Fast susceptibility-weighted imaging with three-dimensional short-axis propeller (SAP)-echo-planar imaging.

BACKGROUND: Susceptibility-weighted imaging (SWI) in neuroimaging can be challenging due to long scan times of three-dimensional (3D) gradient recalled echo (GRE), while faster techniques such as 3D interleaved echo-planar imaging (iEPI) are prone to motion artifacts. Here we outline and implement a 3D short-axis propeller echo-planar imaging (SAP-EPI) trajectory as a faster, motion-correctable approach for SWI. METHODS: Experiments were conducted on a 3T MRI system. The 3D SAP-EPI, 3D iEPI, and 3D GRE SWI scans were acquired on two volunteers. Controlled motion experiments were conducted to test the motion-correction capability of 3D SAP-EPI. The 3D SAP-EPI SWI data were acquired on two pediatric patients as a potential alternative to 2D GRE used clinically. RESULTS: The 3D GRE images had a better target resolution (0.47 × 0.94 × 2 mm, scan time = 5 min), iEPI and SAP-EPI images (resolution = 0.94 × 0.94 × 2 mm) were acquired in a faster scan time (1:52 min) with twice the brain coverage. SAP-EPI showed motion-correction capability and some immunity to undersampling from rejected data. CONCLUSION: While 3D SAP-EPI suffers from some geometric distortion, its short scan time and motion-correction capability suggest that SAP-EPI may be a useful alternative to GRE and iEPI for use in SWI, particularly in uncooperative patients.

Clinical Feasibility of Ultrafast Contrast-Enhanced T1-Weighted 3D-EPI for Evaluating Intracranial Enhancing Lesions in Oncology Patients: Comparison with Standard 3D MPRAGE Sequence.

BACKGROUND AND PURPOSE: Contrast-enhanced 3D T1WI is a preferred sequence for brain tumor imaging despite the long scan time. This study investigated the clinical feasibility of ultrafast contrast-enhanced T1WI by 3D echo-planar imaging compared with a standard contrast-enhanced 3D MPRAGE sequence for evaluating intracranial enhancing lesions in oncology patients. MATERIALS AND METHODS: Sixty-one patients in oncology underwent brain MR imaging including both contrast-enhanced T1WI, 3D-EPI and 3D MPRAGE, in a single examination session for evaluating intracranial tumors. Two neuroradiologists evaluated image quality, lesion conspicuity, diagnostic confidence, number and size of the lesions, and contrast-to-noise ratio measurements from the 2 different sequences. RESULTS: Ultrafast 3D-EPI T1WI did not reveal significant differences in diagnostic confidence, contrast-to-noise ratiolesion/parenchyma, and the number of enhancing lesions compared with MPRAGE (P > .05). However, ultrafast 3D-EPI T1WI revealed inferior image quality, inferior anatomic delineation and greater susceptibility artifacts with fewer motion artifacts than images obtained with MPRAGE. The mean contrast-to-noise ratioWM/GM and visual conspicuity of the lesion on ultrafast 3D-EPI T1WI were lower than those of MPRAGE (P < .001). CONCLUSIONS: Ultrafast 3D-EPI T1WI showed comparable diagnostic performance with sufficient image quality and a 7-fold reduction in scan time for evaluating intracranial enhancing lesions compared with standard MPRAGE, even though it was limited by an inferior image quality and frequent susceptibility artifacts. Therefore, we believe that ultrafast 3D-EPI T1WI may be a viable option in oncology patients prone to movement during imaging studies.

Clinical Experience of 1-Minute Brain MRI Using a Multicontrast EPI Sequence in a Different Scan Environment.

