Biomedical subjects

Michael Forsting

Publications and source records attributed to Michael Forsting.

At least 19 recordsLinked to original sources

PubMed2006

Visualization of the visual cortex in minipigs using fMRI.

Minipigs are widely used to examine physiologic mechanisms under experimental settings. The purpose of our study was to localize the visual cortex of minipigs using visual stimulation in functional magnetic resonance imaging (fMRI). Five male Göttinger minipigs were studied with fMRI during visual stimulation with series of light impulses conducted into the MR cabin via fibre optical wave guides (EPI sequences, block design, 1.5 T clinical routine MR-scanner). Statistics were performed using SPM'99. All minipigs showed activation of the visual cortex due to light stimulation. The activation could be superimposed to T2-weighted structural images with good spatial resolution revealing the exact location of the visual cortex. We were able to localize the visual cortex in minipigs for the first time utilizing fMRI on a routine scanner. However, this may be useful for precise positioning of electrodes or implants or be used as a further uncomplicated non-invasive method in physiologic experiments.

Animals↗

PubMed2006

Whole-body MR vascular screening detects unsuspected concomitant vascular disease in coronary heart disease patients.

Coronary heart disease (CHD) patients often show atherosclerotic vascular disease in other vascular territories. We evaluated how often whole-body MR imaging detects concomitant arterial pathologies in CHD patients, and how often these pathologies were not known to the patients previously. Of 4,814 participants in the population-based Heinz Nixdorf Recall Study, 327 reported CHD (i.e., previous coronary bypass surgery, angioplasty); of those, 160 patients (mean age 66.4 years) were examined using MR of the brain, the heart (excluding the coronary arteries), and whole-body MR angiography. The prevalence of each vascular pathology was assessed, correlated to the others and compared to patients' histories. Of the 160 CHD patients, 16 (10%) showed MR signs of stroke, and 77 (48.1%) had a stenosis >50% in at least one extracerebral peripheral artery (other than the coronaries), including 28 (17.5%) with relevant renal artery stenoses, and 20 (12.5%) with relevant extracerebral internal carotid artery stenoses. False negative histories were reported in 12 of 81 cases with myocardial infarctions, and in 11 of 16 cases with cerebrovascular infarctions. This whole-body atherosclerosis MR screening program allows previously unknown concomitant vascular disease to be detected in coronary heart disease patients. Its prospective value should be assessed in further studies.

Aged↗

PubMed2006

Transcranial sonography of the third ventricle and cognitive dysfunction in HIV patients.

BACKGROUND: Although the incidence and prevalence of dementia associated with human immunodeficiency virus (HIV) infection has decreased since the introduction of highly active antiretroviral therapy, cognitive dysfunction remains one of the most prevalent factors severely affecting quality of life in patients with HIV. Previous magnetic resonance imaging (MRI) studies showed a correlation between brain atrophy, enlargement of the ventricles and cognitive impairment in HIV patients. OBJECTIVE: To investigate the usefulness of transcranial sonographic (TCS) measurement of the third ventricle in detection of brain atrophy in HIV patients and the correlation with neuropsychological deficits. METHODS: We examined 47 HIV patients and 40 healthy age-matched controls with TCS, neuroimaging (cranial MRI or computed tomography) and a neuropsychological test battery. RESULTS: The third ventricle was significantly larger in patients than in healthy controls and correlated significantly with duration of HIV, Center of Disease Control (CDC) stage, CD4 lymphocytes and distinct cognitive and motor deficits. CONCLUSION: TCS cannot replace neuroimaging but is a valuable method in the detection of brain atrophy and follow-up of HIV patients at risk or with a recent diagnosis of HIV encephalopathy.

Adult↗

PubMed2006

Balloon-assisted coil embolization of a posterior cerebral artery aneurysm via a persistent primitive trigeminal artery: technical note.

