THE MRI SIGNS OF SPINAL ARACHNOID DIVERTICULA

Our goal was to find MRI signs of use for identifying a spinal arachno id diverticulum. Three cases of spinal arachnoid diverticula, one extr adural and two intradural, were examined on a 1.5 Timager. There was o bvious mass effect on the adjacent structures in one case and increase d signal intensity in the diverticulum on proton density- and T2-weigh ted images in two cases. Signal changes due to turbulent movement of t he spinal fluid inside the diverticula were seen in all cases on sagit tal fast spin-echo (FSE) proton density- and T2-weighted images; it wa s difficult to tell whether these signal changes imply a communication or are simply FSE artefacts. On contrast-enhanced studies, all cases showed partial enhancement inside the diverticula. There thus are four signs of diverticula: mass effect, the increased signal, signal void sign and partial enhancement; the last of these, the most reliable, ha s never been reported before.