Application advances of habitat imaging based on CT or PET/CT: a systematic review.

BACKGROUND: Habitat imaging (HI) enables the identification of tumor heterogeneity and characterization of the tumor microenvironment. Although HI based on MRI is well-established, its implementation using CT or PET/CT remains nascent and underexplored. OBJECTIVE: This systematic review analyzes recent advances in HI based on CT or PET/CT for tumor diagnosis and treatment, evaluating its clinical utility and limitations. METHODS: Literatures were systematically searched in PubMed, Embase, Web of Science, and Cochrane Library. Study quality was assessed using the radiomics quality score (RQS). RESULTS: A total of 21 studies comprising 7363 patients were included. The number of radiomic features extracted ranged from 41 to 12,838 across studies. Cancer types included lung (47.6%), head and neck (14.3%), renal (14.3%), gastrointestinal (9.5%), ovarian (9.5%), and liver (4.8%). All included studies were retrospective in design. The mean RQS was 15.71 ± 3.06. Common limitations included the absence of scanner simulation studies, prospective validation, cost-effectiveness analyses, and data/code sharing. Furthermore, substantial heterogeneity was observed across studies in terms of image acquisition, segmentation methods, and habitat definitions. CONCLUSION: HI based on CT or PET/CT demonstrates preliminary potential in evaluating treatment response, predicting prognosis, and revealing tumor pathological and molecular characteristics. However, the current evidence is of low-to-moderate quality with a risk of bias, and considerable methodological heterogeneity exists. The overall body of evidence remains at a relatively early stage. Prospective studies are needed to validate HI as a clinical biomarker.