Risk of infection from glucocorticoid and methotrexate interaction in patients with rheumatoid arthritis using biologics: A retrospective cohort study.

AIMS: This retrospective cohort study aimed to evaluate the effect of the interaction between methotrexate and glucocorticoids on the risk of developing bacterial infections in patients with rheumatoid arthritis (RA) using biological disease-modifying antirheumatic drugs (bDMARDs). METHODS: We used the 2005-2018 JMDC claims database, a nationwide claims database in Japan. From the database of 7 175 048 patients, study patients were obtained by applying the following exclusion criteria: no use of bDMARDs; without information on the date of prescription; without RA as a disease; other than the new users of bDMARDs; and age <18 years. The exposures were glucocorticoids and methotrexate, and the outcome was bacterial infection. The interaction effects were examined using multivariate Cox regression analysis. Bacterial infections were identified according to antibiotic prescription and International Statistical Classification of Diseases and Related Health Problems, 10th revision codes. RESULTS: A total of 2837 RA patients were identified, with a median age of 50 years. The incidence of infection was 16.8% (95% confidence interval: 15.5-18.3). The interaction term for the doses of glucocorticoids and methotrexate was significant. Additionally, a higher dose of glucocorticoid was a significant risk factor for developing bacterial infections on the side of high doses of methotrexate. The incidence of bacterial infections tended to increase significantly with increasing methotrexate doses coprescribed with glucocorticoids ≥5 mg or glucocorticoid doses coprescribed with methotrexate ≥8 mg. CONCLUSION: Our results indicate a potential association between methotrexate dose and bacterial infections during bDMARDs administration with glucocorticoids in patients with RA.

Integrated genetic and epigenetic analysis of cancer-related genes in non-ampullary duodenal adenomas and intramucosal adenocarcinomas.

The molecular and clinical characteristics of non-ampullary duodenal adenomas and intramucosal adenocarcinomas are not fully understood because they are rare. To clarify these characteristics, we performed genetic and epigenetic analysis of cancer-related genes in these lesions. One hundred and seven non-ampullary duodenal adenomas and intramucosal adenocarcinomas, including 100 small intestinal-type tumors (90 adenomas and 10 intramucosal adenocarcinomas) and 7 gastric-type tumors (2 pyloric gland adenomas and 5 intramucosal adenocarcinomas), were investigated. Using bisulfite pyrosequencing, we assessed the methylation status of CpG island methylator phenotype (CIMP) markers and MLH1. Then using next-generation sequencing, we performed targeted exome sequence analysis within 75 cancer-related genes in 102 lesions. There were significant differences in the clinicopathological and molecular variables between small intestinal- and gastric-type tumors, which suggests the presence of at least two separate carcinogenic pathways in non-ampullary duodenal adenocarcinomas. The prevalence of CIMP-positive lesions was higher in intramucosal adenocarcinomas than in adenomas. Thus, concurrent hypermethylation of multiple CpG islands is likely associated with development of non-ampullary duodenal intramucosal adenocarcinomas. Mutation analysis showed that APC was the most frequently mutated gene in these lesions (56/102; 55%), followed by KRAS (13/102; 13%), LRP1B (10/102; 10%), GNAS (8/102; 8%), ERBB3 (7/102; 7%), and RNF43 (6/102; 6%). Additionally, the high prevalence of diffuse or focal nuclear ß-catenin accumulation (87/102; 85%) as well as mutations of WNT pathway components (60/102; 59%) indicates the importance of WNT signaling to the initiation of duodenal adenomas. The higher than previously reported frequency of APC gene mutations in small bowel adenocarcinomas as well as the difference in the APC mutation distributions between small intestinal-type adenomas and intramucosal adenocarcinomas may indicate that the adenoma-carcinoma sequence has only limited involvement in duodenal carcinogenesis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Relationship between serum calcium and creatinine in hematopoietic stem cell transplantation patients treated with foscarnet
.

