Evaluation of the performance of both machine learning models using PET and CT radiomics for predicting recurrence following lung stereotactic body radiation therapy: A single-institutional study

PURPOSE

Predicting recurrence following stereotactic body radiotherapy (SBRT) for non-small cell lung cancer provides important information for the feasibility of the individualized radiotherapy and allows to select the appropriate treatment strategy based on the risk of recurrence. In this study, we evaluated the performance of both machine learning models using positron emission tomography (PET) and computed tomography (CT) radiomic features for predicting recurrence after SBRT.

METHODS

Planning CT and PET images of 82 non-small cell lung cancer patients who performed SBRT at our hospital were used. First, tumors were delineated on each CT and PET of each patient, and 111 unique radiomic features were extracted, respectively. Next, the 10 features were selected using three different feature selection algorithms, respectively. Recurrence prediction models based on the selected features and four different machine learning algorithms were developed, respectively. Finally, we compared the predictive performance of each model for each recurrence pattern using the mean area under the curve (AUC) calculated following the 0.632+ bootstrap method.

RESULTS

The highest performance for local recurrence, regional lymph node metastasis, and distant metastasis were observed in models using Support vector machine with PET features (mean AUC = 0.646), Naive Bayes with PET features (mean AUC = 0.611), and Support vector machine with CT features (mean AUC = 0.645), respectively.

CONCLUSIONS

We comprehensively evaluated the performance of prediction model developed for recurrence following SBRT. The model in this study would provide information to predict the recurrence pattern and assist in making treatment strategies.

Deep learning model with collage images for the segmentation of dedicated breast positron emission tomography images

BACKGROUND

Dedicated breast positron emission tomography (dbPET) has high contrast and resolution optimized for detecting small breast cancers, leading to its noisy characteristics. This study evaluated the application of deep learning to the automatic segmentation of abnormal uptakes on dbPET to facilitate the assessment of lesions. To address data scarcity in model training, we used collage images composed of cropped abnormal uptakes and normal breasts for data augmentation.

METHODS

This retrospective study included 1598 examinations between April 2015 and August 2020. A U-Net-based model with an uptake shape classification head was trained using either the original or augmented dataset comprising collage images. The Dice score, which measures the pixel-wise agreement between a prediction and its ground truth, of the models was compared using the Wilcoxon signed-rank test. Moreover, the classification accuracies were evaluated.

RESULTS

After applying the exclusion criteria, 662 breasts were included; among these, 217 breasts had abnormal uptakes (mean age: 58 ± 14 years). Abnormal uptakes on the cranio-caudal and mediolateral maximum intensity projection images of 217 breasts were annotated and labeled as focus, mass, or non-mass. The inclusion of collage images into the original dataset yielded a Dice score of 0.884 and classification accuracy of 91.5%. Improvement in the Dice score was observed across all subgroups, and the score of images without breast cancer improved significantly from 0.750 to 0.834 (effect size: 0.76, P = 0.02).

CONCLUSIONS

Deep learning can be applied for the automatic segmentation of dbPET, and collage images can improve model performance.

Organ-Specific Positron Emission Tomography Scanners for Breast Imaging: Comparison between the Performances of Prior and Novel Models

The performances of photomultiplier tube (PMT)-based dedicated breast positron emission tomography (PET) and silicon photomultiplier tube (SiPM)-based time-of-flight (TOF) PET, which is applicable not only to breast imaging but also to head imaging, were compared using a phantom study. A cylindrical phantom containing four spheres (3–10 mm in diameter) filled with 18F-FDG at two signal-to-background ratios (SBRs), 4:1 and 8:1, was scanned. The phantom images, which were reconstructed using three-dimensional list-mode dynamic row-action maximum likelihood algorithm with various β-values and post-smoothing filters, were visually and quantitatively compared. Visual evaluation showed that the 3 mm sphere was more clearly visualized with higher β and smaller post-filters, while the background was noisier; SiPM-based TOF-PET was superior to PMT-based dbPET in sharpness, smoothness, and detectability, although the background was noisier at the SBR of 8:1. Quantitative evaluation revealed that the detection index (DI) and recovery coefficient (CRC) of SiPM-based TOF-PET images were higher than those of PMT-based PET images, despite a higher background coefficient of variation (CVBG). The two organ-specific PET systems showed that a 3 mm lesion in the breast could be visualized at the center of the detector, and there was less noise in the SiPM-based TOF-PET image.

Dedicated phantom tools using traceable 68Ge/68Ga point-like sources for dedicated-breast PET and positron emission mammography scanners

Since the early 2000s, many types of positron emission tomography (PET) scanners dedicated to breast imaging for the diagnosis of breast cancer have been introduced. However, conventional performance evaluation methods developed for whole-body PET scanners cannot be used for such devices. In this study, we developed phantom tools for evaluating the quantitative accuracy of positron emission mammography (PEM) and dedicated-breast PET (dbPET) scanners using novel traceable point-like ⁶⁸Ge/⁶⁸ Ga sources. The PEM phantom consisted of an acrylic cube (100 × 100 × 40 mm) and three point-like sources. The dbPET phantom comprised an acrylic cylinder (ø100 × 100 mm) and five point-like sources. These phantoms were used for evaluating the fundamental responses of clinical PEM and dbPET scanners to point-like inputs in a medium. The results showed that reasonable recovery values were obtained based on region-of-interest analyses of the reconstructed images. The developed phantoms using traceable ⁶⁸Ge/⁶⁸ Ga point-like sources were useful for evaluating the physical characteristics of PEM and dbPET scanners. Thus, they offer a practical, reliable, and universal measurement scheme for evaluating various types of PET scanners using common sets of sealed sources.

