Sandwich spatial saturation for neuromelanin-sensitive MRI: Development and multi-center trial.

Neuromelanin (NM)-sensitive MRI using a magnetization transfer (MT)-prepared T1-weighted sequence has been suggested as a tool to visualize NM contents in the brain. In this study, a new NM-sensitive imaging method, sandwichNM, is proposed by utilizing the incidental MT effects of spatial saturation RF pulses in order to generate consistent high-quality NM images using product sequences. The spatial saturation pulses are located both superior and inferior to the imaging volume, increasing MT weighting while avoiding asymmetric MT effects. When the parameters of the spatial saturation were optimized, sandwichNM reported a higher NM contrast ratio than those of conventional NM-sensitive imaging methods with matched parameters for comparability with sandwichNM (SandwichNM: 23.6 ± 5.4%; MT-prepared TSE: 20.6 ± 7.4%; MT-prepared GRE: 17.4 ± 6.0%). In a multi-vendor experiment, the sandwichNM images displayed higher means and lower standard deviations of the NM contrast ratio across subjects in all three vendors (SandwichNM vs. MT-prepared GRE; Vendor A: 28.4 ± 1.5% vs. 24.4 ± 2.8%; Vendor B: 27.2 ± 1.0% vs. 13.3 ± 1.3%; Vendor C: 27.3 ± 0.7% vs. 20.1 ± 0.9%). For each subject, the standard deviations of the NM contrast ratio across the vendors were substantially lower in SandwichNM (SandwichNM vs. MT-prepared GRE; subject 1: 1.5% vs. 8.1%, subject 2: 1.1 % vs. 5.1%, subject 3: 0.9% vs. 4.0%, subject 4: 1.1% vs. 5.3%), demonstrating consistent contrasts across the vendors. The proposed method utilizes product sequences, requiring no alteration of a sequence and, therefore, may have a wide practical utility in exploring the NM imaging.

Comparing the standards of one metabolic equivalent of task in accurately estimating physical activity energy expenditure based on acceleration.

The purpose of the study is to analyse how the standard of resting metabolic rate (RMR) affects estimation of the metabolic equivalent of task (MET) using an accelerometer. In order to investigate the effect on estimation according to intensity of activity, comparisons were conducted between the 3.5 ml O2 · kg-1 · min-1 and individually measured resting VO2 as the standard of 1 MET. MET was estimated by linear regression equations that were derived through five-fold cross-validation using 2 types of MET values and accelerations; the accuracy of estimation was analysed through cross-validation, Bland and Altman plot, and one-way ANOVA test. There were no significant differences in the RMS error after cross-validation. However, the individual RMR-based estimations had as many as 0.5 METs of mean difference in modified Bland and Altman plots than RMR of 3.5 ml O2 · kg-1 · min-1. Finally, the results of an ANOVA test indicated that the individual RMR-based estimations had less significant differences between the reference and estimated values at each intensity of activity. In conclusion, the RMR standard is a factor that affects accurate estimation of METs by acceleration; therefore, RMR requires individual specification when it is used for estimation of METs using an accelerometer.

Low-frequency oscillations in cerebrovascular and cardiovascular hemodynamics: Their interrelationships and the effect of age.

The aim of this study was to investigate how the interrelationships between low-frequency oscillations (LFOs) in the cerebral and systemic cardiovascular hemodynamic systems change with aging and systemic hemodynamic perturbation. Seventeen young adult (28.4±3.5years) and seventeen elderly subjects (69.4±8.7years) underwent continuous measurements of arterial blood pressure (ABP), heart rate (HR), and cerebral oxygenation (oxy-hemoglobin, deoxy-hemoglobin, and total hemoglobin) using near-infrared spectroscopy. The LFOs were subdivided into three frequency intervals (FI-1: 0.01-0.02Hz, FI-2: 0.02-0.06Hz, and FI-3: 0.06-0.15Hz) via spectral analysis based on continuous wavelet transform. The amplitudes of the LFOs at these FIs were calculated to examine the effects of aging and head-up tilt (HUT) on cerebral and cardiovascular hemodynamics. Granger causality (GC) was used for analyzing the causal relationships between the LFOs observed in ABP, oxy-hemoglobin, and HR. The amplitudes of the LFOs were generally higher in young adults than in the elderly and increased significantly only in the younger subjects after HUT. GCs in FI-3 oscillations were significantly higher in young subjects compared to older participants in the HUT state. These results indicate that aging dampens systemic and cerebral hemodynamic regulatory mechanisms, and the interrelationships between systemic and cerebral hemodynamics become weaker with age.

Clinical evaluation of a deep-learning model for automatic scoring of the Alberta stroke program early CT score on non-contrast CT.

