Significance of hyperattenuating and contrast-enhancing hepatic nodules detected in the cirrhotic liver during arterial phase helical CT in pre–liver transplant patients: radiologic–histopathologic correlation of explanted livers

Background: Hyperattenuating nodules detected by arterial phase helical computed tomography (HCT) in patients with cirrhosis usually are believed to represent hepatocellular carcinomas (HCCs). We correlated HCT morphology of hyperattenuating hepatic nodules detected during arterial phase scans with the histopathology of explanted livers of patients with hepatic cirrhosis undergoing liver transplantation. Methods: Three hundred fifty-four patients had arterial and portal phase HCT performed before subsequent hepatic transplantation. Each patient received 180 mL of contrast by power injection at 5 mL/s. All hyperattenuating nodules detected on arterial phase HCT were assessed for morphology and evidence for contrast enhancement. Explanted livers in all patients were then sectioned at 10-mm intervals, and the histology of the nodules was correlated with the HCT findings. Results: Sixty-one hyperattenuating nodules were detected on the arterial phase HCT in 43 patients: 41 nodules were benign regenerating nodules (RN), three were dysplastic nodules (DP), and 17 were HCCs. Most RN/DP nodules were 5–20 mm in diameter, had distinct margins, were homogeneous, and were isoattenuating on precontrast, portal, and delayed scans. Thirty-six showed positive contrast enhancement and displayed a wide range of attenuation profiles. HCC nodules were 6–50 mm. All showed positive contrast enhancement and displayed a wide range of attenuation profiles. Conclusion: Hyperattenuating nodules seen on arterial phase HCT are likely to be RN/DP nodules. In many cases, it is not possible to distinguish between RN/DP and HCC. Thus, clinical decisions regarding inclusion criteria for transplantation based on CT morphology of liver lesions may be tenuous.     

Optimal phases of dynamic CT for detecting hepatocellular carcinoma: evaluation of unenhanced and triple-phase images

Background: To determine the optimal phases of dynamic computed tomography (CT) for detecting hepatocellular carcinoma (HCC). Methods: Fifty-two patients with 85 HCC nodules were examined by means of unenhanced and triple-phase CT images of the whole liver. The time for obtaining the arterial-phase images was 25–55 s after intravenous bolus injection of contrast material, the time for obtaining the portal venous-phase images was 65–100 s, and the time for obtaining late-phase images was 145 s to 4 min. Detectability of the HCC nodules for all phases was statistically compared. Results: The detection rates for the arterial- and late-phase images were significantly higher than for the unenhanced and portal venous-phase images (p < 0.01). The combination of arterial- and late-phase images showed the same number of HCC nodules in the same number of patients as did the combination of unenhanced and triple-phase images. Conclusion: The combination of the arterial- and late-phase imagings was best for detecting HCC nodules. Received: 8 July 1998/Revision accepted: 18 November 1998     

Giant hyperplasia of the caudate lobe of the cirrhotic liver: correlation with an anomaly of the caudate portal branch

Different imaging appearances of giant hyperplastic change of the caudate lobe of the liver are presented in a patient with liver cirrhosis. The mass like caudate lobe was isoechoic on ultrasound, hypodense on postcontrast computed tomography (CT), hyperintense on T1-weighted magnetic resonance, images and isointense on T2-weighted images. These imaging findings are similar to those of dysplastic nodule in cirrhotic liver. The caudate lobe received normal portal flow on CT during arterial portography, but superior mesenteric arteriography showed precocious or early division of the caudate portal branch. We suspect that caudate hyperplastic change may be correlated to anomalous caudate portal vein branch.     

