The “Sequence” of Events

When we talk about “sequences” we mean the particular pattern of applied magnetic fields we have used to acquire the images. Each sequence is useful for different properties of the imaged material and we often have to compare the signal characteristics on different sequences to figure out what it is we are looking at.

We have to acquire the relevant sequences at the time of the imaging. We cannot go back and create these sequences from the available data. We also need to acquire the relevant projections (e.g. sagittal, axial, coronal) at the time of imaging, unless we have acquired 3D volumetric studies that we can reconstruct. It is, therefore, important to know which sequences we think we’re going to need based on the clinical history otherwise the patient will have to be called back for further imaging.

The science of MRI is constantly evolving with more and more sequences being developed but there are, luckily, only a few that you need to know about to be able to interpret an MRI study.