Apoptosis plays a key role in many pathological circumstances, such as neurodegenerative diseases. In these processes, the involvement of nitric oxide (NO) has been well established, and the ability of NO to exert cellular damage due to its reactive oxidative properties is perhaps the primary neurotoxic mechanism. The caspase 3 activation has recently been observed in stroke, spinal cord trauma, head injury, and Alzheimer's disease. Although numerous techniques have been described to evaluate apoptosis, these approaches involve invasive techniques and cannot provide detailed information about apoptosis in vivo. In this chapter, we describe the use of functional magnetic resonance imaging (fMRI) as a non-invasive technique to detect apoptosis in vivo. fMRI techniques can detect apoptosis at early stages in the process, allowing the onset in intact biological systems, providing a useful tool for monitoring apoptosis progression.