Associating HIV-1 envelope glycoprotein structures with states on the virus observed by smFRET.

The HIV-1 envelope glycoprotein (Env) trimer mediates cell entry and is conformationally dynamic1-8. Imaging by single-molecule fluorescence resonance energy transfer (smFRET) has revealed that, on the surface of intact virions, mature pre-fusion Env transitions from a pre-triggered conformation (state 1) through a default intermediate conformation (state 2) to a conformation in which it is bound to three CD4 receptor molecules (state 3)8-10. It is currently unclear how these states relate to known structures. Breakthroughs in the structural characterization of the HIV-1 Env trimer have previously been achieved by generating soluble and proteolytically cleaved trimers of gp140 Env that are stabilized by a disulfide bond, an isoleucine-to-proline substitution at residue 559 and a truncation at residue 664 (SOSIP.664 trimers)5,11-18. Cryo-electron microscopy studies have been performed with C-terminally truncated Env of the HIV-1JR-FL strain in complex with the antibody PGT15119. Both approaches have revealed similar structures for Env. Although these structures have been presumed to represent the pre-triggered state 1 of HIV-1 Env, this hypothesis has never directly been tested. Here we use smFRET to compare the conformational states of Env trimers used for structural studies with native Env on intact virus. We find that the constructs upon which extant high-resolution structures are based predominantly occupy downstream conformations that represent states 2 and 3. Therefore, the structure of the pre-triggered state-1 conformation of viral Env that has been identified by smFRET and that is preferentially stabilized by many broadly neutralizing antibodies-and thus of interest for the design of immunogens-remains unknown.

3D printed chamber for live cell imaging on an upright epifluorescence microscope.

Live cell imaging is a standard technique in experimental biology that enables the observation of isolated cells and tissue slices in real time; and the testing of cellular responses to changes in buffer composition. However, most live cell imaging devices require the use of dedicated microscopes and/or specialized stage adaptors, and come at a reasonably high cost. We employed 3D printing technology to create a low-cost imaging chamber with side ports to exchange fluids, to be used on upright microscopes. The chamber increased the functionality of a standard upright epifluorescent microscope to allow dynamic, real-time calcium imaging of cultured hypothalamic astrocytes from mice, and to test the effects of ATP stimulation upon calcium signaling. It was also used on slices obtained from mouse brain using a brain matrix slicer. The advantages of this chamber include a very simple design that can be used with upright epifluorescence microscopes, does not require any special stage adaptor, and includes ports to permit fluid exchange during imaging. This chamber is ideal for educational settings with undergraduate laboratories that do not have access to dedicated inverted fluorescent microscopes for tissue culture experiments.

Dietary fatty acids and endometrial cancer risk within the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: Diet may impact important risk factors for endometrial cancer such as obesity and inflammation. However, evidence on the role of specific dietary factors is limited. We investigated associations between dietary fatty acids and endometrial cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). METHODS: This analysis includes 1,886 incident endometrial cancer cases and 297,432 non-cases. All participants were followed up for a mean of 8.8 years. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) of endometrial cancer across quintiles of individual fatty acids estimated from various food sources quantified through food frequency questionnaires in the entire EPIC cohort. The false discovery rate (q-values) was computed to control for multiple comparisons. RESULTS: Consumption of n-6 γ-linolenic acid was inversely associated with endometrial cancer risk (HR comparing 5th with 1st quintileQ5-Q1=0.77, 95% CI = 0.64; 0.92, ptrend=0.01, q-value = 0.15). This association was mainly driven by γ-linolenic acid derived from plant sources (HRper unit increment=0.94, 95%CI= (0.90;0.98), p = 0.01) but not from animal sources (HRper unit increment= 1.00, 95%CI = (0.92; 1.07), p = 0.92). In addition, an inverse association was found between consumption of n-3 α-linolenic acid from vegetable sources and endometrial cancer risk (HRper unit increment= 0.93, 95%CI = (0.87; 0.99), p = 0.04). No significant association was found between any other fatty acids (individual or grouped) and endometrial cancer risk. CONCLUSION: Our results suggest that higher consumption of γ-linolenic acid and α-linoleic acid from plant sources may be associated with lower risk of endometrial cancer.

The effect of clinical history on diagnostic performance of endodontic cone-beam CT interpretation.

