Bülent MIZRAK, Çağatay ÖNAL, Özlem AYDAGÜN, Kaya SARAÇ, Alpay ALKAN, Abdurrahim DUSAK

Primer beyin tümörleri: Proton manyetik rezonans spektroskopik analiz ve histopatolojik korelasyon

Amaç: Primer beyin tümörlerinin tedavisindeki son gelişmeler, tümörün tanısı yanı sıra, tedavi etkinliğinin de değerlenmesi açısından, radyolojik görüntüleme yöntemlerine olan ilgiyi arttırmıştır. Konvansiyonel Manyetik Rezonans (MR) görünteleme primer beyin tümörlerinin tanı ve takibinde yaygın olarak kullanılmakla birlikte malignitelerinin derecelendirilmesinde yetersiz kalmaktadır. MR spektroskopi ile beyin lezyonlarında invivo biyokimyasal değerlendirme yapılabilmektedir. Çalışmamızda MR spektroskopinin primer beyin tümörlerinin ayırıcı tanısı ve malignitelerinin derecelendirilmesindeki yeri araştırıldı.Yöntemler: Histopatolojik olarak primer beyin tümörü tanısı alan 23 olgu ile 31 sağlıklı gönüllüden oluşan kontrol grubu incelendi. Tüm olgularda rutin konvansiyonel MR görüntüleme ile birlikte point resolved spectroscopy (PRESS) sekansı, single voksel MR spektroskopi (TE: 31 ve 136 msn) elde edildi. MR spektroskopide kantitatif olarak metabolitler [N-asetil aspartat (NAA), kolin (Cho), myoinositol (mI), lipid, laktat ve alanin] ile bunların kreatin (Cr)'e oranları ölçüldü.Bulgular: Nöroglial primer beyin tümörlerinde NAA/Cr ve mI/Cr oranları azalmış, Cho/Cr, lipid/Cr ve laktat/Cr oranları artmış olarak saptandı. Menenjiomlardan oluşan ekstraaksiyel primer beyin tümörlerinde NAA saptanmadı, Cho/Cr oranı belirgin olarak artmış, mI/Cr, lipid/Cr ve laktat/Cr hafif artmış olarak saptandı. Alanin piki sadece menenjiomlarda saptandı. Yüksek grade'li nöroglial tümörlerde düşük grade'lilere göre NAA/Cr ve mI/Cr'de azalma, Cho/Cr, lipid/Cr ve laktat/Cr'de belirgin artma gözlendi.Sonuç: MR spektroskopi primer beyin tümörlerinin intraaksiyel ve ekstraaksiyel olarak sınıflandırılmasında, nöroglial primer beyin tümörlerinin ise; yüksek ve düşük grade'li olarak ayırımında konvansiyonel MR görüntüleme yöntemlerine, ek tanısal veriler sağlar. Primer beyin tümörlerinin ayırıcı tanısında ve malignite derecelerinin belirlenmesinde rutin konvansiyonel MR görüntüleme yöntemleri ile birlikte kullanılmasının yararlı olacağı kanısına varıldı.

Primary brain tumors: Proton magnetic resonance spectroscopic analysis and histopathological correlation

Objective: Recent advances in treatment of primary brain tumors have increased the interest in radiological imaging in respect to both the diagnosis of tumor and the evaluation of the efficiency of therapy. Conventional Magnetic Resonance (MR) imaging is commonly used for diagnosis and follows up of the primary brain tumors, but it fails in grading of the tumors. MR spectroscopy permits in-vivo biochemical evaluation of brain lesions.Methods: Twenty three patients with histopathologic diagnosis of primary brain tumor and control group consisting of 23 healthy volunteers were investigated. In addition to conventional MR imaging of all patients were underwent point resolved spectroscopy (PRESS) sequence via single voxel MR spectroscopy. Using MR spectroscopy, metabolites [N-acetyl aspartate (NAA), choline (Cho), myo-inositol (mI), lipid, lactate and alanine] and their ratio to creatine (Cr) were measured quantitatively.Results: MR spectroscopic imaging of neuroglial primary brain tumors revealed that the NAA/Cr and mI/Cr ratios were decreased. In extra axial primary brain tumors, which consist of meningioma, NAA wasn't detected, Cho/Cr ratio was remarkably increased, mI/Cr, lipid/Cr and lactate/Cr ratios were mildly increased. Alanine peak was detected only in meningioma. In high grade neuroglial tumors in proportion to low grade ones NAA/Cr and mI/Cr ratios were decreased, Cho/Cr, lipid/Cr and lactate/Cr ratios were remarkably increased.Conclusion: MR spectroscopy provides extra information in classification of primary brain tumors as intra-axial and extraaxial, and in grading of neuroglial primary brain tumors as high grade or low grade. It was concluded that using conventional MR imaging in cooperation with MR spectroscopy is beneficial in differential diagnosis and in grading of primary brain tumors.

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