Wolfson Brain Imaging Center

Brain, United Kingdom

Wolfson Brain Imaging Center

Brain, United Kingdom
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Hoffmann M.,Wolfson Brain Imaging Center | Mada M.,Wolfson Brain Imaging Center | Carpenter T.A.,Wolfson Brain Imaging Center | Williams G.B.,Wolfson Brain Imaging Center
Magnetic Resonance in Medicine | Year: 2015

Purpose: While MRI is enhancing our knowledge about the structure and function of the human brain, subject motion remains a problem in many clinical applications. Recently, the use of wireless radiofrequency markers with three one-dimensional (1D) navigators for prospective correction was demonstrated. This method is restricted in the range of motion that can be corrected, however, because of limited information in the 1D readouts. Methods: Here, the limitation of techniques for disambiguating marker locations was investigated. It was shown that including more sampling directions extends the tracking range for head rotations. The efficiency of trading readout resolution for speed was explored. Results: Tracking of head rotations was demonstrated from -19.2 to 34.4°, -2.7 to 10.0°, and -60.9 to 70.9° in the x-, y-, and z-directions, respectively. In the presence of excessive head motion, the deviation of marker estimates from SPM8 was reduced by 17.1% over existing three-projection methods. This was achieved by using an additional seven directions, extending the time needed for readouts by a factor of 3.3. Much of this increase may be circumvented by reducing resolution, without compromising accuracy. Conclusion: Including additional sampling directions extends the range in which markers can be used, for patients who move a lot. © 2015 The Authors.


Carrera E.,University of Cambridge | Jones P.S.,University of Cambridge | Alawneh J.A.,University of Cambridge | Klaerke Mikkelsen I.,University of Aarhus | And 15 more authors.
Stroke | Year: 2011

Background And Purpose- There is ample evidence that in anterior circulation stroke, the diffusion-weighted imaging (DWI) lesion may escape infarction and thus is not a reliable infarct predictor. In this study, we assessed the predictive value of the mean transit time (MTT) for final infarction within the DWI lesion, first in patients scanned back-to-back with O-positron emission tomography and MR (DWI and perfusion-weighted imaging; "Cambridge sample") within 7 to 21 hours of clinical onset, then in a large sample of patients with anterior circulation stroke receiving DWI and perfusion-weighted imaging within 12 hours (85% within 6 hours; "I-KNOW sample"). Methods- Both samples underwent structural MRI at approximately 1 month to map final infarcts. For both imaging modalities, MTT was calculated as cerebral blood volume/cerebral blood flow. After image coregistration and matrix resampling, the MTT values between voxels of interest that later infarcted or not were compared separately within and outside DWI lesions (DWI+ and DWI-, respectively) both within and across patients. In the I-KNOW sample, receiver operating characteristic curves were calculated for these voxel of interest populations and areas under the curve and optimal thresholds calculated. Results- In the Cambridge data set (n=4), there was good concordance between predictive values of MTTpositron emission tomography and MTTperfusion-weighted imaging for both DWI+ and DWI- voxels of interest indicating adequate reliability of MTTperfusion-weighted imaging for this purpose. In the I-KNOW data set (N=42), the MTT significantly added to the DWI lesion to predict infarction in both DWI- and DWI+ voxels of interest with areas under the curve approximately 0.78 and 0.64 (both P<0.001) and optimal thresholds approximately 8 seconds and 11 seconds, respectively. Conclusions- Despite the relatively small samples, this study suggests that adding MTTperfusion-weighted imaging may improve infarct prediction not only as already known outside, but also within, DWI lesions. © 2011 American Heart Association, Inc.


Mak E.,University of Cambridge | Su L.,University of Cambridge | Williams G.B.,Wolfson Brain Imaging Center | Watson R.,Royal Melbourne Hospital | And 4 more authors.
NeuroImage: Clinical | Year: 2015

Background & objective Percent whole brain volume change (PBVC) measured from serial MRI scans is widely accepted as a sensitive marker of disease progression in Alzheimer's disease (AD). However, the utility of PBVC in the differential diagnosis of dementia remains to be established. We compared PBVC in AD and dementia with Lewy bodies (DLB), and investigated associations with clinical measures. Methods 72 participants (14 DLBs, 25 ADs, and 33 healthy controls (HCs)) underwent clinical assessment and 3 Tesla T1-weighted MRI at baseline and repeated at 12 months. We used FSL-SIENA to estimate PBVC for each subject. Voxelwise analyses and ANCOVA compared PBVC between DLB and AD, while correlational tests examined associations of PBVC with clinical measures. Results AD had significantly greater atrophy over 1 year (1.8%) compared to DLB (1.0%; p = 0.01) and HC (0.9%; p < 0.01) in widespread regions of the brain including periventricular areas. PBVC was not significantly different between DLB and HC (p = 0.95). There were no differences in cognitive decline between DLB and AD. In the combined dementia group (AD and DLB), younger age was associated with higher atrophy rates (r = 0.49, p < 0.01). Conclusions AD showed a faster rate of global brain atrophy compared to DLB, which had similar rates of atrophy to HC. Among dementia subjects, younger age was associated with accelerated atrophy, reflecting more aggressive disease in younger people. PBVC could aid in differentiating between DLB and AD, however its utility as an outcome marker in DLB is limited. © 2015 Published by Elsevier Ltd.


