Dose Calculation Accuracy of Beam Models in RadCalc for a 1.5 T MR-Linac

The purpose of this study is to evaluate RadCalc, an independent dose verification software, for patient-specific quality assurance (PSQA) in online adaptive planning with a magnetic resonance linear accelerator (MR-linac) of a 1.5 T. Version 7.1.4 of RadCalc to introduce the capability to establish a beam model that incorporates MR field characteristics. A total of six models were established, with one using manufacturer-provided data and the others differing in percentage depth dose (PDD) data sources. Overall, two models utilized PDD data from the treatment planning system (TPS), and three used commissioned PDD data from gantry angles of 0° and 270°. Simple tests on a virtual water phantom assessed dose-calculation accuracy, revealing percentage differences ranging from -0.5% to -20.6%. Excluding models with significant differences, clinical tests on 575 adaptive plans (prostate, liver, and breast) showed percentage differences of -0.51%, 1.12%, and 4.10%, respectively. The doses calculated using RadCalc demonstrated similar trends to those of the PSQA-based measurements. The newly released version of RadCalc enables beam modeling that considers the characteristics of the 1.5 T magnetic field. The accuracy of the software in calculating doses at 1.5 T magnetic fields has been verified, thereby making it a reliable and effective tool for PSQA in adaptive plans.

Optimal planning target margin for prostate radiotherapy based on interfractional and intrafractional variability assessment during 1.5T MRI-guided radiotherapy

Introduction

We analyzed daily pre-treatment- (PRE) and real-time motion monitoring- (MM) MRI scans of patients receiving definitive prostate radiotherapy (RT) with 1.5 T MRI guidance to assess interfractional and intrafractional variability of the prostate and suggest optimal planning target volume (PTV) margin.

Materials and methods

Rigid registration between PRE-MRI and planning CT images based on the pelvic bone and prostate anatomy were performed. Interfractional setup margin (SM) and interobserver variability (IO) were assessed by comparing the centroid values of prostate contours delineated on PRE-MRIs. MM-MRIs were used for internal margin (IM) assessment, and PTV margin was calculated using the van Herk formula.

Results

We delineated 400 prostate contours on PRE-MRI images. SM was 0.57 ± 0.42, 2.45 ± 1.98, and 2.28 ± 2.08 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively, after bone localization and 0.76 ± 0.57, 1.89 ± 1.60, and 2.02 ± 1.79 mm in the LR, AP, and SI directions, respectively, after prostate localization. IO was 1.06 ± 0.58, 2.32 ± 1.08, and 3.30 ± 1.85 mm in the LR, AP, and SI directions, respectively, after bone localization and 1.11 ± 0.55, 2.13 ± 1.07, and 3.53 ± 1.65 mm in the LR, AP, and SI directions, respectively, after prostate localization. Average IM was 2.12 ± 0.86, 2.24 ± 1.07, and 2.84 ± 0.88 mm in the LR, AP, and SI directions, respectively. Calculated PTV margin was 2.21, 5.16, and 5.40 mm in the LR, AP, and SI directions, respectively.

Conclusions

Movements in the SI direction were the largest source of variability in definitive prostate RT, and interobserver variability was a non-negligible source of margin. The optimal PTV margin should also consider the internal margin.

Optimal Planning Target Margin for Prostate Radiotherapy Based on Interfractional and Intrafractional Variability Assessment during 1.5T MR-Guided Radiotherapy

PURPOSE/OBJECTIVE(S)

MR-guided radiotherapy (MRgRT) provides superior soft-tissue contrast over CT-based image guidance. We collected and analyzed daily pre-treatment (PRE) and real-time motion-monitoring (MM) MR images of patients receiving prostate radiotherapy to assess interfractional and intrafractional variability of prostate using two localization methods: pelvic bony anatomy (bone) and prostate during online adaptive radiotherapy (ART).

MATERIALS/METHODS

PRE and MM MRIs for the first five fractions of twenty prostate cancer patients who received definitive MRgRT with 1.5T MRI were collected. Using MIM software, rigid registration between PRE MRI and planning CT images based on pelvic bony anatomy and prostate reproduced bone localization and online ART, respectively. To determine interfractional setup margin (SM), prostate was delineated on all PRE MRIs registered after bone and prostate localizations by a radiation oncologist, and centroid values of prostate contours between planning CT and PRE MRIs were compared. To determine interobserver variability, another radiation oncologist, a medical physicist, and a radiotherapist contoured prostate for both localization methods. For internal margin (IM) assessment, we used MM MRIs of the five patients who had all three sets of coronal, sagittal, and axial cine images and determined the maximum contour displacement using in-house MATLAB-based software converting binary image files to 2D cine images with a superimposed grid of 1 mm spacing.

