الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Musculoskeletal masses represent high burden on patients as they are usually associated with pain and limitation of movement so treatment of these cases are mandatory for better life. Differentiation between benign and malignant tumors and tumor – like lesions remain the cornerstone in the management, also any information about the extension, the behavior and the components of the lesion can also share in better quality of the treatment. Conventional MRI remain the best imaging modality for assessment of soft tissue lesions due to its higher resolution and tissue contrast compared to other imaging modalities, also due to its high sensitivity in detection of bone marrow lesions. Functional MRI also helps in better diagnosis of musculoskeletal masses due to the extra information obtained from these sequences about the microstructure and the tumor vascularity that share in differentiation between benign and malignant lesions, these sequences include: Diffusion Weighted Imaging and ADC maps, susceptibility weighted, opposed phase MRI and dynamic contrast study. The aim of this study was to assess the value of multi-parametric MR imaging techniques in evaluation of musculoskeletal masses in the lower extremity and differentiation between benign and malignant lesions. This prospective study was conducted on 70 patients with musculoskeletal complaint referred from orthopedic and general surgery departments with clinical and X-ray suggestion of musculoskeletal masses during the period from October 2019 to October 2021. The study was approved by the Research Ethical Committee, Faculty of Medicine, Tanta University. All patients were subjected to clinical evaluation including full history taking and thorough clinical evaluation as well as radiological assessment by regional Plain X-ray, conventional and functional MRI studies. In the present study, the patients age ranged from 10 to 65 years with mean age 33.47 ± 17.53 years and these cases were subdivided into two groups; 34 patients with bony lesions and 36 patients with soft tissue lesions; furthermore these groups were divided into smaller subgroups including benign, tumor – like and malignant lesions. In this study, DWI helped in differentiation between benign and malignant lesions through detection of the lesion‟s microstructure and tissue cellularity qualitatively through diffusion restriction at DWI and quantitatively through ADC values. In the current study, regarding bony lesions; ADC values of benign lesions ranged from (0.80 – 2.15 x 10-3 mm2 /sec) with mean ADC value measured 1.5 ± 0.43, while ADC values of malignant lesions ranged from (0.59 – 1.05 x 10-3 mm2 /sec) with mean ADC value measured 0.79 ± 0.17, with cut off value of ADC for bony lesions was ≤ 1 to be considered malignant with sensitivity, specificity and accuracy measured 83.3 %, 86.4 % and 85.3 % respectively. Regarding soft tissue lesions; ADC values of benign lesions ranged from (0.80 – 2.5 x 10-3 mm2 /sec) with mean ADC value measured 1.67± 0.54, while ADC values of malignant lesions ranged from (0.65 – 0.9 x 10-3 mm2 /sec) with mean ADC value measured 0.77 ± 0.068, with cut off value of ADC for soft tissue lesions was ≤ 0.87 to be considered malignant with sensitivity, specificity and accuracy measured 91.7 %, 87.5 % and 88.9 % respectively. Susceptibility weighted MRI sequence through the susceptibility artifact could give hint about the presence of blood or calcification inside the lesions with the help of filter phase images. The blood appeared as high signal while calcification appeared as signal voids in the automatically processed filter phase. In this study, opposed phase MRI sequences gave an excellent idea about the bone marrow and helped in differentiation between benign and malignant bone marrow lesions qualitatively through DROP of signal at out of phase sequence and quantitatively through SIR value. Regarding SIR; SIR of benign lesions ranged from 0.2 – 1.1 with mean value measured 0.72 ± 0.28, while SIR of malignant lesions ranged from 0.8 – 1.8 with mean value measured 1.2 ± 0.30, with cut off value of SIR ≥ 0.89 to be considered malignant with sensitivity, specificity and accuracy measured 91.7 %, 90.9 % and 91.17 % respectively. In the current study, DCE-MRI gave an idea about the tissue vascularity of the lesion. Benign bony and soft tissue lesions showed mainly type I and II curves while type IV curve appeared mostly at malignant bony and soft tissue lesions; so DCE –MRI helped in differentiation between benign and malignant lesions with sensitivity, specificity and accuracy measured 90.9 %, 91.3 % and 91.17 % respectively at bony lesion and about 91.7 %, 91.7 % and 91.7% at soft tissue lesions. Combined multiparametric MRI techniques showed excellent results with higher sensitivity , specificity and accuracy than their individual accuracy in differentiation between benign and malignant bone and soft tissue lesions.