BACKGROUND: Automated measurement of the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) can support clinical decision making. Based on a deep learning algorithm, we developed an automated ASPECTS scoring system (Heuron ASPECTS) and validated its performance in a prespecified clinical trial. METHODS: For model training, we used non-contrast computed tomography images of 487 patients with acute ischemic stroke (AIS). For the clinical trial, 326 patients (87 with AIS, 56 with other acute brain diseases, and 183 with no brain disease) were enrolled. The results of Heuron ASPECTS were compared with the consensus generated by two stroke experts using the Bland-Altman agreement. A mean difference of less than 0.35 and a maximum allowed difference of less than 3.8 were considered the primary outcome target. The sensitivity and specificity of the model for the 10 regions of interest and dichotomized ASPECTS were calculated. RESULTS: The Bland-Altman agreement had a mean difference of 0.03 [95% confidence interval (CI): -0.08 to 0.14], and the upper and lower limits of agreement were 2.80 [95% CI: 2.62 to 2.99] and -2.74 [95% CI: -2.92 to -2.55], respectively. For ASPECTS calculation, sensitivity and specificity to detect the early ischemic change for 10 ASPECTS regions were 62.78% [95% CI: 58.50 to 67.07] and 96.63% [95% CI: 96.18 to 97.09], respectively. Furthermore, in a dichotomized analysis (ASPECTS >4 vs. ≤4), the sensitivity and specificity were 94.01% [95% CI: 91.26 to 96.77] and 61.90% [95% CI: 47.22 to 76.59], respectively. CONCLUSIONS: The current trial results show that Heuron ASPECTS reliably measures the ASPECTS for use in clinical practice.

Comparison of automated quantification of amyloid deposition between PMOD and Heuron.

Several programs are widely used for clinical and research purposes to automatically quantify the degree of amyloid deposition in the brain using positron emission tomography (PET) images. Given that very few studies have investigated the use of Heuron, a PET image quantification software approved for clinical use, this study aimed to compare amyloid deposition values quantified from 18F-flutemetamol PET images using PMOD and Heuron. Amyloid PET data obtained from 408 patients were analysed using each quantitative program; moreover, the standardized uptake value ratios (SUVRs) of target areas were obtained by dividing the standardized uptake value (SUV) of the target region by the SUV of cerebellar grey matter as a reference. Compared with PMOD, Heuron yielded significantly higher SUVRs for all target areas (paired sample t-test, p < 0.001), except for the PC/PCC (p = 0.986). However, the Bland-Altman plot analysis indicated that the two quantitative methods may be used interchangeably. Moreover, receiver operating characteristic curve analysis revealed no significant between-method difference in the performance of the SUVRs in evaluating the visual positivity of amyloid deposits (p = 0.948). In conclusion, Heuron and PMOD have comparable performance in quantifying the degree of amyloid deposits in PET images.

Automated assessment of the substantia nigra on susceptibility map-weighted imaging using deep convolutional neural networks for diagnosis of Idiopathic Parkinson's disease.

OBJECTIVES: Despite its use in determining nigrostriatal degeneration, the lack of a consistent interpretation of nigrosome 1 susceptibility map-weighted imaging (SMwI) limits its generalized applicability. To implement and evaluate a diagnostic algorithm based on convolutional neural networks for interpreting nigrosome 1 SMwI for determining nigrostriatal degeneration in idiopathic Parkinson's disease (IPD). METHODS: In this retrospective study, we enrolled 267 IPD patients and 160 control subjects (125 patients with drug-induced parkinsonism and 35 healthy subjects) at our institute, and 24 IPD patients and 27 control subjects at three other institutes on approval of the local institutional review boards. Dopamine transporter imaging served as the reference standard for the presence or absence of abnormalities of nigrosome 1 on SMwI. Diagnostic performance was compared between visual assessment by an experienced neuroradiologist and the developed deep learning-based diagnostic algorithm in both internal and external datasets using a bootstrapping method with 10000 re-samples by the "pROC" package of R (version 1.16.2). RESULTS: The area under the receiver operating characteristics curve (AUC) (95% confidence interval [CI]) per participant by the bootstrap method was not significantly different between visual assessment and the deep learning-based algorithm (internal validation, .9622 [0.8912-1.0000] versus 0.9534 [0.8779-0.9956], P = .1511; external validation, 0.9367 [0.8843-0.9802] versus 0.9208 [0.8634-0.9693], P = .6267), indicative of a comparable performance to visual assessment. CONCLUSIONS: Our deep learning-based algorithm for assessing abnormalities of nigrosome 1 on SMwI was found to have a comparable performance to that of an experienced neuroradiologist.

Evaluation of a Novel Trocar-Site Closure Device in Laparoscopic Surgery.

