Parametric Modeling of the Brain Vascular System and its Application in Dynamic Contrast-Enhanced Imaging Studies.

Dynamic Contrast-Enhanced Imaging (DCE) is one of the main tools for in vivo measurement of vascular properties of pathologies such as brain tumors. In DCE imaging, one of the key components for estimation of vascular perfusion and permeability parameters using Pharmacokinetic models is the Arterial Input Function (AIF). To measure these parameters more accurately, there have been approaches for estimating the AIF profile at the capillary level; however, a practical and realistic estimate is still missing. As a solution, we have developed a model of the brain vascular system, based on laws of fluid dynamics and vascular morphology, to address dispersion and delay of the contrast agent (CA) concentration profile at different levels of the brain vascular tree. Using this model, we introduced a transfer function that can describe changes of the AIF profile along a vascular pathway, from a major artery to the capillary bed. Our simulations and also testing this model on DCE Imaging data of the human brain, all showed that our model can give a realistic estimation of the CA concentration profile, at all levels of the vascular tree in the brain. In the next step, we extended our model to address vascular leakage as well. Using this extended vascular (EV) model, we are able to decompose the tissue response signal in DCE images to its intravascular and extravascular components. This feature has provided us with an excellent tool that can lead to relatively unbiased measurements of perfusion and permeability parameters, especially in areas with vascular leakage. We tested this on DCE-CT and DCE-MR images and compared the performance of our model to conventional methods. Also, using a simulation study, we measured the levels of overestimation and underestimation of the permeability parameters using conventional processing methods and demonstrated the superior performance of the EV model for more accurate estimation of these parameters. Overall, the results show that the EV model can provide a platform for better understanding of the role of the AIF in DCE studies as well as estimation of AIF for more accurate measurement of perfusion and permeability parameters in clinical studies.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107177/1/siamak_1.pd

Preparation and Implementation of Intrahospital Transfer Protocol for Emergency Department Patients to Decrease Unexpected Events

Introduction: Most of the patients hospitalized in the emergency department (ED) are in need of transfer to other hospital wards or paraclinic units. This process is called intrahospital transfer (IHT) that may lead to a wide range of complications known as unexpected events (UE). Objective: In the present study we decided to evaluate the effect of using a pre-designed protocol on decrease of UEs and safety improvement of IHT among patients hospitalized in ED. Method: The present cross-sectional study was carried out in 2016 in the ED of Imam Khomeini Hospital, Tehran, Iran. All patients with triage levels of 1 and 2 who were in need of temporary or permanent transfer to other departments of the studied treatment center based on clinical indication as decided by the in-charge physician were enrolled in the study. This study was conducted in 3 phases of pre-intervention, intervention and post-intervention. Any UE was recorded in first phase. During intervention phase ED-IHT protocol was prepared and implemented. the checklist of complications and UEs during transfer was filled again and pre- and post-intervention results were compared. Results: In this study, 207 patients with the mean age of 58.9 ± 20.6 years were evaluated (61.4% male). Demographic data and baseline characteristics of the studied patients in the phases before and after implementation of the protocol has no significant difference. Overall, before implementation of the protocol out of the 105 studied patients, a total of 35 patients (33.3%) were affected by UE during transfer, but after implementation of the protocol this rate decreased to 11 patients (10.8%) out of the 103 studied patients and this decrease was statistically significant (p < 0.001). Conclusion: Based on the results obtained from this study, it seems that performing the IHT protocol specialized for ED patients has been effective in decreasing UE cases

Preparation and Implementation of Intrahospital Transfer Protocol for Emergency Department Patients to Decrease Unexpected Events

Introduction: Most of the patients hospitalized in the emergency department (ED) are in need of transfer to other hospital wards or paraclinic units. This process is called intrahospital transfer (IHT) that may lead to a wide range of complications known as unexpected events (UE). Objective: In the present study we decided to evaluate the effect of using a pre-designed protocol on decrease of UEs and safety improvement of IHT among patients hospitalized in ED. Method: The present cross-sectional study was carried out in 2016 in the ED of Imam Khomeini Hospital, Tehran, Iran. All patients with triage levels of 1 and 2 who were in need of temporary or permanent transfer to other departments of the studied treatment center based on clinical indication as decided by the in-charge physician were enrolled in the study. This study was conducted in 3 phases of pre-intervention, intervention and post-intervention. Any UE was recorded in first phase. During intervention phase ED-IHT protocol was prepared and implemented. the checklist of complications and UEs during transfer was filled again and pre- and post-intervention results were compared. Results: In this study, 207 patients with the mean age of 58.9 ± 20.6 years were evaluated (61.4% male). Demographic data and baseline characteristics of the studied patients in the phases before and after implementation of the protocol has no significant difference. Overall, before implementation of the protocol out of the 105 studied patients, a total of 35 patients (33.3%) were affected by UE during transfer, but after implementation of the protocol this rate decreased to 11 patients (10.8%) out of the 103 studied patients and this decrease was statistically significant (p < 0.001). Conclusion: Based on the results obtained from this study, it seems that performing the IHT protocol specialized for ED patients has been effective in decreasing UE cases

