Definition of Pulmonary nodule Rounded opacity, moderately well defined < 3cm in diameter Web p 97
General Approach to lung nodules Position Is it a lung nodule? – Skin tags, nipple shadows, bone lesions Distribution in the lung Number of Nodules ( SPN, Multiple) Compare with previous radiographs Interpreting CXR p102
Description of pulmonary nodule Pattern of distribution (Relationship to fissures, pleura, secondary lobules) Edge characteristics (sharp, poorly circumscribed, ground glass) Morphology ( branching/ tree in bud) Size: – Pulmonary nodule <3cm – Small nodule < 1cm Web p97 High resolution CT of the lung
HRES CT Interstitial nodules vs Air space nodules
WEB-Algorithmic approach to nodules InterstitialAir space Well definedIll defined Soft tissue attenuationHomogenous soft tissue Obscure edges of vessels they touch Hazy and less dense than adjacent vessels Peripheral in Pulm. LobuleCentral P120 High resolution CT lung,Web - approach
Perilymphatic vs. centrilobular TB Centrilobular changes : nodules, tree-in- bud, branching lines Sarcoidosis - Fissural and subpleural nodules
(A)Perilymphatic nodules. Nodules are immediately in contact with interlobular septa and the visceral pleura (B) Centrilobular nodules. Nodules are positioned 5 - 10 mm from costal and visceral pleural surfaces and interlobular septa.
References High resolution CT of the lung, Web, Naidich CT of the lung, Verschakelen, De Wever Prof Naidich RSSA lecture High-Resolution CT of the Lung: Patterns of Disease and Differential Diagnoses, Radiol Clin N Am 43 (2005) 513 – 542 Imaging of Interstitial Lung Disease, Radiol Clin N Am 43 (2005) 589 – 599
SPN Def: focal area of increased round /oval density in the lung parenchyma measuring less than 3cm, Cause : infection, malignancy, inflammation, vascular, congenital Risk : 30-40% malignant
Approach to SPN Morphology: - Size ( smaller more likely benign) - margins and contours MarginsRisk for malignancy Smooth21% Lobulated ( uneven growth75% Irregular,spiculated, distortion of blood vessels Very high risk
Internal characteristics Homogeneous attenuation (55% benign, 20%malignant) Pseudocavitation and air bronchograms: lymphoma or bronchioalveolar cancer Benign cavitation : smooth,thin walls (<4mm) Malignant cavitation: thick irregular walls( >16mm) Intranodular fat = hamartoma Benign calcification : – post infection: central, diffuse solid, laminated, – hamartoma : popcorn like Malignant calcification: diffuse,amorphous,punctate Metastatic osteosarcoma: high attenuation nodule
25-39% malignant nodules classified as benign on radiological morphology assessment growth rate assessment: doubling rate ( increase in diameter of >26%) for malignant nodules between 30-400 days Clinical data: age, risk factors, previous malignancy
Distribution of lung nodules Cancer – basal predominance Breast CA, Colon, Renal often metastasize to lung Interpreting CXR p100
Size of lung nodules Mayo clinic CT screening trial ( in patients with no history of cancer) <3mm = less than 0,2% malignant <5mm = fewer than 1% malignant 4-7mm = 0,9% malignant 8-20mm = 18% malignant >20mm = 50% malignant Radiology Nov 2005 p 397
Follow-up National Lung Screening Trial nodules smaller than 4mm return for screening after 12 months, without interval scans or other work-up Radiology Nov 2005 p 397
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