Investigating the aspect of asymmetry in brain-first versus body-first Parkinson's disease.

Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons in the substantia nigra. Recent literature has proposed two subgroups of PD. The "body-first subtype" is associated with a prodrome of isolated REM-sleep Behavior Disorder (iRBD) and a relatively symmetric brain degeneration. The "brain-first subtype" is suggested to have a more asymmetric degeneration and a prodromal stage without RBD. This study aims to investigate the proposed difference in symmetry of the degeneration pattern in the presumed body and brain-first PD subtypes. We analyzed 123I-FP-CIT (DAT SPECT) and 18F-FDG PET brain imaging in three groups of patients (iRBD, n = 20, de novo PD with prodromal RBD, n = 22, and de novo PD without RBD, n = 16) and evaluated dopaminergic and glucose metabolic symmetry. The RBD status of all patients was confirmed with video-polysomnography. The PD groups did not differ from each other with regard to the relative or absolute asymmetry of DAT uptake in the putamen (p = 1.0 and p = 0.4, respectively). The patient groups also did not differ from each other with regard to the symmetry of expression of the PD-related metabolic pattern (PDRP) in each hemisphere. The PD groups had no difference in symmetry considering mean FDG uptake in left and right regions of interest and generally had the same degree of symmetry as controls, while the iRBD patients had nine regions with abnormal left-right differences (p < 0.001). Our findings do not support the asymmetry aspect of the "body-first" versus "brain-first" hypothesis.

Impact of microscopic extrathyroidal extension on differentiated thyroid cancer post-surgical risk of recurrence: a retrospective analysis.

PURPOSE: In the last edition of the American Joint Committee on Cancer (AJCC) staging system, differentiated thyroid cancers (DTC) showing microscopic extrathyroidal extension (mETE) are considered comparable to intrathyroidal cancers for their clinical behavior and prognosis. The aim of the study is to evaluate the impact of this updated assessment of T, when applied to the postoperative recurrence risk stratification, according to the American Thyroid Association Guidelines (ATA-RR). METHODS: One-hundred DTC patients who underwent total thyroidectomy were retrospectively evaluated. The downstaging of mETE was introduced in the definition of T, and the updated classification defined as modified ATA-RR (ATAm-RR). For each patient, post-surgical basal and stimulated thyroglobulin (Tg) levels, neck ultrasound (US) and post-ablative 131-I whole body scan (WBS) reports were considered. The predictive performance (PP) of disease recurrence was calculated both for each single parameter, as well as for all of them. RESULTS: According to ATAm-RR classification, 19/100 patients (19%) were downstaged. ATA-RR proved a significant PP for disease recurrence (DR) (sensitivity 75.0%, specificity 63.0%, p = 0.023). However, ATAm-RR performed slightly better due to an increased specificity (sensitivity 75.0%, specificity 83.7%, p < 0.001). For both classifications, the PP was optimal when all the above-mentioned predictive parameters were considered. CONCLUSION: Our results suggest that the new assessment of T considering mETE resulted in a downgrading of ATA-RR class in a significant number of patients. This provides a better PP for disease recurrence, and the best PP was obtained when considering the whole predictive variables together.

The Italian Society of Rheumatology clinical practice guidelines for the management of large vessel vasculitis.

OBJECTIVE: Since of the last publication of last recommendations on primary large-vessel vasculitis (LVV) endorsed by the Italian Society of Rheumatology (SIR) in 2012, new evidence emerged regarding the diagnosis and the treatment with conventional and biologic immunosuppressive drugs. The associated potential change of clinical care supported the need to update the original recommendations. METHODS: Using the grading of recommendations assessment, development and evaluation (GRADE)-ADOLOPMENT framework, a systematic literature review was performed to update the evidence supporting the European Alliance of Associations for Rheumatology (EULAR) guidelines on LVV as reference. A multidisciplinary panel of 12 expert clinicians, a trained nurse, and a patients' representative discussed the recommendation in cooperation with an Evidence Review Team. Sixty-one stakeholders were consulted to externally review and rate the recommendations. RESULTS: Twelve recommendations were formulated. A suspected diagnosis of LVV should be confirmed by imaging or histology. In active GCA or TAK, the prompt commencement of high dose of oral glucocorticoids (40-60 mg prednisone-equivalent per day) is strongly recommended to induce clinical remission. In selected patients with GCA (e.g., refractory or relapsing disease or patients at risk of glucocorticoid related adverse effects) the use of an adjunctive therapy (tocilizumab or methotrexate) is recommended. In all patients diagnosed with TAK, adjunctive therapies, such as conventional synthetic or biological immunosuppressants, should be given in combination with glucocorticoids. CONCLUSIONS: The new set of SIR recommendations was formulated in order to provide a guidance on both diagnosis and treatment of patients suspected of or with a definite diagnosis of LVV.

