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PubMedDate not supplied

Multimodality image integration for stereotactic surgical planning.

A method is presented for integrating stereotactic projection and tomographic image data to give composite 3-D images (stereo pairs) of cerebral anatomy and vasculature. The technique serves to combine complementary information from each modality and allows the imaged volume to be viewed directly. The procedure is largely automated and requires no additional apparatus or information beyond that which is ordinarily employed during stereotactic surgical planning. The two types of data are combined by superimposing the projection angiogram (DSA) onto a translucent volume rendered CT or MR image. Since the rendering algorithm employs an orthographic projection technique, the tomographic volume must first be reshaped and oriented to yield a perspective view that matches the DSA projection. During this process, the data undergo various interpolations which consequently affect the accuracy of target identification based on the resulting images. The integrity of the matching procedure was assessed using simulated data sets. Also, calculations were performed to estimate the resolution of measurements made from digitized stereoscopic images. The resulting sub-pixel accuracy of the matched images suggests that the technique has potential for stereotactic applications. Preliminary results are presented illustrating combined CT-DSA and MR-DSA data sets.

Angiography, Digital Subtraction↗
PubMed1997

Saccadic reaction times: a statistical analysis of multimodal distributions.

The distributions of saccadic reaction times (SRT) often deviate from unimodal normal distributions. An excess-mass procedure was used to detect peaks in 963 data sets containing 90,927 reaction times from 170 subjects. About 55% showed one, 30% two, 12% three and 3% four peaks. According to their clustering along the reaction time scale the modes could be classified into express (90-120 msec), fast regular (135-170 msec) and slow regular (200-220 msec) modes. Among the unimodal distributions 29% had peaks in the range of the express mode and 46% had peaks in the range of the fast regular mode. Therefore, 87% of the data sets support the notion of saccadic reaction time distributions being the superposition of three modes. All experimental distributions were fitted by as many gamma distributions as determined by the excess-mass test. The significance of the multimodality for saccade generation processes is discussed.

Fixation, Ocular↗
PubMed1998

Effects of random perturbations in plastic optical fibers

REVIEW The most important feature of an optical fiber waveguide is its bandwidth, which defines its information-carrying capacity. A major limitation on the bandwidth of multimode glass and plastic optical fibers is modal dispersion, in which different optical modes propagate at different velocities and the dispersion grows linearly with length. However, in plastic optical fibers, experimental and theoretical results indicate that the modes are not independent but are highly coupled, which leads to a characteristic square-root length dependence and an unanticipated large enhancement of the bandwidth to gigahertz levels. The ever increasing demands for low-cost, high-bandwidth communications media for voice, video, and data transmission in short- and medium-distance applications are generating a new assessment of multimode optical fibers to serve as high-speed fiber links.

Journal Article↗
PubMedDate not supplied

Optimal power transformations for analysis of sperm concentration and other semen variables.

The nongaussian (or nonnormal) distribution of sperm concentration, and variables deriving from it, is a common practical problem in the statistical evaluation of semen data. Yet it has been little studied, and its importance to data analysis, as well as to practical remedies, is not widely appreciated. Inappropriate use of the raw scale of measurement produces inflated estimates of mean and variance, leading to false-negative (underpowered) statistical comparisons and excessive sample size estimates. This study employs the Box-Cox family of power transforms to illustrate by a simple graphical method how to identify optimal power transforms for semen data variables. Using robust statistical methods, it is shown that the nongaussian distribution is due to right skewing rather than multimodality or influential outliers. The optimal power transform, typically in the region of 0.15 to 0.35 (most easily implemented as a cube-root transformation), usually performs better than the logarithmic transformation in normalizing the data. In addition, the power transformation has an important practical advantage over the logarithmic transformation in the appropriate handling of zeros (azoospermia), a regular and important features of such data sets in practice.

Humans↗
PubMed2003

Multimodal rehabilitation for faecal incontinence: experience of an Italian centre devoted to faecal disorder rehabilitation.

