Chest Radiograph - Bronchiolitis-3

• General Radiology PHA-649P discusses Chest Radiograph - 3
• This presentation aims to help learners identify infectious disorders of the respiratory system and explain the radiographic appearance of different stages of tuberculosis

Bronchiolitis Definitions/Abbreviations

• RSV is respiratory syncytial virus
• Hyperinflation involves increased intercostal spaces, flattened diaphragms, increased retrosternal space, horizontal ribs, enlarged heart, and decreased vascularity
• Peribronchial thickening (cuffing) presents as a donut sign due to fluid/mucus buildup in the walls
• Band atelectasis, or discoid/plate atelectasis appears as a linear, horizontal shadow, usually caused by subsegmental bronchial obstruction
• Air trapping means lungs don't fully deflate, with radiolucency, evident on expiratory views with differing lung densities
• Barrel chest is an increased AP diameter where the chest is rounder and wider from front to back
• Centrilobular nodules are at small airways, spare subpleural surfaces, well defined or ground glass nodules

Bronchiolitis

• History and Physical findings include cough, congestion, difficulty breathing, wheezing, and nasal flaring
• Diagnosis involves H&P, and ruling out RSV
• X-ray findings include hyperinflation of the lungs, peribronchial thickening, band atelectasis, small lobar air trapping, and increased AP diameter of airways
• CT RSV indicates bronchiolitis, where axial CT shows multifocal bilateral centrilobular nodules, tree-in-bud opacities, and patchy ground-glass opacity areas
• Coronal CT better demonstrates the diffuse distribution of the disease process, with coalescing upper lobe lobular ground-glass opacities consistent with developing bronchopneumonia

Bronchiectasis

• H&P includes chronic cough, purulent sputum, wheezing, hemoptysis, and cystic fibrosis
• Diagnosis includes Chest CT
• X-ray findings via AP chest show coarsening of lung markings, thickened, irregular lines resembling tram tracks or railroad tracks, ring shadows, air fluid levels, cysts, and irreversible widening of bronchial airways with impaired mucus clearance
• In young adults with cystic fibrosis, mucous plugging of dilated airways can be seen

Acute Bronchitis

• H&P includes cough, sputum, and wheezing, with no signs of pneumonia
• Diagnosis includes H&P with helpful X-ray, pulse oximetry, and sputum culture, and ruling out asthma and pneumonia
• X-ray is usually normal but can have bronchial wall thickening

Epiglottitis

• H&P includes distress, drooling, dysphagia, and dysphonia
• Diagnosis involves clinical suspicion and definitive flexible fiberoptic laryngoscopy
• X-ray findings include lateral neck X-ray and "Thumb Sign" where swollen, enlarged epiglottis resembles a thumb
• Thickened Aryepiglottic Folds may also appear thickened on X-rays
• Smaller Vallecula means the pre-epiglottic space (vallecula) may appear smaller than normal

Croup (aka laryngotracheobronchitis)

• H&P includes barking (seal-like) cough, stridor, hoarseness, and aphonia
• Diagnosis involves H&P
• X-ray findings include Neck PA indicating subglottic narrowing with a steeple sign

Retropharyngeal Abscess

• H&P includes drooling, fever, neck swelling, limited range of motion, and stridor
• Diagnosis includes lateral neck radiographs
• X-ray findings include soft tissue swelling posterior to the pharynx, with a widening of the prevertebral soft tissue
• Normal prevertebral soft tissue thickness includes C3 <5 mm and C6 <22 mm, with a slight convex bulge anterior to the C1 anterior tubercle and a concavity caudal to the tubercle

Tuberculosis (TB)

• H&P for Primary TB includes cough, fever, weight loss, hemoptysis, night sweats
• Diagnosis involves CXR, sputum culture for AFB (acid-fast bacilli) (gold standard), NAAT (nucleic acid amplification), TST (tuberculin skin test), and bronchoscopy for lung biopsy
• X-ray findings consist of hilar or mediastinal lymphadenopathy, +/- pleural effusion, and middle lung with Ghon focus or complex
• Primary TB involves a Ghon focus, a small, localized area of granulomatous inflammation in the lung tissue, usually in the lung periphery, such as the apex of the left lower lobe
• The Ghon complex occurs when the Ghon focus accompanies involvement of the draining regional lymph nodes (hilar or mediastinal)
• Lung window axial plane CT confirms a 27 mm nodule in the lingula with adjacent tiny satellite nodules, but no lymphadenopathy
• Inactive (Latent) Primary TB is accompanied with no symptoms
• Diagnosis includes CXR, TST +, with negative sputum culture (not replicating)
• Fibrotic lesions or scars, calcifications, atelectasis, and Ranke's complex appear on X-ray
• Calcification in the lung and calcified lymph nodes, also known as Ranke's complex, indicates Latent Primary TB
• Secondary TB involves reactivation of a dormant infection from a previous primary TB infection with the same H&P plus potential extrapulmonary involvement
• Secondary TB appears years after primary infection, usually in the lung apices
• Cavitation may also be present
• Miliary TB is a hematogenous form of active TB

Miliary TB

• H&P entails an acute or subacute illness following initial infection with high-grade intermittent fevers, anorexia, weight loss, night sweats, rigors, pleurisy, peritoneal pain, and headache
• Diagnosis is the same as primary TB
• X-ray may show Miliary deposits that appear as 1-3 mm diameter pulmonary nodules (millet-seed-like granulomas) that are uniform in size and distribution

Practice Case

• A 22-year-old with a 2-month history of chronic cough and low-grade fever after visiting Southeast Asia has increased Primary TB risk
• HR=90, RR=20, BP 110/80, T=99, Wgt=99 lb and PE=+crepitations apices bilaterally
• CXR of the upper lobe indicates bilateral infiltrates without cavitation with positive sputum for AFB
• The most likely diagnosis is Primary TB due to no cavitation, symptoms developed right after visiting Asia indicating it's not following Lentent TB, no prior TB indication which means Secondary TB is less likely and no millet seed is found which means Miliary TB is unlikely