Image Guided Navigation Utilizing Intra-operative 3D Surface Scanning to Mitigate Morphological Deformation of Surface Anatomy Abstract Purpose The purpose of this study is to navigate an in-house robot under uncertain intraoperative changes of the body surface which is not present in the pre-operative scan in hospital environments and lab environment. Methods The proposed methodology involves the use of a 3D scanner to form a 3D model. The method used in this study is cost effective and takes less time (about 5–7 min). We focused more on the surface anatomical positions of a patient, which may change after a pre-operative scan. With respect to this, we introduced a method to include these deformed regions in navigation, which are not present in pre-operative scans. Results By creating an on-spot 3D surface model of the cadaver’s and phantom’s head, and after registration processes we completed the surgical navigation process with an error (root-mean-square error) of 0.568 mm and 0.791 mm for phantom and cadaver respectively. Conclusion We showed the successful surgical navigation by using on-spot 3D surface modeling and including the deformity in our system. The accuracy of registration in lab condition and hospital condition was compared.

Mechanical Characterization of Soft Tissue Constituents for Cancer Detection Abstract Purpose Tissue classification based upon tissue stiffness is very useful in early diagnosis of cancer; specifically, breast tissue health is diagnosed through tissue stiffness. This paper proposes a method to define the mechanical characteristics of various soft tissues, which could be helpful in discovery of soft tissue abnormalities. Methods This study focused on tissue characterization and the identification of the relationship between tissue properties and pathological mechanics using an elastography technique (method of cancer detection, that uses the response of soft tissue to deformation) based on the Yeoh hyper-elastic model. The suitability of the Yeoh model was validated through compression testing of breast phantoms, animal tissues, and in vivo human tissues. Results The mean deviation between the known and calculated position was 0.31 ± 0.16 mm. The maximum deviation was less than 0.86 mm. Conclusion The results indicate that the location of a scintillator within the recording cage imaged with two cameras can be calculated with submillimeter accuracy. We hope that our methods can be applied to improve automatic (even real-time) tracking of various animals in vivo.

Evaluation of Different Modulation Transfer Function Measurement Based on Different Edge Spread Function Calculations Abstract Purpose As the X-ray imaging market keeps expanding and digital X-ray detector technology has become more important, the International Electro Technical Commission has developed an IEC 62220-1 standard for the device to cope with medical imaging report requirements. This paper specifies the modulation transfer function (MTF) and detective quantum efficiency (DQE) calculation method. However, during the practical operation, we found that if the multiple pre-sampling edge spread functions (ESFs) were averaged directly, the MTF value would be underestimated. This work develops a novel method for calculating the MTF. Methods We compared three different edge spread function (ESF) calculation methods. For method 1, the ESF is obtained by taking only the central line. For method 2, the ESFs are averaged directly. For method 3, the novel method proposed in this study, the ESFs would be shifted before they are averaged. The MTF is then obtained through calculating three different ESFs. Results We used a phantom experiment to verify the correctness of the code and confirm the results from the three methods under ideal conditions. We measured the detector response through a homemade laboratory testing platform. The results showed that, method 3 effectively eliminated MTF underestimation. The difference was not significant when the frequency was less than 1.5 lp/mm, however when it was greater than 1.5 lp/mm, the difference was larger. Conclusions This finding suggests that to eliminate the results caused by noise without any signal processing, and to generate a smoother MTF, our proposed method can give much reliable results.

Predictive Value of Opto-magnetic Imaging Spectroscopy in Discriminating Oral Squamous Cell Carcinoma from Non-tumor Tissue in Surgical Margins Abstract Purpose Negative surgical margins status is of extreme importance for better prognosis and lower recurrence rate in patients undergoing surgical treatment for oral squamous cell carcinoma (OSCC). Standard histopathology is time consuming and current optical procedures come with various limitations. We examined the potential of a new imaging technique—opto-magnetic imaging spectroscopy (OMIS) in discriminating tumor (OSCC) from adjacent non-tumor oral cavity tissue. Methods A total of 46 samples from 21 patients were included in this study. Samples were taken from a fresh surgical specimen of primary OSCC. Digital imaging of samples was performed within 60 min of resection using OMIS device. Images were processed through a specifically designed convolution algorithm based on light-matter interaction. As a result a convolution spectrum was generated. Predictive value of spectral data was assessed using correlation tests and Naïve Bayes classification model. Results There was no significant correlation in distribution of characteristic peaks between tumor and non-tumor tissue (P > 0.05). Tumor tissue showed more magnetic activity compared to non-tumor tissue. Naive Bayes classifier with kernel density estimation discriminated tumor from non-tumor tissue with the accuracy of 82.61%, 86.96% sensitivity, 78.26% specificity and the AUC value of 0.917. Conclusion OMIS seems to be a promising optical method for ex vivo characterization of OSCC and non-tumor tissue. Further investigation is necessary to determine how tissue type and level of pathological transformation impact OMIS results. Ultimately, this could aid surgeons in using this method as an in vivo indicator for surgical resection with safe margins.

