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Feasibility of measuring the T1 relaxation times before and after Gd-EOB-DTPA administration for characterization of liver tumors
Yoshihiko Fukukura1, Takashi Iwanaga2, Yuichi Kumagae1, Hiroto Hakamada1, Koji Takumi1, Kiyohisa Kamimura1, Masanoari Nakajo1, Hiroshi Imai3, and Takashi Yoshiura1

1Radiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan, 2Radiological Technology, Kagoshima University Hospital, Kagoshima, Japan, 3Siemens Healthcare K.K., Tokyo, Japan

Synopsis

This study focused on the potential of T1 relaxation times measurement before and 20 min after Gd-EOB-DTPA administration to characterize liver tumors. T1 relaxation before Gd-EOB-DTPA administration showed the highest area under the receiver operating characteristic (ROC) curve for distinguishing hemangiomas and HCCs. T1 relaxation times 20 min after Gd-EOB-DTPA administration showed the highest the area under the ROC curve for differentiating HCCs from metastases. ΔR1 was considered to be useful for differentiation between hemangiomas and metastases because of the highest the area under the ROC curve.

Purpose

Diagnosing liver tumors including hemangiomas, hepatocellular carcinomas (HCCs), and metastases has obvious clinical importance. Gd-EOB-DTPA is an increasingly used MRI contrast agent that has the combined properties of an extracellular space and a liver specific contrast agents. Visual analysis is commonly performed for Gd-EOB-DTPA-enhanced MRI as well as the combination of T1- and T2-weighted images. Although qualitative analysis alone can be an effective method for diagnosing tumors, it is somewhat dependent on interpreter experience and is limited by subjective assessments. Unlike MR signal intensity that is affected by many technical factors, T1 or T2 relaxation time is an absolute value and is unaffected by these factors. Measurement of the T1 relaxation time in a tumor before and after Gd-EOB-DTPA administration allows quantitative evaluation of Gd-EOB-DTPA uptake, which potentially reveals related properties of the tumor (1, 2). However, the usefulness of T1 relaxation times before and 20 min after Gd-EOB-DTPA administration for characterization of liver tumors has not been elucidated. Therefore, the purpose of this study was to evaluate the feasibility of T1 relaxation times before and 20 min after Gd-EOB-DTPA administration for characterization of liver tumors.

Methods

This study population comprised 68 patients (37 men and 31 women; mean age, 66.0 years; age range, 18–85 years) with 14 hemangiomas (mean size, 38.9 mm; range, 10–129 mm), 35 HCCs (mean size, 34.1 mm; range, 11–90 mm), and 22 metastases (mean size, 22.5 mm; range, 10–70 mm), who underwent 3D T1-weighted volumetric interpolated breath-hold examination at two different flip angles (3° and 17°) for T1 maps with B1 correction before and 20 min after Gd-EOB-DTPA administration. The T1 map of the liver was automatically obtained by using the MapIT processing tool. The processing tool is based on the driven equilibrium single pulse observation of T1 (3). We compared the T1 relaxation times before (T1pre), 20 min after Gd-EOB-DTPA injection (T120min), and ΔR1 within hemangiomas, HCCs, and metastases using Kruskal-Wallis test, followed by the Mann-Whitney U test. Receiver operating characteristic (ROC) analysis was also carried out to assess for differentiation between hemangimas, HCCs and metastases.

Results

Table 1 shows T1pre, T120min, and ΔR1 of the liver, hemangiomas, HCCs, and metastases. T1pre values of HCCs were significantly lower than those of hemangiomas (P < 0.001) and metastases (P < 0.001). Hemangiomas showed significantly higher T1pre values than metastases (P = 0.013). HCCs showed significantly lower T120min than hemangiomas (P < 0.001) and metastases (P<0.001), but no significant difference was obtained between hemangiomas and metastases (P = 0.270). ΔR1 of metastases was significantly lower than those of hemangiomas (P = 0.001) and HCCs (P < 0.001), but no significant difference was observed between hemangiomas and HCCs (P = 0.199). For differentiating hemangiomas and HCCs, T1pre showed the highest area under the ROC curve (0.957; 95% CI: 0.857, 0.994). T120min showed the highest area under the ROC curve for differentiating HCCs and metastases (0.930; 95% CI: 0.830, 0.981). ΔR1 showed the highest area under the ROC curve for differentiating hemangiomas and metastases (0.821; 95% CI: 0.658, 0.929).

Discussion

T1pre and T120min values of HCCs were significantly lower than those of metastases and hemangiomas, and were closer to those of the liver. These results may be attributable to similarities in cell morphology and function of HCCs to the liver. Our ROC analysis suggested that T1pre and T120min are useful for differentiation between hemangiomas and HCCs, and between HCCs and metastases, respectively. ΔR1 values of HCCs were significantly higher than those of metastases. This result can be explained by the fact that HCC has preserved specific intracellular uptake of Gd-EOB-DTPA. ΔR1 values of hemangiomas were significantly higher than those of metastases, and were equal to those of HCCs. This can be attributable to a large amount of dilated sinusoidal spaces within hemangiomas where pooling of Gd-EOB-DTPA occurs. ΔR1 might be the most useful parameter for differentiation between hemangiomas and metastases because of the highest the area under the ROC curve.

Conclusion

T1 relaxation times before and 20 min after Gd-EOB-DTPA administration could help characterize liver tumors.

Acknowledgements

No acknowledgement found.

References

1. Kitao A, Matsui O, Yoneda N, et al. The uptake transporter OATP8 expression decreases during multistep hepatocarcinogenesis: correlation with gadoxetic acid enhanced MR imaging. Eur Radiol 2011; 21:2056-66.

2. Peng Z, Jiang M, Cai H et al. Gd-EOB-DTPA-enhanced magnetic resonance imaging combined with T1 mapping predicts the degree of differentiation in hepatocellular carcinoma. BMC cancer 2016; 164:e625.

3. Kang Y, Choi SH, Kim YJ, et al. Gliomas: histogram analysis of apparent diffusion coefficient maps with standard-or high-b-value diffusion-weighted MR imaging: correlation with tumor grade. Radiology 2011; 261:882-890.

Figures

Table 1. T1pre, T120min, and ΔR1 of the liver, hemangiomas, HCCs, and metastases

Proc. Intl. Soc. Mag. Reson. Med. 25 (2017)
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