الفهرس 
PET/CTOnly 14 pages are availabe for public view
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Abstract
Modern clinical cancer treatments require precise positional information. where is the tumor located? How large is it? Is it confined, or has it spread to lymph nodes? Does it involve any critical anatomical structures that would alter the treatment strategy? These questions are being answered, at ever increasing spatial resolution, through the application of traditional anatomical imaging methods such as computed x-ray tomography (CT) and magnetic resonance imaging) MRI). Although these methods still represent the mainstay of clinical imaging, it has become clear that the acquisition of molecular and physiological information by nuclear magnetic resonance and optical imaging technologies could vastly enhance our ability to fight cancer.
Emerging genomic and proteomic technologies have the potential to transform the way in which cancer is clinically managed. Molecular imaging is poised to play a central role in this transformation, because it will allow the integration of molecular and physiological information specific to each patient with anatomical information obtained by conventional imaging methods.
Combined PET/CT represents a very unique imaging modality that scans the whole body in the same session, providing functional and anatomic information in co-registered images. It combines the high sensitivity of PET to the superior anatomical localization by CT resulting in much more accurate detection and staging of malignancies. It also provides a better quality PET images due to better attenuation correction by CT scan in a relatively short time.
Accordingly 18F- FDG PET/CT has acquired a firm place in the evaluation of malignancies. It is rapidly becoming the key investigative tool for the loco-regional staging and detection of distant metastases. It has a quite greater role in assessment of recurrence and differentiating it from post therapeutic tissue changes. It has also gained widespread acceptance as a key tool used to demonstrate early response to therapy before other markers of response. PET/CT impacts the patient’s prognosis by altering the management strategy according to the obtained findings during the initial staging or the follow up (during the course of treatment or later follow up).
Diffusion-weighted MR imaging is increasingly used for the evaluation of extra-cranial diseases. There is growing interest in the application of DWI for the evaluation of the patient with cancer, providing complementary information to anatomical and metabolical imaging modalities.
DW MR imaging plays a significant role in the assessment of patients with head and neck cancer, as it can differentiate malignant tumors from benign tumors, characterize cervical lymphadenopathy, aid in the grading of malignant tumors, and guide surgeons in the selection of a biopsy site. Additionally, it plays roles in monitoring cancer patients after chemo radiotherapy and in the diagnosis of inflammatory lesions and grading of autoimmune diseases of the head and neck. Continuous progress as a result of wide spread research should lead to improved diagnostic accuracy and clinical applications of diffusion-weighted MR imaging of the head and neck.
Both CT perfusion and MR perfusion permit a depiction of the contrast kinetics within tumors. A CT scan has higher spatial resolutions and is performed more frequently in patients with head and neck malignancies. CT perfusion shows promise in distinguishing benign and malignant process, and in predicting response to chemo radiation therapy. However, MRI does not cause radiation exposure and has advantage over CT in the soft tissue contrast for anatomic delineation of the tumors.
Optical molecular imaging introduces a revolutionary new approach to address the basic challenge in surgical oncology, to discriminate between tumor and normal tissue and consequently determine an adequate tumor-free margin during surgery. This is a critical aspect of oncologic surgery because, apart from tumor characteristics (i.e., stage, differentiation, grade) and complete surgical removal is pivotal for the prognosis of the patient.