Association of cardiothoracic ratio with heart failure hospitalization in patients with atrial fibrillation: the Fushimi AF Registry

Background

Chest radiography is the most common diagnostic imaging test in clinical medicine, and the cardiothoracic ratio (CTR) is a readily available and non-invasive tool with which to assess the volume status and cardiomegaly. However, it remains unknown whether CTR on chest radiography is associated with the incidence of HF hospitalization in AF patients remains unclear.

Methods

The Fushimi AF Registry is a community-based prospective survey of AF patients in Fushimi-ku, Kyoto, Japan. The inclusion criterion of the registry is the documentation of AF at 12-lead electrocardiogram or Holter monitoring at any time, and there are no exclusion criteria. We started to enroll patients from March 2011, and follow-up data were available for 4,489 patients by the end of August 2021. In the present study, 3,727 patients with available data of CTR were examined. We divided the patients into two groups according to their CTR at baseline; Higher group (CTR ≥50.0%, n=2,696) and Lower group (CTR <50.0%, n=1,031), and compared the clinical background and outcomes between the two groups.

Results

The proportion of female was grater in Higher group, and the patients in Higher group were older. The patients in Higher group had higher prevalence of HF, hypertension and chronic kidney disease. During the median follow-up of 3,033 days, in Kaplan-Meier analysis, the incidence rates of HF hospitalization were higher in Higher group (Higher group: 2.5% per person-year vs. Lower group: 1.1%; p<0.01). Multivariate Cox proportional hazards regression analysis revealed that higher CTR (≥50.0%) was an independent determinant of the incidence of HF hospitalization. Furthermore, when we divided the patients into four groups based on the quartile of CTR; Q1 (CTR<49.0%), Q2 (49.0≤CTR<53.8%), Q3 (53.8≤CTR<59.0%), Q4 (59.0%≤CTR), the incidence of HF hospitalization was more frequent in patients with higher CTR, regardless of the presence or absence of prior hospitalization for HF (Figure).

Conclusion

In Japanese AF patients, patients with higher CTR had significantly higher incidence of HF hospitalization, regardless of the prevalence of prior hospitalization for HF.

Funding Acknowledgement

Type of funding sources: None.

The association of left ventricular ejection fraction with incident heart failure in patients with atrial fibrillation

Background

Atrial fibrillation (AF) increases the risk of incident heart failure (HF). Left ventricular ejection fraction (LVEF) is an important prognostic parameter in patients with HF. However, little is known regarding the association of LVEF with incident HF in patients with AF.

Purpose

The aim of this study is to investigate the relationship between LVEF at enrollment and incidence of HF hospitalization during follow-up period in patients with AF.

Methods

The Fushimi AF Registry is a community-based prospective survey of patients with AF in Fushimi-ku, Kyoto, Japan. The inclusion criterion of the registry is the documentation of AF at 12-lead electrocardiogram or Holter monitoring at any time, and there are no exclusion criteria. We started to enroll patients from March 2011, and follow-up data were available for 4,489 patients by the end of August 2021. In the present study, we investigated 3,544 patients with the data of LVEF at enrollment. We divided the patients into 4 groups stratified by LVEF (reduced LVEF [LVEF <40%], mildly reduced LVEF [LVEF: 40–49%], slightly reduced LVEF [LVEF: 50–59%], and normal LVEF [LVEF ≥60%]), and compared the backgrounds and outcomes between these 4 groups.

Results

Of 3,544 patients, the mean age was 73.6±10.7 years, 1,420 (40%) were female, 1,781 (50%) were paroxysmal AF, and 1,085 (30%) had pre-existing HF. The mean CHADS2 and CHA2DS2-VASc scores were 2.1±1.3 and 3.4±1.7, respectively. The mean LVEF at enrollment was 63±12% (reduced LVEF: 197 [6%], mildly reduced LVEF: 250 [7%], slightly reduced LVEF: 532 [15%] and normal LVEF: 2,565 [72%], respectively). Patients with lower LVEF demonstrated lower prevalence of female and paroxysmal AF, and had a higher CHADS2 and CHA2DS2-VASc scores (all P<0.01). A total of 605 patients were hospitalized for HF during the median follow-up period of 5.5 years, corresponding to an annual incidence of 3.4% per person-year. Kaplan-Meier curves demonstrated that LVEF at enrollment could stratify the incidence of HF hospitalization during follow-up in patients with AF (Picture 1). Multivariable Cox regression analysis revealed that lower LVEF strata were significantly associated with the increased risk of HF hospitalization even after adjustment by age, sex, type of AF and CHA2DS2-VASc score (Picture 1). An increased risk of HF hospitalization was observed even in patients with mildly reduced LVEF (adjusted hazard ratio: 2.56, 95% CI: 1.99–3.29) as well as in those with slightly reduced LVEF (adjusted hazard ratio: 1.79, 95% CI: 1.45–2.22) compared with those with normal LVEF. These results were also the case in AF patients without pre-existing HF (Picture 2).

