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This paper presents an innovative approach for terahertz (THz) band communications, utilizing reconfigurable intelligent surfaces (RISs) to implement an angular-based hybrid beamforming (AB-HBF). This study examines two significant THz channel scenarios with cost-efficient solutions utilizing RISs to enhance performance. The first scenario ensures reliable communication in the presence of obstacles blocking the direct path, where RISs offer an alternative transmission path. The second scenario leverages multiple-RIS in line-of-sight dominant or sparse environments to increase the rank of the channel matrix, consequently improving the achievable rate. By introducing an innovative HBF design for multiple-RIS-assisted THz massive MIMO systems, a three-stage design is proposed based on a geometry-based THz channel model. This design encompasses the transmit and receive radio frequency (RF) beamformers, transmit/receive baseband (BB) precoder/combiner, and RIS phase shift matrix. A particle swarm optimization-based solution is employed to design the RIS phase reflections. This design methodology is extended to the multiple-RIS-aided scenario, optimizing the phase shift matrices of each RIS. We also provide sub-connected AB-HBF configuration by offering a remarkable reduction in the total number of phase shifters compared to the fully-connected AB-HBF. Additionally, a deep learning-based phase shift design is incorporated to effectively optimize the RIS configurations, significantly reducing the computational time required for system calibration in dynamic THz environments. Extensive numerical experiments demonstrate the significant enhancement in the achievable rate of THz AB-HBF systems by incorporating RISs, mitigating the wireless propagation disruptions as well as reducing hardware cost/complexity and power consumption for massive MIMO systems.

This paper presents a novel approach to full-duplex (FD) massive multiple-input multiple-output (mMIMO) systems using hybrid beamforming (HBF) architecture, enabling simultaneous uplink (UL) and downlink (DL) transmission within the same frequency band. The proposed solution aims to mitigate strong self-interference (SI) and maximize the total achievable rate based on over-the-air (OTA) measurements of the SI channel. Our objective is to leverage the spatial degrees of freedom (DoF) in mMIMO systems to enhance FD capacity without the need for expensive analog SI-cancellation circuitry. To address this challenging issue, we employ a sub-array configuration for transmit and receive antennas at the base station (BS) and design the RF stages using non-orthogonal beamforming (NOBF) in both UL and DL user directions. Additionally, sub-array selection (SAS) is utilized to identify the optimal Tx-Rx antenna pair. To solve the non-convex multi-objective optimization problem (MOOP), we propose a swarm intelligence-based algorithmic solution to determine the optimal perturbations in user directions jointly with Tx-Rx sub-array indices while satisfying directivity degradation constraints. The illustrative results show that the proposed NOBF scheme with SAS can achieve an SI suppression of −78 dB. Furthermore, in FD mMIMO systems, this approach can effectively double the capacity compared to half-duplex (HD) transmissions.

In-band full-duplex (FD) operation can double the spectral efficiency of massive multiple-input multiple-output (mMIMO) systems by allowing simultaneous transmission and reception over the same time/frequency slot. However, the main challenge encountered in implementing an FD radio wireless transceiver is to greatly suppress the residual self-interference (SI) generated from its own transmitter below the receiver noise floor to avoid performance degradation in the detection of the signal of interest received from remote transmitters. It is pointed out that the single-stage digital beamforming (DBF) scheme would introduce an impractically high complexity unsuitable for implementing FD-mMIMO. This paper considers an FD hybrid beamforming (FD-HBF) scheme for multi-user (MU)-mMIMO systems, in which large SI-suppression is achieved by exploring dynamic transmitter/receiver (Tx/Rx) isolation using RF-beamforming designs, and exploiting the degrees of freedom of a large number of antenna elements in separate Tx and Rx antenna arrays, in conjunction with high-performance baseband (BB) digital fractionally-spaced (FS) SI-cancellation (SIC) techniques. This paper starts with a discussion of the main parameters and impairments (in an mMIMO transceiver) that can impact the SI-suppression performance and the proposed RF-beamforming Tx/Rx isolation and BB SI-cancellation design strategies along with their achieved performance and complexities. Joint-beamforming optimization to maximize both Tx/Rx performance and isolation is discussed with an example of a nature-inspired optimization scheme to achieve an average Tx/Rx RF isolation of 64.4 dB and the best isolation of 76 dB. The paper continues with a description of an FD-mMIMO transceiver prototype using Tx/Rx 8x8-element antenna arrays along with analytical, simulation and measured results. Illustrative results indicate that the proposed combination of RF-beamforming Tx/Rx isolation and BB digital fractionally spaced SI-cancellation can offer an overall SI suppression of more than 131 dB and bring the residual SI below the receiver noise floor.

