Colloid cysts of the third ventricle: Are MR imaging patterns predictive of difficulty with percutaneous treatment?

BACKGROUND AND PURPOSE: Colloid cysts of the third ventricle are rare benig n brain tumors. The purpose of this study was to correlate their patterns o n MR images with the probability of success of percutaneous treatment. METHODS: Nineteen patients underwent endoscopic treatment for colloid cysts of the third ventricle. The cases were divided into two groups based on di fficulty of the aspiration procedure. We reviewed CT scans and MR images an d divided cysts into groups based on their signal intensity on the MR image s and their density on CT scans. Intensity and density were correlated with difficulty of aspiration during the endoscopic procedure. RESULTS: The aspiration procedure was difficult in 63% of the cases. Eighty -nine percent of hyperdense cysts on unenhanced axial CT scans were categor ized as difficult, and 75% of hypodense cysts were categorized as easy. On T2-weighted MR sequences, 100% of low-signal cyst contents were difficult a nd nearly 63% of high-signal lesions were easy. There was a significant cor relation between the T2-weighted sequences and the CT scans regarding the d ifficulty of the aspiration procedure. CONCLUSION: T2-weighted MR sequences are useful for predicting difficulty o f aspiration during stereotactic or endoscopic procedures. A T2-weighted lo w-signal cyst is correlated with high-viscosity intracystic contents.