Experimental investigation of products from thermal treatment of real-world mixed single-use and multi-layered waste plastics.

The usage and disposal of highly abundant single-use and multilayered plastics contribute to significant ecological problems. The thermochemical recovery of these plastics to useful products and chemicals provides opportunity for positive economic and environmental impacts. Most previous research use idealised and unrepresentative feedstocks. To address this, various mixed waste plastics collected from the rejected fraction of a municipal waste recovery facility in Ghana were pyrolyzed at varying temperatures of 450, 500 and 550 °C and their yields compared. The obtained chemical products were analysed using several different techniques. Energy and carbon balances of the processes were produced using the CHNS and energy content of the oil fraction and the compositional results of the pyrolysis gas fraction, the latter of which was measured by Gas Chromatography Thermal Conductivity Detection (GC-TCD). The oils were further assessed via Gas Chromatography Mass Spectrometry (GC-MS) to identify the available valuable compounds. The formed oil contained approximately 40% light hydrocarbons (C6 - C11), 18% middle hydrocarbons (C11 - C16) and 42% heavy hydrocarbon compounds (C16+). The optimal oil yield of 65.9 ± 0.5% and low heating value of 44.7 ± 0.1 MJ/kg for single-use plastics were recorded at highest heating temperatures of 550 and 500 °C, respectively. The findings provide indication that pyrolysis is a fitting solution for energy recovery from waste plastics.

Social, economic and environmental benefits of organic waste home composting in Iran.

Organic waste management is challenging in low-middle income countries. Environmental impacts and high management costs affect the sustainable development of cities, an issue that is exacerbated by the lack of social involvement. The research conducted in Iran aims to assess the benefits of organic waste home composting in Shiraz to improve solid waste management (SWM) sustainability. The introduction of a pilot project to assess home composting systems was described, together with an economic, social and environmental analysis. The current SWM system (S0) has been compared with the new strategy proposed (S1), where home composting is considered to be introduced to collect about 10% of the municipal solid waste generated in a 10-year horizon. An economic balance related to the capital costs and operational costs of both systems was introduced, in parallel with a life cycle assessment (LCA) of the SWM system, and a questionnaire survey of the local population. Results showed that S1 leads to around 5% economic savings for the municipality due to the avoidance of organic waste transportation and disposal. Environmental benefits include a lowering of CO2-Eq emissions of about 19,076 tonnes year-1. In addition, about 28% of the interviewed (n = 319) agreed to employ the home composting system at home (CI 5.5%, 95% of confidence level) supporting the theory that about 10% of the organic waste can be segregated and home-composted. The research underlines that home composting can contribute to improve the sustainability of SWM systems in developing countries.

Refuse-derived fuel potential production for co-combustion in the cement industry in Algeria.

As in many developing countries, municipal solid waste (MSW) management is one of the most significant challenges facing urban communities in Algeria. The effective management of solid waste involves the application of various treatment methods, and technologies to ensure the protection of public health and the environment. This research work aimed to examine potential production and utilization of refuse-derived fuel (RDF) from MSW to be used as a substitute fuel in cement kilns in Algeria. After receiving the input waste, sieves were used to categorize MSW according to size. The waste fractions >80 mm were subjected to a drying process in an open-air area and had been turned periodically in order to increase the dry matter (DM). A cost study was performed to evaluate the environmental and economic savings of RDF utilization in the cement industry. At the end of the drying process, as a consequence of the waste moisture reduction, the low heating value was found to be 16 MJ kg-1, and the DM 87%. Concerning heavy metal content, their concentrations were within the limits set by the European Committee for Standardization (CEN)/TC 343 standardization. The chlorine content was around 0.37% to 0.80%. The feasibility study of adding RDF as a substitute fuel in the cement industry showed that when 15% of RDF is used, the RDF consumption will be 4.7 metric tonnes (Mt) h-1, which will save 4347.2 Nm3 h-1 of natural gas and 0.3 Mt h-1 in carbon dioxide emissions, with a net gas cost saving of 65 USD h-1.

