Use of an optical surface scanner in assessment of outcome following rhinoplasty surgery.

OBJECTIVE: To demonstrate the use of an optical surface scanner, with associated software, in the assessment of rhinoplasty patients, and to discuss the possible clinical applications of this technology in the future. DESIGN: Case study analysis of pre- and post-operative scans of a patient undergoing septorhinoplasty at Whipps Cross University Hospital, London, UK. SUBJECT: A 21-year-old man undergoing septorhinoplasty underwent pre-operative optical surface scanning of his face. The scans were repeated at one week and one year post-operatively. Software developed at University College London was then used to analyse the scans. RESULTS: The scans clearly showed that the man's dorsal hump had been well reduced and the nose straightened, with a resulting 1600 mm3 gain on the right side and a 1000 mm3 loss on the left side of the nose. Tip projection had also been achieved. CONCLUSION: This technique allowed objective quantification of facial features and analysis of change. It may well prove useful in the future in predicting change following surgical intervention.

MnTMPyP, a metalloporphyrin-based superoxide dismutase/catalase mimetic, protects INS-1 cells and human pancreatic islets from an in vitro oxidative challenge.

AIMS: Pancreatic islets can be lost early following allotransplantation from oxidative stress. Antioxidant enzyme overexpression could confer a beneficial effect on islets exposed to reactive oxygen species (ROS) and nitrogen species. Here, we tested the effect of MnTMPyP, a superoxide dismutase/catalase mimetic. METHODS: INS-1 insulin-secreting cells or human islets were cultured with MnTMPyP and exposed to a superoxide donor (the hypoxanthine/xanthine oxidase (HX/XO) system), a nitric oxide donor [3-morpholinosydnonimine (SIN-1)] or menadione. Viability of INS-1 cells was assessed by WST-1 colorimetric assay and FACS analysis (Live/Dead test). ROS production was determined using fluorescent probes. Islet viability was estimated by WST-1 assay and endocrine function by static incubation. RESULTS: Following MnTMPyP treatment, ROS production in INS-1 cells was reduced by 4- to 20-fold upon HX/XO challenge and up to 2-fold upon SIN-1 stress. This phenomenon correlated with higher viability measured by WST-1 or Live/Dead test. MnTMPyP preserved islet viability upon exposure to SIN-1 or menadione but not upon an HX/XO challenge. Similarly, decrease in insulin secretion tended to be less pronounced in MnTMPyP-treated islets than in control islet when exposed to SIN-1, but no changes were noticed during an HX/XO stress. CONCLUSIONS: MnTMPyP was able to improve the viability of INS-1 cells and human islets exposed to oxidative challenges in vitro. Protection of INS-1 cells could be as high as 90%. This agent is therefore potentially attractive in situations involving the overproduction of ROS, such as islet transplantation.

The transverse pelvic plane: a new and practical reference frame for hip arthroplasty.

Acetabular orientation is a crucial part of the planning and performance of hip arthroplasty. Currently, most surgeons use the anterior pelvic plane (APP) to orient themselves when navigating the acetabulum, despite the fact that the anterior superior iliac spine (ASIS) of the unaffected side is not accessible in the lateral position. We have identified another plane, the transverse pelvic plane (TPP), relying on both posterior superior iliac spines and the ASIS of the affected side. In a CT-based study, this plane was found to be as reliable as the APP for the orientation of the cup in both anteversion and inclination. The substantial variation in both measurements between patients is documented, and their relation to the "safe zone" is shown. We recommend consideration of the TPP by surgeons who perform arthroplasty in the lateral position. It may reduce operating time and improve accuracy in computer-assisted arthroplasty.

Overcoming subjectivity in assessing facial lipoatrophy: is there a role for three-dimensional laser scans?

BACKGROUND: Prevalence and incidence rates of lipodystrophy vary widely and frequently rely upon self- and/or clinician reports. Currently no validated assessment tool for facial lipoatrophy is available. AIMS AND OBJECTIVES: To illustrate that assessment of the severity of facial lipoatrophy by patients and clinicians is subjective. To evaluate the reproducibility of facial three-dimensional surface laser scans. METHODS: Twenty-three HIV-positive men were recruited from an inner London HIV outpatient clinic in September 2001. CD4 count, viral load, antiretroviral history and body mass index were recorded. Patients and clinicians independently assessed the severity of facial lipoatrophy on a four-point scale and the level agreement was measured. Seventeen of the 23 patients (73.9%) underwent two scans 1 week apart, which were then superimposed. The volume difference (mm3) and mean difference (mm) between the scans for five regions of the face were measured and compared with the self-reported grade of facial lipoatrophy. RESULTS: For each pair of clinicians (P=0.03, 0.005 and 0.0002, respectively), and for one patient-clinician pair (P=0.004), there was a significant systematic difference between the two sets of gradings of facial lipoatrophy. The level of disagreement was generally higher for patients reporting facial lipoatrophy (n=17) compared to those not reporting it (n=6). The mean volume difference and mean difference between any region were within 200 mm3 and 0.25 mm, respectively. Reproducibility was unaffected by the self-reported grade of facial lipoatrophy. CONCLUSIONS: Assessment of the severity of facial lipoatrophy by patients and clinicians is subjective. Three-dimensional facial laser scans are reproducible and may provide an objective tool for monitoring changes in facial lipoatrophy.

Study of the three-dimensional geometry of the central conducting airways in man using computed tomographic (CT) images.

