Patient and tumor characteristics predictive of an elevated hepatopulmonary shunt fraction before radioembolization of hepatic tumors.

OBJECTIVE: To determine whether any patient or hepatic tumor characteristics are predictive of hepatopulmonary shunt fraction when performed before radioembolization. MATERIALS AND METHODS: A retrospective review was performed on 190 patients who underwent preradioembolization hepatic arteriography with calculation of hepatopulmonary shunt fraction using technetium-99m-labeled macroaggregated albumin perfusion scintigraphy. Patient and tumor characteristics including imaging features were reviewed for correlation with absolute shunt fraction, shunt fraction greater than 10%, and shunt fraction greater than 20%. RESULTS: Most tumor types showed some cases of elevated shunt fraction greater than 10%. Six patients had a shunt fraction greater than 20%: four were hepatocellular carcinoma and two were neuroendocrine tumor metastases. Univariate analysis showed that dominant tumor diameter, hepatic tumor burden, vascular invasion, hepatic venous invasion, and hypervascularity on angiography were associated with a shunt fraction greater than 10%. Only dominant tumor diameter and vascular invasion were associated with a shunt fraction greater than 20%. On multivariate analysis, only tumor diameter (odds ratio 1.2) and hepatic venous invasion (odds ratio 23.0) were associated independently with an increased shunt fraction greater than 10%. CONCLUSION: Multiple patient and tumor-related characteristics were significantly correlated with the hepatopulmonary shunt fraction on univariate analysis. However, on multivariate analysis, only the dominant tumor diameter and presence of hepatic venous invasion were associated independently with a greater than 10% shunt fraction.

Incidental Thyroid Nodules at Non-FDG PET Nuclear Medicine Imaging: Evaluation of Prevalence and Malignancy Rate.

OBJECTIVE: The purpose of this study was to estimate the prevalence of thyroid nodules detected incidentally on non-FDG PET nuclear medicine imaging studies, the malignancy rate, and predictors of malignancy. MATERIALS AND METHODS: A retrospective review of more than 10 years of patient records at an academic medical center identified the cases of 31 patients with incidental focal radiotracer-avid thyroid findings on non-FDG PET nuclear medicine studies who underwent biopsy or surgical excision. Statistical analysis of patient and imaging features was performed to identify features predictive of malignancy. Society of Radiologists in Ultrasound and American Thyroid Association biopsy criteria were applied to patients who had ultrasound images for review. RESULTS: Thirty-one patients had incidental thyroid findings on (99m)Tc-sestamibi parathyroid scans (80.6%), (111)In-pentetreotide scans (16.1%), and (99m)Tc-tetrofosmin cardiac scans (3.2%). These three types of scans accounted for 21,402 total examinations in the study period. Thus, the prevalence of incidental thyroid findings on non-PET nuclear medicine studies that were evaluated by pathologic examination was 0.14%. The malignancy rate was 16.1% (5/31). No clinical or imaging features were identified as predictive of malignancy. Society of Radiologists in Ultrasound and American Thyroid Association criteria were applied to 23 thyroid nodules with available ultrasound images. According to both sets of criteria, biopsy was recommended for 19 of 23 (82.6%) nodules, and one of three (33.3%) cases of thyroid cancer was missed. CONCLUSION: Most thyroid nodules incidentally detected on non-FDG PET nuclear medicine studies are detected on (99m)Tc-sestamibi parathyroid scans and (111)In-pentetreotide scans. Because these nodules are extremely rare and the malignancy rate is high, further evaluation of incidental focal radiotracer-avid thyroid findings with ultrasound is an appropriate recommendation.

Efficient self-assembly of Archaeoglobus fulgidus ferritin around metallic cores.

Interfacing biological systems with inorganic nanoparticles is of great interest, as it offers means of particle stabilization and spatial control in electronic or biomedical applications. We report on the particle-directed assembly of hyperthermophile Archaeoglobus fulgidus ferritin subunits around negatively charged colloidal gold. An annealing process allows rapid assembly of the protein in near-native stoichiometry. Transmission electron microscopy suggests that greater than 95% of nanoparticles are encapsulated while the self-assembly process ensures that almost 100% of the assembled ferritin cavities are occupied.

Structure and activity of apoferritin-stabilized gold nanoparticles.

A simple method for synthesizing gold nanoparticles stabilized by horse spleen apoferritin (HSAF) is reported using NaBH(4) or 3-(N-morpholino)propanesulfonic acid (MOPS) as the reducing agent. AuCl(4)(-) reduction by NaBH(4) was complete within a few seconds, whereas reduction by MOPS was much slower; in all cases, protein was required during reduction to keep the gold particles in aqueous solution. Transmission electron microscopy (TEM) showed that the gold nanoparticles were associated with the outer surface of the protein. The average particle diameters were 3.6 and 15.4 nm for NaBH(4)-reduced and MOPS-reduced Au-HSAF, respectively. A 5-nm difference in the UV-Vis absorption maximum was observed for NaBH(4)-reduced (530 nm) and MOPS-reduced Au-HSAF (535 nm), which was attributed to the greater size and aggregation of the MOPS-reduced gold sample. NaBH(4)-reduced Au-HSAF was much more effective than MOPS-reduced Au-HSAF in catalyzing the reduction of 4-nitrophenol by NaBH(4), based on the greater accessibility of the NaBH(4)-reduced gold particle to the substrate. Rapid reduction of AuCl(4)(-) by NaBH(4) was determined to result in less surface passivation by the protein. Methods for studying ferritin-gold nanoparticle assemblies may be readily applied to other protein-metal colloid systems.