Logistic advantages of four-section helical CT in the abdomen and pelvis

Background: Multisection helical computed tomography (CT) has the potential for providing data sets with better section profiles, more anatomic coverage, and shorter breath-holding periods. Our purpose was to quantitate these advantages in a clinical setting when imaging the abdomen and pelvis. Methods: CT parameters including collimation, timing, z-axis coverage, and milliamperes were gathered retrospectively for the image set of both single-section (GE CT/i with 0.8-s rotation) and four-section (GE QX/i Lightspeed with 0.8-s rotation) helical CT scanners. Data were recorded for the abdomen and pelvis CT (n= 30 each), dual-phase liver CT including the pelvis (n= 15 each), and dual-phase pancreas CT (n= 15 each). Results: The abdominal and pelvic CT averaged 128.4 ± 5.4 s for single-section scanners (70-s delay, two breath-holds of 21.1 and 17.7 s with a 19.5-s interscan delay) and 92.2 ± 2.2 s for the four-section scanner (70-s delay and a 22.2-s breath-hold; p < 0.0001). For the dual liver and pelvis CT, single-section scanners averaged 119.9 ± 7.5 s (30-s delay, 15.8-s arterial phase, 20.0-s interscan delay, 21.2-s venous phase, 19.5-s interscan delay, and 14.2 s for the remaining abdomen and pelvis), whereas the four-section scanner averaged 86.8 ± 2.5 s (30-s delay, 6.7-s arterial phase, 27.9-s interscan delay, and 21.8-s venous phase including the pelvis; p < 0.0001). For the dual pancreas CT, single-section scanners averaged 86.7 ± 2.5 s (20-s delay, 28.3-s arterial phase, 17.8-s interscan delay, 21.7-s venous phase), whereas the four-section scanner averaged 78.0 ± 2.9 s (20-s delay, 9.7-s arterial phase, 30.7-s interscan delay, 13.0-s venous phase; p < 0.0001). Conclusion: CT scanners having four-section technology can reduce overall data acquisition times by 10–30% and total milliamperes by 50–60% depending on the protocol with thinner slice profiles. RID=" ID=" <E5>Correspondence to:</E5> R. C. Nelson Received: 8 December 1999/Revision accepted: 22 March 2000     

Methodological assessment of combined spiral CT angiography and CT arterial portography

Background: To assess an optimal methodology of combined spiral computed tomographic (CT) angiography (CTA) and CT arterial portography (CTAP) for detection and characterization of liver tumors. Methods: We performed spiral CTAP only in five patients with 30–32% contrast (subset A), CTAP combined with preceding spiral CTA using 30–32% contrast in 19 (subset B), and CTAP combined with preceding spiral CTA with 60–64% contrast in seven (subset C). The CT numbers of the aorta immediately before preceding CTA and subsequent CTAP and the CT numbers of malignant tumor and liver parenchyma with CTAP were measured. Results: The differences of the CT number between the malignant tumor and liver parenchyma on CTAP were 61.1–161.8 (mean ± SD, 114.5 ± 39.3) HU, 50.7–164.8 (104.2 ± 31.2) HU, and 101.2–368.3 (219.5 ± 90.5) HU in subsets A, B, and C, respectively. Two cavernous hemangiomas showed pathognomonic findings with preceding CTA. Conclusion: Combination of preceding spiral CTA and subsequent spiral CTAP using 30% contrast with a 5-min interval is an optimal method for detection and characterization of liver tumors. Received: 14 December 1995/Accepted after revision: 13 February 1996     

Diffusion-weighted MR imaging with single-shot echo-planar imaging in the upper abdomen: preliminary clinical experience in 61 patients

Background: To determine the potential ability of diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar imaging (DW imaging) in the upper abdomen by apparent diffusion coefficient (ADC) and signal:intensity ratio (SIR) measurements. Methods: DW imaging was performed in 61 clinical patients. ADCs in the liver, pancreas, spleen, kidney, and different pathological conditions were calculated. Spleen-to-liver SIR and segmental intensity difference of the liver (SID) were also calculated. Results: The mean ADCs (mm²/s) were 2.28 × 10⁻³± 0.07 in the liver, 1.44 × 10⁻³± 0.05 in the spleen, 1.94 × 10⁻³± 0.19 in the pancreas, and 5.76 × 10⁻³± 0.06 in the kidney. The mean ADC of cirrhotic liver was 1.96 × 10⁻³± 0.62, which was lower than that of normal liver. Other pathologic conditions also showed ADCs different from those of normal tissues. All DW images showed significantly higher spleen-to-liver SIRs and SIDs than did T2-weighted images (p < 0.05). Conclusion: The mean ADCs obtained with DW imaging were different in each upper abdominal organ and with each pathologic condition. DW images showed better soft tissue contrast than did T2-weighted images with regard to SIR and CNR in depicting and characterizing upper abdominal disorders. Received: 24 July 1998/Revision accepted: 2 December 1998     