RESULTS

A total of 100 PRE and 25 MM MRIs were analyzed. Four hundred prostate contours were delineated on MR images registered with planning CT based on both bony anatomy and prostate. After bone localization, SM was 0.57±0.42 mm in left-right (LR), 2.45±1.98 mm in anterior-posterior (AP), and 2.28±2.08 mm in superior-inferior (SI) directions, and IO was 1.06±0.58 mm in LR, 2.32±1.08 mm in AP, and 3.30±1.85 mm in SI directions. After prostate localization, SM was 0.76±0.57 mm in LR, 1.89±1.60 mm in AP, and 2.2±1.79 mm in SI directions, and IO was 1.11±0.55 mm in LR, 2.13±1.07 mm in AP, and 3.53±1.65 mm in SI directions. Average IM was 2.12±0.86 mm, 2.24±1.07 mm, and 2.84±0.88 mm in LR, AP, and SI directions, respectively.

CONCLUSION

Using daily MRIs from MRgRT, we showed that movements in the SI direction were the largest source of variability in prostate definitive RT. In addition, interobserver variability was a non-negligible source of margin. Optimal PTV margin should also consider internal margin, especially in the SI direction.

Randomized evaluation of an online single-session intervention for minority stress in LGBTQ+ adolescents

Background

LGBTQ+ youth face myriad adverse health outcomes due to minority stress, creating a need for accessible, mechanism-targeted interventions to mitigate these minority stress-related risk factors. We tested the effectiveness and acceptability of Project RISE, an online single-session intervention designed to ameliorate internalized stigma and improve other outcomes among LGBTQ+ youth. We hypothesized that youth assigned to RISE (versus a control) would report significantly reduced internalized stigma and increased identity pride at post-intervention and at two-week follow-up and would find RISE acceptable.

Methods

We recruited adolescents nationally through Instagram advertisements in May 2022 (N = 538; M age = 15.06, SD age = 0.97). Participants were randomly assigned to RISE or an information-only control and completed questionnaires pre-intervention, immediately post-intervention, and two weeks post-intervention. Inclusion criteria included endorsing: (1) LGBTQ+ identity, (2) age 13-16, (3) English fluency (4) Internet access, and (5) subjective negative impact of LGBTQ+ stigma.

Results

Relative to participants in the control condition, participants who completed RISE reported significant decreases in internalized stigma (d = -0.49) and increases in identity pride (d = 0.25) from pre- to immediately post-intervention, along with decreased internalized stigma (d = -0.26) from baseline to two-week follow-up. Participants rated both RISE and the information-only control as highly, equivalently acceptable.

Conclusions

RISE appears to be an acceptable and useful online SSI for LGBTQ+ adolescents, with potential to reduce internalized stigma in both the short- and longer-term. Future directions include evaluating effects of Project RISE over longer follow-ups and in conjunction with other mental health supports.

Understanding patient-level costs of weekly isoniazid-rifapentine (3HP) among people living with HIV in Uganda

BACKGROUND: Twelve weeks of weekly isoniazid and rifapentine (3HP) prevents TB disease among people with HIV (PWH), but the costs to people of taking TB preventive treatment is not well described.METHODS: We surveyed PWH who initiated 3HP at a large urban HIV/AIDS clinic in Kampala, Uganda, as part of a larger trial. We estimated the cost of one 3HP visit from the patient perspective, including both out-of-pocket costs and estimated lost wages. Costs were reported in 2021 Ugandan shillings (UGX) and US dollars (USD; USD1 = UGX3,587)RESULTS: The survey included 1,655 PWH. The median participant cost of one clinic visit was UGX19,200 (USD5.36), or 38.5% of the median weekly income. Per visit, the cost of transportation was the largest component (median: UGX10,000/USD2.79), followed by lost income (median: UGX4,200/USD1.16) and food (median: UGX2,000/USD0.56). Men reported greater income loss than women (median: UGX6,400/USD1.79 vs. UGX3,300/USD0.93), and participants who lived further than a 30-minute drive to the clinic had higher transportation costs than others (median: UGX14,000/USD3.90 vs. UGX8,000/USD2.23).CONCLUSION: Patient-level costs to receive 3HP accounted for over one-third of weekly income. Patient-centered approaches to averting or defraying these costs are needed.

Risk of stroke with antivenom usage after venomous snakebite in Taiwan: a population-based cohort study

BACKGROUND AND PURPOSE

Stroke is a rare complication of snakebites, but may lead to serious sequelae. We aimed to explore the relationship between venomous snakebite and the risk for acute stroke, in a nationwide population-based cohort study.

