CT of cecal volvulus: unraveling the image.
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Adult↗
Biomedical subjects
C J Moore
Publications and source records attributed to C J Moore.
3D dynamic body surface sensing and CT-body matching: a tool for patient set-up and monitoring in radiotherapy.
Recent advances in radical broad-beam conformal radiotherapy for disease at non-rigid sites suggest that the treatment room set-up of patients should be performed using the CT-plan digital body surface as a reference standard. In effect, the CT-plan surface is a "virtual shell" and should be used as such. To do this requires 3D body surface information to be captured live in the treatment room and then manipulated for comparison with the CT virtual shell. To address this situation, a near real-time prototype opto-electronic dynamic 3D surface sensor has been developed and equipped with a novel software utility for visualizing and matching the disparate surfaces arising from planning and treatment environments. Using the CT virtual shell and height-maps produced by the sensor, a two-phase 3D positioning strategy for patient set-up and monitoring is described. Phase one is an image-guided manual "approach". Phase two is automated "docking" using simulated annealing to determine optimum set-up corrections. The concepts and implementation are illustrated using archival patient data and an anthropomorphic phantom "patient" in a treatment room environment.
Humans↗
Use of a clonidine patch in the treatment of ischemic ulcerations of the foot.
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Administration, Cutaneous↗
Three distinct ventral occipitotemporal regions for reading and object naming.
This study investigates word and object processing during naming and viewing tasks and identifies three distinct regions in the left ventral occipitotemporal cortex. Irrespective of task, words and objects (relative to meaningless visual controls) activated the medial surface of the left anterior fusiform gyrus, a region that has previously been associated with semantic knowledge. A more lateral region was differentially active for naming words and objects relative to viewing the same stimuli and a more posterior region was differentially active for objects relative to words irrespective of task. In addition, we found that word processing resulted in greater activation than object processing on the dorsal surface of the left superior temporal gyrus and the left supramarginal gyrus. These regions appear to be important for converting orthography into phonology; their response to words irrespective of task is consistent with established psychological evidence that implicit phonological processing is stronger for words than objects.
Adult↗
Animation and radiobiological analysis of 3D motion in conformal radiotherapy.
PURPOSE: To allow treatment plans to be evaluated against the range of expected organ motion and set up error anticipated during treatment. METHODS: Planning tools have been developed to allow concurrent animation and radiobiological analysis of three dimensional (3D) target and organ motion in conformal radiotherapy. Surfaces fitted to structures outlined on CT studies are projected onto pre-treatment images or onto megavoltage images collected during the patient treatment. Visual simulation of tumour and normal tissue movement is then performed by the application of three dimensional affine transformations, to the selected surface. Concurrent registration of the surface motion with the 3D dose distribution allows calculation of the change in dose to the volume. Realistic patterns of motion can be applied to the structure to simulate inter-fraction motion and set-up error. The biologically effective dose for the structure is calculated for each fraction as the surface moves over the course of the treatment and is used to calculate the normal tissue complication probability (NTCP) or tumour control probability (TCP) for the moving structure. The tool has been used to evaluate conformal therapy plans against set up measurements recorded during patient treatments. NTCP and TCP were calculated for a patient whose set up had been corrected after systematic deviations from plan geometry were measured during treatment, the effect of not making the correction were also assessed. RESULTS: TCP for the moving tumour was reduced if inadequate margins were set for the treatment. Modelling suggests that smaller margins could have been set for the set up corrected during the course of the treatment. The NTCP for the rectum was also higher for the uncorrected set up due to a more rectal tissue falling in the high dose region. CONCLUSION: This approach provides a simple way for clinical users to utilise information incrementally collected throughout the whole of a patient's treatment. In particular it is possible to test the robustness of a patient plan against a range of possible motion patterns. The methods described represent a move from the inspection of static pre-treatment plans to a review of the dynamic treatment.
Computer Graphics↗
A functional neuroimaging study of the variables that generate category-specific object processing differences.
Brain damage can cause remarkably selective deficits in processing specific categories of objects, indicating the high degree of functional segregation within the brain. The neuroimaging study presented here investigates differences in the neural activity associated with two categories of natural objects (animals and fruit) and two categories of man-made objects (vehicles and tools). Stimuli were outline drawings and the tasks were naming and word-picture matching. For man-made objects, the only category-specific effect was in the left posterior middle temporal cortex, which was most active for drawings of tools, as previously reported. For natural objects, drawings of animals and fruit (relative to drawings of man-made objects) enhanced activity in bilateral anterior temporal and right posterior middle temporal cortices. Critically, these effects with natural objects were not observed when the stimuli were coloured appropriately to facilitate identification. Furthermore, activation in the same right hemisphere areas was also observed for viewing and matching unfamiliar non-objects relative to naming and matching man-made objects. These results indicate that, in the right hemisphere, differences between processing natural relative to man-made objects overlap with the effects of increasing demands on object identification. In the left hemisphere, the effects are more consistent with functional specialization within the semantic system. We discuss (i) how category-specific differences can emerge for multiple reasons and (ii) the implications of these effects on the interpretation of functional imaging data and patients with category-specific deficits.
