Unsupervised and quantitative intestinal ischemia detection using conditional adversarial network in multimodal optical imaging

Purpose

Intraoperative evaluation of bowel perfusion is currently dependent upon subjective assessment. Thus, quantitative and objective methods of bowel viability in intestinal anastomosis are scarce. To address this clinical need, a conditional adversarial network is used to analyze the data from laser speckle contrast imaging (LSCI) paired with a visible-light camera to identify abnormal tissue perfusion regions.

Approach

Our vision platform was based on a dual-modality bench-top imaging system with red-green-blue (RGB) and dye-free LSCI channels. Swine model studies were conducted to collect data on bowel mesenteric vascular structures with normal/abnormal microvascular perfusion to construct the control or experimental group. Subsequently, a deep-learning model based on a conditional generative adversarial network (cGAN) was utilized to perform dual-modality image alignment and learn the distribution of normal datasets for training. Thereafter, abnormal datasets were fed into the predictive model for testing. Ischemic bowel regions could be detected by monitoring the erroneous reconstruction from the latent space. The main advantage is that it is unsupervised and does not require subjective manual annotations. Compared with the conventional qualitative LSCI technique, it provides well-defined segmentation results for different levels of ischemia.

Results

We demonstrated that our model could accurately segment the ischemic intestine images, with a Dice coefficient and accuracy of 90.77% and 93.06%, respectively, in 2560 RGB/LSCI image pairs. The ground truth was labeled by multiple and independent estimations, combining the surgeons' annotations with fastest gradient descent in suspicious areas of vascular images. The total processing time was 0.05 s for an image size of 256 × 256 .

Conclusions

The proposed cGAN can provide pixel-wise and dye-free quantitative analysis of intestinal perfusion, which is an ideal supplement to the traditional LSCI technique. It has potential to help surgeons increase the accuracy of intraoperative diagnosis and improve clinical outcomes of mesenteric ischemia and other gastrointestinal surgeries.

Tumor Apolipoprotein E is a key checkpoint blocking anti-tumor immunity in mouse melanoma

Immunotherapy is a key modality in the treatment of cancer, but many tumors remain immune resistant. The classic mouse model of B16-F10 melanoma is immune resistant even in the face of checkpoint inhibition. Apolipoprotein E (apoE), a known immune suppressant is strikingly elevated in many human tumors, but its role in cancer immunology is not defined. We investigated the role of apoE in the immune micro-environment using a mouse melanoma model. We demonstrate that ApoE is -highly expressed in wild-type B16-F10 melanoma and serum levels progressively increase as tumors grow. The conditioned media from wild type ApoE secreting melanoma cells suppress T-cell activation in vitro while this suppressive effect is absent in conditioned media from ApoE knock out tumor cells. Mechanistically, apoE induces IL-10 secreting dendritic cells and stimulates T-cell apoptosis and arrest partially via the lrp8 receptor. Ablating ApoE in mice inoculated with tumor cells enabled tumor cell rejection and was associated with induction of immune pathway activation and immune cell infiltration. Tumor secreted apoE appears to be a potent immune cell checkpoint and targeting apoE is associated with enhanced tumor immunity in the mouse melanoma model.

Telehealth Delivery of Outpatient Pediatric Surgical Care in Hawai'i: An Opportunity Analysis

In the state of Hawai'i, nearly all pediatric surgical care is delivered on the main island of O'ahu at the state's primary tertiary children's hospital. Outpatient clinic visits require patients and families to travel to O'ahu. The direct and opportunity costs of this can be significant. The objective of this study was to characterize potential telehealth candidates to estimate the opportunity for telehealth delivery of outpatient pediatric surgical care. A retrospective chart review including all patients transported from neighbor islands for outpatient consultation with a pediatric surgeon on O'ahu over a 4-year period was performed. Each patient visit was examined to determine if the visit was eligible for telehealth services using stringent criteria. Direct, insurance-based costs of the travel necessary were then determined. Demographic data was used to characterize the patients potentially affected. A total of 1081 neighbor island patients were seen in the pediatric surgery clinic over 4 years. Thirty-one percent of these patients met criteria as candidates for telehealth visits. The majority of patients came from Hawai'i and Maui. Most patients were identified as Native Hawaiian or Asian. The average cost per trip was $112.53 per person, leading to a potential direct cost savings of $37,697 over 4 years. Over 30% of outpatient pediatric surgical encounters met stringent criteria as candidates for telehealth delivery of care. Given the significant number of patients that met our criteria, we believe there is an opportunity for direct, travel-based cost savings with the implementation of telehealth delivery of outpatient pediatric surgical care in Hawai'i.