This work introduces a novel full-duplex hybrid beamforming (FD-HBF) technique for the millimeter-wave (mmWave) multi-user massive multiple-input multiple-output (MU-mMIMO) systems, where a full-duplex (FD) base station (BS) simultaneously serves half-duplex (HD) downlink and uplink user equipments over the same frequency band. Our main goal is jointly enhancing the downlink/uplink sum-rate capacity via the successful cancellation of the strong self-interference (SI) power. Furthermore, FD-HBF remarkably reduces the hardware cost/complexity in the mMIMO systems by interconnecting the radio frequency (RF) and baseband (BB) stages via a low number of RF chains. First, the RF-stage is constructed via the slow time-varying angular information, where two schemes are proposed for both maximizing the intended signal power and canceling the SI power. Particularly, orthogonal RF beamformer (OBF) scheme only aims canceling the far-field component of SI, while non-orthogonal RF beamformer (NOBF) scheme applies perturbations to the orthogonal beams for also suppressing the near-field component of SI channel. Considering the high computational complexity during the search for optimal perturbations, we apply swarm intelligence to find the optimal perturbations. Second, the BB-stage is designed based on only the reduced-size effective intended channel matrices, where the BB precoder/combiner solutions are obtained via regularized zero-forcing (RZF) and minimum mean square error (MMSE). Hence, the proposed FD-HBF technique does not require the instantaneous SI channel knowledge. It is shown that FD-HBF with NOBF+MMSE achieves 78.1 dB SI cancellation (SIC) on its own. Additionally, FD-HBF with the practical antenna isolation can accomplish more than 130 dB SIC and reduce the SI power below the noise floor. The numerical results present that FD-HBF greatly improves the sum-rate capacity by approximately doubling it compared to its HD counterpart.

Millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems have been considered as one of the primary candidates for the fifth generation (5G) and beyond 5G wireless communication networks to satisfy the ever-increasing capacity demands. Full-duplex technology can further enhance the advantages of mmWave massive MIMO systems. However, the strong self-interference (SI) is the major limiting factor in the full-duplex technology. Hence, this paper proposes a novel angular-based joint hybrid precoding/combining (AB-JHPC) technique for the full-duplex mmWave massive-MIMO systems. Our primary goals are listed as: (i) improving the self-interference cancellation (SIC), (ii) increasing the intended signal power, (iii) decreasing the channel estimation overhead, (iv) designing the massive MIMO systems with a low number of RF chains. First, the RF-stage of AB-JHPC is developed via slow time-varying angle-of-departure (AoD) and angle-of-arrival (AoA) information. A joint transmit/receive RF beamformer design is proposed for covering (excluding) the AoD/AoA support of intended (SI) channel. Second, the BB-stage of AB-JHPC is constructed via the reduced-size effective intended channel. After using the well-known singular value decomposition (SVD) approach at the BB-stage, we also propose a new semi-blind minimum mean square error (S-MMSE) technique to further suppress the residual SI power by using AoD/AoA parameters. Thus, the instantaneous SI channel knowledge is not needed in the proposed AB-JHPC technique. Finally, we consider a transfer block architecture to minimize the number of RF chains. The numerical results demonstrate that the SI signal is remarkably canceled via the proposed AB-JHPC technique. It is shown that AB-JHPC achieves 85.7 dB SIC and the total amount of SIC almost linearly increases via antenna isolation techniques. We observe that the proposed full-duplex mmWave massive MIMO systems double the achievable rate capacity compared to its half-duplex counterpart as the antenna array size increases and the transmit/receive antenna isolation improves. Moreover, the proposed S-MMSE algorithm provides considerably high capacity than the conventional SVD approach.

