Coronary MRA

Coronary X‐ray angiography is the gold standard for coronary artery imaging, but is an invasive procedure, with a minor risk of potentially serious complications in addition to the drawback of exposure to ionizing radiation. Coronary magnetic resonance angiography (MRA) is a noninvasive method of imaging the coronary arteries, with no known adverse effects. In addition to morphologic evaluation of coronary artery disease with coronary MRA, cardiac MRI offers exciting possibilities to study the functional significance of coronary artery disease in the same setting. Three widely used coronary MRA approaches are presented‐‐two free‐breathing navigator‐gated methods, and a breath‐hold method. Although the positive predictive value of coronary MRA for detecting stenoses remains lower than that of X‐ray angiography, coronary MRA can reliably detect anomalous origins of coronary arteries, and has a high negative predictive value for stenoses. In conclusion, coronary MRA is a promising tool to study coronary artery disease.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145393/1/cpmia1105.pd

Language Universals Engage Broca's Area

It is well known that natural languages share certain aspects of their design. For example, across languages, syllables like blif are preferred to lbif. But whether language universals are myths or mentally active constraints—linguistic or otherwise—remains controversial. To address this question, we used fMRI to investigate brain response to four syllable types, arrayed on their linguistic well-formedness (e.g., blif≻bnif≻bdif≻lbif, where ≻ indicates preference). Results showed that syllable structure monotonically modulated hemodynamic response in Broca's area, and its pattern mirrored participants' behavioral preferences. In contrast, ill-formed syllables did not systematically tax sensorimotor regions—while such syllables engaged primary auditory cortex, they tended to deactivate (rather than engage) articulatory motor regions. The convergence between the cross-linguistic preferences and English participants' hemodynamic and behavioral responses is remarkable given that most of these syllables are unattested in their language. We conclude that human brains encode broad restrictions on syllable structure

Using pulse oximetry to account for high and low frequency physiological artifacts in the BOLD signal.

The BOLD signal not only reflects changes in local neural activity, but also exhibits variability from physiological processes like cardiac rhythms and breathing. We investigated how both of these physiological sources are reflected in the pulse oximetry (PO) signal, a direct measure of blood oxygenation, and how this information can be used to account for different types of noise in the BOLD response. Measures of heart rate, respiration and PO were simultaneously recorded while neurologically healthy participants performed an eye-movement task in a 3T MRI. PO exhibited power in frequencies that matched those found in the independently recorded cardiac and respiration signals. Using the phasic and aphasic properties of these signals as nuisance regressors, we found that the different frequency components of the PO signal could be used to identify different types of physiological artifacts in the BOLD response. A comparison of different physiological noise models found that a simple, down-sampled version of the PO signal improves the estimation of task-relevant statistics nearly as well as more established noise models that may run the risk of over-parameterization. These findings suggest that the PO signal captures multiple sources of physiological noise in the BOLD response and provides a simple and efficient way of modeling these noise sources in subsequent analysis.</p

High-resolution diffusion-weighted imaging for the separation of benign from malignant BI-RADS 4/5 lesions found on breast MRI at 3T

Purpose: To determine whether readout‐segmented echo‐planar diffusion imaging (RESOLVE) improves separation of malignant versus benign lesions compared to standard single‐shot echo‐planar imaging (ss‐EPI) on BI‐RADS 4/5 lesions detected on breast magnetic resonance imaging (MRI). Materials and Methods: Consecutive 3T breast MRI studies with BI‐RADS 4/5 designation and subsequent biopsy or benign mastectomy were retrospectively identified. Freehand regions of interest (ROIs) were drawn on lesions and also on normal background fibroglandular tissue for comparison. Lesion‐to‐background contrast was evaluated by normalizing signal intensity of the lesion ROI by the normal background tissue ROI at b = 800. Statistical analysis used the Mann–Whitney/Wilcoxon rank‐sum test for unpaired and Wilcoxon signed‐rank for paired comparisons. Results: Of 38 lesions in 32 patients, 10 were malignant. Lesion‐to‐background contrast was higher on RESOLVE than ss‐EPI (1.80 ± 0.71 vs. 1.62 ± 0.63, P = 0.03). Mean apparent diffusion coefficient (ADC) was the same or lower on RESOLVE than ss‐EPI, and this effect was largest in malignant lesions (RESOLVE 0.90 ± 0.13; ss‐EPI 1.00 ± 0.13; median difference −0.10 (95% confidence interval [CI]: −0.17, −0.02) × 10−3mm2/sec; P = 0.014). By either diffusion method, there was a statistically significant difference between benign and malignant mean ADC (P &lt; 0.001). Conclusion: Increased lesion‐to‐background contrast and improved separation of benign from malignant lesions by RESOLVE compared to standard diffusion suggests that RESOLVE may show promise as an adjunct to clinical breast MRI