Peritumoral Hyperintense Signal on Post-contrast FLAIR Images Surrounding Vestibular Schwannomas Following Stereotactic Radiosurgery.

Background And Purpose: Prior investigations have noted the presence of peritumoral hyperintense signal (a "halo") around vestibular schwannomas on postcontrast 3D T2 FLAIR images. This study evaluated this phenomenon in a cohort of patients undergoing stereotactic radiosurgery.

Materials And Methods: A retrospective review was completed of consecutive patients with presumed vestibular schwannomas undergoing stereotactic radiosurgery.

Improved visualization of the inferior tympanic and mastoid canaliculi with photon counting detector CT.

Purpose: To compare the performance of the photon-counting detector (PCD)-CT versus a state-of-the-art energy-integrating detector (EID)-CT to identify segments of the inferior tympanic canaliculus (Jacobsons nerve) and the mastoid canaliculus (Arnolds nerve).

Materials & Methods: Patients were prospectively recruited to undergo temporal bone CT on both EID-CT (Siemens Somatom Force) and PCD-CT (Siemens NAEOTOM Alpha) scanners under an IRB-approved protocol. Three neuroradiologists reviewed cases by consensus comparing the ability to identify the proximal, mid, and distal segments of the inferior tympanic canaliculus/Jacobsons nerve and mastoid canaliculus/Arnolds nerve on each scanner using 5-point Likert scales (with 1 indicating EID is far superior to PCD, 3 indicating they are equivalent, and 5 indicating PCD is far superior to EID).

Evaluation of Vestibular Schwannoma Size Over Time: How Well do the Experts Perform and What can be Improved?

Background And Purpose: 2D linear measurements are often used in routine clinical practice during vestibular schwannoma (VS) follow-up, primarily due to wider availability and ease of use. We sought to determine radiologist performance compared to 3D-volumetry, along with the impact of number of linear measurements, slice thickness and tumor volumes on these parameters.

Materials And Methods: Single center retrospective study with 97 patients (592 MRI studies).

Neuroimaging Spectrum of Erdheim-Chester Disease: An Image-based Review.

Erdheim-Chester Disease (ECD) is a rare, multisystem histiocytic disorder characterized by its variable clinical presentations. Central Nervous System (CNS) involvement is observed in approximately half of ECD patients (up to 76% in some series), and often carries a poorer prognosis. While CNS involvement may remain asymptomatic, others may experience a range of neurological symptoms, including cognitive decline, neuropsychiatric disturbances, motor deficits, cranial or peripheral neuropathies, and endocrine abnormalities.

EXPRESS: Landmark Publications in Analytical Atomic Spectrometry: Fundamentals and Instrumentation Development.

The almost-two-centuries history of spectrochemical analysis has generated a body of literature so vast that it has become nearly intractable for experts, much less for those wishing to enter the field. Authoritative, focused reviews help to address this problem but become so granular that the overall directions of the field are lost. This broader perspective can be provided partially by general overviews but then the thinking, experimental details, theoretical underpinnings and instrumental innovations of the original work must be sacrificed.

Skull Base CSF Leaks: Potential Underlying Pathophysiology and Evaluation of Brain MR Imaging Findings Associated with Spontaneous Intracranial Hypotension.

Background And Purpose: CSF leaks of the skull base and spine share a common process of CSF volume loss, and yet only the latter has been associated with spontaneous intracranial hypotension (SIH). Despite published claims that only spinal leaks cause SIH, no prior studies have evaluated brain MR imaging in patients with skull base leaks for findings associated with SIH, such as dural enhancement. The purpose of our study was to use a validated brain MR imaging scoring system to evaluate patients with skull base CSF leaks for findings associated with SIH.

7T MRI for Cushing Disease: A Single-Institution Experience and Literature Review.

