PET, SPECT, and MRI imaging for evaluation of Parkinson's disease.

This review assesses the primary neuroimaging techniques used to evaluate Parkinson's disease (PD) - a neurological condition characterized by gradual dopamine-producing nerve cell degeneration. The neuroimaging techniques explored include positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). These modalities offer varying degrees of insights into PD pathophysiology, diagnostic accuracy, specificity by way of exclusion of other Parkinsonian syndromes, and monitoring of disease progression.

Reprogramming neuroblastoma by diet-enhanced polyamine depletion.

Neuroblastoma is a highly lethal childhood tumor derived from differentiation-arrested neural crest cells. Like all cancers, its growth is fueled by metabolites obtained from either circulation or local biosynthesis. Neuroblastomas depend on local polyamine biosynthesis, with the inhibitor difluoromethylornithine showing clinical activity.

Parkinson's Pals: A Student-Led Program to Facilitate Intergenerational Connections and Promote Psychosocial Well-Being Among Persons with Parkinson's Disease.

Parkinson's disease (PD) causes unique motor and non-motor symptoms. Despite symptomatic treatment with pharmacotherapies, many persons with PD report feelings of loneliness and demoralization as their disease progresses. These symptoms greatly interfere with quality of life, necessitating novel treatment strategies.

Novel technique of detecting inflammatory and osseous changes in the glenohumeral joint associated with patient age and weight using FDG- and NaF-PET imaging.

Objective: The glenohumeral (GH) joint is a classic ball-and-socket joint of the shoulder subject to various pathologies including osteoarthritis (OA). Degenerative changes of the OA evident on traditional imaging are proceeded by molecular changes, which if detected early could enhance disease prevention and treatment. In this study, we use F-FluoroDeoxyGlucose (FDG) and F-sodium-fluoride (NaF)-PET/CT to investigate the effects limb laterality, age, and BMI on the inflammation and bone turnover of the GH shoulder joint.

Exposure limits: the underestimation of absorbed cell phone radiation, especially in children.

The existing cell phone certification process uses a plastic model of the head called the Specific Anthropomorphic Mannequin (SAM), representing the top 10% of U.S. military recruits in 1989 and greatly underestimating the Specific Absorption Rate (SAR) for typical mobile phone users, especially children.

Calculation of magnetic field-induced current densities for humans from EAS countertop activation/deactivation devices that use ferromagnetic cores.

Compliance testing of electronic article surveillance (EAS) devices requires that induced current densities in central nervous system (CNS) tissues, i.e. brain and the spinal cord, be less than the prescribed safety limits.

An open-ended waveguide system for SAR system validation or probe calibration for frequencies above 3 GHz.

Compliance with safety guidelines prescribed in terms of maximum electromagnetic power absorption (specific absorption rate or SAR) for any 1- or 10-g of tissue is required for all newly introduced personal wireless devices such as wireless PCs. The prescribed SAR measuring system is a planar phantom with a relatively thin base of thickness 2.0 mm filled with a lossy fluid to simulate dielectric properties of the tissues.

Computation of electric and magnetic stimulation in human head using the 3-D impedance method.

A comparative, computational study of the modeling of transcranial magnetic stimulation (TMS) and electroconvulsive therapy (ECT) is presented using a human head model. The magnetic fields from a typical TMS coil of figure-eight type is modeled using the Biot-Savart law. The TMS coil is placed in a position used clinically for treatment of depression.

Comparison of various safety guidelines for electronic article surveillance devices with pulsed magnetic fields.

The paper uses the two methods suggested in both the ICNIRP and proposed IEEE safety guidelines for compliance testing of security systems based on time-varying magnetic fields being introduced for electronic article surveillance (EAS), radiofrequency identification, and other applications. For nonsinusoidal pulses that are often used, the two procedures are to treat the exposure as a multifrequency exposure with various frequency components or to calculate the peak induced current densities or electric fields treating the highest of the pulses of duration t(p) as a single frequency, half sinusoid of the same duration and frequency 1/(2t(p)). Using either of the procedures, the induced current densities (J) or electric fields (E) are compared to the basic restrictions on J or E for compliance testing.

SARs for pocket-mounted mobile telephones at 835 and 1900 MHz.

Increasingly, mobile telephones are becoming pocket-sized and are being left in the shirt pocket with a connection to the ear for hands-free operation. We have considered an anatomic model of the chest and a planar phantom recommended by US FCC to compare the peak 1 and 10 g SARs for four typical cellular telephones, two each at 835 and 1900 MHz. An agreement within +/- 10% is obtained between calculated and experimental 1 and 10 g SARs for various separations (2-8 mm) from the planar phantom used to represent different thicknesses of the clothing both for the antenna away from or turned back towards the body.

Electromagnetic fields: human safety issues.

Most of the recently revised safety standards worldwide are set in terms of internal rates of electromagnetic energy deposition (specific absorption rates or SAR) at radio frequencies (RF) and microwave frequencies, and of induced electric fields or current densities at lower frequencies up to 10 MHz. Numerical methods have been developed that use millimeter resolution anatomically based models of the human body to determine SAR or the induced electric fields and current densities for real-life EM exposure conditions. A popular method for use at RF and microwave frequencies is the finite-difference time-domain method.

