Anna PuigdellÃvol-Sánchez
University of Barcelona, Spain
Title: Future individualization of intrathecal dosages and paramedian approaches to reduce toxicity and bone contact: Estimating Cerebrospinal fluid dilution volumes and puncture angles from MRI
Biography
Biography: Anna PuigdellÃvol-Sánchez
Abstract
Severe side effects may occur in intrathecal drug delivery systems in cancer patients, where drugs will be diluted in the cerebrospinal fluid, while painful bone contact occurs frequently during punctures. High variability in CSF volumes (CSFv) explains partly the need of different dosages. CSFv and puncture angles may be previously estimated from MRI. Real CSFv values will be close to those obtained from the use of ‘likely’ thresholds, within the range of ‘maximal’ and ‘minimal’ thresholds. ‘Likely’ thresholds: intermediate selection of gray voxels in the borderline zone between roots and CSF. ‘Minimal’ thresholds: selection of cauda equina roots but not adjacent gray voxels. ‘Maximal’ thresholds: threshold is increased until one voxel in the CSF area appears unlabeled and decreased until that voxel was labelled again, selecting the last. Observers made consistent selections with less than 10 minutes of training. Skin-dural sac distances in MRI are close to the distance (d) between the anterior border of the articular process and the external border of the visible soft tissue in lateral lumbosacral Rx. Approximate individualized puncture angle Ì´ inverse cosine [d/ √(1+d2) ] from 1cm paramedian. Significant differences in thresholds exist in the different anatomical area (conus medullaris, upper lumbar levels – cauda equina roots located dorsally within the dural sac- and caudal lumbar levels - roots located laterally-). The estimated range of CSFv within cases is 14%±11%, but maximal/minimal CSFv between cases following a single threshold criterion reached the 210%, suggesting the huge need of individualizing dosages taking the CSFv values into account.