A Platform for 4-Channel Parallel Transmission MRI at 3 T: Demonstration of Reduced Radiofrequency Heating in a Test Object Containing an Implanted Wire Abstract Objective To describe a platform for 4-channel parallel transmission (pTx) integrated on a 3 T MRI system; to demonstrate utility of the platform with a pTx method to reduce localized radiofrequency (RF) heating during MRI of a test object implanted with an electrically conductive wire; and to compare the pTx results with those from a standard birdcage (BC) head coil. Methods A 4-channel pTx system with independent amplitude and phase control was added to a Siemens Prisma MRI system. Turbo spin echo pTx MRI of a homogenous tissue-mimicking head phantom, including an implanted wire to simulate a deep brain stimulation (DBS) electrode, was performed in (a) circular-polarized “quadrature” transmission mode to demonstrate localized RF heating effects, and (b) an optimized RF shim “suppression” mode to counteract RF heating at the tip of the implanted wire. Signal-to-noise ratio (SNR) and temperature results from the pTx experiment were compared with imaging using a Siemens BC head coil. Results The pTx platform provided effective control of RF amplitude and phase to minimize localized RF heating at the wire tip. No temperature elevation was detected for pTx in suppression mode, whereas maximum increases of 6.9 °C and 2.7 °C were observed for pTx quadrature mode and imaging using the BC head coil, respectively. Conclusion The platform has been adapted to a Siemens MRI system without impacting the standard RF transmission pathway, while providing accurate RF signal modulation. Demonstration of the platform showed substantial reduction of localized RF heating in a simulated DBS implant without significant SNR loss.

Whitlockite Promotes Bone Healing in Rabbit Ilium Defect Model Abstract Purpose Treatment of bone defects commonly employs bone substitutes, like hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP) for promoting bone regeneration. However, both the phosphates have limitations with regards to biodegradability and mechanical strength; apparently, there exists a need for other novel phosphates material with an ability to promote optimal bone regeneration. Whitlockite (WH) is the second most abundant phosphate present in the human body and its superiority has only been proven in rat calvarial model. Therefore, in the present study, we have compared osteoconductivity of WH with hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP) by employing human mesenchymal stem cells and a rabbit ilium defect model. Methods The effects of WH on proliferation, alkaline phosphatase activity, and expression of osteogenetic related genes in human mesenchymal stem cells were analyzed. The implants made of HAP, β-TCP or WH were inserted in rabbit ilium defect, and after 6 weeks, the bone formation in each group was analyzed with micro-CT. Results The cells in the WH group exhibited higher proliferation level, ALP activity, and expression levels of osteoblastic related genes. In rabbit ilium defect model, the WH group had compatible percent bone volume compared to the other two groups. Additionally, the newly formed bone in the WH group had significantly thicker bone compared to other groups with a more directional form and migrated wider in the scaffold. Conclusions WH exhibited comparable osteoinductivity with HAP and β-TCP in rabbit ilium defect and is proposed as a better bone substitute material.

