Changes In Attenuation Research Articles

Imaging Cerebral Energy Metabolism in Healthy Infants.

Broadband near-infrared spectroscopy (bNIRS) has the potential to provide non-invasive measures of cerebral haemodynamic changes alongside changes in cellular oxygen utilisation through the measurement of mitochondrial enzyme cytochrome-c-oxidase (oxCCO). It therefore provides the opportunity to explore brain function and specialisation, which remains largely unexplored in infancy. We used bNIRS to measure changes in haemodynamics and changes in oxCCO in 4-to-7-month-old infants over the occipital and right temporal and parietal cortices in response to social and non-social visual and auditory stimuli. Changes in concentration of oxygenated-haemoglobin (Δ[HbO2]), deoxygenated haemoglobin (Δ[HHb]) and change in the oxidation state of oxCCO (Δ[oxCCO]) were calculated using changes in attenuation of light at 120 wavelengths between 780 and900nm, using the UCLn algorithm. For 4 infants, the attenuation changes in a subset of wavelengths were used to perform image reconstruction, in an age-matched infant model, for channels over the right parietal and temporal cortices, using a multispectral approach which allows direct reconstruction of concentration change data. The volumetric reconstructed images were mapped onto the cortical surface to visualise the reconstructed changes in concentration of HbO2 and HHb and changes in metabolism for both social and non-social stimuli. Spatially localised activation was observed for Δ[oxCCO] and Δ[HbO2] over the temporo-parietal region, in response to the social stimulus. This study provides the first reconstructed images of changes in metabolism in healthy, awake infants.

Monitoring geological gas storage sites with ambient noise interferometric methods: focus on seismic attenuation changes for gas movement detection.

Monitoring geological gas storage sites with ambient noise interferometric methods: focus on seismic attenuation changes for gas movement detection.

A dual-mode microwave sensor for edible oil characterization using magnetic-LC Resonators

A low-cost, compact, and high sensitivity dual-mode microwave sensor for edible oil determination and quality monitoring is proposed in this paper. Two magnetic-LC (MLC) resonators loaded on a flared microstrip patch are fabricated on a Rogers RT/Duroid 5880 substrate. The dual-mode microwave sensor is designed and measured to operate at 12.6 GHz and 16.2 GHz. When the proposed dual-mode microwave sensor is submerged in the oils to be tested, the changes of resonance frequency and peak attenuation are utilized for sample identification and dielectric characterization. The complex permittivity of oils under test are extracted by building an approximate model in High Frequency Structure Simulator (HFSS). Two simplified linear equations are established to estimate the complex permittivity of unknown oils and heated peanut oil samples. The estimated error of dielectric constant is less than 0.28% due to the dual-mode resonance design of the sensor. The measured sensitivity of the proposed dual-mode microwave sensor at first and second resonance is as high as 7.4% and 9.9%, respectively. The proposed sensor is expected to be a cost-effective, more sensitive and accurate solution for dielectric characterization of edible oil and its quality assessment.

Bone metastases with post-treatment intralesional fatty content of the spine: imaging features from T1-weighted imaging with CT finding correlations.

Despite post-treatment intralesional fatty content (PIFAT) in bone metastases indicating a healing processes after treatment, the imaging features of PIFAT have not been studied in detail. To analyze imaging features from T1-weighted (T1W) imaging with computed tomography (CT) finding correlations in bone metastases with PIFAT of the spine. A total of 29 bone metastases with PIFAT were analyzed with T1W and CT images before and after treatment. On T1W imaging after treatment, the lesions were categorized into three types according to fat distribution patterns. CT attenuation changes after treatment were also evaluated. According to the MD Anderson (MDA) criteria, response types for all lesions were obtained on magnetic resonance (MR) and CT images. The types from T1W imaging in bone metastases with PIFAT were as follows: 14 with a return to totally normal marrow signal intensity within the lesion; 13 with an inhomogeneous patchy pattern in the lesion; and two with a peripheral halo of fatty marrow or peripheral fat signal intensity foci in the lesion. Among bone metastases with PIFAT, 93.1% showed osteosclerotic changes in this study. According to the MDA criteria, the concordance between the response types of the MR and CT images was 57.2%. Knowledge of imaging features from T1W imaging with CT correlation in bone metastases with PIFAT is important for the accurate interpretation of post-treatment MR and CT studies. Both MR and CT images have a complementary value regarding the post-treatment evaluation of bone metastases with PIFAT.

