Perforators Detected in Computed Tomography Angiography for Anterolateral Thigh Free Flap: Am I the Only One Who Feels Inaccurate?

BACKGROUND: The number, location, and pattern of perforators in anterolateral thigh(ALT) flap vary and predicting them preoperatively will aid in reconstructing complex head and neck defects. This article suggests guidelines for utilizing CTA imagery to predict perforators of ALT-free flaps. METHODS: We retrospectively analyzed 53 Korean patients who underwent reconstruction with ALT flap in our department from March 2021 to July 2022. The location, course, origin, and pedicle lengths predicted in CTA and confirmed in the operation field were recorded and compared. RESULTS: Among the 85 intraoperatively-found perforators, 79 were also identified in CTA. Six perforators unidentified in CTA were newly found intraoperatively. The positive predictive value of CTA for the perforator was 100%, with a sensitivity of 79/85 = 92.9%. Of the 79 perforators depicted by the CTA for the flap, CTA and intraoperative findings for the course were consistent in 52 cases, a 9.6 mm median discrepancy being noted between the actual location and CTA. CONCLUSIONS: The overall pattern or location of perforation was not significantly different between the two, although some differences were observed. It is suggested that the addition of Doppler imaging, in conjunction with CTA, can aid in perforator detection and help minimize such discrepancies.

Robot-assisted radial forearm free flap harvesting: a propensity score-matched case-control study.

Although some surgeons prefer anterolateral thigh and latissimus dorsi flap for soft tissue reconstruction in the head and neck area because it minimizes donor site complications, the radial forearm flap remains the workhorse for soft tissue reconstruction due to its reliability. To reduce donor site morbidity, the authors developed a novel technique for radial forearm flap harvesting using a robotic device. 42 radial forearm free flap reconstruction cases were studied, consisting of 31 conventional and 11 robot-assisted cases. 1:1 propensity score matching was done according to age, sex, previous and postoperative radiation therapy history and method used for vein anastomosis. There was no significant difference in flap outcome, which was 100% vitality in the robot-assisted group and 90.9% vitality in the conventional group. The robot-assisted group showed significantly longer mean harvesting time than did the conventional group, being 107.2 min and 67.0 min, respectively. Robot-assisted radial forearm flap harvesting can reduce donor site complications by minimizing incision. When more surgical experience is gained under appropriate case selection, we expect our robot-assisted method will yield a harvesting time similar to that of the conventional method and thus become more reliable and feasible.

Comparing Free-Flap Reconstruction After Robot-Assisted Neck Dissection via a Retroauricular Approach and a Traditional Transcervical Approach: Single-Surgeon Experiences of 90 Consecutive Cases.

BACKGROUND: Predominant traditional approaches for most patients who have advanced-stage oral cancer with transcervical incision lines left irreversible scars. To address this, surgeons have continuously refined minimally invasive surgery (MIS) techniques, including robot-assisted neck surgeries. This article introduces and discusses the feasibility, versatility, and availability of free-flap reconstruction via the retroauricular approach (RA), considered difficult to date. METHODS: This study retrospectively analyzed 90 consecutive patients who had free-flap reconstruction performed by a single surgeon (D.K.) in the Department of Oral and Maxillofacial Surgery, Yonsei University, from March 2021 to April 2022. The type of defects and flaps, hospitalization days, total operation time, and type of vessels and anastomoses were compared statistically. RESULTS: The type of vessels used did not differ between the RA and the transcervical approach (TA) groups, nor in duration of hospital stays. Likewise, the total reconstruction time did not differ significantly between the TA group (240 min) and the RA group (245 min) (p = 0.756). However, the total operation time was about 1 h less in the TA group, a statistically significant difference (TA group [593 ± 152 min] vs. RA group [655 ± 117 min]; p = 0.044). All flaps were successful in the RA group, whereas one flap in the TA group led to a total loss (TA group [98.3%] vs. RA group [100.0%]; p = 1.000). CONCLUSIONS: Even for patients with advanced oral cancer who require massive tumor ablation, it is feasible to obtain an aesthetic and functional surgical outcome by performing free-flap reconstruction via the retroauricular approach.

