NF2-related schwannomatosis and other schwannomatosis: an updated genetic and epidemiological study.

OBJECTIVES: New diagnostic criteria for NF2-related schwannomatosis (NF2) were published in 2022. An updated UK prevalence was generated in accordance with these, with an emphasis on the rate of de novo NF2 (a 50% frequency is widely quoted in genetic counselling). The distribution of variant types among de novo and familial NF2 cases was also assessed. METHODS: The UK National NF2 database identifies patients meeting updated NF2 criteria from a highly ascertained population cared for by England's specialised service. Diagnostic prevalence was assessed on 1 February 2023. Molecular analysis of blood and, where possible, tumour specimens for NF2, LZTR1 and SMARCB1 was performed. RESULTS: 1084 living NF2 patients were identified on prevalence day (equivalent to 1 in 61 332). The proportion with NF2 inherited from an affected parent was only 23% in England. If people without a confirmed molecular diagnosis or bilateral vestibular schwannoma are excluded, the frequency of de novo NF2 remains high (72%). Of the identified de novo cases, almost half were mosaic. The most common variant type was nonsense variants, accounting for 173/697 (24.8%) of people with an established variant, but only 18/235 (7.7%) with an inherited NF2 pathogenic variant (p<0.0001). Missense variants had the highest proportion of familial association (56%). The prevalence of LZTR1-related schwannomatosis and SMARCB1-related schwannomatosis was 1 in 527 000 and 1 in 1.1M, respectively, 8.4-18.4 times lower than NF2. CONCLUSIONS: This work confirms a much higher rate of de novo NF2 than previously reported and highlights the benefits of maintaining patient databases for accurate counselling.

Genome-wide association analysis identifies a susceptibility locus for sporadic vestibular schwannoma at 9p21.

Vestibular schwannomas are benign nerve sheath tumours that arise on the vestibulocochlear nerves. Vestibular schwannomas are known to occur in the context of tumour predisposition syndromes NF2-related and LZTR1-related schwannomatosis. However, the majority of vestibular schwannomas present sporadically without identification of germline pathogenic variants. To identify novel genetic associations with risk of vestibular schwannoma development, we conducted a genome-wide association study in a cohort of 911 sporadic vestibular schwannoma cases collated from the neurofibromatosis type 2 genetic testing service in the north-west of England, UK and 5500 control samples from the UK Biobank resource. One risk locus reached genome-wide significance in our association analysis (9p21.3, rs1556516, P = 1.47 × 10-13, odds ratio = 0.67, allele frequency = 0.52). 9p21.3 is a genome-wide association study association hotspot, and a number of genes are localized to this region, notably CDKN2B-AS1 and CDKN2A/B, also referred to as the INK4 locus. Dysregulation of gene products within the INK4 locus have been associated with multiple pathologies and the genes in this region have been observed to directly impact the expression of one another. Recurrent associations of the INK4 locus with components of well-described oncogenic pathways provides compelling evidence that the 9p21.3 region is truly associated with risk of vestibular schwannoma tumorigenesis.

Venous thromboembolism chemical prophylaxis after skull base surgery.

PURPOSE: There is no guidance surrounding postoperative venous thromboembolism (VTE) prophylaxis using pharmacological agents (chemoprophylaxis) in patients undergoing skull base surgery. The aim of this study was to compare VTE and intracranial haematoma rates after skull base surgery in patients treated with/without chemoprophylaxis. METHODS: Review of prospective quaternary centre database including adults undergoing first-time skull base surgery (2009-2020). VTE was defined as deep vein thrombosis (DVT) and pulmonary embolism (PE) within 6 months of surgery. Multivariate logistic regression was used to determine factors predictive of postoperative intracranial haematoma/VTE. Propensity score matching (PSM) was used in group comparisons. RESULTS: One thousand five hundred fifty-one patients were included with a median age of 52 years (range 16-89 years) and female predominance (62%). Postoperative chemoprophylaxis was used in 81% of patients at a median of 1 day postoperatively. There were 12 VTE events (1.2%), and the use of chemoprophylaxis did not negate the risk of VTE entirely (p > 0.99) and was highest on/after postoperative day 6 (9/12 VTE events). There were 18 intracranial haematomas (0.8%), and after PSM, chemoprophylaxis did not significantly increase the risk of an intracranial haematoma (p > 0.99). Patients administered chemoprophylaxis from postoperative days 1 and 2 had similar rates of intracranial haematomas (p = 0.60) and VTE (p = 0.60), affirmed in PSM. CONCLUSION: Postoperative chemoprophylaxis represents a relatively safe strategy in patients undergoing skull base surgery. We advocate a personalised approach to chemoprophylaxis and recommend it on postoperative days 1 or 2 when indicated.

