Novel Techniques to Improve Precise Cell Injection

We noted recently that the injection of cells with a needle through a cystoscope in the urethral sphincter muscle of pigs failed to deposit them nearby or at the intended target position in about 50% of all animals investigated (n > 100). Increasing the chance for precise cell injection by shotgun approaches employing several circumferential injections into the sphincter muscle bears the risk of tissue injury. In this study, we developed and tested a novel needle-free technique to precisely inject cells in the urethral sphincter tissue, or other tissues, using a water-jet system. This system was designed to fit in the working channels of endoscopes and cystoscopes, allowing a wide range of minimally invasive applications. We analyze key features, including the physical parameters of the injector design, pressure ranges applicable for tissue penetration and cell injections and biochemical parameters, such as different compositions of injection media. Our results present settings that enable the high viability of cells post-injection. Lastly, the method is suitable to inject cells in the superficial tissue layer and in deeper layers, required when the submucosa or the sphincter muscle of the urethra is targeted.

Reliability assessment of hyperspectral imaging with the HyperView™ system for lower extremity superficial tissue oxygenation in young healthy volunteers

Purpose: Hyperspectral imaging (HSI) is a noninvasive spectroscopy technique for determining superficial tissue oxygenation. The HyperView™ system is a hand-held camera that enables perfusion image acquisition. The evaluation of superficial tissue oxygenation is warranted in the evaluation of patients with peripheral arterial disease. The aim was to determine the reliability of repeated HSI measurements. Methods: In this prospective cohort study, HSI was performed on 50 healthy volunteers with a mean age of 26.4 ± 2.5 years, at the lower extremity. Two independent observers performed HSI during two subsequent measurement sessions. Short term test–retest reliability and intra- and inter-observer reliability were determined, and generalizability and decision studies were performed. Transcutaneous oxygen pressure (TcPo2) measurements were also performed. Results: The short term test–retest reliability was good for the HSI values determined at the lower extremity, ranging from 0.72 to 0.90. Intra- and inter-observer reliability determined at different days were poor to moderate for both HSI (0.24 to 0.71 and 0.30 to 0.58, respectively) and TcPo2 (0.54 and 0.56, and 0.51 and 0.31, respectively). Reliability can be increased to >0.75 by averaging two measurements on different days. Conclusion: This study showed good short term test–retest reliability for HSI measurements, however low intra- and inter-observer reliability was observed for tissue oxygenation measurements with both HSI and TcPo2 performed at separate days in young healthy volunteers. Reliability of HSI can be improved when determined as a mean of two measurements taken on different days.

Migration of liquid silicone, an emerging contraindication of neuraxial anesthesia

The illegal use of liquid silicone products or biopolymers in gluteal augmentation procedures is giving rise to multiple complications, with a significant negative health impact, both in the short and long-term. The migration of polymers to the sacral and lumbar region represents a major limitation to conducting neuraxial anesthesia procedures. This silicon migration is unpredictable through the superficial tissue as is widely described in the literature. Caudal, spinal and epidural anesthesia may cross the silicone in the fascia and contaminate the neural axis with substances that are highly capable of causing inflammation, edema and tissue necrosis. In order to improve the safety of neuraxial anesthetic procedures and avoid the potential risk of dissemination and contamination of the neural axis, this complication must be ruled out, or be considered an emerging contraindication for these anesthetic procedures.

Colored Doppler Ultrasound Diagnosis and Pathological Analysis of Superficial Organ and Vascular Diseases

This paper proposes a fully digital signal processing scheme for ultrasonic Doppler endoscope imaging. 200 patients with superficial tissue lumps were randomly divided into two groups: the control group and the experimental group. These two groups used conventional ultrasound examination and colored Doppler ultrasound imaging technology, respectively, to observe and compare the test method and the surgical pathological examination results. Compared with the results of the two groups, the diagnostic compliance rate of the patients in the experimental group was 99.0% significantly higher than the diagnostic compliance rate of 86.0%. At the same time, 300 patients with surgery and pathologically confirmed superficial organ lesions were selected in the hospital, and all patients were diagnosed by ultrasound to observe the diagnosis. The clinical effects of colored Doppler ultrasound to diagnose vascular lesions in the lower extremities of diabetes were discussed. The rate of arteriosclerosis in the lower extremities of the observation group was 92.32%. The more than 50% vascular stenosis rate was 45.16%. The vascular blocking rate was 16. 13% and thrombosis rate 6.45% were significantly higher than the control group 12.90%, 8.06%, 0.00%, 0.00%. In the diagnosis of superficial tissue lesions, the resolution of colored Doppler ultrasound imaging technology is relatively high, which can significantly improve the clinical diagnosis rate and has clinical application value.

