Saddle nose deformity and septal perforation in granulomatosis with polyangiitis.

BACKGROUND: Patients who have granulomatosis with polyangiitis (GPA, syn. M. Wegener) often develop an external nose deformity which may have devastating psychological effects. Therefore, reconstruction of nasal deformities by rhinoplasty may become necessary to achieve a normal appearance. OBJECTIVE OF REVIEW: The aim of this systematic review was to investigate the efficacy and safety of surgical reconstruction in external nasal deformities and septal perforation in GPA patients. SEARCH STRATEGY: A systematic literature search with defined search terms was performed for scientific articles archived in the MEDLINE-Database up to 10 June 2016 (PubMed Advanced MEDLINE Search), describing management of cases or case series in GPA patients with saddle nose deformity and/or septal perforation. RESULTS: Eleven of 614 publications met the criteria for this analysis including 41 GPA patients undergoing external nasal reconstruction and/or septal reconstruction with a median follow-up of 2.6 years. Overall, saddle nose reconstruction in GPA patients is safe even if an increased rate of revision surgery has to be expected compared with individuals without GPA undergoing septorhinoplasty. Most implanted grafts were autografts of calvarial bone or costal cartilage. For septal perforation reconstruction, few studies were available. Therefore, based on the available data for surgical outcomes, it is impossible to make evidence-based recommendations. All included GPA patients had minimal or no local disease at the time of reconstructive surgery. Therefore, the relationship between disease activity and its impact on surgical outcomes remains unanswered. The potential impact of immune-modulating medications on increased complication rates and the impact of prophylactic antibiotics are unknown. CONCLUSIONS: This study systematically reviews the efficacy and safety of surgical reconstruction of external nasal deformities in GPA patients for the first time. Saddle nose reconstruction in GPA patients with minimal or no local disease is a safe procedure despite an increased rate of revision surgery. Further research is required regarding the impact of antibiotic prophylaxis, immune-modulating therapy, long-term outcomes and functional outcomes measured with subjective and objective parameters.

Factors that influence beverage choices at meal times. An application of the food choice kaleidoscope framework.

Beverages are consumed at almost every meal occasion, but knowledge about the factors that influence beverage choice is less than for food choice. The aim of this research was to characterize and quantify factors that influence beverage choices at meal times. Insights into what beverages are chosen by whom, when and where can be helpful for manufacturers, dieticians/health care providers, and health policy makers. A descriptive framework - the food choice kaleidoscope (Jaeger et al., 2011) - was applied to self-reported 24h food recall data from a sample of New Zealand consumers. Participants (n=164) described 8356 meal occasions in terms of foods and beverages consumed, and the contextual characteristics of the occasion. Beverage choice was explored with random-parameter logit regressions to reveal influences linked to food items eaten, context factors and person factors. Thereby this study contributed to the food choice kaleidoscope research approach by expressing the degree of context dependency in the form of odds ratios and according significance levels. The exploration of co-occurrence of beverages with food items suggests that beverage-meal item combinations can be meal specific. Furthermore, this study integrates psychographic variables into the 'person' mirror of the food choice kaleidoscope. A measure of habit in beverage choice was obtained from the inter-participant correlation.

On few-view tomographic reconstruction with megavoltage photon beams.

Currently portal imaging devices are used to obtain information on patient localization during radiation therapy treatments. Such obtained information is two dimensional in nature, limited to the plane of the captured image. It has been proposed that megavoltage computed tomography images be reconstructed to overcome this limitation. This study explores the feasibility of reconstructing tomographic images from fan-beam projection data acquired with a commercial portal imaging device on a standard radiotherapy linear accelerator. Several CT reconstruction algorithms are examined as to their performance and suitability for applications in radiation therapy verification. The results show that it is possible, using some of the iterative reconstruction techniques, to obtain an image useful for patient localization from only several (< or =10) projection views.

Application of a fuzzy pattern classifier to decision making in portal verification of radiotherapy.

With the large volume of electronic portal images acquired and stringent time constraints, it is no longer feasible to follow the convention whereby the radiation oncologist reviews and approves or rejects all portals. For that purpose we have developed a portal image classifier based on the fuzzy k-nearest neighbour (k-NN) algorithm. Each portal image is represented by a feature vector that consists of translational and rotational errors in the placement of radiation field borders that were measured in the portal image. Memberships in the acceptable portal class for the reference portal images within a training dataset were defined by a radiation oncologist expert. The fuzzy k-NN portal image classifier was trained and tested on a dataset of 328 portal images acquired during tangential irradiations of the breast. The memberships in the acceptable portal class produced by the fuzzy k-NN algorithm agreed very well with those defined by the expert. The linear correlation coefficient was equal to 0.89. Performance of the fuzzy k-NN classifier was also evaluated from the portal decision-making point of view using the measures of accuracy, sensitivity and specificity. The fuzzy k-NN portal classifier was capable of identifying almost all the truly unacceptable portals with an acceptably low false alarm rate.

