A review of the literature shows that pile integrity is a significant concern in pile construction; in particular, determining the location and nature of anomalies along the depth of the piles using thermal integrity testing data. This paper proposes a new anomaly detection approach which combines early-age temperature monitoring data and finite element back-analyses. A case study on a continuous flight auger (CFA) test pile with engineered inclusions was conducted using this new approach. Through 1D finite element analysis, a linear relationship between maximum temperature and effective pile radius is established. A crucial indicator – ‘the effective pile radius’ could be used to reconstruct as-built pile 3D shape and identify anomalous regions inside or outside the pile reinforcement cage. The data interpretation results of the field case study show that thermal integrity testing provides reliable information to identify anomalous regions within the pile. Compared to the conventional cross-hole sonic logging, thermal integrity testing used in combination with the new approach presented in this paper, can provide more reliable information in the pile integrity assessment process.