Consecutive Scans Research Articles

Modified ICP based Framework for 3D Localization and Mapping in GNSS-denied Environments using LiDAR

Abstract. Lidar odometry and mapping has emerged as fundamental technology in various fields, including accurate positioning and mapping, autonomous vehicles, robotics, and environmental monitoring. The ability to create accurate maps and calculate trajectories is essential for localization and navigation in complex environments, particularly in scenarios where GNSS signal are unavailable. In this context, we propose a novel method for simultaneous localization and mapping (SLAM) specifically designed for GNSS-denied environments and without the need for high-accuracy ranging or inertial measurement units (IMUs). Our approach aims to address the challenges posed by GNSS-denied environments and the cost constraints associated with using multiple sensors. By using only lidar sensors, specifically the Velodyne VLP 16 sensor, we offer a cost-effective solution. Our method utilizes a modified version of the Iterative Closest Point (ICP) algorithm to handle consecutive lidar scans seamlessly. In addition to our method, we conducted thorough accuracy assessments on the created map. The reason behind extensive accuracy evaluation is to ensure the quality of registration. By comparing alignment between the features of different frames within the map and determining the error between the registered features and the original, we gain a more comprehensive understanding of registration quality.

Detecting Indoor Tiny Autonomous Malicious Drones within Critical Infrastructures: An Innovative Algorithm based on Harmonic Radar-Equipped Mini-Drones

Critical infrastructures play a central role in the welfare of contemporary societies and they should properly function 24/7. Since their role is so important, they regularly become targets of malicious parties, terrorists, industrial spies, and even hostile governments. In this paper, the scenario of cyber or physical attacks to CIs from tiny autonomous malicious drones is analyzed. In particular, this work focuses on indoor spaces, protected by mini-drones. The mini-drones are equipped with harmonic radar and run a novel algorithm, which guides them to scan the whole area. Assuming that the malicious drones behave as non-linear systems, the mini-drones transmit signals and analyze the received signals, creating a non-linear system 3D location map for the whole space. In the consecutive scans, any changes on the 3D location map indicate that the malicious drone has changed location. Simulated results and comparisons to state-of-the-art approaches exhibit the cost-effectiveness and time efficiency of the proposed scheme as well as its limitations.

Slowly expanding lesions are associated with disease activity and gray matter loss in relapse-onset multiple sclerosis.

Slowly expanding lesions (SELs) have been proposed as novel MRI markers of chronic active lesions in multiple sclerosis (MS). However, the mechanism through which SELs affect brain volume loss in patients with MS remains unknown. Additionally, the prevalence and significance of SELs in Asian patients with MS remain unclear. This study aimed to investigate the association between SELs and no evidence of disease activity (NEDA)-3 status as well as brain volume loss in Japanese patients. A total of 99 patients with relapse-onset MS were retrospectively evaluated. SELs were identified on brain MRI based on local deformation when consecutive scans were registered longitudinally. We developed a logistic regression model and generalized linear mixed models (GLMMs) to evaluate the association between the number of SELs and disease activity and changes in brain volume. During the observation period (2.0±0.22years), 35 patients developed at least one SEL. Multivariable logistic regression analysis showed that ≥2 SELs were associated with 0.2 times the risk of achieving a NEDA-3 status. GLMMs revealed that the number of SELs was negatively associated with volume changes in the cortex (p=.00169) and subcortical gray matter (p=.00964) after correction for multiple comparisons. SELs were identified in Japanese patients with MS during the 2-year observation period. The number of SELs is associated with disease activity and brain volume loss, suggesting that the number of SELs could be a biomarker of disease activity in MS.

Routine Use of [64Cu]Cu-DOTATATE PET/CT in a Neuroendocrine Tumor Center: Referral Patterns and Image Results of 2,249 Consecutive Scans.

