Aim: The aim of this study was to evaluate the inter-examinational, intra-observer and inter-observer reproducibility of three dimensional (3D) power Doppler ultrasonography (US) with the virtual organ computer-aided analysis (VOCAL) program for measuring thyroid volume, mean gray value (MG) and vascular indices in patients with thyroid nodules.
Patients and Methods: Patients had thyroid nodules with diameters range form 0.5 to 3 cm, clear margin and scanty cystic part, without history of thyroidectomy, were examined by 3DUS (V730, GE) from March 2008 to June 2008. The thyroid volume, MG and vascular indices: vascularization index (VI), flow index (FI), vascularization–flow index (VFI) were obtained from the VOCAL program. Inter-examinational reproducibility intra-observer and inter-observer reproducibility were presented as inter-examinational-class correlation coefficient (inter-examin-CC), intra-class correlation coefficient (intra-CC) and inter-class correlation coefficient (inter-CC). Values greater than 0.70 were considered as acceptable.
Results: Totally 38 patients with 44 nodules were included. Twenty nodules were examined with two times’ 3DUS examination. The values of inter-examin-CC of volume, MG, VI, VFI were larger than 0.9323; otherwise, FI was 0.8162 with wide 95% CI 0.5984-0.9224. For evaluating total 44 thyroid nodules, thyroid volume showed excellent intra-observer and inter-observer reproducibility (intra-CC> 0.9677 and inter-CC: 0.8533). MG, VI and VFI also showed excellent reproducibility (intra-CC > 0.9921 and inter-CC > 0.9592). The values of intra-CC of FI were larger than 0.8983 but small inter-CC value (0.5112).
Conclusion: Base on this study, 3DUS with the VOCAL program is a reproducible tool, except FI, for evaluating thyroid nodules.