Decreased retinal–choroidal blood flow in retinitis pigmentosa as measured by MRI
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To evaluate retinal and choroidal blood flow (BF) using high-resolution magnetic resonance imaging (MRI) as well as visual function measured by the electroretinogram (ERG) in patients with retinitis pigmentosa (RP).
MRI studies were performed in 6 RP patients (29–67 years) and 5 healthy volunteers (29–64 years) on a 3-Tesla scanner with a custom-made surface coil. Quantitative BF was measured using the pseudo-continuous arterial spin-labeling technique at 0.5 × 0.8 × 6.0 mm. Full-field ERGs of all patients were recorded. Amplitudes and implicit times of standard ERGs were analyzed.
Basal BF in the posterior retinal-choroid was 142 ± 16 ml/100ml/min (or 1.14 ± 0.13 μl/mm2/min) in the control group and was 70 ±19 ml/100ml/min (or 0.56 ± 0.15 μl/mm2/min) in the RP group. Retinal–choroidal BF was significantly reduced by 52 ± 8 % in RP patients compared to controls (P<0.05). ERG a- and b-wave amplitudes of RP patients were reduced, and b-wave implicit times were delayed. There were statistically significant correlations between a-wave amplitude and BF value (r=0.9, P<0.05) but not between b-wave amplitude and BF value (r =0.7, P=0.2).
This study demonstrates a novel non-invasive MRI approach to measure quantitative retinal and choroidal BF in RP patients. We found that retinal–choroidal BF was markedly reduced and significantly correlated with reduced amplitudes of the a-wave of the standard combined ERG.
KeywordsRetinal diseases Magnetic resonance imaging Electroretinography Retinal degeneration
This work was supported by a Clinical Translational Science Award Pilot Grant and a Translational Technology Resource grant (parent grant UL1TR000149), NIH/NEI (R01 EY014211 and EY018855), and Department of Veterans Affairs MERIT awards to TQD. YZ was supported by a Translational Science Training award through the University of Texas System Graduate Program Initiative.
Conflict of interest
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