Phase-resolved measurement and control of ultrafast dynamics in terahertz electronic oscillators.

As a key component for next-generation wireless communications (6 G and beyond), terahertz (THz) electronic oscillators are being actively developed. Precise and dynamic phase control of ultrafast THz waveforms is essential for high-speed beam steering and high-capacity data transmission. However, measurement and control of such ultrafast dynamic process is beyond the scope of electronics due to the limited bandwidth of the electronic equipment. Here we surpass this limit by applying photonic technology. Using a femtosecond laser, we generate offset-free THz pulses to phase-lock the electronic oscillators based on resonant tunneling diode. This enables us to perform phase-resolved measurement of the emitted THz electric field waveform in time-domain with sub-cycle time resolution. Ultrafast dynamic response such as anti-phase locking behaviour is observed, which is distinct from in-phase stimulated emission observed in laser oscillators. We also show that the dynamics follows the universal synchronization theory for limit cycle oscillators. This provides a basic guideline for dynamic phase control of THz electronic oscillators, enabling many key performance indicators to be achieved in the new era of 6 G and beyond.

Passive mode-locking and terahertz frequency comb generation in resonant-tunneling-diode oscillator.

Optical frequency combs in the terahertz frequency range are long-awaited frequency standards for spectroscopy of molecules and high-speed wireless communications. However, a terahertz frequency comb based on a low-cost, energy-efficient, and room-temperature-operating device remains unavailable especially in the frequency range of 0.1 to 3 THz. In this paper, we show that the resonant-tunneling-diode (RTD) oscillator can be passively mode-locked by optical feedback and generate a terahertz frequency comb. The standard deviation of the spacing between the comb lines, i.e., the repetition frequency, is reduced to less than 420 mHz by applying external bias modulation. A simulation model successfully reproduces the mode-locking behavior by including the nonlinear capacitance of RTD and multiple optical feedback. Since the mode-locked RTD oscillator is a simple semiconductor device that operates at room temperature and covers the frequency range of 0.1 to 2 THz (potentially up to 3 THz), it can be used as a frequency standard for future terahertz sensing and wireless communications.

Real-Time Megapixel Electro-Optical Imaging of THz Beams with Probe Power Normalization.

In this work, we present a simple method to improve the spatial uniformity of two-dimensional electro-optical imaging of terahertz (THz) beams. In this system, near-field THz images are captured by fully illuminating a sample using conventional optical microscope objectives. Unfortunately, due to the linear relationship between the optical probe power and the measured THz electric field, any spatial variation in probe intensity translates directly into a variation of the recorded THz electric field. Using a single normalized background frame information map as a calibration tool prior to recording a sequence of THz images, we show a full recovery of a two-dimensional flat field for various combinations of magnification factors. Our results suggest that the implementation of dynamic intensity profile correction is a promising avenue for real-time electro-optical imaging of THz beams.

Long-term results of laparoscopic Hassab's procedure for esophagogastric varices with portal hypertension.

INTRODUCTION: Recent reports have shown laparoscopic gastric devascularization and splenectomy (Hassab's procedure) to be a safe and effective treatment for esophagogastric varices with portal hypertension. However, the long-term postoperative results remain unclear. METHODS: Between 2009 and 2015, 17 patients with portal hypertension and esophagogastric varices underwent laparoscopic Hassab's procedure at our institution. Two patients were lost to long-term follow-up (at least 2 years) and excluded. The remaining 15 patients' data and endoscopic findings were retrospectively reviewed. RESULTS: The median postoperative follow-up period was 56 months. The median spleen volume, operation time, blood loss, and length of postoperative hospital stay were 651 (320-1,265) mL, 305 (275-547) minutes, 347 (24-1,131) mL, and 20 (8-41) days, respectively. According to the endoscopic findings 1 year after surgery, the esophagogastric varices disappeared in three patients and improved in 12 patients. The median platelet count was significantly higher 1 year after surgery (19.7 × 104 /dL) than before surgery (5.5 × 104 /dL) (P < .001) and remained stable 2 years after surgery. Two patients died of liver disease. The remaining 13 patients, with a median postoperative follow-up of 57 months, were alive without bleeding from esophagogastric varices. CONCLUSION: Laparoscopic Hassab's procedure is a feasible treatment for esophagogastric varices with portal hypertension in terms of both short- and long-term results.

Dynamical Collectivity and Nuclear Quantum Effects on the Intermolecular Stretching Mode of Liquid Water.

