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At least 577 records · Page 32Linked to original sources
PubMed2001

Evaluation of various evoked potential techniques for spinal cord monitoring during scoliosis surgery.

STUDY DESIGN: This prospective study compared the outcomes of different evoked potential (EP) techniques for intraoperative spinal cord monitoring. OBJECTIVES: To evaluate the reliability of different EP techniques administered during scoliosis surgery. SUMMARY OF BACKGROUND DATA: A number of different methods of intraoperative spinal cord monitoring are available. Because each has its own advantages and limitations, multimodal spinal cord monitoring has been proposed to improve monitoring reliability. MATERIALS AND METHODS: Cortical somatosensory-evoked potential (CSEP), cortical motor-evoked potential (CMEP), spinal somatosensory-evoked potential (SSEP), and spinal cord-evoked potential (SCEP) were applied simultaneously to 30 patients undergoing surgical correction for spinal deformity. The presence of the EP waveforms and their reproducibilities over separate tests were compared. In addition, the monitoring outcomes were evaluated with the clinical results. RESULTS: Of the 30 patients, CSEP waveforms were successfully recorded in 28 cases (93%), SCEP in 25 cases (83%), CMEP in 24 cases (80%), and SSEP in 21 cases (70%). Latencies of each EP technique showed no significant variability. However, amplitudes showed significant differences between different techniques. SCEP and CMEP showed clearer waveforms of greater amplitude that could be detected faster than CSEP and SSEP waveforms. SCEP and SSEP waveforms were more easily influenced by the surgical procedure. CONCLUSION: CSEP and CMEP are recommended for routine monitoring, so that both ascending and descending tracts are monitored. If adequate signals for either of these proposed monitoring methods cannot be easily obtained, SSEP can substitute for CSEP, whereas SCEP can substitute for CMEP.

Adolescent↗
PubMed1984

A registry for implantable antitachycardia devices.

Antitachycardia electrical stimulation involves significant problems of sensing the cardiac rhythm and determining whether a tachycardia exists. The simple algorithms developed for bradycardia pacing are inadequate for tachycardia pacing. Electrogram signal analysis and cardiac activation analysis with at least two leads will be required to make a device diagnosis of a tachycardia. Termination of a tachycardia reliably and consistently is difficult and has been accomplished reliably only by defibrillation. Further development of devices which are multimodal in termination capability is necessary. A registry for tachycardias and for tachycardia management is required to provide concentrated and analyzable data from a modality as yet infrequently used.

Electric Countershock↗
PubMed2000

Spatial and temporal registration of CT and SPECT images: development and validation of a technique for in vivo three-dimensional semiquantitative analysis of bone.

UNLABELLED: The combined use of postoperative 3-dimensional CT and SPECT imaging provides a means of relating anatomy and physiology for the semiquantitative in vivo analysis of bone. This study focuses on the development and validation of a technique that accomplishes this through the registration of SPECT data to a 3-dimensional volume of interest (VOI) interactively defined on CT images. METHODS: Five human cadaver heads served as anthropomorphic models for all experiments. Four cranial defects were created in each specimen with inlay and onlay split-skull bone grafts reconstructed to skull and malar recipient sites. To acquire all images, each specimen was landmarked with 1.6-mm ball bearings and CT scanned. Bone surfaces were coated with 99mTc-doped paint. The locations of the ball bearings were marked with paint doped with 111In. Separate SPECT scans were acquired using the energy windows of 99mTc and 111In. RESULTS: Serial SPECT images aligned with an average root-mean-square (RMS) error of 3.8 mm (i.e., <1 pixel). CT-to-SPECT volume matching aligned with an RMS error of 7.8 mm. Total counts in CT-defined VOIs applied to SPECT data showed a strong linear correlation (r2 = 0.86) with true counts obtained from a dose calibrator. CONCLUSION: The capability of this multimodality registration technique to anatomically localize and quantify radiotracer uptake is sufficiently accurate to warrant further assessment in an in vivo trial.

Bone Transplantation↗
PubMed1985

The role of implantable pacemakers in the therapy of tachycardias.

