Feasibility and Accuracy of Thoracolumbar Pedicle Screw Placement Using an Augmented Reality Head Mounted Device

Background: To investigate the accuracy of augmented reality (AR) navigation using the Magic Leap head mounted device (HMD), pedicle screws were minimally invasively placed in four spine phantoms. Methods: AR navigation provided by a combination of a conventional navigation system integrated with the Magic Leap head mounted device (AR-HMD) was used. Forty-eight screws were planned and inserted into Th11-L4 of the phantoms using the AR-HMD and navigated instruments. Postprocedural CT scans were used to grade the technical (deviation from the plan) and clinical (Gertzbein grade) accuracy of the screws. The time for each screw placement was recorded. Results: The mean deviation between navigation plan and screw position was 1.9 ± 0.7 mm (1.9 [0.3–4.1] mm) at the entry point and 1.4 ± 0.8 mm (1.2 [0.1–3.9] mm) at the screw tip. The angular deviation was 3.0 ± 1.4° (2.7 [0.4–6.2]°) and the mean time for screw placement was 130 ± 55 s (108 [58–437] s). The clinical accuracy was 94% according to the Gertzbein grading scale. Conclusion: The combination of an AR-HMD with a conventional navigation system for accurate minimally invasive screw placement is feasible and can exploit the benefits of AR in the perspective of the surgeon with the reliability of a conventional navigation system.

Infrared Thermography for Measuring Elevated Body Temperature: Clinical Accuracy, Calibration, and Evaluation

Infrared thermographs (IRTs) implemented according to standardized best practices have shown strong potential for detecting elevated body temperatures (EBT), which may be useful in clinical settings and during infectious disease epidemics. However, optimal IRT calibration methods have not been established and the clinical performance of these devices relative to the more common non-contact infrared thermometers (NCITs) remains unclear. In addition to confirming the findings of our preliminary analysis of clinical study results, the primary intent of this study was to compare methods for IRT calibration and identify best practices for assessing the performance of IRTs intended to detect EBT. A key secondary aim was to compare IRT clinical accuracy to that of NCITs. We performed a clinical thermographic imaging study of more than 1000 subjects, acquiring temperature data from several facial locations that, along with reference oral temperatures, were used to calibrate two IRT systems based on seven different regression methods. Oral temperatures imputed from facial data were used to evaluate IRT clinical accuracy based on metrics such as clinical bias (Δcb), repeatability, root-mean-square difference, and sensitivity/specificity. We proposed several calibration approaches designed to account for the non-uniform data density across the temperature range and a constant offset approach tended to show better ability to detect EBT. As in our prior study, inner canthi or full-face maximum temperatures provided the highest clinical accuracy. With an optimal calibration approach, these methods achieved a Δcb between ±0.03 °C with standard deviation (σΔcb) less than 0.3 °C, and sensitivity/specificity between 84% and 94%. Results of forehead-center measurements with NCITs or IRTs indicated reduced performance. An analysis of the complete clinical data set confirms the essential findings of our preliminary evaluation, with minor differences. Our findings provide novel insights into methods and metrics for the clinical accuracy assessment of IRTs. Furthermore, our results indicate that calibration approaches providing the highest clinical accuracy in the 37–38.5 °C range may be most effective for measuring EBT. While device performance depends on many factors, IRTs can provide superior performance to NCITs.

Papilloplex HR-HPV test has non-inferior clinical performance for detection of human papillomavirus infection: assessment using the VALGENT framework

AimThe Papilloplex high-risk human papillomavirus (hrHPV) test (Genefirst, Oxford, UK) is a single tube real-time HPV test which provides multiplex detection and separate identification of 14 hrHPV types. Here, we present the clinical validation of the test in SurePath samples in comparison to a clinically validated reference test, the GP5+/6+Enzyme ImmunoAssay (GP5+/6+EIA) using the VALGENT (VALidation of HPV GENotyping Tests) framework.MethodsClinical performance was assessed using 998 unselected, cervical screening samples enriched with 297 cytologically abnormal specimens (100 atypical squamous cells of unspecified significance, 100 low-grade squamous intraepithelial lesions, 97 high-grade squamous intraepithelial lesions). Cases were defined as women diagnosed with histologically confirmed cervical intraepithelial neoplasia two or more (≥CIN2, N=119) and controls defined as women with two subsequent negative cytology results (N=834).ResultsThe Papilloplex HR-HPV test has non-inferior sensitivity for detection of cervical precancer (p=0.0001 for ≥CIN2 and p=0.0005 for ≥CIN3) and non-inferior specificity, compared with GP5+/6+EIA (pni=0.0167)). The assay also showed excellent or good agreement for overall hrHPV and nearly all individual HPV types as compared with GP5+/6+EIA/Luminex.ConclusionThe Papilloplex HR-HPV applied on cervical specimens stored in SurePath medium fulfils the international clinical accuracy criteria for use in cervical cancer screening.

