A novel approach to CSF pressure measurement via lumbar puncture that shortens the measurement time with a high level of accuracy.

Intracranial pressure (ICP) is an important parameter in clinical management and diagnosis of several neurological diseases which is indirectly measured via lumbar puncture (LP). In routine measurements of cerebrospinal fluid pressure (PCSF) from lumbar region, a spinal needle and a spinal manometer are used. PCSF measurement via LP with the use of a spinal manometer may not yield correct PCSF results due to prolonged times required to obtain an accurate pressure value. Equilibrium pressure may be underestimated in circumstances where spinal manometry procedure is terminated prematurely, with the wrong assumption that equilibrium pressure is reached. Elevated PCSF levels can lead to visual loss and brain damage when go undiagnosed. In this study, the spinal needle-spinal manometer combination was modelled with a first-order differential equation and a time constant (τ) was defined as the product of the resistance to flow of the needle with the bore area of the manometer divided by the dynamic viscosity of CSF, i.e. τ= RA/ρCSF. Each needle/manometer combination had a unique constant as a predictor of the equilibrium pressure. The fluid pressure in the manometer rose in an exponential manner which was tested in a simulated environment using 22G spinal needles namely Braun-Spinocan, Pajunk-Sprotte and M.Schilling. Curve fitting of the manometer readings were obtained with regression coefficients of R2 ≥ 0.99 to determine measurement time constants. The residual differences between predicted and true values were less than 1.18 cmH2O. For a given needle/manometer combination, time required to reach equilibrium pressure was identical for all pressure levels. PCSF measured at reduced times can easily be interpolated to their equilibrium level allowing clinicians to obtain PCSF values with high accuracy within seconds. This method can be used as an indirect estimation of ICP in routine clinical practice.

The complex impedance phase angle of dominant arm: a useful parameter in bone mineral density (BMD) assessment of group 1 post-menopausal women.

For widespread osteoporosis (OP) screening, portable and cost-effective screening devices are needed. With 45 menopaused women, when body mass index was below 30 kg.m- 2, the phase angle (PhA) of complex bioimpedance at 5 kHz, measured from the dominant arm, was correlated with dual-energy X-ray absorptiometry (DEXA) measured central bone mineral densities (BMD), for total hip r = 0.493 and for total lumbar r = 0.411, P< 0.05, and the strength of correlation decreased with increasing measurement frequencies. ANOVA tests showed that, below 15 kHz, PhA was a descriptive marker for bone mineral deficiency. By correlating to hip and lumbar bone mineral densities simultaneously, the dominant arm segment PhA was superior to the characteristic frequency fc of the body impedance spectroscopy (BIS) and the PhA of whole-body impedance measurements, of the earlier research works. Due to its medium correlation strength with central BMDs, a PhA measuring device could be considered as a complementary tool to the gold standard (DEXA), for OP screening of group 1 post-menopausal women only. For group 2, with 44 subjects with body mass indices over 30 kg.m- 2, i.e., obese population, the PhA was not correlated with BMD and was no longer a descriptive marker for reduced BMD.

Characterization of carotid endothelial cell proliferation on Au, Au/GO, and Au/rGO surfaces by electrical impedance spectroscopy.

To the best of the authors' knowledge, testing the biocompatibility of graphene coatings can be considered as the first to demonstrate human carotid endothelial cell (HCtAEC) proliferation on Au, graphene oxide-coated Au (Au/GO), and reduced graphene oxide-coated Au (Au/rGO) surfaces. We hypothesized that stent material modified with graphene (G)-based coatings could be used as electrodes for electrical impedance spectroscopy (EIS) in monitoring cell cultures, i.e., endothelialization. Alamar Blue cell viability assay and cell staining and cell counting with optical images were performed. For EIS analysis, an EIS sensor consisting of Au surface electrodes was produced by the photolithographic technique. Surface characterizations were performed by considering scanning electron microscope (SEM) and water contact angle analyses. Results showed that GO and rGO coatings did not prevent neither the electrical measurements nor the cell proliferation and that rGO had a positive effect on HCtAEC proliferation. The rate of increase of impedance change from day 1 to day 10 was nearly fivefold for all electrode surfaces. Alamar Blue assay performed to monitor cell proliferation rates between groups, and rGO has shown the highest Alamar Blue reduction value of 43.65 ± 8.79%. Graphical abstract.