OBJECTIVE: The relationship between serum creatinine and calcium (Ca) was investigated in hematopoietic stem cell transplantation (HSCT) patients treated with foscarnet. MATERIALS AND METHODS: A retrospective study was performed to investigate the development of foscarnet-induced renal dysfunction in patients who received HSCT from April 2010 to November 2018 at the Kindai University Nara Hospital. A total of 80 patients were identified from the medical records, and 42 patients who met the inclusion criteria were enrolled in this study. Renal dysfunction was classified according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. RESULTS: A significant inverse relationship was observed between serum creatinine and Ca levels (r = -0.372; p < 0.0001; y = -0.537x + 9.268). A separate analysis divided into renal dysfunction and non-renal dysfunction groups showed that there was a significant relationship between serum creatinine and Ca levels in the renal dysfunction group (r = -0.531; p < 0.0001; y = -0.617x + 9.239) but not in the non-renal dysfunction group (r = -0.011; p = 0.561; y = -0.023x + 8.934). The optimal cutoff for the minimum Ca level was calculated to be 8.1 mg/mL. CONCLUSION: A significant inverse relationship was observed between serum creatinine and Ca levels in HSCT patients with foscarnet-induced renal dysfunction. Foscarnet-induced renal dysfunction should be noted if Ca levels fall below 8.1 mg/dL. Monitoring Ca levels may be useful for detecting renal dysfunction at early stages in patients treated with foscarnet.

Voriconazole trough concentration and hepatotoxicity in patients with low serum albumin
.

OBJECTIVE: We aimed to investigate the relationship between voriconazole (VRCZ) trough concentrations and hepatotoxicity and to evaluate whether the recommended trough concentration is adequate in our clinical setting. MATERIALS AND METHODS: A retrospective study was performed to investigate the relationship between serum VRCZ concentrations and the development of hepatotoxicity at the Kindai University Nara Hospital. Patients treated with VRCZ from March 2010 to January 2018 were identified from the medical records. A total of 42 patients (mean age of 61.9 ± 16.9 years; 33 males and 9 females) were enrolled in this study. RESULTS: Hepatotoxicity developed in 28.6% (12/42) of patients treated with VRCZ, and 91.7% (11/12) of these patients developed hepatotoxicity within 3 weeks after initiating the treatment. Significantly increased aspartate aminotransferase (AST; p < 0.001), alkaline phosphatase (ALP; p < 0.001), and alanine aminotransferase (p = 0.001) levels were observed after the initiation of VRCZ therapy. In addition, significant positive correlations between AST and VRCZ trough concentrations (p = 0.017) and between ALP and VRCZ trough concentrations (p = 0.012) were observed. VRCZ trough concentration was identified as a significant independent risk factor for hepatotoxicity (adjusted odds ratio: 1.611, 95% confidence interval: 1.131 - 2.579, p = 0.006), and the cutoff serum trough concentration was calculated to be 4.2 µg/mL. CONCLUSION: VRCZ-induced hepatotoxicity should be noted in the early stages of therapy. A sustained VRCZ trough concentration of ~ < 4.2 µg/mL is recommended to prevent hepatotoxicity in patients with low serum albumin levels.

Relationship between the blood concentrations of tacrolimus and voriconazole in hematopoietic stem cell transplant recipients
.