Sporadic vestibular schwannoma: a molecular testing summary.

OBJECTIVES: Cases of sporadic vestibular schwannoma (sVS) have a low rate of association with germline pathogenic variants. However, some individuals with sVS can represent undetected cases of neurofibromatosis type 2 (NF2) or schwannomatosis. Earlier identification of patients with these syndromes can facilitate more accurate familial risk prediction and prognosis. METHODS: Cases of sVS were ascertained from a local register at the Manchester Centre for Genomic Medicine. Genetic analysis was conducted in NF2 on blood samples for all patients, and tumour DNA samples when available. LZTR1 and SMARCB1 screening was also performed in patient subgroups. RESULTS: Age at genetic testing for vestibular schwannoma (VS) presentation was younger in comparison with previous literature, a bias resulting from updated genetic testing recommendations. Mosaic or constitutional germline NF2 variants were confirmed in 2% of patients. Pathogenic germline variants in LZTR1 were found in 3% of all tested patients, with a higher rate of 5% in patients <30 years. No pathogenic SMARCB1 variants were identified within the cohort. Considering all individuals who received tumour DNA analysis, 69% of patients were found to possess two somatic pathogenic NF2 variants, including those with germline LZTR1 pathogenic variants. CONCLUSIONS: Undiagnosed schwannoma predisposition may account for a significant minority of apparently sVS cases, especially at lower presentation ages. Loss of NF2 function is a common event in VS tumours and may represent a targetable common pathway in VS tumourigenesis. These data also support the multi-hit mechanism of LZTR1-associated VS tumourigenesis.

The utility of the exoscope compared to the operating microscope in simulated temporal bone surgery.

OBJECTIVE: To objectively assess the utility of an exoscope during simulated otological surgery. DESIGN: Cohort study. SETTING: Tertiary referral otolaryngology centre. PARTICIPANTS: Seven experienced otologists undertook simulated temporal bone surgery on plastic temporal bones using the Zeiss Kinevo microscope with both a microscope and exoscope facility. OUTCOME MEASURES: The utility of microscope and exoscope was compared using a Likert scale from 1 to 10 with and without PPE. Attributes assessed included image quality, depth perception, adequacy of view, exoscope positioning, surgeon comfort, surgeon safety and adequacy of image and protection for assistants and observers. RESULTS: The exoscope in 3D mode performed as well as or better than the microscope for image quality, field of view and manoeuvrability. It outperformed the microscope for compatibility with PPE, surgeon comfort and assistant/observer experience. It scored almost as highly as the microscope for depth perception. CONCLUSION: There is likely to be a learning curve but this initial assessment of the exoscope shows significant potential as an alternative to the operating microscope in otological surgery but with the advantage of allowing the use of appropriate PPE and better ergonomics for both surgeon and assistant/observer.

Imaging in scrotal trauma: a European Society of Urogenital Radiology Scrotal and Penile Imaging Working Group (ESUR-SPIWG) position statement.

Imaging plays a crucial role in the evaluation of scrotal trauma. Among the imaging modalities, greyscale ultrasound and Colour Doppler ultrasound (CDUS) are the primary techniques with the selective utilisation of advanced techniques such as contrast-enhanced ultrasound (CEUS) and elastography. Despite ultrasound being the mainstay of imaging scrotal trauma, its diagnostic performance is not fully established. Considering these difficulties and their impact on clinical practice, the Scrotal and Penile Imaging Working Group of the European Society of Urogenital Radiology (ESUR-SPIWG) established an expert task force to review the current literature and consolidate their expertise on examination standards and imaging appearances of various entities in scrotal trauma. This paper provides the position statements agreed on by the task force with the aim of providing guidance for the use of imaging especially multiparametric US in scrotal trauma.Key Points• Greyscale and Colour Doppler ultrasound are the mainstay of imaging in patients with scrotal trauma.• Contrast-enhanced ultrasound and elastography are the advanced techniques useful as a problem-solving modality in equivocal cases.• This paper summarises the position statements of the ESUR-SPIWG on the appropriate utilisation of multiparametric ultrasound and other imaging modalities in the evaluation of scrotal trauma.

Deep embedded clustering of coral reef bioacoustics.