Conclusion

LVEF at enrollment could stratify the incidence of HF hospitalization in patients with AF, suggesting the importance of measuring LVEF in all patients with AF. Even mildly (LVEF: 40–49%) or slightly (LVEF: 50–59%) reduced LVEF was independently associated with the risk of incident HF in patients with AF.

Funding Acknowledgement

Type of funding sources: None.

Previous pacemaker therapy was not associated with the risk of clinical events in patients with atrial fibrillation: the Fushimi AF Registry

Background

Patients with atrial fibrillation (AF) occasionally require pacemaker implantation. Meanwhile, patients with implanted pacemaker are occasionally found to have subclinical AF and develop clinical AF. However, little is known about the clinical outcomes of AF patients with implanted pacemaker.

Purpose

We aimed to investigate the clinical outcomes in AF patients undergoing previous pacemaker therapy.

Methods

The Fushimi AF Registry is a community-based prospective survey of the AF patients in a city of Japan. Follow-up data including prescription status were available for 4,447 patients. After exclusion of patients with implantable cardioverter defibrillator and cardiac resynchronization therapy, we investigated 293 AF patients with pacemaker implantation at baseline. We performed propensity score-matching analysis to assess the impact of pacemaker therapy in AF patients.

Results

Of a total cohort, patients with pacemaker were more often female (51.2% vs. 39.7%; p<0.01) and older (78.0 vs. 73.3 years of age; p<0.01). Patients with pacemaker were more likely to have pre-existing heart failure (33.1% vs. 26.6%; p<0.01), valvular heart disease (22.9% vs. 16.8%; p<0.01), chronic kidney disease (48.8% vs. 34.7%; p<0.01), and history of performing direct current cardioversion (7.2% vs. 3.1%; p<0.01), compared with patients without pacemaker. Mean CHA2DS2-VASc score was higher in patients with pacemaker (3.80 vs. 3.34; p<0.01). Patients with pacemaker were more often prescribed oral anticoagulants (62.1% vs. 55.2%; p=0.02), verapamil (13.3% vs. 9.4%; p=0.03), and loop diuretics (30.7% vs. 21.8%; p<0.01). Using propensity score-matching, 291 patients with pacemaker and 291 without pacemaker were matched and baseline characteristics were comparable. The median follow-up period was 1,819 days. All-cause death occurred in 91 patients with pacemaker (6.0 /100 person-years) and 79 patients without pacemaker (5.9 /100 person-years), with a hazard ratio (HR) for patients with pacemaker of 1.01 (95% confidence interval [CI], 0.75 to 1.37; p=0.93). Furthermore, HR of cardiac death for patients with pacemaker was 1.00 (95% CI, 0.23 to 4.32; p=0.99), that of stroke or systemic embolism was 0.69 (95% CI, 0.44 to 1.07; p=0.10) and that of hospitalization for heart failure was 0.94 (95% CI, 0.65 to 1.37; p=0.76).

Conclusion

We identified that patients undergoing previous pacemaker therapy were not associated with the incidence of various adverse clinical events in Japanese AF patients.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Boehringer Ingelheim, Bayer Healthcare, Pfizer, Bristol-Myers Squibb, Astellas Pharma, AstraZeneca, Daiichi Sankyo, Novartis Pharma, MSD, Sanofi-Aventis, Takeda Pharmaceutical, and the Practical Research Project for Life-Style related Diseases including Cardiovascular Diseases and Diabetes Mellitus from Japan Agency for Medical Research and Development.

Predictors and risk model for heart failure hospitalization in atrial fibrillation patients without pre-existing heart failure: the Fushimi AF Registry

Background

Atrial fibrillation (AF) increases the risk of hospitalization for heart failure (HF), as well as that of thromboembolism. The strategy for prediction of thromboembolism has been well-established; however, little focus has been placed on the risk stratification for and prevention of HF hospitalization in AF patients.