Background And Purpose: Cushing disease is typically caused by a pituitary adenoma that frequently is small and challenging to detect on conventional MR imaging. High-field-strength 7T MR imaging can leverage increased SNR and contrast-to-noise ratios compared with lower-field-strength MR imaging to help identify small pituitary lesions. We aimed to describe our institutional experience with 7T MR imaging in patients with Cushing disease and perform a review of the literature.

Optic Neuropathy and Myelopathy in a Teenager With Biotinidase Deficiency.

A 19-year-old man presented with 3 years of gradually progressive, painless vision loss in both eyes. The ophthalmic examination showed bilateral diminished visual acuity, dyschromatopsia, and temporal optic nerve pallor. The neurological examination was consistent with a mild myelopathy with decreased pin-prick sensation starting at T6-T7 and descending through the lower extremities.

Dorsal arachnoid web adjacent to paraspinal retained bullet: Blunt post-traumatic etiology.

Dorsal arachnoid webs are uncommon, and of uncertain etiology. We present a case in which imaging findings of a dorsal arachnoid web were identified at the level of a known prior gunshot injury where a retained bullet was lodged adjacent to the spine, without associated penetrating injury to the spine, suggesting blunt post-traumatic etiology.

Third window lesions of the inner ear: A pictorial review.

Purpose: Radiographic review of pathologies that associate with third window syndrome.

Methods: Case series and literature review.

Results: Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct.

High-resolution computed tomography angiography of the orbit using a photon-counting computed tomography scanner.

Background And Purpose: Recent introduction of photon counting detector (PCD) computed tomography (CT) scanners into clinical practice further improve CT angiography (CTA) depiction of orbital arterial vasculature compared to conventional energy integrating detector (EID) CT scanners. PCD-CTA of the orbit can provide a detailed arterial roadmap of the orbit which can de diagnostic on its own or serve as a helpful planning adjunct for both diagnostic and therapeutic catheter-based angiography of the orbit.

Methods: For this review, EID and PCD-CT imaging was obtained in 28 volunteers.

Improved cochlear implant electrode localization using coregistration of pre- and postoperative CT.

Background And Purpose: Artifact from cochlear implant electrodes degrades image resolution on CT. Here, we describe the use of coregistered pre- and postoperative CT images to reduce metallic artifact from the electrodes to assess its position more accurately within the cochlear lumen.

Methods: Pre- and postoperative CTs were reviewed after coregistration/overlay of both exams.

Spontaneous intracranial hypotension: updates from diagnosis to treatment.

Spontaneous intracranial hypotension (SIH) is caused by spinal cerebrospinal fluid (CSF) leaks, which result in continued loss of CSF volume and multiple debilitating clinical manifestations. The estimated annual incidence of SIH is 5/100,000. Diagnostic methods have evolved in recent years due to improved understanding of pathophysiology and implementation of advanced myelographic techniques.

An aortic wall to vertebral body fistula presenting as a lytic lesion.

There have been multiple reported cases of aortic fistulas but few cases of aorta to vertebral body fistulas and no aortic wall to vertebral body fistulas have been reported. Here we present a case of a patient who is status post thoracic aortic aneurysm (TAA) repair and found to have a lytic vertebral body lesion. Biopsy of the mass revealed blood products without evidence of malignancy and further investigation revealed a fistulous tract between the aortic wall and the vertebral body causing a vertebral body hematoma.

Direct Dielectric Barrier Discharge Ionization Promotes Rapid and Simple Lubricant Oil Fingerprinting.

Petroleomics, which is the characterization, separation, and quantification of the components of petroleum and crude oil, is an emerging area of study. However, the repertoire of analytical methods available to understand commercial automotive lubricant oils (ALOs) is very limited. Ambient mass spectrometry is one of the most sensitive analytical methods for real-time and in situ chemical analysis.

Portable capillary liquid chromatography for pharmaceutical and illicit drug analysis.

