Valid and efficient manual estimates of intracranial volume from magnetic resonance images

Background: Manual segmentations of the whole intracranial vault in high-resolution magnetic resonance images are often regarded as very time-consuming. Therefore it is common to only segment a few linearly spaced intracranial areas to estimate the whole volume. The purpose of the present study was to evaluate how the validity of intracranial volume estimates is affected by the chosen interpolation method, orientation of the intracranial areas and the linear spacing between them. Methods: Intracranial volumes were manually segmented on 62 participants from the Gothenburg MCI study using 1.5 T, T-1-weighted magnetic resonance images. Estimates of the intracranial volumes were then derived using subsamples of linearly spaced coronal, sagittal or transversal intracranial areas from the same volumes. The subsamples of intracranial areas were interpolated into volume estimates by three different interpolation methods. The linear spacing between the intracranial areas ranged from 2 to 50 mm and the validity of the estimates was determined by comparison with the entire intracranial volumes. Results: A progressive decrease in intra-class correlation and an increase in percentage error could be seen with increased linear spacing between intracranial areas. With small linear spacing (<= 15 mm), orientation of the intracranial areas and interpolation method had negligible effects on the validity. With larger linear spacing, the best validity was achieved using cubic spline interpolation with either coronal or sagittal intracranial areas. Even at a linear spacing of 50 mm, cubic spline interpolation on either coronal or sagittal intracranial areas had a mean absolute agreement intra-class correlation with the entire intracranial volumes above 0.97. Conclusion: Cubic spline interpolation in combination with linearly spaced sagittal or coronal intracranial areas overall resulted in the most valid and robust estimates of intracranial volume. Using this method, valid ICV estimates could be obtained in less than five minutes per patient

Hippocampal volumetry in mild cognitive impairment

Dementia is a syndrome with cognitive decline as a prominent feature. MCI is similarly a syndrome of cognitive decline, albeit with much subtler symptoms, and has been identified as a condition at risk for progression to dementia. A considerable clinical challenge lies in identifying MCI patients with an underlying dementia disorder. The overall aim of this thesis is to examine hippocampal volume in MCI with regard to prognostics. Alzheimer’s disease (AD) and vascular dementia are the two most important causes of dementia. Subcortical ischemic vascular dementia (SIVD), characterized by white matter lesions (WMLs), is considered the most important cause of vascular dementia in the elderly. Hippocampal atrophy has been identified as a common feature of AD and increasing evidence suggests that hippocampal atrophy is present in SIVD as well. It was found that MCI patients subsequently converting to dementia have smaller hippocampi than stable MCI patients. Hippocampal volume seems to be a useful marker in MCI patients with different underlying disorders. It can therefore be argued that hippocampal volume may be viewed as a broad cognitive marker. Hippocampal volume was also found to supplement the prognostic ability of CSF Aβ42 and T-tau in MCI. Furthermore, measurement of WML shows that WML volume is related to hippocampal volume in patients with high WML burden, suggesting that WMLs may be involved in the development of hippocampal atrophy in SIVD. Left hippocampal volume was consistently a better prognostic marker than right hippocampal volume. When evaluating their respective association with psychometric test performance, the left hippocampus was found to be more closely related to test performance

Delineation of two intracranial areas and the perpendicular intracranial width is sufficient for intracranial volume estimation

Abstract Objectives The aim of the present study is to determine if the delineation of one or two optimally chosen intracranial areas (ICA) is enough to achieve adequate estimates of intracranial volume (ICV) in magnetic resonance imaging. Methods The correlations of 62 fully delineated ICVs with four types of ICV estimates were calculated. The estimate types were: (1) a single midsagittal ICA, (2) single ICA multiplied by the intracranial width perpendicular to the ICA, (3) sum of two ICAs multiplied by the perpendicular intracranial width and (4) shape-preserving piecewise cubic interpolation using two ICAs. For methods 2–4, the fully delineated ICVs were randomly separated into an evaluation and a validation set of equal size. Method 1 was validated against all of the fully delineated ICVs. Results Estimates from method 1 had a Pearson correlation of 0.904 with fully delineated ICV. For method 2, the correlation was 0.986 when delineating the sagittal ICA at 31% of the sagittal intracranial width. For methods 3 and 4, the correlations were both 0.997 when delineating the sagittal ICAs at 17.5 and 64% and at 12 and 64% respectively. Conclusions Delineation of two specific intracranial areas is sufficient for intracranial volume estimation. Main messages • Delineation of two specific intracranial areas is sufficient for intracranial volume estimation. • The estimates had a Pearson correlation of 0.997 with intracranial volume. • The estimation should take no more than 5 min

