科研之友
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摘要
Aim: We observed a layer between tumour activity and background on FDG PET/CT with the 10-step colour scale and the window level set properly. We named the layer peritumoral halo layer (PHL). We performed this study to establish the reliability of metabolic tumor volume (MTV) segmentation using PHL (MTVPHL) in patients with papillary thyroid carcinoma. Patients, methods: Of a total of 140 papillary thyroid carcinoma (PTC) patients, 70 (50.0%) had FDG-avid PTC. In these patients, MTVPHL, MTV segmented according to fixed 50% SUVmax (MTV50%), and fixed SUV with 2.5 to 4.0 (MTV2.5 to MTV4.0) were compared with pathologic tumour volume (PTV). The absolute percentage difference between MTVPHL and PTV was compared in micropapillary carcinoma (MPTC) and non-micropapillary carcinoma (non-MPTC) subgroups. The % SUVmax and SUV thresholds of MTVPHL were compared with tumour SUVmax. Results: Among the MTVs, MTV50% was not correlated with PTV (r = -0.16, p = 0.182) and was not reliable according to the Bland-Altman plot. Although MTV2.5, MTV3.0, MTV3.5, and MTV4.0 correlated with PTV (r = 0.85, 0.86, 0.87, and 0.87, respectively; p < 0.001), these MTVs were not reliable on Bland-Altman analyses. MTVPHL was significantly correlated with PTV (r = 0.80, p < 0.001), and the Bland-Altman plot did not show systemic error. The MTVPHL was more accurate in non-MPTC than in MPTC (p < 0.001), and the absolute % difference was smaller as PTV became larger (sigma = -0.65, p < 0.001). The MTVPHL thresholds had correlations with SUVmax (% SUVmax threshold: sigma = -0.87, p < 0.001; SUV threshold: r = 0.88, p < 0.001). Conclusions: MTVPHL was more reliable than MTV% (SUVmax) or MTVSUV. The reliability of MTVPHL improved with larger PTVs. The threshold of the MTVPHL was naturally altered by PHL according to SUVmax.
- 出版日期2015
