Liver tissue changes during and post 6-month spaceflight as measured by ultrasound radio frequency signal processing.

Background: Analysis of ultrasound radio frequency (RF) signals allows for the determination of the index of reflectivity (IR), which is a new measure that is dependent on tissue properties. Previous work has shown differences in the IR of the carotid artery wall with long-duration spaceflight; therefore, it was hypothesized that liver tissue would also show differences in this measure with spaceflight.

Methods: The RF signal of a liver tissue region of interest (ROI) was displayed and processed along six different lines covering a surface of approximately 2 cm × 2 cm.

Motorized 3D Ultrasound and Jugular Vein Dimension Measurement on the International Space Station.

Internal jugular vein (IJV) congestion occurs during spaceflight. Historically, IJV distension on the International Space Station (ISS) has been quantified using single slice cross-sectional images from conventional 2D ultrasound with remote guidance. Importantly, the IJV is an irregular shape and highly compressible.

Ultrasound assessments of organs and blood vessels before and after 40 days isolation in a cavern (deep time experiment 2021).

Spaceflight simulation studies like confinement in small volume habitat with limited physical activity have reported even after 60 days an abnormal arterial wall adaptation with increase thickness or stiffness. The purpose of the current study was to determine the effects on blood vessel and organ structure of 40 days of isolation in a huge habitat with intensive physical activity. Data were collected from 14 individuals (7 male) who isolated in a cavern for 40-days while performing normal daily activities without time references.

4 days in dry immersion increases arterial wall response to ultrasound wave as measured using radio-frequency signal, comparison with spaceflight data.

Recent studies have reported a significant increase in common carotid artery (CCA) intima media thickness, wall stiffness and reflectivity to ultrasound, in astronauts, after six months of spaceflight. The hypothesis was that 4 days in dry immersion (subjects under bags of water) will be sufficient to change the CCA wall reflectivity to ultrasound similar to what observed after spaceflight. Such response would be quantified using the amplitude of the ultrasound signal returned to the probe by the target concerned.

4 Day in dry immersion reproduces partially the aging effect on the arteries as observed during 6 month spaceflight or confinement.

The objectives of this study were to determine whether 4 days of dry immersion (DI) induced similar arterial aging as spaceflight and to test the impact of thigh cuffs. Eighteen subjects underwent DI; nine wore thigh cuffs. Cardiac and arterial targets were assessed by ultrasound.

Index of Reflectivity of Ultrasound Radio Frequency Signal from the Carotid Artery Wall Increases in Astronauts after a 6 mo Spaceflight.

The objective was to quantify the index of reflectivity of the common carotid artery and surrounding structures, before and after 6 mo of microgravity. Our hypothesis was that structural changes in the insonated target would increase its index of reflectivity. The neck anterior muscle and common carotid artery (walls and lumen) were visualized by echography (17 MHz linear probe), and the radiofrequency signal along each vertical line was displayed.

Thigh Cuff Effects on Venous Flow Redistribution During 4 Days in Dry Immersion.

The objective was to quantify the venous redistribution during a 4-d dry immersion (DI) and evaluate the effect of thigh cuffs. The study included nine control (Co) and nine subjects wearing thigh cuffs during the daytime (CU). Ultrasound measures were performed Pre-DI, on day 4 AM (D4 AM) and D4 PM: left ventricle stroke volume and ejection fraction (SV, EF), jugular vein volume (JVvol), portal vein diameter (PV), and middle cerebral vein velocity (MCVv).

Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight.

Importance: Exposure to a weightless environment during spaceflight results in a chronic headward blood and tissue fluid shift compared with the upright posture on Earth, with unknown consequences to cerebral venous outflow.

Objectives: To assess internal jugular vein (IJV) flow and morphology during spaceflight and to investigate if lower body negative pressure is associated with reversing the headward fluid shift experienced during spaceflight.

Design, Setting, And Participants: This prospective cohort study included 11 International Space Station crew members participating in long-duration spaceflight missions .

