BACKGROUND Echo-state networks (ESN) are part of a group of reservoir computing methods and are basically a form of recurrent artificial neural networks (ANN). These methods can perform classification tasks on time series data. The recurrent ANN of an echo-state network has an 'echo-state' characteristic. This 'echo-state' functions as a fading memory: samples that have been introduced into the...

One of the most common methods for making images with ultrasound is to use the pulseecho method. The basic idea is to determine the time delay between different echoes from different points on the object. This method assumes that the echoes only differ in arrival time. If the shape of the echo is dependent on where on the surface it is reflected, this method can yield an inaccurate image. To be...

A robust modification of echo-planar imaging dubbed double-shot echo-planar imaging with center-out trajectories and intrinsic navigation (DEPICTING) is proposed, which permits imaging at ultra-short echo time. The k-space data is sampled by two center-out trajectories with a minimal delay achieving a temporal efficiency similar to conventional single-shot echo-planar imaging. Intersegment phas...

PURPOSE To compare six MR sequences (plain and gadolinium-enhanced fat suppressed T1-weighted spin echo, T2-weighted standard spin echo, fat-suppressed and non-fat-suppressed T2-weighted fast spin echo, and inversion-recovery T2-weighted fast spin echo) in their ability to detect, delineate, and characterize lesions of the parotid gland. METHODS Fifty-eight parotid gland lesions imaged on 47 ...

The diffusion in the magnetic dipolar field around a sphere is considered. The diffusion is restricted to the space between two concentric spheres, where the inner sphere is the source of the magnetic dipolar field. Analytical expressions for the CPMG transverse relaxation rate as well as the free induction decay and the spin echo time evolution are given in the Gaussian approximation. The infl...

Functional magnetic resonance imaging (MRI) with gradient echo and echo-planar sequences was applied to healthy volunteers and neurological patients to evaluate the feasibility of detecting and localizing the motor cortex. Time course of the change in signal intensity by an alternate repetition of motor task (squeezing hand) and rest periods was also examined. The motor cortex was localized as ...

PURPOSE To compare conspicuousness of head and neck lesions on fast spin-echo sequences and conventional spin-echo sequences. METHODS Forty consecutive patients with 61 head and neck lesions were evaluated. Lesion conspicuousness was qualitatively compared on conventional spin-echo and fast spin-echo sequences, using both spin-density and T2-weighted images. Thirty-six lesions had surgical or...

BACKGROUND AND PURPOSE 2D gradient-echo imaging is sensitive to T2* lesions (hemorrhages, mineralization, and vascular lesions), and susceptibility-weighted imaging is even more sensitive, but at the cost of additional scan time (SWI: 5-10 minutes; 2D gradient-echo: 2 minutes). The long acquisition time of SWI may pose challenges in motion-prone patients. We hypothesized that 2D SWI/phase unwra...

Purpose: Multi-echo Dixon-based methods have recently gained attention for use in contrast-enhanced MR angiography (CE-MRA) due to their ability to suppress the high signal from fat while avoiding subtraction errors due to motion between preand post-contrast images in subtraction CE-MRA. Additionally, multi-echo Dixon CE-MRA provides improved signal-to-noise ratio (SNR) and contrast-to-noise ra...