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Abstract Background Intratumoral heterogeneity means single site tumor biopsy might not be representative, leading to erroneous conclusions about tumor biology and therapy selection. Here we develop and optimize an MRI-informed multiregional biopsy technique in retroperitoneal and pelvic sarcomas (RPS). Methods Participants with suspected RPS underwent multiparametric (mp)MRI within a week prior to biopsy. Three ‘target regions’ with differing imaging characteristics were contoured. Robotic or freehand multiregional CT-guided biopsy (n = 6 each) was performed between September 2021 and September 2022, collecting samples separate specimen pots for each target region. CT/MRI fusion extracted quantitative imaging biomarkers at precise biopsy sites for correlation with histological biomarkers. The primary endpoint was safety and feasibility. Spearman's correlation was performed for imaging/histological biomarkers. Results Twelve participants (7 women), median age 58.6 years interquartile range IQR: 52–75 years underwent biopsy. All procedures were technically successful with same-day discharge and no complications. While absolute values of ADC and %Ki-67 did not correlate (Spearman’s ρ = -0.08), we observed a very strong correlation between the range of ADC values and the range of Ki-67 proliferation index values across biopsy sites; Spearman’s ρ = 0.93 (95% CI 0.74 to 0.98). Ranges, which represent intratumoral heterogeneity, can only be obtained using multiregional biopsy. Conclusions Multiregional MRI-informed, CT-guided biopsy is feasible and can be safely carried out using freehand and robotic guidance. Sampling three distinct regions within tumors provides a more comprehensive and accurate representation of tumor biology compared to conventional single-site biopsy. Ethical approval A phase I/IIa institutional review board approved prospective development study, identifier 1102, 17/06/2021.
Johnston et al. (Mon,) studied this question.