Hypervascularity during the arterial phase (wash-in) and subsequent wash-out are the hallmark findings of HCCs. The Organ Procurement and Transplantation Network/United Network for Organ Sharing criteria are used for the standardized management of liver transplantation in the US, and require a ring-like enhancement called the capsule in PVP/delayed phase images for the definitive diagnosis of small HCCs (1–2 cm in diameter)1). Gadoxetic acid is a liver-specific contrast agent, which is useful for detecting small or early stage HCCs. However, a capsule is not always visualized by gadoxetic acid-enhanced MRI, since the liver parenchyma is already well enhanced in PVP, obscuring capsular enhancement. Capsular enhancement occurs via transarterial tumor enhancement, while the hepatic uptake of gadoxetic acid is via a transporter, which takes longer. Therefore, we hypothesized that arterial phases after wash-in might enable more frequent visualization of capsular enhancement than PVP. Hence, we evaluated the usefulness of the multiphasic (6 phases) hepatic arterial images (Figure 1) with DISCO2) for improving the detection rate of HCC capsular enhancement in gadoxetic acid-enhanced dynamic MRI.This study was approved by the relevant institutional review board, and informed consent was waived. Between January 2015 and September 2015, 140 clinically diagnosed HCCs in 92 chronic hepatitis patients (56 men, 36 women; aged 55 to 88 years, mean age 73.0 ± 8.17 years) were examined using dynamic gadoxetic acid-enhanced MRI with DISCO. Dynamic MRI was performed using a 3.0-T magnetic resonance system (Discovery 750; GE Medical Systems, Waukesha, WI, USA) with a 32-channel phased-array coil. Gadoxetic acid (0.025 mmol/kg) was administered at 1 mL/s followed by a 20 mL saline flush. Multiphasic hepatic arterial imaging was started 30 s after the start of the injection and completed within a single breath-hold with oxygen inhalation (acquisition time=25–30 s, temporal resolution ~5 s). The PVP (PVP, 90 s) was also obtained. Table 1 summarizes the magnetic resonance sequence parameters. We assessed the presence of capsular enhancement, which was defined as a ring-like enhancement observed after the phase with the maximum tumor-liver contrast ratio on DISCO and PVP images. The prevalence of visible capsular enhancement was compared between PVP alone and PVP + DISCO. All lesions were scored using LI-RADS v2014 to find any improvement in the confidence of diagnosis after additional capsular enhancement visualization with DISCO.All HCCs showed hypervascularity on HAP images. Prevalence of visible capsular enhancement was significantly increased by combining DISCO with PVP (69/140 [49.3%] by PVP alone vs. 88/140 [62.9%] by DISCO + PVP, P<0.0001). Capsular enhancement was observed in three nodules in the only PVP. Combining DISCO with PVP enabled an improvement in LI-RADS score from LR4 to LR5 in 7 nodules (from 68 to 75 nodules, P=0.039; Table 2). The maximum tumor-to-liver contrast ratios in the first, second, and third phases of DISCO were 60.7% (85/140), 21.4% (30/140), and 17.9% (25/140), respectively. Capsular enhancement was first observed one, two, and three phases after the phase with the maximum tumor-liver contrast ratio, in 48 (56.5% (48/85)), 31 (36.5% (31/85)), and 6 (7.1% (6/85)) nodules, respectively. Figure 2 details the clinical cases.Hepatocytes take up gadoxetic acid even in the first pass, and hence, it is difficult to detect capsular enhancement in comparison to that with extracellular gadolinium-based contrast agents. Capsular enhancement was typically observed 1–2 phases after the maximum enhancement of HCCs. Therefore, multiphasic arterial phase imaging with DISCO is useful for detecting capsular enhancement with gadoxetic acid, since it is not revealed on PVP images due to enhanced liver parenchyma.Capsular enhancement of HCC is detected more frequently by combining multiple HAP images with DISCO and PVP images. As a result, the diagnostic performance was improved.