Adult↗
Partnership to engage St. Louis high school students in investigative genetics.
The authors describe the Modern Genetics Project, based on a successful hands-on science implementation model that was developed and field-tested in St. Louis area high schools between 1992 and 1998. The project, begun in 1991, features a curriculum enhancement unit, "Modern Genetics for All Students," that combines strong scientific content, hands-on investigations, and human health applications, with reference to developing national and state science-teaching standards for this topic. The unit provides a significantly higher level of hands-on involvement throughout the school year for students than is found in traditional biology classrooms. This project aims to enhance scientific literacy among St. Louis high school students (all grades) of all learning levels and all socioeconomic, racial, and ethnic backgrounds; many of the students using the curriculum are from underrepresented minorities. This long-term project is carried out by a strong partnership among scientists at Washington University, implementation specialists from the Mathematics and Science Education Center of the Cooperating School Districts of St. Louis, project evaluators from Southern Illinois University at Edwardsville, and biology teachers at local high schools. Funding was originally from the National Institutes of Health and is now from the Howard Hughes Medical Institute. In 1998, there were 31 teachers and approximately 3,200 students participating in the project. Both quantitative and qualitative evaluations of the project during the 1995-96 and 1996-97 school years indicate that there were significant gains in knowledge and attitudes among the students of all racial, ethnic, and socioeconomic groups represented, and among both boys and girls.
Adolescent↗
Premutation female carriers of fragile X syndrome: a pilot study on brain anatomy and metabolism.
OBJECTIVE: It was thought that premutation carriers of fragile X syndrome (FraX) have no neurobiological abnormalities, but there have been no quantitative studies of brain morphometry and metabolism. Thus the authors investigated brain structure and metabolism in premutation carriers of FraX. METHOD: Eight normal IQ, healthy female permutation FraX carriers aged 39 +/- 9 years (mean +/- SD) and 32 age-sex-handedness-matched controls (39 +/- 10 years) were studied; in vivo brain morphometry was measured using volumetric magnetic resonances imaging, and regional cerebral metabolic rates for glucose were measured using positron emission tomography and (18F)-2-fluoro-2-deoxy-D-glucose. RESULTS: Compared with controls, FraX premutation carriers had a significant (1) decrease in volume of whole brain, and caudate and thalamic nuclei bilaterally; (2) increase in volume of hippocampus and peripheral CSF bilaterally, and third ventricle; (3) relative hypometabolism of right parietal, temporal, and occipital association areas; (4) bilateral relative hypermetabolism of hippocampus; (5) relative hypermetabolism of left cerebellum; and (6) difference in right-left asymmetry of the Wernicke and Broca language areas. CONCLUSIONS: Premutation carriers of FraX, as defined by analysis of peripheral lymphocytes, have abnormalities in brain anatomy and metabolism. The biological basis for this is unknown, but most likely it includes tissue heterogeneity for mutation status. The findings may be of relevance to people counseling families with FraX and to understanding other neuropsychiatric disorders which are associated with expansion of triplet repeats and genetic anticipation.
Adult↗
Delineating necessary and sufficient neural systems with functional imaging studies of neuropsychological patients.
This paper demonstrates how functional imaging studies of neuropsychological patients can provide a way of determining which areas in a cognitive network are jointly necessary and sufficient. The approach is illustrated with an investigation of the neural system underlying semantic similarity judgments. Functional neuroimaging demonstrates that normal subjects activate left temporal, parietal, and inferior frontal cortices during this task relative to physical size judgments. Neuropsychology demonstrates that damage to the temporal and parietal regions results in semantic deficits, indicating that these areas are necessary for task performance. In contrast, damage to the inferior frontal cortex does not impair task performance, indicating that the inferior frontal cortex might not be necessary. However, there are two other possible accounts of intact performance following frontal lobe damage: (1) there is functional reorganization involving the right frontal cortex and (2) there is peri-infarct activity around the damaged left-hemisphere tissue. Functional imaging of the patient is required to discount these possibilities. We investigated a patient (SW), who was able to associate words and pictures on the basis of semantic relationships despite extensive damage to the left frontal, inferior parietal, and superior temporal cortices. Although SW showed peri-infarct activation in left extrasylvian temporal cortices, no activity was observed in either left or right inferior frontal cortices. These findings demonstrate that activity in extrasylvian temporo-parietal and medial superior frontal regions is sufficient to perform semantic similarity judgments. In contrast, the left inferior frontal activations detected in each control subject appear not to be necessary for task performance. In conclusion, necessary and sufficient brain systems can be delineated by functional imaging or brain-damaged patients who are not functionally impaired.