Antitachycardia electrical stimulation involves significant problems of sensing the cardiac rhythm and determining whether a tachycardia exists. The simple algorithms developed for bradycardia pacing are inadequate for tachycardia pacing. Electrogram signal analysis and cardiac activation analysis with at least two leads will be required to make a device diagnosis of a tachycardia. Termination of a tachycardia reliably and consistently is difficult and has only been accomplished uniformly by defibrillation. Further development of devices which are multimodal in termination capability is necessary. A registry for tachycardias and for tachycardia management is required to provide concentrated and analyzable data from a modality as yet infrequently used.

Anti-Arrhythmia Agents↗
PubMed1998

[Morbidity and tumor control in limb-saving resection with intraoperative radiotherapy in a multimodality therapy concept in soft tissue sarcoma].

This study evaluates limb-saving surgery (LSS) combined with intraoperative radiotherapy (IORT) and external beam radiotherapy (EBRT) for extremity sarcoma. Prospectively gathered data was analyzed for 50 patients. Advanced stages (UICC IIB-IIIB) predominated (80%) and 50% of the tumors were recurrent. Early local morbidity amounted to 32%, including wound infection (6), skin necrosis (3), hematoma (3) and others (4). Late morbidity of 10% consisted of a fracture, a fibrosis, two chronic lymphedemas and a neuropathy. One patient died (pulmonary embolism). Local control was obtained in 91% with an overall 3-year survival rate of 81% in cases treated with curative intent (follow-up 29 months). No survival benefit was found for patients with microscopically clear margins; however, local failure occurred less frequently (p = 0.02). Our results support the use of LSS with IORT and EBRT for extremity sarcoma and emphasize the importance of the surgical margin.

Adult↗
PubMedDate not supplied

Multimodal neuroimaging studies and neurodevelopment and neurodegeneration hypotheses of schizophrenia.

The interpretation of the huge number of results in schizophrenia research using neuroimaging is uncertain. However, the simultaneous use of complimentary data obtained with these techniques may yield more relevant information in this regard. In this paper we present a series of studies performed by our group in two schizophrenic samples with the use of structural (magnetic resonance imaging, MRI), functional [glucose positron emission tomography (PET) and N-acetyl-aspartate (NAA) magnetic resonance spectrocopy] and neurophysiological techniques (the P300 event-related potential). Transversal and longitudinal measurements were performed.The integrated vision of the results so obtained allows us to propose the hypothesis of a neurodevelopmentally determined state of prefrontal disinihibition, in which the degree of atrophy would directly relate to the metabolic rate. This state would already be present in the first stages of illness and could have neurotoxic consequences in the long term. This would explain the findings of an association between sulcal cerebrospinal fluid (CSF) and illness duration and decreased NAA levels in chronic but not in recent-onset cases. The prefrotnal disinhibition would overstimulate the limbic system and the hippocampus would become overactivated, the metabolic rate at this level being inversely related to P300 amplitude. Clozapine showed a more selective and intense action on that hyperactive metabolic tone than haloperidol.

Journal Article↗
PubMed2000

Analysis of pointing errors reveals properties of data representations and coordinate transformations within the central nervous system.

The execution of a simple pointing task invokes a chain of processing that includes visual acquisition of the target, coordination of multimodal proprioceptive signals, and ultimately the generation of a motor command that will drive the finger to the desired target location. These processes in the sensorimotor chain can be described in terms of internal representations of the target or limb positions and coordinate transformations between different internal reference frames. In this article we first describe how different types of error analysis can be used to identify properties of the internal representations and coordinate transformations within the central nervous system. We then describe a series of experiments in which subjects pointed to remembered 3D visual targets under two lighting conditions (dim light and total darkness) and after two different memory delays (0.5 and 5.0 s) and report results in terms of variable error, constant error, and local distortion. Finally, we present a set of simulations to help explain the patterns of errors produced in this pointing task. These analyses and experiments provide insight into the structure of the underlying sensorimotor processes employed by the central nervous system.

Central Nervous System↗
PubMed2006

Is en-bloc resection of locally recurrent rectal carcinoma involving the urinary tract indicated?

