Lung Radiology

Lung Radiology 1


2INTRODUCTION


Radiologic evaluation of lung lesions can serve many roles including primary detection, narrowing of the differential diagnosis, treatment or surgical planning, and posttreatment surveillance. Plain radiographs are often the first-line modality for evaluation of symptomatic individuals and may be the source of detection of a lung lesion incidentally discovered during the course of other medical work-up. Nevertheless, CT remains as the mainstay of imaging characterization of lung disease due to its widespread access and excellent spatial resolution. CT is also often used as a rapid method of assessing the entire body for metastatic disease in the setting of lung malignancy. CT has a significant advantage over MRI in avoiding motion-related artifacts from breathing, due to the short image acquisition times possible with CT. MRI, on the other hand, is very useful in certain specific situations where its superior contrast resolution can better delineate soft tissue anatomy, such as in the evaluation of mediastinal or superior sulcus invasion by tumor. More recently, F-18 fluorodeoxyglucose-PET has become another widely used tool in diagnostic imaging of lung disease. Fluorodeoxyglucose-PET imaging utilizes the hypermetabolism of most tumors as a method of tumor localization and can be a very powerful tool in detection and assessment of tumor location and activity, sometimes revealing malignancy in places that would otherwise be overlooked by anatomic imaging alone.


In spite of all the technical advances in imaging, clinical and pathologic correlation are often necessary for accurate diagnosis. Image guidance with fluoroscopy, CT, ultrasound, and MRI is commonly used for minimally invasive tissue sampling in the hopes of avoiding or better preparing for a more extensive surgical approach.


This chapter presents the radiologic imaging of a sample of lung pathologies presented in the following order: malignant primary lung carcinoma, benign primary lung neoplasms, metastatic disease, infections, and other miscellaneous lung lesions, some of which can mimic neoplasm on imaging. The goal of this chapter is to provide some insight into the strengths of imaging in diagnosis of lung pathology and to highlight the crucial role that patient history and pathologic correlation often play in overcoming the limitations of imaging alone in order to arrive at a final diagnosis.



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Figure 1.1a — Squamous Cell Carcinoma. Chest radiograph shows a cavitary lesion in the right upper lobe (between arrows). Right minor fissure thickening is also noted (arrowhead).



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Figure 1.1b — Squamous Cell Carcinoma. Axial CT with contrast in soft tissue windows shows an irregular, enhancing nodular component within the cavitary mass. Mediastinal lymphadenopathy is also noted (arrows).



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Figure 1.1c — Squamous Cell Carcinoma. Coronal CT in lung windows demonstrates the thick wall of the cavitary lesion (arrows). Differential considerations include Aspergillus colonization of a preexisting cavity (mycetoma), tuberculosis, or Wegener’s granulomatosis, although the irregular enhancing nodular component highly suggests lung carcinoma. Cavitation is more common with squamous cell lung cancer than other types.



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Figure 1.1d — Squamous Cell Carcinoma. Axial postcontrast image through the upper abdomen shows an enhancing right adrenal nodule (arrow) compatible with metastatic disease.



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Figure 1.2a — Squamous Cell Carcinoma. Axial CT image showing a large, enhancing mass in the left upper lobe invading the chest wall with associated rib destruction (arrow).



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Figure 1.2b — Squamous Cell Carcinoma. PET-CT fusion image shows marked hypermetabolism in the mass consistent with the history of carcinoma. Chest wall invasion would make this lesion at least T3 using the tumor node metastasis staging system.



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Figure 1.3a — Squamous Cell Carcinoma With Postobstructive Pneumonia. Frontal chest radiograph with asymmetric increased opacification of the left lung and nonvisualization of the left heart border, suggesting a left upper lobe process.



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Figure 1.3b — Squamous Cell Carcinoma With Postobstructive Pneumonia. Axial CT with contrast confirms complete loss of aeration of the left upper lobe secondary to an obstructing mass (between arrows). The mass invades the visceral pleura and pericardium. There is a small, malignant pericardial effusion present (arrowhead).



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Figure 1.3c — Squamous Cell Carcinoma With Postobstructive Pneumonia. CT image obtained more superior shows obstructive atelectasis of the left upper lobe and dilated bronchi filled with low density mucus and inflammatory cells (arrowheads). Mediastinal adenopathy is also noted (arrows).



