Prospective Study of Systemic Yttrium-90 Elution during Radioembolization of Hepatic Metastases.

PURPOSE: To evaluate total blood radioactivity (BR) after SIR-Spheres yttrium-90 (90Y) radioembolization and differences in BR based on delivery method. MATERIALS AND METHODS: Twenty participants with hepatic metastases undergoing first radioembolization were prospectively enrolled from December 2017 to June 2018. Blood samples were drawn at baseline and 0, 10, 20, 60, and 120 minutes after 90Y administration. BR was measured with a γ-counter and scaled by estimated blood volume. Percentage of instilled radioactivity in the bloodstream was calculated as area under the fitted curve, and differences between delivery methods were examined with nonparametric statistical tests. RESULTS: In 10 participants, resin microspheres were instilled with 50% Isovue 300 diluted in saline solution in the D line, and 10 others were treated with dextrose 5% in water (D5W) in the D line. Median administered activities were 944 MBq (range, 746-1,993 MBq) and 1,213 MBq (range, 519-2,066 MBq), respectively. Fraction of 90Y in blood was significantly higher with dilute contrast agent than with D5W (median, 0.5% of injected activity vs 0.2%; P = .001). Among all participants, the maximum activity delivered was 2,066 MBq, and a maximum of 1% of administered radioactivity was measured as free 90Y in blood. Assuming these highest-case values and complete decay of all free 90Y in bone, a dose to red marrow of 132.3 mGy was calculated by Organ Level INternal Dose Assessment/EXponential Modeling. CONCLUSIONS: Blood sampling after radioembolization allowed for estimation of the time-activity curve and BR. Delivery with 50% contrast agent in saline solution resulted in a significant increase in BR vs D5W, even though the total BR for both groups was nominal.

METHOD FOR OCCUPATIONAL SKIN DOSE ESTIMATION IN UPPER EXTREMITY 131I-MIBG CONTAMINATION.

This study examines upper extremity skin contamination of nuclear medicine and radiation safety staff during 131I-Metaiodobenzylguanidine (MIBG) therapy. Utilizing retrospective data, a methodology for performing a rapid assessment of the radiation dose to the skin of the upper extremities is presented. Using the skin contamination measurements and calculated skin dose for each contamination incident at our facility, a conversion factor (XE) was derived that estimates skin dose (DE) based on the initial contamination measurement. This methodology yields an estimate of the final skin dose accounting for radioactive decay, decontamination and other factors, such as skin sloughing. As a standard practice multiple time-point measurements from initial contamination to background should be used to calculate the total attributable skin dose. However, to provide an early projection of the expected skin dose, the dose can be reasonably estimated to be <0.10% mSv cpm-1 (10% mrem cpm-1) of the initial contamination measurement.

Investigation of dental cone-beam CT pixel data and a modified method for conversion to Hounsfield unit (HU).

OBJECTIVES: To investigate the relationship in dental cone-beam CT (CBCT) between the manufacturer-reported image pixel data and a modified conversion to CT number densities in Hounsfield unit (HU). METHODS: A standardized CT phantom was imaged using typical clinical parameters on CBCT from three manufacturers (Carestream 9300®, Carestream Health, Rochester, NY; J Morita 3D Accutomo®, J. Morita Mfg. Corp., Kyoto, Japan; and Planmeca Promax 3D®, Planmeca Helsinki, OY, Finland). Reconstructed axial slices were evaluated using regions of interest to ascertain the mean pixel value in five materials in the phantom. The Digital Imaging and Communications in Medicine data were also evaluated to determine if raw pixel data had been adjusted during the image reconstruction. A modified version of the existing manual HU conversion technique was applied, and the resultant slope and y-intercept were used to scale the pixel values ultimately to HU for all images. RESULTS: The DICOM header data show that a modified rescale y-intercept was applied to both the Carestream and Planmeca image data yielding manufacturer-produced results in HU. The Morita pixel data were unmodified and report in shades of grey or grey values (GV). The Carestream manufacturer-derived HU measurements showed good correlation in air (-1000 HU), but all other materials ranged from 2.6 to 13.5 σ from the specified phantom value. Results in the modified conversion technique images fell within 1.0-2.4 σ from the specified phantom values. CONCLUSIONS: While more studies are needed to test for regularity, this study suggests that our modified technique could be a means of getting more accurate quantitative data from dental CBCTs.

Acid sphingomyelinase inhibition protects mice from lung edema and lethal Staphylococcus aureus sepsis.

UNLABELLED: Pulmonary edema associated with increased vascular permeability is a severe complication of Staphylococcus aureus-induced sepsis and an important cause of human pathology and death. We investigated the role of the mammalian acid sphingomyelinase (Asm)/ceramide system in the development of lung edema caused by S. aureus. Our findings demonstrate that genetic deficiency or pharmacologic inhibition of Asm reduced lung edema in mice infected with S. aureus. The Asm/ceramide system triggered the formation of superoxide, resulting in degradation of tight junction proteins followed by lung edema. Treatment of infected mice with amitriptyline, a potent inhibitor of Asm, protected mice from lung edema caused by S. aureus, but did not reduce systemic bacterial numbers. In turn, treatment with antibiotics reduced bacterial numbers but did not protect mice from lung edema. In contrast, only the combination of antibiotics and amitriptyline inhibited both pulmonary edema and bacteremia protecting mice from lethal sepsis and lung dysfunction suggesting the combination of both drugs as novel treatment option for sepsis. KEY MESSAGES: Antibiotics are often insufficient to cure S. aureus-induced sepsis. S. aureus induces lung edema via the Asm/ceramide system. Genetic deficiency of Asm inhibits lung dysfunction upon infection with S. aureus. Pharmacologic inhibition of Asm reduces lung edema induced by S. aureus. Antibiotics plus amitriptyline protect mice from lung edema and lethal S. aureus sepsis.