Evaluation of sustainable diagnostic approaches in metastatic breast cancer (MBC).

Introduction: Assessing bone metastases in metastatic breast cancer is challenging. Due to rising concerns over energy use and emissions, energy-efficient imaging is essential. This study aimed to compare three diagnostic imaging approaches used in therapy monitoring of MBC patients, evaluating both their environmental impact-quantified by energy consumption and related greenhouse gas emissions-and their biological cost, defined as patient exposure to ionizing radiation and contrast media volume.

Methods: We retrospectively analysed 70 patients with bone-dominant metastatic breast cancer who underwent WB-MRI (DL1) and either FDG-PET/CT (DL2) or bone scintigraphy (BS) with CT of chest, abdomen, and pelvis (CT-CAP) (DL3). We compared scan time, energy consumption, greenhouse gas emissions (kgCO2e), radiation dose, and contrast media usage across these diagnostic pathways. Energy consumption was calculated using protocol-defined active and idle phases, while biological exposure was assessed from institutional RIS-PACS records.

Results: DL1 had the highest energy consumption (10.36 ± 0.11 kWh/patient) and GHG emissions (2.53 ± 0.03 kgCO2e). DL2 showed moderate energy use (4.08 ± 0.38 kWh/patient) and GHG emissions (0.99 ± 0.09 kgCO2e), which significantly increased with repeat scans. DL3 exhibited the lowest environmental impact (7.60 ± 1.07 kWh; 1.85 ± 0.26 kgCO2e), though required multiple visits and higher contrast media and radiation doses.

Conclusion: WB-MRI offers a biologically safer alternative for treatment monitoring in metastatic breast cancer, yet its environmental footprint is substantial. FDG-PET/CT represents a more sustainable imaging option if repeated scans are minimized. Integrated imaging pathways and low-energy technologies should guide future diagnostic strategies.