Is the use of gonad protection protectors necessary during infants chest radiography?

INTRODUCTION AND OBJECTIVES

To compare gonad doses with and without a gonad protector and to optimize the use of gonadal protectors in infants thorax radiography.

MATERIALS AND METHODS

Two pediatric anthropomorphic phantoms are used: an X-ray system for KXO-50SS/DRX-3724HD, and a digital radiography system for CALNEO Smart C12, with and without a gonad protector during infants thorax radiography. A real time skin dosimeter is placed on the X-ray system, and a real time skin dosimeter is inserted on the front side of the mammary gland, the front and back sides of the true pelvis level, and on the ovaries and testes. The X-ray system is irradiated 15 times using phantoms with and without a gonad protector. The measured entrance patient doses values of for the real time skin dosimeter are compared for each phantom, with and without the gonad protector.

RESULTS

The medium of measured entrance patient doses values for front side dose of the true pelvis level with and without the protector are 10.00 and 5.00 μGy at newborn, and 10.00 and 0.00μGy at one year, respectively. The medium of measured entrance patient doses values for the back side dose of the true pelvis level with and without the protector are 0.00 and 0.00 μGy at both newborn one year, respectively. The measured entrance patient doses cannot be detected in the ovaries and testes with or without the protector. No significant differences are observed in the measured entrance patient doses values for the front and back side doses of the pelvis, ovaries, and testes at newborn and one year, with and without the protector (p>0.05).

CONCLUSIONS

No significant difference was observed in gonad dose measurements with and without the gonad protector during infants chest radiography. We believe that gonadal protector wearing is not necessary.

Influence of splenomegaly on aortic and liver parenchymal CT numbers during contrast-enhance CT in patients with cirrhosis

INTRODUCTION

To compare CT (computed tomography) values for enhancement of the abdominal aorta and liver parenchyma during dynamic contrast enhancement (CE) CT in cirrhotic patients with and without splenomegaly (SM).

METHODS

We considered 258 patients (83 males and 46 females for the splenomegaly group, and 83 males and 46 females for the control group) for this retrospective study. We measured CT values in the abdominal aorta and hepatic parenchyma during the hepatic arterial (HAP) and portal venous (PVP) phases. The aortic CE at HAP and the hepatic parenchymal CE at PVP were compared between the two groups. For success rate of scans, we also calculated the optimal CE rates (>280 HU in the abdominal aorta and >50 HU in the hepatic parenchyma) for each group.

RESULTS

In the SM group, the CE for abdominal aorta was decreased during the aortic phase for a dynamic CE-CT (p < 0.05). When evaluating the success rates, they were found to be 65.1 % and 58.9 % in the SM group and 81.4 % and 72.3 % in the non-SM group (p < 0.05).

CONCLUSION

The success rate of scans and CE for the abdominal aorta during the aortic phase exhibited a significant decrease during dynamic CE-CT scans on patients with SM. Patients with SM may have reduced diagnostic ability with typical contrast injection protocols.

IMPLICATIONS FOR PRACTICE

It may be necessary to change the injection rates and contrast medium volume during CE-CT depending on the presence or absence of SM.

Iodine contrast volume reduction in preoperative transcatheter aortic valve implantation computed tomography: Comparison with 64- and 256-multidetector row computed tomography

INTRODUCTION

This study aimed to compare the vascular enhancement and radiation dose in preoperative transcatheter aortic valve implantation (TAVI) computed tomography (CT) with a reduced contrast medium (CM) using volume scans in 256-multidetector row CT (MDCT) with a standard CM using 64-MDCT.

METHODS

This study included 78 patients with preoperative TAVI CT with either 64- or 256-MDCT. The CM was injected at 1.5 mL/kg in the 64-MDCT group and 1.0 mL/kg in the 256-MDCT group. We compared vascular enhancement of the aortic root and access routes, image quality (IQ) scores, and radiation dose in both groups.

RESULTS

Despite the reduced CM (by 33 %) in the 256-MDCT group, the mean vascular enhancement of the right and left subclavian arteries was significantly higher than that in the 64-MDCT group [284 and 267 Hounsfield units (HU) vs. 376 and 359 HU; p < 0.05]; however, no significant differences in the mean vascular enhancement in the ascending aorta, abdominal aorta at the celiac level, and bilateral common femoral arteries were observed between the two groups (p > 0.05 for all). The median IQ scores at the aortic root were higher in the 256-MDCT group than in the 64-MDCT group (3 vs. 4; p < 0.05), and those at the femoral access routes were comparable (4 vs. 4; p = 0.33). The mean effective dose was significantly reduced by 30 % in the 256-MDCT group (23.6 vs. 16.3 mSv; p < 0.05).

CONCLUSION

In preoperative TAVI CT, volume scans using 256-MDCT provide comparable or better vascular enhancement and IQ with a 30 % reduction in CM and radiation dose than those using 64-MDCT.

IMPLICATIONS FOR PRACTICE

Volume scan using 256-MDCT for preoperative TAVI CT may reduce CM and radiation dose in TAVI patients with renal dysfunction.

Telemedicine for Pregnant Women on a Japanese Remote Island: A Two-year Report

Introduction

Remote antenatal checkups were conducted on the northernmost island of Japan to reduce the burden of hospital visits among pregnant women. This study aims to investigate the effectiveness and safety of remote antenatal checkups for pregnant women living on a remote island.

Methods

This observational study included singleton pregnancies on Rebun Island between October 2020 and September 2022. General surgeons conducted medical interviews and performed fetal sonography using an obstetrician videoconference system at the main central hospital. The primary outcomes were the degrees of physical, mental, and economic burdens of hospital visits and the levels of anxiety and satisfaction with remote antenatal checkups as assessed using a questionnaire survey. Moreover, we investigated the incidence of adverse perinatal events, including maternal death, fetal death, neonatal death, severe neonatal neurological disorders, and other obstetric complications.

Results

This study included 16 out of 22 pregnant women from Rebun Island who visited the central hospital. No adverse perinatal events occurred as a result of the remote antenatal checkups. One pregnant woman had gestational diabetes, whereas the others had no obstetric complications. The participants underwent a median of two remote antenatal checkups. According to a questionnaire survey, 90.0%, 80.0%, and 70.0% of the pregnant women perceived improvements in their physical, mental, and economic burdens, respectively. Although 70.0% of the participants experienced anxiety regarding remote antenatal checkups before the introduction, all were satisfied after delivery.

