At the moment BRU doesn't extract the image dimensions with the Exif data.
From the BRU help file:
ID3 / Exif Data > Extract Exif Data
Use this option to control whether or not EXIF tags will be extracted from photographs. At present only Date Taken, Aperture, Exposure, Focal Length, Exposure Compensation, Comments, Camera Model and Camera Make are extracted, but even this can slow down the processing. If you don't need these fields then leave this option unchecked to speed up the processing. Only files with the following extensions are processed: .JPG, .JPEG, .TIF, .TIFF, .CRW, .CR2, .NEF.