The role of somatostatin receptor (SSTR) PET/CT, using 68Ga-based tracers or [64Cu]Cu-DOTATATE (64Cu-DOTATATE), in the management of patients with neuroendocrine neoplasm (NEN) is guided by appropriate use criteria (AUC). In this study, we performed systematic analyses of referral patterns and image findings of routine 64Cu-DOTATATE PET/CT scans to support AUC development. Methods: We included all clinical routine 64Cu-DOTATATE PET/CT scans performed between April 10, 2018 (start of clinical use), and May 2, 2022, at Copenhagen University Hospital-Rigshospitalet. We reviewed the referral text and image report of each scan and classified the indication according to clinical scenarios as listed in the AUC. Results: In total, 1,290 patients underwent 2,249 64Cu-DOTATATE PET/CT scans. Monitoring of patients with NEN seen both on conventional imaging and on SSTR PET without clinical evidence of progression was the most common indication (defined as "may be appropriate" in the AUC) and accounted for 703 (31.3%) scans. Initial staging after NEN diagnosis ("appropriate" in the AUC) and restaging after curative-intent surgery ("may be appropriate" in the AUC) accounted for 221 (9.8%) and 241 (10.7%) scans, respectively. Selection of patients eligible for peptide receptor radionuclide therapy ("appropriate" in the AUC) and restaging after peptide receptor radionuclide therapy completion ("appropriate" in the AUC) accounted for 95 (4.2%) and 115 (5.1%) scans, respectively. The number of scans performed for indications not defined in the AUC was 371 (16.5%). Image result analysis revealed no disease in 669 scans (29.7%), stable disease in 582 (25.9%), and progression in 461 (20.5%). In 99 of the 461 (21.5%) scans, progression was detected on PET but not on CT. Conclusion: Our study provided real-life data that may contribute to support development of 64Cu-DOTATATE/SSTR PET/CT guidelines including AUC. Some scenarios listed as "may be appropriate" in the current AUC were frequent in our data. Monitoring of patients with NEN without clinical evidence of progression was the most frequent indication for 64Cu-DOTATATE PET/CT, in which disease progression was detected in more than one third, and a large proportion was visible by PET only. We therefore conclude that this scenario could potentially be classified as appropriate.

Fast vs slow rubidium-82 infusion profiles and test-retest precision of myocardial perfusion using contemporary 3D cardiac analog PET-CT imaging.

BackgroundOn legacy 2D PET systems utilizing a 50 mL/min Rb-82 profile, test-retest precision of quantitative perfusion is ∼10%. It is unclear whether Rb-82 infusion rate significantly impacts quantitative perfusion and/or image quality on modern analog 3D PET-CT systems. We aimed to determine whether the Rb-82 infusion profile significantly impacts test-retest precision of quantitative perfusion, perfusion metrics, and/or image quality on a modern analog 3D PET-CT scanner. MethodsNinety-eight volunteers from 3 distinct groups: healthy volunteers (Normals), patients with risk factors and/or coronary disease (Clinicals) and patients with prior transmural myocardial infarctions (Infarcts), underwent cardiac stress testing on an analog 3D PET-CT. Participants received 3 consecutive resting scans and 2 consecutive stress scans, minutes apart, with two randomly assigned Rb-82 infusion profiles: 50 mL/min (fast [F]) and 20 mL/min (slow [S]). Perfusion metrics (resting (rMBF) and stress myocardial blood flow (sMBF)) were calculated using HeartSee software. Coefficients of variance (COV), repeatability (RC), MBF and image quality metrics were compared. ResultsrMBF correlated well between F and S profiles, with intraclass correlation coefficients (ICC) ranging 0.91-0.93. sMBF was highly correlated between F and S profiles (ICC=0.97). Fast and slow profiles were associated with similar same-day test-retest precision (COV 11.5% vs. 11.3% (p=0.77); RC 21.5% vs. 22.6%, for F-F vs S-S). There were no clinically significant differences in MBF values between F and S profiles. Image quality metrics were similar between the 2 profiles. ConclusionsThere are no clinically significant differences in precision, perfusion metrics or image quality between Rb-82 fast and slow infusions using a contemporary analog 3D PET-CT.

A Multidisciplinary Assessment of Standard Low Dose Versus Ultra-Low Dose Chest CT Scans For Pectus Excavatum Imaging

AimEvaluation of ultra-low dose chest CT imaging for the assessment of pectus excavatum severity as determined by pediatric radiologists and pediatric surgeons using Haller (HI) and Correction indices (CI). MethodsA single institution, prospective evaluation of patients being evaluated for pectus excavatum were scanned with a standard low-dose chest CT protocol (CARE) followed by a consecutive ultra-low dose CT scan (ULTRA). 3 surgeons and 4 radiologists were instructed to determine HI and CI in each series. The Intraclass Correlation Coefficient (ICC) was used to calculate the agreement level between CARE and ULTRA. Bland-Altman (BA) and scatter plots were also performed to determine bias of each approach. Results32 patients had CARE and ULTRA consecutively. The ICC for HI demonstrated good reliability with a value of 0.89 and excellent reliability for CI with a value of 0.91. The reliability for HI was greater in the surgeon group (0.89) compared to the radiologist group (0.88). The reliability for CI was greater in the radiologist group (0.92) compared to the surgeon group (0.90). The Bland Altman plots for the HI and CI demonstrate no consistent bias for CARE or ULTRA approach when evaluating HI and CI. ConclusionUltra-low dose CT scan imaging compared to standard low-dose CT appears to be a reliable alternative for evaluating PE severity as assessed by HI and CI. This work supports the evaluation and potential development of a standardized CT imaging protocol capable of reducing radiation exposure without sacrificing imaging for PE patients. Level of evidence2