Proposal to Improve the Image Quality of Short-Acquisition Time-Dedicated Breast Positron Emission Tomography Using the Pix2pix Generative Adversarial Network

This study aimed to evaluate the ability of the pix2pix generative adversarial network (GAN) to improve the image quality of low-count dedicated breast positron emission tomography (dbPET). Pairs of full- and low-count dbPET images were collected from 49 breasts. An image synthesis model was constructed using pix2pix GAN for each acquisition time with training (3776 pairs from 16 breasts) and validation data (1652 pairs from 7 breasts). Test data included dbPET images synthesized by our model from 26 breasts with short acquisition times. Two breast radiologists visually compared the overall image quality of the original and synthesized images derived from the short-acquisition time data (scores of 1−5). Further quantitative evaluation was performed using a peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). In the visual evaluation, both readers revealed an average score of >3 for all images. The quantitative evaluation revealed significantly higher SSIM (p < 0.01) and PSNR (p < 0.01) for 26 s synthetic images and higher PSNR for 52 s images (p < 0.01) than for the original images. Our model improved the quality of low-count time dbPET synthetic images, with a more significant effect on images with lower counts.

Effect of radioactivity outside the field of view on image quality of dedicated breast positron emission tomography: preliminary phantom and clinical studies

OBJECTIVE

Semi-quantitative positron emission tomography (PET) values, such as the maximum standardized uptake value (SUV_max), are widely used to identify malignant lesions and evaluate the response to treatment. The image quality of ring-shaped dedicated breast positron emission tomography (dbPET) has been known to decrease the closer it is to the detector's edge. This study aimed to investigate the effect of radioactivity (RI) outside the detector field of view (FOV) on the image quality of the ring-shaped dbPET.

METHODS

A breast phantom containing the left myocardium, which was prepared using a 3D printer, filled with ¹⁸F-fluorodeoxyglucose (FDG) solution with various RI concentration ratios (RCRs) of myocardium to background and scanned with the edge of an apex positioned exactly in line with the edge of the FOV of the dbPET scanner. The phantom image quality was visually and quantitatively evaluated. Following the phantom study, left-right breast differences (the left breast uptake ratio to the right breast (LUR)) on clinical dbPET images of 74 women were quantitatively evaluated. The relationships between these parameters, clinical indices, and FDG uptake in the left myocardium on PET/computed tomography (CT) images were analyzed.

RESULTS

The phantom study showed that the higher the RCR of the myocardium and the closer it is to the top edge of the phantom, the higher is the pixel value of the dbPET images. In a clinical study, LUR was significantly correlated with myocardial SUV_max (r = 0.96, p < 0.0001) and metabolic myocardial volume (r = 0.63, p = 0.001) for whole-body PET/CT imaging. Although no significant correlations were found between LUR and age (r = 0.05, p = 0.6865), body mass index (r = 0.03, p = 0.8178), or distance between the left myocardial apex and chest wall (r = 0.16, p = 0.1667).

CONCLUSIONS

FDG uptake in the myocardium affected dbPET images of the left breast, especially near the chest wall. Further, the effect of RI outside the FOV, such as in the myocardium, must be considered in the quantitative evaluation of breast cancer using dbPET.

Semi-automated histogram analysis of normal bone marrow using 18F-FDG PET/CT: correlation with clinical indicators

Background

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly applied to the diagnosis of bone marrow failure such as myeloproliferative neoplasm, aplastic anemia, and myelodysplastic syndrome, as well as malignant lymphoma and multiple myeloma. However, few studies have shown a normal FDG uptake pattern. This study aimed to establish a standard of bone marrow FDG uptake by a reproducible quantitative method with fewer steps using deep learning-based organ segmentation.

Methods

Bone marrow PET images were obtained using segmented whole-spine and pelvic bone marrow cavity CT as mask images using a commercially available imaging workstation that implemented an automatic organ segmentation algorithm based on deep learning. The correlation between clinical indicators and quantitative PET parameters, including histogram features, was evaluated.

Results

A total of 98 healthy adults were analyzed. The volume of bone marrow PET extracted in men was significantly higher than that in women (p < 0.0001). Univariate and multivariate regression analyses showed that mean of standardized uptake value corrected by lean body mass (SUL_mean) and entropy in both men and women were inversely correlated with age (all p < 0.0001), and SUL_max in women were also inversely correlated with age (p = 0.011).

Conclusion

A normal FDG uptake pattern was demonstrated by simplified FDG PET/CT bone marrow quantification.

Deep learning for image classification in dedicated breast positron emission tomography (dbPET)

OBJECTIVE

This study aimed to investigate and determine the best deep learning (DL) model to predict breast cancer (BC) with dedicated breast positron emission tomography (dbPET) images.

METHODS

Of the 1598 women who underwent dbPET examination between April 2015 and August 2020, a total of 618 breasts on 309 examinations for 284 women who were diagnosed with BC or non-BC were analyzed in this retrospective study. The Xception-based DL model was trained to predict BC or non-BC using dbPET images from 458 breasts of 109 BCs and 349 non-BCs, which consisted of mediallateral and craniocaudal maximum intensity projection images, respectively. It was tested using dbPET images from 160 breasts of 43 BC and 117 non-BC. Two expert radiologists and two radiology residents also interpreted them. Sensitivity, specificity, and area under the receiver operating characteristic curves (AUCs) were calculated.

RESULTS

Our DL model had a sensitivity and specificity of 93% and 93%, respectively, while radiologists had a sensitivity and specificity of 77-89% and 79-100%, respectively. Diagnostic performance of our model (AUC = 0.937) tended to be superior to that of residents (AUC = 0.876 and 0.868, p = 0.073 and 0.073), although not significantly different. Moreover, no significant differences were found between the model and experts (AUC = 0.983 and 0.941, p = 0.095 and 0.907).

CONCLUSIONS

Our DL model could be applied to dbPET and achieve the same diagnostic ability as that of experts.

