Application of confocal microscopy for surface and volume imaging of solid state nuclear track detectors.

Inhalation of radon gas is considered a risk factor in the development of lung cancer. Solid state nuclear track detectors (SSNTDs) are often used for monitoring radon levels. We have previously shown that 3D imaging can help distinguish real tracks from artefact. In this study, we investigated particle tracks in nine SSNTDs using surface and volume visualisation from confocal microscope imaging. An Olympus LEXT OLS 4000 confocal microscope equipped with the Olympus LEXT Remote Development Kit was used to acquire z-stack images and surface data from the SSNTDs. Surface and volume visualisation analysis methods were developed and applied to examine the data. The mean (standard deviation) depth of 45 tracks from the nine detectors was 9.5 (4.6) µm. The mean difference in track depth using the two analysis techniques was 0.08 µm, thus showing good agreement. Furthermore, volume visualisation should enable assessment of the structure of tracks deep in the detector.

Three-dimensional visualization of dermal skin structure using confocal laser scanning microscopy.

The properties and performance of collagen-based materials may be affected by the collagen fibre bundle pattern, orientation and weave. The aim of this study was to develop and apply methods to visualize the dermis using confocal laser scanning microscopy from thin tissue sections stained with haematoxylin and eosin. The data was processed to allow three-dimensional (3-D) visualization on a PC and using a 3-D immersive technology system. The 3-D visualization of the confocal microscope image stacks allowed the evaluation of the collagen macromolecular structure including the collagen fibre bundles. The methods developed provide a novel way of viewing complex organic structures with further potential applications in the medical field.

A new method of imaging particle tracks in solid state nuclear track detectors.

Solid state nuclear track detectors are used to determine the concentration of alpha particles in the environment. The standard method for assessing exposed detectors involves 2D image analysis. However 3D imaging has the potential to provide additional information relating to angle as well as to differentiate clustered hit sequences and possibly energy of alpha particles but this could be time consuming. Here we describe a new method for rapid high-resolution 3D imaging of solid state nuclear track detectors. A 'LEXT' OLS3100 confocal laser scanning microscope (Olympus Corporation, Tokyo, Japan) was used in confocal mode to successfully obtain 3D image data on four CR-39 plastic detectors. Three-dimensional visualization and image analysis enabled characterization of track features. This method may provide a means of rapid and detailed 3D analysis of solid state nuclear track detectors.

The use of facial anthropometrics in aesthetic assessment.

OBJECTIVE: To identify a valid method for scoring facial aesthetics, correlating clinicians' assessments with measurements taken from 3D facial photographs. DESIGN: Album assessment of facial images, using a visual analog scale of attractiveness and the scores ranked. Facial ratios, obtained following digitization of the images compared with control group mean data, obtained from the Farkas growth study and the differences from the matched mean calculated. Ranked scores compared according to the inclusion of surface as well as caliper (shortest distance) measurements and whether the ranked scores, representing difference to the mean, were weighted. PATIENTS, PARTICIPANTS: Eleven facial images were presented. Seven clinicians provided clinical judgment. MAIN OUTCOME MEASURES: Correlation coefficients between mean attractiveness rankings and summed differences between patients' facial proportions and matched control data from the Farkas growth study. RESULTS: The highest correlation was obtained with the use of the difference accommodating the mean of the Farkas proportion index (r = -.76, p = .006), followed by standard deviation (r = -.65, p = .032), using data in which the difference is weighted according to the magnitude of the linear measurement involved. Repeatability of the clinicians' assessments and operator digitization were validated. CONCLUSIONS: There appears to be potential in the use of the mean as aesthetic ideal as a principle in aesthetic assessment and perhaps as an objective means of outcome assessment after facial surgery. The most appropriate scoring method would seem to include use of both surface and caliper measurements and incorporate weighting.

How should we estimate driving pressure to measure interrupter resistance in children?

