Design of a multi-detector, single line-of-sight, time-of-flight system to measure time-resolved neutron energy spectra

In the dynamic environment of burning, thermonuclear deuterium-tritium plasmas, diagnosing the time-resolved neutron energy spectrum is of critical importance. Strategies exist for this diagnosis in magnetic confinement fusion plasmas, which presently have a lifetime of ∼10¹² longer than inertial confinement fusion (ICF) plasmas. Here, we present a novel concept for a simple, precise, and scale-able diagnostic to measure time-resolved neutron spectra in ICF plasmas. The concept leverages general tomographic reconstruction techniques adapted to time-of-flight parameter space, and then employs an updated Monte Carlo algorithm and National Ignition Facility-relevant constraints to reconstruct the time-evolving neutron energy spectrum. Reconstructed spectra of the primary 14.028 MeV n_DT peak are in good agreement with the exact synthetic spectra. The technique is also used to reconstruct the time-evolving downscattered spectrum, although the present implementation shows significantly more error.

Impact of time from symptom onset on the diagnostic performance of high-sensitivity cardiac troponin for type 1 myocardial infarction

Background

High-sensitivity cardiac troponin has enabled the rapid rule-out and rule-in of myocardial infarction at presentation. However, increases in cardiac troponin may not be detectable early after symptom onset, and uncertainty remains as to how time of symptom onset influences diagnostic performance.

Purpose

To evaluate the impact of time from symptom onset on the diagnostic performance of high-sensitivity cardiac troponin for type 1 myocardial infarction.

Methods

In a secondary analysis of a prospective multicentre randomised controlled trial of consecutive patients with suspected acute coronary syndrome, we evaluated the diagnostic performance of high-sensitivity cardiac troponin I measurements at presentation stratified by time of symptom onset to blood sampling. Diagnostic performance was evaluated in four groups (≤3 hours, 4–6 hours, 7–12 hours and >12 hours from symptom onset) for recommended thresholds to rule-out (sex-specific 99th centile and optimised threshold [64 ng/L]) type 1 myocardial infarction.

Results

This analysis included 41,104 patients (median 60 [interquartile range 49–74] years, 46% female) of which 12,595 (31%), 10,298 (25%), 7,171 (17%) and 11,040 (27%) presented ≤3 hours, 4–6 hours, 7–12 hours and >12 hours, respectively. Type 1 myocardial infarction was the adjudicated diagnosis in 3,692 (9%) patients. For the rule-out of type 1 myocardial infarction, sensitivity was highest in those tested 7–12 hours from symptom onset and lowest in those tested ≤3 hours. In early presenters, a threshold of <2 ng/L had greater sensitivity and negative predictive value (99.4% [95% CI 98.9 to 99.7%] and 99.7% [95% CI 99.5 to 99.9%]) compared to <5 ng/L (96.7% [95% CI 95.7 to 97.6%] and 99.3% [95% CI 99.1 to 99.5%], respectively). In those tested >3 hrs from symptom onset, the sensitivity and negative predictive value for both thresholds were similar, but a threshold of <5 ng/L correctly ruled out more patients (60% [17,056/28,506] versus 29% [8,316/28,506]). For the rule-in of myocardial infarction, the sensitivity of the 99th centile and 64 ng/L was lowest in patients tested within 3 hours (71.7% [95% CI 69.3 to 74.1%] and 46.5% [95% CI 44.1 to 49.2%], respectively), and increased in those tested later from symptom onset. The specificity and positive predictive value were highest when testing was performed 7–12 hours from symptom onset for the sex-specific 99th centile (92.4% [95% CI 91.8 to 93.0%] and 51.3% [95% CI 48.2–54.5%]) and 64 ng/L (96.2% [95% CI 95.7 to 96.7%] and 61.2% [95% CI 57.3 to 65.2%]).

