Dosimetric Parameters Correlate with Taste Alterations in Head and Neck Radiotherapy

PURPOSE/OBJECTIVE(S)

Dysgeusia is an acute and chronic side effect of head and neck chemoradiation, with persistent taste dysfunction 1-2 years post radiotherapy occurring in 23-50% of patients. Several head and neck clinical trials set oral cavity mean doses between 30 to 40 Gy, however, there are no set guidelines accurately defining the composite structure and anatomic boundaries for the oral cavity or separating the tongue into specific quadrants. In this single institution cross sectional study, we sought to determine the effects of radiation doses to specific regions of the oral cavity and tongue on patient-reported long term dysgeusia. We hypothesize that radiation Dose to specific structures in the oral cavity will correlate with long-term dysgeusia in patients who have received head and neck radiotherapy.

MATERIALS/METHODS

Patients with primary head and neck cancer receiving definitive intensity modulated radiation therapy (RT) completed quality of life assessments that included patient-reported gustatory function, 1 year post RT. Dosimetric data from RT plans were collected for specific regions and organs at risk within the oral cavity. These structures included the anterior, posterior, superior and inferior tongue (OT), pharyngeal constrictors (as a surrogate for the corda-tympani) and the oral cavity. A forward binary logistic regression model was performed using these data points with scoring from the QLQ-H&N43 questionnaire subsection on taste (Q45) to determine the most predictive values for dysgeusia and the OR for moderate/severe alterations in taste.

RESULTS

A total of 78 patients were included in this study, of these patients, 63 had dosimetric data for the pharyngeal constrictors. The Oral Cavity Volume percentage receiving 50Gy (OC V50) and Pharyngeal Constrictors Volume percentage receiving 55Gy (PC V55) were the most predictive constraints for dysgeusia. (0.042, p = 0.011 and 0.041, p = 0.033). Holding all other variables constant in a forward binary logistic regression including 78 patients, the odds of having moderate to severe taste alterations increased by 56% (OR 1.045, 95% CI 1.012-1.079) for a 1% increase in OCV50. When analyzing the 68 patients with available pharyngeal constrictors data, taste alteration increased 20% for every 1% increase in PCV55 (OR 1.042, 95% CI 1.003-1.082). There was no correlation with taste alterations in any of the dose parameters tested (Dmax, mean and V50 up to V70) for superior, inferior, anterior or posterior regions of the tongue.

CONCLUSION

Dosimetric parameters for the oral cavity (OC V50) and pharyngeal constrictors (PC V55) were positively correlated with taste alterations, however, no other specific regions within the oral tongue predicted taste disfunction. Normal tissue complication probability modeling curves to identify OC V50 and PC V55 constraints for dysgeusia are needed.

Prognostic Value of Weekly Delta-Radiomics during MR-Linac Radiotherapy of Glioblastoma

PURPOSE/OBJECTIVE(S)

MRI after chemoradiotherapy (chemoRT) shows areas of presumed tumor growth in ≤ 50% of glioblastoma (GBM) patients, which can be true progression (TP) - tumor growth with poor treatment response, or pseudoprogression (PP) - edema and tumor necrosis with favorable treatment response. Patients with TP have median overall survival (OS) of only 7 months, while patients with PP have median OS of 36 months. However, on imaging, TP and PP are usually not discernible during treatment, making it difficult to adapt radiation for poor responders. The purpose of this study was to investigate the prognostic value of delta radiomic features from MR-Linac for GBM.

MATERIALS/METHODS

Using an IRB-approved prospective cohort of GBM patients undergoing 30 fractions of chemoRT to 60 Gy on a 0.35T MR-Linac, 2 regions of interest (ROI) were contoured on daily T2-weighted treatment set-up scans: 1) tumor/edema (lesion) and 2) post-surgical resection cavity (RC). The lesion ROI were used to calculate texture features: second order radiomics features based on the gray-level co-occurrence matrix (GLCM), gray-level size zone matrix (GLSZM), gray-level run length matrix (GLRLM), and neighborhood gray-tone difference matrix (NGTDM). Each of these describe the probability of spatial relationships of gray levels occurring within the ROI. Features from fraction 1 (pre-radiation) were subtracted from fractions 5, 10, 15, 25, and 30 to create delta features at 5 timepoints (D5-D30). Patient response was retrospectively defined as no progression (NP), TP, or PP. Supervised machine learning was utilized using a 500-tree random forest (RF) classification model with TP or PP as the outcome. Variable importance analysis was conducted by calculating the out-of-bag errors with multiple bootstrapped data sets. The most prognostic features were selected using the RF importance scores.

