Characterization Of Tissue Properties Research Articles

Radiomic Features from Post-Operative 18F-FDG PET/CT and CT Imaging Associated with Locally Recurrent Rectal Cancer: Preliminary Findings

Locally Recurrent Rectal Cancer (LRRC) remains a major clinical concern; it rapidly invades pelvic organs and nerve roots, causing severe symptoms. Curative-intent salvage therapy offers the only potential for cure but it has a higher chance of success when LRRC is diagnosed at an early stage. Imaging diagnosis of LRRC is very challenging due to fibrosis and inflammatory pelvic tissue, which can mislead even the most expert reader. This study exploited a radiomic analysis to enrich, through quantitative features, the characterization of tissue properties, thus favoring an accurate detection of LRRC by Computed Tomography (CT) and 18F-FDG-Positron Emission Tomography/CT (PET/CT). Of 563 eligible patients undergoing radical resection (R0) of primary RC, 57 patients with suspected LRRC were included, 33 of which were histologically confirmed. After manually segmenting suspected LRRC in CT and PET/CT, 144 Radiomic Features (RFs) were generated, and RFs were investigated for univariate significant discriminations (Wilcoxon rank-sum test, p < 0.050) of LRRC from NO LRRC. Five RFs in PET/CT (p < 0.017) and two in CT (p < 0.022) enabled, individually, a clear distinction of the groups, and one RF was shared by PET/CT and CT. As well as confirming the potential role of radiomics to advance LRRC diagnosis, the aforementioned shared RF describes LRRC as tissues having high local inhomogeneity due to the evolving tissue's properties.

Harmonic wideband simultaneous dual-frequency MR Elastography.

Magnetic resonance elastography (MRE) is used to non-invasively quantify viscoelastic properties of tissues based on the measurement of propagation characteristics of shear waves. Because some of these viscoelastic parameters show a frequency dependence, multifrequency analysis allows us to measure the wave propagation dispersion, leading to a better characterization of tissue properties. Conventionally, motion encoding gradients (MEGs) oscillating at the same frequency as the mechanical excitation encode motion. Hence, multifrequency data is usually obtained by sequentially repeating monochromatic wave excitations experiments at different frequencies. The result is that the total acquisition time is multiplied by a factor corresponding to the number of repetitions of monofrequency experiments, which is a major limitation of multifrequency MRE. In order to make it more accessible, a novel single-shot harmonic wideband dual-frequency MRE method is proposed. Two superposed shear waves of different frequencies are simultaneously generated and propagate in a sample. Trapezoidal oscillating MEGs are used to encode mechanical vibrations having frequencies that are an odd multiple of the MEG frequency. The number of phase offsets is optimized to reduce the acquisition time. For this purpose, a sampling method not respecting the Shannon theorem is used to produce a controlled temporal aliasing that allows us to encode both frequencies without any additional examination time. Phantom experiments were run to compare conventional monofrequency MRE with the single-shot dual-frequency MRE method and showed excellent agreement between the reconstructed shear storage moduli G'. In addition, dual-frequency MRE yielded an increased signal-to-noise ratio compared with conventional monofrequency MRE acquisitions when encoding the high frequency component. The novel proposed multifrequency MRE method could be applied to simultaneously acquire more than two frequency components, reducing examination time. Further studies are needed to confirm its applicability in preclinical and clinical models.

Characterization of tissue properties in epidural needle insertion on human specimen and synthetic materials

The force experienced while inserting an 18-gauge Tuohy needle into the epidural space or dura is one of only two feedback components perceived by an anaesthesiologist to deduce the needle tip position in a patient's spine. To the best of the authors knowledge, no x-ray validated measurements of these forces are currently available to the public. A needle insertion force recording during an automated insertion of an 18-gauge Tuohy needle into human vertebral segments of four female donors was conducted. During the measurements, x-ray images were recorded simultaneously. The force peaks due to the penetration of the ligamentum supraspinale and ligamentum flavum were measured and compared to the measurements of an artificial patient phantom for a hybrid patient simulator. Based on these force peaks and the slope of the ligamentum interspinale, a mathematical model was developed. The model parameters were used to compare human specimens and artificial patient phantom haptics. The force peaks for the ligamenta supraspinale and flavum were 7.55 ± 3.63 N and 15.18 ± 5.71 N, respectively. No significant differences were found between the patient phantom and the human specimens for the force peaks and four of six physical model parameters. The patient phantom mimics the same resistive force against the insertion of an 18-gauge Tuohy needle. However, there was a highly significant (p < 0.001, effsize = 0.949 and p < 0.001, effsize = 0.896) statistical difference observed in the insertion depth where the force peaks of the ligamenta supraspinale and flavum were detected between the measurements on the human specimens and the patient phantom. Within this work, biomechanical evidence was identified for the needle insertion force into human specimens. The comparison of the measured values of the human vertebral segments and the artificial patient phantom showed promising results.

Flexible Vesiculovasoscopy Using a Microoptical System in a Human Cadaver Model: An Experimental Approach for Atraumatic Endoscopy of the Seminal Tract.

