Optimized Single-Slab Three-dimensional Spin-Echo MR Imaging of the Brain

Mugler, John P.; Bao, Sumi M.; Mulkern, Robert V.; Guttmann, Charles R.G.; Robertson, Richard L.; Jólesz, Ferenc A.; Brookeman, James R.

doi:10.1148/radiology.216.3.r00au46891

Cited by 294 publications

(253 citation statements)

References 24 publications

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“…High-resolution (1.5-mm 3 ) fMRI scans were acquired using a 3T Magnetom Allegra head only MRI scanner (Siemens Healthcare), taking a partial volume of 35 slices focused on the temporal lobes. High-resolution T2-weighted structural images (0.52 × 0.52 × 0.5 mm 3 ) were acquired on a 3T whole-body MRI scanner (Magnetom TIM Trio; Siemens Healthcare) also in a partial volume focused on the temporal lobes (39). To ensure optimal data quality, images were reconstructed online and underwent online quality assurance (40).…”

Section: Methodsmentioning

confidence: 99%

CA3 size predicts the precision of memory recall

Chadwick

Bonnici

Maguire

2014

Proc. Natl. Acad. Sci. U.S.A.

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There is enduring interest in why some of us have clearer memories than others, given the substantial individual variation that exists in retrieval ability and the precision with which we can differentiate past experiences. Here we report novel evidence showing that variation in the size of human hippocampal subfield CA3 predicted the amount of neural interference between episodic memories within CA3, which in turn predicted how much retrieval confusion occurred between past memories. This effect was not apparent in other hippocampal subfields. This shows that subtle individual differences in subjective mnemonic experience can be accurately gauged from measurable variations in the anatomy and neural coding of hippocampal region CA3. Moreover, this mechanism may be relevant for understanding memory muddles in aging and pathological states.O ur memories often contain overlapping elements, because they tend to feature the same people and places that form the cornerstones of our lives. Nevertheless, we are generally able to recall many of these past experiences as distinct episodes, although we are not all equally adept at doing so. There is substantial individual variation in retrieval ability and the precision with which we can differentiate past events (1, 2). This is most acute as we age and in conditions such as dementia, where confusion about the past is often evident (2). There is keen interest, therefore, in elucidating the neural mechanisms that allow us to recollect numerous life experiences despite a high degree of intermemory similarity.We know little about how this is achieved in humans, but theoretical models propose that computations within hippocampal subfields facilitate the efficient storage and retrieval of similar memories (3-7). When we experience an event, pattern separation leads to the formation of a distinct neural representation within region CA3 (8-11). At retrieval, a previously stored memory representation within CA3 can be reactivated through the process of pattern completion (12, 13). However, when episodes are highly similar, the CA3 neuronal representations may not be completely distinct, leading to partial overlap (14). It is therefore not clear precisely what the limits of CA3 pattern separation might be. Here we directly tested the capacity of human CA3 to maintain distinct episodic representations in the presence of overlapping elements. We further investigated whether variation in this ability provides an explanatory account of individual differences in the precision of episodic memory retrieval. ResultsWe combined high-resolution functional MRI (14) (fMRI) with an ultra-high resolution structural MRI scanning protocol that permitted the separate identification of CA1, CA3, dentate gyrus (DG), and subiculum (15, 16). Stimuli were created by filming two brief action events against a green-screen background. Each event was then superimposed onto the same two spatial contexts, creating four movie clips that included every combination of the two events and the two contexts (17) (Fig...

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Section: Methodsmentioning

confidence: 99%

CA3 size predicts the precision of memory recall

Chadwick

Bonnici

Maguire

2014

Proc. Natl. Acad. Sci. U.S.A.

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“…[7][8][9][10][11][12] FLAIR MR imaging is sensitive to fluids with a high protein content. [13][14][15][16][17] Furthermore, 3D-FLAIR imaging can minimize the undesired inflow artifacts of CSF flow, has a higher signal-tonoise ratio and spatial resolution, and allows recognition of subtle compositional changes of the inner ear fluid. [18][19][20][21] Therefore, one can assume that the increased protein content in the cochlear perilymph of patients with ANs can be detected on 3D FLAIR imaging with a high sensitivity and good spatial resolution.…”

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confidence: 99%

Clinical Significance of an Increased Cochlear 3D Fluid-Attenuated Inversion Recovery Signal Intensity on an MR Imaging Examination in Patients with Acoustic Neuroma

Kim

Lee

Goh

et al. 2014

American Journal of Neuroradiology

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BACKGROUND AND PURPOSE:The increased cochlear signal on FLAIR images in patients with acoustic neuroma is explained by an increased concentration of protein in the perilymphatic space. However, there is still debate whether there is a correlation between the increased cochlear FLAIR signal and the degree of hearing disturbance in patients with acoustic neuroma. Our aim was to investigate the clinical significance of an increased cochlear 3D FLAIR signal in patients with acoustic neuroma according to acoustic neuroma extent in a large patient cohort.

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“…In the beginning, however, 3 D sequences were acquired in a multi-slab mode which had several disadvantages including the occurrence of so-called venetian blind effects and long acquisition times. These drawbacks were extinguished by the introduction of single-slab sequences [16]. More recently, single-slab 3 D FLAIR sequences were tested and compared to 2 D sequences in MS imaging and were shown to be highly sensitive in lesion detection [17,18].…”

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confidence: 99%