RESULTS

Thirty-six patients were screened for inclusion: 9 were excluded due to no T2 lesion (RC ROI only). Of the remaining 27 patients: 10 had NP, 11 had TP, and 6 had PP. Thirty-nine texture features, plus lesion volume and mean lesion intensity (for a total of 41 variables per time point) were calculated and included in the model. Of the 10 most prognostic features, 6 were from D10, suggesting that prognostic changes in the underlying lesion microenvironment are occurring within the first 10 fractions of treatment. The model selected GLSZM high gray-level zone emphasis (HGZE) D10, IBSI code 5GN9, as the most prognostic feature. The receiver operator characteristic (ROC) area under the curve (AUC) for GLSZM HGZE D10 was 0.94 (95% CI = 0.81-1.00).

CONCLUSION

Delta radiomic features extracted from MR-Linac imaging may predict between PP and TP in GBM patients during treatment, which is earlier than current methods. This could allow physicians to adapt/intensify treatment in real time for poorly responding patients. Future directions include analysis with a larger patient cohort and with additional MRI contrasts (MR-Linac multiparametric MRI).

Spectroscopic MRI Detects Occult Glioblastoma Invasion during Chemoradiation

PURPOSE/OBJECTIVE(S)

The standard of care for glioblastoma (GBM) includes surgical resection followed by adjuvant chemoradiation (chemoRT). Treatment margins are controversial since conventional imaging does not define the extent of infiltrating tumor cells. Whole-brain spectroscopic MRI (sMRI) allows for visualization of native metabolites in normal brain and tumor cells, and the relative choline to N-acetyl-aspartate ratio greater than 2 (rChoNAA>2) strongly correlates with the presence of occult GBM cells in otherwise normal-appearing brain. With an MRI-Linac, we are performing studies of adaptive radiotherapy to measure changes in cavity size, edema, and enhancement during chemoRT. We questioned whether rChoNAA>2 would change along with anatomical changes to inform clinical target volumes for adaptive chemoRT trials.

MATERIALS/METHODS

In a prospective study, 18 patients with primary GBM underwent daily MRI-guided chemoRT with standalone 3T sMRI generation of rChoNAA>2 maps at three timepoints before, during, and after chemoradiation. Conventional treatment volumes of T1 post-contrast and cavity (GTV2, i.e., boost) with or without FLAIR hyperintensity (GTV1) were compared to rChoNAA>2 volumes. DICE similarity coefficients were calculated to assess the spatial similarity of these volumes. Hausdorff distances were calculated to identify rChoNAA>2 extending beyond GTVs throughout the course of chemoradiation.

RESULTS

The mean GTV1 was 58.1 cc (range 0-251.4 cc), the mean GTV2 was 47.9 cc (range 0-139.9 cc), and the mean rChoNAA>2 volume was 31.1 cc (range 0-103.2 cc). rChoNAA>2 volumes did not significantly change over the course of chemoRT or correlate with measurement timepoint. The mean DICE similarity coefficient between GTV1 and rChoNAA>2 volumes was 0.39 (range 0-0.80), and the mean DICE similarity coefficient between GTV2 and rChoNAA>2 volumes was 0.29 (range 0-0.77). DICE similarity coefficients were significantly different from unity indicating spatial differences between rChoNAA>2 and conventional MRI volumes. The mean Hausdorff distances of rChoNAA>2 extending beyond GTV1 was 1.3 cm (range 0.7-2.1 cm), and the mean Hausdorff distances of rChoNAA>2 extending beyond GTV2 was 1.9 cm (range 0.8-2.9 cm), suggesting high-risk disease invading beyond what is visible on conventional MRI sequences.

CONCLUSION

Whole-brain sMRI with generation of rChoNAA>2 maps suggest conventional MRI does not fully capture the extent of disease in primary GBM throughout the course of chemoradiation. rChoNAA>2 maps often extend up to approximately 2 cm beyond conventional boost radiotherapy volumes. Further studies are ongoing to determine how sMRI can be used to adapt radiation target volumes during chemoradiation and escalate dose to occult disease.