A Proposed Dedicated Breast PET Lexicon: Standardization of Description and Reporting of Radiotracer Uptake in the Breast

Dedicated breast positron emission tomography (dbPET) is a new diagnostic imaging modality recently used in clinical practice for the detection of breast cancer and the assessment of tumor biology. dbPET has higher spatial resolution than that of conventional whole body PET systems, allowing recognition of detailed morphological attributes of radiotracer accumulation within the breast. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) accumulation in the breast may be due to benign or malignant entities, and recent studies suggest that morphology characterization of ¹⁸F-FDG uptake could aid in estimating the probability of malignancy. However, across the world, there are many descriptors of breast ¹⁸F-FDG uptake, limiting comparisons between studies. In this article, we propose a lexicon for breast radiotracer uptake to standardize description and reporting of image findings on dbPET, consisting of terms for image quality, radiotracer fibroglandular uptake, breast lesion uptake.

Optimal relaxation parameters of dynamic row-action maximum likelihood algorithm and post-smoothing filter for image reconstruction of dedicated breast PET

OBJECTIVE

This study aimed to determine the optimal β value of the relaxation control parameter and the post-smoothing filter in the list-mode dynamic row-action maximum likelihood algorithm (LM-DRAMA) to detect early stage breast cancer with high-resolution dedicated breast positron emission tomography (dbPET) in phantom and clinical studies.

METHODS

A breast phantom containing four spheres (5, 7.5, 10, and 16 mm in diameter) was filled with ¹⁸F-fluorodeoxyglucose solution (sphere-to-background ratio, 8:1) and scanned on a dbPET scanner. The images were reconstructed using LM-DRAMA with different β values (5, 20, or 100) and Gaussian post-filters (0, 0.78, 1.17, 1.56, 1.95, or 2.34 mm). Other conditions were according to those routinely used (1 iteration and 128 subsets including attenuation and scatter correction). Image quality was evaluated visually and by computing the coefficient of variation of the background (CV_BG), detectability index (DI), and contrast recovery coefficient. Parameters optimized in these phantom studies were applied to 25 clinical data sets. Variabilities for different reconstruction methods in visual scores, the maximum standardized uptake value of breast cancer, and the tumor-to-background uptake ratio were estimated.

RESULTS

The reconstruction images of the phantom with higher β values and smaller post-filters yielded higher visual scores for detectability and DI and lower smoothness and CV_BG scores. Based on the phantom study, the β values and post-filter were optimized for clinical dbPET images except for β5 and 2.34 mm post-filter. Applying the other reconstructions to clinical studies showed that β100 provided higher quantitative parameter values. The detectability of lesions was similar for β100 and β20 and decreased with larger post-filters. The lesion detection rate was similar for β100 and β20 and decreased with larger post-filter.

CONCLUSION

The relaxation coefficient factor β20 and a 0.78- or 1.17-mm post-filter were optimal for dbPET image reconstruction with balanced spatial resolution and noise. However, they should be selected according to the impact on the dbPET image and the purpose of the examination.

Clinical practice guidelines for high-resolution breast PET, 2019 edition

Breast positron emission tomography (PET) has had insurance coverage when performed with conventional whole-body PET in Japan since 2013. Together with whole-body PET, accurate examination of breast cancer and diagnosis of metastatic disease are possible, and are expected to contribute significantly to its treatment planning. To facilitate a safer, smoother, and more appropriate examination, the Japanese Society of Nuclear Medicine published the first edition of practice guidelines for high-resolution breast PET in 2013. Subsequently, new types of breast PET have been developed and their clinical usefulness clarified. Therefore, the guidelines for breast PET were revised in 2019. This article updates readers as to what is new in the second edition. This edition supports two different types of breast PET depending on the placement of the detector: the opposite-type (positron emission mammography; PEM) and the ring-shaped type (dedicated breast PET; dbPET), providing an overview of these scanners and appropriate imaging methods, their clinical applications, and future prospects. The name "dedicated breast PET" from the first edition is widely used to refer to ring-shaped type breast PET. In this edition, "breast PET" has been defined as a term that refers to both opposite- and ring-shaped devices. Up-to-date breast PET practice guidelines would help provide useful information for evidence-based breast imaging.

Evaluation of image quality at the detector's edge of dedicated breast positron emission tomography

BACKGROUND

Using phantoms and clinical studies in prone hanging breast imaging, we assessed the image quality of a commercially available dedicated breast PET (dbPET) at the detector's edge, where mammary glands near the chest wall are located. These are compared to supine PET/CT breast images of the same clinical subjects.

METHODS

A breast phantom with four spheres (16-, 10-, 7.5-, and 5-mm diameter) was filled with ¹⁸F-fluorodeoxyglucose solution (sphere-to-background activity concentration ratio, 8:1). The spheres occupied five different positions from the top edge to the centre of the detector and were scanned for 5 min in each position. Reconstructed images were visually evaluated, and the contrast-to-noise ratio (CNR), contrast recovery coefficient (CRC) for all spheres, and coefficient of variation of the background (CV_B) were calculated. Subsequently, clinical images obtained with standard supine PET/CT and prone dbPET were retrospectively analysed. Tumour-to-background ratios (TBRs) between breast cancer near the chest wall (close to the detector's edge; peripheral group) and at other locations (non-peripheral group) were compared. The TBR of each lesion was compared between dbPET and PET/CT.

RESULTS

Closer to the detector's edge, the CNR and CRC of all spheres decreased while the CV_B increased in the phantom study. The disadvantages of this placement were visually confirmed. Regarding clinical images, TBR of dbPET was significantly higher than that of PET/CT in both the peripheral (12.38 ± 6.41 vs 6.73 ± 3.5, p = 0.0006) and non-peripheral (12.44 ± 5.94 vs 7.71 ± 7.1, p = 0.0183) groups. There was no significant difference in TBR of dbPET between the peripheral and non-peripheral groups.