This study investigated the broadband terahertz and low-frequency Raman spectroscopy of liquid water (H2O, D2O, and H218O) over 2 decades of frequency to address long-standing challenges regarding the interpretation of the intermolecular stretching mode at around 5 THz. We experimentally demonstrated that the intermolecular stretching mode of liquid water obtained via terahertz spectroscopy is significantly redshifted and broadened compared with that via Raman. This result was rationalized by the enhanced dynamical collectivity probed by terahertz spectroscopy, although both have a common origin in the kinetic motion. Their temperature and isotope dependences emphasize the significance of oscillation mass in determining the intermolecular stretching lineshape, while quantum effects cannot be overlooked in both terahertz and low-frequency Raman spectra.

Preoperative Controlling Nutritional Status plus Tumor Burden Score for the Assessment of Prognosis after Curative Liver Resection for Hepatocellular Carcinoma.

OBJECTIVE: There are no previous studies analyzing the prognostic predictive value of adding the tumor factor (i.e., Tumor Burden (TB) score) to the Controlling Nutritional Status (CONUT) score for patients with hepatocellular carcinoma (HCC). This study aimed to investigate the value of the CONUT plus TB (CONUT-TB) score as a prognostic predictor in patients with HCC undergoing liver resection. METHODS: Between 2015 and 2018, 96 consecutive patients with HCC underwent liver resection at our institution. Patients undergoing repeated liver resection and combined resection of a metastatic lesion were excluded. Patients were divided into 2 groups according to their CONUT-TB scores according to a cutoff value. Clinicopathologic prognostic factors for survival were analyzed using a database containing the medical records. RESULTS: The optimal cutoff value of the CONUT-TB score determined by using a minimum p value approach was 13 points. Among the 81 patients included in the analytic cohort, 71 patients had low (<13) and 10 patients had high (>13) CONUT-TB scores. The overall 3-year survival rate of patients following liver resection for HCC in the high-CONUT-TB group was significantly worse than that of patients in the low-CONUT-TB group (62.5 vs. 89.3%, p = 0.003). Multivariate analysis indicated that a high CONUT-TB score was independently associated with overall survival after liver resection (p = 0.010). CONCLUSION: The CONUT-TB score is a valuable predictor of survival in patients with HCC after liver resection.

European Society for Clinical Nutrition and Metabolism (ESPEN) Malnutrition Criteria for Predicting Major Complications After Hepatectomy and Pancreatectomy.

BACKGROUND: Recently, diagnostic criteria for malnutrition have been proposed by the European Society for Clinical Nutrition and Metabolism (ESPEN). This study aimed to investigate the utility of the ESPEN malnutrition criteria as a predictor for major complications following hepatectomy and pancreatectomy. METHODS: Data were reviewed from 176 consecutive patients who underwent hepatectomy (n = 103) or pancreatectomy (n = 73) between November 2017 and December 2019. Patients were divided into two groups according to the ESPEN malnutrition criteria using a prospectively collected database. The clinical data and the surgical outcomes of patients in the malnourished and normal groups were retrospectively analyzed. RESULTS: Thirty-five (20%) patients were diagnosed with malnourishment according to ESPEN criteria. The malnourished group had a significantly low preoperative albumin concentration (p = 0.001). After hepatectomy, major complications (Clavien grade ≥ 3a) occurred significantly more frequently in the malnourished group than in the normal group (p = 0.013). Multivariate analysis indicated that operative duration ≥ 300 min (hazard ratio: 22.47, 95% CI: 2.17 to 232.73, p = 0.009) and malnourishment (hazard ratio: 14.56, 95% CI: 2.58 to 82.17, p = 0.002) were independently associated with major complications after hepatectomy. On the other hand, malnutrition was not associated with major complications after pancreatectomy. CONCLUSIONS: The ESPEN malnutrition criteria are a valuable predictor for major complications following hepatectomy.

Dual common bile duct examination with transcystic choledochoscopy and cholangiography in laparoscopic cholecystectomy for suspected choledocholithiasis: a prospective study.

