Nontumorous arterioportal shunt mimicking hypervascular tumor in cirrhotic liver: two-phase spiral CT findings

Single-session combined therapy with chemoembolization and radiofrequency ablation in hepatocellular carcinoma less than or equal to 5 cm: a preliminary study

PURPOSE

To evaluate the efficacy and safety of a single-session combined chemoembolization and radiofrequency (RF) ablation for hepatocellular carcinomas (HCCs) less than or equal to 5 cm.

MATERIALS AND METHODS

Between June 1, 2004, and January 1, 2006, 50 patients (41 men, nine women; age range, 35-77 years; mean age, 61.5 years) with 57 HCCs (1.5-4.5 cm; mean, 2.4 cm) underwent single-session combined therapy. Chemoembolization was performed by using a doxorubicin hydrochloride/iodized oil emulsion with or without gelatin sponge particles. Immediately following chemoembolization, RF ablation was performed under fluoroscopy or ultrasonographic guidance. Initial tumor response and local tumor progression were determined with follow-up computed tomography or magnetic resonance imaging. The recurrence-free and overall survival rates as well as procedure-related complications were evaluated.

RESULTS

At 1-month follow up, complete necrosis was achieved in all index tumors; however, nonindex intrahepatic recurrences were found in two patients (complete response in 48 patients and progressive disease in two patients). The estimated 1- and 3-year local tumor progression rates during the follow-up period (range, 13.1-51.6 months; mean, 29.0 months) were 1.8% and 9.4%, respectively. The 1- and 3-year recurrence-free and overall survival rates were 64.6% and 30.5% and 100% and 79.7%, respectively. Three of the 50 patients (6%) had major complications, including segmental hepatic infarction (n = 2) and hepatic arterial bleeding (n = 1).

CONCLUSIONS

Single-session combined therapy is an effective and safe treatment for HCCs less than or equal to 5 cm.

Nontumorous arterioportal shunts in the liver: CT and MRI findings considering mechanisms and fate

The intrahepatic non-tumorous arterioportal shunt (APS) is one of the important causes of transient hepatic enhancement differences (THED) on dynamic CT or MRI. Most small APSs are located in the peripheral portion of the liver. Because of the parenchymal distortion in the advanced cirrhotic liver, many small APSs tend to show an amorphous or nodular appearance, making them difficult to distinguish from hypervascular tumors. In addition to the use of dynamic CT or MRI, iso-attenuation densities or iso-intensities on pre-contrast and equilibrium phases, MRI using a liver-specific contrast agent can be useful to characterize the hypervascular pseudolesions. Because there is no difference in water diffusion in the hepatic parenchyma in the region of the APS, diffusion-weighted MRI also has great potential to distinguish non-tumorous shunts from true focal lesions. Larger (>2 cm) APSs of direct arterio-portal venous fistulas from extrinsic insults show typical subcapsular wedge-like THEDs that are only temporarily depicted several months after the traumatic event; most of these THEDs gradually decrease in size or vanish completely. By understanding the nature of non-tumorous APSs, radiologists will be able to provide a more accurate assessment of many THEDs during daily interpretations of CT or MR images of the liver.

Ultrasound-guided treatments under low acoustic power contrast harmonic imaging for hepatocellular carcinomas undetected by B-mode ultrasonography

BACKGROUND/AIMS

The aim was to examine the efficacy of contrast-enhanced ultrasound (US) with Sonazoid to demonstrate ultrasonically unrecognizable hypervascular hepatocellular carcinoma (HCC) and apply percutaneous US-guided treatments.

METHODS

The subjects of this prospective study were 44 cirrhotic patients with 55 hypervascular lesions (12.7+/-4.5 mm) found by contrast-enhanced computed tomography but unrecognized by non-contrast US. Contrast-enhanced US was performed to demonstrate these hepatic lesions after an intravenous injection of Sonazoid (0.0075 ml/kg). The sonograms in both the early phase (for 1 min after injection) and the late phase (5-10 min after) were taken in the harmonic imaging mode under a low mechanical index (0.24-0.3).

RESULTS

Fifty-three lesions were demonstrated by contrast-enhanced US, 52 with positive enhancement in the early phase and 44 with negative enhancement in the late phase. Percutaneous US-guided treatments were successfully performed for 42 lesions (ethanol injection in 20 and radiofrequency ablation in 22) in 32 patients with reference to contrast-enhanced US findings. Six patients were treated by transarterial chemoembolization alone because they had more than three lesions in the liver. In the remaining seven lesions in six patients, six were diagnosed as non-HCC lesions: five with vascular abnormalities such as arterioportal or arteriovenous communication and the other one with benign lesion in alcoholic liver disease. These six lesions and one HCC lesion with severe liver damage were followed up without any treatment.

CONCLUSIONS

As the detectability of ultrasonically unrecognizable hypervascular HCC improved by contrast-enhanced US with Sonazoid, a wider application of percutaneous US-guided treatments may be possible.

CT of nonneoplastic hepatic vascular and perfusion disorders

The unique dual blood supply of the liver (75% portal venous, 25% hepatic arterial) makes multiphase helical computed tomography (CT) a highly suitable technique for hepatic evaluation with imaging in two (arterial and portal venous) or more phases. Multiphase helical CT has become an important tool in the detection and characterization of hepatic tumors. In some situations, hemodynamic changes might mimic neoplastic or inflammatory lesions and evoke diagnostic uncertainty. To confidently identify hepatic conditions such as venous outflow obstruction (Budd-Chiari syndrome), arterioportal shunts, hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome), peliosis hepatis, passive congestion, and hepatic infarction, radiologists must be familiar with the disease-specific CT appearances and related clinical manifestations.

Small nodules (1-2 cm) in liver cirrhosis: characterization with contrast-enhanced ultrasound

OBJECTIVE

To determine the diagnostic efficacy of arterial phase contrast-enhanced ultrasound (CEUS) for characterizing small hepatic nodules (1-2 cm) in patients with high-risk for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Over 12 months, CEUS was performed in 59 patients at high-risk for HCC with small hepatic nodules (1-2 cm; mean, 1.5 cm). Based only on arterial phase (<45 s) vascular intensity and pattern, lesions were prospectively diagnosed as HCC if there was hypervascularity without known features of hemangioma. The diagnosis of HCC was made regardless of the presence or absence of washout. Verification of diagnosis was made by liver transplantation (n=13), biopsy (n=12), resection (n=3) or clinical and imaging follow-up for at least 12 months (n=31).

RESULTS

At of the time of CEUS, the 59 nodules were diagnosed as HCC in 26 and benign lesions in 33, including 20 regenerative/dysplastic nodules (RN/DN), 11 hemangiomas, and 2 focal fat sparing. All 26 nodules with arterial phase hypervascularity without hemangioma-like features were HCC. However, CEUS misdiagnosed HCC as RN/DN in 4 cases with arterial iso- (n=3) or hypovascularity (n=1). CEUS correctly diagnosed all 11 hemangiomas. The sensitivity, specificity, and accuracy of CEUS for diagnosing HCC were 86.7, 100, and 93.2%.

