Acidification-based direct electrolysis of treated wastewater for hydrogen production and water reuse.

This report describes the direct electrolysis of treated wastewater (as a catholyte) to produce hydrogen and potentially reuse the water. To suppress the negative shift of the cathodic potential due to an increase in pH by the hydrogen evolution reaction (HER), the treated wastewater is acidified using the synergetic effect of protons generated from the bipolar membrane and inorganic precipitation occurred at the surface of the cathode during the HER. Natural seawater, as an accessible source for Mg2+ ions, was added to the treated wastewater because the concentration of Mg2+ ions contained in the original wastewater was too low for acidification to occur. The mixture of treated wastewater with seawater was acidified to pH 3, allowing the initial cathode potential to be maintained for more than 100 h. The amount of inorganic precipitates formed on the cathode surface is greater than that in the control case (adding 0.5 M NaCl instead of seawater) but does not adversely affect the cathodic potential and Faradaic efficiency for H2 production. Additionally, it was confirmed that less organic matter was adsorbed to the inorganic deposits under acidic conditions. These indicate that acidification plays an important role in improving the performance and stability of low-grade water electrolysis. Considering that the treated wastewater is discharged near the ocean, acidification-based electrolysis of the effluent with seawater can be a water reuse technology for green hydrogen production, enhancing water resilience and contributing to the circular economy of water resources.

Recycling of nutrient medium to improve productivity in large-scale microalgal culture using a hybrid electrochemical water treatment system.

Recycling and reusing of nutrient media in microalgal cultivation are important strategies to reduce water consumption and nutrient costs. However, these approaches have limitations, e.g., a decrease in biomass production, (because as reused media can inhibit biomass growth). To address these limitations, we applied a novel membrane filtration‒electrolysis‒ultraviolet hybrid water treatment method capable of laboratory-to-large-scale operation to increase biomass productivity and enable nutrient medium disinfection and recycling. In laboratory-scale experiments, electrolysis effectively remove the biological contaminants from the spent nutrient medium, resulting in a high on-site removal efficiency of dissolved organic carbon (DOC; 80.3 ± 5 %) and disinfection (99.5 ± 0.2 %). Compared to the results for the recycling of nutrient medium without water treatment, electrolysis resulted in a 1.5-fold increase in biomass production, which was attributable to the removal of biological inhibitors from electrochemically produced oxidants (mainly OCl-). In scaled-up applications, the hybrid system improved the quality of the recycled nutrient medium, with 85 ± 2 % turbidity removal, 75 ± 3 % DOC removal, and 99.5 ± 2 % disinfection efficiency, which was beneficial for biomass growth by removing biological inhibitors. After applying the hybrid water treatment method, we achieved a Spirulina biomass production of 0.47 ± 0.03 g L-1, similar to that obtained using a fresh medium (0.53 ± 0.02 g L-1). The on-site disinfection process described herein is practical and offers a cost-saving and environmental friendly alternative for nutrient medium recycling and reusing water in mass and sustainable cultivation of microalgae.

Sustainable energy harvesting and on-site disinfection of natural seawater using reverse electrodialysis.

Seawater is a cost-effective and abundant electrolyte used as an electrode rinse solution to enable optimum utilization of reverse electrodialysis (RED). However, it is associated with several limitations, including the use of precious electrode materials, and its long-term stability must be addressed prior to its application in the field of seawater technology. In this context, a novel RED based on carbon electrodes was designed, and the experimental conditions were optimized for maximizing the harvesting of energy with aquaculture wastewater disinfection and recycling. The power obtained by RED, with a current density of 30 A/m2 and a flow rate of 424 mL/min, designed by response surface methodology, was in good agreement with the predicted maximum power density (0.64 W/m2). The treatment was sustainable, mainly due to an anodic reaction of electro-generated sodium hypochlorite (NaOCl) under natural conditions, which afforded a high disinfection efficiency (above 99.5 ± 0.2% within 1 min under continuous flow (pH 8)), even under real seawater conditions and in aquaculture wastewater. Simultaneously, a stable power of 0.1 ± 0.03 W (0.25 ± 0.07 W/m2) generated a reasonable specific energy (within 0.02 kWh/m3). Inorganic fouling was efficiently suppressed using a surface-modified carbon cathode for 680 h. Thus, the on-site seawater disinfection by RED described herein is practically feasible and could offer a sustainable and energy-efficient alternative to seawater recycling.

