Temporal hemiarthroplasty for distal femoral osteosarcoma in early childhood: a case report.

BACKGROUND: Prosthetic reconstruction for distal femoral osteosarcoma is challenging for younger children. We herein report a successful case of limb-sparing surgery for a younger patient with distal femoral osteosarcoma requiring osteo-articular resection. CASE PRESENTATION: A 5-year-old girl with high-grade conventional osteosarcoma in the left distal femur underwent a series of surgeries. After three cycles of neoadjuvant chemotherapy, limb-salvage surgery was planned because femoral rotationplasty had been refused. At 6 years and 2 months old, distal femoral resection and temporary spacer insertion using a 7-mm-diameter intramedullary nail and molded polymethylmethacrylate was performed. At 7 years and 8 months old, secondary surgery was performed because the first spacer had been dislocated and the residual femur became atrophic. The distal end of the residual femur was removed by 1 cm, but the periosteum and induced membrane around polymethylmethacrylate was preserved. In order to stabilize the spacer against the tibia, a custom-made ceramic spacer with a smooth straight 8-mm-diameter stem was utilized. The bone-spacer junction was fixed with polymethylmethacrylate and then covered with the preserved periosteum and induced membrane. After surgery, the bone atrophy improved. At 9 years and 7 months old, the second spacer was removed because it had loosened, and the knee joint was reconstructed using a custom-made growing femoral prosthesis with a curved porous 8.5-mm-diameter stem. Cancellous bone tips from the proximal tibia were grafted around the bone-prosthesis junction underneath the induced membrane. At 10 years and 5 months old, the patient was able to walk unsupported and a radiograph showed further thickening of the cortex of the residual femur without any stress shielding. Although having 5 cm of limb length discrepancy, the patient and her mother were satisfied with the function. The MSTS score was 24 out of 30 points. Repeated limb length extensions are planned. CONCLUSIONS: This case report provides an example of limb-salvage surgery after distal femoral resection in a small child. The use of a temporary spacer utilizing partial cementation and preservation of the periosteum and induced membrane appears to afford a viable limb-salvage option after distal femoral resection for younger children.

Classification of heart sound signals using a novel deep WaveNet model.

BACKGROUND AND OBJECTIVES: The high mortality rate and increasing prevalence of heart valve diseases globally warrant the need for rapid and accurate diagnosis of such diseases. Phonocardiogram (PCG) signals are used in this study due to the low cost of obtaining the signals. This study classifies five types of heart sounds, namely normal, aortic stenosis, mitral valve prolapse, mitral stenosis, and mitral regurgitation. METHODS: We have proposed a novel in-house developed deep WaveNet model for automated classification of five types of heart sounds. The model is developed using a total of 1000 PCG recordings belonging to five classes with 200 recordings in each class. RESULTS: We have achieved a training accuracy of 97% for the classification of heart sounds into five classes. The highest classification accuracy of 98.20% was achieved for the normal class. The developed model was validated with a 10-fold cross-validation, thus affirming its robustness. CONCLUSION: The study results clearly indicate that the developed model is able to classify five types of heart sounds accurately. The developed system can be used by cardiologists to aid in the detection of heart valve diseases in patients.

Comprehensive electrocardiographic diagnosis based on deep learning.

Cardiovascular disease (CVD) is the leading cause of death worldwide, and coronary artery disease (CAD) is a major contributor. Early-stage CAD can progress if undiagnosed and left untreated, leading to myocardial infarction (MI) that may induce irreversible heart muscle damage, resulting in heart chamber remodeling and eventual congestive heart failure (CHF). Electrocardiography (ECG) signals can be useful to detect established MI, and may also be helpful for early diagnosis of CAD. For the latter especially, the ECG perturbations can be subtle and potentially misclassified during manual interpretation and/or when analyzed by traditional algorithms found in ECG instrumentation. For automated diagnostic systems (ADS), deep learning techniques are favored over conventional machine learning techniques, due to the automatic feature extraction and selection processes involved. This paper highlights various deep learning algorithms exploited for the classification of ECG signals into CAD, MI, and CHF conditions. The Convolutional Neural Network (CNN), followed by combined CNN and Long Short-Term Memory (LSTM) models, appear to be the most useful architectures for classification. A 16-layer LSTM model was developed in our study and validated using 10-fold cross-validation. A classification accuracy of 98.5% was achieved. Our proposed model has the potential to be a useful diagnostic tool in hospitals for the classification of abnormal ECG signals.

Fabrication of Coaxial and Confocal Transducer Based on Sol-Gel Composite Material for Optical Resolution Photoacoustic Microscopy.

We have newly developed coaxial and confocal optical-resolution photoacoustic microscopy based on sol-gel composite materials. This transducer contains a concave-shaped piezoelectric layer with a focus depth of 5 mm and a hole with a diameter of 3 mm at the center to pass a laser beam into a phantom. Therefore, this system can directly detect an excited photoacoustic signal without prisms or acoustic lenses. We demonstrate the capability of the system through pulse-echo and photoacoustic imaging experiments. The center frequency of the fabricated transducer is approximately 7 MHz, and its relative bandwidth is 86%. An ex-vivo experiment is conducted, and photoacoustic signals are clearly obtained. As a result, 2- and 3-dimensional maximum amplitude projection images are reconstructed.

