palsy. There is loss of the right cardiac border.

There is no abnormal RML opacity. There is evidence of pectus excavatum (depression of the sternum). Pectus excavatum is a known cause of false RML disease and is likely to be a contributing cause of the pseudo-silhouette sign on the PA image. In these patients the heart tends to be displaced towards the left as a result of the limited space between the depressed sternum and the spine.Other contributing factors could be pericardial fat (although none is seen in this patient) and overlying pulmonary vessel. Pectus Excavatum <a class="external" href="http://en.wikipedia.org/wiki/File:Pectus1.jpg" rel="nofollow" target="_blank">http://en.wikipedia.org/wiki/File:Pectus1.jpg</a>

False RML Collapse/Consolidation in Patients with Pericardial fat

Pericardial Fat

<a class="external" href="http://jcmr-online.com/content/11/1/15" rel="nofollow" target="_blank">Validation of cardiovascular magnetic resonance assessment of pericardial adipose tissue volume</a><a class="external" href="http://jcmr-online.com/content/11/1/15" rel="nofollow" target="_blank">Adam J Nelson , Matthew I Worthley , Peter J Psaltis , Angelo Carbone , Benjamin K Dundon , Rae F Duncan , Cynthia Piantadosi , Dennis H Lau , Prashanthan Sanders , Gary A Wittert and Stephen G Worthley</a><a class="external" href="http://jcmr-online.com/content/11/1/15" rel="nofollow" target="_blank">Cardiovascular Research Centre, Royal Adelaide Hospital & Disciplines of Medicine and Physiology, University of Adelaide, Adelaide, SA, Australia</a>

This is a sheep's heart with the pericardium partly dissected off. Note the pericardial fat. Felson (<a class="external" href="http://www.amazon.com/Chest-Roentgenology-Benjamin-Felson/dp/0721635911/ref=sr_1_2?ie=UTF8&s=books&qid=1252240078&sr=1-2" rel="nofollow" target="_blank">Chest Roentgenology, W.B. Saunders, 1973, p55</a>) notes that "For reasons that escape me, fat in the thorax is often impossible to differentiate from water density. Perhaps the adjacent pulmonary gas density has something to do with this illusion." This is an interesting point given the clear differentiaton between fat and water density structures seen in the abdominal plain film.

Case 1

This 49 year old female patient presented for chest radiography with "recent onset of chest pain". There is loss of clarity of the right heart border. In addition, there is loss of clarity of the left heart border. There are good reasons to consider that these silhouette signs are not caused by lung consolidation. The patients history and clinical signs do not suggest a diagnosis of infection/consolidation there is no evidence of alveolar opacity the lateral view does not demonstrate alveolar opacity that you would expect with a lung consolidation The likely cause of the loss of clarity of the cardiac silhouette is the presence of pericardial fat.

There is no abnormal RML or left upper lobe (lingula segment) opacity. Where there is a significant amount of pericardial fat visible on the PA/AP chest image, you would expect to see evidence of this on the lateral image (white arrow)

patient with minimal pericardial fat for comparison (ignore arrow)

Case 2

	This 88 year old male presented to the Emergency Department following a fall. He was referred for a variety of radiographic examinations including chest radiography. He has a moderately large demonstration of pericardial fat (arrowed) (can you see any other pathology!) erect PA DR technique right inferior accessory fissure noted
	He presented to the ED several years later with respiratory symptoms and was referred for chest radiography. His left sided pericardial fat is less evident (? projectional). He has a right middle lobe consolidation (arrowed) causing a partial silhouette sign with the right heart border. AP sitting CR technique

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