Deep clustering was applied to unlabeled, automatically detected signals in a coral reef soundscape to distinguish fish pulse calls from segments of whale song. Deep embedded clustering (DEC) learned latent features and formed classification clusters using fixed-length power spectrograms of the signals. Handpicked spectral and temporal features were also extracted and clustered with Gaussian mixture models (GMM) and conventional clustering. DEC, GMM, and conventional clustering were tested on simulated datasets of fish pulse calls (fish) and whale song units (whale) with randomized bandwidth, duration, and SNR. Both GMM and DEC achieved high accuracy and identified clusters with fish, whale, and overlapping fish and whale signals. Conventional clustering methods had low accuracy in scenarios with unequal-sized clusters or overlapping signals. Fish and whale signals recorded near Hawaii in February-March 2020 were clustered with DEC, GMM, and conventional clustering. DEC features demonstrated the highest accuracy of 77.5% on a small, manually labeled dataset for classifying signals into fish and whale clusters.

Automated two-dimensional localization of underwater acoustic transient impulses using vector sensor image processing (vector sensor localization).

Detecting acoustic transients by signal-to-noise ratio (SNR) becomes problematic in nonstationary ambient noise environments characteristic of coral reefs. An alternate approach presented here uses signal directionality to automatically detect and localize transient impulsive sounds collected on underwater vector sensors spaced tens of meters apart. The procedure, which does not require precise time synchronization, first constructs time-frequency representations of both the squared acoustic pressure (spectrogram) and dominant directionality of the active intensity (azigram) on each sensor. Within each azigram, sets of time-frequency cells associated with transient energy arriving from a consistent azimuthal sector are identified. Binary image processing techniques then link sets that share similar duration and bandwidth between different sensors, after which the algorithm triangulates the source location. Unlike most passive acoustic detectors, the threshold criterion for this algorithm is bandwidth instead of pressure magnitude. Data collected from shallow coral reef environments demonstrate the algorithm's ability to detect SCUBA bubble plumes and consistent spatial distributions of somniferous fish activity. Analytical estimates and direct evaluations both yield false transient localization rates from 3% to 6% in a coral reef environment. The SNR distribution of localized pulses off Hawaii has a median of 7.7 dB and interquartile range of 7.1 dB.

Incidence of mosaicism in 1055 de novo NF2 cases: much higher than previous estimates with high utility of next-generation sequencing.

PURPOSE: To evaluate the incidence of mosaicism in de novo neurofibromatosis 2 (NF2). METHODS: Patients fulfilling NF2 criteria, but with no known affected family member from a previous generation (n = 1055), were tested for NF2 variants in lymphocyte DNA and where available tumor DNA. The proportion of individuals with a proven or presumed mosaic NF2 variant was assessed and allele frequencies of identified variants evaluated using next-generation sequencing. RESULTS: The rate of proven/presumed mosaicism was 232/1055 (22.0%). However, nonmosaic heterozygous pathogenic variants were only identified in 387/1055 (36.7%). When variant detection rates in second generation nonmosaics were applied to de novo cases, we assessed the overall probable mosaicism rate to be 59.7%. This rate differed by age from 21.7% in those presenting with bilateral vestibular schwannoma <20 years to 80.7% in those aged ≥60 years. A mosaic variant was detected in all parents of affected children with a single-nucleotide pathogenic NF2 variant. CONCLUSION: This study has identified a very high probable mosaicism rate in de novo NF2, probably making NF2 the condition with the highest expressed rate of mosaicism in de novo dominant disease that is nonlethal in heterozygote form. Risks to offspring are small and probably correlate with variant allele frequency detected in blood.

Ultrasound evaluation of varicoceles: guidelines and recommendations of the European Society of Urogenital Radiology Scrotal and Penile Imaging Working Group (ESUR-SPIWG) for detection, classification, and grading.

Varicoceles are relatively common particularly in asymptomatic men and are even more prevalent in subfertile men, representing the most common potentially correctable cause of male infertility. Ultrasound (US) is the imaging modality of choice for varicocele evaluation, but there is no widely accepted consensus on examination technique, diagnostic criteria, or classification. In view of this uncertainty, the guideline writing group (WG) of the European Society of Urogenital Radiology (ESUR) Scrotal and Penile Imaging Working Group (ESUR-SPIWG) undertook a literature review and assessment of the quality of relevant evidence. The group then produced evidence-based recommendations for varicocele US examination, interpretation, and classification by consensus agreement. The results are presented in the form of 15 clinical questions with a brief summary of the relevant evidence and the authorised recommendations from the SPIWG. This paper provides a short summary of the evidence evaluation and the complete recommendations.Key Points• Varicocele is a common clinical problem; it is highly prevalent amongst subfertile men and the most common potentially correctable cause of male infertility. • Ultrasound is the imaging modality of choice for varicocele assessment, but there is no generally agreed consensus on the US examination technique or the criteria that should be used for diagnosis, grading, and classification. • This paper summarises the recommendations of the ESUR-SPIWG for standardising the US assessment of varicoceles. This includes examination technique, image interpretation, classification, and reporting.

