Conference Paper

Quantitative T2* Perfusion Evaluation in the Differential Diagnosis between Recurrence and Pseudo-progression in Patients Affected by Glioblastoma Multiforme Treated with Radiotherapy and Temozolamide

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Abstract

PURPOSE The usually scheduled treatment in patient affected by glioblastoma multiforme (GBM) is surgery followed by radiotherapy (RT) associated with temozolamide (TMZ) chemotherapy. Possible findings during early (within 4 months) follow-up MRI are new enhancing lesions either due to recurrence or to early radiation necrosis (the so called pseudo-progression, PP). To distinguish these two entities can impact further treatment. The purpose of our study was to evaluate T2*-weighted dynamic susceptibility-weighted contrast–enhanced (DSC) imaging and the derived rCBV and Ktrans, in the differential diagnosis between recurrent GBM from PP. METHOD AND MATERIALS A retrospective study was performed in 115 patients, affected by GBM, enrolled after surgery and RT associated to TMZ chemotherapy. They all underwent DSC-MRI follow-up. In 24 of them, early follow-up MRI (4 months) revealed a new nodular area of contrast enhancement within the radiation field. The diagnosis of recurrence vs PP was established with clinical-radiological follow-up or surgical resection. ROIs were drawn semiautomatically on the enhancing component of the lesion, avoiding cortical vessels. The same ROIs were copied on the CBV and Ktrans color maps (Perfscape - Olea software, France) and the values obtained were normalized to the contralateral normal appearing white matter. T test was used to compare the groups. RESULTS Mean rCBV (2,7 vs 1,7 P<0,05), maximum rCBV (4 vs 2,6 P<0,05) and minimum rCBV (1,2 vs 0,7 P<0,06) were higher in patients with a GBM recurrence than in patients with PP. Mean Ktrans (68,7 vs 112,7 P<0,05) maximum Ktrans (287 vs 312,8 P<0,5) minimum Ktrans (1 vs 14,5 P<0,05) were lower in patients with a GBM recurrence than in patients with PP. We propose a mean rCBV cut-off ≥ 2,3 (sensibility: 64%; specificity: 75%; positive predictive value: 70%; negative predictive value: 70%). CONCLUSION DSC perfusion MRI can differentiate PP from tumor recurrence in patients with GBM treated with RT associated with TMZ chemotherapy. These results reflect the different vascular density and permeability of the GBM recurrence compared to PP. CLINICAL RELEVANCE/APPLICATION The informations given by DSC perfusion MRI help the radiologist in the differential diagnosis and they are of paramount importance for the subsequent therapy of these patients.

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