Performance enhancement due to a top dielectric coating on a metamaterial perfect absorber.

A tri-layer metamaterial structure with enhanced absorption is demonstrated at infrared wavelengths by coating the top surface of the metamaterial absorber with an additional thin layer of dielectric material. The metamaterial absorber, which consists of a micrometer-sized metallic circular patch separated from a metal ground plane by a dielectric spacer layer, when coated with a supplementary protective dielectric layer on the top, shows a spectral red shift of the peak absorption along with a change in the absorption amplitude. The increase or decrease in absorption arises basically from an interference phenomenon of light reflected from the surface of the protective dielectric and the surface of metamaterial structures, and is highly dependent on the thickness of the top dielectric layer. The protective dielectric coatings provide an alternative way to modify and optimize the absorption in a metamaterial absorber along with a robustness that protects metamaterial structures from environmental and mechanical degradation.

The Current Role of Robotics in Colorectal Surgery.

PURPOSE OF REVIEW: Despite the growth in laparoscopic surgery, comparable oncological outcomes, and reduced complication rates, the majority of colorectal surgery is still performed via an open approach. Reasons for this may include technical difficulties associated with operating in narrow spaces such as in the pelvis and inadequate experience. Robotic surgery provides potential solutions to some of these challenges. This review will summarize the state of the literature regarding robotic colorectal surgery. RECENT FINDINGS: The most consistent benefit of robotic surgery is decreasing operative conversions, specifically in rectal cancer. In partial colectomies, there is evidence to support quicker return to bowel function. Oncologic outcomes compared to the laparoscopic approach are equivalent. Robotic surgery provides solutions to the challenges posed by laparoscopy, including wristed instruments, ease of intracorporeal suturing, and ergonomic advantages. Randomized trials to evaluate peri-operative outcomes will be important. If robotics is able to facilitate conversion of open colectomies to their minimally invasive equivalent, robotics may end up proving to be advantageous in the peri-operative and post-operative period. Continued studies are warranted.

High contrast switchability of VO2 based metamaterial absorbers with ITO ground plane.

A metamaterial consisting of an array of gold micro-disks, separated from a ground plane of indium tin oxide (ITO) by a thin film of vanadium dioxide (VO2), behaves as a perfect absorber at infrared (IR) frequencies at room temperature. This metamaterial, which is transparent to visible light, can be switched to a highly reflecting state for IR light by heating the metamaterial to temperatures larger than the metal-insulator phase transition temperature 68°C of VO2. For a disk diameter of 1.5 µm and VO2 film thickness of 320 nm, two absorption bands are obtained: one, that arises from the metamaterial resonance; and a second peak that arises principally from a Fabry-Pérot resonance. A large change (>78%) occurs in the reflectivity between the low and high temperature phases. IR emittance of the metamaterial was measured with IR cameras and shown to be switchable to result in low emittance at high temperature. Optical readout of the state of VO2 within the metamaterial is demonstrated.

Assessment of osteoporotic fracture risk in urban Indian population using quantitative ultrasonography & FRAX tool.

BACKGROUND & OBJECTIVES: There have been studies around the world on the prevalence of osteoporosis and its related risk factors, but there have been limited studies on risk factors and osteoporosis in the Indian population. In this study, the incidence of osteoporosis and the associated clinical risk factors (CRFs) were studied in the urban Indian population. METHODS: Bone mineral density of 445 individuals >38 yr of age using qualitative ultrasound (QUS) was assessed. The patients were also questioned regarding the presence of the various CRFs as per the FRAX tool. The patients were categorized into normal, osteopenia and osteoporosis groups on the basis of T-score from QUS. RESULTS: There were 223 males and 222 females in this study. Sex was significantly associated with T-score (P<0.001). Forty (8.99%) patients were osteoporotic, 265 (59.55%) were osteopenic and the remaining 140 (31.46%) were normal. A significant association of T-score was found with parent history of fracture (P<0.05), rheumatoid arthritis (P<0.05) and secondary osteoporosis (P<0.05). Previous history of fracture's association was not found to be significant. Smoking, alcohol intake and steroid intake were not found to be significantly associated with T-scores. INTERPRETATION & CONCLUSIONS: The incidence of osteoporosis was found to be high in the urban Indian population. More care and attention should be targeted towards elderly, especially the ones with the risk factors to prevent osteoporosis in future.

Ultra-high-field 7-Tesla magnetic resonance imaging in fragile X tremor/ataxia syndrome (FXTAS).

