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.

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 forK 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 standardizeK trans $$ {K}^{\mathrm{trans}} $$ measurement.

METHODS

A framework was created to evaluateK trans $$ {K}^{\mathrm{trans}} $$ values produced by DCE-MRI analysis pipelines to enable benchmarking. The perfusion MRI community was invited to apply their pipelines forK 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 proposedOSIP I gold $$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score defined with accuracy, repeatability, and reproducibility components.

RESULTS

Across the 10 received submissions, theOSIP 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 inK 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 withinK 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.

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.

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.

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.

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.

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.

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.

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.

Self-compatibility and autonomous selfing of plants in meadow communities

One of the most fundamental, although controversial, questions related to the evolution of plant mating systems is the distribution of outcrossing rates. Self-compatibility, and especially autonomous self-pollination, can become particularly beneficial in anthropogenically degraded habitats with impoverished pollinator assemblages and increased pollen limitation. In a hand-pollination experiment with 46 meadow plants from the Železné hory Mts., Czech Republic, we evaluated the species' ability to adopt different mating systems. For a subset of the species, we also tested seed germination for inbreeding depression. Subsequently, we analysed relationships between the species' mating systems and 12 floral and life-history traits. We found a relatively discrete distribution of the studied species into four groups. Fully and partially self-incompatible species formed the largest group, followed by self-compatible non-selfers and mixed mating species. The germination experiment showed an absence of inbreeding depression in 19 out of 22 examined species. Nectar sugar per flower, nectar sugar per shoot and dichogamy were significant associated with the mating system. Spontaneous selfing ability and self-incompatibility in species of the meadow communities had a discrete distribution, conforming to the general distribution of mating and breeding systems in angiosperms. The low frequency of spontaneous selfers and the lack of inbreeding depression at germination suggest the existence of a selection against selfing at the later ontogenetic stages. Some floral traits, such as the level of dichogamy and amount of nectar reward, may strongly impact the balance between selfing and outcrossing rates in the self-compatible species and thus shape the evolution of mating systems.

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.

Effects of Leukaemia Inhibitory Factor Receptor on the Early Stage of Osteogenic Differentiation of Human Bone Marrow Mesenchymal Cells

Most people worldwide suffer from dental caries. Only a small part of the population is cariesresistant and the reason for this resistance in unknown. Only a few studies compared the saliva protein composition of persons with carious teeth and persons with no caries. Our study is the first to relate proteomic analysis of the caries aetiology with gender. In this study, we compared the differences in the abundances of proteins in the saliva between cariesresistant and caries-susceptible females and males by nano-liquid chromatography-tandem mass spectrometry (Label-Free Quantitative Proteomics). Our results demonstrate that the observed differences in the protein levels might have an influence on anticaries resistance. A total of 19 potential markers of tooth caries were found, for example proteins S100A8 and annexin A1 with higher expression in the cariessusceptible group in comparison with the caries-free group and mucin-5B, lactoferrin, lysozyme C with higher expression in the caries-free group in comparison with the caries-susceptible group. The presented study is the first complex proteomic and gender project where the saliva protein content of caries-free and caries-susceptible persons were compared by label-free MS. The newly detected potential protein markers of dental caries can be a good basis for further research and for possible future therapeutic use.

Epidemiology of selected Mycobacterium tuberculosis complex members in the Czech Republic in 2000-2016

The paper concerns the epidemiology of Mycobacterium tuberculosis complex (MTBC) members except for M. tuberculosis in the Czech Republic in 2000 to 2016. M. bovis was confirmed in 18 patients. M. caprae was diagnosed in two patients in 2001 and 2016 and M. microti in one patient in 2007. M. africanum was detected in one HIV infected woman from Nigeria in 2011. As regards animals, M. pinnipedii was isolated in 2009 from one Southern sea lion (Otaria flavescens) imported from Germany. In 2002, M. caprae was isolated from two Bactrian camels (Camelus ferus) kept in a zoological garden. M. tuberculosis was isolated from one dog in 2004 and from two domestic pigs in 2007. In both cases, the source of M. tuberculosis was an infected patient. Upon examination of 3 727 environmental samples of water and sediments, none of the MTBC members was detected in the stu-died period. Infected persons coming from M. africanum endemic countries (especially West African countries) and infected animals can be considered as the current risk factors for transmission of MTBC species. If the epidemiological situation remains as it is now, there is no risk of transmission of MTBC species via milk or unpasteurised dairy products. Keywords: mycobacterial ecology - domestic and wild animals - food safety.

Decolorization of organic dyes by gold nanoflowers prepared on reduced graphene oxide by tea polyphenols

The green approaches for chemical syntheses are becoming important in various fields comprising chemical synthesis.

Kinetic properties of adenosine triphosphate sulfurylase of intestinal sulfate-reducing bacteria

The investigation of specific activity of ATP sulfurylase and kinetic properties of the enzyme in cell-free extracts of intestinal bacterial strains Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 is presented. The microbiological, biochemical, biophysical and statistical methods were used in the work. The optimal temperature (35°C) and pH 8.0-8.5 for enzyme reaction were determined. An analysis of kinetic properties of ATP sulfurylase has been carried out. Initial (instantaneous) reaction velocity (V0), maximum amount of the product of reaction (Pmax), the reaction time (half saturation period, τ) and maximum velocity of the ATP sulfurylase reaction (Vmax) have been defined. Michaelis constants (Km(Sulfate), Km(ATP), Km(APS), and Km(Pyrophosphate)) of the enzyme reaction were demonstrated for both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains.