CONCLUSIONS

Arterial phase vascular intensity and pattern of CEUS are highly accurate for the diagnosis of small (1-2 cm) HCC and hemangioma in liver cirrhosis. On CEUS, arterial phase hypervascularity without a hemangioma-pattern alone may be sufficient for diagnosis of small HCC. Infrequent iso/hypovascular HCC may erroneously suggest RN/DN necessitating biopsy or close follow-up.

Hepatic capsular and subcapsular pathologic conditions: demonstration with CT and MR imaging

A variety of pathologic conditions and pseudolesions occur at the capsular and subcapsular regions of the liver and are detected with cross-sectional abdominal imaging. These entities are related to anatomic and hemodynamic characteristics of the liver such as negative subdiaphragmatic pressure, connection with other viscera and extraperitoneal sites by the perihepatic ligaments, and a "third inflow" of blood from sources other than the usual hepatic arterial and portal venous sources. Pathologic conditions can affect the hepatic capsular and subcapsular regions by way of peritoneal, hematogenous, biliary, and perihepatic ligamentous routes. Pseudolesions or benign conditions may also be identified on the basis of altered hemodynamics of the liver. Computed tomography and magnetic resonance imaging with a multiphasic approach can be used to identify and characterize these entities. Familiarity with the wide spectrum of pathologic conditions and pseudolesions at the hepatic capsular and subcapsular regions and precise knowledge of the anatomic and hemodynamic characteristics of the liver will aid the radiologist in diagnosing pathologic conditions and differentiating pseudolesions from true lesions.

Macro-regenerative nodules in biliary atresia: CT/MRI findings and their pathological relations

AIM: To describe the radiological findings of a macro-regenerative nodule (MRN) in the liver of pre-transplantation biliary atresia (BA) patients and to correlate it with histological findings.

METHODS: Between August 1990 and November 2007, 144 BA patients underwent liver transplantation (LT) at our institution. The pre-transplantation computer tomography (CT) and magnetic resonance imaging (MRI) findings were reviewed and correlated with the post-transplantation pathological findings.

RESULTS: Nine tumor lesions in 7 patients were diagnosed in explanted livers. The post-transplantation pathological findings showed that all the lesions were MRNs without malignant features. No small nodule was detected by either MRI or CT. Of the 8 detectable lesions, 6 (75%) were in the central part of the liver, 5 (63%) were larger than 5 cm, 5 (63%) had intra-tumor tubular structures, 3 (38%) showed enhancing fibrous septa, 3 (38%) had arterial enhancement in CT, one (13%) showed enhancement in MRI, and one (13%) had internal calcifications.

CONCLUSION: Although varied in radiological appearance, MRN can be differentiated from hepatocellular carcinoma (HCC) in most of BA patients awaiting LT. The presence of an arterial-enhancing nodule does not imply that LT is withheld solely on the basis of presumed malignancy by imaging studies. Liver biopsy may be required in aid of diagnostic imaging to exclude malignancy.

Small hypervascular enhancing lesions on arterial phase images of multiphase dynamic computed tomography in cirrhotic liver: fate and implications

OBJECTIVE

Our purpose was to determine the significance of small hypervascular enhancing lesions exclusively on the arterial phase images of dynamic computed tomography in cirrhotic liver.

METHODS

One hundred sixty-nine enhancing lesions (>5 and <30 mm) on the arterial phase images of dynamic computed tomography in 67 patients with cirrhotic liver, not distinguished from background hepatic parenchyma on equilibrium phase images without hypoattenuation density on portal phase images, were subjected to a retrospective assessment in terms of the lesion growth in addition to the location, size, and contour of the lesions, depending on the final diagnoses of the individual lesions.

RESULTS

Twenty-eight (17%) of the 169 enhancing lesions were hepatocellular carcinomas (HCCs). All of the 43 wedge-shaped, subcapsular lesions were benign, and 126 nodular or irregular lesions were subcapsularly (benign, n = 59; HCC, n = 11) or centrally (benign, n = 39; HCC, n = 17) located. Significant differences were found between HCCs and benign lesions in terms of their shape (P = 0.002) and location (P = 0.041), and the positive and negative predictive values of centrally located lesions for diagnosing HCCs were 21% and 85%, respectively. The positive and negative predictive values for the diagnosis of HCC based on the lesion growth were 90% and 93%, respectively.

CONCLUSIONS

Because of the low positive predictive value of non-wedge-shaped, centrally located, early enhancing lesions in the diagnosis of HCC, the serial follow-up for examining lesion growth is essential to the correct diagnosis of small arterial hypervascular lesions in cirrhotic liver.

Transient hepatic attenuation difference (THAD) following transcatheter arterial chemoembolization for hepatic malignancy: changes on serial CT examinations

The purpose of this study was to investigate the natural history of transcatheter arterial chemoembolization (TACE)-induced, transient hepatic attenuation difference (THAD). Among the patients who underwent TACE for treatment of hepatocellular carcinomas during a 32-month period, 32 patients with 40 newly developed THADs defined as localized, transient, peripheral hepatic parenchymal enhancement during the hepatic arterial phase of dynamic CT (axial dimension, 1.9-8.8 cm; mean, 4.9 cm) in the vicinity of iodized-oil accumulation were subjected to a retrospective analysis of serial follow-up CT examinations. Among the 40 TACE-induced THADs, 18 (45%) and 9 (23%) were accompanied with arterial-portal venous fistula (APF) and portal venous stenosis (PVS), respectively, while 2 (5%) THADs showed both APF and PVS simultaneously. Thirty-eight (95%) THADs disappeared spontaneously during the follow-up period (range, 4-26 months; mean, 9 months), and 11 (29%) of them showed progressive atrophy of the corresponding hepatic parenchyma. Regardless of the presence of APF, 10 (91%) of 11 THADs of following parenchymal atrophy had shown PVSs (P<0.001). During the long-term follow-up period after TACE, almost all of the TACE-induced THADs spontaneously disappeared and either had or did not have corresponding parenchymal atrophy, which is strongly related to the presence of PVS. Understanding the nature of these CT features would be helpful for radiologists in determining the prognosis of the TACE-induced hepatic injuries as well as in distinguishing them from the recurrent tumour.

Abdominal findings in hereditary hemorrhagic telangiectasia: pictorial essay on 2D and 3D findings with isotropic multiphase CT

The rapid evolution in multidetector computed tomographic (CT) technology has produced improvements in temporal and spatial resolution, leading to greater recognition of the spectrum of abdominal findings in hereditary hemorrhagic telangiectasia (HHT). In this multisystem vascular disorder, the abdominal findings are predominantly within the liver. Hepatic vascular lesions in HHT range from tiny telangiectases to transient perfusion abnormalities and large confluent vascular masses. Focal hepatic lesions are often associated with arteriovenous, arterioportal, or portovenous shunts. Pancreatic, splenic, and other vascular abnormalities are also observed because they are included in the field of view. By taking advantage of the increased z-axis spatial resolution and faster scanning times, and by using a bolus tracking technique, multiphase CT can be used to identify hepatic and extrahepatic lesions in HHT and to characterize the associated vascular shunts. Coronal maximum intensity projection images are particularly helpful in depiction of small hepatic vascular lesions.

The clinical outcome of small (<20 mm) arterially enhancing nodules on MRI in the cirrhotic liver

OBJECTIVES

To evaluate the outcome of arterially enhancing nodules (AENs) measuring <20 mm detected on MRI in patients with cirrhosis.