BACKGROUND AND PURPOSE: The long scan time of MR imaging is a major drawback limiting its clinical use in neuroimaging; therefore, we aimed to investigate the clinical feasibility of a 1-minute full-brain MR imaging using a multicontrast EPI sequence on a different MR imaging scanner than the ones previously reported. MATERIALS AND METHODS: We retrospectively reviewed the records of 146 patients who underwent a multicontrast EPI sequence, including T1-FLAIR, T2-FLAIR, T2WI, DWI, and T2*WI sequences. Two attending neuroradiologists assessed the image quality of each sequence to compare the multicontrast EPI sequence with routine MR imaging protocols. We used the Wilcoxon signed rank test and McNemar test to compare the 2 MR imaging protocols. RESULTS: The multicontrast EPI sequence generally showed sufficient image quality of >2 points using a 4-point assessment scale. Regarding image quality and susceptibility artifacts, there was no significant difference between the multicontrast EPI sequence DWI and routine DWI (P > .05), attesting to noninferiority of the multicontrast EPI, whereas there were significant differences in the other 4 sequences between the 2 MR imaging protocols. CONCLUSIONS: The multicontrast EPI sequence showed sufficient image quality for clinical use with a shorter scan time; however, it was limited by inferior image quality and frequent susceptibility artifacts compared with routine brain MR imaging. Therefore, the multicontrast EPI sequence cannot completely replace the routine MR imaging protocol at present; however, it may be a feasible option in specific clinical situations such as screening, time-critical diseases or for use with patients prone to motion.

A review of GHRH stimulation test in psychiatry.

We critically reviewed controlled investigations of the growth hormone releasing hormone (GHRH) stimulation test in depression, anorexia nervosa, bulimia, panic disorder, schizophrenia, and Alzheimer's disease. Comparisons of GH responsiveness between patients and controls within each diagnostic category were equivocal and in some cases contradictory. Factors that may contribute substantially to the inconsistent findings within diagnostic categories include (1) the variability of GHRH-simulated GH among control groups; (2) the lack of uniformity in test procedures and outcome measures; and (3) the age and gender of subjects. In addition, the individual reproducibility of the GHRH stimulation test has not been adequately investigated and until the test's stability within subjects can be determined, the validity of interpretations resulting from the GHRH simulation test are in question.

Intrasubject reproducibility of growth hormone-releasing hormone-stimulated growth hormone in older women, older men, and younger men.

Intrasubject reproducibility of growth hormone (GH) response to growth hormone-releasing hormone (GHRH) was studied in healthy older women (n = 9), older men (n = 8), and younger men (n = 10). Subjects received IV injections of 0.1 ml/kg saline, 1 micrograms/kg GHRH, and 2 micrograms/kg GHRH, three times each, and blood was sampled at 0, 15, 30, 45, 60, and 120 min for GH concentration. There was no significant difference in peak GH response between the 1- and 2-micrograms/kg GHRH dosages. GH responsiveness, group variance of peak GH, and intrasubject variability were greatest for younger men, less for older men, and least for older women at both dosages of GHRH. Because of the large intrasubject variability observed in this study, it appears necessary to test subjects more than once to obtain a valid characterization of GH responsiveness.

Milacemide: a placebo-controlled study in senile dementia of the Alzheimer type.

OBJECTIVE: Milacemide, a MAO-B inhibitor that is also a prodrug for glycine, was tested as a treatment for senile dementia of the Alzheimer type (SDAT) because of its potential for enhancing cognition in animal models of impaired learning and memory. DESIGN: Double-blind, placebo-controlled, randomized clinical trial. SETTING: Sixteen study sites, both university-affiliated and private. PATIENTS: A total of 228 outpatients (116 men and 112 women) with SDAT, ranging in age from 49-93 years. INTERVENTION: 1200 mg/day milacemide treatment for 1 month (113 patients received milacemide, and 115 patients received placebo). MAIN OUTCOME MEASURES: Alzheimer's Disease Assessment Scale and the Mini-Mental State Examination. RESULTS: Milacemide-treated SDAT patients did not show significant improvement in any of the outcome measures used. Significant elevations in liver enzymes in four subjects were of sufficient magnitude to necessitate withdrawal from the study. CONCLUSIONS: Milacemide does not appear to be an effective treatment in enhancing cognition in SDAT patients.