Purpose

The aim of this study is to investigate the predictors and risk model of HF hospitalization in non-valvular AF patients without pre-existing HF.

Methods

The Fushimi AF Registry is a community-based prospective survey of AF patients in Fushimi-ku, Kyoto, Japan. The inclusion criterion of the registry is the documentation of AF at 12-lead electrocardiogram or Holter monitoring at any time, and there are no exclusion criteria. We started to enroll patients from March 2011, and follow-up data were available for 4,472 patients by the end of October 2020. From the registry, we excluded patients without a pre-existing HF (defined as having one of the following; prior hospitalization for HF, New York Heart Association class ≥2, or left ventricular ejection fraction [LVEF] <40%), and those with valvular AF (mitral stenosis or prosthetic heart valve). Among 3,188 non-valvular AF patients without pre-existing HF, we explored the risk factors for the HF hospitalization during follow-up period. The risk model for predicting HF hospitalization was determined by the cumulative numbers of risk factors which were significant on multivariate analysis.

Results

The mean age was 72.4±10.8 years, 1197 were female and 1787 were paroxysmal AF. The mean CHADS2 and CHA2DS2-VASc scores were 1.7±1.2 and 2.9±1.6, respectively. During the median follow-up period of 5.1 years, HF hospitalization occurred in 285 (8.9%), corresponding to an annual incidence of 1.8 events per 100 person-years. In multivariable Cox regression analysis, advanced age (≥75 years), valvular heart disease, coronary artery disease, reduced LVEF (<60%), chronic obstructive pulmonary disease (COPD) and anemia were independently associated with the higher incidence of HF hospitalization (all P<0.001) (Picture 1). A risk model based on these 6 variables could stratify the incidence of HF hospitalization during follow-up period (log-rank; P<0.001) (Picture 2). Patients with ≥3 risk factors had an 11-fold higher incidence of HF hospitalization compared with those not having any of these risk factors (hazard ratio: 11.3, 95% confidence interval: 7.0–18.4; P<0.001).

Conclusions

Advanced age, coronary artery disease, valvular heart disease, reduced LVEF, COPD and anemia were independently associated with the risk of HF hospitalization in AF patients without pre-existing HF. There was good prediction for endpoint of HF hospitalization using these 6 variables, providing the opportunities for the implementation of strategies to reduce the incidence of HF among AF patients.

Funding Acknowledgement

Type of funding sources: None.

Rapid magnetic particles-based enzyme immunoassay for the quality control of Glycyrrhiza spp. based on glycyrrhizin content

Glycyrrhizin (GC) is a triterpenoid saponin isolated from the roots of Glycyrrhiza spp., a medicinal plant that is present in 70% of Kampo prescriptions. Since the GC content in Glycyrrhiza spp. affects its various pharmacological activities, Glycyrrhiza spp. is prescribed to contain at least 2% of GC in the Japanese pharmacopoeia, and its quality control based on GC content is required. In this study, a magnetic particles-based enzyme immunoassay (MPs-EIA) was developed using specific monoclonal antibody against GC (MAb 2H2) for the detection of GC in Glycyrrhiza spp. In this system, the immunoreaction time using primary and secondary antibodies was reduced by taking advantage of the wide surface area of magnetic particles (MPs) conjugated with GC by N,N'‑carbonyldiimidazole (CDI)-mediated method. Optimization of MPs-EIA revealed that total assay time (~2 h) was reduced to over half of that of conventional indirect competitive enzyme-linked immunosorbent assay (ELISA) (~5 h). In addition, the GC concentration was detectable within the range from 97.7 to 781 ng/mL, with a limit of detection of 71.4 ng/mL. A series of further validation analyses support the reliability and accuracy of the developed MPs-EIA for the detection of GC in Glycyrrhiza spp. Since the present MPs-EIA overcomes the disadvantage of ELISA in terms of rapidity, it provides a useful approach for the effective quality control of Glycyrrhiza spp., especially when handling multiple samples.

Outcome of maintenance systemic chemotherapy with drug-free interval for metastatic urothelial carcinoma

OBJECTIVE

Aiming to achieve long-term disease control, maintenance systemic chemotherapy (MSC) with a 1-3-month drug-free interval is continued in selected patients. We report our experience of MSC for metastatic urothelial carcinoma (UC).

