Evaluation of contrast-enhanced CT value in the diagnosis of giant cell tumor

Abstract

Objective To evaluate the contrast-enhanced CT value in the diagnosis of giant cell tumor. Methods From 2461 bone tumors and tumor-like lesions with contrast enhanced CT,408 osteolytic lesions were selected and analyzed retrospectively.Three ROI were selected for every lesion,then the average post-contrast CT value and averageΔCT value of every lesion were calculated by two observers independently.Thirty lesions which were randomly selected from the 408 lesions were measured by two doctors to assess the overall precision of measurements.Contrast agents Iohexol (350 mg I/ml),Iopromide (370 mg I/ml) and Iobitridol (350 mg I/ml) were recorded in 148 GCT and 408 osteolytic lesions.The two observed values were analyzed respectively by using the One-way ANOVA.The 408 lesions were divided into giant cell tumor (GCT) and non-giant cell tumor (non-GCT) according to pathological results,and ROC curve analysis was carried out to get the cutoff values for the diagnosis of GCT and their sensitivity,specificity were determined. Results There was no significant difference of the average post contrast CT values between two observers (t=0.178,P>0.05),nor the averageΔCT values (t=0.682,P>0.05),and the overall precision was 11.94%.There was no significant difference amongst the three groups average post contrast CT values (126.41±27.13),(128.90±23.12),(127.61±23.02) HU for the 142 giant cell tumors (F=0.10,P>0.05),nor the averageΔCT values (82.72±24.83),(81.94±21.71),(84.06±19.45) HU (F=0.05,P>0.05).There was no significant difference amongst the three groups average post contrast CT values (99.15±36.44),(107.08±39.28),(105.75±31.17) HU for the 408 lesions (F=1.905,P>0.05),nor the averageΔCT values (58.63±33.23),(64.40±36.38),(63.04±28.50) HU (F=1.149,P>0.05).The average post contrast CT values of GCT and non-GCT were (127.05±25.69) and (88.07±34.08) HU respectively; The averageΔCT values of GCT and non-GCT were (82.78±23.38) and (48.43±31.68) HU respectively.If average post contrast CT value≥96.5 HU was used as cutoff value,the sensitivity and specificity for the diagnosis of GCT were 89.44% and 62.41% respectively.If averageΔCT value≥41.5 HU was chosen,then the sensitivity and specificity were 98.59% and 48.12% respectively. Conclusion The cutoff values were≥96.5 HU for average post contrast CT value and≥41.5 HU for averageΔCT value in the diagnosis of GCT,which both had high sensitivity and low specificity,and averageΔCT value<41.5 HU was helpful to exclude the diagnosis of GCT. Key words: Osteoblastoma; Diagnosis; Tomography,X-ray computed