Location Of Markers Research Articles

QTL Mapping for Gummy Stem Blight Resistance in Watermelon (Citrullus spp.).

Watermelon (Citrullus lanatus) is an economically important fruit crop worldwide. Gummy stem blight (GSB) is one of the most damaging diseases encountered during watermelon cultivation. In the present study, we identified quantitative trait loci (QTLs) associated with GSB resistance in an F2 population derived from a cross between maternal-susceptible line ‘920533’ (C. lanatus) and the paternal-resistant line ‘PI 189225’ (C. amarus). The resistance of 178 F2 plants was assessed by two different evaluation methods, including leaf lesion (LL) and stem blight (SB). To analyze the QTLs associated with GSB resistance, a linkage map was constructed covering a total genetic distance of 1070.2 cM. QTL analysis detected three QTLs associated with GSB resistance on chromosome 8 and 6. Among them, two QTLs, qLL8.1 and qSB8.1 on chromosome 8 identified as major QTLs, explaining 10.5 and 10.0% of the phenotypic variations localizing at same area and sharing the same top markers for both LL and SB traits, respectively. A minor QTL, qSB6.1, explains 9.7% of phenotypic variations detected on chromosome 6 only for the SB trait. High-throughput markers were developed and validated for the selection of resistant QTLs using watermelon accessions, and commercial cultivars. Four potential candidate genes were predicted associated with GSB resistance based on the physical location of flanking markers on chromosome 8. These findings will be helpful for the development of watermelon cultivars resistant to GSB.

The influence of soft tissue artifacts on multi-segment foot kinematics

Movement of skin markers with respect to their underlying bone (i.e. soft tissue artifacts (STAs)) might corrupt the accuracy of marker-based movement analyses. This study aims to quantify STAs in 3D for foot markers and their effect on multi-segment foot kinematics as calculated by the Oxford and Rizzoli Foot Models (OFM, RFM). Fifteen subjects with asymptomatic feet were seated on a custom-made loading device on a computed tomography (CT) table, with a combined OFM and RFM marker set on their right foot. One unloaded reference CT-scan with neutral foot position was performed, followed by 9 loaded CT-scans at different foot positions. The 3D-displacement (i.e. STA) of each marker in the underlying bone coordinate system between the reference scan and other scans was calculated. Subsequently, segment orientations and joint angles were calculated from the marker positions according to OFM and RFM definitions with and without STAs. The differences in degrees were defined as the errors caused by the marker displacements. Markers on the lateral malleolus and proximally on the posterior aspect of the calcaneus showed the largest STAs. The hindfoot-shank joint angle was most affected by STAs in the most extreme foot position (40° plantar flexion) in the sagittal plane for RFM (mean: 6.7°, max: 11.8°) and the transverse plane for OFM (mean: 3.9°, max: 6.8°). This study showed that STAs introduce clinically relevant errors in multi-segment foot kinematics. Moreover, it identified marker locations that are most affected by STAs, suggesting that their use within multi-segment foot models should be reconsidered.

Impact of scaling errors of the thigh and shank segments on musculoskeletal simulation results

Musculoskeletal simulations are widely used in the research community. The locations of surface markers are mostly used to scale a generic model to the participant's anthropometry. Marker-based scaling approaches include errors due to inaccuracies in marker placements. How do scaling errors of the thigh and shank segments influence simulation results? Motion capture data and magnetic resonance images from a child with cerebral palsy and a typically developing child were used to create a subject-specific reference model for each child. These reference models were modified to mimic scaling errors due to inaccurately placed lateral epicondyle markers, which are frequently used to scale the thigh and shank segments. The thigh length was altered in 1 % steps from the original length and the shank length was accordingly adjusted to keep the total leg length constant. Thirty additional models were created, which included models with an altered thigh length of ±15 %. Subsequently, musculoskeletal simulations with OpenSim were performed with all models. Joint kinematics, joint kinetics, muscle forces and joint contact forces (JCF) were compared between the reference and altered models. The investigated scaling error influenced joint kinematics and joint kinetics by up to 9.4° (hip flexion angle) and 0.15 Nm/kg (knee flexion moment), respectively. Maximum muscle and JCF differences of 46 % (medial gastrocnemius) and 72 % (hip JCF) bodyweight, respectively, were observed between the reference and altered models. Scaling errors mainly changed the magnitude but not the shape of most analyzed parameters. The influence of scaling errors on simulation results were similar in both participants. Scaling errors of the thigh segment influence simulation results at all joints due to the global optimization approach used in musculoskeletal simulations. Our findings can be used to estimate potential errors due to marker-based scaling approaches in previous and future studies.