The most common pathologies of the seminal tract are persistent hematospermia, seminal vesicle stones, and seminal duct obstruction. Endoscopic diagnostic work-up of the seminal tract is impeded by complex anatomy and lack of technical equipment. To date, there is no standardized endoscopic approach. The purpose of this study was to investigate the applicability and feasibility of a flexible microoptical device for atraumatic endoscopy of the seminal tract in a male human cadaver. The transurethral endoscopic examination was performed on a male cadaver. No premortal interventions or diseases of the genitourinary tract had been reported. The seminal orifice was identified via cystoscopy and accessed by the Seldinger technique using a hydrophilic guidewire and ureteral catheter. Retrograde endoscopic inspection of the distal seminal tract was performed using a miniaturized flexible endoscope. An antegrade endoscopic inspection of the seminal tract was carried out via high scrotal access to the vas deferens. Structures of the seminal tract, such as the ejaculatory duct, seminal vesicles, and distal portion of the ductus deferentes, were visualized using the miniaturized endoscope. Image quality allowed identification of anatomical structures and characterization of tissue properties. The technical limitations we observed involved the system's maneuverability. Initial results of this novel endoscopic approach to the seminal tract using a flexible microoptical system are encouraging. However, considerable anatomical limitations of the targeted organs necessitate further refinements of the technical equipment. This approach might improve diagnostics and treatment of genitourinary diseases. Future surgical techniques may include intraseminal laser therapy or endoocclusion to monitor fertility in men.

Flexible Vesiculo-Vasoscopy Using a Micro-Optical System in a Human Cadaver Model: An Experimental Approach for Atraumatic Endoscopy of the Seminal Tract

Objectives: The most common pathologies of the seminal tract are persistent hematospermia, seminal vesicle stones, and seminal duct obstruction. Endoscopic diagnostic work-up of the seminal tract is impeded by complex anatomy and lack of technical equipment. To date, there is no standardized endoscopic approach. Purpose of this study was to investigate the applicability and feasibility of a flexible micro-optical device for atraumatic endoscopy of the seminal tract in a human male cadaver. Materials and Methods: The transurethral endoscopic examination was performed on a male cadaver. No premortal interventions or diseases of the genitourinary tract had been reported. The seminal orifice was identified through cystoscopy and accessed by Seldinger technique using a hydrophilic guidewire and ureteral catheter. Retrograde endoscopic inspection of the distal seminal tract was performed using a miniaturized flexible endoscope. An antegrade endoscopical inspection of the seminal tract was carried out through high scrotal access to the vas deferens. Results: Structures of the seminal tract such as the ejaculatory duct, seminal vesicles, and distal portion of the ductus deferentes were observed using the miniaturized endoscope. Image quality allowed identification of anatomical structures and characterization of tissue properties. The technical limitations we observed involved the system's maneuverability. Conclusions: Initial results of this novel endoscopic approach to the seminal tract using a flexible micro-optical system are encouraging. However, considerable anatomical limitations of the targeted organs necessitate further refinements of the technical equipment. This approach might improve diagnostics and treatment of genitourinary diseases. Future surgical techniques may include intraseminal laser therapy or endo-occlusion to monitor fertility in men. Acknowledgment: We would like to thank Schoelly Fiberoptics GmbH, Denzlingen, Germany, for providing the instruments and technical support for this study. The cadaver (body donor) was provided by the Institute for Anatomy, Medical Faculty, Justus-Liebig-University, Giessen. Institutional funding (Medical Faculty of the University of Freiburg) and nonfinancial industrial funding (providing the instruments and technical support for the study) were by Schoelly Fiberoptic GmbH, Denzlingen, Germany. D.S., M.M., S.H., F.A., and W.W. have no conflicts of interest or financial ties to disclose. M.S. consultant contract with Schoelly Fiberoptics GmbH, Denzlingen, Germany, and NeoTract, Inc., Pleasanton, USA. T.D. Lilly Deutschland GmbH (stocks/stock options, employee: through family member), Pfizer (speaker honorarium), Takeda Pharma GmbH (speaker honorarium), AMS Deutschland (speaker honorarium), Jenapharm GmbH (speaker honorarium), Glenwood (speaker honorarium), Cheplapharm Arzneimittel GmbH (consultant), Marpinion GmbH (Advisory Board member, consultant), Advance Medical S.A., Barcelona (ESP) (Consultatnt, Reviewer). A.M. consultant contract with Schoelly Fiberoptics GmbH, Denzlingen, Germany. Runtime of video: 6 mins 10 secs

ChemInform Abstract: Magnetic Resonance of Porous Media (MRPM). A Perspective

AbstractReview: 112 refs.

Technique for handling wave propagation specific effects in biological tissue: Mapping of the photon transport equation to Maxwell’s equations

A novel algorithm for mapping the photon transport equation (PTE) to Maxwell's equations is presented. Owing to its accuracy, wave propagation through biological tissue is modeled using the PTE. The mapping of the PTE to Maxwell's equations is required to model wave propagation through foreign structures implanted in biological tissue for sensing and characterization of tissue properties. The PTE solves for only the magnitude of the intensity but Maxwell's equations require the phase information as well. However, it is possible to construct the phase information approximately by solving the transport of intensity equation (TIE) using the full multigrid algorithm.