Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Genomic–transcriptomic evolution in lung cancer and metastasis

Intratumour heterogeneity (ITH) fuels lung cancer evolution, which leads to immune evasion and resistance to therapy. Here, using paired whole-exome and RNA sequencing data, we investigate intratumour transcriptomic diversity in 354 non-small cell lung cancer tumours from 347 out of the first 421 patients prospectively recruited into the TRACERx study. Analyses of 947 tumour regions, representing both primary and metastatic disease, alongside 96 tumour-adjacent normal tissue samples implicate the transcriptome as a major source of phenotypic variation. Gene expression levels and ITH relate to patterns of positive and negative selection during tumour evolution. We observe frequent copy number-independent allele-specific expression that is linked to epigenomic dysfunction. Allele-specific expression can also result in genomic–transcriptomic parallel evolution, which converges on cancer gene disruption. We extract signatures of RNA single-base substitutions and link their aetiology to the activity of the RNA-editing enzymes ADAR and APOBEC3A, thereby revealing otherwise undetected ongoing APOBEC activity in tumours. Characterizing the transcriptomes of primary–metastatic tumour pairs, we combine multiple machine-learning approaches that leverage genomic and transcriptomic variables to link metastasis-seeding potential to the evolutionary context of mutations and increased proliferation within primary tumour regions. These results highlight the interplay between the genome and transcriptome in influencing ITH, lung cancer evolution and metastasis

Hybrid clutter rejection technique for improved microwave head imaging

The accuracy of microwave head imaging is adversely affected by strong clutters that can completely mask the target response. To that end, different clutter removal techniques are modified for multistatic frequency-based imaging. It is shown that some deficiencies of those methods in time domain, such as time overlapping, can be alleviated when they are modified for use in frequency domain. Based on the explored performance of different methods in the frequency domain, a hybrid technique, which combines the benefits of average subtraction and entropy-based filtering methods, is proposed. In this method, the average value of the multistatic scattered signals is subtracted from them at each frequency sample to remove late-stage clutters, whereas an entropy-based method is applied to mitigate early-stage strong clutters. The proposed technique is verified in realistic environments using simulations and experiments. The utilized system for verification is 1.1-3.2 GHz frequency-domain multistatic with an eight-element antenna array, and compact microwave transceiver. The simulations are performed on MRI-derived head model, whereas the experiments are done on realistic artificial head phantom. The obtained results from different locations and sizes of emulated brain injuries confirm the effectiveness of the proposed method in producing high quality images of the head after mitigating the clutter

Estimation of frequency dispersive complex permittivity seen by each antenna for enhanced multistatic radar medical imaging

Radar-based microwave imaging requires the effective dielectric properties of the imaged object as a priori information. A technique to determine the effective complex permittivity seen by each imaging antenna across the used frequency band of a multistatic imaging domain is presented. The method uses spatial statistical techniques to model the complex permittivity of the imaging domain as a function of scattering parameters. The proposed method does not require any predefined gap between the antennas and the imaged object, nor does it need the imaged object to be centered within the imaging domain. Also, the method does not need to know boundaries of the imaged object. The proposed method is tested via simulations and experiments using a multistatic human torso imaging system. The collected data across the band 0.65-1.75 GHz using twelve antennas around the human torso are processed to generate accurate images. The results demonstrate significant improvements in image quality and detection accuracy compared to conventional average-permittivity methods. The efficacy of the proposed method is verified experimentally in detecting an early case of lung cancer in a human torso phantom

Multistatic biomedical microwave imaging using spatial interpolator for extended virtual antenna array

The accuracy of multistatic microwave imaging is highly dependent on the number of antennas used for data acquisition. The antenna size, available space for antennas, mutual coupling between antennas and acceptable hardware complexity (switching and processing) limit the usable number of antennas. To address this issue, the concept of virtual array is utilized. In this regard, a spatial interpolator is designed to predict the received signals at the location of the virtual elements using the recorded signals by a limited number of real antennas. Consequently, a frequency-based imaging algorithm is used to process the virtual-array signals and produce clear images that enable accurate detection. The presented method is tested via simulations and experiments using a multistatic-radar-based head imaging system operating using the band 1.1-3.2 GHz. The data recorded by eight antennas around the head is used to form equivalent data from an extended virtual array of 12, 16, and 32 elements. Using quantitative metrics, it is shown that the constructed images from the extended virtual array are more accurate than the images created only from the real antennas. It is also shown that a virtual array that has twice the number of elements of the real array, which meet the minimum limit of degree-of-freedom of the problem, is enough to generate an accurate image with optimized computational resources. In comparison with existing correlation-based methods, the presented approach provides more accurate images

Fast frequency-based multistatic microwave imaging algorithm with application to brain injury detection

