Climate change is an important public health challenge, and healthcare itself contributes to greenhouse gas emissions. Within healthcare, radiology is energy intensive because modern imaging services require high-power equipment, cooling systems, digital infrastructure, consumables, and continuous operational readiness. This review summarizes current evidence on the environmental footprint of radiology and discusses practical strategies for implementing Green Radiology, with particular attention to Japan. Life cycle assessment studies indicate that the operational phase of imaging systems, especially electricity use, is an important contributor to radiology-related emissions, while non-productive idle periods represent a key opportunity for mitigation. MRI, CT, interventional radiology, picture archiving and communication systems, workstations, and emerging artificial intelligence (AI)-related infrastructure each contribute to this footprint in different ways. Practical measures include equipment power management, workflow optimization, protocol optimization, energy-aware information technology management, careful implementation of AI, and reduction of low-value imaging, many of which may also improve operational efficiency and reduce costs. However, these strategies must be implemented with attention to emergency readiness, scanner warm-up requirements, diagnostic accuracy, patient safety, and clinical workflow. In Japan, high CT and MRI scanner density with relatively low per-scanner utilization may increase non-productive energy use, but broad equipment distribution also supports accessibility, regional equity, and emergency preparedness. At the system level, reducing the environmental footprint of radiology in Japan therefore requires balanced regional coordination, shared resource utilization, selective consolidation where appropriate, and effective allocation of limited radiologist resources. Green Radiology should aim to reduce avoidable environmental burden while maintaining diagnostic accuracy, patient safety, equitable access to medical imaging, and high-quality patient care.

Predicting isocitrate dehydrogenase (IDH) mutations in gliomas using magnetic resonance imaging (MRI) is clinically important for treatment planning. This study compared two artificial intelligence (AI) models, GliomaDepth-IDH (ResNet34-based) and GliomaVista-IDH (Vision Transformer-based), with 18 physicians (eight neuroradiologists, five neurosurgeons, and five neurosurgery residents) in predicting IDH mutation status. On the Brain Tumor Segmentation Challenge dataset, the GliomaVista-IDH AI model achieved an area under the curve (AUC) value of 0.97, significantly outperforming all physician groups. However, external validation on a Japanese cohort revealed performance degradation: GliomaDepth-IDH declined to an AUC of 0.75 and GliomaVista-IDH to 0.82, with GliomaVista-IDH showing significant calibration issues (Brier score = 0.32). High-performing physicians achieved comparable results (AUC = 0.88) with superior calibration (Brier score = 0.19). Inter-rater reliability analysis revealed substantial variability across physician groups. These findings suggest that AI models can assist many physicians, while experienced practitioners remain competitive with better-calibrated predictions in challenging domains.

Abusive head trauma in infants and young children can have a significant impact on neurological outcomes and, in severe cases, may be life-threatening. We report 3 cases of abusive head trauma that presented with acute subdural hematomas on computed tomography scans, accompanied by extensive low-density areas and parenchymal brain swelling. All patients exhibited impaired consciousness due to brain injury and underwent craniotomy for hematoma evacuation as well as extensive decompressive craniectomy. Despite the severity of the initial presentation, hemiparesis was mild and gradually improved over several months. Postoperative magnetic resonance imaging revealed widespread parenchymal injury but preservation of the corticospinal tract, including the precentral gyrus. In the acute phase, diffusion-weighted imaging showed no irreversible infarction in the motor cortex, and arterial spin labeling demonstrated increased perfusion in peri-motor regions of the affected hemisphere. These findings suggest that preserved corticospinal pathways and compensatory hyperperfusion may correlate with favorable motor recovery even in the presence of extensive parenchymal damage. These cases highlight the radiological features and short-term neurological outcomes of abusive head trauma, demonstrating preserved motor function despite extensive parenchymal damage.

Acute superior mesenteric artery (SMA) embolism is potentially fatal if intestinal necrosis develops, and prompt revascularization is essential. Although thrombolytic therapy and aspiration thrombectomy are commonly employed, thrombolysis is contraindicated in patients with hemorrhagic lesions. We report the application of the continuous aspiration prior to intracranial vascular embolectomy (CAPTIVE) technique in an elderly woman with acute SMA embolism complicated by hemorrhagic stroke. Mechanical thrombectomy using a React 71 aspiration catheter and Solitaire stent retriever was performed under proximal balloon flow control. Staged thrombectomy of the jejunal and ileal branches achieved wide recanalization with a limited number of passes, avoiding intestinal necrosis. This case highlights the feasibility of adapting an established neuroendovascular technique to visceral arterial occlusion. The CAPTIVE technique may represent a minimally invasive alternative in selected patients in whom thrombolytic therapy is not indicated.

