الفهرس 
Introduction and aim of the work
Aim of the workOnly 14 pages are availabe for public view
 |  | from | 142 |  |  |
| | | from | 142 | | |
Abstract
Influenced by the constantly evolving approach to non-invasive patient management in the era of functional imaging, investigators demonstrated the diagnostic potential of functional MR images to differentiate between benign and malignant tumors including those of the mediastinum. Hence, serving as a virtual biopsy and in some cases preventing unnecessary diagnostic intervention. Conducted studies showed that the ADC value of malignant mediastinal lesions is significantly lower than that of benign lesions and determined cut off ADC values to differentiate the two; concluding that ADC value is a promising noninvasive, imaging parameter that helps assess, characterize mediastinal tumors and grading of mediastinal malignancy .
Taking this a step forward, the primary objective of our prospective study was to investigate the potential of functional MRI to characterize mediastinal lesions and differentiate benign from malignant lesions. The MR imaging findings of a total of fourty eight pathologically proven mediastinal lesions were evaluated. Patients’ demographics, mediastinal compartment in question as well as conventional MR findings were all taken into consideration.
Lesions were classified according to histopathological diagnosis into thymic lesions (4.2%), lymphadenopathy (50%) [lymphoma (45.9%), chronic reactive lymphadenopathy (4.2%)], neurogenic tumors (8.3%), germ cell tumors (4.2%), osteochondroma (4.2%), cancer thyroid (4.2%),non small cell carcinoma suggesting adenocarcinoma of the bronchus (4.2%) ,mets forming mediastinal masses (8.3%), abscess(4.2%) and retrosternal goiter (8.3%).
Mediastinal masses are usually symptomatic at presentation. Majority of the masses were malignant lesions and the symptoms of mediastinal obstruction was significantly higher in malignant lesions and anterior mediastinal masses. Lymphoma was the most frequent primary mediastinal mass
On qualitatively assessing the DW-MR images, malignant lesions predominantly showed restricted diffusion, while benign lesions were of facilitated diffusion pattern.
As for their quantitative assessment, malignant lesions displayed lower ADCmean values than benign lesions in the same category. In addition, we were able to set number of ADCmean cut off values between certain mediastinal pathological categories as following:
• Mean apparent diffusion coefficients (ADC) among enrolled patients was 1.18 ± 0.34 (10-3 mm2/second). Facilitated DWI was present in 16 (33.3%) patients while 32 (66.7%) patients had restricted diffusion.
• At cut off point < 1.27 (10-3 mm2/second), ADC has 94% sensitivity and 88% specificity with overall accuracy was 92% with area under curve was 0.92.
Recommendations
Further studies focused on specific types of tumors are recommended and Furthermore, using another functional imaging modality as 8F-FDG-PET/CT as a comparative group.