Thoracic Imaging

·         Size greater than 2 cm is more suggestive of malignant SPN. Lobulated or spiculated margins with distortion of adjacent vessels are typically associated with malignancy, although a lobulated or spiculated margin is seen in up to 25% and 10% of benign nodules, respectively. The "corona radiata" sign consists of very fine linear strands extending outward from a nodule and is strongly suggestive of malignancy. Partly solid nodules (i.e., nodules composed of "ground-glass" and solid components) tend to be malignant and are most often due to bronchioloalveolar cell carcinoma (BAC) or adenocarcinoma with BAC features. Internal inhomogeneity, particularly from cystic/bubbly lucencies or pseudocavitation, is strongly suggestive of malignancy, most often from BAC. Cavitary nodules with maximal wall thickness >15 mm and wall irregularity tend to be malignant, whereas those with wall thickness =4 mm tend to be benign.

·         Congenital bronchial atresia is due to atresia or stenosis of a bronchus at or near its origin, most often seen in the apicoposterior segment of the left upper lobe. Imaging findings include hyperlucency with air trapping and decreased vascularity to the portion of lung supplied by the involved bronchus, along with a nonenhancing hilar mass (bronchocele) or nonenhancing branching soft tissue opacities usually with bronchial dilation due to mucoid impaction. Congenital bronchial atresia can appear as an SPN on chest radiography.

·         Progressive massive fibrosis (PMF), also know as "conglomerate masses," is the radiographic feature most strongly associated with respiratory deficits.

·         INTERSTITIAL LUNG DISEASE

1.       Interstitial pulmonary edema, usually due to congestive heart failure, is the most common interstitial abnormality encountered in daily practice.

2.       The nodular pattern of interstitial lung disease appears as increased numbers of nodular opacities (<10 mm) that are randomly distributed throughout the lung parenchyma. The three broad groups of disorders that cause nodular interstitial disease are granulomatous lung diseases, nodular pneumoconioses, and small metastases.

3.       The two distinguishing features of the peripheral reticular pattern of interstitial lung disease are the small size of the holes (typically <5 mm) seen within a network of fine crisscrossing linear opacities and a peripheral and basilar distribution of this network. The vast majority of cases will be caused by IPF, a connective tissue disorder, or asbestosis.

4.       The linear pattern of interstitial lung disease appears as increased numbers of lines radiating from the hila centrally. This pattern also may produce peripheral Kerley's B lines. The most common cause of this pattern is congestive heart failure, although lymphangitic carcinomatosis is the most common chronic cause of this pattern.

5.       The cystic pattern is characterized by a group of curved lines that produce a network of fine ring shadows in the more central lung with larger holes than those seen in the peripheral reticular pattern. The most common cause of this pattern is emphysema.

·         MEDIASTINAL DISEASES

1. Lesions that arise in the different compartments of the mediastinum are generally related to the anatomic structures located within the compartments.
2. The majority of patients with asymptomatic mediastinal tumors have benign tumors, whereas the majority of patients with symptomatic mediastinal tumors have malignant tumors.
3. Thymoma is the most common primary tumor of the anterior mediastinum and of the thymus.
4. Primary testicular or ovarian germ cell tumor should be excluded when a mediastinal germ cell tumor is discovered.
5. Neurogenic tumor is the most common mass of the posterior mediastinum.

·         empyema necessitates: This is an uncommon complication of an empyema in which the inflammatory process within the pleural space decompresses and extends into the soft tissues of the chest wall, forming a subcutaneous abscess, which may or may not communicate directly with the skin surface. The most common etiologic factor is tuberculosis, and the most common clinical presentation is a palpable mass in the chest wall, sometimes with a cutaneous fistula. This extension into the chest wall will usually not be evident on chest radiographs but may be detected with CT or magnetic resonance imaging (MRI) of the thorax.

·         TUBES, LINES, AND CATHETERS

1.       If you see focal ovoid lucency surrounding an ETT or tracheostomy tube with an associated bulge in the adjacent tracheal walls, suspect overinflation of the cuff and notify the clinical staff immediately.

2.       If an NGT, OGT, or FT is seen to extend into a distal bronchus, lung, or pleural space, notify the clinical staff immediately and suggest that tube removal be performed only after a thoracostomy tube set is at the bedside in case a significant pneumothorax develops.

3.       Rapid development of an ipsilateral pleural effusion or mediastinal widening after venous catheter placement should lead one to consider venous perforation, with the tip located in the pleural space or mediastinum after catheter infusion, or vessel injury with associated hemithorax or mediastinal hematoma.

4.       When air embolism is suspected during line placement or use, the patient should immediately be placed in the left lateral position to keep the air trapped in the right heart chambers, supplemental oxygen should be administered, and vital signs should be monitored.

·         Twiddler's syndrome is a rare disorder in which a patient causes malfunction of a transvenous pacemaker or AICD by manipulating or "twiddling" with the pacing generator pack, which may be facilitated by a large pocket for the generator pack or loose subcutaneous tissue, leading to dislodgement of the pacing leads. Chest radiography is the key to diagnosis and typically shows twisting or coiling of the lead(s) about the axis of the pacemaker as well as possible lead fracture, displacement, or migration.