AIM: To assess the effect of clinical history on the interpretation of endodontic disease in dental cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A reader performance study of an image test-set was undertaken using a factorial, free-response, crossover design, accounting for the independent variables: case type, case severity, reader type, and reading modality. Twenty-three readers interpreted 60 CBCT images twice over two reading sessions using a balanced design, once with access to clinical history and once without, where 30 in each session included history. Lesion localisations, specificity, false-positive marks and the weighted alternative free-response receiver operating characteristic (wAFROC1) figure of merit were calculated. RESULTS: Clinical history had no significant effect on specificity and false-positive rates in non-diseased cases (p>0.05), but improved lesion localisation in subtle and obvious diseased cases (p<0.01). wAFROC1 values were higher with clinical history for subtle (0.58 versus 0.48; p<0.001) and obvious (0.77 versus 0.71; p=0.006) diseased categories. No associations were observed between clinical history and both readers' years of experience and reading volume in the non-diseased categories. Readers with fewer (p=0.03) and moderate (p=0.008) years of experience and low (p=0.002) CBCT reading volume demonstrated better lesion localisation in subtle diseased cases when clinical history was available. CONCLUSIONS: Clinical history improved the interpretation of CBCT images with disease without affecting the interpretation of images without disease. Less and moderately experienced readers and low-volume readers benefitted more from availability of clinical history.

Test-set training improves the detection rates of invasive cancer in screening mammography.

AIM: To investigate if mammographic test-set participation affects routine breast cancer screening performance. MATERIALS AND METHODS: Clinical audit data between 2008 and 2018 were collected for 35 breast screen readers who participated in the BreastScreen Reader Assessment Strategy (BREAST) and 22 readers with no history of test-set participation. For BREAST readers, the annual audit data were divided according to the year they completed their first test set, and the same years were used randomly to align and divide the data of non-BREAST readers into pre- and post-test set periods. Multiple audit parameters were inspected retrospectively for the two cohorts to identify how their reading performance has evolved in screening mammography. RESULTS: Investigating 2 calendar years before and after test-set participation, BREAST and non-BREAST readers recalled lower rates of women in the latter period (p=0.03 and p=0.02, respectively). They also improved their positive predictive value (PPV; p=0.01 and p=0.02, respectively). BREAST readers additionally improved their detection rates of invasive cancer (p=0.02) and all cancers (p=0.01). In an extended 3-year comparison, similar improvements occurred in the recall rate for BREAST (p=0.02) and non-BREAST readers (p=0.02) and in PPV (p=0.001, 0.01, respectively); however, improvements in detection rates also occurred exclusively in BREAST readers' performance for invasive cancer (p=0.04), DCIS (p=0.05), and all cancers (p=0.02); however, significant improvements in detection did not involve <15 mm invasive cancers in both periods. Meanwhile, non-BREAST readers demonstrated a decrease in sensitivity (p=0.02). CONCLUSION: Participation in test sets is linked to over-time improvements in most audit-measured cancer detection rates.

Clinical performance progress of BREAST participants: the impact of test-set participation.

AIM: To investigate if positive changes in the clinical performance of radiologists are associated with reading mammographic test sets. MATERIALS AND METHODS: This study investigated the clinical audit history for a cohort of 39 participants in the BreastScreen Reader Assessment Strategy who have read for BreastScreen New South Wales in the period between 2010 and 2018, inclusively. Based on the year in which each radiologist completed his or her first test set, data of multiple clinical audit metrics from two calendar years before test-set reading were compared against similar data from three different periods after test-set completion. The same process was repeated after dividing radiologists into two subgroups based on their median screen-reading volume (3,688), to test if experience is a determinant of post-test set performance. RESULTS: On average, radiologists showed significant improvements (p<0.05) in the recall rate for subsequent screening rounds, in positive predictive value 1 (PPV1), and in specificity. When dividing radiologists based on their average annual reading volume, radiologists with higher reading numbers demonstrated similar significant improvements in the recall rate and in PPV1. In addition, they showed significant improvements in the detection rates of invasive breast cancer and ductal carcinoma in situ (DCIS). In contrast, the radiologists with lower reading volume indicated significant changes in the recall rate and in PPV1, both accruing in one of the three compared periods. CONCLUSION: Mammographic test-set participants improve over time in identifying normal breast screens and detecting breast cancer in association with reading higher volumes of breast screening cases.

A cross-sectional study examining the association between MRCS performance and surgeons receiving sanctions against their medical registration.