Correction: The biomechanics of knuckle-walking: 3-D kinematics of the chimpanzee and macaque wrist, hand and fingers.

There was an error published in Journal of Experimental Biology (2020) 223, jeb224360 (doi:10.1242/jeb.224360).The description of the calculation of metacarpophalangeal (MCP) joint abduction and adduction was incorrect. It was originally described as the angle between the metacarpal and the projection of the phalangeal vector onto the plane of best fit of the metacarpals. This was not the case. The MCP adduction/abduction angle was calculated as the 3-D angle between the phalangeal vector projected onto the sagittal metacarpal plane (gray plane of Fig. 2) and the vector describing the actual position of the phalanges. The originally described calculation is sensitive to changes in MCP flexion and extension, whereas the calculation actually used is not. No data, analyses or conclusions are changed as a result of this; only the description of the calculation used in the Materials and Methods and the representation of this in Fig. 2 were incorrect.The corrected text in Materials and Methods (third to last sentence in ‘Metacarpophalangeal motion’) reads: ‘Adduction and abduction were calculated as the 3-D angle between the vector projection of the phalangeal markers onto the sagittal metacarpal plane (vpp_proj in Fig. 2C,D) and the actual vector defining each phalanx. This calculation returns a value for abduction and adduction that is insensitive to the degree of MCP flexion and extension.’The original and corrected versions of Fig. 2 are shown below. Both the online full-text and PDF versions of the article have been updated.The authors apologise to the readers for any inconvenience caused and thank Dr Joris Leijnse for identification of this error.Fig. 2. (corrected). Forearm, hand and phalangeal coordinate systems and marker sets for the right side in dorsal view. Marker locations are described in Table S1. (A) The red markers are those that were used to define the forearm (Xf, Yf and Zf) or hand (Xh, Yh and Zh) coordinate system (black arrows). Dashed arrows represent vectors that were used to help orient the coordinate system. Pink markers are those additional markers that were used to help calculate wrist joint motion, but were not used in defining the coordinate system. (B) nmc is the normal vector to a plane of best fit to all eight metacarpal landmarks (white plane; B). For each digit, a plane perpendicular to this, oriented along each metacarpal's base and head landmark, was used to describe the sagittal plane of each metacarpal (gray plane in B and C, describing sagittal plane of the second metacarpal). (C) The projection of the phalangeal vector onto this plane was used to describe flexion (–; deg) and extension (+; deg). (D) Adduction (–; deg) and abduction (+; deg) were calculated as the 3-D angle between the vector projection of the phalangeal markers (vpp_proj) onto the sagittal metacarpal plane (gray plane) and the actual vector of the phalanges.Fig. 2. (original). Forearm, hand and phalangeal coordinate systems and marker sets for the right side in dorsal view. Marker locations are described in Table S1. (A) The red markers are those that were used to define the forearm (Xf, Yf and Zf) or hand (Xh, Yh and Zh) coordinate system (black arrows). Dashed arrows represent vectors that were used to help orient the coordinate system. Pink markers are those additional markers that were used to help calculate wrist joint motion, but were not used in defining the coordinate system. (B) nmc is the normal vector to a plane of best fit to all eight metacarpal landmarks (white plane; B). For each digit, a plane perpendicular to this, oriented along each metacarpal's base and head landmark, was used to describe the sagittal plane of each metacarpal (gray plane in B and C, describing sagittal plane of the second metacarpal). (C) The projection of the phalangeal vector onto this plane was used to describe flexion (–; deg) and extension (+; deg). (D) The projection of the phalangeal vectors onto the plane of best fit of the metacarpals was used to describe adduction (–; deg) and abduction (+; deg).