BACKGROUND: Sphincter exercises and biofeedback therapy have been used to treat faecal incontinence but results have been unpredictable and standards of treatment have not yet been established. The aim of this study was to retrospectively evaluate the effects of a new multimodal rehabilitation model on faecal incontinence. METHODS: All of the rehabilitative procedures are guided by manometric data. Primary study outcome criteria were the determination of changes or deterioration in incontinence, failure to achieve full continence and/or presence of faecal urgency. The clinical outcome was designed according to the Jorge-Wexner incontinence score. RESULTS: Between 1997 and 2001, one hundred forty-nine incontinent patients (85 F and 64 M; age range, 41-73 years; mean age, 60.6 years) underwent multimodal rehabilitation at our outpatient unit. The overall mean incontinence score had significantly improved after treatment ( p<0.001), and 58 patients (38.9%) were symptom free. No patient reported any deterioration in incontinence. Faecal urgency persisted in 23 patients (15.4%). CONCLUSION: In conclusion, multimodal rehabilitation, using manometric study, can modify the incontinence score.

Adult↗
PubMed2004

Quantum dynamics of gas-phase SN2 reactions.

Understanding the state-resolved dynamics of elementary chemical reactions involving polyatomic molecules, such as the well-known reaction mechanism of nucleophilic bimolecular substitution (SN2), is one of the principal goals in chemistry. In this Review, the progress in the quantum mechanical treatment of SN2 reactions in the gas phase is reviewed. The potential energy profile of this class of reactions is characterized by two relatively deep wells, which correspond to pre- and post-reaction chargedipole complexes. As a consequence, the complex-forming reaction is dominated by Feshbach resonances. Calculations in the energetic continuum constitute a major challenge because the high density of resonance states imposes considerable requirements on the convergence and the energetic resolution of the scattering data. However, the effort is rewarding because new insights into the details of multimode quantum dynamics of elementary chemical reactions can be obtained.

Journal Article↗
PubMedDate not supplied

The relationship between audiogenic seizure (AGS) susceptibility and forebrain tone-responsiveness in genetically AGS-prone Wistar rats.

The present study characterized the intensity-response functions of extracellular field responsiveness of different cortical/subcortical structures of the forebrain following the free-field presentation of tone stimuli, within a population of genetically audiogenic seizure (AGS)-prone KM-Wistar rats. The neural response properties of each case were compared to its propensity to exhibit AGSs during the continuous tone stimulation (15 kHz, 90 s at max.). The amplitudes or slope components of the evoked responses and their peak latencies showed significant positive (amplitude and slope) and negative (peak latency) Bolzmann's sigmoid relationships with the onset-latency of AGS. These relationships, with areal differences in the slopes of saturation functions, applied for the three different data sets recorded simultaneously from the stratum radiatum dendritic layer of the hippocampal CA1 area, primary auditory cortex layers II-IV, and frontal cortex surface. In addition, the similar type of functions between the evoked response variables and AGS onset latency held when all the areas were considered together. These data suggest that the neural responsiveness to acoustic stimulation of the primary sensory, multimodal and association cortices of the forebrain may altogether contribute to the seizure initiation by that modality in the genetically AGS-prone rats. It has been previously shown that there exist abundant and dispersed auditory projections from these forebrain areas to the brain stem and spinal cord, structures that are generally considered to be the key predisposing factors in the generation of AGS. Hence, the types of correlation found reflect the subject-specific stage of forebrain responsiveness, being either related or unrelated to genetic AGS-specific changes, and possibly its triggering impact upon the lower brain AGS network. Accordingly, the mere comparison of forebrain response measures of these AGS-prone animals with those of the AGS-resistant ones could not reveal the result presented.

Acoustic Stimulation↗
PubMedDate not supplied

Design methods and architectural issues of integrated medical image data base systems.

The past 20 years have seen tremendous changes in medical imaging techniques. New modalities and protocols are expanding the available digital image data at a rapid rate. Yet a framework for gathering, managing, and using multimodal image information is an integrated database environment is missing. The purpose of this paper is to present the experience of implementing an integrated medical image database system at UCSF. We discuss the general system architecture, software design methods, and specific database tools and illustrate them with application examples. Two immediate issues conforming the building of medical image database systems are: lack of supporting infrastructure and inability to index images by contest. To circumvent these problems, the evolutionary medical image database system being implemented at UCSF is based on a three-tiered client-server architecture: client medical workstations, database application servers, and a hospital-integrated picture archiving and communication system (HIP-PACS). The approach used to integrate content-based retrieval and knowledge base techniques within the existing HI-PACS to make the whole database system useful in medicine.

Adult↗
PubMed1990

Maltreatment and the school-age child: major academic, socioemotional, and adaptive outcomes.

