A Prospective Phase II Trial of Radioembolization for Treatment of Uveal Melanoma Hepatic Metastasis

Background Overall survival (OS) for patients with uveal melanoma (UM) hepatic metastases is extremely poor. Therefore, stabilization of hepatic metastases is essential to prolonging OS. Purpose To assess the safety and effectiveness of radioembolization (RE) for treatment of UM hepatic metastases. Materials and Methods Enrollment for this prospective phase II trial began November 2011 and concluded January 2017. Treatment-naïve participants (group A) and participants who progressed after immunoembolization (group B) with hepatic tumor burden less than 50% underwent RE. Participants were followed for 1 month and every 3 months for acute and delayed toxicities, respectively. MRI, CT, and PET were performed every 3 months to evaluate for tumor response and extrahepatic disease. Participants were followed for at least 2 years or until death. Kaplan-Meier method and multivariable Cox proportional hazard models were used for data analysis. Results In group A, 24 participants (mean age ± standard deviation, 59 years ± 13; 13 men and 11 women) underwent unilobar (n = 7), fractionated whole-liver (n = 1), or sequential lobar (n = 16) RE. One participant was excluded from the trial. Complete response (n = 0), partial response (n = 9), or stable disease (n = 11) was achieved in 20 of 23 (87.0%; 95% confidence interval [CI]: 66.4%, 97.2%) participants. Median progression-free survival from liver metastasis was 8.1 months (95% CI: 6.4, 11.8; range, 3.3-33.7 months). Median OS was 18.5 months (95% CI: 11.3, 23.5; range, 6.5-73.7 months). In group B, 24 participants (mean age, 58 years ± 10; nine men and 15 women) underwent unilobar (n = 5) or sequential lobar (n = 19) RE. Complete response (n = 0), partial response (n = 8), or stable disease (n = 6) was achieved in 14 of 24 (58.3%; 95% CI: 36.3%, 77.9%) participants. Median progression-free survival from liver metastasis was 5.2 months (95% CI: 3.7, 9.8; range, 2.9-22.0 months). Median OS was 19.2 months (95% CI: 11.5, 24.0; range, 4.8-76.6 months). Grade 3 treatment-related toxicities included transient lymphopenia (group A, n = 1; group B, n = 1), pain (group A, n = 2) and nausea or vomiting (group A, n = 1). Conclusion Radioembolization is a promising treatment for patients with uveal melanoma hepatic metastases. © RSNA, 2019 Online supplemental material is available for this article.

Chronic exposure to green light aggravates high-fat diet-induced obesity and metabolic disorders in male mice

Light is involved in many critical physiological or biochemical processes of human beings, such as visual sensing and the production of vitamin D. Recent studies have showed that the lights of different wavelengths have a profound influence in life activities. For example, blue light promotes alertness, whereas green light (GL) induces sleep in mice. On the other hand, metabolic homeostasis is regulated by a variety of factors, including dietary habits and light exposure. Our study aims to study whether certain wavelength of light would affect metabolic status of mice. Mice were divided into normal diet-fed group and high-fat diet (HFD)-fed group, and then exposed to various colors of the light. Physiological parameters, such as body weight, food intake and water drinking were regularly measured. Glucose tolerance test and pyruvate tolerance test were simultaneously performed. After mice were humanely sacrificed, liver histology and serologic analysis were performed for detecting lipid levels. We found that GL group showed obvious glucose intolerance and increased levels of serum and liver lipid contents compared to white light group. Meanwhile, the expression levels of lipid metabolism-related genes were almost down-regulated in liver. Furthermore, melatonin receptor-1b and thyroid hormone receptor-β expression levels were significantly lowered in liver of GL-treated obese mice, suggesting that these hormone pathways may mediate the changes of lipid metabolism. Our data indicate that GL has a detrimental effect on the energy metabolism and aggravates HFD-induced obesity in mice. In addition to malnutrition, the colors of the lights also have a profound influence in the metabolic homeostasis and should be taken into consideration in the therapy of metabolic disorders.

THE MAYAK WORKER DOSIMETRY SYSTEM (MWDS-2016): INTERNAL DOSIMETRY RESULTS AND COMPARISON WITH MWDS-2013

Differences in results from the new Mayak Worker Dosimetry System (MWDS-2016) vs the previous MWDS-2013 are described. Statistical characteristics are shown for the distribution of accumulated absorbed doses to organs for 8340 workers with bioassay data. Differences in mean values of accumulated doses and their relative standard uncertainties calculated by MWDS-2016 and MWDS-2013 were analysed separately for various types of industrial compounds of plutonium, specifically nitrates, mixtures and oxides. Within the range of accumulated doses >1 mGy, lung doses for nitrates and mixtures decreased by 41 and 15%, respectively, and remained at the same level for oxides. Accumulated liver doses within the range >1 mGy increased for nitrates and mixtures by 13 and 8%, respectively, and decreased for oxides by 7%.