Bone Morphogenetic Protein-7 (BMP-7) Promotes Neuronal Differentiation of Bone Marrow Mesenchymal Stem Cells (BMSCs) In Vitro.

This study is aimed at investigating the effects of bone morphogenetic protein-7 (BMP-7) on the differentiation of bone marrow mesenchymal stem cells (BMSCs) into neuron-like cells in vitro. The rat BMSCs were isolated and identified, which were divided into the control, empty, recombinant rhBMP-7 transfection, and Lv-BMP-7 transfection groups. BMSCs were induced under different conditions. CCK-8 assay was performed to detect cell proliferation. ALP was used to detect cell activity. Cellular morphology after induction was observed. Immunofluorescence was conducted to detect the expression and location of nerve cell markers. Quantitative real-time PCR and Western blot analysis were performed to detect the mRNA and protein expression levels, respectively. The rhBMP-7 and Lv-BMP-7 promoted the proliferation of BMSCs, accompanied with increased ALP activities. Morphological observations revealed that rhBMP-7 and Lv-BMP-7 induced BMSCs to differentiate into neuron-like cells. Immunofluorescence revealed that the rhBMP-7 and Lv-BMP-7 groups showed positive expression of MAP-2 and Nfh in BMSCs. MAP-2 was mainly distributed in the cell body and cellular protrusion, while Nfh was mainly distributed in the cytoplasm and cell protrusion. Positive mRNA and protein expressions of MAP-2 and Nfh were observed in the cells of the rhBMP-7 and Lv-BMP-7 groups, and the expression levels were significantly higher than the control and empty groups. Both exogenous BMP-7 (rhBMP-7) and endogenous BMP-7 (Lv-BMP-7) can induce BMSCs to differentiate into neuron-like cells highly expressing the neuronal markers MAP-2 and Nfh.

Adaptive Real-Time Clustering Method for Dynamic Visual Tracking of Very Flexible Wings

Advancements in aircraft controller design, paired with increasingly flexible aircraft concepts, create the need for the development of novel (smart) adaptive sensing methods suitable for aeroelastic state estimation. A potentially universal and noninvasive approach is visual tracking. However, many tracking methods require manual selection of initial marker locations at the start of a tracking sequence. This study aims to address the gap by investigating a robust machine learning approach for unsupervised automatic labeling of visual markers. The method uses fast DBSCAN and adaptive image segmentation pipeline with hue-saturation-value color filter to extract and label the marker centers under the presence of marker failure. In a comparative study, the DBSCAN clustering performance is assessed against an alternative clustering method, the disjoint-set data structure. The segmentation-clustering pipeline with DBSCAN is capable of running real-time at 250 FPS on a single camera image sequence with a resolution of 1088×600 pixels. To increase robustness against noise, a novel formulation (the inverse DBSCAN, ) is introduced. This approach is validated on an experimental dataset collected from camera observations of a flexible wing undergoing gust excitations in a wind tunnel, demonstrating an excellent match with the ground truth obtained with a laser vibrometer measurement system.

Lr80: A new and widely effective source of leaf rust resistance of wheat for enhancing diversity of resistance among modern cultivars.