Efficient removal of anionic, cationic textile dyes and salt mixture using a novel CS/MIL-100 (Fe) based nanofiltration membrane.

The purification of hazardous textile dyeing wastewater has exhibited many challenges because it consists of a complex mixture, including dyestuff, additives, and salts. It is necessary to fabricate membranes with enhanced permeability, fouling resistance, stability, and superior dyes and salts removal from wastewater. Incorporating a highly water stable metal-organic framework (MOFs) into membranes would meet the requirements for the efficient purification of textile wastewater. In this study, nanofiltration (NF) membranes are fabricated by incorporating MIL-100 (Fe) into the chitosan (CS) through film casting technique. The effect of MIL-100 (Fe) loadings on chitosan characterized by FT-IR, XRD, contact angle measurement, FESEM-EDS, XPS, zeta potential, and surface roughness analysis. The membrane characterization confirmed the enhanced surface roughness, pore size, surface charge, and hydrophilicity. The CS/MIL-100 (Fe) membrane exhibited an improved pure water flux from 5 to 52 L/m2h as well as 99% rejection efficiency for cationic methylene blue (MB) and anionic methyl orange (MO). We obtained the rejection efficiency trend for the MB mixed salts in the order of MgSO4 (Mg2+ - 51.6%, SO42- - 52.5%) > Na2SO4 (Na+ - 26.3%, SO42- - 29.3%) > CaCl2 (Ca2+ - 21.4%, Cl- - 23.8%) > NaCl (Na+ - 16.8%, Cl- - 19.2%). In addition, the CS/MIL-100 (Fe) composite membrane showed excellent rejection efficiency and antifouling performances with high recycling stability. These stunning results evidenced that the CS/MIL-100 (Fe) nanofiltration membrane is a promising candidate for removing toxic pollutants in the textile dyeing wastewater.

Enhanced energy recovery using a cascaded reverse electrodialysis stack for salinity gradient power generation.

Despite significant advances in the field applications of reserve electrodialysis (RED) to produce salinity gradient power, net energy production remains an issue owing to limitations such as high energy requirement for high flow rates of feed solutions, and severe fouling and pressure build up when thin spacers are used. Therefore, to maximize the performance and efficiency of energy harvesting in the RED, a cascaded RED stack, with multiple stages between the anode and cathode electrodes, was investigated. In cascaded stacks, 100-cell paired stacks were divided into several stages, so the feed water flowed into the first stage, and the effluent from the first stage was then reused in the next stages. This cascaded stack could overcome the typical drawbacks of RED (large amount of feed water required, intensive pumping energy, and low net energy production). Although 25% of the feed water volume was used in the 4-stage cascaded stack (100-cell-pairs) compared to the conventional stack (100-cell-pairs with a parallel flow operation), much more energy was produced with the 4-stage cascaded stack. The net power density and net specific energy with the 4-stage cascaded stack were the highest at 0.5 cm/s (0.48 W/m2) and 0.25 cm/s (0.06 kWh/m3), respectively. This is very promising for the practical application of RED since feed water volumes can be greatly reduced, which could reduce the burden on the feed water pretreatment step. Consequently, we can build a compact RED plant with smaller pretreatment processes and fewer RED unit stacks.

Reverse electrodialysis (RED) using a bipolar membrane to suppress inorganic fouling around the cathode.

When operating reverse electrodialysis (RED) with several hundreds of cell pairs, a large stack voltage of more than 10 V facilitates water electrolysis, even when redox couples are employed for the electrode reaction. Upon feeding natural water containing multivalent ions, ion crossover through a shielding membrane causes inorganic scaling around the cathode and the interior of the membrane stack, due to the combination with the hydroxide ions produced via water reduction. In this work, we introduce a bipolar membrane (BPM) as a shielding membrane at the cathode to suppress inorganic precipitation. Water splitting in the bilayer structure of the BPM can block the ions diffusing from the catholyte and the feed solution, maintaining the current density. To evaluate the effect of the BPM on the inorganic precipitates, diluted sea salt solution is allowed to flow through the outermost feed channel near the cathode, in order to maintain as large a stack voltage as possible, which is important to induce water splitting in the BPM when incorporated into an RED stack of 100 cell pairs. We measure the electric power of the RED according to the arrangement of the BPM and compare it with that of conventional RED. The degree of inorganic scaling is also compared according to the kind of shielding membrane used (anion exchange membrane, cation exchange membrane, and BPM (Neosepta or Fumasep)). The BPM (Neosepta) shows the best performance for suppressing the formation of precipitates. It can hence be used to design a highly stable electrode system for long-term operation of a large-scale RED feeding natural water.