This paper investigates a multi-user massive multiple-input multiple-output (MU-mMIMO) hybrid precoding (HP) scheme using low-resolution phase shifters (PSs) and digital-to-analog converters (DACs). The proposed HP approach involves two stages: RF beamforming based on the slowly time-varying channel second-order correlation matrix, and baseband MU precoding based on the instantaneous effective baseband channel to mitigate MU-interference by a regularized zero-forcing (RZF) technique. We consider three HP design architectures: (i) HP using full-resolution PSs and DACs, with a baseband transfer block for constant-modulus RF beamformer, (ii) HP using $b$ -bit PSs and full-resolution DACs, with an orthogonal matching pursuit (OMP) based algorithm that can approach the optimal unconstrained RF beamformer, and (iii) HP using $b$ -bit PSs and $q$ -bit DACs, taking into account also DAC quantization noise. Illustrative results show that the proposed HP schemes with low-resolution PSs can approach the sum-rate of full-resolution PSs by using only 2-bit PSs, while offering higher energy efficiency. Furthermore, a study of sum-rate results for various PS and DAC quantization levels reveals that HP can achieve near-optimal performance with only 2-bit PSs and 5-bit DACs. Moreover, a comparison of the different array configurations, namely, uniform linear array (ULA), uniform circular array (UCA), uniform rectangular array (URA), and concentric circular array (CCA), indicates that URA and CCA outperform UCA and ULA in terms of spectral and energy efficiencies.

This paper presents a novel channel estimation technique for the multi-user massive multiple-input multiple-output (MU-mMIMO) systems using angular-based hybrid precoding (AB-HP). The proposed channel estimation technique generates group-wise channel state information (CSI) of user terminal (UT) zones in the service area by deep neural networks (DNN) and fuzzy c-Means (FCM) clustering. The slow time-varying CSI between the base station (BS) and feasible UT locations in the service area is calculated from the geospatial data by offline ray tracing and a DNN-based path estimation model associated with the 1-dimensional convolutional neural network (1D-CNN) and regression tree ensembles. Then, the UT-level CSI of all feasible locations is grouped into clusters by a proposed FCM clustering. Finally, the service area is divided into a number of non-overlapping UT zones. Each UT zone is characterized by a corresponding set of clusters named as UT-group CSI, which is utilized in the analog RF beamformer design of AB-HP to reduce the required large online CSI overhead in the MU-mMIMO systems. Then, the reduced-size online CSI is employed in the baseband (BB) precoder of AB-HP. Simulations are conducted in the indoor scenario at 28 GHz and tested in an AB-HP MU-mMIMO system with a uniform rectangular array (URA) having $16 \times 16=256$ antennas and 22 RF chains. Illustrative results indicate that 91.4% online CSI can be reduced by using the proposed offline channel estimation technique as compared to the conventional online channel sounding. The proposed DNN-based path estimation technique produces same amount of UT-level CSI with runtime reduced by 65.8% as compared to the computationally expensive ray tracing. The imperfection of UT-level CSI introduced by the DNN-based path estimation technique is mitigated by the FCM clustering technique, where the AB-HP using offline UT-group CSI generated by the DNN-based channel estimation model and ray tracing based model for the RF beamformer achieves, respectively, 98.7% and 99.1% sum-rate performance of the fully digital precoding (FDP) technique using full-size online CSI.

This paper proposes a new user grouping algorithm and three-dimensional (3D) angular-based hybrid precoding (AB-HP) scheme for massive multi-user multiple-input multiple-output (MU-MIMO) systems using uniform rectangular arrays (URA). At first, the users clustered in multiple spots are efficiently grouped according to the proposed user grouping algorithm, which only utilizes the user angle-of-departure (AoD) information and does not require prior knowledge of the number of user groups. By employing the AoD support of the user groups, the RF-beamformer of AB-HP is designed to reduce the inter-group interference, the channel state information (CSI) overhead, and the number of RF chains. Then, the digital baseband precoder of AB-HP is constructed via regularized zero-forcing (RZF) using the effective channel seen from baseband to simultaneously serve the users clustered in multiple groups, by considering three approaches: joint-group-processing (JGP), per-group-processing (PGP) and common-group-processing (CGP). For each approach, the signal-to-interference-plus-noise ratio (SINR) expressions as well as their tight deterministic approximations are derived. To further reduce the number of RF chains, we also propose a new transfer block design, which reduces the number of RF chains down to the number of independent data streams without penalizing the sum-rate performance. Illustrative results reveal that the proposed AB-HP schemes with the relaxed CSI estimation overhead and reduced hardware cost/complexity can closely approach to the sum-rate performance of the single-stage fully-digital precoding (FDP). Furthermore, AB-HP has considerably higher energy efficiency performance compared to FDP due to the reduced number of RF chains. We show through simulation that the proposed AB-HP can offer significantly better performance than existing HP techniques. The computational complexity of AB-HP is also analyzed.

