Intrahepatic portal venous variations: demonstration by helical CT during arterial portography

PURPOSE: We assessed the prevalence and types of intrahepatic portal venous variations by helical computed tomography performed with arterial portography (CTAP). METHODS: In 192 patients without evidence of vascular invasion or distortion, CTAP images were reviewed retrospectively to identify portal venous variations. RESULTS: Of the 192 patients examined, 10 (5.2%) had trifurcation, 5 (2.6%) had a right posterior segmental branch arising from the main portal vein, 5 (2.6%) had an absence of the horizontal segment of the left portal vein, and 1 (0.5%) had an absence of the left lateral segmental portal branch. Of the patients without a horizontal segment, two had a right-sided ligamentum teres associated with malposition of the gallbladder, while another had complete ramification of intrahepatic portal branches from an umbilical vein-like segment. In the patient missing the left lateral segmental branches, the right portal vein segments were subcapsularly located. CONCLUSION: Variations of the intrahepatic portal veins can be recognized on CTAP imaging. tomography-Portal vein, computed tomography.     

The prevalence and variations of inferior right hepatic veins on contrast-enhanced helical CT scanning

PURPOSE: To present the prevalence and variations of inferior right hepatic veins (IRHVs) on contrast-enhanced helical computed tomography (CEHCT) scans. MATERIALS AND METHODS: The routine abdominal CEHCT scans of 349 patients were reviewed. Three hundred and eight patients (88.2%) were included in the study. Of the 349 patients, 41 (11.8%) were excluded from the study because of improper opacification of hepatic veins and right hepatic lobe lesions which made difficult the optimal visualization and assessment of IRHVs. The mean age of 308 patients was 43 years (range 3-97 years). One hundred and forty-three patients (46.4%) were men and 165 (53.6%) women. Scans were examined whether the IRHVs were demonstrated or not and classified according to their numbers, levels, diameters, and joinings to inferior vena cava (IVC). RESULTS: Of the 308 patients, 65 (21.1%) had one or two IRHVs. Fifty-four patients (83.1%) had only one IRHV and 11 (16.9%) patients had two. More than two IRHVs were not seen in any patient. Eight (72.7%) of 11 double IRHVs joined the IVC at the same level and others (27.3%) did not. There was no truncal opening to the IVC. In five patients (7.7%) the IRHV were large (> or =0.5 cm). CONCLUSION: The presence of IRHVs is common and routine CEHCT scanning is efficacious in assessment of IRHVs.     

Portal venous system: evaluation with contrast-enhanced 3D MR portography

The purpose of this study is to compare contrast-enhanced three-dimensional (3D) magnetic resonance (MR) portograms to Doppler sonography in detection of portal venous abnormalities. Thirty-five consecutive patients, who were suspected of having portal venous system abnormalities, were examined with MR portography and Doppler sonography. Vascular abnormalities were identified in 27 of 35 patients. There was statistically significant agreement between the results of MR portography and Doppler sonography. The major limitation of contrast-enhanced 3D MR portography was its inability to provide objective hemodynamic data regarding flow direction and flow pattern.     

超声造影与增强CT在胆囊疾病诊断中的对比分析

目的:比较超声造影(contrast-enhanced ultrasound,CEUS)和CT增强(contrast-enhanced helicalcomputedtomography,CECT)检查在胆囊占位性病变诊断中血流灌注过程中的的特点,探讨其在胆囊占位性病变诊断中的价值。方法:对比分析78例胆囊占位性病变的超声造影和增强CT在不同时相的增强及灌注特征。结果:超声造影和增强CT具有相似的表现。但对于小于5 mm的病变,超声造影的检出率高于增强CT,78例胆囊占位性病变中,胆囊癌35例,胆囊息肉29例,局限性胆囊腺肌增生症14例,增强CT准确率分别为84.35%,89.63%和80.13%,超声造影准确率分别为83.12%,93.79%和79.72%。结论:增强CT和超声造影检查均有助于胆囊疾病诊断,两者结合可提高胆囊疾病的诊断符合率。     

Nonfatal venous air embolism after contrast-enhanced CT

Contrast material-enhanced computed tomography (CT) was performed in 100 patients. Fifty milliliters of contrast material was intravenously injected by hand and followed by a drip infusion of 100 mL of contrast material. Venous air embolism occurred in 23% of the patients. The amount of embolism was minimal in 20 patients and moderate in three. Although large amounts of embolism have been reported to be associated with considerable morbidity and mortality, none of the patients in this study had immediate or delayed complications as a result of the small degree of embolism. The locations of the emboli were in the subclavian or axillary vein in nine, right or left brachiocephalic vein in three, internal jugular vein in two, superior vena cava in two, right ventricle in two, and main pulmonary artery in 12 patients. In patients at high risk for cerebral air embolism, such as those with intracardiac shunts or pulmonary arteriovenous malformations, extreme caution should be used--even in the routine administration of intravenous fluids or contrast media--to prevent venous air embolism and resultant neurologic deficits.     