OBJECTIVE: We aimed to clarify the drug interaction between tacrolimus and voriconazole and investigate the relationship between blood concentrations of tacrolimus and voriconazole in hematopoietic stem cell transplantation (HSCT) patients. MATERIALS AND METHODS: A retrospective study was conducted to investigate the relationship between blood concentration of tacrolimus and that of voriconazole at the Kindai University Nara Hospital. Patients who received HSCT and tacrolimus and were prescribed voriconazole for the prevention or treatment of aspergillosis from April 2010 to July 2018 were identified from the medical records. A total of 13 patients (administration route of tacrolimus: intravenously in 6 patients, orally in 7 patients) were enrolled in the present study. RESULTS: No significant correlation was observed between the blood concentration/dose (C/D) ratio of tacrolimus and the blood concentration of voriconazole (r = 0.38; p = 0.402; y = 102.8x + 928.1). However, a significant correlation was observed between the C/D ratio of tacrolimus and the blood concentration of voriconazole in the intravenous-administration group (r = 0.94; p = 0.0048; y = 421.9x + 810.5). Meanwhile, no significant correlation was observed in the oral-administration group (r = 0.43; p = 0.34; y = 7.9x + 719). CONCLUSION: The C/D ratio of tacrolimus was significantly correlated with the blood concentration of voriconazole when tacrolimus was intravenously administered. There was a difference in the mechanism of drug interaction between tacrolimus and voriconazole depending on the administration routes.

Impact of the clip and snare method using the prelooping technique for colorectal endoscopic submucosal dissection.

BACKGROUND AND STUDY AIM: Endoscopic submucosal dissection (ESD) is more difficult to perform for colorectal tumors, but the use of traction to facilitate direct submucosal layer visualization is a promising method to reduce procedure times and complication rates. This study aimed to evaluate the efficacy and safety of the clip and snare method (CSM) with a prelooping technique (PLT) for colorectal tumors. PATIENTS AND METHODS: A total of 140 colorectal tumors were treated: 17 using the CSM with PLT; 123, used as controls, by standard ESD without these techniques. Therapeutic efficacy and safety were retrospectively assessed. RESULTS: All tumors were successfully resected en bloc using the CSM with PLT. Multisegment resection was found in four tumors in the control group.  There was a significant difference in the procedure time between the patients in the CSM with PLT group and the control group (45.6 vs. 70.1 minutes; P = 0.047). There were no significant differences in the complication rates (5.9 % vs. 8.1 %; P = 1.00). CONCLUSIONS: The CSM with PLT was effective and safe in this study.

Whole Reconstruction-Free System Design for Direct Positron Emission Imaging From Image Generation to Attenuation Correction.

Direct positron emission imaging (dPEI), which does not require a mathematical reconstruction step, is a next-generation molecular imaging modality. To maximize the practical applicability of the dPEI system to clinical practice, we introduce a novel reconstruction-free image-formation method called direct µCompton imaging, which directly localizes the interaction position of Compton scattering from the annihilation photons in a three-dimensional space by utilizing the same compact geometry as that for dPEI, involving ultrafast time-of-flight radiation detectors. This unique imaging method not only provides the anatomical information about an object but can also be applied to attenuation correction of dPEI images. Evaluations through Monte Carlo simulation showed that functional and anatomical hybrid images can be acquired using this multimodal imaging system. By fusing the images, it is possible to simultaneously access various object data, which ensures the synergistic effect of the two imaging methodologies. In addition, attenuation correction improves the quantification of dPEI images. The realization of the whole reconstruction-free imaging system from image generation to quantitative correction provides a new perspective in molecular imaging.

Incidence of serious infections in the working-age Japanese adult population with rheumatoid arthritis treated with tumor necrosis factor-α inhibitors and interleukin-6 inhibitors: A nationwide retrospective cohort study.