BACKGROUND: Detection of common bile duct (CBD) stones is a major objective of intraoperative cholangiography (IOC) in laparoscopic cholecystectomy (LC). We evaluated the feasibility and safety of the routine use of transcystic choledochoscopy following IOC (dual common bile duct examination: DCBDE), which may improve the diagnostic accuracy of CBD stones and facilitate one-stage clearance, in LC for suspected choledocholithiasis. METHODS: Between May 2017 and November 2018, 38 patients with suspected choledocholithiasis were prospectively enrolled in this study, regardless of whether they underwent endoscopic sphincterotomy. Transcystic choledochoscopy was routinely attempted following IOC in LC. RESULTS: Five cases were excluded due to cholecystitis, bile duct anomaly, or liver cirrhosis. DCBDE was performed in the remaining 33 patients. The biliary tree was delineated by IOC in all patients. Subsequently, choledochosope was performed in 32 patients except for one who was found to have pancreaticobiliary malunion in IOC. The scope was successfully passed into the CBD in 25 (78.1%) patients. Choledochoscopy detected 3 (9.4%) cases of cystic duct stones and 4 (12.5%) cases of CBD stones which were not identified by IOC. All those stones were removed via cystic duct. There were no intra- and postoperative complications, except for two cases of wound infection and one case of a transient increase in serum amylase. CONCLUSIONS: DCBDE in LC is a safe and promising approach for intraoperative diagnosis and one-stage treatment of suspected choledocholithasis.

Preliminary results of robotic inguinal hernia repair following its introduction in a single-center trial.

AIM: Robotic surgery using the da Vinci system has markedly increased worldwide. However, robotic inguinal hernia repair remains unpopular outside the United States. We introduced and evaluated a robotic transabdominal preperitoneal repair (R-TAPP) technique for inguinal hernia in our hospital. METHODS: First, we designed a task protocol according to the surgical results of 388 laparoscopic TAPP (L-TAPP) procedures performed during the 4 years prior to introducing R-TAPP. Our task protocol included several time limitations during a step-wise procedure: creating the peritoneal flap (<60 minutes), mesh placement with fixation (<30 minutes), and peritoneal suture closure (<30 minutes) under experienced supervision. We investigated the preliminary clinical results of R-TAPP performed by a single operator between December 2018 and January 2020. RESULTS: We identified 27 lesions in 20 patients (unilateral in 13 and bilateral in seven). According to the Japan Hernia Society Classification, our cohort included eight type I, five type II, and seven bilateral hernias (nine type I, four type II, and one type IV). The median operation time was 124 minutes (range, 81-164 minutes), and the median console operation time was 85 minutes (range, 50-132). The median time required for the peritoneal incision was 30 minutes (range, 18-54 minutes), that for mesh placement (including tucking) was 13 minutes (range, 7-27 minutes), and that for peritoneal suturing was 9 minutes (range, 3-20 minutes). CONCLUSION: Our preliminary results suggest that our task protocol for R-TAPP is feasible. However, refinement of our task protocol is essential for standardization.

A novel classification of aberrant right hepatic ducts ensures a critical view of safety in laparoscopic cholecystectomy.

BACKGROUND: Based on the spatial relationship of an aberrant right hepatic duct (ARHD) with the cystic duct and gallbladder neck, we propose a practical classification to evaluate the specific form predisposing to injury in laparoscopic cholecystectomy (LC). METHODS: We retrospectively investigated the preoperative images (mostly magnetic resonance cholangiopancreatography) and clinical outcomes of 721 consecutive patients who underwent LC at our institute from 2015 to 2018. We defined the high-risk ARHD as follows: Type A: communicating with the cystic duct and Type B: running along the gallbladder neck or adjacent to the infundibulum (the minimal distance from the ARHD < 5 mm), regardless of the confluence pattern in the biliary tree. Other ARHDs were considered to be of low risk. RESULTS: A high-risk ARHD was identified in 16 cases (2.2%): four (0.6%) with Type A anatomy and 12 (1.7%) with Type B. The remaining ARHD cases (n = 34, 4.7%) were categorized as low risk. There were no significant differences in the operative outcomes (operative time, blood loss, hospital stay) between the high- and low- risk groups. Subtotal cholecystectomy was applied in four cases (25%) in the high-risk group, a significantly higher percentage than the low-risk group (n = 1, 2.9%). In all patients with high-risk ARHD, LC was completed safely without bile duct injury or conversion to laparotomy. CONCLUSIONS: Our simple classification of high-risk ARHD can highlight the variants located close to the dissecting site to achieve a critical view of safety and may contribute to avoiding inadvertent damage of an ARHD in LC.

Observation of an exotic state of water in the hydrophilic nanospace of porous coordination polymers.