The impact of exposure of diabetic rats to 900 MHz electromagnetic radiation emitted from mobile phone antenna on hepatic oxidative stress

The excessive exposure of patients with type 2 diabetes mellitus (T2DM) to electromagnetic radiation (EMR) from mobile phones or their base stations antenna may influence oxidative stress and development of diabetic complications. Here, we investigated the effects of exposing type 2 diabetic rats to EMR of 900 MHz emitted from GSM mobile phone antenna for 24 hours/day over a period of 28 days on hyperglycemia and hepatic oxidative stress. Male Sprague-Dawley rats were divided into 4 groups (12 rats/group): control rats, normal rats exposed to EMR, T2DM rats generated by nicotinamide/streptozotocin administration, and T2DM rats exposed to EMR. Our results showed that the exposure of T2DM rats to EMR nonsignificantly reduced the hyperglycemia and hyperinsulinemia compared to unexposed T2DM rats. The exposure of T2DM rats to EMR for 28 days increased the hepatic levels of MDA and Nrf-2 as well as the activities of superoxide dismutase (SOD) and catalase but decreased phosphorylated Akt-2 (pAkt-2) as compared to unexposed T2DM rats. Therefore, the decrease in the hepatic pAkt-2 in T2DM rats after the exposure to EMR may result in elevated level of hepatic MDA, even though the level of Nrf-2 and the activities of SOD and catalase were increased. Abbreviations: BGL: blood glucose level; EMR: electromagnetic radiation; GSM: global system for mobile communication; H2O2: hydrogen peroxide; LSD: least significance difference; MDA:malondialdehyde; Nrf-2: nuclear factor erythroid 2- related factor 2; PI3K: phosphoinositide-3-kinase; pAkt-2: phosphorylated Akt-2; Akt-2: protein kinase; ROS: reactive oxygen species; SEM: standard error of the mean; STZ: streptozotocin; SOD: superoxide dismutase ; O2-: superoxide radical; CT: threshold cycle; T2DM: type 2 diabetes mellitus.

A computational model to investigate the influence of electrode lengths on the single probe bipolar radiofrequency ablation of the liver

BACKGROUND AND OBJECTIVES

Recently, there have been calls for RFA to be implemented in the bipolar mode for cancer treatment due to the benefits it offers over the monopolar mode. These include the ability to prevent skin burns at the grounding pad and to avoid tumour track seeding. The usage of bipolar RFA in clinical practice remains uncommon however, as not many research studies have been carried out on bipolar RFA. As such, there is still uncertainty in understanding the effects of the different RF probe configurations on the treatment outcome of RFA. This paper demonstrates that the electrode lengths have a strong influence on the mechanics of bipolar RFA. The information obtained here may lead to further optimization of the system for subsequent uses in the hospitals.

METHODS

A 2D model in the axisymmetric coordinates was developed to simulate the electro-thermophysiological responses of the tissue during a single probe bipolar RFA. Two different probe configurations were considered, namely the configuration where the active electrode is longer than the ground and the configuration where the ground electrode is longer than the active. The mathematical model was first verified with an existing experimental study found in the literature.

RESULTS

Results from the simulations showed that heating is confined only to the region around the shorter electrode, regardless of whether the shorter electrode is the active or the ground. Consequently, thermal coagulation also occurs in the region surrounding the shorter electrode. This opened up the possibility for a better customized treatment through the development of RF probes with adjustable electrode lengths.

CONCLUSIONS

The electrode length was found to play a significant role on the outcome of single probe bipolar RFA. In particular, the length of the shorter electrode becomes the limiting factor that influences the mechanics of single probe bipolar RFA. Results from this study can be used to further develop and optimize bipolar RFA as an effective and reliable cancer treatment technique.

Effect of gamma radiation on combination therapy of certain antiepileptic drugs in rats

The current study was designed to estimate the effect of υ-radiation on male rats pretreated with Levetiracetam (LEV) and/or Oxcarbazepine (OXC). Poly-treatment of rats with LEV, OXC and υ-radiation showed a significant elevation in the activity of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and isoenzyme creatinine kinase-MB (CK-MB) along with, an increase in the level of creatinine, urea, cardiac troponin (cTnI) and glutamate. These increases were associated with a decrease in acetylcholine (Ach) and υ-aminobutyric acid (GABA) levels. The data further revealed a significant increase of the apoptotic mediators tumor necrosis factor alpha (TNF-α) and brain caspase3 as well as, alterations in the oxidative stress parameters. The Results of the histopathological examination of liver, kidney, heart and brain tissues indicated coincidence with those recorded by the biochemical analysis. It seems promising to conclude that the exposure to υ-radiation intensified the deleterious and detrimental effect of dual treatment of LEV and OXC in rats.