A kinetics-based approach to amyloid PET semi-quantification.

PURPOSE: To develop and validate a semi-quantification method (time-delayed ratio, TDr) applied to amyloid PET scans, based on tracer kinetics information. METHODS: The TDr method requires two static scans per subject: one early (~ 0-10 min after the injection) and one late (typically 50-70 min or 90-100 min after the injection, depending on the tracer). High perfusion regions are delineated on the early scan and applied onto the late scan. A SUVr-like ratio is calculated between the average intensities in the high perfusion regions and the late scan hotspot. TDr was applied to a naturalistic multicenter dataset of 143 subjects acquired with [18F]florbetapir. TDr values are compared to visual evaluation, cortical-cerebellar SUVr, and to the geometrical semi-quantification method ELBA. All three methods are gauged versus the heterogeneity of the dataset. RESULTS: TDr shows excellent agreement with respect to the binary visual assessment (AUC = 0.99) and significantly correlates with both validated semi-quantification methods, reaching a Pearson correlation coefficient of 0.86 with respect to ELBA. CONCLUSIONS: TDr is an alternative approach to previously validated ones (SUVr and ELBA). It requires minimal image processing; it is independent on predefined regions of interest and does not require MR registration. Besides, it takes advantage on the availability of early scans which are becoming common practice while imposing a negligible added patient discomfort.

Does a 6-point scale approach to post-treatment 18F-FDG PET-CT allow to improve response assessment in head and neck squamous cell carcinoma? A multicenter study.

PURPOSE: Response assessment to definitive non-surgical treatment for head and neck squamous cell carcinoma (HNSCC) is centered on the role of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET-CT) 12 weeks after treatment. The 5-point Hopkins score is the only qualitative system available for standardized reporting, albeit limited by suboptimal positive predictive value (PPV). The aim of our study was to explore the feasibility and assess the diagnostic accuracy of an experimental 6-point scale ("Cuneo score"). METHODS: We performed a retrospective, multicenter study on HNSCC patients who received a curatively-intended, radiation-based treatment. A centralized, independent qualitative evaluation of post-treatment FDG-PET/CT scans was undertaken by 3 experienced nuclear medicine physicians who were blinded to patients' information, clinical data, and all other imaging examinations. Response to treatment was evaluated according to Hopkins, Cuneo, and Deauville criteria. The primary endpoint of the study was to evaluate the PPV of Cuneo score in assessing locoregional control (LRC). We also correlated semi-quantitative metabolic factors as included in PERCIST and EORTC criteria with disease outcome. RESULTS: Out of a total sample of 350 patients from 11 centers, 119 subjects (oropharynx, 57.1%; HPV negative, 73.1%) had baseline and post-treatment FDG-PET/CT scans fully compliant with EANM 1.0 guidelines and were therefore included in our analysis. At a median follow-up of 42 months (range 5-98), the median locoregional control was 35 months (95% CI, 32-43), with a 74.5% 3-year rate. Cuneo score had the highest diagnostic accuracy (76.5%), with a positive predictive value for primary tumor (Tref), nodal disease (Nref), and composite TNref of 42.9%, 100%, and 50%, respectively. A Cuneo score of 5-6 (indicative of residual disease) was associated with poor overall survival at multivariate analysis (HR 6.0; 95% CI, 1.88-19.18; p = 0.002). In addition, nodal progressive disease according to PERCIST criteria was associated with worse LRC (OR for LR failure, 5.65; 95% CI, 1.26-25.46; p = 0.024) and overall survival (OR for death, 4.81; 1.07-21.53; p = 0.04). CONCLUSIONS: In the frame of a strictly blinded methodology for response assessment, the feasibility of Cuneo score was preliminarily validated. Prospective investigations are warranted to further evaluate its reproducibility and diagnostic accuracy.

