Keywords:
Musculoskeletal soft tissue, Oncology, MR, MR-Diffusion/Perfusion, Diagnostic procedure, Tissue characterisation, Cancer
Authors:
E. Aktas, M. Arikan, F. ARDIC, B. S. Sahin, J. karakaya, G. Togral, B. K. Arıbaş; Ankara/TR
DOI:
10.1594/essr2018/P-0005
Purpose
Soft tissue sarcomas account for less than 1% of all adult malignities (1,2).
Despite combined and aggressive treatment methods including radiotherapy,
chemotherapy and surgical treatment local relapse rates of soft tissue sarcomas are between 535% (25).
Most relapses develop within the first two years after surgery (3).
For this reason,
postoperative follow up must be done every 36 months with imaging.
The lesion size,
location,
histological grade,
the efficiency of surgical resection and response to adjuvant treatments are important risk factors for the development of local recurrence (2).
Benign changes like hematomas,
seromas,
fibrosis and granulation tissue that develop in the operation lodge after surgical treatment and radiotherapy may be confused with local recurrence on MRI scans.
In cases where a definite differentiation is not possible,
the clinical approach is MRI follow up or evaluation with positron emission tomography (6).
Diffusion MRI is lately being routinely used in radiology clinics for the identification of fibrosis and tumors and is a noninvasive method that generates contrasted images of water’s molecular movement.
The diffusion sensitivity may vary at different b values of diffusion.
Images with low b values are less diffusion weighted and use lower gradients.
The diffusion sensitivity is also effected by perfusion at low b values.
Higher b value images are stronger diffusion weighted and have low signaltonoise ratios.
For a meaningful evaluation of diffusion MRI’s,
MRIs must be obtained with at least 2 separate b values.
Mistakes in ADC calculations can be prevented by obtaining more than one b value (7,8).
There is no common consensus about the b value and the number of different b values required to be used in the MRI evaluations of the muscularskeletal system.
In our study,
we aimed to show the efficacy of diffusion weighted images at different b levels and ADC values in the differentiation of recurrent and residual tumors.