Brain↗
Enhancement and associative restoration of electronic portal images in radiotherapy.
Electronic portal imaging devices use the high energy treatment beam to project the body interior of the patient during radiation onto a fluorescent screen that is scanned by a camera. Because of the imaging physics, the unprocessed images of very poor quality, but they are the only available information during treatment for observation of the patient's organs. This paper presents an approach that combines an associative restoration algorithm with a fuzzy image enhancement technique. By fusion of the electronic portal image (EPI) with a pre-treatment captured simulator image (SI) a higher image quality than by conventional techniques is achieved.
Algorithms↗
How well is the net cost of fractionated radiotherapy predicted by radiobiological parameters?
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Cost-Benefit Analysis↗
Predicting late rectal complications following prostate conformal radiotherapy using biologically effective doses and normalized dose-surface histograms.
A model to predict the late normal tissue complication probability (NTCP) of the rectum following conformal therapy is described. The model evaluates the biological consequence of inhomogeneities in the physical dose by computing dose histograms of the biologically effective dose to the surface of the rectum for a given fractionation scheme. A method of normalizing the surface area of the rectum is employed so that the predicted NTCP is independent of the differing cross-sectional size of sections of the rectum, ensuring the NTCP is dependent only on the dose delivered to sensitive rectal tissues. The model has been used to assess severe late rectal complications and the milder RTOG grades 2 and 3 reactions. This model was found to predict severe toxicity levels of 1.7 +/- 0.6% for an accelerated treatment of 50 Gy in 16 fractions commonly employed at this centre. This result lies between the severe toxicities predicted for 60 and 62 Gy delivered in 2 Gy fractions. The model predicts that the average NTCP for severe late effects for nine prostate patients becomes greater than 5% with a fractionation scheme of 70 Gy in 35 fractions, for the four fields treatment. The effects of not treating all fields at each therapy session on rectal toxicity were also investigated. Biologically effective dose-surface histograms show that the dose to the lower surface of the rectum is increased by not treating all fields at each therapy session, but the predicted differences in rectal NTCP are negligible.
Dose-Response Relationship, Radiation↗
The neural regions sustaining object recognition and naming.
This positron emission tomography study dissociates the neural correlates of object recognition and naming. Stimuli comprised coloured outline drawings of objects and coloured nonsense shapes. Subjects either viewed or explicitly named objects, similarly they viewed or named the colour of the shapes. Activations common to object and colour naming were identified by contrasting the explicit naming conditions (objects and colours) with the control (viewing) conditions. Activations associated with object recognition were identified by contrasting both object conditions (naming and viewing) with both shape conditions and activations specific to object or colour naming were identified by contrasting object naming (relative to object viewing) with colour naming (relative to shape viewing). The results associate: (i) object recognition with left middle occipital and bilateral anterior temporal cortices; (ii) modality independent naming with left posterior basal temporal lobe and the left prefrontal cortex; (iii) areas specific to object naming with left temporal extrasylvian regions, left anterior insula and right cerebellum; and (iv) areas specific to colour naming with left posterior lingual and fusiform gyri and midline cerebellum. These results are discussed in relation to previous neuroimaging and neuropsychological findings.
Adult↗
The effect of varying stimulus rate and duration on brain activity during reading.
The effect of the presentation rate and exposure duration of visually presented words on brain activity was investigated using positron emission tomography. Subjects either read aloud or silently mouthed the names of words. In regions associated with early visual analysis, activity increased with both rate and duration; in regions associated with response generation, activity increased with increasing rate but was unaffected by duration; and in regions associated with word recognition, activity decreased with increasing duration. The variable responses of different brain regions illustrate the functional segregation of these regions. Of particular interest was the dissociation between activity in the posterior fusiform gyri and that in the medial lingual gyrus--in the former, activity increased with rate and duration but the latter was unaffected by either variable. This finding suggests that word processing in the lingual gyrus during reading is distinct from that in the posterior fusiform gyri. A further observation was that during reading aloud, when subjects can hear the sound of their own voice, the response in the primary auditory cortices increased with stimulus rate, demonstrating that subjects process the sound of their own voice in a qualitatively similar way to words spoken by another.
