Nicholas G. Dowell1, Edward H. Hughes2, Paul S. Tofts1
Accurate and precise T1 mapping of the eyeball is difficult due to eye movement and image distortions. An accurate measure of T1 could provide a non-invasive determination of eye oxygenation since T1 times are subtly increased by reduced partial pressure of oxygen (pO2) of the vitreous humour in the eye. Poor oxygenation leads to retinopathy and, in patients with low pO2 at the retina, a vitrectomy may be performed, where the vitreous humour is extracted and replaced by saline. However, there is no clear evidence that an increase in pO2 is actually achieved by this procedure and MRI would provide an important validation for ophthalmologists. We have developed a technique, using a TrueFISP acquisition sequence, which provides eye images with no movement artefacts, no image distortion and good SNR. This permits the measurement of T1 (and hence pO2) from the vitreous humour of the human eye. Furthermore, we show that asking a subject to fixate on a single point can control eye movement but the need to blink limits fixation to < 5 s. Consequently, we will provide an audio/visual cue that warns the subject when they must fixate. This approach to eye imaging could dramatically improve imaging of the eye and retina.