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CT of lung nodules

568 bytes added, 15:23, 17 July 2019
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*'''Multiplicity''': Where the presence of up to an additional 3 nodules has been found to increase the risk of cancer, but decrease in case of 4 or more additional ones, likely because it indicates a previous granulomatous infection rather than cancer.<ref name="MacMahonNaidich2017"/>
*Presence of '''[[emphysema]]''' and/or '''[[lung fibrosis]]''', which are risk factors for cancer.<ref name="MacMahonNaidich2017"/>
*'''AttenuationEnhancement''': A If the exam is done as a combined non-contrast and [[contrast CT]], a solitary nodule with a density below an enhancement off less than 15 [[Hounsfield unit]]s on (HU), whereas a higher enhancement indicates a malignant tumor (with a [[sensitivity and specificity|sensitivity]] estimated at 98%).<ref name=Medscape>{{cite web|url=https://emedicine.medscape.com/article/358090-overview#a3|title=Lung Metastases Imaging|author=Tanay Patel|website=[[computed tomographyMedscape]] tends to be benign}} Updated: Sep 30, whereas malignant tumors often measure more than 20 Hounsfield units2018</ref> [[File:CT of a fat containing hamartoma.png|thumb|Low attenuating nodule (in this case a fat containing hamartoma). Fatty <ref name=Snoeckx2017/>]]*Areas of '''fatty tissue inside hamartomas will have ''' (−40 to −120 HU) indicates a strongly negative value on the [[Hounsfield scalehamartoma]]. However, oly only about 50% of hamartomas are fat containing.<ref name=Snoeckx2017/>
If previous exams are available, also evaluate:
*If there is a '''central cavity''', then a thin wall points to a benign cause whereas a thick wall is associated with malignancy (especially 4&nbsp;mm or less versus 16&nbsp;mm or more).<ref name="Radiology2006"/>
<gallery>
File:CT of a fat containing hamartoma.png|Low attenuating nodule (in this case a fat containing hamartoma).<ref name=Snoeckx2017/>
File:CT of an aspergilloma.png|Cavitation with relatively thick wall, in this case [[aspergilloma]]).<ref name=Snoeckx2017/>
</gallery>
[[Air bronchogram]]s is defined as a pattern of air-filled bronchi on a background of airless lung, and may be seen in both benign and malignant nodules, but certain patterns thereof may help in risk stratification.<ref name=Snoeckx2017/> {{Further|Air bronchogram}}
 
CT densitometry, measuring absolute attenuation on the [[Hounsfield scale]], has low sensitivity and specificity and is not routinely employed, apart from helping to distinguish solid from ground glass lesions, and to confirm visible fatty areas or calcifications.<ref name=Medscape/>
===Further management===
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