Interrupter resistance (R(int)) is a widely used measure of airway caliber, but concerns remain about repeatability and sensitivity. Some R(int) variability may derive from the linear back-extrapolation algorithm (LBE 30/70) usually used to estimate driving pressure. To investigate whether other methods of estimating driving pressure could improve repeatability and sensitivity, we studied 39 children with asthma. Two measurements of R(int)-each the median of 10 interruptions-were made 5 min apart, and 14 children had a third measurement after bronchodilator (R(int)BD). Mouth pressure transients were analyzed using several algorithms, to compare the magnitude, repeatability, and sensitivity to bronchodilator change of R(int) values yielded. Algorithms taking driving pressure from later in the transient, predictably, yielded higher values of R(int) than those which back-extrapolated to time of valve closure. Algorithms which did not rely on back-extrapolation, including mean oscillation pressure (MOP) and mean plateau pressure (MP 30/70) had better repeatability. Sensitivity to detect change, calculated as ratio of bronchodilator response to repeatability coefficient (DeltaR(int)/CR), was also better for non-extrapolating algorithms: MP 30/70 1.67, LBE 30/70 1.28 (P = 0.0004). Measuring R(int) using techniques other than conventional back-extrapolation may give more consistent and clinically useful results, and these approaches merit further exploration.

Comparison of three methods of facial measurement.

The aims of this study were to assess the accuracy of measurements recorded by 3D stereophotogrammetry and to compare three methods of facial measurement: manual anthropometry, 3D stereophotogrammetry and 2D photography. Measurements were taken from 14 landmarks on each of six volunteers and compared. In addition, the variability of the methods was assessed. Three-dimensional measurements were shown to compare well with manual measurements on volunteers as well as test objects for which the mean difference was 0.23 mm (shortest distance) and 0.13 mm (surface). All the three methods of measurement were found to have good levels of repeatability. Two-dimensional measurements were more variable than manual measurements (P=0.021). Three-dimensional stereophotogrammetric measurements were shown to compare well with manual measurements although the values obtained were mostly slightly larger. Stereophotogrammetry allows images to be taken in a Medical Photography Department, facilitating the accurate measurement of facial morphology from digitized data, including changes associated with treatment or growth. There are clear potential benefits of using 3D measurements in the assessment of facial deformity.

MELAS point mutation with unusual clinical presentation.

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder (Pavlakis et al. Advances in Contemporary Neurology. Philadelphia: Davis, 1988: 95-133) and most patients with the typical MELAS phenotype have a point mutation in mitochondrial DNA, an A to G transition at nucleotide 3243 (Goto et al. Nature 1990; 348; 651-653; Koboyashi et al. Biochem Biophys Res Commun 1990; 173: 816-822; Ciafaloni et al. Ann Neurol 1992; 31: 391-398). A 9-yr-old boy presenting with chronic asthma and depression was found to have abnormal mitochondria, partial defects of respiratory chain enzymes, and the MELAS point mutation.

Aminophylline therapy does not improve outcome and increases adverse effects in children hospitalized with acute asthmatic exacerbations.

OBJECTIVE: To evaluate the effects of aminophylline (Am) in children hospitalized with asthma. METHODS: Prospective, randomized, double-blind, placebo-controlled trial. Subjects were children between the ages of 5 and 18 years admitted for asthma exacerbation to either a tertiary care children's hospital or an inner-city general hospital in New York. Exclusion criteria were admission to the intensive care unit, initial theophylline level > 5 micrograms/dL, or the presence of other systemic disorders. All patients received nebulized albuterol therapy and intravenous glucocorticosteroids in standardized doses. Thirty-one patients were randomized to receive either an Am bolus followed by continuous Am infusion or placebo (P) bolus and infusion. The outcome variables were: duration of hospitalization, percent of predicted peak expiratory flow rates recorded at 12-hour intervals, number of albuterol treatments required, and adverse effects. RESULTS: There were no significant differences at study entry in age, sex, race, number of previous hospital admissions, prior medications used, clinical symptom scores, or initial peak flow rates for the two groups. For 26 patients who completed this study, 15 patients in the P group were hospitalized for a mean duration of 2.33 +/- 1.3 days, whereas 11 patients in the Am group required 2.58 +/- 1.5 days. There were no significant differences between the two groups for hospital days, peak flow rates at any time interval, or amount of albuterol therapy required (P > .2). In the Am group, 6 of the 14 patients who entered the study experienced significant adverse effects consisting of nausea, emesis, headache, abdominal pain, and palpitations. Only 1 of 17 patients in the P group had an adverse effect (P < .05). CONCLUSIONS: There is no benefit and considerable risk of adverse effects associated with the use of Am in hospitalized asthmatic children.

