Magnetic resonance spectroscopy of the brain: review of metabolites and clinical applications

Magnetic resonance imaging (MRI) provides anatomic images and morphometric characterization of disease, whereas magnetic resonance spectroscopy (MRS) provides metabolite/biochemical information about tissues non-invasively in vivo. MRS has been used clinically for more than two decades. The major applications of this advanced MRI tool are in the investigation of neurological and neurosurgical disorders. MRS has also been used in the evaluation of the prostate gland and muscle tissue, but these applications will not be addressed in this review. The aim of this review is to attempt to introduce the technique, review the metabolites and literature, as well as briefly describe our clinical experience.

Early changes in adipokine levels and baseline limb fat may predict HIV lipoatrophy over 2 years following initiation of antiretroviral therapy

BACKGROUND

No biological marker has been identified that predicts the development of lipodystrophy (LD). We investigated whether metabolic and body composition parameters could predict the development of LD over 2 years in adults initiating antiretroviral therapy (ART).

METHODS

We used stored plasma collected at baseline and weeks 12, 24 and 48 from adults initiating combination ART. Adipocytokine, inflammatory cytokine, lipid and glycaemic parameters were measured and related to subsequent lipoatrophy (loss of limb fat mass of at least 2 kg from weeks 24 to 96 by dual-energy X-ray absorptiometry) and an increase in visceral adipose tissue (VAT; an increase of at least 18 cm(2) from baseline to week 48 by abdominal computed tomography). Risk factors associated with limb fat loss and VAT gain were analysed by logistic regression.

RESULTS

Fifty-four HIV-infected, treatment-naïve adults were included in the study: 53 (98%) of them were men, and they had a median age of 39 years [interquartile range (IQR) 34-48 years] and a median body mass index of 22.6 kg/m(2) (IQR 20-24.8 kg/m(2)). In multivariate analysis, a higher baseline limb fat percentage, and a 1 mmol/L increase in plasma leptin levels during the first 6 months of ART, independently predicted a peripheral fat loss of > or = 2 kg [odds ratio (OR) 2.58, 95% confidence interval (CI) 1.04-6.41; OR 3.15, 95% CI 1.34-7.35, respectively). VAT changes showed a borderline association with high baseline tumour necrosis factor-alpha levels and hip circumference (OR 1.04, 95% CI 1.00-1.07; OR 1.44, 95% CI 1.07-1.95, respectively).

CONCLUSIONS

In ART-naïve men, higher baseline limb fat and an early increase in leptin concentrations may predict the subsequent development of lipoatrophy. We did not find the same risk factors in the two different groups of patients with peripheral fat loss and central fat gain, suggesting a partially independent pathogenesis.

Estimating the risk of blood donation associated with HIV risk behaviours

A blood donor questionnaire and declaration, with deferral of potential donors at a higher risk of blood-borne infections, was introduced in Australia in the mid-1980s to reduce the risk of donation of HIV-infected blood. However, the absolute risk of HIV transmission through blood donation from high-HIV-risk donors has not been estimated. This study presents a new method of assessing the risk posed to the blood supply by selected HIV risk behaviours. A model was developed to estimate the probability of blood donation during the window period for HIV infection. Five scenarios for blood donors were considered: (1) men who have sex with men (MSM), (2) men who have sex with women in Australia, (3) women who have sex with partners from countries with a high HIV prevalence, (4) men who have sex with commercial sex workers in Australia and (5) people injecting drugs used once in a year. Those estimated to be at highest risk of becoming infected and donating in the window period were MSM. Women who have sex with men from countries of high HIV prevalence are at greater risk than men who have sex with female sex workers from Australia. These three groups under current Australian guidelines are deferred from donating blood for 12 months. In Australia, a single episode of injecting drug use is associated with very low risk of HIV transmission. The model presented in this study can be used to assess the impact of selected individual risk behaviours on the safety of the blood supply.

Long-term clinical and surrogate marker effects of subcutaneous intermittent interleukin-2 without antiretroviral therapy in HIV-infected patients

OBJECTIVES

Subcutaneous administration of interleukin-2 (IL-2) has been shown to increase CD4 counts in HIV-infected patients. It remains unclear whether this effect is associated with a clinical benefit.

PATIENTS AND METHODS

We conducted a long-term follow-up in the cohort of the UK-Vanguard study in which three groups of 12 antiretroviral-naive subjects with CD4 cell counts >350 cells/mm(3) received no treatment or IL-2 at either 4.5 or 7.5 MIU twice daily in 5 day cycles, respectively.

RESULTS

Mean follow-up was 376 weeks. IL-2 therapy was associated with a higher area under the curve of CD4 cell count change from baseline at week 48 but not thereafter. HIV-RNA levels were unaffected. Highly active antiretroviral therapy (HAART) was initiated after a mean of 172, 175 and 152 weeks in the control group, low-dose and high-dose IL-2 treatment group, respectively, a statistically non-significant difference. There was a tendency to start HAART soon after discontinuation of IL-2 therapy which may have been triggered by the steep decay of CD4 counts. There were two serious adverse events in the control group, seven in the low-dose IL-2 group and eight in the high-dose IL-2 group. No pattern of disease was detected, making an association with IL-2 therapy unlikely.

CONCLUSIONS

We could detect neither a benefit of IL-2 therapy after week 48 nor delayed initiation of HAART. This is currently the longest follow-up data comparing IL-2 therapy with no therapy in antiretroviral-naive HIV-infected patients and does not show a persistent benefit of the intervention.

Accuracy of the Alberta Stroke Program Early CT Score during the first 3 hours of middle cerebral artery stroke: comparison of noncontrast CT, CT angiography source images, and CT perfusion

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early CT Score (ASPECTS) is a reliable method of delineating the extent of middle cerebral artery (MCA) stroke. Our aim was to retrospectively compare the accuracy of ASPECTS on noncontrast CT, CT angiography (CTA) source images, and CT perfusion maps of cerebral blood volume (CBV) during the first 3 hours of middle cerebral artery (MCA) stroke.

MATERIALS AND METHODS

First-time patients with MCA stroke who presented <3 hours from symptom onset and were evaluated by noncontrast CT/CTA/CT perfusion, had confirmed acute nonlacunar MCA infarct on diffusion-weighted MR imaging (DWI) within 7 days, and had follow-up angiography were included. Patients were excluded for persistent MCA occlusion or stenosis. Two raters through consensus assigned an ASPECTS on the noncontrast CT, CTA source images, and the section-selective (2 x 12 mm coverage) CT perfusion CBV maps. ASPECTS on follow-up DWI served as the reference standard. For each CT technique, the detection rates of regional infarction, the mean ASPECTS, and the linear correlation to final ASPECTS were determined and compared. P values <.05 were considered significant.

RESULTS

Twenty-eight patients satisfied the criteria with DWI performed at a mean of 50.3 hours (range, 22-125 hours) post-CT imaging. Of 280 ASPECTS regions, 100 were infarcted on DWI. The accuracy of noncontrast CT, CTA source images, and CT perfusion CBV for detecting regional infarct was 80.0%, 84.3%, and 96.8%, respectively (P < .0001). The mean ASPECTSs of noncontrast CT, CTA source images, CT perfusion CBV, and DWI were 8.4 +/- 1.8, 8.0 +/- 1.8, 6.8 +/- 1.9, and 6.5 +/- 1.8, respectively. The mean noncontrast CT and CTA source image ASPECTS was different from that of DWI (P < .05). Correlation of noncontrast CT, CTA source images, and CT perfusion CBV ASPECTS with final ASPECTS was r(2) = 0.34, r(2) = 0.42, and r(2) = 0.91, respectively.

CONCLUSION

In a retrospective cohort of MCA infarcts imaged <3 hours from stroke onset, ASPECTS was most accurately determined on CT perfusion CBV maps.

Measuring elevated microvascular permeability and predicting hemorrhagic transformation in acute ischemic stroke using first-pass dynamic perfusion CT imaging

BACKGROUND AND PURPOSE

Hemorrhagic transformation (HT) can be a devastating complication of acute ischemic stroke (AIS). The purpose of this study was to determine whether increased microvascular permeability (PS) of the blood-brain barrier was detected in early AIS by using first-pass dynamic perfusion CT (PCT) and whether PS was significantly higher in infarcts destined for HT.

