Dynamic Contrast-Enhanced (DCE) MRI with 2nd generation pharmacokinetic models provides estimates of plasma flow and permeability surface-area product in contrast to the broadly used 1st generation ...models (e.g. the Tofts models). However, the use of 2nd generation models requires higher frequency with which the dynamic images are acquired (around 1.5 s per image). Blind deconvolution can decrease the demands on temporal resolution as shown previously for one of the 1st generation models. Here, the temporal-resolution requirements achievable for blind deconvolution with a 2nd generation model are studied.
The 2nd generation model is formulated as the distributed-capillary adiabatic-tissue-homogeneity (DCATH) model. Blind deconvolution is based on Parker's model of the arterial input function. The accuracy and precision of the estimated arterial input functions and the perfusion parameters is evaluated on synthetic and real clinical datasets with different levels of the temporal resolution.
The estimated arterial input functions remained unchanged from their reference high-temporal-resolution estimates (obtained with the sampling interval around 1 s) when increasing the sampling interval up to about 5 s for synthetic data and up to 3.6–4.8 s for real data. Further increasing of the sampling intervals led to systematic distortions, such as lowering and broadening of the 1st pass peak. The resulting perfusion-parameter estimation error was below 10% for the sampling intervals up to 3 s (synthetic data), in line with the real data perfusion-parameter boxplots which remained unchanged up to the sampling interval 3.6 s.
We show that use of blind deconvolution decreases the demands on temporal resolution in DCE-MRI from about 1.5 s (in case of measured arterial input functions) to 3–4 s. This can be exploited in increased spatial resolution or larger organ coverage.
Purpose
The Tofts and the extended Tofts models are the pharmacokinetic models commonly used in dynamic contrast‐enhanced MRI (DCE‐MRI) perfusion analysis, although they do not provide two important ...biological markers, namely, the plasma flow and the permeability‐surface area product. Estimates of such markers are possible using advanced pharmacokinetic models describing the vascular distribution phase, such as the tissue homogeneity model. However, the disadvantage of the advanced models lies in biased and uncertain estimates, especially when the estimates are computed voxelwise. The goal of this work is to improve the reliability of the estimates by including information from neighboring voxels.
Theory and Methods
Information from the neighboring voxels is incorporated in the estimation process through spatial regularization in the form of total variation. The spatial regularization is applied on five maps of perfusion parameters estimated using the tissue homogeneity model. Since the total variation is not differentiable, two proximal techniques of convex optimization are used to solve the problem numerically.
Results
The proposed algorithm helps to reduce noise in the estimated perfusion‐parameter maps together with improving accuracy of the estimates. These conclusions are proved using a numerical phantom. In addition, experiments on real data show improved spatial consistency and readability of perfusion maps without considerable lowering of the quality of fit.
Conclusion
The reliability of the DCE‐MRI perfusion analysis using the tissue homogeneity model can be improved by employing spatial regularization. The proposed utilization of modern optimization techniques implies only slightly higher computational costs compared to the standard approach without spatial regularization.
Parapharyngeal abscess in an infant is a very rare condition. We present the case of a 4-month-old girl with large masses on the neck’s left side. Computed tomography showed an extensive ...parapharyngeal abscess. Left tonsillectomy was performed under general anesthesia from a transoral approach, followed by an incision and evacuation of the abscess from the parapharyngeal space. Microbiological analysis identified a massive occurrence of Streptococcus intermedius.
Purpose
The study aimed to evaluate audiological benefits, quality of hearing and safety of two Bonebridge generation: BCI601 and BCI602 (MED-EL, Innsbruck, Austria) in children.
Methods
Twelve ...children were implanted: five BCI601 and seven BCI602 comprising of ten conductive hearing loss, and two single sided deaf SSD subjects. Audiological outcomes tested were sound field audiometry, functional gain, speech recognition threshold (SRT50), speech recognition in noise (SPRINT) and localisation abilities. Subjective measures were Speech, Spatial and Qualities of Hearing Scale (SSQ12).
Results
The mean FG with the BCI601 was 25.0 dB and with the BCI602 28.0 dB. The benefit in SRT50 was 23.2 dB and 33.8 dB, respectively. The mean benefit in SPRINT was 15% and 6.7% and the localisation ability improved from 33.3° to 16° and from 26.2° to 17.6°, respectively. The two SSD subjects reported a FG of 17 dB, a benefit in SRT50 of 22.5 and a benefit in SPRINT of 20%. Subjective outcomes improved significantly and even exceeded the values of their age-and sex matched normal hearing peers. One revision was reported: a retroauricular emphysema above the implant occurred 12 months post-OP, it was resolved operatively with the implant still being functional.
Conclusion
The pediatric cohort reports significant audiological benefit, even exceeding that of the age- and sex matched control. The combination of the high safety and audiological benefit makes the Bonebridge a comfortable and effective option in hearing rehabilitation in children.
Retraction pocket (RP) of the tympanic membrane (TM) is a common pathology in children that can cause ossicular chain erosion, cholesteatoma formation, and potentially life-threatening complications ...of cholesteatoma. This study assessed the functional and anatomical results of cartilage grafting in children with severe RP of the TM.
This was a retrospective review of 212 children from a tertiary referral center.
