-
Saber sheath trachea => coronal diameter of the trachea is narrowed to coronal/sagittal ration of < 0.6. Seen in patients with COPD.
Subsegmental anatomy:
Secondary lobule is comprised of three to five pulmonary acini (supplied by three to five terminal bronchioles.)
Pulmonary acinus is comprised of respiratory bronchiol, alvoelar duct, alveolar sacs.
Interlobular septa separate secondary lobules from each other.
Fissures
Superior accessory fissure => separates superior segment from the basal segments of the lower lobe.
Inferior accessory fissure (10-20%)
Azygous accessory fissure (0.4%)
Ligaments
Inferior pulmonary ligament => extends from hilum superiorly to level just above the hemidiaphragm.
Contains inferior pulmonay vein.
Pericardiophrenic ligament => seen along posterior side of the right heart border.
Contains phrenic nerve and pericardiophrenic vessels.
Bronchial arteries
One right sided
Usually arises at T5-T6 level (level of tracheal carina).
Two left sided
Pulmonary interstitium
Axial interstitium
Extends from hila to cetrilobular regions and envelopes bronchovascular bundles
Thickening is seen as peribronchial cuffing.
Peripheral interstitium => subpleural interstitium and interlobular septa
Contains pulmonary veins and lymphatics
Thickening is seen as thickened fissures and Kerley B lines.
Intralobular interstitium bridges centrilobular and peripheral compartments.
Thickening may account for some cases of ground glass opacities.
Canals of Lambert => bridge preterminal bronchioles
Pores of Kohn => interalveolar channels
-
Situs inversus
Kartegener’s syndrome => immotile cilia syndrome (respiratory infections and male sterility) + situs inversus
Absence of pericardium
Thoracic inlet
Thyroid
Goiter
Thyromegaly due to thyroiditis
Malignancy
Parathyroid
Hyperplasia
Adenoma
Carcinoma
Lymphoma
Lymphangioma
Cardiac
Anatomy
Coronary anatomy
RM => PDA + R marginal
LM
LAD => diagonal
LCx => obtuse marginals
RA
IVC => eustachian valve
Coronary sinus => thebesian valve
Lipomatous hypertrophy of interatrial septum
Arrhythmogenic right ventricular dysplasia
Replacement of right ventricular myocardium with fat or fibrous tissue
Focal wall thinning and aneurysm may also be seen
Cardiac aneurysm
False aneurysm => inferoposterior, narrow neck
True aneurysm => anteroapical, wide neck
Sinus of Valsalva aneurysm
Associated with aortic regurgitation
Mirror image right arch
Associated with TOF and truncus arteriosus
Mitral valve prolapse
In Marfan syndrome congenital prolapse occurs in the mitral and tricuspid valves
LAE in adult
Mitral stenosis
No cardiomegaly
Mitral regurgitation
Cardiomegaly
RAE in a female
ASD
Unilateral pulmonary arterial enlargement
Pulmonary stenosis
Pulmonary artery aneurysm
Central pulmonary enlargement
Primary pulmonary hypertension
Eisenmerger physiology
Pulmonary enlargement including peripheral vessels
Left-to-right shunts
ASD
VSD
TAPVR
Anterior mediastinum
Peds => cystic hygroma
Thymus
Thymoma (age > 40)
Drop metastses to ipsilateral pleura can be seen with invasive thymoma
Thymolipoma
Thymic cyst
Thymic hyperplasia
Thymic neuroendocrine tumors (carcinoid)
Thymic carcinoma
Lymphoma
Germ cell tumors
Thyroid
Parathyroid
Mesenchymal tumors
Lipoma
Hemangioma
Liposarcoma
Leiomymoma
Hemangiosarcoma
Cardiophrenic angle masses
Epicardial fat pad
Lipoma
Pericardial cyst
Foramen of Morgagni hernia
Middle mediastinum
Lymph node enlargement
Infection
Malignancy
Metastases
Bronchogenic carcinoma
Lymphoma
Leukemia
Kaposi’s
Idiopathic
Castelmans
Sarcoidosis
Angioimmunoblastic lymphadenopathy
Foregut cysts
Bronchogenic cyst
Subcarinal and right paratracheal are most common.