Validity of Triage Performed by Nurses Educated by Train-of-Trainer‬ Workshop Participants; a Cross-sectional Study for Assessment of Cascade Training System

Introduction: In 2010, a national triage train-of-trainer (TOT) workshop was held in Tehran, Iran. Objective: The present study aimed to assess the validity of the triage performed by the nurses educated by those who participated in TOT workshop. Method: This cross-sectional study was carried out in 6 teaching hospitals from 4 universities in Iran. Inter-rater and intra-rater reliability of performed triage by participations was measured. Thirteen nurses were randomly selected. Thereafter, at the end of each working shift, patient data recorded in the daily data registry forms were collected. Then, duration of hospital stay, number of cases admitted to general wards or intensive care units, number of cases discharged from the ED within 12 hours and mortality rate were compared with the triage level determined by the nurse. Results: In total, 30 nurses with a mean age of 28.4 ± 3.7 years were enrolled. In this study, 1491 triage cases (61.6% male) were evaluated, of which 4.2% were triaged as level 1, 18.3% as level 2, 37.1% as level 3, 20.4% as level 4 and 20.0% as level 5. The following outcome was observed: 3.64% were discharged, 6.29% were hospitalized, 3% died and 2.3% were discharged against medical advice without completing treatment. The correlation of determined triage level and patients’ duration of hospitalization was significant based on one-way ANOVA test (p = 0.000). The outcome of the patients significantly correlated with the level of triage determined by the study nurses (p = 0.000). Conclusion: Based on the findings, it appears that triage performed by the study nurses educated by those who participated in TOT workshop through cascade training system had perfect validity

Validity of Triage Performed by Nurses Educated by Train-of-Trainer‬ Workshop Participants; a Cross-sectional Study for Assessment of Cascade Training System

Introduction: In 2010, a national triage train-of-trainer (TOT) workshop was held in Tehran, Iran. Objective: The present study aimed to assess the validity of the triage performed by the nurses educated by those who participated in TOT workshop. Method: This cross-sectional study was carried out in 6 teaching hospitals from 4 universities in Iran. Inter-rater and intra-rater reliability of performed triage by participations was measured. Thirteen nurses were randomly selected. Thereafter, at the end of each working shift, patient data recorded in the daily data registry forms were collected. Then, duration of hospital stay, number of cases admitted to general wards or intensive care units, number of cases discharged from the ED within 12 hours and mortality rate were compared with the triage level determined by the nurse. Results: In total, 30 nurses with a mean age of 28.4 ± 3.7 years were enrolled. In this study, 1491 triage cases (61.6% male) were evaluated, of which 4.2% were triaged as level 1, 18.3% as level 2, 37.1% as level 3, 20.4% as level 4 and 20.0% as level 5. The following outcome was observed: 3.64% were discharged, 6.29% were hospitalized, 3% died and 2.3% were discharged against medical advice without completing treatment. The correlation of determined triage level and patients’ duration of hospitalization was significant based on one-way ANOVA test (p = 0.000). The outcome of the patients significantly correlated with the level of triage determined by the study nurses (p = 0.000). Conclusion: Based on the findings, it appears that triage performed by the study nurses educated by those who participated in TOT workshop through cascade training system had perfect validity

Outcome-Based Validity and Reliability Assessment of Raters Regarding the Admission Triage Level in the Emergency Department: a Cross-Sectional Study