METHODS

This retrospective cohort study used claims data between 1 January 2000 and 31 December 2012, from the Taiwan National Health Insurance Research Database. The study included data of patients aged 18 years or older with venomous snakebite (n = 535), matched for propensity score with controls without venomous snakebite (n = 2140). The follow-up period was the duration from the initial diagnosis of venomous snakebite and administration of antivenom to the date of an acute stroke, or until 31 December 2013. The competing risk model was used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of stroke, ischemic stroke and hemorrhagic stroke, after adjusting for demographic and other possible stroke risk factors.

RESULTS

The adjusted HR for the venomous snakebite group compared with the control group was 2.68 for hemorrhagic stroke (95% CI = 1.35-5.33). Stratified analysis showed that the older age group (>65 years old) had a higher risk of hemorrhagic stroke. A 2.72-fold significant increase in the risk for hemorrhagic stroke was observed following venomous snakebite with antivenom usage (95% CI = 1.41-5.26).

CONCLUSION

Venomous snakebite is associated with an increased risk of hemorrhagic stroke after the use of antivenom. Further study of the underlying mechanism is warranted.

Impact of Denoising on Deep-Learning-Based Automatic Segmentation Framework for Breast Cancer Radiotherapy Planning

Objective: This study aimed to investigate the segmentation accuracy of organs at risk (OARs) when denoised computed tomography (CT) images are used as input data for a deep-learning-based auto-segmentation framework. Methods: We used non-contrast enhanced planning CT scans from 40 patients with breast cancer. The heart, lungs, esophagus, spinal cord, and liver were manually delineated by two experienced radiation oncologists in a double-blind manner. The denoised CT images were used as input data for the AccuContourTM segmentation software to increase the signal difference between structures of interest and unwanted noise in non-contrast CT. The accuracy of the segmentation was assessed using the Dice similarity coefficient (DSC), and the results were compared with those of conventional deep-learning-based auto-segmentation without denoising. Results: The average DSC outcomes were higher than 0.80 for all OARs except for the esophagus. AccuContourTM-based and denoising-based auto-segmentation demonstrated comparable performance for the lungs and spinal cord but showed limited performance for the esophagus. Denoising-based auto-segmentation for the liver was minimal but had statistically significantly better DSC than AccuContourTM-based auto-segmentation (p < 0.05). Conclusions: Denoising-based auto-segmentation demonstrated satisfactory performance in automatic liver segmentation from non-contrast enhanced CT scans. Further external validation studies with larger cohorts are needed to verify the usefulness of denoising-based auto-segmentation.

The impact of nonoptimal lipids on the progression of coronary artery calcification in asymptomatic young adults: results from the KOICA registry

Funding Acknowledgements

Type of funding sources: None.

Background

Recently, as cumulative exposure of lipids for a lifetime has become important to prevent and predict atherosclerotic cardiovascular disease (ASCVD), it is recommended to obtain the optimal lipid levels from a young age. However, questions remain regarding the vascular changes in young adulthood by nonoptimal lipid levels.

Purpose

We aimed to investigate the progression of coronary artery calcification (CAC) according to lipid profiles in Korean young adults.

Methods

From the KOrea Initiative on Coronary Artery calcification registry, we collected 2,940 statin-naïve adults under 45-year-old, undergoing serial coronary artery calcium scans for the purpose of routine health check-ups between 2002 and 2017. CAC progression was assessed according to the optimality of lipid levels and each lipid variable.

Results

In this cohort (mean age, 41.3 years; man 82.4%), only 477 subjects (16.2%) had the optimal lipid profile, defined as triglycerides &lt;150 mg/dl, LDL cholesterol &lt;100 mg/dl, and HDL cholesterol ≥45 mg/dl. During follow-up (median 39.7 months), CAC progression was observed in 438 participants (14.8%) and more frequent in nonoptimal lipid group (16.5% vs 5.9%; p&lt;0.001). Nonoptimal lipid levels during young adulthood increased the risk of CAC progression after adjusting for other cardiovascular risk factors (adjusted HR, 2.36; p=0.001), with a stepwise risk increase according to lipid levels. In particular, in the subjects with an initial calcium score of zero (adjusted HR, 2.13; p=0.014), those in their 20s or 30s (adjusted HR 2.70; p=0.029), and those without any other risk factors (adjusted HR 2.51; p=0.025), deemed as very low-risk groups, nonoptimal lipid levels more than doubled the risk of CAC progression, respectively. Among lipid variables, high triglycerides appeared to provide the greatest impact on CAC progression of young adults.

