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Original Report |
1
Department of Radiology, Baylor University Medical Center-Dallas, 3500 Gaston
Ave., Dallas, TX 75246.
2
Department of Pathology, Baylor University Medical Center-Dallas, Dallas, TX
75246.
3
Institute of Transplantation Services, Baylor University Medical Center,
Dallas, TX 75246.
Received July 26, 2000;
accepted after revision September 22, 2000.
Presented at the annual meeting of the American Roentgen Ray Society,
Washington, DC, May 2000.
Abstract
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CONCLUSION. Abdominal adenopathy was present in 62% of the patient population, and none of the patients with adenopathy had a known malignancy. Findings associated with end-stage cirrhosis and portal hypertension were seen and included ascites (62%), splenomegaly (71%), portosystemic collaterals (57%), portal vein thrombosis (5%), and hepatocellular carcinoma (5%). The MR imaging periportal halo sign was seen in 43% of patients with primary biliary cirrhosis, but none of the patients in a sex- and age-matched cohort of 21 patients with cirrhosis not caused by primary biliary cirrhosis had the finding. Statistical analysis of these results produced a t score of 3.97 and a p value of less than 0.001, suggesting that this new MR imaging sign is highly specific for the diagnosis of primary biliary cirrhosis.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Pathologically, a necrotizing inflammatory process involves the portal triads with destruction of small- and medium-sized bile ducts, development of a dense infiltrate of acute and chronic inflammatory cells, and mild fibrosis. The disease progresses through four stages of increasing fibrosis and hepatocyte depletion (hepatocellular parenchymal extinction), resulting in a network of connecting scars, reduction of bile ducts, and macroor micronodular cirrhosis [1].
Traditionally, there have been no imaging findings that are specific for primary biliary cirrhosis. This article describes a new radiologic sign, the MR imaging periportal halo sign, that will aid in the radiologic diagnosis of primary biliary cirrhosis. The prevalence of common abdominal imaging abnormalities associated with end-stage cirrhosis is also quantified.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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A retrospective review of the primary biliary cirrhosis cases was performed
with attention to adenopathy (defined as 
2 nodes of 1 cm in the short
axis), ascites, splenomegaly (defined as cephalocaudal length, >13 cm),
portosystemic collaterals, hepatic masses, and the MR imaging periportal halo
sign.
MR images obtained before transplantation of an age- and sex-matched group
of 21 patients with non-primary biliary cirrhosis were then evaluated
specifically for the periportal halo sign and statistically compared with MR
findings from the primary biliary cirrhosis cohort. Causes of cirrhosis in
this cohort were viral hepatitis (11/21), cryptogenic (4/21), primary
sclerosing cholangitis (1/21), alcohol-related or Laennec's cirrhosis (3/21),
Budd-Chiari syndrome (1/21), and 
1-antitrypsin deficiency
(1/21).
In an attempt to understand the pathologic explanation for the MR imaging periportal halo sign, we performed histologic analysis of all patients with and without primary biliary cirrhosis. Masson trichrome stains for connective tissue and routine H and E stains were used in the analysis. Tissue samples from patients with primary biliary cirrhosis, those with and those without the MR imaging periportal halo sign, were directly compared for histologic differences. These tissue samples were then compared with the tissue samples of the patients with cirrhosis not caused by primary biliary cirrhosis.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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As in any case of end-stage cirrhosis, findings of portal hypertension are common in primary biliary cirrhosis. In our series, these findings included ascites (13/21 [62%]), splenomegaly (15/21 [71%]), portosystemic collaterals (12/21 [57%]), portal vein thrombosis (1/21 [5%]), and hepatocellular carcinoma (1/21 [5%]). Except one patient with a hepatoma, none of the patients had any other malignancy, including cholangiocarcinoma.
