Super multi-channel recording systems with UWB wireless transmitter for BMI.

In order to realize a low-invasive and high accuracy Brain-Machine Interface (BMI) system for clinical applications, a super multi-channel recording system was developed in which 4096 channels of Electrocorticogram (ECoG) signal can be amplified and transmitted to outside the body by using an Ultra Wide Band (UWB) wireless system. Also, a high density, flexible electrode array made by using a Parylene-C substrate was developed that is composed of units of 32-ch recording arrays. We have succeeded in an evaluation test of UWB wireless transmitting using a body phantom system.

Experimental implant communication of high data rate video using an ultra wideband radio link.

Ultra wideband (UWB) is one of the radio technologies adopted by the IEEE 802.15.6™-2012 standard for on-body communication in body area networks (BANs). However, a number of simulation-based studies suggest the feasibility of using UWB for high data rate implant communication too. This paper presents an experimental verification of said predictions. We carried out radio transmissions of H.264/1280×720 pixels video at 80 Mbps through a UWB multiband orthogonal frequency division multiplexing (MB-OFDM) interface in a porcine chirurgical model. The results demonstrated successful transmission up to a maximum depth of 30 mm in the abdomen and 33 mm in the thorax within the 4.2-4.8 GHz frequency band.

Use of contrast-enhanced ultrasonography with a perflubutane-based contrast agent performed one day after transarterial chemoembolization for the early assessment of residual viable hepatocellular carcinoma.

OBJECTIVE: We evaluated the efficacy of contrast-enhanced ultrasonography (US), compared with contrast-enhanced computed tomography (CT), for early assessments after transarterial chemoembolization (TACE) for the treatment of hypervascular hepatocellular carcinoma (HCC) lesions. SUBJECTS AND METHODS: Thirty-two patients with 59 HCC lesions who were scheduled to receive TACE were enrolled in this prospective study. TACE was performed by injecting a mixture of iodized oil and miriplatin hydrate, followed by a gelatin sponge. Digital subtraction angiography (DSA) and/or contrast-enhanced CT were performed 2-6 months after TACE and were used as the reference standard for residual HCC; the detection rates for residual viable HCC using contrast-enhanced US with a perflubutane-based contrast agent and a high mechanical index (MI) mode performed one day after TACE were also compared with those obtained using contrast-enhanced CT performed one month after TACE. The comparisons were made using the McNemar test. RESULTS: Forty-seven (79.7%) of the 59 HCC lesions were diagnosed as having residual viability based on DSA and contrast-enhanced CT findings obtained 2-6 months after TACE. Eight (17.0%) of the 47 HCC lesions that were diagnosed as having residual viability using one-day contrast-enhanced US were not detected using one-month contrast-enhanced CT because of artifacts produced by the high attenuation of the iodized oil. The detection rate for residual HCC lesions using one-day contrast-enhanced US (95.7%, 45/47) was significantly higher than that using one-month contrast-enhanced CT (78.7%, 37/47) (P<0.05). CONCLUSION: Contrast-enhanced US performed one day after TACE is more sensitive than contrast-enhanced CT performed one month after TACE for detecting residual viable HCC.

Hepatic failure in pregnancy successfully treated by online hemodiafiltration: Chronic hepatitis B virus infection without viral genome mutation.

A 23-year-old nulliparous woman, a hepatitis B virus (HBV) carrier with stable liver functions, presented with exacerbation of viral replication (HBV DNA level >9.0 log copies/mL) in gestational week 26. During the subsequent follow up without antiviral therapy, she was hospitalized with progression to hepatic failure in gestational week 35. Following initiation of antiviral therapy with lamivudine, emergent cesarean delivery was conducted for fetal safety. Liver atrophy and persistent hepatic encephalopathy (stage 2) necessitated artificial liver support (ALS) involving online hemodiafiltration (HDF) and plasma exchange. She regained full consciousness after the sixth online HDF session. ALS was terminated after the seventh online HDF session. On day 33 of hospitalization, she was discharged home without sequelae. Genetic analysis of the HBV strain isolated from her serum showed that this strain had genotype C. Direct full-length sequencing identified no known mutations associated with fulminant hepatitis B. HBV-related hepatic failure observed in the present case might have been related to perinatal changes in the host immune response.