Homogenous near water attenuation
Pericardial cyst
Vascular
Posterior mediastinum
Neurogenic
Peripheral
Ganglia
Paraganglia
Neurofibroma
Ganglioneuroma
Chemodectoma
Schwannoma
Neuroblastoma
Pheochromocytoma
Ganglioneuroblastoma
Esophagus
Foregut cysts
Enteric
Neurenteric
Vertebral
Lateral thoracic meningocele
Pancreatic pseudocyst
Non-Hodgkins lymphoma
Extramedullary hematopoesis
Diffuse mediastinal disease
Infection
Chronic sclerosing fibrosing mediastinitis
Hemorrhage
Medistinal lipomatosis
Malignancy
Pneumomediastinum
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Large
Unilateral enlargement
Infection
TB
Malignancy
Small cell carcinoma
Pulmonary artery enlargement
Bronchogenic cyst
Bilateral hilar enlargement
Sarcoidosis
Infection
TB
Fungal: histoplasmosis, coccidiomycosis
Bacillus anthracis
Yersenia pestis (plaque)
Malignancy
Berylliosis, silicosis
Bilateral pulmonary arterial enlargement
Small
Unilateral
Hypoplasia or absence of pulmonary artery
Swyer-James
Hypoplastic or hypogenic lung
Compression or invasion
Cyst
Neoplasm
Fibrosing mediastinitis
Lobar resection
Bilateral
Emphysema
Pulmonary outflow obstruction
Fibrosing mediastinitis
Tetralogy of Fallot
Valvular pulmonic stenosis
Ebsteins anomaly
-
Tracheal narrowing
Saber-Sheath trachea (COPD)
Amyloidosis
Tracheobronchopathia Osteochondroplastica
Multiple submucosal osseous and cartilagenous deposits within trachea and bronchi of elderly men
Lesions arise as cartilage enchondromas
Calcified plaques involve anterior and lateral walls of the trachea
Posterior wall is spared in contrast to amyloid
Relapsing polychondritis
Systemic autoimmune disorder of the cartilage
Tracheal dilatation
Tracheobronchomegaly (Mournier-Kuhn syndrome)
Congenital disorder of the elastic and smooth muscle components
Associated with Ehlers-Danlos syndrome
Trachea measured more than 3 cm
Tracheobronchomalacia
COPD
Chronic bronchitis
Cystic fibrosis
Relapsing polychondritis
Tracheal neoplasms
Benign
Chondroma
Arises from cartilage
Stippled cartillagenous calcification on CT
Fibroma
Squamous cell papilloma
Young age (HPV)
Mucosal
Papillomatosis of the lung if causative agent spreads via bronchi
Hemangioma
Cervical trachea
Young age
Granular cell myoblastoma
Arises from neural elements
Malignant => 90% of primary tumors of the trachea in adults are malignant
Squamous cell carcinoma (most common) => 50%
Adenoid cystic carcinoma (cylindroma) => 40%
Arises from salivary glands
Involves posterolateral wall of distal 2/3 of the trachea or main or lobar bronchi
Mucoepidermoid carcinoma, carcinoid, lymphoma, small cell carcinoma, leiomyosarcoma, fibrosarcoma, chondrosarcoma
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Congenital
Broncholithiasis
Calcified peribronchial lymph nodes erode into bronchial lumen
Bronchiectasis
Three groups
Cylindrical
Varicose
Saccular
Causes
Cystic fibrosis
Elevated Na+ in the sweat
Infertility more common in males
Dysmotile cilia syndrome
Postinfectious
Allergic Bronchopulmonary Aspergillosis
Bronchial obstruction
Peribronchial fibrosis
Bronchial neoplasms
Benign
Hamartoma
Fatty center covered by fibrous tissue
Malignant
Carcinoma
-
Kulchitzky cell spectrum KCC-1 (low-grade) to KCC-3 (highly malignant)
No FDG avid
Gland neoplasms
Mucoepidermoid carcinoma
Small airway disease
Bronchiolitis
Bronchiolitis obliterans
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Distribution
Upper lungs
EG
Sarcoid
Silicosis
TB or histo
Brochiectasis from CF
Basilar
Asbestosis
Scleroderma
Rheumatoid
UIP, DIP
-
Air space
Reticular
Acute
Interstitial edema
Inflammatory: viral, mycoplasma, PCP
Chronic
Scleroderma
Rheumatoid
UIP, DIP, LIP
LCH
Sarcoidosis
IF
Collagen vascular diseases (scleroderma, SLE)
Atelectasis
Mechanism
Obstrutive