Effects of Resistance Exercise and Nutritional Supplementation on Dynamic Cerebral Autoregulation in Head-Down Bed Rest.

Head-down bed rest (HDBR) is commonly considered as ground-based analog to spaceflight and simulates the headward fluid shift and cardiovascular deconditioning associated with spaceflight. We investigated in healthy volunteers whether HDBR, with or without countermeasures, affect cerebral autoregulation (CA). Twelve men (at selection: 34 ± 7 years; 176 ± 7 cm; 70 ± 7 kg) underwent three interventions of a 21-day HDBR: a control condition without countermeasure (CON), a condition with resistance vibration exercise (RVE) comprising of squats, single leg heel, and bilateral heel raises and a condition using also RVE associated with nutritional supplementation (NeX).

Multi-System Adaptation to Confinement During the 180-Day Controlled Ecological Life Support System (CELSS) Experiment.

Confinement experiments are essential to prepare long-term space exploration. The 180-day Chinese CELSS (Controlled Ecological Life Support System) study is unique in its design, including a closed-loop system and mid-mission simulation of Mars-like day-night cycle of 24 h 40 min for 36 days (days 72-108). Our aim was to study physiological and psychological consequences of this confinement in four healthy volunteers (one female).

Remote Echography between a Ground Control Center and the International Space Station Using a Tele-operated Echograph with Motorized Probe.

Echography is the most appropriate imaging modality for investigating astronauts. Unfortunately, it requires a great deal of training to perform ultrasound examinations, which can be difficult and time consuming, especially if the astronaut does not have a medical background. We designed a new echography system with motorized probes that allows for the majority of exam functions to be controlled by a ground-based sonographer.

Internal Jugular Vein Volume During Head-Down Tilt and Carbon Dioxide Exposure in the SPACECOT Study.

Background: Cerebral hemodynamics and venous outflow from the brain may be altered during exposure to microgravity or head-down tilt (HDT), an analog of microgravity, as well as by increased ambient CO2 exposure as experienced on the International Space Station.

Methods: Six healthy subjects underwent baseline tilt table testing at 0°, 6°, 12°, 18°, 24°, and 30° HDT. The right internal jugular (IJ) vein cross-sectional area (CSA) was measured at four intervals from the submandibular to the clavicular level and IJ volume was calculated.

Carotid and Femoral Arterial Wall Distensibility During Long-Duration Spaceflight.

Introduction: This study aimed to assess changes in common carotid (CA) and superficial femoral (FA) arterial stiffness during long-duration spaceflight.

Methods: Ultrasound imaging was used to investigate the CA and FA of 10 astronauts preflight (PRE), on flight day 15 (FD15), after 4-5 mo (FD4-5m), and 4 d after return to Earth (R+4). Arterial wall properties were assessed through the calculation of strain, stiffness (β), pressure-strain elastic modulus (Ep), and distensibility (DI).

Jugular and Portal Vein Volume, Middle Cerebral Vein Velocity, and Intracranial Pressure in Dry Immersion.

Background: The objective was to determine if short term exposure to dry immersion (DI) results in a cephalic fluid shift similar to what has been observed with spaceflight.

Methods: Data were collected from 10 individuals at rest and during the first 2 h of dry immersion. Jugular vein (JV), portal vein (PV), and thyroid volume were measured using 3D echography.

Tele-Operated Echography and Remote Guidance for Performing Tele-Echography on Geographically Isolated Patients.

Objective: To evaluate the performance of three tele-echography systems for routine use in isolated medical centers.

Methods: Three systems were used for deep (abdomen, pelvis, fetal) and superficial (muscle, thyroid, carotid artery) examinations: (a) a robotic arm (RA) holding an echographic probe; (b) an echograph with a motorized probe (MP); and (c) remote guidance (RG) where the patient site operator performed the examination assisted by an expert via videoconference. All systems were tested in the same medical center located 60 km away from the university hospital.