AIM: This retrospective cohort study aimed to compare the risk of serious infections in patients with rheumatoid arthritis (RA) treated with tumor necrosis factor-α inhibitors (TNFαi) and interleukin-6 inhibitors (IL-6i), with no prior use of biological disease-modifying antirheumatic drugs (bDMARDs). METHODS: We employed the nationwide insurance claims database encompassing the years 2005 to 2018 in Japan. The inclusion criteria specified patients who were prescribed any type of bDMARDs, including TNFαi and IL-6i. The following exclusion criteria were applied: missing prescription dates, RA not diagnosed, below 16 years of age, bDMARDs prescribed within 6 months of registration, RA diagnosed post-bDMARDs prescription, and incidence of serious infections within 2 weeks before bDMARDs therapy. We applied stabilized inverse probability weights and utilized a Cox regression model to estimate the risk of serious infections associated with TNFαi and IL-6i. RESULTS: The cohort of 2493 patients with RA was categorized into a TNFαi group and an IL-6i group of 2018 and 475 participants, respectively. The median follow-up duration (interquartile range) was 347 (147-820) days in the TNFαi group and 369 (149-838) days in the IL-6i group. In the inverse probability-weighted cohort, the incidence rates (95% confidence interval) of serious infections were 2.13 (1.65-2.71) and 3.25 (2.15-4.69) per 100 person-years for the TNFαi and IL-6i groups, respectively. The hazard ratio (95% confidence interval) comparing the TNFαi group to the IL-6i group was 0.66 (0.36-1.20, p = 0.168). DISCUSSION: The results underscore the lack of evidence to preferentially favor either TNFαi or IL-6i as later-line therapy in the management of bDMARDs-naive RA to mitigate the risk of serious infections.

Transformer-CNN hybrid network for improving PET time of flight prediction.

Objective.In positron emission tomography (PET) reconstruction, the integration of time-of-flight (TOF) information, known as TOF-PET, has been a major research focus. Compared to traditional reconstruction methods, the introduction of TOF enhances the signal-to-noise ratio of images. Precision in TOF is measured by full width at half maximum (FWHM) and the offset from ground truth, referred to as coincidence time resolution (CTR) and bias.Approach.This study proposes a network combining transformer and convolutional neural network (CNN) to utilize TOF information from detector waveforms, using event waveform pairs as inputs. This approach integrates the global self-attention mechanism of Transformer, which focuses on temporal relationships, with the local receptive field of CNN. The combination of global and local information allows the network to assign greater weight to the rising edges of waveforms, thereby extracting valuable temporal information for precise TOF predictions. Experiments were conducted using lutetium yttrium oxyorthosilicate (LYSO) scintillators and silicon photomultiplier (SiPM) detectors. The network was trained and tested using the waveform datasets after cropping.Main results.Compared to the constant fraction discriminator (CFD), CNN, CNN with attention, long short-term memory (LSTM) and Transformer, our network achieved an average CTR of 189 ps, reducing it by 82 ps (more than 30%), 13 ps (6.4%), 12 ps (6.0%), 16 ps (7.8%) and 9 ps (4.6%), respectively. Additionally, a reduction of 10.3, 8.7, 6.7 and 4 ps in average bias was achieved compared to CNN, CNN with attention, LSTM and Transformer.Significance.This work demonstrates the potential of applying the Transformer for PET TOF estimation using real experimental data. Through the integration of both CNN and Transformer with local and global attention, it achieves optimal performance, thereby presenting a novel direction for future research in this field.

[Direct Positron Emission Imaging Using Ultrafast Timing Performance Detectors].

This is an explanatory paper on Sun Il Kwon et al., Nat. Photon. 15: 914-918, 2021 and some parts of this manuscript are translated from the paper. Medical imaging modalities such as X-ray computed tomography, Magnetic resonance imaging, positron emission tomography (PET), and single photon emission computed tomography, require image reconstruction processes, consequently constraining them to form cylindrical shapes. However, among them, only PET can use additional information, so called time of flight, on an event-by-event basis. If coincidence time resolution (CTR) of PET detectors improved to 30 ps, which corresponds to spatial resolution of 4.5 mm, directly localizing electron-positron annihilation point is possible, allowing us to circumvent image reconstruction processes and free us from the geometric constraint. We call this concept direct positron emission imaging (dPEI). We have developed ultrafast radiation detectors by focusing on Cherenkov photon detection. Furthermore, the CTR of 32 ps being equivalent to 4.8 mm spatial resolution is achieved by combining deep learning-based signal processing with the detectors. In this article, we explain how we developed the detectors and demonstrated the first dPEI using different types of phantoms, how we will tackle limitations to be addressed to make the dPEI more practical, and how dPEI will emerge as an imaging modality in nuclear medicine.

