Anatomy structure creation and editing using 3D implicit surfaces.

PURPOSE: To accurately reconstruct, and interactively reshape 3D anatomy structures' surfaces using small numbers of 2D contours drawn in the most visually informative views of 3D imagery. The innovation of this program is that the number of 2D contours can be very much smaller than the number of transverse sections, even for anatomy structures spanning many sections. This program can edit 3D structures from prior segmentations, including those from autosegmentation programs. The reconstruction and surface editing works with any image modality. METHODS: Structures are represented by variational implicit surfaces defined by weighted sums of radial basis functions (RBFs). Such surfaces are smooth, continuous, and closed and can be reconstructed with RBFs optimally located to efficiently capture shape in any combination of transverse (T), sagittal (S), and coronal (C) views. The accuracy of implicit surface reconstructions was measured by comparisons with the corresponding expert-contoured surfaces in 103 prostate cancer radiotherapy plans. Editing a pre-existing surface is done by overdrawing its profiles in image views spanning the affected part of the structure, deleting an appropriate set of prior RBFs, and merging the remainder with the new edit contour RBFs. Two methods were devised to identify RBFs to be deleted based only on the geometry of the initial surface and the locations of the new RBFs. RESULTS: Expert-contoured surfaces were compared with implicit surfaces reconstructed from them over varying numbers and combinations of T/S/C planes. Studies revealed that surface-surface agreement increases monotonically with increasing RBF-sample density, and that the rate of increase declines over the same range. These trends were observed for all surface agreement metrics and for all the organs studied-prostate, bladder, and rectum. In addition, S and C contours may convey more shape information than T views for CT studies in which the axial slice thickness is greater than the pixel size. Surface editing accuracy likewise improves with larger sampling densities, and the rate of improvement similarly declines over the same conditions. CONCLUSIONS: Implicit surfaces based on RBFs are accurate representations of anatomic structures and can be interactively generated or modified to correct segmentation errors. The number of input contours is typically smaller than the number of T contours spanned by the structure.

Diabetes self-care activities: a community-based survey in urban southern India.

BACKGROUND: Diabetes is a lifestyle disease and can be successfully managed by good self-care activities such as diet, exercise, monitoring and drug adherence. Adequate baseline information about the prevalence of good self-care activities is not available from India. We aimed to estimate the existing self-care behaviours and factors influencing these behaviours among adult patients with type 2 diabetes in urban southern India. METHODS: A cross-sectional survey was conducted using a cluster design in an urban community in southern India. The Summary Diabetes Self-Care Activities questionnaire was used to collect information on diet, exercise, monitoring of blood sugars and adherence to drugs. Risk factors such as marital status, socioeconomic status, depression, benefit-finding and duration of illness, which are likely to influence self-care behaviour, were assessed. RESULTS: Good dietary behaviour was present in 29% (95% CI 20.8%-37.2%), good exercise behaviour in 19.5% (95% CI 17.4%-21.6%), regular blood sugar monitoring in 70% (95% CI 62.2%-77.8%) and drug adherence in 79.8% (95% CI 75.1%-84.5%). Being male (OR 3.38; 95% CI 1.541-7.407) and married (OR 5.60; 95% CI 1.242-25.212) significantly favoured good exercise behaviour. Being married (OR 2.322; 95% CI 1.104-4.883) and belonging to the higher socioeconomic status (OR 2.713; 95% CI 1.419-5.190) were significantly associated with monitoring of blood sugars. CONCLUSIONS: Self-care activities with respect to diet and exercise are poor in the population studied. The self-care activities relating to blood sugar monitoring and drug adherence are good. Improving self-care behaviour among patients with diabetes in India should start with adequate targeted health education.

Frontal sinus surgery and sinus distribution of nasal irrigation.