CONCLUSION

The phantom study revealed poorer image quality at < 2-cm distance from the detector's edge than at other more central parts. In clinical studies, however, the visibility of breast lesions with dbPET was the same regardless of the lesion position, and it was higher than that in PET/CT. dbPET has a great potential for detecting breast lesions near the chest wall if they are at least 2 cm from the edge of the FOV, even in young women with small breasts.

Texture Analysis in the Diagnosis of Primary Breast Cancer: Comparison of High-Resolution Dedicated Breast Positron Emission Tomography (dbPET) and Whole-Body PET/CT

Objective: This retrospective study aimed to compare the ability to classify tumor characteristics of breast cancer (BC) of positron emission tomography (PET)-derived texture features between dedicated breast PET (dbPET) and whole-body PET/computed tomography (CT).

Methods: Forty-four BCs scanned by both high-resolution ring-shaped dbPET and whole-body PET/CT were analyzed. The primary BC was extracted with a standardized uptake value (SUV) threshold segmentation method. On both dbPET and PET/CT images, 38 texture features were computed; their ability to classify tumor characteristics such as tumor (T)-category, lymph node (N)-category, molecular subtype, and Ki67 levels was compared. The texture features were evaluated using univariate and multivariate analyses following principal component analysis (PCA). AUC values were used to evaluate the diagnostic power of the computed texture features to classify BC characteristics.

Results: Some texture features of dbPET and PET/CT were different between Tis-1 and T2-4 and between Luminal A and other groups, respectively. No association with texture features was found in the N-category or Ki67 level. In contrast, receiver-operating characteristic analysis using texture features' principal components showed that the AUC for classification of any BC characteristics were equally good for both dbPET and whole-body PET/CT.

Conclusions: PET-based texture analysis of dbPET and whole-body PET/CT may have equally good classification power for BC.

Reduction of the fluorine-18-labeled fluorodeoxyglucose dose for clinically dedicated breast positron emission tomography

PURPOSE

To determine the clinically acceptable level of reduction in the injected fluorine-18 (¹⁸F)-labeled fluorodeoxyglucose (¹⁸F-FDG) dose in dedicated breast positron emission tomography (dbPET).

METHODS

A breast phantom with four spheres exhibiting various diameters (5, 7.5, 10, and 16 mm), a background ¹⁸F-FDG radioactivity of 2.28 kBq/mL, and a sphere-to-background radioactivity ratio of 8:1 was used. True dose-reduced dbPET images were obtained by data acquisition for 20 min in list mode at multiple time points over 7 h of radioactive decay. Simulated dose-reduced images were generated by reconstruction with a portion of the list mode acquisition data. True and simulated dose-reduced images were visually and quantitatively compared. On the basis of the phantom study, dbPET images for 32 breasts of 28 women with abnormal uptake were generated after simulated reduction of the injected ¹⁸F-FDG doses; these images were compared with those acquired using current clinical doses.

RESULTS

There were no qualitative differences between true and simulated dose-reduced phantom images. The phantom study revealed that the minimal required dose was 12.5% for the detection of 5-mm spheres and 25% for precise semi-quantification of FDG in the spheres. The 7-min reconstruction with a 100% dose was defined as the reference for the clinical study. The image quality and lesion conspicuity were clinically acceptable for the 25% dose images. Lesion detectability on the 12.5% dose images was maintained despite image quality degradation.

CONCLUSIONS

In summary, 25% of the standard ¹⁸F-FDG dose for dbPET can provide a clinically acceptable image quality, while 12.5% of the standard dose results in acceptable quality in terms of lesion detection when lesions are located at a sufficient distance from the edge of the dbPET detector.

Comparison of dedicated breast positron emission tomography and whole-body positron emission tomography/computed tomography images: a common phantom study

OBJECTIVE

High-resolution dedicated breast positron emission tomography (dbPET) can visualize breast cancer more clearly than whole-body PET/computed tomography (CT). In Japan, the combined use of dbPET and whole-body PET/CT is necessary in indications for health insurance. Although several clinical studies have compared both devices, a physical evaluation by the phantom test has not been reported. The aim of this study was to compare the ability of ring-shaped dbPET and whole-body PET/CT using a common phantom with reference to the Japanese guideline for the oncology ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT data acquisition protocol.

METHODS

A cylindrical breast phantom with four spheres of different diameters (16, 10, 7.5, and 5 mm) filled an FDG solution at sphere-to-background radioactivity ratios (SBRs) of 2:1, 4:1, and 8:1 was prepared. Images were then acquired by whole-body PET/CT and subsequently by dbPET. The reconstructed images were visually evaluated and the coefficient of variation and uniformity of the background (CV_background and SD_ΔSUVmean), percentages of contrast and background variability (%Q_H,5mm and %N_5mm), and their ratio (%Q_H,5mm/N_5mm), and relative recovery coefficient were compared with the standards defined in the protocol for whole-body PET/CT.

RESULTS

The parameters were calculated at an SBR of 8:1, which was the only SBR in which a 5-mm sphere was visible on both devices. The standards were defined as < 10% for CV_background, ≤ 0.025 for SD_ΔSUVmean, < 5.6% for %N_5mm, > 2.8 for %Q_H,5mm/N_5mm, and > 0.38 for the relative recovery coefficient of the smallest sphere (10 mm in diameter) in the protocol for whole-body PET/CT (the %Q_H,5mm was not determined for that protocol); the respective values were 6.14%, 0.024, 4.55%, 3.66, and 0.33 for dbPET and 2.21%, 0.021, 3.11%, 1.72, and 0.18 for PET/CT. The Q_H,5mm was 16.67% for dbPET and 5.34% for PET/CT. The human images also showed higher lesion-to-background contrast on dbPET than on PET/CT despite the noisier background observed with dbPET.