Cerebral radiation necrosis (CRN) is a late complication that can occur after the treatment of a brain tumor with focal radiation therapy, particularly stereotactic radiosurgery (SRS). Since an excessive production of vascular endothelial growth factor (VEGF) from necrotic lesions is a possible etiology of radiation necrosis, the anti-VEGF antibody bevacizumab has been reported as an effective treatment option. We report a case of a 71-year-old Japanese male with CRN following SRS, successfully treated with bevacizumab. He had presented with aphasia and right lower-limb muscle weakness 6 years after a left upper lobectomy for lung adenocarcinoma. Head magnetic resonance imaging (MRI) showed a metastatic brain tumor in the left temporal lobe. A craniotomy and pre- and post-operative SRS treatments were performed to relieve his neurological symptoms. Although initial symptom improvement was observed, the patient developed lower-limb muscle weakness and aphasia symptoms 7 months after the last SRS treatment. 11C-methionine positron emission tomography (PET) and 18F-fluorodeoxyglucose PET scans showed no abnormal uptake, leading to a diagnosis of CRN. The patient was treated with bevacizumab 15 mg/kg every 3 weeks for six cycles. The bevacizumab treatment resulted in an improvement of neurological symptoms and lesions showing gadolinium-enhancing effects and high-signal areas on T2-weighted fluid attenuated inversion recovery on MRI. The improvement was maintained 44 months after the completion of the last bevacizumab treatment. Although no definitive number of cycles and dosage of bevacizumab for CRN have been established, this case suggests that administering six cycles of bevacizumab may prevent long-term recurrence of CRN.

Background:Novel anticoagulants targeting coagulation factor (F)XI/activated FXI (FXIa) are currently under development. However, whether FXI is present in human deep vein thrombosis (DVT) and whether FXIa and activated FX (FXa) play different roles in venous thrombus formation and hemostasis remain unclear. Objectives:To determine the presence of FXI in DVT and the effects of direct oral FXIa and FXa inhibitors on venous thrombus formation and hemostasis in rabbits and on in vitro thrombus formation. Methods:We immunohistochemically assessed FXI localization in human-aspirated DVT (n = 15). Additionally, we compared thrombus formation induced by endothelial denudation and stenosis or stasis in the jugular vein and skin bleeding time and volume between rabbits treated with direct FXIa inhibitors (ONO-1600586) and FXa inhibitors (rivaroxaban). Ex vivo rabbit and human blood were perfused in a flow chamber under low-shear rates (70/s). Results:FXI was localized in all DVT, predominantly in fibrin-rich areas. The FXI immunopositive area in the nonorganizing area was greater than that in the organizing area. Although FXIa and FXa inhibitors comparably inhibited venous thrombus formation, FXIa inhibitors did not affect bleeding time or volume in rabbits. FXIa or FXa inhibitors mildly or strongly inhibited fibrin formation at low-shear rates, respectively. Furthermore, the FXIa inhibitor suppressed human FXIa activity, thrombin generation, and fibrin formation during perfusion. Conclusion:The pathologic findings of human DVT suggest FXI's role in human DVT. FXIa inhibitors may inhibit less fibrin formation than FXa inhibitors and may explain the minor role of FXIa in hemostasis.

A 72-year-old woman with a history of breast cancer presented with left oculomotor nerve palsy. Magnetic resonance imaging revealed a progressive mass lesion in the cavernous sinus. Initially, Tolosa-Hunt syndrome and metastatic brain tumor from breast cancer were suspected; however, radiological differentiation proved challenging. Pathological examination confirmed the diagnosis of primary intracranial Ewing sarcoma. The tumor exhibited progressive growth, and Gamma Knife radiosurgery was performed. After treatment, tumor shrinkage and symptomatic improvement were observed. Ewing sarcoma typically occurs in children and young adults; however, the safety and efficacy of chemotherapy in older populations remain largely unstudied. In this older patient, the rare location of the tumor within the cavernous sinus posed challenges to surgical resection. Chemotherapy was administered at a reduced dose of 50%, with limited side effects. After 7 cycles of chemotherapy, tumor showed further shrinkage, and no recurrence was observed. This case demonstrates that, even in rare tumors with unestablished chemotherapy protocols for older patients, satisfactory outcomes can be achieved with accurate pathological diagnosis and a multidisciplinary treatment approach.

