Some modifications, like the introduction diffusion-sensitizing gradients, must be tested in patients, since changes of tissue diffusion can only be observed in stroke victims. Once the researcher attained the first goal, (s)he may proceed with other modifications, e.g., modifications which will improve the temporal resolution. The completion of a new sequence, which ultimately may be used in a large normal subject or patient study, may involve a large number of design steps, where each step must be tested in one or a few subjects before development proceeds. Another scenario is the application of an existing patient protocol to different, existing, and FDA approved equipment. For example the need may arise to use a different radiofrequency coil (surface coil instead of head coil) or a scanner system with different magnetic field strength (3.0 Tesla instead of 1.5 Tesla). Several parameters, such as signal-to-noise ratio, or T1 and T2 weighting may change under such circumstances. In most cases only a study in a subject will reveal if protocol parameter settings are adequate. Therefore, this protocol is different from a conventional study, where exactly the same protocol will be applied to each of a large number of subjects. However, the protocol and the general procedures of data handling used during the different scans is similar enough, so it can be summarized into a general development protocol.