In this study, a novel cluster index modulation (CIM) scheme, which is based on indexing the available clusters in the environment, is proposed for future mmWave communication systems. Exploiting the fact that the available clusters in the system are well separated in terms of their angular distribution, we selected the best path for each of them and then performed IM in an algorithmic manner to convey information bits. It is shown that by means of large antenna arrays and analog RF beamforming with the indexed clusters, the destructive effect of inter-beam/cluster interference can be remarkably mitigated. Also, we designed a hybrid beamforming architecture at the transmitter to further reduce the effect of residual inter-beam/cluster interference, where the analog RF beamformer is followed by a digital baseband precoder using the zero-forcing technique. Computer simulations reveal that the proposed scheme can provide better error performance than traditional mmWave communication, and the proposed hybrid architecture outperforms beam index modulation (BIM) for a point-to-point scenario. Semi-analytical derivations and closed-form unconditional pairwise error probability (UPEP) expressions are derived for both analog and hybrid architectures, which confirm the validity and superiority of our proposed scheme.

Abstract We investigate outage performance of fixed-gain and variable-gain amplify-and-forward (AF) full-duplex (FD) relaying systems under residual loop-interference (LI) in non-identical Nakagami-m fading channels. New exact outage probability expressions are derived analytically in a single-integral form by using the cumulative distribution function approach. Moreover, tight lower-bound and asymptotic outage probability expressions are derived in closed-form for the evaluated systems. It is shown that the fixed-gain AF-FD relaying outperforms the variable-gain AF-FD relaying when LI power and/or signal-to-noise ratio increase. The analytical results are verified by Monte-Carlo simulations.

Background: Maternal and infant mortality rates in Tanzania have decreased over the past decades, but remain high. One of the challenges the country faces, is the lack of skilled health care workers. High fertility rates make midwives and their patients particularly susceptible to stress as a result of understaffing. Objective: This paper explores the challenges midwives face in their day-to-day practice at a regional referral hospital in Tanzania, and investigates which measures the midwives themselves find necessary to implement to improve their situation. Methods: A qualitative study design with focus group discussions (FGDs) was employed to explore which challenges the midwives experienced. Each focus group consisted of five to six midwives. A FGD topic guide covering challenges, consequences, motivation, ideal situation and possible solutions was used. These data were analyzed using Systematic Text Condensation. Results: A total of 28 Midwives, six men and 22 women, participated in five FGDs. Four categories emerged from the collected material: Feelings of demoralization, shortage of resources, societal challenges and personal struggles. A feeling of demoralization was especially prevalent and was caused by a lack of support from the leaders and little appreciation from the patients. Shortage of resources, and shortage of personnel in particular, was also highlighted as it led to an excessive workload resulting in difficulties with providing adequate care. These difficulties were intensified by lack of equipment, facilities and a non-optimal organization of the healthcare system. Conclusion: The challenges revealed during the FGDs prevent the midwives from providing sufficient midwifery care. To improve the situation, measures such as supportive leadership, reduction of workload, increasing availability of equipment and increasing knowledge of reproductive health in society, should be taken.

Introduction: Low grade inflammation is associated with chronic spontaneous urticaria (CSU) and atherosclerosis. There are little data on the relationship between urticarial inflammation and atherosclerosis. The neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR) and mean platelet volume (MPV) have recently been studied in many diseases as a biomarker of inflammation., Aim: To evaluate hematologic inflammatory parameters and subclinical atherosclerosis in CSU patients., Material and Methods: C-reactive protein (CRP), NLR, PLR, MPV and carotid intima media thickness (CIMT) in CSU patients were compared with healthy controls. Thirty CSU patients and 30 healthy controls participated in the study., Results: Thirty CSU patients and 30 healthy controls participated in the study. 53.3% of the patient group were females, 46.7% were males and the mean age was 37.7 ±7.7. 53.3% of the healthy control group were females, 46.7% were males and the mean age was 37.1 ±7.2. Body mass index was 24.63 ±2.7 kg/m 2 in the patient group and 24.83 ±2.5 kg/m 2 in the control group. Left and right CIMT and CRP values were higher in CSU patients and high-density lipoproteins (HDL) values were lower in the CSU patients. There was a positive correlation between the right and left CIMT and urticaria activity severity 4 (UAS4), disease severity, and triglycerides in the patient group, also a negative correlation was found between the right and left CIMT and the HDL values. C-reactive protein was also correlated with UAS4 and disease severity., Conclusions: This is the first study to evaluate subclinical atherosclerosis in CSU patients. Chronic spontaneous urticaria may be associated with an increased atherosclerotic risk. Serum CRP concentration can also be used as an objective parameter to evaluate disease severity., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2018 Termedia Sp. z o. o.)

