3D ASL Research Articles

Assessment of cerebral blood perfusion reserve with acetazolamide using 3D spiral ASL MRI: Preliminary experience in pediatric patients

PurposeTo demonstrate the clinical feasibility of a new non-Cartesian cylindrically-distributed spiral 3D pseudo-continuous arterial spin labeling (pCASL) magnetic resonance imaging (MRI) pulse sequence in pediatric patients in quantifying cerebral blood flow (CBF) response to an acetazolamide (ACZ) vasodilator challenge. Materials and methodsMRI exams were performed on two 3 Tesla Philips Ingenia systems using 32 channel head coil arrays. After local institutional review board approval, the 3D spiral-based pCASL technique was added to a standard brain MRI exam and evaluated in 13 pediatric patients (average age: 11.7±6.4years, range: 1.4–22.2years). All patients were administered ACZ for clinically indicated reasons. Quantitative whole-brain CBF measurements were computed pre- and post-ACZ to assess cerebrovascular reserve. Results3D spiral pCASL data were successfully reconstructed in all 13 cases. In 11 patients, CBF increased 2.8% to 93.2% after administration of ACZ. In the two remaining patients, CBF decreased by 2.4 to 6.0% after ACZ. The group average change in CBF due to ACZ was approximately 25.0% and individual changes were statistically significant (p<0.01) in all patients using a paired t-test analysis. CBF perfusion data were diagnostically useful in supporting conventional MR angiography and clinical findings. Conclusion3D cylindrically-distributed spiral pCASL MRI provides a robust approach to assess cerebral blood flow and reserve in pediatric patients.

PRODROMAL AND NON-PRODROMAL DEMENTIA WITH LEWY BODIES AND ALZHEIMER'S DISEASE: A MULTIMODAL MRI APPROACH

Dementia with Lewy bodies (DLB) is one of the main etiology of dementia after Alzheimer's disease (AD). Brain imaging studies have reported very few data in prodromal dementia with Lewy bodies (MCI-DLB). To focus on an earlier stage of the disease in a differential diagnostic perspective, we aimed to describe patterns of volume, perfusion, and connectivity in prodromal and non-prodromal DLB, and to assess for differences with prodromal and non-prodromal AD. We studied 112 subjects including 41 prodromal DLB patients, 15 DLB patients at the mild stage of dementia (mild-DLB), 14 prodromal AD (MCI-AD), 21 AD patients at the mild stage (mild-AD), and 21 healthy elderly controls (HC). They all underwent T1 3D MPRAGE, Asl (arterial spin labeling), and DTI MRI sequences. Voxel-wise analysis was conducted for grey matter and perfusion. The analysis of DTI consists in extending the general linear model, as implemented in SPM, to tensor images taking into account all information available in the tensor. Significant effects were identified by a correction for multiple comparisons using family-wise error and false discovery rate at p<0.05. MCI-DLB patients showed diminished GM volumes of bilateral insulae, mild-DLB patients of bilateral insulae, claustrum and putamen, MCI-AD patients of hippocampus and parahippocampal gyrus (right predominant), and mild-AD patients of temporal lobes including hippocampi. The areas of hypoperfusion were larger than atrophy, including anterior cingulate and insular areas for MCI-DLB. The areas of modifications of the tensor images included insulae, anterior cingulate and frontal regions in MCI-DLB. Using three different MRI approach, we found in all cases modifications of the insulae in DLB patients, at the stage of MCI but also mild dementia. Our results supplement previous reports by describing these early abnormalities and supports the role of insula in DLB at the early stages. Moreover it seems that focal atrophy in insula has distant consequences in MCI-DLB patients as seen in perfusion, and is the reflect of probable more diffuse lesions according to the tensor images. The next step is to better understand what is the link of these results with symptoms of DLB such as hallucinations, fluctuations, cognition, and neurovegetative symptoms.

Cerebellar microstructural abnormalities in bipolar depression and unipolar depression: A diffusion kurtosis and perfusion imaging study

BackgroundDepression in the context of bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in cerebellum between BD and UD. MethodsPatients with BD (n=35) and UD (n=30) during a depressive episode as well as 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The DKI parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr),fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr) and 3D ASL parameters (i.e. cerebral blood flow) was measured by using regions-of-interest (ROIs) analysis in the superior cerebellar peduncles (SCP), middle cerebellar peduncles (MCP) and dentate nuclei (DN) of cerebellum. ResultsPatients with UD exhibited significant differences from controls for DKI measures in bilateral SCP and MCP and cerebral blood flow (CBF) in bilateral SCP and left DN. Patients with BD exhibited significant differences from controls for DKI measures in the right MCP and left DN and CBF in the left DN. Patients with UD showed significantly lower MD values compared with patients with BD in the right SCP. Correlation analysis showed there were negative correlations between illness duration and MD and Dr values in the right SCP in UD. LimitationsThis study was cross-sectional and the sample size was not large. Parts of the patients included were under medication prior to MRI scanning. ConclusionsOur findings provide new evidence of microstructural changes in cerebellum in BD and UD. The two disorders may have overlaps in microstructural abnormality in MCP and DN during the depressive period. Microstructural abnormality in SCP may be a key neurobiological feature of UD.

A 3D GRASE ASL technique for fast whole-brain perfusion fMRI: Perfomance investigation and comparison with standard BOLD fMRI in motor-task and reward-learning experiments

A 3D GRASE ASL technique for fast whole-brain perfusion fMRI: Perfomance investigation and comparison with standard BOLD fMRI in motor-task and reward-learning experiments