Correlation between Biological Effective Dose and Radiation-induced Liver Disease from Hypofractionated Radiotherapy

Background

The prevention of radiation-induced liver disease (RILD) is very significant in ensuring a safe radiation treatment and high quality of life.

Aims and Objectives

The purpose of this study is to investigate the correlation of physical and biological effective dose (BED) metrics with liver toxicity from hypo-fractionated liver radiotherapy.

Materials and Methods

41 hypo-fractionated patients in 2 groups were evaluated for classic radiation-induced liver disease (RILD) and chronic RILD, respectively. Patients were graded for effective toxicity (post-treatment minus pre-treatment) using the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Physical dose (PD) distributions were converted to BED. The V_10Gy, V_15Gy, V_20Gy, V_25Gy and V_30Gy physical dose-volume metrics were used in the analysis together with their respective BED-converted metrics of V_16.7Gy3, V_30Gy3, V_46.7Gy3, V_66.7Gy3 and V_90Gy3. All levels were normalized to their respective patient normal liver volumes (NLV) and evaluated for correlation to RILD. Results were measured quantitatively using R² regression analysis.

Results

The classic RILD group had median follow-up time of 1.9 months and the average PD-NLV normalized V_10Gy, V_15Gy, V_20Gy, V_25Gy and V_30Gy metrics per grade were plotted against RILD yielding R² correlations of 0.84, 0.72, 0.73, 0.65 and 0.70, respectively while the BED-volume metrics of V_16.7Gy3, V_30Gy3, V_46.7Gy3, V_66.7Gy3 and V_90Gy3 resulted in correlation values of 0.84, 0.74, 0.66, 0.78 and 0.74, respectively. BED compared to PD showed a statistically significant (p=.03) increase in R² for the classic RILD group. Chronic RILD group had median follow-up time of 12.3 months and the average PD-NLV normalized V_10Gy, V_15Gy, V_20Gy, V_25Gy and V_30Gy metrics per grade were plotted against RILD grade yielding R² correlations of 0.48, 0.92, 0.88, 0.90 and 0.99 while the BED-volume metrics of V_16.7Gy3, V_30Gy3, V_46.7Gy3, V_66.7Gy3 and V_90Gy3 resulted in correlation values of 0.43, 0.94, 0.99, 0.21 and 0.00, respectively.

Conclusion

The strong correlations of the V_10Gy and V_15Gy PD-volume metrics as well as the V_16.7Gy3 (BED of V_10Gy) to both classic and chronic RILD imply the appropriateness of the current 15_Gy evaluation level for liver toxicity with hypo-fractionated treatments.

P4353Global longitudinal strain is a measure of subclinical left ventricular dysfunction in chronic inflammatory autoimmune conditions

Background

Myocardial deformation indices are proposed to be a more sensitive marker of subclinical dysfunction compared to standard measures of left ventricular (LV) systolic function. We hypothesize that subclinical myocardial dysfunction is present in chronic inflammatory autoimmune diseases such as Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA), despite both conditions being mediated by different pro-inflammatory modulators.

Purpose

Identify subclinical myocardial dysfunction through assessment of global longitudinal strain in two different chronic autoimmune conditions, SLE and RA.

Methods

Consecutive patients admitted to our institution with known history of SLE or RA (>1 year disease activity) were examined. Patients with preexisting cardiac disease, LVEF <50% and those without comprehensive transthoracic echocardiograms (TTE) were excluded. Mean longitudinal LV strain was performed offline using vendor-independent software (TomTec v4.6) and compared to age- and gender-matched controls with normal LV function and no history of cardiac disease.

Results

Of the 86 patients examined (mean age 53.01±21.74, 85.4% female), 51 (59.3%) had SLE and 35 (40.7%) had RA. No significant difference in BMI, hypertension, hypercholesterolemia, diabetes, obesity, obstructive sleep apnea and stroke was observed between controls and patients with SLE or RA. While there was no significant difference in LVEF between RA patients and matched controls, there was a significantly lower GLS in the RA cohort. Conversely, patients with SLE had significantly lower LVEF and GLS when compared to matched controls, despite LVEF being in the normal range. See Table 1. Receiver operator curve analysis revealed that mean GLS is a better discriminator for autoimmune disease with an area under the curve of 0.829 (95% CI, 0.77 to 0.89; p<0.01) compared to LVEF with an area under the curve of 0.632 (95% CI, 0.55 to 0.72; p<0.01).

Echocardiographic Parameters SLE (n=51) Controls (n=51) Sig (p value) RA (n=35) Controls (n=35) Sig (p value) LVEDV (mls) 102±30 85±20 <0.01 84±28 89±30 0.43 LVESV (mls) 36±17 29±9 0.02 26±14 30±12 0.24 Biplane LVEF % 59±6 63±4 <0.01 62±6 62±5 0.81 LV Mass (grams/m2) 96±34 72±20 <0.01 79±26 82±23 0.67 LV Mean GLS % 16.7±2.8 21.3±2 <0.01 17.8±1.7 19.1±2.5 0.02

Conclusions

Our results suggest that chronic inflammatory conditions (SLE and RA) are associated with subclinical cardiac dysfunction. Impaired GLS may reflect early myocardial damage and be used as a tool for screening of patients with inflammatory conditions.

Acknowledgement/Funding

None

Habenula-prefrontal resting-state connectivity in reactive aggressive men - A pilot study

Disproportionate anger and reactive aggression in response to provocation are core symptoms of intermittent-explosive disorder (IED). Previous research shows a link between the propensity for aggression in healthy individuals and altered functioning of prefrontal-limbic and default-mode networks (DMN) at rest when no provocation is present. In a pilot study, we used resting-state functional magnetic resonance imaging to investigate the effects of pronounced reactive aggression in men, exemplified by IED, on the functional organization of resting-state brain networks including subcortical nodes such as the habenula previously implicated in aggression in preclinical models. Graph theory was applied to resting-state networks to determine alterations in global efficiency and clustering in high reactive aggressive men compared to low reactive aggressive men (controls). Further, we computed within-group correlations between trait aggression and graph measures, as well as within-group whole-brain seed-to-voxel regression analyses between trait aggression and habenula resting-state functional connectivity (rsFC). Reactive aggressive men compared to controls showed higher global efficiency in the left habenula, the left pulvinar in the thalamus, the left dorso-lateral prefrontal cortex, and the right temporal pole, as well as a trend for decreased clustering in DMN nodes. In the reactive aggressive group, high levels of trait aggression were linked to lower global efficiency of the left habenula, and to lower rsFC between the left habenula and the left ventro-lateral prefrontal cortex, a core region involved in inhibitory control. Together with preclinical evidence, our findings in men underline the relevance of aberrant habenula-prefrontal connectivity for the severity of aggressive behavior. This article is part of the Special Issue entitled 'Current status of the neurobiology of aggression and impulsivity'.