Objective: Psoriasis is a chronic inflammatory disease that affects the skin, joints, and nails. To investigate the efficacy of sonoelastographic evaluation for assessing nail involvement and severity in psoriasis., Materials and Methods: Thirty-one psoriasis patients and 31 healthy control subjects were included in the study. The nail thickness and nail bed thickness of the thumbs of all cases were measured by gray scale ultrasonography. In addition, the values of strain elastography were measured by sonoelastography., Results: Of the participants, 38 were male and 24 were female; the ratio of males and females was equal in both groups. There was no significant difference between the patient and control group in terms of gender and age. In the patient group, the mean duration of illness was 13.87 ± 9.8 years, mean PASI score was 5.53 ± 2.38, and mean NAPSI score was 33.97 ± 37.99. The nail plate thickness and elastography strain ratios were found to be statistically higher in the psoriasis group compared to the control group. There was also significant correlation between elastography strain ratios and nail thickness (P = .014), nail bed thickness (P < .001) and NAPSI scores (P = .01)., Conclusion: Due to the superiority of ultrasound in real-time imaging of the nail structure and the compatibility of sonographic elastography with clinical scores in the assessment of the nail bed, we believe that it can be used as a complementary method.

Objectives: The need for lumbar-lumbosacral fusion surgery has increased in the recent decade. Although this type of surgical approach has been reported to provide better improvement in low back pain compared with conventional conservative treatments, the ratio of failure varies between 5% and 30% in different studies., Methods: This retrospective study was conducted through screening patient files between January 2013 and January 2016. Preoperative and postoperative neurologic examination, Visual Analogue Scale, Oswestry Disability Index, and medical and surgical treatments of 66 patients were evaluated., Results: The data from these 66 patients was included in this study. Of the patients, 28 were male and 38 were female. Mean age was 58.3 years for male and 60.1 years for female subjects. Mean duration of follow-up was 15 months., Conclusions: Our study has revealed that lumbosacral fusion surgery increases sacroiliac joint degeneration. We consider that magnetic resonance imaging is superior to computed tomography for detection of early stage sacroiliac joint degeneration., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Ultrasonography (US) is the most non-invasive, safe, and, especially in the period of infancy, best method for visualizing and examining the spinal cord. Furthermore, US is the primary work-up for development of the spinal canal, and for follow-up on issues relating to subcutaneous tissues, bone development, and the spinal cord. Conus medullaris terminates at the second lumbar vertebra, according to a consensus in the literature., Methods: Healthy children under the age of 6 months who were admitted to the radiology clinic for routine USG follow-ups between the dates of March 2012 to December 2014 were included in this study., Results: Our study includes data from 1125 lumbosacral ultrasounds. The terminal point of the conus level of the attended infants, superior, middle part, inferior of the vertebrae L1, L2, and L3. Furthermore, the termination of the discal distance ratio did not differ significantly between genders., Conclusion: Therefore, according to our results, gender is not an influencing factor in the termination of the spinal cord. Based on the study we performed, as well as the previous literature, in infants without a recognized spinal pathology, the spinal cord is detected below the vertebra L3.

