Jürgen Reul

Intrasubject reproducibility of presurgical language lateralization and mapping using fMRI.

Background: fMRI is becoming a standard tool for the presurgical lateralization and mapping of brain areas involved in language processing. However, its within-subject reproducibility has yet to be fully explored. Objective: To evaluate within-test and test–retest reliability of language fMRI in consecutive patients undergoing evaluation for epilepsy surgery. Methods: Thirty-four unselected patients were investigated once (within-test reliability) and 12 patients twice (test–retest reliability). The imaging series consisted of an alternating 25-second synonym judgment condition with a 25-second letter-matching condition repeated 15 times. Reproducibility of activation maps of the first and second half of session 1 or activation maps of sessions 1 and 2 was evaluated by comparing one global and three regional lateralization indexes (Broca’s area, remaining prefrontal cortex, temporoparietal area) and on a voxel-by-voxel basis (intraclass correlation coefficient, percentage overlap, correlation of t-values). Results: Global and regional language lateralization was achieved with high reliability within and across sessions. Reproducibility was evenly distributed across both hemispheres but not within each hemisphere. Frontal activations were more reliable than temporoparietal ones. Depending on the statistical threshold chosen, the voxel-by-voxel analysis revealed a mean overlap of activations derived from the first and second investigation of up to 48.9%. Conclusion: Language fMRI proved sufficiently reliable for the determination of global and regional lateralization of language representation in individual unselected patients with epilepsy.

Language mapping in less than 15 minutes: Real-time functional MRI during routine clinical investigation

Neurosurgical interventions often require the presurgical determination of language dominance or mapping of language areas. Results obtained by fMRI are closely correlated with invasive procedures such as electrical stimulation mapping or the intracarotid amobarbital test. However, language fMRI is not used routinely, because postprocessing is time-consuming. We utilized a real-time analysis software installed directly on the MR console computer and SPM99 as reference postprocessing software. We assessed the reliability of the immediate determination of language dominance based on individual activation maps by comparing the results of the visual analysis of images derived from conventional postprocessing with those produced by the real-time tool. All images were rated independently by six senior neurologists blinded to other data. We validated the robustness of the real-time method statistically by comparing global and regional lateralization indices derived from real-time and postprocessing analysis. Functional MRI was performed with a standard 1.5-T whole-body scanner. Brain activity was contrasted between an alternating semantic judgment and letter matching task. Twelve right-handed, healthy control subjects and 12 consecutive patients with drug-resistant, localization-related epilepsy were investigated. The semantic condition induced almost invariably left hemispheric activations in Brocas area, the premotor cortex, the dorsolateral prefrontal cortex, and the temporoparietal region. Although real-time analysis reduced noise less effectively than SPM99, visual ratings and lateralization indices produced highly concordant results with both methods. In conclusion, real-time fMRI, as used here, allowed reliable language lateralization and mapping in less than 15 min during routine clinical MRI investigation with no need for postprocessing.

Functional segregation of the temporal lobes into highly differentiated subsystems for auditory perception: an auditory rapid event-related fMRI-task

With this study, we explored the blood oxygen level-dependent responses within the temporal lobe to short auditory stimuli of different classes. To address this issue, we performed an attentive listening event-related fMRI study, where subjects were required to concentrate during the presentation of different types of stimuli. Because the order of stimuli was randomized and not predictable for the subject, the observed differences between the stimuli types were interpreted as an automatic effect and were not affected by attention. We used three types of stimuli: tones, sounds of animals and instruments, and words. We found in all cases bilateral activations of the primary and secondary auditory cortex. The strength and lateralization depended on the type of stimulus. The tone trials led to the weakest and smallest activations. The perception of sounds increased the activated network bilaterally into the superior temporal sulcus mainly on the right and the perception of words led to the highest activation within the left superior temporal sulcus as well as in left inferior frontal gyrus. Within the left temporal sulcus, we were able to distinguish between different subsystems, showing an extending activation from posterior to anterior for speech and speechlike information. Whereas posterior parts were involved in analyzing the complex auditory structure of sounds and speech, the middle and anterior parts responded strongest only in the perception of speech. In summary, a functional segregation of the temporal lobes into several subsystems responsible for auditory processing was visible. A lateralization for verbal stimuli to the left and sounds to the right was already detectable when short stimuli were used.

