Lung Nodules

Lung Nodules

Frans Naudé

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

Web p185

P84, Computed Tomography of the Lung, Verschakelen

Lung nodules: Imaging Modalities

• CXR• CT ( HRES)• PET/CT : F18-FDG

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

Large nodules 1-3cm(Easily seen on CXR)

HRES CTAnatomy of pulmonary lobule

(1) interlobular septa(2) centrilobular region (3) lobular lung parenchyma

Secondary pulmonary lobule

Blue = Pulmonary veinsGreen = lymphatic'sYellow= bronchiolar branchesRed = ArteriesWhite = Connective tissue

Computed Tomography of the lung p9

Secondary pulmonary lobule

Prof Naidich

HRES CT

• Interstitial nodules vs Air space nodules

WEB-Algorithmic approach to nodules

Interstitial Air space

Well defined Ill defined

Soft tissue attenuation Homogenous soft tissue

Obscure edges of vessels they touch

Hazy and less dense than adjacent vessels

Peripheral in Pulm. Lobule Central

P120 High resolution CT lung ,Web - approach

CT of the lung , p74

CT of the lung , p72

HRES CT

High resolution CT lung ,Web – Algorithm 4

Airspace nodules

• = centrilobular distribution• = no pleural/septal nodules• Ground-glass opacification/ less dense than

adjacent blood vessels

Centrilobular nodules : Tree in Bud

Tree – in - Bud

• PT with TB• Indicative of endobronchial spread

P83, Computed Tomography of the Lung,Verschakelen

Infective bronchiolitis Tree in Bud appearance Bronchial wall thickening

Computed Tomography of the Lung,Verschakelen

HRES CT

Tree in bud absent

High resolution CT lung ,Web - approach

Centrilobular: Tree in bud absent

Poorly defined hazy ground glass nodules• Respiratory bronchiolitis• Langercell histiocytosis• Lymphocytic interstitial pneumonitis

Interstitial nodules

• = pleural/ septal predominance

HRES CTPerilymphatic

High resolution CT lung ,Web - approach

Perilymphatic disease• Clustered nodules• Adjacent to fissures

and pleural surfaces and along central vascular structures

• DDX: Sarcoid, silicosis, CWP.

• Rare: Amyloid ,LIP

• Sarcoidosis

P83, Computed Tomography of the Lung,Verschakelen

Silicosis

Web p305

Web p 306

Coal workers pneumoconiosis

Web p 306 Diffuse pattern more in favour of CWP or silicosis than sarcoidosis

HRES CTRandom

High resolution CT lung ,Web - approach

Random nodules• Sharply define,+- feeding

vesselDDX

1. Metastases: lung, breast, kidney, colon, melanoma, thyroid , pancreas

2. Infection: Milliary TB, septic emboli, fungal infection

3. Vasculitis4. Langercell histiocytosis

Metastases• Random• Basilar

predominance

P82, Computed Tomography of the Lung,Verschakelen

CT of the lung, p 75

Perilymphatic vs. centrilobular

TBCentrilobular 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.

High resolution CT lung ,Web - approach

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, congenitalRisk : 30-40% malignant

Radiographics 2000:20: 43

Approach to SPN

• Morphology: • - Size ( smaller more likely benign)• - margins and contours

Margins Risk for malignancy

Smooth 21%

Lobulated ( uneven growth 75%

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

Radiology Nov 2005 p 398