Single STE-MR Acquisition in MR-Based Attenuation Correction of Brain PET Imaging Employing a Fully Automated and Reproducible Level-Set Segmentation Approach

Purpose

The aim of this study is to introduce a fully automatic and reproducible short echo-time (STE) magnetic resonance imaging (MRI) segmentation approach for MR-based attenuation correction of positron emission tomography (PET) data in head region.

Procedures

Single STE-MR imaging was followed by generating attenuation correction maps (μ-maps) through exploiting an automated clustering-based level-set segmentation approach to classify head images into three regions of cortical bone, air, and soft tissue. Quantitative assessment was performed by comparing the STE-derived region classes with the corresponding regions extracted from X-ray computed tomography (CT) images.

Results

The proposed segmentation method returned accuracy and specificity values of over 90 % for cortical bone, air, and soft tissue regions. The MR- and CT-derived μ-maps were compared by quantitative histogram analysis.

Conclusions

The results suggest that the proposed automated segmentation approach can reliably discriminate bony structures from the proximal air and soft tissue in single STE-MR images, which is suitable for generating MR-based μ-maps for attenuation correction of PET data.

     

Multi-institutional use of defibrotide in 88 patients after stem cell transplantation with severe veno-occlusive disease and multisystem organ failure: response without significant toxicity in a high-risk population and factors predictive of outcome

Veno-occlusive disease (VOD) is the most common regimen-related toxicity accompanying stem cell transplantation (SCT). Severe VOD complicated by multisystem organ failure (MOF) remains almost uniformly fatal. Preliminary experience with defibrotide (DF), a single-stranded polydeoxyribonucleotide with fibrinolytic, antithrombotic, and anti-ischemic properties, in the treatment for severe VOD has suggested safety and activity. Eighty-eight patients who developed severe VOD after SCT were treated with DF under a defined treatment plan. At diagnosis, median bilirubin was 76.95 microM (4.5 mg/dL), median weight gain was 7%, ascites was present in 84%, and abnormal hepatic portal venous flow was present in 35%. At DF initiation, median bilirubin had increased to 215.46 microM (12.6 mg/dL), and MOF was present in 97%. DF was administered intravenously in doses ranging from 5 to 60 mg/kg per day for a median of 15 days. No severe hemorrhage or other serious toxicity related to DF was reported. Complete resolution of VOD was seen in 36%, with 35% survival at day +100. Predictors of survival included younger age, autologous SCT, and abnormal portal flow, whereas busulfan-based conditioning and encephalopathy predicted worse outcome. Decreases in mean creatinine and plasminogen activator inhibitor 1(PAI-1) levels during DF therapy predicted better survival. The complete response rate, survival to day +100, and absence of significant DF-associated toxicity in this largest patient cohort reported to date confirm the results of earlier studies. Certain features associated with successful outcome may correlate with DF-related treatment effects, and prospective evaluation of DF therapy for severe VOD should allow better definition of predictors of response or failure.     

Socio-Behavioral Factors Associated with Overweight and Central Obesity in Tehranian Adults: a Structural Equation Model

Purpose

This study aimed to test a conceptual model of associations between socio-demographic and behavioral factors and obesity in the Tehran Lipid and Glucose Study (TLGS).

Methods

Data from 2747 TLGS adult participants (58.3 % female) were analyzed. Socio-demographic and behavioral factors in the conceptual model were tested for their direct and indirect associations with overweight and central obesity, using structural equation modeling (SEM), conducted by IBM SPSS AMOS software.

Results

Overweight and central obesity were found in 61.6 and 48.1 % of respondents, respectively. Fit indices were acceptable for the conceptual model. Daily energy intake had a direct association with overweight and central obesity in both genders; however, poor dietary pattern had direct associations with overweight and central obesity only in men. In women, age, marital status, and level of education had direct associations with overweight and central obesity. In men, only age and marital status had direct associations with overweight and central obesity.