Nernst-Planck analysis of reverse-electrodialysis with the thin-composite pore-filling membranes and its upscaling potential.

To properly design reverse electrodialysis (RED) stacks, modeling of ion transport and prediction of power generation on the single RED stack are very important. Currently, the Nernst-Planck equation is widely adopted to simulate ion transport through IEMs. However, applying typical Nernst-Planck equation is not proper to analyze ion transport through the heterogeneous thin-composite pore-filling membrane because of the non-conductive site in the membrane matrix. Herein, we firstly introduced modified Nernst-Planck equation by addressing conductive traveling length (CTL) to simulate the ion transport through the thin-composite pore-filling membranes and the performance of a single RED stack with the same membranes. Also, 100 cell-pairs of RED stacks were assembled to validate modified Nernst-Planck equation according to the flow rate and membrane types. Under the OCV condition, the conductivity of the effluents was measured to validate the modified Nernst-Planck equation, and differences between modeling and experiments were less than 1.5 mS/cm. Theoretical OCV and current density were estimated by using modified Nernst-Planck equation. In particular, hydrophobicity on the surface of the heterogeneous membrane was considered to describe ion transport through the pore-filling membranes. Moreover, power generation from RED stacks was calculated according to the flow rate and the number of cell pairs.

Assessing the behavior of the feed-water constituents of a pilot-scale 1000-cell-pair reverse electrodialysis with seawater and municipal wastewater effluent.

Reverse electrodialysis (RED) has vast potential as a clean, nonpolluting, and sustainable renewable energy source; however, pilot-scale RED studies employing real waters remain rare. This study reports the largest RED (1000 cell pairs, 250 m2) with municipal wastewater effluent (1.3-5.7 mS/cm) and seawater (52.9-53.8 mS/cm) as feed solutions. The RED stack was operated at a velocity of 1.5 cm/s and the pilot plant produced 95.8 W of power (0.38 W/m2total membrane or 0.76 W/m2cell pair). During operation of the RED, the inlet design of the stack, comprising thin spacers, and the water dissociation reaction at the cathode were revealed as vulnerabilities of the stack. Specifically, pressure drops at the fluid inlet parts had the most detrimental effects on power output due to clogged spacers around the inlet parts. In addition, precipitates resulting in inorganic fouling were inevitable during the water dissociation reaction due to significant potential generated by the stack in the cathode chamber. Na+ and Cl- accounted for the majority of ions transferred from seawater to wastewater effluent through ion exchange membranes (IEMs). Moreover, some divalent cations in seawater, Mg2+ and Ca2+, were also transferred to the wastewater effluent. Some organics with relatively low molecular weights in the wastewater effluent passed through the IEMs, and their hydrophobic properties elevated the specific UV absorbance (SUVA) level in the seawater.

Analysis of unexplained carcinoembryonic antigen elevation after curative treatment of locally advanced rectal cancer.

BACKGROUND: To analyze the causes and patterns of unexplained carcinoembryonic antigen (CEA) elevation after curative treatment in locally advanced rectal cancer patients. METHODS: Among the 1309 locally advanced rectal cancer patients treated with curative resection and radiotherapy between January 2001 and June 2011, 325 patients who postoperatively developed abnormal CEA elevation were reviewed. The unexplained CEA elevation was defined as a CEA level higher than 5 ng/mL with no evidence of cancer recurrence at the time of elevation. RESULTS: Of the 325 patients, 143 (44%) had unexplained CEA elevations. The causes were categorized as delayed recurrence (n = 29, 20%), non-colorectal malignancy (n = 10, 7%), and non-malignancy-related conditions (n = 104, 73%). Shorter intervals between treatment and the first CEA elevation, and a higher peak CEA level, were observed in the delayed recurrence group compared with the non-colorectal malignancy or non-malignancy-related group (intervals of 6.8 vs. 44.9 vs. 23.2 months, respectively, p = 0.002; and peak CEA levels of 9.9 vs. 7.1 vs. 6.2 ng/mL, respectively, p = 0.034). In patients who showed delayed recurrence, the interval between the first CEA elevation and diagnosis of recurrence was a median of 13.0 months (range 3.8-60.6 months). Smoking was the most common cause for non-malignancy-related conditions. The patterns of unexplained CEA elevations were defined as sporadic (n = 78, 55%), stationary (n = 37, 26%), and increasing (n = 28, 20%). The patterns were significantly different depending on the cause (p < 0.001). CONCLUSIONS: Analysis of the patterns of unexplained CEA elevations is a reasonable approach to predict the cause of the cancer.