Adult↗
Hearing and saying. The functional neuro-anatomy of auditory word processing.
The neural systems involved in hearing and repeating single words were investigated in a series of experiments using PET. Neuropsychological and psycholinguistic studies implicate the involvement of posterior and anterior left perisylvian regions (Wernicke's and Broca's areas). Although previous functional neuroimaging studies have consistently shown activation of Wernicke's area, there has been only variable implication of Broca's area. This study demonstrates that Broca's area is involved in both auditory word perception and repetition but activation is dependent on task (greater during repetition than hearing) and stimulus presentation (greater when hearing words at a slow rate). The peak of frontal activation in response to hearing words is anterior to that associated with repeating words; the former is probably located in Brodmann's area 45, the latter in Brodmann's area 44 and the adjacent precentral sulcus. As Broca's area activation is more subtle and complex than that in Wernicke's area during these tasks, the likelihood of observing it is influenced by both the study design and the image analysis technique employed. As a secondary outcome from the study, the response of bilateral auditory association cortex to 'own voice' during repetition was shown to be the same as when listening to "other voice' from a prerecorded tape.
Auditory Perception↗
An ethical analysis of the use of xenografts in human transplant surgery.
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Animal Experimentation↗
Chromosomal radiosensitivity in G2-phase lymphocytes as an indicator of cancer predisposition.
Sanford et al. (Int. J. Radiat. Biol. 55, 963-981, 1989) have reported that G2-phase cells from many heritable cancer-prone conditions exhibit higher yields of X-ray-induced chromosome damage than those found in the majority of healthy controls. We have applied their protocol to lymphocytes of a group of control and cancer-prone individuals to see if we could confirm these observations. For control donors we observed higher aberration yields, different kinetics and more interexperiment variability than found by Sanford et al. These differences could not be attributed to unavoidable minor variations in procedures (e.g. serum batches, glassware washing methods), but the difference in X-ray qualities used in the two laboratories may have made a small contribution to the discrepancies. We attribute some of our experimental variability to the fact that, to varying extents in different experiments, centrifugation of cells prior to irradiation can slow down the progression of cells into metaphase and that cells can continue to repair during the harvesting procedure (centrifugation and hypotonic treatment). We have applied the assay to cases of ataxia telangiectasia (AT, homozygotes and heterozygotes), xeroderma pigmentosum (homozygotes and heterozygotes), familial adenomatous polyposis and the syndromes Li-Fraumeni, basal cell nevus, Down's and Fanconi's but have been unable to discriminate between these groups and controls except for AT homozygotes. By including a control sample in parallel with samples from cancer-prone groups we found a significant difference in mean aberration yields between controls and AT homozygotes and heterozygotes, but not for the other groups. Since technical features could explain the discrepancies between our laboratories, we have devised our own G2-phase assay which appears to be giving promising results.
Adenomatous Polyposis Coli↗
Limonene chemoprevention of mammary carcinoma induction following direct in situ transfer of v-Ha-ras.
Monoterpenes, including limonene and its in vivo rat plasma metabolites, have been shown to be inhibitors of protein isoprenylation of small G proteins, including p21 ras. In addition, dietary limonene has been shown to be capable of preventing the development and causing the regression of chemically induced mammary carcinomas, many of which contain activated ras oncogenes. On the basis of these observations, it was hypothesized that a possible mechanism by which limonene exerts its effects on the chemoprevention and regression of mammary tumors involves the inhibition of protein isoprenylation of the small G protein p21. In the first study, we asked whether dietary limonene was able to prevent the development of mammary carcinomas which were induced using direct retroviral gene transfer of v-Ha-ras into the mammary parenchyma in situ. Limonene modified neither the rate of gene transfer nor the stability of gene expression. However, limonene did greatly inhibit the formation of mammary carcinomas induced by the insertion of activated ras. In a follow-up study, we asked whether chemoprevention by limonene was preferentially effective against a subset of chemically induced mammary carcinomas with activated ras. Rats were fed limonene to prevent the development of N-nitroso-N-methylurea-induced mammary tumors, a majority of which contain the activated Ha-ras oncogene. As expected, limonene administration increased the latency period and lowered the frequency of mammary carcinoma development as compared to controls. However, tumor characterization revealed that limonene treatment did not alter the percentage of carcinomas with activated ras. These studies are consistent with the above studies in that limonene is effective in preventing mammary carcinomas with activated ras. Interestingly, carcinomas without activated ras were prevented to the same extent as those with the activated oncogene.
Animals↗