Threshold Volume Research Articles

Simultaneous Confidence Regions for Image Excursion Sets: a Validation Study with Applications in fMRI.

Functional Magnetic Resonance Imaging (fMRI) is commonly used to localize brain regions activated during a task. Methods have been developed for constructing confidence regions of image excursion sets, allowing inference on brain regions exceeding non-zero activation thresholds. However, these methods have been limited to a single predefined threshold and brain volume data, overlooking more sensitive cortical surface analyses. We present an approach that constructs simultaneous confidence regions (SCRs) which are valid for all possible activation thresholds and are applicable to both volume and surface data. This approach is based on a recent method that constructs SCRs from simultaneous confidence bands (SCBs), obtained by using the bootstrap on 1D and 2D images. To extend this method to fMRI studies, we evaluate the validity of the bootstrap with fMRI data through extensive 2D simulations. Six bootstrap variants, including the nonparametric bootstrap and multiplier bootstrap are compared. The Rademacher multiplier bootstrap-t performs the best, achieving a coverage rate close to the nominal level with sample sizes as low as 20. We further validate our approach using realistic noise simulations obtained by resampling resting-state 3D fMRI data, a technique that has become the gold standard in the field. Moreover, our implementation handles data of any dimension and is equipped with interactive visualization tools designed for fMRI analysis. We apply our approach to task fMRI volume data and surface data from the Human Connectome Project, showcasing the method's utility.

Selective correlation of hippocampal volumes with WADA memory scores in mesial temporal sclerosis patients

ObjectiveThe WADA test is used to determine cerebral language dominance and assess the risk of postoperative amnesia following mesial temporal lobe resection. This study aims to explore the correlation between automated measures of hippocampal volume and WADA memory scores and to evaluate whether these volumetric measurements can reliably predict WADA memory scores.MethodsThis study included patients who underwent a comprehensive presurgical assessment along with bilateral WADA testing. Hippocampal volumes were measured from high-resolution brain MRIs using automated software (volBrain), which were harmonized and normalized to whole brain volume. These harmonized and normalized volumes were then correlated with ipsilateral WADA memory scores and stratified according to brain MRI findings. A similar analysis was conducted between hippocampal volume asymmetry and WADA memory score asymmetry (WMA). A Receiver Operating Characteristic (ROC) curve was generated to compare the sensitivity and specificity in predicting successful WADA outcomes based on ipsilateral harmonized normalized hippocampal volumes.ResultsIn patients with mesial temporal sclerosis (MTS), significant positive correlations were found between harmonized normalized hippocampal volumes and ipsilateral WADA memory scores, as well as between harmonized hippocampal volume asymmetries and WMA. However, no significant correlations were found in patients with epileptogenic lesions other than MTS or those with normal brain MRIs. A harmonized normalized hippocampal volume threshold of ≥ 28.94 units was identified as a predictor of a WADA memory score exceeding 50% following contralateral carotid artery injection, with a sensitivity of 62.1% and a specificity of 100%.SignificanceThis study indicates that hippocampal volumetry could potentially serve as an alternative to the WADA test in patients with MTS. Conversely, in individuals with normal MRI results or other types of epileptogenic lesions, hippocampal volumetry does not reliably predict memory deficits, necessitating the use of the WADA test or functional MRI for planning resections of mesial temporal structures in the dominant hemisphere.

Higher hospital volume reduces early failure rates in single-stage revision TKR for infection: An analysis of the United Kingdom National Joint Registry and National Administrative Databases.

Revision knee replacement (RevKR) for infection is rare but increasing. It is hypothesised that higher hospital volume reduces adverse outcomes. The aim was to estimate the association of surgical unit volume with outcomes following first, single-stage RevKR for infection. This population-based cohort study merged data from the United Kingdom National Joint Registry, Hospital Episode Statistics, National Patient Reported Outcome Measures and the Civil Registrations of Death. Patients undergoing procedures between 1 January 2009 and 30 June 2019 were included. Early outcomes were chosen to reflect the quality of the surgical provision and included re-revision at 2 years, mortality, serious medical complications, length of stay and patient-reported outcome measures (PROMs). Adjusted fixed effect multivariable regression models were used to examine the association between surgical unit mean annual caseload and the risk of adverse outcomes. A total of 1477 patients underwent first-time single-stage RevKRs for infection across 267 surgical units and 716 surgeons. Following adjustment for age, gender, American Society of Anaesthesiologists grade, surgeon volume, year of surgery and operation funder and modelling surgical unit volume with restricted cubic spline, a greater mean annual volume was associated with a lower risk of re-revision at 2 years. The odds of re-revision in hospitals performing fewer than or equal to 12 cases per year was 2.53 (95% confidence interval = 1.50-4.31) times more likely than hospitals performing three to four cases per month. Annual variation in surgical unit volume was not associated with mortality and serious medical complications within 90 days. Only 99 out of 1477 (7%) of patients had linked PROMs which precluded subsequent analysis. Overall, higher volume surgical units had lower rates of early re-revision following the first RevKR for infection. We were unable to provide recommended specific volume thresholds for units; however, the probability of re-revision appears to be lowest in the highest volume units. Level III, retrospective cohort study of prospectively collected data.