A new leaf rust resistance gene Lr80 was identified and closely linked markers were developed for its successful pyramiding with other marker-tagged genes to achieve durable control of leaf rust. Common wheat landrace Hango-2, collected in 2006 from the Himalayan area of Hango, District Kinnaur, in Himachal Pradesh, exhibited a very low infection type (IT;) at the seedling stage to all Indian Puccinia triticina (Pt) pathotypes, except the pathotype 5R9-7 which produced IT 3+. Genetic analysis based on Agra Local/Hango-2-derived F3 families indicated monogenic control of leaf rust resistance, and the underlying locus was temporarily named LrH2. Bulked segregant analysis using 303 simple sequence repeat (SSR) markers located LrH2 in the short arm of chromosome 2D. An additional set of 10 chromosome 2DS-specific markers showed polymorphism between the parents and these weremapped on the entire Agra Local/Hango-2 F3 population. LrH2 was flanked by markers cau96 (distally) and barc124 (proximally). The 90K Infinium SNP array was used to identify SNP markers linked with LrH2. Markers KASP_17425 and KASP_17148 showed association with LrH2. Comparison of seedling leaf rust response data and marker locations across different maps demonstrated the uniqueness of LrH2 and it was formally named Lr80. The Lr80-linked markers KASP_17425, KASP_17148 and barc124 amplified alleles/products different to Hango-2 in 82 Australian cultivars indicating their robustness for marker-assisted selection of this gene in wheat breeding programs.

Fiducial markers and their impact on ablation outcome for patients treated with MR-guided transurethral ablation (TULSA): a retrospective technical analysis

Objectives Fiducial markers improve accuracy in external beam radiation therapy (EBRT) for treatment of prostate cancer (PCa). However, many patients recur after EBRT necessitating additional treatment, such as MR-guided transurethral ultrasound ablation (TULSA). Residual markers may compromise TULSA through ultrasound field distortions and generation of local susceptibility artifacts. The objective was to investigate how markers affect the ablation outcome during clinical TULSA treatments. Subjects and methods A retrospective analysis was performed on nine patients with radiorecurrent PCa and residual markers who received TULSA. The MR susceptibility artifact was quantified as a function of marker type, size and orientation, in particular for thermometry. The spatial distribution of markers inside the prostate was recorded, and the resulting impact on the thermal dose was measured. The thermal dose measurements were directly compared to the residual enhancing prostatic tissue observed on the immediate and control post-TULSA contrast enhanced (CE) image. Results Successful thermal dose accumulation to the target boundary occurred for 14/20 (70%) of markers, confirmed with CE imaging. Gold markers situated simultaneously close to the urethra (≤12 mm) and far from the target boundary (≥13 mm) reduced the ultrasound depth of heating. Nitinol markers produced large, hypointense artifacts that disrupted thermometry and compromised treatment. Artifacts from gold markers were less pronounced, but when located near the target boundary, also affected treatment. Conclusion Marker composition, orientation and location inside the prostate can all potentially impact treatment outcome. Proper patient selection through detailed MRI screening is critical to ensure successful radiorecurrent PCa treatment outcomes with TULSA.

ПРЯМА МОВА У ГРЕЦЬКОМУ РОМАНІ І-ІІІ СТ.

The means of expression of direct speech in the Greek novel (Chariton, Longus, Achilles Tatius, Xenophon of Ephesus) are represented by both verbs, noun and pronominal phrases in which the semе “speech” is implied by a noun or context. The dominant means of introducing direct speech within them are verbs in personal and impersonal forms, which are divided into hyperonyms (λεγω, φημι) and hyponyms (βοαω, αποκρινομαι, κραζω, etc.). The latter also include verbs which in a certain context are close to speech verbs (γραφω, κλαιω). Mostly, direct speech is introduced by hyperonyms, which appear in approximately equal proportions. The studied texts reveal differences in the location of markers of direct speech depending on their nature, which are mainly presented in pre- and intraposition: hyperonyms are located at the beginning (λεγω) and inside (φημι) of direct speech, while hyponyms and noun phrases occupy a prepositional position. Dialogue parties are also characterized by the lack of explicit labeling of direct speech.

Tracking fiducial markers with discriminative correlation filters

In the last few years, squared fiducial markers have become a popular and efficient tool to solve monocular localization and tracking problems at a very low cost. Nevertheless, marker detection is affected by noise and blur: small camera movements may cause image blurriness that prevents marker detection.The contribution of this paper is two-fold. First, it proposes a novel approach for estimating the location of markers in images using a set of Discriminative Correlation Filters (DCF). The proposed method outperforms state-of-the-art methods for marker detection and standard DCFs in terms of speed, precision, and sensitivity. Our method is robust to blur and scales very well with image resolution, obtaining more than 200fps in HD images using a single CPU thread.As a second contribution, this paper proposes a method for camera localization with marker maps employing a predictive approach to detect visible markers with high precision, speed, and robustness to blurriness. The method has been compared to the state-of-the-art SLAM methods obtaining, better accuracy, sensitivity, and speed. The proposed approach is publicly available as part of the ArUco library.

