Online Abstract Book - Radiologiekongress.ch

Poster Presentations SGNM-SSMN
PO61
Added value of DaTSCAN SPECT to FDG PET semi-automated
analysis in the investigation of clinically suspected neurodegenerative
syndromes using ROIs based discriminant analysis
V. Garibotto, M.-L. Montandon, C. Tabouret-Viaud, F. Assal,
P. R. Burkhard, M. Allaoua, O. Ratib, H. Zaidi; Genève
Purpose: Neuroimaging is increasingly used to support the clinical diagnosis
of patients investigated for cognitive impairment . Dopamine transporter
(DAT) imaging, such as DaTSCAN SPECT, tests the integrity of the
nigro-striatal pathway, while FDG PET identifies typical pattern of cortical
and subcortical hypometabolism . Aim of this study was to assess the
relative contribution of DAT and regional glucose metabolism (rCMRglc)
assessment to the differential diagnosis .
Methods and Materials: 57 subjects investigated for the clinical suspicion
of a neurodegenerative parkinsonian syndrome underwent both
FDG PET and DaTSCAN SPECT . We selected patients with a clinical diagnosis
of probable Alzheimer’s disease (AD: 5), corticobasal degeneration
(CBD: 6), Lewy body dementia (LBD: 8), frontotemporal degeneration
(FTLD: 4) and Parkinson’s disease (IPD: 4) . rCMRglc and DAT density
were obtained by BRASS (Hermes software) . We used a discriminant
analysis (SPSS) with a stepwise method and we tested also the results of
the leave-one-out cross-validation .
Results: When using the rCMRglc values the 85 .2% and 55 .6% of the
patients were correctly classified for the discriminant analysis and the
cross-validation, respectively; when DAT alone was considered, the results
were 59 .3% and 51 .9%, and with the combination of both DAT and
rCMRglc 100% and 88 .9% .
Conclusion: These preliminary results obtained by an automated
approach show that the information coming from the analysis of the
rCMRglc and DAT density is not redundant: in fact, taking into account
both rCMRglc and DAT density allows a gain in the correct classification
of individual patients . These results further support the usefulness of performing
both modalities in clinical routine applications .
PO62
Changes in FDG biodistribution in delayed PET-MR studies
O. Ratib, A. Figueral, E. Fleury, M. Lord, M. Viallon, S. Heinzer, H. Zaidi;
Genève
Purpose: To evaluate changes in biodistribution of FDG uptake in different
organs measured at two different points in time to assess variability
of SUV measurements in two consecutive PET studies performed about
one hour apart .
Methods and Materials: In the process of evaluation of a new hybrid
PET-MR scanner two consecutive PET scans were obtained after injection
of FDG in 48 patients undergoing a PET-MR study following a PET-
CT scan . The average delay between the first PET study (PET-CT) and
the second PET study (PET-MR) was 94±25 minutes ranging from 49
minutes to 138 minutes . Changes in biodistribution of tracer uptake were
measured from 10 anatomical regions including brain, cerebellum, lungs,
liver, heart, colon, muscle and bones as well as in tumor and metastatic
lesions when present .
Results: Significant changes in biodistribution of FDG tracer were
observed in different organs . These changes were confirmed form
SUV quantitative ROI measurement of different tissue uptake . While in
general, pathological tracer uptake in malignant lesions seemed to increase
between the first and the second scan, there was significant difference
in delayed changes in uptake of different organs .
Conclusion: Very little is known about changes in FDG tissue uptake in
normal organs over long periods of time after injection . Our study shows
significant variability with different trends in different organs . This enforces
the need for very strict control of time delays of image acquisition
in comparing SUV between different studies since normal changes in
biodistribution can significantly affect these measurements .
PO63
Quality assessment of fluorocholine PET imaging in clinical setting:
Validation of standard quality control parameters
C. Le Petit, C. Jegouic, D. O. Slosman; Genève
Purpose: Standardized parameters for quality control (QC) assessment
of 18F-fluorocholine PET (F-CHO-PET) were validated in transversal and
longitudinal cohorts of patients with prostate cancer to be applied in
clinical setting .
Methods and Materials: Protocol was developed to measure standardized
pulmonary/hepatic/bone tissues SUVmean (T-SUVmean) . Thus 176
PET scans were performed in 142 patients . All patients had standardized
3-phases F-CHO-PET protocol of acquisition using Biograph-16 . A set
of 30 PET scans was used to calculate intra- and inter-observer reproducibility
(CV) and the range of normal values of pulmonary/hepatic/bone
tissues SUVmean (Ref-SUVmean) . Then T-SUVmean of 142 PET scans
(transversal cohort) were measured and compared to Ref-SUVmean .
Values out of range were identified . Appropriateness of QC was define
as occurrence within patient of Ref-SUVmean out of range i) for a single
tissue, ii) for 2 tissues simultaneously, or iii) for the 3 tissues . Similar protocol
was applied to determine the longitudinal range (Ref-∆SUVmean:
change between 2 consecutive exams) and to validate QC in a group of
61 pairs of F-CHO-PET .
Results: The intra- and inter-observer SUVmean CV remained under
4 .1% and 4 .6%, respectively . In the transversal study, none of the
176 PET scans combined the three values out of range, whereas for the
longitudinal study, only one of the 34 pairs of consecutive PET scans
combined the three values out of range values . Accuracy of SUV measurements
was at first related to overweight status .
Conclusion: The validation of a standardized and reproducible F-CHO-
PET QC protocol combining measurements of pulmonary/hepatic/bone
reference tissues SUVmean allows its use in clinical setting .
PO64
Frequency of incidentaloma on F-18-FDG PET/CT:
A first Swiss study
A. Leuenberger, A. Boubaker, J. Prior; Lausanne
Purpose: 18F-FDG PET/CT is used for the cancer staging and it is not
rare to discover unexpected findings (incidentalomas) . Our aim was to
determine the frequency of these clinically silent pretumoral or tumoral
lesions in patients who were addressed for an FDG-PET/CT because of
an oncological indication .
Methods and Materials: We retrospectively reviewed the 1226 examination
reports from August 2009 to July 2010 for consecutive, unselected
patients . We noticed every unexpected finding and their localization, before
searching how they were handled and which subsequent investigations
were made .
Results: We found 309 unexpected foci in 260 patients (25% of all
reports) . Of these, 216 lesion were found in 169 patients followed at
CHUV and 143 lesions were investigated in 129 patients . Finally, we found
34 incidentalomas (2,8%) in 33 patients . Among these, 8 were malignant,
6 premalignant and 20 benign leading to a malignant and premalignant
incidentalomas rate of 1,1% . Frequent sites were similar to those published
in the literature, including the thyroid gland, the colorectal region
(with only premalignant lesions), lymphomas and the lungs . For these last
three, frequency was lower as what is described in other studies .
Conclusion: In this first Swiss study, we obtained a rate of premalignant/
malignant incidentaloma of 1,1%, which corresponds to the lowest limit
reported in the literature . Frequently involved regions were the thyroid
gland, the colorectal region, lymph nodes and the lungs .
Online Abstract Book of the Swiss Congress of Radiology 44