METHODS

Prospective analysis of 54 patients with a total of 161 AENs <20 mm on MRI. Inclusion criteria included a minimum of 12 months of MRI follow-up or histological evaluation of the AEN. Key exclusions were patients with an AEN >20 mm or prior diagnosis of HCC. Two radiologists blinded to the clinical and pathological data reviewed serial MRIs and classified the AENs as no longer visible, stable, increasing, or decreasing in size.

RESULTS

A total of 161 AENs were identified and were followed by serial MRI for a mean of 24 months. Eighty (50%) AENs were no longer visible on repeat imaging, 42 (26%) remained stable, 1 of which was diagnosed as HCC on short-term follow-up, 8 (5%) increased in size and were subsequently diagnosed as HCC, and 24 (15%) decreased in size. In addition, 7 AENs (4%) were diagnosed on biopsy immediately following the initial MRI. Overall MR characteristics diagnostic of HCC were growth > or =2 mm and peripheral rim enhancement on initial MRI.

CONCLUSIONS

The majority (90%) of AENs <20 mm in cirrhosis are benign. The presence of rim enhancement or interval growth of an AEN are suggestive of HCC.

A hypervascular pseudotumor in the liver with angiodysplasia in the center of the lesion: a new entity or a variant of focal nodular hyperplasia?

A unique case of hypervascular pseudotumor in the liver consisting of central angiodysplasia surrounded by atrophic liver tissue is described. A 45-year-old woman was referred for the incidentally found hepatic lesion. Computed tomography with contrast showed strong enhancement of the lesion in the arterial phase, and the effect persisted to the parenchymal phase. Doppler ultrasonography showed winding dilated blood flows into the lesion. Because the pathological examination of the biopsy specimen showed the possibility of a well-differentiated hepatocellular carcinoma, she underwent surgery. Final pathological findings showed that the lesion demonstrated atrophic change of the liver tissue with a cluster of abnormal vessels of various sizes in the center. Although there was no primary liver disease, multiple liver metastases from laryngeal carcinoma were found coincidentally. The present lesion could represent a new entity or a variant (or an unknown stage of development) of focal nodular hyperplasia.

Application of percutaneous ultrasound-guided treatment for ultrasonically invisible hypervascular hepatocellular carcinoma using microbubble contrast agent

AIM

To evaluate the efficacy of contrast-enhanced ultrasound for the localization of ultrasonically invisible hypervascular lesions in the liver to facilitate percutaneous ultrasound-guided treatment.

MATERIALS AND METHODS

Forty patients with 47 ultrasonically invisible hypervascular lesions (5-20mm) diagnosed on contrast-enhanced computed tomography were enrolled in the retrospective study. Contrast-enhanced ultrasound (CEUS) with Levovist was performed to localize the lesions both in the early phase and liver-specific phase. Diagnosis of was confirmed by percutaneous needle biopsy where feasible, and on the basis of on treatment outcomes or changes in computed tomography findings in those not amenable to biopsy.

RESULTS

Thirty-two lesions were diagnosed as hepatocellular carcinoma (HCC). Contrast-enhanced ultrasound localized hepatocellular carcinoma in 24/32 (75%) lesions, the mean diameter (15.1+/-4.9mm), as measured using computed tomography, being significantly larger than that of the remaining eight lesions (10.5+/-2.1mm). Ultrasound-guided treatment was performed in 19 of the 24 lesions, and transarterial chemoembolization (TACE) was applied for the other five lesions because of difficult percutaneous access. Five of the eight non-visualised lesions were treated by transarterial chemoembolization, and the other three by surgical resection. The beneficial effect of CEUS was significantly greater when the reason for poor initial visualisation was the coarse liver architecture (17/17) than when it was due to adverse location (seven of 15, p<0.005). Fifteen of the CT-detected hypervascular lesions were considered to represent false positives for HCC, based on their behaviour during follow-up.

CONCLUSION

Contrast-enhanced ultrasound with Levovist facilitates the application of percutaneous ultrasound-guided treatment by improving localization of ultrasonically invisible hypervascular hepatocellular carcinomas in the liver.

Detection of Hepatocellular Carcinoma on CT in Liver Transplant Candidates: Comparison of PACS Tile and Multisynchronized Stack Modes

OBJECTIVE

The objective of our study was to compare CT image interpretation using PACS tile and multisynchronized stack modes with respect to speed and observer performance for the detection of hepatocellular carcinoma (HCC) in liver transplant candidates.

MATERIALS AND METHODS

Institutional review board approval was obtained, but informed consent was not required for this retrospective study. Sixty-seven patients underwent dynamic multiphasic CT within 3 months before liver transplantation. Interval reviews using tile and multisynchronized stack modes were performed independently by four reviewers with various levels of experience to determine the presence of HCC using a five-point confidence scale. Observer performance was compared using jackknife free-response receiver operating characteristic (ROC) analysis. The time required to interpret the CT scans using each mode was recorded and compared using the paired Student's t test.

RESULTS

Twenty-seven patients had 48 HCC nodules. The mean free-response ROC figures of merit for detecting HCC were significantly higher using the multisynchronized stack mode (0.731) than using the tile mode (0.662) (F-statistic = 6.603, p = 0.012). The 95% CIs for the task were -0.125 - -0.016. The time used for image analysis was also significantly shorter with the stack mode (63 to approximately 75 seconds) than with the tile mode (94 to approximately 191 seconds) for all four reviewers (p < 0.0001).

CONCLUSION

Multisynchronized stack viewing of multiphasic dynamic CT scans significantly increases the detection rate of HCC in liver transplant candidates. It also significantly shortens the interpretation time compared with tile viewing.

Transient hepatic echogenicity difference on contrast-enhanced ultrasonography: sonographic sign and pitfall

OBJECTIVE

The purpose of this study was to report and analyze a new contrast-enhanced ultrasonographic (CEUS) imaging finding, the transient hepatic echogenicity difference due to perfusion changes, using computed tomography (CT) as a reference standard.

METHODS

We retrospectively investigated the records of patients evaluated in a 2-year period, selecting those who had undergone both CT and CEUS within 15 days, who had CT evidence of a perfusion abnormality, and who had had a CEUS study that included the malperfused parenchymal area.

RESULTS

There were 30 patients with 44 hepatic perfusion changes on CT scans (28 around liver focal lesions and 16 unrelated to focal lesions). Retrospectively, CEUS allowed recognition of 21 of 28 perifocal transient hepatic attenuation differences (THADs), 6 of 10 subsegmental THADs, 2 of 3 segmental THADs, and 1 of 3 lobar THADs. Only some of these abnormalities had been identified at the original CEUS examinations: 0 of 3 lobar THADs, 1 of 3 segmental THADs, 2 of 10 subsegmental THADs, and 16 of 28 perifocal THADs.

CONCLUSIONS

Contrast-enhanced ultrasonography can show hepatic perfusion abnormalities similar to those well known from CT literature, although with a lower sensitivity. Knowledge of this transient hepatic echogenicity difference phenomenon may be relevant for avoiding incorrect image interpretation or incorrect tumor size measurement and for eventually identifying occult vascular disorders such as venous thrombosis or fistulas.