METHODS

Of 228 metastatic UC patients treated with systemic chemotherapy, 40 (17.5%, 40/228) had continuously undergone MSC. Data on the regimen, cycle number, and reason for the discontinuation of MSC were also collected. We analyzed OS from the initiation of MSC until death or the last follow-up, using the log-rank test to assess the significance of differences.

RESULTS

The median number of cycles of chemotherapy was 6, and the responses were CR in 6, PR in 20, SD in 13, and PD in 1 before MSC. Gemcitabine plus CDDP or carboplatin was mainly performed as MSC (70%, 28/40). MSC was repeated quarterly in 30 (75%, 30/40), every two months in 8 (20%, 8/40), and with other intervals in 2 (5%, 2/40). Overall, a median of 3.5 cycles (range: 1-29) of MSC was performed. The reason for the discontinuation of MSC was PD in 24 (60%, 24/40), favorable disease control in 9 (22.5%, 9/40), and myelosuppression in 3 (7.5%, 3/40), and for other reasons in 2 (5%, 2/40). MSC was ongoing in 2 (5%, 2/40). The median OS was 27 months from the initiation of MSC. PS0 (P = 0.0169), the absence of lung metastasis (P = 0.0387), and resection of the primary site (P = 0.0495) were associated with long-term survival after MSC.

CONCLUSIONS

In selected patients, long-term systemic chemotherapy could be performed with a drug-free interval. Our maintenance strategy with cytotoxic drugs may become one of the treatment options for long-term disease control.

Mechanical Circulatory Support after Orthotopic Heart Transplantation

Frequently the only therapy for primary graft- and right heart failure, as well as low output syndrome from acute of chronic rejection, is implantation of a mechanical circulatory support system, until recompensation or retransplantation. At our institution, mechanical assist devices were implanted in 25 heart recipients for a cute rejection (n=9), primary graft failure (n=7), acute right heart failure (n=7), and chronic rejection with low output syndrome (n=2).

Patients (pts) with primary graft failure (n=3) received an intraaortic balloon pump (IABP), one pt an IABP plus Abiomed®-System for left ventricular support, one pt the Thoratec®-System for biventricular support. Patients with right heart failure (RHF) received the Biomedicus® centrifugal pump for right ventricular support. Nine pts suffered from acute rejection. Six pts received an IABP, one the Biomedicus® as femoro-femoral bypass, one the Abiomed®-System for biventricular support, two the Thoratec®-System for biventricular support and two within this group switched from the Biomedicus® pump to the Thoratec®-System for biventricular support. Patients with chronic graft failure (n=2) received the Novacor®-System (LVAD) for left ventricular support, one received a Tojobo®-System and an oxygenator for biventricular support post coronary artery bypass surgery.

Support time ranged from 0.5-h to 73 days. Five pts were weaned. Two (8%) of 25 pts were retransplanted, 18 (72%) died in spite of mechanical support from multiple organ failure. The use of a mechanical assist device after heart transplantation is encouraging only in the case of early right heart failure, as well as primary and chronic graft failure. In view of the poor results, the use of mechanical assist devices should not be recommended in the case of heart failure caused by acute rejection.

Development and Initial in Vivo Testing of a New Hydraulic Drive System (Paedipump) for Circulatory Support in Infants

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole.

This new system was tested in experimental animals (6 pigs, body weight 9.5–14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body 0 2 consumption were in the normal range during circulatory support indicating adequate organ perfusion.

Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

Improvement of Survival Rate in Patients with Cardiogenic Shock by Using Nonpulsatile and Pulsatile Ventricular Assist Device

Between January 1988 and January 1992, 65 patients (pts) had a ventricle assist device (VAD) inserted in our clinic. In 24 pts a VAD was applied because of primarily unsuccessful weaning from cardiopulmonary bypass (Group A). In a further 24 pts (Group B) a VAD was installed for the therapy of refractive cardiogenic shock (CS) after initially successful cardiac surgery (n=21) and after acute myocardial infarction (n=3). Twelve pts were bridged to heart transplantation (Group C) and five had a VAD inserted for various other reasons (Group D). In 36 (55.4%) of the total 65 pts a nonpulsatile VAD (Biomedicus® 540) was used: 10 in Group A; 20 in B, 3 in C and 3 in D. In 29 pts (44.6%) a pulsatile VAD (Abiomed® BVS 5000) was used: 14 in Group A, 4 in B, 9 in C and 2 in D. Weaning rate and long-term survival rates were 50% and 46% respectively in Group A and 38% and 42% in Group B. Seven pts from Group C were transplanted and six are long-term survivors. Two pts (40%) in Group D were discharged from hospital. Major postoperative complications were bleeding (46%), thromboembolism (14%), multiple organ failure (11%), renal failure (11%), arterial embolism (4.6%), sepsis (3%). The results indicate that application of a VAD can be recommended in pts with postcardiotomy CS to allow recovery of cardiac function and in pts with irreversible ventricular damage as bridging to HTX.

