Catherine Owen had been healthy all her life until she was floored by a mysterious viral infection while on holiday in Spain for Christmas in 2018.

Instead of easing after a few days, unpleasant symptoms including fatigue, headaches and loss of appetite continued to plague her for months and left doctors baffled.

"I was ill all the way through January and for months afterwards," said Ms Owen, who lives in Gorebridge in Midlothian.

"They couldn't find out what was wrong with me. I was very bunged up, lots of night sweats.

"At one point they thought it was bowel cancer, so they did various tests for that.

"Then they sent me to a general medicine consultant by which time I was finding it very difficult to get up and down the stairs."

READ MORE:

By the end of 2019, Ms Owen - a former actor who now officiates weddings and funerals as a celebrant for the Humanist Society Scotland charity - had lost a significant amount of weight and was suffering from polymyalgia rheumatica, a chronic inflammatory disease which causes pain and stiffness in the shoulders, neck, hips, and upper arms.

A CAT scan in November 2019 finally revealed the cause of her ill health: large vessel vasculitis (LVV), a condition where the aorta - the body's largest artery - and its branches become scarred and inflamed.

There are two main forms of LVV - giant cell arteritis (GCA) and Takayasu arteritis (TA).

Ms Owen had the former.

Scotland has some of the highest rates of GCA in the world, with an incidence of around 20 to 40 cases in every 100,000 people. It almost exclusively affects the over 50s.

Patients with TAK are mostly diagnosed as children or young adults.

This is much rarer - it is estimated that there are roughly 27 new cases of TAK in Scotland each year - but as LVV is incurable and potentially fatal without proper management, patients face the prospect of spending their life on medication, often with adverse side effects.

It is unclear exactly what causes LVV or why Scotland has such high rates of GCA, but the environment appears to be a factor.

Other countries with low levels of sunlight, such as Scandinavia, have similar GCA rates.

Genetics are also thought to play a role in LVV, and there is evidence that the condition can be triggered by viruses.

Catherine OwenCatherine Owen said the steroids used to treat her vasculitis left her feeling 'out of it'. She has now been able to reduce the dose from 55mg to 3mg per day (Image: Duncan McGlynn) Left untreated - or under-treated - it can cause severe complications such as strokes or aneurysms.

On the flipside, the primary treatment for LVV - glucocorticoid steroid hormones - carry risks of vision loss, gastric ulcers, and gastrointestinal bleeds, as well as depression from long-term use.

Dr Dan Pugh, a researcher at Edinburgh University's Centre for Cardiovascular Science, said: "This is a condition that involves inflammation in the big blood vessels - the blood vessels that supply the main route to organs and limbs.

"If one of those blood vessels is affected by the disease and is not treated properly, it will either block or burst. If it blocks, that interrupts the blood supply to that organ or limb.

"If that happens to the brain, it presents as a stroke. If that happens to an arm, you lose the function of that arm. If it happens to a kidney, you lose the function of that kidney.

"And if blood vessels rupture, that can be fatal. So the risk of not treating patients enough is serious because they can develop all of these complications.

"But there is also a risk of giving them too much treatment.

"If the treatments were well tolerated and safe, we would just give everyone loads of treatment, but the treatments themselves are toxic and come with side effects.

"Ideally we want to give just the right amount of treatment, and no more."

Dr Dan PughDr Dan Pugh said he hoped the research would encourage NHS Scotland to 'take note and invest' in PET-MRI so that patients can benefit outside of clinical trials (Image: DanPugh)

The dilemma facing doctors is that once they diagnose a patient with LVV and prescribe the steroids to reduce inflammation, they have no truly accurate way of gauging whether the treatment is working, whether the dose needs to be adjusted, or when a patient is relapsing.

Dr Pugh said it "comes down to guesswork" based on patients' symptoms because existing blood tests "are not particularly helpful" and the scans used to diagnose the disease are unsuitable for monitoring it.

It is a problem that Dr Pugh and his colleagues set out to solve when they embarked on a clinical trial in 2020 to test whether PET-MRI - a device not currently available on the NHS in Scotland - could provide the answer.

Ms Owen, 71, was among the 24 participants recruited onto the study, which has recently published its findings in the journal Nature.

The researchers took body scan results shortly after diagnosis and again after around six months of treatment.

They asked 18 specialist doctors to provide their clinical opinion of whether disease was active based on standard assessment and again using the PET-MRI results.

They found that doctors correctly identified active disease in 30% of cases without the scan, but in 90% of cases using PET-MRI.

For patients in remission, their accuracy was 52% using standard assessment compared to 84% with PET-MRI.

Ms Owen was among the patients whose scan confirmed that the disease had virtually disappeared as a result of steroid treatment, enabling her to reduce her daily dose from 55mg to 3mg now.

Her blood vessels had gone from looking "like fireworks", with inflammation showing up as a bright light all over her body, to lingering only in the aorta where lesions remain.

READ MORE: 

Knowing it was safe to cut down on her steroid medication has been a huge relief as it was leaving her feeling "out of it" most days and unable to engage in activities, like outdoor walks, which she normally enjoyed.

Ms Owen said: "My daughter said it was 'like you were out of it'. I'd be there but not engaging, not making much sense.

"You can't count, you can't work your computer.

"It all sounds so extreme, but in those moments it's like you're so confused that you can't do a simple sum or write a proper sentence.

"I spent a lot of hours watching 'Yorkshire Farm' and 'Escape to the Country' on television because it requires nothing of you, but it's all beautiful and most of the time harmonious."

She knows that her disease will relapse at some point, but - without access to additional scans - for now she is back to providing regular blood samples so that her rheumatologist can look for signals of possible inflammation.

A PET-MRI at the NHS Royal Hallamshire Hospital in YorkshireA PET-MRI at the NHS Royal Hallamshire Hospital in Yorkshire. Edinburgh University is currently home to Scotland's only PET-MRI scanner (Image: UniversityofSheffield)

Dr Pugh hopes that the Edinburgh University study will help to make the case for use of PET-MRI machines in the NHS, so that more vasculitis patients can benefit. 

He said: "This research answers the question: can we monitor the activity of the disease once treatment has started?

"Can we say, after six months of being treated with these heavy duty drugs, 'they've worked', or 'they've not worked - you need to change dose', or 'they've worked a bit - you need to keep going'.

"A test to say 'yes, the treatment worked, you're now in remission, you can come off the drugs or be on less' is what was missing - that's what we now have.

"The research that we've now published is clear that this PET-MRI scan can give us that information.

"At the moment, this type of scan is not available freely on the NHS.

"We have Scotland's only scanner at the moment, at Edinburgh University, but there are several in England and its popularity is spreading.

"PET-MRI is useful for a lot of other conditions too - principally cancers - and it's now being used from a research point of view in heart disease, and brain diseases like Alzheimer's.

 "The hope is that the NHS takes note and invests in this technology.

"It fits perfectly with [the prevention ethos] because these are lifelong conditions.

"If you get the treatment right upfront, you can prevent the bulk of the sickness and morbidity.

"That's what this scan has the potential to do: to get in there early, make sure the treatment is right, and prevent the consequences."