Clinical research on the deposition of inhaled substances (e.g. inhaled medications, airborne contaminants, fumes) in the lungs necessitates anatomical models of the airways. Current conducting airway models lack three-dimensional (3D) reality as little information is available in the literature on the distribution of the airways in space. This is a limitation to the assessment or predictions of the particle deposition in relation to the subject's anatomy. Detailed information on the full topology and morphology of the airways is thus required to model the airway tree realistically. This paper presents the length, diameter, gravity, coronal and sagittal angles that together describe completely the airways in 3D space. The angle at which the airways branch out from their parent (branching angle) and the rotation angle between successive bifurcation planes are also included. These data are from the study of two sets of airways computed tomography (CT) images. One CT scan was performed on a human tracheobronchial tree cast and the other on a healthy male volunteer. The airways in the first nine generations of the cast and in the first six conducting generations of the volunteer were measured using a computer-based algorithm. The data contribute to the knowledge of the lung anatomy. In particular, the spatial structure of the airways is shown to be strongly defined by the central airways with clear angular lobar patterns. Such patterns tend to disappear with a mean gravity, coronal and sagittal angles of 90 degrees in each generation higher than 13-15. The mean branching angle per generation appears independent of the lobe to which the airways belong. Non-planar geometry at bifurcation is observed with the mean (+/- SD) bifurcation plane rotation angle of 79 +/- 410 (n = 229). This angle appears constant over the generations studied. The data are useful for improving the 3D realism of the conducting airway structure modelling as well as for studying aerosol deposition, flow and biological significance of non-planar airway trees using analytical and computational flow dynamics modelling.

Evaluation of the accuracy and precision of lung aerosol deposition measurements from single-photon emission computed tomography using simulation.

Single-photon emission computed tomography (SPECT) imaging is being increasingly used to assess inhaled aerosol deposition. This study uses simulation to evaluate the errors involved in such measurements and to compare them with those from conventional planar imaging. SPECT images of known theoretical distributions of radioaerosol in the lung have been simulated using lung models derived from magnetic resonance studies in human subjects. Total lung activity was evaluated from the simulated images. A spherical transform of the lung distributions was performed, and the absolute penetration index (PI) and a relative value expressed as a fraction of that in a simulated ventilation image were calculated. All parameters were compared with the true value used in the simulation, and the errors were assessed. An iterative method was used to correct for the partial volume effect, and its effectiveness in improving errors was evaluated. The errors were compared with those of planar imaging. The precision of measurements was significantly better for SPECT than planar imaging (2.8 vs 6.3% for total lung activity, 6 vs 20% for PI, and 3 vs 6% for relative PI). The method of correcting for the influence of the partial volume effect significantly improved the accuracy of PI evaluation without affecting precision. SPECT is capable of accurate and precise measurements of aerosol distribution in the lung, which are improved compared with those measured by conventional planar imaging. A technique for correcting the SPECT data for the influence of the partial volume effect has been described. Simulation is demonstrated as a valuable method of technique evaluation and comparison.

Semi-automated tabulation of the 3D topology and morphology of branching networks using CT: application to the airway tree.

Detailed information on biological branching networks (optical nerves, airways or blood vessels) is often required to improve the analysis of 3D medical imaging data. A semi-automated algorithm has been developed to obtain the full 3D topology and dimensions (direction cosine, length, diameter, branching and gravity angles) of branching networks using their CT images. It has been tested using CT images of a simple Perspex branching network and applied to the CT images of a human cast of the airway tree. The morphology and topology of the computer derived network were compared with the manually measured dimensions. Good agreement was found. The airways dimensions also compared well with previous values quoted in literature. This algorithm can provide complete data set analysis much more quickly than manual measurements. Its use is limited by the CT resolution which means that very small branches are not visible. New data are presented on the branching angles of the airway tree.

Evaluation of three gamma detectors for intraoperative detection of tumors using 111In-labeled radiopharmaceuticals.

UNLABELLED: Attempts to detect tumors with intraoperative scintillation using tumor-binding radiopharmaceuticals have intensified recently. In some cases previously unknown lesions were found, but in most cases no additional lesions were detected. In this study the physical characteristics of three detector systems and their ability to detect tumors through accumulation of an 111In-labeled radiopharmaceutical were investigated. The first was a sodium iodide (NaI[TI]) detector; the second, a cesium iodide (CsI[TI]) detector; and the third, a cadmium telluride (CdTe) detector. METHODS: A body phantom and tumor phantoms (diameter 5-20 mm) made of water, agarose gel or epoxy with a density and attenuation coefficient similar to those of soft tissue were used to simulate a clinical situation. The activity concentration in the body phantom was based on reported values of 111In-octreotide in normal tissue in humans. The 111In activity concentration in the tumor phantoms varied from 3 to 80 times the 111In activity concentration in the body phantom. Data were processed to determine tumor detection levels. RESULTS: The NaI(TI) detector showed the lowest values for full width at half maximum because this detector had the best collimation, leading to a high ratio between counts from tumor and counts from background, i.e., small tumors could be detected. Because of high efficiency, the CsI(TI) detector sometimes required a somewhat shorter acquisition time to produce a statistically significant difference between tumor phantom and background. For deep-lying tumors the NaI(TI) detector was superior, whereas the CdTe detector was best suited for superficial tumors with a high activity concentration in the underlying tissue. CONCLUSION: At a maximum acquisition time of 30 s, almost all superficial tumors with a diameter of 10 mm or larger were detected if the ratio between the 111In concentration in the tumor and the 111In concentration in the background exceeded 3. However, in clinical situations, biologic variations in the uptake of 111In-octreotide in tumors and in normal tissue makes difficult the determination of a distinct detection level. For such clinical conditions, the NaI(TI) detector is the best choice because it has good resolution despite a lower efficiency. Documentation of detector characteristics is important so that clinicians can make an adequate device in relation to tumor location and receptor expression.