Conclusions

Remote antenatal checkups effectively reduced the burden of hospital visits for pregnant women, who reported high levels of satisfaction. Furthermore, antenatal checkups were safely conducted on remote islands.

Applying patient characteristics, stent-graft selection, and pre-operative computed tomographic angiography data to a machine learning algorithm: Is endoleak prediction possible?

INTRODUCTION

This study aims to predict endoleak after endovascular aneurysm repair (EVAR) using machine learning (ML) integration of patient characteristics, stent-graft configuration, and a selection of vessel lengths, diameters and angles measured using pre-operative computed tomography angiography (CTA).

METHODS

We evaluated 1-year follow-up CT scans (arterial and delayed phases) in patients who underwent EVAR for the presence or absence of an endoleak. We also obtained data on the patient characteristics, stent-graft selection, and preoperative CT vessel morphology (diameter, length, and angle). The extreme gradient boosting (XGBoost) for the ML system was trained on 30 patients with endoleaks and 81 patients without. We evaluated 5217 items in 111 patients with abdominal aortic aneurysms, including the patient characteristics, stent-graft configuration and vascular morphology acquired using pre-EVAR abdominal CTA. We calculated the area under the curve (AUC) of our receiver operating characteristic analysis using the ML method.

RESULTS

The AUC, accuracy, 95% confidence interval (CI), sensitivity, and specificity were 0.88, 0.88, 0.79-0.97, 0.85, and 0.91 for ML applying XGBoost, respectively.

CONCLUSIONS

The diagnostic performance of the ML method was useful when factors such as the patient characteristics, stent-graft configuration and vessel length, diameter and angle of the vessels were considered from pre-EVAR CTA.

IMPLICATIONS FOR PRACTICE

Based on our findings, we suggest that this is a potential application of ML for the interpretation of abdominal CTA scans in patients with abdominal aortic aneurysms scheduled for EVAR.

Radiation dose reduction method combining the ECG-Edit function and high helical pitch in retrospectively-gated CT angiography

INTRODUCTION

The purpose of this study was to demonstrate that dose reduction does not compromise image quality when combining high helical pitch (HP) and the ECG-Edit function during low HP retrospectively gated computed tomography angiography (CTA).

METHODS

This study made use of a pulsating cardiac phantom (ALPHA 1 VTPC). The heart rate (HR) of the cardiac phantom was changed in five intervals, every 5 beats per minute (bpm), from 40 to 60 bpm. Evaluation of a range of HR was important because data loss might occur when combining a low HR and high HP. We performed retrospectively gated CTA scans five times using a low HP (0.16) and high HP (0.24), for each of the five HR intervals, using a 64-detector row CT scanner. The CT volume dose index (CTDI_vol) was recorded from the CT console of each scan. For the images with data loss, data were repaired using the ECG-Edit function. We compared the CTDI_vol, estimated cardiac phantom volume, and the visualization of the coronary ladder phantom between HP 0.16, with or without repaired HP 0.24, using the ECG-Edit function.

RESULTS

Data loss occurred with a HR of 40 bpm and 45 bpm when using HP 0.24. The CTDI_vol was reduced by approximately 33% with HP 0.24 when compared with HP 0.16. There were no significant differences in the mean cardiac motion phantom volume and visualization scores between HP 0.16 and with and without repaired HP 0.24 using the ECG-Edit function (p < 0.05).

CONCLUSION

The ECG-Edit function is potential useful for repairing the lost data in patients with a low HR, and when combined with a high HP, it is possible to reduce the radiation dose by approximately 33%.

IMPLICATIONS FOR PRACTICE

The ECG-Edit function and high HP may be a viable option in pediatric CTA studies.

Effect of injection duration on contrast enhancement during cardiac computed tomography angiography in newborns and infants

INTRODUCTION

To investigate how changing the injection duration at cardiac computed tomography angiography (CCTA) affects contrast enhancement in newborns and infants.

METHODS

Included were 142 newborns and infants with confirmed congenital heart disease who underwent CCTA between January 2015 and December 2018. In group 1 (n = 71 patients), the injection duration was 8 s; in group 2 (n = 71) it was 16 s. Our findings were assessed by one-to-one matching analysis to estimate the propensity score of each patient. We compare the CT number for the pulmonary artery (PA), ascending aorta (AAO), left superior vena cava (SVC), AAO and PA enhancement ratio, and the scores for visualization between the two groups.

RESULTS

In group 1, median CT number and ranges was 345 (211-591) HU in the AAO, 324 (213-567) HU in the PA, and 62 (1-70) HU in the SVC. These values were 465 (308-669) HU, 467 (295-638) HU, and 234 (67-443) HU, respectively, in group 2 (p < 0.05). The median score for volume-rendering visualization on 3D images of the CCTA was 2 in group 1 and 3 in group 2; the score for visualization of the left SVC of the maximum intensity projection images was 2 in group 1 and 3 in group 2 (p < 0.05). The CT number for the AAO and PA enhancement ratio was 15.2 in group 1 and 9.2 in group 2 (p < 0.05).

CONCLUSION

The 16-sec injection protocol yielded significantly higher CT numbers for the AAO, PA, and the SVC than the 8-sec injection protocol; the visualization scores were also significantly higher in group 2.

IMPLICATIONS FOR PRACTICE

In newborns and infants, the longer injection time for CCTA yields stable and higher contrast enhancement at identical CM concentrations.

Virtual magnetic resonance lumbar spine images generated from computed tomography images using conditional generative adversarial networks

INTRODUCTION

The aim of this study was to generate virtual Magnetic resonance (MR) from computed tomography (CT) using conditional generative adversarial networks (cGAN).

METHODS

We selected examinations from 22 adults who obtained their CT and MR lumbar spine examinations. Overall, 4 examinations were used as test data, and 18 examinations were used as training data. A cGAN was trained to generate virtual MR images from the CT images using the corresponding MR images as targets. After training, the generated virtual MR images from test data in epochs 1, 10, 50, 100, 500, and 1000 were compared with the original ones using the mean square error (MSE) and structural similarity index (SSIM). Additionally, two radiologists also performed qualitative assessments.

RESULTS

The MSE of the virtual MR images decreased as the epoch of the cGANs increased from the original CT images: 8876.7 ± 1192.9 (original CT), 1567.5 ± 433.9 (Epoch 1), 1242.4 ± 442.0 (Epoch 10), 1065.8 ± 478.1 (Epoch 50), 1276.1 ± 718.9 (Epoch 100), 1046.7 ± 488.2 (Epoch 500), and 1031.7 ± 400.0 (Epoch 1000). No considerable differences were observed in the qualitative evaluation between the virtual MR images and the original ones, except in the structure of the spinal canal.