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Figure 1.4a — Adenocarcinoma. Chest radiograph showing a right lung pulmonary nodule with ill-defined margins (arrow).



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Figure 1.4b — Adenocarcinoma. Coronal CT in lung windows shows the nodule in the right upper lobe with spiculated margins (arrowheads), often seen with adenocarcinoma. Adenocarcinoma is the most common primary lung cancer to present as a solitary pulmonary nodule, as in this case.



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Figure 1.5a — Adenocarcinoma. Large, heterogeneous right lower lobe mass seen on contrast enhanced chest CT. The mass shows enhancement, with central low density (arrow) compatible with central necrosis.



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Figure 1.5b — Adenocarcinoma. Lung window shows thickening of the adjacent lung interstitium (arrowheads) representing lymphangitic spread of the tumor. A small satellite tumor nodule is also noted (arrow).



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Figure 1.6a — Adenocarcinoma, Pancoast Tumor. Fifty-nine-year-old male smoker presenting with left shoulder pain. Frontal radiograph shows asymmetric left apical fullness (arrow) and mild left hemidiaphragm elevation.



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Figure 1.6b — Adenocarcinoma, Pancoast Tumor. Fifty-nine-year-old male smoker presenting with left shoulder pain. CT shows a medial left apex mass (m) with large amount of pleural contact suggesting invasion. Note the severe emphysema in the lung apices.



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Figure 1.6c — Adenocarcinoma, Pancoast Tumor. Fifty-nine-year-old male smoker presenting with left shoulder pain. Coronal postcontrast CT image shows the mass (between the arrowheads) encasing the left subclavian artery (arrow) and left vertebral artery origin (black arrow).



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Figure 1.6d — Adenocarcinoma, Pancoast Tumor. Fifty-nine-year-old male smoker presenting with left shoulder pain. PET-CT clearly shows the hypermetabolic tumor at the left apex. In cases of superior sulcus tumor, MRI is superior to CT for evaluation of the extent of involvement of adjacent structures including the great vessels, brachial plexus, ribs, and vertebral column.



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Figure 1.6e — Adenocarcinoma, Pancoast Tumor. Fifty-nine-year-old male smoker presenting with left shoulder pain. Sagittal T2 weighted MRI through the left lung apex shows encasement of the left subclavian artery and left vertebral artery origin (arrow) by tumor. The tumor (between arrowheads) also extends posteriorly to involve the brachial plexus, specifically nerve roots C8 and T1 (labelled).



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Figure 1.7 — Adenocarcinoma in Situ, Nonmucinous Subtype. CT image in lung windows shows the classic appearance of nonmucinous adenocarcinoma in situ with a left upper lobe ground glass nodule containing air bronchograms (arrow). PET is often of limited value as bronchoalveolar carcinomas often show only mild fluorodeoxyglucose uptake. Other differential considerations for a ground glass nodule include hypersensitivity pneumonitis, pneumonias (particularly Pneumocystis, viral), pulmonary edema, pulmonary hemorrhage, and bronchiolitis obliterans organizing pneumonia.



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Figure 1.8a — Bronchoalveolar Carcinomas, Mucinous Subtype. Axial CT through the lung bases shows bilateral multifocal consolidation (arrows).



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Figure 1.8b — Bronchoalveolar Carcinomas, Mucinous Subtype. Postcontrast images show vessels coursing through the area of consolidation in the right lower lobe (CT angiogram sign, arrow), confirming that this is an area of alveolar filling, rather than a large mass. The differential for such consolidation is large and includes pulmonary edema, pneumonia, and hemorrhage, among several others. This case proved to be bronchoalveolar carcinomas. The mucin produced by the tumor can cause consolidation and can demonstrate endobronchial spread.



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Figure 1.9a — Small Cell Carcinoma. Left superior parahilar mass (between arrowheads) with enhancement and probable areas of necrosis. Mediastinal adenopathy (arrow) is present.



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Figure 1.9b — Small Cell Carcinoma. The mass shows marked fluorodeoxyglucose (FGD) uptake. Some increased uptake is also seen in the mediastinal lymph node (arrow).

Mar 31, 2019 | Posted by in RESPIRATORY | Comments Off on Lung Radiology
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