X-Ray Imaging in the Simulated Microgravity Environment of Parabolic Flight.

INTRODUCTION: The advancement of human spaceflight has made urgent the need to develop medical imaging technology to ensure a high level of in-flight care. To date, only ultrasound has been used in spaceflight. Radiography has multiple advantages over ultrasound, including lower operator dependence, more rapid acquisition, typically higher spatial resolution, and characterization of tissue with acoustic impedance precluding ultrasound. This proof-of-concept work demonstrates for the first time the feasibility of performing human radiographs in microgravity.METHODS: Radiographs of a phantom and human subject's hand, knee, chest, cervical spine, and pelvis were obtained aboard a parabolic flight in microgravity and simulated lunar gravity with various subject and operator positions. Control radiographs were acquired with the same system on the ground. These radiographs were performed with a Food and Drug Administration-approved ultra-portable, wireless, battery-powered, digital x-ray system.RESULTS: The radiographs of the phantom acquired in reduced gravity were qualitatively and quantitatively compared to the ground controls and found to exhibit similar diagnostic adequacy. There was no statistically significant difference in contrast resolution or spatial resolution with a spatial resolution across all imaging environments up to the Nyquist frequency of 3.6 line-pairs/mm and an average contrast-to-noise ratio of 2.44.DISCUSSION: As mass, power, and volume limitations lessen over the coming decades and the miniaturization of imaging equipment continues, in-flight implementation of nonsonographic modalities will become practical. Given the demonstrated ease of use and satisfactory image quality, portable radiography is ready to be the new frontier of space medical imaging.Lerner D, Pohlen M, Wang A, Walter J, Cairnie M, Gifford S. X-ray imaging in the simulated microgravity environment of parabolic flight. Aerosp Med Hum Perform. 2023; 94(10):786-791.

Overview of lunar dust toxicity risk.

Lunar dust (LD), the component of lunar regolith with particle sizes less than 20 µm, covers the surface of the Moon. Due to its fineness, jagged edges, and electrostatic charge, LD adheres to and coats almost any surface it contacts. As a result, LD poses known risks to the proper functioning of electronic and mechanical equipment on the lunar surface. However, its mechanical irritancy and chemical reactivity may also pose serious health risks to humans by a number of mechanisms. While Apollo astronauts reported mild short-lived respiratory symptoms, the spectrum of health effects associated with high-dose acute exposure or chronic low-dose exposure are not yet well-understood. This paper explores known and potential human risks of exposure to LD which are thought to be important in planning upcoming lunar missions and planetary surface work.

Just-in-time Training with Remote Guidance for Ultrasound-Guided Percutaneous Intervention.

BACKGROUND: Management of surgical emergencies in spaceflight will pose a challenge as the era of exploration class missions dawns, requiring increased crew autonomy at a time when training and supplies will be limited. Ultrasound-guided percutaneous intervention would allow for the management of a variety of pathologies with largely shared equipment and training. This proof-of-concept work attempts to determine the feasibility of "just-in-time" remote teaching and guidance of a sample procedure of this type.METHODS: Subjects naïve to ultrasound-guided intervention were instructed via a short video regarding the technique for placement of a percutaneous drain into a simulated abscess within a gel phantom. Subjects were then guided through the performance of the procedure via two-way audiovisual communication with an experienced remote assistant. Technical success was determined by the successful aspiration or expression of fluid from the simulated abscess following drain placement. This was then performed by and compared with staff experienced with such procedures. Time to completion and number of needle redirections required were also measured.RESULTS: All 29 subjects naïve to interventional work and the 4 experienced control subjects achieved technical success. There was a statistically significant difference in the time to completion between the two groups, with the experienced subjects averaging 2 min to completion and the inexperienced 5.8 min. There was no statistically significant difference in the number of redirections.DISCUSSION: This proof-of-concept work demonstrates high rates of technical success of percutaneous ultrasound-guided intervention in previously inexperienced personnel when provided with brief just-in-time training and live two-way audiovisual guidance.Lerner DJ, Pohlen MS, Apland RC, Parivash SN. Just-in-time training with remote guidance for ultrasound-guided percutaneous intervention. Aerosp Med Hum Perform. 2022; 93(12):882-886.