Conclusions

The diagnostic performance of cardiac troponin for myocardial infarction is strongly influenced by the time from symptom onset to testing. In early presenters the limit of detection may facilitate immediate rule-out of myocardial infarction, but otherwise testing at least 3 hours from symptom onset is needed with the optimal time to rule-in myocardial infarction being 7–12 hours from the onset of symptoms.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation (BHF)Medical Research council UK (MRC)

Impact of patient selection on performance of an early rule-out pathway for myocardial infarction: from research to the real world

Background

Early rule-out pathways for myocardial infarction using high-sensitivity cardiac troponin are widely recommended in the assessment of patients with suspected acute coronary syndrome. Although developed in selected patients participating in research studies, these pathways are applied more widely in clinical practice where the diagnostic performance and effectiveness of these pathways may differ.

Purpose

To evaluate the performance of an early rule-out pathway for myocardial infarction using high-sensitivity cardiac troponin in selected and consecutive unselected patients with suspected acute coronary syndrome.

Methods

Presentation and serial high-sensitivity cardiac troponin I concentrations were measured in two cohorts of patients with suspected acute coronary syndrome presenting to the Emergency Departments across three acute care hospitals in Scotland. In the unselected cohort, electronic health record data were collected on consecutive patients in whom the usual care clinician measured cardiac troponin for suspected acute coronary syndrome. In the selected cohort, patients with suspected acute coronary syndrome were approached between 8am and 8pm by research staff and written informed consent obtained. In both cohorts, the performance of the High-STEACS early rule-out pathway was evaluated for an adjudicated diagnosis of myocardial infarction (type 1, type 4b or type 4c) during the index hospital admission.

Results

The unselected and selected patient cohorts comprised of 1,242 (median age 60 [interquartile range 47–75] years, 46% women) and 1,695 (median age 61 [52–73] years, 40% women) patients respectively. Myocardial infarction was diagnosed in 6% (74/1,242) and 14% (232/1,695) of patients in the unselected and selected patient cohorts respectively. More patients had myocardial infarction ruled-out in the unselected (74% [828/1,112] versus 66% [1,102/1,678]; P<0.001), with similar negative predictive value (99.9% [95% CI 99.7%-100%] versus 99.7% [95% CI 99.4%-99.0%) and sensitivity (99.3% [95% CI 97.4%-100%] versus 98.9% [95% CI 97.6%-99.9%]; Figure 1). In the selected cohort, more patients had intermediate troponin concentrations requiring serial testing (36% versus 29%) or had myocardial infarction diagnosed (34% versus 26%; P<0.001 for both). In contrast, the positive predictive value for myocardial infarction was lower in unselected patients (26.1% [95% CI 21.2%-31.4%] versus 39.9% [95% CI 35.9%-44.0%]).

Conclusion

The prevalence of myocardial infarction is lower in patients with suspected acute coronary syndrome evaluated in routine practice compared to those selected to participate in a research study. Whilst more patients have myocardial infarction accurately ruled out, the positive-predictive value in those ruled in is lower resulting in more hospital admissions with elevated cardiac troponin due to other conditions.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart FoundationMedical Research Council

Mechanisms of myocardial injury and clinical outcomes in patients hospitalised with suspected COVID-19

Background

Myocardial injury is associated with adverse outcomes in patients with COVID-19. However, the prognostic role of myocardial injury in COVID-19 compared to other acute illnesses and the underlying mechanisms of injury are poorly understood.

Methods

In a prospective, multi-centre, cohort study conducted in secondary and tertiary care hospitals in Scotland, all consecutive patients with suspected COVID-19 underwent cardiac troponin (ARCHITECTSTAT high-sensitive troponin I (hs-cTnI) assay; Abbott Laboratories) testing in plasma that was surplus to clinical requirements. The results were not reported unless required by the attending clinician. We evaluated the prevalence of myocardial injury, mechanisms and outcomes in all patients. In those with any hs-cTnI concentration above the sex-specific 99th centile the diagnosis was adjudicated according to the 4th Universal Definition of Myocardial Infarction. The primary outcome of all-cause mortality was compared in those with and without myocardial injury and COVID-19 by cox regression adjusted for age, sex, renal function and co-morbidities.