MATERIALS AND METHODS

Fifty patients with AIS less than 3 hours old and evaluated by PCT were included. PS color maps were retrospectively generated from PCT data using the Patlak model. One reader analyzed each PS map by drawing 4 circular 10-mm regions of interest on any focal abnormality. The mean of these 4 regions of interest represented the PS of the infarct (PSinfarct). The mean of 4 mirror regions of interest on the nonischemic contralateral hemisphere was also obtained (PScontrol). PSinfarct and PScontrol were compared by using an exact Wilcoxon test. PSinfarct for infarcts that developed HT on follow-up (PSHT) was compared with all of the others (PSNo-HT) using an exact Mann-Whitney test.

RESULTS

Forty-four infarcts (88%) showed focal PS elevation in the region of infarct. In units of milliliters per 100 milliliters per minute, PSinfarct ranged from 0 to 13 (mean: 3.5+/-3.1) versus PScontrol of 0-0.8 (mean: 0.28+/-0.27; P<.0001). Six infarcts (12%) developed HT, all of which were within the region of PS elevation. PSHT ranged from 5.2 to 13 (mean: 9.8+/-2.9) versus PSNo-HT of 0-5.9 (mean: 2.7+/-2.0; P<.0001). Eighteen infarcts (36%) were treated with recombinant tissue plasminogen activator (rtPA). A significant difference between PSHT and PSNo-HT persisted irrespective of rtPA treatment.

CONCLUSIONS

Elevated permeability was detectable in AIS by using first-pass PCT and it predicted subsequent HT.

Predicting grade of cerebral glioma using vascular-space occupancy MR imaging

BACKGROUND AND PURPOSE

MR imaging can measure tissue perfusion and the integrity of the blood-brain barrier. We hypothesize that a combined measure of cerebral blood volume and vascular permeability using vascular-space occupancy (VASO) MR imaging, a recently developed imaging technique, is of diagnostic value for predicting tumor grade.

MATERIALS AND METHODS

Thirty-nine patients (9 World Health Organization [WHO] grade II, 20 grade III, and 10 grade IV as determined by histopathologic assessment) were examined using VASO MR imaging, and regions-of-interest analysis was performed in tumoral regions, as well as in regions contralateral to the tumor. A Mann-Whitney test was conducted on the resulting VASO indices for a pairwise comparison across tumor grades. Nominal logistic regression was used to evaluate the use of VASO parameters for predicting group membership (by the percentage of correct classifications).

RESULTS

The ratio between tumor side and contralateral side, VASO(Ratio), showed significant differences in all 3 of the pairwise comparisons (P < .01). VASO values in the tumoral regions, VASO(Tumor), showed significant difference between grade II and III and between II and IV but not between III and IV. Both VASO(Tumor) and VASO(Ratio) were found to be significant predictors of tumor grade, giving diagnostic accuracies of 66.7% and 71.8%, respectively. When testing to discriminate grade II tumors from higher grade tumors, the areas under the receiver operating characteristic curve were found to be 0.974 and 0.985 for VASO(Tumor) and VASO(Ratio), respectively.

CONCLUSION

VASO MR imaging can be used for noninvasive tumor grade prediction based on cerebral blood volume and vascular permeability. VASO is more effective in separating WHO grade II from higher grades than in separating grade III from grade IV.

Comparing cerebral blood volume and vascular permeability measurements with tumor volume measurements following anti-angiogenesis therapy in recurrent gliomas

2030

Background: Dynamic susceptibility contrast-enhanced MRI (DSC MRI) is emerging as an important adjunctive biomarker to assess the effectiveness of anti-angiogenic therapies in the treatment of brain tumors. The purpose of our study is to compare changes in relative cerebral blood volume (rCBV) and in perfusion-permeability index (KTrans) with those of tumor volume measurements (T1c, T2/Flair) in predicting tumor therapeutic response in recurrent high-grade gliomas treated with bevacizumab, an anti-VEGF monoclonal antibody. Methods: 11 patients were treated with one to four cycles of bevacizumab and CPT-11. Their histological diagnoses were: glioblastoma multiforme (n=7), anaplastic astrocytoma (n=2), anaplastic oligodendroglioma (n=1), and diffuse pontine glioma (n=1). All patients had baseline DSC MRI scans prior to the administration of bevacizumab and were followed clinically and radiographically with both conventional and DSC MRI. Mixed model regression was used to compare the pre-treatment and post-treatment levels of each response measure. Results: There were statistically significant reductions in both actual rCBV measurements and T1c enhancement following treatment with bevacizumab and CPT-11. The pretreatment rCBV and T1c rates of change (as determined per 100 days) correlated significantly with time (p values are 0.0229 and 0.0014, respectively), while only the post treatment rCBV demonstrated significant rate of change (p value = 0.0001), suggesting that rCBV may reflect the effects of bevacizumab better than tumor volume. However, when the changes in rate from pre- to post-treatment status were considered, both rCBV and T1c demonstrated significance (p= 0.0001, 0.0157, respectively). There was a trend towards females having higher mean levels of KTrans than males at the same time point relative to treatment onset, but the result was not statistically significant (p=0.072). Conclusions: rCBV as measured from DSC MRI can be used as a surrogate biomarker to determine therapeutic response to bevacizumab. This may influence the neurosurgical risk/benefit equation as well as alter the aggressiveness of the post-operative adjuvant therapy in patients with recurrent gliomas.

No significant financial relationships to disclose.

Time-resolved MR angiography: optimal parallel imaging method

BACKGROUND AND PURPOSE

Time-resolved (TR) MR angiography (MRA) using parallel imaging techniques is proving to have clinical utility for improving MRA spatial and temporal resolution and separating arterial from venous anatomy. The purpose of this study was to evaluate TR MRA of the intracranial vessels at different integrated parallel acquisition technique (IPAT) factors.

MATERIALS AND METHODS

3D TR MRA using time-resolved echo-shared angiographic technique was performed with different IPAT factors (0, 2, 3) at 1.5 T, resulting in temporal resolutions of 4.0, 1.7, and 1.3 seconds, respectively. We studied 14 subjects, comprising 12 patients with various pathologic conditions and 2 healthy subjects. The brain volume was covered by 36 partitions, and a bolus of 5 mL of gadopentate dimeglumine was administered. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), the number of frames that distinguished between arterial and venous phases, the conspicuity of the vasculature, and artifacts were analyzed.

RESULTS

There was no significant difference in SNR between IPAT factors 0 and 2. Moreover, SNR was significantly lower with IPAT 3 than with IPAT 0 or 2. Smaller vessel segments (M3 and P3) were rated significantly inferior with TR MRA IPAT 2 or 3 compared with MRA without IPAT. For larger proximal vessels (A1 and A2 segments of anterior cerebral artery, M1 and M2 segments of middle cerebral artery, P2 segment of posterior cerebral artery, and basilar artery), there was no difference between TR MRA IPAT 0 and 2.

CONCLUSION

To obtain arterial and venous information in a clinical setting, intracranial TR MRA is best performed with an IPAT factor of 2 with at least 5 mL of contrast.

Histogram analysis versus region of interest analysis of dynamic susceptibility contrast perfusion MR imaging data in the grading of cerebral gliomas

BACKGROUND AND PURPOSE

Histogram analysis can be applied to dynamic susceptibility contrast (DSC) perfusion MR imaging datasets and can be as effective as traditional region-of-interest (ROI) measurements of relative cerebral blood volume (rCBV), an operator-dependent method. We compare the routine ROI method with histogram analysis in the grading of glial neoplasms.

MATERIALS AND METHODS

Ninety-two patients underwent conventional and DSC MR imaging. Routine rCBV (rCBVmax) measurements were obtained from ROIs of the maximal abnormality within the glioma. Histogram analysis rCBVT was performed with an ROI drawn around the maximal tumor diameter. Spearman rank correlations measured associations among glioma grade, rCBVmax, and histogram measures. Mann-Whitney tests compared grade with respect to rCBV and histogram measures. Logistic regression and McNemar test compared the utility of rCBVmax and histogram measures for detecting high grade gliomas.

RESULTS

Routine rCBVmax analysis showed significant correlation with grade (r = 0.734, P < .001). Histogram rCBVT metrics showed significant correlation with grade (P < .008); the 3 highest were rCBVT SD, SD50, and mean25 (r = 0.718, 0.684, and 0.683, respectively). Grade could be predicted by rCBVmax (P < .001) as well as rCBV(T) (P < .008). Three rCBVT histogram measures (SD, SD25, and SD50) detected high-grade glioma with significantly higher specificity than rCBVmax when the diagnostic tests were constrained to have at least 95% sensitivity.

