Optical Density of Subretinal Fluid in Retinal Detachment.

PURPOSE: To investigate the changes over time in optical density (OD) characteristics of subretinal fluid (SRF) in rhegmatogenous retinal detachment (RRD) and their clinical relevance. METHODS: The study included patients with first-onset RRD and no history of intraocular illness who underwent optical coherence tomography (OCT) and whose OCT scans showed sufficient SRF for sampling (08/2013-09/2014). The highest quality B-scan (as graded by the OCT image acquisition software) containing SRF was analyzed. Optical density measurements were obtained using ImageJ. Optical density ratios (ODRs) were calculated as SRF OD divided by vitreous OD. Time from onset of RRD was determined by first signs of visual loss as described in the patient's anamnesis. Patients were divided into three groups by RRD duration: acute (≤1 week), subacute (between 1 week and 1 month), and chronic (>1 month). RESULTS: Thirty-five eyes (34 patients) met the inclusion criteria. The ODR measurement was significantly associated with RRD duration. The ODR had a significant (P < 0.0001) association with the 3-month postoperative visual acuity (VA). Vitreous OD did not differ significantly between the three groups. CONCLUSIONS: The increase over time in the ODR of the SRF in RRD might reflect a change in SRF composition and state of the retina. This, together with a significant association between preoperative ODR values and postoperative VA suggest its potential as a biological prognostic marker.

Differential optical density of subretinal spaces.

PURPOSE: We investigated the optical density characteristics of 3subretinal spaces in neovascular age-related macular degeneration (AMD), diabetic retinopathy (DR), rhegmatogenous retinal detachment (RRD), central serous retinopathy (CSR), retinoschisis (RS), and pseudophakic cystoids macular edema (PCME). METHODS: Patients in whom subretinal fluid (SRF) was detected by optical coherence tomography (OCT), and whose earliest OCT scans showed sufficient SRF for sampling that did not include tissue edges, were chosen for study. The highest quality B-scan containing SRF (as graded by the OCT image acquisition software) was analyzed. Optical density measurements were obtained using ImageJ, an open code Java-based image processing software. RESULTS: The diagnoses of the 71 patients who met the inclusion criteria were AMD in 17, DR in 7, RRD in 18, CSR in 17, RS in 8, and PCME in 4. Optical density ratios (ODRs) were calculated as SRF OD divided by vitreous OD. ODRs were significantly higher in patients with AMD, DR, CSR, and PCME than in those with RRD and RS. No significant difference in vitreous reflectivity was detected between the former and latter patients. CONCLUSIONS: The finding that disease states produce significant changes in optical density ratios calls for further investigation of the possible usefulness of the parameter in differentiating between disease states, determining the outcome of various retinal diseases, and designing therapies aimed at treating the disease by correcting the abnormal density.

The application of MRI for depiction of subtle blood brain barrier disruption in stroke.

The development of imaging methodologies for detecting blood-brain-barrier (BBB) disruption may help predict stroke patient's propensity to develop hemorrhagic complications following reperfusion. We have developed a delayed contrast extravasation MRI-based methodology enabling real-time depiction of subtle BBB abnormalities in humans with high sensitivity to BBB disruption and high spatial resolution. The increased sensitivity to subtle BBB disruption is obtained by acquiring T1-weighted MRI at relatively long delays (~15 minutes) after contrast injection and subtracting from them images acquired immediately after contrast administration. In addition, the relatively long delays allow for acquisition of high resolution images resulting in high resolution BBB disruption maps. The sensitivity is further increased by image preprocessing with corrections for intensity variations and with whole body (rigid+elastic) registration. Since only two separate time points are required, the time between the two acquisitions can be used for acquiring routine clinical data, keeping the total imaging time to a minimum. A proof of concept study was performed in 34 patients with ischemic stroke and 2 patients with brain metastases undergoing high resolution T1-weighted MRI acquired at 3 time points after contrast injection. The MR images were pre-processed and subtracted to produce BBB disruption maps. BBB maps of patients with brain metastases and ischemic stroke presented different patterns of BBB opening. The significant advantage of the long extravasation time was demonstrated by a dynamic-contrast-enhancement study performed continuously for 18 min. The high sensitivity of our methodology enabled depiction of clear BBB disruption in 27% of the stroke patients who did not have abnormalities on conventional contrast-enhanced MRI. In 36% of the patients, who had abnormalities detectable by conventional MRI, the BBB disruption volumes were significantly larger in the maps than in conventional MRI. These results demonstrate the advantages of delayed contrast extravasation in increasing the sensitivity to subtle BBB disruption in ischemic stroke patients. The calculated disruption maps provide clear depiction of significant volumes of BBB disruption unattainable by conventional contrast-enhanced MRI.