Introduction: Emergency department (ED) is usually the first line of healthcare supply to patients in non-urgent to critical situations and, if necessary, provides hospital admission. A dynamic system to evaluate patients and allocate priorities is necessary. Such a structure that facilitates patients’ flow in the ED is termed triage. Objective: This study was conducted to investigate the validity and reliability of implementation of Emergency Severity Index (ESI) system version 4 by triage nurses in an overcrowded referral hospital with more than 80000 patient admissions per year and an average emergency department occupancy rate of more than 80%. Method: This prospective cross-sectional study was conducted in a tertiary care teaching hospital and trauma center with an emergency medicine residency program. Seven participating expert nurses were asked to assess the ESI level of patients in 30 written scenarios twice within a three-week interval to evaluate the inter-rater and intra-rater reliability. Patients were randomly selected to participate in the study, and the triage level assigned by the nurses was compared with that by the emergency physicians. Finally, based on the patients’ charts, an expert panel evaluated the validity of the triage level. Results: During the study period, 527 patients with mean age of 54 ± 7 years, including 253 (48%) women and 274 (52%) men, were assessed by seven trained triage nurses. The degree of retrograde agreement between the collaborated expert panel’s evaluation and the actual triage scales by the nurses and physicians for all 5 levels was excellent, with the Cohen’s weighted kappa being 0.966 (CI 0.985–0.946, p < 0.001) and 0.813 (CI 0.856–0.769, p<0.001), respectively. The intra-rater reliability was 0.94 (p < 0.0001), and the inter-rater reliability for all the nurses was in perfect agreement with the test result (Cohen’s weighted kappa were as follows: 0.919, 0.956, 0.911, 0.955, 0.860, 0.956, and 0.868; p < 0.001). Conclusion: The study findings showed that there was perfect reliability and, overall, almost perfect validity for the triage performed by the studied nurses

Performance of deep learning synthetic CTs for MR-only brain radiation therapy

PURPOSE: To evaluate the dosimetric and image-guided radiation therapy (IGRT) performance of a novel generative adversarial network (GAN) generated synthetic CT (synCT) in the brain and compare its performance for clinical use including conventional brain radiotherapy, cranial stereotactic radiosurgery (SRS), planar, and volumetric IGRT. METHODS AND MATERIALS: SynCT images for 12 brain cancer patients (6 SRS, 6 conventional) were generated from T1-weighted postgadolinium magnetic resonance (MR) images by applying a GAN model with a residual network (ResNet) generator and a convolutional neural network (CNN) with 5 convolutional layers as the discriminator that classified input images as real or synthetic. Following rigid registration, clinical structures and treatment plans derived from simulation CT (simCT) images were transferred to synCTs. Dose was recalculated for 15 simCT/synCT plan pairs using fixed monitor units. Two-dimensional (2D) gamma analysis (2%/2 mm, 1%/1 mm) was performed to compare dose distributions at isocenter. Dose-volume histogram (DVH) metrics (D(95%) , D(99%) , D(0.2cc,) and D(0.035cc) ) were assessed for the targets and organ at risks (OARs). IGRT performance was evaluated via volumetric registration between cone beam CT (CBCT) to synCT/simCT and planar registration between KV images to synCT/simCT digital reconstructed radiographs (DRRs). RESULTS: Average gamma passing rates at 1%/1mm and 2%/2mm were 99.0 ± 1.5% and 99.9 ± 0.2%, respectively. Excellent agreement in DVH metrics was observed (mean difference ≤0.10 ± 0.04 Gy for targets, 0.13 ± 0.04 Gy for OARs). The population averaged mean difference in CBCT-synCT registrations were \u3c0.2 mm and 0.1 degree different from simCT-based registrations. The mean difference between kV-synCT DRR and kV-simCT DRR registrations was \u3c0.5 mm with no statistically significant differences observed (P \u3e 0.05). An outlier with a large resection cavity exhibited the worst-case scenario. CONCLUSION: Brain GAN synCTs demonstrated excellent performance for dosimetric and IGRT endpoints, offering potential use in high precision brain cancer therapy

Outcome-Based Validity and Reliability Assessment of Raters Regarding the Admission Triage Level in the Emergency Department: a Cross-Sectional Study