BACKGROUND: Effective mucus lavage and delivery of topical pharmaceuticals are central to successful management of chronic rhinosinusitis (CRS). The frontal sinus remains difficult to penetrate with topical therapies. This study evaluates the benefit of Draf III frontal dissection compared to traditional Draf IIa for distribution of topical therapies. METHODS: Fresh human cadaver heads were dissected sequentially with Draf IIa frontal sinusotomy and then Draf III procedures. Each cavity was irrigated with pediatric (120 mL) and adult (240 mL) irrigation bottles with 1/1000 10% fluorescein-labeled free water in 2 fixed positions (vertex and Frankfort horizontal). An endoscope at a fixed position within the frontal sinus recorded frontal sinus and frontal recess penetration. The images then underwent blinded evaluation of fluid distribution scored as 0 to 4 (nasal cavity only, frontal recess, medial one-half, lateral one-half, and lavage). Ordinal distribution score was analyzed with Kendall's tau-b. RESULTS: Eight specimens (age 76 ± 11.2 years; 50% female) were assessed. Draf III was superior to Draf IIa in ability to achieve frontal sinus distribution of irrigation (90.6% vs 50.1%, p < 0.001). Vertex head position improved distribution (90.6% vs 50.1%, p < 0.001), was synergistic with Draf III (100% with 87.5% lavage, p < 0.001), but was unable to overcome Draf IIa (81.2% with 25% lavage, p < 0.001). Irrigation volume trended toward improved distribution with larger volume irrigations. CONCLUSION: Successful treatment of sinonasal disease may require postoperative delivery of topical therapies. Draf III frontal sinusotomy achieves superior topical access, and access to the frontal sinus with Draf IIa appears limited, despite large volumes and positioning.

A comparison of the efficacy of two ear drop preparations ('Audax' and 'Earex') in the softening and removal of impacted ear wax.

Thirty-six patients with symptoms of impacted ear wax were recruited to an open, randomized, parallel group study of 'Audax' ear drops and 'Earex' ear drops. Patients had had their symptoms for several weeks and they were assessed on entry for the degree of impaction in each ear. After using the drops, morning and evening for 4 days, they were assessed on the fifth day for degree of impaction, ease of syringing, side-effects or discomfort, and the investigator's and patient's own global impression of efficacy of the ear drops. A trend was seen showing less impaction post-treatment in the 'Audax' group than in the 'Earex' group although the difference did not reach statistical significance. A significant difference was seen in favour of 'Audax' for the frequency and ease of syringing (p < 0.005). No patients in the 'Audax' group reported any side-effect or discomfort although 1 patient using 'Earex' reported slight irritation whilst another found the smell unacceptable. The results of the investigators' and patients' own global impression of efficacy were significantly in favour of 'Audax' ear drops (p < 0.01).

Controlled-release indomethacin and sustained-release diclofenac sodium in the treatment of rheumatoid arthritis: a comparative controlled clinical trial.

The efficacy and tolerability of a new, controlled-release indomethacin (75 mg) tablet was compared to that of a sustained-release diclofenac sodium (100 mg) tablet in 84 patients with rheumatoid arthritis. The study was designed as a double-blind, double-dummy crossover trial, patients being allocated at random to receive 1 active tablet and 1 placebo tablet of the alternative medication at night for 4 weeks before being crossed over to the alternative treatment for a further 4 weeks. Patient and clinical assessments on entry and at the end of each treatment period showed that pain scores for day and night, duration of morning stiffness, requirement for escape analgesia (paracetamol) and treatment preference were similar for both treatments. Both preparations also significantly improved the degree of joint tenderness compared to baseline (p less than 0.001), as measured by a modified Ritchie Articular Index. Incidence and severity of side-effects were comparable, with a significant improvement in degree of constipation reported for both treatments compared to baseline (p less than 0.05). The incidence and severity of headache was statistically significantly worse (p less than 0.05) for controlled-release indomethacin; however, there was no difference in any other parameter of tolerability. It was concluded that controlled-release indomethacin tablets (75 mg) given as a single night-time dose were as efficacious and well tolerated as sustained-release diclofenac sodium (100 mg).

Region segmentation using information divergence measures.

Image segmentations based on maximum likelihood or maximum a posteriori analyses of object textures usually assume parametric models (e.g., Gaussian) for distributions of these features. For real images, parameter accuracy and model stationarity may be elusive, so that model-free inference methods ought to have an advantage over those that are model-dependent. Functions of the relative entropy (RE) from information theory can produce minimum error, model-free inferences, and can detect the boundary of an image object by maximizing the RE between the pixel distributions inside and outside a flexible curve contour. A generalization of the RE -- the Jensen-Rényi divergence (JRD) -- computes optimal n-way decisions and can contour multiple objects in an image simultaneously. Seed regions expand naturally and multiple contours tend not to overlap. An edge detector based on the JRD, combined with multivariate pixel segmentation, generally improved the error of the segmentation. We apply these functions to contour patient anatomy in X-ray computed tomography for radiotherapy treatment planning.