Surgery versus external beam radiation therapy for AJCC stage I hepatocellular carcinoma

PURPOSE

To compare the survival of American Joint Committee on Cancer (AJCC) stage I hepatocellular carcinoma (HCC) treated with surgery versus external beam radiation therapy (EBRT).

METHODS

Surveillance, Epidemiology, and End Results (SEER) database was used to identify the patients diagnosed with HCC between 2004 and 2013. Overall survival (OS) and liver-specific survival (LSS) were compared between patients treated with surgery and EBRT. A 1:1 propensity score matching (PSM) analysis was employed by matching age, sex, and race.

RESULTS

Among the 1553 patients with HCC ≤2cm, there was no significant difference in OS (p=0.605, before PSM; p=0.891, after PSM) and LSS (p=0.281, before PSM; p=0.346, after PSM) between patients treated with surgery and EBRT. Among the 1752 patients with HCC >2cm and ≤3cm, patients treated with surgery had significantly better OS (p=0.001) than those treated with EBRT, but statistically similar LSS (p=0.072) before PSM; however, there was no significant difference in OS (p=0.139) and LSS (p=0.722) between patients treated with surgery and EBRT after PSM. Additionally, 1157, 723, and 1331 patients had HCC >3cm and ≤4cm, HCC >4cm and ≤5cm, and HCC >5cm, respectively; among them, patients treated with surgery had significantly better OS and LSS than those treated with EBRT regardless of PSM.

CONCLUSIONS

At the AJCC stage I, the survival after EBRT might be comparable to that after surgery for HCC ≤3cm, but the survival after EBRT was inferior to that after surgery for HCC >3cm.

Clinical efficacy analysis of transcatheter arterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) in primary liver cancer and recurrent liver cancer

PURPOSE

To compare the efficacy of transcatheter arterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) in primary hepatocellular carcinoma and recurrence of hepatocellular carcinoma after hepatectomy, and analysis the prognostic factors affecting therapeutic outcomes.

METHODS

A total of 132 hepatocellular carcinoma patients treated with TACE combined with RFA were divided into primary group (n=89) and recurrent group (n=43). Their clinical date were reviewed. The overall survival (OS), tumor-free survival (TFS) and safety between 2 groups were compared. Prognostic factors were analyzed with univariate and multivariate analyses.

RESULTS

OS rates at 1 and 3 years were 94.4% (84/89) and 70.8% (63/89) in the primary group, and TFS were 76.4% (68/89) and 37.1% (33/89), respectively. The OS rates in the recurrent group were 93.0% (40/43) and 65.1% (28/43), and TFS rates were 41.9% (18/43) and 13.9% (6/43), respectively. The OS rates had no significant difference between 2 groups (x2=0.0068, 0.4353, p=0.9342, 0.5094), but the TFS rates in primary group were significantly higher than in the recurrent group (x2=15.2378, 7.4483, p=0.0001, 0.0063). Multivariate analysis identified presence of portosystemic collaterals, AFP level, total bilirubin and Child-Pugh grading as factors affecting OS, and the presence of portosystemic collaterals and AFP level were two unfavorable prognostic factors influencing TFS.

CONCLUSIONS

TACE combined with RFA is helpful in improving the survival rate of patients with primary and recurrent hepatocellular carcinoma. Presence of portosystemic collaterals, AFP level,ptotal bilirubin and Child-Pugh grading were the factors affecting OS.

Impact of planned dose reporting methods on Gamma pass rates for IROC lung and liver motion phantoms treated with pencil beam scanning protons

PURPOSE

The purpose of this study is to evaluate the impact of two methods of reporting planned dose distributions on the Gamma analysis pass rates for comparison with measured 2D film dose and simulated delivered 3D dose for proton pencil beam scanning treatment of the Imaging and Radiation Oncology Core (IROC) proton lung and liver mobile phantoms.