Carotid and Femoral Artery Intima-Media Thickness During 6 Months of Spaceflight.

Introduction: The objective was to determine the effects of 6 mo of microgravity exposure on conduit artery diameter and wall thickness.

Methods: Diagnostic images of the common carotid artery (CC) and superficial femoral artery (FA) were obtained using echography which astronauts performed on themselves after receiving minimal training in the use of ultrasound imaging. Echographic video was recorded using a volume capture method directed by a trained sonographer on the ground through videoconferencing.

The use of Doppler ultrasonography for pre- and post-surgery monitoring of abdominal aortic aneurysm. Case report.

A 75 year old male patient was monitored for 3 years by Doppler Ultrasonography (US) for an abdominal aorta aneurysm (AAA). Because the aneurysm increased significantly, an aortic prosthesis was installed via an endovascular procedure. After one month of post-surgery monitoring, both Doppler US exam and contrast enhancement US (CEUS) suspected the presence of a leak at the level of the prosthesis.

Increased postflight carotid artery stiffness and inflight insulin resistance resulting from 6-mo spaceflight in male and female astronauts.

Removal of the normal head-to-foot gravity vector and chronic weightlessness during spaceflight might induce cardiovascular and metabolic adaptations related to changes in arterial pressure and reduction in physical activity. We tested hypotheses that stiffness of arteries located above the heart would be increased postflight, and that blood biomarkers inflight would be consistent with changes in vascular function. Possible sex differences in responses were explored in four male and four female astronauts who lived on the International Space Station for 6 mo.

Teleoperated Echograph and Probe Transducer for Remote Ultrasound Investigation on Isolated Patients (Study of 100 Cases).

Purpose: The objective of this study was to design and validate a "Tele-Operated UltRasound System" ("TOURS") to perform ultrasound examinations on patients located in isolated areas.

Materials And Methods: A commercially available portable echograph was modified to allow functions (Doppler, two-dimensional, three-dimensional, elastography, etc.) and settings (gain, depth, freeze, record, etc.

Remote Sonography in Routine Clinical Practice Between Two Isolated Medical Centers and the University Hospital Using a Robotic Arm: A 1-Year Study.

Background: A robotic arm was developed by our laboratory for tele-operated echography on patients in locations isolated from a trained sonographer. The objective of the study was to evaluate, over a 1-year period, the use of the robotic arm for telesonography performed by a sonographer located at the University Hospital (Tours, France) on patients in two isolated medical centers 50 km away linked via the Internet.

Materials And Methods: A nonsonographer operator (physician or paramedic) located the ultrasound probe attached to the robotic arm over the appropriate acoustic window for the organ of interest by rolling the whole robotic arm and mechanical support across the floor.

5-Day Bed Rest: Portal and Lower Limb Veins With and Without Artificial Gravity Countermeasures.

Purpose: The objective of the study was to evaluate the effect of short-term, head-down bed rest (HDBR), with and without artificial gravity countermeasures, on splanchnic and lower limb vein properties.

Methods: Data were collected from 12 men before and after 5 d of continuous -6° HDBR without countermeasures (CON) and with two artificial gravity countermeasure protocols: 30-min continuous centrifugation (AG1), and 30-min intermittent centrifugation (AG2). Portal (PV), tibial (TibV), and gastrocnemius (GastV) veins were investigated by echography supine and after 30 min of head-up tilt.

Measurements of jugular, portal, femoral, and calf vein cross-sectional area for the assessment of venous blood redistribution with long duration spaceflight (Vessel Imaging Experiment).

Purpose: To determine if 6 months in microgravity resulted in significant changes in the major central and peripheral veins indicating a redistribution of venous blood flow.

Methods: Ten astronauts participated in the study. Jugular vein (JV), portal vein (PV), femoral vein (FV), tibial vein (TibV), and gastrocnemius vein (Gast V) were assessed by echography for the measurement of vessel cross-sectional area.