Evaluation of Focal Ablation of Magnetic Resonance Imaging Defined Prostate Cancer Using Magnetic Resonance Imaging Controlled Transurethral Ultrasound Therapy with Prostatectomy as the Reference Standard.

PURPOSE: We evaluated magnetic resonance imaging controlled transurethral ultrasound therapy as a treatment for magnetic resonance imaging defined focal prostate cancer using subsequent prostatectomy and histology as the reference standard. MATERIALS AND METHODS: Five men completed this pilot study, which was approved by the institutional review board. Prior to radical prostatectomy focal tumors identified by magnetic resonance imaging were treated by coagulating targeted subtotal 3-dimensional volumes of prostate tissue using magnetic resonance imaging controlled transurethral focused ultrasound. Treatment was performed with a 3 Tesla clinical magnetic resonance imaging unit combined with modified clinical planning software for high intensity focused ultrasound therapy. After prostatectomy whole mount histological sections parallel to the magnetic resonance imaging treatment planes were used to compare magnetic resonance imaging measurements with thermal damage at the cellular level and, thus, evaluate treatment and target accuracy. RESULTS: Three-dimensional target volumes of 4 to 20 cc and with radii up to 35 mm from the urethra were treated successfully. Mean ± SD temperature control accuracy at the target boundary was -1.6 ± 4.8C and the mean spatial targeting accuracy achieved was -1.5 ± 2.8 mm. Mean treatment accuracy with respect to histology was -0.4 ± 1.7 mm with all index tumors falling inside the histological outer limit of thermal injury. CONCLUSIONS: Magnetic resonance imaging guided transurethral ultrasound therapy is capable of generating thermal coagulation and tumor destruction in targeted 3-dimensional angular sectors out to the prostate capsule for prostate glands up to 70 cc in volume. Ultrasound parameters needed to achieve ablation at the prostate capsule were determined, providing a foundation for future studies.

An MRI-compatible platform for one-dimensional motion management studies in MRI.

PURPOSE: Abdominal MRI remains challenging because of respiratory motion. Motion compensation strategies are difficult to compare clinically because of the variability across human subjects. The goal of this study was to evaluate a programmable system for one-dimensional motion management MRI research. METHODS: A system comprised of a programmable motorized linear stage and computer was assembled and tested in the MRI environment. Tests of the mutual interference between the platform and a whole-body MRI were performed. Organ trajectories generated from a high-temporal resolution scan of a healthy volunteer were used in phantom tests to evaluate the effects of motion on image quality and quantitative MRI measurements. RESULTS: No interference between the motion platform and the MRI was observed, and reliable motion could be produced across a wide range of imaging conditions. Motion-related artifacts commensurate with motion amplitude, frequency, and waveform were observed. T2 measurement of a kidney lesion in an abdominal phantom showed that its value decreased by 67% with physiologic motion, but could be partially recovered with navigator-based motion-compensation. CONCLUSION: The motion platform can produce reliable linear motion within a whole-body MRI. The system can serve as a foundation for a research platform to investigate and develop motion management approaches for MRI. Magn Reson Med 76:702-712, 2016. © 2015 Wiley Periodicals, Inc.

Temperature-dependent MR signals in cortical bone: potential for monitoring temperature changes during high-intensity focused ultrasound treatment in bone.

PURPOSE: Because existing magnetic resonance thermometry techniques do not provide temperature information within bone, high-intensity focused ultrasound (HIFU) exposures in bone are monitored using temperature changes in adjacent soft tissues. In this study, the potential to monitor temperature changes in cortical bone using a short TE gradient echo sequence is evaluated. METHODS: The feasibility of this proposed method was initially evaluated by measuring the temperature dependence of the gradient echo signal during cooling of cortical bone samples implanted with fiber-optic temperature sensors. A subsequent experiment involved heating a cortical bone sample using a clinical MR-HIFU system. RESULTS: A consistent relationship between temperature change and the change in magnitude signal was observed within and between cortical bone samples. For the two-dimensional gradient echo sequence implemented in this study, a least-squares linear fit determined the percentage change in signal to be (0.90 ± 0.01)%/°C. This relationship was used to estimate temperature changes observed in the HIFU experiment and these temperatures agreed well with those measured from an implanted fiber-optic sensor. CONCLUSION: This method appears capable of displaying changes related to temperature in cortical bone and could improve the safety of MR-HIFU treatments. Further investigations into the sensitivity of the technique in vivo are warranted.

Association between nocturnal blood pressure dipping and insulin resistance in children affected by NAFLD.

UNLABELLED: The aim of this study was to analyse the relationship between insulin-glucose metabolism, nocturnal blood pressure dipping and nonalcoholic fatty liver disease (NAFLD) in obese adolescents without diabetes. One hundred one consecutive children, with biopsy-proven NAFLD, were included in this study. Blood samples were drawn for the analyses of liver function tests, insulin-glucose metabolism and lipid profile appraisal. An ambulatory blood pressure measurement (ABPM) was performed. Seventy-six children (75.3 %) were systolic nondippers, and 23 of them were diastolic nondippers (30.3 %). No differences were found in the anthropometric parameters between the two groups. When compared to the systolic dippers, the systolic nondippers had higher medians of mean nocturnal blood pressure, glucose at 0, 60 and 120 min in the oral glucose tolerance test (OGTT), OGTT insulin at all time points and insulin-resistance values. No correlation of histopathological features with dipping/nondipping statuses was found. CONCLUSIONS: We found an association between a nocturnal blood pressure fall and measures of insulin levels, independent of obesity, or daytime blood pressure levels, among the obese patients with NAFLD. Although no association between nondipping profiles and NAFLD was observed in our study, further studies with a longer term follow-up are needed, to better elucidate the complex link between these particular entities.

