Test-retest analysis with functional MR of the activated area in the human visual cortex.

PURPOSETo investigate the intersubject and intrasubject variability of the activated area in the visual cortex with functional MR imaging.METHODSDouble-section gradient-echo MR images were acquired at 1.5 T in 28 healthy volunteers using the fast low-angle shot (FLASH) technique. Visual stimulation was obtained with light-emitting diode (LED) goggles. Eighteen volunteers were studied twice. The size of the activated areas in the visual cortex and the increase in signal were measured. A reproducibility ratio for size (R[size]) and for location (R[overlap]) was calculated on a scale of 0.0 to 1.0.RESULTSActivation was seen in 89% of the subjects. The size of the activated area was widely variable among subjects: mean, 460 +/- 284 mm2; range, 0 to 1029 mm2 in the first study in all volunteers. Signal increases ranged from 3.2% to 10.9%, with a mean of 6.6 +/- 1.7%. The mean values of intrasubject variability testing were R(size) = 0.83 +/- 0.16 and R(overlap) = 0.31 +/- 0.11.CONCLUSIONFunctional MR imaging with the FLASH technique is useful in identifying certain cortical areas that have quite variable locations among subjects. This study provides reference data for the intrasubject and intersubject variability of the activation pattern of the visual cortex.     

Global spatial normalization of human brain using convex hulls.

Global spatial normalization transforms a brain image so that its principal global spatial features (position, orientation and dimensions) match those of a standard or atlas brain, supporting consistent analysis and referencing of brain locations. The convex hull (CH), derived from the brain's surface, was selected as the basis for automating and standardizing global spatial normalization. The accuracy and precision of CH global spatial normalization of PET and MR brain images were evaluated in normal human subjects. METHODS: Software was developed to extract CHs of brain surfaces from tomographic brain images. Pelizzari's hat-to-head least-square-error surface-fitting method was modified to fit individual CHs (hats) to a template CH (head) and calculate a nine-parameter coordinate transformation to perform spatial normalization. A template CH was refined using MR images from 12 subjects to optimize global spatial feature conformance to the 1988 Talairach Atlas brain. The template was tested in 12 additional subjects. Three major performance characteristics were evaluated: (a) quality of spatial normalization with anatomical MR images, (b) optimal threshold for PET and (c) quality of spatial normalization for functional PET images. RESULTS: As a surface model of the human brain, the CH was shown to be highly consistent across subjects and imaging modalities. In MR images (n = 24), mean errors for anterior and posterior commissures generally were <1 mm, with SDs < 1.5 mm. Mean brain-dimension errors generally were <1.3 mm, and bounding limits were within 1-2 mm of the Talairach Atlas values. The optimal threshold for defining brain boundaries in both 18F-fluorodeoxyglucose (n = 8) and 15O-water (n = 12) PET images was 40% of the brain maximum value. The accuracy of global spatial normalization of PET images was shown to be similar to that of MR images. CONCLUSION: The global features of CH-spatially normalized brain images (position, orientation and size) were consistently transformed to match the Talairach Atlas in both MR and PET images. The CH method supports intermodality and intersubject global spatial normalization of tomographic brain images.     

Reproducibility of functional MR imaging: preliminary results of prospective multi-institutional study performed by Biomedical Informatics Research Network