Automated Polyaxial Screw Placement Using a Commercial-Robot-Based, Image-Guided Spine Surgery System

Robotic spine surgery systems, used for placing pedicle screws, have been in clinical use since 2004; however, these systems act only as a positioner for guide tubes, which the surgeon uses to manually advance tools to prepare the site and place hardware (e.g., pedicle screws). This article presents the development, operation, and evaluation of a new, commercial-robot-based, image-guided surgery system that automates the process of bone preparation and polyaxial screw placement. The system is based on the KUKA LBR iiwa 7-axis collaborative robot. Fiducial marker and screw locations are defined on a pre-operative CT image using the 3D Slicer open source image visualization platform. The system uses the robot’s internal localization system for registration, by touching fiducial markers in a hand-guiding mode. A rotary-motor end effector with exchangeable tools is used for both hole-drilling and screw placement. A novel single-motor based mechanism was developed for placing polyaxial pedicle screws. An accuracy test was performed by placing polyaxial screws in synthetic vertebrae which mimic the mechanical properties of human bone. In placing 10 screws, the entry point accuracy was 0.49 ± 0.17 mm and the destination point accuracy was 1.49 ± 0.46 mm. The results compare favorably to evaluations of commercial robotic spine surgery systems.

Hand-Held Stereovision System for Image Updating in Open Spine Surgery.

Image guidance in open spinal surgery is compromised by changes in spinal alignment between preoperative images and surgical positioning. We evaluated registration of stereo-views of the surgical field to compensate for vertebral alignment changes. To assess accuracy and efficiency of an optically tracked hand-held stereovision (HHS) system to acquire images of the exposed spine during surgery. Standard midline posterior approach exposed L1 to L6 in 6 cadaver porcine spines. Fiducial markers were placed on each vertebra as "ground truth" locations. Spines were positioned supine with accentuated lordosis, and preoperative computed tomography (pCT) was acquired. Spines were re-positioned in a neutral prone posture, and locations of fiducials were acquired with a tracked stylus. Intraoperative stereovision (iSV) images were acquired and 3-dimensional (3D) surfaces of the exposed spine were reconstructed. HHS accuracy was assessed in terms of distances between reconstructed fiducial marker locations and their tracked counterparts. Level-wise registrations aligned pCT with iSV to account for changes in spine posture. Accuracy of updated computed tomography (uCT) was assessed using fiducial markers and other landmarks. Acquisition time for each image pair was<1s. Mean reconstruction time was <1 s for each image pair using batch processing, and mean accuracy was 1.2±0.6 mm across 6 cases. Mean errors of uCT were 3.1±0.7 and 2.0±0.5 mm on the dorsal and ventral sides, respectively. Results suggest that a portable HHS system offers potential to acquire accurate image data from the surgical field to facilitate surgical navigation during open spine surgery.

First-in-Human Study with Eight Patients Using an Absorbable Vena Cava Filter for the Prevention of Pulmonary Embolism