CONCLUSION

Virtual MR lumbar spine images using cGANs could be a feasible technique to generate near-MR images from CT without MR examinations for evaluation of the vertebral body and intervertebral disc.

IMPLICATIONS FOR PRACTICE

Virtual MR lumbar spine images using cGANs can offer virtual CT images with sufficient quality for attenuation correction for PET or dose planning in radiotherapy.

Enhancement rate of venous phase to portal venous phase computed tomography and its correlation with ultrasound elastography determination of liver fibrosis

INTRODUCTION

This study aimed to compare the correlation between the computed tomography (CT) enhancement rate of the venous to portal venous phase (VP-ER) and the extracellular volume (ECV) fraction with shear-wave ultrasound elastography (USE) findings in patients with liver fibrosis.

METHODS

We included 450 patients with clinically suspected liver cirrhosis who underwent triphasic dynamic CT studies and USE. We compared the USE results with the unenhanced CT phase, with enhancement in the hepatic artery phase (HAP), portal venous phase (PVP), and venous phase (VP), and with the ECV fraction and the VP-ER. We also compared the area under the curve (AUC) of the receiver operating characteristic (ROC) curve of the ECV fraction and VP-ER with that of the values obtained with USE.

RESULTS

The VP-ER was the most highly correlated with the liver stiffness value determined with USE (Pearson's correlation coefficient: r = 0.37), followed by enhancement in the PVP (r = -0.25), CT number on unenhanced CT scans (r = -0.22), the ECV fraction (r = 0.19), enhancement in the VP (r = 0.059), and enhancement in the HAP (r = -0.023) (all p < 0.01). The VP-ER showed a significantly higher AUC than the ECV fraction (0.75 vs 0.62) when the liver stiffness was >15 kPa in USE studies (p = 0.04).

CONCLUSION

Compared to the ECV fraction, the VP-ER is more useful for predicting all degrees of liver fibrosis on routine triphasic dynamic CT images.

IMPLICATIONS FOR PRACTICE

Although improvement is needed, the VP-ER has a higher diagnostic ability for liver fibrosis than the ECV fraction in clinical practice.

Efficacy of the spiral flow generating extended tube during paediatric CCTA

INTRODUCTION

To compare the computed tomography (CT) number for paediatric cardiac computed tomography angiography (CCTA) and visualisation score of the three-dimensional (3D) images using the conventional T-shaped extended tube (T-tube) and spiral flow-generating extended tube (spiral-tube) connected between the contrast injector and cannula.

METHODS

In total, 108 patients suspected to have congenital heart disease (CHD) were considered for inclusion. We utilised the T-tube for intravenous contrast and spiral-tube in 54 patients each. Observers individually inspected randomized volume rendering images of the internal thoracic artery, each acquired from the with or without spiral-tube groups, using a four-point scale. We compared the mean CT number of the ascending aorta (AAO) and pulmonary artery (PA), contrast noise ratio (CNR), CT number for the AAO and PA enhancement ratio, and the visualisation scores between the groups.

RESULTS

There were no significant differences in patient characteristics between the with or without spiral-tube groups (p > 0.05). The mean CT number ±standard deviation for the AAO and PA, and the CNR without or with spiral-tube groups were 441.2 ± 89.2 and 489.8 ± 86.1 HU for the AAO, 436.3 ± 100.6 and 475.3 ± 85.2 HU for the PA, and 9.5 ± 2.2 and 10.8 ± 2.4 for the CNR, respectively (p < 0.05). In the spiral-tube group, the CT number, CNR, and visualisations score of the 3D images were significantly higher for the AAO and PA than those in the T-tube group (p < 0.05).

CONCLUSION

The spiral-tube proved to be beneficial in improving the CT number for the AAO and PA, CNR, and visualisation score compared with the conventional T-tube during paediatric CCTA.

IMPLICATIONS FOR PRACTICE

The spiral-tube may allow the visualisation of smaller blood vessels than those visualised by the conventional T-tube for paediatric patients in CCTA.

Clinical usefulness of a novel fluorescence technique for the intraoperative diagnosis of surgical margins in patients with breast cancer

In both 5- and 15-min data, FI was significantly higher in malignant tissues than in benign tissues. The diagnostic accuracy was similar at 5 and 15 min. Therefore, the 5-min FI was enough applying in the further analyses.

Deep learning with convolutional neural network for estimation of the characterisation of coronary plaques: Validation using IB-IVUS

INTRODUCTION

Deep learning approaches have shown high diagnostic performance in image classifications, such as differentiation of malignant tumors and calcified coronary plaque. However, it is unknown whether deep learning is useful for characterizing coronary plaques without the presence of calcification using coronary computed tomography angiography (CCTA). The purpose of this study was to compare the diagnostic performance of deep learning with a convolutional neural network (CNN) with that of radiologists in the estimation of coronary plaques.

METHODS

We retrospectively enrolled 178 patients (191 coronary plaques) who had undergone CCTA and integrated backscatter intravascular ultrasonography (IB-IVUS) studies. IB-IVUS diagnosed 81 fibrous and 110 fatty or fibro-fatty plaques. We manually captured vascular short-axis images of the coronary plaques as Portable Network Graphics (PNG) images (150 × 150 pixels). The display window level and width were 100 and 700 Hounsfield units (HU), respectively. The deep-learning system (CNN; GoogleNet Inception v3) was trained on 153 plaques; its performance was tested on 38 plaques. The area under the curve (AUC) obtained by receiver operating characteristic analysis of the deep learning system and by two board-certified radiologists was compared.

RESULTS

With the CNN, the AUC and the 95% confidence interval were 0.83 and 0.69-0.96, respectively; for radiologist 1 they were 0.61 and 0.42-0.80; for radiologist 2 they were 0.68 and 0.51-0.86, respectively. The AUC for CNN was significantly higher than for radiologists 1 (p = 0.04); for radiologist 2 it was not significantly different (p = 0.22).

CONCLUSION

DL-CNN performed comparably to radiologists for discrimination between fatty and fibro-fatty plaque on CCTA images.

IMPLICATIONS FOR PRACTICE

The diagnostic performance of the CNN and of two radiologists in the assessment of 191 ROIs on CT images of coronary plaques whose type corresponded with their IB-IVUS characterization was comparable.

