Linear and angular measurements of computer-generated models: are they accurate, valid, and reliable?

INTRODUCTION: Traditional advanced imaging modalities such as CT and MRI are limited in their ability to perform accurate linear distance and angular measurements regardless of anatomical orientation. The construction of 3D models has been used to perform anthropometric analyses as well as in the reconstruction of rapid prototypes. We hypothesized that such measurements would be precise to within 2 mm or 2 degrees of measurements performed with a coordinate measurement machine (CMM). We also hypothesized that there would be a high degree of interobserver reliability with these measurements. MATERIALS AND METHODS: Multiple aluminum screws were implanted in various positions in three foam pelvises which were subsequently scanned by CT and rendered as 3D models using a commercially available software package (Mimics). Linear and angular measurements were performed using a CMM machine, the software package, and a dial caliper or goniometer. The deviation of the measurements from the CMM data was compared using ANOVA. The interobserver reliability of both the manual and computer-generated measurements was calculated. RESULTS: The mean difference between the CMM distances and those measured manually and with the software was 2.12 +/- 1.20 mm and 1.57 +/- 1.05 mm, respectively. The mean difference between the CMM angular measurements and the angular measurements performed manually and with the software was 4.07 +/- 4.70 degrees and 1.62 +/- 1.32 degrees, respectively. In all cases, the manual measurements were significantly less accurate (p < 0.0001) and there was a high degree of interobserver reliability. CONCLUSIONS: Computer-generated measurements taken from three-dimensionally reconstructed models are more accurate than manual measurements and are within 2 mm and 2 degrees of measurements performed with a CMM. These measurements have high interobserver reliability.     

FEASIBILITY OF CONDUCTING CARDIOVASCULAR OUTCOME RESEARCH IN AUSTRALIAN GENERAL PRACTICE: RESULTS FROM THE ANBP2 PILOT STUDY

1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial.     

Soft tissue sarcomas of the head and neck in adults

We reviewed the clinical records and pathologic material of 176 adults with primary soft tissue sarcomas treated at Memorial Sloan-Kettering Cancer Center between 1950 and 1985. Seventy-two patients (41%) had low-grade sarcomas and 104 (59%) had high-grade sarcomas. All but 18 patients underwent some form of excision as initial therapy. Adjuvant radiotherapy and chemotherapy combined with surgical excision showed no significant effect. A significantly increased risk of treatment failure was associated with large tumor size, positive surgical margins, bone involvement, local recurrence, metastatic spread, and high histologic grade. Except for recurrence, the p value by univariate analysis in the log-rank test for comparison of survival according to these clinical and pathologic characteristics was p less than 0.0001. Although the overall survival was 75% at 2 years, 55% at 5 years, and 46% at 10 years, only 20% of the patients with high-grade sarcomas were alive 10 years after treatment. Most patients with rhabdomyosarcoma, high-grade peripheral nerve tumor, and high-grade fibrous histiocytoma and all patients with high-grade angiosarcoma died of disease less than 5 years after diagnosis. New therapeutic strategies are needed to improve the survival of adult patients with high-grade soft tissue sarcomas of the head and neck.     

Local Inflammation in Rat Dorsal Root Ganglion Alters Excitability and Ion Currents in Small-diameter Sensory Neurons

Background: Chronic pain conditions may result from peripheral nerve injury, chronic peripheral inflammation, or sensory ganglia inflammation. However, inflammatory processes may also contribute to peripheral nerve injury responses. To isolate the contribution of local inflammation of sensory ganglia to chronic pain states, the authors previously developed a rat model in which long-lasting pain is induced by inflaming sensory ganglia without injuring the neurons. This results in prolonged mechanical pain, local increases in proinflammatory cytokines, increased neuronal hyperexcitability, and abnormal spontaneous activity.

Methods: The authors used whole cell patch clamp in acutely isolated small-diameter neurons to determine how localized inflammation (3-5 days) of L4 and L5 ganglia altered voltage-gated K+ and Na+ currents.

Results: Tetrodotoxin-sensitive Na+ currents increased twofold to threefold in neurons from inflamed ganglia. Tetrodotoxin-resistant Na+ currents increased more than twofold, but only in cells that bound isolectin B4. These increases occurred without shifts in voltage dependence of activation and inactivation. Similar results are seen in models of peripheral inflammation, except for the large magnitudes. Unlike most pain models, localized inflammation increased rather than decreased voltage-gated K+ currents, due to increased amplitudes of the sustained (delayed rectifier) and fast-inactivating transient components. The overall effect in current clamp experiments was an increase in excitability as indicated by decreased rheobase and lower action potential threshold.     

A framework for systematically improving occupational therapy expert opinions on work capacity

Aim:  To present an evidence-based framework to improve the quality of occupational therapy expert opinions on work capacity for litigation, compensation and insurance purposes.
Methods:  Grounded theory methodology was used to collect and analyse data from a sample of 31 participants, comprising 19 occupational therapists, 6 medical specialists and 6 lawyers. A focused semistructured interview was completed with each participant. In addition, 20 participants verified the key findings.
Results:  The framework is contextualised within a medicolegal system requiring increasing expertise. The framework consists of (i) broad professional development strategies and principles, and (ii) specific strategies and principles for improving opinions through reporting and assessment practices.
Conclusions:  The synthesis of the participants' recommendations provides systematic guidelines for improving occupational therapy expert opinion on work capacity.     

SUICIDE ATTEMPT DUE TO METOCLOPRAMIDE-INDUCED AKATHISIA

Akathisia as a side-effect of metoclopramide has received increasing attention in consultation-liaison psychiatry in recent years. A case of metoclopramide-induced akathisia resulting in a suicide attempt is reported in order to highlight the suffering of such patients and the factors that lead to misdiagnosis.     

A comparison of T4:T8 lymphocyte ratio in the periodontal lesion of healthy and HIV-positive patients.

Previous reports describe a characteristic, rapidly progressive, periodontitis that is unique to patients who are seropositive for HIV antibody (Western blot +). The purpose of this study was to compare the T4 and T8 lymphocyte subpopulations in the peripheral blood and periodontal lesions of these HIV patients with those of healthy controls. T-cell subsets in peripheral blood were quantified by flow cytometry. The values from this analysis were used to calculate the peripheral T4:T8 lymphocyte ratio for each patient. Gingival tissue (papilla) was obtained from 8 HIV+ patients and from 6 healthy HIV- control patients during routine gingival surgery. The T-cell subpopulations in the gingival tissue were determined using serial cryostat sections that were labeled with monoclonal antibodies for T4 and T8 cells and developed using an avidin-biotin-peroxidase system. Six sections were taken from each of the 14 tissue specimens (one per patient). The sections were examined at 450 x and the mean number of T4 and T8 cells calculated for each section. These mean values were then used to determine the T4:T8 lymphocyte ratio for each tissue specimen. The peripheral blood analysis revealed a mean serum T4:T8 ratio of (2.07 +/- 0.455) for the controls and (0.58 +/- 0.26) for the HIV patients. The significantly lower T4:T8 ratio in HIV patients is consistent with their diagnosis. Although the results indicated that the mean T4:T8 lymphocyte ratio in the gingiva of controls was highly variable (2.70 +/- 1.344), the gingiva of HIV patients consistently exhibited a complete absence of T-cells.(ABSTRACT TRUNCATED AT 250 WORDS)