Detection of the Onset of Multiple Sclerosis from SD-OCT Thickness Measurements of the Retinal Nerve Fiber Layer

The cumulative sum (CUSUM) likelihood ratio detector (discussed in Lai [1995] and Frisen [2003]) can be used to monitor a process level against linear trend changes. In this article we discuss this detector and its relationship to the standard CUSUM, which guards against step changes in the level; provide software for its implementation; and present a case study that uses this method to detect the onset of multiple sclerosis.

The thickness of the retinal nerve fiber layer has been suggested as a diagnostic measure for evaluating the progression of multiple sclerosis. Newly improved optical coherence tomography (OCT) instrumentation using scan averaging and alignment with a reference scan has reduced the short-term measurement variability in the retinal nerve fiber layer thickness to an extent that allows the proposed CUSUM likelihood ratio detector to detect clinically relevant changes over time. We show that this procedure detects such changes quickly and performs better than the traditional CUSUM technique that protects against step changes in the level.