CONCLUSION

rCBVT histogram analysis is as effective as rCBVmax analysis in the correlation with glioma grade. Inexperienced operators may obtain perfusion metrics using histogram analyses that are comparable with those obtained by experienced operators using ROI analysis.

Correlation of diffusion tensor and dynamic perfusion MR imaging metrics in normal-appearing corpus callosum: support for primary hypoperfusion in multiple sclerosis

BACKGROUND AND PURPOSE

Hypoperfusion of the normal-appearing white matter in multiple sclerosis (MS) may be related to ischemia or secondary to hypometabolism from wallerian degeneration (WD). This study evaluated whether correlating perfusion and diffusion tensor imaging (DTI) metrics in normal-appearing corpus callosum could provide support for an ischemic mechanism for hypoperfusion.

MATERIALS AND METHODS

Fourteen patients with relapsing-remitting MS (RRMS) and 17 control subjects underwent perfusion MR imaging and DTI. Absolute measures of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) were calculated. Mean diffusivity (MD) and fractional anisotropy (FA) maps were computed from DTI data. After visual coregistration of perfusion and DTI images, regions of interest were placed in the genu, central body, and splenium of normal-appearing corpus callosum. Pearson product-moment correlation coefficients were calculated using mean DTI and perfusion measures in each region.

RESULTS

In the RRMS group, CBF and CBV were significantly correlated with MD in the splenium (r = 0.83 and r = 0.63, respectively; both P < .001) and in the central body (r = 0.86 and r = 0.65, respectively; both P < .001), but not in the genu (r = 0.23 and 0.25, respectively; both P is nonsignificant). No significant correlations were found between MTT and DTI measures or between FA and any perfusion measure in the RRMS group. No significant correlations between diffusion and perfusion metrics were found in control subjects.

CONCLUSION

In the normal-appearing corpus callosum of patients with RRMS, decreasing perfusion is correlated with decreasing MD. These findings are more consistent with what would be expected in primary ischemia than in secondary hypoperfusion from WD.

Combination antiretroviral therapy without a nucleoside reverse transcriptase inhibitor: experience from 334 patients in three cohorts

BACKGROUND

Toxicity and resistance may limit the use of HIV nucleoside reverse transcriptase inhibitors (NRTIs). We assessed the safety and activity of regimens that did not include an NRTI.

METHOD AND PATIENTS

We analysed NRTI-sparing regimens using pooled data from three cohorts in Australia and France where HIV RNA viral load, CD4 lymphocyte count and metabolic parameters are assessed prospectively. The inclusion criterion was the commencement of any antiretroviral combination excluding NRTIs.

RESULTS

A total of 334 (3.9%) of 8477 patients were included in the present study for a median follow-up time of 105 weeks. Therapeutic combinations were one nonnucleoside reverse transcriptase inhibitor (NNRTI) plus one protease inhibitor (PI) (58%), two PIs (26%), one PI (16%), and one NNRTI plus two PIs (8%). At baseline, the median CD4 lymphocyte count was 264 cells/muL (interquartile range 164-446 cells/muL) and 25% of patients had plasma HIV RNA below 500 HIV-1 RNA copies/mL. In intent-to-treat analysis, 64% of patients had HIV RNA <500 copies/mL at 6 months and 68% at 24 months. The mean CD4 lymphocyte count increase was 60 cells/microL (95% confidence interval 41-76 cells/microL) at 6 months and 111 cells/microL (95% confidence interval 82-140 cells/microL) at 24 months. Prognostic factors for having HIV RNA <500 copies/mL at 6 months included independently having undetectable HIV RNA at baseline and being naïve for NNRTIs. The proportion of patients with triglycerides >2.3 mmol/L increased from 32% to 63% at 6 months and to 62% at 24 months (P-trend=0.002), and those with total cholesterol >6.2 mmol/L increased from 18% to 38% at 6 months and to 44% at 24 months (P-trend <0.001), with an increased risk for patients treated with NNRTI+PIs. Forty-one per cent of patients discontinued their NRTI-sparing regimen.

CONCLUSION

In these antiretroviral-experienced patients, NRTI-sparing therapy appeared to have satisfactory virological and immunological efficacy. However, hyperlipidaemia was frequent and requires monitoring of cardiovascular risk factors.

Acceptability of Power Variation during a Simulated Hilly Time Trial

We investigated the acceptability of power variation during a cycling time trial (TT) with simulated uphill and downhill sections. Seven cyclists first completed an 800-kJ self-paced TT on a simulated flat course. An 800-kJ TT course with four sections of uphill/downhill was then modeled. Each section involved 100 kJ of cycling up a simulated gradient of 5 % followed by 100 kJ of riding down a simulated gradient of - 5 %. Participants were required to complete this simulated course using two pacing strategies; (i) at a constant power equivalent to the mean power achieved during the initial TT, and (ii) increasing power by 5 % of mean power when traveling uphill (mean duration of each climb = 714 s) and decreasing power in the downhill sections (mean duration of each descent = 190 s), so that overall mean power was equivalent to that in (i). All participants maintained this variable power strategy during the first half of the TT, but two riders could not adhere to the power variations during the final 400 kJ. Nevertheless, mean +/- SD finish time for the variable power trial (3670 +/- 589 s) was significantly faster than that for the constant power TT (3758 +/- 645 s), the 95 % confidence interval for the percentage improvement being 0.4 to 4.3 %. Heart rate and lactate responses were highest in the initial self-paced TT and did not differ between the subsequent constant and variable power trials. Ratings of perceived exertion were also similar between trials. In our externally-valid TT, we found that some cyclists cannot fully adhere to a pacing strategy involving an approximate +/- 5 % variation in mean power in parallel with gradient variation. Nevertheless, an important time saving can still result even if a variable pacing strategy is only partially adopted during a hilly time trial, so that no additional physiological strain is incurred.

The feasibility of clinical endpoint trials in HIV infection in the highly active antiretroviral treatment (HAART) era

BACKGROUND

Planning clinical-endpoint trials in patients with HIV remain difficult as long-term follow-up of many patients is required. Cohort studies of patients with HIV can provide key estimates of the likely disease progression, required sample size and follow-up.

OBJECTIVES

To verify the assumptions used in designing ESPRIT, a large randomized clinical trial assessing the clinical benefit of interleukin-2 treatment in patients with HIV infection, to use EuroSIDA to mimic the inclusion criterion of ESPRIT in order to compare the observed event rate in ESPRIT with the projected rate in EuroSIDA, and to project the required length of ESPRIT.

METHODS

Patients in EuroSIDA who satisfied the ESPRIT recruitment criteria were selected. Patients were followed from baseline to new AIDS or death.

RESULTS

The incidence of clinical progression in the selected EuroSIDA patients (N = 4482) was 1.5 per 100 PYFU (95% CI 1.3-1.7), and did not increase with increasing time from baseline, contrary to what was assumed in the design of the ESPRIT trial. In ESPRIT (N = 4150), for which the comparative data remain blinded, the incidence was 1.1 per 100 PYFU (95% CI 0.9-1.3), with no increase over time. The average follow-up required to complete ESPRIT and accrue the 320 events required by protocol would be seven years, 10 months using the projected rates from the EuroSIDA study, and seven years, 11 months if the observed event rate in ESPRIT continued unchanged.

LIMITATIONS

Differences between patients recruited to observational studies or clinical trials cannot always be adjusted for.

CONCLUSIONS

Event rates in EuroSIDA were similar in the first two years to those used in the design of ESPRIT, but did not increase over time, leading to an increase in the expected duration of ESPRIT. Clinical endpoint trials in HIV infection remain feasible, and large cohort studies are critical to the planning and ongoing assessment of design assumptions in such trials. The underlying assumptions of the clinical trial should be re-examined to ensure the original trial assumptions remain valid.

Measuring children's participation in recreation and leisure activities: construct validation of the CAPE and PAC

There is a need for psychometrically sound measures of children's participation in recreation and leisure activities, for both clinical and research purposes. This paper provides information about the construct validity of the Children's Assessment of Participation and Enjoyment (CAPE) and its companion measure, Preferences for Activities of Children (PAC). These measures are appropriate for children and youth with and without disabilities between the ages of 6 and 21 years. They provide information about six dimensions of participation (i.e. diversity, intensity, where, with whom, enjoyment and preference) and two categories of recreation and leisure activities: (i) formal and informal activities; and (ii) five types of activities (recreational, active physical, social, skill-based and self-improvement). This paper presents information about the performance of the CAPE and PAC activity type scores using data from a study involving 427 children with physical disabilities between the ages of 6 and 15 years. Intensity, enjoyment and preference scores were significantly correlated with environmental, family and child variables, in expected ways. Predictions also were supported with respect to differences in mean scores for boys vs. girls, and children in various age groups. The information substantiates the construct validity of the measures. The clinical and research utility of the measures are discussed.