PurposeTo prospectively evaluate the initial human experience with an absorbable vena cava filter designed for transient protection from pulmonary embolism (PE). Materials and MethodsThis was a prospective, single-arm, first-in-human study of 8 patients with elevated risk of venous thromboembolism (VTE). Seven absorbable IVC filters (made of polydioxanone that breaks down into H2O and CO2 in 6 mo) were placed prophylactically before orthopedic (n = 5) and gynecologic (n = 2) surgeries, and 1 was placed in a case of deep vein thrombosis. Subjects underwent CT cavography and abdominal radiography before and 5, 11, and 36 weeks after filter placement to assess filter migration, embolization, perforation, and caval thrombosis and/or stenosis. Potential PE was assessed immediately before and 5 weeks after filter placement by pulmonary CT angiography. ResultsNo symptomatic PE was reported throughout the study or detected at the planned 5-week follow-up. No filter migration was detected based on the fixed location of the radiopaque markers (attached to the stent section of the filter) relative to the vertebral bodies. No filter embolization or caval perforation was detected, and no caval stenosis was observed. Throughout the study, no filter-related adverse events were reported. ConclusionsImplantation of an absorbable vena cava filter in a limited number of human subjects resulted in 100% clinical success. One planned deployment was aborted as a result of stenotic pelvic veins, resulting in 89% technical success. No PE or filter-related adverse events were observed.

Analysis of the effects of technical marker location on kinematic analysis using a 4D body scanner

Analysis of the effects of technical marker location on kinematic analysis using a 4D body scanner

Bacterial Isolates from Bivalve Clams (Galatea paradoxa, Born 1778): Occurence, Multi-drug Resistance, Location of Antibiotic Resistance Marker and Plasmid Profiles

The occurrence of bacterial isolates in Galatea paradoxa (Born 1778) was determined using standard bacteriological method. The multi-drug resistance, location of antibiotic markers, plasmid DNA extraction and electrophoresis was determined by disc diffusion, acridine orange, TENS alkaline lysis and 0.8% agarose gel electrophoresis, respectively. Of the 63 bacterial isolates from G. paradoxa, Staphylococcus aureus and Streptococcus pyogenes had the highest and lowest percentage of occurrence with 40.0% and 5.0%, respectively. Escherichia coli was 25.0%, Pseudomonas aeruginosa (17.5%), Enterococcus spp and Salmonella spp (15.0%) each, Bacillus subtilis (12.5%), Klebsiella pneumoniae and Enterococcus faecalis (10.0%) each while Vibrio cholerae was (7.5%). The results showed Streptomycin and Ciprofloxacin as the most effective antibiotics against bacterial isolates from G. paradoxa. Bacillus subtilis and P. aeruginosa displayed 100% sensitivity to Streptomycin; Salmonella spp and E. faecalis were 100% sensitive to Augmentin. V. cholerae and S. pyogenes showed 100% resistance to Penicillin and Rifampicin, respectively. Of the 63 bacterial isolates, 43 (68.3%) were multidrug resistant (MDR) isolates, of which S. aureus and E. coli had the widest multiple antibiotic resistance (MAR) indices ranging from 0.3 to 0.8, while S. pyogenes had the least MAR ≤ 0.5. Of the 43 MDR bacterial isolates, 16.3%, 23.3% and 60.5% had their entire antibiotic resistance encoded on plasmid, chromosome and both plasmid and chromosome, respectively. The agarose gel electrophoresis showed that MDR bacterial isolates from G. paradoxa had plasmid DNA with molecular weights ranging from 23.1 to 31.5kb. This study has showed that G. paradoxa harboured bacteria which could pose serious health risks and G. paradoxa should be adequately cooked before consumption.

