Impairment in basal limbic function in schizophrenia during affect recognition.

Patients with schizophrenia routinely fail to perform affect recognition tasks as accurately as healthy controls. The investigation of performance-related changes in cerebral activation in healthy subjects may facilitate the understanding of adaptation processes to different levels of difficulty and help to interpret the activation changes found in schizophrenic patients. Nine first hospitalized partly remitted schizophrenic patients and 10 healthy controls participated in an fMRI study with a facial affect discrimination and labeling task. Seven of the 10 healthy subjects were reexamined with changed stimulus conditions adapted according to the mean accuracy scores detected in schizophrenic patients. Controls showed a significantly increased activation of the right gyrus frontalis medialis with rising task difficulty during both tasks. The schizophrenic patients demonstrated a significantly decreased activation of the anterior cingulate during facial affect discrimination and of the amygdala-hippocampal complex bilaterally during facial affect labeling. In addition, an increased activation of the gyrus frontalis medialis bilaterally became apparent in the schizophrenic patients. It is suggested that the latter may reflect a compensatory effort for deficits in more basal limbic functions.

An MRI-compatible surgical robot for precise radiological interventions.

OBJECTIVE: A variety of medical robots have been developed in recent years. MRI, including MR angiography and morphological imaging, with its excellent soft-tissue contrast is attractive for the development of interventional MRI-guided therapies and operations. This paper presents a telerobotic device for use in CT- and/or MR-guided radiological interventions. A robotic device for precise needle insertion during MR-guided therapy of spinal diseases will be briefly described. MATERIALS AND METHODS: Actuation of robots in an MRI environment is difficult due to the presence of strong magnetic fields. Therefore, the robot was constructed of nonmagnetic materials. The system frame was built from polyether ether ketone (PEEK) and fiber-reinforced epoxy, and actuated using ultrasonic and pneumatic motors. Completely MR-compatible sensors were developed for positioning control. RESULTS: Accuracy evaluation procedures and phantom tests were performed, with the required accuracy of approximately 1 mm being achieved and no significant artifacts being caused by the robotic device during MR image acquisition.

Improvement of auditory hallucinations and reduction of primary auditory area's activation following TMS.

BACKGROUND: In the present case study, improvement of auditory hallucinations following transcranial magnetic stimulation (TMS) therapy was investigated with respect to activation changes of the auditory cortices. METHODS: Using functional magnetic resonance imaging (fMRI), activation of the auditory cortices was assessed prior to and after a 4-week TMS series of the left superior temporal gyrus in a schizophrenic patient with medication-resistant auditory hallucinations. RESULTS: Hallucinations decreased slightly after the third and profoundly after the fourth week of TMS. Activation in the primary auditory area decreased, whereas activation in the operculum and insula remained stable. CONCLUSIONS: Combination of TMS and repetitive fMRI is promising to elucidate the physiological changes induced by TMS.

Toward clinical X-ray phase-contrast CT: demonstration of enhanced soft-tissue contrast in human specimen.

OBJECTIVES: X-ray computed tomography (CT) using phase contrast can provide images with greatly enhanced soft-tissue contrast in comparison to conventional attenuation-based CT. We report on the first scan of a human specimen recorded with a phase-contrast CT system based on an x-ray grating interferometer and a conventional x-ray tube source. Feasibility and potential applications of preclinical and clinical phase-contrast CT are discussed. MATERIALS AND METHODS: A hand of an infant was scanned ex vivo at 40 kVp tube voltage. The simultaneously recorded attenuation and phase-contrast CT images were quantitatively compared with each other, by introducing a specific Hounsfield unit for phase-contrast imaging. RESULTS: We observe significantly enhanced soft-tissue contrast in the phase images, when compared with the attenuation data. Particularly, tendons and ligaments appear with strongly increased contrast-to-noise ratio. CONCLUSIONS: Our results demonstrate the huge potential of phase-contrast CT for clinical investigations of human specimens and, potentially, of humans. Because the applied technique works efficiently with conventional x-ray tubes and detectors, it is suitable for the realization of preclinical and clinical phase-contrast CT systems.

Phase-contrast imaging and tomography at 60 keV using a conventional x-ray tube source.

Phase-contrast imaging at laboratory-based x-ray sources using grating interferometers has been developed over the last few years for x-ray energies of up to 28 keV. Here, we show first phase-contrast projection and tomographic images recorded at significantly higher x-ray energies, produced by an x-ray tube source operated at 100 kV acceleration voltage. We find our measured tomographic phase images in good agreement with tabulated data. The extension of phase-contrast imaging to this significantly higher x-ray energy opens up many applications of the technique in medicine and industrial nondestructive testing.