MRI-Derived Fetal Weight Estimation in the Midpregnancy Fetus: A Method Comparison Study

<b><i>Objectives:</i></b> The aim of this study was to compare the standard ultrasound (US) estimated fetal weight (EFW) and MRI volume-derived methods for the midtrimester fetus. <b><i>Methods:</i></b> Twenty-five paired US and MRI scans had the EFW calculated (gestational age [GA] range = 20–26 weeks). The intra- and interobserver variability of each method was assessed (2 operators/modality). A small sub-analysis was performed on 5 fetuses who were delivered preterm (mean GA 29 ⁺³ weeks) and compared to the actual birthweight. <b><i>Results:</i></b> Two MRI volumetry EFW formulae under-measured compared to US by −10.9% and −14.5% in the midpregnancy fetus (<i>p</i> &#x3c; 0.001) but had excellent intra- and interobserver agreement (intraclass correlation coefficient = 0.998 and 0.993). In the preterm fetus, the mean relative difference (MRD) between the MRI volume-derived EFW (MRI-EFW) and actual expected birthweight (at the scan GA) was −13.7% (−159.0 g, 95% CI: −341.7 to 23.7 g) and −17.1% (−204.6 g, 95% CI: −380.4 to −28.8 g), for the 2 MRI formulae. The MRD was smaller for US at 5.3% (69.8 g, 95% CI: −34.3 to 173.9). <b><i>Conclusions:</i></b> MRI-EFW results should be interpreted with caution in midpregnancy. Despite excellent observer agreement with MRI volumetry, refinement of the EFW formula is needed in the second trimester, for the small and for the GA and preterm fetus to compensate for lower fetal densities.

Defining Vascular Cognitive Impairment in India—A Descriptive Study of MRI Volumetry vs. Cognition in 'Normal' Adults

Background: It is important to establish criteria to define Vascular Cognitive Impairment (VCI) in India as VCI is an image-based diagnosis and MRI changes resulting from age with prevalent vascular risk factors may confound MRI interpretation. Objective: To establish normative community data for MRI volumetry including white matter hyperintensity volume (WMHV), correlated with age-stratified cognitive scores and vascular risk factors in adults ≥40 years old. Materials and Methods: We screened 2651 individuals without known neurological morbidity, living in Mumbai and nearby rural areas, using validated Marathi translations of Kolkata Cognitive Battery (KCB) and Geriatric depression score (GDS). We stratified 1961 persons with GDS ≤9 by age and cognitive score, and randomly selected ten percent from each subgroup for MRI brain volumetry. Crude volumes were standardized to reflect percentage of intracranial volume. Results: MRI volumetry studies were done in 199 individuals (F/M = 90/109; 73 with BMI ≥ 25; 44 hypertensives; 29 diabetics; mean cognitive score 76.5). Both grey and white matter volumes decreased with increasing age. WMHV increased with age and hypertension. Grey matter volume decreased with increasing WMHV. Positive predictors of cognition included standardized hippocampal volume (HCV), urban living, education, and BMI, while WMHV and age were negative predictors. Urban dwellers had higher cognitive scores than rural, and (paradoxically) smaller HCV. Conclusions: Further study is warranted into sociodemographic and biological factors that mutually influence cognition. Our findings contribute to baseline diagnostic criteria for VCI and could help in early diagnosis and control of cognitive decline and its key risk factors.

Basal Forebrain Atrophy Is Associated With Allocentric Navigation Deficits in Subjective Cognitive Decline

Individuals with subjective cognitive decline (SCD) are at higher risk of incipient Alzheimer's disease (AD). Spatial navigation (SN) impairments in AD dementia and mild cognitive impairment patients have been well-documented; however, studies investigating SN deficits in SCD subjects are still lacking. This study aimed to explore whether basal forebrain (BF) and entorhinal cortex (EC) atrophy contribute to spatial disorientation in the SCD stage. In total, 31 SCD subjects and 24 normal controls were enrolled and administered cognitive scales, a 2-dimensional computerized SN test, and structural magnetic resonance imaging (MRI) scanning. We computed the differences in navigation distance errors and volumes of BF subfields, EC, and hippocampus between the SCD and control groups. The correlations between MRI volumetry and navigation distance errors were also calculated. Compared with the controls, the SCD subjects performed worse in both egocentric and allocentric navigation. The SCD group showed volume reductions in the whole BF (p &lt; 0.05, uncorrected) and the Ch4p subfield (p &lt; 0.05, Bonferroni corrected), but comparable EC and hippocampal volumes with the controls. In the SCD cohort, the allocentric errors were negatively correlated with total BF (r = −0.625, p &lt; 0.001), Ch4p (r = −0.625, p &lt; 0.001), total EC (r = −0.423, p = 0.031), and left EC volumes (r = −0.442, p = 0.024), adjusting for age, gender, years of education, total intracranial volume, and hippocampal volume. This study demonstrates that SN deficits and BF atrophy may be promising indicators for the early detection of incipient AD patients. The reduced BF volume, especially in the Ch4p subfield, may serve as a structural basis for allocentric disorientation in SCD subjects independent of hippocampal atrophy. Our findings may have further implications for the preclinical diagnosis and intervention for potential AD patients.

