Thyroid nodules with indeterminate cytology: prospective comparison between 18F-FDG-PET/CT, multiparametric neck ultrasonography, 99mTc-MIBI scintigraphy and histology.

PURPOSE: To evaluate the role of (18)F-flurodeoxiglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) in predicting malignancy of thyroid nodules with indeterminate cytology. PATIENTS AND METHODS: We analysed 87 patients who have been scheduled to undergo surgery for thyroid nodule with indeterminate cytology. All patients underwent (18)F-FDG-PET/CT, multiparametric neck ultrasonography (MPUS), and (99m)Tc-methoxyisobutylisonitrile scintigraphy ((99m)Tc-MIBI-scan). Histopathology was the standard of reference. We compared the sensitivity (SE), specificity (SP), accuracy (AC), positive (PPV) and negative predictive (NPV) values of (18)F-FDG-PET/CT with those of (99m)Tc-MIBI-scan and MPUS in detecting cancer. Univariate and multivariate analyses evaluated the association between each diagnostic tool and histopathology. RESULTS: On histopathology, 69 out of 87 nodules were found to be benign and 18 to be malignant. The SE, SP, AC, PPV and NPV of (18)F-FDG-PET/CT were 94, 58, 66, 37 and 98% respectively. The SE, AC and NPV of (18)F-FDG-PET/CT were significantly higher than those of MPUS and (99m)Tc-MIBI-scan. The association of both positive (18)F-FDG-PET/CT and MPUS (FDG+/MPUS+) showed significantly lower SE (61% vs 94%) and NPV (88% vs 98%) than (18)F-FDG-PET/CT alone, but significantly higher SP (77% vs 58%). On univariate analysis, (18)F-FDG-PET/CT and the combination of FDG+/MPUS+ and of FDG+/MIBI- were all significantly associated with histopathology. On multivariate analysis, only FDG+/MIBI- was significantly associated with histopathology. CONCLUSION: The AC of (18)F-FDG-PET /CT in detecting thyroid malignancy is higher than that of (99m)Tc-MIBI-scan and MPUS. A negative (18)F-FDG-PET/CT correctly predicts benign findings on histopathology. The association of FDG+/MPS+ is significantly more specific than (18)F-FDG-PET/CT alone in identifying differentiated thyroid cancer. A positive (18)F-FDG-PET/CT is significantly associated with malignancy when qualitative (99m)Tc-MIBI-scan is rated as negative.

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.

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.