DXA In People Living With HIV

Abstract Background As people with HIV now live a near normal life-span, prevention of fractures is increasingly important. Alongside conventional risk factors for fractures, antiretrovirals and chronic inflammation are believed to contribute to their increased fracture risk compared to the general population. Methods We audited a 1-year series of consecutive DXA scans conducted on people living with HIV vs the European AIDS Clinical Society guidelines on bone health. These guidelines specify indications for DXA, for repeat DXA and for osteoporosis treatment. We recorded DXA results, any prior DXA, fracture history, fracture risks and drug treatment history. We assessed frequency of scanning and pharmacological management of low bone mass vs. guidelines. Results N=90 referred for DXA, of whom 18% did not attend, leaving n=74; 58% female, 42% male, median age 52 years [36-64] and 56 years [49-69] respectively. Of the 18% (n=14) who were aged under 50, 43% had no clear indication (fracture risk factor) for DXA. Of those aged >50 years (n=60), all scans were indicated as the guidelines advises this in those aged >50 years. Bone density was normal in n=32 (43%), osteopenic in 36 (49%) and osteoporotic in 7 (9%). Fifteen percent overall had a fragility fracture history, none of whom were taking osteoporosis treatment though it was indicated in at least 4 based on their DXA result. N=12 (16%) had a DXA in preceding years, and just 2 of the repeat scans were indicated according to guidelines. For the 12 with serial scans, there was no significant change in T score after a median three-year period. Conclusion Through an audit of consecutive DXA referrals, rather than consecutive individuals, low bone mass and fragility fractures are prevalent in people living with HIV. With advancing age, fracture incidence may rise sizeable in this group therefore due attention to bone health guidelines in required.

ESTUDIO DE LA RESPUESTA I-V EN CELDAS DE MEMORIA DESb70Te30

Chalcogenide glasses are within the group of phase change materials and are promising in their application to non-volatile electronic memories. Under electrical pulses, they can circulate between two amorphous and crystalline structural states that are well differentiated in their conductivity. Assuming that the phase change mechanisms depend on the energy per unit volume delivered to the sensitive material, it is desirable to build cells on a micrometer scale, also considering that they could eventually be integrated into microelectronic manufacturing processes. In a previous work, we observed an abrupt decrease in the resistance of Sb70Te30base thin films deposited by laser ablation in a temperature range of approximately 445 K when the sample is heated at low rates. From the results of differential scanning calorimetry and X-ray diffraction on samples obtained by the same method, we associate the change in resistivity with the crystallization process. In this work, we build micrometric devices with rectangular surface with Sb70Te30assensitive material, deposited on coplanar electrodes with spacing L (8 and 16μm) and width W (4, 8, 16, 32 and 64μm). We measure the voltage response of the devices when excited by scanning of increasing current and, between consecutive scanning, we measure the remaining resistance by applying a constant voltage value. In curves I-V, we identify a transformation from the original state to one of lower resistance, attributable to crystallization, but it was not possible to perform the reverse transformation to a state of higher resistance. Starting from the lack of knowledge about the conductivity of the material, we simulate the electric field in the cell using the Finite Element Method. The electrical conductivity of the chalcogenide glass in its initial state (amorphous) was estimated by adjusting its value in the simulations with different geometries, minimizing the difference between the measured and simulated resistances.