Dyke-Davidoff-Masson syndrome (DDMS) is characterized by cerebral hemiatrophy, seizure, contralateral hemiplegia/hemiparesis, and mental retardation. In this study, clinical and radiological investigations of seven patients who were diagnosed with DDMS as adult age were evaluated and discussed. Seven patients (four male, three female) were included. The mean age ± SD of the patients was 46 ± 21 years. Clinical presentation of six patients was epileptic seizure. One patient was presented with head trauma due to a fall. Two patients had complex partial seizures, three patients had generalized tonic-clonic seizures (GTC), and one had GTC and myoclonic seizure. Mental retardation was in five patients. A congenital cause was detected in one patient in the etiologic investigation and acquired causes in two patients. In four patients, the etiology was not identified. We observed left-hemisphere involvement in four patients and right-hemisphere involvement in three patients. Brain imaging was performed by CT only in four patients and by MRI only in three patients. All patients were diagnosed with DDMS at adulthood. Atrophy in basal ganglia was detected in five patients, and atrophy in brain stem in four patients. Calvarial thickening was observed in four patients. Three patients had hyperpneumatization in mastoid cells. Sinus hyperpneumatization, including the paranasal and frontal sinuses, was seen in six patients. DDMS can also be diagnosed in adulthood symptomatically (mild-severe) or asymptomatically in adulthood. As a result, DDMS is a syndrome with wide clinical and radiological spectra that can be variably symptomatic at different stages of life.

Giant aortic aneurysm is defined as an aneurysm of the aorta of greater than 10 cm in diameter. This rare condition is associated with a high risk of morbidity and mortality and it may lead to fatal complications such as rupture and/or dissection if not managed with proper surgical planning and expertise. Other than atherosclerosis, the main causes of giant ascending aortic aneurysms include Marfan and Ehlers-Danhlos syndromes. Herein we report on a young male patient who had had an aortic valve replacement five years earlier due to a bicuspid aortic valve leading to aortic failure, accompanied by aortic coarctation. He had an aneurysmal expansion rate of 1.81 cm/year to reach a final aneurysmal diameter of 13.25 cm, which, to our knowledge, represents the largest size ever reported in the literature for such lesions, and in which the redo and aneurysmal wall were adjacent to the sternal margins.

Degenerative disc disease and spinal stenosis lead to various symptoms. Degeneration of facet joints is added to this degenerative process with aging.Seventy-four patients who were admitted to the Spinal Column Outpatient Clinic of the Neurosurgery Department with a diagnosis of degenerative narrow spinal canal and lumbar spondylolisthesis between 2011 and 2013 and who underwent surgery were included in the study.Our study was conducted with 74 patients of whom 73.0% (n = 54) were female and 27.0% (n = 20) were male. Mean age was 54.86 ± 7.87 years (range 34-74).Although we did not detect a difference between the two surgical methods with regard to clinical improvement, transforaminal lumbar interbody fusion (TLIF) is preferred due to radiological advantages observed one year later, ease of application, and the development of fewer complications., Competing Interests: The authors have no conflicts of interest to disclose.

The aim of the study was to investigate the relationship between nasal septal deviation and the middle turbinate hypertrophy using computed tomography. In this retrospective analysis, we examined 77 patients with nasal septal deviation. The mucosal and bone structures of the middle turbinate and the angle of the septum were measured using radiological analysis. Measurements of the middle turbinate on the convex side were compared to those on the concave side. Measurements of the bony and mucosal structure area of the middle turbinate were significantly greater than those on the concave side. The dimensions of medial mucosa thickness and bone thickness were not significantly different between the convex and concave sides. No significant correlation was found between the angle of deviation and other parameters. The present findings suggest that compensatory middle turbinate hypertrophy was caused both by conchal bone growth and mucosal hypertrophy in patients with nasal septal deviation.

Spinal dysraphisms are defined as open and closed dysraphisms. A hemivertebra is a congenital condition seen in 61% of patients with congenital anomalies. The first report of the excision of a hemivertebra was by Royle in 1928. A sixteen-year-old girl was admitted to our clinic with a congenital stain on the waist and a normal neurological examination. No new cases have been reported in recent literature. Our case, which is also rare, is associated with a tethered cord only and no other congenital abnormalities.

Spinal fusion surgery techniques develop together with technologic advancements. New complications are seen as the result of new techniques and these may be very severe due to spinal cord and vascular structures in the lumbar region. The posterior lumbar interbody fusion cage (PLIFC) was shown to enhance spinal fusion and to prevent pseudoarthrosis due to its basic dynamic characteristics. PLIFC migrations are usually observed during the postoperative period, just after the mobilization of the patient and usually toward spinal canal. Migration to the retroperitoneal region is a extremely rare condition in the literature. In this article we discussed three cases of PLIFC antepulsion into the retroperitoneal region during the intraoperative period.

