Impact of reconstruction parameters on quantitative bone SPECT imaging: A novel thoracic spine phantom study

INTRODUCTION

The aim of this study was to validate the effect of reconstruction parameters on quantitative accuracy of bone single-photon emission computed tomography (SPECT) images using a novel thoracic spine phantom.

METHODS

We used a novel thoracic spine phantom for bone SPECT image evaluation. This phantom consisted of a body, a vertebral body, a spinous process, and a tumor part (spheres, diameter: 13, 17, 22, 28mm), which were filled with ^99mTc and bone-equivalent solution. The SPECT/CT images were acquired with a dual-head SPECT/CT camera (Infinia8 Hawkeye 4, GE) equipped with low-energy high resolution collimator. The bone phantom images were reconstructed using the ordered subset expectation maximization (OSEM) algorithm with resolution recovery and CT-based attenuation correction and scatter correction. The number of iterations was varied from 1 to 20 and the number of subsets was fixed at 10. The maximum, peak, and mean standardized uptake values (SUVmax, SUVpeak, SUVmean) were calculated for the body and the tumor part, and the relative measurement error was assessed.

RESULTS

All quantitative values increased as the number of iterations increased and reached plateaus at 50-100 update numbers. The SUVmax of tumor part was 59.2 when the number of iterations was 2 and 55.7 when the number of iterations was 20. The maximum relative measurement error on the tumor part (reference value: 50) was obtained using the number of iteration 1 and over 10.

CONCLUSION

Our results indicated that the quantitative accuracy of bone SPECT images was affected by reconstruction parameters. It is important to optimize the reconstruction parameters, and improve quantitative accuracy in bone SPECT imaging.

Effect of phytic acid on postprandial serum uric acid level in healthy volunteers: a randomized, double-blind, crossover study

Phytic acid, a constituent of various plants, has been related to health benefits. Phytic acid has been shown to inhibit purine nucleotide metabolism in vitro and suppress elevation of plasma uric acid levels after purine administration in animal models. This study investigated the effect of phytic acid on postprandial serum uric acid (SUA) in humans. This randomized, double-blind, crossover design study included 48 healthy subjects with normal fasting SUA. Subjects consumed a control drink and a phytic acid drink with purine-rich food, and serum and urine uric acid levels were measured for 360 min after purine loading. Phytic acid lowered the incremental area under the curve (0-360 min) and incremental maximum concentration of SUA after purine loading (p < 0.05); tended to lower cumulative urinary uric acid excretion (0-360 min) after purine loading (p < 0.10); and suppressed postprandial SUA in this clinical study. Altogether, our findings suggest that phytic acid may play a beneficial role in controlling postprandial SUA.

On the Elevated Temperature Thermal Stability of Nanoscale Mn-Ni-Si Precipitates Formed at Lower Temperature in Highly Irradiated Reactor Pressure Vessel Steels

Atom probe tomography (APT) and scanning transmission electron microscopy (STEM) techniques were used to probe the long-time thermal stability of nm-scale Mn-Ni-Si precipitates (MNSPs) formed in intermediate and high Ni reactor pressure vessel steels under high fluence neutron irradiation at ≈320 °C. Post irradiation annealing (PIA) at 425 °C for up to 57 weeks was used to determine if the MNSPs are: (a) non-equilibrium solute clusters formed and sustained by radiation induced segregation (RIS); or, (b) equilibrium G or Γ₂ phases, that precipitate at accelerated rates due to radiation enhanced diffusion (RED). Note the latter is consistent with both thermodynamic models and x-ray diffraction (XRD) measurements. Both the experimental and an independently calibrated cluster dynamics (CD) model results show that the stability of the MNSPs is very sensitive to the alloy Ni and, to a lesser extent, Mn content. Thus, a small fraction of the largest MNSPs in the high Ni steel persist, and begin to coarsen at long times. These results suggest that the MNSPs remain a stable phase, even at 105 °C higher than they formed at, thus are most certainly equilibrium phases at much lower service relevant temperatures of ≈290 °C.

A case of generalized pustular psoriasis caused by hydroxychloroquine in a patient with systemic lupus erythematosus

Hydroxychloroquine (HCQ) has been used to treat systemic lupus erythematosus (SLE) in Japan since 2015. We herein report a case of SLE that developed generalized pustular psoriasis (GPP) following the administration of HCQ. Twenty-one days after the HCQ treatment, a pustular rash with itching appeared on the auricle, scalp, and forearm, and spread rapidly to the face and body trunk with a high fever and arthralgia. Skin biopsy showed pustule formation under the cornified layer, neutrophil infiltration, the destruction of keratinocytes, and spongiform pustules of Kogoj. The patient was diagnosed with GPP. HCQ was immediately discontinued, the dose of prednisolone (PSL) was increased, and granulocyte and monocyte adsorption apheresis was performed. Her symptoms subsequently disappeared. Since arthralgia relapsed after the tapering of PSL, cyclosporine was added. Although single nucleotide polymorphisms (c.28C>T and c.115+6T>C) in the interleukin (IL)-36RN gene, which encodes the IL-36 receptor antagonist, have frequently been reported in GPP, these mutations were not observed in the present case. The potential development of GPP needs to be considered when administering HCQ to patients with SLE.