MR imaging enhancement with superparamagnetic iron oxidein chronic liver disease: influence of liver dysfunction andparenchymal pathology

Purpose: To analyze the influence of liver dysfunction and parenchymal pathology on the accumulation of superparamagnetic iron oxide (SPIO). Methods: We evaluated MR images of 13 patients having small hepatic neoplasms before and after administration of SPIO (10 μmol/kg). Biopsy and laboratory data confirmed the presence of severe cirrhosis in two patients, mild cirrhosis in four, chronic hepatitis in five, and normal livers in two. Degrees of liver dysfunction or liver parenchymal pathology were correlated with reductions in signal intensity of the liver and spleen after administration of SPIO. Signal intensity reduction was evaluated using a 1.5 Tesla MR unit. Results: Response to SPIO of the liver and spleen did not correlate with liver parenchymal pathology, although reductions in signal intensity of the liver were somewhat small in severely cirrhotic livers. There were slight correlations between signal intensity alterations of the liver and laboratory data such as the indocyanine green retention rate (correlation coefficient 0.47), albumin (0.36), total bilirubin (0.36), and serum glutamic oxaloacetic transaminase (GOT) (0.46). Signal intensity reduction of spleen did not correlate with liver function tests except for serum GOT. In patients with cirrhosis, heterogeneous structures were detected in the nontumorous portions of the liver. However, these did not prevent the diagnosis of small hepatomas. Conclusion: The uptake of SPIO showed some correlation with liver function but not with chronic liver parenchymal pathology. SPIO provided sufficient contrast between tumor and surrounding liver parenchyma among patients with chronic liver disease. Received: 22 August 1994/Accepted after revision: 27 January 1995     

Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions

Background: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. Methods: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor–liver signal intensity (T/L) ratios. Results: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion–liver C/N (CSE TE, 90 ms: 18.6 ± 14.0; TSE TE, 90 ms: 16.5 ± 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. Conclusions: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE. Received: 13 December 1994/Accepted after revision: 31 March 1995     

Late-phase enhancement of the upstream portion of pancreatic adenocarcinoma on dual-phase helical CT

Background: Late-phase enhancement of pancreatic parenchyma upstream (tail side) of pancreatic adenocarcinoma is found frequently on dual-phase helical computed tomography (CT). We measured the frequency of late-phase enhancement of the upstream portion of pancreatic adenocarcinoma and normal pancreatic parenchyma using dual-phase helical CT. Methods: Twenty-one patients with pancreatic adenocarcinoma and nontumorous pancreas upstream of tumors were compared with 100 control patients without pancreatic disease. Early and late scans started at 25 and 75 s, respectively, after intravenous injection of contrast material. The attenuation values of normal and nontumorous pancreas upstream of tumors were assessed in three phases: precontrast, early, and late enhanced. Enhancement ratio (ER) was calculated as ER = (late phase − precontrast)/(early phase − precontrast). Results: Late-phase enhancements (ER > 1.0) were seen in 86% of upstream pancreas and 10% of normal pancreas. The mean ER of upstream pancreas was significantly higher than that of normal pancreas (p < 0.01). Conclusion: Late-phase enhancement of the pancreas upstream of the tumor is frequently observed in patients with pancreatic adenocarcinoma. Late-phase enhancement and histology showed a correlation for chronic obstructing pancreatitis in five patients. Received: 30 October 2000/Revision accepted: 7 February 2001     

Spiral CT for the detection of hepatocellular carcinomas: relative value of arterial- and late-phase scanning

Background: Spiral computed tomography (CT) can image the liver during arterial and late phases of contrast and optimize the evaluation of hypervascular tumor. The objective of this study was to evaluate the relative value of arterial- and late-phase spiral CT in the detection of hepatocellular carcinomas. Methods: Fifty-eight patients with hepatocellular carcinomas underwent two-phase spiral CT examination with 10-mm collimation at 10 mm/s table speed (Siemens Somatom Plus S), and 120 mL of contrast material (36 g iodine) was injected at the rate of 3 mL/s. CT images of hepatic arterial and late phases were obtained with a 35-s and 180-s delay, respectively. Results: In 58 patients, 111 hepatocellular carcinoma lesions were seen. The arterial phase detected 93 (84%) and the late phase 75 (68%) lesions (p < 0.01). The arterial phase detected more lesions in 11 patients, and the late phase dected more in two patients and an equal number in 45 patients. If lesions larger than 2 cm are excluded, the arterial phase detected 40 (74%) and the late phase 21 (39%) of 54 lesions (p < 0.001). Conclusion: The arterial phase of spiral CT greatly improves the detection of hepatocellular carcinoma when compared with the late phase. Received: 13 April 1995/Accepted: 22 May 1995     