Predicting acute and late toxicity in prostate cancer stereotactic ablative radiotherapy: the role of dosimetric parameters and prostate volume.

Our objective was to identify the dosimetric parameters and prostate volume that most accurately predict the incidence of acute and late gastrointestinal (GI) and genitourinary (GU) toxicity in prostate cancer stereotactic ablative radiotherapy (SABR) treatments. We conducted aretrospective analysis of 122 patients who received SABR for prostate cancer at our clinic between March 2018 and September 2022 using afive-fraction SABR regimen. The existing plans of these patients were re-evaluated according to our institutional protocols (Hacettepe University [HU-1] and HU-2) as well as PACE‑B, RTOG 0938, and NRG GU005 dose-volume constraints. Univariate and multivariate logistic regression analyses were performed using SPSS version 23.0 (IBM, Armonk, NY, USA). The median follow-up was 24.7 months (0.8-94.4 months). For acute GU toxicity, moderate-dose regions were predictive for grade1-2 toxicity, while high-dose regions were more associated with grade3-4 toxicity. For late GU toxicity, moderate-high-dose regions were predictive. For GI toxicity, moderate-dose regions were important for both acute and late toxicity. The HU protocol encompassed all significant dosimetric factors influencing toxicity outcomes. Aprostate volume threshold of 60 cc was predictive of acute grade3-4 GU toxicity. Our study highlighted the critical role of moderate-dose regions for acute and late GI and GU toxicity. Prostate treatment plans should be rigorously evaluated, and moderate doses should be minimized. The HU protocol is an eligible choice for five-fraction SABR plans.

The Association Between Surgeon Volume and Dislocation After Total Hip Arthroplasty: A Nationwide Evaluation of 5,106 Orthopaedic Surgeons.

The relationship between surgeon volume and risk of dislocation after total hip arthroplasty (THA) is debated. This study sought to characterize this association and assess patient outcomes using a nationwide patient and surgeon registry. The Premier Healthcare Database was queried for adult primary elective THA patients from January 1, 2016, to December 31, 2019. Annual surgeon volume and 90-day risk of dislocation were modeled using multivariable logistic regression with restricted cubic splines. Bootstrap analysis identified a threshold annual case volume, corresponding to the maximum decrease in dislocation risk. Surgeons with an annual volume greater than the threshold were deemed high volume, and those with an annual volume less than the threshold were low volume. Each surgeon within a given year was treated as a unique entity (surgeon-year unit). 90-day complications of patients treated by high-volume and low-volume surgeons were compared. From 2016 to 2019, 352,131 THAs were performed by 5,106 surgeons. The restricted cubic spline model demonstrated an inverse relationship between risk of dislocation and surgeon volume (threshold: 109 cases per year). A total of 9,967 (87.8%) low-volume surgeon-year units had individual dislocation rates lower than the average of the entire surgeon cohort. Patients treated by high-volume surgeons had decreased risk of dislocation (adjusted odds ratio [aOR], 0.60; 95% CI, 0.54 to 0.67), periprosthetic fracture (aOR, 0.87; 95% CI, 0.76 to 0.99), periprosthetic joint infection (aOR, 0.63; 95% CI, 0.56 to 0.69), readmission (aOR, 0.70; 95% CI, 0.67 to 0.73), and in-hospital death (aOR, 0.60; 95% CI, 0.46 to 0.80). While most of the low-volume surgeons had dislocation rates lower than the cohort average, increasing annual surgeon case volume was associated with a reduction in risk of dislocation after primary elective THA. Level IV.

Penumbral Imaging to Guide Endovascular Treatment for M2 Middle Cerebral Artery Stroke.