Podoplanin Drives Amoeboid Invasion in Canine and Human Mucosal Melanoma.

Mucosal melanoma metastasizes at an early stage of the disease in human and dog. We revealed that overexpression of podoplanin in tumor invasion fronts (IF) was related to poor prognosis of dogs with mucosal melanoma. Moreover, podoplanin expressed in canine mucosal melanoma cells promotes proliferation and aggressive amoeboid invasion by activating Rho-associated kinase (ROCK)-myosin light chain 2 (MLC2) signaling. PDPN-ROCK-MLC2 signaling plays a role in cell-cycle arrest and cellular senescence escape as a mechanism for regulating proliferation. Podoplanin induces amoeboid invasion in the IFs of mouse xenografted tumor tissues, similar to canine mucosal melanoma clinical samples. We further identified that podoplanin expression was related to poor prognosis of human patients with mucosal melanoma, and human mucosal melanoma with podoplanin-high expression enriched gene signatures related to amoeboid invasion, similar to canine mucosal melanoma. Overall, we propose that podoplanin promotes canine and human mucosal melanoma metastasis by inducing aggressive amoeboid invasion and naturally occurring canine mucosal melanoma can be a novel research model for podoplanin expressing human mucosal melanoma. IMPLICATIONS: Podoplanin could be a new therapeutic target to restrict the metastatic dissemination of canine and human mucosal melanoma.

Podoplanin promotes cell proliferation, survival, and migration of canine non-tonsillar squamous cell carcinoma.

Podoplanin (PDPN) is a prognostic factor and is involved in several mechanisms of tumor progression in human squamous cell carcinoma (SCC). Canine non-tonsillar SCC (NTSCC) is a common oral tumor in dogs and has a highly invasive characteristic. In this study, we investigated the function of PDPN in canine NTSCC. In canine NTSCC clinical samples, PDPN overexpression was observed in 80% of dogs with NTSCC, and PDPN expression was related to ki67 expression. In PDPN knocked-out canine NTSCC cells, cell proliferation, cancer stemness, and migration were suppressed. As the mechanism of PDPN-mediated cell proliferation, PDPN knocked-out induced apoptosis and G2/M cell cycle arrest in canine NTSCC cells. These findings suggest that PDPN promotes tumor malignancies and may be a novel biomarker and therapeutic target for canine NTSCC.

[Analysis of Factors Affecting Proteinuria Onset Timing in Patients Treated with Bevacizumab].

Bevacizumab (BV) is a recombinant and humanized monoclonal antibody that inhibits vascular endothelial growth factor. BV is used to treat various types of cancer. Proteinuria is a characteristic adverse event that occurs as a result of treatment with BV. However, the onset timing of proteinuria after BV administration remains unclear. In the present study, we examined the risk factors affecting the timing of proteinuria onset upon BV administration. Medical records of 135 patients (62 males and 73 females; mean age: 67.8±10.7 years) treated with BV were reviewed at the Kindai University Nara Hospital from April 2011 to December 2019. Proteinuria was identified in 44.4% (60/135) of the studied patients. The time to the first onset of proteinuria was significantly shorter in the administration of doses of BV (≥10) and history of diabetes mellitus. The median cumulative dose associated with the onset of proteinuria was 30.0 (16.1-58.8) mg/kg. When this cumulative dose was compared with 10 mg/kg, no significant difference was observed (p=0.319). The present study demonstrated that the administration of doses of BV (≥10) and history of diabetes mellitus are one of the main risk factors for early-onset proteinuria. These findings may be useful for the future treatment of early-onset proteinuria in patients treated with BV.

Unbiased TOF estimation using leading-edge discriminator and convolutional neural network trained by single-source-position waveforms.