2D-ROC: a receiver operating surface and its illustrative application in clinical diagnostics.

OBJECTIVE: When there are multiple tests, the receiver operating characteristic (ROC) curve analysis does not answer the question of how the individual tests can be combined in medicine. APPROACH: In this study, 2D-ROC analysis is considered to calculate the correct classification rate (CCR) by using two independent test results. To obtain the best combination of paired tests, results were combined as 'BOTH', 'ANY' or 'AVERAGE' for the final 2D-ROC decision. MAIN RESULTS: When the combined model was 'AVERAGE', the CCR was better than individual test results. At every correlation level, the 2D-ROC was shown to have a better CCR compared to individual tests, and when the correlations were lower, the CCR of 2D-ROC was even better. For uncorrelated test pairs (r = 0, p  < 0.0001), in healthy and diseased populations with normal distributions, the improvement in CCR compared to individual tests were from 2.6% to 6.5%, and leptokurtic distribution of diseased population (k = 2, p  < 0.0001) was better by 1.3% to 5.3%. As a clinical application, multifrequency bioelectric impedance (BI) spectroscopy characteristic frequency (f c) and body mass index (BMI) measurements from 53 post-menopausal women were used in finding the 2D-ROC decision matrix to determine the hip area bone mineral deficiency. Using the 'AVERAGE' combination model, the CCR of 2D-ROC was 1.6% better than BMI and 14.8% better than fc alone. In the second clinical application of prediction of metabolic syndrome (MeS), parameters such as BMI, waist circumference, abnormal fasting blood sugar, triglyceride and high-density lipoprotein cholesterol were measured from 5533 subjects and combined to assess individual and paired success rates. Using the 'AVERAGE' combination model, the CCR of pairs were up to 6.1% better compared to using each parameter alone. SIGNIFICANCE: Although the use of a simple 'AVERAGE' function was promising, the formulation for combining paired test results could be extended to include the deviations from ideal by weighted averaging of individual tests or by adding other parameters like their kurtosis or disease prevalence into the formulation.

Estimation of free hemoglobin concentrations in blood bags by diffuse reflectance spectroscopy.

Free hemoglobin (FHB) concentration is considered a prospect quality indicator for erythrocyte suspensions (ES) under storage. Storage lesions alter the optical properties of ES and can be monitored by diffuse reflectance spectroscopy. Due to storage lesions, erythrocytes lyse and release hemoglobin into the extracellular medium. The purpose of the study is to model and assess the quality of ES units in a blood bank with diffuse reflectance measurements together with hematological variables reflecting absorption and scattering characteristics of ES. FHB concentrations were modeled based on the increased scattering in the extracellular medium. A semiempirical model was used for relating optical properties of ES to the diffuse reflectance measurements. The attenuation in the blood bag was computed and its influence was discarded via normalization, in accordance with Monte Carlo simulations. In the experiments, 40 ES units were measured multiple times during prolonged storage of 70 days. A generalized linear model was used for modeling the training set, and, in the validation, the highest correlation coefficient between predicted and actual FHB concentrations was 0.89. Predicting the actual value was accurate at a maximum level of R2 = 0.80. The error rate of the model in diagnosing the true quality was about 10%.

Screening Post-menopausal Women for Bone Mineral Level by Bioelectrical Impedance Spectroscopy of Dominant Arm.