Abnormal brain white matter in schizophrenia: a diffusion tensor imaging study.

Fractional anisotropy and the mean diffusion coefficient were measured in the cerebral volume in 20 schizophrenic and 24 healthy subjects, men and women, using diffusion tensor imaging. In addition, 3D SPGR was used for segmentation of brain tissue into grey and white matter and cerebrospinal fluid. In schizophrenic patients, fractional anisotropy was reduced in the splenium of the corpus callosum and in adjacent occipital white matter. The segmentation revealed no tissue deficits in the volume of reduced fractional anisotropy. The mean diffusion was increased in the total white and grey matter volume of the schizophrenic patients compared with the healthy subjects. The findings support the view that global and regional white matter abnormalities occur in chronic schizophrenia.

Distribution of peripheral lymphocytes in Alzheimer patients and controls.

Deficient immunoregulation has been postulated to play a role in the pathogenesis of Alzheimer's dementia. Recently, lymphopenia was reported to be more prevalent in Alzheimer patients than in control subjects. In addition, a decreasing number of total lymphocytes was found to be significantly correlated with increasing severity of dementia. In an attempt to replicate these findings, we studied 55 Alzheimer patients and 41 healthy controls of comparable age and gender, but found no significant difference in the distribution of total lymphocytes between these groups. Furthermore, total lymphocytes were not significantly correlated with dementia severity. Our findings, therefore, do not lend further support to an immune hypothesis for Alzheimer's dementia.

Performance of two forms of a computer psychiatric screening interview: version I of the DISSI.

This study reports on the performance of two forms of version I of the Diagnostic Interview Schedule (DIS) computer screening interview, using the traditional interviewer-administered DIS (T-DIS) as the standard. The screening interview was either self-administered (called the S-DISSI) with the subject keying in responses, or interviewer-administered (I-DISSI), with the interviewer keying in the subject's responses. Sensitivity and specificity for both forms were ample (excluding antisocial personality), ranging from 60% to 100% for sensitivity and 54% to 95% for specificity. Concordances with the T-DIS were similar for both forms of the screening interview, ranging from .10 to .87 and compared favorably to those reported by other investigators. The I-DISSI took on average 30 min less than either the T-DIS and S-DISSI. Since the performances of both versions were equivalent, the decision to use either may be based on available resources and characteristics of the study population.

A comparison of two computer-administered versions of the NIMH Diagnostic Interview Schedule.

This study compared three versions of the NIMH Diagnostic Interview Schedule (DIS): "traditional" interviewer-administered DIS; computer-administered DIS (subject interacting alone with computer); computer-prompted DIS (interviewer using computer program as a guide). Kappas for 20 diagnoses ranged from .15 to .94, and averages for the three method pairs ranged from .57 to .64, which are comparable to other DIS reliability studies. Agreement between pairs of methods were comparable. Subjects' attitudes toward the computer interview were positive. While they felt they could better describe their feelings and ideas to a human, they found the computer contact less embarrassing. Overall, subjects had no preference for one method over another. Measures of social desirability and deviant response biases were correlated with diagnostic results. Reading ability did not affect subject's ability to respond to the DIS, although subjects with lower reading levels preferred the computer interview more.

Condition number as a measure of noise performance of diffusion tensor data acquisition schemes with MRI.

