Dataset Information

Oxygen-Sensitive MRI: A Predictive Imaging Biomarker for Tumor Radiation Response?

ABSTRACT:

Purpose

To develop a noninvasive prognostic imaging biomarker related to hypoxia to predict SABR tumor control.

Methods and materials

A total of 145 subcutaneous syngeneic Dunning prostate R3327-AT1 rat tumors were focally irradiated once using cone beam computed tomography guidance on a small animal irradiator at 225 kV. Various doses in the range of 0 to 100 Gy were administered, while rats breathed air or oxygen, and tumor control was assessed up to 200 days. Oxygen-sensitive magnetic resonance imaging (MRI) (T₁-weighted, ΔR₁, ΔR₂*) was applied to 79 of these tumors at 4.7 T to assess response to an oxygen gas breathing challenge on the day before irradiation as a probe of tumor hypoxia.

Results

Increasing radiation dose in the range of 0 to 90 Gy enhanced tumor control of air-breathing rats with a TCD₅₀ estimated at 59.6 ± 1.5 Gy. Control was significantly improved at some doses when rats breathed oxygen during irradiation (eg, 40 Gy; P < .05), and overall there was a modest left shift in the control curve: TCD₅₀(oxygen) = 53.1 ± 3.1 Gy (P < .05 vs air). Oxygen-sensitive MRI showed variable response to oxygen gas breathing challenge; the magnitude of T₁-weighted signal response (%ΔSI) allowed stratification of tumors in terms of local control at 40 Gy. Tumors showing %ΔSI >0.922 with O₂-gas breathing challenge showed significantly better control at 40 Gy during irradiation while breathing oxygen (75% vs 0%, P < .01). In addition, increased radiation dose (50 Gy) substantially overcame resistance, with 50% control for poorly oxygenated tumors. Stratification of dose-response curves based on %ΔSI >0.922 revealed different survival curves, with TCD₅₀ = 36.2 ± 3.2 Gy for tumors responsive to oxygen gas breathing challenge; this was significantly less than the 54.7 ± 2.4 Gy for unresponsive tumors (P < .005), irrespective of the gas inhaled during tumor irradiation.

Conclusions

Oxygen-sensitive MRI allowed stratification of tumors in terms of local control at 40 Gy, indicating its use as a potential predictive imaging biomarker. Increasing dose to 50 Gy overcame radiation resistance attributable to hypoxia in 50% of tumors.

SUBMITTER: Arai TJ

PROVIDER: S-EPMC8286313 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Publications

Oxygen-Sensitive MRI: A Predictive Imaging Biomarker for Tumor Radiation Response?

Arai Tatsuya J TJ Yang Donghan M DM Campbell James W JW Chiu Tsuicheng T Cheng Xinyi X Stojadinovic Strahinja S Peschke Peter P Mason Ralph P RP

International journal of radiation oncology, biology, physics 20210326 5

<h4>Purpose</h4>To develop a noninvasive prognostic imaging biomarker related to hypoxia to predict SABR tumor control.<h4>Methods and materials</h4>A total of 145 subcutaneous syngeneic Dunning prostate R3327-AT1 rat tumors were focally irradiated once using cone beam computed tomography guidance on a small animal irradiator at 225 kV. Various doses in the range of 0 to 100 Gy were administered, while rats breathed air or oxygen, and tumor control was assessed up to 200 days. Oxygen-sensitive m ...[more]

PMID: 33775857

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Project description:BackgroundThis prospective study tested the hypothesis that the apparent diffusion coefficient (ADC) value and tumor volume (TV) measured in diffusion-weighted magnetic resonance imaging (DW-MRI) before, during, and after the treatment are quantitative imaging markers to assess tumor response in muscle-invasive bladder cancer (MIBC) patients undergoing neoadjuvant chemotherapy (NAC).MethodsMulti-parametric MRI was prospectively done for MIBC patients at 3 time points. Pre-treatment ADC value, pre-treatment TV, as well as, percent of changes (ΔADC%, and ΔTV%) in these parameters at mid- and post-treatment relative to baseline were calculated and compared between the patients with and without clinical complete response (CR). Also, further analysis was carried out based on the groups of patients with and without overall response (OR). Two different methods of ADC estimation including single-slice ADC measurement (ADCsingle-slice) and whole-lesion ADC measurement (ADCwhole-lesion) were used.ResultsA total of 50 eligible patients were included in the analysis. Of these, 20 patients (40%) showed clinical CR to treatment, while 30 (60%) did not. Our results showed that although there was no significant difference between the two groups of patients with and without CR in terms of mid-treatment ΔADC% and mid-treatment ΔTV%, significant differences were observed in terms of the pre-treatment ADC (p < 0.01), pre-treatment TV (p < 0.001), post-treatment ΔADC% (p < 0.05), and post-treatment ΔTV% (p < 0.05). The results of the OR-based analysis were in line with the CR-based results. There was also a strong and significant correlation between ADCsingle-slice and ADCwhole-lesion measurements (r > 0.9, P < 0.001).ConclusionPre-treatment ADC, pre-treatment TV, post-treatment ΔADC%, and post-treatment ΔTV% could be considered as promising quantitative imaging markers of tumor response in MIBC patients undergoing NAC. Moreover, mid-treatment ΔADC% and mid-treatment ΔTV% should not be used as predictors of tumor response in these patients. Further larger studies are required to confirm these results.

Dataset Information

Oxygen-Sensitive MRI: A Predictive Imaging Biomarker for Tumor Radiation Response?

Purpose

Methods and materials

Results

Conclusions

Publications

Oxygen-Sensitive MRI: A Predictive Imaging Biomarker for Tumor Radiation Response?

Similar Datasets

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