Glioblastoma multiforme tanılı olgularda radyoterapi sonrasında tümör rekürrensi ve radyonekroz ayırımında perfüzyon MRG ve MR spektroskopinin rolü
The role of perfusion MRİ and MR spectroscopy in differentiation of tumor recurrence and radionecrosis of the patients diagnosis with glioblastoma multiforme after radyoterapi
Yazar: IRADA MUSAYEVA
Danışman: PROF. DR. MEHMET CEM ÇALLI
Ege Üniversitesi / Tıp Fakültesi / Radyoloji Ana Bilim Dalı
Derece: Tıpta Uzmanlık, 2012
Konu: Radyoloji ve Nükleer Tıp = Radiology and Nuclear Medicine
Dizin: Glioblastoma = Glioblastoma ; Manyetik rezonans görüntüleme = Magnetic resonance imaging ; Manyetik rezonans spektroskopi = Magnetic resonance spectroscopy ; Neoplazmlar = Neoplasms ; Nüks = Recurrence ; Radyoterapi = Radiotherapy

Özet:
Purpose: GBM is the most frequent primary malignant brain tumor in adults. Optimal treatment modality is postoperative radiotherapy alone or in combination with concomitant adjuvant chemotherapy after as widest as possible surgical resection. The difficulty in evaluation after RT is distinguishing residual or recurrent tumor from radionecrosis. Radionecrosis is very similar to the clinical features and natural history of recurrent tumor. Therefore, differentiation of these two entites is very important and is often difficult. Contrast-enhanced MRI is the preferred method in these patients after follow-up radiotherapy. However, this method is insufficient. The aim of this study was to determine the additional value of perfusion MRI and MR spectroscopy to contrast enhanced MRI in the differentiation of tumor recurrence and radionecrosis after radiotherapy in patients with GBM.Materials and Methods: Contrast enhanced MR, perfusion MR and MR spectroscopy imaging findings of 40 patients (24 male, 16 female) who were diagnosed as GBM and treated with surgery and radiotherapy were examined rectospectively between January 2009 and July 2012. Radionecrosis group, 14 (35%), recurrence group, 26 (65%) patients were assessed. All patients were investigated at 1.5 and 3 Tesla MR system including conventional MR, diffusion-weighted, perfusion-weighted MRI and MR spectroscopy imaging. rCBV, rCBF values of perfusion MR examination and Cho, Cr, NAA values, Cho / Cr, Cho / NAA ratios of MR spectroscopy examination were evaluated.Results: 6 of 14 cases of radionecrosis (43%) were histopatologically diagnosed. Mean time of diagnosis of radionecrosis and recurrent tumor group was 9.00 ± 6:53 months and 8.04 ± 3.93 months, respectively. Mean rCBV value was calculated 3.79 ± 2.41 in radionecrosis group and 5.46 ± 2.19 in recurrence group . Mean rCBF value was 3.21 ± 1.99 in radionecrosis group and 5.17 ± 2.41 in recurrent group. In radionecrosis group, rCBV and rCBF values were statistically significantly lower than those of recurrence group. (p = 0.032, p = 0.013). Cho / Cr ratios were 2.55 ± 1.63 in radionecrosis group and 2.52 ± 1.60 in recurrence group; Cho / NAA ratios were 4.15 ± 3.69 in radionecrosis group and 3.24 ± 2.55 in recurrent group is measured. Results of MR spectroscopy were not statistically significant different between two analysed groups.Conclusion: As a result, in our opinion, for differentiation of tumor recurrence and radionecrosis after radiotherapy in patients with GBM, perfusion MR and MR spectroscopy imaging should be performed in addition to conventional MR imaging on follow-up examinations.Key Words: glioblastoma multiforme, perfusion weighted imaging, MR spectroscopy, radionecrosis, recurrence.

Abstract:
Purpose: GBM is the most frequent primary malignant brain tumor in adults. Optimal treatment modality is postoperative radiotherapy alone or in combination with concomitant adjuvant chemotherapy after as widest as possible surgical resection. The difficulty in evaluation after RT is distinguishing residual or recurrent tumor from radionecrosis. Radionecrosis is very similar to the clinical features and natural history of recurrent tumor. Therefore, differentiation of these two entites is very important and is often difficult. Contrast-enhanced MRI is the preferred method in these patients after follow-up radiotherapy. However, this method is insufficient. The aim of this study was to determine the additional value of perfusion MRI and MR spectroscopy to contrast enhanced MRI in the differentiation of tumor recurrence and radionecrosis after radiotherapy in patients with GBM.Materials and Methods: Contrast enhanced MR, perfusion MR and MR spectroscopy imaging findings of 40 patients (24 male, 16 female) who were diagnosed as GBM and treated with surgery and radiotherapy were examined rectospectively between January 2009 and July 2012. Radionecrosis group, 14 (35%), recurrence group, 26 (65%) patients were assessed. All patients were investigated at 1.5 and 3 Tesla MR system including conventional MR, diffusion-weighted, perfusion-weighted MRI and MR spectroscopy imaging. rCBV, rCBF values of perfusion MR examination and Cho, Cr, NAA values, Cho / Cr, Cho / NAA ratios of MR spectroscopy examination were evaluated.Results: 6 of 14 cases of radionecrosis (43%) were histopatologically diagnosed. Mean time of diagnosis of radionecrosis and recurrent tumor group was 9.00 ± 6:53 months and 8.04 ± 3.93 months, respectively. Mean rCBV value was calculated 3.79 ± 2.41 in radionecrosis group and 5.46 ± 2.19 in recurrence group . Mean rCBF value was 3.21 ± 1.99 in radionecrosis group and 5.17 ± 2.41 in recurrent group. In radionecrosis group, rCBV and rCBF values were statistically significantly lower than those of recurrence group. (p = 0.032, p = 0.013). Cho / Cr ratios were 2.55 ± 1.63 in radionecrosis group and 2.52 ± 1.60 in recurrence group; Cho / NAA ratios were 4.15 ± 3.69 in radionecrosis group and 3.24 ± 2.55 in recurrent group is measured. Results of MR spectroscopy were not statistically significant different between two analysed groups.onclusion: As a result, in our opinion, for differentiation of tumor recurrence and radionecrosis after radiotherapy in patients with GBM, perfusion MR and MR spectroscopy imaging should be performed in addition to conventional MR imaging on follow-up examinations.Key Words: glioblastoma multiforme, perfusion weighted imaging, MR spectroscopy, radionecrosis, recurrence.