Diffusion tensor mapping with MRI can noninvasively track neural connectivity and has great potential for neural scientific research and clinical applications. For each diffusion tensor imaging (DTI) data acquisition scheme, the diffusion tensor is related to the measured apparent diffusion coefficients (ADC) by a transformation matrix. With theoretical analysis we demonstrate that the noise performance of a DTI scheme is dependent on the condition number of the transformation matrix. To test the theoretical framework, we compared the noise performances of different DTI schemes using Monte-Carlo computer simulations and experimental DTI measurements. Both the simulation and the experimental results confirmed that the noise performances of different DTI schemes are significantly correlated with the condition number of the associated transformation matrices. We therefore applied numerical algorithms to optimize a DTI scheme by minimizing the condition number, hence improving the robustness to experimental noise. In the determination of anisotropic diffusion tensors with different orientations, MRI data acquisitions using a single optimum b value based on the mean diffusivity can produce ADC maps with regional differences in noise level. This will give rise to rotational variances of eigenvalues and anisotropy when diffusion tensor mapping is performed using a DTI scheme with a limited number of diffusion-weighting gradient directions. To reduce this type of artifact, a DTI scheme with not only a small condition number but also a large number of evenly distributed diffusion-weighting gradients in 3D is preferable.

The dexamethasone suppression test in dementia: a review of the literature.

To examine the utility of the dexamethasone suppression test (DST) in the differential diagnosis of depression in elderly demented patients, we reviewed the literature and focused on four components of this question: (1) cortisol nonsuppression rates in dementia; (2) cortisol nonsuppression and dementia severity; (3) cortisol nonsuppression in demented versus depressed patients; and (4) cortisol nonsuppression following antidepressant treatment. A combined analysis of 27 articles showed cortisol nonsuppression in 60% of patients with concurrent dementia and depression, in 47% of patients with depression only, in 41% of patients with dementia only, in 46% of patients with multi-infarct dementia, in 36% of patients with primary degenerative dementia, and in 10% of controls. The abnormal DST rate in demented patients was not significantly different from the abnormal DST rate in depressed patients. Eight of 12 studies (67%) did not find a significant relationship between DST results and dementia severity dementia patients without depression. Twelve of 13 studies (92%) did not find a relationship between age and DST outcome. The data we reviewed do not support the use of the DST in discriminating between depression and dementia or between dementia subtypes.

On the effects of gating in diffusion imaging of the brain using single shot EPI.

To reduce image artifacts in diffusion tensor imaging using single shot EPI, cardiac gating may be performed to prevent brain motion induced signal void in the DWI data. In this work the necessity of performing cardiac gating with single shot echo planar imaging has been explored using F statistics of the variance in DWI data. Peripheral measurement of the cardiac cycle has been employed because of its greater convenience, and hence use, compared to ECG gating. Four volunteers have been studied. Six different trigger delays have been evaluated in the range 18-500 ms relative the peripheral pulse wave. Brain motion was found significant in and inferior to the corpus callosum area. A trigger delay of 500 ms was found to be optimal. However, a long delay allows only for one slice per R-R interval. Therefore, a minimum trigger delay may be the best choice in terms of SNR per unit of experiment time.

Noise considerations in the determination of diffusion tensor anisotropy.

In this study the noise sensitivity of various anisotropy indices has been investigated by Monte-Carlo computer simulations and magnetic resonance imaging (MRI) measurements in a phantom and 5 healthy volunteers. Particularly, we compared the noise performance of indices defined solely in terms of eigenvalues and those based on both the eigenvalues and eigenvectors. It is found that anisotropy indices based on both eigenvalues and eigenvectors are less sensitive to noise, and spatial averaging with neighboring pixels can further reduce the standard deviation. To reduce the partial volume effect caused by the spatial averaging with neighboring voxels, an averaging method in the time domain based on the orientation coherence of eigenvectors in repeated experiments has been proposed.

School-based secondary prevention for children with disruptive behavior: initial outcomes.

First through fourth graders from 22 suburban elementary schools were screened for cross-setting disruptive behavior as eligibility criteria for participation in a longitudinal secondary prevention study aimed at reducing the risk for serious externalizing behavioral disorders. Three hundred nine subjects participated in either a multicomponent competence enhancement intervention (MCEI) or an information/attention control (IAC) condition over a 2-year period. Following baseline requirements, initial intervention effects were assessed at the end of intervention Year 1, at the beginning of intervention Year 2 (fall of the next school year), and at the end of intervention Year 2. Multisource assessments were not supportive of the efficacy of the MCEI over the IAC condition. Children in both groups rated themselves as improved over time in terms of increased adaptive skills and decreased school problems and internalizing symptoms. Teacher and parent ratings of externalizing behavior did not yield evidence of positive change, but teachers noted improved problem solving and observers noted a decrease in behavioral interference in both groups over time, possibly as a result of maturation.

