Brain 123I-ioflupane SPECT and 18F-FDG PET combined use in movement and cognitive associated diseases of recent appearance

Background-Aim: 123I-Ioflupane SPECT (SPECT) represents a
useful tool in the diagnosis of movement disorders (MD) with basal
ganglia dopaminergic damage as Parkinson’s disease (PD) while 18FFDG PET (PET) defines metabolic impairment in cognitive disorders
(CD) as Alzheimer’s disease (AD) and other dementias. Since an
association of MD with CD has been reported in some cases, we
evaluated whether the combined use of SPECT and PET might be
useful in the patients affected by both these conditions.
Methods: We investigated 41 consecutive patients with recent
appearance of clinical symptoms suspect for MD and CD with
doubtful signs at neurological examination and neuropsychological
tests and aspecific data at magnetic resonance imaging. According to
the international guidelines, within 3 weeks the patients were also
submitted to both SPECT and PET. In the two procedures, the images
were evaluated both qualitatively (QL) and quantitatively (QN), the
latter using a dedicated software that compares each patient with age
matched normal control groups (cut-off value of 3.3 and Z core of
- 2.0 for SPECT and PET, respectively).
Results: At SPECT, QL analysis evidenced tracer reduction uptake in
basal ganglia of 18/41 patients, mild in four and severe in 14, while
the uptake was normal in the remaining 23/41 cases. QN analysis
evidenced uptake reduction in 20/41 cases (two of these normal at
QL) and normal values in the other 21 patients. At PET, QL analysis
showed different patterns of cortical hypometabolism in 33/41
patients and was normal in the remaining 8/41 cases; QN evidenced
pathological values in 34/41 cases and normal values in the remaining
7/41 patients. The combining use of the two procedures, evidenced
pathological SPECT and PET in 15/41 (36.6%) patients, considered
with associated dopaminergic and cognitive diseases. SPECT was
pathological and PET was normal in 5/41 (12.2%) cases who were
classified as MD without CD. SPECT was normal and PET pathological in 19/41 (46.3%) cases who were classified as affected by CD
without MD. Both SPECT and PET were normal in 2/41 (4.9%)
cases, thus excluding MD and CD. QN analysis of SPECT and PET
showed better performance than QL analysis.
Conclusions: In this study, the combined use of 123I-Ioflupane
SPECT and 18F-FDG PET has led to a more appropriate disease
diagnosis and characterization, and an adequate treatment and correct
management of patients affected by associated MD and CD of recent
appearance. In particular, the use of QN analysis in both SPECT and
PET proved a useful complementary tool to the conventional QL
analysis, especially when the latter is inconclusive. A wider use of
these combined procedures is suggested even more when the other
exams are not decisive for the diagnosis.