BACKGROUND: This study investigated morbidity, mortality, and long-term survival after multimodality management of locally recurrent rectal carcinoma involving the urinary tract. METHODS: A total of 82 patients (63 males) were identified during 1987 to 2000. Data sources were a prospectively collected database of intraoperative radiotherapy, institutional tumor registry, and chart review. The median follow-up was 3.3 years and lasted until death or for at least 2 years on all patients. RESULTS: A total of 20 (24%) of 82 patients had resection of urogenital tract structures without reconstruction. Sixty-two patients (76%) underwent reconstruction with ileal conduit (43%), ureteroneocystostomy (15%), or miscellaneous (18%). The mean number of fixation sites was 2.8 (SD, 1.5), and the mean number of organs at least partially resected was 2.6 (SD, 1.3). Eighty percent of patients underwent intraoperative radiotherapy among adjuvant treatments. Postoperative mortality was 2% (2 of 82), and morbidity was 39% (32 of 82), most frequently consisting of neuropathy and urinary leak (6% each). The overall 1-, 3-, and 5-year survival rates were 82%, 45%, and 19%, respectively. The median survival was 2.6 years. The number of sites involved was the only survival predictor at multivariate analysis (P < .001). CONCLUSIONS: A multimodality approach for locally recurrent rectal carcinoma involving the urinary tract carries acceptable morbidity, mortality, and potential for long-term survival. The number of fixation sites correlates with a poorer prognosis.

Aged↗
PubMed2003

[Remission rate of mediastinal lymph nodes after multimodal therapy of lung cancer--is it a prognostic factor?].

OBJECTIVE: General acceptance in the oncologic community has been gained for combined modality treatment of non-small cell lung (NSCLC) cancer in locally advanced stage IIIA and IIIB disease. However, no optimal regimen has been established. This study (chemotherapy and radiochemotherapy followed by operation) assesses feasibility, response, resectability, and survival in patients with stage IIIA and IIIB lung cancer. Currently, only little data is available about the prognostic significance of tumor clearance of mediastinal nodes. Thus, an important aim of our study was to evaluate the prognostic significance of the extent of tumor reduction in mediastinal nodes by a neoadjuvant multimodality protocol. PATIENTS: In a phase II protocol, 26 patients underwent neoadjuvant radiochemotherapy. Subsequently, a radical lymphadenectomy was performed during surgery. The extent of tumor regression was determined according to the methodology initially described by Salzer-Kuntschik for osteosarcoma: Grade I: no vital tumor cells, grade II: some tumor cells, grade III: less than 10 % vital tumor cells, grade IV: 10-50 % vital tumor cells, grade V: more than 50 % vital tumor cells, grade VI: no effect of chemotherapy. RESULTS: Complete pathologic response was seen in 30.7 % of primary tumors, in 38.5 % of mediastinal lymph nodes, and in 23 % of corresponding specimens simultaneously. Median survival was 34.7 months for those patients with grade I, 12.6 months with grade II, and 8.9 months for patients showing a grade III/IV regression in mediastinal nodes. Response rate to neoadjuvant chemotherapy in mediastinal nodes proved to be the only statistically significant parameter for long-term survival: In cases with no vital tumor cells in the operation specimen, median survival was 34.7 months in comparison to those with vital cells showing a median survival of only 11.4 months (P = 0.01). CONCLUSION: Patients with locally advanced NSCLCs can enjoy long-term survival after multimodal therapy. However, the complications related to therapy are considerably. Especially, clearance of tumor cells from mediastinal lymph nodes is an important independent prognostic factor.

Adult↗
PubMed1984

Efficacy of a real-time digital disk in the digital lightbox.

This paper describes a high-speed digital lightbox. The current status of film in the medical imaging department sets the stage for this next generation of image display/management systems. Digital imaging devices are proliferating because of their diagnostic speed and accuracy, and their ease of use. However, the resultant images are usually prepared by a technician, transmitted to film, then mounted on a lightbox to be eventually reviewed by the physician. Until recently, the shortcomings of a film display system could be overlooked in favor of its data-acquisition and archiving advantages. With recent developments in real-time disks and high-resolution display systems, it is now possible to improve upon the physician's display with a digital lightbox. A unique Multimodality Acquisition and Review System (MARS) is described that will support this new digital lightbox with performance features that meet or exceed the characteristic use of film in today's medical imaging departments.

Data Display↗
PubMed1996

Multimodality Therapy for Esophageal Cancer.

