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PURPOSE - MR fingerprinting (MRF) sequences permit efficient T and T estimation in cranial and extracranial regions, but these areas may include substantial fat signals that bias T and T estimates. MRI fat signal fraction estimation is also a topic of active research in itself, but may be complicated by B heterogeneity and blurring during spiral k-space acquisitions, which are commonly used for MRF. An MRF method is proposed that separates fat and water signals, estimates water T and T, and accounts for B effects with spiral blurring correction, in a single sequence.
THEORY AND METHODS - A k-space-based fat-water separation method is further extended to unbalanced steady-state free precession MRF with swept echo time. Repeated application of this k-space fat-water separation to demodulated forms of the measured data allows a B map and correction to be approximated. The method is compared with MRF without fat separation across a broad range of fat signal fractions (FSFs), water Ts and Ts, and under heterogeneous static fields in simulations, phantoms, and in vivo.
RESULTS - The proposed method's FSF estimates had a concordance correlation coefficient of 0.990 with conventional measurements, and reduced biases in the T and T estimates due to fat signal relative to other MRF sequences by several hundred ms. The B correction improved the FSF, T, and T estimation compared to those estimates without correction.
CONCLUSION - The proposed method improves MRF water T and T estimation in the presence of fat and provides accurate FSF estimation with inline B correction.
Copyright © 2019 Elsevier Inc. All rights reserved.
OBJECTIVE - This work evaluates current 3-D image registration tools on clinically acquired abdominal computed tomography (CT) scans.
METHODS - Thirteen abdominal organs were manually labeled on a set of 100 CT images, and the 100 labeled images (i.e., atlases) were pairwise registered based on intensity information with six registration tools (FSL, ANTS-CC, ANTS-QUICK-MI, IRTK, NIFTYREG, and DEEDS). The Dice similarity coefficient (DSC), mean surface distance, and Hausdorff distance were calculated on the registered organs individually. Permutation tests and indifference-zone ranking were performed to examine the statistical and practical significance, respectively.
RESULTS - The results suggest that DEEDS yielded the best registration performance. However, due to the overall low DSC values, and substantial portion of low-performing outliers, great care must be taken when image registration is used for local interpretation of abdominal CT.
CONCLUSION - There is substantial room for improvement in image registration for abdominal CT.
SIGNIFICANCE - All data and source code are available so that innovations in registration can be directly compared with the current generation of tools without excessive duplication of effort.
BACKGROUND - Abdominoperineal resection for low rectal adenocarcinoma is a common procedure with high morbidity, including perineal wound complications.
OBJECTIVE - The purpose of this study was to determine risk factors for perineal wound dehiscence and to investigate the effect of wound dehiscence on survival.
DESIGN - This was a retrospective medical chart review.
SETTINGS - The study was conducted in a tertiary care university medical center.
PATIENTS - Patients included in the study were those with low rectal adenocarcinoma who underwent abdominoperineal resection between January 2001 and June 2012.
MAIN OUTCOMES MEASURES - We assessed the incidence of perineal wound dehiscence, as well as survival, after surgery.
RESULTS - A total of 249 patients underwent abdominoperineal resection for rectal carcinoma. The mean age was 62.6 years (range, 23.0-98.0 years), 159 (63.8%) were male, and the mean BMI was 27.9 (range, 16.7-58.5). There were 153 patients (61.1%) who survived for 5 years after surgery. Sixty-nine patients (27.7%) developed wound dehiscence. Multivariable analysis revealed the following associations with dehiscence: BMI (OR, 1.09; 95% CI, 1.03-1.15; p = 0.002), IBD (OR, 6.6; 95% CI, 1.4-32.5; p = 0.02), history of other malignant neoplasm (OR, 3.1; 95% CI, 1.5-6.6), and abdominoperineal resection for cancer recurrence (OR, 2.8; 95% CI, 1.2-6.3; p = 0.01). In the survival analysis, wound dehiscence was associated with decreased survival (mean survival time for dehiscence vs no dehiscence, 66.6 months vs 76.6 months; p = 0.01). This relationship persisted in the multivariable analysis (HR, 1.7; 95% CI, 1.1-2.8; p = 0.02).
LIMITATIONS - This was a retrospective, observational study from a single center.
CONCLUSIONS - The adjusted risk of death was 1.7 times higher in patients who experienced dehiscence than in those who did not. Attention to perineal wound closure with consideration of flap creation should at least be given to patients with a history of malignant neoplasm, those with IBD, those with rectal cancer recurrence, and women undergoing posterior vaginectomy. Preoperative weight loss should also reduce dehiscence risk.