In Vivo visualization of white matter fiber tracts in the brainstem using low flip angle double echo 3D gradient echo imaging at 3T

BackgroundWhite matter (WM) fiber tracts in the brainstem communicate with various regions in the cerebrum, cerebellum, and spinal cord. Clinically, small lesions, malformations, or histopathological changes in the brainstem can cause severe neurological disorders. A direct and non-invasive assessment approach could bring valuable information about the intricate anatomical variations of the white matter fiber tracts and nuclei. Although tractography from diffusion tensor imaging has been commonly used to map the WM fiber tracts connectivity, it is difficult to differentiate the complex WM tracts anatomically. Both high field MRI methods and ultrahigh-field MRI methods at 7T and 11.7 T have been used to enhance the contrast of WM fiber tracts. Despite their promising results, it is still challenging to achieve wide clinical adoption at 3T. In this study, we explored a clinically feasible method using a proton density weighted (PDW) 3D gradient echo (GRE) sequence to directly image the WM fiber tracts in the brainstem at 3T in vivo. MethodsWe optimized a 3D high resolution, double echo, short TR, PDW GRE sequence on 5 healthy volunteers using a clinical 3T scanner to visualize the complicated anatomy of WM fiber tracts in the brain stem. Tissue properties including T1, proton density and T2* from in vivo quantitative MRI data were used for simulations to determine the optimal flip angle for the sequence. The visualization of multiple WM fiber tracts in the brainstem was assessed qualitatively and quantitatively using relative contrast and contrast-to-noise ratio (CNR). To improve the CNR, the final images were created by averaging over all echoes from two consecutive scans at the optimal flip angle. The results were compared to anatomical atlases and histology sections to identify the major fiber tracts. All the identified major fiber tracts were labeled on axial, sagittal and coronal slices. ResultsThe WM fiber tracts were found to have distinct hypointense signal throughout the brainstem and most of the major WM fiber tracts, such as the corticospinal tract, medial lemniscus, medial longitudinal fasciculus, and central tegmental tract, in the brainstem up to and including the thalamus were identified in all subjects. Both qualitative and quantitative evaluations showed that the 3° scan offered the best contrast for WM fiber tracts for a TR of 20 ms. The average over the first two echo times and two consecutive 3° scans gave a CNR of 47.8 ± 6.2 for the pyramidal tracts in particular and CNRs values greater than 6.5 ± 2.4 for the rest of the fiber tracts. ConclusionsAll the major fiber tracts in the brainstem could be visualized. Given the reasonably short scan time of 10 min at 3T, double echo PDW GRE sequence is a very practical approach for clinical adoption.

Culture system for longitudinal monitoring of bone dynamics ex vivo.

To quantify and visualize both bone formation and resorption within osteochondral explants cultured ex vivo is challenging with the current analysis techniques. An approach that enables monitoring of bone remodeling dynamics is longitudinal microcomputed tomography (µCT), a non-destructive technique that relies on repeated µCT scanning and subsequent registration of consecutive scans. In this study, a two-compartment culture system suitable for osteochondral explants that allowed for µCT scanning during ex vivo culture was established. Explants were scanned repeatedly in a fixed orientation, which allowed assessment of bone remodeling due to adequate image registration. Using this method, bone formation was found to be restricted to the outer surfaces when cultured statically. To demonstrate that the culture system could capture differences in bone remodeling, explants were cultured statically and under dynamic compression as loading promotes osteogenesis. No quantitative differences between static and dynamic culture were revealed. Still, only in dynamic conditions, bone formation was visualized on trabecular surfaces located within the inner cores, suggesting enhanced bone formation towards the center of the explants upon mechanical loading. Taken together, the ex vivo culture system in combination with longitudinal µCT scanning and subsequent registration of images demonstrated potential for evaluating bone remodeling within explants.

A comparison of white-to-white measurements obtained by Anterion AS-OCT versus three optical devices in refractive surgery candidates.

To assess the agreement between Anterion AS-OCT and three optical devices in measuring the white-to-white (WTW) diameter in candidates for refractive surgery. In this cross-sectional prospective study, 129 right eyes of 129 normal individuals underwent consecutive scans with the Anterion, the Pentacam AXL, the IOLMaster 700, and the Orbscan IIz. Mean difference (MD), 95% limits of agreement (LoA), and concordance correlation coefficient (CCC) were calculated to assess agreement and interchangeability. The mean age of participants was 30.4 ± 5.9 (range: 21-47) years. The mean WTW distance measured by the different instruments was as follows: 12.00 ± 0.42 mm (range, 10.57 to 13.05) using the Anterion, 11.87 ± 0.34 (11.10 to 12.80) using the Pentacam, 12.12 ± 0.44 (11.00 to 13.30) using the IOLMaster, and 11.73 ± 0.37 (11.00 to 13.10) using the Orbscan. The MD and 95% LoA for Anterion vs. Pentacam, IOLMaster, or Orbscan were [0.11; -0.31 to 0.54 mm], [-0.13; -0.93 to 0.66], and [0.25; -0.28 to 0.78], respectively. The corresponding CCCs were 0.803, 0.514, and 0.631. This study found weak agreement between Anterion and Pentacam AXL, IOLMaster 700, and Orbscan IIz devices regarding WTW distance measurements in refractive surgery candidates. Therefore, it is not recommended to use Anterion's WTW measurements interchangeably with the other three devices, particularly for phakic intraocular lens sizing.

