T2W MRI images following ALA administration without illumination (A), 26 J ALA PDT (B), 1 J interstitial illumination following 5 mg/kg of AlPcS2a PDT (C), and 1 J surface illumination following 5 mg/kg of AlPcS2a PDT (D). No edema is seen without illumination (A), large spherical edematous reactions is seen following interstitial light delivery (B,C), with change in shape to hemispherical following surface illumination (D).