Risk Factors of Microscopically Tumor-Free Surgical Margins for Recurrence and Survival of Oral Squamous Cell Carcinoma Patients.

Objectives: The concept of adequate surgical margins remains controversial in oral squamous cell carcinoma (OSCC) surgery. This study aimed to identify surgical margin-related indicators that might impact recurrence and survival of OSCC patients. Materials and Methods: Histopathological examination was performed using hematoxylin-eosin-stained surgical margin tissue sections in 235 OSCC patients. Axin2 and Snail expression at the surgical margin was detected by immunohistochemistry. The impact of the Axin2-Snail cascade on tumorigenesis of the immortalized human oral keratinocyte (IHOK) line was investigated in vivo. Results: The width and dysplasia of surgical margins were not significantly associated with the outcome of OSCC patients. In a multivariate analysis using variable clinicopathologic factors and with Axin2 and Snail expression as cofactors, higher age (hazard ratio [HR]:1.050; P=0.047), Axin2 (HR:6.883; P=0.014), and Snail abundance (HR:5.663; P=0.009) had independent impacts on worsened overall survival. Similarly, lesion site in retromolar trigone (HR:4.077; P=0.010), upper (HR:4.332; P=0.005) and lower gingiva (HR:3.545; P=0.012), presence of extranodal extension (HR:9.967; P<0.001), perineural invasion (HR:3.627; P=0.024), and Snail abundance (HR:3.587; P<0.001) had independent impacts on worsened recurrence-free survival. Furthermore, Axin2 knockdown induced decreased Snail expression and attenuated tumorigenesis in the IHOK line. Conclusion: Histopathological examination of surgical margins may not be reliable to predict OSCC patient outcome. Molecular analysis may provide a more accurate risk assessment of surgical margins in OSCC. In particular, Axin2 and Snail are potential predictive biomarkers for the risk assessment of surgical margins in OSCC.

Risk factor analysis of dental implants in patients with irradiated head and neck cancer.

BACKGROUND: We investigated dental implant outcomes in patients who had previously received radiotherapy (RT) for head and neck malignancies. METHODS: We reviewed 90 dental implants in 27 patients who received RT for head and neck cancer and received dental implants afterwards. The cumulative implant survival rate (CISR) was calculated. In addition, the implant quality was assessed using "Health Scale for Dental Implants." RESULTS: The CISR at 3 years was 79.6%. The mean radiation dose at the implant site (Dmean ) was identified as an independent prognostic factor for implant survival. No implant failed if Dmean was less than 38 Gy. Regarding implant quality, dental implants in grafted bone and Dmean were independent risk factors. CONCLUSIONS: Dmean was identified as an independent prognostic factor for implant survival and quality. Dental implants can be safely considered when Dmean is lower than 38 Gy.

Spin-orbit torques in normal metal/Nb/ferromagnet heterostructures.

Quantifying the spin-orbit torque (SOT) efficiency with changing the layer thickness is crucial for understanding the physical background of SOT. This study investigates the Nb-thickness-dependent SOT efficiency of two types of layered heterostructures: Ta/Nb/CoFeB and Pt/Nb/CoFeB. We find that the Nb thickness dependence of the SOT efficiency in the two samples is quite different. In the Pt/Nb series, the SOT sign changes according to the thickness variation because Pt and Nb have different spin-orbit coupling signs. We observe the resulting reversal in switching polarity through current-induced SOT switching experiments. However, due to the same spin-orbit coupling signs of Ta and Nb, no such polarity reversal was observed in Ta/Nb series. Further, we extract the spin diffusion length of Nb in each heterostructure. These results provide a systematic understanding of the material- and thickness-dependent SOT characteristics.