Introduction: The success of ACL reconstruction is predicated on a variety of factors. Tunnel placement plays one of the most significant roles in achieving knee kinematics and function. The purposes of this study were to compare femoral tunnel position, angle, length and posterior wall blow-out after ACL reconstruction with hamstring tendons autograft through either a farmedial portal or an anteromedial portal technique., Materials and Methods: We evaluated 36 patients who underwent ACL reconstruction between January 2014 and July 2014 in our institute, in a prospective, randomised cohort study. All the surgical procedures were performed by a sports fellowship-trained orthopaedic surgeon with experience in both portal reaming. The operated knees were evaluated with 0.5 mm fine CT scans of 3-D CT between days 3 and 5 postoperatively., Results: According to the 3-D CT measurements, the mean femoral tunnel length was significantly longer (p < 0.05) in the FAM group compared with the AM group. The femoral bone tunnel length averaged 34.2 ± 3.6 mm versus 36.6 ± 3.0 mm (p = 0.042) in AM and the FAM groups, respectively. The femoral tunnel position, as evaluated with use of the quadrant method, was more anterior in the FAM transportal technique group, and the difference between the two groups was significant (p < 0.05)., Conclusion: FAM tranportal drilling of the femoral tunnel creates longer and anterior femoral tunnels with regard to the AM portal drilling techniques. Additional studies with clinical outcomes are required for the clinical relevance of these techniques and to show which one is superior., Level of Evidence: Level I, prospective randomised comparative cohort study.

Background: Thoracolumbar burst fractures are common clinical entity encountered in neurosurgical practice, accounting for 10-20% of all spinal fractures. Clinical picture could be devastating due to severe neurological deficits which lead the patients dependent both socially and emotionally., Materials and Methods: This study compared two groups of patients who were operated because of thoracolumbar burst fracture secondary to spinal trauma in terms of neurologic deficits, degree of improvement, and radiologic measurements at one-year follow-up. The first group (group I) included the patients who underwent posterior total laminectomy, peroperative reduction of intracanal bone fragments, and posterior spinal instrumentation and the second group (group II) included the patients who underwent total laminectomy, and spinal instrumentation without reduction of free bone fragments., Results: Neither group showed significant correlation with any measurement parameter. Radiological assessments and clinical improvements did not disclosed significant difference between the two groups at one-year follow-up., Conclusion: Retropulsion of free bone fragments extend the time of surgery and causes complications. This study found that there is no need to retropulse the bone fragments in the spinal canal in patients with unstable burst fractures who underwent total laminectomy and posterior long segment stabilization., (Copyright © 2015 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Objective: The aim of the study was to determine the amount of radiation exposure in the orthopedic operating theater, to show that the radiation dose was decreased with distance from the tube, and to inform personnel about protective measures., Methods: Ionised radiation was measured in the orthopedic operating theater where fluoroscopy was used between 18 February 2014 and 02 June 2014. Four dosimeters were placed at the head and foot of the operating table and at 200 cm from those areas at a height of 60 cm vertical to the floor., Results: At the end of 104 days, the total values were determined as 90.5 mrem at the foot of the table, 68.17 mrem at the head of the table, 7.5 mrem at 200 cm from the foot of the table, and 5.17 mrem at 200 cm from the head of the table. A significant decrease was observed in the values determined at a distance from the radiation source., Conclusion: The rate of radiation determined in the dosimeters decreased when distance from the radiation source increased. During the use of fluoroscopy in orthopedic surgery, the wearing of lead aprons, neck protectors, and glasses, in addition to maintaining a distance from the tube, will reduce the radiation exposure of individuals.

With an incidence rate of 15-20%, meningiomas are one of the most common brain tumors among benign intracranial tumors. They are distributed as follows in intracranial localizations: parasagittal and falx (25%), convexity (18%), sphenoid wing (18%), parasellar (12%), posterior fossa (10%), intraventricular (2%), intraorbital (1%), and extracranial (1%). The most common extradural localizations are the paranasal sinuses, nasal cavity, skin, neck, glands, and intraosseous space. Intradiploic meningiomas are generally localized in the frontoparietal and orbital regions. Due to their low incidence and lack of adequate preoperative diagnostic testing, intradiploic meningiomas are generally mistaken for primary calvarial bone tumors and en plaque meningiomas. Our case was discussed here with literature findings since primary intradiploic meningioma is uncommon and poses diagnostic challenges.