Studies of the impact of abuse or neglect on children have focused largely on maltreated infants, toddlers, or preschool children and on single subsystems of development. In the study described in this article, 139 school-age and adolescent children who had been physically abused, who had been neglected, and who had no prior history of maltreatment participated in a multimodal, multisource assessment. The authors used parent and child interviews, teacher ratings, and data from school records to comprehensively assess older maltreated children's school performance; social and emotional development in school, at home, in the community, and with peers; and adaptive behavior in areas such as motor skills, personal care skills, and community orientation. With the effects of socioeconomic status covaried out, results showed that the abused children displayed pervasive and severe academic and socioemotional problems. Neglected children differed little from children who were neither abused nor neglected on measures of socioemotional development, but they displayed severe academic delays. Both groups of maltreated children showed unexpected strengths on measures of adaptive behavior.

Adolescent↗
PubMed1995

Adjuvant chemotherapy improves survival after liver transplantation for hepatocellular carcinoma.

OBJECTIVE: The aim of this study was to evaluate the effect of postoperative adjuvant chemotherapy on the recurrence rate and survival of patients after orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: Historically, liver transplantation for HCC has yielded poor long-term survival. Multimodality therapy has been initiated in an effort to improve survival statistics. METHODS: Twenty-five patients were placed on 6 months of intravenous fluorouracil, doxorubicin, and cisplatin after OLT. Risk factors, recurrence rates, and survival rates were analyzed and compared with historic controls. RESULTS: Overall long-term survival in the protocol patients was 46% at 3 years, improved over our historic controls of 5.8% at 3 years (p = 0.0001). Overall recurrence rate was 20% (n = 4). Possible risk factors, such as tumor size, vascular invasion, multifocality, capsular invasion, and tumor differentiation, were not found to be significantly predictive of survival. Three patients with long-term, disease-free survival had tumors > 5 cm. Side effects from chemotherapy were common, but rarely severe. CONCLUSIONS: This study suggests that adjuvant chemotherapy after transplantation for HCC can provide long-term cure and may improve survival, even in patients with stage III and IV disease.

Actuarial Analysis↗
PubMed1994

An algorithm for Monte Carlo estimation of genotype probabilities on complex pedigrees.

Exact probability and likelihood computation on complex pedigrees is often infeasible, since exact methods are too computationally intensive even with today's computing technology. A statistical tool, Markov chain Monte Carlo (MCMC), is increasingly being explored as a technique for estimating probabilities of genotypic configurations on pedigrees conditional on phenotypic data. However, this conditional probability distribution on a complex pedigree is, in general, multimodal, and multimodality is one of the major difficulties in MCMC exploration of a probability surface. In this paper, a new member of the MCMC Metropolis-Hastings class of algorithms is proposed; the heated-Metropolis algorithm. The algorithm achieves passage through low probability states to other local modes of the probability distribution, and so provides much improved estimates of probabilities of interest. The example considered is the estimation of the probabilities of carrier genotype for the founders of a complex pedigree in which a very rare lethal recessive trait is segregating.

Algorithms↗
PubMed1990

Prognosis in children with rhabdomyosarcoma: a report of the intergroup rhabdomyosarcoma studies I and II. Intergroup Rhabdomyosarcoma Committee.

Prestudy patient characteristics and specific therapy of all eligible patients with rhabdomyosarcoma entered into Intergroup Rhabdomyosarcoma (RMS) Studies I (IRS-I) (1972 to 1978, n = 686) or II (IRS-II) (1978 to 1984, n = 1,002) were examined for their relationship to survival within each of the four clinical groups using univariate and multivariate analyses. The estimated survival at 5 years from the start of treatment was 56% in IRS-I and 62% in IRS-II (P = .006). The largest survival difference between studies was in patients with group III tumors (52% v 65%). The clinical group was the most important patient characteristic related to survival in both studies. Survival progressively decreased for patients from clinical group I (localized disease, completely resected) to group IV (metastatic disease at the onset). In clinical group I, the only patient characteristic consistently related to survival was histology. Patients with alveolar tumors had the poorest survival, while those with botryoid/embryonal lesions had the best survival. In clinical group II, no characteristic was consistently related to survival. In clinical group III, an orbital primary site was associated with a favorable survival. In clinical group IV, patients with genitourinary tumors had a significant survival advantage. Use of disease-free survival as an end point gave very similar results. This information, from the largest available data base on prognostic indicators in childhood RMS in the context of aggressive multimodal therapies, is being used to plan therapy in the forthcoming study (IRS-IV).