Introduction: Emergency department (ED) is usually the first line of healthcare supply to patients in non-urgent to critical situations and, if necessary, provides hospital admission. A dynamic system to evaluate patients and allocate priorities is necessary. Such a structure that facilitates patients’ flow in the ED is termed triage. Objective: This study was conducted to investigate the validity and reliability of implementation of Emergency Severity Index (ESI) system version 4 by triage nurses in an overcrowded referral hospital with more than 80000 patient admissions per year and an average emergency department occupancy rate of more than 80%. Method: This prospective cross-sectional study was conducted in a tertiary care teaching hospital and trauma center with an emergency medicine residency program. Seven participating expert nurses were asked to assess the ESI level of patients in 30 written scenarios twice within a three-week interval to evaluate the inter-rater and intra-rater reliability. Patients were randomly selected to participate in the study, and the triage level assigned by the nurses was compared with that by the emergency physicians. Finally, based on the patients’ charts, an expert panel evaluated the validity of the triage level. Results: During the study period, 527 patients with mean age of 54 ± 7 years, including 253 (48%) women and 274 (52%) men, were assessed by seven trained triage nurses. The degree of retrograde agreement between the collaborated expert panel’s evaluation and the actual triage scales by the nurses and physicians for all 5 levels was excellent, with the Cohen’s weighted kappa being 0.966 (CI 0.985–0.946, p < 0.001) and 0.813 (CI 0.856–0.769, p<0.001), respectively. The intra-rater reliability was 0.94 (p < 0.0001), and the inter-rater reliability for all the nurses was in perfect agreement with the test result (Cohen’s weighted kappa were as follows: 0.919, 0.956, 0.911, 0.955, 0.860, 0.956, and 0.868; p < 0.001). Conclusion: The study findings showed that there was perfect reliability and, overall, almost perfect validity for the triage performed by the studied nurses

Optimization of a novel large field of view distortion phantom for MR-only treatment planning

PURPOSE: MR-only treatment planning requires images of high geometric fidelity, particularly for large fields of view (FOV). However, the availability of large FOV distortion phantoms with analysis software is currently limited. This work sought to optimize a modular distortion phantom to accommodate multiple bore configurations and implement distortion characterization in a widely implementable solution. METHOD AND MATERIALS: To determine candidate materials, 1.0 T MR and CT images were acquired of twelve urethane foam samples of various densities and strengths. Samples were precision-machined to accommodate 6 mm diameter paintballs used as landmarks. Final material candidates were selected by balancing strength, machinability, weight, and cost. Bore sizes and minimum aperture width resulting from couch position were tabulated from the literature (14 systems, 5 vendors). Bore geometry and couch position were simulated using MATLAB to generate machine-specific models to optimize the phantom build. Previously developed software for distortion characterization was modified for several magnet geometries (1.0 T, 1.5 T, 3.0 T), compared against previously published 1.0 T results, and integrated into the 3D Slicer application platform. RESULTS: All foam samples provided sufficient MR image contrast with paintball landmarks. Urethane foam (compressive strength ∼1000 psi, density ~20 lb/ft3 ) was selected for its accurate machinability and weight characteristics. For smaller bores, a phantom version with the following parameters was used: 15 foam plates, 55 × 55 × 37.5 cm3 (L×W×H), 5,082 landmarks, and weight ~30 kg. To accommodate \u3e 70 cm wide bores, an extended build used 20 plates spanning 55 × 55 × 50 cm3 with 7,497 landmarks and weight ~44 kg. Distortion characterization software was implemented as an external module into 3D Slicer\u27s plugin framework and results agreed with the literature. CONCLUSION: The design and implementation of a modular, extendable distortion phantom was optimized for several bore configurations. The phantom and analysis software will be available for multi-institutional collaborations and cross-validation trials to support MR-only planning

Cell Treatment for Stroke in Type Two Diabetic Rats Improves Vascular Permeability Measured by MRI

Treatment of stroke with bone marrow stromal cells (BMSC) significantly enhances brain remodeling and improves neurological function in non-diabetic stroke rats. Diabetes is a major risk factor for stroke and induces neurovascular changes which may impact stroke therapy. Thus, it is necessary to test our hypothesis that the treatment of stroke with BMSC has therapeutic efficacy in the most common form of diabetes, type 2 diabetes mellitus (T2DM). T2DM was induced in adult male Wistar rats by administration of a high fat diet in combination with a single intraperitoneal injection (35mg/kg) of streptozotocin. These rats were then subjected to 2h of middle cerebral artery occlusion (MCAo). T2DM rats received BMSC (5x106, n = 8) or an equal volume of phosphate-buffered saline (PBS) (n = 8) via tail-vein injection at 3 days after MCAo. MRI was performed one day and then weekly for 5 weeks post MCAo for all rats. Compared with vehicle treated control T2DM rats, BMSC treatment of stroke in T2DM rats significantly (