PURPOSE To optimize 3D radial ultrashort echo time MRI for high resolution whole-lung imaging. METHODS 3D radial ultrashort echo time was implemented on a 3T scanner to investigate the effects of: (1) limited field-of-view excitation, (2) variable density readouts, and (3) radial oversampling. Improvements in noise performance and spatial resolution were assessed through simulation and phanto...

This paper describes a new highly accurate fast selfcontained sonar sensor. Transmission and echo analysis are performed at repetition rates exceeding 27 Hz for ranges to 5.4 metres. The sensor contains low noise variable gain preamplifiers, two 1 MHz 12 bit ADC receivers and a DSP echo processor. Optimal arrival time estimation is performed by the DSP using matched filtering of echoes with sho...

Introduction: Two techniques have been presented in the last year to acquire both angiographic and venographic information in a single acquisition (MRAV) using susceptibility weighted imaging (SWI). One uses a double echo approach with the shorter echo used for the angiography and the longer echo used for the venography (1). The other uses a single echo that is a compromise between the two with...

PURPOSE To compare the sensitivity of conventional spin-echo, fast spin-echo, fast fluid-attenuated inversion recovery (FLAIR), and turbo gradient spin-echo MR sequences in the detection of multiple sclerosis lesions. METHODS Conventional spin-echo, fast spin-echo, fast FLAIR, and turbo gradient spin-echo sequences were performed on a 1.0-T MR imager in seven patients with clinically definite...

PURPOSE To determine optimal MR gradient-echo sequences for the visualization of calcium in neurologic MR. METHOD The dependence of signal intensity and image contrast on the imaging parameters repetition time, echo time, flip angle, and spoiling were measured for hydroxyapatite samples. Calculations of signal intensity were shown to correspond to these measures. RESULTS Optimum detectabili...