PURPOSE: To prospectively investigate the factors--including subject, brain hemisphere, study site, field strength, imaging unit vendor, imaging run, and examination visit--affecting the reproducibility of functional magnetic resonance (MR) imaging activations based on a repeated sensory-motor (SM) task. MATERIALS AND METHODS: The institutional review boards of all participating sites approved this HIPAA-compliant study. All subjects gave informed consent. Functional MR imaging data were repeatedly acquired from five healthy men aged 20-29 years who performed the same SM task at 10 sites. Five 1.5-T MR imaging units, four 3.0-T units, and one 4.0-T unit were used. The subjects performed bilateral finger tapping on button boxes with a 3-Hz audio cue and a reversing checkerboard. In a block design, 15-second epochs of alternating baseline and tasks yielded 85 acquisitions per run. Functional MR images were acquired with block-design echo-planar or spiral gradient-echo sequences. Brain activation maps standardized in a unit-sphere for the left and right hemispheres of each subject were constructed. Areas under the receiver operating characteristic curve, intraclass correlation coefficients, multiple regression analysis, and paired Student t tests were used for statistical analyses. RESULTS: Significant factors were subject (P < .005), k-space (P < .005), and field strength (P = .02) for sensitivity and subject (P = .03) and k-space (P = .05) for specificity. At 1.5-T MR imaging, mean sensitivities ranged from 7% to 32% and mean specificities were higher than 99%. At 3.0 T, mean sensitivities and specificities ranged from 42% to 85% and from 96% to 99%, respectively. At 4.0 T, mean sensitivities and specificities ranged from 41% to 73% and from 95% to 99%, respectively. Mean areas under the receiver operating characteristic curve (+/- their standard errors) were 0.77 +/- 0.05 at 1.5 T, 0.90 +/- 0.09 at 3.0 T, and 0.95 +/- 0.02 at 4.0 T, with significant differences between the 1.5- and 3.0-T examinations and between the 1.5- and 4.0-T examinations (P < .01 for both comparisons). Intraclass correlation coefficients ranged from 0.49 to 0.71. CONCLUSION: MR imaging at 3.0- and 4.0-T yielded higher reproducibility across sites and significantly better results than 1.5-T imaging. The effects of subject, k-space, and field strength on examination reproducibility were significant.     

Functional MR in the evaluation of dementia: correlation of abnormal dynamic cerebral blood volume measurements with changes in cerebral metabolism on positron emission tomography with fludeoxyglucose F 18.

PURPOSETo determine whether magnetic susceptibility functional MR imaging of cerebral blood volumes provides information similar to fludeoxyglucose F 18 positron emission tomography (PET) brain images in patients undergoing evaluation for dementia.METHODSTen subjects were studied with both PET and functional MR. Clinical diagnoses included probable Alzheimer disease (n = 5), possible Alzheimer disease (n = 1), Pick disease (n = 2), and primary progressive aphasia (n = 2). The studies were quantitatively evaluated by coregistration of PET and functional MR images followed by regression analyses of corresponding regions of interest. Qualitatively, each brain was categorized into eight regions, and each was classified as normal or abnormal by visual inspection.RESULTSCorrelation coefficients between registered functional MR and PET images were excellent (mean, r = 0.58) in most of the cerebrum. Significant correlations were observed in 72 of 74 brain sections. Qualitatively, 16 brain regions were judged to be abnormal by both MR imaging and PET; 46 regions were normal by both; 10 regions were abnormal by PET only; and 8 regions were abnormal only by functional MR. The concordance between functional MR and PET was 78%, which was highly significant.CONCLUSIONCerebral blood volumes images derived from magnetic susceptibility (functional MR) provide information similar to fludeoxyglucose F 18 PET images in demented patients undergoing evaluation for dementia.     

Presurgical evaluation of the motor hand area with functional MR imaging in patients with tumors and dysplastic lesions

PURPOSE: To test an optimized functional magnetic resonance (MR) imaging procedure to depict the motor hand representation area (HRA) in patients with epilepsy lesions near the central sulcus. MATERIALS AND METHODS: Fast low-angle shot MR imaging was performed with an oblique single-section imaging technique in eight control subjects (10 hemispheres) and six patients (12 hemispheres). Three series of five activation images (obtained while subjects performed repetitive finger-to-thumb opposition movements) and five rest images were acquired. Each hemisphere was studied in three adjacent sections. Difference maps (obtained with simple subtraction between activation and rest images) were compared with t-test maps. RESULTS: In control subjects, the HRA was visible in 27 of 30 sections. Qualitatively, activation was seen better on t-test maps in 14 and on difference maps in four of these sections. In all patients, motor activation could be seen in the hemisphere that contained the lesion. This activation was considered normal in four patients. In two patients, the HRA was deformed. Functional MR imaging activation in the motor area was confirmed with Penfield stimulation in five patients. CONCLUSION: Functional MR imaging findings in the preoperative assessment of dysplastic lesions around the central sulcus are the same as for tumors. t-test maps are superior to difference maps in the treatment of motor functional MR imaging data.     

What is different about a radiologist's brain?

