Q&A with Robert Claeser, Markus Zimmermann, and N. Jon Shah

In today’s interview, we discuss the latest paper by Robert Claeser, Markus Zimmermann, and N. Jon Shah from the Institute of Neuroscience and Medicine at the Jülich Research Centre in Germany. Their paper presents a gradient-delay corrected implementation of the spiral TAPIR (T1 mapping with partial inversion recovery) pulse sequence, which was used to acquire sub-millimeter T1 maps of rapidly relaxing compartments.

For those who would like to get a quick overview of our discussion, below is an annotation of the interview. Clicking on the timestamp will take you to the exact video location where the topic is discussed.

00:33 Audioslides: Robert Claeser provides a 5 minute overview of their paper. Spiral TAPIR (using short and long TR spirals) was implemented to overcome limitations of the conventional cartesian TAPIR sequence (induced T2* and off-resonance effects due to the long TE and TRs, and lower T1 accuracy for short T1 and T2* values).

06:26 The authors give us an overview of their backgrounds. Robert first got involved with MRI through his digital imaging and electrical engineering background. Markus also has an electrical engineering background, and became into this topic through his interest of compressed sensing. Jon started off in low temperature physics and NMR spectroscopy before transitioning to MRI research. In particular, he was intrigued with the mantra of his lab in Cambridge, which was “NMR is a quantitative technique, but MRI is not. Let’s try to make MRI quantitative as well.

08:52 Asked about what else needs to be done to improve the widespread use of this technique, Robert mentions that the undersampling factor could be easily increased due to the high SNR available, and that optimizing the image reconstruction process to make it quicker would also be helpful.

09:34 Potential applications of this pulse sequence could be in dementia research, as the short acquisition time could be beneficial for this patient cohort. Also, because this technique probes the fast relaxing components, it could be useful for other neurological diseases where myelin content plays a role, such as multiple sclerosis.

10:52 As with many other sequences, the difficulty of implementing this pulse sequence will vary depending on the pulse sequence programming platform available. In particular, some platforms only offer standard tools to develop cartesian sequences, and so spiral pulse sequence development can be more challenging. Also, some modern platforms have hidden away the ability to configure low-level parameters like the gradient delay correction.

13:12 Jon implies that many people don’t pay enough attention to accuracy and precision, and shares his opinion that the whole of quantitative imaging lives and dies by it. Although sub-1 millimeter resolution quantitative imaging has been achievable for a few years not, sub-1 percent accuracy has been a goal and challenge for many years, possibly due to partial voluming or movement.

15:37 The authors share what they enjoy doing as pastimes.