Provision of extended producer responsibility system for products packaging: A case study of Iran.

A powerful legal tool in evolving solid waste management (SWM) systems is extended producer responsibility (EPR). It is a mechanism that shifts the responsibility of a product to manufacturers/importers at the 'end-of-life' stage. Yet, implementation of the EPR concept has faced difficulties in developing countries. In Iran, as one such country, the principle of EPR system was issued in executive regulation of SWM in 2005, however, so far, it has been limited to a voluntary scheme. The problem merits further investigation. Therefore, this study aims to shed light on the obstacles in the path of developing EPR system for product packaging. The research examines the current SWM systems in four functional classified frameworks: legal, institutional, financial and technical. The strengths, weaknesses, opportunities and threats of the system are elaborated through semi-structured interviews with a senior executive in the Ministry of Interior (MoI). Then, viable methods to increase resource efficiency and sustainable waste treatment are suggested. The change in the financing mechanism in the Budget Law 2020 forces the manufacturers/importers of products containing recyclable components to pay the revenue from one in 1000 products to MoI for developing recycling facilities and incinerators through partnerships with the private sector. This new strategy would promote proper management of product packaging, create more jobs and a market for international cooperation. However, poor source-separation of wet/dry waste, informal sector activities, exclusive focus on the economic aspect of waste management, lack of expertise and public awareness campaigns are the barriers in this regard.

Adoption of sustainable solid waste management and treatment approaches: A case study of Iran.

Developing countries face serious environmental, social and economic challenges when it comes to managing different kinds of solid waste. Iran, as one such country, is forced to deal with many difficulties including the absence of a comprehensive policy framework, a lack of technical know-how, insufficient financial resources and lack of proper disposal facilities. This study attempts to suggest ways to overcome those problems by providing applicable waste management solutions to the local conditions. The research was performed in four structured phases: diagnosis of the existing solid waste management system practised, identification of areas of weakness in the waste management frameworks, bridging the gaps to ensure the sustainability of the concepts offered, and finally the provision of affordable solutions. A source-separated collection system for wet and dry fractions was drawn up. Establishment of a mechanical biological treatment facility and the introduction of biological treatment technology were considered as the main treatment options. From the economic point of view, the extended producer responsibility concept was provided as a resource management tool. The involvement of the stakeholders, as well as the public-private partnership model, was identified as the cornerstone in the planning and implementing of the new approaches. A roadmap was consequently designed aimed at gradually introducing a waste management system in a sustainable and environmentally sound manner.

Lomustine-temozolomide combination therapy versus standard temozolomide therapy in patients with newly diagnosed glioblastoma with methylated MGMT promoter (CeTeG/NOA-09): a randomised, open-label, phase 3 trial.