Objective: Discriminating between hemorrhage and iodine extravasation can pose challenges in conventional computed tomography (CCT) images following preoperative embolization for meningioma. This study aimed to assess the efficacy of dual-energy computed tomography (DECT) in differentiating hemorrhage from iodine extravasation after preoperative embolization for meningioma. Methods: Twenty-one consecutive meningioma patients who underwent CCT before and DECT immediately after preoperative embolization were included in this study. Two independent observers conducted qualitative assessments on CCT and virtual noncontrast (VNC) images and iodine maps (IMs) to differentiate between hemorrhage and iodine extravasation. One observer recorded CT values of hemorrhage and iodine extravasation on CCT and VNC images. The ratio of maximum attenuation to minimum attenuation on VNC images was defined as the VNC ratio. Statistical analysis included Kappa (kappa) statistics, unpaired t tests, and receiver operating characteristic (ROC) analysis. Results: Interobserver agreement for qualitative assessment was fair (kappa = 0.231) for CCT alone and good (kappa = 0.723) for CCT plus VNC imaging and IM. The addition of VNC imaging and IM to CCT improved differential confidence in 16 (76%) and 18 (86%) cases of the two observers, respectively, increasing the area under the receiver operating characteristic curve (AUROC) from 0.868 to 0.895 and 0.658 to 0.947, respectively. At a cutoff value of 1.527, the VNC ratio was significantly higher for hemorrhage than iodine extravasation (P < 0.05), with the highest diagnostic performance (AUROC, 1). Conclusions: DECT with VNC imaging and IM is useful for differentiating hemorrhage from iodine extravasation in meningiomas with preoperative embolization.

PURPOSE:The development of dual energy CT (DECT) has made it possible to provide not only morphological characteristics but also a wide range of quantitative information. The purpose of this study is to differentiate between benign and malignant solitary pulmonary nodules (SPN) by using electron density values obtained from DECT. METHODS:From the image data diagnosed as SPN, DECT images of 54 cases were selected, and the maximum electron density values of SPN were obtained. Electron density values were compared between benign and malignant cases by t-test. Comparisons between histopathological types and histological subtypes were performed by ANOVA. Logistic regression analysis was also applied to estimate the partial regression coefficients on electron density values. RESULTS:Electron density values were 3.56×1020/mm3 for malignant and 3.51×1020/mm3 for benign, with malignancy being significantly higher (p<0.001). ROC analysis showed that the AUC was 0.77. In a comparison between histopathologic types, electron density values were significantly higher for adenocarcinoma and squamous cell carcinoma (p<0.05). There were no significant differences among subtypes. Logistic regression analysis showed a regression coefficient of 1.24 (p<0.01). CONCLUSION:Electron density values obtained from dual energy CT may serve as a useful quantitative parameter for differentiating between benign and malignant SPN. However, attention should be paid to certain histological subtypes, such as invasive mucinous adenocarcinoma, which may exhibit exceptionally low values.

Background Fibroblast activation protein-α (FAP), a type-II transmembrane serine protease, is associated with wound healing, cancer-associated fibroblasts, and chronic fibrosing diseases. However, its expression in deep vein thrombosis (DVT) remains unclear. Therefore, this study investigated FAP expression and localization in DVT. Methods We performed pathological analyses of the aspirated thrombi of patients with DVT (n = 14), classifying thrombotic areas in terms of fresh, cellular lysis, and organizing reaction components. The organizing reaction included endothelialization and fibroblastic reaction. We immunohistochemically examined FAP-expressed areas and cells, and finally analyzed FAP expression in cultured dermal fibroblasts. Results All the aspirated thrombi showed a heterogeneous mixture of at least two of the three thrombotic areas. Specifically, 83 % of aspirated thrombi showed fresh and organizing reaction components. Immunohistochemical expression of FAP was restricted to the organizing area. Double immunofluorescence staining showed that FAP in the thrombi was mainly expressed in vimentin-positive or α-smooth muscle actin-positive fibroblasts. Some CD163-positive macrophages expressed FAP. FAP mRNA and protein levels were higher in fibroblasts with low-proliferative activity cultured under 0.1 % fetal bovine serum (FBS) than that under 10 % FBS. Fibroblasts cultured in 10 % FBS showed a significant decrease in FAP mRNA levels following supplementation with hemin, but not with thrombin. Conclusions The heterogeneous composition of venous thrombi suggests a multistep thrombus formation process in human DVT. Further, fibroblasts or myofibroblasts may express FAP during the organizing process. FAP expression may be higher in fibroblasts with low proliferative activity.