PURPOSE: To investigate neuronal activations during processing of radiologic and nonradiologic images by experienced radiologists and nonradiologist subjects by using event-related functional magnetic resonance (MR) imaging. MATERIALS AND METHODS: Study was approved by local ethics committee, and informed consent was obtained. Radiologic and control images were presented to 12 experienced radiologists (mean age, 35.8 years +/- 3.6 [standard deviation]) and 12 nonradiologist subjects (mean age, 33.0 years +/- 6.9). Half of the images were artificially manipulated-that is, for example, a local shadow was introduced. Subjects had to indicate whether a visually presented image was original or manipulated, while neuronal activity was assessed by using event-related functional MR imaging. Analysis was performed on the basis of fixed-effects general linear models with correction for multiple comparisons (false discovery rate). RESULTS: Radiologic images, when compared with control images, evoked stronger activations exclusively in the group of radiologists, notably in the bilateral middle and inferior temporal gyrus, bilateral medial and middle frontal gyrus, and left superior and inferior frontal gyrus (P < .001, corrected). Additionally, visual processing of control images (ie, nonradiologic images) differed significantly between experienced radiologists and nonradiologist subjects (P < .001, corrected). Radiologists showed strongest activation in the left-dominant more posterior superior and inferior parietal lobule, while nonradiologist subjects showed strongest activation in the right-dominant more anterior superior and inferior parietal lobule and postcentral gyrus. CONCLUSION: With radiologic experience, there is selective enhancement of brain activation with radiologic images, and the visual system is modified in general.     

Functional MR of brain activity and perfusion in patients with chronic cortical stroke.

PURPOSE(1) To determine whether functional MR can reliably map functional deficits in patients with stroke in the primary visual cortex; (2) to determine whether functional MR can reliably map perfusion deficits; and (3) to determine whether functional MR can give any additional diagnostic information beyond conventional MR.METHODSSeven patients who had had a stroke in their primary visual system were examined using two functional MR techniques: (1) dynamic susceptibility contrast imaging, and (2) cortical activation mapping during full-field visual stimulation. Maps of relative cerebral blood volume and activation were created and compared with visual field examinations and conventional T2-weighted images on a quadrant-by-quadrant basis in five of these patients.RESULTSVisual field mapping matched with both T2-weighted conventional images and activation mapping of 16 of 18 quadrants. In two quadrants, the activation maps detected abnormalities that were present on the visual field examination but not present on the T2-weighted images nor on the relative cerebral blood volume maps, which may indicate abnormal function without frank infarction. In addition, the activation maps demonstrated decreased activation in extrastriate cortex and had normal T2 signal and relative cerebral blood volume but was adjacent to infarcted primary cortex, mapping in vivo how stroke in one location can affect the function of distant tissue.CONCLUSIONFunctional MR techniques can accurately map functional and perfusion deficits and thereby provide additional clinically useful information. Additional studies will be needed to determine the prognostic utility of functional MR in stroke patients.     

Correlation of reaction time in and out of the functional MR unit

RATIONALE AND OBJECTIVES: The authors performed this study to determine whether reaction times (RTs) recorded in the functional magnetic resonance (MR) imaging environment reflect the performance of the patient outside the imaging room. MATERIALS AND METHODS: Fifteen healthy control subjects (mean age, 61.6 years) performed a simple reaction time (SRT) task outside the MR magnet and a visuomotor response time task inside the magnet with use of block-design and event-related paradigms. For both behavioral and functional MR imaging tests, subjects tapped the right index finger upon the appearance of a visual cue. The mean RTs for out-of-magnet and functional MR imaging paradigms were compared. Results. There was a statistically significant difference in RTs between block-design and single-event paradigms (t = 3.458, P < .004). The RT values during functional MR imaging and SRT tasks did not show significant differences (.65 < P < .7, paired t test). However, no correlation was found in RT values between event-related (p = -0.004, P = .15) or block-design (p = 0.03, P = .13) paradigms and SRT data. With the block-design functional MR imaging paradigm, the RT was significantly faster (P < .0003) at the beginning of the session than the end, illustrating the effect of anticipation. CONCLUSION: Functional MR imaging RTs must be used to determine the correlation between subjects' performance and the volume of brain activation in a functional MR imaging experiment. The effect of anticipation should be minimized, which could best be achieved by using event-related paradigms.     