Diagnostic performance of computed tomography digital subtraction angiography of the lower extremities during haemodialysis in patients with suspected peripheral artery disease

INTRODUCTION

With intra-arterial digital subtraction angiography (DSA) considered as the gold standard, we compared the diagnostic value of computed tomography angiography (CTA) and computed tomography-digital subtraction angiography (CT-DSA in hemodialysis (HD) patients suspected of having lower limb peripheral artery disease (PAD).

METHODS

In this retrospective study, we enrolled 220 HD patients with suspected PAD. CT-DSA images were obtained by subtracting unenhanced images from enhanced images. The research team calculated the area under the curve (AUC), sensitivity, specificity, positive and negative predictive value (PPV, NPV), and recorded the diagnostic accuracy between the CTA and CT-DSA images using the DSA as gold standard. Visual evaluation of calcifications in the peripheral arteries were also compared between CTA and CT-DSA images.

RESULTS

At the above-knee level, the CTA AUC [95% confidence interval (CI)] was 0.68 (CI 0.64-0.72), sensitivity and specificity were 60 and 81%, PPV and NPV were 85 and 53%, and accuracy was 67%. Below the knee, these values were 0.66 (CI 0.62-0.70), 71 and 79%, 79 and 47%, and 66%. For CT-DSA, above-knee, the AUC [95% CI] was 0.88 (CI 0.85-0.91), sensitivity and specificity were 84 and 92%, PPV and NPV were 89 and 97%, and accuracy was 93%. Below the knee, these values were 0.95 (CI 0.93-0.97), 95 and 93%, 96 and 83%, and 93%. The scores for the visualization of calcification in the peripheral arteries was significantly higher for CT-DSA than CTA (p < 0.05).

CONCLUSIONS

CT-DSA helps to assess stenotic PAD with high calcification in the lower extremities of HD patients.

IMPLICATIONS FOR PRACTICE

On CT-DSA images, the severity of vascular calcification can be assessed for HD patients suspected of PAD of the lower extremities.

Study of the K_{L}→π^{0}νν[over ¯] Decay at the J-PARC KOTO Experiment

The rare decay K_{L}→π^{0}νν[over ¯] was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of (7.20±0.05_{stat}±0.66_{syst})×10^{-10}, three candidate events were observed in the signal region. After unveiling them, contaminations from K^{±} and scattered K_{L} decays were studied, and the total number of background events was estimated to be 1.22±0.26. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of 4.9×10^{-9} on the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level.

Machine learning to identify lymph node metastasis from thyroid cancer in patients undergoing contrast-enhanced CT studies

INTRODUCTION

We compared the diagnostic performance of morphological methods such as the major axis, the minor axis, the volume and sphericity and of machine learning with texture analysis in the identification of lymph node metastasis in patients with thyroid cancer who had undergone contrast-enhanced CT studies.

METHODS

We sampled 772 lymph nodes with histology defined tissue types (84 metastatic and 688 benign lymph nodes) that were visualised on CT images of 117 patients. A support vector machine (SVM), free programming software (Python), and the scikit-learn machine learning library were used to discriminate metastatic-from benign lymph nodes. We assessed 96 texture and 4 morphological features (major axis, minor axis, volume, sphericity) that were reported useful for the differentiation between metastatic and benign lymph nodes on CT images. The area under the curve (AUC) obtained by receiver operating characteristic analysis of univariate logistic regression and SVM classifiers were calculated for the training and testing datasets.

RESULTS

The AUC for all classifiers in training and testing datasets was 0.96 and 0.86, at the SVM for machine learning. When we applied conventional methods to the training and testing datasets, the AUCs were 0.63 and 0.48 for the major axis, 0.70 and 0.44 for the minor axis, 0.66 and 0.43 for the volume, and 0.69 and 0.54 for sphericity, respectively. The SVM using texture features yielded significantly higher AUCs than univariate logistic regression models using morphological features (p = 0.001).

CONCLUSION

For the identification of metastatic lymph nodes from thyroid cancer on contrast-enhanced CT images, machine learning combined with texture analysis was superior to conventional diagnostic methods with the morphological parameters.

IMPLICATIONS FOR PRACTICE

Our findings suggest that in patients with thyroid cancer and suspected lymph node metastasis who undergo contrast-enhanced CT studies, machine learning using texture analysis is high diagnostic value for the identification of metastatic lymph nodes.

The combined application of the contrast-to-noise index and 80 kVp for cardiac CTA scanning before atrial fibrillation ablation reduces radiation dose exposure

INTRODUCTION

To compare the radiation dose, diagnostic accuracy, and the resultant ablation procedures using 80 and 120-kVp cardiac computed tomography angiography (CCTA) protocols with the same contrast-to-noise ratio in patients scheduled for atrial fibrillation (AF) ablation.

METHODS

This retrospective study was performed following institutional review board approval. We divided 140 consecutive patients who had undergone CCTA using a 64-MDCT scanner into two equal groups. Standard deviation (SD) of the CT number was set at 25 Hounsfield units (HU) for the 120-kVp protocol. To facilitate a reduction in radiation dose it was set at 40 HU for the 80 kVp protocol. We compared the two protocols with respect to the radiation dose, the diagnostic accuracy for detecting left atrial appendage (LAA) thrombi, matching for surface registration, and the resultant ablation procedures.

RESULTS

At 120 kVp, the dose length product (DLP) was 2.2 times that at 80 kVp (1269.0 vs 559.0 mGy cm, p < 0.01). The diagnostic accuracy for thrombus detection was 100% using both protocols. There was no difference between the two protocols with respect to matching for surface registration. The protocols did not differ with respect to the subsequent time required for the ablation procedures and the ablation fluoroscopy time, and the radiation dose (p = 0.54, 0.33, and 0.32, respectively).

CONCLUSION

For the same CNR, the DLP at 80 kVp (559.0 mGy cm) was 56% of that delivered at 120 kVp (1269.0 mGy cm). There was no reduction in diagnostic accuracy.

IMPLICATIONS FOR PRACTICE

Maintaining CNR allows for a reduction in the radiation dose without reducing the image quality.

P6331Influence of dynapenia and obesity on prognoses of elderly heart failure patients

Background

In elderly people, a decline in activities of daily living is more closely associated with low muscle strength (dynapenia) than with low muscle mass. Moreover, the combination of low muscle strength and obesity (dynapenic obesity) is associated with a higher risk of mortality than dynapenia or obesity alone, but its influence on prognosis is still unknown in elderly heart failure (HF) patients. To clarify these relationships may contribute to the development of rehabilitation programs for elderly HF patients and the improvement their prognoses in the future.