Dynamic CT for detecting small hepatocellular carcinoma: usefulness of delayed phase imaging

OBJECTIVE

The purpose of this retrospective study was to determine the usefulness of delayed phase imaging for detecting small (< or = 2 cm) hepatocellular carcinomas (HCCs) in patients with liver cirrhosis.

MATERIALS AND METHODS

Triphasic (arterial, portal venous, and delayed phases) dynamic CT was performed in 33 patients with 48 HCCs proven histopathologically and in 65 control subjects. Arterial, portal venous, and delayed phase images were obtained 30 seconds, 68-70 seconds, and 5 minutes after the start of contrast material injection, respectively. Three blinded observers reviewed the images independently and evaluated tumor attenuation. Diagnostic performance for the combination of phases was assessed using receiver operating characteristic (ROC) curve analysis.

RESULTS

On arterial phase images, 28 of the 48 HCCs were hyperattenuating, nine were isoattenuating, and 11 were hypoattenuating. On portal venous phase images, three tumors were hyperattenuating, 17 were isoattenuating, and 28 were hypoattenuating. On delayed phase images, five tumors were isoattenuating, and 43 were hypoattenuating. The mean sensitivity for the combination of arterial and portal venous phase imaging was 86.8%, that for the combination of arterial and delayed phase imaging was 90.3%, and that for the combination of all three phase imaging was 93.8%. The area underneath composite ROC curve (A(Z)) for the combination of all three phase imaging (A(Z) = 0.940) was significantly higher than that for the combination of arterial and portal venous phase imaging (A(Z) = 0.917) and for the combination of arterial and delayed phase imaging (A(Z) = 0.922).

CONCLUSION

Delayed phase imaging is useful for detecting small HCCs and should be included in dynamic CT examinations of patients with liver cirrhosis.

Quadruple-phase MDCT of the liver in patients with suspected hepatocellular carcinoma: effect of contrast material flow rate

OBJECTIVE

The purposes of this study were to evaluate the effect of contrast material flow rate (3 mL/sec vs 5 mL/sec) on the detection and visualization of hepatocellular carcinoma (HCC) with MDCT and the safety profile of iodixanol at different injection rates.

SUBJECTS AND METHODS

In a prospective, randomized multicenter trial, 97 patients (83 men and 14 women, with a mean age of 64 years) suspected of having HCC underwent quadruple-phase (double arterial, portal venous, delayed phase) 4-16-MDCT. Patients were randomized to receive iodixanol, 320 mg I/mL (1.5 mL/kg body weight), at a flow rate of 3 mL/sec (48 patients) or 5 mL/sec (49 patients). Qualitative (lesion detection, image quality) and quantitative (liver and aortic enhancement, tumor-liver contrast) analyses and safety assessment were performed.

RESULTS

Overall, 145 HCCs were detected in the 5 mL/sec group and 100 HCCs in the 3 mL/sec group (p < 0.05). More lesions equal to or less than 1 cm were detected at 5 mL/sec (33 vs 16 lesions). The late arterial phase showed significantly more lesions than the early, arterial phase (133 vs 100 and 96 vs 67 lesions, respectively, p < 0.0001). Hyperattenuating HCCs were better visualized in the late arterial phase at 5 mL/sec (excellent visualization: 54% vs 27%). Using a flow of 5 mL/sec did not increase the rate of patient discomfort or contrast media-related adverse events. Most discomfort in both groups was of mild intensity and there was no severe discomfort.

CONCLUSION

For detection of HCC with MDCT, a higher flow rate of 5 mL/sec is recommended. Visualization of hyperattenuating HCC is improved with no greater discomfort or adverse events.

Multiple intrahepatic vascular shunts causing hyperammoniaemic encephalopathy in a patient without liver cirrhosis

The very rare case of a non-cirrhotic patient with multiple intrahepatic portosystemic and arteriosystemic vascular shunts, presenting with hyperammoniaemic type B encephalopathy and hypoalbuminaemia due to proteinuria, is reported. The correct diagnosis, suspected by abdominal ultrasound and colour-Doppler imaging, was confirmed by hepatic and superior mesenteric angiography. A comparison with the few similar cases existing in the literature is offered.

Postbiopsy Arterioportal Fistula in Patients with Hepatocellular Carcinoma: Clinical Significance in Transarterial Chemoembolization

OBJECTIVE

The purpose of this study was to determine, retrospectively, the frequency of postbiopsy arterioportal fistula in hepatocellular carcinoma and its significance in transarterial chemoembolization (TACE).

MATERIALS AND METHODS

Forty-one patients who underwent percutaneous liver biopsy for diagnosis of hepatocellular carcinoma were referred for TACE. The control population comprised 161 patients referred during the same period who underwent TACE without biopsy. We determined that an arterioportal fistula was present by opacification of the portal vein during the arterial phase of angiography or by opacification with iodized oil during TACE. We considered hepatocellular carcinoma to be responsive to TACE when the sum of iodized oil retention in the tumor and a low-attenuation area on CT was greater than 50% of tumor size. We compared the frequency of arterioportal fistula and the rate of tumor response to TACE in both groups and also evaluated possible factors associated with postbiopsy arterioportal fistula, such as age, sex, Child-Pugh score, tumor size, average number of needle passes, average distance that the needle traversed normal liver before reaching the mass, and average interval between biopsy and TACE.

RESULTS

Twenty-three (56.1%) of 41 patients in the biopsy group and 19 (11.8%) of 161 patients in the control group had an arterioportal fistula (p < 0.001). The rate of tumor response to TACE was 87.8% (36/41) in the biopsy group and 87.0% (140/161) in the control group (p = 0.5932). Of the possible related factors, only tumor size correlated negatively with the occurrence of arterioportal fistula.

CONCLUSION

Percutaneous liver biopsy in hepatocellular carcinoma patients apparently increases the rate of arterioportal fistula but does not seem to affect the rate of tumor response to TACE.

Hepatocellular carcinoma: conventional MRI findings including gadolinium-enhanced dynamic imaging

A great variety of MR pulse sequences for hepatocellular carcinomas (HCCs) are now available. In this article, we reviewed the current MR imaging techniques that are routinely used for hepatic imaging, and described the optimization of these sequences as well as the utility and characteristics of each sequence for the accurate diagnosis of HCCs. Then, we reviewed various MR imaging findings of advanced and early HCCs with emphasis on signal intensity and hemodynamic patterns. Finally, we described the value of multi-arterial-phase contrast-enhanced dynamic MR imaging of the whole liver with excellent temporal resolution for evaluating transitional hemodynamics of hepatic lesions during the six arterial phases.

Multiple non-tumorous arterioportal shunts due to chronic liver disease mimicking hepatocellular carcinoma: outcomes and the associated elevation of alpha-fetoprotein

PURPOSE

To elucidate the morphologic appearance of small non-tumorous arterioportal (AP) shunts mimicking hepatocellular carcinoma on helical computed tomography (CT), their associated outcomes, and their relationship with alpha-fetoprotein levels in patients with chronic liver disease.

