Blind deconvolution decreases requirements on temporal resolution of DCE-MRI: Application to 2nd generation pharmacokinetic modeling.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Cartilage tympanoplasty for retraction pocket of the tympanic membrane in children.

Background: 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. Methods: This was a retrospective review of 212 children from a tertiary referral center. Results: 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. Conclusions: Cartilage tympanoplasty for retraction pocket of the tympanic membrane in children is a safe procedure with good anatomical and hearing results.

The ISMRM Open Science Initiative for Perfusion Imaging (OSIPI): Results from the OSIPI-Dynamic Contrast-Enhanced challenge.

PURPOSE: K trans $$ {K}^{\mathrm{trans}} $$ has often been proposed as a quantitative imaging biomarker for diagnosis, prognosis, and treatment response assessment for various tumors. None of the many software tools for K trans $$ {K}^{\mathrm{trans}} $$ quantification are standardized. The ISMRM Open Science Initiative for Perfusion Imaging-Dynamic Contrast-Enhanced (OSIPI-DCE) challenge was designed to benchmark methods to better help the efforts to standardize K trans $$ {K}^{\mathrm{trans}} $$ measurement. METHODS: A framework was created to evaluate K trans $$ {K}^{\mathrm{trans}} $$ values produced by DCE-MRI analysis pipelines to enable benchmarking. The perfusion MRI community was invited to apply their pipelines for K trans $$ {K}^{\mathrm{trans}} $$ quantification in glioblastoma from clinical and synthetic patients. Submissions were required to include the entrants' K trans $$ {K}^{\mathrm{trans}} $$ values, the applied software, and a standard operating procedure. These were evaluated using the proposed OSIP I gold $$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score defined with accuracy, repeatability, and reproducibility components. RESULTS: Across the 10 received submissions, the OSIP I gold $$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score ranged from 28% to 78% with a 59% median. The accuracy, repeatability, and reproducibility scores ranged from 0.54 to 0.92, 0.64 to 0.86, and 0.65 to 1.00, respectively (0-1 = lowest-highest). Manual arterial input function selection markedly affected the reproducibility and showed greater variability in K trans $$ {K}^{\mathrm{trans}} $$ analysis than automated methods. Furthermore, provision of a detailed standard operating procedure was critical for higher reproducibility. CONCLUSIONS: This study reports results from the OSIPI-DCE challenge and highlights the high inter-software variability within K trans $$ {K}^{\mathrm{trans}} $$ estimation, providing a framework for ongoing benchmarking against the scores presented. Through this challenge, the participating teams were ranked based on the performance of their software tools in the particular setting of this challenge. In a real-world clinical setting, many of these tools may perform differently with different benchmarking methodology.

Improvement in quality of life comparing noninvasive versus invasive hearing rehabilitation in children.

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 (r 2 = .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.

Bonebridge Implantation in Treacher-Collins Syndrome With Conductive Hearing Loss-Case Report.

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.

Long-Term Device Satisfaction and Safety after Cochlear Implantation in Children.

(1) Objectives: For full benefit in children implanted with a cochlear implant (CI), wearing the device all waking hours is necessary. This study focuses on the relationship between daily use and audiological outcomes, with the hypothesis that frequent daily device use coincides with high device satisfaction resulting in better functional gain (FG). Confounding factors such as implantation age, device experience and type of device were considered. (2) Results: Thirty-eight CI children (65 ears) were investigated. In total, 76.92% of the children were using their device for >12 h per day (h/d), 18.46% for 9−12 h/d, the remaining for 6−9 h/d and one subject reported 3 h/d. The revision rate up to the 90-month follow-up (F/U) was 4.6%. The mean FG was 59.00 ± 7.67 dB. The Audio Processor Satisfaction Questionnaire (APSQ) separated for single unit (SU) versus behind the ear (BTE) devices showed significantly better results for the latter in terms of wearing comfort (WC) (p = 0.00062). A correlation between device use and FG was found with a device experience of <2 years (n = 29; r2 = 0.398), whereas no correlation was seen with ≥2 years of device experience (n = 36; r2 = 0.0038). (3) Conclusion: This study found significant relationships between daily device use and FG, wearing comfort and long-term safety (90 months).

