Accuracy of magnetic resonance imaging in determining cause of sudden death in adults: comparison with conventional autopsy

AIM

To determine the accuracy and define the limitations of post mortem magnetic resonance imaging (MRI) in determining the cause of sudden death in adults.

METHODS AND RESULTS

Sudden unexpected adult deaths in the community, reported to the Coroner (n = 10), excluding suspicious, violent or potentially drug-related deaths, were submitted to whole body MRI, followed by full invasive autopsy. The MRI scans were reported independently by four radiologists, blinded to the autopsy findings; two had previous experience of post mortem MRI. An abnormality that related to the cause of death as identified at autopsy, was identified by at least one radiologist in eight cases. These were pulmonary consolidation (autopsy finding pneumonia) (n = 1), pneumoperitoneum (autopsy finding perforated peptic ulcer) (n = 2), left ventricular failure (autopsy finding ischaemic heart disease) (n = 4), and disseminated bronchial carcinoma (n = 1). However, in only one case were all radiologists able to provide a confident cause of death (disseminated bronchial carcinoma). In two cases, in which death occurred 2-6 days and 3-6 days before MRI, early decomposition prevented interpretation of the images. Severe coronary artery atheroma was detected at autopsy in 7/10, but these lesions were not detected by MRI. Previous experience in reporting post mortem MRI, without autopsy comparison, did not result in more accurate interpretation of the images.

CONCLUSIONS

This pilot study suggests that post mortem MRI can identify some abnormalities relating to the common causes of sudden death in adults, but there is a need for greater experience in correlating MRI with autopsy findings before a reliable cause of death can be made by MRI alone. Inability to image coronary artery lesions, differentiating thrombus from clot and pulmonary oedema from pneumonic exudates, are specific problems that may be corrected with greater experience and higher resolution scans.

Identification of genes regulated during osteoblastic differentiation by genome-wide expression analysis of mouse calvaria primary osteoblasts in vitro

Although several independent studies of gene expression patterns during osteoblast differentiation in cultures from calvaria and other in vitro models have been reported, only a small portion of the mRNAs expressed in osteoblasts have been characterized. We have previously analyzed the behavior of several known markers in osteoblasts, using Affymetrix GeneChip murine probe arrays (27,000 genes). In the present study we report larger groups of transcripts displaying significant expression modulation during the culture of osteoblasts isolated from mice calvaria. The expression profiles of 601 such regulated genes, classified in distinct functional families, are presented and analyzed here. Although some of these genes have previously been shown to play important roles in bone biology, the large majority of them have never been demonstrated to be regulated during osteoblast differentiation. Despite the fact that the precise involvement of these genes in osteoblast differentiation and function needs to be evaluated, the data presented herein will aid in the identification of genes that play a significant role in osteoblasts. This will provide a better understanding of the regulation of osteoblast differentiation and maturation.

Maternal activity in relation to birth size in rural India. The Pune Maternal Nutrition Study

OBJECTIVE

To describe the relationship of the mother's physical activity to the birth size of her baby in a rural Indian population.

DESIGN

: Prospective observational study.

SETTING

Six villages near Pune, Maharashtra, India.

SUBJECTS

: A total of 797 women were studied after excluding abortions and termination of pregnancies (112), foetal anomalies (8), multiple pregnancies (3), incomplete pre-pregnancy anthropometry (14) and pregnancies detected later than 21 weeks of gestation (168).

METHOD

An activity questionnaire was developed after focus group discussions and incorporated community-specific activities. It was validated against an observer-maintained diary. Activity scores were derived using published data on energy costs to weight the contributions of various activities. It was then administered to assess physical activity at 18 (+/-2) and 28 (+/-2) weeks of gestation.

OUTCOME MEASURES

Birth outcome, maternal weight gain and neonatal anthropometry.