Dominant arm bioimpedance spectroscopy (BIS) and lumbar and hip dual energy X-ray absorptiometry (DXA) measurements were conducted simultaneously on 48 post-menopausal women, aged between 43 and 86 years, with no hip or arm fracture history at Department of Radiology of Istanbul University Cerrahpasa Hospital. According to lumbar DXA results, 21 women were classified as normal, 22 as osteopenia and 5 as osteoporosis; whereas hip DXA results classified 30 women as normal, 15 as osteopenia and 3 as osteoporosis. Only 26 participants had identical lumbar and hip bone mineral density (BMD) diagnostic results. Dominant arm characteristic frequencies of normal subjects were statistically significantly different from osteoporotic subjects based on both lumbar (p < 0.005) and hip classification groups (p < 0.001). Hip and lumbar spine DXA BMD values were significantly correlated (r = 0.55, p < 0.005). The dominant arm BIS characteristic frequency, considered as the single predictor in earlier diagnosis of osteoporosis, was found negatively correlated with DXA measurements for both hip and lumbar spine regions. The Spearman rank correlation coefficient of BIS values with the hip DXA values (r = -0.53, p < 0.001) was higher than that of lumbar spine (r = -0.37, p < 0.001). In receiver operating characteristic (ROC) curve analysis, the best discrimination of dominant arm characteristic frequency was made between normal and osteoporotic subjects based on the hip subgroups (p < 0.001). Both lumbar bone mineral content (BMC) (r = -0.47, p < 0.001) and hip BMC (r = -0.4340, p < 0.005) were statistically significantly correlated with dominant arm characteristic frequency.

Photobiomodulation of wound healing via visible and infrared laser irradiation.

Fibroblast cells are known to be one of the key elements in wound healing process, which has been under the scope of research for decades. However, the exact mechanism of photobiomodulation on wound healing is not fully understood yet. Photobiomodulation of 635 and 809 nm laser irradiation at two different energy densities were investigated with two independent experiments; first, in vitro cell proliferation and then in vivo wound healing. L929 mouse fibroblast cell suspensions were exposed with 635 and 809 nm laser irradiations of 1 and 3 J/cm2 energy densities at 50 mW output power separately for the investigation of photobiomodulation in vitro. Viabilities of cells were examined by means of MTT assays performed at the 24th, 48th, and 72nd hours following the laser irradiations. Following the in vitro experiments, 1 cm long cutaneous incisional skin wounds on Wistar albino rats (n = 24) were exposed with the same laser sources and doses in vivo. Wound samples were examined on 3rd, 5th, and 7th days of healing by means of mechanical tensile strength tests and histological examinations. MTT assay results showed that 635 nm laser irradiation of both energy densities after 24 h were found to be proliferative. One joule per square centimeter laser irradiation results also had positive effect on cell proliferation after 72 h. However, 809 nm laser irradiation at both energy densities had neither positive nor negative affects on cell viability. In vivo experiment results showed that, 635 nm laser irradiation of both energy densities stimulated wound healing in terms of tensile strength, whereas 809 nm laser stimulation did not cause any stimulative effect. The results of mechanical tests were compatible with the histological evaluations. In this study, it is observed that 635 nm laser irradiations of low energy densities had stimulative effects in terms of cell proliferation in vitro and mechanical strength of incisions in vivo. However, 809 nm laser irradiations at the same doses did not have any positive effect.

Laser biostimulation of wound healing: bioimpedance measurements support histology.

Laser biostimulation in medicine has become widespread supporting the idea of therapeutic effects of photobiomodulation in biological tissues. The aim of this study was to investigate the biostimulation effect of laser irradiation on healing of cutaneous skin wounds, in vivo, by means of bioimpedance measurements and histological examinations. Cutaneous skin wounds on rats were subjected to 635 nm diode laser irradiations at two energy densities of 1 and 3 J/cm2 separately. Changes in the electrical properties of the wound sites were examined with multi-frequency electrical impedance measurements performed on the 3rd, 7th, 10th, and 14th days following the wounding. Tissue samples were both morphologically and histologically examined to determine the relationship between electrical properties and structure of tissues during healing. Laser irradiations of both energy densities stimulated the wound healing process. In particular, laser irradiation of lower energy density had more evidence especially for the first days of healing process. On the 7th day of healing, 3 J/cm2 laser-irradiated tissues had significantly smaller wound areas compared to non-irradiated wounds (p < 0.05). The electrical impedance results supported the idea of laser biostimulation on healing of cutaneous skin wounds. Thus, bioimpedance measurements may be considered as a non-invasive supplementary method for following the healing process of laser-irradiated tissues.

Using a low-amplitude RF pulse at echo time (LARFET) for device localization in MRI.