Central processing of rectal pain: a functional MR imaging study

BACKGROUND AND PURPOSE: Although the central processing of somatic pain has been dealt with in numerous brain imaging studies, the neural correlates of visceral pain have received much more limited attention. Our goal was to assess the feasibility of detecting brain activation patterns induced by rectal pain by means of functional MR imaging. We hypothesized that the cerebral processing of rectal pain would exhibit strong similarities with the central processing of somatic pain. METHODS: Functional MR imaging data were obtained from eight healthy subjects. A block paradigm was applied. Rectal pain was induced by inflating a latex balloon catheter that had been inserted into the rectum. Functional responses were established by means of cross-correlation analysis. RESULTS: Activation was detected within the anterior cingulate gyrus, the prefrontal cortex, the insular cortex, the sensory-motor cortex, the inferior parietal lobule, the posterior cingulate gyrus, and the visual cortex. CONCLUSION: Functional MR imaging of visceral pain is feasible in healthy subjects. The activation patterns observed in this study support the hypothesis that the cerebral processing of visceral pain involves multiple components, similar to the central processing of somatic pain. Our results constitute a first step toward the identification of possible aberrations in the activation patterns of patients suffering from visceral hypersensitivity.     

Reproducibility of functional MR imaging results using two different MR systems

BACKGROUND AND PURPOSE: In the application of functional MR imaging for presurgical planning, high reproducibility is required. We investigated whether the reproducibility of functional MR imaging results in healthy volunteers depended on the MR system used. METHODS: Visual functional MR imaging reproducibility experiments were performed with 12 subjects, by using two comparable 1.5-T MR systems from different manufacturers. Each session consisted of two runs, and each subject underwent three sessions, two on one system and one on the other. Reproducibility measures D (distance in millimeters) and R(size) and R(overlap) (ratios) were calculated under three conditions: same session, which compared runs from one session; intersession, which compared runs from different sessions but from the same system; and intermachine, which compared runs from the two different systems. The data were averaged per condition and per system, and were compared. RESULTS: The average same-session values of the reproducibility measures did not differ significantly between the two systems. The average intersession values did not differ significantly as to the volume of activation (R(size)), but did differ significantly as to the location of this volume (D and R(overlap)). The average intermachine reproducibility did not differ significantly from the average intersession reproducibility of the MR system with the worst reproducibility. CONCLUSION: The location of activated voxels from visual functional MR imaging experiments varied more between sessions on one MR system than on other MR system. The amount of the activated voxels is independent of the MR system used. We suggest that sites performing functional MR imaging for presurgical planning measure the intersession reproducibility to determine an accurate surgical safety margin.     

Anatomic validation of spatial normalization methods for PET.

Spatial normalization methods, which are indispensable for intersubject analysis in current PET studies, have been improved in many aspects. These methods have not necessarily been evaluated as anatomic normalization methods because PET images are functional images. However, in view of the close relation between brain function and morphology, it is very intriguing how precisely normalized brains coincide with each other. In this report, the anatomic precision of spatial normalization is validated with three different methods. METHODS: Four PET centers in Japan participated in this study. In each center, six normal subjects were recruited for both H2(15)O-PET and high-resolution MRI studies. Variations in the location of the anterior commissure (AC) and size and contours of the brain and the courses of major sulci were measured in spatially normalized MR images for each method. Spatial normalization was performed as follows. (a) Linear: The AC-posterior commissure and midsagittal plane were identified on MRI and the size of the brain was adjusted to the Talairach space in each axis using linear parameters. (b) Human brain atlas (HBA): Atlas structures were manually adjusted to MRI to determine linear and nonlinear transformation parameters and then MRI was transformed with the inverse of these parameters. (c) Statistical parametric mapping (SPM) 95: PET images were transformed into the template PET image with linear and nonlinear parameters in a least-squares manner. Then, coregistered MR images were transformed with the same parameters used for the PET transformation. RESULTS: The AC was well registered in all methods. The size of the brain normalized with SPM95 varied to a greater extent than with other approaches. Larger variance in contours was observed with the linear method. Only SPM95 showed significant superiority to the linear method when the courses of major sulci were compared. CONCLUSION: The results of this study indicate that SPM95 is as effective a spatial normalization as HBA, although it does not use anatomic images. Large variance in structures other than the AC and size of the brain in the linear method suggests the necessity of nonlinear transformations for effective spatial normalization. Operator dependency of HBA also must be considered.     