Conclusions

The proportion of young adults with optimal lipid levels was lower than expected. Nonoptimal lipid level was significantly associated with the risk of CAC progression in young adults, even with low-risk. Triglycerides had the strongest association with the risk of CAC progression. Screening and intervention for nonoptimal lipid levels, particularly triglycerides, from an early age might be of clinical value.

Mutual Information-Based Non-Local Total Variation Denoiser for Low-Dose Cone-Beam Computed Tomography

Conventional non-local total variation (NLTV) approaches use the weight of a non-local means (NLM) filter, which degrades performance in low-dose cone-beam computed tomography (CBCT) images generated with a low milliampere-seconds (mAs) parameter value because a local patch used to determine the pixel weights comprises noisy-damaged pixels that reduce the similarity between corresponding patches. In this paper, we propose a novel type of NLTV based on a combination of mutual information (MI): MI-NLTV. It is based on a statistical measure for a similarity calculation between the corresponding bins of non-local patches vs. a reference patch. The weight is determined in terms of a statistical measure comprising the MI value between corresponding non-local patches and the reference-patch entropy. The MI-NLTV denoising process is applied to CBCT images generated by the analytical reconstruction algorithm using a ray-driven backprojector (RDB). The MI-NLTV objective function is minimized based on the steepest gradient descent optimization to augment the difference between a real structure and noise, cleaning noisy pixels without significant loss of the fine structure and details that remain in the reconstructed images. The proposed method was evaluated using patient data and actual phantom measurement data acquired with lower mAs. The results show that integrating the RDB further enhances the MI-NLTV denoising-based analytical reconstruction algorithm to achieve a higher CBCT image quality when compared with those generated by NLTV denoising-based approach, with an average of 15.97% higher contrast-to-noise ratio, 2.67% lower root mean square error, 0.12% lower spatial non-uniformity, 1.14% higher correlation, and an average of 18.11% higher detectability index. These quantitative results indicate that the incorporation of MI makes the NLTV more stable and robust than the conventional NLM filter for low-dose CBCT imaging. In addition, achieving clinically acceptable CBCT image quality despite low-mAs projection acquisition can reduce the burden on common online CBCT imaging, improving patient safety throughout the course of radiotherapy.

Association of blood pressure classification using the 2017 ACC/AHA guidelines with the progression of coronary artery calcification

Funding Acknowledgements

Type of funding sources: None.

Aims

The recent American College of Cardiology/American Heart Association guidelines reinforced the criteria for diagnosis of hypertension. We assessed the association of this reinforced criteria with coronary artery calcification (CAC) progression in asymptomatic adults according to different age groups.

Methods and results

We included 10,839 asymptomatic Korean adults (23.4% aged ≤45 years) who underwent at least two coronary artery calcium score (CACS) evaluations between 2012 and 2016. All participants were categorised into normal blood pressure (BP) (untreated systolic/diastolic &lt;120/&lt;80 mmHg), elevated BP (untreated systolic/diastolic 120–129/&lt;80 mmHg), stage 1 hypertension (untreated systolic/diastolic BP 130–139/80–89 mmHg), or stage 2 hypertension (systolic/diastolic BP ≥140/≥90 mmHg or taking anti-hypertensive medication) groups. CAC progression was defined as a difference ≥2.5 between the square roots (√) of the baseline and follow-up CACSs (Δ√transformed CACS). During a mean 3.3-year follow-up, the incidence of CAC progression was 13.5% and 36.3% in groups with ≤45 and &gt;45 years, respectively. After multivariable adjustment for sex, diabetes, dyslipidaemia, obesity, current smoking, and baseline CACS, hazard ratios (95% confidence interval) for CAC progression versus normal BP in elevated BP, stage 1 hypertension, and stage 2 hypertension were 1.39 (0.93–2.07)(P = 0.107), 1.59 (1.17–2.17)(P = 0.003), and 2.38 (1.82–3.12)(P &lt;0.001) in the ≤45 years group and 1.13 (0.97–1.32)(P = 0.111), 1.20 (1.06–1.34)(P = 0.003), and 1.72 (1.57–1.87)(P &lt;0.001) in the &gt;45 years group.

Conclusion

Newly defined stage 1 hypertension is independently associated with CAC progression in asymptomatic Korean adults irrespective of different age groups.

Sensitivity of radio-photoluminescence glass dosimeters to accumulated doses

Background

This study investigated the effect of accumulated doses on radio-photoluminescence glass dosimeters (RPLGDs) from measurements involving mega-voltage photons.