BACKGROUND: There is an urgent need for more effective therapies for glioblastoma. Data from a previous unrandomised phase 2 trial suggested that lomustine-temozolomide plus radiotherapy might be superior to temozolomide chemoradiotherapy in newly diagnosed glioblastoma with methylation of the MGMT promoter. In the CeTeG/NOA-09 trial, we aimed to further investigate the effect of lomustine-temozolomide therapy in the setting of a randomised phase 3 trial. METHODS: In this open-label, randomised, phase 3 trial, we enrolled patients from 17 German university hospitals who were aged 18-70 years, with newly diagnosed glioblastoma with methylated MGMT promoter, and a Karnofsky Performance Score of 70% and higher. Patients were randomly assigned (1:1) with a predefined SAS-generated randomisation list to standard temozolomide chemoradiotherapy (75 mg/m2 per day concomitant to radiotherapy [59-60 Gy] followed by six courses of temozolomide 150-200 mg/m2 per day on the first 5 days of the 4-week course) or to up to six courses of lomustine (100 mg/m2 on day 1) plus temozolomide (100-200 mg/m2 per day on days 2-6 of the 6-week course) in addition to radiotherapy (59-60 Gy). Because of the different schedules, patients and physicians were not masked to treatment groups. The primary endpoint was overall survival in the modified intention-to-treat population, comprising all randomly assigned patients who started their allocated chemotherapy. The prespecified test for overall survival differences was a log-rank test stratified for centre and recursive partitioning analysis class. The trial is registered with ClinicalTrials.gov, number NCT01149109. FINDINGS: Between June 17, 2011, and April 8, 2014, 141 patients were randomly assigned to the treatment groups; 129 patients (63 in the temozolomide and 66 in the lomustine-temozolomide group) constituted the modified intention-to-treat population. Median overall survival was improved from 31·4 months (95% CI 27·7-47·1) with temozolomide to 48·1 months (32·6 months-not assessable) with lomustine-temozolomide (hazard ratio [HR] 0·60, 95% CI 0·35-1·03; p=0·0492 for log-rank analysis). A significant overall survival difference between groups was also found in a secondary analysis of the intention-to-treat population (n=141, HR 0·60, 95% CI 0·35-1·03; p=0·0432 for log-rank analysis). Adverse events of grade 3 or higher were observed in 32 (51%) of 63 patients in the temozolomide group and 39 (59%) of 66 patients in the lomustine-temozolomide group. There were no treatment-related deaths. INTERPRETATION: Our results suggest that lomustine-temozolomide chemotherapy might improve survival compared with temozolomide standard therapy in patients with newly diagnosed glioblastoma with methylated MGMT promoter. The findings should be interpreted with caution, owing to the small size of the trial. FUNDING: German Federal Ministry of Education and Research.

Potential utilization of commercial waste in Jakarta as alternative fuel by cement industry.

As the capital city of Indonesia, Jakarta had a population of 10.2 million in 2015 that generated 6200 metric tonnes (Mt) day-1 of municipal waste in the 2017-2019 period. In the composition of the waste, as much as 9% is contributed by the commercial sector. This research focuses on five shopping areas in Jakarta (commercial areas (CAs)). The five CAs produce 110 Mt of waste per day and 79% of them are disposed of in landfills. 95% of the waste is a combustible fraction which can be used as an alternative fuel by the cement industry because the fraction has a low heating value of around 24 MJ kg-1. It is estimated that in one year, the CAs can produce about 34,500 Mt of alternative fuel with 820 TJ of energy. Approximately, the resulting energy savings are 2.6% which is equal to approximately 35,500 Mt of coal. In addition, the utilization of alternative fuel can reduce carbon dioxide emissions by 1.7% or 50,000 Mt.

Recycled Products from Municipal Wastewater: Composition and Effects on Phosphorus Mobility in a Sandy Soil.

Recycled products from wastewater may contain high concentrations of phosphorus (P) and are thus promising alternative fertilizers. However, to better predict their P fertilizer efficiency and potential for P leaching, investigations on P forms and P mobility in soil are essential. In this study, different recycled products-an untreated sewage sludge ash (SSA), an HSO-digested SSA, four thermochemically treated SSAs (two Mg-SSAs and two Ca-SSAs), and struvite-were investigated using a combination of wet chemical methods and P K-edge X-ray absorption near-edge structure (XANES) spectroscopy concerning their composition and their effects on P sorption in a sandy soil in comparison to triple superphosphate. Most of the P in the SSAs was associated with Ca in stable P fractions. The lowest P values in labile fractions (HO-P, NaHCO-P) were found for the untreated SSA and struvite. However, the addition of struvite resulted in an immediate increase in the bioavailable P fractions and the degree of P saturation in soil after only 1 d of incubation. This suggests a high P fertilizer potential for struvite but also a risk of P losses. Among the SSAs, the two Mg-SSAs increased the bioavailable P fractions in soil the most, whereas the lowest values were measured after application of the untreated SSA. Our results demonstrate that chemical analyses of recycled P products may involve the risk of misjudging the fertilizer quality when performed alone, without considering the behavior of these products in soil.

Demand-driven biogas production by flexible feeding in full-scale - Process stability and flexibility potentials.