Predictive modelling of level IIb lymph node metastasis in oral squamous cell carcinoma.

The aim of the present study was to examine the conditions, characteristics, and risk factors of level IIb lymph node metastases in oral squamous cell carcinoma and to formulate surgical criteria for level IIb lymph node dissection. We analyzed clinical and pathological records for 541 oral squamous carcinoma patients in relation to level IIb metastasis. Univariate and multivariate analyses were performed to detect risk factors for level IIb lymph node metastasis; a predictive model was built based on multivariate analysis and tested in a validation group. Univariate and multivariate analyses using the training group indicated that level IIa metastasis and Lymphovascular permeation (LVP) were two independent risk factors for level IIb lymph node metastasis. This model was built and tested in a validation group, the area under the curve being 0.697 (P < .0.001). The model's sensitivity was 66.7% and specificity was 77.4%. Nomogram incorporating validated variables was developed for level IIb metastasis prediction. Expected survival probabilites were analysed to specify significance of model's variable on patients' overall survival and recurrence. Level IIb dissection should be performed in patients with level IIa metastasis and LVP. However, thorough consideration of the oncologic safety of omitting level IIb dissection is compulsory.

Longitudinal detection of somatic mutations in saliva and plasma for the surveillance of oral squamous cell carcinomas.

PURPOSES: Although clinical and radiological examinations can be used to diagnose oral cancer, and surgical pathology remains the gold standard, these conventional methods have limitations. We evaluated the feasibility of longitudinal next-generation sequencing-based liquid biopsy for oral squamous cell carcinoma surveillance. MATERIALS AND METHODS: Eleven patients were enrolled, and plasma and saliva were collected before, and 1, 3, and 6 months after surgery. Tumor-specific mutations were selected using paired, whole-exome analyses of tumor tissues and whole blood. Genes frequently mutated in head and neck cancer were identified using the Cancer Genome Atlas (TCGA) and Catalogue of Somatic Mutations in Cancer (COSMIC) databases to design targeted deep sequencing panels. RESULTS: In five of the six patients with recurrent cancer, circulating tumor DNA (ctDNA) was detected earlier with liquid biopsy than with conventional monitoring techniques. Moreover, patients without recurrence exhibited decreased ctDNA allele frequency post-treatment. CONCLUSIONS: Longitudinal liquid biopsy of plasma and saliva may be feasible for detecting somatic mutations associated with oral squamous cell carcinomas. It might be attributable to determine early tumor recurrence through genetic analysis of ctDNA.

Appropriate follow-up period for odontogenic keratocyst: a retrospective study.

PURPOSE: The aim of this study was to conduct epidemiologic investigations on the pattern of the lesion and differences between treatment modalities in terms of recurrence by reviewing follow-up records to form a basis for planning patient follow-up visits. MATERIALS AND METHODS: In this retrospective, single-center cohort study, 266 patients diagnosed with odontogenic keratocyst between 1993 and 2013 were included. Medical records and radiographic images were analyzed for age distribution, occurrence site and size, treatment modalities, and recurrence. RESULTS: The average age at first diagnosis was 33.1 years, and the male to female ratio was 1.33:1.00. The highest rate of incidence was in the third decade followed by the fourth, second, and fifth decades. The incidence in the maxilla was 34%, and 66% in the mandible. Mandibular ramus was most commonly involved. Lesions between 3 and 6 crowns were the most common, and the rate of recurrence increased with size. Enucleation after decompression had higher rate of recurrence (35.8%) than enucleation (27.1%), but there was no statistical significance. CONCLUSION: The recurrence of odontogenic kerotocyst (OKC) was significantly associated with large size, multilocular form, and surgical procedure. A 10-year follow-up period is recommended to determine any recurrence of OKC.

Ruderman-Kittel-Kasuya-Yosida-type interfacial Dzyaloshinskii-Moriya interaction in heavy metal/ferromagnet heterostructures.

