Douglas Ebert

New heights in ultrasound: first report of spinal ultrasound from the international space station.

BACKGROUND Changes in the lumbar and sacral spine occur with exposure to microgravity in astronauts; monitoring these alterations without radiographic capabilities on the International Space Station (ISS) requires novel diagnostic solutions to be developed. STUDY OBJECTIVES We evaluated the ability of point-of-care ultrasound, performed by nonexpert-operator astronauts, to provide accurate anatomic information about the spine in long-duration crewmembers in space. METHODS Astronauts received brief ultrasound instruction on the ground and performed in-flight cervical and lumbosacral ultrasound examinations using just-in-time training and remote expert tele-ultrasound guidance. Ultrasound examinations on the ISS used a portable ultrasound device with real-time communication/guidance with ground experts in Mission Control. RESULTS The crewmembers were able to obtain diagnostic-quality examinations of the cervical and lumbar spine that would provide essential information about acute or chronic changes to the spine. CONCLUSIONS Spinal ultrasound provides essential anatomic information in the cervical and lumbosacral spine; this technique may be extensible to point-of-care situations in emergency departments or resource-challenged areas without direct access to additional radiologic capabilities.

Concept of Operations Evaluation for Using Remote-Guidance Ultrasound for Exploration Spaceflight.

BACKGROUND Remote-guidance (RG) techniques aboard the International Space Station (ISS) have enabled astronauts to collect diagnostic-level ultrasound (US) images. Exploration-class missions will likely require nonformally trained sonographers to operate with greater autonomy given longer communication delays (> 6 s for missions beyond the Moon) and blackouts. Training requirements for autonomous collection of US images by non-US experts are being determined. METHODS Novice US operators were randomly assigned to one of three groups to collect standardized US images while drawing expertise from A) RG only, B) a computer training tool only, or C) both RG and a computer training tool. Images were assessed for quality and examination duration. All operators were given a 10-min standardized generic training session in US scanning. The imaging task included: 1) bone fracture assessment in a phantom and 2) Focused Assessment with Sonography in Trauma (FAST) examination in a healthy volunteer. A human factors questionnaire was also completed. RESULTS Mean time for group B during FAST was shorter (20.4 vs. 22.7 min) than time for the other groups. Image quality scoring was lower than in groups A or C, but all groups produced images of acceptable diagnostic quality. DISCUSSION RG produces US images of higher quality than those produced with only computer-based instruction. Extended communication delays in exploration missions will eliminate the option of real-time guidance, thus requiring autonomous operation. The computer program used appears effective and could be a model for future digital US expertise banks. Terrestrially, it also provides adequate self-training and mentoring mechanisms.

Preflight, In-Flight, and Postflight Imaging of the Cervical and Lumbar Spine in Astronauts

BACKGROUND Back pain is a common complaint during spaceflight that is commonly attributed to intervertebral disc swelling in microgravity. Ultrasound (US) represents the only imaging modality on the International Space Station (ISS) to assess its etiology. The present study investigated: 1) The agreement and correlation of spinal US assessments as compared to results of pre- and postflight MRI studies; and 2) the trend in intervertebral disc characteristics over the course of spaceflight to ISS. METHODS Seven ISS astronauts underwent pre- and postflight US examinations that included anterior disc height and anterior intervertebral angles with comparison to pre- and postflight MRI results. In-flight US images were analyzed for changes in disc height and angle. Statistical analysis included repeated measures ANOVA with Bonferroni post hoc analysis, Bland-Altman plots, and Pearson correlation. RESULTS Bland-Altman plots revealed significant disagreement between disc heights and angles for MRI and US measurements while significant Pearson correlations were found in MRI and US measurements for lumbar disc height (r2 = 0.83) and angle (r2 = 0.89), but not for cervical disc height (r2 = 0.26) or angle (r2 = 0.02). Changes in anterior intervertebral disc angle-initially increases followed by decreases-were observed in the lumbar and cervical spine over the course of the long-duration mission. The cervical spine demonstrated a loss of total disc height during in-flight assessments (∼0.5 cm). DISCUSSION Significant disagreement but significant correlation was noted between US and MRI measurements of disc height and angle. Consistency in imaging modality is important for trending measurements and more research related to US technique is required.Harrison MF, Garcia KM, Sargsyan AE, Ebert D, Riascos-Castaneda RF, Dulchavsky SA. Preflight, in-flight, and postflight imaging of the cervical and lumbar spine in astronauts. Aerosp Med Hum Perform. 2018; 89(1):32-40.

Volumetric Ophthalmic Ultrasound for Inflight Monitoring of Visual Impairment and Intracranial Pressure

OBJECTIVE The objective is enhanced ophthalmic ultrasound imaging to monitor ocular structure and intracranial dynamics changes related to visual impairment and intracranial pressure (ICP) induced by microgravity. The goals are to improve the ease of use and reduce operator variability by automatically rendering improved views of the anatomy and deriving new metrics of the morphology and dynamics. MATERIALS AND METHODS A prototype three-dimensional (3-D) probe was integrated onto a portable ultrasound scanner. Image analysis algorithms were developed to automatically detect the ocular anatomy and simultaneously render views of the optic nerve with improved sheath definition. Curvature metrics were calculated from 3-D retinal surfaces to quantify posterior globe flattening, and tissue velocity waveforms of the optic nerve were analyzed to assess intracranial dynamics. RESULTS New 3-D structural measurements were evaluated in a head-down tilt study. The response of optic nerve sheath and globe flattening metrics were quantified in 11 healthy volunteers from baseline to moderately elevated ICP. The optic nerve measurements showed good correlation with existing two-dimensional (2-D) methods and an acute response to increased ICP, while globe flattening did not show an acute response. The tissue velocities were evaluated in a porcine model from baseline to significantly elevated ICP and correlated with invasive ICP readings in four animals. CONCLUSIONS Volumetric ophthalmic imaging was demonstrated on a portable ultrasound system and structural measurements validated with existing methods. New 3-D structural measurements and dynamic measurements were evaluation during in vivo studies. Further investigations are needed to evaluate improvements in performance for non-experts and application to clinically relevant conditions.