BACKGROUND: Fitness to practice (FtP) investigations by the General Medical Council (GMC) safeguard patients and maintain the integrity of the medical profession. The likelihood of FtP sanctions is influenced by specialty and socio-demographic factors and can be predicted by performance at postgraduate examinations. This is the first study to characterise the prevalence of FtP sanctions in early-career surgeons and to examine the association with performance at the Membership of the Royal College of Surgeons (MRCS) examination. METHODS: All UK graduates who attempted MRCS between September 2007-January 2020 were matched to the GMC list of registered medical practitioners. Clinicians who had active FtP sanctions between 28th August 2018 and 28th August 2020 were identified. Data were anonymised by RCS England prior to analysis. RESULTS: Of 11,660 candidates who attempted MRCS within the study period, only 31 (0.3%) had FtP sanctions between 2018 and 2020. Of these, 12 had active conditions on registration, seven had undertakings and 14 had warnings. There was no statistically significant difference in MRCS performance in either Parts A or B of the examination for those with and those free from FtP sanctions (P > 0.05). CONCLUSIONS: In this, the largest study of MRCS candidates to date, the prevalence of active FtP sanctions in early-career surgeons was 0.3%, significantly lower than the prevalence of sanctions across more experienced UK surgeons (0.9%). These data highlight early-career surgeons as a low-risk group for disciplinary action and should reassure patients and medical professionals of the rarity of FtP sanctions.

Second surgery for progressive glioblastoma: a multi-centre questionnaire and cohort-based review of clinical decision-making and patient outcomes in current practice.

PURPOSE: Glioblastoma prognosis is poor. Treatment options are limited at progression. Surgery may benefit, but no quality guidelines exist to inform patient selection. We sought to describe variations in surgical management at progression, highlight where further evidence is needed, and build towards a consensus strategy. METHODS: Current practice in selection of patients with progressive GBM for second surgery was surveyed online amongst specialists in the UK and Europe. We complemented this with an assessment of practice in a retrospective cohort study from six United Kingdom neurosurgical units. We used descriptive statistics to analyse the data. RESULTS: 234 questionnaire responses were received. Maintaining or improving patient quality of life was key to decision making, with variation as to whether patient age, performance status or intended extent of resection was relevant. MGMT methylation status was not important. Half considered no minimum time after first surgery. 288 patients were reported in the cohort analysis. Median time to second surgery from first surgery 390 days. Median overall survival 815 days, with no association between time to second surgery and time to death (p = 0.874). CONCLUSIONS: This is the most wide-ranging examination of contemporaneous practice in management of GBM progression. Without evidence-based guidelines, the variation is unsurprising. We propose consensus guidelines for consideration, to reduce heterogeneity in decision making, support data collection and analysis of factors influencing outcomes, and to inform clinical trials to establish whether second surgery improves patient outcomes, or simply selects to patients already performing well.

Fire safety and emergency evacuation guidelines for intensive care units and operating theatres: for use in the event of fire, flood, power cut, oxygen supply failure, noxious gas, structural collapse or other critical incidents: Guidelines from the Association of Anaesthetists and the Intensive Care Society.

The need to evacuate an ICU or operating theatre complex during a fire or other emergency is a rare event but one potentially fraught with difficulty: Not only is there a risk that patients may come to harm but also that staff may be injured and unable to work. Designing newly-built or refurbished ICUs and operating theatre suites is an opportunity to incorporate mandatory fire safety features and improve the management and outcomes of such emergencies: These include well-marked manual fire call points and oxygen shut off valves (area valve service units); the ability to isolate individual zones; multiple clear exit routes; small bays or side rooms; preference for ground floor ICU location and interconnecting routes with operating theatres; separate clinical and non-clinical areas. ICUs and operating theatre suites should have a bespoke emergency evacuation plan and route map that is readily available. Staff should receive practical fire and evacuation training in their clinical area of work on induction and annually as part of mandatory training, including 'walk-through practice' or simulation training and location of manual fire call points and fire extinguishers, evacuation routes and location and operation of area valve service units. The staff member in charge of each shift should be able to select and operate fire extinguishers and lead an evacuation. Following an emergency evacuation, a network-wide response should be activated, including retrieval and transport of patients to other ICUs if needed. A full investigation should take place and ongoing support and follow-up of staff provided.

Visual Sequence Repetition Learning is Not Impaired in Signing DHH Children.

