Contrast enhanced MRI, diffusion weighted MRI and histopathological findings of head and neck lesions

Determination of benign or malignant nature of head and neck lesions and their appropriate therapy is important in the preoperative period. MRI is beyond the other radiological modalities in case of characterization of soft tissue lesions. However, conventional MRI examinations might be inefficient in the preoperative diagnosis of head and neck lesions. Our aim is to evaluate the contrast enhanced MRI, diffusion weighted MRI and histopathological findings of head and neck lesions of patients referred to our department.Forty two patients referred to Abant Izzet Baysal University, School of Medicine, Department of Radiology between July 2008 and June 2011 with a prediagnosis of head-neck lesion, underwent contrast enhanced MRI and diffusion weighted MRI, and diagnosed as benign or malignant mass after incisional biopsy or operation, were included in this study. Patients, whose MRI examinations were not evaluated properly due to artefacts, were excluded. After determination of radiological criteria ( signal intensity, enhancement pattern, ADC value etc.) contrast enhanced MRI and diffusion weighted MRI were evaluated by a radiologist who had a ten years of experience. Histopathological evaluation was made by a pathologist who had no knowledge about the patient and the ADC value. Descriptive statistics, chi square and Mann Whitney U tests were used for statistical analyses and a p<0 .05 was considered to indicate statistical significance.Two MRI examinations were excluded from the study due to artefacts. Fortytwo masses were detected in 42 patients. Of the 42 masses 25 were benign and 17 were malignant. MRI criteria such as signal intensity, internal structure, presence of cystic space and enhancement were found to be insignificant in the differentiation of benign and malignant lesions. The mean ADC value of benign and malignant lesions were 0,128x10-3±0,053 mm² /sn and 0,100x10-3±0,026, mm²/sn respectively.ADC value was significantly higher in benign lesions compared to malignant ones (p=0.032).In histopathological evaluation, nucleus/cytoplasm ratio was between 0,25-2 in squamous cell carcinoma, 0,5-0,6 in plasmocytoma, 2-5 in malignant melanoma infiltration, 1,5-2,3 in infiltration of indifferentiated malignant tumor, 3-4 in diffuse large cell B lymphoma and was 0,25 in schwannoma, 0,01 in lipoma, 2 in malignant epithelial tumor, and 2 in basosquamous carcinoma. Tumor/stroma ratio was between 1,5-4 in squamous cell carcinoma. Stroma was very dense in Warthin tumor. Only 20 lesions were evaluated for necrosis. Fourteen lesions did not have necrosis while minimal, moderate and apparent necrosis were present in 3, 1, and 2 lesions respectively. Matrix/ epithelium ratio was between 0,5- 4.In conclusion, conventional MRI sequences are important in the diagnosis of head and neck lesions but not sufficient due to the overlapping findings. Diffusion weighted MRI, that is applied in addition to conventional MRI examinations, an efficient technique and has additional diagnostic value. The mean ADC value which can be measured in diffusion weighted MRI is significantly higher in benign lesions compared to malignant ones.