ارزیابی اندازه و تغییرات سیسترنا مگنا با MRI

Title

evaluation of the size and variation of Cisterna Magna by MRI

English Abstract

Cisterna magna is the largest subarachnoid cistern located between cerebellum and medulla obliangata. Cisterna magna is enlarged in Dandy Walker syndrome and is small in Arnold Chiari syndrome and syrningomyelia. Enlargment of the cistern magna can be a normal variation. We studied the size of cistern magna in 400 cases. Any of them had symptoms of the mass in the posterior fossa. First we measured the surface of the cistern magna in midsagittal plane. Then the size of cistern magna is measured in axial plane. Also we evaluated the shape of the cistern magna in midsagittal plane. We evaluated the herniation of the cerebellar tonsils in midsagittal plane. Surface of the cistern magna in midsagittal plane ranged between 0-726.6 mm2. The mean of this surface was 167.8±141.6. Surface of the cistern magna in males is significantly greater than females (p=0.000). In 9.3% of cases surface of the cistern magna is about 0 and 86.5% of them were females. Incidence of Arnold Chiari is 0.25% in our study. The size of cistern magna in axial plane was between 3.1-34.1 mm. the mean of this size was 15.6±7.04. The size of cistern magna in males was significantly greater than females in axial plane (p=0.000). Cistern magna is effaced in 9.3% of our cases, which 86.5% of them were females. Maximum size of the cistern magna in males is greater than females. These results maybe related to differential between the anatomic size of the posterior fossa in males and females. We studied symptoms of the cerebral atrophy in 5% of our cases which had largest cistern magna. None of them had obvious symptoms of cerebral atrophy. In 323 cases of all cases cistern magna is triangular in midsagittal plane and in 37 cases obliterated.

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