The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures.

In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

Microscopic observation of glass bead movement in soft tissue-mimicking phantom under ultrasound PW mode scanning.

Previous studies have demonstrated that stones and calcification in soft tissue show special enhancement in response to color flow (CF) or pulse Doppler (PW) mode ultrasound scan. This phenomenon is known as the "twinkling sign (TS)". The authors conducted an in vitro experiment to investigate the mechanism of TS occurrence by observing a glass bead in a transparent PVA-H soft tissue-mimicking phantom. The TS in PW mode showed a low-power and slow-velocity spectrum. At the same time, analysis of images by high-speed camera showed that the glass bead in the phantom oscillated following the pulse repetition frequency (PRF) of the PW mode ultrasound scan. The harmonic oscillations were confirmed, as well. The ultrasound radiation force-driven micro-oscillation possibly affects the ultrasound propagation around the scatterer and triggers random signals in the received echo signals. The results indicate that TS is a phenomenon based on complicated acoustic-mechanical interaction of multiple mechanisms. Further investigation is required for gaining a full understanding of the mechanism of TS occurrence and its clinical application.

Fundamental study on micro calcification detection using twinkling sign (TS): the effect of stiffness of surrounding tissue on the appearance of TS.

The twinkling sign (TS) observed in ultrasound imaging (e.g., color flow mode and pulse Doppler mode) has been reported in previous researches as a potential phenomenon to detect micro calcification in soft tissue. However, the mechanism of the twinkling sign has not been clearly understood yet. The authors investigated the effect of stiffness of surrounding tissue on the appearance of TS using the soft tissue-mimicking phantoms and a medical ultrasound device. The author used Poly (vinyl alcohol) hydro (PVA-H) gel as the material of phantom and developed three phantoms with different PVA concentration; 8 %wt, 10 %wt and 15 %wt those correspond to Young's modulus (E) as 50 kPa, 100 kPa and 230 kPa, respectively. Micro glass and CaCO3 particles were embedded in the phantoms as pseudo micro calcification. The authors observed TS in each phantom and analyzed the temporal average of TS. The temporal average of TS was largest in the 8 %wt (E = 50 kPa) PVA-H gel phantom, and decreased with increasing the phantom stiffness. The result indicated that the micro oscillation of the particles had a close relationship with the occurrence of TS.

Transmission of 100-MHz-range ultrasound through a fused quartz fiber.

PURPOSE: This paper describes an investigation into direct observation of microscopic images of tissue using a thin acoustic wave guide. METHODS: First, the characteristics of the ultrasonic wave propagated in a fused quartz fiber were measured using the reflection method in order to study the insertion loss and the frequency shift of the ultrasonic wave transmitted from the transducer. Next, a receiving transducer was placed close to the end of the fiber, and the characteristics of the ultrasonic waves propagated through the acoustic coupling medium were measured using the penetration method in order to study the insertion loss and the frequency-dependent attenuation of the penetrated waves. Finally, a C-mode image was obtained by optimizing the measuring conditions using the results of the above measurements and scanning the ultrasonic beams on a target (coin) in water. RESULTS: A reflected wave with a peak frequency of approximately 220 MHz was obtained from the end of the fiber. The transmitted ultrasonic waves propagated through the acoustic coupling medium were detected with a frequency range of approximately 125-170 MHz, and the maximum detectable distance of the waves was approximately 1.2 mm within the 100-MHz frequency range. Finally, a high-frequency C-mode image of a coin in water was obtained using a tapered fused quartz fiber. CONCLUSION: The results suggest that it is necessary to improve the signal-to-noise ratio and reduce the insertion loss in the experimental system in order to make it possible to obtain microscopic images of tissue.

Analysis of enzyme production by submerged culture of Aspergillus oryzae using whole barley.

We have reported on high enzyme production by submerged culture of Aspergillus kawachii using barley with the husk (whole barley). To elucidate the mechanism underlying this high enzyme production, we performed a detailed analysis. Aspergillus oryzae RIB40 was submerged-cultured using whole barley and milled whole barley. Enzyme production was analyzed in terms of changes in medium components and gene expression levels. When whole barley was used, high production of glucoamylase and alpha-amylase and high gene expression levels of these enzymes were observed. Low ammonium concentrations were maintained with nitrate ion uptake continuing into the late stage using whole barley. These findings suggest that the sustainability of nitrogen metabolism is related to high enzyme production, and that a mechanism other than that associated with the conventional amylase expression system is involved in this relationship.

Simultaneous production of glucoamylase and acid-stable alpha-amylase using novel submerged culture of Aspergillus kawachii NBRC4308.

We developed a novel submerged culture system of Aspergillus kawachii NBRC4308 using barley whose surface is completely or partly covered with husk. The culture supernatant showed a glucoamylase activity of 150.8 U/ml and an acid-stable alpha-amylase activity of 7.7 U/ml brought about by the maintenance of a low glucose concentration in the culture system.