Methods

Forty-five commercially available RPLGDs were irradiated to estimate their dose responses. Photon beams of 6, 10, and 15 MV were irradiated onto the RPLGDs inside a phantom, which were divided into five groups with different doses and energies. Groups 1 and 2 were irradiated at 1, 5, 10, 50, and 100 Gy in a sequential manner; Group 3 was irradiated 10 times with a dose of 10 Gy; and Groups 4 and 5 followed the same method as that of Group 3, but with doses of 50 Gy and 100 Gy, respectively. Each device was subjected to a measurement reading procedure each time irradiation.

Results

For the annealed Group 1, RPLGD exhibited a linearity response with variance within 5%. For the non-annealed Group 2, readings demonstrated hyperlinearity at 6 MV and 10 MV, and linearity at 15 MV. Following the 100 Gy irradiation, the readings for Group 2 were 118.7 ± 1.9%, 112.2 ± 2.7%, and 101.5 ± 2.3% at 6, 10, and 15 MV, respectively. For Groups 3, 4, and 5, the responsiveness of the RPLGDs gradually decreased as the number of repeated irradiations increased. The percentage readings for the 10th beam irradiation with respect to the readings for the primary beam irradiation were 84.6 ± 1.9%, 87.5 ± 2.4%, and 93.0 ± 3.0% at 6 MV, 10 MV, and 15 MV, respectively.

Conclusions

The non-annealed RPLGD response to dose was hyperlinear for the 6 MV and 10 MV photon beams but not for the 15 MV photon beam. Additionally, the annealed RPLGD exhibited a fading phenomenon when the measurement was repeated several times and demonstrated a relatively large fading effect at low energies than at high energies.

Development and Validation of a Deep Learning-Based Automatic Brain Segmentation and Classification Algorithm for Alzheimer Disease Using 3D T1-Weighted Volumetric Images

BACKGROUND AND PURPOSE

Limited evidence has suggested that a deep learning automatic brain segmentation and classification method, based on T1-weighted brain MR images, can predict Alzheimer disease. Our aim was to develop and validate a deep learning-based automatic brain segmentation and classification algorithm for the diagnosis of Alzheimer disease using 3D T1-weighted brain MR images.

MATERIALS AND METHODS

A deep learning-based algorithm was developed using a dataset of T1-weighted brain MR images in consecutive patients with Alzheimer disease and mild cognitive impairment. We developed a 2-step algorithm using a convolutional neural network to perform brain parcellation followed by 3 classifier techniques including XGBoost for disease prediction. All classification experiments were performed using 5-fold cross-validation. The diagnostic performance of the XGBoost method was compared with logistic regression and a linear Support Vector Machine by calculating their areas under the curve for differentiating Alzheimer disease from mild cognitive impairment and mild cognitive impairment from healthy controls.

RESULTS

In a total of 4 datasets, 1099, 212, 711, and 705 eligible patients were included. Compared with the linear Support Vector Machine and logistic regression, XGBoost significantly improved the prediction of Alzheimer disease (P < .001). In terms of differentiating Alzheimer disease from mild cognitive impairment, the 3 algorithms resulted in areas under the curve of 0.758-0.825. XGBoost had a sensitivity of 68% and a specificity of 70%. In terms of differentiating mild cognitive impairment from the healthy control group, the 3 algorithms resulted in areas under the curve of 0.668-0.870. XGBoost had a sensitivity of 79% and a specificity of 80%.

CONCLUSIONS

The deep learning-based automatic brain segmentation and classification algorithm allowed an accurate diagnosis of Alzheimer disease using T1-weighted brain MR images. The widespread availability of T1-weighted brain MR imaging suggests that this algorithm is a promising and widely applicable method for predicting Alzheimer disease.

Flexible film dosimeter for in vivo dosimetry

PURPOSE

The aims of this study were to develop a flexible film dosimeter applicable to the irregular surface of a patient for in vivo dosimetry and to evaluate the device's dosimetric characteristics.

METHODS

A flexible film dosimeter with active layers consisting of radiochromic-sensitive films and flexible silicone materials was constructed. The dose-response, sensitivity, scanning orientation dependence, energy dependence, and dose rate dependence of the flexible film dosimeter were tested. Irradiated dosimeters were scanned 24 h post-irradiation, and the region of interest was 5 mm × 5 mm. Biological stability tests ensured the safety of application of the flexible film dosimeter for patients. A preliminary clinical study with the flexible film dosimeter was implemented on four patients.