MATERIALS AND METHODS

Ten patients with multiple AP shunts on dynamic helical CT were evaluated. A non-tumorous AP shunt was defined as no increase or spontaneous regression in size on follow-up CT scans. The number and shape of shunts more than 5 mm in diameter were studied on a segment-by-segment basis on the initial CT scan, and compared with those on follow-up CT scans. Alpha-fetoprotein levels were measured at the same time as CT scanning was performed.

RESULTS

Ten patients with 86 AP shunts (range 0.5-3.8 cm; mean 1.2 cm) underwent arterial, portal and delayed phase imaging of the entire liver. The AP shunts were geographic (44%), round (33%) or wedge-like (23%) in shape. All shunts changed from high- to iso-attenuation on the delayed phase CT. A follow-up CT (mean 73 days) revealed spontaneous disappearance in all but three (97%) of the 86 AP shunts. Furthermore, 16 new shunts appeared in different segments from the primary ones in four patients. The rapid elevation of alpha-fetoprotein levels to 5-10-fold higher than the baseline level was recognized at the same time as the initial appearance of AP shunts in three patients (30%). Further follow-up CT scans detected solitary hepatocellular carcinomas in four patients at a mean 1283 days after the initial CT. The location of the hepatocellular carcinomas was quite different from those of the initially recognized AP shunts.

CONCLUSIONS

Non-tumorous AP shunts varied in CT appearance and demonstrated iso-attenuation in the delayed phase, most of which disappeared within 4 months. For these multiple small stains in chronic liver disease, periodic follow-up CT is recommended rather than alternative invasive interventions, even though there was an association with rapid elevation of alpha-fetoprotein levels.

Hemodynamic and morphologic changes of peripheral hepatic vasculature in chronic liver disease: a preliminary study by contrast-enhanced coded phase-inversion harmonic sonography

To investigate whether observing the morphology of the peripheral hepatic vasculature and the hemodynamics of microbubble arrival time in these vessels can provide useful information for the diagnosis of liver disease, Five normal volunteers and 16 patients were studied by contrast-enhanced coded phase-inversion harmonic sonography. Vessel images of the peripheral vessels were observed in real time after intravenous injection of Levovist. The time when the microbubbles appeared in the peripheral vessels was measured. Three patterns of morphologic change of the peripheral hepatic vasculature were seen, marked, slight, and no abnormal changes. The microbubble arrival times at the peripheral vessels were all shorter in patients with cirrhosis than chronic hepatitis or normal subjects. Marked, slight, and no abnormal morphologic changes of the peripheral hepatic vasculature in patients with liver cirrhosis were found in five, one and zero of the six patients, respectively. Those patients with chronic hepatitis, were found in one, six and three of the ten patients, respectively. There was a significant difference among the different groups (P < 0.001). Evaluating the hemodynamics and morphology by contrast-enhanced coded pulse-inversion harmonic sonography may offer useful information in the diagnosis of liver disease.

Indeterminate small, low-attenuating hepatocellular nodules on helical CT in patients with chronic liver disease: 2-year follow-up

To evaluate the clinical significance of indeterminate, small, low-attenuating nodular lesions on helical dynamic computed tomography (CT) in chronic liver diseases, CT images were reviewed retrospectively in 281 patients. Indeterminate, low-attenuating nodular lesions less than 20 mm in diameter were followed for 24 to 35 months. Of 127 nodules in 73 patients, 21 nodules turned out to be hepatocellular carcinomas (16%), 25 nodules (20%) became larger, while the remaining 81 nodules (64%) remained unchanged or disappeared. Some low-attenuating nodules larger than 10 mm in diameter may develop into hepatocellular carcinoma.

Liver and Biliary System: Evaluation by Multidetector CT

CT commonly is indicated for the evaluation of suspected hepatic and biliary pathology. The recent introduction of multidetector CT (MDCT) provides unique capabilities that are valuable especially in hepatic volume acquisitions, combining short scan times, narrow collimation, and the ability to obtain multiphase data. These features result in improved lesion detection and characterization. Concomitant advances in computer software programs have made three-dimensional applications practical for a range of hepatic image analyses and displays. This article discusses the specific areas of hepatic and biliary pathology where MDCT has a significant diagnostic impact.

Hemodynamic and morphologic changes of peripheral hepatic vasculature in cirrhotic liver disease: A preliminary study using contrast-enhanced coded phase inversion harmonic ultrasonography

AIM: To provide the useful information for the diagnosis of liver cirrhosis by observing the morphology of peripheral hepatic vessels and the hemodynamics of microbubble arrival time in these vessels.

METHODS: Twenty-one subjects including 5 normal volunteers and 16 patients (liver cirrhosis, n=10; chronic hepatitis, n=6) were studied by contrast-enhanced coded phase inversion harmonic sonography (GE LOGIQ 9 series) using a 6-8 MHz convex-arrayed wide-band transducer. The images of peripheral hepatic artery, portal and hepatic vein were observed in real-time for about 2 min after intravenous injection of Levovist. The time when microbubbles appeared in the peripheral vessels (microbubble arrival time) was also recorded. The morphologic changes of peripheral hepatic vasculature were classified as marked, slight, and no changes based on the regularity in caliber, course, ramification, and the delineation of vessels compared to normal subjects.

RESULTS: The microbubble arrival time at peripheral artery, portal, and hepatic vein was shorter in cirrhotic patients than in chronic hepatitis patients and normal subjects. The marked, slight and no morphologic changes of peripheral hepatic vasculature found in 5 (5/6, 83.3%), 1 (1/6, 16.7%), and 0 (0/6, 0%) liver cirrhosis patients, respectively, and in 1 (1/10, 10%), 6 (6/10, 60%), and 3 (3/10, 30%) chronic hepatitis patients, respectively. There was a significant difference between the two groups (P<0.001).

CONCLUSION: Evaluation of the hemodynamics and morphology of peripheral hepatic vasculature by contrast-enhanced coded pulse inversion harmonic sonography can provide useful information for the diagnosis of liver cirrhosis.

Outcome of small (10-20 mm) arterial phase-enhancing nodules seen on triphasic liver CT in patients with cirrhosis or chronic liver disease

OBJECTIVE

To determine the outcome of small arterial phase-enhancing nodules, 10-20 mm, seen on serial triphasic liver CT scans in a hepatocellular cancer-screening population.

METHODS

Of 58 patients referred for triphasic liver CT, 20 (18 men, 2 women) with 32 nodules formed the study group. Each patient in the study group had at least two CT scans, a minimum of 3 months follow-up, at least one nodule measuring 10-20 mm, no prior diagnosis of hepatocellular carcinoma, and no nodule greater than 20 mm typical of hepatocellular carcinoma at the time of the first CT. Serial CT scans were reviewed by an abdominal imaging radiologist who classified the nodules as stable, decreasing, or increasing in size.

RESULTS

A mean of six CT studies (range 2-10) were performed for each patient with a mean follow-up of 25 months (range 4-47 months). Of 32 nodules, 14 (44%) were stable, 9 (28%) decreased, and 9 (28%) increased in size. Nodules that increased in size were treated as hepatocellular carcinoma: six were hepatocellular carcinoma, two were biopsy negative but showed recurrent tumor after radiofrequency ablation, and one was a high-grade dysplastic nodule. Mean doubling time for these nine nodules was 5.7 months (range 2.3-10.8 months).