Italian consensus recommendations for a biomarker-based aetiological diagnosis in mild cognitive impairment patients.

BACKGROUND AND PURPOSE: Biomarkers support the aetiological diagnosis of neurocognitive disorders in vivo. Incomplete evidence is available to drive clinical decisions; available diagnostic algorithms are generic and not very helpful in clinical practice. The aim was to develop a biomarker-based diagnostic algorithm for mild cognitive impairment patients, leveraging on knowledge from recognized national experts. METHODS: With a Delphi procedure, experienced clinicians making variable use of biomarkers in clinical practice and representing five Italian scientific societies (neurology - Società Italiana di Neurologia per le Demenze; neuroradiology - Associazione Italiana di Neuroradiologia; biochemistry - Società Italiana di Biochimica Clinica; psychogeriatrics - Associazione Italiana di Psicogeriatria; nuclear medicine - Associazione Italiana di Medicina Nucleare) defined the theoretical framework, relevant literature, the diagnostic issues to be addressed and the diagnostic algorithm. An N-1 majority defined consensus achievement. RESULTS: The panellists chose the 2011 National Institute on Aging and Alzheimer's Association diagnostic criteria as the reference theoretical framework and defined the algorithm in seven Delphi rounds. The algorithm includes baseline clinical and cognitive assessment, blood examination, and magnetic resonance imaging with exclusionary and inclusionary roles; dopamine transporter single-photon emission computed tomography (if no/unclear parkinsonism) or metaiodobenzylguanidine cardiac scintigraphy for suspected dementia with Lewy bodies with clear parkinsonism (round VII, votes (yes-no-abstained): 3-1-1); 18 F-fluorodeoxyglucose positron emission tomography for suspected frontotemporal lobar degeneration and low diagnostic confidence of Alzheimer's disease (round VII, 4-0-1); cerebrospinal fluid for suspected Alzheimer's disease (round IV, 4-1-0); and amyloid positron emission tomography if cerebrospinal fluid was not possible/accepted (round V, 4-1-0) or inconclusive (round VI, 5-0-0). CONCLUSIONS: These consensus recommendations can guide clinicians in the biomarker-based aetiological diagnosis of mild cognitive impairment, whilst guidelines cannot be defined with evidence-to-decision procedures due to incomplete evidence.

Semi-quantification and grading of amyloid PET: A project of the European Alzheimer's Disease Consortium (EADC).

BACKGROUND: amyloid-PET reading has been classically implemented as a binary assessment, although the clinical experience has shown that the number of borderline cases is non negligible not only in epidemiological studies of asymptomatic subjects but also in naturalistic groups of symptomatic patients attending memory clinics. In this work we develop a model to compare and integrate visual reading with two independent semi-quantification methods in order to obtain a tracer-independent multi-parametric evaluation. METHODS: We retrospectively enrolled three cohorts of cognitively impaired patients submitted to 18F-florbetaben (53 subjects), 18F-flutemetamol (62 subjects), 18F-florbetapir (60 subjects) PET/CT respectively, in 6 European centres belonging to the EADC. The 175 scans were visually classified as positive/negative following approved criteria and further classified with a 5-step grading as negative, mild negative, borderline, mild positive, positive by 5 independent readers, blind to clinical data. Scan quality was also visually assessed and recorded. Semi-quantification was based on two quantifiers: the standardized uptake value (SUVr) and the ELBA method. We used a sigmoid model to relate the grading with the quantifiers. We measured the readers accord and inconsistencies in the visual assessment as well as the relationship between discrepancies on the grading and semi-quantifications. CONCLUSION: It is possible to construct a map between different tracers and different quantification methods without resorting to ad-hoc acquired cases. We used a 5-level visual scale which, together with a mathematical model, delivered cut-offs and transition regions on tracers that are (largely) independent from the population. All fluorinated tracers appeared to have the same contrast and discrimination ability with respect to the negative-to-positive grading. We validated the integration of both visual reading and different quantifiers in a more robust framework thus bridging the gap between a binary and a user-independent continuous scale.

Anti-tumoral effects of somatostatin analogs: a lesson from the CLARINET study.

