time-of-flight
Also written as: TOF — Time-of-Flight
MR angiography technique that creates vascular contrast based on blood flow without requiring contrast injection.
Full Definition
Time-of-flight (TOF) is a non-contrast MR angiography technique that exploits the flow-related enhancement of moving blood to create vascular images. The method relies on the principle that flowing blood enters the imaging volume with full longitudinal magnetization while stationary tissues become saturated by repeated radiofrequency pulses. This creates natural contrast between flowing blood (bright signal) and background tissues (suppressed signal). TOF angiography is particularly effective for imaging intracranial arteries and can be performed in two-dimensional or three-dimensional acquisition modes. The technique is especially valuable when gadolinium-based contrast agents are contraindicated.
Usage
Usage note: Specify 2D or 3D acquisition when relevant to the clinical context.
In Context
- "Time-of-flight angiography was performed to evaluate the circle of Willis." — MRI protocol description
- "TOF images demonstrated adequate flow in the carotid and vertebral arteries." — Stroke workup report