Types of high-riding vertebral artery: a classification system for preoperative planning of C2 instrumentation based on 908 potential screw insertion sites

BACKGROUND CONTEXTOur recent studies indicated that a high-riding vertebral artery (HRVA) is a common variant posing a risk of injuring the vessel during C2 instrumentation. However, several different types fit in the current definition of HRVA, which may require a different strategy for C2 screw placement. PURPOSETo classify HRVA and provide a clinical aid for preoperative planning of C2 instrumentation. A secondary goal was to estimate coexistence of each HRVA type with the ipsilateral narrow C2 pedicle (NP). STUDY DESIGNA retrospective observational study involving radiologic measurements of the estimated number of anonymized cervical computed tomography (CT) scans. STROBE checklist was applied. PATIENT SAMPLEA total of 908 potential screw insertion sites (PSIS) of 454 consecutive cervical CT scans were analyzed. The sample size was estimated using ScalaR SP function in RStudio. OUTCOME MEASURESThree types of HRVA based on a series of C2 vertebral morphological parameters including the C2 isthmus height (C2IsH) and C2 internal height (C2InH). Also, the prevalences of each HRVA type and coexisting NP based on the C2 pedicle width (C2PW). METHODSHRVA was defined as C2IsH of ≤5 mm and/or C2InH of ≤2 mm measured 3 mm lateral to the lateral border of the spinal canal. A narrow pedicle was defined as C2PW of ≤4 mm. Measurements were done using Syn.govia software. Interobserver, intraobserver, and inter-software agreement coefficients for C2IsH, C2InH, and C2PW parameters were adopted from our previous study. K-means cluster analysis was applied. RESULTSPrevalence of at least 1 HRVA was 24.9% (n=113 subjects) and 16.2% of PSIS (n=147 sites). Based on the measurements and K-means clustering, the following 3 types of HRVA have been distinguished: type 1—isthmic with only C2IsH being reduced and normal C2InH; type 2—internal with only C2InH being reduced and C2IsH within normal limits; type 3—isthmo-internal with both C2IsH and C2InH being reduced. Kruskal-Wallis test followed by unadjusted and Bonferroni-adjusted post-hoc multiple comparison analysis detected significant differences across the types. The prevalences of the newly identified types were as follows: 78.2%, 8.8%, and 12.9% for type 1, type 2, and type 3, respectively. 73.9% of type 1 HRVA, 53.8% of type 2 HRVA, and 100% of type 3 HRVA had a concomitant ipsilateral NP. Prediction of the HRVA types by the K-means clustering has been evaluated. Screw placement techniques for each type are proposed and discussed. CONCLUSIONWe present the first classification system for the high-riding vertebral artery distinguishing 3 types based on the large homogenous cohort, which may serve as an adjunct to preoperative planning of C2 instrumentation. External validation of this classification scheme shall determine its further clinical utility.

Body mass index associated with respiration predicts motion in resting-state functional magnetic resonance imaging scans.

Decreasing body mass index (BMI) reduces head motion in resting-state fMRI (rs-fMRI) data. Yet, the mechanism by which BMI affects head motion remains poorly understood. Understanding how BMI interacts with respiration to affect head motion can improve head motion reduction strategies. A total of 254 patients with back pain were included in this study, each of whom had two visits (interval time = 13.85 ± 7.81 weeks) during which two consecutive re-fMRI scans were obtained. We investigated the relationships between head motion and demographic and pain-related characteristics-head motion was reliable across scans and correlated with age, pain intensity, and BMI. Multiple linear regression models determined that BMI was the main determinant in predicting head motion. BMI was also associated with two features derived from respiration signal. Anterior-posterior and superior-inferior motion dominated both overall motion magnitude and the coupling between motion and respiration. BMI interacted with respiration to influence motion only in the pitch dimension. These findings indicate that BMI should be a critical parameter in both study designs and analyses of fMRI data.

Image plate multi-scan response to fusion protons in the range of 1-14 MeV.