The finding that initiated the review of this cohort was our observation that many patients with primary biliary cirrhosis have a conspicuous low-signal-intensity abnormality centered around portal venous branches on T1- and T2-weighted MR images. We had not observed this finding in patients with cirrhosis not caused by primary biliary cirrhosis. We termed this appearance the "MR imaging periportal halo sign." Our criteria for a positive MR imaging periportal halo sign included the following: a rounded lesion centered on a portal venous branch, 5 mm-1 cm in size, numerous lesions involving all hepatic segments, low signal intensity on T1-and T2-weighted images, and no mass effect. These criteria allow differentiation of this finding from regenerating nodules, which are usually of various sizes and signal intensity, may exert mass effect, and are not centered on portal venous branches.
Several articles have described areas of both hypoechogenicity [5] and hyperechogenicity [6] around the portal triads on sonography, and our finding may be the MR imaging correlate for these observations. However, the abnormal signal intensity described in this study is distinctly different from the areas of proposed periportal lymphedema or inflammatory cell infiltrate previously described on MR imaging as regions of periportal hyperintensity on T2-weighted images [7]. The low-signal-intensity halo seen on T1- and T2-weighted images in our study speaks strongly for the abnormality being caused by fibrous tissue deposition or cellular depletion around the portal triads rather than by periportal lymphedema or inflammation.
Although seen on all MR images, the periportal halo sign is most conspicuous on those obtained during the portal venous and equilibrium phases (images obtained 45-sec and 3-min after infusion). The periportal halo sign was seen in nine (43%) of 21 patients with primary biliary cirrhosis and in none of the patients in the sex- and age-matched cohort of 21 patients with cirrhosis not caused by primary biliary cirrhosis. A Student's t test for two independent samples with 40 degrees of freedom was used to assess the statistical significance of this comparison. The t score was 3.97 with a p value of less than 0.001. These results suggest that the periportal halo sign is a highly specific MR finding for the diagnosis of primary biliary cirrhosis. The MR imaging periportal halo sign is shown in Figures 1,2,3A,3B.
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The periportal halo sign was not seen in all patients. Using the criteria previously outlined, we needed to differentiate this sign from small regenerating nodules that could mimic the periportal halo sign on MR imaging. These regenerating nodules vary in size and signal intensity and are not centered on the portal vein branches but, rather, are distributed throughout the liver parenchyma in a random pattern (Fig. 4).
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In the primary biliary cirrhosis cohort, reanalysis of liver tissue of patients, both with and without the periportal halo sign, was performed with the intent of discovering the histologic correlate for the MR findings. It was postulated that the finding was caused by periportal fibrosis or periportal cellular depletion. Patients with the periportal halo sign on MR imaging have striking areas of stellate hepatocellular parenchymal extinction around portal venous branches (Fig. 5A,5B). These patients also had larger and more variably sized regenerating nodules arranged in a rosette around the areas of hepatocellular parenchymal extinction. This appearance was not seen in patients with primary biliary cirrhosis without the periportal halo sign visible on MR imaging. Interestingly, it was difficult to see a difference in the histologic appearance of patients with primary biliary cirrhosis and the MR imaging periportal halo sign, compared with patients with advanced cirrhosis of other causes (Fig. 6A,6B). The exception was that the above-mentioned findings are more diffusely distributed throughout the liver parenchyma in patients with primary biliary cirrhosis and the MR imaging periportal halo sign (Fig. 7A,7B).
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Most significant, however, is our observation of a new sign for the recognition of primary biliary cirrhosis, which has traditionally been an entity void of specific imaging findings. The MR imaging periportal halo sign is described in detail, and specific criteria for using the sign are provided. The MR imaging periportal halo sign was seen only in patients with primary biliary cirrhosis, at a high level of statistical significance. The histologic explanation for the low halo of signal intensity surrounding the enhancing portal veins (MR imaging periportal halo sign) may be stellate, periportal, hepatocellular parenchymal extinction encircled by a rosette of large regenerating nodules. These findings were more pronounced, conspicuous, and diffuse in the patients with the MR imaging periportal halo sign than those without the MR imaging periportal halo sign.
We propose that the periportal halo sign is a specific MR imaging sign for the diagnosis of end-stage primary biliary cirrhosis. Larger prospective studies are necessary to further evaluate the usefulness, specificity, and histologic explanation of this finding in patients with and without primary biliary cirrhosis.
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