Prevalence Of Motion Research Articles

Detection and correction of patient motion in dynamic 15O-water PET MPI

BackgroundPatient motion constitutes a limitation to 15O-water cardiac PET imaging. We examined the ability of image readers to detect and correct patient motion using simulated motion data and clinical patient scans.MethodsSimulated data consisting of 16 motions applied to 10 motion-free scans were motion corrected using two approaches, pre-analysis and post-analysis for motion identification. Both approaches employed a manual frame-by-frame correction method. In addition, a clinical cohort was analyzed for assessment of prevalence and effect of motion and motion correction.ResultsMotion correction was performed on 94% (pre-analysis) and 64% (post-analysis) of the scans. Large motion artifacts were corrected in 91% (pre-analysis) and 74% (post-analysis) of scans. Artifacts in MBF were reduced in 56% (pre-analysis) and 58% (post-analysis) of the scans. The prevalence of motion in the clinical patient cohort (n = 762) was 10%. Motion correction altered exam interpretation in only 10 (1.3%) clinical patient exams.ConclusionFrame-by-frame motion correction after visual inspection is useful in reducing motion artifacts in cardiac 15O-water PET. Reviewing the initial results (parametric images and polar maps) as part of the motion correction process, reduced erroneous corrections in motion-free scans. In a large clinical cohort, the impact of motion correction was limited to few patients.

Toward an Olfactory Language System

The lack of a scent discourse in art restricts our cultural understanding of olfaction. Part of this lack is attributable to an impoverished vocabulary for scent. Throughout Western culture, scents are referred to by their observable, visual counterpart, such as “banana.” However, looking at cultural factors that influence our sensorial vocabulary, researchers Asifa Majid and Niclas Burenhult have noted a more diverse vocabulary for olfactory phenomena in the Jahai language (spoken in parts of Malaysia and Thailand). Considering the possibilities of such extended scent vocabulary system, this article describes preliminary attempts to generate such terminology through a panel experiment at the Hammer Museum. In the results of the panel experiment, the prevalence of motion, tactile, and physical contour–related descriptors points to an almost uncanny relationship between the tactile and the olfactory. The sense of olfaction, like the tactile sense, often evokes metaphors of movement along a surface . This enlarged sensory vocabulary for describing scent would increase our ability to conceive of, and communicate, possible experiences within our material world, with potential implications for museum practitioners and preservationists.

Distribution of Pico- and Nanosecond Motions in Disordered Proteins from Nuclear Spin Relaxation

Intrinsically disordered proteins and intrinsically disordered regions (IDRs) are ubiquitous in the eukaryotic proteome. The description and understanding of their conformational properties require the development of new experimental, computational, and theoretical approaches. Here, we use nuclear spin relaxation to investigate the distribution of timescales of motions in an IDR from picoseconds to nanoseconds. Nitrogen-15 relaxation rates have been measured at five magnetic fields, ranging from 9.4 to 23.5 T (400–1000 MHz for protons). This exceptional wealth of data allowed us to map the spectral density function for the motions of backbone NH pairs in the partially disordered transcription factor Engrailed at 11 different frequencies. We introduce an approach called interpretation of motions by a projection onto an array of correlation times (IMPACT), which focuses on an array of six correlation times with intervals that are equidistant on a logarithmic scale between 21 ps and 21 ns. The distribution of motions in Engrailed varies smoothly along the protein sequence and is multimodal for most residues, with a prevalence of motions around 1 ns in the IDR. We show that IMPACT often provides better quantitative agreement with experimental data than conventional model-free or extended model-free analyses with two or three correlation times. We introduce a graphical representation that offers a convenient platform for a qualitative discussion of dynamics. Even when relaxation data are only acquired at three magnetic fields that are readily accessible, the IMPACT analysis gives a satisfactory characterization of spectral density functions, thus opening the way to a broad use of this approach.