For a study, researchers sought to evaluate the MRI’s cost-effectiveness in active surveillance (AS) protocols for a study. For men with low-risk cancer diagnoses, a probabilistic microsimulation was used to estimate individual patient trajectories. Investigators evaluated AS procedures, including transrectal ultrasound-guided (TRUS) biopsy or MRI-based regimens at serial intervals, up-front therapy (surgery or radiation), and no surveillance. The estimated net monetary benefit at $50,000/quality-adjusted life-year and incremental cost-effectiveness ratios were calculated using lifetime quality-adjusted life-years and expenses adjusted to 2020 US dollars. Probabilistic sensitivity analysis and linear regression metamodeling were used to evaluate uncertainty. In a modelled cohort matching characteristics from a multi-institutional trial, conservative care with AS did better than upfront definitive treatment. The biggest projected net financial advantage came from a biopsy decision made contingent on positive imaging (MRI triage) at 2-year intervals (incremental cost-effectiveness ratio: $44,576). The TRUS biopsy-based regimens and biopsy following positive and negative imaging (MRI route) were not cost-effective. Fewer biopsies were performed due to MRI triage, whereas the incidence of metastatic illness or cancer death was decreased. Results were highly dependent on test efficiency and price. According to a statistical sensitivity analysis, MRI triage was the most likely cost-effective option. Their modelling showed that AS with sequential MRI triage was more cost-effective than biopsy for men with low-risk prostate cancer, regardless of imaging, TRUS biopsy alone, or rapid therapy. The imaging function should be highlighted in AS guidelines, and prospective studies should be promoted.