Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with 99mTc and 68Ga.

Nanoparticles of Human Serum Albumin (NC) labelled with 99mTc are widely used in Nuclear Medicine and represent the gold-standard for the intraoperative detection of the sentinel lymph node in many kinds of cancer, mainly breast cancer and melanoma. A significant amount of radionuclides can be incorporated into the HSA particle, due to the multiple binding sites, and HSA-based nanocolloid catabolism is a fast and easy process that results in innocuous degradation products. NCs labelled with different isotopes represent an interesting radiopharmaceutical for extending diagnostic accuracy and surgical outcome, but the knowledge of the chemical bond between NCs and isotopes has not been fully elucidated, including information on its strength and specificity. The aim of this study is to investigate and compare the physicochemical characteristics of the bond between NCs and 99mTc and 68Ga isotopes. Commercial kits of HSA-based nanocolloid particles (NanoAlbumon®) were used. For this purpose, we have primarily studied the kinetic orders of NC radiolabelling. Langmuir isotherms and pH effect on radiolabelling were tested and the stability of the radiometal complex was verified through competition reactions carried out in presence of different ligands. The future goal of our research is the development of inexpensive and instant kits, easily labelled with a wide spectrum of diagnostic and therapeutic isotopes, thus facilitating the availability of versatile and multipurpose radiopharmaceuticals.

99mTc-68Ga-ICG-Labelled Macroaggregates and Nanocolloids of Human Serum Albumin: Synthesis Procedures of a Trimodal Imaging Agent Using Commercial Kits.

Recent developments in sentinel lymph node (SLN) and radio occult lesion localization (ROLL) highlight the need for a multimodal contrast agent, providing better presurgical PET imaging and improved intraoperative mapping thanks to fluorescence detection. For this reason, we have studied a trimodal SLN/ROLL targeting agent (99mTc-68Ga-ICG) with commercially available kits of macroaggregated or nanocolloidal albumin (MA/NC-HSA). 68Ga PET imaging does provide better spatial resolution and makes it possible to predict signal intensity during surgery. The presence of 99mTc assesses the efficacy of these compounds in vitro and also during the surgery procedure. The aim of this study was to optimise the labelling and tagging of these two radiopharmaceuticals and assess their yields and stability. Kits of MA/NC-HSA particles (Pulmocis® and NanoAlbumon®) were used for sequential radiolabelling with 99mTc and 68Ga. Fluorescent tagging was performed using indocyanine green, a tricarbocyanine dye. The ITLC radiochemical purity of the trilabelled MA/NC-HSA was >95%. Fluorescent purity was measured by scanning the strips with a PhotoDynamicEye probe. Finally, in vitro stability tests, performed with DTPA and human serum solutions, assessed the efficacy of fluorescent tagging and radiolabelling.

Prognostic role of FDG PET/CT in patients with differentiated thyroid cancer treated with 131-iodine empiric therapy.

BACKGROUND: To assess the long-term prognostic value of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with differentiated thyroid carcinoma (DTC) undergoing empiric radioiodine (RAI) therapy due to raising values of thyroglobulin (Tg). METHODS: Forty-nine patients with histological diagnosis of DTC (31 with papillary and 18 with follicular carcinoma) follow-up for a mean period of 7.9 ±â€Š5 years after empiric RAI therapy were retrospectively analyzed. RESULTS: FDG-PET/CT was negative in 15 (30.6%) patients and positive in 34 (69.4%), whereas postradioiodine therapy whole body scan (t-WBS) was negative in 16 (32.7%) and positive in 33 (67.3%) patients. FDG-PET/CT and t-WBS were in agreement in 32 patients (7 both negative and 25 both positive); on the contrary, in 17 patients there was disagreement between FDG-PET/CT and t-WBS (P =ns). At short-term follow-up, Tg normalized in 19 (38.8%) patients and was unchanged or increased in 30 (61.2%). Of the 15 patients with negative FDG-PET/CT, 11 (73.3%) showed Tg normalization, whereas of the 34 patients with positive FDG-PET/CT, only 8 (23.5%) had Tg normalization (χ =8.9, P < .005). At multivariate analysis, FDG-PET/CT and Tg normalization at short-term follow-up were independent predictors of disease-free survival (χ =26.3, P < .0001), while Tg normalization was the only variable associated with overall survival χ =7.2, P < .01). CONCLUSION: FDG-PET/CT in association with Tg normalization at short-term follow-up may be useful for long-term prognostic stratification in DTC patients.

Impact of obesity and acquisition protocol on (123)I-metaiodobenzylguanidine indexes of cardiac sympathetic innervation.

BACKGROUND: This study was designed to assess the impact of obesity and acquisition protocol on (123)I-metaiodobenzylguanidine (MIBG) indexes of cardiac sympathetic innervation. METHODS: Forty-five patients with heart failure (HF) (38 men, age 58±15 years) underwent (123)I-MIBG cardiac imaging. Of these patients, 10 were obese [body mass index (BMI) ≥30 kg/m(2)]. Ten-minute planar images of the thorax in anterior view were performed 15 minutes ("early" image) and 3 hours and 50 minutes ("late" image) after tracer administration in both supine- and prone-position. Early and late (123)I-MIBG heart-to-mediastinum (H/M) ratios and washout rate were computed. RESULTS: In overall study population, early and late (123)I-MIBG H/M ratios and washout rate were comparable between supine- and prone-position acquisitions. Obese patients had a lower early and late (123)I-MIBG H/M ratios both in supine (P<0.01) and prone (P<0.05) positions compared to non-obese subjects. CONCLUSIONS: Our results indicate that in HF patients, obesity has a significant impact on (123)I-MIBG indexes of cardiac sympathetic innervation. Prone-position did not change early and late (123)I-MIBG H/M ratios and washout rate compared to supine position both in obese and non-obese HF patients.