PubMed | Wolfson Brain Imaging Center, Royal Melbourne Hospital, Vitality, University of Cambridge and Northumbria University
Type: | Journal: NeuroImage. Clinical | Year: 2015

Percent whole brain volume change (PBVC) measured from serial MRI scans is widely accepted as a sensitive marker of disease progression in Alzheimers disease (AD). However, the utility of PBVC in the differential diagnosis of dementia remains to be established. We compared PBVC in AD and dementia with Lewy bodies (DLB), and investigated associations with clinical measures.72 participants (14 DLBs, 25 ADs, and 33 healthy controls (HCs)) underwent clinical assessment and 3Tesla T1-weighted MRI at baseline and repeated at 12months. We used FSL-SIENA to estimate PBVC for each subject. Voxelwise analyses and ANCOVA compared PBVC between DLB and AD, while correlational tests examined associations of PBVC with clinical measures.AD had significantly greater atrophy over 1year (1.8%) compared to DLB (1.0%; p=0.01) and HC (0.9%; p<0.01) in widespread regions of the brain including periventricular areas. PBVC was not significantly different between DLB and HC (p=0.95). There were no differences in cognitive decline between DLB and AD. In the combined dementia group (AD and DLB), younger age was associated with higher atrophy rates (r=0.49, p<0.01).AD showed a faster rate of global brain atrophy compared to DLB, which had similar rates of atrophy to HC. Among dementia subjects, younger age was associated with accelerated atrophy, reflecting more aggressive disease in younger people. PBVC could aid in differentiating between DLB and AD, however its utility as an outcome marker in DLB is limited.


Mak E.,University of Cambridge | Su L.,University of Cambridge | Williams G.B.,Wolfson Brain Imaging Center | O'Brien J.T.,University of Cambridge
Alzheimer's Research and Therapy | Year: 2014

This review summarises the findings and applications from neuroimaging studies in dementia with Lewy bodies (DLB), highlighting key differences between DLB and other subtypes of dementia. We also discuss the increasingly important role of imaging biomarkers in differential diagnosis and outline promising areas for future research in DLB. DLB shares common clinical, neuropsychological and pathological features with Parkinson's disease dementia and other dementia subtypes, such as Alzheimer's disease. Despite the development of consensus diagnostic criteria, the sensitivity for differential diagnosis of DLB in clinical practice remains low and many DLB patients will be misdiagnosed. The importance of developing accurate imaging markers in dementia is highlighted by the potential for treatments targeting specific molecular abnormalities as well as the responsiveness to cholinesterase inhibitors and marked neuroleptic sensitivity of DLB. We review various brain imaging techniques that have been applied to investigate DLB, including the characteristic nigrostriatal degeneration in DLB using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers. Dopamine transporter loss has proven to reliably differentiate DLB from other dementias and has been incorporated into the revised clinical diagnostic criteria for DLB. To date, this remains the 'gold standard' for diagnostic imaging of DLB. Regional cerebral blood flow, 18 F-fluorodeoxygluclose-PET and SPECT have also identified marked deficits in the occipital regions with relative sparing of the medial temporal lobe when compared to Alzheimer's disease. In addition, structural, diffusion, and functional magnetic resonance imaging techniques have shown alterations in structure, white matter integrity, and functional activity in DLB. We argue that the multimodal identification of DLB-specific biomarkers has the potential to improve ante-mortem diagnosis and contribute to our understanding of the pathological background of DLB and its progression. © 2014 Mak et al.; licensee BioMed Central Ltd.