Cranial magnetic resonance imaging in genetically proven myotonic dystrophy type 1 and 2

Abstract.Cranial magnetic resonance imaging (MRI) in 19 German patients with genetically proven myotonic dystrophy Type 1 (DM1, n = 10) or Type 2 (DM2, n = 9) showed pathological findings consisting of white matter lesions (WML) and/or brain atrophy in 9/10 DM1 and 8/9 DM2 patients. Anterior temporal WML (ATWML) were exclusively seen in DM1 patients. Our findings indicate a high frequency of central nervous system (CNS) involvement in both disorders. However, temporopolar pathology, previously associated with intellectual dysfunction, seems to be restricted to DM1.

Cerebral lesions can impair fMRI‐based language lateralization

Purpose:  Several small patient studies and case reports raise concerns that the reliability of functional magnetic resonance imaging (fMRI) may be impaired in the vicinity of cerebral lesions. This could affect the clinical validity of fMRI for presurgical language lateralization. The current study sets out to identify if a systematic effect of lesion type and localization on fMRI exists.

Evidence for a dysfunctional retrosplenial cortex in patients with schizophrenia: a functional magnetic resonance imaging study with a semantic—perceptual contrast

We investigated whether the retrosplenial and the posterior cingulate cortex (RS-PCC) is functionally impaired in schizophrenia patients. Therefore, we measured functional magnetic resonance imaging (fMRI) signal changes associated with a synonym-judgment task known to activate, among other areas, the RS-PCC. Compared to 12 matched control subjects, 12 schizophrenia patients exhibited reliably weaker activations in the RS-PCC, the dorsolateral prefrontal cortex and the left orbitofrontal cortex (P < 0.05, corrected). Differences in frontal activations are in line with previous studies showing a structurally and functionally affected prefrontal cortex in schizophrenia. The impaired RS-PCC functionality in a semantic task may relate to verbal memory deficits frequently observed in schizophrenia patients, because this region is pivotal for gating information into the medial temporal lobe memory system.

Plug & Play fMRI

965 popular. Nowadays, the real-time fMRI analyses could be performed on the MR-scanner itself . Those optional software packages are allowing a statistical analysis during or directly after the measurement. This enables the fMRI investigator, not only to explore the active brain areas, but also to decide whether an additional scan would be needed, in case of large movements or low BOLD signals. Those essential decisions are important for the success of an fMRI study, and should be made before the patient has left the scanner. This simplifies the scanning procedure and saves time, especially in a clinical environment. An offline analysis, using common functional imaging software could complete the individual picture of the patient’s diseases and abilities. To facilitate the performance of a clinical fMRI study, we developed an easy-to-use presentation tool, simplifying the scanning and presentation procedure by an automated synchronization of MR-scanner and stimulus PC, which is running the presentation of the tasks and collecting the subject’s responses. Introduction

Experiences and Applicability of Presurgical Real-Time fMRI

1092 success of the investigation. Besides this, the development of easyto-use presentation software and the standardization of paradigms allows one to run fMRI as a clinical diagnostic procedure also in a pure clinical environment, without specialized staff for fMRI . One can predict, that fMRI will become a standard procedure in the future, and its reliability and applicability in clinical cases is explored by an increasing number of studies . Common to all studies is a successfully location of the most relevant functional systems, like memory, language, sensorimotor, systems for auditory or visual perception. The studies are also demonstrating a partly large intraand inter-subject variability with respect to signal strength , shape of the BOLD signal 21 and also an age dependency of the signal strength is reported . Beside this, the exploration of an individual case could lead to additional problems like reduced or unusual BOLD signals close or around pathologically changed areas. Finally, the development of easy-to-use fMRI procedures 11 is an important progress on the way to a more clinical use of fMRI. This article describes our experiIntroduction