EFFECTS OF SMOOTH, MEDIUM SMOOTH AND MEDIUM RECONSTRUCTION KERNELS ON IMAGE QUALITY IN THREE-PHASE CT OF LIVER

Reconstruction kernel is one of the parameters that affects the computed tomography (CT) image quality. This study aimed to evaluate the effects of applying three different reconstruction kernels on image quality in 3-phased CT of the liver. A total of 63 CT liver images including normal liver (n = 43) and liver lesion (n = 20) were retrospectively reviewed. Smooth (B20f), medium smooth (B30f) and medium (B40f) reconstruction kernels were employed in the image reconstruction process. Mean attenuation, image noise, and signal-to-noise ratio (SNR) values from each kernel reconstruction were quantified and compared among those kernels using One Way Analysis of Variance (ANOVA) statistical analysis. Significant changes in image noise and SNR were observed in the normal liver (p < 0.001, respectively) following the application of those reconstruction kernels. However, no significant changes in mean attenuation, image noise, and SNR were demonstrated in the liver lesion (p > 0.05). Application of smooth (B20f), medium smooth (B30f), and medium (B40f) kernel reconstructions would significantly affect the image noise and SNR in the normal liver of CT images instead of liver lesions. Hence, proper selection of reconstruction kernel is important in CT images reconstruction to improve precision in diagnostic CT interpretation.

Strong thermal stratification reduces detection efficiency and range of acoustic telemetry in a large freshwater lake

BackgroundThe successful use of acoustic telemetry to detect fish hinges on understanding the factors that control the acoustic range. The speed-of-sound in water is primarily a function of density, and in freshwater lakes density is primarily driven by temperature. The strong seasonal thermal stratification in the Great Lakes represent some of the steepest sound speed gradients in any aquatic system. Such speed-of-sound gradients can refract sound waves leading to greater divergence of acoustic signal, and hence more rapid attenuation. The changes in sound attenuation change the detection range of a telemetry array and hence influence the ability to monitor fish. We use 3 months of data from a sentinel array of V9 and V16 Vemco acoustic fish tags, and a record of temperature profiles to determine how changes in stratification influence acoustic range in eastern Lake Ontario.ResultWe interpret data from an acoustic telemetry array in Lake Ontario to show that changes in acoustic detection efficiency and range correlate strongly with changes in sound speed gradients due to thermal stratification. The steepest sound speed gradients of 10.38 m s−1/m crossing the thermocline occurred in late summer, which caused the sound speed difference between the top and bottom of the water column to be greater than 60 m/s. V9 tags transmitting across the thermocline could have their acoustic range reduced from > 650 m to 350 m, while the more powerful V16 tags had their range reduced from > 650 m to 450 m. In contrast we found that when the acoustic source and receiver were both transmitting below thermocline there was no change in range, even as the strength of sound speed gradient varied.ConclusionChanges in thermal stratification occur routinely in the Great Lakes, on timescales between months and days. The acoustic range can be reduced by as much as 50% compared to unstratified conditions when fish move across the thermocline. We recommend that researchers consider the influences of thermal stratification to acoustic telemetry when configuring receiver position.

Tests for the correct insertion of earplugs in the ear canal performed with the use of a portable device

The aim of the study was to assess the correct insertion of earplugs in the ear canal by people with different knowledge regarding this matter. The use of hearing protectors leads to a reduction in the risk of hearing loss, which is part of environmental engineering. Measurements of sound attenuation by earplugs were carried out with the participation of 21 people with no experience in the use of earplugs. The measurements were repeated until the subjects had read the instructions for the use of earplugs, and then after the subjects had been trained in the correct insertion of earplugs in the ear canal. The tests were carried out using a newly developed portable device for quick measurements of sound attenuation. Familiarizing the subjects with the instructions for use resulted in a sound attenuation value being 6.7 and 3.3 dB higher, at 250 and 4000 Hz, respectively, compared to the measurement when the subjects inserted earplugs in the ear canal without any guidance. An even greater increase in attenuation was observed when the subjects were trained to insert earplugs, at 9.2 dB (250 Hz) and 5.4 dB (4000 Hz), respectively. In most cases, the changes in attenuation as a result of providing guidance were statistically significant. Persons who have no experience in using earplugs have significant problems with their correct insertion. Reading the instructions for use does not guarantee that earplugs will be inserted correctly. Only the training showing how to insert the earplugs correctly results in people being able to do it correctly in most cases. Med Pr. 2021;72(5):521-8.