The manipulation of magnetization with interfacial modification using various spin-orbit coupling phenomena has been recently revisited due to its scientific and technological potential for next-generation memory devices. Herein, we experimentally and theoretically demonstrate the interfacial Dzyaloshinskii-Moriya interaction characteristics penetrating through a MgO dielectric layer inserted between the Pt and CoFeSiB. The inserted MgO layer seems to function as a chiral exchange interaction mediator of the interfacial Dzyaloshinskii-Moriya interaction from the heavy metal atoms to ferromagnet ones. The potential physical mechanism of the anti-symmetric exchange is based on the tunneling-like behavior of conduction electrons through the semi-conductor-like ultrathin MgO. Such behavior can be correlated with the oscillations of the indirect exchange coupling of the Ruderman-Kittel-Kasuya-Yosida type. From the theoretical demonstration, we could provide approximate estimation and show qualitative trends peculiar to the system under investigation.

Primary malignant mucosal melanoma of the maxillofacial area.

OBJECTIVES: We aimed to collect and report data from all patients who have been diagnosed with mucosal malignant melanoma to obtain the epidemiology and principles of current treatments. MATERIALS AND METHODS: Between January 2008 and December 2018, 20 patients underwent surgery or follow-up observations at Yonsei University Dental Hospital. The patients' clinical information was reviewed retrospectively. RESULTS: Seventeen of 20 patients had undergone definitive surgery, while only 6 patients received adjuvant radiotherapy or systemic therapy. Eight of 20 patients, including those that had recurrent lesions, were provided immunotherapy. The 3-year survival for all stages was 50%, with a local recurrence rate of 75% and a metastasis rate of 65%. CONCLUSION: The overall survival of patients receiving surgical treatment was longer than that of patients who did not undergo surgical resection. Eight of 20 patients received immunotherapy as the first-line regimen at our clinic, and those patients exhibited longer overall survival compared to patients in reported keynote studies.

Postoperative Concurrent Chemoradiotherapy Versus Radiotherapy Alone for Advanced Oral Cavity Cancer in the Era of Modern Radiation Techniques.

BACKGROUND/PURPOSE: Surgery followed by postoperative radiotherapy (RT) has been considered the standard treatment for oral cavity squamous cell carcinoma (OCSCC) of advanced stages or with adverse prognostic factors. In this study, we compared the outcomes in patients with OCSCC who received postoperative concurrent chemoradiotherapy (CCRT) or postoperative RT alone using modern RT techniques. METHODS: A total of 275 patients with OCSCC treated between 2002 and 2018 were retrospectively analyzed. Adverse prognostic factor was defined as extranodal extension (ENE), microscopically involved surgical margin, involvement of ≥2 lymph nodes, perineural disease, and/or lymphovascular invasion (LVI). In total, 148 patients (54%) received CCRT and 127 patients (46%) received RT alone. More patients in the CCRT group had N3 disease and stage IVB disease (46.6% vs. 10.2%, p<0.001), ENE (56.1% vs. 15.7%, p<0.001), LVI (28.4% vs. 13.4%, p=0.033). RESULTS: With a median follow-up of 40 (range, 5-203) months, there were no significant differences in the 5-year overall survival (OS) and PFS between treatment groups. In the subgroup analysis according to high risk, the concurrent use of chemotherapy showed significantly improved OS in patients with ENE (HR 0.39, p=0.003). CONCLUSION: Our retrospective study showed that postoperative CCRT group had comparable survival outcomes to those in the RT alone group for advanced OCSCC in the era of modern RT techniques and indicated that concurrent chemotherapy should be administered to patients with ENE. Prospective randomized studies for confirmation are needed.

Handheld Near-Infrared Fluorescence Imaging Device Using Modified Action Cameras for Peri-Operative Guidance of Microvascular Flap Surgery.

