الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Direct laryngoscopy, allows direct visualization of mucosa and can be used for biopsy. However, it is invasive, requires general anesthesia and depends on the surgeon’s experience ;in addition viewing is limited to the lumen with restriction of transmural evaluation, as well as, the larynx has a complex anatomy and multiple regions as subglottic area, ventricle and commissures which may not be easily and fully evaluated by direct laryngoscopy.
CT may reveal the extent of infiltration of laryngeal carcinoma, but it also has certain limitations, including over estimation of invasion of the vocal cords, underestimation of invasion of the upper esophagus, difficulty in displaying mild invasion of thyroid cartilage, and uncertainty with regard to the normal size of the cervical lymph nodes and whether they are subject to metastasis. Routine MRI has high resolution in soft tissue, enabling it to accurately determine the infiltration extent of tumors; however, it remains a challenge to diagnose small lesions or micro metastatic nodes.
Recently, diffusion-weighted magnetic resonance imaging (DWI) has emerged as a relatively novel functional imaging tool that records the molecular motion of protons corresponding to Brownian motion within living tissue. The extent of molecular diffusion may be estimated and quantified in terms of the apparent diffusion coefficient (ADC). DWI is widely used in clinical practice to differentiate benign masses from malignant tumors, to diagnose lymph node metastasis, to detect recurrent lesions following radiotherapy/chemotherapy, and to predict the effect of treatment using DWI and ADC values. DWI is able to detect changes in tumor size and shape prior to them becoming visible to the naked eye, and the ADC value is affected by cell size, density and integrity. However, the complex anatomical structure and functions occurring in the head and neck, including respiration, swallowing and phonation, limit the use of DWI in these regions. Nonetheless, with the advances in MRI technical performance and MRI machinery, the application of DWI to head and neck oncology is increasing.
Diffusion-weighted MRI (DWI) was introduced in head and neck cancers for differential diagnosis, monitoring of the treatment response the differentiation of recurrence, and post-therapeutic changes after radiotherapy, DWI uses the movement of water molecules to produce images that indirectly reflect information regarding cell density and microstructures in living tissues .These changes can be estimated and quantified in terms of the apparent diffusion coefficient (ADC) , DWI can detect changes in tumor size and shape before they are visible to the naked eye .
Aim of the study
a- Our ultimate goal is to detect sensitivity and specificity of DWI as non-invasive technique in detection of
1- De novo cases of cancer larynx
2- Follow up of cancer larynx (irradiated, chemotherapy, Concomitant chemo radiotherapy).
b- Whether ADC has diagnostic value in discriminating carcinomas from benign lesions, or discriminating metastatic lymph nodes from reactive cervical lymph nodes;
This prospective randomized comparative clinical trial is to evaluate the role of DW-MRI in diagnosis of laryngeal carcinoma in comparison direct endoscopy and biopsy.
In our study 22 patients have different types of laryngeal carcinoma undergone diagnosis by DW-MRI and direct laryngoscopy under general anesthesia. Patients included in the study were patients suspected of denovo cancer larynx and patients suspected of tumor recurrence, after radiotherapy and chemotherapy, Patients excluded in the study who had contraindication to magnetic resonance imaging (e.g., pacemaker, metallic implant, cochlear implant or claustrophobia). According to sites 12 cases were glottic (54.54%) , three cases were supraglottic (13.63%) ,five cases were transglottic (22.72%) and Hoarseness of voice was the main presenting symptom of all laryngeal lesions 17 cases (77.27%) followed by recurrent attacks of stridor three cases ( 13.6%) , discomfort sensation and dysphagia 3 cases (13.6%) , chronic irritative cough 2 cases (9.4%) , the mean total ADC (0.73±sd0.23), as regarding deep tumor extension by MRI: - paraglottic space invasion found in nine patients (40.9 %), preepiglottic space invasion was found in five patients (22.7 %), cartilage invasion was found in seven patients (31.8 %) lesion, histopathological examination of biopsies obtained from the laryngeal mucosal lesion showed them to be squamous cell carcinoma of different grading (most common type is well differentiated type seven patients, In conventional MRI (T2 weighted image) were found that hyper intense lesion 17 patients (77.3%) , as regarding diffusion MRI (qualitative method) ) was found that restricted diffusion in 16 patients (72.7%) and facilitated diffusion in six patients (27.3%) ,also The mean ADC was found to be (0.73±sd 0.23) , This study showed that neither site of tumor nor invasion of parglottic space nor preepiglottic or cartilage affect ADC and diffusion. Sensitivity and specificity and accuracy were calculated in comparison between ADC value and histopathology it was found that cut off point in total number of cases the ADC using receiver operating characteristics >.87 10-.3 mm2/s ,with highly significant p value >0.0001. with sensitivity 88.89% and specificity 100% and accuracy 94.45%. in group A result that cut off value of the ADC using receiver operating characteristics >.87 x 10-.3 mm2/s insignificant p value (0.869), with sensitivity 100% and specificity 50% and accuracy 75%, in group B the cut off value of the ADC using receiver operating characteristics < 0.64x 10-.3 mm2/s with insignificant p value (0.677) with sensitivity 90% and specificity 66.67% and accuracy 78.34%.
Diffusion weighted MRI (DW-MRI), is an easily reproducible and noninvasive technique that can accurately explore the larynx and became a very important diagnostic tool of laryngeal diseases. DW-MRI is considered as a safe imaging modality for the diagnosis DW-MRI a trustable diagnostic tool to discriminate benign lesion from malignant one and in detecting subsites and accurate site of taking biopsy DW-MRI using ADC value is highly reliable method in searching malignancy in previously treated cases of laryngeal cancer if ADC >.87DW-MRI is alternate technique that can be used in patients with suspected tumor recurrence after radiotherapy , chemotherapy to discriminate radio necrosis from residual or recurrent lesion(The ADC threshold in treated cases (group A) is >0.87x10-3mm/s) Delineate denovo cases of laryngeal cancer (The ADC threshold in denovo cases (group b) is <0.64x10-3mm/s). The ADC values of well differentiated carcinoma are higher than those of poorly differentiated carcinoma as the increases in the cellularity and cellular turnover which are frequently observed in malignant tumors standard endoscopy and biopsy and DW-MRI. DWI of the head and neck has commonly been done with a 1.5-T scanner. Further study need to be conducted at 3.0T MRI machines. Comparison between PET scan and DW-MRI are needed to be done in whole body scan to detect metastasis due to advantage of MRI. Direct comparison between histologic sections and the correspondingDWI maps of tumors was not achievable because in mostcases, the specimens were obtained at biopsy and the planesof MR images and those of histologic sections in each tumor
were not identical. Another important feature of DWI is that ADC values may aid in detecting metastatic lymph nodes in patients with head and neck squamous cell carcinoma (HNSCC) so more study of relation between ADC and metastatic lymph nodes. More study about ADC With the prognosis of patients (cure rate and survival rate) with laryngeal carcinoma. With comparison between fiberoptic evaluation and stroboscope in phoniatric unit in with laryngeal lesions. Does certain cancer cells with low ADC values were critically damaged following radiotherapy