Conclusions

Age and marital status in both genders and level of education only in women were among the socio-demographic factors which were directly associated with both overweight and central obesity. Among behavioral factors, daily energy intake was the most important factor that was directly associated with both overweight and central obesity in both genders. Adherence to poor diet directly was associated with overweight and central obesity only in men. The current findings provide beneficial information for designing culturally relevant and effective interventions/strategies for prevention of overweight among Tehranian adults.

     

Mesenchymal Stem Cells Pretreatment With Stromal-Derived Factor-1 Alpha Augments Cardiac Function and Angiogenesis in Infarcted Myocardium

BackgroundStem cell therapy is among the novel approaches for the treatment of post-myocardial infarction cardiomyopathy. This study aims to compare the effect of stromal-derived factor 1 α (SDF1α), mesenchymal stem cells (MSCs) in combination with the lentiviral production of vascular endothelial growth factor (VEGF) on infarct area, vascularization and eventually cardiac function in a rat model of myocardial infarction (MI).MethodsThe influence of SDf1α on MSCs survival was investigated. MSCs were transduced via a lentiviral vector containing VEGF. After that, the effect of mesenchymal stem cell transfection of VEGF-A165 and SDf1α preconditioning on cardiac function and scar size was investigated in five groups of MI rat models. The MSC survival, cardiac function, scar size, angiogenesis, and lymphocyte count were assessed 72 hours and 6 weeks after cell transplantation.ResultsSDF1α decreased the lactate dehydrogenase release in MSCs significantly. Also, the number of viable cells in the SDF1α-pretreated group was meaningfully more than the control. The left ventricular systolic function significantly enhanced in groups with ^p240MSC, ^SDF1αMSC, and ^VEGF-A165MSC in comparison to the control group.ConclusionsThese findings suggest that SDF1α pretreatment and overexpressing VEGF in MSCs could augment the MSCs' survival in the infarcted myocardium, reduce the scar size, and improve the cardiac systolic function.     

Cone-beam Computed Tomographic Analysis of Canal Transportation and Centering Ability of Single-file Systems

Introduction

The purpose of this study was to compare canal transportation and the centering ability of Reciproc (VDW, Munich, Germany), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), and EdgeFile (EdgeEndo, Albuquerque, NM) rotary systems using cone-beam computed tomographic imaging.

Enlarged Areas of Pain and Pressure Hypersensitivityby Spatially Distributed Intramuscular Injections ofLow-Dose Nerve Growth Factor

Intramuscular injection of nerve growth factor (NGF) causes muscle hyperalgesia without immediate pain. This double-blinded, randomized study assessed pain and muscle hypersensitivity after a single-site bolus NGF injection (5 µg) compared with 5 spatially distributed, low-dose NGF injections (1 µg, 4 cm distance) into the tibialis anterior (TA) muscles in 20 healthy subjects. Injection pain was rated on a visual analog scale. Reports of muscle pain with functional tasks (Likert scale score) and the presence of spontaneous pain were collected daily by using a diary. Pressure pain threshold (PPT), overall pain intensity (numerical rating scale), and pain areas following the TA contraction were collected at baseline; 3 hours; and 1, 3, 7, 14, and 21 days postinjection. Low immediate visual analog scale scores were associated with both injection protocols. Likert scale scores showed moderate pain intensities but no spontaneous pain, until day 12, for both injection protocols (P < .05). Reduced PPTs at the 5- and 1-µg injection sites were found after 3 hours, lasting until day 7 (P < .05). The 1-µg injection provoked decreased PPTs at day 1 (P = .036) at the proximal injection site and at day 1 (P = .02) and day 3 (P = .01) at the distal injection site. The TA muscle contraction resulted in larger pain areas and higher numerical rating scale scores at day 3 for the distributed injections compared with the single-site injection (P < .001).Perspective: Spatially distributed low-dose NGF injections induced prolonged pain, mechanical muscle hypersensitivity, and enlarged contraction-evoked pain areas. These features mirror some clinical muscle pain conditions in which diffuse pain areas and muscle hypersensitivity are present during the activities of daily living. Low-dose NGF injections may be useful for further studies of prolonged pain conditions.