Passive – mass effect from pleural space. Compressive – intrapulmonary process
Cicatricial – parenchymal fibrosis results in volume loss
Adhesive – surfactant deficiency
Extent
Lobar
Segmental
Subsegemental
Rounded
Location (RUL, RML, RLL, LUL, LLL)
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Focal
Congenital
Bronchogenic cysts
Intrapulmonary sequestration
Bronchiectatic cysts
Cavity wall should be more than 1mm thick
Multiple cavities can result from necrosis after infection
TB, histoplasmosis, coccidiomycosis
Metastases
Vascular occlusions
Thromboembolism
Septic embolism
Vasculitis
Wegeners
Rheumatoid
Bulla = >1 cm with wall <1mm
Type 1 => Superficial, narrow neck
Type 2 => Parenchymal, vascularity present
Type 3 => Deep intraparenchymal
Air cyst = wall >1mm thick
Traumatic air cyst
Bronchiectatic cysts
Bleb = <1cm within layers of visceral pleura
Pneumatocele = distended air spaces
Healing phase of PNA
Post-traumatic pneumatocele from pulmonary laceration
PE => Westermark sign
Ischemic necrosis can result in a cavity
Diffuse
Unilateral
Swyer-James syndrome = adenoviral infection, asymmetric obliterative bronchiolitis, air trapping, unilateral pulmonary artery hypoplasia
Bilateral
Emphysema
Pathologic classification
Centrilobular
Panlobular
Alpha-1-antitrypsin deficiency
Paraseptal
Paracicatricial
Asthma
HRCT
Interlobular (Septal) thickening (ELIS)
Edema
Lymphangitic spread
IPF
Sarcoidosis
Intralobular
IPF
NSIP
Collagen vascular disease
HP – chronic
Sarcoidosis
Nodular
Cystic
IPF
LAM
LCH
LIP
DIP
PCP
BAC
Ground glass
HP
DIP
AIP
NSIP
Connective tissue disease
SLE
Drug induced
Hemorrhage
Consolidation
COP
Eosinophillic PNA – chronic
Lymphoma
BAC
Acute disease
Mosaic
Small airway disease
Pulm vascular disease
-
Bronchopulmonary sequestration
Bronchogenic cysts
Congenital cystic adenomatoid malformation
Pulmonary agenesis (lungs and associated tissues are absent)
Pulmonary aplasia (no lung parenchyma, but rudimentary main bronchus present)
Scimitar (Radiology 210 (1): 288)
Scimitar syndrome => always right-sided lobar hypoplasia or aplasia
Combination of
Anomalous venous drainage of all or most of the right lung to the right atrium or IVC
Hypoplasia of the right lung
Systemic arterial collateral vessels to the right lung
Associated with sequestration, cystic adenomatoid malformation, foregut malformations, ASD, VSD, TOF, PDA, accessory diaphragm, horseshoe lung
Scimitar vein
Vertical curvilinear vein that drains all or portion of the right lung to the right atrium or IVC
Scimitar sign
Scimitar vein visible on a chest radiograph
Unilateral pulmonary hypoplasia (normal main bronchus, rudimentary lung)
Congenital lobar emphysema
Results from any check valve bronchial obstruction
Hyperlucent lobe (as opposed to hyperlucent segment in bronchial stenosis or atresia)
Congenital bronchial atresia
-
-
Osler-Weber-Rendu disease
PAPVD
PA hypoplasia/atresia
-
-
Lobar PNA
Starts in alveolar spaces, spreads through pores of Kohn
Broncho PNA
Starts in the airway, spreads through canals of Langerhans
Interstitial PNA
Linear => viral, mycoplasma, PCP
Ground glass => PCP, CMV, Mycoplasma
Nodular
Miliary => TB, fungal
Nodular/mass
Round PNA
Lung abcess
Granulomatous infection
Actinomyces/Nocardia
Parasitic infection
Infection in immunocompromised patient
Lobar => bacterial, TB, parenchymal lymphoma
Nodular/cavities => bacterial, fungal (hematologic malignancy), malignancy (post-transplant lymphoproliferative disease, metastases)
Diffuse => PCP, viral (CMV, herpes), drug-induced, non-specific interstitial pneumonitis, hemorrhage, pulmonary edema
Complications of PNA
Lung abcess (spherical, destruction of adjacent parenchyma)
Empyema (lenticular, compression of adjacent parenchyma)
TB
Rasmussen aneurysm => pulmonary artery aneurysm in the tuberculous cavity.