METHODS AND MATERIALS

Four-dimensional (4D) computed-tomography (CT) image sets were acquired for IROC proton lung and liver mobile phantoms, which include dosimetry inserts that contains targets, thermoluminescent dosimeters and EBT2 films for plan dose verification. 4DCT measured fixed motion magnitudes were 1.3 and 1.0 cm for the lung and liver phantoms, respectively. To study the effects of motion magnitude on the Gamma analysis pass rate, three motion magnitudes for each phantom were simulated by creating virtual 4DCT image sets with motion magnitudes scaled from the scanned phantom motion by 50, 100, and 200%. The internal target volumes were contoured on the maximum intensity projection CTs of the 4DCTs for the lung phantom and on the minimum intensity projection CTs of the 4DCTs for the liver phantom. Treatment plans were optimized on the average intensity projection (AVE) CTs of the 4DCTs using the RayStation treatment planning system. Plan doses were calculated on the AVE CTs, which was defined as the planned AVE dose (method one). Plan doses were also calculated on all 10 phase CTs of the 4DCTs and were registered using target alignment to and equal-weight-summed on the 50% phase (T50) CT, which was defined as the planned 4D dose (method two). The planned AVE doses and 4D doses for phantom treatment were reported to IROC, and the 2D-2D Gamma analysis pass rates for measured film dose relative to the planned AVE and 4D doses were compared. To evaluate motion interplay effects, simulated delivered doses were calculated for each plan by sorting spots into corresponding respiratory phases using spot delivery time recorded in the log files by the beam delivery system to calculate each phase dose and accumulate dose to the T50 CTs. Ten random beam starting phases were used for each beam to obtain the range of the simulated delivered dose distributions. 3D-3D Gamma analyses were performed to compare the planned 4D/AVE doses with simulated delivered doses.

RESULTS

The planned 4D dose matched better with the measured 2D film dose and simulated delivered 3D dose than the planned AVE dose. Using planned 4D dose as institution reported planned dose to IROC improved IROC film dose 2D-2D Gamma analysis pass rate from 92 to 96% on average for three films for the lung phantom (7% 5 mm), and from 92 to 94% in the sagittal plane for the liver phantom (7% 4 mm), respectively, compared with using the planned AVE dose. The 3D-3D Gamma analysis (3% 3 mm) pass rate showed that the simulated delivered doses for lung and liver phantoms using 10 random beam starting phases for each delivered beam matched the planned 4D dose significantly better than the planned AVE dose for phantom motions larger than 1 cm (p ≤ 0.04).

CONCLUSIONS

It is recommended to use the planned 4D dose as the institution reported planned dose to IROC to compare with the measured film dose for proton mobile phantoms to improve film Gamma analysis pass rate in the IROC credentialing process.

Exposure to solar ultraviolet radiation limits diet-induced weight gain, increases liver triglycerides and prevents the early signs of cardiovascular disease in mice

BACKGROUND AND AIMS

Sunlight exposure is associated with a number of health benefits including protecting us from autoimmunity, cardiovascular disease, obesity and diabetes. Animal studies have confirmed that ultraviolet (UV)-B radiation, independently of vitamin D, can limit diet-induced obesity, metabolic syndrome and atherosclerosis. The aim of this study is to investigate whether exposure to the UV radiation contained in sunlight impacts on these disease parameters.

METHODS AND RESULTS

We have trialled an intervention with solar UV in obese and atherosclerosis-prone mice. We have discovered that solar-simulated UV can significantly limit diet-induced obesity and reduce atheroma development in mice fed a diet high in sugar and fat. The optimal regime for this benefit was exposure once a week to solar UV equivalent to approximately 30 min of summer sun. Exposure to this optimal dose of solar UV also led to a significant increase in liver triglycerides which may protect the liver from damage.

CONCLUSION

Our results show that the UV contained in sunlight has the potential to prevent and treat chronic disease at sites distant from irradiated skin. A major health challenge going forward will be to harness the power of the sun safely, without risking an increase in skin cancers.

Identification of Cofilin-1 and Destrin as Potential Early-warning Biomarkers for Gamma Radiation in Mouse Liver Tissues

Gamma radiation causes cell injury and leads to an increased risk of cancer, so it is of practical significance to identify biomarkers for gamma radiation. We used proteomic analysis to identify differentially expressed proteins in liver tissues of C57BL/6J mice treated with gamma radiation from Cs for 360 d. We confirmed obvious pathological changes in mouse liver tissues after irradiation. Compared with the control group, 74 proteins showed a fold change of ≥1.5 in the irradiated groups. We selected 24 proteins for bioinformatics analysis and peptide mass fingerprinting and found that 20 of the identified proteins were meaningful. These proteins were associated with tumorigenesis, tumor suppression, catalysis, cell apoptosis, cytoskeleton, metabolism, gene transcription, T-cell response, and other pathways. We confirmed that both cofilin-1 and destrin were up regulated in the irradiated groups by western blot and real-time polymerase chain reaction. Our findings indicate that cofilin-1 and destrin are sensitive to gamma radiation and may be potential biomarkers for gamma radiation. Whether these proteins are involved in radiation-induced tumorigenesis requires further investigation.