Background: Plaque erosion, a type of coronary atherothrombosis, involves superficial injury to smooth muscle cell (SMC)-rich plaques. Elevated levels of coagulation factor VIII (FVIII) correlate with an increased ischemic heart disease risk. FVIII may contribute to thrombus formation on eroded plaques. Aims: We aimed to elucidate the role of elevated FVIII in arterial thrombus formation within SMC-rich neointima in rabbits. Methods and results: We assessed the effect of recombinant human FVIII (rFVIII) on blood coagulation in vitro and platelet aggregation ex vivo. An SMC-rich neointima was induced through balloon injury to the unilateral femoral artery. Three weeks after the first balloon injury, superficial erosive injury and thrombus formation were initiated with a second balloon injury of the bilateral femoral arteries 45 min after the administration of rFVIII (100 IU/kg) or saline. The thrombus area and contents were histologically measured 15 min after the second balloon injury. rFVIII administration reduced the activated partial thromboplastin time and augmented botrocetininduced, but not collagen- or adenosine 5 '-diphosphate-induced, platelet aggregation. While rFVIII did not influence platelet-thrombus formation in normal intima, it increased thrombus formation on SMC-rich neointima post-superficial erosive injury. Enhanced immunopositivity for glycoprotein IIb/IIIa and fibrin was observed in rFVIII-administered SMC-rich neointima. Neutrophil count in the arterial thrombus on the SMC-rich neointima correlated positively with thrombus size in the control group, unlike the rFVIII group. Conclusions: Increased FVIII contributes to thrombus propagation within erosive SMC-rich neointima, highlighting FVIII's potential role in plaque erosion-related atherothrombosis.

Background Fibroblast activation protein-α (FAP), a type-II transmembrane serine protease, is expressed during wound healing, in cancer-associated fibroblasts, and in chronic fibrosing diseases. However, its expression in deep vein thrombus (DVT) remains unclear. Therefore, in this study, we investigated FAP expression and localization in DVT.Methods First, we pathologically accessed aspirated thrombi of patients with DVT (n=14), classifying thrombotic areas as follows; fresh, cellular lysis, endothelialization, fibroblastic reaction. Endothelialization and fibroblastic reaction were defined as organizing reactions. We immunohistochemically examined FAP-expressed areas and expressed cells. Second, we analyzed FAP expression in cultured dermal fibroblasts.Results All the aspirated thrombi showed a mixture of at least three of the four thrombotic areas. Specifically, 83 % of aspirated thrombi showed fresh and organizing reactions within each thrombus. Immunohistochemical expression of FAP was restricted in organizing area. Further, FAP expression in the thrombi was mainly found in vimentin-positive or α-smooth muscle actin-positive fibroblasts in double immunofluorescence. Some CD163-positive macrophages also showed FAP expression. FAP mRNA and protein levels significantly increased in cultured fibroblasts with low- proliferative activity under 0.1% fetal bovine serum (FBS) than that in fibroblasts under 10% FBS. Fibroblasts cultured in 10% FBS showed a significant decrease in FAP mRNA levels following supplementation with hemin, but not with thrombin.Conclusions The heterogeneous composition of the venous thrombi suggests the existence of a multistep thrombus formation process in human DVT. Further, fibroblasts or myofibroblasts may express FAP in organizing process in DVT. FAP expression may increase in fibroblasts with low-proliferative activity.### Competing Interest StatementThe authors have declared no competing interest.* CAF : cancer-associated fibroblast DMEM : Dulbecco’s Modified Eagle medium DVT : deep vein thrombosis FAP : fibroblast activation protein-α FBS : fetal bovine serum GP IIb/IIIa : glycoprotein IIb/IIIa SMA : smooth muscle actin

PURPOSE:Three-dimensional (3D) quantification using an interleaved Look-Locker acquisition sequence with a T2 preparation pulse (QALAS) is a quantitative sequence used to measure relaxation times. The accuracy of the relaxation time measurement of 3D-QALAS at 3.0 T and the bias of 3D-QALAS have not yet been assessed. The purpose of this study was to clarify the accuracy of the relaxation time measurements using 3D-QALAS at 3.0 T MRI.METHODS:The accuracy of the T1 and T2 values for 3D-QALAS was evaluated using a phantom. Subsequently, the T1 and T2 values and proton density of the brain parenchyma in healthy subjects were measured using 3D-QALAS and compared with those of 2D multi-dynamic multi-echo (MDME).RESULTS:In the phantom study, the average T1 value of 3D-QALAS was 8.3% prolonged than that for conventional inversion recovery spin-echo; the average T2 value for 3D-QALAS was 18.4% shorter than that for multi-echo spin-echo. The in vivo assessment showed that the mean T1 and T2 values and PD for 3D-QALAS were prolonged by 5.3%, shortened by 9.6%, and increased by 7.0%, respectively, compared with those for 2D-MDME.CONCLUSION:Although 3D-QALAS at 3.0 T has high accuracy T1 value, which is less than 1000 ms, the T1 value could be overestimated for tissues with it longer than that T1 value. The T2 value for 3D-QALAS could be underestimated for tissues with T2 values, and this tendency increases with longer T2 values.

