PET-CT in diagnosing dementia:


Why bother and who is going to pay for it? David Fitzgerald


In the absence of disease-modifying treatments, some may find it difficult to justify funding services that provide the latest imaging techniques for diagnosing dementia.


P


F-FDG PET-CT) is an established technique for assisting in the differential diagnosis of mild cognitive impairment, Alzheimer’s disease, vascular dementia, dementia with Lewy bodies and fronto-temporal


ositron emission tomography fluorine-18 fluorodeoxyglucose integrated with computed tomography (18


dementia. Amyloid PET-CT imaging is another technique recommended in specific circumstances for differentiating between normal subjects and various dementias. However, these imaging techniques are not centrally funded and this is preventing their widespread implementation in the early diagnosis of dementia, particularly Alzheimer’s disease. Without disease-modifying treatments currently being available, it is difficult to determine if these are services that should be funded before the drugs required to reverse the effects are developed. The Alzheimer’s Society estimates that in 2015 there are 850,000 people with dementia in the United Kingdom (UK) and predicts that this will rise to one million by 2025. It also states that the financial cost related to dementia is £26 billion per year1


. The most startling statistic from the Alzheimer’s Society is that only 44% of people with


dementia in England, Wales and Northern Ireland receive a diagnosis. This may lead to the conclusion that there are no diagnostic tests that can aid pure clinical assessment in the diagnosis of dementia. However, nuclear medicine has been providing a number of imaging studies successfully, to aid the diagnosis of dementia including HMPAO single photon emission computed tomography (SPECT) studies and 18


F-FDG and amyloid imaging PET-CT studies over 10 years at least. This article will cover the use of 18 F-FDG


and amyloid imaging PET-CT studies only. World leaders are taking dementia seriously – UK Prime Minister David Cameron introduced the first international dementia summit at the 2013 G8 meeting and was quoted as saying at the Alzheimer’s Society Conference in 2012: “One of the greatest challenges of our time is what I’d call the quiet crisis, one that steals lives and tears at the hearts of families, but that relative to its impact is hardly acknowledged. We’ve got to treat this like the national crisis it is. We need an all-out fight-back against this disease; one that cuts across society2


." -26-


In December 2013, the Secretary of State for Health showed commitment by signing up to the 'G8 Dementia Summit Declaration' alongside health ministers from Canada, France, Germany, Italy, Japan, Russia and the USA3


Dementia is a significant and increasing burden on the health economy and this is one of the major factors behind the international drive to research, treat and cure it. Approximately 75,000 PET-CT scans were performed in England during 2013/20144


but the majority of these should have been for oncology indications based on the NHS England Clinical Commissioning Policy Statement5 .


Only 10% of the oncology activity was allowed, at the discretion of the ARSAC (administration of radioactive substances advisory committee) licence holder, to be used for non-oncology indications. At most, this could mean that in England 7500 scans may have been performed for diagnosing dementia. However, this is unlikely as the 10% discretion was permitted for a number of indications and not just dementia diagnosis. This compares with over three million CT scans and over two million MRI scans performed in England during 2013/20144


.


The 30 to 44 fold difference between the activity for PET-CT scans and MRI/CT activity respectively, indicates the disparity in access between the different modalities. Limited access to PET-CT imaging facilities is probably one factor but with more facilities becoming available and improvements in scanner technology leading to faster scans, this is becoming less of an issue. The question therefore remains, that if diagnostic imaging exists, able to support clinicians in establishing the diagnosis of dementia and potentially allowing treatment and/or support for patients earlier, why is it not used more widely? The lack of appropriate commissioning is certainly one very important factor. However, a lack of randomised control trials and large scales reviews studying the effectiveness of 18F-FDG and amyloid PET-CT imaging, is


probably impeding an evidence-based approach to approving the commissioning of these services. Dementia


Dementia is a syndrome where patients develop a deterioration in memory, thinking and behaviour and the ability to perform everyday activities6


dementia with Lewy bodies and fronto-temporal dementia. . This syndrome includes vascular dementia, Alzheimer’s disease, .


. CT and MRI scans are recommended by the National Institute for Health and Care Excellence in order to exclude other cerebral pathologies in those suspected of a dementia diagnosis from clinical examination6


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