Pericaval fat mimicking intracaval deposits on unenhanced and contrast-enhanced helical CT in patients with cirrhosis.

PURPOSE: The purpose of this work was to determine whether there is a significant difference in radiographic depiction of pericaval fat mimicking intracaval deposits on CT scans in patients with cirrhosis versus those without cirrhosis. METHOD: The incidence of radiographic pseudolesions depicted as an intracaval fat mass identified on CT scans in 62 patients with cirrhosis was compared with that in 81 patients without cirrhosis. RESULTS: Pericaval fat depicted as an intracaval fat mass was identified more frequently in patients with cirrhosis (20/62, 32%) than in patients without cirrhosis (4/81, 5%), representing a statistically significant difference (p < 0.0001). A total of 24 lesions were seen in 20 patients with cirrhosis. Lesions were identified at the confluence of the hepatic veins (n = 19), below the confluence (n = 4), and above the confluence (n = 1). Pseudolesions appeared round (n = 5), oval (n = 15), or linear (n = 4). Locations included medial (n = 15), posteromedial (n = 4), anteromedial (n = 1), and posterior (n = 4). The average length was 1.5 cm. CONCLUSION: The cause of pseudolesions depicted as intracaval fat masses on CT is likely secondary to morphologic changes in the liver such as cirrhosis.     

Fungal liver infection in immunocompromised patients: depiction with multiphasic contrast-enhanced helical CT

PURPOSE: To retrospectively assess multiphasic (nonenhanced, arterial phase, and portal venous phase) computed tomography (CT) of the liver for depiction of hepatic fungal infection in immunocompromised patients. MATERIALS AND METHODS: The institutional ethics review board approved the study and waived the requirement for informed consent. Sixty multiphasic hepatic CT examinations were performed in 39 immunocompromised patients who fulfilled the criteria for having probable or proved fungal liver infection. The detection and conspicuity of focal liver lesions were assessed on scans obtained during each CT phase. The lesion enhancement pattern was determined, and, accordingly, lesions were stratified into two groups: lesions suggestive of infection (with ring enhancement patterns or high attenuation) and nonspecific hypoattenuating lesions. Statistical analyses were performed by using logistic regression with generalized estimating equations. RESULTS: A total of 536 liver lesions detected at 36 CT examinations with results positive for fungal infection were assessed. All 36 (100%) examinations yielded positive results during the arterial phase, whereas 25 (69%) of them yielded positive results during the portal venous phase (P < .001). At lesion-by-lesion analysis, the arterial phase scans depicted significantly more lesions (483 of 536 [90%]) than the portal venous phase (329 of 536 [61%]) and nonenhanced (265 of 465 [57%]) scans (P < .001 for both comparisons). In addition, on arterial phase scans, 386 of 483 lesions, as compared with 134 of 329 lesions on portal venous phase scans (P < .001), were judged to have an enhancement pattern suggestive of infection. The CT phases did not differ significantly in terms of the conspicuity of detected lesions. CONCLUSION: In patients suspected of having hepatic fungal infection, arterial phase CT depicts significantly more hepatic lesions than does CT performed during the other phases, and it reveals more lesions with enhancement patterns suggestive of infection. Arterial phase CT should be performed in addition to portal venous phase CT in patients suspected of having hepatic fungal infection.     