Mechanical ventricular support using pulsatile Abiomed BVS 5000 and centrifugal Biomedicus-pump in postcardiotomy shock

Since we started using ventricular assist devices (VAD) in July 1987 up to August 1993, 63 of 15,650 (0.4%) patients (pts) who underwent open heart sugery were supported postoperatively by VAD at out institution. Forty-three were male and 20 female, mean age 55.5 years. In 49 pts coronary artery bypass grafting (CABG), in 8 pts valve surgery, in 3 pts combined CABG and valve surgery and in 3 pts corrective procedures for congenital heart disease were performed. Perioperative myocardial infarction was the most frequent indication (73%). In 37 of the 63 pts (58.7%) a centrifugal (Biomedicus pump (group A) was used and in 26 pts (41.3%) a pulsatile Abiomed BVS 5000 (group B). Fourteen of 37 pts (38%) in group A were weaned from the VAD and all of them were discharged. Twenty-three pts were unable to be weaned and 19 of these pts died. The remaining 4 pts were transplanted successfully and subsequently 3 died and 1 was discharged. In all, 15 pts (39%) were long-term survivors. Sixteen of 26 pts (62%) in group B were weaned from VAD and 13 (50%) of them were discharged of whom 3 died. Ten patients were unable to be weaned and 7 of these died. The remaining 3 pts were transplanted successfully. In all, 16 pts (61.5%) were long-term survivors. The shorter the interval between beginning resuscitation and application of VAD the better the outcome. Younger age, VAD installation in OR, support time between 2 and 7 days and Abiomed pump, influence the survival rate positively. Because of higher recovery and survival rates in patients assisted by Abiomed compared to the Biomedicus pump, we recommend the Abiomed pump in postcardiotomy cardiac failure.

Correction to: Development of micro mechanical device having two-dimensional array of micro chambers for cell stretching

The original article has been corrected. Instances of the character "μ" should be replaced by the term "micro".

Development of micro mechanical device having two-dimensional array of micro chambers for cell stretching

This paper presents a novel cell stretching micro device having two-dimensional array of micro chambers. It enables an in situ time-lapse observation of stretched cell by using an optical microscope with high measurement efficiency. The presented device consists of a cell culture dish and the array of micro chambers made of silicone elastomer and extension structures made of photocurable resin, and is fabricated with MEMS technology. The fabrication process of the thin micro chamber array combines photoresist mold and lift-off process based on conventional photolithography. The fabricated device has 134micro chambers in 5μm or less thickness. It was demonstrated that the fabricated micro device could be used to make in-situ time-lapse observation of cell responses to stretching under optical microscopy. In addition, the influence of the chamber thickness to the quality of the microscope image observed was evaluated. It is confirmed that the proposed device having two-dimensional array of the thin micro chambers makes it possible to observe cell response for stretch stimuli with high quality and efficiency.

Survey of patient exposure from general radiography and mammography in Japan in 2014

With the objective of reducing patient exposure to radiation, we conducted a questionnaire survey regarding radiographic conditions in 2014. Here we report estimates of dose exposure in general radiography and mammography through an investigation and comparison of present patient exposure conditions. Questionnaires were sent to 3000 facilities nationwide in Japan. Surveys asked questions on a total of 16 items related to general radiography, including the chest, abdomen, and breast. Output data from x-ray tubes measured in the Chubu area of Japan were used as the mean in these estimates. The index of patient exposure was adopted as the entrance skin dose (ESD) for general radiography and as the mean glandular dose (MGD) for mammography. The response rate for this survey was 21.9%. Our results showed that doses received through the use of flat-panel detector (FPD) devices were lower than those received through computed radiography devices, except for the ankle joint (e.g. in chest examination, the dose from FPD and CR was 0.24 mGy, 0.31 mGy on the average, respectively). These results suggest that more widespread use of FPD devices could lead to decreases in the ESD and MGD, thereby reducing patient exposure.