Intraoperative evaluation of blood flow for soft tissues in orthopaedic surgery using indocyanine green fluorescence angiography: A pilot study

Objectives

Indocyanine green (ICG) fluorescence angiography is an emerging technique that can provide detailed anatomical information during surgery. The purpose of this study is to determine whether ICG fluorescence angiography can be used to evaluate the blood flow of the rotator cuff tendon in the clinical setting.

Methods

Twenty-six patients were evaluated from October 2016 to December 2017. The participants were categorized into three groups based on their diagnoses: the rotator cuff tear group; normal rotator cuff group; and adhesive capsulitis group. After establishing a posterior standard viewing portal, intravenous administration of ICG at 0.2 mg/kg body weight was performed, and fluorescence images were recorded. The time from injection of the drug to the beginning of enhancement of the observed area was measured. The hypovascular area in the rotator cuff was evaluated, and the ratio of the hypovascular area to the anterolateral area of the rotator cuff tendon was calculated (hypovascular area ratio).

Results

ICG fluorescence angiography allowed for visualization of blood flow in the rotator cuff in all groups. The adhesive capsulitis group showed significantly earlier enhancement than the other groups. Furthermore, the adhesive capsulitis group had a significantly smaller hypovascular area ratio than the other groups.

Conclusion

ICG fluorescence angiography allowed for evaluation of real-time blood flow of the rotator cuff in arthroscopic shoulder surgery. The techniques of ICG fluorescence angiography are simple and easy to observe, observer reliability is high, and it has utility for evaluating blood flow during surgery.Cite this article: N. Doi, T. Izaki, S. Miyake, T. Shibata, T. Ishimatsu, Y. Shibata, T. Yamamoto. Intraoperative evaluation of blood flow for soft tissues in orthopaedic surgery using indocyanine green fluorescence angiography: A pilot study. Bone Joint Res 2019;8:118-125. DOI: 10.1302/2046-3758.83.BJR-2018-0151.R1.

Abstract P6-21-08: Synergistic anti-cancer activity of cyclin-dependent kinase 4/6 inhibitor palbociclib and dual mTOR kinase inhibitor MLN0128 in pRb-expressing triple negative breast cancer

Background

No targeted therapies have been approved for triple negative breast cancer (TNBC) thus far. Retinoblastoma protein (pRb), a major substrate of cyclin-dependent kinase (CDK) 4/6, might be a potential target especially in chemoresistant TNBC. Palbociclib is a first approved oral CDK4/6 inhibitor for treatment of patients with estrogen receptor (ER) -positive and human epidermal growth factor receptor 2 (HER2) -negative breast cancers. Nevertheless, the usefulness of CDK4/6 inhibitors has not been established in patients with TNBC although, pRb is expressed in approximately 60% of this subtype of breast cancer. In addition, pRb expression has been shown to be associated with poor prognosis after chemotherapy. This pre-clinical study investigated the combination effects of palbociclib with oral dual mTOR kinase inhibitor MLN0128 in TNBC in vitro and in vivo.

Methods

Four TNBC cell lines (MB231, MB453, MB468, and CAL148) were tested with the combination of two drugs in vitro. The combination effects on cell proliferation were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and colony formation assay. Cell cycle analysis and level changes of molecules related to G1/S transition and mTOR pathway were examined. Importantly, a pRb-expressing TNBC patient-derived xenograft (PDX) model was used for confirming the combination effect in vivo.

Results

Palbociclib suppressed cell proliferation in pRb-expressing cell lines (MB231 and MB453), not pRb-deficient lines (MB468 and CAL148). The combination of palbociclib with MLN0128 showed synergistic inhibition of proliferation of MB231 and MB453 cells. Western blot analysis revealed that CDK4/6-pRb and mTOR-p70S6K pathways were inhibited by palbociclib or MLN0128 alone, but considerably more effective by the combination treatment. Cell cycle analysis showed that this combination induced G1 cell cycle arrest. The combined effect of palbociclib and MLN0128 were investigated further in vivo. In pRb-expressing TNBC PDX, the combination treatment drastically inhibited pRb phosphorylation and tumor growth compared to control or single treatment. In addition, effective reduction of PDX tumors was also demonstrated by major suppression of Ki67-positive cells by the combination treatment compared to control or single treatment.

Conclusions

In this pre-clinical study, we discovered that the combination treatment of CDK4/6 inhibitor palbociclib and dual mTOR kinase inhibitor MLN0128 had synergistic anti-cancer activity in pRb+ TNBC cell lines and a PDX model. Our results prove that such combination therapy is earnest to be further investigated in a clinical setting.

Citation Format: Yamamoto T, Kanaya N, Somlo G, Chen S. Synergistic anti-cancer activity of cyclin-dependent kinase 4/6 inhibitor palbociclib and dual mTOR kinase inhibitor MLN0128 in pRb-expressing triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-21-08.