Adjuvant and neoadjuvant therapeutic principles have in recent years received increasing attention in the management of patients with esophageal cancer. A series of randomized prospective trials has convincingly demonstrated that adjuvant postoperative radiation or chemotherapy does not result in a survival advantage after a complete tumor resection. The available data on the role of neoadjuvant preoperative therapy in patients with adenocarcinoma or squamous cell carcinoma of the esophagus are not yet conclusive. While neoadjuvant therapy may undoubtedly reduce the tumor mass in a substantial portion of patients, a series of randomized controlled trials has shown that compared with primary resection, a multimodal approach does not result in a survival benefit in patients with locoregional, i.e., potentially resectable, tumors. In contrast, in patients with locally advanced tumors, i.e., tumors in which a complete tumor removal with primary surgery appears unlikely, neoadjuvant therapy allows a marked downstaging of the primary tumor and thus significantly increases the chance for complete tumor removal on subsequent surgery. However, only patients with objective clinical or histopathological response to preoperative therapy appear to benefit from this approach. Compared with preoperative chemotherapy alone, combined radiochemotherapy increases the rate of response but may also increase postoperative morbidity and mortality. Neoadjuvant therapy should therefore currently be performed only in experienced centers within the context of clinical trials. The identification of factors which would facilitate prediction of the response to neoadjuvant therapy is currently the focus of several studies. Furthermore, more effective and less toxic preoperative therapy regimens are required to increase the response rates and combat systemic recurrences.

Journal Article↗
PubMed2002

[Local recurrence and survival rate after rectal cancer operations and multimodal therapy].

INTRODUCTION: In the guidelines of the German specialist medical societies, postoperative chemoradiotherapy is recommended for rectal carcinomas in stages II and III. In the meantime, there are important study findings favoring preoperative radiotherapy as against postoperative irradiation. In the present unicentric study, the clinical results after preoperative irradiation and postoperative chemotherapy are to be determined. In period I, sandwich radiation without total mesorectal excision was applied. In period II, the treatment was developed further with exclusive preoperative radiation and total mesorectal excision. Since from 1994 the therapy regimen has changed with the introduction of total mesorectal excision and improved radiotherapy, the present study was carried out to check whether this has led to better results of therapy. PATIENTS AND METHODS: Over a period of 7 years, data from 607 patients with rectal carcinoma were recorded and stored in an Excel file. The carcinomas were grouped into lower, middle and upper segment levels and classified endosconographically. Multimodal treatment was administered in stage uT3. In period I, sandwich radiation was carried out with 24 Gy preoperatively and 24 Gy postoperatively, followed by adjuvant chemotherapy. Total mesorectal excision was not performed. In period II, 50.4 Gy were applied preoperatively, followed by adjuvant chemotherapy. The operation comprised total mesorectal excision of the lower two thirds of the rectum. Calcium folinate and 5-fluoroucil were administered in six chemotherapy cycles. Primarily inoperable patients received preoperative irradiation with up to 50.4 Gy in both periods to attain down-staging. The following surgical procedures were applied: abdominal perineal extirpations, deep anterior resections, coloanal anastomoses, colon pouch anal anastomoses and transanal microsurgical resections. RESULTS: In 469 curatively operated patients, including primarily inoperable patients after down-staging radiotherapy, the rates of local recurrence were 5.8% with a mean follow-up observation of 4.29 years, and the carcinoma-specific 4-year actuarial survival was 84%. The rate of recurrence was highest in the lowest segment level of the rectum (7.6 as compared to 2.4%, P = 0.042). The rates of local recurrence were 7.4% in period I and 4.3% in period II (P = 0.44). The carcinoma-specific 4-year actuarial survivals were 81% in period I and 87% in period II (P = 0.202). Investigation of the subgroups of irradiated patients showed complete freedom from recurrence after a mean follow-up observation time of 3.58 years for patients in stage uT3 with total mesorectal excision, preoperative radiotherapy and postoperative chemotherapy (n = 51). The difference from patients without postoperative chemotherapy was significant (P = 0.018). After radiotherapy, the complication observed was a raised rate of sacral cavity infections after total resection of the rectum (p = 0.039). CONCLUSION: Total mesorectal excision, preoperative radiotherapy and postoperative chemotherapy can effectively influence the rate of local recurrences after rectal carcinoma operations (0-4.3% after a mean period of follow-up observation of 3.58 years). No appraisal can be made with regard to the benefit resulting from the individual measures.

