Paired CT offers instant results of liver tumor treatment

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 - CBCT liver tumor response
Representative contrast-enhanced arterial and venous phase MR images (MRI) and cone-beam CT scans (CBCT) in 58-year-old man with HCC in right lobe secondary to hepatitis C virus.
Source: Radiology 2013;266:636-48

Two successive pairs of specialized CT scans can, within one minute, show whether targeted chemotherapy is working to kill liver tumors, according to a study published in the January issue of Radiology.

Jean-Francois Geschwind, MD, of Johns Hopkins University School of Medicine in Baltimore, and colleagues looked at dual-phase cone-beam CT (DPCBCT) images, taken immediately before and after transcatheter arterial chemoembolization, and found that tumor response in these scans matched up well with MRI scans acquired one month later.

"Patients should not have to endure the uncertainty of waiting weeks or more to find out if their chemoembolization was successful in fighting their liver cancer," Geschwind said in a press release, adding that such delays allow cancer to spread.

"This new scanning method is giving us almost instant feedback about the value of injecting antitumor drugs directly into large liver tumors and their surrounding blood vessels in an effort to quickly kill them, and to prevent the cancer from spreading.”

A total of 27 patients with inoperable liver cancer were included in the final analysis. All were treated with transcatheter arterial chemoembolization using drug-eluting beads between March and December 2009. MRI was performed at baseline and one month after treatment. These MRI findings were used to assess tumor enhancement at DPCBCT in the early arterial and delayed venous phases.

MRI follow-up showed complete and/or partial tumor response in 74 percent and 76 percent of lesions in the arterial and venous phases, respectively. The decrease in tumor enhancement seen with DPCBCT after chemoembolization showed a linear correlation with MR findings, reported the authors, and a significant relationship between tumor enhancement at DPCBCT after treatment and tumor response at MRI was found in both phases.

In order to test the additional radiation dose administered through DPCBCT, Geschwind and colleagues used measurements from a porcine model and determined the dose from the dual-phase scan was 3.08 mSv. The entire scanning time was 20-30 seconds.

The authors explained that conebeam CT has the advantage of being readily available in many practices and tumor imaging could be performed with only one contrast material injection without the need for multiple patient transfers.

“Furthermore, dual-phase cone-beam CT has a benefit over contrast-enhanced MR imaging in that cone-beam CT can be performed during the [transcatheter arterial chemoembolization] procedure, with minimal additional effort other than that required with [digital subtraction angiography] and fluoroscopy,” wrote the authors. “This can provide live-image feedback not only on the [transcatheter arterial chemoembolization] delivery catheter positioning and drug delivery amount but also on embolization success, as shown in our study.”

Geschwind and colleagues wrote that DPCBCT could improve treatment planning and may ultimately eliminate the need for one-month MRI follow-up.