RESULTS

The activity questionnaire was used to classify women into light, moderate and heavy activity categories. Maternal activity did not influence the incidence of prematurity or stillbirth, or the duration of gestation. It was inversely related to maternal weight gain up to 28 weeks of gestation (P=0.002). Higher maternal activity in early, as well as mid gestation, was associated with lower mean birth weight (P=0.05 and 0.02, respectively ), and smaller neonatal head circumference (P=0.005 and 0.009) and mid-arm circumference (P=0.03 and 0.01) after adjusting for the effect of major confounding factors.

CONCLUSIONS

The Findings suggest that excessive maternal activity during pregnancy is associated with smaller foetal size in rural India, The approach described for developing an activity questionnaire has potential for adoption in other settings.

Is clinical growth index a reliable predictor of tumour growth in vestibular schwannomas?

We have assessed the clinical growth index as an indicator of tumour growth rate in 50 patients with a vestibular schwannoma. Clinical growth index was calculated by measuring the length of history and dividing it by the maximum tumour diameter. Total tumour volumes were also measured from all MRI examinations and an effective tumour volume doubling time was calculated. Radiological growth measurements demonstrated involution in 10/50 patients. The median volume doubling time was 1.65 years (range 20.9-46.3 months, skewness 1.72 years). The median clinical growth index was 0.030 cm per month (range 0-0.270 cm per month, skewness 2.398). There was no significant correlation between volume doubling time and clinical growth index. Identification of rapidly growing tumours with clinical growth index >0.025 cm/month had a positive predictive value of 61%, negative predictive value of 48%, false-positive rate of 30% and false-negative rate of 52%. In conclusion, we have shown that the growth rate of vestibular schwannoma is not related to the clinical growth index and we recommend that this measure should be abandoned in the clinical management of patients where conservative management regimes are being considered.

The use of sentinel node biopsy in the treatment of cancer of an accessory breast

A patient with an accessory breast on the anterior abdominal wall was found to have cancer of this tissue, because of its unusual position it was decided that lymphatic mapping was necessary to identify the lymphatic drainage of this tumour. A metastasis was found in a sentinel node deep to the 'true' ipsilateral breast; however, the sentinel node identified in the axilla of this patient was free of metastases. The use of the sentinel node technique up staged the cancer from I to II and the patient went on to have adjuvant treatment with chemotherapy. The use of lymphatic mapping and sentinel node biopsy in the case of cancer of an accessory breast allows more accurate determination of lymph node status.

Reproducibility of quantitative dynamic contrast-enhanced MRI in newly presenting glioma

We have investigated the reproducibility of dynamic contrast enhanced imaging techniques in nine patients with cerebral glioma. Patients were imaged twice with a 2 day interval between scans. Maps were produced of the time taken to achieve 90% enhancement (T90), the maximal intensity change per time interval ratio (MITR), the volume transfer coefficient between plasma and the extravascular extracellular space (K(trans)) and the extravascular extracellular contrast distribution volume, v(e). Measurements of K(trans) greater than 1.2 min(-1) were used to exclude pixels where first pass perfusion effects dominated the measurement. Measures of the test-retest coefficient of variation (CoV) and intraclass correlation coefficients were used to assess reproducibility for measurements from a volume of interest containing enhancing tissue from the whole tumour. MITR showed poor reproducibility (mean CoV 17.9%, 95% confidence limits for group comparisons 20.2%). T90 showed good reproducibility (mean CoV 7.1%, 95% confidence limits for group comparisons 5.2%). Calculated values of K(trans) and v(e) also showed good reproducibility (mean CoV 7.7% and 6.2% respectively, 95% confidence limits for group comparisons 6.2% and 4.8%, respectively). We conclude that the measurements of K(trans) and v(e) derived from pharmacokinetic analysis are sufficiently reproducible to support their use as a biological markers in therapeutic trials.

