Broadband 2D phase-gradient metasurface for linearly-polarized waves by suppressing Lorentz resonance of meta-atoms.

Metasurfaces have exhibited versatile capacities of controlling electromagnetic (EM) waves due to the high degree of freedom of designing artificially engineered meta-atoms. For circular polarization (CP), broadband phase gradient metasurfaces (PGMs) can be realized based on P-B geometric phase by rotating meta-atoms; while for linear polarization (LP), realization of broadband phase gradients has to resort to P-B geometric phase during polarization conversion and polarization purity has to be sacrificed for broadband properties. It is still challenging to obtain broadband PGMs for LP waves without polarization conversion. In this paper, we propose the design of 2D PGMs by combining the inherently wideband geometric phases and non-resonant phases of meta-atom, under the philosophy of suppressing Lorentz resonances that usually bring about abrupt phase changes. To this end, an anisotropic meta-atom is devised which can suppress abrupt Lorentz resonances in 2D for both x- and y-polarized waves. For y-polarized waves, the central straight wire is in perpendicular to electric vector Ein of incident waves, Lorentz resonance cannot be excited although the electrical length approaches or even exceeds half a wavelength. For x-polarized waves, the central straight wire is in parallel with Ein, a split gap is opened on the center of the straight wire so as to avoid Lorentz resonance. In this way, the abrupt Lorentz resonances are suppressed in 2D and the wideband geometric phase and the gradual non-resonant phase are left for broadband PGM design. As a proof of concept, a 2D PGM prototype for LP waves was designed, fabricated and measured in microwave regime. Both simulated and measured results show that the PGM can achieve broadband beam deflection for reflected waves for both x- and y-polarized waves in broadband, without changing the LP state. This work provides a broadband route to 2D PGMs for LP waves and can be readily extended to higher frequencies such as terahertz and infrared regimes.

Multifield-Controlled Terahertz Hybrid Metasurface for Switches and Logic Operations.

Terahertz (THz) meta-devices are considered to be a promising framework for constructing integrated photonic circuitry, which is significant for processing the upsurge of data brought about by next-generation telecommunications. However, present active metasurfaces are typically restricted by a single external driving field, a single modulated frequency, fixed switching speed, and deficiency in logical operation functions which prevents devices from further practical applications. Here, to overcome these limitations, we propose a hybrid THz metasurface consisting of vanadium dioxide (VO2) and germanium (Ge) that enables electrical and optical tuning methods individually or simultaneously and theoretically investigate its performance. Each of the two materials is arranged in the meta-atom to dominate the resonance strength of toroidal or magnetic dipoles. Controlled by either or both of the external excitations, the device can switch on or off at four different frequencies, possessing two temporal degrees of freedom in terms of manipulation when considering the nonvolatility of VO2 and ultrafast photogenerated carriers of Ge. Furthermore, the "AND" and "OR" logic operations are respectively achieved at two adjacent frequency bands by weighing normalized transmission amplitude. This work may provide an auspicious paradigm of THz components, such as dynamic filters, multiband switches, and logical modulators, potentially promoting the design and implementation of multifunctional electro-optical devices in future THz computing and communication.

Calibration-free, high-precision, and robust terahertz ultrafast metasurfaces for monitoring gastric cancers.

Optical sensors, with great potential to convert invisible bioanalytical response into readable information, have been envisioned as a powerful platform for biological analysis and early diagnosis of diseases. However, the current extraction of sensing data is basically processed via a series of complicated and time-consuming calibrations between samples and reference, which inevitably introduce extra measurement errors and potentially annihilate small intrinsic responses. Here, we have proposed and experimentally demonstrated a calibration-free sensor for achieving high-precision biosensing detection, based on an optically controlled terahertz (THz) ultrafast metasurface. Photoexcitation of the silicon bridge enables the resonant frequency shifting from 1.385 to 0.825 THz and reaches the maximal phase variation up to 50° at 1.11 THz. The typical environmental measurement errors are completely eliminated in theory by normalizing the Fourier-transformed transmission spectra between ultrashort time delays of 37 ps, resulting in an extremely robust sensing device for monitoring the cancerous process of gastric cells. We believe that our calibration-free sensors with high precision and robust advantages can extend their implementation to study ultrafast biological dynamics and may inspire considerable innovations in the field of medical devices with nondestructive detection.

Pattern and prognostic value of lymph node metastasis in sinonasal mucosal melanoma.