The auditory scaffolding hypothesis states that early experience with sound underpins the development of domain-general sequence processing abilities, supported by studies observing impaired sequence processing in deaf or hard-of-hearing (DHH) children. To test this hypothesis, we administered a sequence processing task to 77 DHH children who use American Sign Language (ASL) and 23 hearing monolingual children aged 7-12 years and found no performance difference between them after controlling for age and nonverbal intelligence. Additionally, neither spoken language comprehension scores nor hearing loss levels predicted sequence processing scores in the DHH group, whereas ASL comprehension scores did. Our results do not indicate sequence processing deficits in DHH children and do not support the auditory scaffolding hypothesis; instead, these findings suggest that factors related to experience with and/or proficiency in an accessible language during development may be more important determinants of sequence processing abilities.

Interdependence of physical and psychological morbidity among patients with cancer and family caregivers: Review of the literature.

OBJECTIVE: Caregivers for patients with cancer have an integral role in maintaining patients' health. Although patients and caregivers experience the impact of cancer individually, studies suggest their health is interdependent. The objective of this review was to synthesize the literature on interdependent physical and psychological morbidity in patient-caregiver dyads published since 2016. METHODS: A search of PubMed, CINAHL, Embase, and PsycInfo databases was performed using Cooper's recommendations and the Preferred Reporting Items for Systematic Reviews And Meta-Analyses Guidelines. Studies were included if they measured individual physical or psychological morbidity in cancer patient-caregiver dyads, evaluated interdependence, and were published in a peer-reviewed journal. RESULTS: Twenty-three studies met criteria, characterized by mainly spousal dyads. Studies included a variety of cancers and methodologies. Findings were inconsistent, indicating varying interdependence. However, the studies demonstrated a stronger relationship between patients' and caregivers' psychological morbidity than between their physical morbidity. CONCLUSIONS: This review revealed a need for continued exploration of dyadic health interdependence. Future studies should consider samples of patients with a single type of cancer, testing cultural mediators/moderators, and using longitudinal designs.

The roles of clinical audit and test sets in promoting the quality of breast screening: a scoping review.

Breast screening programmes enhance the probability of early breast cancer detection in many countries worldwide; however, the success of these efforts is highly dependent on the ability of breast screen readers to detect abnormalities in the screened population, which has low prevalence. Therefore, this task can be challenging. Clinical audit is a key quality assurance measure that aims to keep the screen reading performance within acceptable standards. Auditing, nonetheless, is a lengthy process, and its accuracy is dependent on available clinical data, which often can be limited. Mammographic standardised test sets are a different screen reading evaluation approach that provides participants with instant feedback based on a simulated environment. Although a test set provides unique evaluative qualities, its ability to represent clinical performance is debated. This article describes the distinctive roles of clinical audit and test sets in measuring and improving the quality of breast screening and highlights the relationship between test sets and clinical performance.

Effects of time of day on radiological interpretation.

Accurate interpretation of radiological images involves a complex visual search that relies on several cognitive processes, including selective attention, working memory, and decision-making. Patient outcomes often depend on the accuracy of image interpretations, and yet research has revealed that conclusions vary significantly from one radiologist to another. A myriad of factors has been shown to contribute to the likelihood of interpretative errors and discrepancies, including the radiologist's level of experience and fatigue, and these factors are well reported elsewhere; however, a potentially important factor that has been given little previous consideration is how radiologists' interpretations might be impacted by the time of day at which the reading takes place, a factor that other disciplines have shown to be a determinant of competency. The available literature shows that while the time of day is known to significantly impact some cognitive functions that likely relate to reading competence, including selective visual attention and visual working memory, little is known about the impact of the time of day on radiology interpretation performance. This review explores the evidence regarding the relationship between time of day and performance, with a particular emphasis on radiological activities.

Impact of time of day on radiology image interpretations.