Laryngotracheal stenosis and airway surgery--an outcomes based approach.

OBJECTIVES: To review the outcomes of endoscopic, open or a combination of both surgical modalities for laryngotracheal stenosis and establish which factors influence results. METHODS: Records of all children undergoing laryngotracheal procedures (excluding laryngomalacia and aspirated foreign bodies) by the Department of Otolaryngology at The Children's Hospital at Westmead between January 2003 and November 2011 were reviewed. Specific data on population, intervention, covariates and outcomes were recorded and analysed. RESULTS: A total of 104 patients undergoing 277 procedures were included. 211 (76%) of the procedures were endoscopic, remaining 66 (24%) open. Patients undergoing open surgery were more likely to have significant co-morbidity, prior intubation, require ICU admission or tracheostomy and have a longer hospital stay. 57 (54.8%) patients were successfully treated with a single procedure (48 endoscopic and 9 open). Of the endoscopic patients requiring further surgery, 16 were managed with multiple endoscopic procedures, whilst 12 underwent subsequent open procedures. Open surgery was performed on 66 patients, 63.6% (42/66) of all open procedures required further endoscopic intervention and 45.2% (19/42) of these avoided further open surgery. CONCLUSIONS: Both open and endoscopic surgery have a role in laryngotracheal stenosis, and many patients benefit from a combination of both. Ultimately the decision depends on experience of the treating team, social considerations, and institutional capabilities. A multi-centre prospective data collection would be a useful tool to further investigate optimal management approach.

Clinical validation of atlas-based auto-segmentation of multiple target volumes and normal tissue (swallowing/mastication) structures in the head and neck.

PURPOSE: To validate and clinically evaluate autocontouring using atlas-based autosegmentation (ABAS) of computed tomography images. METHODS AND MATERIALS: The data from 10 head-and-neck patients were selected as input for ABAS, and neck levels I-V and 20 organs at risk were manually contoured according to published guidelines. The total contouring times were recorded. Two different ABAS strategies, multiple and single subject, were evaluated, and the similarity of the autocontours with the atlas contours was assessed using Dice coefficients and the mean distances, using the leave-one-out method. For 12 clinically treated patients, 5 experienced observers edited the autosegmented contours. The editing times were recorded. The Dice coefficients and mean distances were calculated among the clinically used contours, autocontours, and edited autocontours. Finally, an expert panel scored all autocontours and the edited autocontours regarding their adequacy relative to the published atlas. RESULTS: The time to autosegment all the structures using ABAS was 7 min/patient. No significant differences were observed in the autosegmentation accuracy for stage N0 and N+ patients. The multisubject atlas performed best, with a Dice coefficient and mean distance of 0.74 and 2 mm, 0.67 and 3 mm, 0.71 and 2 mm, 0.50 and 2 mm, and 0.78 and 2 mm for the salivary glands, neck levels, chewing muscles, swallowing muscles, and spinal cord-brainstem, respectively. The mean Dice coefficient and mean distance of the autocontours vs. the clinical contours was 0.8 and 2.4 mm for the neck levels and salivary glands, respectively. For the autocontours vs. the edited autocontours, the mean Dice coefficient and mean distance was 0.9 and 1.6 mm, respectively. The expert panel scored 100% of the autocontours as a "minor deviation, editable" or better. The expert panel scored 88% of the edited contours as good compared with 83% of the clinical contours. The total editing time was 66 min. CONCLUSION: Multiple-subject ABAS of computed tomography images proved to be a useful novel tool in the rapid delineation of target and normal tissues. Although editing of the autocontours is inevitable, a substantial time reduction was achieved using editing, instead of manual contouring (180 vs. 66 min).

Atlas-based auto-segmentation of head and neck CT images.

Treatment planning for high precision radiotherapy of head and neck (H&N) cancer patients requires accurate delineation of many structures and lymph node regions. Manual contouring is tedious and suffers from large inter- and intra-rater variability. To reduce manual labor, we have developed a fully automated, atlas-based method for H&N CT image segmentation that employs a novel hierarchical atlas registration approach. This registration strategy makes use of object shape information in the atlas to help improve the registration efficiency and robustness while still being able to account for large inter-subject shape differences. Validation results showed that our method provides accurate segmentation for many structures despite difficulties presented by real clinical data. Comparison of two different atlas selection strategies is also reported.