Octreotide and lanreotide, the first-generation somatostatin analogs, successfully control hormone hyperproduction, and related syndromes, in patients with acromegaly and neuroendocrine tumors. However, their anti-tumor effect, rather evident in large number of pituitary adenomas in acromegalic patients, has been hypothesized for a long time in patients with neuroendocrine tumors as well, although a significant tumor shrinkage has rarely been observed. However, the recent publication of the CLARINET study has strengthened the evidence, already emerged with the PROMID trial, that the long-term treatment with the first-generation long-acting somatostatin analogs may exert an anti-tumor activity on G1 and G2 enteropancreatic neuroendocrine tumors, as well. After the publication, majority of international guidelines have updated their algorithms in line with these results and this class of drugs obtained the indication as anti-tumor agents in the majority of patients with neuroendocrine tumors.

Relationship between circulating anti-thyroglobulin antibodies (TgAb) and tumor metabolism in patients with differentiated thyroid cancer (DTC): prognostic implications.

PURPOSE: TgAb have been proposed as tumor markers in DTC. Recent evidence links TgAb levels with DTC aggressiveness. We aimed to evaluate the relationship between TgAb and tumor glucose metabolism in DTC patients. METHODS: Seventy-one DTC patients who underwent 18F-FDG PET/CT were included. According to TgAb value and trends, patients were divided into TgAb positive (TgAb+) or negative (TgAb-) as well as in patients with increasing (Inc-TgAb) or decreasing (Dec-TgAb) trend. On the basis of the results of FDG-PET, post-therapy 131I and Tg levels, patients were divided into two groups according to the evidence (ED) or absence (NED) of disease. ED patients were further divided into three subgroups: 1. radioiodine avid with positive 18F-FDG PET/CT (PET+/131I+), 2. radioiodine refractory with positive 18F-FDG PET/CT (PET+/131I-) and 3. radioiodine avid with negative 18F-FDG PET/CT (PET-/131I+). MeanSUV of FDG-avid lesions was assessed and averaged for each patient (SUVmean-pt). T test was performed to assess the difference between SUVmean in TgAb-, TgAb+ and in Inc-TgAb and Dec-TgAb subgroups. Difference in TgAb between ED and NED patients as well as between ED patients and PET+/131I+, PET+/131I- and PET-/131I+ subgroups was compared. RESULTS: SUVmean was significantly higher in Inc-TgAb with respect to Dec-TgAb subgroup (5.2 ± 1.5 vs. 2.9 ± 1.1, p < 0.05). TgAb were higher only in the ED PET+/131I+ subgroup with respect to NED patients (p < 0.01). CONCLUSIONS: The relationship between higher tumor metabolism and trend of TgAb supports a prognostic relevance of TgAb in DTC patients. Significantly higher TgAb in radioiodine avid tumors with positive 18F-FDG PET/CT further testify the role of TgAb as surrogate tumor marker in DTC.

18F-FDG PET/CT is a prognostic biomarker in patients affected by bone metastases from breast cancer in comparison with 18F-NaF PET/CT.

AIM: To compare 18F-FDG PET/CT and 18F-NaF PET/CT with respect to disease prognostication and outcome in patients affected by bone metastases from breast cancer (BC). PATIENTS, METHODS: We retrospectively investigated 32 women with BC and documented bone metastases. Semi-quantitative parameters were applied to 18F-FDG PET/CT and 18F-Na PET/CT in order to evaluate disease extent and tumour metabolism. We used time-to-event analyses (Kaplan Meier and COX proportional hazard methods) to estimate progression-free (PFS) and overall survival (OS) in order to assess the independent prognostic value of 18F-FDG PET/CT and 18F-Na PET/CT. RESULTS: The sensitivity of 18F-NaF PET/CT (100%) was higher (p < 0.05) than that of 18F-FDG PET/CT (72% and 72%). None of the 18F-FDG PET/CT-negative patients showed disease progression at the end of follow-up. After adjustment for age, Ki-67 levels, presence of visceral metastases, hormone therapy, duration of bone disease and response to first-line therapy, only 18F-FDG SUV mean [HR 15.7, 95% confidence interval (CI) 1.15-214.5] and 18F-FDG whole-body bone metabolic burden (WB-B-MB) (HR 16.9; 95%CI 1.87-152.2) were independently and significantly associated with OS. None of the 18F-NaF PET/CT parameters were associated with OS. None of the conventional clinical prognostic parameters remained significantly associated with OS after the inclusion of PET/CT parameters in the model. CONCLUSION: 18F-FDG PET/CT is independently associated with OS in BC patients with bone metastases and its prognostic impact seems to be higher than conventional clinical and biological prognostic factors. Although 18F-NaF PET/CT has a higher diagnostic sensitivity than 18F-FDG PET/CT, it is not independently associated with OS.

