Browsing by Autor "Andrei Irimia"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item type: Item ,
    P2‐108: USING COMPUTED TOMOGRAPHY TO ASSESS BRAIN VOLUMETRICS IN AGING
    (Wiley, 2019) Andrei Irimia; Hillard Kaplan; Ben C. Trumble; Juan J. Copajira Adrian; Alexander S. Maher; Kenneth A. Rostowsky; Nahian F. Chowdhury; M. Linda Sutherland; James D. Sutherland; Adel H. Allam
    Although magnetic resonance imaging (MRI) remains the gold standard for the noninvasive evaluation of white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) volumes in the aging brain, CT continues to be used widely for brain imaging, particularly when MRI is unavailable or contraindicated. In developing countries, CT is often the only imaging modality available for evaluation of brain atrophy in patients with mild cognitive impairment (MCI) or Alzheimer's disease (AD). This has renewed interest in the development of approaches to use head CT to estimate brain volumetrics. A brain segmentation approach was developed to delineate WM, GM and CSF from head CT using probabilistic, atlas-based classification. Feasibility and utility were evaluated by comparing MRI-only to CT-only segmentations in 10 older adults [mean (μ) ± standard deviation (σ) of age = 65 ± 7 yrs; 5 females] from whom both MRI and CT scans were acquired within an eight-week period. Segmentation similarity was quantified using the Dice coefficient (DC), a robust measure of inter-modality tissue classification agreement. Comparison of MRI vs. CT segmentations yielded normally-distributed DCs [μ ± σ across participants: 85.5% ± 4.6% (WM), 86.7% ± 5.6% (GM) and 91.3% ± 2.8% (CSF)], indicating satisfactory ability to calculate brain volumetrics from the CT scans of the participants, relative to MRI measurements. For this sample, bootstrapping suggests that the tissue classification method is sufficiently sensitive to estimate WM, GM and CSF volumes within ∼5%, ∼4% and ∼3% of their MRI-based values, respectively. Compared to MRI, volumes computed from CT displayed no evidence of systematic over- or under-estimation [t (9) = 0.89, p > 0.80]. Our contribution broadens the ability to integrate CT imaging findings with other research on brain aging in health and disease, and complements other methodologies for the study of brain volumetrics in neurodegenerative diseases, including AD.
  • Thumbnail Image
    Item type: Item ,
    Prevalence of cerebrovascular calcifications in indigenous Bolivian Tsimane and Moseten
    (Wiley, 2023) Giuseppe Barisano; M. Linda Sutherland; James D. Sutherland; Margaret Gatz; Wendy J. Mack; Helena C. Chui; Meng Law; Daniel Eid Rodríguez; Raúl Quispe Gutierrez; Andrei Irimia
    Abstract Background Intracranial arteriosclerosis has been increasingly recognized as an etiological factor contributing to cognitive impairment. Indigenous Tsimane and Moseten, Amerindians of the Bolivian Amazon with physically‐active subsistence lifestyle, are reported to have lower prevalence of dementia (Gatz et al., Alzheimer’s Dement, In press) and coronary artery disease (Kaplan et al.,Lancet,2017) than Western populations. We assessed the prevalence of intracranial arteriosclerosis, cerebrovascular calcifications, and leukoaraiosis in these populations and investigated their relationship with brain atrophy and cognition. Method 155 participants aged ≥60 (60.6% females) underwent a non‐contrast computed tomography scan and cognitive testing. Visual rating scales were used to evaluate global cortical atrophy (GCA, simplified Pasquier), medial temporal atrophy (MTA, Scheltens), internal carotid artery (ICA) calcifications extent and morphology (Babiarz/Kockelkoren), lenticulostriate arteries (LSA) calcifications (de Brouwer), deep and periventricular leukoaraiosis (Fazekas). The maximum density (Hounsfield units) of LSA calcifications and the presence of infarcts and vertebral arteries (VA) calcifications were also evaluated. Result Virtually all participants presented vascular calcifications in ICA (99.3%), LSA (87.4%), and VA (98.5%) ( Fig.1,2 ). ICA calcification morphology was continuous in 58.7% and irregular/patchy in 40.5%, indicating medial and intimal pathology, respectively ( Fig.3 ). In 13.2% of cases, the LSA calcifications were surrounded by parenchymal calcifications in the basal ganglia ( Fig.4 ). Most cases showed no radiological sign of infarcts or leukoaraiosis. ICA calcifications correlated with age (P<.0001) while other calcification locations showed little association with age. LSA calcifications were greater in men than women (P<.01) with sex differences minimal for other calcification locations. After controlling for age and sex, ICA, LSA, basal ganglia and VA calcifications were related to greater GCA (all P<.05). LSA calcification density was significantly related to greater GCA and MTA, and to poorer visuo‐constructional ability (all P<.01). Prevalence of ICA and VA calcifications were higher compared to those reported in a population‐based European sample (79% and 16.9%, respectively; Vinke et al.,Neurobiol.Aging,2021). ( Fig.5 ) Conclusion Despite the low prevalence of dementia and coronary artery disease, cerebrovascular calcifications are commonly observed in this indigenous Bolivian population, and are associated with greater brain atrophy. Their underlying pathogenetic mechanisms remain unclear, but the high prevalence of infectious and inflammatory disorders might play a role.