Mak E.,University of Cambridge | Su L.,University of Cambridge | Williams G.B.,Wolfson Brain Imaging Center | O'Brien J.T.,University of Cambridge
Parkinsonism and Related Disorders | Year: 2015

There has been a gradual shift in the definition of Parkinson's disease, from a movement disorder to a neurodegenerative condition affecting multiple cognitive domains. Mild cognitive impairment (PD-MCI) is a frequent comorbidity in PD that is associated with progression to dementia (PDD) and debilitating consequences for patients and caregivers. At present, the pathophysiology underpinning cognitive impairment in PD is not established, although emerging evidence has suggested that multi-modal imaging biomarkers could be useful in the early diagnosis of PD-MCI and PDD, thereby identifying at-risk patients to enable treatment at the earliest stage possible. Structural MRI studies have revealed prominent grey matter atrophy and disruptions of white matter tracts in PDD, although findings in non-demented PD have been more variable. There is a need for further longitudinal studies to clarify the spatial and temporal progression of morphological changes in PD, as well as to assess their underlying involvement in the evolution of cognitive deficits. In this review, we discuss the aetiology and neuropsychological profiles of PD-MCI and PDD, summarize the putative imaging substrates in light of evidence from multi-modal neuroimaging studies, highlight limitations in the present literature, and suggest recommendations for future research. © 2015 Elsevier Ltd.


PubMed | Wolfson Brain Imaging Center and University of Cambridge
Type: Journal Article | Journal: Parkinsonism & related disorders | Year: 2015

There has been a gradual shift in the definition of Parkinsons disease, from a movement disorder to a neurodegenerative condition affecting multiple cognitive domains. Mild cognitive impairment (PD-MCI) is a frequent comorbidity in PD that is associated with progression to dementia (PDD) and debilitating consequences for patients and caregivers. At present, the pathophysiology underpinning cognitive impairment in PD is not established, although emerging evidence has suggested that multi-modal imaging biomarkers could be useful in the early diagnosis of PD-MCI and PDD, thereby identifying at-risk patients to enable treatment at the earliest stage possible. Structural MRI studies have revealed prominent grey matter atrophy and disruptions of white matter tracts in PDD, although findings in non-demented PD have been more variable. There is a need for further longitudinal studies to clarify the spatial and temporal progression of morphological changes in PD, as well as to assess their underlying involvement in the evolution of cognitive deficits. In this review, we discuss the aetiology and neuropsychological profiles of PD-MCI and PDD, summarize the putative imaging substrates in light of evidence from multi-modal neuroimaging studies, highlight limitations in the present literature, and suggest recommendations for future research.


PubMed | Wolfson Brain Imaging Center and University of Cambridge
Type: Journal Article | Journal: Alzheimer's research & therapy | Year: 2014

This review summarises the findings and applications from neuroimaging studies in dementia with Lewy bodies (DLB), highlighting key differences between DLB and other subtypes of dementia. We also discuss the increasingly important role of imaging biomarkers in differential diagnosis and outline promising areas for future research in DLB. DLB shares common clinical, neuropsychological and pathological features with Parkinsons disease dementia and other dementia subtypes, such as Alzheimers disease. Despite the development of consensus diagnostic criteria, the sensitivity for differential diagnosis of DLB in clinical practice remains low and many DLB patients will be misdiagnosed. The importance of developing accurate imaging markers in dementia is highlighted by the potential for treatments targeting specific molecular abnormalities as well as the responsiveness to cholinesterase inhibitors and marked neuroleptic sensitivity of DLB. We review various brain imaging techniques that have been applied to investigate DLB, including the characteristic nigrostriatal degeneration in DLB using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers. Dopamine transporter loss has proven to reliably differentiate DLB from other dementias and has been incorporated into the revised clinical diagnostic criteria for DLB. To date, this remains the gold standard for diagnostic imaging of DLB. Regional cerebral blood flow, 18F-fluorodeoxygluclose-PET and SPECT have also identified marked deficits in the occipital regions with relative sparing of the medial temporal lobe when compared to Alzheimers disease. In addition, structural, diffusion, and functional magnetic resonance imaging techniques have shown alterations in structure, white matter integrity, and functional activity in DLB. We argue that the multimodal identification of DLB-specific biomarkers has the potential to improve ante-mortem diagnosis and contribute to our understanding of the pathological background of DLB and its progression.


PubMed | Wolfson Brain Imaging Center, Behavioural and Clinical Neuroscience Institute and University of Cambridge
Type: | Journal: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment | Year: 2015

We consider the effects of using a fixed linear transformation to match positron emission tomography (PET) and magnetic resonance imaging (MRI) data acquired simultaneously using a split-magnet system. Estimates of the frequency offset in MRI scans were used to calculate geometric variability in MRI reconstruction as a consequence of mis-setting this parameter in addition to repeated estimation of the transformation matrix by manual measurements. None of the measured variability approached the resolution of the PET images so we concluded that a fixed matrix can be reliably used in such a system.

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