Functional MR Studies Research Articles

Neuroscience and architecture: What does the brain tell to an emotional experience of architecture via a functional MR study?

Environment psychologically affects individuals. According to the base of cognitive psychology, there is a direct relationship between human behavior, environment, and emotional process. Assuming that pleasantness and unpleasantness are associated with peripheral nervous system activation, the current study aims to explore if the pleasant or unpleasant architectural places can stimulate the brain regions engaged in emotions or not. As the main contribution, we used functional magnetic resonance imaging (fMRI) measuring blood oxygenation level-dependent (BOLD) changes to effectively detect the brain's region that mainly responds to the emotional-perceptual processes. Based on the results of examining the emotional assessment model of “Pleasure-Arousal” applied to 140 students, 30 most-rated images representing 15 pleasant and 15 unpleasant places were shown to 32 participants in a 1.5-T MRI scanner. After applying standard preprocessing steps (re-alignment, slice-timing, co-registration, segmentation, normalization, and smoothing) to functional MR images, first-level analysis was applied to each subject. The results were evaluated using statistical corrections at different levels for female and male participants with the second-level analysis. In conclusion, it has been shown that there is a significant linkage between environmental experience and brain activation so that the architectural qualities can change blood flow in specific brain regions.

A high temporal/spatial resolution neuro-architecture study of rodent brain by wideband echo planar imaging

Latest simultaneous multi-slice (SMS) methods greatly benefit MR efficiency for recent studies using parallel imaging technique. However, these methods are limited by the requirement of array coils. The proposed Coherent Wideband method, which employs an extended field of view to separate multiple excited slices, can be applied to any existing MRI instrument, even those without array coils. In this study, the Coherent Wideband echo-planar imaging method was implemented on 7 T animal MRI to exhibit comprehensive enhancements in neuro-architecture, including diffusion tensor imaging (DTI) and functional MR studies (fMRI). Under the same scan time, the time-saving effect can be manipulated to increase the number of averages for DTI SNR improvement, reducing fractional anisotropy difference by 56.9% (from 0.072 to 0.041) and the deviation angle by 64% (from 25.3° to 16.2°). In summary, Coherent Wideband Echo Planar Imaging (EPI) will provide faster, higher resolution, thinner slice, or higher SNR imaging for precision neuro-architecture studies.

Imaging Evaluation of Recurrence in Treated Prostate Cancer

: Prostate cancer is the most common cancer in men and although most prostate cancers are slow growing but aggressive prostate cancers cases are seen too. Prevalence of prostate cancer vary widely across the world, it is more common in the developed countries. It is the second leading cause of cancer-related death in men in the United States and the sixth cause of cancer-related death globally in the world. Many cases of prostate cancer remain subclinical and never have symptoms until late progressive stages of the disease. About 85% of patients diagnosed with prostate cancer have localized disease and could be treated by definitive radiation therapy or radical prostatectomy. In 3050% of patients who had radical prostatectomy, PSA relapse happens at 5 years. Diagnosis and treatment of patients with PSA relapse are difficult. Detection of local recurrence of prostate cancer is important because it could be treated by local radiation therapy. Local treatment of local recurrence of prostate cancer have higher rate of complications in comparison to treatment of primary prostate cancer, hence, accurate detection of local recurrence and excluding distant metastasis is important. Distant metastasis is treated by hormone therapy. Imaging studies play an important role in detection of local recurrence of prostate cancer and its differentiation with distant metastasis. The main imaging studies that are used for evaluation of patients after radical prostatectomy are transrectal ultrasonography (TRUS) and magnetic resonance imaging (MRI). The patients with local recurrence of prostate cancer could be divided to three groups based on imaging studies. 1- Patients who have a mass lesion in surgical bed that is detectable by both MRI and TRUS. TRUS is useful for obtaining biopsy from these mass lesions. 2- Patients who have residual prostate tissue detectable by both MRI and TRUS. The residual tissue may be tumoral and responsible for local recurrence or may be non-tumoral. MRI functional studies including dynamic contrast study, diffusion weighted imaging (DWI) and MR spectroscopy (MRS) is able to confirm presence of tumoral tissue within the prostate glands remnant. Differentiation of tumoral and non-tumoral prostate remnant is not possible by means of TRUS but TRUS is useful for doing biopsy from the prostate remnant. 3- There is no mass lesion in surgical bed and anastomotic site and surrounding tissues have normal appearance in both TRUS and conventional MRI but local tumor recurrence is detected by functional MR studies like abnormal early phase enhancement in surgical bed structures, restrictive pattern in DWI or rise in choline to creatine ratio in MRS. There is no role for TRUS in detection and management of this third group of patients. CT scan is not useful for evaluation of prostate gland itself but is beneficial for evaluation of lungs and abdominal organs and can detect skeletal metastasis.