Results

A total of 2,916 (median age 69 [interquartile range, IQR 54–79] years, 53% women) consecutive patients with suspected COVID-19 were followed up for 228 [IQR 203–249] days. Myocardial injury occurred in 26% (750/2,916) with a median troponin concentration of 66 [35–178] ng/L; the prevalence was 41% (46/112) and 25% (704/2,804) in those with and without COVID-19, respectively. The most common mechanism was acute non-ischaemic myocardial injury occurring in 80% (37/46) and 71% (502/704) of patients with and without COVID-19, respectively. Type 1 myocardial infarction (2% and 4%), type 2 myocardial infarction (7% and 14%) and chronic myocardial injury (11% and 11%) were less common and only one patient had confirmed myocarditis. In patients with myocardial injury mortality was increased compared to those without (P<0.001 log rank), whether they had COVID-19 (54% [25/46] versus 26% [17/66]) or not (35% [248/704] versus 14% [294/2100]). Myocardial injury was an independent predictor of death in all patients (adjusted hazard ratio [aHR] 2.04, 95% confidence interval [CI] 1.71 to 2.43), but this excess risk was not higher in patients with COVID-19 (aHR 1.58, 95% CI 0.75 to 3.15) compared to those without the condition (aHR 2.01, 95% CI 1.81 to 2.49).

Conclusion

Myocardial injury is common in hospitalised patients with suspected COVID-19 whether or not COVID-19 was the cause of their presentation. The majority of patients had acute non-ischaemic myocardial injury rather than a defined cardiac condition. Despite this the presence of myocardial injury was an independent predictor of death in all hospitalised patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation Kaplan-Meier curve for all-cause death

Precise measurement of the neutron magnetic form factor G(M)n in the few-GeV2 region

The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q;{2}=1.0-4.8 GeV2 with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data.

Measurements of H-->D-->(gamma-->,pi) and implications for the convergence of the Gerasimov-Drell-Hern integral

We report new measurements of inclusive pi production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microb, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microb lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise, and generally lower than available calculations.

Measurement of direct f0(980) photoproduction on the proton

We report on the results of the first measurement of exclusive f_{0}(980) meson photoproduction on protons for E_{gamma}=3.0-3.8 GeV and -t=0.4-1.0 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the pi;{+}pi;{-} channel by performing a partial wave analysis of the reaction gammap-->ppi;{+}pi;{-}. Clear evidence of the f_{0}(980) meson was found in the interference between P and S waves at M_{pi;{+}pi;{-}} approximately 1 GeV. The S-wave differential cross section integrated in the mass range of the f_{0}(980) was found to be a factor of about 50 smaller than the cross section for the rho meson. This is the first time the f_{0}(980) meson has been measured in a photoproduction experiment.

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3T

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3T field strength and thereby improve the diagnostic quality of the images obtained.

Neoadjuvant chemotherapy in breast cancer: early response prediction with quantitative MR imaging and spectroscopy

A prospective study was undertaken in women undergoing neoadjuvant chemotherapy for locally advanced breast cancer in order to determine the ability of quantitative magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to predict ultimate tumour response (percentage decrease in volume) or to detect early response. Magnetic resonance imaging and MRS were carried out before treatment and after the second of six treatment cycles. Pharmacokinetic parameters were derived from T₁-weighted dynamic contrast-enhanced MRI, water apparent diffusion coefficient (ADC) was measured, and tissue water : fat peak area ratios and water T₂ were measured using unsuppressed one-dimensional proton spectroscopic imaging (30 and 135 ms echo times). Pharmacokinetic parameters and ADC did not detect early response; however, early changes in water : fat ratios and water T₂ (after cycle two) demonstrated substantial prognostic efficacy. Larger decreases in water T₂ accurately predicted final volume response in 69% of cases (11/16) while maintaining 100% specificity and positive predictive value. Small/absent decreases in water : fat ratios accurately predicted final volume non-response in 50% of cases (3/6) while maintaining 100% sensitivity and negative predictive value. This level of accuracy might permit clinical application where early, accurate prediction of non-response would permit an early change to second-line treatment, thus sparing patients unnecessary toxicity, psychological morbidity and delay of initiation of effective treatment.