Some present problems and a proposed experimental phantom for SAR compliance testing of cellular telephones at 835 and 1900 MHz.

This paper compares the maximum allowable powers of some typical cellular telephones at 835 and 1900 MHz for compliance with the limits of specific absorption rates (SAR) given in ANSI/IEEE, ICNIRP and the proposed modification of ANSI/IEEE safety guidelines. It is shown that the present ANSI/IEEE guideline is the most conservative with the ICNIRP guidelines allowing a maximum radiated powerthat is 2.5-3 times higher, and the proposed IEEE modification of treating pinna as an extremity tissue the least conservative allowing even higher radiated powers by up to 50%.

Calculation of induced current densities for humans by magnetic fields from electronic article surveillance devices.

This paper illustrates the use of the impedance method to calculate the electric fields and current densities induced in millimetre resolution anatomic models of the human body, namely an adult and 10- and 5-year-old children, for exposure to nonuniform magnetic fields typical of two assumed but representative electronic article surveillance (EAS) devices at 1 and 30 kHz, respectively. The devices assumed for the calculations are a solenoid type magnetic deactivator used at store checkouts and a pass-by panel-type EAS system consisting of two overlapping rectangular current-carrying coils used at entry and exit from a store. The impedance method code is modified to obtain induced current densities averaged over a cross section of 1 cm2 perpendicular to the direction of induced currents.

Currents induced in anatomic models of the human for uniform and nonuniform power frequency magnetic fields.

We have used the quasi-static impedance method to calculate the currents induced in the nominal 2 x 2 x 3 and 6 mm resolution anatomically based models of the human body for exposure to magnetic fields at 60 Hz. Uniform magnetic fields of various orientations and magnitudes 1 or 0.417 mT suggested in the ACGIH and ICNIRP safety guidelines are used to calculate induced electric fields or current densities for the various glands and organs of the body including the pineal gland.

Inter-laboratory comparison of numerical dosimetry for human exposure to 60 Hz electric and magnetic fields.

In recent years, with the availability of high resolution models of the human body, numerical computations of induced electric fields and currents have been made in more than one laboratory for various exposure conditions. Despite the verification of computational methods, questions are often asked about the reliability of these data. In this paper, computational results from two laboratories that presented data in compatible formats are compared, supplemented with additional data from the third laboratory.

Comparison of numerical and experimental methods for determination of SAR and radiation patterns of handheld wireless telephones.

Some recent developments in both the numerical and experimental methods for determination of SARs and radiation patterns of handheld wireless telephones are described, with emphasis on comparison of results using the two methods. For numerical calculations, it was possible to use the Pro-Engineer CAD Files of cellular telephones for a realistic description of the device. Also, we used the expanding grid formulation of the finite-difference time-domain (FDTD) method for finer-resolution representation of the coupled region, including the antenna, and an increasingly coarser representation of the more-distant, less-coupled region.

Specific absorption rates and induced current densities for an anatomy-based model of the human for exposure to time-varying magnetic fields of MRI.

A 6-mm resolution, 30-tissue anatomy-based model of the human body is used to calculate specific absorption rate (SAR) and the induced current density distributions for radiofrequency and switched gradient magnetic fields used for MRI, respectively. For SAR distributions, the finite-difference time-domain (FDTD) method is used including modeling of 16-conductor birdcage coils and outer shields of dimensions that are typical of body and head coils and a new high-frequency head coil proposed for the 300-400 MHz band. SARs at 64, 128, and 170 MHz have been found to increase with frequency (f) as f(k) where k is on the order of 1.

Head and neck resonance in a rhesus monkey--a comparison with results from a human model.

The use of primates for examining the effects of electromagnetic radiation on behavioural patterns is well established. Rats have also been used for this purpose. However, the monkey is of greater interest as its physiological make-up is somewhat closer to that of the human.

Comparison of cardiac-induced endogenous fields and power frequency induced exogenous fields in an anatomical model of the human body.

Time-domain potentials measured at 64 points on the surface of a large canine heart, considered comparable with those of a human heart, were used to calculate the electric fields and current densities within various organs of the human body. A heterogeneous volume conductor model of an adult male with a resolution of approximately 6 mm3 and 30 segmented tissue types was used along with the admittance method and successive over-relaxation to calculate the voltage distribution throughout the torso and head as a function of time. From this time-domain voltage description, values of [E(t)] and [J(t)] were obtained, allowing for maximum values to be found within the given tissues of interest.

Power deposition in the head and neck of an anatomically based human body model for plane wave exposures.

At certain frequencies, when the human head becomes a resonant structure, the power absorbed by the head and neck, when the body is exposed to a vertically polarized plane wave propagating from front to back, becomes significantly larger than would ordinarily be expected from its shadow cross section. This has possible implications in the study of the biological effects of electromagnetic fields. Additionally the frequencies at which these resonances occur are not readily predicted by simple approximations of the head in isolation.

Calculation of electric fields and currents induced in a millimeter-resolution human model at 60 Hz using the FDTD method.

The finite-difference time-domain (FDTD) method has previously been used to calculate induced currents in anatomically based models of the human body at frequencies ranging from 20 to 915 MHz and resolutions down to about 1.25 cm. Calculations at lower frequencies and higher resolutions have been precluded by the huge number of time steps that would be needed in these simulations.