Crocin mitigates γ-rays-induced hepatic toxicity in rats

Crocin (C₄₄H₆₄O₂₄) is an isolated bioactive molecule of saffron extract. It has different pharmacological effects such as antioxidant and anti-inflammatory activities. In the present study, radioprotective property of crocin was investigated in the rat liver. Thirty-two rats were equally divided into four groups: (1) control (normal saline), (2) crocin (200 mg/kg), (3) γ-rays (6Gy), and (4) crocin plus γ-rays-treated groups. The liver histopathology, serum transaminases (ALT and AST), alkaline phosphatase (ALP), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and hepatic lipid peroxidation, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) have been assessed. The histopathological result of hepatic tissue in group 3 showed hydropic degeneration and this progressed to focal or spotty necrosis through the lobule. Moreover, some sinusoids are distended with blood or with leukocytic infiltrations. Other cases in group 3 showed periportal leukocytic infiltrations and necrosis extended out from the portal tract to involve hepatic lobules with fibrinous necrosis in portal vessels, while the examination of hepatic tissues of group 4 showed reduced deformities, irregular arrangement, congested hepatic vessels, and necrosis in hepatocytes. The results also showed significant decreased level of liver function activities, inflammatory markers, lipid peroxidation, and increased levels of liver antioxidants enzymes in group 4. Crocin showed moderate protective effect against γ-rays-induced liver toxicity. The antioxidant effect of crocin may be a major reason for its positive impact on liver parameters. Graphical abstract .

The volume of liver irradiated during modern free-breathing breast radiotherapy: Implications for theory and practice

INTRODUCTION

Incidental liver irradiation during breast radiotherapy can increase the risk of second primary malignancy and induce adverse inflammatory states. This study establishes the volume of liver irradiated during free-breathing breast radiotherapy. Novel associations between liver dose-volume data and systemic interleukin-6 soluble receptor and blood counts are evaluated.

METHODS

The volume of liver within the 10%, 50% and 90% isodose was determined for 100 women with stage 0 to II breast carcinoma undergoing 40Gy in 15 fractions over three weeks tangential irradiation. Blood counts and interleukin 6 soluble receptor concentration were recorded before, during and four weeks after radiotherapy. Dose-volume data for right-sided treatments was associated with longitudinal measures at bivariate and multivariable levels.

RESULTS

A maximum of 226cm³ (19%), 92 cm³ (8%) and 62 cm³ (5%) of the liver was irradiated within the 10%, 50% and 90% isodose. Liver irradiation was almost exclusively a feature of the 52 right-sided treatments and was strongly correlated with breast volume (ρ = 0.7, p < 0.0001). Liver V10% was significantly associated with interleukin-6 soluble receptor concentration four weeks post-radiotherapy (beta = 0.38, p = 0.01) after controlling for theoretical confounding variables.

CONCLUSION

Up to 8% of the liver is irradiated within the primary beam during local right-sided breast radiotherapy. Select use of a deep inspiration breath hold technique would reduce this volume, and minimise the risk of radiation-induced malignancy and acute systemic elevation of inflammatory interleukin 6 soluble receptor.

Exploiting Ballou's rule for better tissue classification

Ultrasound tissue characterization based on the coefficient of nonlinearity, β_n = 1 + B/2A, has been demonstrated to produce added diagnostic value due to its large variation and sensitivity to tissue structure. However, the parameter has been observed to be significantly correlated to the speed of sound and density. These relationships are analyzed empirically as well as theoretically by developing a pressure-density relation based on a thermodynamic model and the Mie intermolecular potential. The results indicate that for many soft tissues, the coefficient of nonlinearity is largely determined by the isentropic compressibility, κ_s. Consequently, for tissue characterization, estimating the nonlinear response of the medium, given by β_p = β_nκ_s, appears to be beneficial due to correlated quantities.

Analysis of a lectin microarray identifies altered sialylation of mouse serum glycoproteins induced by whole-body radiation exposure

Microarrays containing 45 different lectins were analyzed to identify global changes in the glycosylation of serum glycoproteins from mice exposed to whole-body γ-radiation. The results showed that radiation exposure increased and decreased the relative amounts of α-2,3- and α-2,6-sialic acids, respectively. The expression of α-2,3- and α-2,6-sialyltransferase genes in the liver was analyzed to determine whether changes in their expression were responsible for the sialic acid changes. The increase in α-2,3-sialic acid correlated with St3gal5 upregulation after radiation exposure; however, a decrease in St6gal1 expression was not observed. Analysis of a PCR array of genes expressed in irradiated mouse livers revealed that irradiation did not alter the expression of most of the included genes. These results suggest that glycomic screening of serum glycoproteins using lectin microarrays can be a powerful tool for identifying radiation-induced changes in the post-translational addition of sugar moieties to proteins. In addition, the results indicate that altered sialylation of glycoproteins may be an initial response to acute radiation exposure.

