Diffusion sensitising for dynamic imaging and MRI

摘要

The MRI appts. has a magnet assembly (1) applying the main magnetic field and a gradient magnetic field using coils fed from a power source (2) with a gradient field drive circuit (3), a RF power amplifier (4) preamplifier (5). A computer (7) creates a pulse sequence and sends it to a sequence memory circuit (8). Based on the pulse sequence, the gradient magnetic field drive circuit operates to drive the gradient coils to produce gradient magnetic field. A gate modulation circuit (9) modulates the carrier signal produced by an RF oscillator (10) into a pulsative signal with a prescribed timing and envelope to deliver the resulting pulse to the power amplifier. The amplified RF pulse is applied to the transmission coil. The preamplifier amplifies the NMR signal received by a reception coil and delivers it to a phase detector, whose output is digitised and read by the computer.