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MI6 Medical Imaging Chest Imaging
RUL LUL LUL
RUL RML
Toronto Notes 2019
LUL LLL
Soft Tissue Window
Bone Window
Lung Window
RML LLL RUL LLL
RML RLL
RLL
RUL: Right Upper Lobe; RML: Right Middle Lobe; RLL: Right Lower Lobe; LUL: Left Upper Lobe; LLL: Left Lower Lobe
Figure 3. Location of lobes of the lung
Computed Tomography Chest
Approach to CT Chest
• softtissuewindow
■ thyroid, chest wall, pleura
■ heart: chambers, coronary artery calcifications, pericardium ■ vessels: aorta, pulmonary artery, smaller vasculature
■ lymph nodes: mediastinal, axillary
• bonewindow
■ vertebrae, sternum, manubrium, ribs: fractures, lytic lesions, sclerosis
• lungwindow
■ trachea: patency, secretions
■ bronchial trees: anatomic variants, mucus plugs, airway collapse ■ lung parenchyma: fissures, nodules, fibrosis/interstitial changes ■ pleural space: effusions
• pleaserefertoTorontoNoteswebsiteforsupplementarymaterialonhowtoapproachaCTchest
Front AP Right-Lateral
Back AP
RLL
Left-Lateral
Figure 4. CT thorax windows
Table 4. Types of CT Chest
Standard
Low Dose CTA
Advantage
Scans full lung very quickly (<1 min)
± high resolution reconstructions
1/5th the radiation
Iodinated contrast highlights vasculature
Disadvantage Contrast
Radiation ±
Indication
CXR abnormality
Pleural and mediastinal abnormality Lung cancer staging
Cancer follow-up
Empyema vs. abscess
Lung cancer sScreening
Follow-up infections, lung transplant, metastases
PE
Aortic aneurysms Aortic dissection
Decreased detail
Contrast can cause severe allergic reaction and is nephrotoxic
No Yes
Figure 5. Atelectasis: RML collapse
DDx of Airspace Disease
Lung Abnormalities
Atelectasis
• pathogenesis:collapseofalveoliduetorestrictedbreathing,blockageofbronchi,externalcompression,
• Pus (e.g. infections such as pneumonia, non-infectious inflammatory process)
• Fluid (e.g. pulmonary edema)
• Blood (e.g. pulmonary hemorrhage)
• Cells (e.g. bronchioalveolar carcinoma,
lymphoma)
• Protein (e.g. alveolar proteinosis)
•
•
•
or poor surfactant findings
■ increased opacity of involved segment/lobe, vascular crowding, silhouette sign, air bronchograms ■ volume loss: fissure deviation, hilar/mediastinal displacement, diaphragm elevation
■ compensatory hyperinflation of remaining normal lung
differentialdiagnosis
■ obstructive (most common): air distal to obstruction is reabsorbed causing alveolar collapse
◆ post-surgical, endobronchial lesion, foreign body, inflammation (granulomatous infections, pneumoconiosis, sarcoidosis, radiation injury), or mucous plug (cystic fibrosis)
■ compressive
■ tumour, bulla, effusion, enlarged heart, lymphadenopathy
■ traction (cicatrization): due to scarring, which distorts alveoli and contracts the lung ■ adhesive: due to lack of surfactant
◆ hyaline membrane disease, prematurity
■ passive (relaxation): a result of air or fluid in the pleural space
◆ pleural effusion, pneumothorax management:intheabsenceofaknownetiology,persistingatelectasismustbeinvestigated(i.e.CT thorax) to rule out a bronchogenic carcinoma
Figure 6. Air bronchograms in right lung
© Anas Nader 2009