Mapping of the sensorimotor cortex: functional MR and magnetic source imaging.

PURPOSETo assess the reliability and comparability of functional MR imaging and magnetic source imaging for mapping the somatosensory cortex.METHODSParallel studies were performed in eight volunteer subjects in whom both hemispheres were measured with the use of painless tactile stimulation of the tip of each index finger. Magnetic source imaging was performed using a 37-channel biomagnetometer; evoked magnetic fields were analyzed using the single-equivalent dipole representation to ascertain the neuronal source. Functional MR imaging was performed on a 1.5-T MR unit. Blocks of images during periods of rest and activation were acquired using gradient-echo echo-planar imaging. Correlation analysis identified pixels in which signal intensity correlated with the stimulus function. A subsequent requirement for spatial connectivity of activation was imposed to reduce the random occurrence of pixels satisfying the correlation criteria.RESULTSUsing temporal and spatial statistical criteria for activation, we found that functional MR imaging showed activation in 1 of 16 hemispheres. In three cases, this was accompanied by activity either frontally or ipsilateral to the stimulus. Magnetic source imaging showed parietal contralateral location in all 16 cases. Where successful localization was achieved with both methods, the separation between sources appeared to be between 1 and 4 cm. Functional MR imaging localizations tended to lie more superficially than the magnetic source imaging localizations. Performance of a simple motor task, rather than use of somatosensory stimulation, resulted in a cortical signal change detectable with a similar functional MR imaging approach in all cases, suggesting the more robust nature of this stimulus.CONCLUSIONSFunctional mapping of the somatosensory cortex can be achieved with functional MR imaging or magnetic source imaging. Functional MR imaging yields more spurious locations and fails to show localization more often. If neuronal signal propagation pathways are of interest, the temporal resolution of functional MR imaging alone may be inadequate. A combination of magnetic source imaging and functional MR imaging may allow improved sensitivity, fewer false-positive results, and high spatial and temporal resolution.     

Quantification and reproducibility of tracking cortical extent of activation by use of functional MR imaging and magnetoencephalography

BACKGROUND AND PURPOSE: Functional MR imaging and magnetoencephalography are commonly used to study normal cortical sensory and cognitive processing as well as a variety of disease states. The usefulness of these techniques is dependent on the reproducibility and sensitivity to change of derived measures of brain function. The purpose of this study was to compare the efficacy of functional MR imaging and magnetoencephalography as measures of the extent of cortical activity in response to a graded stimulus. METHODS: Five participants underwent functional MR imaging and magnetoencephalography involving stimulation of one, two, three, and four digits of the left hand. Measurements of activation were repeated three times per participant. The cortical extent of activation was assessed for functional MR imaging by observing the number of "activated" pixels and the "amount of activation": the product of the number of activated pixels and the mean signal change. Activation was quantified for magnetoencephalography as the magnitude of the evoked magnetic field peak and as the strength of the modeled current source, Q. RESULTS: For functional MR imaging, the number of activated pixels tended to increase with the increasing number of stimulated digits. High intra- and interparticipant variability (66% and 85% variation, respectively) did not, however, allow statistical resolution of this trend. The amount of activation was similarly variable (interparticipant, 89%). Magnetoencephalography was more robust regarding quantification. The evoked field amplitude varied linearly with the number of digits stimulated; intra- and interparticipant variability was 18% and 41%, respectively, permitting resolution of significant differences between any combination of stimulated digits, except two versus three (P < .05). CONCLUSION: Although functional MR imaging and magnetoencephalography show measurable evoked responses with somatosensory stimulation, in this study, functional MR imaging did not permit robust quantification of increasing cortical areas of activation.     