Successful umbilical cord blood stem cell transplantation for chronic granulomatous disease

Chronic granulomatous disease (CGD) causes growth failure, inflammatory lung damage and often early death. Prophylactic cotrimoxazole improves medium-term survival, but cannot prevent inflammatory sequelae. We report the first patient with CGD who underwent successful HLA identical sibling umbilical cord stem cell transplantation (UCSCT) after myeloablative conditioning. The patient presented with colitis, confirmed as CGD at 2 years of age. Following BU16/CY200 conditioning, he had UCSCT from his unaffected HLA identical sister. A year post-transplant, his colitis had resolved clinically and on radioisotope scan growth has improved. Neutrophil oxidative burst was 92% normal with full donor lymphocyte reconstitution.

Can dynamic susceptibility contrast magnetic resonance imaging perfusion data be analyzed using a model based on directional flow?

PURPOSE

To examine the implications of a physiological model of cerebral blood that uses the contradictory assumption that blood flow in all voxels of DSCE-MRI data sets is directional in nature. Analysis of dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSCE-MRI) uses techniques based on indicator dilution theory. Underlying this approach is an assumption that blood flow through pixels of gray and white matter is entirely random in direction.

MATERIALS AND METHODS

We have used a directional flow model to estimate theoretical blood flow velocities that would be observed through normal cerebral tissues. Estimates of flow velocities from individual pixels were made by measuring the mean transit time for net flow (nMTT). Measurements of nMTT were made for each voxel by estimating the mean difference in contrast arrival time between each of the adjacent six voxels.

RESULTS

Examination of the spatial distribution of contrast arrival time from DSCE-MRI data sets in normal volunteers demonstrated clear evidence of directional flow both in large vessels and in gray and white matter. The mean velocities of blood flow in gray and white matter in 12 normal volunteers were 0.25 +/- 0.013 and 0.21 +/- 0.014 cm/second, respectively, compared to predicted values of 0.25 and 0.18 cm/second. These values give measured nMTT for a 1-mm isotropic voxel of gray and white matter of 0.45 +/- 0.12 and 0.52 +/- 0.11 seconds, respectively, compared to predicted values of 0.47 and 0.55 seconds.

CONCLUSION

A directional model of blood flow provides an alternative approach to the calculation of cerebral blood flow from (CBF) DSCE-MRI data.

Predictors of outcome of mammography in the National Health Service Breast Screening Programme

BACKGROUND

Little is known about the factors influencing the risk of recall for assessment, invasive diagnostic procedures, and early rescreening after screening mammography.

METHODS

From June 1996 to March 1998 women attending screening at 10 National Health Service Breast Screening Programme (NHSBSP) centres completed a self administered questionnaire and were followed up for their screening outcome.

RESULTS

1969 (3.3%) out of 60 443 women aged 50-64 who had never used hormone replacement therapy (HRT) were recalled for assessment but were not diagnosed with breast cancer (defined here as false positive recall). After adjustment for the variation between centres, false positive recall was decreased significantly among women who were likely to have had a previous NHSBSP mammogram (odds ratio (OR) 0.49, 95% confidence interval (95% CI) 0.38 to 0.63 for likely versus unlikely), who were postmenopausal (OR 0.65, 95% CI 0.56 to 0.76 for postmenopausal v premenopausal) and increased significantly for women reporting previous breast surgery (OR 1.64, 95% CI 1.42 to 1.89). Although false positive recall decreased significantly with parity and increasing body mass index, these effects were not large and no significant variation was found with age, education, family history of breast cancer, oral contraceptive use, sterilisation, exercise, smoking, or alcohol consumption. Altogether 655 (1.1%) women had an invasive diagnostic procedure; no personal characteristics were predictive of this outcome, 286(0.5%) were referred for early rescreening, and this was increased significantly by nulliparity and a family history of breast cancer.

INTERPRETATION

Premenopausal women, those without a previous NHSBSP mammogram, and women with previous breast surgery have an increased risk of false positive recall by the NHSBSP.