An image registration scheme applied to verification of radiation therapy.

The introduction of modern conformal radiation therapy techniques requires high geometric precision in treatment delivery which must be verified. For that purpose we have developed an automated system based on registration of portal and simulation (or planning) image pairs. The image registration is performed on anatomical features which are automatically extracted from the portal image. The portal image is then registered with a planning or simulation radiographic image which represents the geometric prescription for the treatment, using an optimized version of the chamfer matching algorithm. Subsequently, the magnitude of the radiation field displacement during treatment is measured by registering the prescribed and treated field boundaries. Algorithms based on chamfer matching and polygon matching have been used for the field boundary registration. Performance of the entire scheme was evaluated on a series of 15 portal images of a pelvic phantom representing various known degrees of the radiation field displacement. The measurements of the radiation field displacements performed by the automated system proved very reliable and after correction for systematic bias agreed to within 1.5 mm or 1 degree with the displacements applied. Second test series involved comparisons between the automated registrations and those performed manually/visually by an experienced human observer, on 31 portal images acquired during treatments of 18 pelvic patients. These tests showed close agreement (in 80% of cases discrepancies were smaller than 1.5 mm or 1.5 degrees) between the automated scheme and the human observer. It is concluded that the developed scheme would be suitable for online geometric verification of radiation therapy treatments.

Quantitative vs. subjective portal verification using digital portal images.

PURPOSE: Off-line, computer-aided prescription (simulator) and treatment (portal) image registration using chamfer matching has been implemented on PC based viewing station. The purposes of this study were (a) to evaluate the performance of interactive anatomy and field edge extraction and subsequent registration, and (b) to compare observer's perceptions of field accuracy with measured discrepancies following anatomical registration. METHODS AND MATERIALS: Prescription-treatment image pairs for 48 different patients were examined in this study. Digital prescription images were produced with the aid of a television camera and a digital frame grabber, while the treatment images were obtained directly from an on-line portal imaging system. To facilitate perception of low contrast anatomical detail, on-line portal images were enhanced with selective adaptive histogram equalization prior to extraction of anatomical edges. Following interactive extraction of anatomical and field border information by an experienced observer, the identified anatomy was registered using chamfer matching. The degree of conformity between the prescription and treatment fields was quantified using several parameters, which included relative prescription field coverage and overcoverage, as well as the translational and rotational displacements as measured by chamfer matching applied to the boundaries of the two fields. These quantitative measures were compared with subjective evaluations made by four radiation oncologists. RESULTS: All the images in this series that included a range of the most commonly seen treatment sites were registered and the conformity parameters were found. The mean treatment/prescription field coverage and overcoverage were approximately 95 and 7%, respectively before registration. The mean translational displacement in the transverse and cranio-caudal directions were 2.9 and 3.4 mm, respectively. The mean rotational displacement was approximately 2 degrees. For all four oncologists, the portals classified as unacceptable, in terms of the field placement, exhibited significantly higher (p < 0.03) translational errors in the transverse direction. The field coverages were significantly lower (p < 0.05) and the translational errors in the cranio-caudal direction were significantly higher (p < 0.05) for the portals rated as unacceptable by two of the oncologists. CONCLUSIONS: From the parameters that were used to quantify the degree of conformity between the prescription and treatment fields, the translational error in the transverse direction correlated best with the oncologists' assessments on the field placement. Field coverage and translational error in the cranio-caudal direction correlated well with assessments of only two out of the four participating oncologists. This can be explained by the fact that for the majority of treatment sites included in the study the positioning of field borders was more critical for the transverse direction. A conclusion for the design of future quantitative and automated on-line portal verification systems is that they will have to model different perceived significances of different types of localization errors intrinsic to oncologist evaluation of portal images.

A polygon matching algorithm and its applications to verification of radiation field placement in radiotherapy.