A potential benefit of mechanical thrombectomy for patients with distal medium vessel occlusions is currently being investigated in randomized trials. Computed tomography perfusion imaging has not yet been tested as a method to guide mechanical thrombectomy for distal medium vessel occlusions. The purpose of this study was to assess penumbral imaging as an imaging-based method for triaging patients with ischemic stroke and acute M2-middle cerebral artery occlusion. This observational retrospective study of M2-middle cerebral artery patients with ischemic stroke triaged by multimodal computed tomography undergoing mechanical thrombectomy at a high-volume stroke center between January 2015 and January 2023. The effect of recanalization was analyzed according to computed tomography perfusion-derived lesion volumes (defined using relative cerebral blood flow <30% and Tmax >6 seconds) using logistic regression analysis, and interaction terms between the independent variables and recanalization were tested. The primary end point was functional independence at day 90, defined using modified Rankin Scale scores of 0 to 2. A total of 140 patients with M2-middle cerebral artery occlusion were included. In multivariable logistic regression analysis, recanalization was not associated with better functional outcome (adjusted odds ratio, 1.85 [95% CI, 0.87-3.90]; P=0.11). After including interaction terms, a significant treatment effect between recanalization and computed tomography perfusion-derived lesion volumes was observed in patients with >150 mL hypoperfusion volume (adjusted odds ratio, 1.02 [95% CI, 1.00-1.03]; P=0.007) or >125 mL penumbral volumes (adjusted odds ratio, 1.02 [95% CI, 1.01-1.03]; P=0.005), as well as for baseline ischemic core volume within the range of 15 to 40 mL (adjusted odds ratio, 1.11 [95% CI, 1.01-1.22]; P=0.03). Penumbral imaging might serve as a useful tool for treatment decision-making in distal medium vessel occlusions, particularly in cases of suspected non- or codominant M2-middle cerebral artery vessel occlusions. A hypoperfusion volume threshold of >150 mL emphasizes the potential value of computed tomography perfusion as a standardized tool directly showing the volumetric relevance in distal medium vessel occlusion cases.

Evaluating conversion from mild cognitive impairment to Alzheimer's disease with structural MRI: a machine learning study.

Alzheimer's disease is a disabling neurodegenerative disorder for which no effective treatment currently exists. To predict the diagnosis of Alzheimer's disease could be crucial for patients' outcome, but current Alzheimer's disease biomarkers are invasive, time consuming or expensive. Thus, developing MRI-based computational methods for Alzheimer's disease early diagnosis would be essential to narrow down the phenotypic measures predictive of cognitive decline. Amnestic mild cognitive impairment (aMCI) is associated with higher risk for Alzheimer's disease, and here, we aimed to identify MRI-based quantitative rules to predict aMCI to possible Alzheimer's disease conversion, applying different machine learning algorithms sequentially. At baseline, T1-weighted brain images were collected for 104 aMCI patients and processed to obtain 146 volumetric measures of cerebral grey matter regions [regions of interest (ROIs)]. One year later, patients were classified as converters (aMCI-c = 32) or non-converters, i.e. clinically and neuropsychologically stable (aMCI-s = 72) based on cognitive performance. Feature selection was performed by random forest (RF), and the identified seven ROIs volumetric data were used to implement support vector machine (SVM) and decision tree (DT) classification algorithms. Both SVM and DT reached an average accuracy of 86% in identifying aMCI-c and aMCI-s. DT found a critical threshold volume of the right entorhinal cortex (EC-r) as the first feature for differentiating aMCI-c/aMCI-s. Almost all aMCI-c had an EC-r volume <1286 mm3, while more than half of the aMCI-s patients had a volume above the identified threshold for this structure. Other key regions for the classification between aMCI-c/aMCI-s were the left lateral occipital (LOC-l), the middle temporal gyrus and the temporal pole cortices. Our study reinforces previous evidence suggesting that the morphometry of the EC-r and LOC-l best predicts aMCI to Alzheimer's disease conversion. Further investigations are needed prior to deeming our findings as a broadly applicable predictive framework. However, here, a first indication was derived for volumetric thresholds that, being easy to obtain, may assist in early identification of Alzheimer's disease in clinical practice, thus contributing to establishing MRI as a useful non-invasive prognostic instrument for dementia onset.

The impact of radiation therapy on thyroid function in patient with head and neck tumors