Simultaneous mapping of blood volume and endothelial permeability surface area product in gliomas using iterative analysis of first-pass dynamic contrast enhanced MRI data

We describe a novel method for the calculation of endothelial permeability surface area product from dynamic contrast enhanced MRI. The technique uses iterative estimation to automatically decompose tissue residue function into intravascular and extravascular components, which are subsequently used to generate tumour blood volume, which is equal to relative cerebral blood volume calculated from T(1) weighted images and corrected for contamination by contrast agent leakage (rCBV(T1)(corrected), and endothelial permeability (k(fp)) maps. The technique was assessed in patients with cerebral glioma (n=5) by examining the reproducibility of endothelial permeability and rCBV(T1)(corrected) between two separate examinations conducted with a 2-day interval. The technique produces maps of endothelial permeability that appear to be free of any contribution from intravascular contrast agent. Maps of rCBV(T1)(corrected) show close correlation with maps of blood volume calculated from independently acquired dynamic susceptibility weighted MRI examinations, with no evidence of residual permeability effects. The results were highly reproducible with strong intra-class correlation between the two examinations for mean values and for 97.5 percentiles of endothelial permeability and rCBV(T1)(corrected). The excellent reproducibility of this technique and the ability to calculate endothelial permeability and rCBV(T1)(corrected) values from rapidly acquired data sets offer considerable advantages over conventional approaches and support the use of this methodology for therapeutic monitoring or trials of novel therapeutic agents.

Task-dependent modulations of cortical oscillatory activity in human subjects during a bimanual precision grip task

Oscillations are a widespread feature of normal brain activity and have been reported at a variety of different frequencies in different neuronal systems. The demonstration that oscillatory activity is present in motor command signals has prompted renewed interest in the possible functions of synchronous oscillatory activity within the primate sensorimotor system. In the current study, we investigated task-dependent modulations in coupling between sensorimotor cortical oscillators during a bimanual precision grip task. The task required a hold-ramp-hold pattern of grip force to be exerted on a compliant object with the dominant right hand, while maintaining a steady grip with the nondominant hand. We found significant task-related modulation of 15- to 30-Hz coherence between magnetoencephalographic (MEG) activity recorded from the left sensorimotor cortex and electromyographic (EMG) activity in hand muscles on the right side. This coherence was maximal during steady hold, but disappeared during the ramp movements. Interestingly coherence between the right sensorimotor MEG and left-hand EMG showed a similar, although less deeply modulated, task-related pattern, even though this hand was maintaining a simple steady grip. No significant ipsilateral MEG-EMG coherence was observed in the 15- to 30-Hz passband for either hand. These results suggest that the cortical oscillators in the two sensorimotor cortices are independent to some degree but that they may share a common mechanism that attenuates the cortical power in both hemispheres in the 15- to 30-Hz range during movements of one hand. The results are consistent with the hypothesis that oscillatory activity in the motor system is important in resetting the descending motor commands needed for changes in motor state, such as those that occur in the transition from movement to steady grip.

CAMPATH-1M T-cell depleted BMT for SCID: long-term follow-up of 19 children treated 1987-98 in a single center

BACKGROUND

SCID can be cured by BMT. Depletion of mature T cells from BM has enabled HLA non-identical stem-cell transplantation. We report the outcome of 30 patients treated with 37 T-cell depleted BMT procedures using CAMPATH-1M in vitro between 1987-98 in a single center.

METHODS

Immune reconstitution and quality-of-life were assessed in 19 longterm survivors. All but two received pre-transplant conditioning. T- and B-cell chimerism, numbers and function were analyzed during a median follow-up of 5.3 years (range 1.33-12).

RESULTS

The overall engraftment rate was 59%, six children required repeated BMT and the survival rate was 63%. All have donor T cells, 58% normal T-cell numbers and 74% normal T-cell function. Of 17 evaluated, 16 patients (94%) have normal IgM and IgG levels, and production of specific Abs to protein Ags, but only 5/16 (31%) have a good response to pneumococcal polysaccharide. Early and late post-BMT complications were rare and there were no delayed deaths. Only one child continues on long-term i.v. Ig 4-years post-BMT. Eleven children died (37%).

DISCUSSION

CAMPATH-1M T-cell depleted BMT for SCID resulted in 63% survival. Deaths of 11 children were mainly due to pre-existing infections. Seventeen of 19 long-term survivors have normal immune function and good quality-of-life.