Peripancreatic vascular abnormalities complicating acute pancreatitis: contrast-enhanced helical CT findings

OBJECTIVE: To determine the prevalence and morphologic helical computed tomography (CT) features of peripancreatic vascular abnormalities in patients with acute pancreatic inflammatory disease in correlation with the severity of the pancreatitis. MATERIALS AND METHODS: One hundred and fifty-nine contrast-enhanced helical CT scans of 100 consecutive patients with acute pancreatitis were retrospectively and independently reviewed by three observers. CT scans were scored using the CT severity index (CTSI): pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the CT severity index and the presence of peripancreatic vascular abnormalities was calculated (K-statistic). Correlation between the prevalence of complications and the degree of pancreatitis was estimated using Fisher's exact test. RESULTS: The severity of pancreatitis was graded as mild (n = 59 scans), moderate (n = 82 scans), and severe (n = 18 scans). Venous abnormalities detected included splenic vein (SV) thrombosis (31 scans, 19 patients), superior mesenteric vein (SMV) thrombosis (20 scans, 14 patients), and portal vein (PV) thrombosis (17 scans, 13 patients). Arterial hemorrhage occurred in five patients (6 scans). In our series, no cases of arterial pseudoaneurysm formation were detected. The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of major vascular abnormalities was 75.5-79.2 and 86.2-98.8%, respectively. The presence of the vascular abnormalities in correlation with the severity of pancreatitis was variable. CONCLUSION: Vascular abnormalities are relatively common CT findings in association with acute pancreatitis. The CT severity index is insufficiently accurate in predicting some of these complications since no statistically significant correlation between their prevalence and the severity of pancreatitis could be established.     

Multiphase contrast-enhanced helical CT of liver metastases from renal cell carcinoma

The aim of this study was to evaluate whether in patients with metastatic renal cell carcinoma (RCC) multiphase liver studies would improve detection of metastatic liver disease. Forty-six consecutive patients with known metastatic RCC underwent standardized non-contrast and triphasic contrast enhanced hepatic CT examinations as part of their routine imaging studies. Once a liver abnormality was detected, it was characterized as metastatic by a panel of three radiologists who followed pre-set criteria. These criteria included change in size, biopsy results and lack of benign features. Presence and conspicuity of liver metastases were graded using a five-point scale by consensus of a panel of three radiologists. The highest number of lesions evaluated per patient was limited to ten. Seventy-two liver metastases were detected in 16 patients. Of these, 54 were seen on unenhanced scans; 47 in the hepatic arterial (HA) phase, at 25 s; 65 in the portal-venous (PV) phase, at 60 s; and 49 in delayed images, at 90 s. Scanning only during the PV phase would have missed seven lesions (10%), six of which were seen on unenhanced images and six were seen in HA phase. All patients with metastatic liver disease would have been identified by combination of unenhanced and PV phase or by HA and PV phase scanning. Forty-two lesions were graded more conspicuous on the PV phase, whereas 18 (25%) were more conspicuous on the HA phase. The combination of unenhanced, HA and PV scanning should be considered in the initial evaluation of patients with metastatic RCC for improved lesion detection and characterization. Subsequently, the combination of unenhanced and PV phase imaging is preferred.     

Portal vein occlusion or stenosis in patients with hepatolithiasis: observation by multiphasic contrast-enhanced CT

AIMS: To analyze the dynamic findings of multiphasic contrast-enhanced CT in hepatolithiasis and to elucidate occlusive changes in portal veins and other associated abnormalities. METHODS: This was a retrospective study of 25 selected patients with hepatolithiasis who underwent various imaging examinations, including multiphasic contrast-enhanced CT. The following CT findings were evaluated in each of 71 hepatic segments: visualization of a calculus; biliary dilation or focal hepatic atrophy of the affected segment; areas that were abnormally enhanced in the hepatic arterial phase; degrees (normal, stenosis, occlusion) of portal vein calibre; and linear delayed enhancement along the bile-duct walls, suggesting cholangitis. RESULTS: On CT, calculi were depicted as a hyperdense structures in 61 of 71 segments (86%). Focal hepatic atrophy, which frequently accompanied CT findings suggesting compensatory hypertrophy of other segments, was seen in 50 of 71 segments (70%). Areas that were abnormally enhanced were recognized in 36 of 71 segments (51%). Stenosis or occlusion of portal venous branches was observed in 59 of 71 segments (83%), including 13 segments with occlusion. Findings indicating cholangitis were noted in 50 of 71 segments (70%). The degrees of portal vein calibre were significantly correlated with the presence of hepatic atrophy or cholangitis. CONCLUSION: Hepatolithiasis is associated with significant rates of stenosis or occlusion of adjacent portal veins as well as hepatic parenchymal changes in the affected area. Chronic deterioration of portal flow may cause these morphological changes.     