Whole-brain N-acetylaspartate spectroscopy and diffusion tensor imaging in patients with newly diagnosed gliomas: a preliminary study

BACKGROUND AND PURPOSE

Glial cancer cells can be found well beyond the MR imaging T2 signal-intensity hyperintensity. To quantify the extent of the diffuse microstructural tissue damage possibly due to the presence of these satellite tumor cells, we investigated the relationships between global metabolic and microstructural abnormalities in the normal-appearing brain regions of patients with newly diagnosed glioma.

MATERIAL AND METHODS

Ten patients (6 men, 4 women) with radiologically suspected untreated supratentorial glial tumors and 9 healthy controls (5 men, 4 women) were studied with T1- and T2-weighted MR imaging, diffusion-weighted echo-planar MR imaging, and whole-brain N-acetylaspartate (WBNAA) proton MR spectroscopy. The relationship between the WBNAA concentration, the mean diffusivity (MD), and fractional anisotropy (FA) values in a large contralateral normal-appearing white matter (NAWM) brain region was investigated with the Spearman rank correlation test.

RESULTS

WBNAA values were significantly lower (P < .001) in patients (9.7 +/- 1.7 mmol/L) than controls (13.1 +/- 1.1 mmol/L). MD values were higher (P = .0001) in patients (0.95 +/- 0.07 mm(2)s(-1)) than in controls (0.61 +/- 0.04 mm(2)s(-1)). FA values did not differ between patients (0.42 +/- 0.08) and controls (0.43 +/- 0.041). A strong inverse correlation between WBNAA and MD (r = -0.88, P = .0008) was found in the patients but not in controls (r = 0.012, P = .975).

CONCLUSION

The correlation between the WBNAA and MD in the contralateral NAWM suggests that the microstructural damage possibly related to the presence of infiltrative tumor cells contributes to WBNAA decline in these patients.

Comparing perfusion metrics obtained from a single compartment versus pharmacokinetic modeling methods using dynamic susceptibility contrast-enhanced perfusion MR imaging with glioma grade

BACKGROUND AND PURPOSE

Numerous different parameters measured by perfusion MR imaging can be used for characterizing gliomas. Parameters derived from 3 different analyses were correlated with histopathologically confirmed grade in gliomas to determine which parameters best predict tumor grade.

METHODS

Seventy-four patients with gliomas underwent dynamic susceptibility contrast-enhanced MR imaging (DSC MR imaging). Data were analyzed by 3 different algorithms. Analysis 1 estimated relative cerebral blood volume (rCBV) by using a single compartment model. Analysis 2 estimated fractional plasma volume (V(p)) and vascular transfer constant (K(trans)) by using a 2-compartment pharmacokinetic model. Analysis 3 estimated absolute cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) by using a single compartment model and an automated arterial input function. The Mann-Whitney U test was used make pairwise comparisons. Binary logistic regression was used to assess whether rCBV, V(p), K(trans), CBV, CBF, and MTT can discriminate high- from low-grade tumors.

RESULTS

rCBV was the best discriminator of tumor grade ype, followed by CBF, CBV, and K(trans). Spearman rank correlation factors were the following: rCBV = 0.812 (P < .0001), CBF = 0.677 (P < .0001), CBV = 0.604 (P < .0001), K(trans) = 0.457 (P < .0001), V(p) = 0.301 (P =.009), and MTT = 0.089 (P = .448). rCBV was the best single predictor, and K(trans) with rCBV was the best set of predictors of high-grade glioma.

CONCLUSION

rCBV, CBF, CBV K(trans), and V(p) measurements correlated well with histopathologic grade. rCBV was the best predictor of glioma grade, and the combination of rCBV with K(trans) was the best set of metrics to predict glioma grade.

Keeping It Together: an information KIT for parents of children and youth with special needs

BACKGROUND

Provision and use of information about their children is a major concern to families who have a child with a disability. Strategies or systems to influence parents' abilities to receive, give and use information in a way that is satisfying to them have not been well validated.

METHODS

This paper reports on the development and evaluation of a Parent Information KIT ('Keeping It Together') information management system and child advocacy tool. The KIT was designed to assist parents in giving, getting and organizing information in an effective way. The KIT was evaluated by a sample of 440 parents, with outcomes of use, utility, impact and perceptions of family-centred care measured at baseline, and after 6 months, and 15 months.

RESULTS

Parents' perceptions of their ability, confidence and satisfaction when using information improved significantly after using the KIT. Parents' perceptions of care, as measured with the Measure of Processes of Care, also improved significantly in the areas of 'Enabling/Partnership' and 'Providing General Information'. Parents' ratings of the use and utility of the KIT were associated with increased impact and, in turn, predicted improved perceptions of care.

CONCLUSION

Parents who received and actively used the Parent Information KIT experienced significant increases in their perception of their ability and self-confidence in getting, giving and using information to assist their child with a disability. Strategies for improving the use of the KIT among parents are discussed.

Diffusion tensor imaging in multiple sclerosis: assessment of regional differences in the axial plane within normal-appearing cervical spinal cord

BACKGROUND AND PURPOSE

Evaluation of the spinal cord is important in the diagnosis and follow-up of patients with multiple sclerosis. Our purpose was to investigate diffusion tensor imaging (DTI) changes in different regions of normal-appearing spinal cord (NASC) in relapsing-remitting multiple sclerosis (RRMS).

METHODS

Axial DTI of the cervical spinal cord was performed in 24 patients with RRMS and 24 age- and sex-matched control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated in separate regions of interest (ROIs) in the anterior, lateral, and posterior spinal cord, bilaterally, and the central spinal cord, at the C2-C3 level. Patients and control subjects were compared with respect to FA and MD with the use of an exact Mann-Whitney test. Logistic regression and receiver operating characteristic (ROC) curve analysis assessed the utility of each measure for the diagnosis of RRMS.

RESULTS

DTI metrics in areas of NASC in MS were significantly different in patients compared with control subjects; FA was lower in the lateral (mean +/- SD of 0.56 +/- 0.10 versus 0.69 +/- 0.09 in control subjects, P < .0001), posterior (0.52 +/- 0.11 versus 0.63 +/- 0.10, P < .0001), and central (0.53 +/- 0.10 versus 0.58 +/- 0.10, P = .049) NASC ROIs. Assessing DTI metrics in the diagnosis of MS, a sensitivity of 87.0% (95% confidence interval [CI], 66.4 to 97.1) and a specificity of 91.7% (95% CI, 73.0 to 98.7) were demonstrated.

CONCLUSION

The NASC in RRMS demonstrates DTI changes. This may prove useful in detecting occult spinal cord pathology, predicting clinical course, and monitoring disease progression and therapeutic effect in MS.

Methylation of INK4 and CIP/KIP families of cyclin-dependent kinase inhibitor in chronic lymphocytic leukaemia in Chinese patients

BACKGROUND

INK4 (p15, p16, p18 and p19) and CIP/KIP (p21, p27 and p57) are two families of cyclin-dependent kinase inhibitors (CKI) targeting CDK4/6 and CDK2, respectively.

AIM

To study the role of methylation in the inactivation of CKI in chronic lymphocytic leukaemia (CLL).

MATERIALS AND METHODS

Methylation-specific polymerase chain reaction was carried out on DNA obtained from the bone marrow of 56 newly diagnosed patients with CLL.

RESULTS

Similar demographic features and clinical outcome were observed in our patients when compared with Caucasian patients, including an indolent clinical course (10-year overall survival 51%) and advanced Rai stage (p = 0.006), and a high-risk karyotype such as trisomy 12 and complex aberrations (p = 0.03). In the INK4 family, methylation in p15 and p16 occurred in 20 (35.7%) and 8 (14.3%) patients, respectively. In all, 5 (8.9%) CLL samples harboured concurrent methylation of both p15 and p16. Apart from an association of p16 methylation with higher presenting leucocyte count (64.5 x 10(9)/l in methylated p16 and 16.0 x 10(9)/l in unmethylated p16 patients; p = 0.016), there was no association between p15 and p16 methylation and age, sex and Rai stage. No difference was observed in the overall survival for patients with and without p15 and p16 methylation. By contrast, p18 and Rb were unmethylated in all samples. In the CIP/KIP family, apart from infrequent methylation of p57 in 4 (7.1%) patients, methylation of p21 and p27 was uniformly absent.

