Development of a shoulder-mounted robot for MRI-guided needle placement: phantom study

Purpose

This paper presents new quantitative data on a signal-to-noise ratio (SNR) study, distortion study, and targeting accuracy phantom study for our patient-mounted robot (called Arthrobot). Arthrobot was developed as an MRI-guided needle placement device for diagnostic and interventional procedures such as arthrography.

Methods

We present the robot design and inverse kinematics. Quantitative assessment results for SNR and distortion study are also reported. A respiratory motion study was conducted to evaluate the shoulder mounting method. A phantom study was conducted to investigate end-to-end targeting accuracy. Combined error considering targeting accuracy, respiratory motion, and structure deformation is also reported.

Results

The SNR study showed that the SNR changes only 2% when the unpowered robot was placed on top of a standard water phantom. The distortion study showed that the maximum distortion from the ground truth was 2.57%. The average error associated with respiratory motion was 1.32 mm with standard deviation of 1.38 mm. Results of gel phantom targeting studies indicate average needle placement error of 1.64 mm, with a standard deviation of 0.90 mm.

Conclusions

Noise and distortion of the MR images were not significant, and image quality in the presence of the robot was satisfactory for MRI-guided targeting. Combined average total error, adding mounting stability errors and structure deformation errors to targeting error, is estimated to be 3.4 mm with a standard deviation of 1.65 mm. In clinical practice, needle placement accuracy under 5 mm is considered sufficient for successful joint injection during shoulder arthrography. Therefore, for the intended clinical procedure, these results indicate that Arthrobot has sufficient positioning accuracy.

     

Initial graft size and not the innate immune response limit survival of engrafted neural stem cells

Transplantation of neural stem cells (NSCs) appears to be a promising regenerative therapy for a variety of neurological disorders. Nevertheless, NSC engraftment is limited by the number of surviving cells. To maximize stem cell‐mediated effects, timing of implantation and cell number have to be precisely evaluated. Here, a transgenic murine NSC line was optimized for high expression levels of the imaging reporters Luc2 and copGFP. NSCs of 150 000, 75 000, 15 000 or 1500 cells or Hanks buffered salt solution were implanted into the striatum of nude mice. The survival of NSCs was monitored with in vivo bioluminescence imaging (BLI) over 2 weeks and brain sections were histologically analysed for glial cells of the innate immune system. The longitudinal in vivo BLI data revealed a significantly reduced viability with the highest rate for 150 000 engrafted NSCs. The cell loss was not correlated with the number of Iba‐1⁺ immune cells nor GFAP⁺ astrocytes. Histological quantification of copGFP⁺ cells at 14 days postimplantation confirmed the in vivo data with the highest density of copGFP⁺ cells in the 150 000‐cell graft and the highest survival rate for 1500 cells/graft. In conclusion, regenerative therapies should strictly evaluate the maximal number of stem cells to be transplanted in one location, as the results suggest that there is a critical limit of cells able to survive in the adult brain. Survival is limited by availability of oxygen and nutrients but not the inflammatory response induced by the implantation.     

Prevalence and reliability of treatment-based classification for subgrouping patients with low back pain

Objectives: To observe the distribution of patients who presented with low back pain (LBP) and to determine the between therapists’ interrater reliability of assessments in a private outpatient setting using treatment-based classification (TBC) subgroups.

Methods: An observational and methodological study was conducted. Four hundred and twenty-nine patients (231 male; 198 female) presenting LBP symptoms and referred to conservative treatment were assessed by 13 physical therapists who conducted a 60-min examination process utilizing TBC subgroups. Interrater reliability analyses from six raters were assessed using Fleiss’ kappa and previously recorded data (n = 30).

Results: In this study, 65.74% of patients were classified in only one subgroup, the most prevalent being stabilization (21.91%), followed by extension (15.38%), traction (11.89%), flexion (10.96%), manipulation (5.13%), and lateral shift (0.47%). Approximately 20.98% of patients were classified in two subgroups, where the most frequent overlaps were flexion + stabilization (7.46%), extension + stabilization (6.06%), flexion + traction (4.20%), extension + manipulation (1.86%), and 13.29% of patients were not classified in any TBC subgroup. Analysis of interrater reliability showed a kappa value of 0.62 and an overall agreement of 66% between raters.

Discussion: LBP is a heterogeneous clinical condition and several classification methods are proposed in the attempt to observe better outcomes for patients. Eighty-five percent of patients assessed were able to be classified when using the TBC assessment and reliability analysis showed a substantial agreement between raters.

Level of Evidence: 2c.     