Fundamental understanding of the confinement of water in porous coordination polymers (PCPs) is important not only with respect to their application, such as in gas storage and separation, but also for exploring confinement effects in nanoscale spaces. Here, we report the observation of water in an exotic state in the well-designed hydrophilic nanopores of PCPs. Single-crystal X-ray diffraction finds that nanoconfined water has an ordered structure that is characteristic in ices, but infrared spectroscopy reveals a significant number of broken hydrogen bonds that is characteristic in liquids. We find that their structural properties are quite similar to those of solid-liquid supercritical water predicted in hydrophobic nanospace at extremely high pressure. Our results will open up not only new potential applications of water in an exotic state in PCPs to control chemical reactions, but also experimental systems to clarify the existence of solid-liquid critical points.

Novel approach to intraoperative peritoneal lavage with an extracorporeal stirring method in laparoscopic surgery for generalized peritonitis: Preliminary results.

INTRODUCTION: The primary concern with laparoscopic intraoperative peritoneal lavage (IOPL) for generalized peritonitis relates to the difficulty and uncertainty in ensuring adequate washout of contaminated fluid. Here, we describe a new method of laparoscopy-assisted IOPL. METHODS: We performed emergency surgery in 10 patients with generalized peritonitis necessitating IOPL. A small wound retractor was inserted into the abdominal cavity through an incision and elevated to raise the abdominal wall. More than 3-L saline was injected via the retractor at one time. The abdomen was manually shaken by pressure from outside the body. Contaminated fluid was removed with a long suction device through the retractor. This procedure was repeated until the fluid was confirmed to be transparent by laparoscopy, and then drains were placed. RESULTS: Median lavage time was 23.5 minutes (range, 15-34 minutes), and volume of lavage fluid was 19 L (range, 10-20 L). Median time to resumption of fluid intake was 3 days (range, 1-12 days), time to food intake was 6 days (range, 3-14 days), and time to first bowel movement was 5 days (range, 3-10 days). Median duration of antibiotic use was 8.5 days (range, 5-15 days). Complications were one case of antibiotic-induced rash, two cases of paralytic ileus, and one case of pelvic abscess. All patients recovered well without additional surgical intervention. CONCLUSIONS: This new approach to laparoscopy-assisted IOPL was feasible for these patients with generalized peritonitis. This procedure enabled corpus lavage to be performed in a similarly short time to open surgery but with less invasiveness. Further research is needed to confirm indications and long-term outcomes.

Laparoscopic repair of secondary perineal hernia with coverage by the mobilized cecum.

The incidence of secondary perineal hernia (SPH) has increased since the introduction of extralevator abdominoperineal resection and laparoscopic abdominoperineal resection. Currently, laparoscopic mesh repair is the usual procedure. Here, we demonstrate a repair of SPH without mesh that uses the mobilized cecum to cover the pelvic hernial orifice. An 83-year-old man complained of discomfort when sitting for long periods. He was status post laparoscopic abdominoperineal resection and was diagnosed with SPH. Hernia repair was performed. After transperitoneal adhesiolysis in the inferior pelvis, the right colon was laparoscopically mobilized, and the pelvic orifice was covered by suturing the cecum to the pelvic brim. The perineal skin was managed with negative pressure wound therapy. The postoperative course was uneventful. There has been no sign of recurrent herniation for 12 months. This method of SPH repair is simple to perform and avoids mesh-related complications.

Terahertz microscopy assisted by semiconductor nonlinearities.

Terahertz (THz) imaging is currently based on linear effects, but there is great interest on how nonlinear effects induced by terahertz radiation could be exploited to provide extra information that is unobtainable by conventional imaging schemes. In particular, at field strengths on the order of 100 kV cm-1 to 1 MV cm-1, transmission properties inside semiconductor materials are largely affected at the picosecond time-scale, which raise the prospect of interesting nonlinear imaging applications at THz frequencies. Here, we experimentally investigate a method to map the two-dimensional nonlinear near-field distribution of an intense THz pulse passing through a thin film-doped semiconductor. By inserting a metamaterial structure between the electro-optic sensor and the doped film, the nonlinear near-field dynamics shows a different and enhanced contrast of the sample when compared to its linear counterpart.

Reconsideration of the relaxational and vibrational line shapes of liquid water based on ultrabroadband dielectric spectroscopy.