Imaging spectrum of immunomodulating, chemotherapeutic and radiation therapy-related intracranial effects.

OBJECTIVE: A wide range of treatment-related side effects result in specific neurologic symptoms and signs and neuroimaging features. Even to the most seasoned neuroradiologist, elucidating therapy-related side effects from other common mimics can be challenging. We provide a pictorial survey of some common and uncommon medication-induced and therapy-related neuroimaging manifestations, discuss pathophysiology and common pitfalls in imaging and diagnosis. METHODS: A case-based review is utilized to depict scenarios on a routine basis in a general radiology or neuroradiology practice such as medication-induced posterior reversible encephalopathy syndrome to the more challenging cases of pseudoprogression and pseudoregression in temozolmide and bevacizumab therapy in gliobastoma treatment protocols. CONCLUSION: Knowledge of the treatment-induced imaging abnormalities is essential in the accurate interpretation and diagnosis from the most routine to most challenging of clinical situations. We provide a pictorial review for the radiologist to employ in order to be an invaluable provider to our clinical colleagues and patients.

Haemorrhagic conversion of infectious myelitis in an immunocompromised patient.

A 28-year-old man recently diagnosed with HIV (CD4 19 cells/mm3, viral load 3.6 million copies/mL, not on highly active antiretroviral therapy on initial diagnosis at outside hospital), disseminated histoplasmosis, shingles and syphilis presented with paraplegia developing over 3 days. Spine MRI demonstrated a longitudinally extensive cord lesion extending from C3 to the tip of the conus. Brain MRI was consistent with meningoencephalitis. Cerebrospinal fluid findings were notable for positive varicella zoster virus (VZV) and cytomegalovirus (CMV) PCRs as well as a Venereal Disease Research Laboratory titre of 1:2. Patient was started on treatment for VZV and CMV meningoencephalitis, neurosyphilis and high-dose steroids for infectious myelitis. Repeat spine MRI demonstrated subacute intramedullary haemorrhage of the cervical cord. He was ultimately discharged to a skilled nursing facility for long-term intravenous antiviral therapy and rehabilitation. After 59 days in the hospital, his neurological exam remained grossly unchanged, with flaccid paraplegia and lack of sensation to fine touch in his lower extremities.

Pharmacoresistance with newer anti-epileptic drugs in mesial temporal lobe epilepsy with hippocampal sclerosis.

This study aims to evaluate the overall prognosis, prognostic factors, and efficacy of treatment in patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) who have access to third generation anti-epileptic drugs but not to epilepsy surgery. Eighty-five MTLE-HS patients were retrospectively placed into a seizure-free (seizure-free for >1year) or drug-resistant group, and the two groups were compared on the basis of age, sex, age at onset of seizures, duration of epilepsy, side of lesion, handedness, EEG findings, history of CNS infection, history of febrile convulsions, history of head trauma, history of cognitive impairment, family history of seizures, number of current anti-epileptic drugs (AEDs), total number of AED trials, and presence of individual AEDs. Only 24.7% of MTLE-HS patients had achieved seizure freedom for >1 year. Poor prognosis and drug-resistance were associated with younger age at onset of seizures (p=0.002), longer duration of epilepsy (p=0.018), greater number of current AEDs (p<0.001), and greater total number of AED trials (p<0.001). In addition, regimens with newer AEDs had no greater efficacy than regimens with older AEDs. Most medically managed MTLE-HS patients do not achieve seizure freedom despite multiple AED trials, and treatment with third generation AEDs should not preclude evaluation for epilepsy surgery.