In-vivo X-ray dark-field computed tomography for the detection of radiation-induced lung damage in mice

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Radiation-induced lung damage was observed using X-ray dark-field tomography.

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In this pre-clinical study, mouse lungs were irradiated and subsequently imaged.

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We report increased sensitivity of X-ray dark-field tomography over absorption-based tomography.

Background and Purpose

Radiotherapy of thoracic tumours can lead to side effects in the lung, which may benefit from early diagnosis. We investigated the potential of X-ray dark-field computed tomography by a proof-of-principle murine study in a clinically relevant radiotherapeutic setting aiming at the detection of radiation-induced lung damage.

Material and Methods

Six mice were irradiated with 20 Gy to the entire right lung. Together with five unirradiated control mice, they were imaged using computed tomography with absorption and dark-field contrast before and 16 weeks post irradiation. Mean pixel values for the right and left lung were calculated for both contrasts, and the right-to-left-ratio R of these means was compared. Radiologists also assessed the tomograms acquired 16 weeks post irradiation. Sensitivity, specificity, inter- and intra-reader accuracy were evaluated.

Results

In absorption contrast the group-average of R showed no increase in the control group and increased by 7% (p = 0.005) in the irradiated group. In dark-field contrast, it increased by 2% in the control group and by 14% (p = 0.005) in the irradiated group. Specificity was 100% for both contrasts but sensitivity was almost four times higher using dark-field tomography. Two cases were missed by absorption tomography but were detected by dark-field tomography.

Conclusions

The applicability of X-ray dark-field computed tomography for the detection of radiation-induced lung damage was demonstrated in a pre-clinical mouse model. The presented results illustrate the differences between dark-field and absorption contrast and show that dark-field tomography could be advantageous in future clinical settings.

In Silico Ventilation Within the Dose-Volume is Predictive of Lung Function Post-radiation Therapy in Patients with Lung Cancer

Lung cancer is a leading cause of death worldwide. Radiation therapy (RT) is one method to treat this disease. A common side effect of RT for lung cancer is radiation-induced lung damage (RILD) which leads to loss of lung function. RILD often compounds pre-existing smoking-related regional lung function impairment. It is difficult to predict patient outcomes due to large variability in individual response to RT. In this study, the capability of image-based modelling of regional ventilation in lung cancer patients to predict lung function post-RT was investigated. Twenty-five patient-based models were created using CT images to define the airway geometry, size and location of tumour, and distribution of emphysema. Simulated ventilation within the 20 Gy isodose volume showed a statistically significant negative correlation with the change in forced expiratory volume in 1 s 12-months post-RT (p = 0.001, R = - 0.61). Patients with higher simulated ventilation within the 20 Gy isodose volume had a greater loss in lung function post-RT and vice versa. This relationship was only evident with the combined impact of tumour and emphysema, with the location of the emphysema relative to the dose-volume being important. Our results suggest that model-based ventilation measures can be used in the prediction of patient lung function post-RT.

Long term radiological features of radiation-induced lung damage

PURPOSE

To describe the radiological findings of radiation-induced lung damage (RILD) present on CT imaging of lung cancer patients 12 months after radical chemoradiation.

MATERIAL AND METHODS

Baseline and 12-month CT scans of 33 patients were reviewed from a phase I/II clinical trial of isotoxic chemoradiation (IDEAL CRT). CT findings were scored in three categories derived from eleven sub-categories: (1) parenchymal change, defined as the presence of consolidation, ground-glass opacities (GGOs), traction bronchiectasis and/or reticulation; (2) lung volume reduction, identified through reduction in lung height and/or distortions in fissures, diaphragm, anterior junction line and major airways anatomy, and (3) pleural changes, either thickening and/or effusion.

RESULTS

Six patients were excluded from the analysis due to anatomical changes caused by partial lung collapse and abscess. All remaining 27 patients had radiological evidence of lung damage. The three categories, parenchymal change, shrinkage and pleural change were present in 100%, 96% and 82% respectively. All patients had at least two categories of change present and 72% all three. GGOs, reticulation and traction bronchiectasis were present in 44%, 52% and 37% of patients.

CONCLUSIONS

Parenchymal change, lung shrinkage and pleural change are present in a high proportion of patients and are frequently identified in RILD. GGOs, reticulation and traction bronchiectasis are common at 12 months but not diagnostic.

Subjective Global Assessment (SGA) Score Could Be a Predictive Factor for Radiation Pneumonitis in Lung Cancer Patients With Normal Pulmonary Function Treated by Intensity-Modulated Radiation Therapy and Concurrent Chemotherapy

INTRODUCTION

To investigate the relationship between malnutrition and the severity of radiation pneumonitis (RP) in patients with lung cancer with normal baseline pulmonary function and lungs' V20 < 35% treated by intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy.

MATERIALS AND METHODS

A total of 150 patients with lung cancer who received definitive IMRT (≥ 60 Gy) and concurrent chemotherapy were enrolled. In the condition of normal baseline pulmonary function and strict constraints of the irradiation dose to normal lung tissues, we recorded Eastern Cooperative Oncology Group score; concurrent chemotherapy; clinical stage; the level of albumin (ALB), hemoglobin, and C-reactive protein; Subjective Global Assessment (SGA) scores; radiation esophagitis grade; V20 of lungs; and mean lung dose. These factors were correlated with RP using univariate and multivariate regression analyses.

RESULTS

Of 150 patients, 12 patients (8.0%) developed Grade 3 to 5 RP, 37 (24.6%) patients developed grade 3 to 5 esophageal toxicity. In univariate analysis, ALB level (P = .002), radiation esophagitis (P < .001), and SGA score (P < .001) were significantly associated with RP. Multivariate analysis revealed that SGA (P < .001) was the independent predictor of RP.

CONCLUSIONS

SGA could be a predictor for RP in patients with lung cancer treated with definitive IMRT and concurrent chemotherapy.

Nintedanib reduces radiation-induced microscopic lung fibrosis but this cannot be monitored by CT imaging: A preclinical study with a high precision image-guided irradiator

BACKGROUND

Nintedanib has anti-fibrotic and anti-inflammatory activity and is approved for the treatment of idiopathic pulmonary fibrosis. The aim of this study was to noninvasively assess the efficacy of nintedanib in a mouse model of partial lung irradiation to prevent radiation-induced lung damage (RILD).

METHODS

266 C57BL/6 adult male mice were irradiated with a single radiation dose (0, 4, 8, 12, 16 or 20Gy) using parallel-opposed fields targeting the upper right lung using a precision image-guided small animal irradiator sparing heart and spine based on micro-CT images. One week post irradiation, mice were randomized across nintedanib daily oral gavage treatment (0, 30 or 60mg/kg). CT density analysis of the lungs was performed on monthly acquired micro-CT images. After 39weeks, lungs were processed to evaluate the fibrotic phenotype.

RESULTS

Although the CT density increase correlated with the radiation dose, nintedanib did not influence this relationship. Immunohistochemical analysis confirmed the ability of nintedanib to reduce the microscopic fibrotic phenotype, in particular interstitial edema, interstitial and perivascular fibrosis and inflammation, and vasculitis.

CONCLUSIONS

Nintedanib reduces radiation-induced lung fibrosis after partial lung irradiation without adverse effects, however, noninvasive CT imaging measuring electron density cannot be applied for monitoring its effects.