The Debye relaxation function is widely used to describe the large dielectric dispersion of ambient water around 20 GHz. However, from a theoretical point of view, this function is supposed to give incorrect predictions at high frequencies owing to the inappropriate assumption that inertial effects and intermolecular interactions do not affect the relaxation dynamics. Our ultrabroadband spectroscopy investigation of liquid water ranging from 500 MHz to 400 THz did demonstrate that the Debye function is inaccurate far above the microwave region. As an alternative, we tried a stochastic frequency modulation (SFM) model assuming instantaneous modification of the line shapes by the correlation with the surrounding system. The SFM relaxation model reproduced the experimental dielectric spectra up to 400 THz, showing that the hydrogen-bond dynamics are associated with the inertial effect that causes the non-exponential relaxation behaviour in a very short time (typically 25 fs). Within the framework of this relaxation model, the hindered translation modes are able to be approximated as fast modulation (homogeneous) line shapes because the interaction time with frequency modulation is too short. Compared with them, the libation mode is found to have a relatively slow modulation (inhomogeneous) origin, where disturbance of water hydrogen bonds induced by the hindered translations leads to fluctuations in the libration frequency.

Intrapericardial diaphragmatic hernia into the pericardium after esophagectomy: a case report.

BACKGROUND: Intrapericardial diaphragmatic hernia (IPDH), defined as prolapse of the abdominal viscera into the pericardium, is a rare clinical condition. This case illustrates the possibility of IPDH after esophagectomy with antethoracic alimentary reconstruction, although such hernias are extremely rare. IPDH often presents with symptoms of bowel obstruction such as abdominal discomfort or vomiting. If not properly treated, life-threatening necrosis and/or perforation of the herniated contents may occur. CASE PRESENTATION: A 68-year-old Japanese man underwent subtotal esophagectomy with three-field lymph node dissection for treatment of esophageal cancer. Completion gastrectomy with perigastric lymph node dissection was also performed because the patient had previously undergone distal partial gastrectomy for treatment of gastric cancer. The alimentary continuity was reconstructed using the pedicled jejunal limb through the antethoracic route. When we separated the diaphragm from the esophagus and removed xiphoid surgically to prevent a pedicled jejunal limb injury, the pericardium was opened. The patient was readmitted to our hospital because of abdominal discomfort and vomiting 6 months after the esophagectomy. A diagnosis of IPDH after esophagectomy was made. The patient was treated by primary closure of the diaphragmatic defect using vertical mattress sutures and additional reinforcement of the closing defect using a graft harvested from the rectus abdominis posterior sheath. The postoperative course was uneventful, and he was discharged on the seventh day after hernia repair. CONCLUSIONS: This patient's clinical course provides two important clinical suggestions. First, we must be aware of the possibility of iatrogenic IPHD after esophagectomy with antethoracic alimentary reconstruction. Second, a graft from the rectus abdominis posterior sheath is beneficial in the treatment of IPDH.

Sphincter-preserving surgery for recurrent pelvic malignancy using a hybrid procedure of open laparotomy and transanal endoscopic approach.

BACKGROUND: Surgery for the treatment of recurrent pelvic malignancy is challenging. Sphincter-preserving surgery (SPS) has been applied in limited cases. Transanal endoscopic approach (TEA) has been used for primary rectal cancer, predominantly for hybrid transabdominal-transanal total mesorectal excision. Here, we describe the use of TEA as a hybrid approach in a case of recurrent ovarian cancer. CASE PRESENTATION: A 59-year-old woman had recurrence of serous ovarian adenocarcinoma in the vaginal stump, near the site of anastomosis from a rectal resection 18 months previously. We used a hybrid approach comprising conventional open laparotomy and TEA to accomplish sphincter preservation. In addition to sphincter preservation, TEA allowed for the creation of a "terminal" space, which was made by anterior dissection between the rectum and the vagina. We employed TEA to create an opening in the scar tissue along the sacrum, which was used as a "guide" for pelvic dissection to prevent nerve injury. After exteriorization of the tumor, bowel continuity was achieved by hand-sewn coloanal anastomosis with a protective diverting ileostomy. Pathological examination revealed no involvement of the surgical margins. The diverting ileostomy was taken down 8 months postoperatively. CONCLUSION: A hybrid approach comprising conventional open laparotomy and TEA allowed for safe and secure SPS and complete excision of a recurrent pelvic malignancy. This hybrid surgical approach expands the use of SPS in highly selected cases.

