 Hello everyone, this is Dr. Vaishnay Rubit Kaurjaya resident from the department of radio diagnosis at TNMC and VYL Niagara charitable hospital. For the 23rd MRI teaching course my topic for paper presentation today is clinical applications of MRI CSF flow met. The normal CSF flow in the systole in the cranial cordial direction it appears as dark and in the diastole in the cordial cranial direction it appears as spread. The image on the left side is a sagittal image and on the left side is the axial face contrast image. There are two types of MRI techniques the first one is a face contrast and the second one is the time slip depth. We use the face contrast image at our institute. The anticipated maximum CSF flow velocity also known as the VENG it must be entered into the pulse sequence protocol to obtain the optimal signal. The mean VENG value is usually between 5 to 8 centimeters for standard CSF flow image. For velocities which are more than that of the VENG it produces aliasing artifacts and for velocities which are less than that of the VENG it produces weak CSF signal. Quantitative CSF flow parameters the first one is the stroke volume is the average of the volume passing distally in systole and proximally in diastole. Normal value is usually between 30 to 50 microliters its use is in that of cases of normal pressure hydrocephalus. Absolute stroke volume is the sum of the volume passing distally in systole and proximally in diastole. It is used in post endoscopic third ventriculostomy patients and the other parameters include peak velocity and mean velocity. Clinical applications include postoperative follow-up of patients with neuro endoscopic third ventriculostomy and ventricular peritoneal shunting. Preoperative evaluation includes normal pressure hydrocephalus and Kiari 1-mal. The other indications are communicating hydrocephalus versus non-communicating hydrocephalus, level of obstruction in obstructive hydrocephalus, arachnoid cyst versus cisterna magna, flow patterns of posterior post-acistic mass formations and syringomydom. So this is a patient with endoscopic third ventriculostomy as we can see there is good to end flow motion across the third ventricle which suggests positive outcome of AETU. And on the left side we can see four images. The first one is that of the defaced image which in which the background is visible and the flow appears bright. The second one is the magnitude in which the background is dark and the flow is bright. The third and fourth one are the two and flow motions in which they are also known as phase images in which the background is great and the motion is detected according to the flow. Here we can see is the axial phase contrast imaging which shows the two and flow motion. So the absolute stroke volume on Q-flow imaging it showed it came out to be 118 microliters. ETV's tomoflow quantification overall flow amplitude also known as the absolute stroke volume in microliters if it's more than 75 microliters it indicates successful ETV outcome. Thus our patient showed good ETV outcome classified into three categories adequate flow which is more than 75 microliters, low flow 25 up to less than 75 microliters and obstructed ETV's tomoflow with impaired flow is less than 25 microliters. In V-patients it's a one-way valve mechanism which is the flow's unit direction and it's rhythmic. So because of very low CSF flow rates in shunt catheters minimum vent which is between two to five centimeters is used for assessing V-patients. No signal means no flow on phase contrast image. As we can see here in phase contrast MRI it demonstrates a bright signal than the background which has this patency at the side of the shunt. This flow pattern is consistent with the one-way flow in the VP shunt. In normal pressure hydrocephalus significantly higher vent values which are between 20 to 25 centimeters should be chosen owing to the hyperdynamic CSF flow within the cerebral algorithm. For shunt responsiveness cutoff value for stoke volume is 42 microliters. As we can see here in phase contrast imaging there's good two-and-flow flow however the pulse pressure is increased. In the Q flow imaging technique average stoke volume came out to be 90 microliters which shows good response for shunting of an NPH patient. Kiari one mile formation as we can see there is herniation of the brainstem as well as the tonsils below which leads to effacement of the anterior as well as the posterior subarachnoid space. So the size of the herniation is not always associated with symptom severity. In the preoperative patient there is no flow across the anterior subarachnoid space and in the postoperative patient post surgical decompression there is good two-and-flow flow. In five mm tonsillar descent we can see there is good anterior and posterior flow thus it means that if there is less tonsillar descent there is less effacement. In 15 mm tonsillar and brainstem descent with syringomyelia, tonsillar and brainstem pistonin effect can be seen and there is absence of posterior fluid. In tonsillar and brainstem descent of 13 mm there is no anterior or posterior fluid. So the degree of CSF flow obstruction rather than the degree of tonsillar herniation can better select patients who are most responsive to surgery. In obstructive hydrocephalus due to aqueductal stenosis there is no flow at the level of aqueduct in both sagittal as well as axial face controsymbology. Arachnoid cyst versus cysternomagnum, megasysternomagnum, pulsatile CSF flow can be seen throughout the dilated cysternomagnum whereas in communicating posterior fossa arachnoid cyst pulsatile flow into the cyst at the level of cerebellum medullary junction is seen. However the flow is not present throughout the cyst and it is different from that of megasysternomagnum. Flow patterns of posterior fossa cystic malformations in dandy walker malformation CSF flow MRI shows no communication between the cyst and posterior cervical subarygnoid space and hyperdynamic CSF flow through the aqueduct into the cyst produces turbulent flow within the cyst. In syringomyia it detects altered flow inside the syringe cavity. It is predictive of subsequent enlargement and helps discriminate it from amylomilation and provides a direct evaluation for the follow-up and the postoperative survey in patients with syringomylic cyst. Teaching points, face controsymbology is a primary non-invasive technique providing assessment of disruptions in the CSF compartment both qualitatively as well as quantitative. It plays a vital role in pre-operative decision-making and post-operative follow-up of patients. Thank you very much.