The effect of Zizyphus spina-christi leaf extract on the isolated rat aorta.

OBJECTIVE: To investigate the effect of Zizyphus spina christi leaf hydroalcoholic extract (ZLHE) on the isolated rat aorta. METHODS: The rings of the endothelium intact and denuded thoracic aorta of Male and female Sprague Dawley rats were placed in Krebs-Henseleit solution to measure isometric contractile force. To study the involvement of voltage dependent L type calcium channels, concentration of 10 ?M verapamil was applied. Potassium chloride (50 mM) was also added to the organ bath to compare the effect of extract and KCl. Potassium concentration of the extract at 2.5 and 5 mg/ml was measured. RESULTS: ZLHE induced contraction in the endothelium intact and denuded aorta dose dependently and significantly (P < 0.0001). Also, the response to extract at 5 mg/ml was similar to that of KCl (50 mM). The application of verapamil reduced the contraction in the endothelium intact and denuded aorta by 66.7 +/- 3.1% (mean +/- SEM.) and 71.6 +/- 3.8% respectively. CONCLUSION: The results showed the vasoconstrictive effect of ZLHE which was not endothelium-dependent and largely blocked by verapamil, suggesting that the voltage-dependent Calcium channels play a pivotal role in the mechanism of action.

Influence of geometric and material properties on artifacts generated by interventional MRI devices: Relevance to PRF-shift thermometry.

PURPOSE: Magnetic resonance imaging (MRI) is capable of providing valuable real-time feedback during medical procedures, partly due to the excellent soft-tissue contrast available. Several technical hurdles still exist to seamless integration of medical devices with MRI due to incompatibility of most conventional devices with this imaging modality. In this study, the effect of local perturbations in the magnetic field caused by the magnetization of medical devices was examined using finite element analysis modeling. As an example, the influence of the geometric and material characteristics of a transurethral high-intensity ultrasound applicator on temperature measurements using proton resonance frequency (PRF)-shift thermometry was investigated. METHODS: The effect of local perturbations in the magnetic field, caused by the magnetization of medical device components, was examined using finite element analysis modeling. The thermometry artifact generated by a transurethral ultrasound applicator was simulated, and these results were validated against analytic models and scans of an applicator in a phantom. Several parameters were then varied to identify which most strongly impacted the level of simulated thermometry artifact, which varies as the applicator moves over the course of an ablative high-intensity ultrasound treatment. RESULTS: Key design parameters identified as having a strong influence on the magnitude of thermometry artifact included the susceptibility of materials and their volume. The location of components was also important, particularly when positioned to maximize symmetry of the device. Finally, the location of component edges and the inclination of the device relative to the magnetic field were also found to be important factors. CONCLUSIONS: Previous design strategies to minimize thermometry artifact were validated, and novel design strategies were identified that substantially reduce PRF-shift thermometry artifacts for a variety of device orientations. These new strategies are being incorporated into the next generation of applicators. The general strategy described in this study can be applied to the design of other interventional devices intended for use with MRI.

Assessing Markov and time homogeneity assumptions in multi-state models: application in patients with gastric cancer undergoing surgery in the Iran cancer institute.

BACKGROUND: Multi-state models are appropriate for cancer studies such as gastrectomy which have high mortality statistics. These models can be used to better describe the natural disease process. But reaching that goal requires making assumptions like Markov and homogeneity with time. The present study aims to investigate these hypotheses. MATERIALS AND METHODS: Data from 330 patients with gastric cancer undergoing surgery at Iran Cancer Institute from 1995 to 1999 were analyzed. To assess Markov assumption and time homogeneity in modeling transition rates among states of multi-state model, Cox-Snell residuals, Akaikie information criteria and Schoenfeld residuals were used, respectively. RESULTS: The assessment of Markov assumption based on Cox-Snell residuals and Akaikie information criterion showed that Markov assumption was not held just for transition rate of relapse (state 1-state 2) and for other transition rates - death hazard without relapse (state 1-state 3) and death hazard with relapse (state 2-state 3) - this assumption could also be made. Moreover, the assessment of time homogeneity assumption based on Schoenfeld residuals revealed that this assumption - regarding the general test and each of the variables in the model - was held just for relapse (state 1-state 2) and death hazard with a relapse (state 2-state 3). CONCLUSIONS: Most researchers take account of assumptions such as Markov and time homogeneity in modeling transition rates. These assumptions can make the multi-state model simpler but if these assumptions are not made, they will lead to incorrect inferences and improper fitting.

An overview of the epidemiology of primary infertility in iran.

INTRODUCTION: This article compares the prevalence of primary infertility in Iran estimates provided by different studies. No other study had provided a review about the researches related to epidemiology of infertility in the country. MATERIALS AND METHODS: A literature review was undertaken using the scientific resources on the internet and the list of national projects obtained from Deputy of Research and Technology, of Iran Ministry of Health and Medical Education (MOH & ME) and relevant research centers. These resources were attentively reviewed to find about national studies on the epidemiology of primary infertility in Iran during the last decade. Based on their design quality, the National Infertility Study (NIS) (2004-2005), National Health Survey (NHS) (2001) and Tehran Study (1997) were considered for the research. RESULTS: Current primary infertility estimated by National Health Survey (NHS) was 2.8% and by National Infertility Survey (NIS) 3.4%. Tehran study and NIS estimated the prevalence of lifetime primary infertility to be 21.9% and 24.9%, respectively. The minimum prevalence of lifetime primary infertility was found to be 15.8% for the marriage age of 19-27 by Tehran study and 17.2% for the marriage age of 21-26 by NIS. CONCLUSION: On the average, 21-22% of women experience primary infertility during their marital life. The best age of marriage for women in Iran seems to be 20-27 years. At this age group, the lowest number of women (16-18%) would experience primary infertility.