CONCLUSION

p15 and, less frequently, p16 of the INK4 family of CKI, instead of the CIP or KIP family, were targeted by methylation in CLL. p16 methylation was associated with a higher lymphocyte count at presentation. This is the first comprehensive study of the epigenetic dysregulation of the INK4 and CIP/KIP families of CKI in Chinese patients with CLL.

Field, coil, and echo-time influence on sensitivity and reproducibility of brain proton MR spectroscopy

BACKGROUND AND PURPOSE

Clinical MR imaging scanners now offer many choices of hardware configurations that were not available in the first 25 years of their existence. Our goal was to assess the influence of coil technology, magnetic field strength, and echo time (TE) on the sensitivity, reflected by the signal intensity-to-noise-ratio (SNR) and reproducibility of proton MR spectroscopy (1H-MR spectroscopy).

MATERIAL AND METHODS

The SNR, the intersubject reproducibility, and the intrasubject reproducibility of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were compared at the common TEs of 30, 144, and 288 ms, by using 1H-MR spectroscopy in 6 volunteers at (1) 3T with a single-element quadrature (SEQ); (2) 1.5T with SEQ; and (3) 1.5T with a 12-channel phased-array (PA) head coil.

RESULTS

In terms of sensitivity, the best SNR for all metabolites was obtained at the shortest TE (30 ms). It was comparable between the 3 and 1.5T with the PA, but approximately 35% better than the 1.5T with SEQ. This SNR difference declined <25% at TE of 144 ms and to equity among all imagers at TE of 288 ms. Reproducibility, reflected in the coefficient of variation (CV), was best for NAA at TE of 288 ms, 15%-50% better than at TE of 30 ms in either gray (GM) or white matter (WM). The CV for Cr was best, at TE of 288 ms for GM, but its WM results were independent of TE. Metabolite level reproducibility did not depend on coil technology or magnetic field strength.

CONCLUSIONS

For the same coil type, the SNR of all major metabolites was approximately 35% better at 3T than at 1.5T. This advantage, however, was offset at 1.5T with a PA coil, making it a cost-effective upgrade for existing scanners. Surprisingly and counterintuitively, despite the lowest SNR, the best reproducibility was obtained at the longest TE (288 ms), regardless of field or coil.

Dollars and sense. Is there a better way to determine private surgical fees in New Zealand?

In New Zealand, private insurers reimburse surgeons on a fee-for-service basis. Ideally, the level of reimbursements should reflect competitive market prices. Due to concerns such a market does not exist, other countries have adopted Relative Value Scales (RVS) to estimate a fair reimbursement level for different procedures. No such scale exists in New Zealand for surgeons, but it does for anaesthetists. This study compares reimbursements to surgeons and anaesthetists from private insurers using data from 3186 procedures performed between 1996 and 2002. We calculate an implicit hourly rate of reimbursement and compare the level of reimbursement between procedures and the variance of reimbursements within procedures for surgeons and anaesthetists. The results suggest that there are significantly greater deviations in average reimbursements between procedures for surgeons than for anaesthetists. Furthermore, the variability of reimbursements is greater for reimbursements to surgeons within specific procedures. While the results do not necessarily imply that surgical reimbursements are inconsistent with underlying market rates, the results are consistent with the hypothesis that anaesthetist's fees show greater stability because of the existence of a RVS. We conclude by discussing what would be required to implement a RVS for surgical fees in New Zealand.

Family-centred service: moving ideas into practice

BACKGROUND

With parents more involved in their child's day-to-day care, concepts of family-centred service (FCS) are increasingly adopted in children's health and rehabilitation service organizations.

METHODS

In this paper, we report the results of a study to develop and evaluate educational materials for parents, service providers and health sciences students about FCS. The materials focus on the nature and philosophy of FCS, and the practical skills and systemic changes required for its implementation.

RESULTS

Thirty-six participants (12 families, 12 service providers and 12 rehabilitation science students) were randomly assigned to receive one of the six FCS educational packages, each containing three FCS educational sheets. Participants' ratings of the format and content, and the impact of the FCS Sheets were very high, with overall means above 5.0 on a 7-point scale. Using a mixed model analysis, we found significant differences in participants' ratings of familiarity with the materials (students were less familiar than service providers). After statistical adjustment for familiarity, there were no significant differences between the groups or the packages on ratings of format and content or impact.

CONCLUSIONS

There were no significant differences in the way in which the participant groups rated the impact of the FCS Sheets and the specific packages did not have an effect on the participants' ratings. The FCS educational materials, even those less familiar to participants, were rated highly on format and content, and impact. Results indicate that the material was perceived to be important to each group, and was formatted and written in a way that was easy to understand. This finding counters current recommendations in the knowledge transfer literature that suggest different versions should be written for different target groups.

Understanding α-Globin Gene Regulation: Aiming to Improve the Management of Thalassemia

Over the past 50 years, many advances in our understanding of the general principles controlling gene expression during hematopoiesis have come from studying the synthesis of hemoglobin. Discovering how the alpha- and beta-globin genes are normally regulated and documenting the effects of inherited mutations that cause thalassemia have played a major role in establishing our current understanding of how genes are switched on or off in hematopoietic cells. Previously, nearly all mutations causing thalassemia have been found in or around the globin loci, but rare inherited and acquired trans-acting mutations are being found more often. Such mutations have demonstrated new mechanisms underlying human genetic disease. Furthermore, they are revealing new pathways in the regulation of globin gene expression that, in turn, may open up new avenues for improving the management of patients with common types of thalassemia.

Meeting health need, accessing health care: the role of neighbourhood

Much of what we know about the determinants of access to health care comes from studies undertaken at a large scale, such as between cities, regions/counties/provinces/states and countries. This paper examines local level variations in access to and utilization of health care services across four distinct neighbourhoods in Hamilton, Ontario, Canada. Survey data (n = 1500) were analysed using logistic regression to explore the potential relationships between neighbourhood and health care utilization and unmet health care need. Results show some relationships between neighbourhood of residence and levels of reported utilization as well as unmet need, even when controlling for predisposing, enabling, and need factors (i.e. Age, gender, household composition, income, education, perceived gp visit time) as well as health status. Findings from this empirical study suggest a finer lens is required to examine the mechanisms through which place impacts access to and utilization of care, one that recognizes the roles of compositional, contextual and collective aspects of neighbourhood.

Heterogeneities in the production of health: smoking, health status and place

The harmful effects of smoking on health are well-established. However, little attention has been given to possible variations in the size of the association within populations. In this paper, we test for neighbourhood variation in the smoking-health relationship. We estimate equations to explain variations in self-reported health using data from a survey of adults in four distinct neighbourhood clusters in Hamilton, Ontario. After controlling for neighbourhood composition, the probability of being unhealthy remained significantly higher in the two lower socioeconomic status neighbourhoods (North East and Downtown) than in the rest of the city. The smoking-health association was not the result of more smokers living in less healthy neighbourhoods. In the Downtown neighbourhood, the relative odds of being unhealthy among smokers compared to non-smokers was less than one-half of the corresponding relative odds in the rest of the city. Although smoking represents a health risk for individuals in all neighbourhoods, for individuals living in the Downtown neighbourhood the size of this risk is substantially smaller than for individuals in other neighbourhoods.

Efficacy of DNA and fowlpox virus priming/boosting vaccines for simian/human immunodeficiency virus

Further advances are required in understanding protection from AIDS by T-cell immunity. We analyzed a set of multigenic simian/human immunodeficiency virus (SHIV) DNA and fowlpox virus priming and boosting vaccines for immunogenicity and protective efficacy in outbred pigtail macaques. The number of vaccinations required, the effect of DNA vaccination alone, and the effect of cytokine (gamma interferon) coexpression by the fowlpox virus boost was also studied. A coordinated induction of high levels of broadly reactive CD4 and CD8 T-cell immune responses was induced by sequential DNA and fowlpox virus vaccination. The immunogenicity of regimens utilizing fowlpox virus coexpressing gamma interferon, a single DNA priming vaccination, or DNA vaccines alone was inferior. Significant control of a virulent SHIV challenge was observed despite a loss of SHIV-specific proliferating T cells. The outcome of challenge with virulent SHIV(mn229) correlated with vaccine immunogenicity except that DNA vaccination alone primed for protection almost as effectively as the DNA/fowlpox virus regimen despite negligible immunogenicity by standard assays. These studies suggest that priming of immunity with DNA and fowlpox virus vaccines could delay AIDS in humans.