Purpose

We aimed to investigate the influence of dynapenia and obesity on prognoses of elderly HF patients.

Methods

We evaluated 1006 elderly HF patients aged ≥65 years (76.5±6.9 years, 579 males) who were admitted to our hospital and participated in an inpatient cardiac rehabilitation program. We assessed patients' characteristics, including body mass index (BMI) and handgrip strength during hospitalization. Patients with low handgrip strength (<26 kg and <18 kg in males and females, respectively) and high BMI (≥25 kg/m2) were considered to have dynapenia and obesity, respectively. Moreover, patients fulfilling the above two criteria (dynapenia, obesity) were considered to have dynapenic obesity. Patients were divided into four groups: normal, dynapenia only, obesity only, and dynapenic obesity. We compared survival rates among the four groups using the Kaplan-Meier method and log-rank test. To identify predictors for all-cause mortality, we performed Cox regression analysis.

Results

During the 8-year follow-up period, 228 patients (21.2%) died. Eight-year cumulative incidences of mortality were 35.4%, 26.0%, 62.6%, and 33.1% in the normal, obesity only, dynapenia only, and dynapenic obesity groups, respectively. Significantly lower survival rates were observed in the dynapenia only group than in the other 3 groups (log-rank: 28.893, P<0.001). Cox regression analysis, after adjusting for age and sex, showed significantly poor prognosis in the dyanapenia only group than in the other 3 groups (normal group, hazard ratio [HR] = 0.684, 95% confidence interval [CI] = 0.488–0.959, P=0.028; obesity only group, HR = 0.330, 95% CI = 0.182–0.598, P<0.001; dynapenic obesity group, HR = 0.390, 95% CI = 0.206–0.739, P=0.004).

Conclusion

Elderly HF patients with dynapenia alone had poor prognoses. Obesity may have protective effects on the survival of dynapenia patients with HF.

P2610Increase in comfortable walking speed during hospitalization predicts the readmission due to decompensated heart failure in heart failure patients with preserved ejection fraction

Background

Heart failure patients with preserved ejection fraction (HFpEF) have reduced exercise capacity and poor prognosis as well as those with reduced ejection fraction (HFrEF). Both cardiac function and exercise capacity have been known as prognostic factors for patients with HFrEF. However, few reports documented the relations of comfortable walking speed (CWS) during hospitalization to exercise capacity and prognosis. is used as a clinical measure to assess their exercise capacity and prognosis. However, few reports documented the correlations of CWS with exercise capacity and prognosis in patients with HFpEF.

Purpose

This study aimed to investigate whether CWS at hospital discharge and the increase in CWS during hospitalization predicted the readmission due to decompensated heart failure in patients with HFpEF and HFrEF.

Methods

Patients who were hospitalized due to heart failure with New York Heart Association (NYHA) Functional Classification III or IV were prospectively followed up for 3 years after hospital discharge. Consequently, 264 patients, 173 males and 92 females, aged 73.2±6.8 years were studied. Patients were divided into 3 groups based on their ejection fraction (EF): HFpEF group (EF≥50%; n=98), HFrEF group (EF<40%; n=138) and heart failure with mid-range ejection fraction (HFmrEF) group (40%≤EF≤49%; n=28). We assessed clinical characteristics including age, gender, height, NYHA functional classification, etiology of CHF, plasma brain natriuretic peptide and left ventricular ejection fraction (LVEF) on admission, and measured CWS several days after admission and at discharge. We determined significant factors affecting the readmission and their cut-off values using univariate and multivariate logistic regression analyses and the area under the receiver operating characteristics curves in the three groups.

Results

Forty patients (40.8%), 54 (39.1%) and 6 (21.4%) were readmitted in the HFpEF, HFrEF and HFmrEF groups, respectively, within 3 years after the discharge. Univariate logistic regression analysis detected the age, LVEF, CWS at discharge and the CWS increase during hospitalization as significant limiting factors for readmission in the HFpEF and HFrEF groups (P<0.05, respectively). The multivariate logistic regression analysis detected the CWS increase during hospitalization as significant limiting factor for readmission in the HFpEF and HFrEF groups (P<0.001 and P<0.05, respectively). The odds ratios of readmission were 1.86 (P<0.01) and 1.44 (P<0.001) with each 5-meter decrease of CWS increase during hospitalization and predictive cut-off values of the CWS increase were 7.5 and 8.5 meters/min in the HFpEF and HFrEF groups, respectively.

Conclusion

This study demonstrated that the CWS increase during hospitalization was a strong predictor for readmission due to decompensated heart failure in patients not only with HFrEF but also with HFpEF and each predictive the cut-off value was 7.5 and 8.5 meters/min.

298Change in respiratory muscle strength predicts clinical events in patients with chronic heart failure

Background

Respiratory muscle weakness, frequently observed in patients with chronic heart failure (CHF), has been documented as a predictor for poor prognosis. Several studies have reported that respiratory muscle training increases respiratory muscle strength and consequently improves exercise tolerance and quality of life in these patients. However, the relationship between the change in respiratory muscle strength and prognosis is still unclear.

Purpose

We aimed to investigate whether the change in respiratory muscle strength following cardiac rehabilitation predicts the incidence of clinical events in CHF patients.

Methods

We studied 348 patients with CHF who were hospitalized because of decompensated heart failure and received 5-month cardiac rehabilitation during hospitalization and after hospital discharge. Clinical characteristics including aetiology of heart failure, comorbidity conditions, medications, blood examination and echocardiographic variables were obtained from clinical records. We also measured maximal inspiratory pressure (PImax) as respiratory muscle strength at hospital discharge and 5 months later. The change of PImax (ΔPImax) between the 5-month observation period was examined. We followed up the patients after the observation period and investigated the incidence of all-cause mortality or all-cause unplanned readmission. In statistical analysis, patients were divided into two groups based on the median value of ΔPImax. We compared the event-free survival rate between the two groups using the Kaplan-Meier method with a log-rank test. We also performed the Cox proportional hazard model to clarify whether the ΔPImax was an independent predictor for the incidence of clinical events.

Results

Over a median follow-up of 1.6 years, 121 patients (34.8%) died or readmitted, and their rate of incidence was 21.7/100 person-years. The higher ΔPImax was associated significantly with a higher rate of event-free survival (Log-rank: 8.085, P=0.004, Figure 1). In univariate Cox proportional hazard model, ΔPImax was a significant predictor for the all-cause mortality/readmission (unadjusted hazard ratio for PImax increase of 10 cmH2O: 0.842, 95% CI: 0.763 - 0.931, P=0.001). Even after adjustment for clinical confounding factors including baseline PImax, ΔPImax remained significant and independent predictor for the all-cause mortality/readmission (adjusted hazard ratio for PImax increase of 10 cmH2O: 0.862, 95% CI: 0.763 - 0.974, P=0.017, Figure 2).