The magnetic resonance imaging appearances of the interureteric crest of the urinary bladder.

PURPOSE: This study was devised to evaluate the imaging appearances of the interureteric crest (IUC) of the bladder on magnetic resonance imaging (MRI). The primary objective was to determine how commonly the IUC was observed on pelvic MRI examinations. The secondary objectives were to determine the average size of the IUC, its MRI signal characteristics and whether there is variation between men and women. By defining the imaging findings we hope to prevent misinterpretation of normal anatomy on MRI and, therefore, prevent unnecessary further investigations and procedures. METHODS: We retrospectively reviewed 114 adult patient's magnetic resonance imaging examinations of the pelvis. Two readers independently recorded information about the presence and characteristics of the IUC with a third reader used to arbitrate in cases of disagreement. RESULTS: The IUC was demonstrated on MRI in 75% of patients. It was best observed on T2w sequences as a continual ridge of low signal intensity between the ureters. The mean AP diameter of the IUC at its mid-point on the sagittal images was 2.4 mm. CONCLUSIONS: The IUC is often seen on MRI on T2w images of a non-collapsed bladder. Its characteristic appearance can be used to help the reporting radiologist confidently differentiate identify this normal structure from an area of focal bladder wall thickening that might be misinterpreted as a bladder tumor.

Identifying the deficiencies of current diagnostic criteria for neurofibromatosis 2 using databases of 2777 individuals with molecular testing.

PURPOSE: We have evaluated deficiencies in existing diagnostic criteria for neurofibromatosis 2 (NF2). METHODS: Two large databases of individuals fulfilling NF2 criteria (n = 1361) and those tested for NF2 variants with criteria short of diagnosis (n = 1416) were interrogated. We assessed the proportions meeting each diagnostic criterion with constitutional or mosaic NF2 variants and the positive predictive value (PPV) with regard to definite diagnosis. RESULTS: There was no evidence for usefulness of old criteria "glioma" or "neurofibroma." "Ependymoma" had 100% PPV and high levels of confirmed NF2 diagnosis (67.7%). Those with bilateral vestibular schwannoma (VS) alone aged ≥60 years had the lowest confirmation rate (6.6%) and reduced PPV (80%). Siblings as a first-degree relative, without an affected parent, had 0% PPV. All three individuals with unilateral VS and an affected sibling were proven not to have NF2. The biggest overlap was with LZTR1-associated schwannomatosis. In this category, seven individuals with unilateral VS plus ≥2 nondermal schwannomas reduced PPV to 67%. CONCLUSIONS: The present study confirms important deficiencies in NF2 diagnostic criteria. The term "glioma" should be dropped and replaced by "ependymoma." Similarly "neurofibroma" should be removed. Dropping "sibling" from first-degree relatives should be considered and testing of LZTR1 should be recommended for unilateral VS.

Capacitive Bio-Inspired Flow Sensing Cupula.

Submersible robotics have improved in efficiency and versatility by incorporating features found in aquatic life, ranging from thunniform kinematics to shark skin textures. To fully realize these benefits, sensor systems must be incorporated to aid in object detection and navigation through complex flows. Again, inspiration can be taken from biology, drawing on the lateral line sensor systems and neuromast structures found on fish. To maintain a truly soft-bodied robot, a man-made flow sensor must be developed that is entirely complaint, introducing no rigidity to the artificial "skin." We present a capacitive cupula inspired by superficial neuromasts. Fabricated via lost wax methods and vacuum injection, our 5 mm tall device exhibits a sensitivity of 0.5 pF/mm (capacitance versus tip deflection) and consists of room temperature liquid metal plates embedded in a soft silicone body. In contrast to existing capacitive examples, our sensor incorporates the transducers into the cupula itself rather than at its base. We present a kinematic theory and energy-based approach to approximate capacitance versus flow, resulting in equations that are verified with a combination of experiments and COMSOL simulations.

An unusual pelvic mass: Contrast-enhanced sonographic diagnosis of pelvic splenosis.