Transcatheter arterial embolization in the treatment of symptomatic cavernous hemangiomas of the liver: a prospective study

Background: This prospective study evaluated the clinical and radiologic results of transcatheter arterial embolization (TAE) for the treatment of symptomatic cavernous hemangiomas of the liver. The technique, its complications, and effectiveness also were analyzed. Methods: Eight patients (five male, three female; mean age ± SD = 47.75 ± 8.59 years) with symptomatic cavernous hemangiomas of the liver were treated by TAE with polyvinyl alcohol particles or gelfoam and steel coils (single session) followed by supportive treatment. Tumor characterization (including the extent and number of lesions) was done on triple-phase helical computed tomography or gadolinium-enhanced dynamic magnetic resonance imaging. Results: The lesions were located in the right lobe in five patients, left lobe in one, and both lobes in two. The largest diameter of the lesions was 6–18 cm (9.28 ± 5.13 cm). The treatment response was assessed on follow-up ultrasound and color Doppler and/or contrast-enhanced helical computed tomography. There were no treatment-related deaths and morbidity was minimal. Embolization was the only method of treatment in seven patients; however, one patient had surgery after TAE because the symptoms were only partly relieved. Indications for embolization were abdominal pain (eight patients), rapid tumor enlargement (four of eight), and recurrent jaundice (one of eight). Symptomatic improvement was documented in all patients after embolization. Symptoms did not worsen in any patient. The mean size of the tumor did not show any statistically significant change on follow-up radiologic examinations. However, in one patient, the tumor significantly regressed in size after embolization. Conclusion: TAE of hepatic cavernous hemangioma is a useful procedure in the therapy of symptomatic hemangiomas. Received: 13 July 2000/Revision accepted: 27 December 2000     

Cirrhosis: spectrum of findings on unenhanced and dynamic gadolinium-enhanced MR imaging

The appearance of the cirrhotic liver on computed tomography can be difficult to evaluate and can frustrate the radiologist distinguishing benign from malignant lesions. Hepatic edema, fibrosis, atrophy, and vascular abnormalities are common in the cirrhotic liver and produce derangements in morphology, attenuation, and perfusion, limiting the accurate characterization of hepatic masses. With the development of fast magnetic resonance (MR) sequences and dynamic postgadolinium-enhanced imaging, most hepatic lesions with uncertain etiology on computed tomography can be accurately characterized on MR imaging. We describe MR imaging techniques useful for imaging cirrhosis and its complications. We also illustrate the spectrum of findings in the cirrhotic liver on dynamic gadolinium-enhanced MR imaging, including reticular and confluent fibrosis, fatty infiltration, hemochromatosis, regenerating nodules, dysplastic nodules, hepatocellular carcinoma, and sequela of portal hypertension. Received: 16 November 2000/Revision accepted: 7 February 2001     

Focal nodular hyperplasia of the liver: detection and characterization with plain and dynamic-enhanced MRI