RESULTS

The red channel demonstrated the highest sensitivity among all channels, and the response sensitivity of the dosimeter decreased with the applied dose, which were the same as the characteristics of GAFCHROMIC EBT3 radiochromic films. The flexible film dosimeter showed no significant energy dependence for photon beams of 6 MV, 6 MV flattening filter-free (FFF), 10 MV, and 15 MV. The flexible film dosimeter showed no substantial dose rate dependence with 6 or 6 MV FFF. In terms of biological stability, the flexible film dosimeter demonstrated no cytotoxicity, no irritation, and no skin sensitization. In the preliminary clinical study, the dose differences between the measurements with the flexible film dosimeter and calculations with the treatment planning system ranged from -0.1% to 1.2% for all patients.

CONCLUSIONS

The dosimeter developed in this study is a flexible film capable of attachment to a curved skin surface. The biological test results indicate the stability of the flexible film dosimeter. The preliminary clinical study showed that the flexible film dosimeter can be successfully applied as an in vivo dosimeter.

Effectiveness of a Fractionated Therapy Scheme in Tumor Treating Fields Therapy

This study aimed to evaluate the biological effectiveness of cancer therapy with tumor treating fields using a fractionated treatment scheme that was originally designed for radiotherapy. Discontinuous fractional tumor treating fields of an intensity of 0.9 to 1.2 V/cm and a frequency of 150 KHz were applied to U373 cancer cells and IEC6 normal cells for 3 days, with durations of 3, 6, 12, or 24 h/d. As the treatment duration of the tumor treating fields increased from 3 to 24 h/d, the relative tumor cell (U373) number (% of control) reduced in proportion to the treatment duration. Compared to a 25% cell number reduction (75% of control) for the group of 6 h/d treatment at 1.2 V/cm, only 5% (70% of control) and 8% (67% of control) of additional reductions were observed for the group of 12 and 24 h/d treatment, respectively. This experimental result indicates that the dependence on treatment duration in tumor cell inhibition was weakened distinctly at treatment duration over 6 h/d. For normal cells (IEC6), the relative cell number corresponding to the treatment time of the tumor treating fields at 1.2 V/cm of electric field strength was not decreased much for the treatment times of 3, 6, and 12 h/d, revealing 93.3%, 90.0%, and 89.3% relative cell numbers, respectively, but it suddenly decreased to ∼73% for the 24 h/d treatment. Our results showed that the effects of tumor treating fields on tumor cells were higher than on normal cells for treatment duration of 3 to 12 h/d, but the difference became minimal for treatment duration of 24 h/d. The fractionated scheme, using tumor treating fields, reduced the treatment time while maintaining efficacy, suggesting that this method may be clinically applicable for cancer treatment.

Medical infrared thermal imaging of canine appendicular bone neoplasia

Background

Medical infrared thermal imaging (MITI) is a noninvasive imaging modality used in veterinary medicine as a screening tool for musculoskeletal and neurological disease processes. An infrared camera measures the surface body heat and produces a color map that represents the heat distribution. Local trauma or disease can impair the autonomic nervous system, which leads to changes in the local dermal microcirculation and subsequent alteration of surface body heat. Disruption of autonomic flow to the cutaneous vasculature at deeper levels can also result in asymmetric thermographic results. The purpose of this study was to evaluate surface temperature differences between limbs affected by bone neoplasia and their normal contralateral limbs.

Results

A statistically significant difference in average temperature was noted between regions of interest of the two groups (paired difference: 0.53 C° ± 0.14; P = 0.0005). In addition, pattern recognition analysis yielded a 75–100% success rate in lesion identification.

Conclusions

Significant alterations noted with average temperature and thermographic patterns indicate that MITI can document discernible changes associated with the presence of canine appendicular bone tumors. While MITI cannot be used as the sole diagnostic tool for bone cancer, it can be used as a screening modality and may be applicable in early detection of cancer.

1423Adherence to triple component antihypertensive regimen is higher in single-pill combination than two-pill regimen: data from a randomized controlled trial using medication event monitoring system

Background

Simplicity of regimen is known to be an important determinant of medication adherence and using single-pill combination (SPC) in hypertension treatment resulted in better adherence and persistence than free-equivalent combination. However, this finding has been studied only in dual-component antihypertensive treatments and in observational studies using medication possession ratio as an index of adherence. Medication event monitoring system (MEMS) is considered to be the gold standard in estimating medication adherence.

