STP Reflections | 8 weeks in MR

Medical physicists face a challenge familiar to all healthcare scientists in that, if you took a random member of the public, and asked if they knew what a medical physicist did, the probability of a yes answer is… small!  My first evidence of this came when I tried to explain to my Mum what I would be doing at Addenbrookes for the next 8 weeks!

In all fairness, most medical physicists would struggle to provide an elevator pitch as to the job description but it certainly is hard to imagine modern healthcare without physics; the contributions of physics to healthcare are well known (X-rays, nuclear medicine, PET scanning, magnetic resonance spectroscopy, magnetoencephalography, high-intensity focused ultrasound with MRI, radiotherapy, fluoroscopy, interventional MRI, photonics, to name quite a few).  “Medical physicists have an especially important part to play; for example, in patient safety, ensuring the safe, as well as the effective, implementation of new physics-based health technologies” (https://www.thelancet.com/series/physics-and-medicine).  

This is why I really commend Jes and Adriana for the work they are doing here with STP Perspectives blog, in supporting healthcare scientist trainees as well as providing a platform for increased public awareness and engagement in healthcare science. In the words of Dr Cloutman-Green “Research is funded by the public, for the public, so why shouldn’t we be working with the public to … up-skill them so they can be more involved and engaged”. I too believe that the public should be more familiar with what goes on behind the scenes in a hospital in support of patient facing services.  To this end, I thought I might share some of my thoughts on the excellent experience I had during an eight-week rotation in MRI, with the aim of informing the public and for the benefit of future trainees.  

The starting point, for me, was MR hardware and safety.  The word “safety” here requires expounding.  MRI affords exquisite anatomical soft tissue contrast and it is considered a safe imaging modality, in that it does not use potentially harmful X-rays or radionuclides. However, MRI is the only medical imaging modality that can kill you instantly.  The MRI room is basically a human sized microwave (ignoring a frequency technicality) with a massive superconducting magnet.  It is this extremely strong magnet that poses the danger.  If sharp or heavy metallic objects are brought into the MR environment then there is a real risk of the so-called projectile affect.  A significant proportion of the training of medical physicists, for this reason, is substantiated around the hazards associated with MR environment and understanding all the procedures and protocols in place to make MR safe (I hope that’s a relief!). 

The MR environment is, of course, also equipped with some seriously impressive hardware.  A top of the range 3T scanner could set a trust back by over £2 million.  Being a budding physicist, it is hard to resist the temptation to talk at length about superconductivity, echo planar imaging, reduced k-space sampling and the rest of the physics that make MRI a clinically viable imaging modality.  In my opinion, the really clever bit in MRI is how which piece of tissue gave rise to which bit of the MR signal is determined, for this we have Paul Lauterbur and Sir Peter Mansfield to thank.  If you want more of the gory details DM me on Twitter @Stubbington2309.

I volunteered for two MRI research scans during my 8 weeks.  So from a patient perspective I can comment on how your visit to the MRI department might unfold.  You will be given a questionnaire, it is advisable to fill this out truthfully, as it is designed to identify any potentially hazardous items that you might unwittingly bring into the MR environment including tattoos, piercings, pace-makers or bullets.   Once you have donned the patient gown, the radiographers will make sure you are comfortable before landmarking your position and sliding you into the bore of the magnet.  It can be a bit of a tight fit, but rest assured the radiographers are at the other end of the panic alarm.  On the subject of radiographers, I encourage future trainees to schedule a few observations with the radiographers.  In speaking to them, you are guaranteed to learn a lot about how MR benefits patients and about how to navigate the pulse sequence jungle.  In my experience, they are a talented bunch of people with the patients’ best interests at heart and, despite being busy, are happy to talk through various aspects of what they do with trainees.   Once the radiographers have left, the interlock is secured and, just as you are beginning to get comfy, there will be a series of scratching and ticking sounds as the scanner figures out what frequency you like, before your peace is well and truly shattered by loud and obnoxious drilling sounds eminating from the bore of the magnet.  It is true that whilst the images from MRI are exquisite, the images can take a long time to acquire.   Typical examinations can vary from 20-60 minutes depending on what needs imaging. Being a volunteer I was fortunate enough to see my own kidneys, at the desk opposite mine, in the aftermath of my scan.  For the record, my guts look glorious!    

An important aspect of the MR physicist’s role is acceptance testing and ongoing QA of the MR machine. This, essentially, ensures in the first instance that the hospital is getting good value for the upfront cost of the scanner and safeguards against any degradation in performance over time. I was pleased to see that two sessions of phantom imaging had been scheduled for me.  As a physicist, there is something enormously gratifying about going into your scan room/lab with an object to image and getting out something that matches your expectation.  What I wasn’t prepared for was the near perfect synchrony between the data and theory. With my background in experimental biophysics, where, if you turn your monitor upside down, step back 10 yards and squint, there might just be a causal trend if you cross your fingers and stand your ground in discussions. I guess that is what you get when you have GE’s most expensive engineers developing your scanner.  

Another important component of the MR physicist’s life is academic, especially for uninitiated trainees.  To learn a lot of MR physics in a very short space of time, write down your questions and engage Andy Priest or Martin Graves, both at Cambridge University Hospital, in a face-to-face discussion.  As part of my many tutorials I also had the pleasure of attending an MR lecture at the Cavendish laboratory.  Whilst there I had the privilege to inspect one of J.J. Thompson’s cathode ray tubes and gawp at Maxwell’s desk, I felt the magnetism. 

A significant portion of what practicing MR physicists do evolves around developing and testing new pulse sequences for imaging.  For example, the emerging technique that I had the chance to appraise delivers an alternative means of quantifying blood perfusion in the brain.  This measurement is an important diagnostic tool in a host of neurodegernative diseases, such as stroke and dementia.  At the moment, the clinical protocol for measuring brain perfusion requires the administration of a Gadolinium-based contrast agent and there’s growing concern (and mounting evidence) that these drugs might not be so nice.  As a consequence, physicists are working hard at implementing an alternative means of measuring blood flow to the brain that uses only the cacophony of bangs and buzzes of the scanner hardware. 

Dan Sutcliffe explained that training is bracketed into the four disciplines of medical physics.  My MRI rotation fell under the remit of imaging with non-ionising radiation (although in my opinion these classifications are becoming increasingly old hat with the emergence of cross-disciplinary combined modalities, like PET-MR).   I can’t resist mentioning that I also benefited from a highly rewarding experience in ultrasound.  Ultrasound is everywhere and I believe you can even get an app to run ultrasound hardware from an iPhone these days.  Because of this ubiquity, it perhaps doesn’t harbour the same panache as its sexy non-ionising sister, MRI.  But the science underpinning ultrasound is engrossing and there is a highly active research community.  On top of this ultrasound can boast that it is the only imaging modality to benefit almost 100% of people born in the West, through prenatal scans.   

I realise that I haven’t offered much in the way of advice for future or current trainees as of yet. If I could summarise my experience in just 3 take home messages for future trainees, it would be the following. Firstly, be flexible.  Be prepared to work on submissions that appear further down the line.  If you can’t do X today, do the background reading for Y.  Secondly, be proactive in arranging discussions with the relevant members of staff, scheduling observations, timetabling scanner time etc. The best days you will have will be when you are talking and asking questions directly to the people who work with what you are interested in.  And finally, enjoy it! MRI is fantastic physics and on top of that, benefits the lives of countless numbers of patients every single day.  

Author: Liam

Trainee clinical scientist at the Ipswich Hospital.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s