CONCLUSIONS

Most small (10-20 mm) arterial phase-enhancing nodules seen on triphasic liver CT are not hepatocellular carcinoma. Serial CT is useful to guide management in these patients. Growth of small arterial phase-enhancing nodules can be used as an indicator that the nodule should be treated as hepatocellular carcinoma.

Imaging diagnosis of hepatocellular carcinoma with differentiation from other pathology

Recent advances in liver imaging techniques and better understanding of imaging findings have facilitated the detection and characterization of hepatocellular nodules in a cirrhotic liver. It is important to recognize that various types of benign nodules and pseudolesions are identified on all imaging scans performed for the diagnosis of hepatocellular carcinoma. An accurate differentiation between them is critical for adequate management of cirrhotic patients. Unfortunately, any of the imaging tests and even percutaneous biopsy are not diagnostic for borderline lesions. Intimate collaboration of hepatologists, pathologists, surgeons, and radiologists with reasonable imaging and clinical criteria estimating the degree of malignancy is imperative.

MRI in detection of hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the commonest malignancy of the liver and is usually due to cirrhosis. Early detection of HCC and the premalignant dysplastic nodules has implications on the management options of tumor ablation, liver resection and transplantation. Magnetic resonance imaging is useful for the detection and characterization of lesions, in the identification of dysplastic nodules and their malignant transformation into HCC.

Detection of hepatocellular carcinoma: comparison of Gd-DTPA- and ferumoxides-enhanced MR imaging

The aim was to compare the diagnostic performance of dynamic Gd-DTPA- and ferumoxides-enhanced MRI for hepatocellular carcinoma (HCC). Twenty-five patients with chronic hepatitis or liver cirrhosis underwent both dynamic gadopentetate- and ferumoxides-enhanced MRI studies of the liver for HCC detection on the same day. MR data of both studies were retrospectively and independently analyzed. Two observers determined in consensus the grade of diffuse fibrotic liver changes (mild, moderate or severe) and the number of focal lesions. HCCs were confirmed by histology (n=22) and/or follow-up studies for at least six months (n=64). Differences in results obtained from both MR data sets were tested for significance with the McNemar's test (p<0.05). Ferumoxides-enhanced MR images detected 84 of 99 hepatic lesions, including 82 of 86 HCCs and 2 false positive, nonmalignant lesions, while Gd-DTPA-enhanced MR images detected 92 of 99 hepatic lesions, including 81 of 86 HCCs and 11 false positive, nonmalignant lesions. Sensitivity of MRI for detection of HCCs was not significantly different between ferumoxides-enhanced (95.3%; p>0.05) and Gd-DTPA-enhanced scans (94.2%). Gd-DTPA- and ferumoxides-enhanced MRI perform equally well for HCC detection. The majority of small hypervascular hepatic lesions, detected on dynamic Gd-DTPA-enhanced MRI but not on ferumoxides-enhanced MRI, represent no HCCs.

Multidetector CT of hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common causes of cancer death worldwide. Numerous surgical and nonsurgical treatment options are available for the management of patients with HCC. Successful long-term outcome is dependent on early detection of HCC, as well as accurate delineation of the number and location of tumor nodules. We present the different manifestations of hepatocellular carcinoma as depicted by multidetector-row CT with advanced image processing.

A novel display of reconstruction computed tomography for the detection of small hepatocellular carcinoma

PURPOSE

To evaluate the usefulness of the alternate display of arterial and equilibrium phase images (ADAEI) of 2 mm-pitch reconstruction computed tomography (CT) in the detection of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

One hundred and eleven nodules in 72 patients were confirmed as HCC by radiology, histology, or clinical course. Blinded to the outcome, we retrospectively reviewed the CT images obtained with dual-phase spiral CT (Radix Prima, Hitachi Medical, Tokyo, Japan) by ADAEI and by conventional display on cut films. Scanning for the arterial and equilibrium phases was initiated at 33 and 120 s, respectively, after starting the injection of contrast medium (iopamidol 3 ml/s) with a section thickness of 5 mm and a table feed speed of 5-7 mm/s. In ADAEI, all images were reconstructed with a 2-mm interval, and displayed on the monitor in an alternating fashion so that an image in the arterial phase was followed by the corresponding image in the equilibrium phase, and then by the next pair of images in the craniocaudal direction.

RESULTS

All 20 HCC nodules larger than 20 mm in diameter were detected by both ADAEI and the conventional display (NS). On the other hand, detectability of smaller HCC nodules was 91/91 (100%) and 72/91 (79%), respectively (P<0.0001 by McNemar' test). False-positively identified HCC nodules, including those diagnosed as possible HCC, were 11 by ADAEI and eight by conventional display.

CONCLUSION

The novel, alternate display, ADAEI of 2 mm-pitch reconstruction CT images was useful in detecting small HCC nodules while not requiring additional equipment or expense.

Hepatocellular carcinoma - issues in imaging

The imaging diagnosis of hepatocellular carcinoma is challenging as benign hypervascular lesions and arterioportal shunts (pseudolesions) often mimic it. There is also overlap in the imaging appearance from dysplastic and regenerating nodules. This article addresses the above imaging problems, examines proposed non-invasive imaging criteria for the diagnosis of hepatoma and discusses the optimal imaging modality.

Early-enhancing nonneoplastic lesions on gadolinium-enhanced magnetic resonance imaging of the liver following partial hepatectomy

PURPOSE

To assess the frequency, imaging findings, and significance of early-enhancing nonneoplastic (EN) lesions with gadolinium-enhanced magnetic resonance imaging (MRI) of the liver following partial hepatectomy.

MATERIALS AND METHODS

We retrospectively reviewed MR images after partial hepatectomy in 30 patients. Postoperative MRI was performed in 1-12 months (mean, 3.7 months) after partial hepatectomy. We defined the EN lesion as a lesion that was ill defined; irregular, wedge shaped, or serpiginous; located along the liver edge; not visible on unenhanced MR images; did not appear hypointense on portal venous- or equilibrium-phase images; or a combination of those imaging findings.

RESULTS

A total of 39 EN lesions (size range, 5-60 mm; mean, 25.2 mm) in 19 patients and 17 recurrent tumors (size range, 5-50 mm; mean, 16.8 mm) in 10 patients newly appeared after partial hepatectomy. The EN lesions were diagnosed as pseudolesions by the second postoperative follow-up MRI in 17 patients or contrast-enhanced computed tomography (CT) in two. A total of 13 EN lesions (33%) were located along the liver edge and 20 (51%) were adjacent to the resected area. The shape was circular in 11 (28%), oval in three (8%), irregular in 11 (28%), wedge shaped in five (13%), and serpiginous in nine (23%). No EN lesion showed hypointensity on gadolinium-enhanced portal venous-phase or equilibrium-phase images. A total of 14 EN lesions (36%) showed slight hyperintensity on T2-weighted images. The confidence levels for malignancy probability assigned by blinded radiologists were lower with EN lesions than with recurrent tumors (P < 0.001).

CONCLUSION

EN lesions are frequently seen in MRI following partial hepatectomy, and occasionally are slightly hyperintense on T2-weighted images, mimicking malignant tumors. However, most EN lesions can be correctly diagnosed with MRI findings.