Survey of volume CT dose index in Japan in 2014

OBJECTIVE

The aims of this study are to propose a new set of Japanese diagnostic reference levels (DRLs) for 2014 and to study the impact of tube voltage and the type of reconstruction algorithm on patient doses. The volume CT dose index (CTDI(vol)) for adult and paediatric patients is assessed and compared with the results of a 2011 national survey and data from other countries.

METHODS

Scanning procedures for the head (non-helical and helical), chest and upper abdomen were examined for adults and 5-year-old children. A questionnaire concerning the following items was sent to 3000 facilities: tube voltage, use of reconstruction algorithms and displayed CTDI(vol).

RESULTS

The mean CTDI(vol) values for paediatric examinations using voltages ranging from 80 to 100 kV were significantly lower than those for paediatric examinations using 120 kV. For adult examinations, the use of iterative reconstruction algorithms significantly reduced the mean CTDI(vol) values compared with the use of filtered back projection. Paediatric chest and abdominal scans showed slightly higher mean CTDI(vol) values in 2014 than in 2011. The proposed DRLs for adult head and abdominal scans were higher than those reported in other countries.

CONCLUSION

The results imply that further optimization of CT examination protocols is required for adult head and abdominal scans as well as paediatric chest and abdominal scans.

ADVANCES IN KNOWLEDGE

Low-tube-voltage CT may be useful for reducing radiation doses in paediatric patients. The mean CTDI(vol) values for paediatric scans showed little difference that could be attributed to the choice of reconstruction algorithm.

Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation

Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film was controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique.

Results of a 2011 national questionnaire for investigation of mean glandular dose from mammography in Japan

Diagnostic reference levels (DRLs) for mammography have yet to be created in Japan. A national questionnaire investigation into radiographic conditions in Japan was carried out for the purpose of creating DRLs. Items investigated included the following: tube voltage; tube current; current-time product; source-image distance; craniocaudal view; automatic exposure control (AEC) settings; name of mammography unit; image receptor system (computed radiography (CR), flat panel detector (FPD), or film/screen (F/S)); and supported or unsupported monitor diagnosis (including monitor resolution). Estimation of the mean glandular dose (MGD) for mammography was performed and compared with previous investigations. The MGD was 1.58(0.48) mGy, which did not significantly differ from a 2007 investigation. In relation to image receptors, although no difference in average MGD values was observed between CR and FPD systems, F/S systems had a significantly decreased value compared to both CR and FPDs. Concerning digital systems (FPDs), the MGD value of the direct conversion system was significantly higher than the indirect conversion system. No significant difference in MGD value was evident concerning type of monitor diagnosis for either the CR or the FPD digital systems; however, hard copies were used more often in CR. No significant difference in the MGD value was found in relation to monitor resolution. This report suggests ways to lower the doses patients undergoing mammography receive in Japan, and serves as reference data for 4.2 cm compressed breast tissue of 50% composition DRLs. Furthermore, our findings suggest that further optimisation of FPD settings can promote a reduction in the MGD value.

Comparison of sensitivity of lung nodule detection between radiologists and technologists on low-dose CT lung cancer screening images

OBJECTIVES

The objective of this study was to compare the sensitivity of detection of lung nodules on low-dose screening CT images between radiologists and technologists.

METHODS

11 radiologists and 10 technologists read the low-dose screening CT images of 78 subjects. On images with a slice thickness of 5 mm, there were 60 lung nodules that were ≥5 mm in diameter: 26 nodules with pure ground-glass opacity (GGO), 7 nodules with mixed ground-glass opacity (GGO with a solid component) and 27 solid nodules. On images with a slice thickness of 2 mm, 69 lung nodules were ≥5 mm in diameter: 35 pure GGOs, 7 mixed GGOs and 27 solid nodules. The 21 observers read screening CT images of 5-mm slice thickness at first; then, 6 months later, they read screening CT images of 2-mm slice thickness from the 78 subjects.

RESULTS

The differences in the mean sensitivities of detection of the pure GGOs, mixed GGOs and solid nodules between radiologists and technologists were not statistically significant, except for the case of solid nodules; the p-values of the differences for pure GGOs, mixed GGOs and solid nodules on the CT images with 5-mm slice thickness were 0.095, 0.461 and 0.005, respectively, and the corresponding p-values on CT images of 2-mm slice thickness were 0.971, 0.722 and 0.0037, respectively.