Objective.Convolutional neural networks (CNNs) are a strong tool for improving the coincidence time resolution (CTR) of time-of-flight (TOF) positron emission tomography detectors. However, several signal waveforms from multiple source positions are required for CNN training. Furthermore, there is concern that TOF estimation is biased near the edge of the training space, despite the reduced estimation variance (i.e. timing uncertainty).Approach.We propose a simple method for unbiased TOF estimation by combining a conventional leading-edge discriminator (LED) and a CNN that can be trained with waveforms collected from one source position. The proposed method estimates and corrects the time difference error calculated by the LED rather than the absolute time difference. This model can eliminate the TOF estimation bias, as the combination with the LED converts the distribution of the label data from discrete values at each position into a continuous symmetric distribution.Main results.Evaluation results using signal waveforms collected from scintillation detectors show that the proposed method can correctly estimate all source positions without bias from a single source position. Moreover, the proposed method improves the CTR of the conventional LED.Significance.We believe that the improved CTR will not only increase the signal-to-noise ratio but will also contribute significantly to a part of the direct positron emission imaging.

Biologic Disease-Modifying and Other Anti-Rheumatic Drugs Use in Patients with Moderate-to-Severe Juvenile Idiopathic Arthritis Based on a Japanese Nationwide Claims Database.

Purpose: Biologic disease-modifying anti-rheumatic drugs (bDMARDs) are highly effective and safe against juvenile idiopathic arthritis (JIA), which is classified into systemic JIA (sJIA) and the other JIA categories (non-sJIA) according to differences in clinical symptoms and pathophysiology. The purpose of the current study was to investigate trends in patterns of prescribing bDMARDs for moderate-to-severe JIA using a relatively large sample size in Japan. Patients and Methods: A descriptive epidemiological study based on a nationwide claims database in Japan was conducted from 2012 to 2018 using the "JMDC Claims Database" to explain annual changes based on the number of patients prescribed bDMARDs. Study drugs were identified based on the Anatomical Therapeutic Chemical codes, such as methotrexate, glucocorticoids, non-steroidal anti-inflammatory drugs, and bDMARDs. Results: From a database of 6,862,244 patients, the following exclusion criteria were applied: aged ≥16 years, without "M08" in their ICD-10 code as disease, and missing the information of prescription date in the database during the study period, resulting in a final number of 111 JIA patients. We found an increasing trend for adalimumab and tocilizumab and a decreasing trend for methotrexate. Differences in medication use between sJIA and non-sJIA patients were also evident, being consistent with national and international guidelines. Conclusion: Although the introduction of bDMARDs has markedly improved the efficacy of JIA therapy, there are still many short- and long-term safety issues to be examined, including the risk of infection and potential risk of associated malignancy. Future studies are needed to clarify these issues.

[Photon counting detectors and their applications ranging from particle physics experiments to environmental radiation monitoring and medical imaging].

This is a review article on photon counting detector for radiation measurement by JSRT and JSMP (https://www.jsmp.org/en).

Photon counting detectors and their applications ranging from particle physics experiments to environmental radiation monitoring and medical imaging.

Photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) have played essential roles in various applications, such as fundamental particle physics experiments, nuclear medicine, and environmental radiation monitoring, for several decades. Understandings their physical properties as well as present applications is indispensable for the development and future applications of these detectors. In this review, we describe the physical principles of PMTs and SiPMs and introduce various applications of these detectors.

Relationship between renal dysfunction and electrolyte abnormalities in hematopoietic stem cell transplant patients treated with foscarnet.

This study aimed to investigate the relationship between renal dysfunction and electrolyte abnormalities, which are adverse events of foscarnet used for cytomegalovirus infection. Of the Ninety hematopoietic stem cell transplantation patients, 32 who met the selection criteria were enrolled in this retrospective study. The study patients were divided into two groups according to whether they developed renal dysfunction. The incidences of hypocalcemia, hypokalemia, and hypomagnesemia with an increase of grade 2 or higher in the renal dysfunction group were 45.5%, 18.2%, and 27.3%, respectively. Additionally, in the renal dysfunction group, a significant correlation was observed between creatinine and calcium (r = -0.458, p = 0.0244) and between creatinine and potassium (r = -0.520, p = 0.0092). This study shows that renal dysfunction and electrolyte abnormalities may be closely related in HSCT patients receiving foscarnet; thus, it is a report that may contribute to the safety of continuous foscarnet treatment.