Conclusion

This study is the first to demonstrate that the change in respiratory muscle strength following cardiac rehabilitation independently predicts the incidence of clinical events in patients with CHF. The increase in PImax of 10 cmH2O was associated significantly with a 14% decrease in the rate of all-cause mortality or readmission.

Acknowledgement/Funding

JSPS KAKENHI JP16K16442

P3106Atrial fibrillation is not associated with the responses to exercise training in heart failure patients with preserved ejection fraction

Background

Atrial fibrillation (AF) is known as a common arrhythmia in heart failure patients with preserved left ventricular ejection fraction (HFpEF). Several studies have reported that HFpEF patients with AF show lower exercise tolerance and poorer prognosis as compared with those with sinus rhythm (SR). On the other hand, exercise training is documented to improve peripheral muscle function and exercise tolerance in HFpEF patients. However, the relationship between AF status and outcomes due to exercise training is still unclear in these patients.

Purpose

We aimed to investigate the influence of AF on the responses to outcomes with exercise training in HFpEF patients.

Methods

We studied 426 patients with HFpEF who received 5-month cardiac rehabilitation including exercise training during hospitalization and after hospital discharge. As clinical characteristics, we obtained body mass index, disease aetiology, comorbidity conditions, blood examination and echocardiographic variables from medical records. We also measured isometric quadriceps strength (QS) and 6-minute walk distance (6MWD) as peripheral muscle strength and exercise tolerance, respectively. The QS and 6MWD were assessed at hospital discharge as the baseline and 5 months later. AF status was determined by the presence on electrocardiogram at baseline 6MWD or medical history of AF during hospitalization. In statistical analysis, we compared baseline clinical characteristics, QS and 6MWD between the rhythm status (SR group or AF group). We also examined the changes in QS and 6MWD from baseline to the 5-month observation period (ΔQS and Δ6MWD) and compared them between the 2 groups using analysis of covariance with adjustment for baseline clinical confounding factors.

Results

At baseline, 289 patients (68%) were in SR, and 111 patients (26%) had AF. The AF was associated significantly with older age (P<0.001) and lower levels of estimated glomerular filtration rate (P=0.013), QS (P<0.001) and 6MWD (P<0.001) at baseline. The QS increased significantly from 25.2±11.0 kg at baseline to 30.8±13.0 kg after 5-month cardiac rehabilitation in the SR group, and from 21.1±8.3 kg to 26.0±9.4 kg in the AF group (P<0.001, respectively). The 6MWD also increased significantly from 394.8±129.2 to 463.5±133.5 meters in the SR, and from 343.7±107.9 to 403.0±114.5 meters in the AF (P<0.001, respectively). There were no significant differences in ΔQS and Δ6MWD between the SR and AF groups even after adjustment for clinical confounding factors including baseline QS or 6MWD (Figure).

Conclusions

The AF status in HFpEF patients was associated with older age, lower peripheral muscle function and also lower exercise tolerance at baseline, but not associated with the responses to exercise training.

Acknowledgement/Funding

JSPS KAKENHI JP16K16442

Abstract P4-08-24: Prognostic significance of preoperative neutrophil-to-lymphocyte ratio in postmenopausal breast cancer patients

Background: Several studies have shown the association between high neutrophil-to-lymphocyte ratio (NLR) and poor prognosis in various cancer types, including breast cancer. On the other hand, menopausal status, which is an important consideration in breast cancer treatment, has been shown to be associated with changes in NLR levels. The purpose of the present study was to clarify the prognostic significance of preoperative NLR, especially in postmenopausal breast cancer patients.

Patients and methods: Between October 2003 and December 2014, 1868 women underwent surgery without neoadjuvant systemic therapy for primary breast cancer in our department. The optimal cutoff value of preoperative NLR was determined using receiver operating characteristic curve analysis. The patients were divided into two groups based on the NLR cutoff value of 3.34: High NLR (NLR value ≥ 3.34) and Low NLR (NLR value &lt; 3.34). Correlations between clinicopathological characteristics and preoperative NLR were analyzed, and relapse-free survival (RFS) and overall survival (OS) were estimated.

Results: Among the 1868 patients, 286 (15.3%) and 1582 (84.7%) patients were classified into High NLR and Low NLR, respectively. Although the patients in High NLR was younger (p=0.0023), there were no significant correlations between NLR and all other prognostic factors, such as tumor size, lymph node status, and histological grade. High NLR was associated with tendency to shorter RFS (p=0.0583) and shorter OS (p=0.0303). In postmenopausal patients (n=1177), significant correlations were observed between High NLR and shorter RFS and OS (p=0.0002 and p=0.0011). However, NLR was not correlated with RFS and OS in premenopausal patients (n=691). Although the postmenopausal patients with relapsed cancer had higher NLR levels than those without relapse (p=0.0252), NLR levels were not correlated with relapse occurrence in premenopausal patients. Both univariate (p=0.0009) and multivariate (p=0.0015) analyses revealed that High NLR as well as larger tumor size, lymph node metastases, and higher histological grade was significantly associated with relapse in postmenopausal patients. Moreover, in postmenopausal patients, subgroup analysis according to cancer subtype revealed that High NLR was correlated with shorter RFS only in patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer (p=0.0009), in those without adjuvant chemotherapy (p=0.0034) but not in those with adjuvant chemotherapy.

Conclusion: Elevated preoperative NLR is an independent predictor of poor prognosis in postmenopausal but not premenopausal patients with breast cancer. In postmenopausal patients, adjuvant chemotherapy may improve prognosis in patients with HR-positive/HER2-negative breast cancer, especially in those with elevated preoperative NLR.

Citation Format: Ijichi H, Tajiri W, Masuda T, Koga C, Tanaka J, Nakamura Y, Okamoto M, Tokunaga E. Prognostic significance of preoperative neutrophil-to-lymphocyte ratio in postmenopausal breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-24.

Search for K_{L}→π^{0}νν[over ¯] and K_{L}→π^{0}X^{0} Decays at the J-PARC KOTO Experiment

A search for the rare decay K_{L}→π^{0}νν[over ¯] was performed. With the data collected in 2015, corresponding to 2.2×10^{19} protons on target, a single event sensitivity of (1.30±0.01_{stat}±0.14_{syst})×10^{-9} was achieved and no candidate events were observed. We set an upper limit of 3.0×10^{-9} for the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for K_{L}→π^{0}X^{0} was also set as 2.4×10^{-9} at the 90% C.L., where X^{0} is an invisible boson with a mass of 135  MeV/c^{2}.