Differentiation of benign from malignant breast disease associated with screening detected microcalcifications using dynamic contrast enhanced magnetic resonance imaging

Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) is an effective diagnostic modality for symptomatic breast disease. However, its role in evaluating clinically occult disease associated with mammographically detected microcalcification remains unclear. Women recalled following screening mammography with microcalcification had DCE-MRI examination of the breast. The data were evaluated subjectively and objectively using both empirical and 2-compartment pharmacokinetic modelling techniques to evaluate signal intensity parameters. Eighty-eight patients aged 50-75 years (median 58) were recruited. Comparing malignant and benign lesions, the mean values in arbitrary units for the enhancement index at 1 min in the most enhancing 9-pixel square +/-1 standard deviation were 0.61+/-0.40 vs. 0.22+/-0.26 p=<0.001 with sensitivity, specificity, PPV, NPV and accuracy of 80.0%, 82.4%, 57.1%, 93.3% and 81.8%, respectively. The corresponding values attained by the radiologist were 75.0%, 89.7%, 68.2%, 92.4% and 86.4%. DCE-MRI is able to differentiate malignant from benign clinically occult lesions associated with microcalcification and may therefore offer an alternative to open surgical biopsy for women with equivocal findings following initial triple assessment for microcalcification in the breast.

Differentiation of benign and malignant sub-1 cm breast lesions using dynamic contrast enhanced MRI

The purpose of this work is to assess the additional benefit of MRI-based morphology and quantification of contrast enhancement in the differential diagnosis of sub-1cm breast lesions. Forty-three women with suspected breast cancer were examined using X-ray mammography, ultrasound mammography, and MRI. Dynamic contrast imaging was performed and relative enhancement at various time-points was calculated. The dynamic data was also processed using a two-compartment pharmacokinetic model. Radiological interpretation of high-resolution post-contrast images revealed a similar accuracy (69%) compared to X-ray mammography (69%) and ultrasound mammography (67%). The best individual parameter calculated from the dynamic images was found to be the exchange rate constant which revealed a diagnostic accuracy of 0.74 +/- 0.08. When information from the post-contrast images and dynamic data was combined in a logistic regression model a diagnostic accuracy of 0.92 +/- 0.03 was achieved. In conclusion, MR imaging of small breast lesions is feasible and the incorporation of quantitative MR derived parameters is beneficial.

Systematic review of proton magnetic resonance spectroscopy of the striatum in parkinsonian syndromes

It has been suggested that proton magnetic resonance spectroscopy (MRS) of the striatum can differentiate between parkinsonian syndromes. The present study aims to examine this claim by performing a systematic review of the existing literature. A MEDLINE search was performed between 1966 and October 1999, along with searches of conference abstracts and reference lists of papers identified. Eleven groups have used MRS to examine metabolite ratios in the striatum in Parkinsonian syndromes. A number of these have shown reduced N-acetylaspartate/choline (NAA/Cho) and/or N-acetylaspartate/creatine (NAA/Cr) ratios in either idiopathic Parkinson's disease (IPD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP) or corticobasal degeneration. However, the heterogeneity in the results precludes the use of any of these findings in differential diagnosis at the present time. The only group to use absolute metabolite concentrations rather than ratios showed that the decreased NAA/Cho ratio in IPD was because of an increase in choline which is of uncertain biological significance. Further large multicentre trials are required using absolute quantitation of tissue metabolite concentrations and a standardized technique. The patients entering such studies must be rigorously assessed to establish the diagnosis of the type of parkinsonism as accurately as possible. Any discriminatory abnormality must be tested in a large prospective study of newly presenting parkinsonian patients with long-term clinical follow up and ultimate pathological confirmation of the diagnosis as far as possible.

An open-label acceptability study of Norditropin SimpleXx--a new liquid growth hormone formulation

A new liquid formulation of hGH (Norditropin SimpleXx) has been developed to avoid the need for reconstitution before administration. In addition, the liquid GH formulation has been combined with an advanced pen delivery system, either with or without a needle auto-insertion mechanism. This study was designed to assess the acceptability of the new system compared with the patient's previous system. A total of 103 children with GH deficiency received a daily injection of Norditropin liquid GH for 12 weeks with a choice of a pen/auto-insertion system. Acceptability was determined by nurse-supervised questionnaires administered to the patients and parents. Following treatment, 94% of patients preferred the Norditropin liquid GH system. This preference was irrespective of the previous system in use, patient age or length of GH therapy. More patients found it the less painful system (50% vs 13%), 92% of patients found it more convenient, and the formulation was well tolerated. In conclusion, Norditropin liquid GH was very well accepted and preferred by the majority of patients. It avoided reconstitution which had been a major cause of dissatisfaction with the patients' previous systems, and resulted in greater convenience and reduced levels of pain associated with injection.