Assessing language and visuospatial functions with one task: A “dual use” approach to performing fMRI in children

In order to increase the rate of successful functional MR studies in children it is helpful to shorten the time spent in the scanner. To this effect, assessing two cognitive functions with one task seems to be a promising approach. The hypothesis of this study was that the control condition of an established language task (vowel identification task, VIT) requires visuospatial processing and that the control condition (VIT(CC)) therefore may also be applicable to localize visuospatial functions. As a reference task, a visual search task (VST, previously established for use in children) was employed. To test this hypothesis, 43 children (19 f, 24 m; 12.0±2.6, range 7.9 to 17.8 years) were recruited and scanned using both tasks. Second-level random effects group analyses showed activation of left inferior-frontal cortex in the active condition of the VIT, as in previous studies. Additionally, analysis of the VIT(CC) demonstrated activation in right-dominant superior parietal and high-frontal brain regions, classically associated with visuospatial functions; activation seen in the VST was similar with a substantial overlap. However, lateralization in the parietal lobe was significantly more bilateral in the VST than in the VIT(CC). This suggests that the VIT can not only be applied to assess language functions (using the active>control contrast), but also that the control>active condition is useful for assessing visuospatial functions. Future task design may benefit from such a "dual use" approach to performing fMRI not only, but also particularly in children.

A three-dimensional digital segmented and deformable brain atlas of the domestic pig

We used high-magnetic field (4.7 T) magnetic resonance imaging (MRI) to build the first high-resolution (100 μm × 150 μm × 100 μm) three-dimensional (3D) digital atlas in stereotaxic coordinates of the brain of a female domestic pig ( Sus scrofa domesticus). This atlas was constructed from one hemisphere which underwent a symmetrical transformation through the midsagittal plane. Concomitant construction of a 3D histological atlas based on the same scheme facilitated control of deep brain structure delimitation and enabled cortical mapping to be achieved. The atlas contains 178 individual cerebral structures including 42 paired and 9 single deep brain structures, 5 ventricular system areas, 6 paired deep cerebellar nuclei, 12 cerebellar lobules and 28 cortical areas per hemisphere. Given the increasing importance of pig brains in medical research, this atlas should be a useful tool for intersubject normalization in anatomical imaging as well as for precisely localizing brain areas in functional MR studies or electrode implantation trials. The atlas can be freely downloaded from our institution's Website.

Novel MRI approaches to assess patients with multiple sclerosis

This review summarizes novel MRI approaches for the investigation of lesion burden and understanding of the pathophysiology of multiple sclerosis (MS). Recent technical advances are improving our ability to detect and define the nature of focal lesions and 'diffuse' tissue damage in MS as well as the functional consequences of such structural abnormalities. New contrast agents allow to monitor the pluriformity of MS inflammation. Double inversion recovery sequences enable us to detect and monitor the evolution of MS lesions in the cortex. High and ultra-high field scanners are improving imaging of MS-related abnormalities at an unprecedented resolution. Furthermore, this new generation of scanners has the potential to ameliorate structural and functional MR studies of the disease. All of this has contributed, and is likely to continue to contribute, to the definition of the factors associated with the development of irreversible disability in MS. Finally, new analysis methods have allowed to track regional disease-related changes and are resulting in an increased correlation between MRI and clinical deficits. Novel MR approaches highlighted previously unrecognized or neglected aspects of MS pathophysiology, which are likely to improve our understanding of the heterogeneous clinical manifestations of this condition.

Simulated MR magnetic field induces steady‐state changes in brain dynamics: Implications for interpretation of functional MR studies

We examined whether a magnetic field comparable to one of the fields produced during MRI induced steady-state changes in brain electrical activity while the field was applied (called a presence effect to distinguish it from evoked potentials). The electroencephalogram was measured from standard scalp locations in the presence and absence of 100-200 microT, 60 Hz, and the effect of the field was evaluated by nonlinear (recurrence analysis) and linear techniques; individual subjects served as their own controls. Using recurrence analysis, changes in brain activity lasting 1 sec (the longest interval considered) were found in 21 of 22 subjects (P < 0.05 for each subject). The presence effect was not detected using linear analysis and was reversible, as indicated by a return of brain activity to baseline levels in all subjects within 2 sec of field offset. The possible role of artifacts or systematic errors was ruled out by studies using electrical phantoms and by analyses of electroencephalograms recorded during sham exposure. It is reasonable to expect that actual scanner magnetic fields also produce nonlinear steady-state perturbations of brain dynamical activity. The effect may influence the picture of brain connectivity inferred in some functional MR studies.

Functional MR study of hepatic fibrosis

The accurate diagnosis and staging of hepatic fibrosis is crucial for treatment and prognosis of liver disease. The current gold standard is liver biopsy, but it cannot be used in population-based screening, and has well known drawbacks if used for monitoring of disease progression or treatment results. Functional MR, as a non-invasive method, is increasingly used in hepatic fibrosis and became the current hot spot. Most recently available functional MR imaging techniques including diffusion weighted imaging, perfusion weighted imaging and MR spectroscopy can detect cirrhosis or fibrosis reasonably accurately. However, to date only MR elastography has been able to stage fibrosis or diagnose mild disease. MR diffusion weighted appears next most promising.

Whole body MRI and PET/CT in haematological malignancies.