CONCLUSION

The common phantom study showed that the background was noisier and that the contrast was much higher in the dbPET image than in the PET/CT image. The acquisition protocol and standards for dbPET will need to be different from those used for whole-body PET/CT.

P737Endothelial ERK2/thromboxane receptor pathway induces endothelial dysfunction, insulin resistance and steatohepatosis through superoxide with high fat high sucrose diet

Introduction

Metabolic syndrome (MetS) is well known as the risk of cardiovascular diseases associated with endothelial dysfunction and induces steatohepatosis. Insulin resistance is a major character of MetS, which affects intracellular signaling pathways and endothelial function. Extracellular signal-regulated kinase (ERK) is a major component of insulin signal and many of vasoactive peptides, which were released in MetS, can activate it in endothelium. However, the role of endothelial ERK in nitric oxide (NO) bioactivity in MetS in in vivo has been unknown.

Purpose

The aim of this study is to clarify the role of endothelial ERK2 on NO bioactivity in mice model of MetS.

Methods and results

We created endothelial specific ERK2 knock out mice (EE2KO) crossing Tie2-Cre mice and ERK2 flox mice and fed them with normal or high-fat/high-sucrose diet (HFHSD) for 24 weeks. Serum glucose and insulin levels and HOMA-IR were lowered in EE2KO with HFHSD without changing body weight. In wild type mice (WT) with HFHSD, nonalcoholic fatty liver disease (NAFLD) activity score, fibrosis score and serum ALT level were increased, all of which were blunted in EE2KO. EE2KO with HFHSD lowered systolic blood pressure (WT: 123.7±5.83 mmHg, EE2KO: 101.4±3.66 mmHg, P<0.01, N=8) without changing heart rate, which was increased to the same levels with L-NAME, an endothelial NO synthase inhibitor, in both groups. Serum NO levels measured with serum nitrite/nitrate concentrations were increased in EE2KO with HFHSD (WT: 23.10±3.74 μmol/l, EE2KO: 41.71±6.73 μmol/l, P<0.05, N=12). Endothelial function was assessed with the isometric tension measurement of aortic rings with acetylcholine (ACh). ACh-induced relaxation was improved in EE2KO with HFHSD. Superoxide production of aorta from EE2KO was lowered than WT with HFHSD in dihydroethidium (DHE) staining. S18886, an antagonist of the thromboxane A2-prostanoid (TP) receptor, decreased superoxide production of aorta in DHE staining resulting in improving endothelial function in the isometric tension measurement of aortic rings. Oral administrations of S18886 decreased systolic blood pressure, serum fasting glucose and insulin levels, and surprisingly improved steatohepatosis by decreasing NAFLD activity score and fibrosis score.

Relaxation of aortic rings with ACh

Conclusions

Endothelial ERK2/TP receptor pathway increases superoxide production and decreased NO bioactivity, resulting in deteriorating endothelial function, insulin resistance and steatohepatosis, which were improved by antagonist of the TP receptor in mice model of MetS. The present study indicates that ERK2/TP pathway could be a therapeutic target for complications of MetS.

Routine Referral by Urologists Increase Opportunities for Corneal Donation

BACKGROUND

The levels of corneal donation are insufficient to meet the demand for corneal transplantation in Japan. To overcome this problem, we started to routinely mention the possibility of corneal donation to the families of patients who died in our hospital's Urology Department in February 2008. In this study, we evaluated the effectiveness of this approach.

METHODS

We retrospectively reviewed the medical records of the patients who died in the Department of Urology, St. Marianna University School of Medicine Hospital, and analyzed the patients' characteristics and information about corneal donation.

RESULTS

In total, 211 patients died in our department between February 2008 and March 2017, and 155 patients were medically suitable corneal donors. We mentioned the possibility of corneal donation to 129 (83.2%) families, and 29 (18.7%) families agreed. Three families subsequently withdrew their consent. Finally, 26 (16.8%) of the families that were approached about corneal donation by urologists agreed to donate their relatives' corneas. Another 2 families voluntarily offered to donate their relatives' corneas. Thus, 28 (18.1%) of 155 medically suitable donors donated their corneas for transplantation. Twenty-six (92.8%) donors were 60 years or older and all donors were affected with malignant genitourinary tumors. Fifty-four (96.4%) corneas were successfully transplanted into recipients.

CONCLUSIONS

Even elderly patients who die of solid carcinoma can be an important source of corneal donors. In this study, we showed that routine referral by urologists increased corneal donation. If this approach were adopted by other departments, it might further increase the number of corneal donations.

Prognostic value of preoperative fluorodeoxyglucose positron emission tomography/computed tomography in patients with potentially resectable pancreatic cancer

PURPOSE

To evaluate the prognostic value of preoperative 18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with potentially resectable pancreatic cancer.

METHODS

The study included 103 consecutive patients with potentially resectable pancreatic cancer who underwent preoperative FDG-PET/CT. Age, sex, blood glucose level, tumor marker levels (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9)), PET-related parameters (maximum standardized uptake value (SUVmax)), and contrast-enhanced CT-related factors (tumor size, location, enhancement pattern, and CT-based T and N factors by tumor nodes metastasis (TNM) classification) were assessed for their ability to independently predict postoperative tumor recurrence using Cox proportional hazards model.

RESULTS

Median follow-up was 23.1 months. Univariate analyses revealed that SUVmax (P = 0.0004), tumor size (P = 0.0002), T factor (P = 0.0102), N factor (P = 0.0049), and CA19-9 levels (P = 0.0059) were significantly associated with disease-free survival (DFS). In multivariate analysis, SUVmax (P = 0.0163) and CA19-9 levels (P = 0.0364) independently predicted DFS. Kaplan-Meier analysis revealed that patients with low (< 2.5) SUVmax had a significantly better prognosis than those with higher SUVmax (P = 0.0006). The DFS in patients with SUVmax < 2.5 (n = 23) and SUVmax ≥ 2.5 (n = 80) was 61.9% and 9.7%, respectively, 3 years postoperatively.