The most useful findings for diagnosing acute appendicitis on contrast-enhanced helical CT

PURPOSE: To evaluate the most useful findings to look for in diagnosing acute appendicitis on contrast-enhanced helical CT. MATERIAL AND METHODS: Appendiceal helical CT scans with intravenous contrast administration (abdomen, 7-mm collimation; abdominopelvic junction, 5-mm collimation) of 71 patients with surgically proven acute appendicitis and 167 patients with alternative diagnoses were reviewed retrospectively. Three radiologists analyzed the following parameters: enlarged appendix (>6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), appendiceal intraluminal air, intramural air, extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, segmental terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. The features that best distinguished appendicitis from alternative diagnoses were selected with stepwise logistic regression analysis. RESULTS: Nine CT findings distinguished acute appendicitis from alternative diagnoses (P < 0.05): enlarged appendix (R = 0.739), appendiceal wall thickening (R = 0.525), periappendiceal fat stranding (R = 0.414), appendiceal wall enhancement (R = 0.404), focal cecal apical thickening (R = 0.171), appendicolith(s) (R = 0.157), extraluminal air (R = 0.050), intramural air (R = 0.043), and phlegmon (R = 0.030). Enlarged appendix (sensitivity, 93%; specificity, 92%), appendiceal wall thickening (sensitivity, 66%; specificity, 96%), periappendiceal fat stranding (sensitivity, 87%; specificity, 74%), and appendiceal wall enhancement (sensitivity, 75%; specificity, 85%) showed the statistically most significant association with acute appendicitis. CONCLUSION: On 5-mm-section contrast-enhanced helical CT examinations, enlarged appendix, appendiceal wall thickening, periappendiceal fat stranding, and appendiceal wall enhancement were the most useful findings for diagnosing acute appendicitis.     

Hepatocellular carcinoma treated with radiofrequency ablation: comparison of pulse inversion contrast-enhanced harmonic sonography, contrast-enhanced power Doppler sonography, and helical CT.

OBJECTIVE: The purpose of this study was to compare the efficacy of contrast-enhanced pulse inversion harmonic imaging with contrast-enhanced power Doppler sonography and helical CT to determine incomplete local treatment after radiofrequency ablation in patients with hepatocellular carcinoma. MATERIALS AND METHODS: Thirty-five consecutive patients (24 men and 11 women; mean age, 64 years) with 43 hepatocellular carcinomas (3.6 +/- 1.1 cm) were treated using internally cooled radiofrequency ablation therapy. Therapeutic response was evaluated at 4 months with dual-phase contrast-enhanced helical CT, conventional power Doppler Sonography, and pulse inversion harmonic imaging using a sonographic contrast agent (SH-508). CT and sonographic studies were reviewed separately in random order by four radiologists at different consensus conferences. Sensitivity and specificity of the sonographic methods were determined using CT as a gold standard and results were compared using the McNemar test. RESULTS: CT examinations identified residual tumor in 12 lesions (27.9%). Although conventional contrast-enhanced power Doppler sonography identified residual viable tumor foci in four incompletely treated lesions (9.3%), contrast-enhanced pulse inversion harmonic imaging identified residual tumoral enhancement in 10 lesions (23.3%). Thus, the sensitivity of pulse inversion harmonic imaging (83.3%) was significantly greater (p < 0.05) for detecting residual nonablated tumor compared with conventional contrast-enhanced power Doppler sonography. CONCLUSION: Our study suggests that contrast-enhanced pulse inversion harmonic imaging may enable the detection of residual nonablated tumor in more cases than contrast-enhanced power Doppler sonography and may ultimately prove to be a useful adjunct for percutaneous ablation therapies. Nevertheless, contrast-enhanced axial imaging (CT or MR imaging) is currently the most sensitive test for managing thermal ablation for patients with hepatocellular carcinoma.     

Metastases to the pancreas from renal cell carcinoma: findings on three-phase contrast-enhanced helical CT.