Thoracoabdominal pressure gradient and gastroesophageal reflux: insights from lung transplant candidates

Advanced lung disease is associated with gastroesophageal reflux disease (GERD). The thoracoabdominal pressure gradient (TAPG) facilitates gastroesophageal reflux, but the effects of TAPG on gastroesophageal reflux in patients with pulmonary disease have not been well defined. Patients diagnosed with end-stage lung disease are expected to have the most extreme derangement in respiratory mechanics. The aim of this study is to explore the relationship between TAPG and reflux in lung transplant (LTx) candidates. We reviewed LTx recipients who underwent pretransplant esophageal high-resolution manometry and a 24-hour pH study. Patients were excluded if they were undergoing redo LTx, had manometric hiatal hernia, or had previously undergone foregut surgery. TAPG was defined as the intra-abdominal pressure minus the intrathoracic pressure during inspiration. Adjusted TAPG was calculated by the TAPG minus the resting lower esophageal sphincter (LES) pressure (LESP). Twenty-two patients with normal esophageal function tests (i.e., normal esophageal motility with neither manometric hiatal hernia nor pathological reflux on 24-hour pH monitoring) were selected as the pulmonary disease-free control group. In total, 204 patients underwent LTx between January 2015 and December 2016. Of these, 77 patients met inclusion criteria. We compared patients with obstructive lung disease (OLD, n = 33; 42.9%) and those with restrictive lung disease (RLD, n = 42; 54.5%). 2/77 patients (2.6%) had pulmonary arterial hypertension. GERD was more common in the RLD group than in the OLD group (24.2% vs. 47.6%, P = 0.038). TAPG was similar between the OLD group and the controls (14.2 vs. 15.3 mmHg, P = 0.850); however, patients in the RLD group had significantly higher TAPG than the controls (24.4 vs. 15.3 mmHg, P = 0.002). Although TAPG was not correlated with GERD, the adjusted TAPG correlated with reflux in all 77 patients with end-stage lung disease (DeMeester score, rs = 0.256, P = 0.024; total reflux time, rs = 0.259, P = 0.023; total number of reflux episodes, rs = 0.268, P = 0.018). Additionally, pathological reflux was seen in 59.1% of lung transplant candidates with adjusted TAPG greater than 0 mmHg (i.e., TAPG exceeding LESP); GERD was seen in 30.9% of patients who had an adjusted TAPG ≤ 0 mmHg. In summary, TAPG varies based on the underlying cause of lung disease. Higher adjusted TAPG increases pathological reflux, even if patients have normal antireflux anatomy and physiology (i.e., no hiatal hernia and manometrically normal LES function). Adjusted TAPG may provide further insights into the pathophysiology of GERD.

Decreased regional cerebral blood flow in patients with diphenylarsinic acid intoxication

BACKGROUND AND PURPOSE

Diphenylarsinic acid (DPAA) intoxication caused by drinking contaminated well water was found in Kamisu, Japan. The symptoms indicated cerebellar-brainstem and temporo-occipital involvement. However, it remains unclear how it affects the human brain. To elucidate the effect of DPAA on the human brain, we analyzed cerebral blood flow (CBF) data after the drinking of DPAA-contaminated water was stopped and investigated the correlation between DPAA exposure level and CBF by single-photon emission computed tomography (CBF-SPECT).

METHODS

The DPAA-exposed inhabitants (n = 78) were divided into 35 symptomatic and 43 asymptomatic subjects and compared with 38 healthy controls. The DPAA concentration in nails or hair and well water was measured using a high-performance liquid chromatography system and coupled plasma mass spectrometry after adequate extraction treatment. CBF-SPECT data, obtained within 1 year after the drinking of contaminated well water was stopped, were analyzed by statistical parametric mapping. We also examined the relationship between variations in CBF-SPECT signals and variations in DPAA concentrations in the hair or nails of the subjects.

RESULTS

Compared with control subjects, CBF in symptomatic DPAA-exposed subjects was significantly lower in the occipital lobe, including the cuneus and inferior occipital gyri. The DPAA concentration in the nails or hair of subjects was inversely and significantly related to their CBF.

CONCLUSION

These data suggest that CBF-SPECT may be useful as a clinical marker to infer the effect of accumulated DPAA on the brain.

Prognostic usefulness of arm circumference and nutritional screening tools in older patients with cardiovascular disease

BACKGROUND AND AIM

Arm circumference (AC) and nutritional screening tools have been shown to have prognostic capability in patients with cardiovascular disease (CVD). This study aimed to compare the prognostic predictive capabilities of AC and nutritional screening tools in older patients with CVD.

METHODS AND RESULTS

The study population consisted of 949 admitted patients ≥60 years old with CVD. Patients underwent AC measurement and nutritional screening before hospital discharge. We used the controlling nutritional status index (CONUT), the geriatric nutritional risk index (GNRI), and the prognostic nutritional index (PNI) as nutritional screening tools. The end point of the study was all-cause mortality. The mean age of the study population was 72.3 ± 7.2 years, and 68.2% of the patients were male. A total of 130 deaths occurred over a median follow-up period of 2.2 years (interquartile range, 1.1-3.8 years). After adjusting for other prognostic factors, AC (hazard ratio [HR]: 0.59; p < 0.001), CONUT (HR: 0.82; p = 0.016), GNRI (HR: 0.77; p = 0.040), and PNI (HR: 0.80; p = 0.014) were significant predictors of mortality. However, adding AC to the multivariate-adjusted model (0.739 vs. 0.714, respectively; p = 0.037), but not CONUT, GNRI, or PNI (0.724, 0.717, and 0.723 vs. 0.714; p = 0.072, p = 0.306, and p = 0.127, respectively), significantly increased the area under the curve on receiver operating characteristic curve.

CONCLUSIONS

AC, but not nutritional screening tools, plays a complementary role to preexisting prognostic factors for predicting prognosis in older patients with CVD.

