Browsing by Author "Stecher, Ximena"

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    Association between spontaneous internal carotid artery dissection and perivascular adipose tissue attenuation on computed tomography angiography
    (2023) Cheng, Kevin; Lin, Andrew; Stecher, Ximena; Bernstein, Tomas; Zuniga, Paulo; Mazzon, Enrico; Brunser, Alejandro; Diaz, Violeta; Martinez, Gonzalo; Cameron, William; Nicholls, Stephen J.; Patel, Sanjay; Dey, Damini; Wong, Dennis T. L.; Venturelli, Paula Munoz
    Background: Spontaneous cervical artery dissection (sCAD) is a leading cause of ischemic stroke in young patients. Studies using high-resolution magnetic resonance imaging and positron emission tomography have suggested vessel wall inflammation to be a pathogenic factor in sCAD. Computed tomography (CT) attenuation of perivascular adipose tissue (PVAT) is an established non-invasive imaging biomarker of inflammation in coronary arteries, with higher attenuation values reflecting a greater degree of vascular inflammation. Objectives: We evaluate the CT attenuation of PVAT surrounding the internal carotid artery (PVAT(carotid)) with and without spontaneous dissection. Methods: Single-center prospective observational study of 56 consecutive patients with CT-verified spontaneous dissection of the internal carotid artery (ICA). Of these patients, six underwent follow-up computed tomography angiography (CTA). Twenty-two patients who underwent CTA for acute neurological symptoms but did not have dissection formed the control group. Using semi-automated research software, PVAT(carotid) was measured as the mean Hounsfield unit (HU) attenuation of adipose tissue within a defined volume of interest surrounding the ICA. Results: PVAT(carotid) was significantly higher around dissected ICA compared with non-dissected contralateral ICA in the same patients (-58.7 +/- 10.2 vs -68.9 +/- 8.1 HU, p < 0.0001) and ICA of patients without dissection (-58.7 +/- 10.2 vs -69.3 +/- 9.3 HU, p < 0.0001). After a median follow-up of 89 days, there was a significant reduction in PVAT(carotid) around dissected ICA (-57.5 +/- 13.4 to -74.3 +/- 10.5 HU, p < 0.05), while no change was observed around non-dissected contralateral ICA (-71.0 +/- 4.4 to -74.1 +/- 4.1 HU, p = 0.19). ICA dissection was an independent predictor of PVAT(carotid) following multivariable adjustment for age and the presence of ICA occlusion. Conclusion: PVAT(carotid) is elevated in the presence of sCAD and may decrease following the acute event.
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    Patients recovering from COVID-19 who presented with anosmia during their acute episode have behavioral, functional, and structural brain alterations
    (2024) Kausel, Leonie; Figueroa-Vargas, Alejandra; Zamorano, Francisco; Stecher, Ximena; Aspe-Sanchez, Mauricio; Carvajal-Paredes, Patricio; Marquez-Rodriguez, Victor; Martinez-Molina, Maria Paz; Roman, Claudio; Soto-Fernandez, Patricio; Valdebenito-Oyarzo, Gabriela; Manterola, Carla; Uribe-San-Martin, Reinaldo; Silva, Claudio; Henriquez-Ch, Rodrigo; Aboitiz, Francisco; Polania, Rafael; Guevara, Pamela; Munoz-Venturelli, Paula; Soto-Icaza, Patricia; Billeke, Pablo
    Patients recovering from COVID-19 commonly exhibit cognitive and brain alterations, yet the specific neuropathological mechanisms and risk factors underlying these alterations remain elusive. Given the significant global incidence of COVID-19, identifying factors that can distinguish individuals at risk of developing brain alterations is crucial for prioritizing follow-up care. Here, we report findings from a sample of patients consisting of 73 adults with a mild to moderate SARS-CoV-2 infection without signs of respiratory failure and 27 with infections attributed to other agents and no history of COVID-19. The participants underwent cognitive screening, a decision-making task, and MRI evaluations. We assessed for the presence of anosmia and the requirement for hospitalization. Groups did not differ in age or cognitive performance. Patients who presented with anosmia exhibited more impulsive alternative changes after a shift in probabilities (r = - 0.26, p = 0.001), while patients who required hospitalization showed more perseverative choices (r = 0.25, p = 0.003). Anosmia correlated with brain measures, including decreased functional activity during the decision-making task, thinning of cortical thickness in parietal regions, and loss of white matter integrity. Hence, anosmia could be a factor to be considered when identifying at-risk populations for follow-up.