A newly developed portable capillary liquid chromatograph was investigated for the separation of various pharmaceutical and illicit drug compounds. The system consists of two high-pressure syringe pumps capable of delivering capillary-scale flow rates at pressures up to 10 000 psi. Capillary liquid chromatography columns packed with sub-2 μm particles are housed in cartridges that can be inserted into the system and easily connected through high-pressure fluidic contact points by simply applying a specific, predetermined torque rather than using standard fittings and less precise sealing protocols.

Dual-wavelength light-emitting diode-based ultraviolet absorption detector for nano-flow capillary liquid chromatography.

The design of a miniaturized LED-based UV-absorption detector was significantly improved for on-column nanoflow LC. The detector measures approximately 27mm×24mm×10mm and weighs only 30g. Detection limits down to the nanomolar range and linearity across 3 orders of magnitude were obtained using sodium anthraquinone-2-sulfonate as a test analyte.

Imaging regiospecific lipid turnover in mouse brain with desorption electrospray ionization mass spectrometry.

Compartmentalization of metabolism into specific regions of the cell, tissue, and organ is critical to life for all organisms. Mass spectrometric imaging techniques have been valuable in identifying and quantifying concentrations of metabolites in specific locations of cells and tissues, but a true understanding of metabolism requires measurement of metabolite flux on a spatially resolved basis. Here, we utilize desorption ESI-MS (DESI-MS) to measure lipid turnover in the brains of mice.

Systematic Comparison between Half and Full Dielectric Barrier Discharges Based on the Low Temperature Plasma Probe (LTP) and Dielectric Barrier Discharge for Soft Ionization (DBDI) Configurations.

Dielectric barrier discharge (DBD)-based analytical applications have experienced rapid development in recent years. DBD designs and parameters and the application they are used for can vary considerably. This leads to a diverse field with many apparently unique systems that are all based on the same physical principle.

Compact Ultrahigh-Pressure Nanoflow Capillary Liquid Chromatograph.

A compact ultrahigh-pressure nanoflow liquid chromatograph (LC) was developed with the purpose in mind of creating a portable system that could be easily moved to various testing locations or placed in close proximity to other instruments for optimal coupling, such as with mass spectrometry (MS). The system utilized innovative nanoflow pumps integrated with a very low volume stop-flow injector and mixing tee. The system weighed only 5.

The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry.

We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules.

Multimodal Vacuum-Assisted Plasma Ion (VaPI) Source with Transmission Mode and Laser Ablation Sampling Capabilities.

We have developed a multimodal ion source design that can be configured on the fly for various analysis modes, designed for more efficient and reproducible sampling at the mass spectrometer atmospheric pressure (AP) interface in a number of different applications. This vacuum-assisted plasma ionization (VaPI) source features interchangeable transmission mode and laser ablation sampling geometries. Operating in both AC and DC power regimes with similar results, the ion source was optimized for parameters including helium flow rate and gas temperature using transmission mode to analyze volatile standards and drug tablets.

Multi-instrument characterization of five nanodiamond samples: a thorough example of nanomaterial characterization.

Here, we report the most comprehensive characterization of nanodiamonds (NDs) yet undertaken. Five different samples from three different vendors were analyzed by a suite of analytical techniques, including X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), inductively coupled plasma mass spectrometry (ICP-MS), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), Brunauer-Emmett-Teller (BET) surface area measurements, and particle size distribution (PSD) measurements. XPS revealed the elemental compositions of the ND surfaces (83-87 at.

Hand-Portable Gradient Capillary Liquid Chromatography Pumping System.

In this work, a novel splitless nanoflow gradient generator integrated with a stop-flow injector was developed and evaluated using an on-column UV-absorption detector. The gradient pumping system consisted of two nanoflow pumps controlled by micro stepper motors, a mixer connected to a serpentine tube, and a high-pressure valve. The gradient system weighed only 4 kg (9 lbs) and could generate up to 55 MPa (8000 psi) pressure.