T1-weighted MRI contrast enhanced images showing focal contrast enhancment at 2 (a), 24 (b) and 72 (c) hours post-treatment, respectively. PDT treatments using 9 J (a,b,c) or 17 J (d,e,f) were performed at a fluence rate of 10 mW. All animals were scanned 15 minutes, following i.p. contrast injection. A localized contrast enhancement is clearly seen 2 and 24 hours following light treatment (a,b,d,e) for both 9 and 17 J. Images taken 72 hours following treatment with 9 J showed no enhancing regions (c) while reduced enhancement persisted up to day 7 following PDT with 17 J (f).