Longitudinal CT and MRI Characteristics of Unilocular Thymic Cysts.

Background Isoattenuating and hyperattenuating thymic cysts at CT are often misinterpreted as lymphadenopathy or thymic epithelial neoplasms. Purpose To evaluate the longitudinal change in thymic cyst appearance at CT and MRI. Materials and Methods All chest MRI studies showing thymic cysts between July 2008 and December 2019, identified from a retrospective search of a quality assurance database, were included in this study if initial CT depicted a thymic lesion, the patient was referred for follow-up MRI for characterization, and the baseline (ie, index) MRI indicated a cystic lesion. Follow-up CT scans and/or MRI scans were identified through July 2020. Thymic cyst characteristics, such as size, location, and morphologic features, as well as CT and MRI characteristics, were recorded. Change in size, attenuation, and T1-weighted MRI signal was assessed longitudinally. Descriptive statistics of longitudinal change were tabulated. Results A total of 244 chest MRI studies in 140 patients with 142 unique cysts and 392 CT examinations (636 total examinations and 645 thymic cysts-nine examinations with two cysts each) were evaluated. The median follow-up duration was 2.2 years. Thirty-three patients with 34 unique cysts (34 of 142 cysts [24%]) underwent imaging follow-up for more than 5 years. Thymic cysts followed up for more than 5 years were most commonly saccular (189 of 274 cysts [69% axially]) and retrosternal (14 of 34 cysts [41%]). Craniocaudal dimension was larger than transverse and anteroposterior dimensions in 223 of 274 cysts (81%). Mean thymic cyst attenuation was 25 HU (range, 15-100 HU). Five of 31 cysts (16%) exhibited wall calcification. The median cyst wall thickness was 2.0 mm (range, 0.9-3.0 mm). Most thymic cysts changed in volume (31 of 34 cysts [91%]), CT attenuation (15 of 35 cysts [43%]), and T1-weighted MRI signal (12 of 18 cysts [67%]) over time. None developed mural irregularity, nodularity, or septations. Conclusion Unilocular thymic cysts, defined at index MRI, never developed irregular wall thickening, mural nodularity, or septations that would raise concern for malignant transformation. However, these cysts showed mural calcification and change in size, CT attenuation, and MRI signal over more than 5 years of follow-up. © RSNA, 2021 Online supplemental material is available for this article.

Rime ice growth characterized by surface acoustic wave

We propose a new theoretical method and experimental investigation to characterize the growth process of rime ice through surface acoustic waves (SAWs). The Biot theory of dual-phase porous media was employed to construct a theoretical model to describe the acoustic wave propagation in porous rime ice; the transient changes in acoustic propagation attenuation and velocity were simulated; and the icing sensing mechanism of the acoustic wave propagation attenuation (∼18 dB) and the transient change in velocity (0.8 m/s) during the icing process was obtained. A 177.5 MHz waveguide type SAW micro–nano-device with an SU8/ST-90°X quartz multilayer composite film structure and a microfluidic cavity on the top of the acoustic device were designed and fabricated, and the transient attenuation in the growth of rime ice was evaluated experimentally. The experimental results indicated that the appearance of rime ice can be monitored accurately by utilizing the transient changes in acoustic wave velocity and attenuation. Therefore, the acoustic method can aid in the early warning of the development status of rime ice.

Peri-vascular adipose tissue attenuation on chest computed tomography in patients with Marfan Syndrome: a case series.