Early perioperative complication rates and subsidence with the Tribute® short cementless, tapered stem in primary total hip arthroplasty

This study examined early perioperative complications and subsidence following total hip arthroplasty (THA) with a short femoral stem. A retrospective review of 207 consecutive patients (247 hips) having undergone THA via the direct anterior approach produced only six perioperative complications: two intraoperative fractures, three perioperative femur fractures and one dislocation. Subsidence greater than 5 mm was observed in four hips but subsidence did not progress greater than 3 mm at the latest follow-up. Based on these results, cementless THA though the direct anterior approach with a short femoral stem provides a clinical and radiographic advantage while maintaining low complication rates.

Perioperative Complications Following One-Stage Bilateral and Unilateral Total Hip Arthroplasty via Direct Anterior Approach

Background A single stage bilateral total hip arthroplasty utilizing the direct anterior approach has been reported to have a similar incidence of perioperative complications as unilateral total hip arthroplasty.  However, previous studies have included various surgeons with differences in contraindications, protocol, technique and/or experience. Questions/Purposes The purpose of this retrospective review was to compare perioperative outcomes in single-stage bilateral and unilateral total hip arthroplasties via the direct anterior approach performed by a single, fellowship trained, high volume arthroplasty surgeon. Methods A retrospective review was completed on consecutive single-stage bilateral total hip arthroplasties performed between 2009 and 2017 and compared to consecutive unilateral total hip arthroplasties performed between 2014 and 2016.  Perioperative data and complications occurring within 90 days were collected for all included patients.  Student t-tests were performed to detect differences between bilateral and unilateral surgical variables. Results A total of 349 patients (531 hips) were included, consisting of 182 BTHA patients (364 hips) and 167 unilateral THA patients. Patients undergoing unilateral THA had significantly lower operating time, shorter length of stay, lower estimated blood loss, lower rate of transfusions and higher rate of home discharge compared to BTHA (p<0.001). Complications were present in four unilateral THA patients, three requiring revision, and nine BTHA patients, three requiring revision. Conclusions There was no difference in complications, as well as no perioperative mortalities or systemic complications, within 90 days following surgery between unilateral and bilateral patients.  Based on these results, single-stage DAA BTHA is a safe procedure to perform, and did not appear to result in higher rates of complications when compared to patients receiving a DAA unilateral THA.

Filter-free wavelength converter using Sagnac loop and delayed interferometer

A filter-free fiber-XPM-based wavelength converter is proposed and experimentally demonstrated without conventional bandpass optical filters used to filter out the converted signal. The converter is constructed with a propagation-diversity Sagnac loop to separate a converted signal from a pump signal and a delayed interferometer to covert the XPM signal into intensity modulation. We show that 10-Gbit/s input signals are successfully converted to signals with allotted wavelengths by our proposed scheme.

Provider-reported illness and absence due to illness among children attending child-care homes and centers in San Diego, Calif

PURPOSE

To compare the incidence of provider-reported illness and absence due to illness among children attending small child-care homes, large child-care homes, and child care centers in a large metropolitan area.

METHODS

From July 6, 1992, through January 28, 1994, we collected information from child-care providers on illness and absence due to illness at 64 small and 58 large child-care homes and 41 child-care centers. This included 113 446 child-weeks of information on 5360 children.