Diffusion-weighted imaging with dual-echo echo-planar imaging for better sensitivity to acute stroke.

BACKGROUND AND PURPOSE: Parallel imaging facilitates the acquisition of echo-planar images with a reduced TE, enabling the incorporation of an additional image at a later TE. Here we investigated the use of a parallel imaging-enhanced dual-echo EPI sequence to improve lesion conspicuity in diffusion-weighted imaging. MATERIALS AND METHODS: Parallel imaging-enhanced dual-echo DWI data were acquired in 50 consecutive patients suspected of stroke at 1.5T. The dual-echo acquisition included 2 EPI for 1 diffusion-preparation period (echo 1 [TE = 48 ms] and echo 2 [TE = 105 ms]). Three neuroradiologists independently reviewed the 2 echoes by using the routine DWI of our institution as a reference. Images were graded on lesion conspicuity, diagnostic confidence, and image quality. The apparent diffusion coefficient map from echo 1 was used to validate the presence of acute infarction. Relaxivity maps calculated from the 2 echoes were evaluated for potential complementary information. RESULTS: Echo 1 and 2 DWIs were rated as better than the reference DWI. While echo 1 had better image quality overall, echo 2 was unanimously favored over both echo 1 and the reference DWI for its high sensitivity in detecting acute infarcts. CONCLUSIONS: Parallel imaging-enhanced dual-echo diffusion-weighted EPI is a useful method for evaluating lesions with reduced diffusivity. The long TE of echo 2 produced DWIs that exhibited superior lesion conspicuity compared with images acquired at a shorter TE. Echo 1 provided higher SNR ADC maps for specificity to acute infarction. The relaxivity maps may serve to complement information regarding blood products and mineralization.

Clinical assessment of standard and generalized autocalibrating partially parallel acquisition diffusion imaging: effects of reduction factor and spatial resolution.

BACKGROUND AND PURPOSE: PI improves routine EPI-based DWI by enabling higher spatial resolution and reducing geometric distortion, though it remains unclear which of these is most important. We evaluated the relative contribution of these factors and assessed their ability to increase lesion conspicuity and diagnostic confidence by using a GRAPPA technique. MATERIALS AND METHODS: Four separate DWI scans were obtained at 1.5T in 48 patients with independent variation of in-plane spatial resolution (1.88 mm(2) versus 1.25 mm(2)) and/or reduction factor (R = 1 versus R = 3). A neuroradiologist with access to clinical history and additional imaging sequences provided a reference standard diagnosis for each case. Three blinded neuroradiologists assessed scans for abnormalities and also evaluated multiple imaging-quality metrics by using a 5-point ordinal scale. Logistic regression was used to determine the impact of each factor on subjective image quality and confidence. RESULTS: Reference standard diagnoses in the patient cohort were acute ischemic stroke (n = 30), ischemic stroke with hemorrhagic conversion (n = 4), intraparenchymal hemorrhage (n = 9), or no acute lesion (n = 5). While readers preferred both a higher reduction factor and a higher spatial resolution, the largest effect was due to an increased reduction factor (odds ratio, 47 ± 16). Small lesions were more confidently discriminated from artifacts on R = 3 images. The diagnosis changed in 5 of 48 scans, always toward the reference standard reading and exclusively for posterior fossa lesions. CONCLUSIONS: PI improves DWI primarily by reducing geometric distortion rather than by increasing spatial resolution. This outcome leads to a more accurate and confident diagnosis of small lesions.

Clinical application of readout-segmented- echo-planar imaging for diffusion-weighted imaging in pediatric brain.