Cerebellum and brain stem volume loss in relapsing remission multiple sclerosis by MRI volumetry: relation to neurological disability score and number of relapses

Background MRI is the method of choice in the diagnosis of MS as well as in monitoring the disease activity. MRI volumetry is used to assess whole or regional brain volume loss which reflects neurodegenerative aspect of the disease and plays an important role in all stages of disease. The aim of this work is to study MRI volumetry in the evaluation of cerebellum and brain stem volume loss in RRMS patients and its correlation with neurological disability score and number of relapses. Results Volumes of whole brainstem, medulla, and pons showed a significant decrease in RRMS cases compared to controls (p < 0.05). Brainstem volume had a mean volume of 22.17 and 25.09 cm3 in cases and controls, respectively. However, midbrain volume showed no significant difference between cases and controls (p = 0.134). Volume of left cerebellar cortex showed a significant decrease in RRMS cases compared to controls (p < 0.001). It had mean volumes of 81.64 and 92.14 ml in cases and controls, respectively, at left cerebellar hemisphere, while right cerebellar hemisphere cortex volumes were 80.37 and 91.97 ml in cases and controls, respectively. Cerebellar white matter showed no significant volume decrease in cases and controls. Conclusion Volumetric MR imaging is an important tool for quantifying the MS disease, assesses MS activity, progression, and tissue loss. The degree and the pattern of atrophy on MRI images correlate significantly with the neurological disability score and number of relapses.

Vitamin D Levels, APOE Allele, and MRI Volumetry Assessed by NeuroQuant in Norwegian Adults with Cognitive Symptoms

Background: Allele ɛ4 of the apolipoprotein (APOE ∈4) gene is the strongest known genetic risk factor for late-onset sporadic Alzheimer’s disease. A possible relationship between vitamin D and APOE is not yet clear. Objective: In this exploratory, cross-sectional study, we examined the association between serum levels of 25-hydroxyvitamin D [25(OH)D] and brain volumes and the associations of both serum levels of 25(OH)D and APOE polymorphism to brain volumes in 127 persons (mean age 66 years) with cognitive symptoms. Methods: All subjects were examined with fully automated software for MRI volumetry, NeuroQuant. Results: After adjustment for relevant covariates, higher serum 25(OH)D levels were associated with greater volumes of cortical gray matter on both left (p = 0.02) and right (p = 0.04) sides. When both 25(OH)D levels and APOE genotype were used as the main covariates, no significant associations were found between vitamin D level and brain volume in any of the 11 brain regions. In adjusted models, only homozygous but not heterozygous APOE ∈4 allele carriers had significantly larger inferior lateral ventricles (p = 0.003) and smaller hippocampal volume (p = 0.035) than those without ɛ4. Homozygous APOE ∈4 carriers also had significantly higher vitamin D levels (p = 0.009) compared to persons without the APOE ∈4 allele. Conclusion: Higher vitamin D levels might have a preserving effect on cortical grey matter volume.

Improving Accuracy of Brainstem MRI Volumetry: Effects of Age and Sex, and Normalization Strategies

Background: Brainstem-mediated functions are impaired in neurodegenerative diseases and aging. Atrophy can be visualized by MRI. This study investigates extrinsic sources of brainstem volume variability, intrinsic sources of anatomical variability, and the influence of age and sex on the brainstem volumes in healthy subjects. We aimed to develop efficient normalization strategies to reduce the effects of intrinsic anatomic variability on brainstem volumetry.Methods: Brainstem segmentation was performed from MPRAGE data using our deep-learning-based brainstem segmentation algorithm MD-GRU. The extrinsic variability of brainstem volume assessments across scanners and protocols was investigated in two groups comprising 11 (median age 33.3 years, 7 women) and 22 healthy subjects (median age 27.6 years, 50% women) scanned twice and compared using Dice scores. Intrinsic anatomical inter-individual variability and age and sex effects on brainstem volumes were assessed in segmentations of 110 healthy subjects (median age 30.9 years, range 18–72 years, 53.6% women) acquired on 1.5T (45%) and 3T (55%) scanners. The association between brainstem volumes and predefined anatomical covariates was studied using Pearson correlations. Anatomical variables with associations of |r| &gt; 0.30 as well as the variables age and sex were used to construct normalization models using backward selection. The effect of the resulting normalization models was assessed by % relative standard deviation reduction and by comparing the inter-individual variability of the normalized brainstem volumes to the non-normalized values using paired t- tests with Bonferroni correction.Results: The extrinsic variability of brainstem volumetry across different field strengths and imaging protocols was low (Dice scores &gt; 0.94). Mean inter-individual variability/SD of total brainstem volumes was 9.8%/7.36. A normalization based on either total intracranial volume (TICV), TICV and age, or v-scale significantly reduced the inter-individual variability of total brainstem volumes compared to non-normalized volumes and similarly reduced the relative standard deviation by about 35%.Conclusion: The extrinsic variability of the novel brainstem segmentation method MD-GRU across different scanners and imaging protocols is very low. Anatomic inter-individual variability of brainstem volumes is substantial. This study presents efficient normalization models for variability reduction in brainstem volumetry in healthy subjects.