Validation of statistical channel models for 60 GHz radio systems in hospital environments.

Statistical channel models for 60 GHz communications systems in hospital environments are validated using channel capacity and throughput of a physical layer as figures of merit. The channel models are validated by comparing the performance figures with channels from the measurements and the channel models. The throughput evaluation is based on system specifications given by the IEEE 802.15.3 c standard for high data rate wireless personal area networks, namely orthogonal frequency division multiplexing and single carrier transmissions. The channel capacity serves as a metric of the potential of the two transmission schemes since it defines the upper bound of the throughput. The capacity is derived based on the signal formats of the transmission schemes. The capacity shows that 97 % of the measurement results are within 2σ range of the modeled results. The throughput shows that the channel models predict the maximum achievable throughput of the measured channels precisely, while the mean throughput in some cases shows difference because of the interpolation effect of the small-scale fading in the statistical channel models. Due to the interpolation effect, the channel model is more suitable for a precise analysis of the outage performance than the measurements where the number of channel samples is limited and the worst faded channels are not necessarily included.

[A case of rectal hemorrhage during chemotherapy with bevacizumab for local recurrence of rectal cancer].

Chemotherapy with bevacizumab(BV)has been one of the standard treatments for patients with metastatic colorectal cancer. However, emergent treatments are sometimes required because of severe adverse events associated with it. We experienced a case of massive rectal hemorrhage during BV treatment, and interventional radiology(IVR)successfully controlled it. An 81-year-old male visited our hospital, suffering from local recurrence of rectal cancer. He underwent colostomy for fecal diversion, and chemoradiation therapy was performed. Systemic chemotherapy with XELOX+BV was performed for the residual tumor. On the 27th day after the first administration of BV, the patient was hospitalized because of anal bleeding and a state of shock. The colonoscopic examination showed a dimple caused by tumor shrinkage, which was closed by clipping. However, a state of shock was caused by intermittent hemorrhages again afterwards. The hemorrhagic point was identified as the oral side of the dimple by angiography, and coil embolization led to immediate hemostasis. The colonoscopic examination revealed nothing abnormal besides the dimple. It is therefore suspected that the cause of rectal hemorrhage might be induced by BV. During combination chemotherapy with BV, bleeding is one of the severe adverse events requiring an emergent treatment regardless of BV dose. IVR may be an effective treatment when bleeding can not be controlled by endoscopic hemostasis. Therefore, we should construct a system for emergency hemostasis including IVR.

Prototype ultra wideband-based wireless body area network--consideration of CAP and CFP slot allocation during human walking motion.

This paper presents an experimental evaluation of communication during human walking motion, using the medium access control (MAC) evaluation system for a prototype ultra-wideband (UWB) based wireless body area network for suitable MAC parameter settings for data transmission. Its physical layer and MAC specifications are based on the draft standard in IEEE802.15.6. This paper studies the effects of the number of retransmissions and the number of commands of GTS (guaranteed time slot) request packets in the CAP (contention access period) during human walking motion by varying the number of sensor nodes or the number of CFP (contention free period) slots in the superframe. The experiments were performed in an anechoic chamber. The number of packets received is decreased by packet loss caused by human walking motion in the case where 2 slots are set for CFP, regardless of the number of nodes, and this materially decreases the total number of packets received. The number of retransmissions and the GTS request commands increase according to increases in the number of nodes, largely reflecting the effects of the number of CFP slots in the case where 4 nodes are attached. In the cases where 2 or 3 nodes are attached and 4 slots are set for CFP, the packet transmission rate is more than 95%. In the case where 4 nodes are attached and 6 slots are set for CFP, the packet transmission rate is reduced to 88% at best.

Interoperable and diligent body area networks over IEEE802.15.6 for real-time monitoring.

Currently, there are no standardization efforts to define interfaces and verify interoperability among implementations for body area networks (BANs) on IEEE802.15.6. A BAN consists of small and lightweight sensors, such as the ring-type SpO2 sensor, and a coordinator that collects vital data from the sensors and transfers them to a backend system for real-time monitoring and analysis. It is important for sensors to be easy-to-use, light for wearing and that they are long-lived using a small rechargeable battery. IEEE802.15.6 provides basic features for these sensors. We establish an industry-driven standardization association for healthcare/medical services on IEEE802.15.6. Industry standardization targets current and emerging small sensors, not those for fixed medical devices in hospitals, such as those in the ISO/IEEE11073 family, and deals with time-driven data. We propose a combination of various layers of power-saving functions for a sensor that satisfies the interfaces. We discuss these functions and evaluate them. As a feasibility study, we then test a false-alert system using a BAN configuration following the standard interfaces, though the standardizations and evaluations are still in progress along with the IEEE802.15.6 standardization activity.