Comparison of fMRI coregistration results between human experts and software solutions in patients and healthy subjects

Functional magnetic resonance imaging (fMRI) performed by echo-planar imaging (EPI) is often highly distorted, and it is therefore necessary to coregister the functional to undistorted anatomical images, especially for clinical applications. This pilot study provides an evaluation of human and automatic coregistration results in the human motor cortex of normal and pathological brains. Ten healthy right-handed subjects and ten right-handed patients performed simple right hand movements during fMRI. A reference point chosen at a characteristic anatomical location within the fMRI sensorimotor activations was transferred to the high resolution anatomical MRI images by three human fMRI experts and by three automatic coregistration programs. The 3D distance between the median localizations of experts and programs was calculated and compared between patients and healthy subjects. Results show that fMRI localization on anatomical images was better with the experts than software in 70% of the cases and that software performance was worse for patients than healthy subjects (unpaired t-test: P = 0.040). With 45.6 mm the maximum disagreement between experts and software was quite large. The inter-rater consistency was better for the fMRI experts compared to the coregistration programs (ANOVA: P = 0.003). We conclude that results of automatic coregistration should be evaluated carefully, especially in case of clinical application.     

Real-time reconstruction and high-speed processing in functional MR imaging.

Access to fully processed activation maps in near real time during a functional MR examination enables run-to-run assessment of results. This is particularly useful in clinical studies, since the results of the functional MR examination can be ascertained before the patient leaves the MR suite, permitting interactive tailoring of the functional MR study. We describe how a real-time MR system can be customized to complete the following tasks in less than 3 minutes: obtain an 81-second acquisition of a multisection functional MR imaging time series using single-shot echo-planar imaging, perform image reconstruction, extract functional MR activation maps using cross-correlation and thresholding, and superimpose activation maps on previously acquired T1-weighted anatomic images.     

Functional MR Imaging of Vision in the Deaf

RATIONALE AND OBJECTIVES: Early loss of a sensory modality has been associated with cortical reorganization in both animal models and humans. The purpose of this study was to map visual activation with functional magnetic resonance (MR) imaging and to document possible developmental reorganization in the temporal lobe caused by early deafness. MATERIALS AND METHODS: Six prelingual, profoundly deaf subjects were compared with a similar group of six hearing subjects. Three visual tasks were performed by both groups: attention to movement in the field-of-view periphery, shape matching, and mental rotation. Echo-planar coronal MR imaging was performed at 1.5 T. RESULTS: Regions of interest encompassing the middle and posterior aspects of the superior and middle temporal gyri demonstrated a significantly (P < .05) increased activation in deaf subjects compared with hearing subjects, particularly on the right side (P < .05) and during the tasks involving motion. The most specific effect was noted during the mental-rotation task. CONCLUSION: These results support the hypothesis that portions of the temporal lobe usually involved in auditory processing are more active during certain visual tasks in deaf compared with hearing subjects. Cortical reorganization may be an important factor in the deaf population when considering the physiology of temporal lobe lesions and predicting surgical outcomes. Functional MR imaging may be helpful during preoperative assessment in individuals with deafness.     

Parkinson disease: pattern of functional MR imaging activation during deep brain stimulation of subthalamic nucleus--initial experience

PURPOSE: To prospectively determine the pattern of functional magnetic resonance (MR) imaging activation at 3 T produced by deep brain stimulation (DBS) of subthalamic nucleus (STN) for treatment of Parkinson disease and to determine the safety of DBS electrode stimulation during functional MR imaging at 3 T. MATERIALS AND METHODS: Informed consent was obtained from all subjects participating in the study, and the study protocol was approved by the institutional review board at the Cleveland Clinic Foundation and was HIPAA compliant. After extensive phantom safety testing of DBS lead systems, five patients (three men, two women; mean age, 49.4 years +/- 14.5 [standard deviation]; range, 31-74 years) with percutaneously extended bilateral DBS electrodes placed in the STN for treatment of Parkinson disease were examined at 3 T on the 1st or 2nd postoperative day. Imaging consisted of a three-dimensional anatomic data set with leads disconnected and a blood oxygen level-dependent functional MR image with a single lead connected to the external pulse generator in the MR imaging control room by using stimulation parameters previously determined to produce optimal stimulation for alleviation of symptoms. A total of nine leads were tested with the functional MR imaging protocol. Subjects underwent neurologic examination immediately before and after MR imaging. RESULTS: All five patients completed the study without change in their neurologic examination and with activation seen in eight of nine electrodes stimulated. Activation was seen in the ipsilateral basal ganglia in all subjects and ipsilateral thalamus in six of the electrodes tested. Two of the electrode stimulations demonstrated additional activation in the STN and/or substantia nigra region adjacent to the electrode tip. For three electrode stimulations, activation was seen in the contralateral superior cerebellum. CONCLUSION: Therapeutically effective DBS of STN can be performed safely during functional MR imaging at 3 T and produces a consistent pattern of ipsilateral activation of deep brain motor structures.     