Abstract 3267: Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma

Abstract The role of immune checkpoint inhibitors (ICPIs) in ovarian cancer continues to be refined. The presence of intratumoral T cells in ovarian tumors correlates with improved survival and progression, suggesting that immune modulation, such as by ICPIs, may be beneficial. However, a better understanding of the immune effects following ICPI use, particularly in those with a long progression free survival, is needed. Thus, we used imaging mass cytometry (IMC) to compare the tumor immune landscape of patients with ovarian cancer before and after a CTLA4 immune checkpoint inhibitor treatment to determine the association between alterations in immune landscapes and progression free survival. Fine needle biopsies were obtained from 8 patients with recurrent platinum-resistant ovarian carcinoma enrolled in a phase 2 randomized trial evaluating the efficacy of Tremelimumab and Durvalumab (CTLA4 and PDL1 checkpoint inhibitors, respectively) in recurrent ovarian cancer treatment. Each patient had a pre-treatment biopsy and on-treatment biopsy after 3 cycles of CTLA4 inhibitor therapy. Progression free time (PFS) was recorded with 3 patients with a long PFS (&amp;gt;180 days) and 5 with short PFS (&amp;lt;60 days). Formalin fixed paraffin embedded (FFPE) tissue sections were stained for IMC analysis via Fluidigm protocol with 34 metal-tagged antibodies to detect various cell and immune related markers. The IMC data was obtained using the Fluidigm Helios CyTOF instrument and Hyperion Imaging System laser ablation module. A novel image informatics pipeline through Matlab was used to assess the image intensity of each marker and cell location. Using the developed image informatics pipeline, cell types and locations were analyzed for 16 samples from 8 patients. In all patients, mean CD8+ T cell densities had an increased trend in on-treatment vs pre-treatment samples (205.6 v 129.9 cells/mm2, p=0.086). An analysis of cell location found that in all patients on-treatment, the mean number of CD8+ T cells adjacent to M2 macrophages increased significantly (0.09 v. 0.17 cells, p = 0.0460) as well as the mean number of CD8+ T cells adjacent to B7H4+ tumor cells (0.035 v. 0.01 cells, p = 0.046). Furthermore, patients with a long PFS had a significantly higher number of CD8+ cells neighboring B cells on-treatment than short PFS (0.12 v. 0.27 cells, p=0.028). Using IMC and novel image informatics pipeline, we found that patients with recurrent ovarian cancer treated with Tremelimumab with a long PFS mounted a significant immune response compared to patients with a short PFS, with a higher number of CD8+ T cells neighboring B cells after treatment. For all patients, the immune landscape altered after treatment. To our knowledge, this is the first known use of IMC to demonstrate immune response in ovarian cancer following ICPI therapy. Overall, IMC and image informatics pipeline are robust tools that simultaneously analyze multiple biomarkers and spatial location of cells to better assess the tumor immune microenvironment and cellular interactions. Citation Format: Han Cun, Emily M. Hinchcliff, Ying Zhu, Sammy Ferri-Borgogno, Rita Cheng, Jared K. Burks, Stephen T. Wong, Amir A. Jazaeri, Samuel C. Mok. Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3267.

Numerical and Experimental Evaluation of Magnetic Markers for Localized Tumor Excision With a Handheld Magnetic Probe

For patients with nonpalpable breast lesions, breast-conserving surgery can be performed to remove the primary lesion while leaving as much normal breast tissue as possible. To perform breast-conserving surgery, localization tools are required to indicate such lesions' location. Conventional localization tools such as wire-guided localization (WGL) lead to a high reexcision rate. A magnetic detection system reduces the reexcision rate by providing objective information about the marker's location. In this study, we numerically evaluated the induced magnetic field strength from the magnetic marker from all orientations and found an optimal design achieving 100% detection at 40 mm distance from all orientations. Two marker samples are fabricated, and the experimentally detectable magnetic field strength is compared with the numerical simulation results. Both data show similar trends, thus validating the numerical simulation. The application of premagnetization on the magnetic markers are also evaluated. With the use of premagnetization, magnetic markers with 0.6 mm diameter can be detected in 46 mm distance, exceeding existing commercialized magnetic markers.

Ultrasound visibility of select breast biopsy markers for targeted axillary node localization following neoadjuvant treatment: simulation using animal tissue models.