We identified significant differences in hearing results, indication criteria, and location of TM fixation between stages II and III of RP (according to Charachon). We observed a significantly higher incidence of RP in boys than in girls.
Cartilage tympanoplasty for retraction pocket of the tympanic membrane in children is a safe procedure with good anatomical and hearing results.
Bonebridge (BB) is the first active implantation system for bone conduction that is placed fully under the skin. Experience suggests that BB is characterized by low incidence of postoperative ...complications. This case report presents a rare case of a 16-year-old girl with incidence of emphysema occurring over the implant 1 year after operation. We performed a computed tomography scan that showed pockets of gas above the floating mass transducer so we provided the revision surgery and sealed the artificial opening with fat from the earlobe and fibrin glue. Since that time, no air has collected in the retroauricular area and the implant has been fully functional.
The paper deals with the conceptual design of cable-driven parallel robot which will be used for inspection and monitoring tasks in production process. The reason and need of vision based control of ...the production process is described in the introduction. Furthermore, mechanisms with parallel kinematic structure are described, as well as their usage in industry and sports broadcasts. On that basis, there is proposed the conceptual design of the cable driven parallel robot (CDPR) for desired task of visual monitoring of production line. Finally, there is proposed a simulation of designed robotic system and workspace shape analysis.
The article deals with the analysis of the existing full-suspension downhill bicycle’s frame damaged while using and the subsequent conceptual improved design of the critical point. The origin of ...symmetrical and asymmetrical bicycle loads in individual riding modes is investigated. Subsequently, their impact on the overall load of the frame and especially the identified critical point are assessed. An overview of different full-suspension bicycle frames, complemented by a literature overview of research related to cycling engineering and sport application is introduced. The first phase began with a kinematic analysis of the bicycle suspension system and an effect assessment of the symmetrical or asymmetrical distribution of forces, respectively, in the individual components. Furthermore, a strength analysis of the main frame was performed, taking into account the static and dynamic forces. Based on the results of the analyses performed in the ANSYS/Workbench, a critical frame point, as well as the role of individual driving regimes, were identified. The structural detail of the pocket under the saddle tube together with the asymmetrical combined load generated while out of saddle pedalling proved to be crucial for frame crack initiation and formation. Different design variants with improved stiffness were proposed for the given place. The chosen variant can be successfully implemented due to the final reduction of the maximum stress level approximately two times compared to the original pocket (only 50.4% of the original maximum stress) as well as a simple design and repair of the damaged area in terms of technology.
The Bonebridge (BB) was the first active transcutaneous implantation system for bone conduction. The main indications are conductive or mixed hearing loss and single-sided deafness. Treacher-Collins ...syndrome (TCS) is a rare genetic disease that affects craniofacial development. The disorder results in deformations of facial structure including ear malformations, especially microtia and ear canal atresia. These patients suffer from conductive hearing loss. CT scans often show unfavorable temporal bone anatomy making placement of an implant difficult. For implantable hearing rehabilitation, patients may decide for conduction implants, such as a BAHA, a Ponto, a Vibrant Soundbridge, or a Bonebridge. In this case report, we present 2 patients with TCS implanted with the Bonebridge system, their audiological results, and quality of life.
Objectives
The young population requires early rehabilitation of their hearing loss for normal cognitive, auditive hence social development. All of which, in turn, may have an impact on quality of ...life (QoL). This study aims to evaluate QoL between two different bone conduction (BC) hearing devices: a noninvasive adhesive hearing aid (Adhear ADH) vs. an active transcutaneous implant (Bonebridge BB).
Methods
This study composed of 12 BB and 15 ADH users. Pure tone as well as speech in noise and quiet measurements were evaluated and compared to the Assessment in QoL questionnaire (AQoL‐6d).
Results
Freefield results showed significant improvements for both devices compared to the unaided condition (p < .0001). Emphasis needs to be drawn on the different unaided level of conductive hearing loss as well as the indication range for both evaluated device groups: the ADH subjects exhibited a mean BC value of 9.50 ± 7.96 dB HL (the indication range up to 25 dB) and the BB subjects a mean of 23.33 ± 25.66 dB HL (the indication range up to 45 dB). Speech perception in quiet and in noise was significantly improved (p < .05; p < .001, respectively). QoL was significantly improved for both treatments (p < .05) but was not different among the devices, and the values were similar to their normal hearing, age, and sex‐matched control group. High correlations were found between QoL utility scores and improved PTA4 in the aided condition (r2 = .8839 and .7810 for BB and ADH, respectively).
Conclusion
Our results show that both devices offer significant beneficial audiological rehabilitations with significantly increased QoL. However, the underlying condition and the unaided degree of hearing loss, hence the required higher stimulation must be the deciding factor when opting for a hearing device, and this should be independent of age.
Level of evidence
2c.
This study aims to evaluate QoL in two different bone conduction (BC) hearing devices: a noninvasive adhesive hearing aid (Adhear ADH) versus an active transcutaneous implant (Bonebridge BB). QoL was significantly improved for both treatments (p < .05) but was not different among the devices and values were similar to their normal hearing, age‐ and sex‐matched control group. Our results show that both devices offer significant beneficial audiological rehabilitations with significantly increased QoL.
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