Abstract: Pulsatile flow is measured using magnetic resonance imaging without cardiac gating using a phase-contrast excitation method to rapidly quantify blood flow and using a spiral k-space trajectory for image data read-out to mitigate deleterious effects of pulsatility. Post-processing of the read-out data provides a cumulative-average velocity plot from which a period of a cardiac cycle is obtained. Time-averaged blood flow rates can be rapidly and robustly measured and is more repeatable than conventional gated techniques.

Abstract: Pulsatile flow is measured using magnetic resonance imaging without cardiac gating using a phase-contrast excitation method to rapidly quantify blood flow and using a spiral k-space trajectory for image data read-out to mitigate deleterious effects of pulsatility. Post-processing of the read-out data provides a cumulative-average velocity plot from which a period of a cardiac cycle is obtained. Time-averaged blood flow rates can be rapidly and robustly measured and is more repeatable than conventional gated techniques.

Abstract: A negative film image conversion apparatus for a video camera which is capable of obtaining an image of the same color and luminance as those of a real image upon shooting of a negative film as well as a general object. The negative film image conversion apparatus comprises a signal processor for obtaining a luminance signal and a plurality of color difference signals from an image signal inputted therein, a subtracter for subtracting the luminance signal from the signal processor from a predetermined reference signal, inverters for inverting the plurality of color difference signals from the signal processor, individually, and an encoder for combining output signals from the subtracter and the inverters and outputting the combined signal as a composite video signal.

Abstract: A vignetting compensating circuit for a video camera utilizing the horizontal synchronizing signal and the vertical synchronizing signal. The circuit prevents vignetting on the screen from a signal generated by a video camera with a zoom lens by obtaining and adding inverse parabolic wave form voltages corresponding to the cycles of the horizontal synchronizing signal and the vertical synchronizing signal and controlling the amplification factors of a voltage controlled amplifier for the video signal by the added voltage.