Background. Head and neck cancers (HNC) accounted for 1,518,133 new cases and 510,771 new deaths worldwide. The first reports of hypothyroidism following radiotherapy (RT) for HNC were published in the 1960s. The objective of this study was to ascertain the frequency of thyroiditis in patients with HNC and to establish the threshold of radiation dose volume for radiation-induced hypothyroidism in HNC. Methods. This was a prospective study of 35 patients with HNC treated with IMRT-VMAT. The following characteristics were examined: age, gender, comorbidity, initial tumor site, histology, surgical margin resection, radiation therapy dosage, V40, V50, V60 (percentage of thyroid tissue volume), 95% dose received, mean dose, minimum dose, and maximum dose. Thyroid assessment was performed using ultrasonography of the neck. Thyroid function was determined by TFT tests (TSH, free T3, and free T4), which were done at baseline before treatment and after RT for each case. Results. In this study, the mean age was 57.71 ± 11.43 years, with males comprising 68.6% (24 patients) and females comprising 31.4% (11 patients). Regarding TSH, the results showed that post-RT, the mean level of TSH was significantly higher than pretreatment, with a significant difference (P = 0.009). Regarding fT3, the results showed that post-RT, the mean level of fT3 was significantly lower than pretreatment, with a significant difference (P = 0.007). Regarding fT4, the results showed that post-RT, the mean level of fT4 was significantly lower than pretreatment, with a significant difference (P = 0.015). In addition, the mean 95% dose was 6.8 Gy (median = 4 Gy). The percentages of thyroid tissue volumes at V40, V50, and V60 were 79.47%, 39.28%, and 38.02%, respectively. The incidence of hypothyroidism was 14.3%, and the euthyroid incidence rate was 85.7%. Conclusions. There is a strong correlation between radiation therapy doses exceeding 66 Gy and the occurrence of hypothyroidism. The levels of fT3 and fT4 decreased after RT, while TSH levels increased. In dosimetry, the mean 95% dose was 6.8 Gy. The percentages of thyroid tissue volumes at V40, V50, and V60 were 79.47%, 39.28%, and 38.02%, respectively. The incidence of hypothyroidism was 14.3%, and the euthyroid incidence rate was 85.7%.

Drivers of global tourism carbon emissions

Tourism has a critical role to play in global carbon emissions pathway. This study estimates the global tourism carbon footprint and identifies the key drivers using environmentally extended input-output modelling. The results indicate that global tourism emissions grew 3.5% p.a. between 2009-2019, double that of the worldwide economy, reaching 5.2 Gt CO2-e or 8.8% of total global GHG emissions in 2019. The primary drivers of emissions growth are slow technology efficiency gains (0.3% p.a.) combined with sustained high growth in tourism demand (3.8% p.a. in constant 2009 prices). Tourism emissions are associated with alarming distributional inequalities. Under both destination- and resident-based accounting, the twenty highest-emitting countries contribute three-quarters of the global footprint. The disparity in per-capita tourism emissions between high- and low-income nations now exceeds two orders of magnitude. National tourism decarbonisation strategies will require demand volume thresholds to be defined to align global tourism with the Paris Agreement.

GOLD Science Committee recommendations for the use of pre- and post-bronchodilator spirometry for the diagnosis of COPD.

The Global initiative for chronic Obstructive Lung Disease (GOLD) report states that the diagnosis of chronic obstructive pulmonary disease (COPD) should be considered in individuals with chronic respiratory symptoms and / or exposure to risk factors. Forced spirometry demonstrating airflow obstruction after bronchodilation is required to confirm the diagnosis using a threshold of forced expiratory volume in 1 s (FEV1) / forced vital capacity (FVC) ratio<0.7. This GOLD Science Committee review weighs the evidence for using pre- or post-bronchodilator (BD) spirometry to diagnose COPD.Cohort studies have shown that pre- and post-BD spirometry give concordant diagnostic results in most cases, although the prevalence of COPD is up to 36% lower with post-BD values. Discordant results may occur in "volume" or "flow" responders. Volume responders have reduced FVC due to gas trapping causing FEV1/ FVC ratio >0.7 pre-BD, but a volume response occurs post-BD with a greater improvement in FVC relative to FEV1 decreasing the ratio to <0.7. Flow responders show a greater FEV1 improvement relative to FVC which may increase FEV1/ FVC from <0.7 pre-BD to >0.7 post-BD; these individuals have an increased likelihood of developing post-BD obstruction during follow up and require monitoring longitudinally.GOLD 2025 recommends using pre-BD spirometry to rule out COPD and post-BD measurements to confirm the diagnosis. This will reduce clinical workload. Post-BD results close to the threshold should be repeated to ensure a correct diagnosis is made. Post-BD measurements ensure that volume responders are not overlooked and limit COPD overdiagnosis.

Perfusion-Based Relative Cerebral Blood Volume Is Associated With Functional Dependence in Large-Vessel Occlusion Ischemic Stroke.

