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Decreased retinal-choroidal blood flow in retinitis pigmentosa as measured by MRI
Yi Zhang1, Joseph M Harrison, Oscar San Emeterio Nateras
1Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA.
Purpose:
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).
Methods:
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.
Results:
Basal BF in the posterior retinal-choroid was 142 ± 16 ml/100ml/min (or 1.14 ± 0.13 μl/mm(2)/min) in the control group and was 70 ±19 ml/100ml/min (or 0.56 ± 0.15 μl/mm(2)/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).
Conclusions:
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.
Insights
Retinitis pigmentosa (RP) patients show significantly reduced retinal and choroidal blood flow (BF) measured by MRI. This reduced blood flow correlates with specific electroretinogram (ERG) abnormalities, indicating a potential new diagnostic approach.
Area of Science:
- Ophthalmology
- Medical Imaging
- Neuroscience
Background:
- Retinitis pigmentosa (RP) is a group of inherited diseases causing progressive vision loss.
- Current understanding of RP pathophysiology lacks detailed information on vascular changes.
Purpose of the Study:
- To assess retinal and choroidal blood flow (BF) in RP patients using high-resolution MRI.
- To correlate BF measurements with visual function assessed by electroretinogram (ERG).
Main Methods:
- Quantitative BF was measured using pseudo-continuous arterial spin-labeling MRI in 6 RP patients and 5 healthy controls.
- Full-field ERGs were recorded to analyze amplitudes and implicit times.
Main Results:
- Retinal-choroidal BF was significantly reduced by 52% in RP patients compared to controls.
- ERG a-wave amplitudes correlated significantly with BF values, while b-wave amplitudes did not.
Conclusions:
- A novel non-invasive MRI method can quantify retinal and choroidal BF in RP.
- Markedly reduced BF in RP patients is linked to reduced a-wave amplitudes on ERG.
