Radiation injury vs. recurrent brain metastasis: combining textural feature radiomics analysis and standard...

We investigated the potential of textural feature analysis of O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (¹⁸F-FET) PET to differentiate radiation injury from brain metastasis recurrence.

Forty-seven patients with contrast-enhancing brain lesions (n = 54) on MRI after radiotherapy of brain metastases underwent dynamic ¹⁸F-FET PET. Tumour-to-brain ratios (TBRs) of ¹⁸F-FET uptake and 62 textural parameters were determined on summed images 20-40 min post-injection. Tracer uptake kinetics, i.e., time-to-peak (TTP) and patterns of time-activity curves (TAC) were evaluated on dynamic PET data from 0-50 min post-injection. Diagnostic accuracy of investigated parameters and combinations thereof to discriminate between brain metastasis recurrence and radiation injury was compared.

Diagnostic accuracy increased from 81 % for TBR_mean alone to 85 % when combined with the textural parameter Coarseness or Short-zone emphasis. The accuracy of TBR_max alone was 83 % and increased to 85 % after combination with the textural parameters Coarseness, Short-zone emphasis, or Correlation. Analysis of TACs resulted in an accuracy of 70 % for kinetic pattern alone and increased to 83 % when combined with TBR_max.

Textural feature analysis in combination with TBRs may have the potential to increase diagnostic accuracy for discrimination between brain metastasis recurrence and radiation injury, without the need for dynamic ¹⁸F-FET PET scans.

• Textural feature analysis provides quantitative information about tumour heterogeneity • Textural features help improve discrimination between brain metastasis recurrence and radiation injury • Textural features might be helpful to further understand tumour heterogeneity • Analysis does not require a more time consuming dynamic PET acquisition.