Indocyanine green near-infrared fluorescence (ICG-NIRF) imaging has recently come into use as a novel method in peri-operative microvascular flap assessment. However, a majority of the many commercial devices launched for clinical use lack mobility, portability, and cost-efficiency and are thus unsuitable for intra-oral applications. This study introduces a cost-effective, customized, handheld NIRF device following principles of ICG-NIRF imaging. Moreover, the novel characteristics of our prototype, considered in conjunction with a literature review highlighting the significance of fluorescence devices in microvascular surgery, point to a new generation of devices for use in microvascular flap surgery.

Effects of pre-extraction intermittent PTH administration on extraction socket healing in bisphosphonate administered ovariectomized rats.

The purpose of this study was to investigate the effect of administering intermittent parathyroid hormone (iPTH) before tooth extraction versus after tooth extraction on the risk of developing MRONJ in experimental animal model. Twenty-five ovariectomized rats received 6 weeks of bisphosphonate therapy. They were classified into 3 groups, based on the timing of the medication, as Control, Pre-PTH and Post-PTH groups. For Control group, normal saline was administered before and after tooth extraction. iPTH was administered during 4 weeks before tooth extraction for Pre-PTH group and after tooth extraction for Post-PTH group. The animals were euthanized 8 weeks after tooth extraction. Macroscopic, histological, micro-computed tomography (micro-CT), and histomorphometric examinations were conducted. The incidences of impaired healing were 11.11% both in Pre-PTH and Post-PTH groups, which was lower than the Control group (42.86%). Bone healing in the extraction socket, based on micro-CT and histomorphometry evaluations, was best in Post-PTH and worst in Control group. The Pre-PTH group showed moderate healing pattern. Despite of limitations in this study, the authors identified Pre-PTH group seems to have positive effect on extraction socket healing. With regard to timing, administering iPTH after tooth extraction was superior to applying it before tooth extraction.

Magnetic Direct-Write Skyrmion Nanolithography.

Magnetic skyrmions are stable spin textures with quasi-particle behavior and attract significant interest in fundamental and applied physics. The metastability of magnetic skyrmions at zero magnetic field is particularly important to enable, for instance, a skyrmion racetrack memory. Here, the results of the nucleation of stable skyrmions and formation of ordered skyrmion lattices by magnetic force microscopy in (Pt/CoFeSiB/W)n multilayers, exploiting the additive effect of the interfacial Dzyaloshinskii-Moriya interaction, are presented. The appropriate conditions under which skyrmion lattices are confined with a dense two-dimensional liquid phase are identified. A crucial parameter to control the skyrmion lattice characteristics and the number of scans resulting in the complete formation of a skyrmion lattice is the distance between two adjacent scanning lines of a magnetic force microscopy probe. The creation of skyrmion patterns with complex geometry is demonstrated, and the physical mechanism of direct magnetic writing of skyrmions is comprehended by micromagnetic simulations. This study shows a potential of a direct-write (maskless) skyrmion (topological) nanolithography with sub-100 nm resolution, where each skyrmion acts as a pixel in the final topological image.

Prognostic value of systemic inflammatory markers for oral cancer patients based on the 8th edition of AJCC staging system.

It has been recognized that systemic inflammatory markers (SIMs) are associated with patient survival in various types of cancer. This study aimed to determine the optimal cut-off values, and to evaluate the prognostic performance of SIMs for oral squamous cell carcinoma (OSCC) within the framework of the American Joint Committee of Cancer (AJCC) cancer staging manual, 8th edition. Records were collected for a total 291 patients who had had a peripheral blood test within 1 week prior to surgery and had undergone the surgical resection of OSCC in a single institution between 2005 and 2018. The cut-off values of SIMs were obtained, and the survival analyses for overall survival (OS) and disease-free survival (DFS) were performed. Multivariate analyses incorporating other clinicopathologic factors were performed to verify the independent risk factors for survival. The cut-off values of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were 2.23, 135.14 for OS and 2.16, 131.07 for DFS, respectively, demonstrating a significant association for OS and DFS in OSCC. AJCC pathologic regional lymph node category (pN) (P < 0.001), perineural invasion (PNI) (P < 0.001) and NLR (P < 0.001) were independent predictors for OS. Meanwhile, for DFS, AJCC pN (P = 0.018) and NLR (P = 0.015) were shown to be independent predictors. Before the curative surgery, NLR and PLR could be auxiliary parameters for OS and DFS in OSCC. And based on the 8th edition of AJCC staging system, elevated NLR will be a potential indicator of the worse OS or DFS along with pN or PNI in OSCC.