Combined proton MR spectroscopy and dynamic contrast enhanced MR imaging of human intracranial tumours in vivo

A study was undertaken to determine if the vascular characteristics measured by dynamic contrast-enhanced magnetic resonance imaging (primarily permeability surface area product and extracellular-extravascular tissue volume fraction) would be beneficial in explaining the inter-lesion metabolic heterogeneity displayed by human intracranial tumours. Magnetic resonance spectroscopy was carried out using a single-voxel STEAM sequence and dynamic imaging was carried out using a combination of pre-contrast proton density-weighted FSPGR images (to remove the influence of native tissue T1), bolus injection of Gd-DTPA and subsequent T1-weighted FSPGR dynamic imaging. A two-compartment pharmacokinetic model was employed to determine vascular characteristics. Results obtained from 12 meningiomas suggest a possible correlation between the level of lipids/macromolecules and permeability surface area product, although the confounding issue of extra-voxel contamination arising from lipids in the scalp and skull marrow cannot be ruled out in the more superficial lesions. Results obtained from 11 gliomas (four low and seven high grade) demonstrate that permeability surface area product is not specific for the range of vascular characteristics and metabolite profiles observed in gliomas and is therefore unable to explain metabolic heterogeneity in these lesions.

Basal ganglia metabolite concentrations in idiopathic Parkinson's disease and multiple system atrophy measured by proton magnetic resonance spectroscopy

Six patients with idiopathic Parkinson's disease (IPD), six with clinically probable multiple system atrophy and six control subjects underwent quantitative proton magnetic resonance spectroscopy (MRS). The concentrations of the three major metabolites, N-acetylaspartate (NAA), creatine and choline, were quantified in the lentiform nucleus using tissue water content as an internal concentration reference. Glutamate was assessed as the (glutamate + glutamine)/creatine peak area ratio (Glx/Cre). In the control subjects the mean (+/- SD) concentrations of the three metabolites were 15.2 +/- 2.9 micromol/g wet weight for NAA, 12.0 +/- 1.4 for creatine and 2.4 +/- 0.3 for choline. The Glx/Cre ratio was 1.28 +/- 0.32. The only significant difference in any metabolite concentration was in the lentiform nucleus of patients with IPD compared with controls, with an increase in choline which lead to a significant reduction in the NAA/choline ratio. The relevance of this finding is uncertain. The results of the present pilot study, combined with the conflicting findings from previous work, suggest that further, much larger, studies are required to evaluate the diagnostic capability of proton MRS.

Computer assisted learning: the potential for teaching and assessing in nursing

This article discusses computer assisted learning (CAL) and the importance of applying it in nurse education. The articles recognizes the general technological developments as exemplified by the Teaching and Learning Technology Programme (TLTP) from which ideas about application and benefits came. The ideas from TLTP are hereby used in CAL and applied to nursing and health-care undergraduate programmes in one university. In the light of this experience the main intention of this article is to consider the benefits and costs of introducing computer programmes as part of the teaching provision for nurses and other health-care professionals both at beginner and advanced level. The article further argues that CAL can also be used for patient teaching thus providing transferable skills and benefits for teachers as well as learners, be they students or patients. To support such multiple uses of CAL selected examples will be offered and appropriate conclusions will be drawn.

Dealing with problems in clinical practice

The identification of problems and how they are dealt with is affected by the individual perspectives of all parties involved. Mike Lowry discusses how groups of nurses often have difficulty accepting that problems exist and suggests ways they might go about identifying and dealing with them.

The Glasgow Coma Scale in clinical practice: a critique

Nurses need to be able to assess a patient's neurological state and record changes in this status over time. One instrument for classifying neurological status is the Glasgow Coma Scale (GCS). Its use is now widespread, although it has not been validated. This article describes the weaknesses of this method and points to an alternative.

