The general objective of this thesis was to investigate new (quantitative) MR techniques and MR markers in the light of both AD and cerebral aging. The quantitative MR techniques that we used were... Show moreThe general objective of this thesis was to investigate new (quantitative) MR techniques and MR markers in the light of both AD and cerebral aging. The quantitative MR techniques that we used were MTI, tCBF and WSS measurements. The new markers we studied were cerebral microbleeds and iron accumulation in the basal ganglia. In chapter 2 we investigated whether MTI changes could be detected in the GM, WM or both in patients suffering from MCI or AD. Using MTI we found evidence for structural brain changes in both GM and WM of patients with MCI and AD. Furthermore, these MTI changes were related to cognitive impairment as expressed by the mini mental state examination (MMSE) score. These findings imply that cerebral changes can be detected in both GM and WM even before patients are clinically demented. The finding of MTI changes in the GM might relate to classical AD type pathology, whereas WM MTI changes could indicate concomitant vascular pathology. The findings in chapter 2 raised the question of how the MTI changes found in this study are distributed over the GM and WM. This was investigated in chapter 3. In this study we showed that brain damage, as detected by MTI, is widespread over the lobes in both AD and MCI patients whereas GM damage is more focally present in the temporal and frontal lobe of MCI patients. These findings are compatible with the knowledge that GM damage originates from the temporal lobe in AD. This interpretation is further supported by the observed independent association between temporal GM peak height and cognitive decline. MTI changes were found in all four lobes of the MCI patients investigated in this study and show the involvement of a diffuse process affecting the WM even before patients are clinically demented, a finding potentially explained by the presence of diffuse vascular pathology. Chapter 4 shows that the tCBF is strongly associated with parenchymal volume rather than age and, although much weaker, with the severity of WMHs. Although the association between tCBF and parenchyma volume seems straightforward, this finding has important implications for future studies. Volume flow measurements should be corrected for parenchymal volume ratherthan age in all future studies in which flow measurements are being used as a diagnostic tool. In addition, studies including elderly patients or patients with a pathological increase of WMHs, such as diabetic type II subjects, should also correct their tCBF measurements for WMH volumes. Chapter 5 shows that hemodynamic conditions of the carotid and basilar arteries, as expressed in lower WSS parameters, are worse in both MCI and AD compared to controls. In addition, the WSS parameters were found to correlate strongly with cognition. Again, this study is additional evidence for an important role of vascular pathology in the development of AD. In chapter 6, we found a high prevalence of microbleeds in a population of patients suffering from vascular disease or at high risk of developing this condition. Age, hypertension and WMH were the most important risk factors for microbleeds, especially when located in the cortico-subcortical junction and basal ganglia. Regarding the associations between the presence and location of microbleeds on the one hand and parameters of cognitive functioning on the other, chapter 7 shows that microbleeds located infratentorially are associated with impaired cognitive functioning in the aging population with increased vascular risk factors. This suggests that in elderly individuals microbleeds in the posterior fossa should be considered a sign of small vessel disease with potential functional consequences. The semi-quantative scale for scoring basal ganglia hypo-intensity on T2*- weighted imaging presented in chapter 8 was associated with markers of neurodegeneration. This study showed that low signal intensity of the caudate nucleus T2*-weighted MR is a frequent finding which is associated with more cerebral atrophy, a higher load of WMH and a higher load of invisible changes in both cortical GM and NAWM non-demented elderly. Furthermore, hypo- intensity limited to the globus pallidus and putamen was not associated with any of these parameters of neurodegeneration. In chapter 9 we present a method for automated detection and classification of hypo-intense regions on T2-weighted MR images of the basal ganglia. In this chapter we not only show an association between basal ganglia hypo-intensity and cardiovascular risk factors but also with measures of cognitive functioning. From this we conclude that hypo-intensity of the basal ganglia on T2-weighted MR is not only a radiological finding accompanying cerebral aging but also an independent marker of neurodegeneration. Show less
OBJECTIVES Cerebral microbleeds (MBs) are an important indicator of cerebral small-vessel disease, and their prevalence increases with increasing age. Little is known about the functional... Show moreOBJECTIVES Cerebral microbleeds (MBs) are an important indicator of cerebral small-vessel disease, and their prevalence increases with increasing age. Little is known about the functional consequences of MBs in the aging population. In this study we investigated whether the presence and location of MBs are associated with cognition in the PROSPER study. METHODS For 439 subjects the number and location (cortico-subcortical, deep white matter, basal ganglia, and infratentorial) of the MBs was recorded. Difference in cognitive performance between subjects with and without MBs was calculated by entering the variables sex, age, white matter hyperintensity volume, infarction, and MBs in a linear mixed model. Differences in cognition between subjects with and without one or more MBs at different anatomic locations were assessed using the same model. RESULTS We found that after correction for sex, age, white matter hyperintensity volume, and infarction, subjects with infratentorial MBs had a significantly lower score on the Immediate Picture-Word Learning test, Delayed Picture-Word Learning, and Instrumental Activities of Daily Living. CONCLUSIONS Our data demonstrate that in elderly individuals at increased vascular risk, infratentorial MBs are associated with loss in cognitive functioning. Show less
