Image of the Month

Image of the Month


Photoacoustic imaging from CABI on the front cover of nature photonics. Click the image to read the article.

Arterial spin labelling

Arterial spin labelling (ASL) is an established technique, based on MRI, and is typically used to measure blood flow in the brain and heart. A main advantage of ASL over other techniques is that it does not require a contrast agent to be injected, instead using radiofrequency pulses to discriminate between static and flowing fluid. These measurements are then used in numerical models to quantify blood flow. Rajiv Ramasawmy’s PhD project is focussed on using ASL to measure blood flow in liver tumours, which is particularly challenging as the liver moves significantly during the respiratory cycle and has two separate blood supplies (portal and arterial). Using a range of ‘gating’ techniques, he has developed a technique for measuring liver blood flow, which he is now using to assess response to therapy using a class of drug known as a vascular disrupting agent.
Arterial spin labeling of liver tumours

Figure 1: Examples of axial, T2-weighted fast spin echo images of a liver with metastases (examples outlined) (A,C) and its corresponding perfusion map (B,D). The liver ROI selected to calculate the perfusion map can be seen as a dashed line in (A,C). Low perfusion can be seen at the locations of the metastases, outlined on (B,D). High perfusion can be seen at blood vessels such as the IVC (long arrow (B,D)) and the aorta (short arrow (B)).

Associated publications:

Ramasawmy R, Campbell A, Johnson SP, Wells J, Predley RB, Lythgoe MF, Walker-Samuel S, Look-Locker arterial spin labelling (ASL) of liver metastases, Proceedings of the British Chapter of the International Society for Magnetic Resonance in Medicine, 2011 (Manchester).

Page last modified on 19 jan 12 14:20