A system for computer analysis of cancer cell movement.

BACKGROUND: Motility of cancer cells is a principal cellular parameter, essentially required in the invasion and formation of distant metastasis in human cancer. Measures to stimulate or inhibit motility of cancer cells may play an important part in the understanding of metastasis biology. The aim of this study was to develop a computer system to analyse and evaluate the movement of cells. METHOD: Software was developed which enabled cell boundary definition by specifying salient points around the cell. The position of the centre of area was calculated. Six human cancer cells treated with a motogen and cells without added motogen were analysed by the system. RESULTS: We observed higher velocities and greater variation in area and velocity of the cells treated with HGF/SF motogen compared with control cells. CONCLUSION: The system enables rapid analysis of cell area, velocity and movement, and may thus be of value in further understanding cell motility.

Measurement of forces associated with compression therapy.

Compression therapy is the principal treatment for leg ulcers associated with venous disease. The efficacy of compression therapy can be variable, which may in part be owing to the degree of compression applied. However, if the mechanism of action of this treatment could be better understood, it might be possible to improve its efficacy. It is not clear whether assessment of the degree of compression should be made under static or dynamic conditions, or both. A review of methods used previously suggests the need for a new method of assessment allowing continuous monitoring, even during movement. A system for continuous static and dynamic measurements of compression is described. Using an air chamber and manometer to test the system, agreement within +/- 3 mmHg is observed. The system is applied to investigate changes in forces, expressed as pressure, under bandages and compression stockings. Application of five bandage systems by experienced nurses to a volunteer shows a marked variation in applied pressure. During short periods of walking, rapid changes in pressure under compression stockings are observed, including some transients of less than 0.25 s. The method is simple to apply and may help to understand further the mechanism of action of compression therapy.

Interactive image processing system for assessment of cell movement.

The study of cancer cell motility is considered to be important in understanding cancer metastasis. The movement behaviour of cells within clustered cell colonies is of particular interest. Changes in cell movement, area and velocity can be an indicator of cell spreading. The aim of the study is to develop and apply a computerised interactive image processing system to quantify the movement of cells within cell clusters. A semi-automatic boundary description method based on two-dimensional rendering is devised. The system is later combined with image-processing methods that facilitate the relocation of the cell boundary over time; this forms a new approach to assessing cell movement. These methods are incorporated into a software system, enabling an interactive procedure to define and monitor the movement of single cells in cell clusters from digitised microscope images. Validation of the method shows a maximum error of 10% in defining the area through a cubic spline interpolation. The system is applied to analyse the movement and area of HT115 human colon cancer cells. The system provides tools for the analysis of movement, area and velocity of single cells in cancer cell colonies and may thus be of value in further understanding cancer cell motility.

Quantitative use of photography in orthognathic outcome assessment.

This study reports an independent audit of two aspects of orthognathic surgery, namely control of inter-alar width and mandibular outline asymmetry. Measurements were taken from standardized photographs of a consecutive series of 27 patients, using an on-screen digitizing program (IPTool). All patients had undergone bimaxillary osteotomies involving maxillary impaction and/or advancement, by one surgeon, using a cinch suture for nasal width control. Nine-twelve months after surgery, inter-alar width had increased by just 0.08 cm mean (SD 0.3). Four patients showed an increase of just over 2mm, whilst six showed a small reduction. Based on ratios of size (area) and shape (compactness) of the right and left mandibular segments, there was a small overall improvement in mandibular symmetry (0.019 and 0.005 respectively). Whilst in most of the patients the need for surgery was primarily the correction of antero-posterior and vertical discrepancies, five patients with demonstrable asymmetry showed a clear improvement. In three patients whose asymmetry scores were very mild pre-treatment, there was a small, measured increase in asymmetry, but not to a degree that would be clinically noticeable. At a time when 3D imaging is still unavailable to many clinicians, the results of this study suggest that appropriate measurements taken from carefully standardized conventional photographs can provide a valid and objective means of assessing treatment outcome.