Adolescent↗
PubMed2004

Microsurgical treatment of basilar apex aneurysms: perioperative and long-term clinical outcome.

OBJECTIVE: We sought to analyze the perioperative and long-term clinical outcome data for patients with microsurgically treated basilar apex aneurysms. METHODS: We identified 98 consecutively treated basilar apex aneurysms in patients prospectively enrolled in a cerebral aneurysm database. RESULTS: Fifty patients presented with subarachnoid hemorrhage, and 19 aneurysms were giant. Eighty-four of 98 aneurysms were directly clipped. Surgical morbidity was 19.4% for the entire cohort and 8.8% for the unruptured, nongiant subgroup. The most common complication resulting in long-term morbidity was perforator injury. Sixty-seven percent of patients with clipped aneurysms were independent at discharge; this fraction increased to 79.0% at the 3-month follow-up examination. Good long-term outcomes (modified Rankin Scale score < or =2) were achieved in 56 (70%) of 80 cases. The mean Barthel Index of surviving patients was 95.8 +/- 15.0 (median = 100, n = 66). Patients with unruptured, nongiant lesions fared considerably better than patients in other cohorts. Ninety-three percent of this subgroup was independent at discharge; this fraction increased to 100% at the 3-month follow-up examination (n = 27). In univariate analyses, poor clinical grade, giant aneurysm size, major operative complications, and operations performed early in the series were associated with worse outcomes. In the multivariate analysis, unruptured giant aneurysm status was found to confer a tremendous risk for poor outcome (risk ratio, 80.0; 95% confidence interval, 8.0-800.7; P < 0.01). Surviving patients were observed for a mean clinical follow-up period of 7.4 +/- 3.7 years. The annual rate of postoperative subarachnoid hemorrhage was 0.18% for all clipped aneurysms and 0% for completely clipped lesions. CONCLUSION: In comparison to data from the existing literature regarding Guglielmi detachable coil embolization of basilar apex aneurysms, the data presented suggest that surgical clipping should be an important component of a multimodality approach to the treatment of patients with basilar apex aneurysms.

Adult↗
PubMed2006

Speckle contrast reduction in a large-core fiber delivering Q-switched pulses for fluid flow measurements.

Due to their capability for supporting high-peak powers, large-core hollow optical fibers may be used to deliver high-peak-power nanosecond pulses for the fluid flow measurement technique of particle image velocimetry [Meas. Sci. Technol. 16, 1119 (2005)]. One drawback of using such fibers for fluid flow measurements is that the output suffers from a speckled interference pattern due to the fiber's multimode nature, which can lead to a loss of spatial information and reduced data quality. Presented here is a technique to reduce the speckle contrast from these fibers when delivering nanosecond pulses. Significant smoothing of the output intensity distribution is demonstrated, giving an improved source of illumination for fluid flow measurements and other imaging techniques requiring pulsed laser illumination.

Journal Article↗
PubMed2004

Prognostic significance of micrometastasis in non-small-cell lung cancer.

Accurate staging of non-small-cell lung cancer (NSCLC) determines prognosis and facilitates decisions regarding treatment options. Unfortunately, even after an apparently complete resection in patients with stage I disease, the recurrence rates range from 25% to 50%, and overall survival is not encouraging. One possible reason for this may be that those patients with a poor outcome actually have more extensive disease, with occult locoregional and/or distant metastasis than originally identified by routine pathologic staging techniques. There is now a sizable body of literature on the detection and possible prognostic role of occult disease in lung cancer. The majority of these studies are based on immunohistochemical analysis of lymph nodes and/or bone marrow, but a handful of studies use molecular approaches. The purpose of this review is to summarize and critique the current literature on occult tumor cell spread to lymph nodes and bone marrow in patients with NSCLC. Based on this literature, we believe that the prognostic significance of bone marrow micrometastasis remains unclear. However, the majority of studies indicate that occult lymph node disease is associated with a poor outcome. Thus, our ability to detect individual tumor cells could result in more accurate staging of NSCLC in patients and would potentially lead to the development of novel therapies, as well as influence decisions regarding the use of appropriate multimodality treatment strategies, the choice of surgical technique, and extent of dissection. As data accumulate, the presence or absence of occult nodal involvement should probably be considered at the next revision of the staging system for NSCLC.

