MRI bests ultrasound for cancer screening of cirrhotic livers, but is it fiscally feasible?

When surveilling cirrhosis-stricken patients for hepatocellular carcinoma—or HCC, the frequently incurable cancer that starts in the liver and sometimes follows cirrhosis—MRI with liver-specific contrast can be a better diagnostic performer than ultrasound, the guideline-recommended screening tool for such situations.

That’s the conclusion of researchers in South Korea whose findings were posted Sept. 22 in JAMA Oncology.

Whether making the switch would make good economic sense is another question, as the researchers have acknowledged and critics have underscored.  

So Yeon Kim, MD, PhD, of the University of Ulsan in Seoul and colleagues found that MRI, when enhanced with the targeted contrast agent gadoxetic acid, both detected more cancers and yielded fewer false positives than ultrasound.

Moreover, the MRI exams detected cancers at very early stage, laying the ground for longer survival and better disease management.

Kim and colleagues conducted a prospective study of 407 patients with cirrhosis and an estimated annual risk of HCC greater than 5 percent. Between November 2011 and August 2014, the patients received one to three biannual screening exams with both ultrasound and gadoxetic acid-enhanced MRI.

In total, the patients received 1,100 screenings with paired ultrasound and MRI.

At six months after the last screening round, the team followed up with all study patients, using contrast-enhanced CT scans to exclude false-negative findings. They confirmed HCC based on pathology results and/or CT images.

HCC was diagnosed in 43 patients. Ultrasound alone detected only one confirmed cancer, while MRI alone caught 26. The two modalities together detected 11, and five cancers were missed by both.

MRI’s total detection rate was 86.0 percent (37 of 43), significantly higher than ultrasound’s 27.9 percent (12 of 43).

Further:

• MRI showed a significantly lower rate of false-positive findings than ultrasound (3.0 percent vs. 5.6 percent, respectively).
• Of the 43 patients with HCC, 32 (74.4 percent) had very early-stage HCC, and 29 (67.4 percent) received curative treatments.
• The three-year survival rate of the patients with HCC (86.0 percent) was not inferior to those without HCC (94.2 percent; hazard ratio, 2.26).

While the authors urge readers to interpret the study within its limitations, which included an inability to obtain pathological confirmation for all patients, they also suggest liver MRI deserves greater consideration as a screening tool than it’s gotten up to this point.

“Since the annual risk of developing HCC is not uniform across all patients with cirrhosis, the tailored surveillance strategy based on the individual HCC risks may enable delivery of precision medicine to patients and improve their clinical outcomes,” Kim et al. write, adding that further investigation is needed to establish whether surveillance with liver-specific contrast-enhanced MRI would reduce HCC mortality in high-risk patients.

Expensive but worth it?

Taking up the matter of MRI’s inescapably high price tag, Kim and colleagues point out the situational variables that go into determining its utilization.  

“In general, the cost-effectiveness of a cancer screening program relies on multiple factors,” they write, noting that these might include “the characteristics of the population under surveillance, the test’s performance, the test’s cost and the availability of treatments that substantially extend survival of the patients.”

Financial feasibility is among several concerns raised in an accompanying opinion piece submitted by Tung-Hung Su, MD, PhD, and Jia-Horng Kao, MD, PhD, both of National Taiwan University in Taipei.

“It may not be fair to compare the two imaging modalities for the diagnosis of HCC because MRI is used for diagnostic imaging and has higher sensitivity and specificity, whereas ultrasonography is used for screening purposes,” Su and Kao point out, adding that, in clinical practice, ultrasound is readily available and recommended by all current guidelines.

‘Only in high-risk patients’

“For future perspectives, the cost-effectiveness of ultrasonographic screening followed by MRI or CT confirmation compared with MRI surveillance with longer follow-up for the reduction of mortality should be explored,” Su and Kao write.

They also recommend looking into the comparative cost-effectiveness between gadoxetic acid-enhanced MRI and conventional MRI.

Kim et al. have “raised a novel idea of MRI surveillance for HCC,” Su and Kao conclude. “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.”