Fragile X tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder characterized by premutation expansion of fragile X mental retardation 1 (FMR1) gene. It is a common single-gene cause of tremor, ataxia, and cognitive decline in adults. FXTAS affects the central, peripheral and autonomic nervous systems, leading to a range of neurological symptoms from dementia to dysautonomia. A characteristic imaging feature of FXTAS is symmetric T2 hyperintensity in the deep white matter of the cerebellar hemispheres and middle cerebral peduncle. However, recent studies have reported additional findings on diffusion weighted images (DWI), such as a symmetric high-intensity band-like signal at the cerebral corticomedullary junction. These findings, along with the characteristic cerebellar signal alterations, overlap with imaging findings seen in adult-onset neuronal intranuclear inclusion disease (NIID). Importantly, recent pathology studies have shown that both FXTAS and NIID can manifest intranuclear inclusion bodies, posing a diagnostic challenge and potential for misdiagnosis. We describe a 58-year-old man with FXTAS who received an erroneous diagnosis based on imaging and histopathology results. We emphasize the potential pitfalls in distinguishing NIID from FXTAS and stress the importance of genetic analysis in all cases with suspected NIID and FXTAS for confirmation. Additionally, we present the 7T MRI brain findings of FXTAS.

Reinforced tissue matrix to strengthen the abdominal wall following reversal of temporary ostomies or to treat incisional hernias.

BACKGROUND: Abdominal wall deficiencies or weakness are a common complication of temporary ostomies, and incisional hernias frequently develop after colostomy or ileostomy takedown. The use of synthetic meshes to reinforce the abdominal wall has reduced hernia occurrence. Biologic meshes have also been used to enhance healing, particularly in contaminated conditions. Reinforced tissue matrices (RTMs), which include a biologic scaffold of native extracellular matrix and a synthetic component for added strength/durability, are designed to take advantage of aspects of both synthetic and biologic materials. To date, RTMs have not been reported to reinforce the abdominal wall following stoma reversal. AIM: To evaluate the effectiveness of using an RTM to reinforce the abdominal wall at stoma takedown sites. METHODS: Twenty-eight patients were selected with a parastomal and/or incisional hernia who had received a temporary ileostomy or colostomy for fecal diversion after rectal cancer treatment or trauma. Following hernia repair and proximal stoma closure, RTM (OviTex® 1S permanent or OviTex® LPR) was placed to reinforce the abdominal wall using a laparoscopic, robotic, or open surgical approach. Post-operative follow-up was performed at 1 month and 1 year. Hernia recurrence was determined by physical examination and, when necessary, via computed tomography scan. Secondary endpoints included length of hospital stay, time to return to work, and hospital readmissions. Evaluated complications of the wound/repair site included presence of surgical site infection, seroma, hematoma, wound dehiscence, or fistula formation. RESULTS: The observational study cohort included 16 male and 12 female patients with average age of 58.5 years ± 16.3 years and average body mass index of 26.2 kg/m2 ± 4.1 kg/m2. Patients presented with a parastomal hernia (75.0%), incisional hernia (14.3%), or combined parastomal/incisional hernia (10.7%). Using a laparoscopic (53.6%), robotic (35.7%), or open (10.7%) technique, RTMs (OviTex® LPR: 82.1%, OviTex® 1S: 17.9%) were placed using sublay (82.1%) or intraperitoneal onlay (IPOM; 17.9%) mesh positioning. At 1-month and 1-year follow-ups, there were no hernia recurrences (0%). Average hospital stays were 2.1 d ± 1.2 d and return to work occurred at 8.3 post-operative days ± 3.0 post-operative days. Three patients (10.7%) were readmitted before the 1-month follow up due to mesh infection and/or gastrointestinal issues. Fistula and mesh infection were observed in two patients each (7.1%), leading to partial mesh removal in one patient (3.6%). There were no complications between 1 month and 1 year (0%). CONCLUSION: RTMs were used successfully to treat parastomal and incisional hernias at ileostomy reversal, with no hernia recurrences and favorable outcomes after 1-month and 1-year.

Clinical and Genomic Profile of Primary Cranial Neurolymphomatosis.