A dosimetric comparison between volumetric-modulated arc therapy and dynamic conformal arc therapy in SBRT

PURPOSE

The purpose of this study was to investigate the dosimetric equivalency of dynamic conformal arc therapy (DCAT) against volumetric modulated arc therapy (VMAT) plans in stereotactic body radiation therapy (SBRT) of lung and liver lesions and to examine if efficiency can be increased.

METHODS

Nineteen patients previously treated for lung and liver cancer lesions with SBRT were included. Organs at risk (OAR) and targets were contoured by a single radiation oncologist. All plans were optimized by the same dosimetrist using ELEKTA Monaco treatment planning system version 5.0 for 6MV flattening filter free (FFF) photon beam in a VersaHD (ELEKTA, Crawley, UK). A VMAT and DCAT plan was optimized using the same objectives using coplanar arcs of 225o arc span.

RESULTS

All plans have achieved the target and OAR planning objectives. The target dose conformity was comparable (mean VMAT PTVr=1.3 and DCAT PTVr=1.4), and the low dose spillage were similar (mean VMAT R50=4.5 and DCAT R50=4.6). However, monitor units (MU) for DCAT plans were lower by 2.5 times on average than VMAT plans. It was observed that in 75% of cases where OARs overlapped with the PTV, maximum doses to OAR were higher in VMAT than DCAT plans, but the difference was not significant. Patient specific quality assurance (QA) plans were measured using the Scandidos Delta4 phantom and gamma analysis performed using 2mm distance to agreement (DTA) and 2% dose difference yielded more than 95% passing rates on both VMAT and DCAT plans.

CONCLUSIONS

DCAT delivery for lung and liver SBRT is a dosimetrically equivalent and an efficient alternative to VMAT plans.

Computed tomography or contrast-enhanced ultrasonography for follow-up of liver metastases after Cyberknife therapy?: A prospective pilot study

OBJECTIVES

Contrast-enhanced ultrasonography (CEUS) allows the study of vascularization of secondary liver lesions. The Cyberknife (Accuray, Inc, Sunnyvale, CA) is a therapeutic method that allows a tumor target to be subjected to a high radiant dose gradient. This prospective pilot study aimed to demonstrate the concordance of CEUS versus contrast-enhanced computed tomography (CECT) in determining the stability or disease progression of secondary liver lesions after treatment with the Cyberknife.

METHODS

Twenty-four patients were consecutively enrolled, and 3 different operators evaluated the CEUS images and the intermodality concordance with CECT. All patients received CEUS at 1 and 2 months after the Cyberknife therapy. The intermodality agreement was evaluated by the Cohen κ coefficient and a multivariate analysis according to the method of Janson and Olsson (Educ Psychol Meas 2001; 61:277-289).

RESULTS

Forty secondary liver lesions were detected and treated. Forty-one CECT and 51 CEUS examinations were performed without any adverse events in the 24 patients. The intermodality agreement rates, calculated for the operators as Cohen κ values, were κ = 1.00, 0.881, and 0.767, respectively. The multivariate analysis of intermodality agreement showed an almost perfect value (ι = 0.841).

CONCLUSIONS

This pilot study found excellent diagnostic correspondence between CEUS and CECT in the evaluation of local disease stability or progression after Cyberknife therapy in liver metastases. These findings suggest that CEUS could play an important role in the surveillance of these patients because of its high accuracy and reproducibility, thus reducing the need for CECT.

Role of betaine in liver injury induced by the exposure to ionizing radiation

Oxidative stress, apoptosis, and fibrosis may play a major role in the development of radiation-induced liver damage. Betaine, a native compound widely present in beetroot, was reported to possess hepato-protective properties. The objective of this study was to investigate the influence of betaine on radiation-induced liver damage. Animals were exposed to 9 Gy applied in 3 doses of 3 Gy/wk. Betaine (400 mg/kg/d), was orally supplemented to rats after the first radiation dose, and daily during the irradiation period. Animals were sacrificed 1 day after the last dose of radiation. The results showed that irradiation has induced oxidative stress in the liver denoted by a significant elevation in malondialdehyde, protein carbonyl, and 8-hydroxy-2-deoxyguanosine with a significant reduction in catalase activity and glutathione (GSH) content. The activity of the detoxification enzyme cytochrome P450 (CYP450) increased while GSH transferase (GSH-T) decreased. The activity of the apoptotic marker caspase-3 increased concomitant with increased hyaluronic acid, hydroxyproline, laminin (LN), and collagen IV. These alterations were associated with a significant increase of gamma-glutamyl transferase, alkaline phosphatase and alanine and aspartate aminotransferase markers of liver dysfunction. Betaine treatment has significantly attenuated oxidative stress, decreased the activity of CYP450, enhanced GSH-T, reduced the activity of caspase-3, and the level of fibrotic markers concomitant with a significant improvement of liver function. In conclusion, betaine through its antioxidant activity and by enhancing liver detoxification and reducing apoptosis may alleviate the progression of liver fibrosis and exert a beneficial impact on radiation-induced liver damage.