Working in syndicate groups towards the development of clinical care protocols: a study into the professional learning of undergraduate nursing students

Group work is an important element in nurse education and practice, and is an issue of consistent relevance given the increasing emphasis on collaborative and multidisciplinary working, and the fact that most nurses' work involves them in a variety of groups. This study is ongoing research, and considers the experiences of five groups, each comprising four final year nursing undergraduate students working in syndicate groups. The students are working towards the creation and development of clinical care protocols. The study method is grounded theory. Data have been collected over 3 academic years, with the group facilitator as researcher. The data management involves tape recording meetings and transcribing these, with continual reduction and analysis of the data. Findings from early analysis suggest that important phenomena, for example 'resistance', 'tangible action goals', and the concept of 'closure', play a key part in the way in which the groups under study have functioned.

Clinical supervision for the development of nursing practice

Nursing practice demands a range of problem-solving skills and abilities, and preregistration courses may only provide limited preparation. Clinicians need to draw on the skills and expertise of experienced colleagues in order most effectively to use their time and energies in a new role or clinical area. Experienced staff may enhance both their clinical expertise and their support of colleagues through the role of clinical supervisor. Clinical supervision has benefits for the supervisor in terms of professional development and for the supervisee as regards identifying and addressing clinical problems. According to the position statement on clinical supervision for nurses and health visitors published by the UKCC (UKCC, 1996) clinical supervision aims to identify solutions to problems, improve practice and increase understanding of professional issues. This article examines roles and responsibilities in clinical supervision and discusses the benefits for individuals and for health services.

In vivo quantification of citrate concentration and water T2 relaxation time of the pathologic prostate gland using 1H MRS and MRI

We have previously reported a striking correlation between water T2 relaxation time and citrate concentration in the normal prostate (Liney G.P.; Lowry M.; Turnbull L.W.; Manton D.J.; Knowles A.J.; Blackband S.J.; Horsman A. Proton MR T2 maps correlate with the citrate concentration in the prostate. NMR Biomed. 9:59-64; 1996). In this study we present data from similar studies of the pathologic gland. The findings support the hypothesis that measurement of both citrate concentration and water T2 relaxation time in vivo may aid the differentiation of prostatic carcinoma from benign disease and normal tissue.

Unchanged basal ganglia N-acetylaspartate and glutamate in idiopathic Parkinson's disease measured by proton magnetic resonance spectroscopy

The lentiform nucleus of five patients with idiopathic Parkinson's disease (IPD) was studied by quantitative magnetic resonance spectroscopy (MRS), both before and after administration of apomorphine, and the spectra were compared with those from a group of age-matched normal subjects. The concentrations of the three major metabolites, choline, creatine, and N-acetylaspartate (NAA), were quantified using tissue water content as an internal concentration reference. Glutamate concentration was assessed as the (glutamate + glutamine; GLX)/creatine peak area ratio. In normal subjects, the mean +/- SD concentrations of the the three metabolites were 2.4 +/- 0.4 mumol/g wet wt for choline, 11.5 +/- 0.8 mumol/g for creatine, and 14.7 +/- 2.8 mumol/g for NAA. The Glx/creatine ratio was 1.26 +/- 0.12. There was no significant difference in these parameters in the lentiform nucleus of patients with IPD either before or after apomorphine. The absence of detectable differences in IPD in this study implies that the changes in glutamate metabolism in the basal ganglia predicted by animal work are more subtle than those currently observable by MRS.

Teaching patients with newly diagnosed diabetes

Diabetes mellitus is a condition with potentially serious complications, which may be preventable with appropriate patient teaching. Patient teaching for the group in this study appears to have failed adequately to meet their needs. Health-care professionals have a responsibility to prepare patient teaching according to patients' perceived needs rather than simply those prescribed by carers.

Using learning contracts in clinical practice

A learning contract is focused on the process of learning as well as the content. Control is vested in the clinical learner. Learning contracts can be particularly useful for the newly qualified staff nurse.