OBJECTIVE: Our goal was to define the lesion enhancement characteristics of renal cell carcinoma metastases to the pancreas using three-phase helical CT. MATERIALS AND METHODS: Thin-section three-phase contrast-enhanced CT scans of nine patients with renal cell carcinoma metastases to the pancreas were evaluated. The helical CT protocol included 3-mm collimation and a 2:1 pitch. Scans through the pancreas were obtained in three series beginning 25, 60, and 120 sec after the start of administration of i.v. contrast material delivered at 3 ml/sec. The Hounsfield densities of the pancreatic lesions and normal pancreatic parenchyma during each of the enhancement phases were recorded and compared. RESULTS: The enhancement patterns of the metastatic deposits and the normal pancreas differed. Thirty-four lesions ranging in size from 6 to 110 mm were identified. All metastases showed rapid enhancement during the early (arterial and portal) phases, resulting in differential attenuations (compared with normal pancreatic parenchyma) of approximately 50-100 H. The differential attenuations were approximately 5-45 H on delayed-phase scans, resulting in poorer conspicuity of the lesions. Multifocal metastases were clearly identified on the early-phase scans in seven patients. CONCLUSION: Renal cell carcinoma metastases to the pancreas enhance most conspicuously during the early phases of helical CT. Such metastases may fail to be appreciated in the delayed phase. In patients with suspected renal cell carcinoma metastases to the pancreas, early-phase scanning after i.v. contrast administration should be performed.     

Measuring portal venous perfusion with contrast-enhanced CT: comparison of direct and indirect methods

RATIONALE AND OBJECTIVES: Two algorithms can be used to measure portal venous perfusion (PVP) with contrast material-enhanced single-level liver computed tomography. The "direct" and "indirect" algorithms use data from the portal vein and aorta, respectively. This study compared PVP values obtained with direct and with indirect algorithms in a series of patients. MATERIALS AND METHODS: Both techniques were applied in 27 patients with cirrhosis (14 men and 13 women; mean age, 56.1 years +/- 9.4) and 18 control patients (seven men and 11 women; 52.8 years +/- 12.3). A single section through the liver was scanned after intravenous injection of ioversol (40-mL bolus; 320 mg of iodine per milliliter). RESULTS: Both techniques showed reduced PVP in patients with cirrhosis (0.63 for direct and 0.17 for indirect method) compared with control patients (1.06 and 0.26, respectively), but only the direct method agreed with physiologic expectations based on animal and human studies. In separating cirrhotic and control patients, the area under the receiver operating characteristic curve was significantly greater for the direct method (0.91 vs 0.78; P = .03). CONCLUSION: Both direct and indirect methods are feasible and distinguish well between cirrhotic and control patients, but the direct method is more physiologic and is preferable if portal venous data are available.     

Evaluation of computer-assisted diagnosis of small pulmonary nodules using contrast-enhanced dynamic helical CT

Dynamic helical computed tomography(DH-CT) was performed to examine 45 lesions(23 lung cancers, 2 pulmonary metastasis, and 20 benign nodules) as an application of computer-assisted qualitative analysis of small pulmonary nodules. Based on the three-dimensional(3D) CT image data, the internal structure of the nodule was assessed quantitatively and temporal changes were evaluated. The entire lesion was examined by helical scanning with a beam width of 2 mm(pitch of 1) before contrast enhancement and 2 and 4 minutes after contrast enhancement. Using the digital CT data, the pixels inside the nodules were quantified based on a combination of CT values and 3D curvature in order to differentiate between benign(BN) and malignant nodules (MN). (The numeral score abovementioned was calculated.) The average scores for BN 2 and 4 minutes were -5.72 and -12.8, respectively, and those for MN were 5.51 and 12.0, respectively(p < 0.01). Assuming that a score of 0 or higher indicates a MN based on the CT data 4 minutes. In conclusion, 3D computer-assisted analysis of the internal structure of small pulmonary nodules using contrast-enhanced DH-CT was found to be effective for differentiating between benign and malignant nodules.     

Efficacy of multi-slice helical CT venography for the diagnosis of deep venous thrombosis: comparison with venous sonography

OBJECTIVE: The purpose of this study was to assess the efficacy of contrast enhanced multi-slice helical CT (MSCT) venography for the diagnosis of deep venous thrombosis (DVT) in comparison with venous sonography. MATERIALS AND METHODS: MSCT was used to obtain contiguous, 5-mm thick axial CT images from the diaphragm to the ankles of 27 patients after intravenous injection of contrast material. These patients were clinically suspected of having DVT. The same patients underwent venous sonography before CT examination. The detectability of DVT with MSCT venography was compared with that with venous sonography. RESULTS: MSCT venography detected DVT in 21 patients, but venous sonography did so in only 17. MSCT venography detected DVT missed by venous sonography in five patients, while venous sonography detected DVT missed by MSCT venography in one patient. CONCLUSION: MSCT venography can be expected to make a valuable contribution to the diagnosis of DVT and to the prophylaxis of pulmonary embolism.