An automated method for quantitative evaluation of geometric accuracy of radiation field placement during radiation therapy treatments has been developed and is presented in this article. The method is based on matching polygons representing the boundaries of the prescribed and treated radiation fields. An efficient algorithm for finding the intersection of two arbitrary simple polygons has been developed for that purpose. The process of polygon matching is performed by iterative optimization of the goodness-of-match measure derived from the area of the intersection between the two polygons to be matched. The optimization is done with respect to the translation and rotation in the plane that are applied to the polygon representing the treated field. The optimum translation and rotation define the adjustments in the position of the treated field, relative to the patients anatomy, which are necessary in order to bring the treated field into the best possible agreement with the prescription. The radiation field matching scheme was applied to a clinical dataset consisting of prescription-treatment field pairs extracted from simulation and portal images for 40 patients. It is concluded that the observed accuracy and efficiency of the method make it very suitable for applications in radiation therapy verification.

Segmented chamfer matching for the registration of field borders in radiotherapy images.

Optimum conformity between treated and prescribed radiotherapy fields is likely to be achieved when the full versatility of modern therapy equipment is reflected in the field registration method. To allow for independent jaws and custom shielding, chamfer matching has been used to register selected segments of field borders independently. In a study involving 50 clinical prescription-treatment field pairs it is shown that segmented chamfer matching is superior not only to conventional unsegmented chamfer matching but also to several other methods. An example of the clinical value of segmented chamfer matching applied to electronic portal images is given.

The investigation and rectification of field placement errors in the delivery of complex head and neck fields.

PURPOSE: To evaluate a novel technique for resolving field placement errors into their components and to quantify the improvement in accuracy potentially achievable by translation and rotation of the radiation beam. METHODS AND MATERIALS: One hundred and eighty-five films (both simulator and portal) from seventeen patients receiving radiotherapy to the head and neck region were analyzed in pairs. The computer based comparisons of complex fields with curved edges employed the intersections of perpendiculars from two reference points with the field periphery to define field match points. Field placement errors were resolved into those due to patient motion within the immobilization shell and those due to incorrect beam position, orientation, or shape. RESULTS: The median and the 95 percentile of the distribution of differences between prescribed (simulator) fields and treated (portal) fields referenced to the patients anatomy were 4.4 mm and 8.9 mm, respectively. The analysis suggests that with appropriate translation and rotation of the beam with respect to the immobilization shell these figures could be reduced to 3.1 mm and 8.2 mm, respectively, confirming the large contribution of patient motion within the shell to field placement accuracy. Comparisons between treated fields indicated smaller variability during treatment than between simulation and treatment. CONCLUSION: The perpendicular intersection method described here was found appropriate for the identification of field match points. The distributions of field placement errors were similar to those in a published study of straight edged fields. Translation and rotation of the applied field with respect to the immobilization shell would generally result in only a small improvement in field placement accuracy.

Sizes and sources of field placement error in routine irradiation for prostate cancer.

Discrepancies between prescribed and treated field edges have been measured from 76 film pairs taken on 29 patients being treated for prostate cancer. The distribution of field edge discrepancies is described by a standard deviation of 4.5 mm and has an average absolute value of 3.5 mm. The observed discrepancies are shown to be attributable to field position errors and hence, in principle, are easily rectifiable.

On the mode of action of antiphlogistically active DL-omega-phenyl amino acid esters.

DL-omega-phenyl amino acid esters turned out to be inhibitors of the sheep vesicular gland prostaglandin H synthase in addition to their antiphlogistic action on the carrageenan-induced oedema of the rat paw and weak antihistaminic actions. The inhibition of the prostaglandin H synthase was dose-dependent, the inhibitory potencies were however much lower than that of indomethacin. Some but not all derivatives, such as DL-4-amino-4-phenylbutyric acid octyl ester, also caused inhibition of the pure lipoxygenase from rabbit reticulocytes and the conversion of arachidonic acid to leukotriene B4 and 5S-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid by human polymorphonuclear leukocytes as well as inhibition of antigen-induced release of histamine from mast cells of ovalbumin-sensibilized rats. Since no clear relations between the data of the in vitro and in vivo models were obtained, further studies on the pharmacokinetics and possible biotransformations are required.

[Water binding of adsorptive immobilized lipases]. / Zur Wasserbindung adsorptiv immobilisierter Lipasen.

It is supposed that not only the total water content of lipase preparations but more their state of water binding is of technological importance in enzymatic interesterification reactions in systems nearly free from water. The isotherms at 65 degrees C of two microbial lipases immobilized on various adsorbents as well as different adsorbents themselves are shown. The water binding capacity in the range of water content of technological interest decreases from the anion exchange resin Amberlyst A 21 via nonpolar adsorbent Amberlite XAD-2 to kieselguhr Celite 545. It is demonstrated that water binding by lipases is depending on temperature but is also affected by adsorptive immobilization. Adsorptive immobilized lipases show hysteresis, which is very important for preparing a definite water content of the enzyme preparations.