Improved vascular depiction and image quality through deep learning reconstruction of CT hepatic arteriography during transcatheter arterial chemoembolization.

PURPOSE: To evaluate the effect of deep learning reconstruction (DLR) on vascular depiction, tumor enhancement, and image quality of computed tomography hepatic arteriography (CTHA) images acquired during transcatheter arterial chemoembolization (TACE). METHODS: Institutional review board approval was obtained. Twenty-seven patients (18 men and 9 women, mean age, 75.7 years) who underwent CTHA immediately before TACE were enrolled. All images were reconstructed using three reconstruction algorithms: hybrid-iterative reconstruction (hybrid-IR), DLR with mild strength (DLR-M), and DLR with strong strength (DLR-S). Vascular depiction, tumor enhancement, feeder visualization, and image quality of CTHA were quantitatively and qualitatively assessed by two radiologists and compared between the three reconstruction algorithms. RESULTS: The mean signal-to-noise ratios (SNR) of sub-segmental arteries and sub-sub-segmental arteries, and the contrast-to-noise ratio (CNR) of tumors, were significantly higher on DLR-S than on DLR-M and hybrid-IR (P < 0.001). The mean qualitative score for sharpness of sub-segmental and sub-sub-segmental arteries was significantly better on DLR-S than on DLR-M and hybrid-IR (P < 0.001). There was no significant difference in the feeder artery detection rate of automated feeder artery detection software among three reconstruction algorithms (P = 0.102). The contrast, continuity, and confidence level of feeder artery detection was significantly better on DLR-S than on DLR-M (P = 0.013, 0.005, and 0.001) and hybrid-IR (P < 0.001, P = 0.002, and P < 0.001). The weighted kappa values between two readers for qualitative scores of feeder artery visualization were 0.807-0.874. The mean qualitative scores for sharpness, granulation, and diagnostic acceptability of CTHA were better on DLR-S than on DLR-M and hybrid-IR (P < 0.001). CONCLUSIONS: DLR significantly improved the SNR of small hepatic arteries, the CNR of tumor, and feeder artery visualization on CTHA images. DLR-S seems to be better suited to routine CTHA in TACE than does hybrid-IR.

[Efficacy of L-shaped Shielding in Interventional Radiology by Transradial Approach and Consideration of Methods for Appropriate Use].

The present study investigated how effective an L-shaped shield was, depending on its position, in reducing a doctor's exposure to radiation during catheterization to access the transradial approach (TRA). The shield's effectiveness was evaluated by measuring the air kerma where the doctor stood under four conditions: with and without the shield, and with and without the shield in conjunction with conventional protection. To enable the shield to be positioned correctly in clinical practice, an illustrated instruction decal affixable to the shield's doctor-facing surface was produced, and the effectiveness of the decal was verified by means of a crossover test in which, as subjects of the study, different nurses set up the shield with and without the decal affixed to it. In the test, in which a human body phantom was used, the C-arm set at the PA angle, and the shield positioned 10 cm from the axilla of the phantom, the shield's effectiveness at 100 cm, 130 cm, and 160 cm above the floor where the doctor stood was 55%, 77%, and 47%, respectively. The effectiveness increased when the shield was positioned closer to the axilla. A significant difference in the positioning of the shield by the subjects was observed depending on whether or not the decal was affixed ( p<0.05, Wilcoxon signed-rank test), indicating that the use of the decal improved the positioning. It was concluded that, positioned correctly, the shield could effectively reduce the doctor's exposure to radiation during TRA.

Tumor necrosis factor stimulates osteoclastogenesis from human bone marrow cells under hypoxic conditions.

Bone homeostasis is maintained by the balance between osteoblastic bone formation and osteoclastic bone resorption. In this study, we used human bone marrow cells (BMCs) to investigate the role of hypoxic exposure on human osteoclast (OC) formation in the presence of tumor necrosis factor (TNF). Exposing the BMCs to 3%, 5%, or 10% O2 in the presence of receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) generated tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells, consistent with OCs. The addition of TNF under hypoxic conditions generated significantly greater numbers of mature OCs with more nuclei than OCs generated under normoxic conditions. Longer initial hypoxic exposure increased the number of OC precursor cells and facilitated the differentiation of OC precursor cells into multinucleated OCs. Quantitative RT-PCR analysis revealed that RANKL and TNFR1 were expressed at higher levels in non-OC cells from BMCs under hypoxic conditions than under normoxic conditions. Furthermore, to confirm the involvement of TNF-induced signaling, we examined the effects of blocking antibodies against TNFR1 and TNFR2 on OC formation under hypoxic conditions. The TNFR1 antibody was observed to significantly suppress OC formation. These results suggest that hypoxic exposure plays an important role in TNF-induced osteoclastogenesis from human BMCs.