Coexistence of Kosmotropic and Chaotropic Impacts of Urea on Water As Revealed by Terahertz Spectroscopy.

Whether urea can serve as a kosmotrope or chaotrope has long been a topic of debate. In this study, broad-band THz spectroscopy (0.2-12 THz) of aqueous solutions of urea was used to characterize the hydration state and the hydrogen bond structure of water around urea. Three low-frequency vibration modes of urea were found around 2, 4, and above 12 THz. After eliminating the contribution of these modes, the "urea-vibration-free" complex dielectric constant was decomposed into the relaxation modes of bulk water and the oscillation modes of water. When hydration water is defined to be reorientationally retarded relative to bulk, our analysis revealed that the hydration number is 1.9 independent of urea concentrations up to 5 M, and this number is in close agreement with that of water constrained by strong acceptor hydrogen bonds of urea oxygen. Regarding the hydrogen bond structure, it was found that the tetrahedral-like water structure is mostly preserved (though the hydrogen bond lifetime is significantly shortened) but the population of non-hydrogen-bonded water molecules fragmented from the network is markedly increased, presumably due to urea's NH2 inversion. These experimental results point to the coexistence of apparently two contradictory aspects of urea: dynamical retardation (the kosmotropic aspect) by the -CO group and slight structural disturbance (the chaotropic aspect) by the -NH2 group.

Closure of the cystic duct orifice in laparoscopic subtotal cholecystectomy for severe cholecystitis.

INTRODUCTION: Laparoscopic subtotal cholecystectomy (LSC) has been recognized as an alternative to conversion to laparotomy for severe cholecystitis. However, it may be associated with an increased risk of recurrent stones in the gallbladder remnant. The objective of this study was to evaluate the safety and feasibility of the complete removal of the gallbladder cavity in LSC for severe cholecystitis using the cystic duct orifice suturing (CDOS) technique. METHODS: In a consecutive series of 412 laparoscopic cholecystectomies that were performed from January 2015 to June 2017, 12 patients who underwent LSC with CDOS were enrolled in this retrospective study. In this procedure, Hartmann's pouch was carefully identified, and the infundibulum-cystic duct junction was transected while the posterior wall adherent to Calot's triangle was left behind. The clinical records, including the operative records and outcomes, were analyzed. RESULTS: The median operating time and blood loss were 158 min and 20 mL, respectively. In all cases, LSC with CDOS was completed without conversion to open surgery. No injuries to the bile duct or vessels were experienced. The median postoperative hospital stay was 6 days. Postoperative complications occurred in two patients (bile leakage, n = 1: common bile duct stones, n = 1) and were successfully treated by endoscopic management. A gallbladder remnant was not delineated by postoperative imaging in any of the cases. CONCLUSION: These results suggest that LSC with CDOS is a promising approach that can avoid dissection of Calot's triangle and achieve the complete removal of the gallbladder cavity in patients with severe cholecystitis.

Surgical outcome of laparoscopic hepatic resection for hepatocellular carcinoma: A matched case-control study with propensity score matching.

BACKGROUND: Although the number of reports on laparoscopic hepatic resection (LHR) has increased, studies of long-term outcomes regarding tumor recurrence and patient survival compared to the conventional open approach are limited. We evaluated the long-term survival and feasibility of LHR in patients with hepatocellular carcinoma (HCC). PATIENTS AND METHODS: A retrospective analysis was performed on the clinical data of patients who underwent hepatic resection for primary HCC between August 2000 and December 2013. The patients were divided into the LHR or open hepatic resection (OHR) groups. To control for selection bias in the two groups, propensity score matching was used at a 1:1 ratio based on the following covariates: Child-Pugh grade, tumour size, tumour number and tumour location. Following propensity score matching, thirty patients were included in the LHR group and thirty were included in the OHR group. RESULTS: The respective disease-free survival rates at 1 year, 3 years and 5 years were 78.4%, 61.1% and 38.9%, respectively, for the LHR group, and 89.3%, 57.5% and 47.9%, respectively, for the OHR group (P = 0.89). Also, the overall survival rates at 1 year, 3 years and 5 years were 96.4%, 68.2% and 62.5%, respectively, for the LHR group and 100.0%, 95.8% and 72.3%, respectively, for the OHR group (P = 0.44). CONCLUSIONS: According to our study, using propensity score matching, LHR for HCC is safe, feasible and comparative, with good oncologic results.