Background: We compared nonenhanced and dynamic gadolinium (Gd)–enhanced magnetic resonance imaging (MRI) appearances of hepatic focal nodular hyperplasia (FNH) as depicted with breath-hold MR sequences and assessed the detectability of the individual MR sequences used. Methods: We retrospectively reviewed 48 consecutive patients with FNH. All patients underwent nonenhanced (T1 fast low-angle shot [FLASH] and T2 half-Fourier acquisition [HASTE]) and dynamic Gd-enhanced (T1 FLASH) MRI between December 1997 and March 2000. Individual MR sequences were analyzed separately for number of lesions, signal intensity features, dynamic enhancement pattern, and the presence and enhancement profile of a central scar. Ninety-five percent confidence intervals of absolute discrepancy were calculated to define differences in lesion detection. Results: Seventy-seven lesions were found in 48 patients. Nonenhanced FLASH imaging depicted 59 (76.6%) lesions in 45 patients. HASTE images showed 55 (71.4%) lesions in 44 patients. On T1- and T2-weighted images, lesions appeared predominantly hypointense (69.5%) and hyperintense (72.7%), respectively. Arterial and portal venous dominant phase Gd-enhanced MRI demonstrated all 77 lesions (100%), most of which showed hypervascular (94.8%), homogeneous (97.4%), and incomplete (except the central scar: 58.4%) enhancement in the arterial phase. Portal venous phase images showed lesion isointensity (50.6%) or moderate hyperintensity (46.8%) with complete enhancement (central scar: 94.8%). A central scar was detected on nonenhanced T1-weighted images (hypointense: 100%), T2-weighted images (hyperintense: 100%), arterial phase (hypointense: 59.7%) and portal venous phase (hyperintense: 71.4%) Gd-enhanced images in 78%, 69.1%, 77.9%, and 75.3% of tumors, respectively. Conclusion: Arterial and portal venous phase Gd-enhanced T1-weighted sequences are superior to nonenhanced images in the detection of FNH. Typical MRI appearances include hypointensity on T1-weighted and hyperintensity on nonenhanced T2-weighted images. Most commonly, FNH shows a homogeneous (without scar) and strong enhancement during the arterial phase, with lesion isointensity or slight hyperintensity during the portal venous phase. Received: 15 May 2001/Revision accepted: 22 August 2001     

Icteric-type hepatoma: magnetic resonance imaging and magnetic resonance cholangiographic features

Background: We evaluated the imaging features of magnetic resonance imaging (MRI) and magnetic resonance cholangiography (MRC) of icteric-type hepatoma and correlated these with the findings of endoscopic retrograde cholangiography (ERC), percutaneous cholangiography, and surgery. Methods: Thirteen patients with viral hepatitis complicated by cirrhosis of the liver and obstructive jaundice underwent MRC and dynamic MRI. Five patients received percutaneous transhepatic cholangiography and drainage; one of these patients also underwent resection of the left hepatic lobe. Another patient received MRC followed by thrombectomy and T-tube insertion. ERC and endoscopic nasobiliary drainage were performed in another patient for bile diversion. Results: Primary liver tumors and dilatation of biliary system were demonstrated in all patients. No capsule formation could be found in any primary liver tumors. MRI showed the simultaneous presence of an intraluminal tumor in the portal trunk and common hepatic duct in eight patients. Three different MRC features were found: (a) an oval defect in the hilar bile duct(s) with dilated intrahepatic ducts (n= 9), (b) dilated intrahepatic ducts with missing major bile ducts (n= 2), and (c) localized stricture of the hilar bile duct(s) (n= 2). Conclusion: The presence of one or more of the following features in multiplanar MRI and MRC help to identify this rare, specific type of hepatocellular carcinoma: (a) the presence of an intraluminal tumor in both the portal trunk and the common hepatic duct, (b) enhancement of the intraluminal tumor in the common hepatic duct on the arterial phase, (c) type I MRC feature, and (d) hemobilia, blood clot within the gallbladder, and/or type II MRC feature. Received: 12 January 2000/Revision accepted: 12 July 2000     

Hepatic pseudolymphoma: imaging–pathologic correlation with special reference to hemodynamic analysis

Objectives

To clarify radiological findings and hemodynamic characteristics of hepatic pseudolymphoma, as compared with the histopathological findings.

Methods

Radiological findings of ten histopathologically confirmed hepatic pseudolymphomas in seven patients were examined using US, CT, and MRI. Six patients also underwent angiography-assisted CT, including CT during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) to analyze hemodynamics.

Results

The nodules were depicted as hypoechoic on US, hypodense on precontrast CT, hypointense on T1-weighted images, and hyperintense on T2-weighted images. On contrast-enhanced CT/MRI, they showed various degrees of enhancement, and sometimes, perinodular enhancement was observed at the arterial dominant and/or equilibrium phase. On CTAP, the nodules showed portal perfusion defects, including some in the perinodular liver parenchyma. On CTHA, irregular bordered enhancement was observed in perinodular liver parenchyma on early phase, and continued until delayed phase. Some nodules had preserved intra-tumoral portal tracts. Histopathologically, the nodules consisted of marked lymphoid cells. In perinodular liver parenchyma, stenosis or disappearance of portal venules, caused by lymphoid cell infiltration in the portal tracts, was observed.

