Mn-DPDP-enhanced MR Imaging: the Optimal Pulse Sequence for Detection of Focal Hepatic Tumor

Youk, Ji Hyun; Lee, Jeong Min; Kim, In Hwan; Chung, Gyung Ho; Lee, Seung Ok; Kim, Dae Kon; You, Hee Cheol; Cho, Back Hwan; Kim, Chong Soo

Abstract

PURPOSE
To assess the diagnostic value of Mn-DPDP for the detection of focal hepatic tumors on MR images and to determine the optimal pulse sequence to maximize its effect.
MATERIALS AND METHODS
Twenty-three patients with 32 focal hepatic tumors were examined by means of 1.5-T MRI. Before and after the intravenous administration of Mn-DPDP, five pulse sequences were used to obtain T1-weighted images: two-dimensional fast low-angle shot (2D FLASH) with/without fat saturation (FS), spinecho (SE), and three-dimensional fast low angle shot reconstruction (3D FLASH) with/without FS. Quantitative assessment involved determination of the signal-to-noise ratio (SNR) of the liver and the tumor, the percentage signal enhancement ratio (PSER) of the liver, and tumor-to-liver contrast to noise ratio (CNR). Pulse sequences were also evaluated subjectively for tumor conspicuity, delineation, and image artifact. In addition, two experienced radiologists compared tumor detection rates between precontrast and postcontrast images.
RESULTS
Mn-DPDP had a marked effect on liver SNR and absolute CNR at all pulse sequences (p<0.05). On postcontrast images, PSER and absolute CNR of the liver were highest at 3D FLASH and 2D FLASH FS, respectively, and significantly higher at GRE than at SE (p<0.05). On postcontrast images, the CNR of focal nodular hyperplasia and hepatocellular carcinoma was positive, while that of hemangioma, metastasis and cholangiocarcinoma was negative. The postcontrast CNR of all tumors except hepatocellular carcinoma increased more than 100%. Qualitative studies showed that tumor conspicuity increased significantly at all sequences except SE, and delineation increased significantly except at SE and postcontrast 2D GRE FS. After Mn-DPDP, GRE more effectively demonstrated tumor conspicuity and image artifact than did SE, and GRE other than 2D FLASH FS was also better than SE for tumor dilineation (p<0.05). The sensitivity of all postcontrast images increased and the tumor detection rate at GRE was significantly higher than at SE.
CONCLUSION
Mn-DPDP favorably affects tumor-to-liver contrast, and may be useful in the imaging of focal hepatic tumors, more so with 2D or 3D FLASH pulse sequences than with SE.