Internal defect scanning of sweetpotatoes using interactance spectroscopy

While standard visible-light imaging offers a fast and inexpensive means of quality analysis of horticultural products, it is generally limited to measuring superficial (surface) defects. Using light at longer (near-infrared) or shorter (X-ray) wavelengths enables the detection of superficial tissue bruising and density defects, respectively; however, it does not enable the optical absorption and scattering properties of sub-dermal tissue to be quantified. This paper applies visible and near-infrared interactance spectroscopy to detect internal necrosis in sweetpotatoes and develops a Zemax scattering simulation that models the measured optical signatures for both healthy and necrotic tissue. This study demonstrates that interactance spectroscopy can detect the unique near-infrared optical signatures of necrotic tissues in sweetpotatoes down to a depth of approximately 5±0.5 mm. We anticipate that light scattering measurement methods will represent a significant improvement over the current destructive analysis methods used to assay for internal defects in sweetpotatoes.

Efficacy of radiofrequency RDN may be significantly improved if the procedure is guided by impedance drop during the treatment

Background Experimental studies of radiofrequency renal denervation (RDN) have shown a strong relation of the depth of structural lesions and completeness of renal nerve injury to the relative drop in impedance during the treatment caused by the increased permeability of the cell membranes. Thus, the otherwise successful treatments but with low impedance drop may be, in fact, totally ineffective. Objective We assessed the relation between impedance drop during single radiofrequency treatments and local structural changes of vascular wall at the electrode positions using optical coherence tomography. Methods Optical coherence tomography of the treated segments was performed during radiofrequency RDN in 14 patients with resistant hypertension. The parameters of contrast injection depended on the position of the guiding catheter: for selective branch imaging 15 ml volume was injected at 8 ml/sec speed; otherwise 30 ml of contrast was injected at the speed 15 ml/sec to flush the whole renal artery. Automatic pullback of the sensor was done with the standard speed 20 mm/sec. In total, 423 mm of treated segments in 22 renal vessels (mostly distal branches) had sufficient quality of imaging and were studied for structural changes. Results There was almost no local structural changes of the arterial wall after the treatments with low impedance drop <10% reflecting a rather weak heating of even superficial tissue layers. No effect on the deeper tissue layers is expected in this case because these layers are heated almost exclusively by the heat transfer from superficial layer. In contrast, the treatments with the impedance drop 10% or greater were able to significantly affect the arterial structure causing local edema, small dissections, and local thrombi formation as a result of significant resistive heating of the superficial tissue, and, therefore, high potential for heating of the deep layers containing the renal nerves. Only approximately 40% of the point treatments had the impedance drop 10% or greater suggesting adequate lesion depth and sufficient completeness of renal nerve injury. This may indicate a rather low procedural efficacy of the current mode of radiofrequency RDN due to a large proportion of small-depth treatments marked by only a few percent decrease in impedance yet considered fully “successful”. Also, it means a potential for significant increase in the efficacy of radiofrequency RDN through controlling/guiding the treatment by the impedance drop. Conclusion Our study shows that variable efficacy of radiofrequency RDN may be explained by a significant proportion of the small-depth point treatments ineffective in terms of renal nerve injury, and, thereby, may be significantly improved if the procedure is guided by the impedance drop during the treatment. Funding Acknowledgement Type of funding source: None

Transformational change in the field of diffuse optics: From going bananas to going nuts

The concept of region of sensitivity is central to the field of diffuse optics and is closely related to the Jacobian matrix used to solve the inverse problem in imaging. It is well known that, in diffuse reflectance, the region of sensitivity associated with a given source–detector pair is shaped as a banana, and features maximal sensitivity to the portions of the sample that are closest to the source and the detector. We have recently introduced a dual-slope (DS) method based on a special arrangement of two sources and two detectors, which results in deeper and more localized regions of sensitivity, resembling the shapes of different kinds of nuts. Here, we report the regions of sensitivity associated with a variety of source–detector arrangements for DS measurements of intensity and phase with frequency-domain spectroscopy (modulation frequency: 140[Formula: see text]MHz) in a medium with absorption and reduced scattering coefficients of 0.1 and 12 cm[Formula: see text], respectively. The main result is that the depth of maximum sensitivity, considering only cases that use source-detector separations of 25 and 35 mm, progressively increases as we consider single-distance intensity (2.0[Formula: see text]mm), DS intensity (4.6[Formula: see text]mm), single-distance phase (7.5[Formula: see text]mm), and DS phase (10.9[Formula: see text]mm). These results indicate the importance of DS measurements, and even more so of phase measurements, when it is desirable to selectively probe deeper portions of a sample with diffuse optics. This is certainly the case in non-invasive optical studies of brain, muscle, and breast tissue, which are located underneath the superficial tissue at variable depths.