Quantification of citrate concentration in the prostate by proton magnetic resonance spectroscopy: zonal and age-related differences

A commercial phased-array multicoil was used to acquire water-suppressed localized proton spectra of the two major anatomical regions of the prostate. The signal-to-noise ratio and spectral resolution allowed identification of peaks from choline and creatine, as well as a major peak from citrate. Quantification of the citrate peak using experimentally determined relaxation parameters with tissue water as an internal concentration reference revealed a marked variability between different volunteers. Nevertheless, in each case, the citrate concentration was up to fourfold greater in the peripheral zone than in the central gland. Furthermore, the difference in citrate concentration between these two regions was positively correlated with the subjects age. The results indicate a consistent difference in cellular function between the major anatomical regions within the prostate and may have important consequences for the application of magnetic resonance spectroscopy to the diagnosis of prostatic pathology.

Developing nurse-led primary health care

General practice in the community is ripe for development. Nurses need to value their skills and abilities. Continuing education and research is an integral part of practice development. There is a need for vision and creativity in nurse leaders.

Proton MR T2 maps correlate with the citrate concentration in the prostate

A significant correlation between water T2 relaxation time and citrate concentration in the normal prostate is demonstrated using spatially localized spectroscopy and water T2 maps. These data imply that MR images may be used to infer the concentration of citrate at high spatial resolution. Preliminary results in patients demonstrate that this relationship is maintained in benign prostatic hyperplasia (BPH) and prostatic carcinoma. The determination of citrate concentration and water T2 may aid the differentiation of prostate carcinoma from BPH and normal tissue.

Evaluating a patient teaching programme

Patient teaching is an essential element of care that should involve the multidisciplinary team. Patients and their significant others must have access to patient teaching programmes in order that they may make informed choices. The design of the programme must be considered carefully in order to meet the needs of patients and their significant others. Patients clearly benefit from well-organised and appropriately planned patient teaching programmes.

Determination of proton metabolite concentrations and relaxation parameters in normal human brain and intracranial tumours

Quantitative proton spectroscopic studies were performed on 39 volunteers and 16 patients with intracranial tumours. Estimates of T2 were obtained in white matter, grey matter, cerebellum, astrocytomas and meningiomas; T1 was determined in white matter only. White matter values of T2 for trimethylamines, creatine and N-acetyl aspartate (NAA) were 309 +/- 84, 195 +/- 41 and 369 +/- 124 ms, respectively (mean +/- SD, n = 20). Metabolite concentrations in white matter were 2.0 +/- 0.4 mumol/g wet weight for trimethylamines, 7.3 +/- 1.1 for creatine and 11.4 +/- 1.4 for NAA. The mean concentrations of creatine and NAA in grey matter and all of three metabolites in cerebellum were greater than those in white matter. Tumour spectra were characterized by increased trimethylamines, reduced creatine and NAA and occasionally the presence of lactate. Meningiomas were further characterized by the presence of alanine. The mean T2 and concentration of trimethylamines in tumours was significantly greater than in normal brain. Creatine and NAA concentrations were decreased in all tumours. The longer T2 of trimethylamines and presence of alanine in meningiomas indicate that important differences exist in membrane and glucose metabolism within these tumours when compared to either astrocytomas or normal brain tissue.

Planning and writing academic essays

To write academic essays to a high standard takes time, practice and skill, but the process can be facilitated by appropriate guidance. This article examines the requirements for planning and writing academic essays. It considers the reasons for writing them, and explains how best to plan and prepare the work for presentation. Some guidelines as to how essays may be assessed by tutors are also provided.

Knowledge that reduces anxiety. Creating patient information leaflets

1. Patient information is an essential ingredient of caring, which needs to be both carefully considered and consistent. 2. Creating information leaflets should be a collaborative effort, involving members of the multidisciplinary team. 3. There are demonstrable benefits in providing information for patients, including compliance and patient empowerment. 4. Team working is enhanced by having common understandings. It also improves interdisciplinary communication. 5. There are cost benefits in taking time to produce good quality patient information leaflets.

Quality assessment in in vivo NMR spectroscopy: IV. A multicentre trial of test objects and protocols for performance assessment in clinical NMR spectroscopy

A multicentre trial of test objects and protocols for performance assessment in single volume and slice selective magnetic resonance spectroscopy (MRS) was conducted by the European Community Concerted Action on MRI and MRS. The trial assessed phosphorus and proton localisation techniques implemented on commercially available MR systems at ten sites in Europe. At each site, a number of parameters devised by the Concerted Action were measured using prototype test objects. Some of these parameters related to the quality of localisation and others to the overall performance of the spectrometer. Results were obtained for the ISIS, DRESS, STEAM, and PRESS sequences with a range of acquisition parameters, allowing evaluation of the assessment methodology and comparison of the efficacy of various implementations of these localisation techniques. The results of this trial have been important in the development of the Concerted Action's final recommendations for MRS performance assessment, and demonstrate that such assessment provides valuable information in the comparison of spectroscopy data from different sites and in the development of new localisation sequences, and provides a means of quality assurance in MRS.