Pretreatment computed tomography perfusion parameter relative cerebral blood volume (rCBV) lesion volume has been shown to predict 90-day modified Rankin Scale score in small-core strokes with Alberta Stroke Program Early Computed Tomography Score ≥5, including those with medium-vessel occlusions (mid and distal M2 segment occlusions). Hence, in this study we aim to assess the performance of different rCBV lesion volume thresholds (rCBV <42%, rCBV <38%, and rCBV <34%) with 90-day modified Rankin Scale score including patients with large core (Alberta Stroke Program Early Computed Tomography Score <5) and strictly including only patients with anterior circulation large-vessel occlusion. In this retrospective evaluation of our prospectively collected database, inclusion criteria were (1) Computed tomographic angiography confirmed anterior circulation large-vessel occlusion from September 1, 2017, to October 1, 2023; and (2) diagnostic computed tomography perfusion. Student t test, Mann-Whitney U test, and χ2 test were used in the univariate data analysis. Spearman's rank correlation analysis was used to assess correlations. Outcome measure was dichotomized into good functional outcome (90-day modified Rankin Scale score, 0-2) and poor functional outcome (90-day modified Rankin Scale score, 3-6) for logistic regression and receiver operating characteristic analysis. P≤0.05 was considered significant. In total, 229 patients met our inclusion criteria. The majority of the patients (n=161) in our cohort had M1 occlusion. All the rCBV thresholds were significantly higher in patients with poor 90-day functional outcomes and were independently associated with the outcome. Spearman's rank correlation analysis revealed a slightly stronger correlation of rCBV <42% (ρ=0.27, P<0.001), as compared with rCBV <38% (ρ=0.25, P<0.001) and rCBV <34% (ρ=0.24, P<0.001) with functional outcome. Receiver operating characteristic analysis revealed that rCBV <42% (area under the curve, 0.67 [95% CI, 0.60-0.74]; P<0.001) performed marginally better than rCBV <38% (area under the curve, 0.66 [95% CI, 0.59-0.73]; P<0.001), and rCBV <34% (area under the curve, 0.65 [95% CI, 0.58-0.72]; P<0.001). All the rCBV thresholds were independently associated with poor 90-day functional outcome; however, the rCBV <42% marginally outperformed rCBV <38% and rCBV <34% lesion volumes.

Geographic Access to High-Volume Mechanical Thrombectomy Centers in Florida, 2019.

Mechanical thrombectomy (MT) improves outcomes for acute ischemic stroke (AIS) due to large vessel occlusion, but is time sensitive and requires specialized infrastructure. Professional organizations and certification bodies have promulgated minimum procedural volume standards for centers and for individual proceduralists but it is unclear whether enforcing these requirements would decrease geographic access to MT. Therefore, we sought to evaluate the potential impact of applying a minimum procedural volume threshold on geographic access to MT. We identified all hospital discharges for stroke where an MT procedure was performed at any nonfederal hospital in Florida in 2019 using statewide hospital discharge data. We then generated geographic service area maps based on prespecified ground transport distances for the subset of hospitals that performed at least 1 MT and for those that performed at least 15 MTs that year, the minimum volume threshold required for thrombectomy capable and comprehensive stroke centers by the Joint Commission. Then, using zip code centroids and patient-level discharge hospital data, we computed the proportion of patients with AIS who lived within each of the generated service areas. A total of 105 of 297 hospitals performed MT; of those, 51 (17%) were low-volume centers (1-14 MTs/year) and 54 (18%) were high-volume centers (≥15 MTs/year). High-volume centers accounted for nearly 95% of all MTs performed in the state. Most patients hospitalized with AIS (87%) lived within 20 miles (or an estimated as a 1-hour driving time) of a hospital that performed at least 1 MT, and all (100%) lived within 115 miles (or estimated as 3-hour driving time). Setting a minimum MT volume threshold of 15 would decrease the proportion of stroke patients living within 1-hour driving time of an MT center from 87% to 77%. In 2019, most Florida stroke patients lived within a 1-hour ground transport time to a center that performed at least 1 MT and all lived within 3-hour driving time of an MT center, irrespective of whether a minimum procedural volume threshold of 15 cases per year was applied or not.

Ultra-High Frequency Spinal Nerve Neuromodulation for Improving Bladder Continence: Implications for Overactive Bladder Management

ObjectiveUltrahigh frequencies (UHF) have been shown to selectively suppress the sensory pathway with a rapid onset and prolonged effect compared with low frequencies. Few studies have explored the feasibility of UHF electrical stimulation in treating overactive bladder. This study aimed to investigate whether bladder overactivity could be inhibited by UHF stimulation at the L6 nerve root. Materials and MethodsFemale Sprague-Dawley rats (n = 12) were divided into two groups: sham and UHF groups. Bladder overactivity was induced by continuous intravesical infusion of 0.5% acetic acid (AA). UHF L6 nerve root stimulation (500 kHz, 20 mA for 5 minutes) was applied to the rats in the UHF group. To investigate the effects of the treatment, intravesical pressure was recorded by cystometrography during continuous transvesical infusion, with volume threshold (VT) and intercontraction interval (ICI) used to conduct the investigation. ResultsBladder overactivity was successfully developed in all rats with a significant decrease of median VT and ICI to 83.7% and 86.4%, respectively. UHF stimulation of the L6 nerve root was able to counteract the AA effect by significantly increasing median VT and ICI to 220% and 36.1%, respectively; these effects persisted for ≥two hours. There was a significant difference in the effects of UHF electrical stimulation between the sham and UHF groups (p < 0.05). ConclusionThis preliminary study provides evidence for UHF stimulation of the L6 spinal nerve root, analogous to the sacral nerve root in humans, as a potential alternative neuromodulation technique to suppress bladder overactivity.