Pattern Analysis of Daily Lesion Volume Trajectories for Early Prediction of Glioblastoma Progression During MR-Linac Radiotherapy

PURPOSE/OBJECTIVE(S)

Distinguishing between true progression (TP) and pseudoprogression (PP) post-radiotherapy (RT) is of paramount importance for treatment management of patients with glioblastoma (GBM). MR-Linac systems allow for daily monitoring of tumor changes throughout the course of RT. We hypothesized that the patterns of tumor volume change during RT may enable early prediction of treatment response.

MATERIALS/METHODS

Using an IRB-approved prospective cohort of GBM patients undergoing 30 fractions of chemoRT to 60 Gy on a 0.35T MR-Linac, tumor/edema (tumor lesion) regions of interest (ROI) were contoured on daily T2-weighted treatment set-up scans. The obtained tumor lesion (TL) volume changes during treatment were smoothed with a moving average Gaussian window over time. Non-negative Matrix Factorization (NMF) was applied to the data matrix D (N x F), containing the trajectories in its rows for each patient, where N is the number of patients analyzed and F is the number of fractions. NMF represents D as a linear combination of three temporal (hidden) patterns and their weights in each individual trajectory. The same analysis was performed for ΔD, containing the changes in volumes with reference to the first fraction. The calculated weights were scaled in [0, 1], expressed as probabilities (by ℓ1-normalization) and used as features in Linear Discriminant Analysis (LDA). The LDA model was trained to differentiate between no progression (NP), PP and TP, and assessed by leave-one-subject-out cross-validation.

RESULTS

Thirty-six patients were screened for inclusion: 9 were excluded due to no T2 lesion (resection cavity only). Of the remaining 27 GBM patients analyzed, 10 had no tumor growth on first post-RT diagnostic MRI, 6 were determined to have PP based on regression or long-term stability of findings, and 11 had TP due to continued progression of disease past 6 months, rapid patient death from disease, or tissue sampling showing active malignancy. With the use of only 2 features, LDA achieved an overall accuracy of 70.4% classifying correctly: 6 (60%), 4 (67%), and 9 (82%) patients with NP, PP, and TP, respectively. The temporal NMF patterns (monotonous decrease, rapid increase during the third part of the treatment, etc.) indicate that there is enough signal to classify patients' response based on the pattern tumor volume changes during RT.

CONCLUSION

We identified tumor dynamics' patterns during RT, indicative of differential behavior of tumor growth between TP and PP. Although with a limited number of patients, these initial results suggest that tumor volume changes during treatment may provide early markers of treatment response. This could allow physicians to adapt/intensify treatment in real time for poorly responding patients. Next steps include automating the process of real-time tumor volume monitoring by incorporating a deep learning solution for automatic volume delineation on daily treatment set-up scans.

Lactobacillus plantarum DR7 improved brain health in aging rats via the serotonin, inflammatory and apoptosis pathways

Aging processes affect the brain in many ways, ranging from cellular to functional levels which lead to cognitive decline and increased oxidative stress. The aim of this study was to investigate the potentials of Lactobacillus plantarum DR7 on brain health including cognitive and memory functions during aging and the impacts of high fat diet during a 12-week period. Male Sprague-Dawley rats were separated into six groups: (1) young animals on normal diet (ND, (2) young animals on a high fat diet (HFD), (3) aged animals on ND, (4) aged animals on HFD, (5) aged animals on HFD and L. plantarum DR7 (10⁹ cfu/day) and (6) aged animals receiving HFD and lovastatin. To induce ageing, all rats in group 3 to 6 were injected sub-cutaneously at 600 mg/kg/day of D-galactose daily. The administration of DR7 has reduced anxiety accompanied by enhanced memory during behavioural assessments in aged-HFD rats (P<0.05). Hippocampal concentration of all three pro-inflammatory cytokines were increased during aging but reduced upon administration of both statin and DR7. Expressions of hippocampal neurotransmitters and apoptosis genes showed reduced expressions of indoleamine dioxygenase and P53 accompanied by increased expression of TPH1 in aged- HFD rats administered with DR7, indicating potential effects of DR7 along the pathways of serotonin and oxidative senescence. This study provided an insight into potentials of L. plantarum DR7 as a prospective dietary strategy to improve cognitive functions during aging. This study provided an insight into potentials of L. plantarum DR7 as a prospective dietary strategy to improve cognitive functions during aging.

The molecular mechanisms of probiotic strains in improving ageing bone and muscle of d-galactose-induced ageing rats

AIM

The aim of this study was to evaluate the molecular mechanisms of Lactobacillus strains in improving ageing of the musculoskeletal system.