Clinical significance of radiation-induced liver disease after stereotactic body radiation therapy for hepatocellular carcinoma.

BACKGROUND/AIMS: The aim of this study was to investigate parameters that predict radiation-induced liver disease (RILD) following stereotactic body radiotherapy (SBRT) in patients with hepatocellular carcinoma (HCC) and to identify the clinical significance of RILD. METHODS: We retrospectively reviewed the medical records of 117 HCC patients who were treated by SBRT from March 2011 to February 2015. RILD was defined as elevated liver transaminases more than five times the upper normal limit or a worsening of Child-Pugh (CP) score by 2 within 3 months after SBRT. All patients were assessed at 1 month and every 3 months after SBRT. RESULTS: Median follow-up was 22.5 months (range, 3 to 56) after SBRT. RILD was developed in 29 of the 117 patients (24.7%). On univariate analysis, significant predictive factors of RILD were pretreatment CP score (p < 0.001) and normal liver volume (p = 0.002). Multivariate analysis showed that CP score was a significant predictor of RILD (p < 0.001). The incidence of RILD increased above a CP score of 6 remarkably. The rate of recovery from RILD decreased significantly above a CP score of 8. Survival analysis showed that CP score was an independent prognostic factor of overall survival (p = 0.001). CONCLUSION: CP score is a significant factor to predict RILD in patients with chronic liver disease. RILD can be tolerated by patients with a CP score ≤ 7. However, careful monitoring of liver function is needed for patients with a CP score 7 after SBRT.

Ibulocydine sensitizes human hepatocellular carcinoma cells to TRAIL-induced apoptosis via calpain-mediated Bax cleavage.

Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) induces apoptosis selectively in cancer cells without affecting the majority of normal human cells. However, hepatocellular carcinoma (HCC) cells often display resistance to TRAIL-induced apoptosis. Ibulocydine (IB) is an isobutyrate ester pro-drug of a novel synthetic Cdk inhibitor that targets Cdk7 and Cdk9. In this study, we show that treatment with subtoxic doses of IB in combination with TRAIL displays potent cytotoxicity in TRAIL-resistant human HCC cells. Combination of IB and TRAIL was found to synergistically induce apoptosis through activation of caspases, which was blocked by a pan-caspase inhibitor (zVAD). Although the expression of Mcl-1 and survivin were reduced by IB plus TRAIL, overexpression of Mcl-1 and survivin did not block the cell death induced by co-treatment. Moreover, overexpression of Bcl-xL did not significantly interfere with the cell death induced by co-treatment of IB and TRAIL. Interestingly, the combination treatment induced cleavage of Bax, which was translocated to mitochondria upon induction of apoptosis. Furthermore, down-regulation of Bax by small interfering RNA effectively reduced the cell death and loss of mitochondrial membrane potential (MMP) caused by co-treatment with IB and TRAIL. Finally, pre-treatment of HCC cells with a calpain inhibitor effectively blocked IB plus TRAIL-induced cleavage of Bax and apoptosis. Collectively, our results demonstrate that IB increases the sensitivity of human HCC cells to TRAIL via mitochondria signaling pathway mediated by calpain-induced cleavage of Bax, suggesting that combined treatment with IB and TRAIL may offer an effective therapeutic strategy for human HCC.

Locoregional Recurrence by Tumor Biology in Breast Cancer Patients after Preoperative Chemotherapy and Breast Conservation Treatment.