The Relationship Between Surgeon Volume and Major Surgical Complications After Total Shoulder Arthroplasty: An Evaluation of 3177 US Orthopedic Surgeons.

Total shoulder arthroplasty (TSA), which includes anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA), is a technically demanding procedure and limited data exist on the relationship between case volume and complications. We sought to identify volume thresholds for TSA, aTSA, and rTSA at which risk of a major surgical complication decreased and to compare complications of patients treated by high-volume surgeons with those of patients treated by low-volume surgeons. Primary, elective TSAs (aTSA and rTSA) from January 1, 2016, to December 31, 2019, were identified in the Premier Healthcare Database. Multivariable logistic regression with restricted cubic splines modeled the relationship between annual TSA, aTSA, and rTSA surgeon volume and 90-day risk of major surgical complications. The 90-day complications of patients treated by high- and low-volume surgeons were compared. From 2016 to 2019, 3177 surgeons performed 78,639 TSAs. Increasing annual volume was associated with decreasing major surgical complication risk (thresholds: 50 TSAs, 25 aTSAs, and 36 rTSAs). High- and low-volume surgeons performed 24,595 and 54,044 TSAs, respectively. Patients of high-volume surgeons had lower risk of major surgical complications (adjusted odds ratio [aOR], 0.69; 95% CI, 0.56-0.84), myocardial infarction (aOR, 0.59; 95% CI, 0.36-0.97), and readmission (aOR, 0.71; 95% CI, 0.62-0.81). Importantly, 74.9% of high-volume and 93.0% of low-volume surgeon-year units had major surgical complication rates below the mean of all recorded surgeons. While most high- and low-volume surgeons had major surgical complication rates below the cohort average, increasing TSA volume was associated with a decreased risk of complications. [Orthopedics. 202x;4x(x):xx-xx.].

Feasibility of quantitative evaluation of hemodynamics using SPECT/CT in patients with chronic thromboembolic pulmonary hypertension

Abstract Background A ventilation/perfusion (V/Q) lung scan is recommended in the diagnostic work-up of patients with newly diagnosed pulmonary hypertension to rule out chronic thromboembolic pulmonary hypertension (CTEPH). V/Q single-photon emission computed tomography (SPECT) is considered the method of choice for diagnosis in CTEPH because it allows more precise evaluation than planar imaging. However, the evaluation of lung perfusion using V/Q SPECT imaging remains mainly a qualitative evaluation, and no quantitative method has been established. We hypothesized that the standardized uptake value (SUV) technique in Positron Emission Tomography (PET)-CT, a nuclear imaging technique well suited for quantitative of tumor biology, could be applied to quantitative assessment of lung perfusion. Purpose The purpose of this study was to evaluate the correlation between pulmonary perfusion distribution and hemodynamic data in Tc-labeled large-assembly albumin (99mTc-MAA) SPECT images in order to determine the feasibility of SPECT/CT for quantitative assessment of lung perfusion. Methods Twenty-five patients with CTEPH who underwent BPA and received SPECT-CT were included. Since the injected 99mTc-MAA selectively accumulates only in the lungs, SUV normalization was conducted using each patient’s lung volume, calculated by SPECT/CT and defined as SUV lung volume (LV) . The percentage of lung volume below each SUVLV value in total lung volume on SPECT/CT was examined before BPA, after two procedures of BPA, and six months after a series of BPA, and the correlations with hemodynamic parameters on right heart catheterization at each time point were evaluated. Results The Percent lung volume below SUVLV of 0.7 in total lung volume before BPA, after two procedures of BPA, and six months after a series of BPA had the strongest correlation with mean pulmonary artery pressure (mPAP) (rs; 0.727, p&amp;lt;0.001, Figure 1). The percent lung volume below SUVLV of 0.7 decreased with the BPA procedure in each patient with CTEPH (Figure 2). Furthermore, receiver operating characteristic analysis revealed that a threshold for the percent lung volume below SUVLV of 0.7 of 50.3% or greater could identify mPAP greater than 21 mmHg for right heart catheterization (area under the curve = 0.86, 95% CI 0.78-0.94, p&amp;lt;0.001). Conclusion Percent lung volume below SUVLV of 0.7 in total lung volume using SPECT/CT might reflect the severity of hemodynamics in patients with CTEPH. This method would be feasible for quantitative assessment of lung perfusion, even inter-patient and intra-patient.Figure 1Figure 2