Variation in specialist fees: evidence from New Zealand insurance claims

OBJECTIVES

To examine the parity between specialties in reimbursements for surgical procedures in a private, fee-for-service setting and to ascertain whether differences exist after accounting for factors suggested by a Resource-Based Relative Value Scale (RBRVS).

METHODS

A routinely updated database covering several private insurers (n = 8294 procedures from 1997 to 2002) was used to examine differences in overall and hourly reimbursement. Multiple regression analysis was used to control for factors that might be responsible for differences in payment (location, year, sex of patient and the associated anaesthetist fee). The resulting regression residuals were compared between specialties.

RESULTS

Large differences between specialties in reimbursements were found in the overall amount paid. For most specialties, these differences were explained by factors such as time for procedure, location, complexity of procedure and sex of patients. However, hourly reimbursements for ophthalmologists were substantially higher (more than 50% above general surgery overall and 72% higher on an hourly basis). Some other smaller differences in overall and hourly reimbursement were also found.

CONCLUSIONS

These results indicate that specialist fees vary significantly but many of the differences are explainable by factors incorporated into the RBRVS. However, significant variation remains for some specialties, most notably ophthalmology. Explanations for the results are discussed, including the possibility that political factors may influence the setting of specialist fees. This raises questions concerning the fairness of reimbursements and resulting solidarity within the medical profession.

Evaluating children's rehabilitation services: an application of a programme logic model

OBJECTIVES

To apply a programme logic model to evaluate the effectiveness of a new therapy service for children with special needs who were in transition from pre-school to kindergarten.

SETTING

A children's outpatient rehabilitation centre in Ontario, Canada.

MAIN OUTCOMES

The short-term outcomes included parents' perceptions of the transition process itself and the information they required, the children's skill development for the transition to kindergarten, and parents' perceptions of services and satisfaction with resources.

METHODS

A combination of quantitative methods [Goal Attainment Scaling (GAS), Measure of Processes of Care (MPOC), Client Satisfaction Questionnaire (CSQ)] and qualitative interviews were used to evaluate both the process ('Outputs') and outcomes ('Short-term objectives') of the new therapy service.

RESULTS

The children involved in the evaluation met or exceeded goals that were set by therapists and parents. Parents' perceptions of, and satisfaction with, the new service were higher than the provincial average. Qualitative data from interviews with parents and service providers supported the findings from standardized measures, and provided suggestions for future service delivery.

CONCLUSIONS

The programme logic model provided researchers and service providers a collaborative and systematic approach to conducting programme evaluation in a relatively short-time frame. It appears to be a useful option for evaluation of other children's services.

Linking perceptions of neighbourhood to health in Hamilton, Canada

STUDY OBJECTIVE

To investigate the association between perceptions of neighbourhood physical and social characteristics and three health outcomes (self assessed health status, chronic conditions, and emotional distress).

DESIGN

Cross sectional survey data analysed in small neighbourhoods.

SETTING

Hamilton, Ontario, Canada, a medium sized industrial city, located at the western end of Lake Ontario (population at the time of the study about 380 000).

PARTICIPANTS

Random sample of 1504 adults aged 18 years and older residing in four contrasting neighbourhoods.

MAIN RESULTS

Significant differences across the four neighbourhoods are apparent in self assessed health status and emotional distress, but not in chronic conditions. Neighbourhoods with lower SES reported poorer health and more emotional distress. Perceptions of the physical environment dominated social concerns in all neighbourhoods. For all three health outcomes, individual risk factors followed expectations, with measures of poverty, age, and lifestyle all significantly associated with poor health outcomes. Physical environmental problems were positively and significantly associated with poor physical and emotional health. Specifically, people reporting they dislike aspects of their neighbourhood's physical environment are 1.5 times more likely to report chronic health conditions (OR 1.56, 95% CI 1.19 to 2.05), while those reporting physical likes with their neighbourhood are less likely to report fair/poor health (OR 0.50, 95% CI 0.28 to 0.90) or emotional distress (OR 0.45, 95% CI 0.26 to 0.80).

CONCLUSIONS

These results demonstrate the importance of neighbourhood perceptions as a determinant of health, as well as conventional factors such as low income, lifestyle, and age. The dominance of physical environmental concerns may have arisen from the industrial nature of Hamilton, but this result merits further investigation.

Lowering blood pressure to prevent myocardial infarction and stroke: a new preventive strategy

OBJECTIVES

To investigate the screening performance of measuring blood pressure and other variables in identifying those who will develop, or die from, ischaemic heart disease and stroke. To quantify by how much drugs that lower blood pressure will reduce the risk of ischaemic heart disease and stroke in those designated 'screen positive'.

DATA SOURCES

MEDLINE, Cochrane collaboration and Web of Science databases; Stroke registries; Health Survey for England; Office of National Statistics; BUPA (British United Provident Association) study.

REVIEW METHODS

Relevant cohort studies and randomised trials were identified and analysed. Statistical analysis was used to determine drug efficacy and adverse effects.

RESULTS

Lowering blood pressure by 5 mmHg diastolic reduces the risk of stroke by an estimated 34% and ischaemic heart disease by 21% from any pre-treatment level; there is no threshold. These estimates, from cohort studies, have been corroborated by the results of randomised trials in persons with high, average and below average levels of blood pressure. In spite of its importance in causing cardiovascular disease blood pressure is a poor predictor of cardiovascular events. Its poor screening performance is illustrated by the findings that in the largest cohort study, persons in the top 10% of the distribution of systolic blood pressure experienced only 21% of all ischaemic heart disease events and 28% of all strokes at a given age. Combining several reversible risk factors adds little to the screening performance of blood pressure alone; for example the 25% of men aged 5564 at highest computed risk (> or =1%) experience only 46% of all ischaemic heart disease events. The main methods of screening should be to identify all persons with a history of cardiovascular disease events (for example identifying patients at the time of hospital discharge following a first myocardial infarction detects 50% of all heart disease deaths in a population at a false positive rate of 12%), and to use a person's age. Identifying everyone with a history of myocardial infarction or stroke in a population and everyone aged 55 or more would include 98% of all deaths from ischaemic heart disease and stroke. The five main categories of blood pressure lowering drugs, thiazides, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor antagonists and calcium channel blockers, significantly reduce blood pressure from all pre-treatment levels though the extent of the blood pressure reduction increased with pre-treatment blood pressure. The reductions were similar at standard dose for the five categories; average reduction was 9.1 systolic and 5 diastolic. The effect of combinations of two drugs on blood pressure was additive. No effect of age was apparent, given blood pressure. There were no serious metabolic consequences of using these drugs in standard dose.

CONCLUSIONS

The evidence presented indicates that three drugs in combination may reduce stroke by about two-thirds and ischaemic heart disease by half. The report suggests that the term hypertension should be avoided because it is not a disease and it implies another category (normotensives) who would not benefit from lowering blood pressure. Blood pressure reduction using combinations of safe, well-established drugs is effective in preventing cardiovascular events. It is therefore suggested that such preventive therapy be considered more widely in people who by virtue of existing disease or simply age are at risk of a heart attack or stroke regardless of initial blood pressure.

Patient effective dose from sentinel lymph node lymphoscintigraphy in breast cancer: a study using a female humanoid phantom and thermoluminescent dosemeters

The aim of this study was to measure the dose delivered to patients undergoing sentinel lymph node lymphoscintigraphy by taking into account both the transmission scan dose using a (57)Co flood source and the (99)Tc(m) internal emission dose. An adult female humanoid phantom and a set of thermoluminescent dosimeters were used in the measurements. The choice of measurement organs in the humanoid was guided by the recommendations described in the International Commission on Radiological Protection report number 60. A (57)Co flood source was used in external transmission to irradiate the humanoid at posterior, left lateral, left posterior oblique, right lateral and right posterior oblique positions. Four (99)Tc(m) deposits as internal emission sources were used to simulate patient peritumoural injection. The individual effective doses for external transmission and internal emission, normalized to the cumulated activity and expressed in micro Sv(MBq x h)(-1) were then calculated. The effective dose for a transmission scan was on average 0.061 micro Sv(MBq x h)(-1) for each (57)Co flood source position and for internal emission 0.312 micro Sv(MBq x h)(-1) and 0.291 micro Sv(MBq x h)(-1) for left and right breast injection, respectively. Using these results, the effective dose from both transmission and emission sources can be calculated according to the nuclear medicine scanning protocol and surgical procedure of the individual institution. For our protocols, the patient receives a maximum effective dose of 52 micro Sv for the 1 day protocol (18 MBq injection) and 204 micro Sv for the 2 day protocol (74 MBq injection) if only the sentinel lymph node is excised. If other tissues containing radioactivity are removed, the patient effective dose will be reduced by about 50% and 6%, respectively, for the 1 day protocol and 2 day protocol. Although the doses are low compared with other radiological examinations, the results are informative for patients concerned about radiation exposure for this new imaging technique.

