Which intracranial lesions would be suitable for 5-aminolevulenic acid-induced fluorescence-guided identification, localization, or resection? A prospective study of 114 consecutive intracranial lesions.

5-Aminolevulenic acid (ALA) is a naturally occurring compound in all living mammalian cells.13 ALA is formed within the mitochondria from glycine and metabolized along a pathway in the cytosol and mitochondria into protoporphyrin-IX (PpIX) before combining with ferrous to form heme.6,12,14,15 The transformation from PpIX to heme is a rate-limiting step in all tumor cells leading to accumulation of PpIX in the mitochondria of these cells.6,12,14,15 PpIX fluoresces under blue light, and its fluorescence can be observed leading to the application of fluorescence-guided resection (FGR) and fluorescence image-guided surgery (FIGS).6,14,15 Stummer et al.14 reported a prospective, uncontrolled series of high-grade gliomas in 2000 and concluded that ALA-induced FGR was very specific and highly sensitive and led to complete resection of enhanced tumor tissue in more than 60% of patients. The ALA study group reported a randomized, controlled trial (RCT) in which the study population had high-grade gliomas removed using ALA-induced FGR.15 Gross total resection was accomplished in 65% of the study group compared with 35% of the controls (P 0.001), with a tumor-free survival gain of more than 6 weeks (P 0.001).15 Eljamel et al6 reported an RCT in which ALA Photofrininduced FIGS and repetitive photodynamic therapy (PDT) were used and demonstrated that complete surgical resection was achieved in 77% of the study group, with a tumor-free survival gain of 3.8 months. This study prospectively explored the use of ALAinduced fluorescence in a wide range of intracranial tumors that may benefit from this technology in terms of intraoperative localization or gross total resection.