Primary cranial neurolymphomatosis (PCNL) is a rare subtype of primary CNS lymphoma (PCNSL) in which infiltrative lymphomatous involvement is confined to cranial nerves. Here, we report a case of PCNL with successful genomic profiling. A 57-year-old male had a lengthy prediagnostic phase spanning approximately 30 months, characterized by multiple episodes of cranial neuropathies managed by steroids. At the time of diagnosis, the patient had right-sided cranial neuropathies involving cranial nerves (CN) V, VI, and VII. Pathological findings of the right cavernous lesion biopsy were consistent with large B-cell lymphoma-infiltrating nerve fibers. The clinical course was aggressive and refractory, characterized by relentless progression with the development of cervical spinal neurolymphomatosis, cerebrospinal fluid involvement, and ependymal and intraparenchymal cerebral involvement, despite multiple lines of therapy, including chemoimmunotherapy, Bruton's tyrosine kinase inhibitor, radiation, autologous stem cell transplant, chimeric antigen receptor T-cell therapy (CAR-T), and whole-brain radiation. The patient survived for 22 months from the time of the initial diagnosis and 52 months after the first episode of cranial neuropathy. Next-generation sequencing identified mutations (MYD88, CD79b, and PIM1) that are frequently observed in PCNSL. The unusual findings included a total of 22 mutations involving PIM1, indicating a highly active aberrant somatic hypermutation and two missense CXCR4 mutations. CXCR4 mutations have never been described in PCNSL and may have implications for disease biology and therapeutic interventions. We provide a literature review to further elucidate PCNL.

Comprehensive Review of External and Middle Ear Anatomy on Photon Counting CT.

Photon counting CT allows for improved spatial and contrast resolution as compared to traditional energy integrating detector CT. Photon counting CT offers markedly improved visualization of previously described structures, as well as those that were previously beyond the resolution of imaging. Although the anatomical details of the external ear and middle ear structures have been described previously, the rich detail of these structures has not been comprehensively reviewed in the radiology literature. The microarchitecture of the middle ear ossicles and bony protuberances are particularly well visualized on photon counting CT. This manuscript updates the existing literature with a detailed anatomical review of external ear and the middle ear on temporal bone CT.ABBREVIATIONS: EID, energy-integrating detector; PCT, photon-counting computed tomography.

Cauda equina neuroendocrine tumors: A single institutional imaging review of cases over two decades.

Cauda Equina Neuroendocrine Tumors (CE-NET), previously referred to as paragangliomas are a rare subset of spinal tumors, with limited data on imaging. Herein, we present a retrospective review of clinical and imaging findings of CE-NETs in ten patients who were evaluated at our institution over the past two decades. All patients had well-defined intradural lesions in the lumbar spine which demonstrated slow growth. A review of imaging findings revealed the presence of an eccentric vascular pedicle along the dorsal aspect of the tumor in 8 of the 10 patients (eccentric vessel sign), a distinctive finding that has not previously been reported with this tumor and may help improve the accuracy of imaging-based diagnosis. In all cases, a gross-total resection was performed, with resolution of symptoms in most of the cases.

Radiologic Classification of Hippocampal Sclerosis in Epilepsy.

Temporal lobe epilepsy is a common form of epilepsy that is often associated with hippocampal sclerosis (HS). Although HS is commonly considered a binary assessment in radiological evaluation, it is known that histopathological changes occur in distinct clusters. Some subtypes of HS only affect certain subfields, resulting in minimal changes to the overall volume of the hippocampus. This is likely a major reason why whole hippocampal volumetrics have underperformed versus expert readers. With recent advancements in MRI technology, it is now possible to characterize the substructure of the hippocampus more accurately. However, this is not consistently addressed in radiographic evaluations. The histological subtype of HS is critical for prognosis and treatment decision making, necessitating improved radiological classification of HS. The International League Against Epilepsy (ILAE) has issued a consensus classification scheme for subtyping HS histopathological changes. This review aims to explore how the ILAE subtypes of HS correlate with radiographic findings, introduce a grading system that integrates radiological and pathological reporting in HS, and outline an approach to detecting HS subtypes using MRI. This framework will not only benefit current clinical evaluations, but also enhance future studies involving high-resolution MRI in temporal lobe epilepsy.ABBREVIATIONS: CA = cornu ammonis; DG = dentate gyrus; HS = hippocampal sclerosis; ILAE = International League Against Epilepsy; SRLM = strata radiatum, lacunosum, and moleculare layers; TLE = temporal lobe epilepsy.

Imaging findings in Giant Cell Arteritis: Don't Turn A Blind Eye To The Obvious!

Giant cell arteritis (GCA) is the most common primary large vessel systemic vasculitis in the western world. Even though the involvement of scalp and intracranial vessels has received much attention in the neuroradiology literature, GCA, being a systemic vasculitis can involve multiple other larger vessels including aorta and its major head and neck branches. Herein, the authors present a pictorial review of the various cranial, extracranial and orbital manifestations of GCA. An increased awareness of this entity may help with timely and accurate diagnosis, helping expedite therapy and preventing serious complications.ABBREVIATIONS: ACR= American College of Rheumatology, AION= Anterior Ischemic Optic Neuropathy, EULAR= European League Against Rheumatism, GCA= Giant Cell Arteritis, LV-GCA= Large vessel GCA, PMR= Polymyalgia Rheumatica, US= Ultrasound, VWI= Vessel Wall Imaging.