Factors affecting family-centred service delivery for children with disabilities

BACKGROUND

The provision of family-centred services (FCS) emphasizes a partnership between parents and service providers so that families are involved in every aspect of services for their child. There is evidence that providing FCS is associated with improvements in parents' satisfaction with services, decreased parental stress, and positive child outcomes.

METHODS

The purpose of this study was to examine factors that are most important in determining parent perceptions of the family centredness of care and parent satisfaction with service. A cross-sectional survey was completed by 494 parents, 324 service providers, and 15 CEOs from 16 organizations delivering children's rehabilitation services. Analyses were completed using a structural equation modelling approach.

RESULTS

Survey return rates ranged from 77 to 94%. Findings indicate that the principal determinants of parent satisfaction with services are the family-centred culture at the organization and parent perceptions of FCS. Parent satisfaction with services was also influenced by the number of places where services were received and the number of health and development problems experienced by their child.

CONCLUSION

Parent satisfaction with services is strongly influenced by the perception that services are more family centred, fewer places where services were received and fewer health and development problems for their child. Ways in which organizations can improve satisfaction through carrying out family-centred behaviours are discussed.

HIV Lipodystrophy Case Definition using Artificial Neural Network Modelling

Objective

A case definition of HIV lipodystrophy has recently been developed from a combination of clinical, metabolic and imaging/body composition variables using logistic regression methods. We aimed to evaluate whether artificial neural networks could improve the diagnostic accuracy.

Methods

The database of the case-control Lipodystrophy Case Definition Study was split into 504 subjects (265 with and 239 without lipodystrophy) used for training and 284 independent subjects (152 with and 132 without lipodystrophy) used for validation. Back-propagation neural networks with one or two middle layers were trained and validated. Results were compared against logistic regression models using the same information.

Results

Neural networks using clinical variables only (41 items) achieved consistently superior performance than logistic regression in terms of specificity, overall accuracy and area under the ROC curve. Their average sensitivity and specificity were 72.4 and 71.2%, as compared with 73.0 and 62.9% for logistic regression, respectively (area under the ROC curve, 0.784 vs 0.748). The discriminating performance of the neural networks was largely unaffected when built excluding 13 parameters that patients may not have readily available. The average sensitivity and specificity of the neural networks remained the same when metabolic variables were also considered (total 60 items) without a clear advantage against logistic regression (overall accuracy 71.8%). The performance of networks considering also body composition variables was similar to that of logistic regression (overall accuracy 78.5% for both).

Conclusions

Neural networks may offer a means to improve the discriminating performance for HIV lipodystrophy, when only clinical data are available and a rapid approximate diagnostic decision is needed. In this context, information on metabolic parameters is apparently not helpful in improving the diagnosis of HIV lipodystrophy, unless imaging and body composition studies are also obtained.

Combined analysis of two-year follow-up from two open-label randomized trials comparing efficacy of three nucleoside reverse transcriptase inhibitor backbones for previously untreated HIV-1 infection: OzCombo 1 and 2

PURPOSE

To compare inhibition of HIV replication, improvements in CD4+ T-cell counts, metabolic parameters, and body shape changes after 2 years of assigned therapy in OzCombo patients.

METHOD

Study participants were those who were recruited into the open-label OzCombo 1 (1996/1997) and OzCombo 2 (1997/1998) trials. Patients in OzCombo 1 were randomized to receive indinavir in combination with zidovudine+lamivudine (AZT+3TC; n = 35), stavudine (d4T)+3TC (n = 34), or d4T+didanosine (ddI) (n = 37). OzCombo 2 patients were randomized to the same nucleoside reverse transcriptase inhibitor (NRTI) backbones with nevirapine (n = 20, 22, 23, respectively). The mean time-weighted changes from baseline in CD4 T-cell count/mL, HIV RNA (log copies/mL plasma), and proportions with detectable viral load (<500 copies plasma HIV RNA/mL) between NRTI arms over 2 years were compared by formal meta-analysis. A cross-sectional study of metabolic and body shape complications was also undertaken.

RESULTS

For the comparison of d4T+3TC and d4T+ddI to AZT+3TC, mean differences in time-weighted change from baseline in CD4 T-cell count/microL and log copies HIV RNA/mL adjusted for baseline CD4+ T-cell and HIV RNA counts were: -44 (p =.08) and -14 (p =.56) cells/microL and -0.1 (p =.40) and -0.1 (p =.6) copies/mL. Odds ratios for detectable viral load in the last study quarter were 0.6 (p =.44) and 1.0 (p =.95). The mean percent leg fat was lower in the d4T+3TC and d4T+ddI than the AZT+3TC arm (mean difference 5.1% [p =.07] and 7.6% [p =.02], respectively).

CONCLUSION

For all regimens, virological control and immunological response were maintained over 2 years. Regimens containing d4T and particularly d4T+ddI were significantly associated with increased peripheral fat loss compared with AZT+3TC.

Spasmodic dysphonia: clinical features and effects of botulinum toxin therapy in 169 patients-an Australian experience

Adductor spasmodic dysphonia (SD) is a focal laryngeal dystonia, characterised by strangled, effortful speech with breaks in pitch and phonation. Injection of laryngeal muscles with BTX is widely used in the treatment of SD. A consecutive series of 169 patients with SD, of whom 144 were treated with BTX injections, seen at St. Vincent's Hospital between 1983 and 1999 were studied prospectively. Patients underwent neurological, quantitative voice and otolaryngological assessment. Females (62.1%) outnumbered males (37.9%) and the mean age at diagnosis was 56 years (range 19-88). Adductor SD (89.4%) was more frequent than abductor SD (1.8%) or mixed SD (4.7%). Stridor was present in 14 patients (8.3%) and in 7 was the sole manifestation of the laryngeal dystonia. The median treatment outcome score was excellent in 63.2%, very good in 18.5%, satisfactory in 14.7% and unsatisfactory in 3.5%. Poorer treatment outcome was associated with abductor SD (OR = 4.69, CI [1.23, 17.92] p=0.024] and age >65 (OR = 2.83, CI [0.95, 8.42] p=0.049). Mild post-injection paralytic dysphonia was associated with longer lasting treatment (4.42 vs. 3.62 months p<0.001) and superior treatment outcome rating (1.37 vs. 1.81 p<0.001). We conclude that BTX injections are highly effective and severe adverse events are rare. Older age and abductor SD may confer a relatively poorer treatment outcome. Mild post-injection paralytic dysphonia may be a marker for more effective and lasting treatment in adductor SD.

HIV lipodystrophy: prevalence, severity and correlates of risk in Australia

OBJECTIVE

To establish the prevalence, severity and factors associated with the HIV lipodystrophy syndrome.

METHODS

Cross-sectional study of lipodystrophy conducted in high HIV caseload primary care sites and HIV outpatient clinics. A subset of patients was examined using dual energy X-ray absorptiometry (DEXA) and single cut abdominal computerized tomography (CT) at the L4 vertebral level to quantify regional and total body fat. Factors associated with lipodystrophy, lipoatrophy and lipohypertrophy were assessed using multiple logistic regression based on assignment of cases and non-cases.

RESULTS

One thousand, three hundred and forty-eight patients (95% male) were surveyed, 20% had AIDS, the mean CD4 lymphocyte count was 486 cells/microL, and 55% had <500 HIV-1 RNA copies/mL. Most participants (87%) had previously received or were currently receiving combination antiretroviral therapy, 73% with at least one protease inhibitor (PI) and 14% a non-PI-containing regimen. Lipodystrophy prevalence was 53% and of these, 55% reported both peripheral lipoatrophy and central lipohypertrophy, 31% experienced peripheral lipoatrophy only and 14% had central lipohypertrophy only. The prevalence of any body habitus change was 62% in PI-experienced patients, 33% in PI-naive patients and 21% in antiretroviral-naive patients. Lipodystrophy severity was less in antiretroviral-naive patients and most severe in PI-experienced patients. Increasing severity of lipodystrophy was both positively and significantly correlated with elevated liver enzymes, decreased testosterone levels, decreased skin-fold thickness, lower levels of total and peripheral fat (DEXA) and higher levels of visceral fat (CT). Lipodystrophy was also significantly associated with increasing age, symptomatic HIV disease, effective viral suppression, and increasing duration of therapy with both nucleoside reverse transcriptase inhibitors and PIs.

