{'fraction_non_alphanumeric': 0.04293294741919923, 'fraction_numerical': 0.030390738060781478, 'mean_word_length': 4.994219653179191, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
129 Using Magnetic Resonance Imaging to Establish Patency Between Adjacent Cerebral Spinal Fluid Compartments.

INTRODUCTION
The ability to establish patency of cerebral spinal fluid (CSF) flow between adjacent central nervous system (CNS) compartments is of importance in the diagnosis and treatment of patients with CSF flow obstruction in various areas. The method described was originally derived from arterial spin labeling (ASL) of blood flowing in vessels. This technique, referred to as time-spatial labeling inversion pulse (time-SLIP), was further modified to noninvasively visualize CSF pulsatile and turbulent flow between 2 regions of interest.


METHODS
The presence of CSF flow was examined at the foramen Magnum (FMag), the aqueduct of Sylvius (AS), the foramen of Magendie (FMgd), the floor of the third ventricle (3rd V), and at the foramen of Monro (FM). The studies were compared with clinical information and classified as true positive, true negative, false positive, and false negative based on expectation of patency.


RESULTS
A total of 83 studies were done on 51 patients. Among positive readings of the FMag, AS, 3rd V, and FM, 49/49, 40/40, 15/15, and 9/9 were true, while 3/5, 20/30, 2/5, and 0/2 negative readings were true, respectively. The sensitivity and specificity percentages of the technique at the FMag, AS, 3rd V, and FM were, respectively, 96, 100; 80, 100; 83, 100, and 82, undefined. Negative likelihood ratios for these sites were, respectively, 0.04, 0.20, 0.17, and undefined.


CONCLUSION
Establishing qualitative patency between adjacent CSF compartments using MRI is possible with a modified ASL technique. The freely selectable tag allows CSF flow to be visualized in any direction or location. This technique can be used after endoscopic third ventriculostomy to evaluate the patency of the fenestration in addition to evaluating pre- and postoperative craniocervical decompression changes to CSF flow. This technique has excellent (above 80%) sensitivity, specificity, and negative likelihood ratio at all sites studied.