Transient hepatic attenuation differences and focal liver lesions: sump effect due to primary arterial hyperperfusion.

OBJECTIVE: To analyze at computed tomography (CT) examination the "sump effect," a particular type of transient hepatic attenuation differences, related primarily to an increase in arterial flow without any accompanying decrease in portal flow. METHODS: We retrospectively evaluated all biphasic upper abdomen CT examinations (1283 in 807 patients) performed from the year 2003 to the year 2006 and selected and organized those with at least 1 transient hepatic attenuation differences. Of these, we enrolled patients with lobar/multisegmental arterializations surrounding focal lesion(s), without CT portal hypoperfusion signs, in the study group. We assessed histology, number, site, diameter, and volume of causing focal lesion(s); site, extension, and attenuation of arterial area; greater visibility of feeding artery branches ipsilateral to causal focal lesion; and presence of aberrant left hepatic artery. Thirty patients with normal liver represented the control group. RESULTS: Fifteen of the 99 patients with transient hepatic attenuation differences presented with sump effect. In our series, this phenomenon was always related to hypervascular inflammatory and benign lesion(s) with overall average diameter of 8 +/- 4 cm inscribed in arterial area. Attenuation of arterial enhanced areas were significantly higher than the contralateral parenchyma and control patients' parenchyma, with frequent hypertrophy of ipsilateral arterial feeding branches and/or aberrant left hepatic artery visibility. CONCLUSIONS: Siphonage seems to be primary hyperperfusion area determined by arterial bed enlargement, induced by inscribed large hypervascular inflammatory/benign lesion(s).

Transient hepatic attenuation difference (THAD) in biliary duct disease.

BACKGROUND: THADs are associated with a wide spectrum of hepato-biliary pathologies. The aim of this paper is to find out the role of THADs in the imaging assessment of biliary diseases. We performed a retrospective study to establish the frequency of arterial phenomena in patients with specific biliary diseases. METHODS: Out of 1833 patients who underwent upper abdomen biphasic CT (2003-2007), we selected those with the following diagnoses: biliary duct dilation due to extrahepatic obstruction (20 patients-group A), intrahepatic-hilar cholangiocellular-carcinoma (19 patients-group B), and cholangitis (14 patients-group C). THAD presence/pattern was assessed for each group. Patients without any demonstrable clinical/imaging signs of liver/biliary pathology (1124) were the control group. RESULTS: THADs were observed in 36/53 (67.9%) and 20/1124 (1.78%) in study and control groups respectively, with significant association between each diagnostic group and THAD patterns (P < 0.0001). Eleven out of 20 (55%) group A patients showed peribiliary-THAD around dilated biliary tracts; 15/19 (79%) group B patients demonstrated portal involvement and sectorial-THAD; 10/14 (71%) group C patients revealed polymorphous-THAD all along inflamed biliary duct. CONCLUSIONS: However, THADs are complex phenomena, their evaluation can be an additional diagnostic tool in patients with a biliary pathology. Diffuse peribiliary, sectorial, and polymorphous-THADs show a good rate of correlation (P < 0.0001) with biliary duct ectasia, portal infiltration, and cholangitis, respectively.

Transient hepatic intensity differences: part 1, Those associated with focal lesions.

OBJECTIVE: The purpose of our study was to evaluate, on MRI, transient hepatic signal intensity differences (THID) that have already been seen on CT as transient hepatic attenuation differences (THAD) and to show the range of appearance of such arterial phenomena, when associated with focal lesions, in an effort to correlate morphology, cause, and pathogenesis. CONCLUSION: Hepatic arterial phenomena visualized on MRI should be known and recognized to avoid incorrect diagnoses and to improve the characterization of focal liver lesions because their shape can lead to an understanding of pathogenetic mechanisms.

Transient hepatic intensity differences: part 2, Those not associated with focal lesions.

OBJECTIVE: The purpose of our study was to evaluate and to show the range of appearance of transient hepatic signal intensity differences when not associated with focal lesions, and to correlate morphology, cause, and pathogenesis. CONCLUSION: Hepatic arterial phenomena, visualized on MRI and CT, must be considered important signs of underlying liver disorders, which these phenomena contribute to evaluate. Accordingly, the hepatic arterial phase must always be performed on MRI as well as on CT, even if no focal lesion is expected.

[Meaning and etiopathogenesis of sectorial transient hepatic attenuation differences (THAD)]. / Significato ed eziopatogenesi dei fenomeni arteriali epatici (THAD) settoriali.

PURPOSE: To examine sectoral transient hepatic attenuation differences (THAD) in an attempt to correlate semeiotics with etiopathogenesis and to deduce a possible diagnostic value. MATERIALS AND METHODS: Over a period of three years (January 1998-January 2001) we observed 130 THAD in 988 patients, and we selected 30 sectoral THAD in 18 patients (10 males and 8 females), ranging in age from 24 to 82 years (average = 63.3). The 18 patients comprised 6 cancer patients undergoing CT staging/restaging, 5 cirrhotic patients being studied for possible hepatocellular carcinoma, 7 patients undergoing helical CT to further investigate clinical and/or US findings. For each patient a biphasic helical CT liver examination was performed, during the arterial and portal dominant phase. After the first diagnosis, all patients were followed up for 12 months with at least one US and helical CT examination; 8/18 were also studied by MRI. RESULTS: Thirty THAD were associated with 14 metastatic lesions, 4 hepatocellular carcinomas, 1 cholangiocarcinoma of the liver, 4 haemangiomas, 3 abscesses, 1 FNH, 2 cases of arterioportal shunting (APS) and 1 fine-needle percutaneous biopsy. Nine THAD turned out to be the sole sign of disease and occurred at least 3/6 months before the causal focal lesion had become detectable. At the first examination, all focal lesions had a maximum diameter of 2 cm; the size of THAD varied from 1 to 5 cm. All of the THAD were sectoral, with the base side represented by the glissonian capsule and the apex towards the parenchyma. 27/30 THAD were connected to focal lesions: 24/27 were fan-shaped and the lesion was situated at the apex of the triangle; 3/27 were roughly wedge-shaped and the lesion was entirely inscribed in the hyperattenuating area. 3/30 were not connected to focal lesions, being in 2 cases fan-shaped and in only one case irregularly shaped. CONCLUSIONS: Sectoral THAD may or may not be connected to focal lesions. Whenever a sectoral THAD not connected to a focal lesion is detected, all of the possible causes should be considered: portal or superhepatic vein thrombosis, traumatic (biopsy) or cirrhotic intraparenchymal APS, or a benign occult nodule. If none of these explanations are confirmed, we should consider the possibility of an occult malignant lesion.