The usefulness of whole body magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT) in haematological malignancies is reviewed. PET/CT combining functional and anatomical information is currently a valuable tool in the management of patients with lymphoma, especially in the assessment of early treatment response. MRI is advantageous in evaluating bone marrow involvement and therefore plays an important role in clinical decision making for patients with myeloma. The development of whole body functional MR studies is underway and can potentially complement the PET/CT for better patient care.

Functional MR study of a motor task and the Tower of London task at 1.0 T

The use of functional magnetic resonance imaging (fMRI) for clinical applications and basic neuroscience is constantly increasing. The discussion about minimum performance requirement for a correct implementation of fMRI is still open, and one of the critical points is the magnetic field strength. We tested the feasibility of fMRI at 1.0 T during motor and cognitive tasks. Fourteen healthy subjects were scanned during a motor task and 12 while performing the Tower of London task. In the activated areas, the percentage signal change due to BOLD (blood oxygenation level dependent) contrast was analysed. To check basic image quality of the acquisition system we measured quality indices in a temporal series of images of a phantom. Motor and cognitive brain activations matched previous results obtained at higher field strengths. The mean percentage change over subjects in the motor task was in the range 1.3-2.6% for the primary motor area and 0.8-6.7% for the cerebellum. In the cognitive task, the mean percentage change over subjects was 0.7-1.2% for a frontal area and 0.6-2.8% for a parietal area. The percentage noise of the phantom temporal series was less than 0.4%. Percentage changes and signal to noise ratio, although lower than that obtained with high-field systems, allowed activation maps to be obtained in all subjects. Our results replicate previous fMRI results demonstrating reproducible motor-related brain activations and extend the field to a complex cognitive task, thus providing evidence of the safety for routine clinical use of 1-T equipment.

Cerebral activation during vagus nerve stimulation: a functional MR study.

To study the short-term effects of vagus nerve stimulation (VNS) on brain activation and cerebral blood flow by using functional magnetic resonance imaging (fMRI). Five patients (three women, two men; mean age, 35.4 years) who were treated for medically refractory epilepsy with VNS, underwent fMRI. All patients had a nonfocal brain MRI. The VNS was set at 30 Hz, 0.5-2.0 mA for intervals of activation of 30 s on and 30 s off, during which the fMRI was performed. Statistical parametric mapping (SPM) was used to determine significant areas of activation or inhibition during vagal nerve stimulation (p < 0.05). VNS-induced activation was detected in the thalami bilaterally (left more than right), insular cortices bilaterally, ipsilateral basal ganglia and postcentral gyri, right posterior superior temporal gyrus, and inferomedial occipital gyri (left more than right). The most robust activation was seen in the thalami (left more than right) and insular cortices. VNS-induced thalamic and insular cortical activation during fMRI suggests that these areas may play a role in modulating cerebral cortical activity, and the observed decrease in seizure frequency in patients who are given VNS may be a consequence of this increased activation.

MR-imaging of non-Alzheimer's dementia.

Up to now, computerized tomography (CT) and MR-imaging have been used for the morphological assessment of dementia patients, while MRI has become the structure imaging modality of choice. With the advent of fast and ultrafast sequences provided by higher gradient field strengths, functional MR studies like diffusion, perfusion and activation studies become available. The greatest advantage of MR is its versatility including MR-imaging, 3D postprocessing, MR-volumetry, MR-spectroscopy, MR-angiography, MR-perfusion and diffusion imaging as well as functional MRI activation studies. The application of the multimodal MR-technology in dementia disorders has already began and has to be validated in clinical practice. The multimodality of MR represents a diagnostic challenge for the future with the hope, that the diagnostic efficacy, which has to be proven, is also followed by an improvement of patients care and prognosis.

MRT-Untersuchung zur Dehnbarkeit der Kreuzbänder gesunder Kniegelenke

Examination of the distensibility of the cruciate ligaments to evaluate the tense plasty of the cruciate ligaments. A functional MR study was performed using a Magnetom Open (0.2 Tesla, Fa. Siemens). We measured the length and width of the anterior and posterior cruciate ligament in volunteers (n = 12), age 20-40. We examined in 4 knee positions between maximal extension and maximal flexion. Using the Wilcoxon test, the statistics do not show any significant difference between the length and width of the cruciate ligaments in the monoxial movement. Our results may support the operative tense plasty of the cruciate ligaments although the entire complex mechanical system has not been examined.

MR Study of Normal Joint Function Using a Low Field Strength System

A functional MR study was performed using a 0.064 T permanent magnet MR system. The shoulder joints, elbow joints, hip joints, and knee joints of three volunteers (mean height and weight, 176 cm and 71 kg, respectively) were examined at incremental joint angles in three to eight stages during flexion-extension, abduction-adduction, or pronation-supination movement. Each set of 16 images was obtained in 4 min, 49 s using three-dimensional Fourier transformation methods with gradient echo pulse sequences. The images were evaluated in static mode and sometimes in cine mode. The findings obtained about the physiology of these normal joints was generally compatible with findings previously accumulated in the field of kinesiology. The study suggests that this method can be useful for in vivo study of kinesiology and pathogenesis of diseases and that patients with most types of contracture or deformity can be examined by MR imaging.