Conclusions

Hepatic pseudolymphoma showed some characteristic radiological findings including hemodynamics on CT, MRI, and angiography-assisted CT. These findings are useful in the differentiation from hepatocellular carcinoma and other tumors.     

Detection of pancreatic adenocarcinoma: relative value of arterial and late phases of spiral CT

Background: Spiral computed tomography (CT) allows the pancreas to be imaged during peak contrast levels owing to the capability of fast data acquisition. The objective of this study was to evaluate the relative value of the arterial and late phases of spiral CT for detecting pancreatic adenocarcinomas. Methods: Twenty-two patients with pathologically proved pancreatic adenocarcinomas underwent two-phase spiral CT. The CT scans were performed with 5 mm collimation and 5 mm/s table speed. Images during the arterial and late phases were obtained at 30- and 180-second delays, respectively. The images of the arterial phase were compared with those of the late phase in terms of tumor conspicuity from surrounding pancreatic parenchyma and tumor detectability by means of a 3-point grading system: 1 (poor), 2 (fair), and 3 (good). Results: In terms of tumor conspicuity from surrounding pancreatic parenchyma, 16 lesions (73%) were good, 5 lesions (23%) were fair, and 1 lesion (4%) was poor during the arterial phase, whereas 6 lesions (27%) were good, 9 lesions (41%) were fair, and 7 lesions (32%) were poor during the late phase (p= 0.0007). The arterial phase was superior to the late phase in 16 patients (73%) and equal in 6 patients (27%). For tumor detectability, 18 lesions (82%) were good, 3 lesions (14%) were fair, and 1 lesion (4%) was poor during the arterial phase, whereas 10 lesions (45%) were good, 7 lesions (32%) were fair, and 5 lesions (23%) were poor during the late phase (p= 0.0033). For detectability, the arterial phase was superior to the late phase in 14 patients (64%) and equal in 8 patients (36%). Conclusion: The arterial phase of spiral CT is superior to the late phase, which is equivalent to conventional CT for detecting pancreatic adenocarcinoma. Received: 1 August 1995/Accepted: 12 September 1995     

AN EXPERIMENTAL STUDY INTO THE CAUSE OF THE INCREASED PORTAL PRESSURE IN PORTAL CIRRHOSIS

1. In the liver of portal cirrhosis there is a far freer communication between the arterial and portal currents than in the normal liver. 2. Factors contributing to the increased portal pressure in portal cirrhosis are (1) the direct communication of the arterial pressure to the portal vessels through dilated capillaries, (2) the larger volume-flow of the hepatic artery in proportion to the portal flow in cirrhosis as compared to that in the normal liver. 3. A portal cirrhotic liver gives passage to an amount of portal fluid proportionate to .its weight. There is no obstruction to the portal vessels from fibrosis in the large portal cirrhotic liver. 4. From an arterial inflow there is a free return flow through the portal as well as through the hepatic veins in both normal and cirrhotic livers. 5. From a portal inflow the return is through the hepatic vein only. The Gad''s theory of valves and the arterial capillary network account for this fact. 6. The portal pressure has a decided influence on the arterial volume-flow and vice versa. This influence is more marked in the cirrhotic than in the normal liver. 7. The communication of the arterial pressure to the portal pressure is an important factor in an explanation of the increased portal pressure in portal cirrhosis.     

Multiphase helical CT findings after percutaneous ablation procedures for hepatocellular carcinoma

