Spinal Cord Segmentation by One Dimensional Normalized Template Matching: A Novel, Quantitative Technique to Analyze Advanced Magnetic Resonance Imaging Data.

Spinal cord segmentation is a developing area of research intended to aid the processing and interpretation of advanced magnetic resonance imaging (MRI). For example, high resolution three-dimensional volumes can be segmented to provide a measurement of spinal cord atrophy. Spinal cord segmentation is difficult due to the variety of MRI contrasts and the variation in human anatomy. In this study we propose a new method of spinal cord segmentation based on one-dimensional template matching and provide several metrics that can be used to compare with other segmentation methods. A set of ground-truth data from 10 subjects was manually-segmented by two different raters. These ground truth data formed the basis of the segmentation algorithm. A user was required to manually initialize the spinal cord center-line on new images, taking less than one minute. Template matching was used to segment the new cord and a refined center line was calculated based on multiple centroids within the segmentation. Arc distances down the spinal cord and cross-sectional areas were calculated. Inter-rater validation was performed by comparing two manual raters (n = 10). Semi-automatic validation was performed by comparing the two manual raters to the semi-automatic method (n = 10). Comparing the semi-automatic method to one of the raters yielded a Dice coefficient of 0.91 +/- 0.02 for ten subjects, a mean distance between spinal cord center lines of 0.32 +/- 0.08 mm, and a Hausdorff distance of 1.82 +/- 0.33 mm. The absolute variation in cross-sectional area was comparable for the semi-automatic method versus manual segmentation when compared to inter-rater manual segmentation. The results demonstrate that this novel segmentation method performs as well as a manual rater for most segmentation metrics. It offers a new approach to study spinal cord disease and to quantitatively track changes within the spinal cord in an individual case and across cohorts of subjects.

Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility.

Optical coherence tomography (OCT) has the combined advantage of high temporal (µsec) and spatial (<10µm) resolution. These features make it an attractive tool to study the dynamic relationship between neural activity and the surrounding blood vessels in the spinal cord, a topic that is poorly understood. Here we present work that aims to optimize an in vivo OCT imaging model of the rodent spinal cord. In this study we image the microvascular networks of both rats and mice using speckle variance OCT. This is the first report of depth resolved imaging of the in vivo spinal cord using an entirely endogenous contrast mechanism.

The consequence of delayed neurosurgical care at Tikur Anbessa Hospital, Addis Ababa, Ethiopia.

Tikur Anbessa Hospital (TAH) is the major teaching hospital for Addis Ababa University and the only tertiary referral hospital for neurosurgery in Ethiopia. We explore the consequence of delayed treatment by examining the current system in place for treating patients and the wait times experienced by patients. A retrospective chart review was carried out on patients who received a neurosurgical operation at TAH between January 1 and June 30, 2007. We divided patients into those requiring an elective procedure and those requiring emergency surgical care. Based on data entered in the chart, we determined the length of time from symptom onset to neurosurgical consultation and the time from consultation to receiving an operation. Selective cases were chosen to illustrate the effects of delayed care. A total of 172 neurosurgical operations were performed between January 1 and June 30, 2007, at TAH. Of these, 107 (62.2%) charts were available for retrospective review. Fifty-six elective cases were reviewed. The median time from symptom onset to neurosurgical consultation was 185 days. The median time from neurosurgical consultation to operation was 44 days. Fifty-one trauma/emergency surgical cases were reviewed. The median time from symptom onset or traumatic event to neurosurgical consultation was 3 days. The median time from neurosurgical consultation to operation was 1 day. Delayed neurosurgical care comes with a high personal and social cost. By measuring the time from diagnosis to treatment and taking note of institutional practices, changes can be initiated to improve patient waiting times.