Deep Learning for Automated Detection of Cyst and Tumors of the Jaw in Panoramic Radiographs.

Patients with odontogenic cysts and tumors may have to undergo serious surgery unless the lesion is properly detected at the early stage. The purpose of this study is to evaluate the diagnostic performance of the real-time object detecting deep convolutional neural network You Only Look Once (YOLO) v2-a deep learning algorithm that can both detect and classify an object at the same time-on panoramic radiographs. In this study, 1602 lesions on panoramic radiographs taken from 2010 to 2019 at Yonsei University Dental Hospital were selected as a database. Images were classified and labeled into four categories: dentigerous cysts, odontogenic keratocyst, ameloblastoma, and no cyst. Comparative analysis among three groups (YOLO, oral and maxillofacial surgeons, and general practitioners) was done in terms of precision, recall, accuracy, and F1 score. While YOLO ranked highest among the three groups (precision = 0.707, recall = 0.680), the performance differences between the machine and clinicians were statistically insignificant. The results of this study indicate the usefulness of auto-detecting convolutional networks in certain pathology detection and thus morbidity prevention in the field of oral and maxillofacial surgery.

Prognostic Implications of Combined Imaging and Histologic Criteria in Squamous Cell Carcinoma with Mandibular Invasion.

Prognosis prediction of squamous cell carcinoma (SCC) with mandibular invasion is controversial, and a more sophisticated staging system to aid prognosis could be developed with imaging characteristics of bone invasion. Imaging-feature analysis provides practical, stratified results for survival prognosis in oral SCC (OSCC) of the mandible, and imaging advances enable more detailed tumor visualization. We retrospectively evaluated significant bone-invasion features associated with poor outcomes in mandibular OSCC to assess the predictive value of staging criteria that combined imaging features and histologic grade (combined imaging-histology (IH) grade) in 65 patients (39 men, 26 women) with mandibular SCC diagnosed from 2006 to 2016. Clinicopathologic features, including T-stage and histologic grade, and prognosis were retrieved. Tumors were classified into three types by extent of mandibular invasion on pretreatment imaging studies. Moreover, we assessed the involvement of the mandibular canal. We examined the correlation of factors associated with locoregional recurrence and overall mortality. The Harrell Concordance Index (C-index) determined prognostic performance of predictors. Nineteen (29%) patients showed locoregional recurrence and 13 (20%) died. For locoregional recurrence and mortality rates, imaging-detected mandibular canal (MC) involvement is a stronger prognostic factor for recurrence (C-index = 0.61 > 0.58) and survival (C-index = 0.58 > 0.63) than histopathologically confirmed perineural invasion, as was the IH grade, especially IH Grade 3, which was significantly associated with worse locoregional recurrence (p < 0.02). Imaging-based staging showed higher prognostic performance than T-staging (C-index = 0.57 (recurrence), 0.60 (death)), when combined with histologic grading (C-index = 0.69 for both) or used alone (C-index = 0.63 (locoregional recurrence), 0.69 (death)). Overall survival was significantly stratified by Imaging type and IH grade. Therefore, analysis of imaging features provided more specific, practical results for survival prognosis in mandibular OSCC. Imaging advances can potentially provide detailed gross views of tumor masses to facilitate development of prognostic criteria for OSCC.