Actuarial Analysis↗
PubMed2000

Stepwise multimodal approach in the treatment of Kasabach-Merritt syndrome.

BACKGROUND: The purpose of the present study was to evalutate the various treatment modalities for Kasabach-Merritt syndrome (KMS) and to identify the most reliable treatment modalities. METHODS: A retrospective analysis was performed on 37 KMS patients who were admitted to Seoul National University Hospital between January 1979 and June 1999. Age, sex, locations of the hemangiomas, clinical symptoms and hematologic data were analyzed by multivariate logistical regression analysis to determine the response to various treatment modalities. RESULTS: Twenty-four of 37 patients (20 boys and 17 girls) were diagnosed during infancy. The locations of hemangioma were superficial skin in 31 patients, combined skin and visceral organs in four patients and visceral organs only in two patients. Tumor size was more than 5 cm in diameter in all cases, except for one. The treatment principle of KMS in our center involves a stepwise multimodal approach. Of the 37 cases, surgical resection was performed in two. Steroids were tried initially in 35 patients over a 1 week period, with an initial response rate of 11.4% (4/35). Combined steroid/radiation treatment was given in 28 cases, with a response rate of 75.0% (21/28). Four of five patients with additional interferon (IFN)-alpha therapy improved. No significant correlations were found between the prognostic factors, such as age, sex, size and locations of the hemangioma, hematologic data and the treatment modalities. CONCLUSIONS: Based on the experiences in a single center over a period of 20 years, we recommend a stepwise multimodal approach for the treatment of KMS; for example, steroid, radiation therapy and IFN-alpha in this order. However, surgical treatment is helpful if total resection is possible.

Abnormalities, Multiple↗
PubMed2002

SMART-PET: multimodality white matter imaging and display without loss of quantitative information.

PURPOSE: To improve analysis of cerebral white matter (WM) in fluoro-deoxy-glucose positron emission tomography (PET) images. MATERIALS AND METHODS: A multimodality analysis technique (segmented MRI and registered Talairach-transformed PET [SMART-PET]) was used for quantitative assessment of WM metabolism. Data processing included Talairach transformation of three-dimensional magnetic resonance imaging (MRI) and subsequent automated segmentation and coregistration to normalized PET images. Color model transformations were used for combined display: the hue saturation value color model was regarded as a three-dimensional data matrix, integrating quantitative voxel data of both modalities. The technique was applied in normal subjects and in patients suffering from different WM diseases. Regional analysis was performed to classify metabolic impairment on a five-point scale. RESULTS: Using SMART-PET, a considerable gain in image contrast for WM was achieved in all cases. In the normal subjects, WM metabolism was shown to be homogeneously unimpaired. Sum scores of regional analysis revealed metabolic WM changes in all patients. Extent of WM hypometabolism exceeded the extent of the lesions as delineated by MRI signal changes. CONCLUSION: The potential of the method for further elucidation of the role of WM diseases in brain dysfunction in patients is discussed.

Brain↗
PubMed2004

A hierarchical parametric algorithm for deformable multimodal image registration.

Image fusion is of utmost importance for many applications in image analysis. Particularly in medical imaging, images of different modalities are necessary because they provide complementary information that must be merged for an optimal use. The fusion of these images, which can be achieved through a registration process, makes it possible to superimpose all available information on the same frame. In many cases, a rigid transformation is sufficient to align correctly the images. However, there are cases where a non-rigid transformation is needed: geometrical distortions present in one image, non-rigid motion, etc. The purpose of this paper is to propose a generic method to account for these deformations in case of multimodal images. We have applied the algorithm in the particular context of 3D medical images and present results on simulated and real data.

Algorithms↗
PubMed1997

Analysis of phosphorescence in heterogeneous systems using distributions of quencher concentration.