Fourth branchial cleft anomaly in a 7-month-old infant: A case report and literature review.

Fourth branchial cleft anomalies are rare head and neck congenital lesions seen in children. They present as a neck inflammatory mass and arise essentially on the left side of the neck. We report the case of a 7-month-old female with a mass of the neck associated with respiratory distress. The mass was diagnosed as an incomplete fourth branchial cleft fistula. Surgical revision of the neck abscess from an external approach and plasma coblation of the orifice in the pyriform fossa by an endoscopic approach were performed.

Two Bonebridge bone conduction hearing implant generations: audiological benefit and quality of hearing in children.

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.

Extensive Parapharyngeal Abscess in a 4-Month-Old Infant.

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.

Risk Factors for Postoperative Bleeding after Adenoidectomy.

IMPORTANCE: Postoperative bleeding is a common and potentially life-threatening complication. Precise identification of risk factors in addition to the basic ones, such as coagulation parameters, is certainly very desirable. OBJECTIVE: The aim of this study was to identify other possible risk factors for bleeding after adenoidectomy in children. DESIGN: This observational prospective study enrolled children undergoing adenoidectomy from October 2019 to February 2020, then evaluated the influence of possible risk factors for bleeding. SETTING: Tertiary pediatric otorhinolaryngology center. PARTICIPANTS: A total of 288 children aged 0-18 years undergoing adenoidectomy for recurrent upper respiratory tract infections, recurrent acute otitis media, secretory otitis media, and obstructive sleep apnea syndrome. MAIN OUTCOMES AND MEASURES: Increased blood pressure and time of surgery were identified as risk factors for bleeding after adenoidectomy. RESULTS: Elevated systolic (p = 0.046), diastolic (p = 0.012), and mean arterial blood pressure (p = 0.007) (Mann-Whitney U test) as adjusted for age-specific distributions and with corrections for height and weight, as well as time length of surgery (p < 0.001) (Fisher's exact test) were revealed as statistically significant risk factors for postoperative bleeding. Atmospheric pressure, surgeon's level of experiences, chronic inflammatory content in adenoid vegetation (AV), size of AV, recidivism of AV, recurrent infections of the upper respiratory tract, type of anesthesia, long-term using of drugs, and positive coagulation questionnaire or pathology in standard coagulation tests were not found to be risk factors for bleeding after adenoidectomy. CONCLUSIONS AND RELEVANCE: In this prospective study within a well-defined population of children, we evaluated increased blood pressure and time of surgery as risk factors for bleeding after adenoidectomy. These data bring new information that complements current knowledge in this field.

Retroauricular Emphysema as a Late Complication After Bonebridge Implantation: Case Report.

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.

Spatially regularized estimation of the tissue homogeneity model parameters in DCE-MRI using proximal minimization.

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.

Blind deconvolution estimation of an arterial input function for small animal DCE-MRI.

PURPOSE: One of the main obstacles for reliable quantitative dynamic contrast-enhanced (DCE) MRI is the need for accurate knowledge of the arterial input function (AIF). This is a special challenge for preclinical small animal applications where it is very difficult to measure the AIF without partial volume and flow artifacts. Furthermore, using advanced pharmacokinetic models (allowing estimation of blood flow and permeability-surface area product in addition to the classical perfusion parameters) poses stricter requirements on the accuracy and precision of AIF estimation. This paper addresses small animal DCE-MRI with advanced pharmacokinetic models and presents a method for estimation of the AIF based on blind deconvolution. METHODS: A parametric AIF model designed for small animal physiology and use of advanced pharmacokinetic models is proposed. The parameters of the AIF are estimated using multichannel blind deconvolution. RESULTS: Evaluation on simulated data show that for realistic signal to noise ratios blind deconvolution AIF estimation leads to comparable results as the use of the true AIF. Evaluation on real data based on DCE-MRI with two contrast agents of different molecular weights showed a consistence with the known effects of the molecular weight. CONCLUSION: Multi-channel blind deconvolution using the proposed AIF model specific for small animal DCE-MRI provides reliable perfusion parameter estimates under realistic signal to noise conditions.