Prescribing Trends of Biologic Disease-Modifying Anti-rheumatic Drugs Using a Claims Database from 6 Million People in Japan.

BACKGROUND AND OBJECTIVE: Biologic disease-modifying anti-rheumatic drugs (bDMARDs) are used either when conventional synthetic DMARDs are ineffective or when disease activity is high and with poor prognostic factors, based on various clinical guidelines. The purpose of this study was to investigate the prescribing trends of bDMARDs for patients with rheumatoid arthritis in Japan, and to clarify whether the pharmacological therapy of bDMARDs is administered based on guidelines. METHODS: We conducted a descriptive epidemiological study from 2012 to 2018 using the JMDC Claims Database, a nationwide claims database, and described the annual changes based on the number of patients prescribed bDMARDs. Anti-rheumatic drugs were identified based on the Anatomical Therapeutic Chemical codes, including methotrexate, glucocorticoids, non-steroidal anti-inflammatory drugs and bDMARDs. RESULTS: From the database including 6,862,244 people, the data of 6407 patients with rheumatoid arthritis were extracted. The present study demonstrated that the proportion of patients prescribed bDMARDs was 1.0 per 1000 people, with those aged ≥ 65 years being the most common age group. The proportion of patients with rheumatoid arthritis who were prescribed bDMARDs increased significantly over time (p < 0.0001). Additionally, the concomitant proportions of methotrexate (p < 0.0001), non-steroidal anti-inflammatory drugs (p < 0.0001) and glucocorticoids (p = 0.0001) prescribed with bDMARDs decreased significantly over time. CONCLUSIONS: The increase in bDMARD monotherapy may be attributed to the new bDMARDs that have been launched sequentially; furthermore, physicians have come to recognise monotherapy as the mainstay of treatment. Future studies must accumulate evidence on the long-term efficacy and safety of bDMARDs.

Anatomical-guided attention enhances unsupervised PET image denoising performance.

Although supervised convolutional neural networks (CNNs) often outperform conventional alternatives for denoising positron emission tomography (PET) images, they require many low- and high-quality reference PET image pairs. Herein, we propose an unsupervised 3D PET image denoising method based on an anatomical information-guided attention mechanism. The proposed magnetic resonance-guided deep decoder (MR-GDD) utilizes the spatial details and semantic features of MR-guidance image more effectively by introducing encoder-decoder and deep decoder subnetworks. Moreover, the specific shapes and patterns of the guidance image do not affect the denoised PET image, because the guidance image is input to the network through an attention gate. In a Monte Carlo simulation of [18F]fluoro-2-deoxy-D-glucose (FDG), the proposed method achieved the highest peak signal-to-noise ratio and structural similarity (27.92 ± 0.44 dB/0.886 ± 0.007), as compared with Gaussian filtering (26.68 ± 0.10 dB/0.807 ± 0.004), image guided filtering (27.40 ± 0.11 dB/0.849 ± 0.003), deep image prior (DIP) (24.22 ± 0.43 dB/0.737 ± 0.017), and MR-DIP (27.65 ± 0.42 dB/0.879 ± 0.007). Furthermore, we experimentally visualized the behavior of the optimization process, which is often unknown in unsupervised CNN-based restoration problems. For preclinical (using [18F]FDG and [11C]raclopride) and clinical (using [18F]florbetapir) studies, the proposed method demonstrates state-of-the-art denoising performance while retaining spatial resolution and quantitative accuracy, despite using a common network architecture for various noisy PET images with 1/10th of the full counts. These results suggest that the proposed MR-GDD can reduce PET scan times and PET tracer doses considerably without impacting patients.