CONCLUSION

Well-trained technologists may contribute to the detection of pure and mixed GGOs ≥5 mm in diameter on low-dose screening CT images.

Development of a micro cell compression stimulator for evaluating real-time cellular responses

This paper presents a micro cell compression stimulator for evaluating real-time cellular responses to compression stimuli. The device was produced by a micro three-dimensional structure fabrication process using multiple exposures to the photoresist. The device consists of a pressure inlet port, cell inlet ports, a gasket, microchannels, cell culture chambers, and a diaphragm on the culture chamber for applying compressive pressure to cells. Compression stimuli applied to the cells can be controlled by regulating the expansion of the diaphragm via a pressure control. The device permits the observation of cellular responses to compressive pressure in real time because it is made of transparent materials and stimulates the cells without deforming the cell culture surface, when observed by optical microscopy. We demonstrated the validity of the fabrication process, evaluated the performance of the fabricated device, and compared the experimental results with the FEM structural analysis results. We found through operational testing that the diaphragm was deformed quickly by applying negative/positive pressure and that the diaphragm displacement became larger with increasing applied pressure. These results indicate that this device can be used to control the intensity and the cell stimulus profile by regulating the applied pressure. In all cases, the cellular deformation during compression stimulus was successfully observed in real time using an optical microscope. The device is expected to facilitate the control of stem cell differentiation and the clarification of cellular mechanoreceptor mechanisms and signal transduction pathways.

Calculation of personal dose equivalent for positron-emitting radionuclides using Monte Carlo code EGS5

The conversion coefficients, H'(d,α)/Φ, for monoenergetic positrons and positron-emitting radionuclides were calculated by using the user code UCICRPM of the Monte Carlo code EGS5 to estimate the radiation dose for medical staff involved in positron emission tomography examinations. From these coefficients, the dose equivalent rates per unit activity at 0.07 and 10 mm depths in a soft tissue for a straight-line source of 2-deoxy-2-[(18)F]fluoro-d-glucose ((18)F-FDG) were calculated by using the developed user code UCF18DOSE. The dose equivalent rates per unit activity at 0.07 and 10 mm depths were measured by using a personal dosemeter (DOSE(3)) under the same conditions as those considered in the calculation. The calculated dose equivalent rates per unit activity at 0.07 and 10 mm depths were 0.116 and 0.0352 pSv min(-1) Bq(-1), respectively, at 20 cm from the (18)F-FDG injection tube.

Role of lymph node dissection in the treatment of urothelial carcinoma of the upper urinary tract: multi-institutional relapse analysis and immunohistochemical re-evaluation of negative lymph nodes

AIM

To determine the role of lymph node dissection (LND) in the treatment of urothelial carcinoma (UC) of the upper urinary tract (UUT).

PATIENTS AND METHODS

[Study-1] A retrospective multi-institutional study evaluated 293 patients undergoing predominantly nephroureterectomy for UC of the UUT. Of 293 patients, 267 patients had pure UC and 26 demonstrated other histological components. Regarding the pathological node status, 130 patients had pN0 disease, 141 patients had pNx disease and 22 patients had pN+ disease. The sites of initial recurrence and time to first recurrence were reviewed. The sites of recurrence were classified as locoregional or distant recurrence. The relationship between node status and future recurrence was analyzed. [Study-2] Fifty-one patients treated by nephroureterectomy at Hokkaido University Hospital were included. All had LND and all LNs were negative on hematoxylin and eosin staining. We re-evaluated the presence of micrometastasis in LND specimens by anti-cytokeratin immunohistochemistory.

RESULTS

[Study-1] Of 293 patients, 76 developed disease relapse. Regional lymph node recurrence was the most common site (34 patients). On multivariate analyses that adjusted for the effect of tumor stage and tumor grade, pNx (skipping LND) was an adverse factor not only for locoregional recurrence, but also for distant relapse. [Study-2] Immunohistochemistry identified micrometastases in 7 (14%) of 51 patients. Regarding survival, 5 of these 7 patients with micrometastases were alive at last follow-up.

CONCLUSIONS

On relapse analysis, skipping LND was an adverse factor not only for locoregional recurrence, but also for distant relapse. Immunohistochemistry detected micrometastases in about 14% of patients previously diagnosed as pN0. These findings further support a potential therapeutic benefit of LND by eliminating micrometastases.