Subjective cognitive impairment is a predominantly benign condition in memory clinic patients followed for 6 years: The Gothenburg-oslo MCI Study

Background/Aims: In the quest for prevention or treatment, there is a need to find early markers for preclinical dementia. This study observed memory clinic patients with subjective cognitive impairment (SCI) and normal cognitive function at baseline. The primary aim was to address SCI as a potential risk factor for cognitive decline. The secondary aim was to address a potential relation between (1) baseline cerebrospinal fluid biomarkers and (2) a decline in memory performance over the first 2 years of follow-up, with a possible cognitive decline after 6 years. Methods: Eighty-one patients (mean age 61 years) were recruited from university memory clinics and followed up for 6 years. Results: Eighty-six percent of the cohort remained cognitively stable or improved, 9% developed mild cognitive impairment, and only 5% (n = 4) developed dementia. Regression analysis revealed that low levels of Aβ42 at baseline and memory decline during the first 2 years predicted dementia. When combined, these variables were associated with a 50% risk of developing dementia. Conclusions: Cognitive stability for 86% of the cohort suggests that SCI is predominantly a benign condition with regard to neuropathology. The low number of individuals who developed dementia limits the generalizability of the results and discussion of progression factors.

Subjective Cognitive Impairment Is a Predominantly Benign Condition in Memory Clinic Patients Followed for 6 Years: The Gothenburg-Oslo MCI Study

Background/Aims: In the quest for prevention or treatment, there is a need to find early markers for preclinical dementia. This study observed memory clinic patients with subjective cognitive impairment (SCI) and normal cognitive function at baseline. The primary aim was to address SCI as a potential risk factor for cognitive decline. The secondary aim was to address a potential relation between (1) baseline cerebrospinal fluid biomarkers and (2) a decline in memory performance over the first 2 years of follow-up, with a possible cognitive decline after 6 years. Methods: Eighty-one patients (mean age 61 years) were recruited from university memory clinics and followed up for 6 years. Results: Eighty-six percent of the cohort remained cognitively stable or improved, 9% developed mild cognitive impairment, and only 5% (n = 4) developed dementia. Regression analysis revealed that low levels of Aβ42 at baseline and memory decline during the first 2 years predicted dementia. When combined, these variables were associated with a 50% risk of developing dementia. Conclusions: Cognitive stability for 86% of the cohort suggests that SCI is predominantly a benign condition with regard to neuropathology. The low number of individuals who developed dementia limits the generalizability of the results and discussion of progression factors

Open Access

Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case

Neuronal and Glia-Related Biomarkers in Cerebrospinal Fluid of Patients with Acute Ischemic Stroke

Background Cerebral ischemia promotes morphological reactions of the neurons, astrocytes, oligodendrocytes, and microglia in experimental studies. Our aim was to examine the profile of CSF (cerebrospinal fluid) biomarkers and their relation to stroke severity and degree of white matter lesions (WML). Methods A total of 20 patients (mean age 76 years) were included within 5–10 days after acute ischemic stroke (AIS) onset. Stroke severity was assessed using NIHSS (National Institute of Health stroke scale). The age-related white matter changes (ARWMC) scale was used to evaluate the extent of WML on CT-scans. The concentrations of specific CSF biomarkers were analyzed. Results Patients with AIS had significantly higher levels of NFL (neurofilament, light), T-tau, myelin basic protein (MBP), YKL-40, and glial fibrillary acidic protein (GFAP) compared with controls; T-Tau, MBP, GFAP, and YKL-40 correlated with clinical stroke severity, whereas NFL correlated with severity of WML (tested by Mann–Whitney test). Conclusions Several CSF biomarkers increase in AIS, and they correlate to clinical stroke severity. However, only NFL was found to be a marker of degree of WML

Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case–control study in long-term survivors from cancer in the head and neck region

Abstract Background An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients’ lowered QoL was coupled to a reduction in hippocampal volume. Methods Patients (11 men and 4 women, age 31–65) treated for head and neck cancer 4–10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 – 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon’s signed rank test were used for the main statistical analysis. Results There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. Conclusion The study gives solid evidence against the hypothesis that the patients’ lowered quality of life was due to a major reduction of hippocampal volume.</p

Hippocampal volumes in patients exposed to low-dose radiation to the basal brain : a case–control study in long-term survivors from cancer in the head and neck region

Background An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients’ lowered QoL was coupled to a reduction in hippocampal volume. Methods Patients (11 men and 4 women, age 31–65) treated for head and neck cancer 4–10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 – 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon’s signed rank test were used for the main statistical analysis. Results There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. Conclusion The study gives solid evidence against the hypothesis that the patients’ lowered quality of life was due to a major reduction of hippocampal volume