Marfan Syndrome is a genetic disorder that determines histopathological alterations of the aortic vascular wall leading to increased inflammatory component. The peri-vascular adipose tissue attenuation is a method able to capture localized vascular inflammation by mapping spatial changes of perivascular tissue attenuation on computed tomography. We measured peri-vascular adipose tissue attenuation around the ascending aorta in three consecutive subjects with confirmed genetic diagnosis of Marfan Syndrome. All subjects received the genetic diagnosis of fibrillin-1 gene mutation as part of the family screening of patients with known Marfan Syndrome. Chest computed tomography was performed in such asymptomatic subjects after genetic confirmation of Marfan Syndrome. None of these subjects showed aortic aneurysms or suffered from chronic inflammatory/infectious disease. In the three subjects identified with Marfan Syndrome the value of aortic peri-vascular adipose tissue attenuation measured at chest computed tomography was higher than normal and the volume of aortic peri-vascular adipose tissue was lower. These preliminary observations suggest that peri-vascular adipose tissue attenuation is unexpectedly high in patients with Marfan Syndrome, notwithstanding the normal aortic diameter at the time of computed tomography. Whether this observation may find a clinical use in suspected Marfan Syndrome or in predicting aortic complications in Marfan Syndrome is worth to be assessed in prospective studies.

Radiotherapy Response Assessment of Multiple Myeloma: A Dual-Energy CT Approach With Virtual Non-Calcium Images.

BackgroundLife expectancy of patients with multiple myeloma (MM) has increased over the past decades, underlining the importance of local tumor control and avoidance of dose-dependent side effects of palliative radiotherapy (RT). Virtual noncalcium (VNCa) imaging from dual-energy computed tomography (DECT) has been suggested to estimate cellularity and metabolic activity of lytic bone lesions (LBLs) in MM.ObjectiveTo explore the feasibility of RT response monitoring with DECT-derived VNCa attenuation measurements in MM.MethodsThirty-three patients with 85 LBLs that had been irradiated and 85 paired non-irradiated LBLs from the same patients were included in this retrospective study. Irradiated and non-irradiated LBLs were measured by circular regions of interest (ROIs) on conventional and VNCa images in a total of 216 follow-up measurements (48 before and 168 after RT). Follow-ups were rated as therapy response, stable disease, or local progression according to the MD Anderson criteria. Receiver operating characteristic (ROC) analysis was performed to discriminate irradiated vs. non-irradiated and locally progressive vs. stable/responsive LBLs using absolute attenuation post-irradiation and percentage attenuation change for patients with pre-irradiation DECT, if available.ResultsAttenuation of LBLs decreased after RT depending on the time that had passed after irradiation [absolute thresholds for identification of irradiated LBLs 30.5–70.0 HU [best area under the curve [AUC] 0.75 (0.59–0.91)] and -77.0 to -22.5 HU [best AUC 0.85 (0.65–1.00)]/-50% and -117% to -167% proportional change of attenuation on conventional and VNCa images, respectively]. VNCa CT was significantly superior for identification of RT effects in LBLs with higher calcium content [best VNCa AUC 0.96 (0.91–1.00), best conventional CT AUC 0.64 (0.45–0.83)]. Thresholds for early identification of local irradiation failure were >20.5 HU on conventional CT [AUC 0.78 (0.68–0.88)] and >-27 HU on VNCa CT [AUC 0.83 (0.70–0.96)].ConclusionTherapy response of LBLs after RT can be monitored by VNCa imaging based on regular myeloma scans, which yields potential for optimizing the lesion-specific radiation dose for local tumor control. Decreasing attenuation indicates RT response, while above threshold attenuation of LBLs precedes local irradiation failure.

An ultrasonic shear wave viscometer for low viscosity Newtonian liquids

A method based on ultrasonic wave propagation is applied for the determination of the viscosity of low viscous liquids. A waveguide is used to remotely transmit the ultrasonic waves from a shear piezoelectric transducer into the liquid. At the solid–liquid interface, a guided wave mode, the shear mode, is used to extract the liquid viscosity. The energy of the reflected ultrasonic wave depends upon its operating frequency, the physical properties of the liquid (viscosity and density), and the waveguide (density and shear modulus). The results show that the attenuation of the waves, and thus the viscosity of the liquid, can be retrieved using this method. Measurements on water, ethanol, and mixtures of water/glycerol illustrate that the method can monitor changes in attenuation due to the viscosity of the liquid. The range of viscosities measured was between 0.8 and 60 mPa s. Compared to literature values, the relative error for these measurements was lower than 12% while the uncertainty in the measurements was lower than 5%. Besides its ability to measure low viscosities, this method offers advantages such as the capability to perform in-situ measurements of liquids in harsh environments, the omission of mechanical parts, and the possibility to handle small volumes of liquid. These features make this method suitable for low viscous liquids that are radioactive, corrosive and at high temperature.