Development, evaluation of the PNA RT-LAMP assay for rapid molecular detection of SARS-CoV-2

Dual-labeled PNA probe used RT-LAMP molecular rapid assay targeting SARS-CoV-2 ORF1ab and N genes was developed, and the analytical, clinical performances for detection of SARS-CoV-2 RNA extracted from clinical nasopharyngeal swab specimens were evaluated in this study. Data showed that this assay is highly specific for SARS-CoV-2, and the absolute detection limit is 1 genomic copy per microliter of viral RNA which can be considered to be comparable to gold-standard molecular diagnostic method real-time reverse transcriptase PCR. Both clinical sensitivity and specificity against a commercial real-time RT-PCR assay were determined as identical. In conclusion, the PNA RT-LAMP assay showed high analytical and clinical accuracy which are identical to real-time RT-PCR which has been routinely used for the detection of SARS-CoV-2.

EP.FRI.479 Clinical accuracy of u/sound combined with inflammatory markers in Acute Appendicitis

Traditionally acute appendicitis has been a clinical diagnosis based on patients' history and physical examination, but the accuracy of clinical diagnosis ranges from 70-95%. Pre-operative diagnosis of acute appendicitis still remains an enigmatic challenge, because no single test alone can reduce the rate of negative appendectomy. Hence some authors have recommended a combination of two or more investigations to increase accuracy and therefore the use of imaging is gaining support. The objective of the study was to determine the clinical accuracy of ultrasound, combined with inflammatory markers such as CRP, WBC, and neutrophilia keeping histopathology as the gold standard. Methods The study was conducted in a Tertiary care hospital in Peshawar from September 2014 to March 2015 on 250 patients who were clinically diagnosed with acute appendicitis. All these patients underwent u/sound scanning in addition to blood tests. Findings In this study, WBC had the highest sensitivity (77.68%) followed by neutrophil% (69.96%), CRP(67.10%), and U/Sound (62.96%) respectively. While U/Sound had the highest specificity (70.59%) followed by CRP and TLC (64.71% each) and neutrophil% (58.82%) respectively. When all the four tests were combined the sensitivity, specificity, (99.17% and 98.45%) increased significantly. When all four tests were negative, appendicitis could be safely ruled out. Conclusion Acute appendicitis is very unlikely and surgery can be safely deferred in these patients when all tests are negative thereby reducing the negative appendicectomy rates.

Clinical accuracy and initial experience with augmented reality–assisted pedicle screw placement: the first 205 screws

OBJECTIVE Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system. METHODS A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors’ institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion. RESULTS Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m2. Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall. CONCLUSIONS AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

Evaluation of indeterminate SARS-CoV-2 results with repeat testing on an alternative platform

Introduction/Objective Accurate SARS-CoV-2 results are crucial for patient management and infection prevention. Result confidence decreases with low viral load because near the assay’s limit of detection (LOD), test results may alternate between positive and negative, as characterized by Poisson distribution for target analytes at low density. Low positive results may indicate past infection, early infection, a vaccinated individual with low level viral shed, or a false-positive result. EUA methods provide guidance on test interpretation, but laboratories should assess clinical accuracy. The purpose of this study was to assess clinical accuracy of specimens with low positive results. Methods/Case Report Respiratory specimens were tested by Cepheid Xpert® Xpress SARS-CoV-2 assay with positive results up to a Ct of 45. A low positive (defined as Ct ≥35), which could not be confirmed by Hologic Aptima® SARS-CoV-2 assay was reported as indeterminate and repeat testing recommended. Repeat testing occurred by Cepheid, Hologic, BioFire, Roche, or Quest assays. Retrospectively, final results were extracted from the LIS (Epic Beaker, Madison, WI, version May 2020) for 5-months (12/1/2020 to 5/31/2021), and chart review performed. Results (if a Case Study enter NA) A total of 19,969 tests were performed; 10.4% (n=2,083) were positive, 89% (n=17,728) negative, and 0.79% (n=158) indeterminate. Previous infection (up to 3 months prior) was documented in 18% (n=28) of indeterminate results and defined as true positive. Of remaining indeterminate results, 43% (n=68) had repeat testing as recommended by laboratory; 26% (n=18) were positive and 74% (n=50) were negative. The average number of days between indeterminate and negative result was 7.25 (range 1-38). Conclusion Result discordance occurred in < 1% of all samples, excellent agreement. For low positive samples, discordance was higher, as expected. It’s impossible to determine if negative results from the 50 repeat samples were false-positive by Cepheid or false-negative by other methods. In summary, 32% (50/158) of indeterminant samples did not repeat as positive. Overall concordance was high and results fluctuate when low virus is present. In absence of symptoms, we conclude repeat testing is not routinely recommended. Laboratories must recognize that normal variability occurs near assay LOD and must critically assess performance against other methods with similar LODs to fully assess performance of EUA methods.