A computer-assisted system for handheld whole-breast ultrasonography.

PURPOSE: Breast ultrasonography (US) presents an alternative to mammography in young asymptomatic individuals and a complementary examination in screening of women with dense breasts. Handheld US is the standard-of-care, yet when used in whole-breast examination, no effort has been devoted to monitoring breast coverage and missed regions, which is the purpose of this study. METHODS: We introduce a computer-aided system assisting radiologists and US technologists in covering the whole breast with minimum alteration to the standard workflow. The proposed system comprises a standard US device, proprietary electromagnetic 3D tracking technology and software that combines US visual and tracking data to estimate a probe trajectory, total time spent in different breast segments, and a map of missed regions. A case study, which involved four radiologists (two junior and two senior) performing whole-breast ultrasound in 75 asymptomatic patients, was conducted to test the importance and relevance of the system. RESULTS: The mean process time per breast was [Formula: see text], with no statistically significant difference between the left and the right sides, and slightly longer examination time of junior radiologists. The process time density shows that central parts of the breast have better coverage compared to the periphery. Within the central part, missed regions of minimum detectable size of [Formula: see text] occur in [Formula: see text] of examinations, and non-negligible [Formula: see text] regions occur in [Formula: see text] of cases. CONCLUSION: The results of the case study indicate that missed regions are present in handheld whole-breast US, which renders the proposed system for tracking the probe position during examination a valuable tool for monitoring coverage.

Fast Bayesian JPEG Decompression and Denoising With Tight Frame Priors.

JPEG decompression can be understood as an image reconstruction problem similar to denoising or deconvolution. Such problems can be solved within the Bayesian maximum a posteriori probability framework by iterative optimization algorithms. Prior knowledge about an image is usually described by the l1 norm of its sparse domain representation. For many problems, if the sparse domain forms a tight frame, optimization by the alternating direction method of multipliers can be very efficient. However, for JPEG, such solution is not straightforward, e.g., due to quantization and subsampling of chrominance channels. Derivation of such solution is the main contribution of this paper. In addition, we show that a minor modification of the proposed algorithm solves simultaneously the problem of image denoising. In the experimental section, we analyze the behavior of the proposed decompression algorithm in a small number of iterations with an interesting conclusion that this mode outperforms full convergence. Example images demonstrate the visual quality of decompression and quantitative experiments compare the algorithm with other state-of-the-art methods.

PIZZARO: Forensic analysis and restoration of image and video data.

This paper introduces a set of methods for image and video forensic analysis. They were designed to help to assess image and video credibility and origin and to restore and increase image quality by diminishing unwanted blur, noise, and other possible artifacts. The motivation came from the best practices used in the criminal investigation utilizing images and/or videos. The determination of the image source, the verification of the image content, and image restoration were identified as the most important issues of which automation can facilitate criminalists work. Novel theoretical results complemented with existing approaches (LCD re-capture detection and denoising) were implemented in the PIZZARO software tool, which consists of the image processing functionality as well as of reporting and archiving functions to ensure the repeatability of image analysis procedures and thus fulfills formal aspects of the image/video analysis work. Comparison of new proposed methods with the state of the art approaches is shown. Real use cases are presented, which illustrate the functionality of the developed methods and demonstrate their applicability in different situations. The use cases as well as the method design were solved in tight cooperation of scientists from the Institute of Criminalistics, National Drug Headquarters of the Criminal Police and Investigation Service of the Police of the Czech Republic, and image processing experts from the Czech Academy of Sciences.