BiCyCLE NMES\u2014neuromuscular electrical stimulation in the perioperative treatment of sarcopenia and myosteatosis in advanced rectal cancer patients: design and methodology of a phase II randomised controlled trial

BackgroundColorectal cancer is associated with secondary sarcopenia (muscle loss) and myosteatosis (fatty infiltration of muscle) and patients who exhibit these host characteristics have poorer outcomes following surgery. Furthermore, patients, who undergo curative advanced rectal cancer surgery such as pelvic exenteration, are at risk of skeletal muscle loss due to immobility, malnutrition and a post-surgical catabolic state. Neuromuscular electrical stimulation (NMES) may be a feasible adjunctive treatment to help ameliorate these adverse side-effects. Hence, the purpose of this study is to investigate NMES as an adjunctive pre- and post-operative treatment for rectal cancer patients in the radical pelvic surgery setting and to provide early indicative evidence of efficacy in relation to key health outcomes.MethodIn a phase II, double-blind, randomised controlled study, 58 patients will be recruited and randomised (1:1) to either a treatment (NMES plus standard care) or placebo (sham-NMES plus standard care) group. The intervention will begin 2 weeks pre-operatively and continue for 8 weeks after exenterative surgery. The primary outcome will be change in mean skeletal muscle attenuation, a surrogate marker of myosteatosis. Sarcopenia, quality of life, inflammatory status and cancer specific outcomes will also be assessed.DiscussionThis phase II randomised controlled trial will provide important preliminary evidence of the potential for this adjunctive treatment. It will provide guidance on subsequent development of phase 3 studies on the clinical benefit of NMES for rectal cancer patients in the radical pelvic surgery setting.Trial registrationProtocol version 6.0; 05/06/20. ClinicalTrials.gov NCT04065984. Registered on 22 August 2019; recruiting.

Improving Clinical dosimetric Accuracy of cancer treatment using a special quality of Electron and Photon Beam

In external beam radiation therapy, electron and photon beams have extraordinary characteristics in the treatment of cancer. The electron and photon beam characteristic are essential to study before calibration of machine. This study focused on the dosimetric characteristics of different energies of electron beams for different field size. The basic objective of this work is, to calculate dosimetric parameters and characteristics of electron beam, specially depth dose characteristics along central axis. In this work, 6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV of electron beam and 6 MV and 15 MV of photon beam with different field size is used. Characteristics of depth dose of electron and photon beam in water have analyzed to provide better quality of radiation therapy treatment planning. The different beam characteristics are due to different interactions that occurs between electron beams giving them a definite range whereas photon beams are attenuated leading to dose deposition and much larger range with no definite end. Depth dose characteristics of electron and photon beams do not show same characteristics as interaction of beam with matter depends on the quality of beam. Attenuation and penetration factors change with changing dosimetric parameters. Complete analysis of dosimetric characteristics of electron and photon beam help to choose more accurate beam for the treatment of cancer. This work will help to increase accuracy in treatment of cancer with radiotherapy.

Improving Clinical dosimetric Accuracy of Cancer Treatment Using a Special Quality of Electron and Photon Beam

Electron and photon beams demonstrate extraordinary characteristics useful for the treatment of cancer. These characteristics are essential to analyze before the calibration of the linear accelerator with dual energies. This study focused on the dosimetric characteristics of the different energies of electron beam for different field sizes. The basic objective of this work was to calculate the dosimetric parameters and characteristics of the electron beam, especially depth dose characteristics along the central axis. In this work, 6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV of electron beam and 6 MV and 15 MV of photon beam with different field sizes were used. The characteristics of the depth dose of electron and photon beams in water were analyzed to optimize the radiation quality for radiation treatment planning. The different beam characteristics are due to different interactions that occur between electron beams giving them a definite range, whereas photon beams are attenuated leading to dose deposition and a much larger range with no definite end. Depth dose characteristics of electron and photon beams are not similar since the interaction of these beams with matter depends on their quality. Attenuation and penetration factors change with changing dosimetric parameters. A complete analysis of the dosimetric characteristics of electron and photon beams helps to choose the more accurate beam for the treatment of cancer. This work helps to increase accuracy in the treatment of cancer with radiotherapy.
 Copyright(c) The Authors

Estimation of time of death using brain parenchyma attenuation in post mortem computed tomography of brain – In malaysian setting