Altmann-Schneider, I.; Trompet, S.; Craen, A.J.M. de; Es, A.C.G.M. van; Jukema, J.W.; Stott, D.J.; ... ; Grond, J. van der 2011
Background and Purpose-To investigate the prognostic value of cerebral microbleeds (CMB) regarding overall, cardiovascular-related, and stroke-related mortality and to investigate possible... Show moreBackground and Purpose-To investigate the prognostic value of cerebral microbleeds (CMB) regarding overall, cardiovascular-related, and stroke-related mortality and to investigate possible differences based on a cerebral amyloid angiopathy-type and nonlobar distribution of microbleeds. Methods-We included 435 subjects who were participants from the nested MRI substudy of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). Cox proportional hazard models were applied to estimate the risk of overall, cardiovascular-related, and stroke-related death associated with microbleeds in general and microbleeds with a lobar distribution suggestive of the presence of cerebral amyloid angiopathy. The corresponding Kaplan-Meier survival curves were calculated. Results-Subjects with >1 CMB had a 6-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 5.97; 95% CI, 1.60-22.26; P=0.01). The diagnosis of nonlobar microbleeds was associated with >2-fold risk of cardiovascular death compared to subjects without microbleeds (hazard ratio, 2.67; 95% CI, 1.23-5.81; P=0.01). Subjects with probable cerebral amyloid angiopathy-type microbleeds had >7-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 7.20; 95% CI, 1.44-36.10; P=0.02). Conclusions-This is the first study investigating the association between microbleeds and risk of overall, cardiovascular-related, and stroke-related mortality in an elderly population. Our findings indicate that the diagnosis of microbleeds is potentially of clinical relevance. Larger studies are needed to expand our observations and to address potential clinical implications and cost-benefits of such a policy. (Stroke. 2011;42:638-644.) Show less
Altmann-Schneider, I.; Trompet, S.; Craen, A.J.M. de; Es, A.C.G.M. van; Jukema, J.W.; Stott, D.J.; ... ; Grond, J. van der 2011
BACKGROUND AND PURPOSE: To investigate the prognostic value of cerebral microbleeds (CMB) regarding overall, cardiovascular-related, and stroke-related mortality and to investigate possible... Show moreBACKGROUND AND PURPOSE: To investigate the prognostic value of cerebral microbleeds (CMB) regarding overall, cardiovascular-related, and stroke-related mortality and to investigate possible differences based on a cerebral amyloid angiopathy-type and nonlobar distribution of microbleeds. METHODS: We included 435 subjects who were participants from the nested MRI substudy of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). Cox proportional hazard models were applied to estimate the risk of overall, cardiovascular-related, and stroke-related death associated with microbleeds in general and microbleeds with a lobar distribution suggestive of the presence of cerebral amyloid angiopathy. The corresponding Kaplan-Meier survival curves were calculated. RESULTS: Subjects with >1 CMB had a 6-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 5.97; 95% CI, 1.60-22.26; P=0.01). The diagnosis of nonlobar microbleeds was associated with >2-fold risk of cardiovascular death compared to subjects without microbleeds (hazard ratio, 2.67; 95% CI, 1.23-5.81; P=0.01). Subjects with probable cerebral amyloid angiopathy-type microbleeds had >7-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 7.20; 95% CI, 1.44-36.10; P=0.02). CONCLUSIONS: This is the first study investigating the association between microbleeds and risk of overall, cardiovascular-related, and stroke-related mortality in an elderly population. Our findings indicate that the diagnosis of microbleeds is potentially of clinical relevance. Larger studies are needed to expand our observations and to address potential clinical implications and cost-benefits of such a policy. Show less
Es, A.C.G.M. van; Grond, J. van der; Dam, V.H. ten; Craen, A.J.M. de; Blauw, G.J.; Westendorp, R.G.J.; ... ; PROSPER Study Grp 2010
Background and Purpose: Although total cerebral blood flow (tCBF) is known to be related to age, less is known regarding the associations between tCBF and the morphologic changes of the brain... Show moreBackground and Purpose: Although total cerebral blood flow (tCBF) is known to be related to age, less is known regarding the associations between tCBF and the morphologic changes of the brain accompanying cerebral aging. The purpose of this study was to investigate whether total cerebral blood flow (tCBF) is related to white matter hyperintensity (WMH) volume and/or cerebral atrophy. Furthermore, we investigate whether tCBF should be expressed in mL/min, as was done in all previous MR studies, or in mL/100 mL/min, which yielded good results in precious SPECT, PET and perfusion MRI studies investigating regional cerebral blood flow. Materials and Methods: Patients were included from the nested MRI sub-study of the PROSPER study. Dual fast spin echo and FLAIR images were obtained in all patients. In addition, single slice phase contrast MR angiography was used for flow measurements in the internal carotids and vertebral arteries. tCBF was expressed in both mL/min and mL/100 mL/min. Results: We found a significant correlation between tCBF in mL/min and both age (r = -.124; p = p <=.001) and parenchymal volume (r = 0.430; p <=.001). We found no association between tCBF in mL/min and %-atrophy (r = -.077; p <=.103) or total WMH volume (r = -.069; p =.148). When tCBF was expressed in mL/100 mL/min the correlation between tCBF and age was no longer found (r = -.001; p =.985). Multivariate regression analyses corrected for age showed a significant correlation between tCBF in mL/100 mL/min and WMH volume (r = -.106; p =.044). No significant association between tCBF in mL/100 mL/min and %- atrophy was found. Conclusion: From this study we conclude that, when evaluating tCBF alterations due to various pathologies, tCBF should in mL/100 mL/min instead of mL/min. Furthermore, changes or differences in WMH volume should be accounted for. Show less
