title: Decreased retinal-choroidal blood flow in retinitis pigmentosa as measured by MRI.
abstract: OBJECTIVE
  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.
authors: Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA.
authors: Yi
authors: Y
authors: Zhang
authors: Joseph M
authors: JM
authors: Harrison
authors: Oscar San Emeterio
authors: OS
authors: Nateras
authors: Steven
authors: S
authors: Chalfin
authors: Timothy Q
authors: TQ
authors: Duong
mesh_terms: D000328:Adult; D000368:Aged; D002829:Choroid / Q000098:blood supply* / Q000503:physiopathology; D004596:Electroretinography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology*; D012160:Retina / Q000503:physiopathology*; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000503:physiopathology*