PURPOSE - The objective of this study is to assess the performance of existing wear/nonwear time classification algorithms for accelerometry data collected in the free-living environment using a wrist-worn triaxial accelerometer and a waist-worn uniaxial accelerometer in older adults.
METHODS - Twenty-nine adults age 76 to 96 yr wore wrist accelerometers for approximately 24 h per day and waist accelerometers during waking for approximately 7 d of free living. Wear and nonwear times were classified by existing algorithms (Alg([ActiLife]), Alg([Troiano]), and Alg([Choi])) and compared with wear and nonwear times identified by data plots and diary records. With the use of bias and probability of correct classification, the performance of the algorithms, two time windows (60 and 90 min), and vector magnitude (VM) versus vertical axis (V) counts from a triaxial accelerometer were compared.
RESULTS - Automated algorithms (Alg([Choi]) and Alg([Troiano])) classified wear/nonwear time intervals more accurately from VM than V counts. The use of the 90-min time window improved wear/nonwear classification accuracy when compared with the 60-min window. The Alg([Choi]) and Alg([Troiano]) performed better than the manufacturer-provided algorithm (Alg([ActiLife])), and the Alg([Choi]) performed better than the Alg([Troiano]) for wear/nonwear time classification using the data collected by both accelerometers.
CONCLUSIONS - Triaxial wrist-worn accelerometer can be used for an accurate wear/nonwear time classification in free-living older adults. The use of the 90-min window and the VM counts improves the performance of commonly used algorithms for wear/nonwear classification for both uniaxial and triaxial accelerometers.
OBJECTIVE - To assess the association of 0.9% saline use versus a calcium-free physiologically balanced crystalloid solution with major morbidity and clinical resource use after abdominal surgery.
BACKGROUND - 0.9% saline, which results in a hyperchloremic acidosis after infusion, is frequently used to replace volume losses after major surgery.
METHODS - An observational study using the Premier Perspective Comparative Database was performed to evaluate adult patients undergoing major open abdominal surgery who received either 0.9% saline (30,994 patients) or a balanced crystalloid solution (926 patients) on the day of surgery. The primary outcome was major morbidity and secondary outcomes included minor complications and acidosis-related interventions. Outcomes were evaluated using multivariable logistic regression and propensity scoring models.
RESULTS - For the entire cohort, the in-hospital mortality was 5.6% in the saline group and 2.9% in the balanced group (P < 0.001). One or more major complications occurred in 33.7% of the saline group and 23% of the balanced group (P < 0.001). In the 3:1 propensity-matched sample, treatment with balanced fluid was associated with fewer complications (odds ratio 0.79; 95% confidence interval 0.66-0.97). Postoperative infection (P = 0.006), renal failure requiring dialysis (P < 0.001), blood transfusion (P < 0.001), electrolyte disturbance (P = 0.046), acidosis investigation (P < 0.001), and intervention (P = 0.02) were all more frequent in patients receiving 0.9% saline.
CONCLUSIONS - Among hospitals in the Premier Perspective Database, the use of a calcium-free balanced crystalloid for replacement of fluid losses on the day of major surgery was associated with less postoperative morbidity than 0.9% saline.
BACKGROUND - Hemolymph circulation in mosquitoes is primarily controlled by the contractile action of a dorsal vessel that runs underneath the dorsal midline and is subdivided into a thoracic aorta and an abdominal heart. Wave-like peristaltic contractions of the heart alternate in propelling hemolymph in anterograde and retrograde directions, where it empties into the hemocoel at the terminal ends of the insect. During our analyses of hemolymph propulsion in Anopheles gambiae, we observed periodic ventral abdominal contractions and hypothesized that they promote extracardiac hemolymph circulation in the abdominal hemocoel.
METHODOLOGY/PRINCIPAL FINDINGS - We devised methods to simultaneously analyze both heart and abdominal contractions, as well as to measure hemolymph flow in the abdominal hemocoel. Qualitative and quantitative analyses revealed that ventral abdominal contractions occur as series of bursts that propagate in the retrograde direction. Periods of ventral abdominal contraction begin only during periods of anterograde heart contraction and end immediately following a heartbeat directional reversal, suggesting that ventral abdominal contractions function to propel extracardiac hemolymph in the retrograde direction. To test this functional role, fluorescent microspheres were intrathoracically injected and their trajectory tracked throughout the hemocoel. Quantitative measurements of microsphere movement in extracardiac regions of the abdominal cavity showed that during periods of abdominal contractions hemolymph flows in dorsal and retrograde directions at a higher velocity and with greater acceleration than during periods of abdominal rest. Histochemical staining of the abdominal musculature then revealed that ventral abdominal contractions result from the contraction of intrasegmental lateral muscle fibers, intersegmental ventral muscle bands, and the ventral transverse muscles that form the ventral diaphragm.