Image plates (IPs) are a quickly recoverable and reusable radiation detector often used to measure proton and x-ray fluence in laser-driven experiments. Recently, IPs have been used in a proton radiography detector stack on the OMEGA laser, a diagnostic historically implemented with CR-39, or radiochromic film. The IPs used in this and other diagnostics detect charged particles, neutrons, and x-rays indiscriminately. IPs detect radiation using a photo-stimulated luminescence (PSL) material, often phosphor, in which electrons are excited to metastable states by ionizing radiation. Protons at MeV energies deposit energy deeper into the IP compared with x rays below ∼20keV due to the Bragg peak present for protons. This property is exploited to discriminate between radiation types. Doses of mono-energetic protons between 1.7 and 14MeV are applied to IPs using the MIT linear electrostatic ion accelerator. This paper presents the results from consecutive scans of IPs irradiated with different proton energies. The PSL ratios between subsequent scans are shown to depend on proton energy, with higher energy protons having lower PSL ratios for each scan. This finding is separate from the known energy dependence in the absolute sensitivity of IPs. The results can be compared to complimentary work on x rays, showing a difference between protons and x rays, forging a path to discriminate between proton and x-ray fluence in mixed radiation environments.

Comparison of Automated and Manual Measurement of Corneal Epithelial Thickness in Eyes With Limbal Stem Cell Deficiency.

The purpose of this study was to compare the outcomes of manual and automated corneal epithelial thickness (CET) assessments using anterior segment optical coherence tomography in eyes with limbal stem cell deficiency (LSCD). Eighty-seven eyes from 64 patients with LSCD and 65 eyes from 39 healthy subjects were included in this cross-sectional study. OCT images of corneas were acquired using a Fourier-domain anterior segment optical coherence tomography. The automated measurement of CET was obtained using the manufacturer's program and the manual measurements were obtained by 2 masked observers. The average CET was obtained from 3 consecutive epithelial profile maps. The average CET of manual measurement was obtained from 3 consecutive cross-line scans using 3-point measurement as previously described. The central CET was thinner in patients with LSCD compared with healthy individuals by both manual and automated measurements. Automated CET measurements were similar to the manually obtained CET in the healthy controls (r = 0.911). However, there is a lower correlation between the automated and manually obtained CET in the LSCD group (r = 0.497). Manual measurements of CET (39.8 ± 11 μm) in eyes with LSCD were significantly lower than the automated measurements (48.8 ± 7.2 μm, P = 0.001, 95% CI -11.0 to -6.9). The correlations between the automated and manually obtained measurements in the mild, moderate, and severe stages of LSCD were 0.623, 0.632, and 0.378, respectively. There is a large discrepancy between the manual and automated measurements in eyes with LSCD but not in normal eyes. Automated measurements in LSCD exhibited a higher rate of errors and nonuniform measurements due to the presence of subepithelial scars. Automated CET measurements appear to be unreliable in eyes with corneal scars in LSCD.

Bacterial reduction and temperature increase of titanium dental implant models treated with a 445 nm diode laser: an in vitro study

In this in vitro study, the use of a 445 nm diode laser was investigated for the decontamination of titanium dental implants. Different irradiation protocols and the effect of repetitive laser irradiation on temperature increase and decontamination efficacy were evaluated on titanium implant models. An automated setup was developed to realize a scanning procedure for a full surface irradiation to recapitulate a clinical treatment. Three irradiation parameter sets A (continuous wave, power 0.8 W, duty cycle (DC) 100%, and 5 s), B (pulsed mode, DC 50%, power 1.0 W, and 10 s), and C (pulsed mode, DC 10%, power 3.0 W, and 20 s) were used to treat the rods for up to ten consecutive scans. The resulting temperature increase was measured by a thermal imaging camera and the decontamination efficacy of the procedures was evaluated against Escherichia coli and Staphylococcus aureus, and correlated with the applied laser fluence. An implant’s temperature increase of 10 °C was set as the limit accepted in literature to avoid thermal damage to the surrounding tissue in vivo. Repeated irradiation of the specimens resulted in a steady increase in temperature. Parameter sets A and B caused a temperature increase of 11.27 ± 0.81 °C and 9.90 ± 0.37 °C after five consecutive laser scans, respectively, while parameter set C resulted in a temperature increase of only 8.20 ± 0.53 °C after ten surface scans. The microbiological study showed that all irradiation parameter sets achieved a complete bacterial reduction (99.9999% or 6-log10) after ten consecutive scans, however only parameter set C did not exceed the temperature threshold. A 445 nm diode laser can be used to decontaminate dental titanium rods, and repeated laser irradiation of the contaminated areas increases the antimicrobial effect of the treatment; however, the correct choice of parameters is needed to provide adequate laser fluence while preventing an implant’s temperature increase that could cause damage to the surrounding tissue.