Median arcuate ligament syndrome is an anatomic and clinical entity characterized by dynamic compression of the proximal celiac artery by the median arcuate ligament, which leads to postprandial epigastric pain, vomiting, and weight loss. These symptoms are usually nonspecific and are easily misdiagnosed as functional dyspepsia, peptic ulcer disease, or gastropathy. In this report, we presented a 72-year-old male patient with celiac artery compression syndrome causing recurrent abdominal pain associated with gastric ulcer and iron deficiency anemia. This association is relatively uncommon and therefore not well determined. In addition, we reported the CT angiography findings and three-dimensional reconstructions of this rare case.

Purpose: We aimed to compare the inspiratory and expiratory quantitative computed tomography (CT) densitometric data of healthy volunteers, individuals with chronic obstructive pulmonary disease (COPD) risk, and COPD patients to aid in the early diagnosis of COPD., Materials and Methods: Of the study patients, 14 were healthy volunteers (Group I), 12 were patients at risk for COPD (Group II), and 13 were COPD patients (Group III). The high-resolution CT was performed at three levels (the upper, middle, and lower parts of the lungs). All images were evaluated with a specific program for the segmentation of pulmonary parenchyma. The mean lung density (MLD) was measured, and the emphysema index (EI) was calculated using this program., Results: Both MLD values and calculated EI ratios showed significant differences between Groups I and III, and Groups II and III in both expiratory and inspiratory phases (P < 0.05). However, in the comparison of healthy volunteers and patients at risk for COPD (Group I and II), only expiratory-phase MLD values showed statistically significant difference (P < 0.001)., Conclusion: In patients at risk for COPD, expiratory-phase MLD measurements can be used as an early diagnostic method.

The purpose of this study was to analyze the effect of various tube current settings (mAs) and optimize the image quality and dose for adult cranial CT protocol. Sixty adult patients who underwent a cranial CT scanning for different indications were subdivided into three subgroups. Subjective image and noise quality scores and quantitative noise measurements were selectively studied on three reference levels (cerebellar, basal ganglia and centrum semiovale levels). For each subgroup, only one level was studied. Head circumference (HC) and the maximum anteroposterior diameter (MAPD) of each patient were measured. At 50% decreased dose protocol, there was no poor quality score at any level. At nearly 60% decreased dose protocol, the incidence of poor quality scores was much higher at the cerebellar level than at the other two levels. For the same protocol number, quantitative noise measurements were higher at the cerebellar level than the other two supratentorial levels. The correlation was found to be significant between HC, MAPD and quantitative noise measurements, and there was a non-significant correlation between HC and subjective noise scores. In adult cranial CT, depending on the level, a dose reduction of up to 60% may be possible while maintaining image quality.

Purpose: The purpose of this study was to evaluate the role of the subject's position and two different maneuvers in the reflux measurements in femoral veins., Materials and Methods: Venous reflux times in the common femoral vein (CFV) and superficial femoral vein (SFV) were studied in 50 healthy subjects (25 women, 25 male) aged between 22-57 years-old while the subjects were in supine and standing positions. Reflux was provocated only by Valsalva maneuver (VM) when the subject was lying down, whereas it was provocated by (1) Valsalva maneuver and (2) compression and release maneuver, respectively, when the subject was standing. Reflux times were recorded with each of the three methods., Results: Regarding CFV, a reflux time of 1 second or more was recorded in 29 limbs (29%) only in the supine position. Of these 29 measurements, 19 were between 1 and 1.9 sec and 8 between 2 and 2.9 sec. When the subjects were examined in the standing position, the prevalence of reflux lasting more than 1 sec substantially decreased (5%). The prevalence of reflux lasting less than 0.5 sec was 97% with standing compression maneuver, 84% with standing VM and 27% with supine VM. Similarly, prevalence of reflux of longer than 0.5 sec or 1 sec was lower in the standing position than in the supine position in SFV. In CFV, mean reflux time was 1.3 sec in the supine position, whereas it was 0.7 sec and 0.4 sec with standing compression and standing Valsalva maneuvers, respectively. Corresponding values in SFV were 0.5 sec, 0.3 sec and 0.2 sec, respectively., Conclusion: The probability of making a false positive diagnosis of pathological reflux is high with supine examinations. When an examination in the supine position reveals a reflux time of longer than 1 second, making the patient stand up is expected to yield more reliable results. Compression and release maneuver, with its lowest false positive reflux prevalence, is the most reliable method in the evaluation of venous insufficiency.