METHODS AND RESULTS

The anti-ageing mechanism of three probiotics strains Lactobacillus fermentum DR9, Lactobacillus paracasei OFS 0291 and L. helveticus OFS 1515 were evaluated on gastrocnemius muscle and tibia of d-galactose-induced ageing rats. Upon senescence induction, aged rats demonstrated reduced antioxidative genes CAT and SOD expression in both bone and muscle compared to the young rats (P < 0·05). Strain L. fermentum DR9 demonstrated improved expression of SOD in bone and muscle compared to the aged rats (P < 0·05). In the evaluation of myogenesis-related genes, L. paracasei OFS 0291 and L. fermentum DR9 increased the mRNA expression of IGF-1; L. helveticus OFS 1515 and L. fermentum DR9 reduced the expression of MyoD, in contrast to the aged controls (P < 0·05). Protective effects of L. fermentum DR9 on ageing muscle were believed to be contributed by increased AMPK-α2 expression. Among the osteoclastogenesis genes studied, TNF-α expression was highly elevated in tibia of aged rats, while all three probiotics strains ameliorated the expression. Lactobacillus fermentum DR9 also reduced the expression of IL-6 and TRAP in tibia when compared to the aged rats (P < 0·05). All probiotics treatment resulted in declined proinflammatory cytokines IL-1β in muscle and bone.

CONCLUSIONS

Lactobacillus fermentum DR9 appeared to be the strongest strain in modulation of musculoskeletal health during ageing.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study demonstrated the protective effects of the bacteria on muscle and bone through antioxidative and anti-inflammatory actions. Therefore, L. fermentum DR9 may serve as a promising targeted anti-ageing therapy.

Lactobacillus probiotics improved the gut microbiota profile of a Drosophila melanogaster Alzheimer's disease model and alleviated neurodegeneration in the eye

Alzheimer's disease (AD) is a progressive disease and one of the most common forms of neurodegenerative disorders. Emerging evidence is supporting the use of various strategies that modulate gut microbiota to exert neurological and psychological changes. This includes the utilisation of probiotics as a natural and dietary intervention for brain health. Here, we showed the potential AD-reversal effects of Lactobacillus probiotics through feeding to our Drosophila melanogaster AD model. The administration of Lactobacillus strains was able to rescue the rough eye phenotype (REP) seen in AD-induced Drosophila, with a more prominent effect observed upon the administration of Lactobacillus plantarum DR7 (DR7). Furthermore, we analysed the gut microbiota of the AD-induced Drosophila and found elevated levels of Wolbachia. The administration of DR7 restored the gut microbiota diversity of AD-induced Drosophila with a significant reduction in Wolbachia's relative abundance, accompanied by an increase of Stenotrophomonas and Acetobacter. Through functional predictive analyses, Wolbachia was predicted to be positively correlated with neurodegenerative disorders, such as Parkinson's, Huntington's and Alzheimer's diseases, while Stenotrophomonas was negatively correlated with these neurodegenerative disorders. Altogether, our data exhibited DR7's ability to ameliorate the AD effects in our AD-induced Drosophila. Thus, we propose that Wolbachia be used as a potential biomarker for AD.

Lactobacilli modulated AMPK activity and prevented telomere shortening in ageing rats

This study aimed to evaluate the anti-ageing effects of different strains of lactobacilli putative probiotics on an ageing rat model as induced by D-galactose and a high fat diet. Male Sprague-Dawley rats were fed with high fat diet (54% kcal fat) and injected with D-galactose daily for 12 weeks to induce ageing. The effects of putative probiotic strains on age-related impairment such as telomere length, plasma lipid peroxidation, hepatic 5'adenosine monophosphate-activated protein kinase (AMPK) expression, as well as endurance performance were evaluated. Administration of statin, Lactobacillus plantarum DR7 (LP-DR7), Lactobacillus fermentum DR9 (LF-DR9), and Lactobacillus reuteri 8513d (LR-8513d) significantly reduced the shortening of telomere and increased the expression of AMPK subunit-α1 (P<0.05). Plasma lipid peroxidation was lower (P<0.05) in groups administered with statin and LF-DR9 as compared to the control. AMPK subunit-α2 was elevated in rats administered with LP-DR7 as compared to the control (P<0.05). Using an in vivo ageing rat model, the current study has illustrated the potentials of lactobacilli putative probiotics in alleviation of age-related impairment in a strain-dependent manner.