INTRODUCTION: We present a patient with an acutely ruptured, wide-necked aneurysm of the left posterior cerebral artery (PCA) treated with Guglielmi detachable coils using the remodeling technique. METHODS: Since the left vertebral artery was compressed due to a tumor in the cerebellopontine angle and the right vertebral artery was hypoplastic, we used a carotid artery approach via a persistent primitive trigeminal artery (PPTA) to selectively catheterize the aneurysm. RESULTS: The aneurysm was occluded completely. CONCLUSION: To our knowledge this is the first case of a wide-necked PCA aneurysm treated via a PPTA and using the remodeling technique. In patients with hypoplastic vertebral arteries and a PPTA, this approach may represent an alternative for selective embolization of posterior circulation aneurysms not amenable to the conventional approach.

Adult↗

PubMed2006

Horizontal stent placement plus coiling in a broad-based basilar-tip aneurysm: an alternative to the Y-stent technique.

INTRODUCTION: Basilar tip aneurysms are the most frequent type of aneurysm in the posterior circulation. Specifically, if wide-necked, they remain a significant therapeutic challenge. On the endovascular side, stents may help to overcome many of these technical challenges. However, if both P1 segments encroach into the aneurysm neck, sometimes stent placement from the middle of the basilar artery to one P1 segment is not enough. Therefore, some groups recommend the use of the so-called Y-stent technique, with one stent passing through the interstices of another stent in a Y-configuration thus remodelling the basilar tip. METHODS: We describe a patient with a broad-based basilar tip aneurysm and a single, very tortuous vertebral artery which did not allow the use of the vertebrobasilar system as the straight route to the aneurysm. Because of the well-known high surgical risk we decided to navigate the stent through the internal carotid artery and via the posterior communicating artery into the contralateral P1 segment and placed the stent at right angles to the aneurysm from one P1 segment to the contralateral one. RESULTS: The outcome in the patients was excellent without any ischemic lesions. CONCLUSION: Horizontal stent placement in wide-necked basilar tip aneurysms may be a therapeutic alternative if the regular route via the vertebral arteries is not feasible.

Blood Vessel Prosthesis Implantation↗

PubMed2006

Extinction of conditioned eyeblink responses in patients with cerebellar disorders.

Extinction of conditioned eyeblink responses (CRs) was analyzed in sixteen patients with pure cortical cerebellar degeneration, 14 patients with lesions within the territory of the superior cerebellar artery (SCA), 13 patients with infarctions within the territory of the posterior inferior cerebellar artery (PICA) and 45 age-matched controls. Three-dimensional (3D) magnetic resonance (MRI) data sets were acquired in patients with focal lesions to identify affected cerebellar lobules and possible involvement of nuclei. Eyeblink conditioning was performed using a standard delay protocol. At the end of the experiment 10 CS-alone trials were presented as extinction trials. Controls showed significant effects of extinction that is a significant decline comparing CR-incidences in the extinction trials and the last block of 10 trials of the paired trials. In the group of all cerebellar patients, however, no significant effects of extinction were observed. In patients with unilateral lesions effects of extinction were present on the unaffected, but not on the affected side. Deficits of extinction were observed in PICA and SCA patients both with and without involvement of cerebellar nuclei. Extending previous reports in cerebellar patients the present findings show that the ipsilateral cerebellar hemisphere contributes to extinction of conditioned eyeblink responses in humans. It cannot be ruled out, however, that impaired acquisition affected the extinction results.

Adult↗

PubMed2006

Structural brain abnormalities in the frontostriatal system and cerebellum in pedophilia.

Even though previous neuropsychological studies and clinical case reports have suggested an association between pedophilia and frontocortical dysfunction, our knowledge about the neurobiological mechanisms underlying pedophilia is still fragmentary. Specifically, the brain morphology of such disorders has not yet been investigated using MR imaging techniques. Whole brain structural T1-weighted MR images from 18 pedophile patients (9 attracted to males, 9 attracted to females) and 24 healthy age-matched control subjects (12 hetero- and 12 homosexual) from a comparable socioeconomic stratum were processed by using optimized automated voxel-based morphometry within multiple linear regression analyses. Compared to the homosexual and heterosexual control subjects, pedophiles showed decreased gray matter volume in the ventral striatum (also extending into the nucl. accumbens), the orbitofrontal cortex and the cerebellum. These observations further indicate an association between frontostriatal morphometric abnormalities and pedophilia. In this respect these findings may support the hypothesis that there is a shared etiopathological mechanism in all obsessive-compulsive spectrum disorders.

