الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Summary
Cancer is one of the leading causes of morbidity and mortality even in devel¬oped countries. Complex clinical decisions about treatment of tumors are largely guided by imaging findings, among other factors. Most radiological procedures map the anatomy and morphology of tumors with little or no information about their metabolism.
Lung cancer is a common disease that has a poor prognosis. Survival is inversely proportional to the stage, with early detection and diagnosis being the key to achieving surgical cure. Cross-sectional imaging is now the main radiological means of assessment. Chest radiography is still important, and frequently suggests the first diagnosis, but its relative insensitivity has led to CT scanning being currently evaluated in screening studies.
Currently there is little to choose between CT and MRI in staging the disease although CT is more widely available and less expensive. MRI imaging offers heightened sensitivity for both detection of the primary malignancy and disease spread, although it is not 100% accurate and is only available in a few centers.
Accurate evaluation of disease extent prior to therapy and of response to therapy have a significant impact on the clinical management of oncologic disorders. Co-registration of PET scans (functional and morphologic information) with computed tomographic (CT) scans (anatomic information) using a combined PET/CT scanner improves the overall sensitivity and specificity of information provided by PET or CT alone. The unique advantage of PET/CT fusion imaging is the ability to correlate findings at two complementary imaging modalities in a comprehensive examination. Hence, PET/CT provides more precise anatomic definition for both the physiologic and pathologic uptake seen at FDG PET.
PET/CT is a major development in imaging technology and it represents more than just a combination of their two component parts. Previously, studies have concentrated on the role of individual PET and CT in lung cancer staging. Currently available data on PET/CT suggests that its superiority to lone PET lies principally in better T staging, but it also provides tangible benefits for N and M staging. As with PET, hybrid PET/CT also appears to have a role in selecting patients for mediastinoscopy because of its high negative predictive value for nodal disease.
CT examination inevitably resulting in some duplication. With advances in PET/CT technology and the advent of new protocols incorporating intravenous contrast, the possibility arises for PET/CT to act as a ‘‘one stop’’ diagnostic imaging device.
Non–small cell lung cancer (NSCLC) accounts for approximately 75% of all lung cancers. NSCLC is subdivided into adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Despite their histologic and clinical differences, they share a similar prognosis and management and are staged by using the same TNM system.
Surgery is the treatment of choice for NSCLC if the primary tumor is resectable and if metastatic disease is absent. Chemotherapy and radiation therapy are used to treat tumors that are unresectable because of intrathoracic spread or distant metastases. Small cell lung cancer (SCLC), which metastasizes early and has a worse outcome than NSCLC, has a separate staging system.
Metabolic imaging has provided a great opportunity for improving the management of NSCLC. PET/CT imaging, which combines both functional and morphologic imaging in a single examination, has shown how the initial staging and subsequent follow-up of patients with NSCLC can supersede more traditional methods of evaluation in terms of diagnostic accuracy. In particular, PET/CT imaging can predict prognosis, assess tumor response to treatment, and influence treatment plans by detecting unexpected sites of mediastinal and metastatic disease. The clinical applications of PET/CT are still evolving, and future research will determine the precise role that metabolic imaging has to play in the management of patients with lung cancer.
Use of dual-modality PET/CT significantly increases the number of patients with correctly staged non–small cell lung cancer (NSCLC) and thus has a positive effect on treatment.
PET/CT imaging is changing the care of patients with lung cancer in several ways:
a) Metabolic and anatomic whole-body staging of patients can be performed in one examination and much reduced scan times, thus, increasing patient comfort.
b) Because of limited patient motion, near ideal fusion of metabolic and anatomic images can be achieved.
c) Anatomic landmarks provided by CT will greatly facilitate the assignment of functional abnormalities to anatomic structures.
d) ”Difficult to image” regions of the body (such as the head and neck and mediastinum) will be evaluated with a high diagnostic accuracy.
e) Fused images can be used to target radiation treatment more accurately and monitor the effects of chemotherapy, surgery, and radiation treatment.
Conclusion
PET/CT is a safe, noninvasive technique that frequently allows fast and accurate diagnosis of lung cancer. PET/CT improved the diagnosis and staging of lung cancer through better anatomic localization and characterization of suspicious PET findings. This resulted in a clinically significant impact on patient management.