Evaluation of treatment response with serial CT in patients with non-tuberculous mycobacterial pulmonary disease.

In patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD), the response to treatment is evaluated based on microbiological, clinical, and radiological data. However, little is known about the dynamics of CT findings. The aim of this study was to evaluate CT changes in NTM-PD in order to define radiological criteria for treatment success. Retrospective multicenter study (Hannover, Heidelberg, Gauting). Sixty patients with NTM-PD and at least two consecutive CT scans were included. Scoring for NTM-PD was performed by evaluating variables of bronchiectasis, mucus plugging, bronchiolitis, cavities, nodules, and consolidations on an ordinal scale from 0 to 3. Differences between baseline and follow-up were calculated, and patients with/without cultural conversion were compared using the Mann-Whitney U-test. For paired comparison of the two consecutive CT scans the Wilcoxon test was used. Comparing patients with and without culture conversion, there were significant differences in temporal changes of bronchiectasis (p < 0.001), cavities (p = 0.006), bronchiolitis (p < 0.001), consolidations (p = 0.004), and total score (p < 0.001). Nodules showed no significant differences between groups (p = 0.060). The Wilcoxon test showed significant differences between both CTs in patients with a microbiological cure for the total score (p < 0.001), cavities (p = 0.005), bronchiolitis (p < 0.001), and consolidations (p = 0.021) with a decrease after microbiological cure, whereas bronchiectasis (p = 0.102) and nodules (p = 0.18) stayed stable. In the case of persistently positive cultures, there was an increase in the total score (p = 0.010) which was attributable to progressivebronchiectasis (p < 0.001). Cavities, consolidations, and bronchiolitis are useful to assess treatment response, whereas bronchiectasis and nodules may remain stable despite successful treatment. Cavities, consolidations, and bronchiolitis can assess treatment response whereas bronchiectasis and nodules may remain stable despite successful treatment. In persistently positive cultures, bronchiectasis showed an increase over time indicating that NTM-PD is a progressive chronic disease. Little is known about CT changes in nontuberculous mycobacteriapulmonary disease (NTM-PD) and criteria to evaluate treatment response. In the case of culture conversion, cavities and bronchiolitis decreased whereas bronchiectasis and nodules remained stable. Cavities and bronchiolitis can evaluate treatment response in NTM, but bronchiectasis and nodules may persist despite successful treatment.

Reproducibility of CT-based opportunistic vertebral volumetric bone mineral density measurements from an automated segmentation framework

BackgroundTo investigate the reproducibility of automated volumetric bone mineral density (vBMD) measurements from routine thoracoabdominal computed tomography (CT) assessed with segmentations by a convolutional neural network and automated correction of contrast phases, on diverse scanners, with scanner-specific asynchronous or scanner-agnostic calibrations.MethodsWe obtained 679 observations from 278 CT scans in 121 patients (77 males, 63.6%) studied from 04/2019 to 06/2020. Observations consisted of two vBMD measurements from Δdifferent reconstruction kernels (n = 169), Δcontrast phases (n = 133), scan Δsessions (n = 123), Δscanners (n = 63), or Δall of the aforementioned (n = 20), and observations lacking scanner-specific calibration (n = 171). Precision was assessed using root-mean-square error (RMSE) and root-mean-square coefficient of variation (RMSCV). Cross-measurement agreement was assessed using Bland-Altman plots; outliers within 95% confidence interval of the limits of agreement were reviewed.ResultsRepeated measurements from Δdifferent reconstruction kernels were highly precise (RMSE 3.0 mg/cm3; RMSCV 1.3%), even for consecutive scans with different Δcontrast phases (RMSCV 2.9%). Measurements from different Δscan sessions or Δscanners showed decreased precision (RMSCV 4.7% and 4.9%, respectively). Plot-review identified 12 outliers from different scan Δsessions, with signs of hydropic decompensation. Observations with Δall differences showed decreased precision compared to those lacking scanner-specific calibration (RMSCV 5.9 and 3.7, respectively).ConclusionAutomatic vBMD assessment from routine CT is precise across varying setups, when calibrated appropriately. Low precision was found in patients with signs of new or worsening hydropic decompensation, what should be considered an exclusion criterion for both opportunistic and dedicated quantitative CT.Relevance statementAutomated CT-based vBMD measurements are precise in various scenarios, including cross-session and cross-scanner settings, and may therefore facilitate opportunistic screening for osteoporosis and surveillance of BMD in patients undergoing routine clinical CT scans.Key PointsArtificial intelligence-based tools facilitate BMD measurements in routine clinical CT datasets.Automated BMD measurements are highly reproducible in various settings.Reliable, automated opportunistic osteoporosis diagnostics allow for large-scale application.Graphical

Human Brain Deuterium Metabolic Imaging at 7 T: Impact of Different [6,6'-2H2]Glucose Doses.