We describe a new method for frequency down-conversion of MR signals acquired with the radio-frequency projections method for device localization. A low-amplitude, off-center RF pulse applied simultaneously with the echo signal is utilized as the reference for frequency down-conversion. Because of the low-amplitude and large offset from the Larmor frequency, the RF pulse minimally interfered with magnetic resonance of protons. We conducted an experiment with the coil placed at different positions to verify this concept. The down-converted signal was transformed into optical signal and transmitted via fiber-optic cable to a receiver unit placed outside the scanner room. The position of the coil could then be determined by the frequency analysis of this down-converted signal and superimposed on previously acquired MR images for comparison. Because of minimal positional errors (≤ 0.8 mm), this new device localization method may be adequate for most interventional MRI applications.

Network security vulnerabilities and personal privacy issues in Healthcare Information Systems: a case study in a private hospital in Turkey.

Healthcare industry has become widely dependent on information technology and internet as it moves from paper to electronic records. Healthcare Information System has to provide a high quality service to patients and a productive knowledge share between healthcare staff by means of patient data. With the internet being commonly used across hospitals, healthcare industry got its own share from cyber threats like other industries in the world. The challenge is allowing knowledge transfer to hospital staff while still ensuring compliance with security mandates. Working in collaboration with a private hospital in Turkey; this study aims to reveal the essential elements of a 21st century business continuity plan for hospitals while presenting the security vulnerabilities in the current hospital information systems and personal privacy auditing standards proposed by regulations and laws. We will survey the accreditation criteria in Turkey and counterparts in US and EU. We will also interview with medical staff in the hospital to understand the needs for personal privacy and the technical staff to perceive the technical requirements in terms of network security configuration and deployment. As hospitals are adopting electronic transactions, it should be considered a must to protect these electronic health records in terms of personal privacy aspects.

Classification of juvenile myoclonic epilepsy data acquired through scanning electromyography with machine learning algorithms.

In this paper, classification of Juvenile Myoclonic Epilepsy (JME) patients and healthy volunteers included into Normal Control (NC) groups was established using Feed-Forward Neural Networks (NN), Support Vector Machines (SVM), Decision Trees (DT), and Naïve Bayes (NB) methods by utilizing the data obtained through the scanning EMG method used in a clinical study. An experimental setup was built for this purpose. 105 motor units were measured. 44 of them belonged to JME group consisting of 9 patients and 61 of them belonged to NC group comprising ten healthy volunteers. k-fold cross validation was applied to train and test the models. ROC curves were drawn for k values of 4, 6, 8 and 10. 100% of detection sensitivity was obtained for DT, NN, and NB classification methods. The lowest FP number, which was obtained by NN, was 5.

Large motor unit territories by scanning electromyography in patients with juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy is a genetically inherited disorder characterized by myoclonic jerks and generalized seizures. It has been proposed that patients with juvenile myoclonic epilepsy have larger motor units (MUs) than normals by MU number estimation and macro electromyography techniques. In this study, an experimental setup for scanning electromyography was built to investigate electrophysiologic cross-sections of the MU territories in 9 patients with juvenile myoclonic epilepsy, 3 patients with spinal muscular atrophy, and 10 healthy volunteers. Scanning electromyography was performed on the biceps brachii muscle. For each MU, three-dimensional maps of the MU territories were plotted. The length of MU cross-section and the maximum amplitude of each MU were measured from these maps and compared among the three groups of subjects. Like spinal muscular atrophy patients, patients with juvenile myoclonic epilepsy had significantly larger MU territories than normal controls.

Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry.