• Brain is first organ to undergo decomposition after death occurs and can be used to estimate early PMI. • Overall average attenuation of brain show linear positive correlation with early PMI. • Attenuation measurement at centrum semiovale, high convexity and parietal lobe can be grouped together and its average attenuation shows good correlation with early PMI. • In regards to one area of brain attenuation that corresponds best to PMI is at high convexity level. To measure brain attenuation of Post Mortem Computed Tomography (PMCT) of brain and to determine the correlation between the Post-Mortem Interval (PMI) and brain parenchymal attenuation value. This was a retrospective cross sectional study conducted at Institut Perubatan Forensik Negara (IPFN) of Hospital Kuala Lumpur from April 2019 to April 2020. Total of 160 PMCT brain samples that met inclusion criteria were examined. A measurement cursor with fixed size was used to measure the brain parenchymal attenuation in Hounsfield Unit (HU). The values were then averaged and plotted against the PMI to assess the correlation. Each brain location average attenuation as well as average attenuation of grouped locations were plotted against PMI to examine if any particular site of the brain had almost similar correlation or trend as the overall attenuation. There was positive linear correlation between the brain parenchymal attenuation changes and PMI, where there was progressive increase in HU values within the time limit of PMCT at our center, in which the longest stood at 31 hours. The best-fit model for the correlation involved the average attenuation of Centrum Semiovale-High Convexity-Parietal (CSHCP) levels. There was positive linear correlation between PMI and brain parenchymal attenuation and within the CSHCP levels, High Convexity was the single location that was most representative of this group, hence can be used to estimate PMI of a brain particularly in early decomposition state.

Echolocation call frequencies of bats vary with body temperature and weather conditions

Many animals vary their acoustic signals with weather conditions to ensure sufficient range of signal transmission as atmospheric attenuation increases (the atmospheric attenuation change hypothesis). However, few studies have considered the effects of weather conditions on the vocalizations of endotherms via the effects on their physiological condition (the physiological change hypothesis). In the present study, we directly linked weather conditions to changes in bats' body temperatures and to their echolocation call frequencies. We found a significantly positive correlation between body temperatures and call frequencies among individuals of the great leaf-nosed bat, Hipposideros armiger , in the wild. We then monitored changes in body temperature and call frequency of H. armiger over an hour at an ambient temperature of about 11 °C. The bats emitted echolocation calls of lower frequencies with decreasing body temperature caused by decreased ambient temperature, supporting the physiological change hypothesis. We also investigated changes in body temperature and echolocation call frequencies for H. armiger from summer to winter. The bats’ body temperatures decreased with decreasing ambient temperature. However, echolocation call frequencies increased significantly. A linear mixed-effects model suggested that the change in atmospheric attenuation rather than body temperature had a significant effect on the call frequency, supporting the atmospheric attenuation change hypothesis. Overall, our results suggested that weather conditions can affect the echolocation signals of bats via the effects on their body temperature and on atmospheric attenuation. When both effects coexist, weather-induced adjustments in the echolocation signals could be more likely to be driven by the atmospheric attenuation effect. • Call frequency is correlated with body temperature among individuals in H. armiger . • Body temperature and call frequency decrease at low (constant) ambient temperature. • Seasonal variation in weather conditions causes a decrease in body temperature. • Call frequency is negatively correlated with atmospheric attenuation.

Does knee osteoarhtritis antecipate muscle attenuation changes in differents muscles of thigh since early ages?

Purpose: Knee osteoarthritis (KOA) is one of the most common chronic-degenerative joint diseases in individuals aged 40 years or more. KOA is characterized to cause numerous negative impacts on joint adjacent tissue, such as muscles. It is already known that decreasing in muscle mass associated with increased adipose tissue are characteristics that have contributed to the progression of KOA. Similarly, the aging process causes changes in cross-sectional area, decrease in muscle mass, and increase in fat deposit on muscles.