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.

[Retinal tamponade with silicone oil - long term results]

AIM

The aim of this study is to evaluate the frequency and efficacy of silicone oil (SO) retinal tamponade in various retinal diseases. The incidence of silicone oil tamponade according to individual indications, incidence of complications and duration of tamponade were evaluated in the study.

MATERIAL AND METHODS

A retrospective study included 510 eyes that were operated on pars plana vitrectomy (PPV) from January 2010 to December 2012. In our group we evaluated 241 men and 189 women, age 4-84 years, mean 62 years . Follow-up period was 12 to 48 months, an average of 27.5 months . We evaluated 253 eyes with diabetic retinopathy, 201 eyes with regmatogenous retinal detachment, 34 eyes with endophthalmitis and 22 eyes after the injury.

RESULTS

In 253 diabetic retinopathy eyes (DR) silicone oil tamponade was indicated in 56 eyes (22.1 %). Silicone oil removal was done on 22 eyes (39.3 %), the average length of SO tamponade was 9.7 months. After SO removal BCVA (best corrected visual acuity) 0,1 and worse had 12 eyes (54,6 %), 0,2 - 0,4 had 5 eyes (22,7 %) and 0,5 or better had 5 eyes (22,7 %). Permanent SO tamponade was left in 34 diabetic retinopathy eyes (60.7 %). Secondary glaucoma (SG) was present in 40 eyes (71.5 %). In 201 retinal detachment (RD) eyes silicone oil tamponade was used in 76 eyes (37.8 %). Secondary glaucoma was present in 31 eyes (40.8 %). Silicone oil was successfully removed in 40 eyes (52.6 %), the average length of tamponade was 9.2 months. In this group BCVA 0,1 and worse had 22 eyes (55,0 %), 0,2 - 0,4 had 15 eyes (37,5 %) and 0,5 or better had 3 eyes (7,5 %). 36 eyes (47,4 %) RD eyes had permanent silicone oil tamponade. In a group of 34 eyes with endophthalmitis SO tamponade was used in 16 eyes (47 %). Secondary glaucoma was present in 3 eyes (18.8 %). Silicone oil removal we did in 11 eyes (68.8 %), the average length of SO tamponade was 5.5 months. After SO removal BCVA 0,1 and worse had 3 eyes (27,2 %), 0,2 - 0,4 had 4 eyes (36,4 %) and 0,5 or better had 4 eyes (36,4 %). 5 eyes (31.2 %) with endophthalmitis had permanent SO tamponade. Out of 22 eyes with eye injuries SO tamponade was used in 14 eyes (63.6 %). 5 eyes (35.7 %) had secondary glaucoma. In 9 eyes (64.3 %) silicone oil was removed, the average length of tamponade was 9.1 months. In this group BCVA 0,1 and worse had 6 eyes (66,7 %), 0,2-0,4 had 1 eye (11,1 %) and 0,5 or better had 2 eyes (22,2 %). Permanent silicone oil tamponade had 5 eyes (35,7 %). In group of 56 phakic eyes (100 %) with silicone oil tamponade we followed cataract progression. 26 eyes (40 %) had cataract surgery in 6 month follow up, 47 eyes (72.3 %) in 1 year follow up and 57 eyes (87.7 %) had cataract surgery in 3 years follow up.

CONCLUSION

Silicone oil tamponade is the method of choice for long-term and stable retinal tamponade, which is important for good functional outcomes of the surgical intervention. The silicone oil tamponade of the retina is nowadays irreplaceable, despite of its potential risks and complications.

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.

[Surgical treatment of the idiopatic macular hole - our experience]

AIM

To evaluate the results of the idiopathic macular hole (IDM) surgical treatment. Surgery included pars plana vitrectomy (PPV) with the removal (peeling) of internal limiting membrane (ILM) and intraocular tamponade with a diluted expanding gas.

MATERIAL AND METHODS

A retrospective study included 100 eyes of 96 patients (10 men and 86 women) with IDM, that were operated at II. Eye Clinic SZU in Banska Bystrica from August 2008 to August 2012. Patients age ranged from 48 to 86 years, average 69.3 years. Mean follow-up time was 39.2 months. All patients underwent PPV with the ILM peeling. Intraocular air tamponade was used in 1-case, 16 % SF6 84-times and 12 % C3F8 15 times.

RESULTS

Anatomical success of the operation was evaluated with OCT examination. After primary operation there were 92 (92 %) closed macular holes in our study. In 6 patients (6 %), we decided to reoperate with gas tamponade (SF6 2-times, C3F8 4 times). After the reoperations final anatomical success in our study was 97 eyes (97 %). Functional results we examined with Snellen. Improved best corrected visual acuity (BCVA) was observed in 85 eyes (85 %), no changes in 11 eyes (11 %), and deterioration in 4 eyes (4 %). Improvement in vision was following: 1 line - 18 eyes, 2 lines - 20 eyes, 3 lines - 18 eyes, 4 lines - 11 eyes, 5 or more lines in 18 eyes.

CONCLUSION

Pars plana vitrectomy with ILM peeling and gas tamponade is highly effective and safe treatment of idiopathic macular hole.Key words: idiopathic macular hole, pars plana vitrectomy, expanding gas.