BACKGROUND AND OBJECTIVES: We evaluated the effectiveness and safety of EZ-CloseTM compared to those of hand suture for trocar-site closure according to obesity. METHODS: Fifty-four cases of laparoscopic colorectal surgery were enrolled. For the same patient, the right port site was closed using EZ-CloseTM and left port site was closed by hand suture among cases with port-site diameter ≥10 mm. Cases switched to use of a conventional fascial closure device or with closure time 120 s were considered failures. Closure time was analyzed according to body mass index (BMI) and abdominal wall thickness (AWT). RESULTS: The mean closure time was significantly shorter with EZ-CloseTM than with hand suture (87.9 ± 21.0 vs. 128.0 ± 59.0 s, p < 0.001). The number of failure cases was significantly lower with EZ-CloseTM than with hand suture (7 vs. 27, p < 0.001). The closure time of EZ-CloseTM was significantly shorter than that of hand suture in patients with BMI ≥ 25 and < 27 kg/m2 (n = 15, 85.9 ± 19.8 vs. 135.6 ± 67.9 s, p < 0.014) and ≥ 27 kg/m2 (n = 13, 85.1 ± 18.4 vs. 150.2 ± 70.6 s, p < 0.010). With respect to AWT, the closure time of EZ-CloseTM was significantly shorter than that of hand suture in patients with AWT ≥ 20 and < 26 mm (n = 12, 81.1 ± 11.5 vs. 142.3 ± 83.7 s, p = 0.023) and ≥ 26 mm (n = 17, 85.6 ± 22.6 vs. 160.2 ± 55.5, p < 0.001). No infection and herniation were detected in both trocar sites during the follow-up period (median 20.4 months). CONCLUSION: EZ-CloseTM could provide time efficiency in trocar-site closure, especially in obese patients.

Comparison of the Effect of Fimasartan versus Valsartan on Blood Pressure Variability in Acute Ischemic Stroke: A Double-Blind Randomized Trial.

Higher blood pressure variability (BPV) is associated with poor functional outcome and mortality in acute stroke. This randomized controlled trial was conducted to compare the effect on BPV between fimasartan and valsartan (Boryung Pharmaceutical Co., Ltd., Seoul, Republic of Korea) in patients with acute ischemic stroke. Eighty patients were randomly assigned to receive either valsartan or fimasartan after 7 days of acute ischemic stroke onset, for duration of 8 weeks. Of them, 62 patients completed the study [valsartan (n=31), fimasartan (n=31)]. We measured BP for 24 hours using ambulatory BP monitoring device before and after 8 weeks of starting BP medication. We calculated several indexes such as standard deviation (SD), weighted 24-hour BP with SD (wSD), coefficient of variation (CV), and average real variability (ARV) to assess BPV and to compare indexes of BPV between 2 drugs. SD values of systolic BP in daytime, nighttime, and 24 h period (15.55±4.02 versus 20.55±8.77, P=0.006; 11.98±5.52 versus 16.47±6.94, P=0.007; 17.22±5.30 versus 21.45±8.51, P=0.024), wSD of systolic BP (8.27±3.01 versus 10.77±4.18, P=0.010), and ARV of systolic BP (15.85±6.17 versus 19.68±7.83, P=0.040) of patients receiving fimasartan after 8 weeks were significantly lower than patients receiving valsartan. In paired t-test, SD values of daytime, nighttime, and 24 h period of systolic BP of patients receiving fimasartan were significantly decreased after 8 weeks (15.55±4.02 versus 18.70±7.04, P=0.038; 11.98±5.52 versus 17.19±7.35, P=0.006; 17.22±5.30 versus 20.59±5.91, P=0.015). Our study showed that fimasartan had greater effect on reducing BPV after acute ischemic stroke than valsartan. Trials registry number is KCT0003254.

Does the accuracy of blood pressure measurement correlate with hearing loss of the observer?

OBJECTIVE: The auscultatory method is influenced by the hearing level of the observers. If the observer has hearing loss, it is possible to measure blood pressure inaccurately by misreading the Korotkoff sounds at systolic blood pressure (SBP) and diastolic blood pressure (DBP). Because of the potential clinical problems this discrepancy may cause, we used a hearing loss simulator to determine how hearing level affects the accuracy of blood pressure measurements. MATERIALS AND METHODS: Two data sets (data set A, 32 Korotkoff sound video clips recorded by the British Hypertension Society; data set B, 28 Korotkoff sound data acquired from the Korotkoff sound recording system developed by Hanyang University) were used and all the data were attenuated to simulate a hearing loss of 5, 10, 15, 20, and 25 dB using the hearing loss simulator. Five observers with normal hearing assessed the blood pressures from these data sets and the differences between the values measured from the original recordings (no attenuation) and the attenuated versions were analyzed. RESULTS: Greater attenuation of the Korotkoff sounds, or greater hearing loss, resulted in larger blood pressure measurement differences when compared with the original data. When measuring blood pressure with hearing loss, the SBP tended to be underestimated and the DBP was overestimated. The mean differences between the original data and the 25 dB hearing loss data for the two data sets combined were 1.55±2.71 and -4.32±4.21 mmHg for SBP and DBP, respectively. CONCLUSION: This experiment showed that the accuracy of blood pressure measurements using the auscultatory method is affected by observer hearing level. Therefore, to reduce possible error using the auscultatory method, observers' hearing should be tested.