Path-loss estimation of wireless channels in capsule endoscopy from X-ray CT images.

The paper describes an estimation method of path-loss for capsule endoscopy using wireless communications to send images from digestive tract. This method is based on the use of a set of X-ray computer tomography (CT) images of the patient. In order to evaluate this method, we conducted a measurement of received signal strength (RSS) by introducing a signal generator (SG) in esophagus and duodenum of a participant. As a result of comparisons, the method provides estimates on path-loss for the participant with estimation errors of less than 6 dB in 75% measurement positions.

Design of packet erasure mitigation technique using a digital fountain code for wearable wireless body area networks.

This paper presents a digital fountain code as a design criterion in order to mitigate packet erasure in wireless wearable body area networks (WBANs). First, we measure its radio propagation around the human body between two antennas attached to participants, and then analyze the measurement results from the standpoint of occurrence ratio of packet erasure. Then, we evaluate the application of digital fountain code into such WBANs where a rateless code is introduced as such code in order to provide a design criterion for the code.

Performance evaluation of wearable wireless body area networks during walking motions in 444.5 MHz and 2450 MHz.

This paper gives performance evaluation of wearable wireless body area networks (WBANs) during walking motion. In order to evaluate the performance, received signal strength (RSS), packet error rate (PER), and bit error rate (BER) are measured in an anechoic chamber and an office room. This measurement is conducted in the frequency band of 444.5 and 2450 MHz by using GFSK signal with symbol rate of 1 MHz. The results show that in the anechoic chamber the WBAN using the 444.5 MHz enables to provide error-free communication, on the other hand, the WBAN operated in the 2450 MHz faces packet errors. Measurement results in the office room give comparable performance between these frequencies. From these observations, the use of 2450 MHz for wearable WBANs needs reflection waves in order to compensate a shadowing effect caused by the human body using the WBAN.

Low-complexity video encoding method for wireless image transmission in capsule endoscope.

This paper presents a low-complexity video encoding method applicable for wireless image transmission in capsule endoscopes. This encoding method is based on Wyner-Ziv theory, in which side information available at a transmitter is treated as side information at its receiver. Therefore complex processes in video encoding, such as estimation of the motion vector, are moved to the receiver side, which has a larger-capacity battery. As a result, the encoding process is only to decimate coded original data through channel coding. We provide a performance evaluation for a low-density parity check (LDPC) coding method in the AWGN channel.

Novel joint source-channel coding for wireless transmission of radiography images.

A wireless technology is required to realize robust transmission of medical images like a radiography image over noisy environment. The use of error correction technique is essential for realizing such a reliable communication, in which a suitable channel coding is introduced to correct erroneous bits caused by passing through a noisy channel. However, the use of a channel code decreases its efficiency because redundancy bits are also transmitted with information bits. This paper presents a joint source-channel coding which maintains the channel efficiency during transmission of medical images like a radiography image. As medical images under the test, we use typical radiography images in this paper. The joint coding technique enjoys correlations between pixels of the radiography image. The results show that the proposed joint coding provides capability to correcting erroneous bits without increasing the redundancy of the codeword.

A feasibility study on image-based control of surgical robot using a 60-GHz wireless communication system.

This paper presents an evaluation study on the feasibility of introducing wireless connection into a neurosurgical robot, which is controlled by an image-based navigation system. The wireless connection introduced into the robotic system is based on amplitude shift keying (ASK) at 60 GHz. With this wireless connection, data transmission at the bit-rate of 1 Gbps or more is possible, and here high-definition video images (1080i/1080p) can be transmitted. Such a wireless connection system is implemented in the surgical robot replaces the cable connection between the digital video camera and the controller. In this study, the wireless robotic surgical system is evaluated in terms of its accuracy of navigation using the transmitted video images. The results of a wireless connection test under a line-of-sight (LOS) environment show that navigation accuracy observed when using this wireless surgical robot is comparable to that when using a wired robotic system.

