Optical Topographic Imaging for Spinal Intraoperative Three-Dimensional Navigation in Mini-Open Approaches: A Prospective Cohort Study of Initial Preclinical and Clinical Feasibility.

OBJECTIVE: Computer-assisted three-dimensional navigation often guides spinal instrumentation. Optical topographic imaging (OTI) offers comparable accuracy and significantly faster registration relative to current navigation systems in open posterior thoracolumbar exposures. We validate the usefulness and accuracy of OTI in minimally invasive spinal approaches. METHODS: Mini-open midline posterior exposures were performed in 4 human cadavers. Square exposures of 25, 30, 35, and 40 mm were registered to preoperative computed tomography imaging. Screw tracts were fashioned using a tracked awl and probe with instrumentation placed. Navigation data were compared with screw positions on postoperative computed tomography imaging, and absolute translational and angular deviations were computed. In vivo validation was performed in 8 patients, with mini-open thoracolumbar exposures and percutaneous placement of navigated instrumentation. Navigated instrumentation was performed in the previously described manner. RESULTS: For 37 cadaveric screws, absolute translational errors were (1.79 ± 1.43 mm) and (1.81 ± 1.51 mm) in the axial and sagittal planes, respectively. Absolute angular deviations were (3.81 ± 2.91°) and (3.45 ± 2.82°), respectively (mean ± standard deviation). The number of surface points registered by the navigation system, but not exposure size, correlated positively with the likelihood of successful registration (odds ratio, 1.02; 95% confidence interval, 1.009-1.024; P < 0.001). Fifty-five in vivo thoracolumbar pedicle screws were analyzed. Overall (mean ± standard deviation) axial and sagittal translational errors were (1.79 ± 1.41 mm) and (2.68 ± 2.26 mm), respectively. Axial and sagittal angular errors were (3.63° ± 2.92°) and (4.65° ± 3.36°), respectively. There were no radiographic breaches >2 mm or any neurovascular complications. CONCLUSIONS: OTI is a novel navigation technique previously validated for open posterior exposures and in this study has comparable accuracy for mini-open minimally invasive surgery exposures. The likelihood of successful registration is affected more by the geometry of the exposure than by its size.

Point-of-Care Ultrasound in Pediatric Diagnostic Dilemmas: Two Atypical Presentations of Intussusception.

Diagnostic dilemmas are ubiquitous in pediatric emergency medicine because of the varied and often insidious presentations of many pediatric conditions. Point-of-care ultrasound (POCUS) in emergency departments is being used for some of these diagnostic challenges and can often provide rapid and valuable information to supplement a physician's clinical assessment. Intussusception is a pediatric condition that may be challenging to recognize because of its subtle and varied presenting symptoms. An unrecognized or delayed diagnosis of intussusception can be catastrophic, with complications including bowel obstruction, bowel perforation, and death. Here we present two challenging cases of intussusception, one due to its atypical age of presentation and the other due to its unique symptoms. These cases demonstrate the benefits of point-of-care ultrasound for diagnostically challenging cases in the emergency department.

The role of palmitoylation for protein recruitment to the inner membrane complex of the malaria parasite.

To survive and persist within its human host, the malaria parasite Plasmodium falciparum utilizes a battery of lineage-specific innovations to invade and multiply in human erythrocytes. With central roles in invasion and cytokinesis, the inner membrane complex, a Golgi-derived double membrane structure underlying the plasma membrane of the parasite, represents a unique and unifying structure characteristic to all organisms belonging to a large phylogenetic group called Alveolata. More than 30 structurally and phylogenetically distinct proteins are embedded in the IMC, where a portion of these proteins displays N-terminal acylation motifs. Although N-terminal myristoylation is catalyzed co-translationally within the cytoplasm of the parasite, palmitoylation takes place at membranes and is mediated by palmitoyl acyltransferases (PATs). Here, we identify a PAT (PfDHHC1) that is exclusively localized to the IMC. Systematic phylogenetic analysis of the alveolate PAT family reveals PfDHHC1 to be a member of a highly conserved, apicomplexan-specific clade of PATs. We show that during schizogony this enzyme has an identical distribution like two dual-acylated, IMC-localized proteins (PfISP1 and PfISP3). We used these proteins to probe into specific sequence requirements for IMC-specific membrane recruitment and their interaction with differentially localized PATs of the parasite.

Comparison of 3% sorbitol vs psyllium fibre as oral contrast agents in MR enterography.

OBJECTIVE: To compare the degree of small bowel distension achieved by 3% sorbitol, a high osmolarity solution, and a psyllium-based bulk fibre as oral contrast agents (OCAs) in MR enterography (MRE). METHODS: This retrospective study was approved by our institutional review board. A total of 45 consecutive normal MRE examinations (sorbitol, n = 20; psyllium, n = 25) were reviewed. The patients received either 1.5 l of 3% sorbitol or 2 l of 1.6 g kg(-1) psyllium prior to imaging. Quantitative small bowel distension measurements were taken in five segments: proximal jejunum, distal jejunum, proximal ileum, distal ileum and terminal ileum by two independent radiologists. Distension in these five segments was also qualitatively graded from 0 (very poor) to 4 (excellent) by two additional independent radiologists. Statistical analysis comparing the groups and assessing agreement included intraclass coefficients, Student's t-test and Mann-Whitney U-test. RESULTS: Small bowel distension was not significantly different in any of the five small bowel segments between the use of sorbitol and psyllium as OCAs in both the qualitative (p = 0.338-0.908) and quantitative assessments (p = 0.083-0.856). The mean bowel distension achieved was 20.1 ± 2.2 mm for sorbitol and 19.8 ± 2.5 mm for psyllium (p = 0.722). Visualization of the ileum was good or excellent in 65% of the examinations in both groups. CONCLUSION: Sorbitol and psyllium are not significantly different at distending the small bowel and both may be used as OCAs for MRE studies. ADVANCES IN KNOWLEDGE: This is the first study to directly compare the degree of distension in MRE between these two common, readily available and inexpensive OCAs.