Multiarterial phase dynamic MRI of small early enhancing hepatic lesions in cirrhosis or chronic hepatitis: differentiating between hypervascular hepatocellular carcinomas and pseudolesions

OBJECTIVE

The purpose of this study was to assess the value of multiarterial phase contrast-enhanced dynamic MRI of the whole liver obtained during a single breath-hold for small early enhancing hepatic lesions in patients with cirrhosis or chronic hepatitis, emphasizing the distinction between hypervascular hepatocellular carcinomas and pseudolesions.

MATERIALS AND METHODS

The study population included 40 patients with cirrhosis or chronic hepatitis who had small early enhancing hepatic lesions (a total of 70 lesions: 40 hepatocellular carcinomas, 30 pseudolesions). All patients underwent multiarterial phase contrast-enhanced dynamic MRI (six phases) of the whole liver during a single breath-hold.

RESULTS

Twenty-one (53%) of 40 hypervascular hepatocellular carcinomas showed rapid central washout after early enhancement of the lesion as well as peritumoral coronal enhancement, but these findings were not observed in any hypervascular pseudolesions (p < 0.001). In 19 hepatocellular carcinomas without rapid central washout, early enhancement of the lesion appeared at the second, third, or fourth phase (mean, 2.5 phases). In eight of these 19 hepatocellular carcinomas, lesion enhancement disappeared by the sixth phase. Conversely, in 30 hypervascular pseudolesions, early enhancement of the lesion appeared at the second, third, fourth, or fifth phase (mean, 3.0 phases). In 28 of these 30 pseudolesions, lesion enhancement continued until the sixth phase.

CONCLUSION

Rapid central washout after the early enhancement of the lesion and coronal enhancement surrounding the lesion are highly specific and diagnostic findings of small hypervascular hepatocellular carcinomas if present at multiarterial phase contrast-enhanced dynamic MRI. Hypervascular pseudolesions tend to show prolonged enhancement during the arterial phase compared with hypervascular hepatocellular carcinomas.

Hepatic involvement in hereditary hemorrhagic telangiectasia: CT findings

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber disease, is an autosomal-dominant vascular disease characterized by mucocutaneous or visceral angiodysplastic lesions (telangiectases and arteriovenous malformations) that may be widely distributed throughout the cardiovascular system. The recognition of mucocutaneous telangiectases, the occurrence of spontaneous and recurrent episodes of epistaxis, the presence of visceral involvement, and a family history of this disease are the clinical criteria that allow diagnosis. In comparison with skin, lungs, gastrointestinal tract, and brain involvement, hepatic involvement defined by clinical criteria alone has long been considered uncommon. Our experience with a large group of HHT patients, even those asymptomatic for liver involvement, demonstrates that it is more frequent than reported and is characterized by the presence of intrahepatic shunts, disseminated intraparenchymal telangiectases, and other vascular lesions. Congestive cardiac failure, portal hypertension, portosystemic encephalopathy, cholangitis, and atypical cirrhosis have been reported as possible serious complications related to this condition. Thus, a correct diagnosis is important, and diagnostic imaging has a fundamental role in detecting alterations involving the liver. The possibilities to perform a multiphasic study and to provide high-quality multiplanar and angiographic reconstructions, gives multidetector row helical computed tomography the ability to detect and characterize the complex anatomopathologic alterations typical of this disease.

Screening and treatment for hepatocellular carcinoma

Surveillance for hepatocellular carcinoma (HCC) has become routine despite a lack of evidence of efficacy. Suitable candidates for surveillance include patients with cirrhosis and some subsets of noncirrhotic chronic hepatitis B carriers. The best surveillance testis ultrasonography at 6- to 12-month intervals. Serological tests are less effective. Defining an abnormal result is difficult in the cirrhotic liver. Diagnosis requires radiological investigations and may require a biopsy if the lesion is between 1 and 2 cm in diameter. In the face of an abnormal surveillance test and failure to confirm the diagnosis initially, enhanced follow-up is required. HCC can be treated for cure by liver transplantation, resection, or local ablation. For patients with suitable lesions, liver transplantation offers the best form of therapy. Chemoembolization offers increased survival over no therapy. Several experimental therapies are being investigated.

Intrahepatic portal-to-portal venous shunts in cirrhosis: a potential mimic of hepatocellular carcinoma

Two intrahepatic portal-to-portal venous shunts demonstrated at computed tomography (CT) and ultrasound in a 40-year-old woman with cirrhosis are described. The shunts appeared as hypervascular hepatic foci on CT, simulating multifocal hepatocellular carcinoma. Follow-up multiphase CT with multiplanar reformation and Doppler ultrasound confirmed the correct diagnosis. Recognition of intrahepatic portal-to-portal venous shunts as a rare mimic of hepatocellular carcinoma in cirrhosis should prevent misinterpretation or inappropriate management.

Pathogenesis and screening for hepatocellular carcinoma

Hepatocellular carcinoma is an increasingly common clinical problem. Investigators have begun to understand aspects of the pathogenesis of the tumor, mainly from a morphologic point of view. Preneoplastic lesions and early cancer may be difficult to distinguish radiologically. Nonetheless, programs for surveillance of liver cancer have been developed. Little uniformity exists in methods of surveillance, and even less in methods of investigation and follow-up after an abnormal result is obtained. This article attempts to bring some rigor to the understanding of hepatocellular carcinoma.

T2-weighted MR imaging in the assessment of cirrhotic liver

PURPOSE

To assess if T2-weighted magnetic resonance (MR) imaging provides added diagnostic value in combination with dynamic gadolinium-enhanced MR imaging in the detection and characterization of nodular lesions in cirrhotic liver.

MATERIALS AND METHODS

Two readers retrospectively and independently analyzed 54 MR imaging studies in 52 patients with cirrhosis. In session 1, readers reviewed T1-weighted and dynamic gadolinium-enhanced images. In session 2, readers reviewed T1-weighted, dynamic gadolinium-enhanced, and respiratory-triggered T2-weighted fast spin-echo images. Readers identified and characterized all focal lesions by using a scale of 1-4 (1, definitely benign; 4, definitely malignant). Multireader correlated receiver operating characteristic (ROC) analysis was employed to assess radiologist performance in session 2 compared with session 1. The difference in the areas under the ROC curves for the two sessions was tested. In a third session, readers assessed conspicuity of biopsy-proved lesions on T2-weighted MR images by using a scale of 1-3 (1, not seen; 3, well seen) and identified causes of reduced conspicuity.

RESULTS

Two additional benign lesions were detected by each reader in session 2. Fifty-five lesions had pathologic verification, including 32 malignant, three high-grade dysplastic, and 20 benign nodules. There was no significant difference in the area under the ROC curves between the two sessions (P =.48). Thirty-two lesions were inconspicuous on T2-weighted MR images because of parenchymal heterogeneity, breathing artifacts (particularly in patients with ascites), and lesion isointensity with liver parenchyma. T2-weighted MR imaging was useful in the evaluation of cysts and lymph nodes.

CONCLUSION

T2-weighted MR imaging does not provide added diagnostic value in the detection and characterization of focal lesions in cirrhotic liver.