CONCLUSIONS/SIGNIFICANCE - These data show that abdominal contractions potentiate extracardiac retrograde hemolymph propulsion in the abdominal hemocoel during periods of anterograde heart flow.
Evidence suggests that NK and NKT cells contribute to inflammation and mortality during septic shock caused by cecal ligation and puncture (CLP). However, the specific contributions of these cell types to the pathogenesis of CLP-induced septic shock have not been fully defined. The goal of the present study was to determine the mechanisms by which NK and NKT cells mediate the host response to CLP. Control, NK cell-deficient, and NKT cell-deficient mice underwent CLP. Survival, cytokine production, and bacterial clearance were measured. NK cell trafficking and interaction with myeloid cells was also studied. Results show that mice treated with anti-asialoGM1 (NK cell deficient) or anti-NK1.1 (NK/NKT cell deficient) show less systemic inflammation and have improved survival compared with IgG-treated controls. CD1 knockout mice (NKT cell deficient) did not demonstrate decreased cytokine production or improved survival compared with wild type mice. Trafficking studies show migration of NK cells from blood and spleen into the inflamed peritoneal cavity where they appear to facilitate the activation of peritoneal macrophages (F4-80(+)GR-1(-)) and F4-80(+)Gr-1(+) myeloid cells. These findings indicate that NK but not CD1-restricted NKT cells contribute to acute CLP-induced inflammation. NK cells appear to mediate their proinflammatory functions during septic shock, in part, by migration into the peritoneal cavity and amplification of the proinflammatory activities of specific myeloid cell populations. These findings provide new insights into the mechanisms used by NK cells to facilitate acute inflammation during septic shock.
Increasing prostate volume contributes to urinary tract symptoms and may obscure prostate cancer detection. We investigated the association between obesity and prostate volume, prostate-specific antigen (PSA) and PSA density among 753 men referred for prostate biopsy. Among men with a negative biopsy, prostate volume significantly increased approximately 25% from the lowest to highest body mass index (BMI), waist or hip circumference or height categories. PSA was 0.7 ng/ml lower with a high waist-to-hip ratio. These associations were less consistent among subjects diagnosed with high-grade prostatic intraepithelial neoplasia or cancer. Our data suggest that obesity and height are independently associated with prostate volume..
OBJECTIVE - To determine, among patients at risk for intrauterine growth restriction (IUGR), the peripartum outcomes and predictive accuracy for those with normal abdominal circumference (AC) and estimated fetal weight (EFW) for gestational age (GA; group 1) versus those with AC < or = 10% for GA but EFW>10% (group 2) versus those with AC and EFW < or = 10% for GA (group 3).
STUDY DESIGN - We identified, retrospectively, non-anomalous singleton pregnancies with reliable GA, and delivery within 21 days of the examination who were referred for possible IUGR. Odds ratios (OR) and 95% confidence intervals (CI) were calculated, as were likelihood ratios (LR) for detection of small for gestational age (SGA) (birth weight < or = 10% for GA; SGA).
RESULTS - Among the 169 consecutive patients who met the inclusion criteria, the prevalence of SGA was significantly higher for group 3 (80%) than group 1 (42%; OR 4.26, 95% CI 1.94-9.16) or group 2 (49%; OR 5.49, 95% CI 2.13-13.85). The rate of admission to the neonatal intensive care unit (67%, 34%, and 36% for groups 3, 2, and 1, respectively) and the combined perinatal morbidity (35%, 23%, and 15%) were different for the three groups. The LR for detection of SGA was 1.2 (95% CI 1.0-1.4) for group 2 and 2.8 (95% CI 1.6-4.9) for group 3.
CONCLUSIONS - Among patients suspected for IUGR, the peripartum outcome is poorest for those with AC and EFW < or = 10% for GA, than for those with AC < or = 10% but EFW>10%. The detection of SGA is poor regardless of whether just AC or AC plus EFW are < or = 10%.