Purpose

To investigate the superiority in adherence of triple-component SPC compared to equivalent two-pill regimen using MEMS

Methods

This is a multi-center open-label randomized controlled trial. Inclusion criteria were hypertensive patients whose clinic blood pressure is not adequately controlled (systolic >140 mmHg or diastolic >90 mmHg) with combination antihypertensive regimen comprising two of three classes (angiotensin receptor blocker, calcium channel blocker and thiazide diuretics) for at least 4 weeks. Eligible patients were randomized either to single-pill (triple-component SPC, olmesartan/amlodipine/ hydrochlorothiazide 20/5/12.5 mg) or two-pill (dual-component SPC + one free pill, olmesartan/hydrochlorothiazide 20/12.5 mg + amlodipine 5 mg) groups and maintained for 12 weeks. Medications were dispensed in MEMS. Primary outcomes were the difference of percentage of dose taken (PDT) and percentage of days with prescribed dose taken correctly (PDTc) between single- and two-pill therapy, calculated from MEMS data.

Results

From 8 hospitals, 146 hypertensive patients were randomized into single- and two-pill groups. Final analysis was done in 65 and 66 patients in each group from which adherence index could be obtained. Baseline clinical characteristics of the two groups were not different. The single-pill group had significantly higher PDT and PDTc compared to the two-pill group. (median (25–75 percentile) (%), PDT 95.1 (87.9 - 100.0) vs 91.2 (79.8 - 96.5); PDTc 93.1 (79.8 - 96.5) vs 91.3 (70.7 - 96.4), p = both 0.04, by Wilcoxon rank sum test)

Percent dose taken

Conclusion

Single-pill combination of triple-component antihypertensive regimen showed superior adherence compared to equivalent two-pill therapy. Reducing pill burden by using SPC is a relevant strategy to enhance the adherence to multi-drug antihypertensive therapy.

Acknowledgement/Funding

Daiichi-Sankyo

The recruitment of extra-intestinal cells to the injured mucosa promotes healing in radiation enteritis and chemical colitis in a mouse parabiosis model

Mucosal healing occurs through migration and proliferation of cells within injured epithelium, yet these processes may be inadequate for mucosal healing after significant injury where the mucosa is denuded. We hypothesize that extra-intestinal cells can contribute to mucosal healing after injury to the small and large intestine. We generated parabiotic pairs between wild-type and tdTomato mice, which were then subjected to radiation-induced enteritis and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. We now show that as compared with singleton mice, mice with a parabiotic partner were protected against intestinal damage as revealed by significantly reduced weight loss, reduced expression of pro-inflammatory cytokines, reduced enterocyte apoptosis, and improved crypt proliferation. Donor cells expressed CD45-, Sca-1+, c-kit+, and CXCR4+ and accumulated around the injured crypts but did not transdifferentiate into epithelia, suggesting that extra-intestinal cells play a paracrine role in the healing response, while parabiotic pairings with Rag1-/- mice showed improved healing, indicating that adaptive immune cells were dispensable for mucosal healing. Strikingly, ablation of the bone marrow of the donor parabionts removed the protective effects. These findings reveal that the recruitment of extra-intestinal, bone marrow-derived cells into the injured intestinal mucosa can promote mucosal healing, suggesting novel therapeutic approaches for severe intestinal disease.

Associations between birth size and later height from infancy through adulthood: An individual based pooled analysis of 28 twin cohorts participating in the CODATwins project

BACKGROUND

There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment.

AIM

To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

METHODS

This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses.

RESULTS

Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length.

CONCLUSION

Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight.

Biological effect of an alternating electric field on cell proliferation and synergistic antimitotic effect in combination with ionizing radiation

Alternating electric fields at an intermediate frequency (100~300 kHz), referred to as tumour-treating fields (TTF), are believed to interrupt the process of mitosis via apoptosis and to act as an inhibitor of cell proliferation. Although the existence of an antimitotic effect of TTF is widely known, the proposed apoptotic mechanism of TTF on cell function and the efficacy of TTF are controversial issues among medical experts. To resolve these controversial issues, a better understanding of the underlying molecular mechanisms of TTF on cell function and the differences between the effects of TTF alone and in combination with other treatment techniques is essential. Here, we report experimental evidence of TTF-induced apoptosis and the synergistic antimitotic effect of TTF in combination with ionizing radiation (IR). For these experiments, two human Glioblastoma multiforme (GBM) cells (U373 and U87) were treated either with TTF alone or with TTF followed by ionizing radiation (IR). Cell apoptosis, DNA damage, and mitotic abnormalities were quantified after the application of TTF, and their percentages were markedly increased when TTF was combined with IR. Our experimental results also suggested that TTF combined with IR synergistically suppressed both cell migration and invasion, based on the inhibition of MMP-9 and vimentin.