Improved diagnostic accuracy of vessel-specific myocardial ischemia by coronary computed tomography angiography (CCTA)

BackgroundDiscrepancies between stenosis severity assessed at coronary computed tomography angiography (CCTA) and ischemia might depend on vessel type. Coronary plaque features are associated with ischemia. Thus, we evaluated the vessel-specific correlation of CCTA-derived diameter stenosis (DS) and invasive fractional flow reserve (FFR) and explored whether integrating morphological plaque features stratified by vessel might increase the predictive yield in identifying vessel-specific ischemia. MethodsObservational cohort study including patients undergoing CCTA for suspected coronary artery disease, with at least one vessel with DS ​≥ ​50 ​% at CCTA, undergoing invasive coronary angiography and FFR. Plaque analysis was performed using validated semi-automated software. Coronary vessels were stratified in left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA). Per vessel independent predictors of ischemia among CCTA-derived anatomical and morphologic plaque features were tested at univariable and multivariable logistic regression analysis. The best cut-off to predict ischemia was determined by Youden's index. Ischemia was defined by FFR≤0.80. ResultsThe study population consisted of 192 patients, of whom 224 vessels (61 ​% LAD, 19 ​% LCX, 20 ​% RCA) had lesions with DS ​≥ ​50 ​% interrogated by FFR. Despite similar DS, the rate of FFR≤0.80 was higher in the LAD compared to LCX and RCA (67.2 ​% vs 43.2 ​% and 44.2 ​%, respectively, p ​= ​0.018). A significant correlation between DS and FFR was observed only in LAD (p ​= ​0.003). At multivariable analysis stratified by vessel, the vessel-specific independent predictors of positive FFR were percent atheroma volume (threshold>17 ​%) for LAD, non-calcified plaque volume (threshold >130 ​mm3) for LCX, and lumen volume (threshold <844 ​mm3) for RCA. Integrating DS and vessel-specific morphological plaque features significantly increased the predictive yield for ischemia compared to DS alone (AUC ranging from 0.51 to 0.63 to 0.76–0.80). ConclusionsIntegrating DS and vessel-specific morphological plaque features significantly increased the predictive yield for vessel-specific ischemia compared to DS alone, potentially improving patients’ referral to the catheterization laboratory.

Effects of capsaicin on esophageal peristalsis in humans using high resolution manometry.

Capsaicin-containing red pepper sauce suspension augments esophageal contraction amplitude on conventional manometry. This study used high-resolution manometry (HRM) to investigate if capsaicin infusion modulates segmental esophageal smooth muscle peristalsis in healthy adults. Sixteen healthy volunteers (mean age 37 years, 14 male) underwent HRM for the evaluation of primary peristalsis and secondary peristalsis using slow and rapid air distensions. Both primary and secondary peristalsis were assessed following infusions of capsaicin-containing red pepper sauce and saline. Capsaicin infusion significantly increased heartburn symptoms compared to saline infusion (p < 0.001), and significantly decreased threshold volumes of secondary peristalsis during rapid air distensions (p = 0.02). The frequency of secondary peristalsis during rapid air distensions was significantly increased by capsaicin infusion (p = 0.03). Neither capsaicin infusion (p = 0.06) nor saline infusion (p = 0.27) altered threshold volume during slow air distensions. Capsaicin infusion significantly increased distal contractile integral (DCI) of primary peristalsis (p = 0.04), particularly in the proximal smooth muscle segment (p = 0.048). It enhanced secondary peristalsis during rapid air distensions (p = 0.003) but not during slow air distension (p = 0.23). Saline infusion significantly increased DCI of secondary peristalsis during rapid air distension (p = 0.01). Augmentation of distension-induced secondary peristalsis can be modulated by activation of capsaicin-sensitive afferents similar to mechanosensitive afferents. Capsaicin-induced augmentation of primary peristalsis isolates to the cholinergic-mediated proximal smooth muscle segment, which warrants study in ineffective esophageal motility to determine therapeutic potential.

Factors influencing urinary retention following freehand transperineal prostate biopsy: Insights from a tertiary care center study.