Adult↗

PubMed2006

Recommendations for the management of intracranial haemorrhage - part I: spontaneous intracerebral haemorrhage. The European Stroke Initiative Writing Committee and the Writing Committee for the EUSI Executive Committee.

This article represents the recommendations for the management of spontaneous intracerebral haemorrhage of the European Stroke Initiative (EUSI). These recommendations are endorsed by the 3 European societies which are represented in the EUSI: the European Stroke Council, the European Neurological Society and the European Federation of Neurological Societies.

Emergency Medical Services↗

PubMed2006

MR imaging of the uterus and cervix in healthy women: determination of normal values.

The purpose of this study was to establish normal values for the volume of the uterus and cervix in MRI based on age and the menstrual cycle phase. We performed MRI of the pelvis in 100 healthy women. For the uterus, they were further divided into two groups: one with myomas and/or adenomyosis and one without either. The volume of the uterus and cervix and thickness of the uterine wall layers were analysed by age and the menstrual cycle phase. The mean volume of the uterus in both groups and the cervix significantly increased with age to reach its peak at 41-50 years, and then dropped. Likewise, the thickness of the endometrium and the junctional zone, but not the myometrium, significantly increased until 41-50 years, and then decreased. When we compared the volume of the uterus and cervix and the thickness of the uterine wall layers between the two phases of the menstrual cycle, we found no significant differences. The volume of the uterus and cervix and the thickness of the endometrium and junctional zone differ significantly with age, but not between the two phases of the menstrual cycle. Knowledge of MRI-related normal values can be expected to aid the early identification of uterine pathologies.

Adult↗

PubMed2006

There are differences in cerebral activation between females in distinct menstrual phases during viewing of erotic stimuli: A fMRI study.

There is evidence that men experience more sexual arousal than women but also that women in mid-luteal phase experience more sexual arousal than women outside this phase. Recently, a few functional brain imaging studies have tackled the issue of gender differences as pertaining to reactions to erotica. The question of whether or not gender differences in reactions to erotica are maintained with women in different phases has not yet been answered from a functional brain imaging perspective. In order to examine this issue, functional MRI was performed in 22 male and 22 female volunteers. Subjects viewed erotic film excerpts alternating with emotionally neutral excerpts in a standard block-design paradigm. Arousal to erotic stimuli was evaluated using standard rating scales after scanning. Two-sample t-test with uncorrected P < 0.001 values for a priori determined region of interests involved in processing of erotic stimuli and with corrected P < 0.05 revealed gender differences: Comparing women in mid-luteal phase and during their menses, superior activation was revealed for women in mid-luteal phase in the anterior cingulate, left insula, and orbitofrontal cortex. A superior activation for men was found in the left thalamus, the bilateral amygdala, the anterior cingulate, the bilateral orbitofrontal, bilateral parahippocampal, and insular regions, which were maintained at a corrected P in the amygdala, the insula, and thalamus. There were no areas of significant superior activation for women neither in mid-luteal phase nor during their menses. Our results indicate that there are differences between women in the two cycle times in cerebral activity during viewing of erotic stimuli. Furthermore, gender differences with women in mid-luteal phases are similar to those in females outside the mid-luteal phase.

Adolescent↗

PubMed2006

Neural activation during successful and unsuccessful verbal learning in schizophrenia.

Successful and unsuccessful intention to learn words was assessed by means of event-related functional MRI. Eighteen patients with schizophrenia and 15 healthy control participants were scanned while being given two word lists to read and another seven to learn with immediate recall. Neural activation patterns were segregated according to whether words were subsequently recalled or forgotten and these conditions were contrasted with each other and reading. Compared to controls, patients with schizophrenia showed deficits with regard to neural recruitment of right hippocampus and of cerebellar structures during successful verbal learning. Furthermore, a reversal of activated structures was evident in the two groups: Controls showed activation of right frontal and left middle temporal structures during the unsuccessful intention to learn. During successful learning, there was additional activation of right superior parietal lobule. In contrast, patients showed activation of right superior parietal lobule during unsuccessful and successful intention to learn. There were additional frontal and left middle temporal lobe activations during successful learning. We conclude that increased parietal activity may reflect a mechanism which compensates for the lack of hippocampal and cerebellar contributions to verbal learning in schizophrenia.