CONCLUSIONS

SUVmax can predict DFS in patients with resectable pancreatic cancer. A SUVmax < 2.5 heralds a better prognosis.

A case of refractory lupus nephritis complicated by psoriasis vulgaris that was controlled with secukinumab

It has been reported that T helper 17 cells are involved in the pathogenesis of systemic lupus erythematosus, but there is no report on interleukin-17-targeted therapy. We report a case of a 62-year-old female who presented with psoriasis vulgaris and refractory lupus nephritis. Because her conditions were resistant to conventional treatment, and flow cytometry confirmed the proliferation of activated T helper 17 cells in peripheral blood, and examination of a renal biopsy tissue sample confirmed infiltration of numerous interleukin-17-positive lymphocytes to the renal interstitium, administration of the anti-interleukin-17A antibody secukinumab was initiated. After starting secukinumab the clinical and biological features were improved.

Pretreatment 18F-fluorodeoxyglucose Uptake in the Lung Parenchyma Predicts Poor Survival After Stereotactic Body Radiation Therapy in Patients With Stage I Non-Small Cell Lung Cancer

PURPOSE

In this study, we aimed to evaluate the prognostic value of fluorodeoxyglucose uptake in the lung parenchyma and the presence of subclinical interstitial lung disease on computed tomography as predictive factors for survival following stereotactic body radiation therapy in patients with stage I non-small cell lung cancer.

METHODS

We retrospectively evaluated 125 patients with stage I non-small cell lung cancer who underwent stereotactic body radiation therapy at our institute between December 2005 and March 2013 for various demographic and clinical parameters. The fluorodeoxyglucose uptake in the lung parenchyma corrected with computed tomography value (tissue fraction-corrected standardized uptake value) was quantified using fluorodeoxyglucose-positron emission tomography/computed tomography before the therapy. Additionally, the radiological findings of interstitial lung disease on computed tomography were evaluated. The prognostic analyses were performed using the Kaplan-Meier analysis and Cox proportional hazards regression model for univariate and multivariate analyses.

RESULTS

The median follow-up period was 39 months. The 3-year overall survival rate was 67.9%, and the 3-year progression-free survival rate was 52.0%. The multivariate analysis indicated that the tissue fraction-corrected standardized uptake value was correlated with the patients' overall survival ( P = .027, hazard ratio: 2.694, 95% confidence interval: 1.109-8.057). The presence of subclinical interstitial lung disease showed no correlation with the overall survival ( P = .535, hazard ratio: 1.256, 95% confidence interval: 0.592-2.473).

CONCLUSION

The results indicated that fluorodeoxyglucose uptake in the lung parenchyma, expressed as the tissue fraction-corrected standardized uptake value, was an independent prognostic factor in patients with stage I non-small cell lung cancer who have received stereotactic body radiation therapy.

18F-FDG-PET/CT is effective in distinguishing myelofibrosis due to bone marrow infiltration of diffuse large B-cell lymphoma from triple-negative primary myelofibrosis

Although myelofibrosis is mainly associated with myeloproliferative neoplasms (MPN), especially primary myelofibrosis (PMF), a variety of hematological malignancies, including acute myeloid leukemia, multiple myeloma and malignant lymphoma, also cause myelofibrosis with markedly varying degrees of severity. Thus, it is extremely important to accurately diagnose the underlying diseases that cause fibrosis in bone marrow. Analyses of JAK2, MPL and calreticulin gene mutations are useful for distinguishing MPN from other diseases, since 90% of MPN patients have a mutation in one of these genes. However, 10% of PMF patients do not have mutations in any of these genes, and these patients have a disease known as triple negative PMF. It is sometimes difficult to accurately distinguish triple negative PMF from secondary myelofibrosis caused by other diseases. Herein, we present a case of diffuse large B cell lymphoma (DLBCL) with bone marrow involvement, mimicking triple negative primary myelofibrosis. 18F-FDG-PET was useful for correctly diagnosing DLBCL.

Acute Electrolyte Disturbances in Coronary Sinus during Left Coronary Arteriography in Man

Electrolyte disturbances, particularly reduction of ionized calcium, induced by iodinated contrast media (CM) are important considerations in coronary arteriography. A study was conducted in 24 patients to evaluate the acute electrolyte alterations in the coronary sinus during left coronary arteriography. During left coronary arteriography, coronary sinus blood was withdrawn for measurement of electrolytes. The CM used were diatrizoate, ioxaglate, iohexol, and iopamidol. The hematocrit was decreased moderately by all 4 CM used at 5 s and returned to the control level at 15 s. The level of ionized calcium was decreased by all CM at 5 s. Prolonged reduction of ionic calcium was observed with diatrizoate and ioxaglate at 15 s. The level of potassium was almost unchanged by diatrizoate and ioxaglate in spite of hemodilution, which may lead us to a hypothesis that potassium can be released from the intracellular spaces such as red blood cells and vascular endothelial cells. Thus the depression of left ventricular function might be caused not only by reduction of ionized calcium, but also by a relative increase in the level of serum potassium.

Age-related decline of cerebral oxygen metabolism in normal population detected with positron emission tomography

Using positron emission tomography (PET), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured in 32 healthy volunteers aged from 27 to 67 years. In bilateral putamen, left supratemporal, left infrafrontal and left parietal cortices, CMRO2 showed a significant decline during aging. The age-related decline of CBF was seen only at the left superior temporal cortex. The mean CMRO2 was significantly lower in the elder group (over 51 years old) than in the younger group (under 50 years old), whereas no significant difference in mean CBF between the two groups. The poor correlation of CBF to the age could be explained partly by the fact that CBF is easily influenced by the physiological, psychological and/or environmental factors. The age-related changes of CMRO2 were more marked in the association cortices of the left hemisphere than in that of the right hemisphere.