Acoustic Field of Phased-Array Ultrasound Transducer with the Focus/Foci Shifting Abstract Background High-intensity focused ultrasound (HIFU) is becoming popular in the treatment of solid tumors because of its non-invasiveness with few complications. The acoustic field is of importance in evaluating the safe focus shifting distance and determining the treatment plan. Methods The propagation of finite-amplitude acoustic wave from a 331-element HIFU phased-array with focus steering along and transverse to the transducer axis and 4-foci shifting on the focal plane was simulated using the angular spectrum approach (ASA) with a marching second-order operator-splitting scheme. In addition, the acoustic field produced by a truncated asymmetric transesophageal HIFU annular array was also simulated, and the effects of driving frequency and the number of concentric rings were investigated. Results Because of the nonlinear effects, the peak negative pressure is lower than that of peak positive pressure at the main lobe but has a larger beam size. However, the peak positive and negative pressures at the grating lobe are quite similar. The effects of the focus shifting distances on the main and grating lobe (both acoustic pressure and − 6 dB beam size) were evaluated. With the focus shifting axially away from the transducer surface, the main lobe has decreased acoustic pressure by ~ 1.9 fold and increased beam size by ~ 4.5 fold while the grating lobe has the increased acoustic pressure by ~ 1.8 fold. The focus shifting laterally leads to the reduced pressure at the main lobe by ~ 1.4 fold but the slight decrease at the grating lobe by ~ 1.1 fold. In comparison, the shifting of multi-foci has similar influences on the main lobe but increases the pressure at the grating lobe. Driving frequency of annular array is found to have greater influences on the peak pressure and beam size. Conclusion Our algorithm can simulate the acoustic field of phased-array in arbitrary shape and optimize the transducer design, and the focus shifting distance and strategy should be selected appropriately for the safe HIFU exposure.

Automatic Conformal Anti-radial Ultrasound Scanning for Whole Breast Screening Abstract Background Anti-radial ultrasound scanning is one of the main scanning approaches used in ultrasound breast screening. It can be used for cross-sectional imaging of mammary ductal/lobular tissue and provide information about suspicious tissue. It has certain advantages compared to linear scanning, but automatic anti-radial scanning is not yet available. Our goal is to propose an ultrasound scanning system for whole breast anti-radial scanning. Methods We previously developed an automatic ultrasound scanning system for whole breast screening involving linear scanning. The present study builds on our previous work by incorporating (1) surface-reconstruction algorithms, (2) a rotatable holder design, and (3) a scan-path-smoothing algorithm to achieve conformal anti-radial scanning. Results An improvement of approximately 40% in the normal-vector estimation is obtained with our new method, and the scan stability is improved by the scan-path-smoothing algorithm. 3D volume data of each scan are available. Conclusions We have successfully developed an automatic ultrasound scanning system for anti-radial breast scanning. This type of system, which has not been reported previously in the literature, can be an effective tool for fully automatic ultrasound breast screening.

Utilization of Mechanical Energy During Push-Off in Human Walking Abstract Purpose Notable disagreements have emerged from research on the role of ankle during push-off, the resolution of which is crucial to the understanding of the human movement science or the clinical treatment in rehabilitation. This research proposed a new symbolic convention of energy flow diagram to manifest where the ankle power generated during push-off is transmitted to in order to ease of interpreting the function of the ankle. Methods Gait data of eight healthy young adults at self-selected speeds were analyzed. Energetic data of the pelvis and lower limb were used to construct an energy flow diagram at the instant of peak ankle power generation during push-off. Results Our results suggest that the ankle mainly contributes to increase the kinetic energy of the ipsilateral leg in preparation for swing during push-off. The magnitude of the power flowing to the pelvis, which could be used for forward propulsion, was only 10% of that generated by the ankle. Conclusions The energy flow diagram with the proposed convention is a useful analytic tool with applications across many disciplines, for example, evaluating the energy performance of elite athletes, designing the powered prostheses, and revealing the compensatory movement strategy of people with disabilities.

Adaptive Filtering for Epileptic Event Detection in the EEG Abstract Purpose The development of online seizure detection techniques as well as prediction methods are very critical. Patient quality of life could improve significantly if the beginning of a seizure could be predicted or detected early. Methods This paper proposes a method to automatically detect epileptic seizures based on adaptive filters and signal averaging. The process was applied to 425 h of epileptic EEG records from CHB-MIT EEG database. The developed algorithm does not require any training since it is simple and involves low processing time. Therefore, it can be implemented in real time as well as offline. Results Three thresholds were evaluated and calculated as 10, 20 and 30 times the median value of ST(n). The threshold of 20 showed the best relation between SEN and SPE. In this case, these indexes reached average values, across all the patients, of 90.3% and 73.7% respectively. Conclusions The proposed method has several strengths, for example: that no training is required due to the automatic adaptation to the threshold to each new EEG record. The algorithm could be implemented in real time. It is simple owing to its low processing time which makes it suitable for the analysis of long-term records and a large number of channels. The system could be implemented on electronic devices for warning purposes (of the seizure onset). It employs methods to process signals that were not used with epileptic seizure detection in EEG, such as in the case of adaptive predictive filters.