Distributed capillary adiabatic tissue homogeneity model in parametric multi-channel blind AIF estimation using DCE-MRI.

PURPOSE: One of the main challenges in quantitative dynamic contrast-enhanced (DCE) MRI is estimation of the arterial input function (AIF). Usually, the signal from a single artery (ignoring contrast dispersion, partial volume effects and flow artifacts) or a population average of such signals (also ignoring variability between patients) is used. METHODS: Multi-channel blind deconvolution is an alternative approach avoiding most of these problems. The AIF is estimated directly from the measured tracer concentration curves in several tissues. This contribution extends the published methods of multi-channel blind deconvolution by applying a more realistic model of the impulse residue function, the distributed capillary adiabatic tissue homogeneity model (DCATH). In addition, an alternative AIF model is used and several AIF-scaling methods are tested. RESULTS: The proposed method is evaluated on synthetic data with respect to the number of tissue regions and to the signal-to-noise ratio. Evaluation on clinical data (renal cell carcinoma patients before and after the beginning of the treatment) gave consistent results. An initial evaluation on clinical data indicates more reliable and less noise sensitive perfusion parameter estimates. CONCLUSION: Blind multi-channel deconvolution using the DCATH model might be a method of choice for AIF estimation in a clinical setup.

The precision of DCE-MRI using the tissue homogeneity model with continuous formulation of the perfusion parameters.

The present trend in dynamic contrast-enhanced MRI is to increase the number of estimated perfusion parameters using complex pharmacokinetic models. However, less attention is given to the precision analysis of the parameter estimates. In this paper, the distributed capillary adiabatic tissue homogeneity pharmacokinetic model is extended by the bolus arrival time formulated as a free continuous parameter. With the continuous formulation of all perfusion parameters, it is possible to use standard gradient-based optimization algorithms in the approximation of the tissue concentration time sequences. This new six-parameter model is investigated by comparing Monte-Carlo simulations with theoretically derived covariance matrices. The covariance-matrix approach is extended from the usual analysis of the primary perfusion parameters of the pharmacokinetic model to the analysis of the perfusion parameters derived from the primary ones. The results indicate that the precision of the estimated perfusion parameters can be described by the covariance matrix for signal-to-noise ratio higher than~20dB. The application of the new analysis model on a real DCE-MRI data set is also presented.

Blind deconvolution in dynamic contrast-enhanced MRI and ultrasound.

This paper is focused on quantitative perfusion analysis using MRI and ultrasound. In both MRI and ultrasound, most approaches allow estimation of rate constants (Ktrans, kep for MRI) and indices (AUC, TTP) that are only related to the physiological perfusion parameters of a tissue (e.g. blood flow, vessel permeability) but do not allow their absolute quantification. Recent methods for quantification of these physiological perfusion parameters are shortly reviewed. The main problem of these methods is estimation of the arterial input function (AIF). This paper summarizes and extends the current blind-deconvolution approaches to AIF estimation. The feasibility of these methods is shown on a small preclinical study using both MRI and ultrasound.

Single-channel blind estimation of arterial input function and tissue impulse response in DCE-MRI.

Multipass dynamic MRI and pharmacokinetic modeling are used to estimate perfusion parameters of leaky capillaries. Curve fitting and nonblind deconvolution are the established methods to derive the perfusion estimates from the observed arterial input function (AIF) and tissue tracer concentration function. These nonblind methods are sensitive to errors in the AIF, measured in some nearby artery or estimated by multichannel blind deconvolution. Here, a single-channel blind deconvolution algorithm is presented, which only uses a single tissue tracer concentration function to estimate the corresponding AIF and tissue impulse response function. That way, many errors affecting these functions are reduced. The validity of the algorithm is supported by simulations and tests on real data from mouse. The corresponding nonblind and multichannel methods are also presented.