A multistatic microwave imaging technique is presented for fast diagnosis of medical emergencies pertaining to brain injuries. The frequency-based imaging method utilizes Bessel functions to estimate the scattered power intensity inside the imaged region from measured multistatic scattered signals outside the imaged region in a quasi-real-time manner. A theory is used to prove that the relation between the scattered fields outside the imaged object (the head) and the internal scattering profile follows the first order of first type Bessel function. To reconstruct the internal scattered power intensity accurately, the average-trace subtraction method is used to remove the skin reflections and clutters. The presented algorithm is verified using realistic numerical simulations and experimental measurements, which are performed using a radar-based head imaging system that includes an antenna array containing eight elements, microwave transceiver, and switching network. To emulate different brain injuries, realistic head phantoms are utilized. The obtained results using frequency steps that meet Nyquist criterion confirm the reliability of the proposed method in the successful detection of different sizes and locations of injuries inside the head phantom in a fast and consistent way. In comparison with existing multistatic time-domain methods, the presented approach is faster and more accurate

Pattern reconfigurable wideband loop antenna for thorax imaging

A unidirectional loop antenna that can achieve wideband pattern re-configurability from -40 to +40 degrees in azimuth plane is presented. The antenna is designed to fulfill the multi-slice (level) scanning requirements of electromagnetic imaging (EMI) systems for thorax imaging. To overcome the need for positioning of several antenna-arrays, and hence eliminate the mutual coupling related complications, a square-loop antenna with reconfigurable pattern is designed. To create a unidirectional radiation, the loop is loaded with capacitive gaps, which convert its radiation mechanism to that of two virtual dipole arrays with quadrature phase excitation. By utilizing this feature, the location of the gaps are varied on the loop’s structure to form virtual dipole arrays in different directions, thus rotating the radiation pattern without physically moving the structure of the antenna. As a proof of concept, six gaps were created on the loop and each gap is loaded with a PIN diode to electronically switch between the positions of the designed gaps, thus enabling changing the radiation direction. The proposed antenna can achieve a compact size of 0.32λ×0.32λ×0.002λ (λ is the wavelength of the lowest resonance of the antenna) and a wide fractional bandwidth of 32% at 0.8-1.15 GHz, with a peak gain and front-to-back-ratio of 2.1 dBi and 8 dB, respectively. The antenna is successfully tested on a thorax imaging platform to detect small volume of water (5 mL) inside lungs as an emulation of early pulmonary edema

Three-dimensional electromagnetic torso imaging using reconfigurable antennas

Thoracic disorders, such as lung and liver cancer, and congestive heart failure are the major causes of chronic morbidity and mortality in the world. Electromagnetic imaging (EMI) is an emerging technique to diagnose those abnormalities in a fast and cost-effective way. In that regard, a portable human torso scanner, including a pattern reconfigurable metasurface antenna as a data acquisition device and a three-dimensional backpropagation method as an imaging algorithm are proposed. The utilized antenna consists of three rectangular microstrip-fed slot radiators to scan the torso in the bandwidth of 0.8-1.15 GHz. The image construction algorithm is then utilized to detect the locations of contrasts in dielectric properties of tissues, which are due to abnormal tissue. To that end, the electromagnetic power intensity inside the three-dimensional imaging region is estimated by combining a backpropagation technique with an interpolation method. The proposed method is successfully tested in measurements by detecting 20 mL accumulated water inside lungs of a human torso phantom as an emulation of pulmonary edema. The obtained results show that the proposed technique enables the accurate detection and localization of the target

Pattern Reconfigurable Metasurface Antenna for Electromagnetic Torso Imaging

A pattern reconfigurable metasurface antenna for electromagnetic torso imaging system operating at the ultra-high frequency (UHF) band is presented. To meet the electromagnetic torso imaging requirements, the antenna can scan the human chest with steerable unidirectional radiation patterns. The designed antenna consists of three rectangular microstrip-fed slot radiators illuminating a metasurface layer with 7 × 5 unit cells to cover the whole chest. Six PIN diodes are used to switch the radiating slots creating different beams. The unit cell dimensions are . × . and the antenna has a low profile of . × . × . ( is the wavelength of the lowest operating frequency of the antenna). The antenna creates three distinct beams with a peak gain of 8 dBi at 1 GHz and 2 dBi gain variations across different beams over its measured wide operating frequency bandwidth of 27% at 0.8-1.05 GHz. A complete electromagnetic torso imaging system, which utilizes the designed antenna, is built and successfully tested to detect 20 mL of fluid (water) inside the torso, and thus differentiate between healthy and unhealthy cases

Three-Dimensional Electromagnetic Torso Scanner

A three-dimensional (3D) electromagnetic torso scanner system is presented. This system aims at providing a complimentary/auxiliary imaging modality to supplement conventional imaging devices, e.g., ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI), for pathologies in the chest and upper abdomen such as pulmonary abscess, fatty liver disease and renal cancer. The system is comprised of an array of 14 resonance-based reflector (RBR) antennas that operate from 0.83 to 1.9 GHz and are located on a movable flange. The system is able to scan different regions of the chest and upper abdomen by mechanically moving the antenna array to different positions along the long axis of the thorax with an accuracy of about 1 mm at each step. To verify the capability of the system, a three-dimensional imaging algorithm is proposed. This algorithm utilizes a fast frequency-based microwave imaging method in conjunction with a slice interpolation technique to generate three-dimensional images. To validate the system, pulmonary abscess was simulated within an artificial torso phantom. This was achieved by injecting an arbitrary amount of fluid (e.g., 30 mL of water), into the lungs regions of the torso phantom. The system could reliably and reproducibly determine the location and volume of the embedded target