Arjen Lindenholz
Intracranial vessel wall imaging is an emerging MRI technique that is increasingly being used in clinical practice. The ability to depict and analyze the intracranial vessel wall itself, rather than luminal changes, has already shown its value in an increasing number of intracranial arterial diseases, such as vasculitis and intracranial atherosclerosis.
Most of these sequences, however, have a relatively long acquisition time, varying from 5–10 minutes, which is doubled when acquiring both pre- and postcontrast images. This is a result of the high spatial resolution that is required to visualize the thin walls of the intracranial vasculature, together with the time-consuming methods to null both intraluminal blood and extraluminal cerebrospinal fluid.
Although these long acquisition times posed no problem when intracranial vessel wall sequences were first introduced in a research setting several years ago, the challenges arising with their clinical use have become increasingly more obvious. Not only does the addition of such long sequences to existing protocols result in encroachment of the predefined examination time slots, but it also increases the risk of movement artifacts, with detrimental effects on image quality.
In our study, we therefore aimed to develop a faster intracranial vessel wall sequence at 3T without sacrificing image quality, which is challenging in MR pulse sequence development. Six different variants with various trade-offs between scan parameters were qualitatively and quantitatively assessed for image quality and compared with our clinically used sequence (6:42 minutes). The scan time of the fastest vessel wall sequence that we have tested amounts to 4:39 minutes, which is 30% faster than our clinically used variant.
Our results show that sufficient image quality required for assessment could be maintained in this 30% faster vessel wall sequence. This intracranial vessel wall sequence is currently being used in our clinic when assessment of the vessel wall is needed. Especially in children or patients with neurologic disabilities, who are prone to move during the MRI examination, this sequence has been shown to be easier to use.