Influence of region-of-interest determination on measurement of signal-to-noise ratio in liver on PET images

Objective

On ¹⁸F-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography (PET), signal-to-noise ratio in the liver (SNR_liver) is used as a metric to assess image quality. However, some regions-of-interest (ROIs) are used when measuring the SNR_liver. The purpose of this study is to examine the different ROIs and volumes of interest (VOIs) to obtain a reproducible SNR_liver.

Methods

This study included 108 patients who underwent ¹⁸F-FDG-PET/CT scans for the purpose of cancer screening. We examined four different ROIs and VOIs; a 3-cm-diameter and a 4-cm-diameter circular ROI and a 3-cm-diameter and a 4-cm-diameter spherical VOI on the right lobe of the patients’ livers. The average of SUV (SUV_mean), standard deviation (SD) of SUV (SUV_SD), SNR_liver and SD of the SNR_liver obtained using ROIs and VOIs were then compared.

Results

Although the SUV_mean was not different among the ROIs and VOIs, the SUV_SD was small with a 3-cm-diameter ROI. The largest SUV_SD was obtained with a 4-cm-diameter spherical VOI. The SNR_liver and the SD of the SNR_liver with a 4-cm-diameter spherical VOI were the smallest, while those with a 3-cm-diameter circular ROI were the largest. These results suggest that a small ROI may be placed on a relatively homogeneous region not representing whole liver unintentionally.

Conclusion

The SNR_liver varied according to the shape and size of ROIs or VOIs. A 4-cm-diameter spherical VOI is recommended to obtain stable and reproducible SNR_liver.

     

Congenitally corrected transposition of the great arteries treated by partial systemic ventriculectomy.

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart disease characterized by atrioventricular (AV) and ventriculo-arterial discordance;(1) that is, the left ventricle supports the pulmonary circulation and the right ventricle supports the systemic circulation. The most common cardiac anomalies in CCTGA include ventricular septal defect, pulmonary outflow tract obstruction and abnormalities of the systemic AV valve. (1) The dysfunction of the systemic ventricle occurs with increasing frequency in older patients with CCTGA, independent of their commonly associated structural defects.(2-4) We report a patient with CCTGA undergone the partial ventriculectomy for his systemic ventricular dysfunction.     

Lymphocytic hypophysitis accompanied by aseptic meningitis mimics subacute meningoencephalitis

A 66-year-old man was admitted to our hospital with muscle pain, fatigue and appetite loss that had lasted for a month. The patient was somnolent and had nuchal stiffness with a high fever. Cerebrospinal fluid (CSF) tests demonstrated lymphocytic pleocytosis with a decreased CSF-blood glucose ratio. The tests for tuberculous, fungal and carcinomatous meningitis and herpetic meningoencephalitis were negative. Endocrinological exams showed hypopituitarism and diabetes insipidus. A pituitary MRI showed an enlargement of the pituitary stalk. A diagnosis of lymphocytic hypophysitis with aseptic meningitis was made after the exclusion of secondary hypophysitis. Lymphocytic hypophysitis with aseptic meningitis can mimic subacute meningoencephalitis.     

IgA attenuates anaphylaxis and subsequent immune responses in mice: possible application of IgA to vaccines

Administration of the influenza vaccination to patients with an egg allergy is major health concern. Contaminating egg antigens occasionally induce severe anaphylactic shock in these patients following administration of the vaccination; therefore, the development of a safer vaccination is needed. In the present study, we investigated whether a mixture of four newly and previously generated anti-ovalbumin (OVA) IgA monoclonal antibodies (mAbs) could inhibit both anaphylactic shock upon a subcutaneous OVA challenge and subsequent further sensitization against OVA in passively anti-OVA IgE-sensitized mice and actively sensitized mice with an injection of OVA. The prevention of anaphylaxis by anti-OVA IgA mAbs was suggested to be mediated through the inhibition of OVA binding to allergenic antibodies such as anti-OVA IgE on mast cells and deceleration of the rate of OVA penetration from the injected site into the systemic circulation. Anti-OVA IgA mAbs inhibited further sensitization against OVA in mice actively sensitized with OVA, but did not affect sensitization against the unrelated antigen, phosphorylcholine-keyhole limpet hemocyanin co-injected with OVA. Our findings indicate that adding the anti-egg antigen IgA to the influenza vaccine should reduce not only the risk of inducing anaphylactic shock, but also undesired further sensitization against egg antigens following the vaccination without affecting the intended beneficial effect of the vaccine, namely the upregulation of immune responses to influenza viruses.     

Prevalence of thromboembolic events and status of prophylactic anticoagulant therapy in hospitalized patients with COVID-19 in Japan

IntroductionOne of the most prominent and concerning complications associated with coronavirus disease 2019 (COVID-19) is venous and arterial thromboembolisms. The aim of the present study was to delineate the prevalence of thromboembolic events and the current status of prophylactic anticoagulation therapy in patients with COVID-19 in Japan.MethodsBetween February 1 and August 31, 2020, we performed a dual-center, retrospective cohort study based on data obtained from the medical charts of COVID-19 patients admitted to healthcare facilities in Japan. The primary outcome was any thromboembolic event including pulmonary embolism (PE), deep vein thrombosis (DVT), myocardial infarction, ischemic stroke and other systemic thromboemboli.ResultsDuring the study period, we extracted 628 consecutive patients admitted for COVID-19. Prophylactic anticoagulant therapy was administered in 63 (10%) patients of whom 20 (31.7%) were admitted to the intensive care unit (ICU). Thromboembolic events occurred in 18 (2.9%) patients (14.3% of patients in ICU and 2.2% of patients in the general wards). DVT were detected in 13 (2.1%) patients, PE in 11 (1.8%), and both DVT and PE in 6 (0.96%) patients. An increasing prevalence in thromboembolic events was noted with progressive clinical severity. Overall in-hospital mortality was 4.8%.ConclusionsProphylactic anticoagulation therapy was administered in only 10% of all hospitalized COVID-19 patients. The prevalence of any thromboembolic events was 2.9% in COVID-19 patients with most events occurring in severe and critical patients. Therefore, prophylactic anticoagulation therapy may be warranted in severe and critical patients but in asymptomatic to moderate patients the practice remains controversial.     

Defective induction of the proteasome associated with T‐cell receptor signaling underlies T‐cell senescence

The proteasome degradation machinery is essential for a variety of cellular processes including senescence and T‐cell immunity. Decreased proteasome activity is associated with the aging process; however, the regulation of the proteasome in CD4⁺ T cells in relation to aging is unclear. Here, we show that defects in the induction of the proteasome in CD4⁺ T cells upon T‐cell receptor (TCR) stimulation underlie T‐cell senescence. Proteasome dysfunction promotes senescence‐associated phenotypes, including defective proliferation, cytokine production and increased levels of PD‐1⁺ CD44^High CD4⁺ T cells. Proteasome induction by TCR signaling via MEK‐, IKK‐ and calcineurin‐dependent pathways is attenuated with age and decreased in PD‐1⁺ CD44^High CD4⁺ T cells, the proportion of which increases with age. Our results indicate that defective induction of the proteasome is a hallmark of CD4⁺ T‐cell senescence.