Quantitative Analysis of Spinal Canal Areas in the Lumbar Spine: An Imaging Informatics and Machine Learning Study

BACKGROUND AND PURPOSE

Quantitative imaging biomarkers have not been established for the diagnosis of spinal canal stenosis. This work aimed to lay the groundwork to establish such biomarkers by leveraging the developments in machine learning and medical imaging informatics.

MATERIALS AND METHODS

Machine learning algorithms were trained to segment lumbar spinal canal areas on axial views and intervertebral discs on sagittal views of lumbar MRIs. These were used to measure spinal canal areas at each lumbar level (L1 through L5). Machine-generated delineations were compared with 2 sets of human-generated delineations to validate the proposed techniques. Then, we use these machine learning methods to delineate and measure lumbar spinal canal areas in a normative cohort and to analyze their variation with respect to age, sex, and height using a variable-intercept mixed model.

RESULTS

We established that machine-generated delineations are comparable with human-generated segmentations. Spinal canal areas as measured by machine are statistically significantly correlated with height (P < .05) but not with age or sex.

CONCLUSIONS

Our machine learning methodology demonstrates that this important anatomic structure can be accurately detected and quantitatively measured without human input in a manner comparable with that of human raters. Anatomic deviations measured against the normative model established here could be used to flag spinal stenosis in the future.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Psychogenic mania and bereavement

Early notions of mania invoked a combination of psychogenic and organic factors, but psychogenic mania has not endured as a concept. We present a 37-year-old woman with an acute manic episode precipitated by the prolonged death of her husband from cancer. To our knowledge this is the first published account of 'maniacal grief' in the absence of pre-existing affective disorder, and with clear causal relations. Mania was clearly induced by the bereavement and we argue that the loss represented more than a non-specific life event. This case supports a re-examination of mania as potentially a 'reactive' or psychogenic phenomenon.

Treatment of resistant CAPD peritonitis by temporary discontinuation of peritoneal dialysis

Resistant continuous ambulatory peritoneal dialysis (CAPD) peritonitis (recurrent or persistent infection) is traditionally treated by removal of the CAPD catheter and a period off peritoneal dialysis. In a pilot study we have treated 8 patients with recurrent staphylococcal peritonitis and 3 patients with persistent staphylococcal peritonitis by stopping CAPD for a 2-week period, the CAPD catheter being left in-situ. All 8 patients with recurrent peritonitis and 2 of the 3 patients with persistent peritonitis had resolution of their infection; the third patient required catheter removal to clear the infection. There were no acute problems associated with stopping CAPD, and there was no evidence of loss of peritoneal filtration capacity on restarting CAPD. This novel approach to the treatment of resistant CAPD peritonitis should reduce the number of CAPD catheters replaced and therefore diminish the risks and inconvenience to patients that such replacements entail.

Localization of X-linked dominant Charcot-Marie-Tooth disease (CMT 2) to Xq13

A family is described in which Charcot-Marie-Tooth disease is inherited as an X-linked dominant mutation (CMT2). Ten DNA marker loci on the X chromosome were used to map the disease locus by linkage analysis. The DXYS1 sequence at Xq13 was found to be linked to the CMT2 locus at an estimated distance of 6 cM (Zmax = 2.87 at theta max = 0.06). The data also suggested close linkage of the CMT2 locus to PGK1 (Zmax = 1.51 at theta max = 0) which has also been mapped to Xq13. Another DNA locus (DXS3), in the Xq21.3----Xq22 region, did not show close linkage (Zmax = -2.231 at theta max = 0.01). We conclude that the CMT2 locus is probably in or close to band Xq13.

Effect of prostacyclin on the circulatory histamine during cardiopulmonary bypass

Changes in plasma histamine levels were studied in sixteen dogs under cardiopulmonary bypass (CPB) or bypass with the addition of prostacyclin (PGI2) infusion. In both groups, plasma histamine rose immediately after anaesthetic induction (median above pre-induction: 0.4 ng/ml) and following heparin infusion (median above pre-induction: 0.7 ng/ml). During CPB, plasma histamine levels were elevated throughout the 90 minute period of perfusion (median above pre-induction: 0.5-1.2 ng/ml). PGI2 infusion reduced the elevation in plasma histamine levels (median above preinduction: 0-0.7 ng/ml). These data support the hypothesis that histamine release occurs during CPB. Platelet aggregation in the extracorporeal circuit may be contributory since prostacyclin premedication reduces histamine release.

Regional localization of 18 human X-linked DNA sequences

A series of human probes with unique sequences has been isolated from a recombinant phage library constructed with DNA obtained from a human-hamster hybrid cell line. This cell line contained the X chromosome as the only human component. For 18 of these probes, a human X-chromosome origin has been confirmed and they have been regionally assigned by a combination of techniques: dosage studies utilizing DNA from human fibroblasts carrying X-chromosome duplications and deletions; the presence or absence of hybridization to digested DNA from hybrid lines carrying fragments of the X chromosome; and in situ hybridization to metaphase chromosomes. The use of dosage as a means to regionally assign probes significantly improves resolution of the X chromosome.