Search results for "Image processing"
showing 10 items of 3285 documents
Virtual reality system for planning minimally invasive neurosurgery
2008
Object The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Methods Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. Results After a short period of acclimatization, the system proved easy to operate and is currently used routinely for pre…
Perfusion MRI in normal and abnormal pituitary gland. A preliminary study.
1997
Perfusion MRI (magnetic resonance imaging) of the pituitary gland was performed in 20 healthy volunteers and 63 patients with various lesions involving the pituitary gland. All patients underwent sequential contrast-enhanced MRI using spoiled gradient recalled sequences with high temporal resolution (7 seconds). Four pituitary areas (pituitary stalk, posterior lobe, postero-superior, and antero-inferior adenohypophysis) were tested with a selected region of interest. Maximal contrast percentual variation was calculated. The timing of enhancement in normal patients matched perfectly with normal pituitary vascularization. Abnormal timing in pathological condition was investigated.
3D microvascular architecture of pre-cancerous lesions and invasive carcinomas of the colon.
2001
Despite the significance of tumour neoangiogenesis and the extensive knowledge on the molecular basis of blood vessel formation currently no quantitative data exist on the 3D microvascular architecture in human primary tumours and their precursor lesions. This prompted us to examine the 3D vascular network of normal colon mucosa, adenomas and invasive carcinomas by means of quantitative microvascular corrosion casting. Fresh hemicolectomy specimens from 20 patients undergoing cancer or polyposis coli surgery were used for corrosion casting, factor VIII and VEGF immunostaining. In addition, immunostaining was done on colorectal tissue from 33 patients with metastatic and non-metastatic carci…
Thalamic infarctions cause side-specific suppression of vestibular cortex activations.
2005
H2O15-PET was performed during caloric vestibular stimulation of the right and left external ears in eight right-handed patients with acute unilateral infarctions or haemorrhages of the posterolateral thalamus (four right, four left). The posterolateral thalamus is the relay station for ipsi- and contralateral ascending vestibular input to the multiple multisensory vestibular cortex areas. The aim of this study was to evaluate the differential effects of unilateral vestibular thalamic lesions on thalamo-cortical projections, right hemispheric dominance and reciprocal inhibitory visual-vestibular interaction, as well as perceptual and ocular motor consequences during caloric irrigation. The …
Interindividual synchronization of brain activity during live verbal communication
2013
Verbal social interaction plays an important role both in the etiology and treatment of psychiatric disorders. However, the neural basis of social interaction has primarily been studied in the individual brain, neglecting the inter-individual perspective. Here, we show inter-individual neuronal coupling of brain activity during live verbal interaction, by investigating 11 pairs of good female friends who were instructed to speak about autobiographical life events during simultaneous fMRI acquisition. The analysis revealed that the time course of neural activity in areas associated with speech production was coupled with the time course of neural activity in the interlocutor's auditory corte…
Transient and sustained BOLD signal time courses affect the detection of emotion-related brain activation in fMRI.
2014
A tremendous amount of effort has been dedicated to unravel the functional neuroanatomy of the processing and regulation of emotion, resulting in a well-described picture of limbic, para-limbic and prefrontal regions involved. Studies applying functional magnetic resonance imaging (fMRI) often use the block-wise presentation of stimuli with affective content, and conventionally model brain activation as a function of stimulus or task duration. However, there is increasing evidence that regional brain responses may not always translate to task duration and rather show stimulus onset-related transient time courses. We assume that brain regions showing transient responses cannot be detected in…
Volume stability of hydroxyapatite and β-tricalcium phosphate biphasic bone graft material in maxillary sinus floor elevation: a radiographic study u…
2015
Objectives The purpose of this study was to confirm volume stability of biphasic calcium phosphate (BCP) through the changes of grafted volume over the time by 3D CT analyzing software program. Patients and Methods Fifteen patients, 16 sinuses who were scheduled a staged implantation through sinus floor elevation (SFE)–lateral window technique from 2009 to 2011 were included in the study. Of the 15 patients, eight were male and seven were female (mean age 50.1). For sinus floor augmentation, BCP with local blood was packed loosely into the maxillary sinus and the grafted site was covered with a collagen membrane. For the evaluation of volume change, 3D CBCT scans were taken five times at pr…
Facilitating cartilage volume measurement using MRI.
2010
To compare quantitative cartilage volume measurement (CVM) using different slice thicknesses.Ten knees were scanned with a 1.5T MRI (Sonata, Siemens, Erlangen, Germany) using a 3D gradient echo sequence (FLASH, fast low-angle shot). Cartilage volume of the medial and lateral tibial plateau was measured by two independent readers in 1.5mm, 3.0mm and 5.0mm slices using the Argus software application. Accuracy and time effectiveness served as control parameters.Determining cartilage volume, time for calculation diminished for the lateral tibial plateau from 384.6+/-127.7s and 379.1+/-117.6s to 214.9+/-109.9s and 213.9+/-102.2s to 122.1+/-60.1s and 126.8+/-56.2s and for the medial tibial platea…
Magnetic resonance chondro-crassometry (MR CCM): a method for accurate determination of articular cartilage thickness?
1996
A method for the assessment of articular cartilage thickness based on MRI is presented and its accuracy and reproducibility tested. Six specimens of human patellae were imaged, using a fat-suppressed FLASH 3D sequence, and sectioned with a high-precision band saw. The regional distribution of articular cartilage thickness was determined from the MR images and from the anatomical sections (intervals of 0.5 mm). With image analysis 50-90% of the image points were found to lie within exactly the same thickness interval in corresponding patterns, and less than 17% deviated more than 0.5 mm. More than 85% of all pixels were reproducible with MRI after new positioning of the joint. No influence o…
Repeatability of patellar cartilage thickness patterns in the living, using a fat-suppressed magnetic resonance imaging sequence with short acquisiti…
1998
A fast, reproducible, and noninvasive method is required for quantifying cartilage thickness clinically and for studying the deformation of articular cartilage during and after mechanical loading in vivo. The objective of the current investigation was to test the repeatability of regional distribution patterns of patellar cartilage thickness in the living on the basis of a fat-suppressed magnetic resonance imaging sequence with a short acquisition time and three-dimensional digital data processing. The knees of eight healthy volunteers were transversally imaged with a fat-suppressed FLASH-3D (fast low angle shot) sequence (acquisition time: 4 minutes and 10 seconds). In each case, the joint…