Volume of interest-based [18F]fluorodeoxyglucose PET discriminates MCI converting to Alzheimer's disease from healthy controls. A European Alzheimer's Disease Consortium (EADC) study.

An emerging issue in neuroimaging is to assess the diagnostic reliability of PET and its application in clinical practice. We aimed at assessing the accuracy of brain FDG-PET in discriminating patients with MCI due to Alzheimer's disease and healthy controls. Sixty-two patients with amnestic MCI and 109 healthy subjects recruited in five centers of the European AD Consortium were enrolled. Group analysis was performed by SPM8 to confirm metabolic differences. Discriminant analyses were then carried out using the mean FDG uptake values normalized to the cerebellum computed in 45 anatomical volumes of interest (VOIs) in each hemisphere (90 VOIs) as defined in the Automated Anatomical Labeling (AAL) Atlas and on 12 meta-VOIs, bilaterally, obtained merging VOIs with similar anatomo-functional characteristics. Further, asymmetry indexes were calculated for both datasets. Accuracy of discrimination by a Support Vector Machine and the AAL VOIs was tested against a validated method (PALZ). At the voxel level SMP8 showed a relative hypometabolism in the bilateral precuneus, and posterior cingulate, temporo-parietal and frontal cortices. Discriminant analysis classified subjects with an accuracy ranging between .91 and .83 as a function of data organization. The best values were obtained from a subset of 6 meta-VOIs plus 6 asymmetry values reaching an area under the ROC curve of .947, significantly larger than the one obtained by the PALZ score. High accuracy in discriminating MCI converters from healthy controls was reached by a non-linear classifier based on SVM applied on predefined anatomo-functional regions and inter-hemispheric asymmetries. Data pre-processing was automated and simplified by an in-house created Matlab-based script encouraging its routine clinical use. Further validation toward nonconverter MCI patients with adequately long follow-up is needed.

Functional imaging in pre-motor Parkinson's disease.

Several non motor symptoms (NMS) can precede the onset of the classical motor Parkinson's disease (PD) syndrome. The existence of pre-motor and even pre-clinical PD stages has been proposed but the best target population to be screened to disclose PD patients in a pre-clinical, thus asymptomatic, stage is still matter of debate. The REM sleep behavior disorder (RBD) often affects PD patients at different stages of the disease and could precede the onset of motor symptoms by several years. However, RBD could also precede other synucleinopathies (namely, dementia with Lewy bodies and multisystem atrophy), and less frequently could be related to other neurological conditions or remain idiopathic. Moreover, not all PD patients exhibit RBD. Despite these caveats, RBD probably represents the best feature to disclose pre-motor PD patients given its high-risk of developing a full motor syndrome. Other clinical clues in the premotor stages of PD undergoing active investigation include hyposmia, depression, and autonomic dysfunction. Effective biomarkers are needed in order to improve the diagnostic accuracy in the pre-motor stage of PD, to monitor disease progression and to plan both pharmacological and non-pharmacological intervention. Functional imaging, in particular radionuclide methodologies, has been often used to investigate dopaminergic and non-dopaminergic features as well as cortical functioning in patients with RBD in its idiopathic form (iRBD) and/or associated with PD. Recently, new tracers to image α-synuclein pathologies are under development. Functional imaging in pre-motor PD, and in particular in iRBD, could improve our knowledge about the underlying mechanisms and the neurodegenerative progress of PD.

Efficacy of sorafenib and impact on cardiac function in patients with thyroid cancer: a retrospective analysis.