PURPOSE: The purpose of this study is to determine whether breast cancer subtype can affect locoregional recurrence (LRR) and ipsilateral breast tumor recurrence (IBTR) after neoadjuvant chemotherapy (NAC) and breast-conserving therapy (BCT). MATERIALS AND METHODS: We evaluated 335 consecutive patients with clinical stage II-III breast cancer who received NAC plus BCT from 2002 to 2009. Patients were classified according to six molecular subtypes: luminal A (hormone receptor [HR]+/HER2-/Ki-67 < 15%, n=113), luminal B1 (HR+/HER2-/Ki-67 ≥ 15%, n=33), luminal B2 (HR+/HER2+, n=83), HER2 with trastuzumab (HER2[T+]) (HR-/HER2+/use of trastuzumab, n=14), HER2 without trastuzumab (HER2[T-]) (HR-/HER2+, n=31), and triple negative (TN) (HR-/HER2-, n=61). RESULTS: After a median follow-up period of 7.2 years, 26 IBTRs and 37 LRRs occurred. The 5-year LRR-free survival rates were luminal A, 96.4%; B1, 93.9%; B2, 90.3%; HER2(T+), 92.9%; HER2(T-), 78.3%; and TN, 79.6%. The 5-year IBTR-free survival rates were luminal A, 97.2%; B1, 93.9%; B2, 92.8%; HER2(T+), 92.9%; HER2(T-), 89.1%; and TN, 84.6%. In multivariate analysis, HER2(T-) (IBTR: hazard ratio, 4.2; p=0.04 and LRR: hazard ratio, 7.6; p < 0.01) and TN subtypes (IBTR: hazard ratio, 6.9; p=0.01 and LRR: hazard ratio, 8.1; p < 0.01) were associated with higher IBTR and LRR rates. A pathologic complete response (pCR) was found to show correlation with better LRR and a tendency toward improved IBTR controls in TN patients (IBTR, p=0.07; LRR, p=0.03). CONCLUSION: The TN and HER2(T-) subtypes predict higher rates of IBTR and LRR after NAC and BCT. A pCR is predictive of improved IBTR or LRR in TN subtype.

Identification of Risk Factors for Locoregional Recurrence in Breast Cancer Patients with Nodal Stage N0 and N1: Who Could Benefit from Post-Mastectomy Radiotherapy?

INTRODUCTION: The locoregional recurrence (LRR) rate was reported as high as approximately 20% in stage I-II breast cancer following mastectomy. To investigate the risk factors for LRR in pT1-2N0-1 breast cancer patients treated with mastectomy but not radiation, and to define a subgroup of patients at high risk of LRR who may benefit from postmastectomy radiotherapy (PMRT). METHODS AND MATERIALS: In total, 390 patients with pT1-2N0M0 (n = 307) and pT1-2N1M0 (n = 83) breast cancer who underwent total mastectomy without adjuvant radiotherapy from 2002 to 2011 were enrolled in the study. RESULTS: After a median follow-up period of 5.6 years (range, 0.6-11.3 years), 21 patients had 18 systemic relapses and 12 LRRs including six in the chest wall and eight in the regional nodal area. The 5-year LRR-free survival (LRRFS) rates were 97.0% in pN0, 98.8% in pN1, and 97.4% in all patients. Multivariate analysis revealed that age < 50 years (Hazard Ratio, 11.4; p = 0.01) and no adjuvant chemotherapy (Hazard Ratio, 10.2; p = 0.04) were independent risk factors for LRR in pN0 patients. Using these factors, the 5-year LRRFS rates were 100% without any risk factors, 96.4% with one risk factor, and 86.7% with two risk factors. In pN1 patients, multivariate analysis revealed that having a hormone receptor negative tumor (Hazard Ratio, 18.3; p = 0.03) was the only independent risk factor for LRR. The 5-year LRRFS rates were 100.0% for luminal type, and 92.3% for non-luminal type cancer. CONCLUSION: Patients with pT1-2N0-1 breast cancer who underwent total mastectomy without PMRT could be stratified by nodal stage and risk factors for LRR. PMRT may have of value for node negative patients aged less than 50 years and who are not treated with adjuvant chemotherapy, and for non-luminal type patients with one to three positive nodes.

Adjuvant radiotherapy for stage III/IV urothelial carcinoma of the upper tract.

