الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Lymphatic metastasis is the most important mechanism in the spread of head and neck squamous cell carcinomas. The rate of metastasis probably reflects the aggressiveness of the primary tumor and is an important prognosticator not only the presence, but also the number, of nodal metastasis, the level in the neck, the size of the nodes, and the presence of extra nodal spread are important prognostic features.
Conventional imaging depends upon the morphologic criteria of the lymph node. Ultrasound (US), computed tomography (CT) and magnetic resonance (MR) can be used in the detection of enlarged cervical nodes; however, they cannot accurately differentiate benign from malignant lymph nodes. Metabolic imaging using single photon emission CT (SPECT) and positron emission tomography (PET) can help in this differentiation but they are limited by low spatial resolution and variable physiological flurodeoxyglucose (FDG) uptake in anatomical structures and inflammatory lymph nodes. Ultrasound guided fine needle aspiration cytology (FNAC) is invasive with false negative results due to operator-dependency.
Diffusion-weighted MRI (DWI) is a non-invasive functional technique which allows the characterization of tissues and lesions by difference in microstructure based on the analysis of water motion as architectural changes in the water molecule movement will alter the apparent diffusion coefficient and the signal intensity in DWI and apparent diffusion coefficient (ADC) map.
The present work aims at evaluation of the diagnostic value of DWI in assessment of N0 neck in patients with head and neck malignancies, through correlation with intra operative findings and postoperative histopathologic nodal examination
The current work included twenty patients with primary upper aero digestive tract squamous cell carcinoma and clinically negative neck.
All patients were subjected to complete head and neck examination; palpation of the neck for assessment of neck lymph nodes level, CT neck.
The radiographic criteria used to determine whether lymph nodes are suspicious for metastatic disease are the size of the individual lymph nodes, their shape, the presence of central necrosis, internal speculation or extra capsular spread, and the number of nodes. (33)
Lymph node was staged according to TNM system of the UICC. All patients were subjected to MRI studies using a 1.5 T superconducting closed magnet MRI unit (Avanto, Siemens, Erlangen, Germany).