 Good morning, everyone. I am Dr. Kalathuru Uha Sahi from C. Devraj Aras Medical College, Tamaka Kolar. Today, I am presenting a paper on the topic of evaluation of normal measurements of fourth ventricle by computer tomography. My co-authors are Dr. Deepthi Naikma, Dr. Anil Kumar Sakleta, Dr. Chaitanya, Dr. Sandeep Mahima and Dr. Pujita Chaudhary. Aim to evaluate normal measurements of fourth ventricle and their correlation with measurements of cerebrum and age. Introduction. Fourth ventricle of brain, a rhomboid-shaped small cavity containing cerebrospinal fluid communicates anterior superiorly with third ventricle through narrow cerebral aqueduct. Inferiorly with central canal of spinal cord and superior laterally with subarachnoids based through the foremen of Lusca and Majini in its roof. Its dimensions may change with intracranial hypertension, psychiatric alterations, hydrocephalus, epilepsy, meningo, encephalitis, migraines, spinal cord injuries and neurocystisarchosis. Normal size of ventricles in such cases may be of some help to come to a conclusion. Methods. Design of the study, hospital-based prospectus observational study connected to 96 subjects. Method of data selection. Soft copies of normal head CT scans were selected for the measurements using FUSI Synapse Image Software. Inclusion criteria. The patients of both sex with age group from 2 years to 60 years, virtually normal head CT scan, unenhanced head CT scan. Exclusion criteria. CT scan showing gross pathological changes affecting the normal anatomy of ventricles. Methods. Image selection. For the present study, two images were selected for each patient. One axial view at the level of head of potted nucleus. In this view, api diameter of the cerebrum was measured as the maximum distance between the inner tables of the skull in midline. Transverse diameter was measured at the midpoint of the api diameter. The next view is axial view for 4th ventricle measurements. The view was selected in which pan cerebellum, peterous bone, mastoid, andrum, and temporal lobes were visible clearly along with the widest part of the 4th ventricle. Results. General demographic data. Total number of patients included by 96, mean age of patient is 37 years. Total number of male patients were 66. Total number of female patients were 33. Statistical evaluation. All the data was checked by Leven's test for equality of variances for normal distribution, mean standard deviation, ranges, and 95% confidence intervals were calculated for all the parameters. Two sample independent student details was used to find the difference in male and females in these indices. Correlation with diameters of cerebrum were found by calculating PSN correlation coefficient. Correlation with age was found by studying regression statistics. The level of significance was taken as 0.05. This is a table of statistical analysis of frequencies of data. Mean age of the patient is 37 years with the standard deviation of 16.8 ranging from 3 to 60 years. Coming to the AP dimension of the 4th ventricle, mean is 0.75 with the standard deviation of 0.25 cm ranging from 0.3 to 1.6 cm. Transverse diameter of the 4th ventricle, mean is 1.2 cm with the standard deviation of 0.31 cm ranging from 0.6 to 2.1 cm. Coming to the cerebral dimensions, AP dimension, mean is 14.5 cm with the standard deviation of 0.67 cm ranging from 12.8 to 16.3 cm. Transverse dimension of the cerebrum, mean is 12.3 cm with the standard deviation of 0.6 cm ranging from 10.9 to 13.9 cm. T-test is done to find out the difference in males and females in these indices. The difference is significant only in AP and transverse diameter of the cerebrum with the p-value of 0.02 and 0.01 respectively. Correlation is done with the Pearson correlation coefficient. In this correlation, only in this correlation, age is showing a positive correlation with AP and transverse diameter of the 4th ventricle and negative correlation with AP and transverse diameter of the cerebrum. AP diameter of the 4th ventricle is showing a positive correlation with the transverse diameter of the 4th ventricle and transverse diameter of the 4th ventricle is showing a positive correlation with AP diameter of the cerebrum but in this scenario p-value is not significant. Regression statistics is done to find the correlation with age. This is the regression statistics for AP dimension of the 4th ventricle. The formula is Y is equal to 0.03 plus 0.01 X. Here X is the age of the patient and Y is the AP dimension of the 4th ventricle. R-square value is 0.487 and the constant is 0.368. This is the regression statistics for transverse dimension of the 4th ventricle. The formula is Y is equal to 0.835 plus 0.012 X. Where X is the age of the patient and Y is the transverse dimension of the 4th ventricle. R-square value is 0.434 and the constant is 0.835. AP dimension of the 4th ventricle. The present study showed mean AP length of the 4th ventricle as 7.5 plus or minus 2.5 mm. The maximum value being 16 mm. Ampari Vijay et al. By plastination method found the mean height of the 4th ventricle as 2.29 plus or minus 0.3 cm. Desauza and Goller reported height as 1.18 cm, 1.08 cm and 3.8 cm. By CT ventricleography and MRA respectively. Gammeridian et al. found maximum mean height as 9.68 plus or minus 2.15 mm in Saudi population by CT. My findings are in accordance with those Desauza and Gammeridian. In the present study, mean length of the 4th ventricle was higher in meals than in females. But the difference was not significant. Range and variation was also higher in meals than in females. The findings were in accordance with those of study by Brijee Raj et al. And by Mehram Preeti by CT where the height of the 4th ventricle was larger in meals as compared to females. AP diameter of the 4th ventricle showed non-significant correlation with the AP diameter of the cerebrum and no significant correlation with the transverse diameter of the cerebrum. AP diameter of the 4th ventricle showed positive correlation with age which was statistically significant. Coming to the transverse diameter of the 4th ventricle, it showed a mean transverse diameter as 12.8 plus or minus 3.1 mm in the study population. The maximum value being 21.1 mm. The findings are in accordance with those of Agbari, F Duffner, Desauza and Gammeridian. The transverse diameter of the 4th ventricle was higher than the AP length of it. Analyzing the general variation, we found that transverse diameter was higher in meals than in females. Transverse diameter of the 4th ventricle showed slight positive correlation with the antidepressant diameter of the cerebrum and no correlation with the transverse diameter of the skull. Transverse diameter of the 4th ventricle showed positive correlation with age which was statistically significant. Discussion. Ventricle size is increased in various obstructive lesions like in brainstem tumors, blockage of foramina flushka and nachindi, oral churri malformations, autism, etc. Size is changed even according to the hydration status of the patient. It gets increased in first 28 hours of dehydration and then again decreases. CT remains the most accessible, affordable and widely available investigation for brain amazing in Indian scenario. Though the margins of the ventricles are less sharply defined on CT because of partial volume averaging or change in shape of the ventricle due to slight variation in angulation in individual patients due to subjective body buildup. In the context of increased brain ventricle size in protein clinical practice, knowledge of normal range of precise measurements is needed before taking appropriate decisions for further management. These are all my references. Thank you.