OBJECTIVE: To analyze the pattern of lymph node (LN) metastasis and its effect on prognosis in sinonasal mucosal melanoma (SNMM). METHODS: This retrospective study was conducted based on the Surveillance, Epidemiology, and End Results (SEER) Program data. Survival outcomes were analyzed using the Kaplan-Meier method. Factors were compared between groups using log-rank test and Fisher's exact test, and prognostic factors were screened using the Cox proportional hazards model. Propensity score matching (PSM) was conducted to examine the treatment differences after accounting for sex, age, race, T stage, N stage, and M stage. RESULTS: Level I (57.1%) and level II (53.6%) nodes were the most common sites of lymph node metastasis, followed by level III (17.9%) and IV (17.9%) nodes. T stage, M stage, and tumor size were associated with LN metastasis. The 5-year overall survival rates for patients without and with LN metastasis were 35.2% and 5.3%, respectively. CONCLUSIONS: Level I and II lymph nodes may be the sentinel nodes of SNMM, Advanced T stage and increasing tumor size could promote LN metastasis. LN metastasis may promote distant metastasis and remains an important prognostic factor for patients with SNMM.

Designing an ultra-thin and wideband low-frequency absorber based on lumped resistance.

Traditional absorbers are mostly limited by their large size and high profile, which renders them unfavorable for practical devices. To solve this problem, we design and test an ultra-thin metamaterial absorber (UTMA). The top layer of the metamaterial absorber is designed as a patterned combination of split ring and metal strips, so that its resonant frequency point is in the target low frequency. Meanwhile, ohmic loss is enhanced by loading lumped resistance in the gap of the meta-surface to improve the absorb efficiency (> 90%) and to expand the working bandwidth (1.24-3.14 GHz). Moreover, the total thickness of the absorber is 9 mm (0.037λwith respect to the lowest operating frequency). The working mechanism of UTMA is analyzed based on the equivalent media theory, surface current and electric field energy distribution. The experimental results are in good agreement with the simulation, which verifies the feasibility of the design. In this work, the metamaterial absorber is designed to meet the target requirements from three performance indexes: low frequency, ultra-thin, and wideband, leading to the prospect of broad applications in the military and civil fields.

Optically Controlled Ultrafast Terahertz Metadevices with Ultralow Pump Threshold.

Arming metasurface with active materials furnishes a feasible solution to dynamically control over terahertz (THz) waves, which is extremely significant for the realization of upcoming sixth generation telecommunications. However, the present active materials are mainly limited to single external driving field, hindering the capability of metasurface for flexible manipulation of THz waves. Besides, less attention has been paid to the energy question how to significantly reduce the pump threshold for achieving the desired function. Here, a germanium (Ge) hybrid Fano metasurface under dual-stimulus control is experimentally demonstrated. Photoexcitation of Ge thin film enables 100% modulation depth of Fano resonance and ultrafast switching time within 10 ps. By adding current-bias, the pump threshold to modulate the metasurface is greatly reduced from 1600 to 200 µJ cm-2 . Different from the optical modulation independent of film thickness, it is found that the current function is in proportion with the thickness of Ge thin film. Moreover, it is demonstrated that compared to the single optical-stimulus, the THz amplitude modulation is increased by 56.3% under dual-stimulus function. This work naturally improves the flexibility and practicality of Ge-based metadevice and inspires more innovations to boost the development of switchable sensing, lasing spacer, and nonlinear systems.

Ultra-thin and broadband surface wave meta-absorber.

Perfect absorbers are highly desired in many engineering and military applications, including radar cross section (RCS) reduction, cloaking devices, and sensor detectors. However, most types of present absorbers can only absorb space propagation waves, but absorption for surface waves has not been researched intensively. Surface waves are easily excited on the interfaces between metal and dielectrics for electronic devices, which decreases their working performances due to the electromagnetic disturbances. Thus, it is of great significance to design appropriate absorbers to dissipate undesirable surface waves. Here, we propose the concept of a surface wave absorber, analyze its working principle, and prove its good performances experimentally. To demonstrate our concept, we design and fabricate a realistic surface wave absorber that is fixed on a metal surface. Experiments are performed to verify its electromagnetic characteristics. The results show that our designed meta-absorber can achieve an excellent surface wave absorption within a wide frequency window (5.8-11.2 GHz) and exhibit a very high efficiency over than 90%, but only with the thickness of 1 mm (0.028 λ). Our device can help to solve the issues of absorption at large angles, and it can find wide applications in large antenna array design and other communication systems.