Multidisciplinary analysis of hydraulic stimulation and production effects within the Niobrara and Codell reservoirs, Wattenberg Field, Colorado — Part 2: Analysis of hydraulic fracturing and production

Enhanced hydrocarbon recovery is essential for continued economic development of unconventional reservoirs. We have focused on dynamic characterization of the Niobrara and Codell Formations in Wattenberg Field through the development and analysis of a full integrated reservoir model. We determine the effectiveness of the hydraulic fracturing and production with two seismic monitor surveys, surface microseismic, completion data, and production data. The two monitor surveys were recorded after stimulation and again after two years of production. Identification of reservoir deformation due to hydraulic fracturing and production improves reservoir models by mapping nonstimulated and nonproducing zones. Monitoring these time-variant changes improves the prediction capability of reservoir models, which in turn leads to improved well and stage placement. We quantify dynamic reservoir changes with time-lapse P-wave seismic data using prestack inversion and velocity-independent layer stripping for velocity and attenuation changes within the Niobrara and Codell reservoirs. A 3D geomechanical model and production data are history matched, and a simulation is run for two years of production. Results are integrated with time-lapse seismic data to illustrate the effects of hydraulic fracturing and production. Our analyses illustrate that chalk facies have significantly higher hydraulic fracture efficiency and production performance than marl facies. In addition, structural and hydraulic complexity associated with faults generate spatial variability in a well’s total production.

Fatal COVID-19 is Characterized by Distinct Vasculopathic Features and Increased Congestion of the Alveolar Capillary-Bed

Background: Clinical and radiologic studies investigating Coronavirus disease 2019 (COVID-19) indicate that a possible cause of severe hypoxia is marked ventilation-perfusion (VA/Q) mismatch. Published histopathology reports diffuse alveolar damage (DAD) in fatal COVID-19 is indistinguishable from other causes of DAD. We compared lung parenchymal and vascular alterations between COVID-19 and DAD of other etiologies using a multidimensional approach. Methods: This autopsy cohort consisted of consecutive COVID-19 patients (n=20) and patients with clinical acute respiratory distress syndrome and histologic DAD (n=21; non-COVID-19 viral and non-viral etiologies). Premortem chest CTs were evaluated for mosaic attenuation and vascular changes. Postmortem lung tissues were compared using histopathological, immunohistochemical, transcriptomics and computational analyses. Machine-learning-derived morphometric analysis of microvasculature was performed, with a random forest classifier quantifying vascular congestion (VSCong), in different microscopic compartments. Findings: On premortem CT, COVID-19 patients showed more mosaic attenuation (p<0·020), and subsegmental dilated vasculature (p=0·003) compared to controls. Histopathology revealed vasculopathic changes including: capillary-congestion and hemangiomatosis-like changes (p=0·043), microthrombi (p=0·026), thromboemboli (p=0·0036), infarcts (p=0·048), and perivascular inflammation(p <0·001). Immunohistochemistry revealed increased CD4+ T-cells(p=0·023), TIM3+ lymphocytes/macrophages (p=0·037/0·019), and PD-1+ cells(p=0·008). Morphometric analysis in COVID-19 revealed significantly higher bronchiolar VS Cong (p <0·0001) and alveolar-septal VSCong (p<0·0001), with larger overall VSCong range (p=0·002). Septal-congestion was associated with a significantly shorter time-to-death from symptom onset (p=0·02). Interpretation: Severe COVID-19 is characterized by significant vasculopathy and aberrant alveolar septal-congestion, which may be associated with shorter time-to-death. Dilated sublobar vessels and heterogeneously increased septal-congestion may translate to VA/Q mismatch in COVID-19. These findings warrant further investigation in larger multi-institutional autopsy cohorts. Funding Information: Supported by Internal Sundry, and Vickery-Colvin Award from the Department of Pathology, Massachusetts General Hospital. Declaration of Interests: LPH reports grants from Boehringer Ingelheim and has received personal consulting fees from Boehringer Ingelheim, Pliant Therapeutics, and Biogen Idec, all of which are not related to this study. SET have received CDC funding for other COVID-related work which are not related to this study. JAB has received grant support from Zeus Scientific, bioMerieux, Immunetics, the Bay Area Lyme Foundation and the Lyme Disease Biobank Foundation for work not related to this study, and has been a consultant for T2 Biosystems, DiaSorin and Roche Diagnostics, not related to this study. BPL reports royalties from Elsevier, Inc. for his work as an associate textbook editor, not related to this study. MMK has served as a compensated consultant for H3 Biomedicine and AstraZeneca and has received research (institutional) funding from Novartis and loyalty from Elsevier, all of which are not related to this study. The other authors declare no competing interests. Ethics Approval Statement: Analysis of patient autopsy material was reviewed and approved by the Partners Human Research IRB (Protocol #: 2020P001146).