Ranke complex is seen in primary TB
Ghon focus
Eosinophilic lung disease
Pulmonary alveolar proteinosis
Chronic alveolar proteinosis can have interstitial pattern
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Nomenclature
Kerley’s A = thickening of central connective tissue
Kerley’s B = thickening of peripheral interlobular septa
Kerley’s C = network of thickened interlobular septa
Hydrostatic
PCWP 8 – 12 = nl
PCWP 12-18 = constriction of lower lobe vessels and enlargement of upper lobe vessels
PCWP 19-25 = loss of vascular definition, peribronchial cuffing, Kerley’s lines
PCWP > 25 = alveolar filling, perihilar and lower lung zones bilateral air space opacities
Distribution is even from central to peripheral with over lower lung zones
Vascular pedicle (width at the level of SVC and LSCA) is > 53mm on PA
Permeability (ARDS)
Leakage of protein rich edema fluid
Distribution is peripheral with normal vascular pedicle width and normal heart size
Progression
12-24 hours: patchy peripheral air space opacities
Several days: Confluent bilateral air-space opacities with ABGram
First week may improve from increasing PPV
> 1 week: Coarse reticulonodular pattern
> 1 mos: resolves or irreversible pulmonary fibrosis develops
Neurogenic = massive sympathetic discharge
Hydrostatic and increased permeability
High Altitude
Reexpansion
RUL pulmonary edema
Preferential regurgitant flow into right upper lobe pulmonary vein in patients with severe mitral valve regurgitation
Acute upper airway obstruction
Amniotic fluid embolus
Acute cor pulmonale from sudden pulmonary arterial HTN after emboli obstruction of PA by mucin and fetal squames
Fat embolism
24-72 hours after FX of a long bone
-
Autoimmune (Radiographics 20(6), 1623)
Goodpasture’s
Hemorrhages
Wegener’s
Granulomatous vasculitis of upper and lower airways, diffuse small vessel vasculitis and focal glomerulonephritis
Ill-defined nodular masses that cavitate in 50% of patients
SLA
Rheumatoid Arthritis
Polyarteritis nodosa
Idiopathic
-
Westermark sign= oligemia
Hampton’s hump = infarction
-
PAP > 30
Calcifications on pulmonary arteries are rare but specific
Transverse diameter of pulmonary artery on PA CXR > 16 mm
Transverse measurement of main pulmonary artery on CT or MR > 28.6 mm
Idiopathic or primary pulmonary hypertension
Plexogenic pumonary arteriopathy => medial hypertrophy and intimal fibrosis obliterate muscular arteries. (Dilated vascular channels within periphery of the obliterated vessels produce plexogenic lesions seen on biopsy
Recurrent microscopic pulmonary emboli
Pulmonary venocclusive disease => transmission of increased pressure to arterial side results in medial hypertrophy and obliteration of vessels.
-
Primary lung vs. metastasis
In the absence of known primary maligancy, SPN is unlikely to be a metastasis
In patients with melanoma, sarcoma and testicular carcinoma, SPN is 2.5 times more likely to be a metastasis than a primary lung cancer
In patients with head and neck squamous cell carcinoma, a malignant SPN is 8 times more likely to be a primary lung cancer.
Calcification patterns
Benign
Central nidus
Laminated
Popcorn
Diffuse
If a nodule smaller than 9mm is seen on CXR, it is likely to be diffusely calcified and benign
In patient’s with history of bone malignancy, malignant SPNs may have benign calcification pattern
Malignant
Eccentric
Stippled
Amorphous
Diffuse
Enhancement pattern
Enhancement of less than 15 HU indicates benignity.
Size
< 5mm => Follow up in 1 year
5-9 mm => 3, 6, 12, 24 serial CT scans or FNA
1 cm => PET and contrast study
Differential
Malignant neoplasms
Pulmonary Hamartoma
Popcorn calcification
Bronchogenic cyst
NHL
Granular cell myoblastoma
Leiomyoma/Leiomyosarcoma
Fibroma/Neurofibroma
Lipomas
Hemangiopericytoma
Plasma cell granulomas
Lipoid PNA
Multiple pulmonary nodules
Sarcoidosis
Neoplasms
Lymphoma
Osteosarcoma => spontaneous PTX
-
-
Adenocarcinoma 35%
Peripheral nodule
Bronchoalveolar carcinoma is a subtype of adenocarcinoma
Produces mucin
Not FDG avid
Has ground glass appearance because the tumor grows along interstitium without invasion (lepidic growth).