AIM: To examine the impact of the time of day on radiologists' mammography reading performance. MATERIALS AND METHODS: Retrospective mammographic reading assessment data were collected from the BreastScreen Reader Assessment Strategy database and included timestamps of the readings and reader-specific demographic data of 197 radiologists. The radiologists performed the readings in a workshop setting with test case sets enriched with malignancies (one-third of cases were malignant). The collected data were evaluated with an analysis of covariance to determine whether time of day influenced radiologists' specificity, lesion sensitivity or the jackknife alternative free-response receiver operating characteristic (JAFROC). RESULTS: After adjusting for radiologist experience and fellowship, specificity varied significantly by time of day (p=0.027), but there was no evidence of any significant impact on lesion sensitivity (p=0.441) or JAFROC (p=0.120). The collected data demonstrated that specificity during the late morning (10.00-12.00) was 71.7%; this was significantly lower than in the early morning (08.00-10.00) and mid-afternoon (14.00-16.00), which were 82.74% (p=0.003) and 81.39% (p=0.031), respectively. Specificity during the late afternoon (16.00-18.00) was 73.95%; this was significantly lower than in the early morning (08.00-10.00) and mid-afternoon (14.00-16.00), which were 82.74% (p=0.003) and 81.39% (p=0.031), respectively. CONCLUSION: The results indicated that the time of day may influence radiologists' performance, specifically their ability to identify normal images correctly.

Reversible cerebral vasoconstrictive syndrome preceded by minor head trauma.

Reversible cerebral vasoconstriction syndrome is a heterogeneous and under-recognised neurovascular disorder. Our knowledge with regards to specific syndrome triggers and optimal management is limited. The delay in diagnosis can be deleterious to the patient due to intracerebral sequelae causing temporary or permanent morbidity. Prompt identification of this syndrome is vital to reverse neurological deficits while appropriately managing and supporting patient recovery.

Meeting report from the joint IARC-NCI international cancer seminar series: a focus on colorectal cancer.

Despite significant progress in our understanding of the etiology, biology and genetics of colorectal cancer, as well as important clinical advances, it remains the third most frequently diagnosed cancer worldwide and is the second leading cause of cancer death. Based on demographic projections, the global burden of colorectal cancer would be expected to rise by 72% from 1.8 million new cases in 2018 to over 3 million in 2040 with substantial increases anticipated in low- and middle-income countries. In this meeting report, we summarize the content of a joint workshop led by the National Cancer Institute and the International Agency for Research on Cancer, which was held to summarize the important achievements that have been made in our understanding of colorectal cancer etiology, genetics, early detection and treatment and to identify key research questions that remain to be addressed.

Vitamin B6 catabolism and lung cancer risk: results from the Lung Cancer Cohort Consortium (LC3).

BACKGROUND: Increased vitamin B6 catabolism related to inflammation, as measured by the PAr index (the ratio of 4-pyridoxic acid over the sum of pyridoxal and pyridoxal-5'-phosphate), has been positively associated with lung cancer risk in two prospective European studies. However, the extent to which this association translates to more diverse populations is not known. MATERIALS AND METHODS: For this study, we included 5323 incident lung cancer cases and 5323 controls individually matched by age, sex, and smoking status within each of 20 prospective cohorts from the Lung Cancer Cohort Consortium. Cohort-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between PAr and lung cancer risk were calculated using conditional logistic regression and pooled using random-effects models. RESULTS: PAr was positively associated with lung cancer risk in a dose-response fashion. Comparing the fourth versus first quartiles of PAr resulted in an OR of 1.38 (95% CI: 1.19-1.59) for overall lung cancer risk. The association between PAr and lung cancer risk was most prominent in former smokers (OR: 1.69, 95% CI: 1.36-2.10), men (OR: 1.60, 95% CI: 1.28-2.00), and for cancers diagnosed within 3 years of blood draw (OR: 1.73, 95% CI: 1.34-2.23). CONCLUSION: Based on pre-diagnostic data from 20 cohorts across 4 continents, this study confirms that increased vitamin B6 catabolism related to inflammation and immune activation is associated with a higher risk of developing lung cancer. Moreover, PAr may be a pre-diagnostic marker of lung cancer rather than a causal factor.

Timing of HPV16-E6 antibody seroconversion before OPSCC: findings from the HPVC3 consortium.