Swallow-induced esophageal shortening in patients without hiatal hernia is associated with gastroesophageal reflux

Longitudinal esophageal body shortening with swallow-induced peristalsis has been reported in healthy individuals. Esophageal shortening is immediately followed by esophageal re-elongation, and the lower esophageal sphincter (LES) returns to the baseline position. High-resolution manometry (HRM) allows for objective assessment of extent of shortening and duration of shortening. In patients without hiatal hernia at rest, swallow-induced esophageal shortening can lead to transient hiatal hernia (tHH) which at times may persist after the completion of swallow. This manometric finding has not been investigated in the literature, but a question arises whether this swallow-induced transient herniation can effect on the likelihood of gastroesophageal reflux. This study aims to assess the relationship between gastroesophageal reflux and the subtypes of swallow-induced esophageal shortening, i.e. tHH and non-tHH, in patients without hiatal hernia at rest. After Institutional Review Board (IRB) approval, we queried a prospectively maintained database to identify patients who underwent HRM evaluation and 24-hour pH study between January to December 2015. Patients with type-I esophagogastric junction (EGJ) morphology (i.e. no hiatal hernia) according to the Chicago classification v3.0 were included. The patterns of the esophageal shortening with swallows were divided into two subtypes, i.e. tHH and non-tHH. tHH was defined as an EGJ double high-pressure zones (≥1 cm) at the second inspiration after the termination of swallow-induced esophageal body contraction. The number of episodes of tHH was counted per 10 swallows and tHH size was measured for each patient. In total, 41 patients with EGJ morphology Type-I met the inclusion criteria. The mean age was 47.2 years, 35 patients (85.4%) were women, and the mean body mass index was 33.9 kg/m2. The mean number of tHH episodes was 3 out of 10 swallows; mean maximal tHH size was 1.3 cm. Patients who had tHH in ≥3 out of 10 swallows (n = 16; 39.0%) were more likely to have abnormal DeMeester scores than patients with <3 swallows (56% vs. 28%; P = 0.070). Patients with maximal tHH ≥2 cm in at least 1 swallow (n = 17; 41.5%) were more likely to experience pathological reflux than patients with maximal tHH <2 cm (59% vs. 25%; P = 0.029). In conclusion, we showed that, in a subset of patients with Type-I EGJ morphology, swallowing induced transient EGJ double high-pressure zones (≥1 cm) after peristalsis. We have named this new manometric finding the swallow-induced tHH. A high prevalence of pathological reflux disease was observed in patients with maximal tHH ≥2 cm. The degree of swallow-induced tHH could be an early indicator of lower esophageal sphincter dysfunction in patients without manometric hiatal hernia.

Low temperature magnetic properties of Nd2Ru2O7

We present magnetic susceptibility, heat capacity, and neutron diffraction measurements of polycrystalline Nd₂Ru₂O₇ down to 0.4 K. Three anomalies in the magnetic susceptibility measurements at 146, 21 and 1.8 K are associated with an antiferromagnetic ordering of the Ru⁴⁺ moments, a weak ferromagnetic signal attributed to a canting of the Ru⁴⁺ and Nd³⁺ moments, and a long-range-ordering of the Nd³⁺ moments, respectively. The long-range order of the Nd³⁺ moments was observed in all the measurements, indicating that the ground state of the compound is not a spin glass. The magnetic entropy of Rln2 accumulated up to 5 K, suggests the Nd³⁺ has a doublet ground state. Lattice distortions accompany the transitions, as revealed by neutron diffraction measurements, and in agreement with earlier synchrotron x-ray studies. The magnetic moment of the Nd³⁺ ion at 0.4 K is estimated to be 1.54(2)µ _B and the magnetic structure is all-in all-out as determined by our neutron diffraction measurements.

Improved On-Line Thoracic Duct Drainage for Lymphocytapheresis

Lymphocytapheresis using thoracic duct drainage (TDD) is a recognized technique of extracorporeal immunomodulation for various autoimmune diseases such as rheumatoid arthritis (RA), and its clinical benefit has been reported and generally accepted. Lymphocytapheresis using TDD is very selective for removing lymphocytes (especially helper T-cells) but raises some problems such as hypoproteinemia due to the massive removal of lymph, and difficulties in repeated treatment. Along with the development of a new polyester fiber filter, we have developed a simple and effective method of lymphocytapheresis for wide adoption for these techniques. We performed lymphocytapheresis using TDD in patients with RA and previously reported its clinical efficacy indicated by the significantly lower number of peripheral lymphocytes and T4/T8 ratio. We present here our newly-developed on-line system designed to prevent hypoproteinemia. Furthermore we report on the advantages with a new subcutaneous vascular access device set up to manage the problems of repeated treatments. A small reservoir for keeping the thoracic duct open and returning lymph to the patient permitted sufficient lymph drainage and removal of lymphocytes and the clinical application of TDD is discussed.

Abstract P2-09-33: Not presented

This abstract was not presented at the symposium.

Angiopoietin-like protein 2 promotes chondrogenic differentiation during bone growth as a cartilage matrix factor

OBJECTIVE

Chondrocyte differentiation is crucial for long bone growth. Many cartilage extracellular matrix (ECM) proteins reportedly contribute to chondrocyte differentiation, indicating that mechanisms underlying chondrocyte differentiation are likely more complex than previously appreciated. Angiopoietin-like protein 2 (ANGPTL2) is a secreted factor normally abundantly produced in mesenchymal lineage cells such as adipocytes and fibroblasts, but its loss contributes to the pathogenesis of lifestyle- or aging-related diseases. However, the function of ANGPTL2 in chondrocytes, which are also differentiated from mesenchymal stem cells, remains unclear. Here, we investigate whether ANGPTL2 is expressed in or functions in chondrocytes.

METHODS

First, we evaluated Angptl2 expression during chondrocyte differentiation using chondrogenic ATDC5 cells and wild-type epiphyseal cartilage of newborn mice. We next assessed ANGPTL2 function in chondrogenic differentiation and associated signaling using Angptl2 knockdown ATDC5 cells and Angptl2 knockout mice.

RESULTS

ANGPTL2 is expressed in chondrocytes, particularly those located in resting and proliferative zones, and accumulates in ECM surrounding chondrocytes. Interestingly, long bone growth was retarded in Angptl2 knockout mice from neonatal to adult stages via attenuation of chondrocyte differentiation. Both in vivo and in vitro experiments show that changes in ANGPTL2 expression can also alter p38 mitogen-activated protein kinase (MAPK) activity mediated by integrin α5β1.

CONCLUSION

ANGPTL2 contributes to chondrocyte differentiation and subsequent endochondral ossification through α5β1 integrin and p38 MAPK signaling during bone growth. Our findings provide insight into molecular mechanisms governing communication between chondrocytes and surrounding ECM components in bone growth activities.