PURPOSE: Sorafenib has recently been recognized as an important standard option for the management of patients with differentiated thyroid cancer. Although data concerning cardiac safety are available in pan-tumor studies, no data are available on its use in everyday clinical practice in patients with thyroid cancer. METHODS: In the off-label program of our institution, we enrolled 14 patients with different histological types of thyroid cancer suitable for treatment with sorafenib. Our aims were to evaluate cardiac safety factors-LVEF (left ventricular ejection fraction), heart rate and blood pressure-the cardiac markers NT-proBNP and troponin I, radiological response evaluated by CT and (18)FDG-PET (according to RECIST 1.1 criteria) and biomarker reduction (Eastern Cooperative Oncology Group Performance Status: ECOG PS) 0-2. RESULTS: Patients with ECOG PS 2 accounted for 36%. After starting sorafenib, many patients displayed reduced or stabilized metabolic activity in target lesions (clinical benefit = 44%), radiologic reduction or stabilization (74%) and decreased cancer markers (90%). Lung metastases displayed the largest reductions in size. Median overall survival (OS) was 7 months and median progression-free survival (PFS) was 3 months. No sign of cardiotoxicity was observed in almost all patients. LVEF was altered in two patients and proved symptomatic in one. CONCLUSIONS: Sorafenib seems to be effective in reducing disease progression in the early stages of treatment (3-6 months). Responses varied considerably according to the criteria investigated. Cardiac toxicities did not raise concerns and were in line with data reported in other malignancies. However, cardiac monitoring is recommended.

Systemic vascular inflammation in abdominal aortic aneurysm patients: a contrast-enhanced PET/CT study.

AIM: The aim of this paper was to investigate the presence of systemic vascular inflammation and its relationship with risk factors and biomarkers of systemic inflammation related to atherosclerosis in asymptomatic abdominal aortic aneurysm (AAA) patients. METHODS: Thirty AAA patients and 30 age-matched controls underwent contrast-enhanced 2-deoxy-2-[18F]fluoro-D-glucose (FDG) PET/CT. C-reactive protein, erythrocyte sedimentation rate, white blood cell count and differential, serum fibrinogen, D-dimer and full lipid panel were also evaluated. Region of interest analyses were performed to obtain target-to-background (TBR) metabolism of aorta, subclavian, carotid, iliac arteries and AAA. CT-based arterial calcium load (CL) was evaluated. Arterial Metabolism and CL intergroup differences were tested (unpaired t-test). Linear regression analysis was performed only between blood biomarkers on one side and both TBR and ACL of the arterial districts that resulted significantly different between patients and controls on the other. In all the analyses P values <0.05 were considered significant. RESULT: FDG-uptake was higher with respect to controls in aorta, carotid and iliac arteries (P<0.01, P<0.007, P<0.04 respectively). AAA and aorta metabolism showed an inverse correlation with HDL-chol (P<0.02 and P<0.01, respectively) while only aorta showed a direct correlation with lymphocytes' count (P<0.02). Carotid metabolism was directly correlated with monocytes' count and C-reactive protein concentration (P<0.02 and P<0.004, respectively). CONCLUSION: The present findings support the relevance of systemic vascular inflammation in all phases of atherosclerosis-related disorders. Moreover they confirm the concept that acute ischemic syndromes might represent the local result of a systemic inflammation rather than the focal involvement of a single arterial lesion.

Trafficking and homing of systemically administered stem cells: the need for appropriate analysis tools of radionuclide images.

AIM: Despite its enormous relevance, homing of hematopoietic stem cells (SCs) remains relatively uncertain due to the limitations of measuring small number of systemically administered cells in the different organs. Despite its high sensitivity, radionuclide detection has been relatively underutilized to this purpose since it cannot differentiate hematopietic SCs recruited by target tissues from those circulating in the blood pool. Our study aims to verify the potential of tracer kinetic approaches in estimating the recruitment of labeled SCs after their systemic administration. METHODS: Twenty-four Lewis rats underwent administration of 2 millions cells labeled with 37 MBq of 99mTc-exametazime. Animals were divided into 2 groups according to administered cells: hematopoietic SCs or cells obtained from a line of rat hepatoma. Cell injection was performed during a planar dynamic acquisition. Regions of interest were positioned to plot time activity curves on heart, lungs, liver and spleen. Blood cell clearance was evaluated according to common stochastic analysis approach. Either fraction of dose in each organ at the end of the experiment or computing the slope of regression line provided by Patlak or Logan graphical approach estimated cell recruitment. At the end of the study, animals were sacrificed and the number of cells retained in the same organs was estimated by in vitro counting. RESULTS: Cell number, documented by the dose fraction retained in each organ at imaging was consistently higher with respect to the "gold standard" in vitro counting in all experiments. An inverse correlation was observed between degree of overestimation and blood clearance of labeled cells (r=-0.56, P<0.05). Logan plot analysis consistently provided identifiable lines, whose slope values closely agreed with the "in vitro" estimation of hepatic and splenic cell recruitment. CONCLUSION: The simple evaluation of organ radioactivity concentration does not provide reliable estimates of local recruitment of systemically administered cells. Yet, the combined analysis of temporal trends of tracer (cell) tissue accumulation and blood clearance can provide quantitative estimations of cell homing in the different organs.

