Resting-state fMRI using passband balanced steady-state free precession

OBJECTIVE: Resting-state functional MRI (rsfMRI) has been increasingly used for understanding brain functional architecture. To date, most rsfMRI studies have exploited blood oxygenation level-dependent (BOLD) contrast using gradient-echo (GE) echo planar imaging (EPI), which can suffer from image distortion and signal dropout due to magnetic susceptibility and inherent long echo time. In this study, the feasibility of passband balanced steady-state free precession (bSSFP) imaging for distortion-free and high-resolution rsfMRI was investigated. METHODS: rsfMRI was performed in humans at 3 T and in rats at 7 T using bSSFP with short repetition time (TR = 4/2.5 ms respectively) in comparison with conventional GE-EPI. Resting-state networks (RSNs) were detected using independent component analysis. RESULTS AND SIGNIFICANCE: RSNs derived from bSSFP images were shown to be spatially and spectrally comparable to those derived from GE-EPI images with considerable intra- and inter-subject reproducibility. High-resolution bSSFP images corresponded well to the anatomical images, with RSNs exquisitely co-localized to the gray matter. Furthermore, RSNs at areas of severe susceptibility such as human anterior prefrontal cortex and rat piriform cortex were proved accessible. These findings demonstrated for the first time that passband bSSFP approach can be a promising alternative to GE-EPI for rsfMRI. It offers distortion-free and high-resolution RSNs and is potentially suited for high field studies.published_or_final_versio

Psychiatric assessment of suicide attempters in Japan: a pilot study at a critical emergency unit in an urban area

<p>Abstract</p> <p>Background</p> <p>The incidence of suicide has increased markedly in Japan since 1998. As psychological autopsy is not generally accepted in Japan, surveys of suicide attempts, an established risk factor of suicide, are highly regarded. We have carried out this study to gain insight into the psychiatric aspects of those attempting suicide in Japan.</p> <p>Methods</p> <p>Three hundred and twenty consecutive cases of attempted suicide who were admitted to an urban emergency department were interviewed, with the focus on psychosocial background and DSM-IV diagnosis. Moreover, they were divided into two groups according to the method of attempted suicide in terms of lethality, and the two groups were compared.</p> <p>Results</p> <p>Ninety-five percent of patients received a psychiatric diagnosis: 81% of subjects met the criteria for an axis I disorder. The most frequent diagnosis was mood disorder. The mean age was higher and living alone more common in the high-lethality group. Middle-aged men tended to have a higher prevalence of mood disorders.</p> <p>Conclusion</p> <p>This is the first large-scale study of cases of attempted suicide since the dramatic increase in suicides began in Japan. The identification and introduction of treatments for psychiatric disorders at emergency departments has been indicated to be important in suicide prevention.</p

Investigating resting-state functional connectivity using passband bSSFP

Electronic Poster Session: Functional MRI (neuro) - Resting State Connectivity: MethodsResting-state functional MRI (rsfMRI) using blood-oxygen-level-dependent (BOLD) contrast has emerged as a valuable become an increasingly important tool for mapping inter and intra-hemispheric connectivity in normal and diseased brains. To date, most rsfMRI studies have exploited blood oxygenation level-dependent (BOLD) contrast using T2*- weighted gradient-echo (GE) EPI, which suffers from signal drops and image distortion due to magnetic susceptibility and inherent long TE. Alternatively, T2/T1- weighted passband balanced SSFP (bSSFP) has been promoted for distortion-free, high spatial resolution task-based functional imaging. In this study, we studied the capability of passband b-SSFP for rsfMRI. Resting-state networks (RSNs) of similar but different spatial and temporal pattern were identified, especially into areas near air sinus. (Abstract by ISMRM)link_to_OA_fulltex

Diffusion-weighted resting-state functional MRI at 3T

Electronic Poster Session: Functional MRI (neuro) - Resting State Connectivity: MethodsResting-state functional MRI (rsfMRI) has emerged as a valuable become an increasingly important tool for mapping inter and intra-hemispheric connectivity in normal and diseased brains. To date, most rsfMRI studies have used T2*-weighted gradient-echo (GE) for the benefit of sensitivity. Theoretically, spin-echo (SE) provides better spatial specificity due to the elimination of static dephasing around macro-vessels. At 3T, the benefit however is limited because of a nearly equal share of undesired intravascular (IV) and well-localized extravascular (EV) contribution from microvasculature. Diffusion gradients induce velocity-dependent phase shifts and thus reduce signal from blood due to inhomogeneous velocities within vessel and presence of vessels with different orientations in a pixel. In this study, we aimed to investigate rsfMRI connectivity at 3T using diffusion-weighted (DW) SE to eliminate IV effect from large vessels. By using interleaving non-DW and DW acquisition, we identified default mode networks with similar but different pattern, spatially and spectrally. (Abstract by ISMRM)link_to_OA_fulltex

Hypodensity of >1/3 middle cerebral artery territory versus Alberta Sroke Programme Early CT Score (ASPECTS): Comparison of two methods of quantitative evaluation of early CT changes in hyperacute ischemic stroke in the community setting

Background - The one third middle cerebral artery territory (1/3 MCA) method and the Alberta Stroke Program Early CT Score (ASPECTS) were used to detect significant early ischemic changes (EIC) on CT brain of acute stroke patients. We sought to compare the reliability of the 2 methods in routine clinical practice. Methods - Eighty consecutive patients admitted to a community hospital in Hong Kong with suspected acute ischemic stroke and a CT brain scan performed within 6 hours of symptom onset were included. Five blinded observers (1 neurologist, 2 general radiologists, and 2 neuroradiologists) independently evaluated the scans, using the ATLANTIS/CT Summit criteria for >1/3 MCA involvement, and ASPECTS ≤7. Kappa statistics were used to determine interobserver agreement. Results - Significant EIC were present in 11.4% of the scans with the 1/3 MCA method, and 19.4% with ASPECTS. For >1/3 MCA involvement, all observers agreed in 57 cases (71%), with moderate interobserver agreement (κ = 0.49). For ASPECTS ≤7, all observers agreed in 34 cases (42%), with fair interobserver agreement (κ = 0.34). After prevalence and bias adjustments, substantial (prevalence-adjusted bias-adjusted κ [PABAK] = 0.74) and moderate (PABAK = 0.44) agreements were found for the 1/3 MCA method and ASPECTS respectively. Conclusions - The 1/3 MCA method was more reliable in detecting significant EIC on CT brain within 6 hours of stroke onset in routine clinical practice, whereas ASPECTS was able to detect significant EIC in a higher proportion of these early scans.link_to_OA_fulltex