Can processed images be used to determine the modulation transfer function and detective quantum efficiency?

Purpose: The modulation transfer function (MTF) and detective quantum efficiency (DQE) of x-ray detectors are key Fourier metrics of performance, valid only for linear and shift-invariant (LSI) systems and generally measured following IEC guidelines requiring the use of raw (unprocessed) image data. However, many detectors incorporate processing in the imaging chain that is difficult or impossible to disable, raising questions about the practical relevance of MTF and DQE testing. We investigate the impact of convolution-based embedded processing on MTF and DQE measurements.

Direct SAR mapping by thermoacoustic imaging: A feasibility study.

Purpose: To develop a new method capable of directly measuring specific absorption rate (SAR) deposited in tissue using the thermoacoustic signal induced by short radiofrequency (RF) pulse excitation.

Theory: A detailed model based on the thermoacoustic wave generation and propagation is presented.

Methods: We propose a new concept for direct measurement of SAR, to be used as a safety assessment/monitoring tool for MRI.

Neonatal brain: regional variability of in vivo MR imaging relaxation rates at 3.0 T--initial experience.

Purpose: To retrospectively investigate regional in vivo magnetic resonance (MR) imaging transverse and longitudinal relaxation rates at 3.0 T in neonatal brain, the relationship between these rates, and their potential use for gray matter (GM) versus white matter (WM) tissue discrimination.

Materials And Methods: Informed parental consent for performance of imaging procedures was obtained in each infant.

Quantitative near infrared spectroscopy measurement of cerebral hemodynamics in newborn piglets.

Severely premature infants are often at increased risk of cerebral hemorrhage and/or ischemic injury caused by immature autoregulatory control of blood flow to the brain. If blood flow is too high, the infant is at risk of hemorrhage, whereas too little blood flow can result in ischemic injury. The development of a noninvasive, bedside means of measuring cerebral hemodynamics would greatly facilitate both diagnosis and monitoring of afflicted individuals.