Guiding Radiotherapy Target Area Delineation by Gd-EOB-DTPA-Enhanced MRI

Purpose/Objective(s)

To compare the differences between the diameters and volumes of liver tumors measured with preoperative Gd-EOB-DTPA-enhanced MRI, enhanced CT and postoperative gross pathology specimens and to measure the hepatic lesion microinvasion range for accurate radiotherapy GTV delineation. This study also provides an important reference for CTV delineation.

Materials/Methods

Twenty-eight hepatocellular carcinoma (HCC) patients who underwent EOB-MRI and enhanced CT before surgery were enrolled. The results from EOB-MRI, enhanced CT and pathology were compared. The differences in GTV were calculated as V_MRI = G_MRI-G_P and V_CT = G_CT-G_P, and MI_MAX was the microinvasion distance around the tumor.

Results

The V_MRI was 5.90 ± 6.52 mm, and the mean V_CT was 11.40 ± 8.06 mm. The volume difference between MRI and pathological examinations was significantly smaller than that between CT and pathological examinations (P<0.05). Twenty-seven of the 28 patients had microscopic infiltration. The mean MI_MAX was 3.27±1.38 mm; thus, grade I MI_MAX < grade II MI_MAX < grade III MI_MAX < grade IV MI_MAX, and the differences were statistically significant (P<0.05).

Conclusion

EOB-MRI, enhanced CT and pathological GTV are comparable. GTVs delineated with EOB-MRI and enhanced CT can replace GTVs determined by pathology. The consistency between GTVs delineated by EOB-MRI and those delineated by pathology is high, and the GTVs delineated by EOB-MRI are more accurate than those delineated by enhanced CT; high-grade HCC requires a large boundary. The HCC boundary needs to be expanded by 5.97 mm to include 95% of the pathological microinvasions.