Splenosis is an unusual condition representing auto-transplantation of splenic tissue following splenic trauma or surgery. When detected on imaging studies, the splenosis deposits are usually misinterpreted as pathological masses. We present a case where a pelvic mass incidentally visualized on an MRI examination, was proven to represent a deposit of splenosis by contrast enhanced ultrasound (CEUS). CEUS demonstrated persistent late-phase enhancement characteristic of splenic tissue. Ultrasound practitioners should be aware of this condition when an unusual abdominal or pelvic mass is encountered in a patient with a history of splenic trauma or surgery. CEUS is ideally suited to confirming the diagnosis.

Schwannomatosis: a genetic and epidemiological study.

OBJECTIVES: Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2. METHODS: Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.8 million) and from across the UK. Point prevalence and birth incidence were calculated from regional birth statistics. Genetic analysis was also performed on NF2, LZTR1 and SMARCB1 on blood and tumour DNA samples when available. RESULTS: Regional prevalence for schwannomatosis and NF2 were 1 in 126 315 and 50 500, respectively, with calculated birth incidences of 1 in 68 956 and 1 in 27 956. Mosaic NF2 causes a substantial overlap with schwannomatosis resulting in the misdiagnosis of at least 9% of schwannomatosis cases. LZTR1-associated schwannomatosis also causes a small number of cases that are misdiagnosed with NF2 (1%-2%), due to the occurrence of a unilateral vestibular schwannoma. Patients with schwannomatosis had lower numbers of non-vestibular cranial schwannomas, but more peripheral and spinal nerve schwannomas with pain as a predominant presenting symptom. Life expectancy was significantly better in schwannomatosis (mean age at death 76.9) compared with NF2 (mean age at death 66.2; p=0.004). CONCLUSIONS: Within the highly ascertained North-West England population, schwannomatosis has less than half the birth incidence and prevalence of NF2.

MRI of the scrotum: Recommendations of the ESUR Scrotal and Penile Imaging Working Group.

OBJECTIVES: The Scrotal and Penile Imaging Working Group (SPI-WG) appointed by the board of the European Society of Urogenital Radiology (ESUR) has produced recommendations for magnetic resonance imaging (MRI) of the scrotum. METHODS: The SPI-WG searched for original and review articles published before September 2016 using the Pubmed and Medline databases. Keywords used were 'magnetic resonance imaging', 'testis or testicle or testicular', 'scrotum', 'intratesticular', 'paratesticular', 'extratesticular' 'diffusion-weighted', 'dynamic MRI'. Consensus was obtained among the members of the subcommittee. The expert panel proposed recommendations using Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence. RESULTS: The recommended MRI protocol should include T1-, T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced MRI. Scrotal MRI can be clinically applied for lesion characterisation (primary), including both intratesticular and paratesticular masses, differentiation between germ-cell and non-germ-cell neoplasms (evolving), characterisation of the histological type of testicular germ cell neoplasms (TGCNs, in selected cases), local staging of TGCNs (primary), acute scrotum (in selected cases), trauma (in selected cases) and undescended testes (primary). CONCLUSIONS: The ESUR SPI-WG produced this consensus paper in which the existing literature on MRI of the scrotum is reviewed. The recommendations for the optimal imaging technique and clinical indications are presented. KEY POINTS: • This report presents recommendations for magnetic resonance imaging (MRI) of the scrotum. • Imaging acquisition protocols and clinical indications are provided. • MRI is becoming established as a worthwhile second-line diagnostic tool for scrotal pathology.

Beamforming using chip-scale atomic clocks in a controlled environment.

Recently developed low-power Chip-Scale Atomic Clocks (CSACs) hold promise for underwater acoustics applications because they enable time-coherent processing, critical for estimating the directionality of the sound field, when acoustic array elements cannot share a timing reference. Controlled, tank-based experiments with a small acoustic array (N = 4) featuring CSAC-equipped elements show that optimal disciplining is important for continued array coherence. Clock drift equivalent to a 10% wavelength error at 0.3, 1, and 10 kHz was reached at approximately 25, 10, and 3 days, respectively. Within application-specific limits, this technology brings enhanced capabilities to acoustic thermometry, geoacoustic, biological, and under-ice acoustic oceanography.

The EFSUMB Guidelines and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound (CEUS) in Non-Hepatic Applications: Update 2017 (Long Version).

The updated version of the EFSUMB guidelines on the application of non-hepatic contrast-enhanced ultrasound (CEUS) deals with the use of microbubble ultrasound contrast outside the liver in the many established and emerging applications.

The EFSUMB Guidelines and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound (CEUS) in Non-Hepatic Applications: Update 2017 (Short Version).

The updated version of the EFSUMB guidelines on the application of non-hepatic contrast-enhanced ultrasound (CEUS) deals with the use of microbubble ultrasound contrast outside the liver in the many established and emerging applications.