Genome-wide association study identifies a potent locus associated with human opioid sensitivity

Opioids, such as morphine and fentanyl, are widely used as effective analgesics for the treatment of acute and chronic pain. In addition, the opioid system has a key role in the rewarding effects of morphine, ethanol, cocaine and various other drugs. Although opioid sensitivity is well known to vary widely among individual subjects, several candidate genetic polymorphisms reported so far are not sufficient for fully understanding the wide range of interindividual differences in human opioid sensitivity. By conducting a multistage genome-wide association study (GWAS) in healthy subjects, we found that genetic polymorphisms within a linkage disequilibrium block that spans 2q33.3-2q34 were strongly associated with the requirements for postoperative opioid analgesics after painful cosmetic surgery. The C allele of the best candidate single-nucleotide polymorphism (SNP), rs2952768, was associated with more analgesic requirements, and consistent results were obtained in patients who underwent abdominal surgery. In addition, carriers of the C allele in this SNP exhibited less vulnerability to severe drug dependence in patients with methamphetamine dependence, alcohol dependence, and eating disorders and a lower 'Reward Dependence' score on a personality questionnaire in healthy subjects. Furthermore, the C/C genotype of this SNP was significantly associated with the elevated expression of a neighboring gene, CREB1. These results show that SNPs in this locus are the most potent genetic factors associated with human opioid sensitivity known to date, affecting both the efficacy of opioid analgesics and liability to severe substance dependence. Our findings provide valuable information for the personalized treatment of pain and drug dependence.

Development of Interferon Suppositories. I. Enhanced Rectal Absorption of Human Fibroblast Interferon by Fusogenic Lipid via Lymphotropic Delivery in Rats

We attempted to enhance the rectal absorption of human fibroblast interferon (HuIFN-β) in rats by the administration of suppositories containing fusogenic lipid and a nontoxic surfactant. Suppositories containing either the lipid (linoleic acid) or the surfactant [HCO60; polyoxyethylated (60 mol) hydrogenated castor oil] alone failed to enhance the absorption of HuIFN-β. However, suppositories containing both linoleic acid and HCO60 facilitated the rectal absorption of HuIFN-β. The absorbed HuIFN-β was selectively delivered via the lymph.

Effect of salicylate on the uptake of cefmetazole into brain of mice

Cefmetazole distribution into mice cerebral cortex was minimal when the drug was administered alone. However, the co-administration of salicylate or diethyl maleate enhanced cefmetazole uptake into the cerebral cortex, while it decreased the level of reduced nonprotein sulfhydryls in cerebral cortex. The enhanced cerebral uptake of cefmetazole was suppressed by the simultaneous administration of cysteamine with a concomitant recovery of the reduced nonprotein sulfhydryl concentration in cerebral cortex.

Potentiation of enteral absorption of human interferon alpha and selective transfer into lymphatics in rats

Enhancement of human leucocyte interferon (HuIFN-α) absorption from rat large intestine was studied with the aid of lipid, surfactant and lipid-surfactant mixed micelles. Neither the emulsified lipid (linoleic acid) nor the surfactant (HCO60, polyoxyethylated [60 moles] hydrogenated castor oil) alone were able to enhance the absorption of HuIFN-α. However, linoleic acid-HCO60 mixed micelles enhanced the absorption of HuIFN-α from the large intestine. Highly selective delivery of HuIFN-α into the lymphatics compared to the blood was also observed.

Volume-based parameters measured by using FDG PET/CT in patients with stage I NSCLC treated with stereotactic body radiation therapy: prognostic value

PURPOSE

To evaluate the prognostic importance and predictive performance of volume-based parameters of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with stage I non-small cell lung cancer (NSCLC) after stereotactic body radiation therapy (SBRT).

MATERIALS AND METHODS

This study had institutional review board approval. All patients gave written informed consent for SBRT as well as for future anonymous use of clinical data. Data in 88 patients with stage I NSCLC (68 patients with T1N0M0 disease and 20 with T2aN0M0 disease) who had undergone FDG PET/CT and then SBRT were retrospectively evaluated. Seventy-seven tumors were histopathologically proved (48 adenocarcinomas, 24 squamous cell carcinomas, and five unspecified non-small cell carcinomas), and the remaining 11 tumors were diagnosed clinically without histopathologic diagnosis. Maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were analyzed. The MTV of the primary tumor was calculated as all voxels with an SUV of 2.5 or greater within the isocontour line, while TLG was calculated as MTV multiplied by the average SUV, by using fixed thresholds of either 50% (TLG50) or 60% (TLG60) of the maximum intratumoral FDG activity. The prognostic importance of PET parameters and other clinicopathologic variables (age, sex, tumor size, tumor location [peripheral or central], and biologically effective dose) was assessed by using Cox proportional hazards regression analysis of overall survival (OS) and disease-free survival (DFS) for both univariate and multiple-variable analyses.

RESULTS

The median follow-up period was 33 months. At 3 years, OS and DFS were 70.0% and 49.7%, respectively. In the univariate analyses, SUVmax (P = .001), MTV (P = .002), TLG50 (P = .001), and TLG60 (P < .001) were found to be significantly associated with DFS. In multiple variable analysis, these parameters were also significantly associated with DFS (P = .011 for SUVmax, P = .010 for MTV, P = .004 for TLG50, and P = .005 for TLG60). Only volumetric parameters (MTV, TLG50, and TLG60) were significant indicators of DFS in patients with tumors larger than 3 cm.

CONCLUSION

SUVmax, MTV, and TLG at FDG PET/CT have a prognostic role for patients with NSCLC treated with SBRT. When tumors are larger than 3 cm, only MTV and TLG are predictive of DFS.