Hepatocellular carcinoma in advanced liver cirrhosis: CT detection in transplant patients

Computed tomography (CT) is being used as the standard pretransplantation imaging for recipients and donors in the evaluation of liver volume, liver reserve function, vascular anatomy, diagnosis of hepatocellular carcinoma and metastasis, and global information of the abdominal cavity. Whereas CT detection of hepatocellular carcinoma in non-cirrhotic patients is satisfactory, detection sensitivity in severely cirrhotic patients is limited, with a reported sensitivity of 53% to 68%. Tumors smaller than 2 cm are more difficult to detect. Innumerable regenerative nodules, localized or diffuse fibrosis, arterioportal shunts, nodular surface, and distorted anatomy in end-stage liver cirrhosis make it difficult to detect small hepatocellular carcinoma. Because of the shortage of cadavers and living donors, judicious use of CT is necessary in the selection of candidates and the decision of priority for liver transplantation in patients with advanced liver cirrhosis.

Study on hepatocelluar carcinoma-associated hepatic arteriovenous shunt using multidetector CT

AIM: To investigate multidetector CT (MDCT) findings of hepatocelluar carcinoma (HCC)- associated hepatic arteriovenous shunt (HAVS) and to evaluate their clinical significance.

METHODS: Thin-slice and dynamic enhancement MDCT of HAVS was performed on 56 patients with HCC. MDCT findings, including those of portal veins, hepatic veins, superior mesenteric veins, splenic veins, HCC foci, liver parenchyma without HCC foci, spleens, and thromboses in portal veins and hepatic veins, were all confirmed by digital subtract angiography and analyzed.

RESULTS: MDCT demonstrated earlier enhancement of main portal trunks and/or the first order branches than that of superior mesenteric veins or splenic veins (n = 31). One patient had strong early enhancement of left hepatic vein with thromboses in left hepatic vein and upper part of inferior vena cava and 1 patient had transient patchy enhancement peripheral to HCC foci in late hepatic arterial phase among them. It demonstrated stronger opacification of main portal trunks and/or the first order branches than that of superior mesenteric veins or splenic veins (n = 18), and earlier enhancement of the second order and smaller branches of portal veins than that of main portal trunks (n = 4), stronger opacification of the second order and smaller branches of portal veins than that of main portal trunks (n = 3), with transient patchy enhancement (n = 3) or wedge-shaped enhancement (n = 4) peripheral to HCC foci in late hepatic arterial phase. Enhancement degree of HCC foci was all decreased. As for 49 patients with severe or moderate shunts, enhancement degree of liver parenchyma without HCC foci was increased with heterogeneous density, but enhancement degree of spleens was decreased. There were thromboses in main portal trunks and/or the first order branches in 32 patients.

CONCLUSION: The main MDCT findings of HCC-associated HAVS are earlier enhancement and stronger opacification of portal veins and/or hepatic veins. Understanding of these findings will contribute to the diagnosis and prognosis of the disease and improve therapy for the patients.

Early-enhancing Non-neoplastic Lesions on Gadolinium-enhanced MRI of the Liver

AIM

To assess the frequency, cause, and significance of early-enhancing, non-neoplastic (EN) lesions on gadolinium-enhanced magnetic resonance imaging (MRI) of the liver performed for the detection of malignant hepatic tumours.

MATERIALS AND METHODS

From September 1997 to September 2000, we reviewed the images of 125 patients, suspected of having hepatic tumours, in whom (1) gadolinium-enhanced triphasic dynamic gradient-recalled-echo (GRE) imaging in addition to unenhanced T1- and T2-weighted MRI was performed, (2) conventional angiography and combination computed tomography (CT) hepatic arteriography and CT during arterial portography were performed within 2 weeks of the MRI, and (3) definitive surgery within 2 weeks of the MRI or follow-up study by means of intravenously contrast-enhanced CT or MRI in 10 months or more was performed. Angiographic studies were correlated to determine the underlying causes of the EN lesions.

RESULTS

We found 78 EN lesions in 36 patients (29%), ranging in size from 4 and 50 mm (mean, 12.2 mm). From the MR reports, our radiologists had prospectively diagnosed EN lesions as probable malignant tumours in eight (10%), possible malignant tumours in 36 (46%), and probable non-neoplastic lesion in 34 (44%). EN lesions were found in 27 of 81 (33%) cirrhotic patients and in nine of 44 (20%) non-cirrhotic patients. Fifty-one EN lesions (65%) were located along the liver edge. The shape was circular in 42 (54%), oval in 14 (18%), irregular in 12 (15%), wedge-shaped in seven (9%), and fan-shaped in three (4%). Twenty EN lesions (26%) appeared slightly hyperintense on T2-weighted images. The causes were non-neoplastic arterio-portal shunting in 48 (62%), cystic venous drainage in four (5%), rib compression in four (5%), aberrant right gastric venous drainage in two (3%), and unknown in 20 (26%).

CONCLUSION

Over half the number of EN lesions were caused by non-neoplastic arterio-portal shunting, occasionally showing slight hyperintensity on T2-weighted images. On MR images the non-neoplastic nature of the EN lesion was often ascertained. Radiologists should not overcall EN lesions as malignant as the patients involved would be inappropriately considered inoperable. In problematic cases, further investigation with angiographic CT or follow-up imaging studies should be performed.

Pseudolesões hepáticas na ressonância magnética: ensaio iconográfico

A ressonância magnética é uma técnica de grande importância na avaliação do fígado. Assim como na tomografia computadorizada helicoidal, o emprego de aquisições rápidas, em fases diferentes da vascularização hepática, auxilia na detecção e caracterização de tumores. Contudo, algumas armadilhas podem confundir e dificultar a interpretação do exame, simulando lesões parenquimatosas. Estas armadilhas têm forma, localização e características variadas, sendo denominadas de pseudolesões. Podem ser decorrentes de diversos fatores, como alterações perfusionais, esteatose focal, parênquima hepático preservado na esteatose difusa, artefatos, entre outros. É muito importante que sejam reconhecidas, para que não sejam causas de resultados falso-positivos. O objetivo deste ensaio é classificar e ilustrar as diversas pseudolesões hepáticas na ressonância magnética, com breve descrição delas, e alternativas para diferenciá-las das lesões do parênquima.

Pseudolesões hepáticas na tomografia computadorizada helicoidal: ensaio iconográfico

A tomografia computadorizada helicoidal é largamente empregada na avaliação do parênquima hepático e tem grande importância no planejamento clínico e cirúrgico. O fígado é o órgão que mais se beneficia de aquisições helicoidais, em fases diferentes da perfusão do parênquima, pela sua dupla vascularização e pela diferença de aporte sanguíneo entre tumores e parênquima sadio. Entretanto, várias armadilhas diagnósticas podem ser encontradas, dificultando a análise e prejudicando a diferenciação entre lesões verdadeiras e pseudolesões, principalmente aos olhos de radiologistas menos experientes. Essas pseudolesões têm forma, localização e características variadas, podendo simular lesões parenquimatosas. É de fundamental importância que estejamos aptos a reconhecê-las, no sentido de interpretar corretamente as imagens tomográficas. O objetivo deste ensaio é classificar e ilustrar as diversas pseudolesões hepáticas pela tomografia computadorizada helicoidal, com uma breve descrição dessas lesões e com alternativas para diferenciá-las das lesões do parênquima.