Ultra-light planar meta-absorber with wideband and full-polarization properties.

Absorbers have high potential application values in the military field, such as electronic screening, radar cross-section reduction and invisible cloaking. However, most methods have the defects of narrow bandwidth, low absorptivity, complex three-dimensional structure and fixed polarizations. In this paper, we realize an ultra-broadband and full-polarization planar metamaterial absorber (PMA) with a three-layer composite structure, which exhibits multi-resonant and impedance matching properties by combining the ultra-light foams and indium tin oxide (ITO) films. The bottom two layers achieve a high-efficiency absorption rate at the low and medium spectrum, while the upper layer realizes a absorption property at a high frequency. Also, an equivalent circuit model is extracted to explain its operating mechanism. The experimental results show that our meta-absorber can achieve great absorber performance of better than 90% within 1-18 GHz for full-polarization incident waves, which is in great agreement with the numerical simulations. Moreover, our device is insensitive to oblique incidences and polarizations and possesses the physical characteristics of an ultralight, weighing 0.6 kg for a square meter, which is only 1/85.0-1/126.7 of the conventional absorbers under the same size. All these excellent performances determine that our research can be a good candidate for military stealth materials.

High-performance meta-absorber for the surface wave under the spoof surface plasmon polariton mode.

Perfect absorbers are highly desired in many engineering and military applications, including radar cross section (RCS) reduction, cloaking devices, and sensor detectors. However, most types of present absorbers can only absorb space propagation waves, yet absorption for the surface wave (SW) has not been researched intensively. In reality, when the space wave illuminates on the metal under large oblique angles, surface waves can be excited on the interface between metal and dielectric and thus would increase the RCS and influence the stealth performance. Here, based on the wave vector and impedance matching theories, we propose a broadband absorber for the surface wave under spoof surface plasmon polariton (SSPP) mode. The former theory ensures that surface waves can enter the absorber efficiently, and the latter guarantees perfect absorption. The experimental results indicate that our absorber can achieve a broadband (9.4-18 GHz) performance with an absorption ratio better than 90%, which is in great agreement with the simulations. Therefore, our device can be applied in RCS reduction for the metal devices, antenna array decoupling and many other applications. Also, this work provides a unique methodology to design new types of broadband surface wave absorbers.

High-performance and broadband chirality-dependent absorber based on planar spiral metasurface.

A perfect absorber is highly desired in many engineering applications, including cloaking devices and sensor detectors, but most types of absorbers with chirality-dependence have limited bandwidth. In this paper, we propose a novel broadband and chirality-dependent metasurface absorber that consists of an array of planar spiral elements. The spiral orientation can determine the absorption polarization, such as counterclockwise for right circular polarization (RCP) absorption and clockwise for left circular polarization (LCP) absorption. Three steps are adopted to enhance the absorption bandwidth: carefully optimizing the spiral turns, impedance of load resistor, and introducing a matching layer. To demonstrate our concept, we have designed and fabricated a realistic metasurface absorber. The numerical simulations are in good agreement with the experimental results. The simulation and measurement results demonstrate that this device can achieve a broadband (8.3-18 GHz) absorption for RCP incidence, while reflecting the LCP incident waves between 9 GHz to 17.8 GHz without changing its chirality. Our findings explore a novel way to realize broadband absorption and simultaneously provide a new strategy to design chirality-dependent multi-functional meta-devices.

Endoscopic anatomical study of the trans-lateral molar approach to the infratemporal fossa.

BACKGROUND: The infratemporal fossa (ITF) is located deep in the skull base. Recently, the endoscopic transoral approach has enabled maxillofacial surgeons to access the ITF using a less invasive approach compared to the traditional transfacial and endonasal endoscopic approaches. OBJECTIVE: The present study aims to provide maxillofacial surgeons with new data concerning direct endoscopic measurement and precise anatomical topography features of the endoscopic trans-lateral molar approach to ITF by comparing the endoscopic and regional anatomy of ITF. A clinical case receiving the proposed surgical approach is used to determine the feasibility of this technique. METHOD: The anatomical data were obtained by measuring the bone anatomical landmarks and analyzing the CT imaging data using GE's Advance Windows 4.1 software on 25 subjects (50 sides). Morphological pictures of the regional anatomy and endoscopic anatomy were obtained from 6 (12 sides) adult cadaver heads, and the anatomical features were described. The present study reports the management of one case using the proposed surgical approach. RESULTS: The proposed surgical approach clearly revealed neurovascular, muscular, and surgical landmarks in the ITF. The surgical case supports the minimally invasive treatment approach, which could rapidly access the ITF and completely excise benign tumors. CONCLUSION: The anatomical studies and surgical case presentation helps us understand the spatial relationship of surgical landmarks of the surgical approach to the ITF for the treatment of benign lesions in the deep cranial base area.

