Magnetic resonance imaging Locus Coeruleus abnormality in amnestic Mild Cognitive Impairment is associated with future progression to dementia.

BACKGROUND AND PURPOSE: Human neuropathological studies indicate that the pontine nucleus Locus Coeruleus (LC) undergoes significant and early degeneration in Alzheimer's disease. This line of evidence alongside experimental data suggests that the LC functional/structural decay may represent a critical factor for Alzheimer's disease pathophysiological and clinical progression. In the present prospective study, we used Magnetic Resonance Imaging (MRI) with LC-sensitive sequence (LC-MRI) to investigate in vivo the LC involvement in Alzheimer's disease progression, and whether specific LC-MRI features at baseline are associated with prognosis and cognitive performance in amnestic Mild Cognitive Impairment. METHODS: LC-MRI parameters were measured at baseline by a template-based method on 3.0-T magnetic resonance images in 34 patients with Alzheimer's disease dementia, 73 patients with amnestic Mild Cognitive Impairment, and 53 cognitively intact individuals. A thorough neurological and neuropsychological assessment was performed at baseline and 2.5-year follow-up. RESULTS: In subjects with Mild Cognitive Impairment who converted to dementia (n = 32), the LC intensity and number of LC-related voxels were significantly lower than in cognitively intact individuals, resembling those observed in demented patients. Such a reduction was not detected in Mild Cognitive Impairment individuals, who remained stable at follow-up. In Mild Cognitive Impairment subjects converting to dementia, LC-MRI parameter reduction was maximal in the rostral part of the left nucleus. Structural equation modeling analysis showed that LC-MRI parameters positively correlate with cognitive performance. CONCLUSIONS: Our findings highlight a potential role of LC-MRI for predicting clinical progression in Mild Cognitive Impairment and support the key role of LC degeneration in the Alzheimer clinical continuum.

Detecting the vulnerable carotid plaque: the Carotid Artery Multimodality imaging Prognostic study design.

BACKGROUND: Carotid artery disease is highly prevalent and a main cause of ischemic stroke and vascular dementia. There is a paucity of information on predictors of serious vascular events. Besides percentage diameter stenosis, international guidelines also recommend the evaluation of qualitative characteristics of carotid artery disease as a guide to treatment, but with no agreement on which qualitative features to assess. This inadequate knowledge leads to a poor ability to identify patients at risk, dispersion of medical resources, and unproven use of expensive and resource-consuming techniques, such as magnetic resonance imaging, positron emission tomography, and computed tomography. OBJECTIVES: The Carotid Artery Multimodality imaging Prognostic (CAMP) study will: prospectively determine the best predictors of silent and overt ischemic stroke and vascular dementia in patients with asymptomatic subcritical carotid artery disease by identifying the noninvasive diagnostic features of the 'vulnerable carotid plaque'; assess whether 'smart' use of low-cost diagnostic methods such as ultrasound-based evaluations may yield at least the same level of prospective information as more expensive techniques. STUDY DESIGN: We will compare the prognostic/predictive value of all proposed techniques with regard to silent or clinically manifest ischemic stroke and vascular dementia. The study will include ≥300 patients with asymptomatic, unilateral, intermediate degree (40-60% diameter) common or internal carotid artery stenosis detected at carotid ultrasound, with a 2-year follow-up. The study design has been registered on Clinicaltrial.gov on December 17, 2020 (ID number NCT04679727).

Locus Coeruleus magnetic resonance imaging in cognitively intact elderly subjects.

The locus coeruleus is the main noradrenergic nucleus of the brain and is often affected in neurodegenerative diseases. Recently, magnetic resonance imaging with specific T1-weighted sequences for neuromelanin has been used to evaluate locus coeruleus integrity in patients with these conditions. In some of these studies, abnormalities in locus coeruleus signal have also been found in healthy controls and related to ageing. However, this would be at variance with recent post-mortem studies showing that the nucleus is not affected during normal ageing. The present study aimed at evaluating locus coeruleus features in a well-defined cohort of cognitively healthy subjects who remained cognitively intact on a one-year follow-up. An ad-hoc semiautomatic analysis of locus coeruleus magnetic resonance was applied. Sixty-two cognitively intact subjects aged 60-80 years, without significant comorbidities, underwent 3 T magnetic resonance with specific sequences for locus coeruleus. A semi-automatic tool was used to estimate the number of voxels belonging to locus coeruleus and its intensity was obtained for each subject. Each subject underwent extensive neuropsychological testing at baseline and 12 months after magnetic resonance scan. Based on neuropsychological testing 53 subjects were cognitively normal at baseline and follow up. No significant age-related differences in locus coeruleus parameters were found in this cohort. In line with recent post-mortem studies, our in vivo study confirms that locus coeruleus magnetic resonance features are not statistically significantly affected by age between 60 and 80 years, the age range usually evaluated in studies on neurodegenerative diseases. A significant alteration of locus coeruleus features in a cognitively intact elderly subject might be an early sign of pathology.

Functional magnetic resonance imaging with encoding task in patients with mild cognitive impairment and different severity of leukoaraiosis.

Leukoaraiosis is one of the main contributors to mild cognitive impairment due to vascular damage (vascular MCI, VMCI), whose pathophysiology has not been fully elucidated yet. We aimed to shed light on such issue using functional MRI (fMRI). Sixteen patients with VMCI were enrolled and compared with twenty-five patients with MCI but without significant vascular damage (non-vascular MCI, NVMCI) and with fifteen healthy controls (HC). They all underwent fMRI with incidental verbal learning paradigm, using a 3T scanner. Differently from cases with NVMCI (versus HC), VMCI patients presented a higher BOLD activation in the right parieto-occipital cortex and a lower activation in the left superior and middle frontal gyri, anterior cingulum and in left fronto-opercular area when compared to HC. Cortical activation evaluated by fMRI may reflect specific patterns of damage and attempt of compensation in patients with MCI and different severity of leukoaraiosis.