CONCLUSIONS

The prevalence and severity of lipodystrophy reflects both length and type of treatment with antiretroviral therapy and is associated with decreased testosterone, increases in liver enzymes and greater suppression of HIV RNA. The reports of lipodystrophy in a small percentage of antiretroviral-naive patients suggests that factors other than antiretroviral therapy may be involved in the aetiology of this syndrome or that some conditions, such as wasting or age-associated obesity, may mimic lipoatrophy and lipohypertrophy, respectively.

Organ distribution of prion proteins in variant Creutzfeldt-Jakob disease

In this article we give an overview of the transmissible spongiform encephalopathies, with emphasis on the evidence for the distribution of abnormal prions in tissues. The normal prion protein is distributed ubiquitously throughout human body tissues. Endogenous expression of the normal prion protein, as well as auxiliary proteins, plays a part in accumulation of the abnormal prion protein. As exemplified by variant Creutzfeldt-Jakob disease (vCJD) the abnormal prion protein can accumulate in the host lymphoid system, in particular the follicular dendritic cells. The route for the disease-related prion neuroinvasion is likely to involve the peripheral nervous system. An alternative route may involve blood constituents. Both animal studies and studies on vCJD patients suggest a potential for abnormal prion distribution in several peripheral tissues other than the lymphoreticular system. In human beings the abnormal prion has been reported in the brain, tonsils, spleen, lymph node, retina, and proximal optic nerve. Infectivity, although present in peripheral tissues, is at lower levels than in the central nervous system (CNS). Animal models suggest that the growth of infectivity in the CNS is likely to be gradual with maximum values during the clinical phase of disease. That tissues may harbour the abnormal prion, at different levels of infectivity, during the incubation period of the disease raises concerns of iatrogenic transmission of the disease either after surgery, blood transfusion, or accidental organ transplantation from donors in the preclinical phase of the disease.

An objective case definition of lipodystrophy in HIV-infected adults: a case-control study

BACKGROUND

Lipodystrophy (peripheral lipoatrophy, central fat accumulation, and lipomatosis) is a common and disfiguring problem in adult patients with HIV-1 infection on antiretrovirals. However, an objective, validated definition of the disorder does not exist. We aimed to develop an objective, sensitive, specific, and broadly applicable case definition of HIV lipodystrophy.

METHODS

In a case-control study, 1081 consecutive, HIV-infected, adult outpatients (261 [15%] women) without active AIDS were recruited from 32 sites worldwide. We classed patients with at least one moderate or severe subjective lipodystrophic feature, identified by lipodystrophy-specific physical examination and patient questionnaire, and apparent to both doctor and patient as cases (n=417). We classed patients with no such feature as controls (n=371), and patients without a clear diagnosis as non-assigned. We used objective clinical, metabolic, and body composition measurements to construct a logistic regression model with a subset of randomly selected cases and controls. The model was validated in the remaining patients.

FINDINGS

A model including age, sex, duration of HIV infection, HIV disease stage, waist to hip ratio, anion gap, serum HDL cholesterol concentration, trunk to peripheral fat ratio, percentage leg fat, and intra-abdominal to extra-abdominal fat ratio had 79% (95% CI 70-85) sensitivity and 80% (95% CI 71-87) specificity for diagnosis of lipodystrophy. Models that incorporated only clinical, or only clinical and metabolic variables had lower sensitivity and specificity than the inclusive model. Models for lipoatrophy, fat accumulation, and lipomatosis could not be developed since pure phenotypes occurred in fewer than 10% of patients with clinical diagnoses of these disorders.

INTERPRETATION

Our objective case definition of HIV-associated lipodystrophy should improve assessment of lipodystrophy prevalence, risk factors, and pathogenesis; prevention and treatment approaches; and assist in diagnosis.

Modelling the 3-year risk of myocardial infarction among participants in the Data Collection on Adverse Events of Anti-HIV Drugs (DAD) study

OBJECTIVES

To estimate the 3-year risk of myocardial infarction (MI) among participants in the Data Collection on Adverse Events of Anti-HIV Drugs (DAD) study.

METHODS

Conventional cardiovascular risk equations were applied to baseline data from the DAD study to estimate the 3-year risk of MI. Best estimates were obtained by simply applying the risk equations, with upper and lower limits based on worst case and optimistic case scenarios. Three-year risks of AIDS or death were also estimated based on a prognostic scoring system for patients receiving antiretroviral (ARV) treatment, and on estimated AIDS rates in untreated people with HIV for those patients not on ARVs or if they were to cease ARVs.

RESULTS

Analyses were based on 17 600 patients (24.3% female) recruited into the DAD study with baseline data and no previous MI. The overall 3-year risk of MI was estimated to be 0.72% (lower limit 0.35, upper limit 1.12%), corresponding to a total predicted 127 (65-197) MIs over a 3-year follow-up period. The risk was much greater for men than women (0.92% vs. 0.07%), with only three (2-8) MIs predicted in women. The 3-year risk of MI was estimated to increase from 0.30% (0.20-0.38%) in ARV naive patients to 1.07% (0.43-1.77%) in patients receiving ARVs from all three drug classes. The estimated 3-year risk of AIDS or death was in the range 6.2% to 11.1% in patients receiving ARVs if they continued treatment, and 22.5% to 29.4% if they ceased ARVs.

DISCUSSION

These models suggest that although the increase in relative risk of MI as a result of ARV treatment may be as high as threefold in a worst case scenario, the absolute risk is modest with a best estimate of 3-year risk less than or equal to 1% in all groups of patients, and is outweighed by the benefits of ARV treatment in terms of reduced risk of AIDS and death in most patients. As estimates are based on models not validated for people receiving ARV drugs, all estimates should be interpreted cautiously.

Spectroscopic magnetic resonance imaging of a tumefactive demyelinating lesion

Tumefactive demyelinating lesions can present with features similar, clinically and radiologically, to those of brain tumours. Proton MR spectroscopy has been increasingly used to characterize intracranial pathology. As the underlying pathophysiology of neoplasms is different from that of demyelinating disease, one may expect the metabolic composition of neoplasms to be significantly different from that of demyelinating lesions. We report a 49-year-old woman in whom the neurologic and radiologic findings were highly suggestive of a high-grade brain tumor, and the spectroscopic features were sufficiently similar to that of a tumor to convince the neurosurgeon to operate. This case emphasizes the need for caution when confronted with a patient who presents with a differential diagnosis of demyelinating lesion versus neoplasm.

Creutzfeldt-Jakob disease in Australia 1970-1999

OBJECTIVE

To ascertain all persons who developed a transmissible spongiform encephalopathy (TSE) within Australia during the 30-year period 1970 to 1999 through a comprehensive national surveillance program and subject the group to detailed epidemiologic analysis.

METHODS

Cases were ascertained through reviews of morbidity separation coding data from all university-affiliated tertiary referral hospitals, as well as the centralized data bases of state and territory health departments, regular national death certificate searches, and semiannual mailout questionnaires to all neurologists and pathologists throughout Australia. Prospective monitoring commenced in September 1993.

RESULTS

A total of 387 patients were confirmed as having TSE during this epoch. The majority of cases were sporadic Creutzfeldt-Jakob disease (CJD) (90.7%), with 7.2% heredofamilial and 2.1% iatrogenic. Over this 30-year period, the national average annual sporadic CJD incidence rate per million progressively increased from 0.31 for the decade 1970 through 1979 to 0.77 for 1980 through 1989, reaching 1.03 for 1990 through 1999. Death certificates were found to have a false-positive rate of 11.5% and sensitivity of 83.0% for sporadic CJD.

CONCLUSIONS

Within Australia, there has been a gradual increase in the incidence of transmissible spongiform encephalopathy over the three-decade period 1970 through 1999, peaking in 1999 at 1.4/million/year for sporadic Creutzfeldt-Jakob disease. This increase is believed secondary to improved case ascertainment. Variant Creutzfeldt-Jakob disease was not identified during this period. Age- and sex-adjusted comparisons showed a decline in incidence rates in the elderly in both sexes, usually from age 74 years. Death certificates were a useful but imperfect method of case detection.