The accuracy of the Leksell GammaPlan, the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near the paranosal sinuses cavities. The homogeneous phantom was a spherical glass balloon of 16 cm diameter, filled with MAGIC gel; i.e., the normoxic polymer gel. Two hollow PVC balls of 2 cm radius, filled with N2 gas, represented the air cavities inside the inhomogeneous phantom. For dose calibration purposes, 100 ml gel-containing vials were irradiated at predefined doses, and then scanned in a MR unit. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. Dose distributions are the results of a single shot of irradiation, obtained by collimating all 201 cobalt sources to a known target in the phantom. Both phantoms were irradiated at the same dose level at the same coordinates. Stereotactic frames and fiducial markers were attached to the phantoms prior to MR scanning. The dose distribution predicted by the Gamma Knife planning system was compared with that of the gel dosimetry. As expected, for the homogeneous phantom the isodose diameters measured by the gel dosimetry and the GammaPlan differed by 5% at most. However, with the inhomogeneous phantom, the dose maps in the axial, coronal and sagittal planes were spatially different. The diameters of the 50% isodose curves differed 43% in the X axis and 32% in the Y axis for the Z =90 mm axial plane; by 44% in the X axis and 24% in the Z axis for the Y=90 mm coronal plane; and by 32% in the Z axis and 42% in the Y axis for the X=92 mm sagittal plane. The lack of ability of the GammaPlan to predict the rapid dose fall off, due to the air cavities behind or near the lesion led to an overestimation of the dose that was actually delivered. Clinically, this can result in underdosing of lesions near tissue inhomogeneities in patients under treatment.

Effects of physiological parameters on the electrical properties of blood bank stored erythrocyte suspensions.

In this study, the physiological parameters such as extracellular (SAGM+CPD+residual plasma) Na+, K+, Cl-, pH, 2,3-DPG and ATP together with the Cole-Cole parameters were measured using erythrocyte suspensions from 51 male donors (31 donors form the training set and 20 donors are used for testing), on the 0th, 10th, 21st, 35th and 42nd days of storage. Accordingly, electrical parameters were all correlated with Na+, K+, Cl-, pH and ATP, at varying levels. By applying the multi-regression analysis, it is concluded that Ri, Re and Cm are appropriate for modeling Na+, K+, Cl-, pH and ATP during blood bank storage and predicting blood quality.

Changes in electrical and physiological properties of human blood during storage.

In this study, the relationship between physiological parameters and electrical impedance changes of human blood and their further clinical implications are investigated. The study is performed on 255 erythrocyte suspension samples derived from 51 male donors. The samples are stored at 4°C and measurements are done on the 0th, 10th, 21st, 35thand 42nddays of storage. The complex impedance is measured in the frequency range from 100 kHz to 1 MHz. The extracellular resistance Reand the effective cell memebrane capacitance Cmincreased progressively with storage time while the intracellular resistance Rihas decreased. Electrical impedance alterations are explained in terms of the measurements of Na+, K+and Cl-concentrations, pH and ATP. Storage of red blood cells resulted in a rise in the extracellular K+and a fall in the extracellular Na+, Cl-, pH and ATP. Variance analysis (ANOVA) is used to evaluate any variations in blood parameters, in relation to storage time. According to the (SPSS) regression analysis, Riand Reare highly correlated with Na+, K+, Cl-and pH and, more significantly with ATP. The Cole-Cole parameters Fcand α showed very little change with storage time and Cmhad weak correlations with blood parameters. Results show that complex impedance measurements may serve as a useful indicator in the quality assessment of blood bank stored blood samples.

Relative dose distribution in gamma knife treatment near tissue inhomogeneties.

The primary goal in this study was to investigate 3-D dose distribution, near the areas of tissue inhomogeneities, in Gamma Knife Radiosurgery with the gel dosimetry. The spherical glass balloon of a diameter of 16 cm filled with the gel forms the homogeneous phantom; and an identical balloon with two corks placed on each side to represent the air cavities forms the inhomogeneous phantom. Dose calibration is performed by irradiating vials at known doses and then utilizing the R2- dose calibration curve. Stereotactic frames and fudicial markers were attached to the phantoms for MR scanning and image processing. Dose distributions from a single shot, using all 201 Cobalt sources, delivered to a known point with identical coordinates, are calculated both in homogeneous and inhomogeneous gel phantoms. In the aspect of dosimetrical quality control, the Gamma Knife planning system predicted dose distribution is compared with the experimental results. In the homogeneous phantom, the gel dosimetry calculated dose distribution is in good agreement with the GammaPlan predicted dose distribution. However, with the inhomogeneous phantom, the dose distribution is spatially different and significant differences in dose levels are observed.