Relation of retinal and hippocampal thickness in patients with amnestic mild cognitive impairment and healthy controls.

OBJECTIVE: Investigating retinal thickness may complement existing biological markers for dementia and other neurodegenerative diseases. Although retinal thinning is predictive for cognitive decline, it remains to be investigated if and how this feature aligns with neurodegeneration elsewhere in the brain, specifically in early disease stages. METHODS: Using optical coherence tomography and magnetic resonance imaging, we examined retinal thickness as well as hippocampal structure in patients with amnestic mild cognitive impairment and healthy controls. RESULTS: The groups did not differ in hippocampal and retinal thickness measures. However, we detected a correlation of peripapillary retinal nerve fiber layer thickness and hippocampal thickness in healthy people but not in cognitively impaired patients. The ratio of hippocampus to retina thickness was significantly smaller in patients with mild cognitive impairment and correlated positively with cognitive performance. CONCLUSIONS: Different temporal trajectories of neurodegeneration may disrupt transregional brain structure associations in patients with amnestic mild cognitive impairment.

Influence of adenosine on ventricular function measurements as part of a comprehensive stress perfusion magnetic resonance imaging study.

BACKGROUND: Stress-rest perfusion magnetic resonance imaging (MRI) has become one of the major indications for cardiovascular MRI. Standard multibreath hold short-axis image acquisition is the gold standard for LV function assessment and part of a comprehensive stress-rest perfusion MRI study, but takes up to 10 min. The total scan time could significantly be shortened when cine imaging would be performed between stress and rest perfusion. PURPOSE: To systematically study whether adenosine, albeit its short half-life time, influences LV function measurements in this setting. MATERIAL AND METHODS: Thirty-nine patients with suspected and/or known coronary artery disease underwent 3-Tesla adenosine (140 µg/min/kg) stress-rest perfusion MRI. A stack of short-axis slices covering the entire ventricles was acquired before and ≥3 min after adenosine infusion using standard multibreath-hold 2D steady-state free precession imaging. LV volumes (EDV, ESV), EF, and mass were calculated by the slice summation method, and wall motion was assessed using a 4-point scoring scale. Reproducibility was assessed by Bland-Altman statistics. RESULTS: EDV, ESV, EF, and mass were not significantly different between the two imaging time points (before versus after adenosine administration) in all patients (P ≥ 0.346) and patients with impaired LV function (P ≥ 0.718). Wall motion scores did not differ either (P ≥ 0.124). Inter-observer variability before (P ≥ 0.468) and after (P ≥ 0.451) adenosine infusion was low. CONCLUSION: Short-axis cine imaging for LV function assessment can accurately be performed between stress and rest imaging. These data demonstrate that potential effects of adenosine on LV function are of short duration, and propose a new time-saving imaging protocol without compromising accuracy.