Adult↗

PubMed2006

Variability of preoperatively determined hepatic volumes in potential living liver donors.

RATIONALE AND OBJECTIVES: The aim of the study is to evaluate variability in hepatic volumes during the preoperative period in potential liver donors. MATERIALS AND METHODS: Eight potential living liver donors underwent preoperative multirow-detector computed tomographic assessment of hepatic transplant volumes twice. Intraindividual delay between the two examinations range was 3-62 days (mean, 30.1 days). Liver volumes were determined in a blinded fashion by an experienced radiologist and a transplantation surgeon. Results were compared and correlated with time of data acquisition during the day. RESULTS: Interobserver variability for assessments of liver volumes range was 6-32 mL (mean, 16 mL). Intraindividually, the difference between the two volume assessments ranged between -103 and +45 mL (mean, -19 mL), corresponding to percentages of alteration between -7.5% and +3.2%. There was no statistical correlation evident concerning volume alterations and specific time of data acquisition. CONCLUSION: Neither time of data acquisition nor waiting period for the surgical procedure seems to affect the accuracy of liver volume calculation. Apparent volume variations likely are in the range of the method error of the applied technique.

Adult↗

PubMed2005

Cerebellar activation patterns in deaf participants for perception of sign language and written text.

To address the influence of language presentation on cerebellar activation, hearing volunteers were compared with deaf individuals using functional magnetic resonance imaging during observation of German sign language and text reading. In deaf participants, German sign language revealed activation of the auditory and language-related areas including the medial temporal gyrus (BA 21) and Crus I. In normal hearing participants not understanding German sign language, Crus I was less activated during observation of German sign language but strongly activated during text reading and accompanied by activation of the medial temporal gyrus. Our results indicate that cerebellar activation in Crus I corresponds to language perception as correlated with cortical activation in language-related areas and is not dependent on the mode of language presentation.

Adolescent↗

PubMed2005

Gender-specific cerebral activation during cognitive tasks using functional MRI: comparison of women in mid-luteal phase and men.

Previous studies of gender-specific differences in functional imaging during spatial and language tasks have been inconclusive. Furthermore, among women, such differences may occur during mid-luteal phase compared to the rest of the menstrual cycle. In order to examine further gender differences, functional MRI was performed in 12 male volunteers and 12 female volunteers (in the mid-luteal phase) during mental rotation and verb-generation tests. Two-sample t-tests with uncorrected P values of <0.001 for the specific regions of interest (ROIs) revealed cerebral activation differences in both stimuli. During mental rotation tests, higher levels of activation were noted in the right medial frontal, precentral, and bilateral inferior parietal cortex, while in women this occurred in the right inferior and medial temporal, right superior frontal cortex, and left fusiform gyrus. During verb-generation tests, higher levels of activation in men was found in the left medial temporal and precentral cortex. Our results indicate that differences in cerebral activity during cognitive tasks can be shown between men and women in the mid-luteal phase. Gender differences while performing a mental rotation task were more prominent than during a verb-generation task.

Adolescent↗

PubMed2005

Cross-modal plasticity in deaf subjects dependent on the extent of hearing loss.

Cross-modal plasticity in deaf subjects is still discussed controversial. We tried to figure out whether the plasticity is dependent on the extent of hearing loss. Three groups of volunteers, comprising twelve individuals each, were investigated. They were characterized by three distinctive features, one had normal hearing, the other one lost hearing and the third had only minimal residual hearing ability. All participants, except those of group one, were capable of using German Sign Language (GSL). The groups were studied with functional MRI in a standard block design during individuals' watching sign language videos alternating with black frame. During sign language conditions, deaf subjects revealed a significant activation of the auditory cortex in both hemispheres comprising Brodmann areas (BA) 42 and 22 corresponding to the secondary associative auditory areas. Additionally, activation of the angular and supramarginal gyrus was seen. Activation of the primary auditory cortex was revealed in deaf subjects with total hearing loss during sign language tasks but not in subjects with residual hearing ability. In conclusion our results indicate a cortical reorganization of the auditory cortex comprising primary auditory fields only present in subjects with total hearing loss.