Cognitive impairment in degenerative parkinsonisms: role of radionuclide brain imaging.

Cognitive impairment in Parkinson's disease (PD) and atypical parkinsonian syndromes is gaining increased clinical significance. The neurochemical and neuropathological basis in the various parkinsonian forms and even in an individual patient are not fully elucidated yet and could be heterogeneous. Loss of dopaminergic, cholinergic and noradrenergic innervation has been suggested to be the underlying neurochemical deficits for cognitive impairment and dementia in PD, but the onset of cognitive impairment and the progression to dementia may not share the same underlying neurochemical basis. Similarly, pathological evidence is also heterogeneous, ranging from subcortical pathology, limbic or cortical Lewy body type degeneration, and Alzheimer's type pathology that can be found even in the same patient with PD dementia (PDD). Typically, the prototype of early cognitive deficit in PD is a dysexecutive syndrome, but other cognitive domains are more involved when dementia develops, mainly including visuospatial, language and memory dysfunction. Functional radionuclide neuroimaging, by means of single-photon emission computed tomography and positron emission tomography, are contributing to characterize the topographic cortical pattern of cognitive impairment, as well as to define the underlying neurochemical deficit. Lastly, the advent of amyloid PET may help clarifying the meaning of amyloid load in diffuse Lewy body disease and PDD. Knowing the neurochemical and pathophysiological substrate of cognitive deficit in patients with PD or other degenerative Parkinsonisms may help the clinician in understanding the clinical condition of an individual patient in order to plan pharmacological and non-pharmacological intervention. The introduction of acetylcholinesterase inhibitors for therapy of PDD is an example of information integration between clinical-neuropsychological and pathophysiological-neurochemical aspects obtained also with the key contribution of functional neuroimaging.

Could [18]F-fluorodeoxyglucose PET/CT change the therapeutic management of stage IV thyroid cancer with positive (131)I whole body scan?

AIM: Stage-IV differentiated thyroid cancer (DTC) patients may present elevated serum thyroglobulin (Tg) levels associated with positive [(131)I] whole-body-scan (WBS). Nevertheless some patients in whom WBS does not reveal new sites of disease show increased Tg levels. This finding prompts thorough restaging in order to exclude the presence of metastases unable to concentrate iodine. The aim of our study was to evaluate the impact of [(18)F]FDG-PET/CT in both the assessment of overall extent of the disease and the therapeutic management in a group of stage-IV DTC patients. METHODS: On suspicious of non-iodine concentrating additional metastases, 20 stage-IV DTC patients with increasing Tg levels and stable positive post-therapy WBS were enrolled. Conventional imaging (CI) procedures, including neck ultrasonography, bone-scintigraphy and computed tomography (CT) were performed before [(18)F]FDG-PET/CT. RESULTS: [(18)F]FDG-PET/CT was positive in 16 out of 20 patients (80%). In 9 patients (45%) [(18)F]FDG PET/CT detected a larger number of tumour recurrences/metastatic sites than WBS+CI. [(18)F]FDG PET/CT findings prompted modification of the management of 11 patients (55%), in whom surgery or external radiotherapy were eventually considered more appropriate than radioactive iodine therapy. These further therapies improved the quality of life in several patients but did not change their survival rate. CONCLUSION: Our results showed that [18F]FDG-PET/CT can detect new radioiodine-negative metastases in advanced DTC patients with unchanged positive WBS and increasing Tg levels. [(18)F]FDG-PET/CT may constitute a useful tool in the choice of the best therapeutic strategy in such difficult cases.