BACKGROUND AND PURPOSE: RS-EPI has been suggested as an alternative approach to EPI for high-resolution DWI with reduced distortions. To determine whether RS-EPI is a useful approach for routine clinical use, we implemented GRAPPA-accelerated RS-EPI DWI at our pediatric hospital and graded the images alongside standard accelerated (ASSET) EPI DWI used routinely for clinical studies. MATERIALS AND METHODS: GRAPPA-accelerated RS-EPI DWIs and ASSET EPI DWIs were acquired on 35 pediatric patients using a 3T system in 35 pediatric patients. The images were graded alongside each other by using a 7-point Likert scale as follows: 1, nondiagnostic; 2, poor; 3, acceptable; 4, standard; 5, above average; 6, good; and 7, outstanding. RESULTS: The following were the average scores for EPI and RS-EPI, respectively: resolution, 3.5/5.2; distortion level, 2.9/6.0; SNR, 3.4/4.1; lesion conspicuity, 3.3/5.9; and diagnostic confidence, 3.2/6.0. Overall, the RS-EPI had significantly improved diagnostic confidence and more reliably defined the extent and structure of several lesions. Although ASSET EPI scans had better SNR per scanning time, the higher spatial resolution as well as reduced blurring and distortions on RS-EPI scans helped to better reveal important anatomic details at the cortical-subcortical levels, brain stem, temporal and inferior frontal lobes, skull base, sinonasal cavity, cranial nerves, and orbits. CONCLUSIONS: This work shows the importance of both resolution and decreased distortions in the clinics, which can be accomplished by a combination of parallel imaging and alternative k-space trajectories such as RS-EPI.

Correction of MR image distortions induced by metallic objects using a 3D cubic B-spline basis set: application to stereotactic surgical planning.

Metallic implants in MRI cause spin-echo (SE) images to be distorted in the slice and frequency-encoding directions. Chang and Fitzpatrick (IEEE Trans Med Imaging 1992;11:319-329) proposed a distortion correction method (termed the CF method) based on the magnitude images from two SE acquisitions that differ only in the polarity of the frequency-encoding and slice-selection gradients. In the present study we solved some problems with the CF method, primarily by modeling the field inhomogeneities as a single 3D displacement field built by 3D cubic B-splines. The 3D displacement field was applied in the actual distortion direction in the slice/frequency-encoding plane. To account for patient head motion, a 3D rigid body motion correction was also incorporated in the model. Experiments on a phantom containing an aneurysm clip showed that the knot spacing between the B-splines is a very important factor in both the final image quality and the processing speed. Depending on the knot spacing and the image volume size, the number of unknowns range from a few thousands to over 100,000, leading to processing times ranging from minutes to days. Optimal knot spacing, a means of increasing the processing speed, and other parameters are investigated and discussed.

Lack of effect of somatostatin on thyroid gland function in Graves' disease.

Five women with Graves' disease, 26-52 years of age, with serum concentrations of triiodothyronine (T3) 4.8-9.2 nmol/l and thyroxine (T4) 200-320 nmol/l were studied. A 26 h infusion of cyclic somatostatin (Bachem), 6 mg in isotonic saline solution was administered. Radioactive iodine i.v. (125I or 131I) was given immediately after the start of this infusion. Serum T3, T4 and conversion rate (CR% = PBRI: total RI X 100) were determined four times during the infusion, then daily for a week. The same studies, related to an injection of radioiodine, were performed during a control week when no somatostatin was administered. Arginine-stimulated insulin and growth hormone (hGH) concentrations were considerably lowered by the somatostatin infusion. No difference in serum T3, T4 or CR between the week that started with somatostatin infusion and the control week was observed. Twelve-26 h after the somatostatin infusion started, all patients experienced gastrointestinal symptoms, which lasted 2-6 h after somatostatin withdrawal. Somatostatin in the dose given does not inhibit thyroid gland function in Graves' disease.