High-efficiency transparent vortex beam generator based on ultrathin Pancharatnam-Berry metasurfaces.

Vortex beam generators are promising to improve the transmission data rate and enlarge the communication capacity due to the fact that they inherently carry the orbital angular momentum (OAM). However, current available devices are limited because of high profiles and low efficiencies, especially for the transmissive case. Here, we propose a new strategy to design an ultrathin (0.07λ0) transmissive Pancharatnam-Berry (PB) metasurface with nearly unit transmittance. The carefully optimized metasurface integrates an anisotropic crossbar structure with positive permittivity and a holey metallic ring resonator with negative permittivity based on certain criterions placed on both sides of a dielectric substrate, which realize an exact π phase difference due to the control of permittivities at both polarizations. As a proof of concept, a microwave vortex beam generator is designed, fabricated and experimentally characterized. Both measured far-field and near-field characterizations are in excellent agreement with numerical simulations, indicating that our transmissive PB meta-device (operating at 10.6 GHz) exhibits a maximum experimental efficiency of 87%. Our findings can motivate the realizations of high-performance transmissive PB meta-devices with a very low profile or operation at other frequency domains.

Cochlea sparing with a stratified scheme of dose limitation employed in intensity-modulated radiotherapy for nasopharyngeal carcinoma: A dosimetry study.

Hearing loss is 1 of the major complications after radiotherapy in nasopharyngeal carcinoma (NPC) patients, how to minimize dose to cochlea in order to reduce the incidence of sensorineural hearing loss is a critical task. This study is to investigate a stratified scheme of cochlea sparing based on T stage in intensity-modulated radiotherapy. We designed a comparison between 2 plans of cochlea sparing plan (C-Plan) and regular noncochlea sparing plan (R-Plan) from 19 NPC patients with 2, 3, 8, and 6 cases of T1, T2, T3, and T4 stage, respectively. The outcomes showed that target coverage parameters and dose-volume histogram features were of no significant difference, with a significant difference in dose distribution between C-Plan and R-Plan in cochlea and eustachian, e.g., ipsilateral cochlea Dmean 4619.75 ± 1134.09 cGy in C-Plan and 5061.03 ± 1121.09 cGy in R-Plan (p = 0.000), contralateral cochlea Dmean 4386.73 ± 945.14 cGy in C-Plan and 4991.38 ± 961.21 cGy in R-Plan (p = 0.000). Meanwhile, there was no significant difference in dose distribution in spinal cord, brainstem, and other OARs. Our dosimetry study showed cochlea sparing in intensity-modulated radiotherapy for NPC reduced cochlea dose to different extent, so we suggested a stratified scheme of cochlea sparing based on T stage could be a useful and practical tool for both physicists and radiation doctors.

[Clinical study on lymph node metastasis regularity in 1456 patients with gastric cancer].