Bone Marrow↗
PubMed2000

Intraoperative radiotherapy for primary and locally recurrent soft tissue sarcoma: morbidity and long-term prognosis.

INTRODUCTION: Soft tissue sarcoma has a high risk of local recurrence. Therefore, extensive surgical resection has been combined with radiotherapy to improve long-term results. Because external beam radiation doses may be limited by adjacent radiosensitive tissue, intraoperative boost radiation has been devised to achieve a higher total radiation dose in combination with external beam radiotherapy. We report our experience with this multimodal approach for primary and recurrent soft tissue sarcoma. METHODS: Clinical and pathological data were extracted from a prospective data base including all patients with a diagnosis of soft tissue sarcoma treated at the Department of Surgery, University of Heidelberg between 1988 and 1999. Intraoperative radiotherapy dosages were 12-15 Gy for the extremities and 15-18 Gy for the trunk and the retroperitoneum. Additional external beam radiotherapy was given at 40 Gy, whenever possible. RESULTS: Between 1988 and 1999, a total of 251 patients with primary or recurrent soft tissue sarcoma of the extremities, the trunk or the retroperitoneum were treated. The mean (+/- SD) age of 136 men and 115 women was 53+/-16 years. Five of 251 patients died post-operatively, giving a mortality rate of 2.0%. Intraoperative radiotherapy (IORT) was used in 92 patients (37%). Surgical complications were more frequent in IORT patients (30 of 92; 33%) compared to non-IORT patients (36 of 159; 23% P=0.1). Infectious complications were significantly more frequent in patients receiving IORT (P=0.03). Two hundred and four patients were macroscopically tumour-free (R0, R1 resection). For these patients multivariate analysis identified grading (relative risk (RR) 3.1-6.6; P<0.001), age (over 55 years; (RR) 1.8: P<0.008) and tumour location in the retroperitoneum (RR 2.2; P<0.004) as independently associated with recurrence-free survival. The use of IORT (P<0.02) reduced the relative risk of death or recurrence by 40% (RR 0.6; P<0.02). Sex, primary vs. recurrent tumour, T classification and R-status (R0 vs. R1) were not significantly related to recurrence-free survival. CONCLUSIONS: In this prospective, non-randomized study of soft tissue sarcoma IORT was associated with a higher rate of infectious complications, but the the risk of death or recurrence was reduced by 40%.

Adolescent↗
PubMed1990

Long-term abstinence from alcohol in patients receiving aversion therapy as part of a multimodal inpatient program.

A sample of 200 patients who had been treated for alcoholism in a multimodal inpatient program that used aversion therapy as a treatment component was selected for outcome evaluation. One hundred sixty (80%) were located. A minimum of 13 months had elapsed since treatment (mean 20.5 months) collateral reports were used to verify self-reports in 36% of the cases. Abstinence status was determined for the first 12 months since treatment, the entire elapsed time since treatment (range 13 to 25 months, mean 20.5 months), and "current abstinence" (last 6 months). The abstinence rate for the first 12 months was 71.3%; for the total period since treatment, the rate was 65% (mean 20.5 months); the current abstinence rate was 78.1%. The data was also viewed from other perspectives. The findings of this study suggest that a multimodal alcoholism treatment program utilizing aversion conditioning is at least as acceptable to patients as counseling centered programs and can be expected to yield favorable abstinence rates.

Adult↗
PubMed2002

Integration of sulcal and functional information for multimodal neuronavigation.

OBJECT: The authors present the use of cortical sulci, segmented from magnetic resonance (MR) imaging, and functional data from functional (f)MR imaging and magnetoencephalography (MEG) in the image-guided surgical management of lesions adjacent to the sensorimotor cortex. METHODS: In an initial set of 11 patients, sulci near lesions were automatically segmented from MR imaging data sets, then MEG and fMR imaging examinations were performed. Relevant functional information was preoperatively interpreted and selected from MEG and fMR imaging and subsequently transferred to the navigation system for selected sulci. A neuronavigation system consisting of a surgical microscope with enhanced reality overlay display was used. Data were displayed as contours on the cut-plane images of a stereotactic workstation and as contours on the overlay screen of the head-up display within the optical path of the right eyepiece of the surgical microscope. CONCLUSIONS: This method, in which both sulcal and functional mapping are used for surgery planning and neuronavigation, provides helpful information. It is a promising procedure for the treatment of patients who harbor lesions in areas around the eloquent cortex.

Adult↗