Abstract 838: Effect of tumor treating fields on cell proliferation and synergistic antitumor efficacy in combination with ionizing radiation

Alternating electric fields at an intermediate frequency (100~300 kHz), called tumor treating fields (TTFs), are reported to interrupt the process of mitosis via apoptosis and to act as an inhibitor of cell proliferation. Although the presence of an antimitotic effect of TTFs has been widely reported, the efficacy of TTFs is still controversial issue among medical experts. To resolve this controversial issue, the comparison study between the effects of TTFs and the effect of other conventional cancer treatment techniques need to be carried out. In this study, experimental evidence of the synergistic antimitotic effect of TTFs in combination with ionizing radiation (IR) is reported. For these experiments, aggressive brain cancer cells, glioblastoma multiforme (GBM) cells (U373 and U87), were treated either with TTFs alone, with IR alone or with TTFs followed by ionizing radiation (IR). The percentages of cell apoptosis, DNA damage, and mitotic abnormalities were increased by the application of TTFs alone and its quantity was markedly increased when TTFs were combined with IR. Our results also suggested that radiotherapy together with TTFs may be clinically beneficial since the combination treatment seemed to synergistically suppress both cell migration and invasion, based on the inhibition of MMP-9 and vimentin.

Citation Format: Eun Ho Kim, Yunhui Jo, Jiwon Sung, Hyo Sook Song, Myonggeun Yoon. Effect of tumor treating fields on cell proliferation and synergistic antitumor efficacy in combination with ionizing radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 838. doi:10.1158/1538-7445.AM2017-838

Rice Bran Extract Inhibits TMEM16A-Involved Activity in the Neonatal Rat Cochlea

TMEM16A is a Ca²⁺-activated Cl⁻ channel found in secretory glands, GI and respiratory tracts, and sensory organs, playing a major physiological role in fluid secretion, autonomous GI motility, and sensory transduction. In addition, overexpression of TMEM16A has been associated with cancer cell proliferation and invasion. Suppression of upregulated TMEM16A has been proposed as an effective anti-cancer strategy. While searching for a potential TMEM16A inhibitor, components of rice bran attracted our attention due to their anti-cancer potential in colon cancer cells, a type of cells known to overexpressing TMEM16A. Here, it was tested whether rice bran extract exhibits anti-TMEM16A activity. Rice bran extract was tested in the neonatal rat cochlear tissues where TMEM16A-involved spontaneous activity is generated as a part of normal development of the auditory pathway. Rice bran extract readily inhibited the TMEM16A-involved activity in the cochlear tissues and the effect was reversible upon washout. Taken together, rice bran extract appears to contain a putative TMEM16A inhibitor and the rice byproduct might serve as a source of a new anti-cancer agent.

Secondary cancer-incidence risk estimates for external radiotherapy and high-dose-rate brachytherapy in cervical cancer: phantom study

This study was designed to estimate radiation‐induced secondary cancer risks from high‐dose‐rate (HDR) brachytherapy and external radiotherapy for patients with cervical cancer based on measurements of doses absorbed by various organs. Organ doses from HDR brachytherapy and external radiotherapy were measured using glass rod dosimeters. Doses to out‐of‐field organs were measured at various locations inside an anthropomorphic phantom. Brachytherapy‐associated organ doses were measured using a specialized phantom that enabled applicator insertion, with the pelvis portion of the existing anthropomorphic phantom replaced by this new phantom. Measured organ doses were used to calculate secondary cancer risk based on Biological Effects of Ionizing Radiation (BEIR) VII models. In both treatment modalities, organ doses per prescribed dose (PD) mostly depended on the distance between organs. The locations showing the highest and lowest doses were the right kidney (external radiotherapy: 215.2 mGy; brachytherapy: 655.17 mGy) and the brain (external radiotherapy: 15.82 mGy; brachytherapy: 2.49 mGy), respectively. Organ doses to nearby regions were higher for brachytherapy than for external beam therapy, whereas organ doses to distant regions were higher for external beam therapy. Organ doses to distant treatment regions in external radiotherapy were due primarily to out‐of‐field radiation resulting from scattering and leakage in the gantry head. For brachytherapy, the highest estimated lifetime attributable risk per 100,000 population was to the stomach (88.6), whereas the lowest risks were to the brain (0.4) and eye (0.4); for external radiotherapy, the highest and lowest risks were to the thyroid (305.1) and brain (2.4). These results may help provide a database on the impact of radiotherapy‐induced secondary cancer incidence during cervical cancer treatment, as well as suggest further research on strategies to counteract the risks of radiotherapy‐associated secondary malignancies.

PACS number(s): 87.52.‐g, 87.52.Px, 87.53.Dq, 87.53.Jw