To compare ultrasound visibility of selected biopsy markers in animal tissue models simulating axillary echotexture. Four breast biopsy markers were selected based on size, shape, and composition and compared to an institutional standard for testing in beef steak and pork loin phantoms. BD® UltraCor™ Twirl™; Hologic® Tumark® Professional series Q, Vision, and X; and BD® UltraClip™ Dual Trigger wing-shaped (institutional standard) biopsy markers were deployed at superficial (0-2.0cm) and deep (2.1-4.0cm) depths in the animal models. An animal model without a biopsy marker served as control. Four participating breast imagers blinded to marker shape and location assessed ultrasound visibility of each biopsy marker using a handheld 5-12MHz linear array transducer with a 4-point grading system (0, not visible; 1, unsure if visible; 2, visible with difficulty; 3, definite visibility). Each breast imager was asked to select the three most easily visualized biopsy markers. Total visibility scores with the four-point grading system demonstrate highest score for the Twirl™ (48/48 points), followed by the Tumark® Q (42/48) and Tumark® Vision (41/48) biopsy markers. Overall individual accuracy scores across all biopsy marker types ranged from 83.3 to 95.8%. Visibility scores based on subjective radiologist assessment also demonstrate the highest vote for the Twirl™ (11), followed by the Tumark® Vision (7) and Tumark® Q (6) biopsy markers. The wing-shaped biopsy marker had the lowest visibility and voter score. The Twirl™ followed by the Tumark® Q and Vision biopsy markers demonstrates the highest visibility scores using a four-point grading system and by radiologist vote.

Quantification and correction of distortion in diffusion-weighted MRI at 1.5 and 3 T in a muscle-invasive bladder cancer phantom for radiotherapy planning

Limited visibility of post-resection muscle-invasive bladder cancer (MIBC) on CT hinders radiotherapy dose escalation of the residual tumour. Diffusion-weighted MRI (DW-MRI) visualises areas of high tumour burden and is increasingly used within diagnosis and as a biomarker for cancer. DW-MRI could, therefore, facilitate dose escalation, potentially via dose-painting and/or accommodating response. However, the distortion inherent in DW-MRI could limit geometric accuracy. Therefore, this study aims to quantify DW-MRI distortion via imaging of a bladder phantom. A phantom was designed to mimic MIBC and imaged using CT, DW-MRI and T2W-MRI. Fiducial marker locations were compared across modalities and publicly available software was assessed for correction of magnetic susceptibility-related distortion. Fiducial marker locations on CT and T2W-MRI agreed within 1.2 mm at 3 T and 1.8 mm at 1.5 T. The greatest discrepancy between CT and apparent diffusion coefficient (ADC) maps was 6.3 mm at 3 T, reducing to 1.8 mm when corrected for distortion. At 1.5 T, these values were 3.9 mm and 1.7 mm, respectively. Geometric distortion in DW-MRI of a model bladder was initially >6 mm at 3 T and >3 mm at 1.5 T; however, established correction methods reduced this to <2 mm in both cases. A phantom designed to mimic MIBC has been produced and used to show distortion in DW-MRI can be sufficiently mitigated for incorporation into the radiotherapy pathway. Further investigation is therefore warranted to enable individually adaptive image-guided radiotherapy of MIBC based upon DW-MRI.

55 Mn-based fiducial markers for rapid and automated RF coil localization for hyperpolarized 13 C MRI.

To use fiducial markers containing manganese 55 to rapidly localize carbon 13 (13 C) RF coils for correcting images for B1 variation. Hollow high-density polyethylene spheres were filled with 3M sodium permanganate and affixed to a rectangular 13 C-tuned RF coil. The relative positions of the markers and coil conductors were mapped using CT. Marker positions were measured by MRI using a series of 1D projections and automated peak detection. Once the coil location was determined, coil sensitivity was estimated using a quasi-static calculation. Simulations were performed to determine the minimum number of projections required for robust localization. Phantom experiments were used to confirm the accuracy of marker localization as well as the calculated coil sensitivity. Finally, in vivo validation was performed using hyperpolarized 13 C pyruvate in a rat model. In simulations, our algorithm was accurate in determining marker positions when at least 6 projections were used (RMSE 1.4 ± 0.9 mm). These estimates were verified in phantom experiments, where markers locations were determined with an RMS accuracy of 1.3 mm. A minimum SNR of 4 was required for automated detection to perform accurately. Computed coil sensitivity had a median error of 17% when taken over the entire measured area and 5.7% over a central region. In a rat, correction for nonuniform reception and flip angle was able to normalize the signals arising from asymmetrically positioned kidneys. Manganese 55 fiducial markers are an inexpensive and reliable method for rapidly localizing 13 C RF coils and correcting 13 C images for B1 variation without user intervention.