Background: Multiple-phase helical computed tomography (CT) has been regarded as the method of choice in the evaluation of patients with hepatocellular carcinoma (HCC) treated by nonsurgical procedures. The aim of this article was to report our experience in the assessment of nodular and parenchymal changes recognizable after various percutaneous ablation therapies. Methods: We reviewed the studies of 116 consecutive patients with HCC treated with multisession percutaneous ethanol injection (56 patients, 98 nodules), single-session percutaneous ethanol injection (14 patients, 31 nodules), radiofrequency thermal ablation (32 patients, 48 nodules), and interstitial laser photocoagulation (14 patients, 25 nodules). CT had been performed 3–28 days after the last session (mean = 18 days) with unenhanced helical acquisition and with contrast-enhanced double- or triple-phase helical acquisition. Results: Persisting neoplastic tissue was identified within 54.5% of the nodules. It was located centrally in 4.5% of these nodules, peripherally in 11%, and eccentrically in 84.5%, and its shape was crescent in 58%, globular in 24.5%, and other in 16%. On arterial phase scans, viable tumor was hyperdense in 97% of the lesions and isodense in 3%; on portal phase scans, the tumor was hyperdense in 20%, isodense in 28%, and hypodense in 52%; on delayed phase scans, the tumor was consistently hypodense. Tumor necrosis was always hypodense on contrast-enhanced scans. On unenhanced images, 7.4% of the nodules were undetectable. Nodule diameter appeared as unchanged in 53% of the nodules and as larger in 47%; its shape was unchanged in 54% and modified in 46%; its margins were unchanged in 36% and modified in 64%. A rim of granulation tissue was detected around 15% of the nodules, and a perilesional transient attenuation difference was detected in 21%. Perihepatic effusion was seen in 13% of the patients, segmental biliary duct dilation and local atrophy each in 9%, arterioportal fistula in 6%, portal vein thrombosis, subcapsular collection and pleural effusion each in 7%, hepatic infarction in 5%, and inferior vena cava thrombosis in 2%. Conclusion: Percutaneous ablation of HCC may cause several changes. Knowledge of their CT appearance is mandatory to correctly assess and manage this tumor. RID=" ID=" <E5>Correspondence to:</E5> O. Catalano Received: 6 April 2000/Accepted: 3 May 2000     

Acute hepatic vein occlusion: spiral CT findings in an experimental study

Background: We investigatedspiral computed tomographic (CT) findings and underlying hemodynamic alterations in acute hepatic vein occlusion. Methods: In nine dogs, immediately after balloon occlusion of the right (n = 4) or left (n = 5) hepatic vein through the transjugular or transfemoral route, we performed single-level dynamic CT with intravenous administration of contrast medium. We created time attenuation curves of individual hepatic segments showing attenuation differences. To investigate underlying hemodynamic alterations, hepatic arteriograms were obtained in two dogs. Results: In all cases, there were three compartments with different time attenuation curves: normal, occluded, and adjacent. The normal compartment, which comprised segments far from the occluded hepatic compartment, showed the normal pattern of hepatic enhancement. The occluded compartment, which was the drainage territory of the occluded hepatic vein, showed high attenuation in the early arterial phase and low attenuation in the portal phase. The adjacent compartment, which shared the same portal vein with the occluded compartment and was drained by the patent hepatic vein adjacent to the occluded one, showed strong contrast enhancement in the late arterial and early portal phase. Spiral CT and hepatic arteriography demonstrated the arterioportal shunt and reversed portal venous flow in the occluded compartment, which drained into the adjacent compartment. Conclusion: Acute hepatic vein occlusion on spiral CT appears as mild, early arterial, high attenuation and portal low attenuation of the occluded compartment and strong enhancement in the late arterial and early portal phases of the adjacent compartment due to arterioportal shunt and reversed portal flow. Received: 15 March 2001/Revision accepted: 4 July 2001     

双层探测器光谱CT虚拟平扫应用于肝脏三期增强扫描

目的 探讨双层探测器光谱CT（SDCT）对肝脏行三期增强扫描的虚拟平扫（VNC）图像代替真实平扫（TNC）的可行性。方法 回顾性分析36例肝脏疾病患者SDCT三期增强扫描的影像学资料。经后处理获得动脉期VNC图像（VNC_a）、门静脉期VNC图像（VNC_p）及平衡期VNC图像（VNC_e）。联合单能量成像，采用TNC与VNC成像技术分别测量肝脏及竖脊肌的CT值与噪声值（SD），计算信噪比（SNR）和对比噪声比（CNR），计算受检者接受的有效剂量（ED），比较2者的图像质量及诊断效能。结果 VNC的SD值比TNC低（P<0.05），SNR值比TNC高（P<0.05）。肝实质VNC与TNC图像CT值一致性良好（平均差值<2 HU），病灶均显示清晰，肝脏VNC_a图像质量最佳（P<0.05）。采用"VNC+直接增强"方案可降低约24.65%的辐射剂量。结论 采用SDCT三期VNC图像均可满足诊断肝脏疾病需要，较TNC噪声更低、SNR值更高，并可良好显示病灶。