Fast technetium-99m liver SPECT for evaluation of the pretreatment procedure for radioembolization dosimetry

PURPOSE

The efficiency of radioembolization procedures could be greatly enhanced if results of the 99m Tc-MAA pretreatment procedure were immediately available in the interventional suite, enabling 1-day procedures as a result of direct estimation of the hepatic radiation dose and lung shunt fraction. This would, however, require a relatively fast, but still quantitative, SPECT procedure, which might be achieved with acquisition protocols using nonuniform durations of the projection images.

METHODS

SPECT liver images of the 150-MBq 99m Tc-MAA pretreatment procedure were simulated for eight different lesion locations and two different lesion sizes using the digital XCAT phantom for both single- and dual-head scanning geometries with respective total acquisition times of 1, 2, 5, 10, and 30 min. Three nonuniform projection-time acquisition protocols ("half-circle SPECT (HCS)," "nonuniform SPECT (NUS) I," and "NUS II") for fast quantitative SPECT of the liver were designed and compared with the standard uniform projection-time protocol. Images were evaluated in terms of contrast-to-noise ratio (CNR), activity recovery coefficient (ARC), tumor/non-tumor (T/N) activity concentration ratio, and lung shunt fraction (LSF) estimation. In addition, image quality was verified with a physical phantom experiment, reconstructed with both clinical and Monte Carlo-based reconstruction software.

RESULTS

Simulations showed no substantial change in image quality and dosimetry by usage of a nonuniform projection-time acquisition protocol. Upon shortening acquisition times, CNR dropped, but ARC, T/N ratio, and LSF estimates were stable across all simulated acquisition times. Results of the physical phantom were in agreement with those of the simulations.

CONCLUSION

Both uniform and nonuniform projection-time acquisition liver SPECT protocols yield accurate dosimetric metrics for radioembolization treatment planning in the interventional suite within 10 min, without compromising image quality. Consequently, fast quantitative SPECT of the liver in the interventional suite is feasible.

Melatonin and Its Metabolites Ameliorate UVR-Induced Mitochondrial Oxidative Stress in Human MNT-1 Melanoma Cells

Melatonin (Mel) is the major biologically active molecule secreted by the pineal gland. Mel and its metabolites, 6-hydroxymelatonin (6(OH)Mel) and 5-methoxytryptamine (5-MT), possess a variety of functions, including the scavenging of free radicals and the induction of protective or reparative mechanisms in the cell. Their amphiphilic character allows them to cross cellular membranes and reach subcellular organelles, including the mitochondria. Herein, the action of Mel, 6(OH)Mel, and 5-MT in human MNT-1 melanoma cells against ultraviolet B (UVB) radiation was investigated. The dose of 50 mJ/cm² caused a significant reduction of cell viability up to 48%, while investigated compounds counteracted this deleterious effect. UVB exposure increased catalase activity and led to a simultaneous Ca⁺⁺ influx (16%), while tested compounds prevented these disturbances. Additional analysis focused on mitochondrial respiration performed in isolated mitochondria from the liver of BALB/cJ mice where Mel, 6(OH)Mel, and 5-MT significantly enhanced the oxidative phosphorylation at the dose of 10⁻⁶ M with lower effects seen at 10⁻⁹ or 10⁻⁴ M. In conclusion, Mel, 6(OH)Mel and 5-MT protect MNT-1 cells, which express melatonin receptors (MT1 and MT2) against UVB-induced oxidative stress and mitochondrial dysfunction, including the uncoupling of oxidative phosphorylation.

Evaluation of 2D and 3D ultrasound tracking algorithms and impact on ultrasound-guided liver radiotherapy margins

PURPOSE

Compensation for respiratory motion is important during abdominal cancer treatments. In this work we report the results of the 2015 MICCAI Challenge on Liver Ultrasound Tracking and extend the 2D results to relate them to clinical relevance in form of reducing treatment margins and hence sparing healthy tissues, while maintaining full duty cycle.

METHODS

We describe methodologies for estimating and temporally predicting respiratory liver motion from continuous ultrasound imaging, used during ultrasound-guided radiation therapy. Furthermore, we investigated the trade-off between tracking accuracy and runtime in combination with temporal prediction strategies and their impact on treatment margins.