OBJECTIVE: To investigated the characteristics and regularity of lymph node metastasis around gastric cancer in order to provide reference for standardized and optimal surgical treatment. METHODS: A retrospective case series study was carried out on 1456 patients with gastric cancer undergoing surgical treatment at the Affiliated Tumor Hospital of Tianjin Medical University from March 2003 to August 2011. The number of harvested lymph node and metastasis status of various lymph node station were determined by routine pathological examination of specimens, including resected gastric tissue and dissected lymph node tissue, according to the 13th version of the Japanese Gastric Cancer Treatment Guidelines. Tumor T, N and M staging was performed to evaluate lymphatic metastasis status of different locations of gastric cancer according to the TNM staging criteria of the 8th edition of the American Joint Committee on Cancer (AJCC). The influence of gender, age, tumor diameter, Borrmann type, T staging and M staging, tumor differentiation degree, invasion of vessels, lymphatic vessels and nerves, radical surgical degree and other clinical factors on lymph node metastasis was analyzed. RESULTS: A total of 1062 cases(72.9%) had lymph node metastasis in the 1456 patients with gastric cancer. A total of 9766 lymph nodes were positive for metastasis. Lymph node metastasis occurred in 11 of 44 (25.0%) patients with early gastric cancer and in 1051 of 1412 (74.4%) patients with advanced gastric cancer. The largest number of lymph node metastases was found in No.3 station [653 cases (44.8%)], followed by No.6 [437 cases(30.0%)], No.7 [345 cases (23.7%)], No.1 [304 cases (20.9%)], No.4sb [290 cases (19.9%)]. No.14v lymph node metastasis was observed in 23 cases, of whom No.6 (16 cases, 69.6%), No.8a (15 cases, 65.2%) and No.3 (12 cases, 52.2%) developed simultaneous metastasis. As for different locations of gastric cancer, stations with more lymph node metastasis in 309 patients with proximal gastric cancer were No.3 (133 cases, 43.0%), No.1 (96 cases, 31.1%), No.2 (90 cases, 29.1%) and No.7 (89 cases, 28.8%); in 144 patients with middle gastric cancer were No.3 (68 cases, 47.2%), No.6 (50 cases, 34.7%), No.7 (40 cases, 27.8%) and No.4sb (38 cases, 26.4%); in 700 patients with distal gastric cancer were No.3(287 cases, 41.0%), No.6 (265 cases, 37.8%), No.4sb (138 cases, 19.7%) and No.8a (138 cases, 19.7%); in 303 cases with diffuse-type gastric cancer were No.3 (165 cases, 54.4%), No.6 (100 cases, 33.0%), No.7 (88 cases, 29.0%), No.1 (84 cases, 27.7%) and No.4sb (72 cases, 23.8%). The incidence of lymph node skip metastasis was 7.2% (105/1456) in whole group. Positive lymph node metastasis was associated with tumor size (RR=2.016, 95%CI: 1.550-2.621, P=0.000), tumor differentiation(RR=1.631, 95%CI:1.405-1.894, P=0.000), tumor T staging (RR=1.886, 95%CI: 1.629-2.184, P=0.000), tumor M staging (RR=3.671, 95%CI:1.265-10.660, P=0.017) and radical surgery(RR=3.819, 95%CI: 2.023-7.207, P=0.000). CONCLUSIONS: The main direction of peripheral lymph node drainage in gastric cancer is lesser curvature, and then the left gastric artery, the common hepatic artery and the peripheral lymph nodes of the celiac axis, and finally the peripheral lymph nodes of the abdominal aorta. Therefore the No.6 station lymph node adjacent to the perigastric area, the No.7, No.8 and No.9 lymph nodes should be the focus of the radical surgical dissection of gastric cancer. Tumor size, differentiation degree, invasion depth and distant metastasis have significant association with lymph node metastasis. For patients with adverse factors, radical surgery is necessary to ensure efficacy.

High-efficiency dual-modes vortex beam generator with polarization-dependent transmission and reflection properties.

Vortex beam is believed to be an effective way to extend communication capacity, but available efforts suffer from the issues of complex configurations, fixed operation mode as well as low efficiency. Here, we propose a general strategy to design dual-modes vortex beam generator by using metasurfaces with polarization-dependent transmission and reflection properties. Combining the focusing and vortex functionalities, we design/fabricate a type of compact dual-modes vortex beam generator operating at both reflection/transmission sides of the system. Experimental results demonstrate that the designed metadevice can switch freely and independently between the reflective vortex with topological charge m1 = 2 and transmissive vortex with m2 = 1. Moreover, the metadevice exhibits very high efficiencies of 91% and 85% for the reflective and transmissive case respectively. Our findings open a door for multifunctional metadevices with high performances, which indicate wide applications in modern integration-optics and wireless communication systems.

Supraglottic squamous cell carcinomas have distinctive clinical features and prognosis based on subregion.

OBJECTIVE: To analyze the clinicopathologic characteristics and prognosis of patients with squamous cell carcinoma localized to different supraglottic subregions. METHODS: Clinicopathologic data were reviewed retrospectively for 111 patients with supraglottic squamous cell carcinoma who were diagnosed between January 1, 1995 and December 31, 2005 and were initially treated with surgery. DNA from human papillomavirus (HPV) 16 and (or /and) HPV 18 were detected in all the 111 supraglottic carcinoma specimens using in situ hybridization. Survival analysis was performed by Kaplan-Meier analysis, factors were compared using log-rank test, and prognostic factors were determined using Cox proportional hazards model. The relationship between subregions and clinicopathologic factors was analyzed using Chi-square tests. RESULTS: HPV prevalence differed between patients with aryepiglottic fold carcinoma and ventricle carcinoma (P < .05). The local-regional control rates, overall survival rates or cancer specific survival rates were significantly different between different subregions. Univariate analysis indicated that pTNM classification, pN spread, and subregion were associated with prognosis (P < .05). Multivariate analysis indicated that pTNM classification and subregion were associated with supraglottic carcinoma prognosis. The survival rate was better for patients with carcinoma of the epiglottis or ventricular bands compared to those with carcinoma in the aryepiglottic fold or ventricle (P = .012). CONCLUSIONS: Subregion may be a new prognostic factor for supraglottic squamous cell carcinoma. Different supraglottic carcinoma subregions have distinct clinical features such as HPV expression, lymph node metastasis rate, local-regional control and prognosis. Therefore, it is necessary to subdivide supraglottic squamous cell carcinomas into several subregion groups to individualize therapy.