A continuous distribution approach, instead of the traditional mono- and multiexponential analysis, for determining quencher concentration in a heterogeneous system has been developed. A mathematical model of phosphorescence decay inside a volume with homogeneous concentration of phosphor and heterogeneous concentration of quencher was formulated to obtain pulse-response fitting functions for four different distributions of quencher concentration: rectangular, normal (Gaussian), gamma, and multimodal. The analysis was applied to parameter estimates of a heterogeneous distribution of oxygen tension (PO2) within a volume. Simulated phosphorescence decay data were randomly generated for different distributions and heterogeneity of PO2 inside the excitation/emission volume, consisting of 200 domains, and then fit with equations developed for the four models. Analysis using a monoexponential fit yielded a systematic error (underestimate) in mean PO2 that increased with the degree of heterogeneity. The fitting procedures based on the continuous distribution approach returned more accurate values for parameters of the generated PO2 distribution than did the monoexponential fit. The parameters of the fit (M = mean; sigma = standard deviation) were investigated as a function of signal-to-noise ratio (SNR = maximum signal amplitude/peak-to-peak noise). The best-fit parameter values were stable when SNR > or = 20. All four fitting models returned accurate values of M and sigma for different PO2 distributions. The ability of our procedures to resolve two different heterogeneous compartments was also demonstrated using a bimodal fitting model. An approximate scheme was formulated to allow calculation of the first moments of a spatial distribution of quencher without specifying the distribution. In addition, a procedure for the recovery of a histogram, representing the quencher concentration distribution, was developed and successfully tested.

Light↗
PubMed1994

Pairwise comparisons of mitochondrial DNA sequences in subdivided populations and implications for early human evolution.

We consider the effect on the distribution of pairwise differences between mitochondrial DNA sequences of the incorporation into the underlying population genetics model of two particular effects that seem realistic for human populations. The first is that the population size was roughly constant before growing to its current level. The second is that the population is geographically subdivided rather than panmictic. In each case these features tend to encourage multimodal distributions of pairwise differences, in contrast to existing, unimodal datasets. We argue that population genetics models currently used to analyze such data may thus fail to reflect important features of human mitochondrial DNA evolution. These may include selection on the mitochondrial genome, more realistic mutation mechanisms, or special population or migration dynamics. Particularly in view of the variability inherent in the single available human mitochondrial genealogy, it is argued that until these effects are better understood, inferences from such data should be rather cautious.

Animals↗
PubMed2006

Planned post-chemoradiation neck dissection: significance of radiation dose.

OBJECTIVE: The increasing prominence of multimodality therapy for patients with advanced head and neck cancer reflects its high survival and functional preservation rates. We report the pathologic data on patients undergoing neck dissection (ND) after induction chemotherapy followed by concomitant chemoradiotherapy (IC-CRT) in three similar protocols utilizing decreasing doses of radiation therapy. MATERIALS AND METHODS: The databases of 221 patients who underwent IC-CRT between 1999 and 2002 were reviewed. Based on posttreatment residual or pretreatment N2a or greater neck disease, 73 patients without pretreatment neck surgery were eligible for analysis (1 N1, 3 N2a, 26 N2b, 20 N2c, 23 N3). Three additional subgroups were also analyzed with respect to outcome: Undissected patients with less than N2 disease, patients who had neck surgery prior to IC-CRT, and patients with N2a or greater neck disease who did not have post-IC-CRT ND. STUDY DESIGN: Retrospective analysis. RESULTS: Sixty-seven patients underwent unilateral or bilateral selective neck dissection. Six patients had modified or radical ND. There were no wound healing complications. Pathologic analysis revealed viable cancer in 15 of 73 patients (20.5%): 1 had N1, 3 had N2b, 4 had N2c, and 7 had N3 neck disease. The incidence of viable cancer in the neck dissection specimen increased as radiation dose decreased. Complete response induction chemotherapy predicted negative pathology (P = .003). In the subgroup analysis, patients who had pretreatment surgery had a lower risk of dying from the primary cancer CONCLUSIONS: 1) The incidence of positive pathology after IC-CRT increases as radiation dose decreases. 2) Selective neck dissection after CRT has been demonstrated to be feasible and safe; the complication rate of ND after IC-CRT is acceptably low. 3) There is viable posttreatment cancer in 20.5% of patients, indicating necessity of ND in these patients.

Adult↗