In this study, we evaluated the risk factors for urinary retention after freehand transrectal ultrasound (TRUS) guided transperineal prostate biopsy (TPB). Data from 102 cases of freehand TPB at a single institution were retrospectively collected and analyzed. All patients underwent magnetic resonance imaging (MRI)-TRUS cognitive fusion TPB using a transperineal needle guide, with systematic biopsies from 10 prostate sectors and additional MRI-guided targeted biopsies. Exclusions comprised patients with coagulation abnormalities, prior prostate surgeries including biopsy, active urinary tract infection, or a lack of pre-biopsy multiparametric MRI. 14/102 (13.72%) had urinary retention and required urethral catheterization for voiding difficulty or discomfort along with a bladder volume of ≥500 ml. Patients with retention exhibited significantly larger prostate volumes (median 75 cc vs. 40 cc; P < 0.05). Receiver operating curve analysis revealed a prostate volume threshold of 57.5 cc and a core number cutoff of 23 for predicting post-TPB urinary retention, with sensitivities of 78.57% and 85.71%, specificities of 75% and 82.95%, positive predictive values of 33.33% and 44.44%, and negative predictive values of 95.75% and 97.33%, respectively, whereas the number of biopsy cores correlated positively with the development of urinary retention (median 25 vs. 22; P < 0.05). Urinary retention was independent of the patient's age, comorbidities, presenting prostate-specific antigen levels, prebiopsy severity of lower urinary tract symptoms, and use of alpha-blockers. Patients with larger prostates and higher number of biopsy cores are at a higher risk of postfreehand TPB urinary retention and should receive appropriate counselling. Targeted biopsies alone, rather than a full template, may help mitigate urinary retention in these high-risk groups.

Enhanced classification performance using deep learning based segmentation for pulmonary embolism detection in CT angiography

PurposeTo develop a deep learning-based algorithm that automatically and accurately classifies patients as either having pulmonary emboli or not in CT pulmonary angiography (CTPA) examinations. Materials and methodsFor model development, 700 CTPA examinations from 652 patients performed at a single institution were used, of which 149 examinations contained 1497 PE traced by radiologists. The nnU-Net deep learning-based segmentation framework was trained using 5-fold cross-validation. To enhance classification, we applied logical rules based on PE volume and probability thresholds. External model evaluation was performed in 770 and 34 CTPAs from two independent datasets. ResultsA total of 1483 CTPA examinations were evaluated. In internal cross-validation and test set, the trained model correctly classified 123 of 128 examinations as positive for PE (sensitivity 96.1 %; 95 % C.I. 91–98 %; P < .05) and 521 of 551 as negative (specificity 94.6 %; 95 % C.I. 92–96 %; P < .05), achieving an area under the receiver operating characteristic (AUROC) of 96.4 % (95 % C.I. 79–99 %; P < .05). In the first external test dataset, the trained model correctly classified 31 of 32 examinations as positive (sensitivity 96.9 %; 95 % C.I. 84–99 %; P < .05) and 2 of 2 as negative (specificity 100 %; 95 % C.I. 34–100 %; P < .05), achieving an AUROC of 98.6 % (95 % C.I. 83–100 %; P < .05). In the second external test dataset, the trained model correctly classified 379 of 385 examinations as positive (sensitivity 98.4 %; 95 % C.I. 97–99 %; P < .05) and 346 of 385 as negative (specificity 89.9 %; 95 % C.I. 86–93 %; P < .05), achieving an AUROC of 98.5 % (95 % C.I. 83–100 %; P < .05). ConclusionOur automatic pipeline achieved beyond state-of-the-art diagnostic performance of PE in CTPA using nnU-Net for segmentation and volume- and probability-based post-processing for classification.

Tailoring microstructure in a soft-magnetic Fe-based amorphous-nanocrystalline alloy for high resistivity according to electrical percolation threshold

Superior soft-magnetic materials are necessary for the development of modern magnetic devices with energy-saving and high-power density requirements. However, improving the magnetism by nanocrystallization always brings about the sacrifice of resistivity, presenting a common trade-off in Fe-based amorphous-nanocrystalline alloys. Here, the comprehensive merits of both superior soft-magnetic properties (high saturation magnetization of 1.81 T and low coercivity of 3.8 A/m) and high resistivity of 117.2 μΩ·cm were obtained by precisely tailoring amorphous-nanocrystalline microstructure close to electrical percolation threshold for a Fe82.5B12P2C1Cu0.5Co2 amorphous alloy. The soft-magnetic properties are attributed to the low magnetic anisotropy stemming from high nuclei number density and ultrafine nanocrystalline grains of 9.2 nm. The high resistivity is associated with the electrical percolation behavior with a nanocrystalline volume threshold of 14.8 % in the composite alloy. The results provide an effective strategy to overcome the trade-off in traditional amorphous-nanocrystalline alloys, significant for applications in high-frequency, high-power, and energy-saving devices.