BÜNYAMİN GÜNEY, ÖMER KİTİŞ, Cem ÇALLI, Nilgün YÜNTEN

İntrakranial kistik lezyonlarda difüzyon-ağırlıklı MR görüntüleme

Bu çalışmanın amacı kistik yada nekrotik intrakranial lezyonların difüzyon ağırlıklı görüntülemede (DAG) sinyal intensitelerini değerlendirmek ve bu lezyonların apparent diffusion coefficient (ADC) değerlerini ölçerek ayırıcı tanıya katkısını araştırmaktı. Kistik yada nekrotik intrakranial lezyonu bulunan 24 olgu (7 baktehal abse, 6 epidermoid kist, 4 araknoid kist, 5 glioblastom, 2 kist hidatik) çalışmaya dahil edildi. Bu olgulara rutin MR görüntülerin yanısıra eko-planar difüzyon ağırlıklı görüntüme yapıldı. DAG için, aksiyel planda multipl kesitli, single shot, eko-planar spin-eko sekans b=1000sn/mma kullanılmıştır. DAG'de lezyonların kistik yada nekrotik kısımları beyin parankimi ile karşılaştırılarak değerlendirildi. ADC haritalarından ROI (region of interest) ile kantitatif ölçümler yapıldı. DAG'de araknoid kistlerin, kist hidatik lezyonlarının ve tümörlerin kistik bölümleri serebral paranklme oranla hipointens iken, bakterial apselerde ve epidermoid tümörlerde kistik komponent belirgin hiperintensti. ADC haritasında DAG'de hiperintens /z/enenen epidermoid tümör ve bakterial apseler düşük ADC değerine sahipken, DAG'de hipointens izlenen araknoid kist, kist hidatik ve glioblastomlar yüksek ADC değerine sahipti. İntrakranial kistik lezyonların ayırıcı tanısında DAG yararlı ek bilgiler vermektedir. DAG, bakteriyel abseien kistik-nekrotik tümörlerden, epidermoid kisti ise araknoid kistlerden ayırabilmektedir. Serebral kist hidatik ile araknoid kistin DAG'deki sinyal intensiteleri benzerlik gösterir ve bu iki lezyon arasındaki tek fark intrakranial yerleşimdir (intra/ekstraaksiyel).

Anahtar Kelimeler:

Merkezi sinir sistemi kistleri, Araknoid kistleri, Tanı, ayırıcı, Epidermal kist, Manyetik rezonans görüntüleme, Beyin apsesi

Diffusion-weighted MR imaging of intracranial cystic lesions

The purpose of the study was to evaluate the signal intensities of cystic or necrotic intracranial lesions on diffusion-weighted MRI (DWI) and to investigate the contribution of apparent diffusion coefficient (ADC) values in differential diagnosis. In the study group, there were 24 consecutive patients with intracranial cystic lesions; seven pyogenic abscesses, six epidermoid cysts, four arachnoid cysts, five cystic glioblastomas, and two hydatid cysts. In the MR examinations, conventional spin echo sequences and diffusion-weighted MRI were performed. On DWI imaging, multislice axial plane, single shot, echo-planar spin echo sequence (b=1000 mm2/sn) were used. The intracranial cystic or necrotic lesion signals on DWI were evaluated comparing with normal appearing brain parenchyma. Quantitative ADC measurement were performed on ADC map images with ROI (region of interest). While the cystic portions of tumours, arachnoid cysts and hydatic cysts were hypointense, cystic parts of bacterial abscesses and epidermoid cysts were hyperintense compared to brain parenchyma on diffusion-weighted images. On ADC map images, the cystic portions of tumours, arachnoid cysts and hydatic cysts showed marked high ADC values. However, low ADC values were calculated from cystic parts of bacterial abscesses and epidermoid cysts. DWI is useful technique in evaluation of intracranial cystic lesions. DWI can differentiate pyogenic abscesses from cystic-necrotic tumors as well as epidermoid cysts from arachnoid cysts. Cerebral hydatic cysts and arachnoid cysts show same signals on DWI, but these lesions can be distinguished from others by their location (intraaxial/extraaxial).

Keywords:

Central Nervous System Cysts, Arachnoid Cysts, Diagnosis, Differential, Epidermal Cyst, Magnetic Resonance Imaging, Brain Abscess,

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