7 T Lesion-Attenuated Magnetization-Prepared Gradient Echo Acquisition for Detection of Posterior Fossa Demyelinating Lesions in Multiple Sclerosis.

OBJECTIVES: Detection of infratentorial demyelinating lesions in multiple sclerosis (MS) presents a challenge in magnetic resonance imaging (MRI), a difficulty that is further heightened in 7 T MRI. This study aimed to assess the efficacy of a novel MRI approach, lesion-attenuated magnetization-prepared gradient echo acquisition (LAMA), for detecting demyelinating lesions within the posterior fossa and upper cervical spine on 7 T MRI and contrast its performance with conventional double-inversion recovery (DIR) and T2-weighted turbo spin echo sequences. MATERIALS AND METHODS: We conducted a retrospective cross-sectional study in 42 patients with a confirmed diagnosis of MS. All patients had 7 T MRI that incorporated LAMA, 3D DIR, and 2D T2-weighted turbo spin echo sequences. Three readers assessed lesion count in the brainstem, cerebellum, and upper cervical spinal cord using both DIR and T2-weighted images in one session. In a separate session, LAMA was analyzed alone. Contrast-to-noise ratio was also compared between LAMA and the conventional sequences. Lesion counts between methods were assessed using nonparametric Wilcoxon signed rank test. Interrater agreement in lesion detection was estimated by intraclass correlation coefficients. RESULTS: LAMA identified a significantly greater number of lesions than DIR + T2 (mean 6.4 vs 3.0; P < 0.001). LAMA also exhibited better interrater agreement (intraclass correlation coefficient [95% confidence interval], 0.75 [0.41-0.88] vs 0.61 [0.35-0.78]). The contrast-to-noise ratio for LAMA (3.7 ± 0.9) significantly exceeded that of DIR (1.94 ± 0.7) and T2 (1.2 ± 0.7) (all P 's < 0.001). In cases with no lesions detected using DIR + T2, at least 1 lesion was identified in 83.3% with LAMA. Across all analyzed brain regions, LAMA consistently detected more lesions than DIR + T2. CONCLUSIONS: LAMA significantly improves the detection of infratentorial demyelinating lesions in MS patients compared with traditional methods. Integrating LAMA with standard magnetization-prepared 2 rapid acquisition gradient echo acquisition provides a valuable tool for accurately characterizing the extent of MS disease.

Multiple floating metatarsals: a unique injury.

Concomitant dislocation of the tarsometatarsal and metatarsophalangeal joints of foot is an extremely rare injury. Such injuries presenting in a single or adjacent dual rays have been described in few cases previously. We describe such an injury in adjacent three metatarsals of a polytrauma patient. These injuries are likely to be missed in the initial assessment of a polytrauma patient. These patients are at risk of an overlooked diagnosis but the consequences of missing this type of injury may be quite severe. This case is presented in view of its uniqueness along with possible mechanism of injury, the sequence of reduction and follow-up. Knowledge of such injury and its proper management may be useful to the trauma surgeons.

Is the use of nonsteroidal anti-inflammatories after bowel anastomosis in trauma safe?

BACKGROUND: With an increasing interest in multimodal and opioid-reducing pain strategies, nonsteroidal anti-inflammatory drugs (NSAIDs) have become common place in the care of injured patients. Long-standing concerns of increased anastomotic leak (AL) rate with the use of NSAIDs, however, have persisted. We hypothesized that there would be no significant risk associated with NSAID use after bowel anastomosis in trauma patients. METHODS: All patients presenting to a level 1 trauma center who required intestinal resection and anastomosis from 2011 to 2017 were reviewed. Patients receiving NSAIDs were compared with those managed without NSAIDs. Primary outcome of interest was anastomosis-related complications (AL, intra-abdominal abscess, anastomotic bleed, fascial dehiscence, fascial dehiscence, and enterocutaneous fistula). Multivariable logistic regression analyses were performed with propensity adjustment for inverse probability of NSAID treatment weights. RESULTS: A total of 295 patients met the inclusion criteria with 192 receiving NSAIDs. Patients receiving NSAIDs had lower abdominal Abbreviated Injury Scale and Injury Severity Score ( p < 0.046). Arrival systolic blood pressure, diastolic blood pressure, and Glasgow Coma Scale were higher in the NSAID group ( p < 0.013). After propensity weighting, NSAID use was not a major predictor of anastomotic complication ( p = 0.39). There was an increased risk of AL with perioperative vasopressor exposure (odds ratio [OR], 3.33; 95% confidence interval [CI], 1.17-9.05; p < 0.001). Increasing red blood cell transfusions in the first 24 hours were associated with intra-abdominal complications (OR, 1.02; 95% CI, 1.00-1.04; p = 0.05). Nonsteroidal anti-inflammatory drug exposure demonstrated a weak association with AL (OR, 1.92; 95% CI, 0.97-3.90; p = 0.06). CONCLUSION: Consistent with previous studies, perioperative vasopressor exposure and increased number of red blood cell transfusions are risk factors for ALs and intra-abdominal complications, respectively. Nonsteroidal anti-inflammatory drug use in trauma patients with multiple risk factors may be associated with an increased risk of AL and should be used with caution in the setting of other established risk factors. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