Adolescent↗

PubMed2005

Prefrontal cortex activity in self-initiated movements is condition-specific, but not movement-related.

Activity of the prefrontal cortex (PFC) has been observed in previous block-design brain imaging studies of self-initiated movements. However, the meaning of these activations remained unclear. A functional MRI experiment was carried out, which utilized an epoch and an event-related analysis approach to the data. We hypothesized that event-related activity of the PFC would argue for a contribution to movement preparation. In contrast, epoch-, but not event-related activity pointed to tonic activations, probably reflecting enhanced attentional states or working memory processing. Twenty-one subjects were examined with 845 T2*-weighted images. During active phases, subjects were instructed to perform self-initiated movements of the right index finger with intertrial intervals of about 8 s. On single subject level, epoch- and event-related regressors were entered into a combined model, estimating the exclusive contribution of either regressor. For statistical inference on multisubject level, random effects analyses were performed. For the epoch regressor, activity within the right dorso- and ventrolateral prefrontal cortex, the bilateral insula, and the right inferior parietal lobe was observed. The event-related regressor detected activity within the right inferior parietal lobe, ventral from the activity found with the epoch regressor. The present results indicate a condition-, but not a movement-related function of the PFC in self-initiated movements. Furthermore, anatomically distinct regions within the inferior parietal cortex seem to be involved in condition-specific and movement-related processes. The observed condition-specific activations are suggested to reflect attentional or working memory processes, supervising task performance, rather than movement preparation or initiation.

Adult↗

PubMed2005

Detection of residual tumor after radiofrequency ablation of liver metastasis with dual-modality PET/CT: initial results.

The aim of this study was to determine the accuracy of dual-modality positron emission tomography(PET)/computed tomography (CT) in the detection of residual tumor after radiofrequency ablation (RFA) of liver metastasis of colorectal cancer. Eleven patients with 16 hepatic metastases (mean size 2.9 cm) from colorectal cancer were enrolled in this study, and 19 RFA procedures and 32 PET/CT examinations were performed. The patients had PET/CT before and after RFA using [18F]-2-fluoro-2-deoxy-D: -glucose. CT images alone were read by two radiologists, PET images alone were evaluated by two nuclear physicians. Fused images were read by one physician of each speciality in consensus. The accuracy for detection of residual tumor by the different imaging modalities following RFA was assessed. Eleven patients with a mean age of 63 (range 55-71) years were evaluated. The mean follow-up period was 393 days. The overall procedure-based sensitivity for detection of residual tumor was 65% for PET and PET/CT and 44% for CT alone. The accuracies were 68% and 47%, respectively. Four patients had residual tumor after RFA, six patients total developed local recurrence. PET/CT therefore possibly proved superior to CT alone when assessing the liver for residual tumor after RFA.

Aged↗

PubMed2005

Comparison of volume, four- and eight-channel head coils using standard and parallel imaging.

Array coils can potentially offer increased signal-to-noise ratio (SNR) over standard coils adjacent to the array elements, while preserving the SNR at the center of the volume. The SNR advantage should theoretically increase with the number of array elements. Parallel acquisition techniques (PAT), on the other hand, can benefit acquisition times or spatial resolution at a cost to SNR as well as image quality. This study examines the question of whether SNR and image quality are still acceptable with two different array coils (four and eight channels) in conjunction with PAT when compared to standard imaging with a volume coil. All imaging was on a 1.5 T MR scanner. T2-weighted, FLAIR, diffusion-weighted, and time of flight (TOF) angiography images were performed with and without PAT in a phantom and in ten healthy volunteers. The phantom measurements demonstrated superior SNR for the eight-channel coil versus the four-channel and standard head coils. Using the eight-channel head coil for in vivo imaging, image quality with PAT (acceleration factor=2) was scored similar to images without PAT using the volume coil. The four-channel head coil suffered from inhomogeneity, lower SNR and poorer image quality when using PAT compared to standard imaging with the volume head coil. Both the in vivo and the phantom results indicate that the eight-channel head coil should be used for the highest quality brain images; this coil can be combined with PAT sequences for shorter acquisition time without a significant decrease in image quality relative to a volume coil without PAT.

Adult↗