Pulmonary Radiography Notes 2025 PDF

Pulmonary Radiography Robson F. Giglio, DVM, MSc, PhD, DACVR Assistant Professor, Diagnostic Imaging College of Veterinary Medicine University of Georgia...

Pulmonary Radiography Robson F. Giglio, DVM, MSc, PhD, DACVR Assistant Professor, Diagnostic Imaging College of Veterinary Medicine University of Georgia Founder and President – ZEWDIS / ACVR Goals Identify the characteristics of the pulmonary patterns Generate appropriate differential diagnoses based on the predominant pulmonary pattern, location/distribution, and signalment and clinical signs Review of the “Normals”: Radiographic Anatomy of the lungs Lung lobes Dogs and cats Named for the branching of 4 lobe in the right the principal bronchi into the 2 lobes in the left lobar bronchi Left principal bronchus: 2 lobar bronchi: Cranial and Caudal Cranial lobar bronchus immediately divides into cranial and caudal subsegments of the cranial lobe Right principal bronchus: 3 lobar bronchi: Cranial, Middle, and Caudal Accessory originates from the right caudal lobar bronchus media.news.health.ufl.edu/misc/vetmed/gvi/canineairways/CanineAirways.html Positions of the Lung Lobes – VD View Cr - L Cr R Cr Ca - L Cr R Middle L Ca R Ca L Ca Accessory Positions of Right Lung Lobes – Left Lateral R Ca R Ca Accessory Accessory R Cr Cr – R Mid L Cr Positions of Left Lung Lobes – Right Lateral L Ca Cr - L Cr R Cr Ca - L Cr  Canine Pulmonary Air Flow media.news.health.ufl.edu/misc/vetmed/gvi/canineairways/CanineAirways.html Pulmonary Parenchyma A 3 components contribute to what is seen: B A - Air within the small airways and alveoli B - Blood vessels C - Airway walls C Canine and Feline: 6 lobes Radiographic Evaluation of the Lungs  Radiographic Evaluation of the Lungs Important to take THREE projections of the thorax Lesion conspicuity Both laterals (RL and LL) VD or DV  Radiographic Evaluation of the Lungs Normal pulmonary opacity Reduced pulmonary opacity Increased pulmonary opacity Most of the diseases Pulmonary patterns Reduced pulmonary opacity Pulmonary (hyper)lucency Lungs appear more black/darker Increased gas and decreased soft tissues in the lungs (i.e. small vessels, no vessels)  Reduced pulmonary opacity - DDx Diffuse changes Focal changes Hypovolemia (Multi)Focal lucency(ies) Small vessels, small heart, small CdVC Hypovolemic shock, Hypoadrenocorticism Bulla, bleb, pneumatocele, cavitated mass Increased thoracic volume Regional oligemia Hyperinflation / air trapping Pulmonary Feline asthma thromboembolism (PTE) Bronchial dilation Artifact Bronchiectasis Overexposure Reduced pulmonary opacity: Diffuse Reduced pulmonary opacity: Diffuse Flattening of the diaphragm Tenting of the diaphragm Reduced pulmonary opacity: Focal Bullous emphysema Large emphysematous cyst  Pulmonary Patterns (increased pulmonary pattern) – Radiographic approach Pulmonary patterns Increased pulmonary opacity o Lungs appear whiter o Most of the diseases!! Causes: Soft tissue opaque material within the air spaces Blood, pus, water, cells Thickening of the pulmonary interstitium / connective tissue Nodules/masses Bronchial wall thickening Enlarged pulmonary vessels Pulmonary patterns Somewhat complicated subject Breaking in pieces Lung patterns for teaching purposes The majority are mixed patterns In order to narrow down the differential list): ⮚ Pattern (recognition of the most predominant/important pattern) ⮚ Location Cone of certainty  Pulmonary Patterns ⮚Alveolar ⮚Interstitial ⮚ Unstructured ⮚ Structured (military, nodular, masses) ⮚Bronchial ⮚+/- Vascular ⮚ Enlarged pulmonary arteries, veins, or both ⮚ Small pulmonary arteries, veins, or both My first question is: Can I see vessels?  Pulmonary Patterns Unstructured interstitial and alveolar patterns are related ❑ “A continuum” ❑ Similar list of differential diagnoses ❑ Attempt to classify differentials by location ❑ Cranioventral: Bronchopneumonia ❑ Caudodorsal: Pulmonary Edema ❑ Ventral: Aspiration pneumonia ❑ Multifocal: Contusions, Fungal Pneumonia, Metastasis ❑ Diffuse: Lymphoma, ARDS ❑ Pattern Reflects SEVERITY ❑ Unstructured Interstitial Alveolar ❑ Which way is it going? Recheck Exam!!!!  