Cervical degenerative disease at flexion-extension MR imaging: prediction criteria

PURPOSE: To determine if there are any neutral-position imaging criteria that can help predict functional cord impingement at flexion-extension cervical magnetic resonance (MR) imaging. MATERIALS AND METHODS: Sixty-two patients with cervical degenerative disease were evaluated with regard to the dynamic changes of canal stenosis at flexion-extension MR imaging. Functional cord impingement was considered if the cord was impinged or more impinged after neck flexion or extension. Selection criteria for neutral-position MR imaging, such as cervical curvature, canal space, degenerative stage, intramedullary high signal intensity on T2-weighted images, and resting instability, were evaluated for their ability to predict functional cord impingement at flexion-extension MR imaging (Fisher exact test, logistic regression analysis). RESULTS: MR images in 19 (31%) of 62 patients showed functional cord impingement at extension MR imaging compared with images in two (3%) patients at flexion MR imaging. Statistically significant differences were found for the criteria cervical degeneration stage (P <.001) and spinal canal space (P =.037) for predicting functional cord impingement at extension MR imaging. In contrast, no significant differences were found among selection criteria for flexion MR imaging. Probabilities of functional cord impingement at extension MR imaging were calculated with different combinations of degenerative stages and canal spaces. Probability could increase to 79% if the patient had both stabilization degeneration (disk protrusion or osteophytic formation with hypertrophy of the ligamentum flavum) and C7 canal space of 10 mm or less. CONCLUSION: None of the selection criteria evaluated in this study has the ability to predict functional cord impingement at flexion MR imaging; however, prediction of impingement at extension MR imaging can increase from 31% to 79% if proper criteria are selected.     

Female genitalia: dynamic MR imaging with use of MS-325 initial experiences evaluating female sexual response

PURPOSE: To determine whether magnetic resonance (MR) imaging with MS-325, a recently developed blood pool contrast agent, can depict sexual arousal response in healthy women. MATERIALS AND METHODS: Serial MR imaging of the external genitalia was performed in 12 healthy sexually functional women before and after administration of MS-325. MR images were obtained every 3 minutes during a 45-minute examination. During the examination, the subjects viewed neutral and erotic video material while they were in the magnet bore. MR image analysis at each interval consisted of vaginal wall, vaginal mucosa, and clitoris assessments; femoral vein signal intensity measurements; relative regional blood volume (rRBV) calculations; and clitoral volume measurements. Statistical analysis of the results was performed with a t test. RESULTS: On subjective questionnaires, all subjects in the test group reported being sexually aroused. MS-325-enhanced MR images showed strong contrast enhancement of the external genitalia. The rRBV in the glans clitoris of seven of 10 subjects and in the clitoral body of eight of these subjects increased significantly (P <.05) during erotic visual stimulation. All 10 subjects had a significant (P <.05) increase in clitoral size. There were no significant differences in any measures between the pre- and postmenopausal study groups. CONCLUSION: The sexual arousal response in healthy women can be monitored at serial MR imaging with MS-325. This examination holds promise for future studies of sexual arousal dysfunction in women.     

Use of functional MR to map language in multilingual volunteers.

PURPOSETo use functional MR imaging to compare brain activation during processing of languages in which multilingual volunteers are fluent with brain activation during processing of languages in which they are not fluent.METHODSEchoplanar images were obtained for five right-handed male multilingual subjects who performed a language task in three languages, one of which was a language in which the subject was not fluent. The functional MR technique included echoplanar images obtained at 1 per second during cycles of rest and performance of the task, from which functional images were processed by means of cross-correlation analysis. The numbers of active pixels in each volunteer and for each language were compared.RESULTSActivation was noted in the left frontal lobe in all subjects performing language tasks. In each subject, the number of activated pixels was greatest for the language in which the subject was least fluent.CONCLUSIONFunctional MR imaging shows differences in the processing of different languages in multilingual volunteer subjects, depending on the level of fluency in the language, and it is an effective functional imaging method for studying the processing of different languages.