AIM: In order to define the role of adjuvant radiotherapy (RT), the clinical outcomes of patients with stage III/IV urothelial carcinoma of the upper urinary tract (UTUC) were reviewed. PATIENTS AND METHODS: Clinical data from a total of 127 patients who underwent radical nephroureterectomy with bladder cuff were analyzed. While 36 patients underwent adjuvant RT following surgery, 91 were treated with surgery-alone. Differences in risk-adjusted treatment outcomes between the two groups were assessed using a multivariable Cox proportional-hazards model and inverse probability of treatment weighting with propensity score for balancing covariates including use of chemotherapy between the two groups was estimated. RESULTS: With a median follow-up of 38.3 months, 3-year actuarial locoregional recurrence-free survival rates were 89% vs. 61% in the RT vs. non-RT groups, respectively (p=0.01). Three-year bladder recurrence-free survival rates were 73% and 52% in favor of the RT group (p=0.02). After adjustment for differences in covariates, the risks of locoregional, bladder, and disease recurrence were found significantly lower in the RT group. CONCLUSION: Adjuvant RT may be beneficial in terms of locoregional and bladder control in patients with stage III/IV UTUC. Further prospective studied are needed to verify these findings.

Hypofractionated intensity-modulated radiotherapy using simultaneous integrated boost technique with concurrent and adjuvant temozolomide for glioblastoma.

AIMS AND BACKGROUND: We assessed the therapeutic efficacy of combined hypofractionated intensity-modulated radiotherapy with temozolomide in patients with primary glioblastoma. METHODS AND STUDY DESIGN: Thirty-nine patients with histologically confirmed glioblastoma were accrued. Using the simultaneous integrated boost technique, a dose of 50 Gy in 5-Gy fractions was applied to the gross tumor volume, together with 40 Gy in 4-Gy fractions and 30 Gy in 3-Gy fractions to the 1- and 2-cm margins from the gross tumor volume, respectively. Patients were also treated with concurrent temozolomide during intensity-modulated radiotherapy, followed by six cycles of adjuvant temozolomide. RESULTS: Median follow-up was 16.8 months (range, 4.3-54.3). Tumor progression was observed in 28 patients (71.8%), and the median time to progression was 6.8 months. Median survival was 16.8 months, and it was affected significantly by the extent of surgery. During adjuvant temozolomide treatment, 3 patients (9.7%) developed grade 3-4 hematologic or hepatic toxicity. Radiation necrosis developed in 7 patients (17.9%) and massive necrosis, requiring emergency surgery, in 1 patient (2.6%). CONCLUSIONS: The regimen of hypofractionated intensity-modulated radiotherapy with temozolomide showed a relatively good outcome in patients with glioblastoma. Further studies are required to define the optimal fraction size for glioblastoma using this highly sophisticated radiation technique.

Prognostic value of (18)F-fluorodeoxyglucose positron emission tomography, computed tomography and magnetic resonance imaging in oral cavity squamous cell carcinoma with pathologically positive neck lymph node.

PURPOSE: To evaluate the prognostic value of preoperative neck lymph node (LN) assessment with (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET), computed tomography (CT), and magnetic resonance imaging (MRI) in oral cavity squamous cell carcinoma (OSCC) patients with pathologically positive LN. MATERIALS AND METHODS: In total, 47 OSCC patients with pathologically positive LN were retrospectively reviewed with preoperative (18)F-FDG PET and CT/MRI. All patients underwent surgical resection, neck dissection and postoperative adjuvant radiotherapy and/or chemotherapy between March 2002 and October 2010. Histologic correlation was performed for findings of (18)F-FDG PET and CT/MRI. RESULTS: Thirty-six (76.6%) of 47 cases were correctly diagnosed with neck LN metastasis by (18)F-FDG PET and 32 (68.1%) of 47 cases were correctly diagnosed by CT/MRI. Follow-up ranged from 20 to 114 months (median, 56 months). Clinically negative nodal status evaluated by (18)F-FDG PET or CT/MRI revealed a trend toward better clinical outcomes in terms of overall survival, disease-free survival, local recurrence-free survival, regional nodal recurrence-free survival, and distant metastasis-free survival rates even though the trends were not statistically significant. However, there was no impact of neck node standardized uptake value (SUV(max)) on clinical outcomes. Notably, SUV(max) showed significant correlation with tumor size in LN (p < 0.01, R(2) = 0.62). PET and CT/MRI status of LN also had significant correlation with the size of intranodal tumor deposit (p < 0.05, R(2) = 0.37 and p < 0.01, R(2) = 0.48, respectively). CONCLUSION: (18)F-FDG PET and CT/MRI at the neck LNs might improve risk stratification in OSCC patients with pathologically positive neck LN in this study, even without significant prognostic value of SUV(max).