Extracting respiratory data from pulse oximeter plethysmogram traces in newborn infants.

To investigate whether valid respiratory data can be extracted from the pulse oximeter plethysmographic (pleth) trace in healthy newborn infants, pleth data were collected from the foot, and respiratory airflow was simultaneously measured using a facemask. The pleth waveform was analysed using fast Fourier transform (FFT), low-pass filtering (LPF), and by plotting the peak-to-peak amplitude variation (PtP). Using FFT in 14 term infants, the median (range) respiratory rate from the pleth signal was 43 (30-65) breaths/min, and from the flow signal it was 44 (30-67) breaths/min (median difference 0.01 breaths/min, p>0.05). Both LPF and PtP analysis yielded waveforms with a frequency similar to the respiratory rate. Respiratory information, including respiratory rate and a respiratory-like waveform, can reliably be extracted from the pleth trace of a standard pulse oximeter in newborn infants. Such analysis may be clinically useful for non-invasive assessment of respiratory problems in infants and young children.

Measurement and repeatability of interrupter resistance in unsedated newborn infants.

Interrupter resistance (R(int)) is a useful measure of airway caliber in young children, but has not been well characterized in infants-in whom there are concerns about the accurate measurement of driving pressure. This study aimed to assess the feasibility and repeatability of measuring R(int) in unsedated newborn infants, and to explore alternative algorithms for calculating driving pressure. R(int) measurement was attempted in 28 healthy term newborn infants during natural sleep using the MicroRint device. Paired R(int) measurements were achieved in 24 infants, but after screening of waveforms only 15 infants had at least 5 technically acceptable waveforms on both measurements. R(int) values obtained were comparable with reported values for airflow resistance in newborns using other methods. However, the repeatability coefficient (CR) was much higher than reported values in preschool children using standard back-extrapolation algorithms, with CR 2.47 KPa L(-1) sec (unscreened) and 2.93 KPa L(-1) sec (screened). Other algorithms gave only marginally better repeatability, with all CR values over 50% of the mean R(int) value. Using current commercially available equipment, R(int) is too poorly repeatable to be a reliable measurement of airflow resistance in newborn infants. Lower deadspace equipment is needed, but anatomical and physiological factors in the infant are also important.

Radon track imaging in CR-39 plastic detectors using confocal scanning laser microscopy.

Confocal scanning laser microscopy (CSLM) has been used to provide the first images of radon track populations in two external CR-39 plastic detectors. Measurements of variables including track area distribution and estimates of the angle of track inclination (dip) derived from surface CSLM sections are presented. CSLM depth slices, combined with three-dimensional (3D) visualization techniques, provide a new, non-destructive way of examining the 2D and 3D geometry of the etched tracks within solid-state nuclear track detectors that may prove useful in complementing existing optical microscopy methods.

Computer analysis of upper gastrointestinal endoscope images.

Gastro-oesophageal reflux disease (GORD) occurs in up to 40% of adults in the West. Oesophagitis is a major determinant in the treatment of GORD but its current classification systems are subjective. In order to help to provide objective interpretation of upper gastro-intestinal (GI) endoscope examination and reduce inter-observer variability, we developed a computer image analysis system. Digital video recordings were made on patients with clinical evidence of reflux oesophagitis. Cross-sectional profiles of hue and saturation data were analysed on images from seven patients with grade B or C oesophagitis (LA grading). This analysis showed clear changes in hue (p = 0.01) and saturation (p = 0.001). These results suggest that quantification of upper GI endoscopic images is feasible and may help in objective assessment.