A reliable wireless monitoring of periodic vital signals using a novel joint source-channel coding.

This paper proposes a joint source-channel coding technology to transmit periodic vital information such as an electrocardiogram (ECG). It shows the iterative decoding method using a correlation value which can be obtained from ECG periodicity as Side-Information. The improvement is shown when bit strings are transmitted with different encoding rates. Because the proposed method has an error correcting system and makes a code processing decrease, some miniaturization and energy-saving can be expected of the equipment. Finally, the effectiveness of the proposed method is shown by comparisons with Differential Pulse Code Modulation, which is a typical compression method of ECG, and with the no coding method.

Performance evaluation of wireless communications through capsule endoscope.

This paper presents a performance evaluation of wireless communications applicable into a capsule endoscope. A numerical model to describe the received signal strength (RSS) radiated from a capsule-sized signal generator is derived through measurements in which a liquid phantom that has equivalent electrical constants is used. By introducing this model and taking into account the characteristics of its direction pattern of the capsule and propagation distance between the implanted capsule and on-body antenna, a cumulative distribution function (CDF) of the received SNR is evaluated. Then, simulation results related to the error ratio in the wireless channel are obtained. These results show that the frequencies of 611 MHz or lesser would be useful for the capsule endoscope applications from the view point of error rate performance. Further, we show that the use of antenna diversity brings additional gain to this application.

Molecularly defined caprolactone oligomers and polymers: synthesis and characterization.

The synthesis of molecularly defined epsilon-caprolactone oligomers and polymers up to the 64-mer, via an exponential growth strategy, is described. By careful selection of orthogonal protecting groups, t-butyldimethylsilyl (TBDMS) ether for the hydroxyl group and benzyl (Bn) ester for the carboxylic acid group, a highly efficient synthetic strategy was developed with yields for both deprotection steps being essentially quantitative and for the coupling reactions using 1,3-dicyclohexylcarbodiimide (DCC), yields of 80-95% were obtained even at high molecular weights. This allows monodisperse dimers, tetramers, octamers, 16-mers, 32-mers and 64-mers to be prepared in gram quantities and fully characterized using mass spectroscopy, size exclusion chromatography (SEC), and IR and NMR spectroscopy. Thermal and physical properties were measured using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). These results conclusively show a distinct structure/property relationship with a close correlation between the number of repeat units and physical properties. In addition, a number of marked differences were observed on comparison with the parent poly(caprolactone) polymer.

Channel models for wireless body area networks.

Wireless patient monitoring using wearable sensors is a promising application. This paper provides stochastic channel models for wireless body area network (WBAN) on the human body. Parameters of the channel models are extracted from measured channel transfer functions (CTFs) in a hospital room. Measured frequency bands are selected so as to include permissible bands for WBAN; ultra wideband (UWB), the industry, science and medical (ISM) bands, and wireless medical telemetry system (WMTS) bands. As channel models, both a path loss model and a power delay profile (PDP) model are considered. But, even though path loss models are derived for the all frequency bands, PDP model is only for the UWB band due to the highly frequency selectiveness of UWB channels. The parameters extracted from the measurement results are summarized for each channel model.

Wireless vital sign monitoring using ultra wideband-based personal area networks.

This paper presents a wireless vital sign monitoring system using IEEE802.15.4a standard based on ultra wideband (UWB) wireless communications. The vital signs are categorized into continuous and routine vital signs; the continuous signs include electrocardiogram (ECG), and the routine ones cover blood pressure, oxygen saturation, and body temperature. To conduct both tasks simultaneously, a superframe structure is optimized to minimize the delay time of packet transmission through computer simulation. Results showed that IEEE802.15.4a standard has capability to together monitor both single continuous sign and multiple routine signs simultaneously.

A versatile new monomer family: functionalized 4-vinyl-1,2,3-triazoles via click chemistry.

Using facile, highly modular synthetic approaches, a new monomer family based on a 1,2,3-triazole-4-vinyl building block has been prepared, and various functional derivatives have been obtained. Subsequent homo- and copolymerization of these novel functionalized monomers gives polymeric materials with unique physical properties, combining many attractive features of more traditional monomers, such as styrene, vinylpyridine, and meth/acrylates.