For future energy supply systems with high proportions from renewable energy sources, biogas plants are a promising option to supply demand-driven electricity to compensate the divergence between energy demand and energy supply by uncontrolled sources like wind and solar. Apart expanding gas storage capacity a demand-oriented feeding with the aim of flexible gas production can be an effective alternative. The presented study demonstrated a high degree of intraday flexibility (up to 50% compared to the average) and a potential for an electricity shutdown of up to 3 days (decreasing gas production by more than 60%) by flexible feeding in full-scale. Furthermore, the long-term process stability was not affected negatively due to the flexible feeding. The flexible feeding resulted in a variable rate of gas production and a dynamic progression of individual acids and the respective pH-value. In consequence, a demand-driven biogas production may enable significant savings in terms of the required gas storage volume (up to 65%) and permit far greater plant flexibility compared to constant gas production.

Vision after trans-sylvian or temporobasal selective amygdalohippocampectomy: a prospective randomised trial.

BACKGROUND: Selective amygdalohippocampectomy (SAH) is an accepted surgical procedure for treatment of pharmacoresistant mesial temporal lobe epilepsy, but it may lead to postoperative visual field deficits (VFDs). Here we present a prospective randomised trial comparing the postoperative VFDs after either a trans-sylvian or temporobasal approach for SAH. METHOD: Forty-eight patients were randomly assigned to trans-sylvian (n = 24) or temporobasal (n = 24) SAH. Postoperative VFD were quantitatively evaluated using automated static and kinetic perimetry. In 24 cases, diffusion tensor imaging-based deterministic fibre-tracking of the optic radiation was performed. The primary endpoint was absence of postoperative VFD. The secondary endpoint was seizure outcome and driving ability. RESULTS: Three patients (13 %) from the trans-sylvian group showed no VFD, compared to 11 patients (46 %) from the temporobasal group without VFD (p = 0.01, RR = 3.7; CI = 1.2-11.5). Fifteen patients from each group (63 %) became completely seizure-free (ILAE1). Among those seizure-free cases, five trans-sylvian (33 %) and ten temporobasal (66 %) patients could apply for a driving licence (NNT = 3) when VFDs were considered. Although the trans-sylvian group experienced more frequent VFDs, the mean functional visual impairment showed a tendency to be less pronounced compared with the temporobasal group. DTI-based tracking of the optic radiation revealed that a lower distance of optic radiation to the temporal base correlated with increased rate of VFD in the temporobasal group. CONCLUSIONS: Temporobasal SAH shows significantly fewer VFDs and equal seizure-free rate compared with the trans-sylvian SAH. However, in patients in whom the optic radiation is close to the temporal base, the trans-sylvian approach may be a preferred alternative.

Biogas Production from Sugarcane Waste: Assessment on Kinetic Challenges for Process Designing.

Biogas production from sugarcane waste has large potential for energy generation, however, to enable the optimization of the anaerobic digestion (AD) process each substrate characteristic should be carefully evaluated. In this study, the kinetic challenges for biogas production from different types of sugarcane waste were assessed. Samples of vinasse, filter cake, bagasse, and straw were analyzed in terms of total and volatile solids, chemical oxygen demand, macronutrients, trace elements, and nutritional value. Biochemical methane potential assays were performed to evaluate the energy potential of the substrates according to different types of sugarcane plants. Methane yields varied considerably (5-181 Nm³·tonFM(-1)), mainly due to the different substrate characteristics and sugar and/or ethanol production processes. Therefore, for the optimization of AD on a large-scale, continuous stirred-tank reactor with long hydraulic retention times (>35 days) should be used for biogas production from bagasse and straw, coupled with pre-treatment process to enhance the degradation of the fibrous carbohydrates. Biomass immobilization systems are recommended in case vinasse is used as substrate, due to its low solid content, while filter cake could complement the biogas production from vinasse during the sugarcane offseason, providing a higher utilization of the biogas system during the entire year.

Comparative Study of Commercial Silica and Sol-Gel-Derived Porous Silica from Cornhusk for Low-Temperature Catalytic Methane Combustion.