Phosphorus-31 metabolism of post-menopausal breast cancer studied in vivo by magnetic resonance spectroscopy

We have studied the metabolism of 31P-containing metabolites of post-menopausal breast cancers in vivo using magnetic resonance spectroscopy (MRS) and a 5.5 cm surface coil. Spectra were acquired from 23 diameter. The spectra of the 19 previously untreated tumours had significantly higher phosphomonoester (PME) 31P relative peak areas than the normal breasts of eight post-menopausal women (11.7% and 7.7% respectively, P = 0.002). Although an increased PME relative peak area was characteristic of malignancy, PME relative peak area is similarly raised in lactating breast and, therefore, not a specific feature of cancer. An apparently lower nucleotide triphosphate (NTP) relative peak area in tumours than healthy postmenopausal breast was secondary to the differences in PME relative peak area; contamination by signal from chest wall muscle probably accounts for the ostensibly higher phosphocreatine (PCr) relative peak area of the tumours. Spectroscopy was repeated following chemotherapy in six women. An increase in PCr relative peak area was seen in all five patients who responded, but again this may represent increased contamination secondary to changes in tumour size. A fall in PME relative peak area was noted in four responders, but also one non-responder, so this finding may not be sufficiently specific to be of use clinically. Further studies are need to elucidate fully the role of MRS in breast cancer.

Trisomy 12 mosaicism in a 7 year old girl with dysmorphic features and normal mental development

We present the case of a mentally normal 7 year old girl with short stature, scoliosis, atrial septal defect, and dysmorphic features including linear pigmented streaks on the forearms and lower legs. Chromosome analysis of cultured fibroblasts showed trisomy 12 in 9% and 13% of cells from two skin biopsies. Two trisomy 12 cells were found in lymphocytes after analysis of 500 metaphases. Her clinical features are compared with those of other liveborn cases of trisomy 12 mosaicism and the problems of prenatal diagnosis of such an abnormality are discussed.

Phosphorus-31 metabolism of human breast--an in vivo magnetic resonance spectroscopic study at 1.5 Tesla

We have studied the metabolism of compounds containing 31P in normal breast using magnetic resonance spectroscopy (MRS). Spectra were acquired from non-lactating pre-menopausal breast (n = 14 women), lactating breast (n = 8) and post-menopausal breast (n = 8). The standard acquisition protocol used a 5.5 cm surface coil with the volunteer prone to minimize chest wall signal contamination. In pre-menopausal non-lactating women the phosphocreatine (PCr) peak area, expressed relative to the sum of all 31P peak areas, was negatively correlated with breast size (r = -0.56, p = 0.02) suggesting that much of the PCr signal originated from the chest wall. The phosphodiester (PDE) relative peak area was positively correlated with breast size (r = 0.71; p = 0.002). Spectra could be acquired at all phases of the menstrual cycle. In sequential examinations of five women not taking the oral contraceptive pill (OCP), phosphomonoester (PME) relative peak area was significantly lower on Week 2 than other weeks of the cycle (p = 0.03). Among pre-menopausal women no clear difference was apparent between the spectra from women taking the OCP and those not taking the OCP. Lactating breast had significantly higher PME relative peak area than non-lactating pre-menopausal breast (p = 0.02), probably reflecting the higher proportion of epithelial tissue in lactation; the lower PCr relative peak area in lactating breast (p = 0.05) is probably due to the greater size of the breast during lactation. Spectra were acquired from post-menopausal women but with a relatively low signal-to-noise ratio. The only significant difference between 31P relative peak areas of breast spectra acquired from pre- and post-menopausal women was that less PCr was detected in the post-menopausal volunteers (p = 0.03), probably as a result of differences in breast size.