Pulmonary Patterns Unstructured interstitial and alveolar patterns are related ❑ Fog / pulmonary vessel analogy Alveolar Severe unstructured interstitial Moderate unstructured interstitial Mild unstructured interstitial Normal  Pulmonary Patterns Unstructured interstitial and alveolar patterns are related ❑ Fog / pulmonary vessel analogy Alveolar Severe unstructured interstitial Moderate unstructured interstitial Mild unstructured interstitial Normal Alveolar and Unstructured Interstitial Patterns Common Differentials Atelectasis Pulmonary edema Aspiration pneumonia Cardiogenic Non-cardiogenic Bronchopneumonia Pneumonitis Neoplasia Lymphoma (unstructured interstitial) Alveolar pattern Alveolar pattern Very important !! Four main features: ❑ Uniform grey (Absent visualization of vessels) ❑ Border effacement (silhouetting) with adjacent soft tissue/fluid opaque structures ❑ Air broncograms ❑ Lobar sign Alveolar pattern: Scheme  Alveolar pattern Air Bronchogram Air filled bronchus surrounded by soft tissue opaque lung Lobar Sign Abnormal lung border contrasted with normal lung Lobar sign border The disease is respecting the lobar border! Air bronchogram 3 0 Alveolar pattern: Example of the features Thrall, 7th ed, 2018 Alveolar pattern: Example of the features Thrall, 7th ed, 2018 Unstructured interstitial pattern  Unstructured Interstitial Radiographic Finding: Increased soft tissue opacity that partially obscures pulmonary vascular margins Hazy Never mild! – Moderate and severe 3 4  Unstructured interstitial pattern: Scheme Variable Ddx: From underexposed films, expiratory radiograph to interstitial pneumonia and neoplasia Unstructured interstitial pattern: Example of the features Thrall, 7th ed, 2018 Different species, different amount of connective tissue in the lungs Dogs and cats < Horses < Farm animals Macrochelys temminckii Fake outs and DDx for unstructured interstitial pattern Underexposure Expiratory radiographs Large body habitus If real: Pneumonia Pneumonitis Fibrosis (WHWT) Lymphoma Fake out for unstructured interstitial pattern Expiratory Inspiratory Structured interstitial pattern Structured interstitial pattern Technical names for nodules and masses Difference in size Miliary ~ 1mm Nodule < 3cm Mass > 3 cm Structured interstitial pattern: Scheme Miliary, nodules, and masses Solid vs/ cavitated Soft tissue vs mineral opaque 43 Structured Interstitial Pattern: Miliary DDx: Fungal pneumonia Metastatic neoplasia Very small nodules – pinpoint lesions  Structured Interstitial Common Differentials for Nodules: Metastatic Neoplasia Mammary carcinoma Hemangiosarcoma Thyroid carcinoma Etc Fungal Pneumonia Blastomycosis Often + TB lymphadenopathy Less common DDx in Small Animals: Benign Pulmonary Osteomas Abscesses and granuloma formation Mineral opaque  Structured Interstitial - DDx Common Differentials for Masses: Primary Neoplasia Bronchoalveolar carcinoma Histiocytic sarcoma Lymphoma Etc Inflammatory (usually in young dogs) Pulmonary eosinophilic granulomatosis Lymphomatoid granulomatosis Abscess Granuloma Lung lobe torsion Not a true structured interstital pattern, but may look like a mass Structured interstitial pattern: Example of the features Structured interstitial pattern: Example of the features Thrall, 7th ed, 2018  Structured interstitial Nodules (< 3 cm in diameter) – Can be subtle – Look over diaphragm and vertebrae – Metastatic disease may change the patient’s prognosis / owner’s decision Fake-outs – End-on vessels – Cutaneous nodules – Nipples – Ectoparasites – Osteomas Structured Interstitial 50 Structured Interstitial Pattern - Cavitated Primary Lung Tumor - Cat  Structured Interstitial Pattern: Watch out for that! o End-on vessel: Same or smaller size than adjacent longitudinal (side-on) vessel More opaque than similar sized longitudinal (side-on) vessel Less numerous in periphery End-On Vessels End-On Vessels  Structured Interstitial Pattern: Pulmonary Osseous Metaplasia Heterotopic bone, pulmonary osteomas, osteomata, pneumoliths Small (< 5mm) May be numerous Often more ventrally Mineral opaque Structured interstitial pattern: Example of the features Thrall, 7th ed, 2018  Fake out: Cutaneous Nodule(s) oNipples, skin tags, papillomas, ticks ▪ Distinct, sharply marginated, opacity superimposed on lungs ▪ Surrounded by air (half of the surface) oCareful examination of patient oPositive contrast (Barium) or metallic marker ▪ Re-radiograph Bronchial pattern Bronchial Pattern Common Differentials: Bronchial wall mineralization (dogs) – not a bronchial pattern Chronic Bronchitis Infectious, allergic, irritant Asthma (cats) Eosinophilic Bronchopneumopathy (dogs) Heartworm disease (in combination with other findings) Bronchial pattern: Scheme Usually diffuse: Allergic, infectious or irritant etiologies. Less common: cardiogenic edema (cats) and neoplasia  Bronchial Pattern Chronic inflammation Major bronchi are normally visible in a central (hilar) position Always look in the periphery!! Thickened walls are abnormal RINGS and LINES – Donut and tram lines Usually generalized disease Cats: May have concurrent mucous plugs (small nodules) 6 0  Bronchial Pattern "Rings" – End on small airways "Lines" – Airways moving from central to peripheral position Bronchial Pattern Bronchial Pattern 6 3 Bronchial Mineralization: not a bronchial pattern! 6 4 Bronchial pattern: Bronchiectasis Abnormal and PERMANENT bronchial dilation Secondary to chronic airway disease Radiographic findings: Increased bronchial lumen diameter Failure to taper peripherally Thickened bronchial wall Bronchial pattern: Bronchiectasis Thrall, 7th ed, 2018 Location of the pulmonary changes General Divisions Caudodorsal Cranial Cranioventral Caudal Lung Lobe anatomy RCa RCr A RCr LCr RM Cr Seg LCr Cr Seg RM LCa A LCr A Cr Seg RCa LCa LCr Cr Seg Distribution of the Pulmonary Changes Cranial or caudal Dorsal or ventral Focal (lobar), multifocal or diffuse Hilar [yellow], mid-zone [red], or peripheral [blue] Differentials by location: Scheme - Normal (top left) - Cardiogenic edema (top right) - Non-cardiogenic edema (bottom left) - Aspiration pneumonia (bottom right) Differentials by location: Some examples Caudodorsal distribution Pulmonary edema (cardiogenic vs. non- cardiogenic) Differentials by location: Some examples Cranioventral distribution Aspiration pneumonia vs. bronchopneumonia Differentials by location: Scheme Variable location: - Hemorrhage/Trauma - Based on the trauma - Coagulopathy: diffuse - PTE - Peripheral to diffuse - ARDS - Usually diffuse Acute Respiratory Distress Syndrome Differentials by location: Scheme Variable location: - Hemorrhage/Trauma - Based on the trauma - Coagulopathy: diffuse - PTE - Peripheral to diffuse - ARDS - Usually diffuse Thoracic trauma  Some Definitions Ipsilateral mediastinal Consolidation shift ❑ Increase opacity with normal to increased lung volume ❑ Lungs are filled with something other than air: o Blood o Pus o Water o Cells Atelectasis (aka collapse) o Lungs are collapsed o Increased opacity with DECREASED lung volume o Possible underlying disease Both will result in an unstructured interstitial to alveolar pattern Atelectasis or not? Odd patterns Bulla Vesicular pattern – Lung lobe torsion Lung lobe torsion Uncommon Important DDx for lobar consolidation +/- vesicular pattern Abnormal lobar bronchial path Easier to seen on CT Concurrent pleural effusion (very common) Pugs (Left cranial LL) and Afghan Hounds (Right middle LL) Rare in cats Lung lobe torsion  “The Vascular Pattern" Any changes along pulmonary lobar vessels: Enlarged Small Tortuous Dennis. Radiologic Assessment of Lung Disease in Small Animals (Parts 1 and 2). In Practice 2008.  DDx for Pulmonary Lobar Vascular Abnormalities ❑ Enlarged arteries AND veins ❑ Enlarged ARTERIES with normal veins Fluid overload Pulmonary Hypertension Left-sided cardiac failure ▪ Heartworm disease ▪ specially in cats ▪ Important pulmonary fibrosis o Small arteries AND veins o Enlarged VEINS with normal Hypovolemia arteries Addison’s disease Left-sided heart failure Vascular pattern – Enlarged arteries Vascular pattern – Enlarged veins Pulmonary Hypertension RL DV Equine corner Equine Pulmonary Disease Same pulmonary patterns! - Associate predominant pulmonary pattern and location for DDx - DDx list may differ from dogs and cats Unstructured interstitial Alveolar Bronchial 87  Some examples: Cavitated structured interstitial pattern: Pulmonary abscesses Caudodorsal alveolar pattern: Caudodorsal (peripheral) unstructured Pulmonary edema interstitial pattern: Exercise-induced pulmonary hemorrhage Key concepts ❑Most pulmonary pattern are MIXED! o Identify predominant pattern o Identify lungs/portions involved o Note severity o Concurrent cardiac, pleural, or vascular changes? o Create rule out list ❑ Keys to differential diagnosis o Identify predominant pattern o Distribution ✔Identify vessels to help distinguish patterns ✔Recognize differences between atelectasis and consolidation Questions ?