Squamous cell carcinoma 25%
Hilar mass
Atelectasis
Small cell carcinoma 25%
Hilar mass
Mediastinal mass
Large cell carcinoma
Large peripheral mass
Giant cell carcinoma is a subtype of large cell carcinoma
Mixed cell carcinomas
Adenosquamous carcinoma
Carcinosarcoma
Sarcoma
Blastoma
Lymphoma
-
SPN
Rectosigmoid carcinoma
Osteosarcoma
RCC
Melanoma
Multiple – findings suggestive of metastastatis vs granulomas
Feeding vessel
No calcifications (except if known osseous lesion exists, calcifications can be malignant)
Presence of large nodule with miliary nodules
Lymphangitic carcinomatosis
Breast, stomach, pancreas, prostate
-
Iatrogenic lung disease
Drug reactions
Nitrofurantoin
Bleomycin
Alkylating agents (Cytoxan and busulfan)
Methotrexate
Amiodarone
Radiation induced lung disease
Doses of nore than 2000 rads
Pneumoconiosis
Silicosis
Acute: Bilateral perihilar consolidations/ground glass opacities/centrilobular nodules
Classic: 2mm-5mm nodules in the upper and posterior portions of the lungs in centrilobular, paraseptal and subpleural regions, some maybe calcified. Egg shell calcifications maybe present in the hilar and subcarinal lymph nodes.
Coal worker pneumoconiosis
Appearance is similar to silicosis
Asbestosis
Fibrosis at the lung bases. Prone imaging maybe needed to differentiate fibrosis related to asbestosis from dependent atelectasis.
Berryliosis
Hilar lymph node enlargement (similar to sarcoidosis)
Small nodules along bronchovascular bundles or interlobular septa
Hard-metal pneumoconiosis
Diffuse interstitial fibrosis
Talcosis
Generalized haziness, nodulation and reticulation with characteristic sparing of costophrenic sulci and apices.
Siderosis
Small perihilar centrilobular nodules
Branching linear structures, which are related to deposition of iron oxide particles can be seen.
Cystic changes
LAM – diffuse
EG – perdominantly involving upper lobes
Associated with tuberous sclerosis
-
Spontaneous PTX associated with
Osteosarcoma metastasis
Cystic fibrosis
LAM
Pleural effusion
Infectious
Cardiovascular
Neoplastic
Bronchogenic carcinoma
Metastases
Lymphoma
Immunologic
SLE
RA
Sarcoidosis
Trauma
Abdominal disease
Focal pleural thickening
Fibrosis from
PNA
PE
Asbestos exposure
Trauma
Chemical pleurodesis
Drug related pleural disease
Calcification
Prior hemorrhage
Prior empyema (TB)
Asbestos
Plaques are found in parietal pleura
Tumors
Localized fibrous tumors of pleura
Associated with hypertrophic pulmonary osteoarthropathy and hypoglycemia
Lipomas
Mesotheliomas
Benign (no association with asbestos exposure)
Malignant (associated with asbestos exposure)
Metastasis
Usually adenocarcinomas (lung and breast primaries), melanoma or invasive thymoma
Diffuse pleural thickening
Smooth
Fibrothorax
Lobulated
Multiloculated pleural effusion
Pleural malignancy
Mesothelioma
Metastases
-
Congenital
Diaphragmatic hernias
Hiatal hernia
Foramen of Bochdalek
Site of embryonic pleuroperitoneal canal (posterior)
Hernias are usually seen on the left side because of protective effect of liver
Foramen of Morgagni
Least common type of diaphragmatic hernia
Invariably right sided cardiophrenic angle mass
Trauma
Left-sided in 90% of the cases, because liver protects the right hemidiaphragm
-
Apical cysts
Langerhan’s cell histiocytosis
Lymphangioleiomyomatosis
Mediastinum
Congenital abnormalities
Anomalous right subclavian artery
Passes behind esophagus
Diverticulum of Kommerrel
Right aortic arch (descending aorta is usually left sided)
Mirror image
Right arch associated with anomalous left subclavian artery
Double aortic arch
No innominate artery
Symmetric appearance of great vessels
Coarctation and pseudocoarctation
Pseudocoarctation – kinked and somewhat narrowed but no significant pressure gradient exists
Both are associated with congenital bicuspid aortic valve
Aortic aneurysm
Ascending aorta more than 4 cm
Aortic dissection
Stanford Type A (DeBakey I – entire, and DeBakey II) and Type B (DeBakey III)