Streamline phenomena in liver metastasis of gastrointestinal tumors - a clinical-study based upon 172 patients

Location and number of liver metastasis of gastrointestinal tumors were detected preoperatively and intraoperatively. The distribution of the liver segment(s) occupied by metastatic tumors varied significantly (p<0.05). Significantly more frequent distributions were demonstrated in the lateral segment with gastric cancer (p<0.05), in the posterior segment with left colic cancer (p<0.001), in the medial segment with rectal cancer (p<0.01), in the anterior segment with bile duct cancer (p<0.05) and the whole of the liver with pancreatic cancer (p<0.05). Significantly less frequent distribution was demonstrated in the posterior segment with gastric cancer (p<0.01). When the liver was divided into the right and the left halves, the distribution of each half of the liver occupied by metastatic tumors varied significantly (p<0.05). Liver metastases of whole colic cancer were significantly more frequent in the right half of the liver (p<0.05). The results suggest that the tumor distribution in liver metastases of gastrointestinal tumors differ depending upon the primary tumors, basically in accordance with the 'streamline' phenomena.

[Thoracic surgery for patients with bronchial asthma]

Thoracic surgery poses a risk for complications in the respiratory system. In particular, for patients with bronchial asthma, we need to care for perioperative complications because it is well known that these patients frequently have respiratory complications after surgery, and they may have bronchial spasms during surgery. If we can get good control of their bronchial asthma, we can usually perform surgery for these patients without limitations. For safe postoperative care, it is desirable that these patients have stable asthma conditions that are well-controlled before surgery, as thoracic surgery requires intrabronchial intubation for anesthesia and sometimes bronchial resection. These stimulations to the bronchus do not provide for good conditions because of the risk of bronchial spasm. Therefore, we should use the same agents that are used to control bronchial asthma if it is already well controlled. If it is not, we have to administer a β₂ stimulator, aminophylline, or steroidal agents for good control. Isoflurane or sevoflurane are effective for the safe control of anesthesia during surgery, and we should use a β₂ stimulator, with or without inhalation, or steroidal agents after surgery. It is important to understand that we can perform thoracic surgery for asthma patients if we can provide perioperative control of bronchial asthma, although these patients still have severe risks.

Impairment of heme biosynthesis induces short circadian period in body temperature rhythms in mice

It has been demonstrated that the function of mammalian clock gene transcripts is controlled by the binding of heme in vitro. To examine the effects of heme on biological rhythms in vivo, we measured locomotor activity (LA) and core body temperature (Tb) in a mouse model of porphyria with impaired heme biosynthesis by feeding mice a griseofulvin (GF)-containing diet. Mice fed with a 2.0% GF-containing diet (GF2.0) transiently exhibited phase advance or phase advance-like phenomenon by 1–3 h in terms of the biological rhythms of Tbor LA, respectively (both, P < 0.05) while mice were kept under conditions of a light/dark cycle (12 h:12 h). We also observed a transient, ∼0.3 h shortening of the period of circadian Tbrhythms in mice kept under conditions of constant darkness ( P < 0.01). Interestingly, the observed duration of abnormal circadian rhythms in GF2.0 mice lasted between 1 and 3 wk after the onset of GF ingestion; this finding correlated well with the extent of impairment of heme biosynthesis. When we examined the effects of therapeutic agents for acute porphyria, heme, and hypertonic glucose on the pathological status of GF2.0 mice, it was found that the intraperitoneal administration of heme (10 mg·kg−1·day−1) or glucose (9 g·kg−1·day−1) for 7 days partially reversed (50%) increases in urinary δ-aminolevulinic acids levels associated with acute porphyria. Treatment with heme, but not with glucose, suppressed the phase advance (-like phenomenon) in the diurnal rhythms ( P < 0.05) and restored the decrease of heme ( P < 0.01) in GF2.0 mice. These results suggest that impairments of heme biosynthesis, in particular a decrease in heme, may affect phase and period of circadian rhythms in animals.

Value of dual time point F-18 FDG-PET/CT imaging for the evaluation of prognosis and risk factors for recurrence in patients with stage I non-small cell lung cancer treated with stereotactic body radiation therapy

PURPOSE

To investigate prognostic and risk factors for recurrence after stereotactic body radiation therapy (SBRT) in patients with stage I non-small cell lung carcinoma (NSCLC), focusing on dual time point [18]F-fluorodeoxyglucose positron emission tomography (FDG PET).

MATERIALS AND METHODS

We prospectively evaluated 57 patients with stage I NSCLC (45 T1N0M0 and 12 T2N0M0) who had undergone pretreatment FDG-PET/CT and were subsequently treated with SBRT. All patients received a whole-body PET/CT scan at 60 min and a whole-lung at 120 min after the injection. The maximum standardized uptake value (SUV) and retention index (RI) of the lesions were calculated. Local recurrence, regional lymph node metastasis, distant metastasis, and the recurrence pattern were evaluated. Cox proportional hazard regression analyses were performed to evaluate prognostic factors or risk factors of recurrence.

RESULTS

During the median follow-up period of 27 months, local recurrence, regional lymph node metastasis, and distant metastasis were seen in 17 (30%), 12 (21%), and 17 (30%) of the 57 patients, respectively. The 3-year overall survival rate was 63.4%. SUVmax did not affect any recurrence, DFS, OS, or CSS. RI significantly predicted higher distant metastasis (HR 47.546, p=0.026). In contrast, RI tended to predict lower local recurrence (HR 0.175, p=0.246) and regional lymph node metastasis (HR 0.109, p=0.115).

CONCLUSIONS

SUVmax at staging FDG-PET does not predict any recurrence, DFS, OS or CSS. In contrast, higher RI predicts higher distant metastasis and tended to predict lower local or regional lymph node metastasis.