Child care decisions: parental choice or chance?

AIM

A study of the context of child care decision making by inner city and suburban mothers, using parents to help develop and administer a semi-structured questionnaire.

METHODS

A total of 131 mothers were interviewed (73 inner city and 58 suburban) at home.

RESULTS

Inner city mothers were more likely to bottle feed, smoke and adopt risky infant sleeping positions, for example the settee. Virtually all babies (98%) were fully vaccinated and placed prone (95%) to sleep at night. Inner city mothers smoked (71%) despite the known health risks and continued postnatally (55%), mainly as a means of relieving stress. In total, 30% of inner city mothers wanted to breast feed; 19% had succeeded to 6-8 weeks postnatally. Bottle feeding helped both mother and baby to have uninterrupted nights of sleep. Suburban mothers (59%) succeeded in breast feeding, with others choosing bottle feeding mostly because of returning to work. The average weekly alcohol consumption, 32 units inner city and 15 units suburban, was taken in weekend binges by inner city parents, but in daily small amounts by suburban mothers.

CONCLUSIONS

The well-being of the baby was the prime concern of all mothers, irrespective of social background. However, inner city mothers made rational decisions to smoke and bottle feed to reduce the impact of stress and allow the mother much needed respite for the good of the entire family.

Behavior of osteoblast, adipocyte, and myoblast markers in genome-wide expression analysis of mouse calvaria primary osteoblasts in vitro

Several genes, such as alkaline phosphatase, osteocalcin, and Cbfa1/Osf2, are known to be regulated during osteoblastic differentiation and are commonly used as "osteoblast markers" for in vitro or in vivo studies. The number of these genes is very limited, however, and it is of major interest to identify new genes that are activated or repressed during the process of osteoblast differentiation and bone formation as well as to extend the available information on gene families relevant to this particular differentiation pathway. To identify such genes, we have implemented a genome-wide analysis by determining changes in expression levels of 27,000 genes during in vitro differentiation of primary osteoblasts isolated from mouse calvaria. This study focuses on the description of the analytical and filtering process applied; on the transcriptional analysis of well-established "bone," "adipocyte," and "muscle" pathway markers; and on a description of the regulation profiles for genes recently described in the Skeletal Gene Database. We also demonstrate that new array technologies constitute reliable and powerful tools to monitor the transcription of genes involved in osteoblastic differentiation, allowing a more integrated vision of the biological pathways regulated during osteoblast commitment, differentiation, and function.

Rhythm generation in monkey motor cortex explored using pyramidal tract stimulation

We investigated whether stimulation of the pyramidal tract (PT) could reset the phase of 15-30 Hz beta oscillations observed in the macaque motor cortex. We recorded local field potentials (LFPs) and multiple single-unit activity from two conscious macaque monkeys performing a precision grip task. EMG activity was also recorded from the second animal. Single PT stimuli were delivered during the hold period of the task, when oscillations in the LFP were most prominent. Stimulus-triggered averaging of the LFP showed a phase-locked oscillatory response to PT stimulation. Frequency domain analysis revealed two components within the response: a 15-30 Hz component, which represented resetting of on-going beta rhythms, and a lower frequency 10 Hz response. Only the higher frequency could be observed in the EMG activity, at stronger stimulus intensities than were required for resetting the cortical rhythm. Stimulation of the PT during movement elicited a greatly reduced oscillatory response. Analysis of single-unit discharge confirmed that PT stimulation was capable of resetting periodic activity in motor cortex. The firing patterns of pyramidal tract neurones (PTNs) and unidentified neurones exhibited successive cycles of suppression and facilitation, time locked to the stimulus. We conclude that PTN activity directly influences the generation of the 15-30 Hz rhythm. These PTNs facilitate EMG activity in upper limb muscles, contributing to corticomuscular coherence at this same frequency. Since the earliest oscillatory effect observed following stimulation was a suppression of firing, we speculate that inhibitory feedback may be the key mechanism generating such oscillations in the motor cortex.