Accurate pre-therapy and follow-up imaging are essential for the successful management of fibrolamellar hepatocellular carcinoma (HCC), according to doctors at the University of Pittsburgh Medical Center. CT and MRI are cornerstones of the staging, assessment, and aggressive surgical intervention that can yield years of tumor-free survival, they wrote in a paper published in the October issue of Radiology.
In the article, Drs. Tomoaki Ichikawa, Michael Federle, and others from the University of Pittsburgh and Yamanashi Medical University in Japan examined the features of fibrolamellar HCC, as well as the effects on prognosis of aggressive management (Radiology, October 2000, Vol.217:1 pp.145-151).
Fibrolamellar HCC differs from conventional HCC in several respects. While some researchers consider it slower-growing and less prone to metastasis than conventional HCC, others have characterized it as an aggressive invader that can produce distant metastases similar to those found in conventional HCC. Nevertheless, it has a reported five-year survival rate of 25%-30%, and up to 63% in patients whose tumors are resected.
The U.S.-Japan team studied 40 patients, ages 15-65, who had histopathologic confirmation of fibrolamellar HCC.
"The tumors were composed of cords, sheets, and pseudoglands of polygonal hepatocyte-like cells separated by irregularly arranged fibrolamellar bands of dense collogen," the authors wrote.
All 40 patients underwent pre-therapy CT scans of the liver (31 of those with iodinated contrast), and 11 had pre-therapy MR imaging. All patients had post-therapy CT, and four underwent follow-up MR imaging. Of the 31 patients who underwent contrast-enhanced CT, 10 had conventional nonenhanced and contrast-enhanced scans, and 21 had multiphase spiral CT scans of the liver.
The spiral CT scans were obtained with a commercial CT scanner (HiSpeed Advantage, GE Medical Systems, Waukesha, WI), using a section thickness of 5 or 7 mm and a pitch of 1 to 1.5, which enabled the scans to be completed in one breath-hold. The non-spiral CT scans were obtained with a GE HiLight Advantage scanner with a section thickness of 7 mm, the authors wrote.
All MR imaging sequences included T-1 weighted spin-echo imaging (140-700/12-20) and T-2 weighted spin-echo or fast spin-echo imaging (4,000-9,230/70-140) with echo-train length of 8 or 16, and without fat-suppression techniques. All but two patients received contrast, according to the authors.
Post-therapy CT and MR imaging occurred between 1-14 days after surgery. Precise timing was not possible due to clinical signs and symptoms in some patients, the authors noted. After treatment, some patients received follow-up care at institutions in their home communities.
"We were able to follow the clinical course of all patients for a minimum of 6 months, and were able to follow up most patients until their death (n = 19) or for a mean interval of 4 years," they wrote.
Two radiologists interpreted the CT and MR images, evaluating the number, size, and distribution of tumors. They were aware of the fibrolamellar HCC diagnosis, but were blinded to clinical, surgical, and histopathologic findings.
In pre-therapy imaging results, the 31 patients who underwent contrast-enhanced CT had 31 primary fibrolamellar HCCs ranging in size from 3-27 mm, of which 25 were solitary tumors. Intrahepatic metastases were found in 19%. Intrahepatic biliary duration was found in 42% of these patients, and compression, occlusion, or invasion of major hepatic vessels was seen in 87%. Extrahepatic tumors were detected in imaging or at surgery in 33 patients.
Thirty-two of 40 patients with fibrolamellar HCC underwent surgical exploration. Of these, four underwent orthotic liver transplantation, 16 underwent attempted resection without adjuvant therapy, and 12 patients underwent attempted resection following neoadjuvant chemotherapy, the authors wrote. Tumor resection was not performed in seven patients due to diverse factors such as diffuse metastases of the liver and lymph nodes that could not be resected completely.
Although correlation between pre- and postoperative imaging was limited when there were multiple lesions, all major intravascular tumors seen in CT or MR imaging were confirmed at surgery or at histopathology. However, vessel compression or occlusion was difficult to differentiate at imaging, and difficult to prove histopathologically.
"Our experience suggests that CT and MR imaging accurately demonstrate major vascular tumor thrombi. Distinction of vascular compression from actual encasement or obstruction is more difficult," the researchers said.
However, "direct local invasion and peritoneal seeding were more evident at surgery than at preoperative imaging. CT demonstrated definite peritoneal tumors in only two of 12 patients with ascites, while 10 of them had carcinomatosis at surgery," the authors wrote.
The 17 patients who underwent curative resection were subsequently evaluated at a mean of four years; 12 of them (71%) had recurrent or metastatic disease. Recurrent tumors were intrahepatic in 12 patients; the remaining patients had metastases of the lung (6) and lymph nodes (1).
A previous study (American Journal of Roentgenology, May 1995, Vol.164:5, pp.1153-1158) at the Mayo Clinic in Rochester, MN, found that accurate imaging is especially important for managing fibrolamellar HCC because surgery is often attempted in cases where imaging features would generally indicate unresectability, the authors wrote.
"Our experience with 40 patients with fibrolamellar HCC reinforces the impressions and recommendations of the Mayo Clinic investigators," they wrote. "We found that contrast-enhanced CT, particularly helical multiphase CT, allowed excellent characterization and staging of fibrolamellar HCC. MR imaging seems to provide similar information, accurately depicting hepatic involvement, although evaluation for distant metastases and lymph node involvement might be more challenging and expensive with MR imaging."
By Eric BarnesAuntMinnie.com staff writer
October 31, 2000
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