Random Combinatorial Gradient Metasurface for Broadband, Wide-Angle and Polarization-Independent Diffusion Scattering.

This paper proposes an easy, efficient strategy for designing broadband, wide-angle and polarization-independent diffusion metasurface for radar cross section (RCS) reduction. A dual-resonance unit cell, composed of a cross wire and cross loop (CWCL), is employed to enhance the phase bandwidth covering the 2π range. Both oblique-gradient and horizontal-gradient phase supercells are designed for illustration. The numerical results agree well with the theoretical ones. To significantly reduce backward scattering, the random combinatorial gradient metasurface (RCGM) is subsequently constructed by collecting eight supercells with randomly distributed gradient directions. The proposed metasurface features an enhanced specular RCS reduction performance and less design complexity compared to other candidates. Both simulated and measured results show that the proposed RCGM can significantly suppress RCS and exhibits broadband, wide-angle and polarization independence features.

Polarization-independent broadband meta-surface for bifunctional antenna.

Functional integration is crucial and has become a research interest in recent years; however, available efforts suffer from low efficiency and narrow operating bandwidth. Here, we propose a novel strategy to design bifunctional meta-surface with high efficiency and largely enhanced bandwidth in reflection geometry. For demonstration, we designed and fabricated a bifunctional meta-surface which enables both focusing and anomalous reflection under different polarizations. The working bandwidth is significantly extended by using the dual-resonant three-turn meander-line resonator (TMLR) element which provides an almost consistent phase response within a large frequency interval. For potential applications, we engineered a bifunctional antenna by launching the designed meta-surface with proper feed sources. Numerical and experimental results coincide well, indicating bifunctionalities of high gain pencil-beam radiation (reflectarray) and beam steering radiation with comparable performances. Our results can stimulate the realizations of high-performance meta-surfaces and antenna systems.

[Pituitary adenoma with initial symptom of cerebrospinal fluid rhinorrhea: a case report].

Pituitary adenoma with cerebrospinal fluid rhinorrhea is rare clinically. In this paper, through the analysis of a pituitary adenoma patient with initial symptom of cerebrospinal fluid rhinorrhea, we look forward to provide evidence for clinical diagnosis, so that we can avoid misdiagnosis.

[Endoscopic minitrephination combined with endoscopic frontal sinusotomy for management of chronic frontal sinusitis].

OBJECTIVE: To evaluate the efficacy of endoscopic minitrephination combined with endoscopic frontal sinusotomy in the management of complex chronic frontal sinusitis. METHOD: Twenty-six patients suffering from chronic frontal sinusitis with complex frontal drainage approach were analyzed. Eleven patients (13 sides) received endoscopic minitrephination combined with endoscopic frontal sinusotomy, while the other 15 patients (18 sides) received endoscopic frontal sinusotomy only. Postoperatively all cases were followed up to evaluate the efficacy. RESULT: The ostia of frontal sinus were successfully opened in the group of patients received endoscopic minitrephination combined with endoscopic frontal sinusotomy without any complications. In the endoscopic frontal sinusotomy only group, three cases of complications were observed, one with the injury of anterior ethmoidal artery and the other two with the injury of papyraceous lamina. After 10 to 24 months of follow up postoperatively, the symptoms were relieved in all cases without recurrence. The combined surgery group with endoscopic minitrephination showed an endoscopic frontal sinus patency rate of 85%, and the endoscopic frontal sinusotomy only group exhibited an endoscopic frontal sinus patency rate of 83%. CONCLUSION: Endoscopic minitrephination combined with endoscopic frontal sinusotomy is a simple, convenient, safe and effective method for management of complex chronic frontal sinusitis.