radiological imaging of pulmonary nodules

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Text of radiological imaging of pulmonary nodules

  • 1. Radiological imaging of the pulmonary nodules. Dr/ ABD ALLAH NAZEER. MD.

2. Pulmonary nodules What are pulmonary nodules? A pulmonary nodule is a small round or oval-shaped growth in the lung. It is sometimes also called a spot on the lung or a coin lesion. Pulmonary nodules are generally smaller than 3 centimeters in diameter. If the growth is larger than that, it is known as a pulmonary mass. A mass is more likely to represent a cancer than is a nodule. Pulmonary nodule is a mass lesion in the lung , not a lesion arising from alveoli. It may be solitary or multiple and is usually round or oval in shape. 3. Objectives: Should be able to: Identify, characterize and described nodular lung pathology. Appreciate nodules as mass lesions in lung irrespective of their size. Differentiate from patches of consolidation. Common causes of solitary and multiple pulmonary nodules. Presentation of pulmonary nodules. It may be asymptomatic and discovered incidentally in periodic check up or in pre-operative X-Ray of the chest. May be symptomatic such as cough and cough up blood. Cervical lymphadenopathy. Finger clubbing. Rash-Vasculitis. Source of metastasis(Abdomen, Breast or thyroid). 4. What causes pulmonary nodules? There are two main types of pulmonary nodules: malignant (cancerous) and benign (noncancerous). Over 90% of pulmonary nodules that are smaller than 2 centimeters in diameter are benign. Benign pulmonary nodules can have a wide variety of causes. Many are the result of inflammation in the lung as a result of an infection or disease producing inflammation in the body. The nodule may represent an active process or be the result of scar tissue formation related to prior inflammation. Benign developmental lesions may also appear as nodules. Infections Most infections that appear as with pulmonary nodules are relatively indolent and often not active. Examples include mycobacterium such as mycobacterium tuberculosis or mycobacterium avium intracellulare, and fungal infections such as aspergillosis, histoplasmosis, coccidiomycosis, and cryptococcosis. Inflammation related to infections often forms what is termed a granuloma. A granuloma is a small clump of cells that form when lung tissue becomes inflamed. Granulomas form when the immune system isolates substances that it considers foreign. Most of the time granulomas occur in the lungs, but they may also form in other parts of the body. They can become calcified over time, as calcium tends to collect in the healing tissue. 5. Noninfectious causes of benign inflammatory lung nodulesNoninfectious disorders such as sarcoidosis, Wegeners granulomatosis, and rheumatoid arthritis, also manifest with granulomas forming in the lungs. Wegeners granulomatosis is a rare autoimmune disorder whose exact cause is unknown. It causes the blood vessels to become inflamed and may result in sores (lesions) in the respiratory tract. Sarcoidosis also can result in inflammation of the lungs and other organs of the body. Its cause is unknown. NeoplasmsNeoplasms are abnormal growths that may be benign or malignant. Types of benign neoplasms include: fibroma (a lump of fibrous connective tissue) hamartoma (an abnormal grouping of normal tissues) neurofibroma (a lump made up of nerve tissue) blastoma (a growth made up of immature cells) Types of malignant tumors include: lung cancer lymphoma (a growth containing lymphoid tissue) Carcinoid (a small, slow-growing cancerous tumor) sarcoma (a tumor consisting of connective tissue) metastatic tumors (tumors that have spread to the lungs from cancer in another part of the body) 6. Imaging modalities. Computed Tomography: Contrast-enhanced CT of solitary pulmonary nodules has also been used to distinguish benign from malignant nodules. Results from a large multicenter study found that contrast-enhanced CT has a sensitivity of 98% and a specificity of 58% when using a cutoff of 15 Hounsfield units for enhancement. The absence of enhancement is a strong predictor of benignity . An analysis of combined wash-in and washout characteristics at dynamic contrast-enhanced multidetector CT showed 92% accuracy for distinguishing benign from malignant nodules. Magnetic Resonance Imaging: Use of magnetic resonance imaging (MRI) in evaluation of pulmonary nodules has thus far been limited. Faster imaging sequences and techniques to mitigate artifact have allowed for detection of smaller nodules (6-10 mm) with sensitivity near 95%. For nodules >1 cm, contrast- enhanced dynamic MRI has shown to be comparable to CT for distinguishing benign from malignant nodules with a sensitivity of 96%, specificity of 88%, and accuracy of 92% . 7. Positron Emission Tomography: Positron emission tomography (PET) using fluorine-18-2-fluoro-2-deoxy-D- glucose (FDG) has assumed a major role in the evaluation of patients with solitary pulmonary nodules. This technique relies on measuring glucose metabolism, which has been shown to be different between benign and malignant nodules. Many studies have demonstrated the accuracy of FDG-PET in evaluating solitary pulmonary nodules . The sensitivity and specificity for this technique, as reported in the literature, have ranged from 83%-97% and from 69%-100%, respectively. FDG-PET has a higher specificity and only slightly reduced sensitivity compared to nodule enhancement CT. Limitations of PET scanning include its inability to accurately characterize certain types of lesions, including low-grade adenocarcinoma and typical carcinoid tumors. It is also limited in its ability to characterize nodules