Intracranial hypostasis is a common postmortem change evident on postmortem CT (PMCT), but can be readily misinterpreted as subdural hematoma by inexperienced physicians. Although PMCT is necessarily lacking contrast enhancement, we reconstructed hypostatic sinuses into three-dimensional images resembling the results of in vivo venography. This simple methodology facilitates easy recognition of intracranial hypostasis.

OBJECTIVE: Craniopharyngiomas remain surgically challenging because of the strong adhesion to vital neurovascular structures. We propose a system for the se-lection of surgical approaches based on the optic recess (OR) displacement pattern to facilitate surgical planning and obtain optimum visual and endocrinologic outcomes.METHODS: Craniopharyngiomas were divided into 3 types based on the OR displacement pattern: superior, anterior, and involvement types. Selected surgical approaches and patient outcome were retrospectively reviewed according to these classifications. Visual and endocrinologic outcomes were compared among the groups. -RESULTS: This study included 26 patients with primary craniopharyngiomas who underwent surgery at our institution, classified into 11 anterior, 11 superior, and 4 involvement types. The extended endoscopic endonasal approach provided excellent exposure inferodorsal aspect of the chiasm for manipulation of the dissection plane in the anterior and superior types with midline location. A -nilateral subfrontal approach was required for tumor of the superior type with lateral extension. An interhemispheric translamina terminalis approach could provide safe dissection under direct vision of strong adhesion at the superior aspect of the chiasm in the involvement type. Visual and endocrinologic outcomes were better in the involvement type compared with the superior and anterior types. Visual outcome was significantly correlated with preoperative visual function.CONCLUSIONS: Craniopharyngiomas with the involve-ment type are indicated for the translamina terminalis approach to achieve the best visual and endocrinologic outcome. Our classification of the OR displacement pattern is useful to select the optimal surgical approach for cra-n iopharyngiomas more accurately and concisely, espe-cially in cases with third ventricular extension.

In 2022, a follow-up survey was conducted to the National Survey on Safety Management of MRI Examinations carried out in 2018. This study aimed to compare the two surveys to determine how the “Guidelines for the Safe Operation of Clinical MRI” affect the safe management of MRI examinations in clinical practice, and to identify factors associated with incidents affecting patient health. Automated machine learning was used to identify factors associated with major incidents. Of the 5,816 medical facilities we approached, 2,668 (45.9%) provided full or partial responses, with 2,582 (44.4%) valid responses. Although the number of facilities that participated in the survey and provided valid responses had increased by 567 from the previous survey, the response to safety management varied again in this survey. On the other hand, improvement was seen on most items related to safety management and MRI exam operations. Between October 2020 and September 2021, 242 major incidents occurred at 166 facilities (6%), a 1% increase from 2018. Most of these were related to contrast administration. Minor incidents also increased by 5% (2,068 incidents) at 833 facilities (32%). The largest contributor to the increase in major incidents was the number of examinations per month. Although there was wide variation in the safety standards applied by Japanese facilities performing clinical MRI examinations, facility responses improved for most items related to the safe management and operation of MRI scans.

A 48-year-old woman underwent transcatheter arterial embolization (TAE) for a splenic artery aneurysm, which resulted in a partial splenic infarction in the middle lobe. Five years after TAE, a 20-mm diameter mass in the noninfarcted area of the spleen was detected on imaging, which grew to 25 mm in diameter after 6 months. MRI after gadolinium administration showed a 35 × 34 mm mass within the superior pole and 15 × 12 mm mass within the inferior pole. The patient underwent laparoscopic splenectomy and had an uneventful postoperative recovery. No evidence of recurrence was observed during the 2-year follow-up period after surgery. The mass was pathologically confirmed to be sclerosing angiomatoid nodular transformation (SANT) of the spleen. While some studies hypothesize that SANT is a response to vascular injury or trauma, to the best of our knowledge, there have been no previous reports of SANT occurring after procedures directly affecting splenic blood flow. Additionally, multifocal SANTs are reported to be very rare, accounting for only 4.7

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (>= 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.