VISUALIZATION OF SUBTLE CONTRAST-RELATED INTENSITY CHANGES USING TEMPORAL CORRELATION

Contrast-enhanced magnetic resonance imaging (MRI) is a promising meth od for investigating the breakdown of the blood-retinal barrier (BRB). However, subtle intensity changes due to low concentrations of contra st agent can be difficult to detect without observer bias. In this stu dy, we developed a temporal correlation method for detecting these sub tle signal intensity changes. The method was evaluated in eyes with ch emically induced retinal lesions of known size. A time series of MRI d ata were collected following IV administration of different doses of g adolinium-diethylaminetriaminepentaacetic acid (0.05, 0.1, 0.5 mmol/kg ). These time course images were analyzed by temporal correlation to a reference enhancement curve. The reference curve was generated based on a validated theoretical enhancement curve. The temporal correlation method detected signal intensity changes in cases where the changes w ere too subtle to be visible on a postinjection image or a subtraction image (obtained by subtracting the precontrast image from the final i mage in the time course set). In addition, assessment of leakage was p erformed by viewing each image in the set with an eight gray-level pal ette. Areas of leakage identified in this manner corresponded to those identified by temporal correlation, a finding which supports the vali dity of the temporal correlation method. These results suggest that te mporal correlation may be a time-efficient way to screen large numbers of image data sets using an objective, user-independent criterion.