BACKGROUND: Human papillomavirus type 16 (HPV16)-E6 antibodies are detectable in peripheral blood before diagnosis in the majority of HPV16-driven oropharyngeal squamous cell carcinoma (OPSCC), but the timing of seroconversion is unknown. PATIENTS AND METHODS: We formed the HPV Cancer Cohort Consortium which comprises nine population cohorts from Europe, North America and Australia. In total, 743 incident OPSCC cases and 5814 controls provided at least one pre-diagnostic blood sample, including 111 cases with multiple samples. Median time between first blood collection and OPSCC diagnosis was 11.4 years (IQR = 6-11 years, range = 0-40 years). Antibodies against HPV16-E6 were measured by multiplex serology (GST fusion protein based Luminex assay). RESULTS: HPV16-E6 seropositivity was present in 0.4% of controls (22/5814; 95% CI 0.2% to 0.6%) and 26.2% (195/743; 95% CI 23.1% to 29.6%) of OPSCC cases. HPV16-E6 seropositivity increased the odds of OPSCC 98.2-fold (95% CI 62.1-155.4) in whites and 17.2-fold (95% CI 1.7-170.5) in blacks. Seropositivity in cases was more frequent in recent calendar periods, ranging from 21.9% pre-1996 to 68.4% in 2005 onwards, in those with blood collection near diagnosis (lead time <5 years). HPV16-E6 seropositivity increased with lead time: 0.0%, 13.5%, 23.7%, and 38.9% with lead times of >30 years (N = 24), 20-30 years (N = 148), 10-20 years (N = 228), and <10 years (N = 301 cases) (p-trend < 0.001). Of the 47 HPV16-E6 seropositive cases with serially-collected blood samples, 17 cases seroconverted during follow-up, with timing ranging from 6 to 28 years before diagnosis. For the remaining 30 cases, robust seropositivity was observed up to 25 years before diagnosis. CONCLUSIONS: The immune response to HPV16-driven tumorigenesis is most often detectable several decades before OPSCC diagnosis. HPV16-E6 seropositive individuals face increased risk of OPSCC over several decades.

Radiologist performance in the detection of lung cancer using CT.

AIM: To measure the level of radiologists' performance in lung cancer detection, and to explore radiologists' performance in cancer specialised and non-specialised centres. MATERIALS AND METHODS: Thirty radiologists read 60 chest computed tomography (CT) examinations. Thirty cases had surgically or biopsy-proven lung cancer and 30 were cancer-free cases. The cancer cases were validated by four expert radiologists who located the malignant lung nodules. Reader performance was evaluated by calculating sensitivity, location sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (AUC). In addition, sensitivity at fixed specificity (0.794) was computed from each reader's estimated ROC curve. RESULTS: The radiologists had a mean sensitivity of 0.749, sensitivity at fixed specificity of 0.744, location sensitivity of 0.666, specificity of 0.81 and AUC of 0.846. Radiologists in the specialised and non-specialised cancer centres had the following (specialised, non-specialised) pairs of values: sensitivity=(0.80, 0.719); sensitivity for fixed 0.794 specificity=(0.752, 0.740); location sensitivity=(0.712, 0.637); specificity=(0.794, 0.82) and AUC=(0.846, 0.846). CONCLUSION: The efficacy of radiologists was comparable to other studies. Furthermore, AUC outcomes were similar for specialised and non-specialised cancer centre radiologists, suggesting they have similar discriminatory ability and that the higher sensitivity and lower specificity for specialised-centre radiologists can be attributed to them being less conservative in interpreting case images.

A quantitative analysis of CT angiography, large vessel occlusion, and thrombectomy rates in acute ischaemic stroke.

AIMS: To determine the workload of acute computed tomography angiography (CTA) in patients presenting with suspected acute ischaemic stroke (AIS) and rate of large vessel occlusion (LVO) and thrombectomy relative to suspected and confirmed stroke diagnoses across three stroke centres within the Republic of Ireland. MATERIALS AND METHODS: A retrospective review of data from three stroke centres, one of which provides a 24-hour thrombectomy service was undertaken. The number of CTA studies performed from January 2015 to December 2017 for suspected AIS was quantified using the national PACS in addition to occlusion location, collateral status, and rates of LVO and thrombectomy. The hospital inpatient enquiry (HIPE) system was searched for all patients with a primary discharge diagnosis of stroke and then correlated with patients who underwent CTA on admission. RESULTS: A total of 2,358 CTA studies were performed for suspected AIS during the study period across three stroke centres. LVO was demonstrated in 18.4% of suspected AIS, 18.4% of primary discharge stroke diagnoses, and 40.2% of confirmed AIS who underwent CTA. A total of 283 thrombectomies were performed of which 64.6% were LVO. Thrombectomy was performed in 12% of suspected AIS, 12% of overall primary discharge diagnoses of stroke cases, and 26% of confirmed stroke who underwent CTA. CONCLUSION: Establishing the volume of acute CTAs and rates of LVO and thrombectomy when compared to suspected AIS on admission, confirmed stroke diagnoses who underwent CTA and primary discharge diagnosis of stroke is essential for the planning and provision of stroke services worldwide.