Deuterium metabolic imaging (DMI) is an innovative, noninvasive metabolic MR imaging method conducted after administration of 2H-labeled substrates. DMI after [6,6'-2H2]glucose consumption has been used to investigate brain metabolic processes, but the impact of different [6,6'-2H2]glucose doses on DMI brain data is not well known. To investigate three different [6,6'-2H2]glucose doses for DMI in the human brain at 7 T. Prospective. Six healthy participants (age: 28 ± 8 years, male/female: 3/3). 7 T, 3D 2H free-induction-decay (FID)-magnetic resonance spectroscopic imaging (MRSI) sequence. Three subjects received two different doses (0.25 g/kg, 0.50 g/kg or 0.75 g/kg body weight) of [6,6'-2H2]glucose on two occasions and underwent consecutive 2H-MRSI scans for 120 minutes. Blood was sampled every 10 minutes during the scan, to determine plasma glucose levels and plasma 2H-Glucose atom percent excess (APE) (part-1). Three subjects underwent the same protocol once after receiving 0.50 g/kg [6,6'-2H2]glucose (part-2). Mean plasma 2H-Glucose APE and glucose plasma concentrations were compared using one-way ANOVA. Brain 2H-Glc and brain 2H-Glx (part-1) were analyzed with a two-level Linear Mixed Model. In part-2, a General Linear Model was used to compare brain metabolite signals. Statistical significance was set at P < 0.05. Between 60 and 100 minutes after ingesting [6,6'-2H2]glucose, plasma 2H-Glc APE did not differ between 0.50 g/kg and 0.75 g/kg doses (P = 0.961), but was significantly lower for 0.25 g/kg. Time and doses significantly affected brain 2H-Glucose levels (estimate ± standard error [SE]: 0.89 ± 0.01, 1.09 ± 0.01, and 1.27 ± 0.01, for 0.25 g/kg, 0.50 g/kg, and 0.75 g/kg, respectively) and brain 2H-Glutamate/Glutamine levels (estimate ± SE: 1.91 ± 0.03, 2.27 ± 0.03, and 2.46 ± 0.03, for 0.25 g/kg, 0.50 g/kg, and 0.75 g/kg, respectively). Plasma 2H-Glc APE, brain 2H-Glc, and brain 2H-Glx levels were comparable among subjects receiving 0.50 g/kg [6,6'-2H2]glucose. Brain 2H-Glucose and brain 2H-Glutamate/Glutamine showed to be [6,6'-2H2]glucose dose dependent. A dose of 0.50 g/kg demonstrated comparable, and well-detectable, 2H-Glucose and 2H-Glutamate/Glutamine signals in the brain. 1 TECHNICAL EFFICACY: Stage 2.

Dynamic evaluation of corneal cross-linking and osmotic diffusion effects using optical coherence elastography

Dynamic deformation events induced by osmosis or photochemical stiffening substantially influence geometrical and mechanical assessments in post-mortem corneas, therefore need to be carefully monitored in experimental settings. In this study, we employed optical coherence elastography (OCE) to quantify dynamic deformation processes at high resolution in freshly enucleated porcine corneas. Osmotic effects were studied by immerging n = 9 eyes in preservation media of three different tonicities. Dynamic processes underlying corneal cross-linking (CXL) were studied by subjecting n = 6 eyes to standard Dresden treatment, while three control groups were used. The entire procedures were performed under an OCE setup during up to 80 min, acquiring a volumetric scan every 20 s. Changes in OCE-derived axial deformations were incrementally calculated between consecutive scans. Preservation conditions had a strong influence on the observed strain patterns, which were consistent with the tonicity of the medium (swelling in hypotonic, deswelling in hypertonic environment). In the CXL group, we observed deswelling of the anterior stroma 10 min after starting the UV irradiation, which was not observed in any control group (p = 0.007). The presented results proved OCE to be a valuable technique to quantify subtle dynamic biomechanical alterations in the cornea resulting from CXL and preservation solutions.