The role of STIR MRI sequence in the evaluation of the breast following conservative surgery and radiotherapy

The purpose of the study was to define the value of fat suppressed STIR seq uence in the MRI of the conserved breast. To our knowledge, this study is t he first clinical evaluation of STIR sequence in post-therapy conditions. Forty patients with early (T1-2, N0-1) invasive breast cancer underwent con servative surgery and postoperative radiotherapy. Routine follow-up examina tions, including physical examination and mammography were supplemented wit h breast MRI in all cases 6-166 months (mean 27.6) after initial treatments . Three patients had bilateral cancer. Including follow-up (9 patients) MRI examinations, altogether 53 MRIs were available for analysis. An 0.5 T MRI (Elscint, Haifa, Israel) was used with double breast coil. Axi al T1 and T2 weighted spin echo, STIR and 3D gradient echo dynamic sequence s were performed. Pre- and postcontrast slices underwent serial subtraction . Twenty-eight circumscribed lesions were identified. All were well visualise d on STIR sequence, regardless of histologic nature of lesions. One low gra de DCIS was not detected by any sequence. Differential diagnosis between benign and malignant lesions was not possibl e by STIR sequence alone. STIR sequence was found to be more sensitive in the detection of treatment related breast edema and fluid collection, than T2 SE (spin-echo) sequence. Even the patients who were not good candidates for subtracted contrast enha nced dynamic studies - because of motion artefacts - could have been examin ed with satisfactory results. STIR is a very sensitive sequence for depicting circumscribed lesions and p ost-therapy complications, but not suitable for differentiation. It is a us eful tool in the follow-up of patients with conserved breast subjected to r adiotherapy.