MRI outplays ultrasonography in HCC detection
medwireNews: Screening cirrhotic patients at high risk of hepatocellular carcinoma (HCC) with gadoxetic acid-enhanced magnetic resonance imaging (MRI) results in significantly improved HCC detection compared with ultrasonography, findings indicate.
“[S]urveillance by MRI with liver-specific contrast may allow earlier detection of HCC than [ultrasonography], improving clinical outcomes” in this patient population, say Young-Suk Lim (Asan Medical Center, Seoul, Korea) and team.
A total of 407 individuals, each with an estimated annual risk of HCC of over 5%, underwent 1–3 screening assessments with paired contrast-enhanced MRI and ultrasonography at 6-month intervals. HCC cases were confirmed by histological evaluation and/or by dynamic computed tomography (CT).
During a median follow-up of 1.5 years, 43 patients received an HCC diagnosis. Of these, 26 were detected by MRI alone, one by ultrasonography only and 11 by both, while five were missed by both and detected on the follow-up CT scan conducted 6 months after the last round of screening. Four of the missed lesions were detectable on a retrospective review of the MRI images, but all had atypical vascular patterns.
The overall rate of HCC detection was significantly higher for MRI than for ultrasonography, at 86.0% versus 27.9%, as was the rate of detection of very early-stage tumours (single nodule <2 cm), at 84.8% and 27.3%, respectively.
Screening with MRI led to significantly fewer false–positive findings, at a rate of 3.0% compared with 5.6% for ultrasonography.
And area under the receiver operating characteristic curve analysis showed that MRI detected HCCs with 93% accuracy, which was significantly better than the 62% accuracy of ultrasonography.
The majority (74.4%) of cases were very early-stage HCC, and more than half the patients (67.4%) received “potentially curative treatments, treatments, such as liver transplantation, surgical resection, and local ablation”, the investigators report in JAMA Oncology.
Of note, they did not find a significant difference in 3-year overall survival from the first screening assessment for individuals with versus without HCC. However, “[w]hether surveillance with liver-specific contrast-enhanced MRI would reduce mortality from HCC in high-risk patients requires further investigation”, say Lim et al.
In a linked editorial, Tung-Hung Su and Jia-Horng Kao, from National Taiwan University Hospital in Taipei, note that the “detection rate of MRI and ultrasonography in this study is somewhat suboptimal.” For instance, although the positive predictive value (PPV) of MRI was superior to that of ultrasonography (53.6 vs 16.9%), “the PPV of liver-specific contrast-enhanced MRI for the detection of HCC [has] been reported up to 100%.”
The editorial authors continue: “Another concern is that multidetector CT was used as the criterion standard of HCC diagnosis”, even though CT has lower sensitivity than gadoxetic acid-enhanced MRI for HCC detection. But there may be no way around this for studies investigating MRI as a surveillance tool, they write.
Su and Kao conclude that “the authors raised a novel idea of MRI surveillance for HCC. However, whether we should recommend gadoxetic acid–enhanced MRI for HCC surveillance is still an open question and should be considered only in high-risk patients.”
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