RESULTS

Based on 2D ultrasound sequences from 39 volunteers, a mean tracking accuracy of 0.9 mm was achieved when combining the results from the 4 challenge submissions (1.2 to 3.3 mm). The two submissions for the 3D sequences from 14 volunteers provided mean accuracies of 1.7 and 1.8 mm. In combination with temporal prediction, using the faster (41 vs 228 ms) but less accurate (1.4 vs 0.9 mm) tracking method resulted in substantially reduced treatment margins (70% vs 39%) in contrast to mid-ventilation margins, as it avoided non-linear temporal prediction by keeping the treatment system latency low (150 vs 400 ms). Acceleration of the best tracking method would improve the margin reduction to 75%.

CONCLUSIONS

Liver motion estimation and prediction during free-breathing from 2D ultrasound images can substantially reduce the in-plane motion uncertainty and hence treatment margins. Employing an accurate tracking method while avoiding non-linear temporal prediction would be favorable. This approach has the potential to shorten treatment time compared to breath-hold and gated approaches, and increase treatment efficiency and safety.

Acoustic Methods for Increasing the Cavitation Initiation Pressure Threshold

Histotripsy is a tissue ablation method that utilizes focused, high-amplitude ultrasound to generate a cavitation bubble cloud that mechanically fractionates tissue. Effective histotripsy depends on the initiation, control, and maintenance of cavitation bubble clouds in the targeted area. In this study, we hypothesized that a low-pressure acoustic pulse sequence applied before and/or during histotripsy therapy would increase the cavitation initiation pressure threshold and the growth of cavitation bubble clouds. This technique could shrink or "sharpen" the focal zone during histotripsy to produce more precise and well-defined lesions with minimal collateral damage. It may also be a way to actively protect the soft tissue from cavitation damage during lithotripsy by increasing the pressure threshold for bubble cloud initiation. We applied these low-amplitude acoustic pulse sequences before and during histotripsy treatments with the pulse repetition frequency of 1 and 100 Hz, in three different mediums: water, tissue phantom agarose gel, and bovine liver in vitro. Acoustic backscatter signals and optical imaging were used to detect and monitor the initiation, maintenance, and growth of the resulting cavitation bubble cloud. The results demonstrated that the use of low-amplitude acoustic pulse sequences could increase the cavitation pressure amplitude threshold by 20% in the targeted area.

SMER28 is a mTOR-independent small molecule enhancer of autophagy that protects mouse bone marrow and liver against radiotherapy

Effective cytoprotectors that are selective for normal tissues could decrease radiotherapy and chemotherapy sequelae and facilitate the safe administration of higher radiation doses. This could improve the cure rates of radiotherapy for cancer patients. Autophagy is a cytoplasmic cellular process that is necessary for the clearance of damaged or aged proteins and organelles. It is a strong determinant of post-irradiation cell fate. In this study, we investigated the effect of the mTOR-independent small molecule enhancer of autophagy (SMER28) on mouse liver autophagy and post-irradiation recovery of mouse bone marrow and liver. SMER28 enhanced the autophagy flux and improved the survival of normal hepatocytes. This effect was specific for normal cells because SMER28 had no protective effect on hepatoma or other cancer cell line survival in vitro. In vivo subcutaneous administration of SMER28 protected mouse liver and bone marrow against radiation damage and facilitated survival of mice after lethal whole body or abdominal irradiation. These findings open a new field of research on autophagy-targeting radioprotectors with clinical applications in oncology, occupational, and space medicine.

Optimization of the ICRP 67 and NCRP 156 Transfer Rates Applied to Nonhuman Primates Intramuscularly Injected With 241Am

Nonhuman primates intramuscularly injected with Am have been investigated using the International Commission on Radiological Protection Report 67 model coupled with National Council on Radiation Protection and Measurements Report 156 model. Default parameters from these models were input into the Integrated Modules for Bioassay Analysis software to predict the intake and skeleton retention in 20 tested nonhuman primates. The predictions generated were compared to the experimental data from the Durbin nonhuman primate studies. A previous study conducted by Alomairy in 2017 indicated that the early behavior of Am(NO3)3 in wound cases can be explained using the default transfer rates. However, these transfer rates were not able to predict the intake and skeleton retention at the time of sacrifice after 100 d postintake due to differences in the amount of activity translocated or deposited in liver tissue and nonliver tissues (primarily skeleton). This is likely due to the physiological differences between the nonhuman primate and human. The objective of this study was to develop new transfer rate parameters for wound and systemic models in an effort to improve biokinetic predictions. Estimates of new transfer rates appropriate for nonhuman primate data were estimated by employing a companion software program called Integrated Modules for Bioassay Analysis Uncertainty Analyzer. During validation of the suggested transfer rates, it was observed that the optimized parameters predicted the intake in 66% of the tested animals used in this investigation. The activity retained in the skeleton improved in almost all cases where the differences between predicted and measured activity is less than 20%.