RESULTS

Providers reported 14 474 illness episodes (6.6 episodes per child-year) and 8593 days of absence due to illness (3.9 days per child-year). The incidence of illness episodes was greatest in children who were younger than 1 year, white, or enrolled in small child-care homes. The incidence of absence due to illness was greatest in children who were 1 year of age, Hispanic, or enrolled in child-care centers. Respiratory symptoms were most commonly associated with illness episodes and absence due to illness.

CONCLUSIONS

Children in child-care homes had a greater incidence of provider-reported illness than did those in centers. This risk varied by the type of facility and was greatest in small child-care homes. The increased risk for absence due to illness among children in child-care centers reflects exclusion and attendance patterns. It may be possible to reduce the incidence of absence due to illness and subsequent economic impact of child-care-associated illness by educating providers on exclusion guidelines.

Wavelength-shift-free spectral inversion with an optical parametric loop mirror

A spectral-inversion technique with no wavelength shift is presented that utilizes a novel four-wave mixing (FWM) scheme named the optical parametric loop mirror. This scheme eliminates both the input signal wave and the nondegenerate pump waves from the FWM wave generated at the signal wavelength. The compensation of waveform distortion caused by fiber chromatic dispersion is successfully demonstrated by the proposed method.

Optical parametric loop mirror

A novel configuration for four-wave mixing (FWM) is proposed that offers the remarkable feature of inherently separating the FWM wave from the input pump and signal waves and suppressing their background amplified stimulated emission without optical filtering. In the proposed configuration, an optical parametric loop mirror, two counterpropagating FWM waves generated in a Sagnac interferometer interfere with a relative phase difference that is introduced deliberately. FWM frequency-conversion experiments in a polarization-maintaining fiber achieved more than 35 dB of input-wave suppression against the FWM wave.

Optical homodyne detection with an injection-locked Er-doped-fiber ring laser

Optical homodyne detection is demonstrated with an injection-locked Er-doped-fiber ring laser. A 3-MHz phase-modulated optical signal is successfully demodulated.

Temporal coherence characteristics of InGaAsP laser diode with single-longitudinal-mode oscillation

Temporal coherence characteristics of the InGaAsP laser diode in the single longitudinal mode are measured using an unbalanced Michelson interferometer. It is demonstrated that the coherence characteristics can be expressed by the sum of the Fourier transformation of a spectral fine structure, which consists of a main mode and two adjacent submodes. These submodes cause the coherence length to be shorter than would be expected if direct line-width measurements were made.

Semiconductor laser to single-mode fiber coupler

Promising results of various coupling experiments between laser diodes and single-mode fibers to determine the optimum coupling method are reported. The cylindrical lens method is shown to be most efficient, with a coupling loss of 1.8 dB under optimum alignment conditions. More than -2 dB coupling efficiency is attained with a cylindrical lens whose radius is less than 8 microm. The laser to fiber coupling characteristics are estimated by Gaussian beam approximation. The optimum radius of a cylindrical lens, which gives maximum coupling efficiency, is derived by theoretical calculation, using the ray matrix method. The cylindrical lens alignment tolerance is also shown theoretically and experimentally.

Optical fiber (800-Mbit/sec) transmission experiment at 1.05 microm

An 800-Mbit/sec optical fiber transmission experiment at the 1.05-microm wavelength is reported. Single frequency output of a LiNdP(4)O(12) laser is modulated with a guided-wave LiNbO(3) modulator in an NRZ code and is transmitted through 4-km long single-mode fibers. The minimum receiving level is -30 dBm using a Ge avalanche photodiode. It is shown that, since the repeater spacing is limited by loss rather than dispersion in the present system configuration, a more than 10-km repeater spacing seems to be feasible. Distinctive features and problems associated with the system and constituent devices are discussed.

Birefringent Branching Filters for Wideband Optical FDM Communications

Optical branching filters consisting of birefringent filters for combining and splitting eight optical channels are studied in detail both theoretically and experimentally. Multisegment structures were used in the channel-splitting filter to suppress the crosstalk from other channels. The crosstalk of -15.5 dB was realized for a signal bandwidth B(in) equal to 67.5% of the channel separation. Discussions on the pulse response of the filter system, effects of nonzero extinction ratio, and influences of the filter frequency detuning are included.