The synthesis and characterization of sol-gel-derived cornhusk support for low-temperature catalytic methane combustion (LTCMC) were investigated in this study. The prepared cornhusk support was impregnated with palladium and cerium oxide (Pd/CeO2) via the classical incipient wetness method. The resulting catalyst was characterized using various techniques, including X-ray diffraction (XRD), N2 physisorption (BET), transmission electron microscopy (TEM), and hydrogen temperature-programmed reduction (H2-TPR). The catalytic performance of the Pd/CeO2/CHSiO2 catalyst was evaluated for methane combustion in the temperature range of 150-600 °C using a temperature-controlled catalytic flow reactor, and its performance was compared with a commercial catalyst. The results showed that the Pd/CeO2 dispersed on SiO2 from the cornhusk ash support (Pd/CeO2/CHSiO2) catalyst exhibited excellent catalytic activity for methane combustion, with a conversion of 50% at 394 °C compared with 593 °C for the commercial silica catalyst (Pd/CeO2/commercial). Moreover, the Pd/CeO2/CHSiO2 catalyst displayed better catalytic stability after 10 h on stream, with a 7% marginal loss in catalytic activity compared with 11% recorded for the Pd/CeO2/commercial catalyst. The N2 physisorption and H2-TPR results indicated that the cornhusk SiO2 support possessed a higher surface area and strong reducibility than the synthesized commercial catalyst, contributing to the enhanced catalytic activity of the Pd/CeO2/SiO2 catalyst. Overall, the SiO2 generated from cornhusk ash exhibited promising potential as a low-cost and environmentally friendly support for LTCMC catalysts.

Neuropsychological outcome after selective amygdalohippocampectomy: subtemporal versus transsylvian approach.

OBJECTIVE: In the context of discussions on the optimal cognitive outcome of temporal lobe epilepsy surgery, and stimulated by recent reports on the beneficial effects of a selective subtemporal approach to memory function, this study evaluated the cognitive consequences of subtemporal versus transsylvian selective amygdalohippocampectomy (SAH) in patients with mesial temporal lobe epilepsy, taking verbal/figural memory and language functions into account. METHODS: We contrasted cognitive outcomes of 26 subtemporal SAH patients with those observed in a transsylvian SAH control group. The surgical groups were pairwise matched with regard to clinical and demographic characteristics. Preoperative and 1 year postoperative memory and language evaluations served as within group factors, and surgical approach (transsylvian vs subtemporal) and side of surgery (right vs left) as between group factors. RESULTS: Both surgical approaches caused decline in verbal memory to a similar degree. Differential effects were seen with regard to decline in verbal recognition memory (more affected by left transsylvian SAH) as well as in figural memory and verbal fluency (more affected by subtemporal SAH). INTERPRETATION: Different from previous optimistic reports, this study demonstrates that subtemporal surgery, such as transsylvian surgery, poses similar risks for verbal memory. Differences between the approaches appear to reflect the effect of different collateral temporal lobe lesions due to the approach. Different cognitive outcomes across studies on the subtemporal approach are discussed as being in part due to study design and the chosen dependent functional measures.

A review of energy recovery from waste in China.

Although municipal solid waste (MSW) disposal in Europe and other developed countries has led to a widespread production of solid recovered fuel (SRF) and its incineration in various technical combustion processes, such developments have not yet occurred that widely in developing and transitional economies. This article puts mass-burn technologies and SRF into a China perspective, reviewing issues from technology application problems to emerging trends and future perspectives. Over the last two decades, growing waste volumes have prompted a move to waste incineration, especially in the large densely populated first-tier cities. However, with an organic fraction above 70% and a resulting water content of up to 65%, it is still argued that MSW in China is too moist for incineration. The introduction of mechanical biological treatment (MBT) or mechanical physical stabilization (MPS) technology for SRF production could provide the solution, either by offering further pre-drying options to mass-burn incinerators or by creating SRF to be burnt in co-incineration plants. First experiences of MBT and MPS technologies show promising results in terms of the capacity to deal with organic waste fractions, but the further disposal/utilization of the plants' output stream has not yet been fully addressed.

