602
(DDNP), binds to synthetic beta-amyloid(1–40) fi brils, neurofi brillary tangles
(NFTs) and amyloid plaques in human AD brain specimens.
18 F-FDDNP, in conjunction with PET, can be used to determine the localization and
load of NFTs and Aβ senile plaques in the brains of living AD patients. Greater accu-
mulation and slower clearance is observed in amyloid plaque- and NFT-dense brain
areas and correlated with lower memory performance scores. The relative residence
time of the probe in brain regions affected by AD is signifi cantly greater in patients
with AD than in control subjects. This noninvasive technique for monitoring AP and
NFT development is expected to facilitate diagnostic assessment of patients with
AD and assist in response-monitoring during experimental treatments.
There is loss of glucose metabolism in AD usually measured by FDG-PET. This
can also be measured by^11 C-PIB and the slope values correlate with the fi ndings of
FDG dementia index.^123 I-QNB SPECT can demonstrate M1 muscarinic receptor
binding in AD. There is increased M1 binding in donepezil responders as compared
to non-responders.
Commercial Development of Molecular Imaging
Companies developing molecular imaging have a considerable interest in develop-
ing personalized medicine. Three major companies – GE, Philips and Siemens –
involved in producing imaging equipments such as MRI and PET for healthcare
applications, are interested in these developments. Amersham Healthcare, North
American Scientifi c Inc and Schering AG provide imaging agents.
Molecular imaging and diagnostics (MID) is being developed by Philips Medical
Systems, a part of Royal Philips Electronics. New imaging, diagnostic and
therapeutic techniques arising from MID will cause a paradigm shift in healthcare
procedures. Through time, much more emphasis will be placed on diagnosing and
treating symptoms – even providing a cure – before secondary symptoms occur. In
contrast, with molecular diagnostics, highly sensitive devices will permit the screen-
ing of initial symptoms and that will change the scenario for the next 10–20 years,
where the family doctor will be able to screen for very early symptoms, or even treat
before symptoms occur. Then, if required, the patient will be referred to a hospital
or medical center for further diagnosis and staging, using molecular imaging and
targeted contrast agents that can interact with processes in a ‘pre-disease’ state. If
treatment is required, new pharmaceutical procedures will allow patient-specifi c
drug delivery, resulting in the ‘prevention rather than the cure’ of a (potential) dis-
ease. In the more distant future (after 20 years) screening, staging and treatment
will, as can be expected, all be performed at the molecular level, and probably by the
family doctor. It is also feasible that screening for certain selected symptoms may be
performed at home by the individual without professional medical assistance.
GE Medical Systems (Waukesha, Wisconsin, USA) provides non-invasive
molecular imaging methods, such as PET, CT or MRI combined with novel imaging
agents. GE Medical Systems is collaborating with biotechnology industry to
combine genetic and proteomic data with diagnostic imaging for enhancing early
20 Development of Personalized Medicine