Hyperviscosity Syndrome Induced Bilateral Visual and Auditory Impairment in Therapy Resistant Waldenström Macroglobulinemia with MYD88 and CXCR4 Mutations.

Hyperviscosity syndrome (HVS) is an emergent complication of Waldenström macroglobulinemia (WM) characterized by visual, neurologic, and rarely auditory impairment. We report a 69-year-old female with MYD88 and CXCR4-mutant WM who developed HVS resulting in bilateral blindness and deafness associated with neurologic manifestations including confusion, severe generalized weakness, and imbalance. Ophthalmologic evaluation revealed bilateral central retinal vein occlusion (CRVO), diffuse retinal hemorrhages, macular edema, and serous macular detachments (SMD). Magnetic resonance imaging of the brain showed bleeding in the inner ears. Management was challenging as her WM was resistant to systemic therapies including bendamustine + rituximab (BR) and rituximab + bortezomib + dexamethasone (RVD). Bruton's tyrosine kinase inhibitors could not be used initially due to ongoing lower gastrointestinal bleeding. She required five total sessions of plasma exchange and was finally initiated on zanubrutinib, achieving a partial response. She also received intravitreal bevacizumab with rapid resolution of the retinal hemorrhages but with little improvement of the SMD. She had partial restoration of her hearing in the right ear and only slight improvement in her bilateral visual deficits. The management of HVS in frail, elderly patients with therapy-resistant WM can be challenging. In these cases, plasma exchange is required until an effective systemic therapy can be safely instituted. Genomic profiling is important in the management of WM as it can predict treatment resistance and guide therapeutic decisions.

Central Vein Sign in Multiple Sclerosis: A Comparison Study of the Diagnostic Performance of 3T versus 7T MRI.

BACKGROUND AND PURPOSE: An early and accurate diagnosis of multiple sclerosis remains challenging in clinical neurology. Established diagnostic methods have less than desirable sensitivity and specificity. An accurate, noninvasive diagnostic test for MS could have a major impact on diagnostic criteria. We compared the frequency of detection of the central vein sign (CVS) in white matter lesions of MS and controls on 7T T2*-weighted and SWI to 3T SWI. Additionally, we assessed the diagnostic performance of 7T T2*, 7T SWI, and 3T SWI for MS. MATERIALS AND METHODS: A retrospective case-control study was performed of patients with MS having both 7T MRI and 3T MRI. A control group of patients without MS was selected. Diagnosis of MS was established by board-certified neurologists with fellowship training in autoimmune neurology in line with the 2017 McDonald criteria. Percentage of lesions with a CVS was blindly measured for each technique. Diagnostic performance was computed by sensitivity, specificity, and positive and negative likelihood ratios (LRs). RESULTS: Sixty-one patients with MS (903 lesions) and 39 controls (1088 lesions) were included. 7T T2* showed significantly more CVS (87%) than both 7T SWI (73%) and 3T SWI (31%) (all P < .001). CVS was identified in the control group in ≤6% of lesions on all sequences. Using a threshold of >40% of lesions with CVS on 7T T2* and >15% on 7T SWI, both sequences had an accuracy = 100%, sensitivity = 100%, specificity = 100%, infinite positive LR, and zero negative LR. Using an optimal threshold of >12%, 3T SWI had an accuracy = 96.0%, sensitivity = 93.4%, specificity = 100%, infinite positive LR, and negative LR = 0.066. CONCLUSIONS: 7T MRI had 100% sensitivity and specificity for the diagnosis of MS and is superior to 3T. Future revisions to MS diagnostic criteria may consider recommendations for 7T MRI and inclusion of CVS as a biomarker.