Greenhouse gas emissions of different waste treatment options for sector-specific commercial and industrial waste in Germany.

This article investigates greenhouse gas (GHG) emissions from commercial and industrial (C&I) waste treatment considering five sector-specific waste compositions and four different treatment scenarios in Germany. Results show that the highest share of CO2-equivalent emissions can be avoided in each of the analysed industrial sectors if solid recovered fuel (SRF) is produced for co-incineration in cement kilns. Across all industries, emissions of approximately 680 kg CO2-eq. Mg⁻¹ C&I waste can be avoided on average under this scenario. The combustion of C&I waste in waste incineration plants without any previous mechanical treatment generates the lowest potential to avoid GHG emissions with a value of approximately 50 kg CO2-eq. Mg⁻¹ C&I waste on average in all industries. If recyclables are sorted, this can save emissions of approximately 280 kg CO2-eq. Mg⁻¹ C&I waste while the treatment in SRF power plants amounts to savings of approximately 210 kg CO2-eq. Mg⁻¹ C&I waste. A comparison of the treatment scenarios of the waste from these five sectors shows that waste treatment of the craft sector leads to the lowest CO2-equivalent reduction rates of all scenarios. In contrast, the treatment of waste from catering sector leads to the highest CO2-equivalent reduction rates except for direct incineration in waste incineration plants. The sensitivity analysis of the different scenarios for this paper shows that the efficiency and the substitution factor of energy have a relevant influence on the result. Changes in the substitution factor of 10% can result in changes in emissions of approximately 55 to 75 kg CO2-eq. Mg⁻¹ in waste incineration plants and approximately 90 kg CO2-eq. Mg⁻¹ in the case of cement kilns.

Water Desalination Using the Once-through Multi-Stage Flash Concept: Design and Modeling.

Thermal water desalination is one of the most important techniques to solve the water scarcity problem in many regions of the world. Out of around 7.8 billion people in the world, only about 6 billion of them have access to clean water; notably, climate change plays a major role in accelerating the evaporation rate of water from water bodies, which in turn increases the scarcity. Multi-stage flash, recognized to have a high rate of water production in comparison with other available technologies, accounts for 35% of water desalination facilities worldwide. This paper presents a detailed Excel model to evaluate the amount of energy required to drive 16 stages of multi-stage flash. This model aims to design and evaluate the amount of thermal energy required for such projects and optimize their performance by calibrating the governing parameters. Furthermore, the 16 stages were simulated via the Ebsilon 13.02 software package to match the results and evaluate the fulfillment of the plant requirements. The temperature drop of the brine stream was 2.34 °C/stage. The top brine temperature was 130 °C. The results show that 29.5 kg/s of superheated steam is required to desalinate 162 kg/s of 2500 kg/s influent mass flow of brine. The effect of water intake temperature was also examined by using Ebsilon. The performance ratio decreased from 5.49 to 2.66 when the water intake temperature decreased from 30 °C to 5 °C.

Material characterization and conditioning of cattle feedlot manure as feedstock for dry batch anaerobic digestion.

The focus of the study was to determine the suitability of cattle feedlot manure originating from clay-pack feedlots as a possible feedstock material for dry batch anaerobic digestion. Oedometer tests were carried out that measure the permeability and compressibility of the feedstock under practical conditions experienced in large-scale dry batch anaerobic digestion plants. Material characterization tests showed that feedlot manure was impermeable under compression and therefore unsuitable for percolation. Mixtures of feedlot manure, wood chips (3 %ww) and wheat straw (6 %ww) showed superior permeability under compression compared to feedlot manure alone with an 56% increased permeability. Further practical tests showed that dry digestion of feedlot manure mixtures led to methane yields of 99 mL/g VS which equals 86% of the material biochemical methane potential (BMP). High percolation rate and low inoculum recycle led to the highest specific methane yield (SMY) and digester productivity with implications on process design to reduce capital investment costs.