Therapies for multidrug resistant and extensively drug-resistant non-fermenting gram-negative bacteria causing nosocomial infections: a perilous journey toward ‘molecularly targeted’ therapy

Introduction: Non-fermenting Gram-negative bacilli are at the center of the antimicrobial resistance epidemic. Acinetobacter baumannii and Pseudomonas aeruginosa are both designated with a threat level to human health of ‘serious’ by the Centers for Disease Control and Prevention. Two other major non-fermenting Gram-negative bacilli, Stenotrophomonas maltophilia and Burkholderia cepacia complex, while not as prevalent, have devastating effects on vulnerable populations, such as those with cystic fibrosis, as well as immunosuppressed or hospitalized patients.

Areas covered: In this review, we summarize the clinical impact, presentations, and mechanisms of resistance of these four major groups of non-fermenting Gram-negative bacilli. We also describe available and promising novel therapeutic options and strategies, particularly combination antibiotic strategies, with a focus on multidrug resistant variants.

Expert commentary: We finally advocate for a therapeutic approach that incorporates in vitro antibiotic susceptibility testing with molecular and genotypic characterization of mechanisms of resistance, as well as pharmacokinetics and pharmacodynamics (PK/PD) parameters. The goal is to begin to formulate a precision medicine approach to antimicrobial therapy: a clinical-decision making model that integrates bacterial phenotype, genotype and patient’s PK/PD to arrive at rationally-optimized combination antibiotic chemotherapy regimens tailored to individual clinical scenarios.     

Sleep Mediates the Association Between PTSD Symptoms and Chronic Pain in Youth

Symptoms of post-traumatic stress disorder (PTSS) and chronic pain have been shown to co-occur at high rates in adolescents and this co-occurrence is linked to worse pain and quality of life. Sleep disturbance has been posited as a mechanism underlying this co-occurrence in conceptual models of mutual maintenance. This study examined the mediating role of sleep in the relationship between PTSS and pain in youth (aged 10–17 years) with chronic pain. Ninety-seven participants completed measures of PTSS, pain (intensity and interference), anxiety symptoms, and sleep quality, in addition to demographic characteristics. Mediation models were conducted. Findings revealed that, over and above the influence of associated demographic characteristics (age, race) and anxiety symptoms, sleep quality partially mediated the relationships between PTSS and pain intensity and interference for youth with chronic pain. Specifically, higher levels of PTSS was linked to higher levels of pain intensity and pain interference, and these relationships were partially explained by poor sleep quality. Findings highlight the potential mechanistic role of sleep in explaining the co-occurrence of chronic pain and PTSS and suggest sleep might be an important target in future interventions.

The clinical evaluation of the CADence device in the acoustic detection of coronary artery disease

The noninvasive detection of turbulent coronary flow may enable diagnosis of significant coronary artery disease (CAD) using novel sensor and analytic technology. Eligible patients (n?=?1013) with chest pain and CAD risk factors undergoing nuclear stress testing were studied using the CADence (AUM Cardiovascular Inc., Northfield MN) acoustic detection (AD) system. The trial was designed to demonstrate non-inferiority of AD for diagnostic accuracy in detecting significant CAD as compared to an objective performance criteria (sensitivity 83% and specificity 80%, with 15% non-inferiority margins) for nuclear stress testing. AD analysis was blinded to clinical, core lab-adjudicated angiographic, and nuclear data. The presence of significant CAD was determined by computed tomographic (CCTA) or invasive angiography. A total of 1013 subjects without prior coronary revascularization or Q-wave myocardial infarction were enrolled. Primary analysis was performed on subjects with complete angiographic and AD data (n?=?763) including 111 subjects (15%) with severe CAD based on CCTA (n?=?34) and invasive angiography (n?=?77). The sensitivity and specificity of AD were 78% (p?=?0.012 for non-inferiority) and 35% (p?<?0.001 for failure to demonstrate non-inferiority), respectively. AD results had a high 91% negative predictive value for the presence of significant CAD. AD testing failed to demonstrate non-inferior diagnostic accuracy as compared to the historical performance of a nuclear stress OPC due to low specificity. AD sensitivity was non-inferior in detecting significant CAD with a high negative predictive value supporting a potential value in excluding CAD.     

Advanced Practice Registered Nurse–directed Care Coordination Interventions and Outreach After Critical Illness

The purpose of this pilot study was to implement care collaboration measures into a critical care advanced practice. The intervention included an outreach algorithm and a standardized handoff tool during care transition. One hundred eight patients were enrolled; 5 (4%) experienced unplanned readmission. There was no significant association with transition time and the ability to complete the algorithm. Comorbidities of chronic obstructive pulmonary disease (P < .005), a PaO₂ ratio < 200 (P < .003), and pulmonary disease (P < .027) showed increased unplanned readmission within 48 hours of transition. Implementing critical care collaborating measures was not affected by transition time and unit care flow.