Estimation of radioactivity in single photon emission computed tomography for sentinel lymph node biopsy in a torso phantom study

Objectives: Number of lymph nodes to be removed are determined from residual counts. Estimating residual radioactivity in lymphatic nodes before a biopsy in advance is useful for reducing surgical operation time. The purpose of this study was to estimate total radioactivity of a small hot spot in single-photon emission computed tomography (SPECT) of a torso phantom. Methods: Cross-calibration study was performed to convert counts in SPECT images to radioactivity. A simulation study was performed to estimate the size of volume of interest (VOI) covering a hot spot corrupted with full width at half maximum (FWHM) between 8 and 16 mm. The estimation of total radioactivity was validated in a torso phantom study using small sources. Results: True radioactivity was approximately equal to integrated values of hot spots using the VOI with a diameter of 40 mm in our simulation study. The difference was less than18% in cases of more than 9.4 kBq. Conclusions: The total radioactivity in small sources simulating a typical sentinel node was estimated from SPECT images using a VOI of 40 mm in a torso phantom study. Because the difference from actual values were less than 10% on average when radioactivities were more than 9.4 kBq, the total radioactivity of a lymph node can be estimated in a clinical examination

Dynamic changes in 18F-borono-L-phenylalanine uptake in unresectable, advanced, or recurrent squamous cell carcinoma of the head and neck and malignant melanoma during boron neutron capture therapy patient selection

Abstract Background We evaluated dynamic changes in 18F–borono-L-phenylalanine (18F–BPA) uptake in unresectable, advanced, or recurrent squamous cell carcinoma of the head and neck (SCC) and malignant melanoma (MM) during boron neutron capture therapy (BNCT) patient selection. Methods Dynamic changes in the maximum standardized uptake value (SUVmax), tumor-to-normal tissue ratio (TNR), and tumor-to-blood pool ratio (TBR) for 18F–BPA were evaluated in 20 patients with SCC and 8 patients with MM. Results SUVmax in SCC tumors decreased significantly from 30 to 120 min. There was a non-statistically significant decrease in SUVmax for SCC tumors from 30 to 60 min and from 60 to 120 min. Patients with MM had nonsignificant SUVmax changes in 18F–BPA uptake on delayed imaging. Nonsignificant 18F–BPA TNR and TBR changes were seen in patients with SCC and MM. Conclusions Dynamic changes in SUVmax for 18F–BPA uptake had a washout pattern in SCC and a persistent pattern in MM. Dynamic 18F–BPA -PET studies should be performed to investigate the pharmacokinetics of 18F–BPA in humans and select appropriate candidates who may benefit from BNCT

Cost analysis of leuprorelin acetate in Japanese prostate cancer patients: comparison between 6-month and 3-month depot formulations

<p><b>Aims:</b> This study aimed to evaluate the economic value for leuprorelin acetate 6-month depot compared with leuprorelin acetate 3-month depot from a societal perspective in Japanese prostate cancer patients.</p> <p><b>Methods:</b> The cost analysis estimated the reduction in direct and indirect costs as well as intangible costs saved by having one less injection. Claims data were used for the analyses of direct and indirect costs reduction. A discrete choice experiment based on a web-based survey estimated the monetary value of the intangible costs for one injection. Another web-based survey of prostate cancer patients, who had received treatment with leuprorelin acetate injections, was carried out to calibrate the results of the discrete choice experiment.</p> <p><b>Results:</b> Reductions in medical costs and loss of productivity for having one less injection in prostate cancer patients receiving leuprorelin acetate were JPY 5,670 and JPY 1,723, respectively. Intangible costs saved by using a 6-month depot formulation instead of a 3-month depot formulation for the injection of leuprorelin acetate were estimated to be JPY 19,872, including the values for a reduction in pain (JPY 3,131), injection site reactions (JPY 11,545), waiting time (JPY 9,479), and subtracting the value of medical consultation (JPY 4,283). The total cost reduction for having one less injection was JPY 27,265.</p> <p><b>Limitations:</b> The respondents from the internet panel provided by a survey company are not necessarily a representative population of Japanese society.</p> <p><b>Conclusions:</b> Leuprorelin acetate 6-month depot has an advantage in monetary value in the reduction in medical costs, loss of productivity, and intangible costs for having one less injection in prostate cancer patients compared with leuprorelin acetate 3-month depot. In the costs for treating with leuprorelin acetate, the percentage of intangible costs might not be negligible. The intangible costs will probably be actively evaluated to proceed to patient-centered healthcare in society.</p

SANS and DLS Study of Tacticity Effects on Hydrophobicity and Phase Separation of Poly(<i>N</i>‑isopropylacrylamide)

The tacticity effect on phase separation process of poly­(<i>N</i>-isopropylacrylamide) (PNiPAM) aqueous solutions was investigated by dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements. SANS measurement revealed that hydrophobicity of PNiPAM consisting of meso- and racemo-isomers increased with increasing the meso-content. This result is in accordance with the result of the previous experimental and simulation study on NiPAM dimers (DNiPAM) and trimers (TNiPAM) [Katsumoto, Y.; J. Phys. Chem. B 2010, 114, 13312−13318, and Autieri, E.; J. Phys. Chem. B 2011, 115, 5827–5839]; i.e., meso-diad is more hydrophobic than racemo-diad. In addition, a series of scattering experiments revealed that the ratio of meso-diad does not affect the static structure or the shrinking behavior of a single chain, but strongly affects the aggregation behavior. The PNiPAMs with low meso-content suddenly associate around the phase separation temperature, while that of the high meso-content gradually aggregate with increasing temperature. We propose that phase transition behavior of PNiPAM aqueous solutions can be controlled by changing the stereoregularity of the polymer chain

Structural Analysis of Lipophilic Polyelectrolyte Solutions and Gels in Low-Polar Solvents

Lipophilic polyelectrolyte gels capable of large swelling in low-polar solvents (3 ≤ ε ≤ 10) were developed by Ono et al. (Nature Mater. 2007), where ε is the dielectric constant. These gels were prepared by introducing tetraphenylborate as a lipophilic anion (tetrakis­(3,5-bis­(trifluoromethyl)­phenyl)­borate; TFPB^–) and tetraalkylammonium with long alkyl chains as a lipophilic cation (tetra­(<i>n</i>-butyl)­ammonium; TBA⁺) into a poly­(octadecyl acrylate) (pODA) backbone chain. Here, we investigated the structure of the lipophilic polyelectrolyte gels and corresponding polymer solutions in CH₂Cl₂ with small-angle neutron scattering (SANS) and dynamic light scattering (DLS). From SANS, it was revealed that individual pODA chain is regarded as a rod with the cross-section radius of 15 Å and the length of ca. 160 Å and is little changed by introduction of charges or cross-linking. In addition to this, it was revealed from SANS measurements that the second virial coefficient of pODA in CH₂Cl₂ was positive. In combination with DLS measurements, we observed several characteristic features similar to polyelectrolyte aqueous systems such as (i) the clear appearance of slow diffusional motion in polymer solutions, (ii) an increase of diffusion coefficient in gels, and (iii) an increase of osmotic modulus in solutions and gels when ionic groups are incorporated in pODA. These experimental findings clearly show that [TBA⁺]­[TFPB^–] dissociates enough and pODA, accompanying these ionic groups, acts as a polyelectrolyte even in a low-polar solvent such as CH₂Cl₂ (ε = 8.9). It is concluded that the good compatibility of pODA with CH₂Cl₂ and the introduction of dissociable ionic groups into pODA result in high-swelling capability of the lipophilic polyelectrolyte gels