Neurologic and ocular phenotype in Pitt-Hopkins syndrome and a zebrafish model.

In this study, we performed an in-depth analysis of the neurologic and ophthalmologic phenotype in a patient with Pitt-Hopkins syndrome (PTHS), a disorder characterized by severe mental and motor retardation, carrying a uniallelic TCF4 deletion, and studied a zebrafish model. The PTHS-patient was characterized by high-resolution magnetic resonance imaging (MRI) with diffusion tensor imaging to analyze the brain structurally, spectral-domain optical coherence tomography to visualize the retinal layers, and electroretinography to evaluate retinal function. A zebrafish model was generated by knockdown of tcf4-function by injection of morpholino antisense oligos into zebrafish embryos and the morphant phenotype was characterized for expression of neural differentiation genes neurog1, ascl1b, pax6a, zic1, atoh1a, atoh2b. Data from PTHS-patient and zebrafish morphants were compared. While a cerebral MRI-scan showed markedly delayed myelination and ventriculomegaly in the 1-year-old PTHS-patient, no structural cerebral anomalies including no white matter tract alterations were detected at 9 years of age. Structural ocular examinations showed highly myopic eyes and an increase in ocular length, while retinal layers were normal. Knockdown of tcf4-function in zebrafish embryos resulted in a developmental delay or defects in terminal differentiation of brain and eyes, small eyes with a relative increase in ocular length and an enlargement of the hindbrain ventricle. In summary, tcf4-knockdown in zebrafish embryos does not seem to affect early neural patterning and regionalization of the forebrain, but may be involved in later aspects of neurogenesis and differentiation. We provide evidence for a role of TCF4/E2-2 in ocular growth control in PTHS-patients and the zebrafish model.

Focal liver lesions at 3.0 T: lesion detectability and image quality with T2-weighted imaging by using conventional and dual-source parallel radiofrequency transmission.

PURPOSE: To prospectively compare T2-weighted single-shot turbo spin-echo (TSE) sequences performed with parallel and conventional radiofrequency (RF) transmission at 3.0 T for liver lesion detection, image quality, lesion conspicuity, and lesion contrast. MATERIALS AND METHODS: After written informed consent and institutional review board approval, 52 consecutive patients (32 men, 20 women; mean age, 56.6 years ± 13.7 [standard deviation]) underwent routine magnetic resonance (MR) imaging with a clinical 3.0-T unit. Two independent readers reviewed images acquired with conventional and dual-source parallel RF transmission for detection of focal liver lesions, with separate reading of a third radiologist, including all available imaging findings, clinical history, and histopathologic findings, as reference. Image quality and lesion conspicuity were rated on five- and three-point evaluation scales, respectively. Contrast ratios between focal liver lesions and adjacent liver parenchyma were calculated. Significance was determined by using nonparametric Wilcoxon signed-rank and marginal homogeneity tests. RESULTS: With the reference standard, 106 index lesions were identified in 22 patients. Detection rate significantly improved from 87% (92 of 106) to 97% (103 of 106) (reader 1) and from 85% (90 of 106) to 96% (102 of 106) (reader 2) with parallel RF transmission (reader 1, P = .0078; reader 2, P = .002). Quality of parallel RF transmission images was assigned scores significantly higher, compared with quality of conventional RF transmission images (mean for reader 1, 2.88 ± 0.73 vs 4.04 ± 0.44; mean for reader 2, 2.81 ± 0.72 vs 4.04 ± 0.39; P < .0001 for both). Lesion conspicuity scores were significantly higher on parallel RF transmission images, compared with conventional RF transmission images (mean for reader 1, 2.02 ± 0.64 vs 2.92 ± 0.27; mean for reader 2, 2.06 ± 0.67 vs 2.90 ± 0.30; P < .0001 for both). Contrast ratios were significantly higher with parallel RF transmission (P < .05). CONCLUSION: Compared with conventional RF transmission, parallel RF transmission significantly improved liver lesion detection rate, image quality, lesion conspicuity, and lesion contrast. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101429/-/DC1.