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.     

Hepatocellular carcinoma with skeletal metastasis

Three patients with symptoms related to metastases from hepatocellular carcinoma are described. The diagnosis of the primary tumor was made at autopsy in two cases and by biopsy in one. The skeletal lesions had a lytic, expansile, and hypervascular appearance. This hypervascularity may lead to bleeding either spontaneously or following biopsy. Hepatocellular carcinoma should be included in the differential diagnosis of osteolytic, expansile, hypervascular metastases, especially when such lesions are encountered in patients with liver cirrhosis.     

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.     

Hepatocellular carcinoma in cirrhotic livers: double-contrast thin-section MR imaging with pathologic correlation of explanted tissue

OBJECTIVE: The aim of our study was to determine the sensitivity of double-contrast MR imaging in the detection of hepatocellular carcinomas in patients with a cirrhotic liver. SUBJECTS AND METHODS: Thirty-one patients underwent double-contrast MR imaging and subsequent liver transplantation. Breath-hold T1- and T2-weighted MR images were obtained before and after administration of superparamagnetic iron oxide, and three-dimensional T1-weighted gradient-recalled echo MR images were obtained 10, 40, and 120 sec after a bolus injection of gadolinium. Hypervascular lesions that failed to take up superparamagnetic iron oxide were regarded as showing typical characteristics of hepatocellular carcinoma; lesions that had only one of these two characteristics (either hypervascularity or failure to take up superparamagnetic iron oxide) were regarded as highly suspicious for hepatocellular carcinoma. Radiology reports were correlated with pathology reports for the explanted livers. RESULTS: Thirty-two hepatocellular carcinomas were found in 14 of the 31 patients. Combining the number of MR imaging reports citing lesions that were "typical of hepatocellular carcinoma" with the number of those citing lesions that were "highly suspicious," we found that for 25 of 32 lesions, an accurate MR imaging diagnosis of hepatocellular carcinoma was made (overall sensitivity, 78%). These lesions included 10 of the 11 lesions that were larger than 20 mm (sensitivity, 91%), 12 of the 13 lesions that were 11-20 mm (sensitivity, 92%), and three of the eight lesions that were 10 mm or less (sensitivity, 38%). Nineteen (76%) of 25 lesions had characteristics considered typical of hepatocellular carcinoma; the remaining six lesions either failed to take up superparamagnetic iron oxide and were hypovascular or were hypervascular but showed some uptake of superparamagnetic iron oxide. CONCLUSION: In patients with a cirrhotic liver, double-contrast MR imaging is highly sensitive in the diagnosis of hepatocellular carcinomas of 10 mm or larger, but success in the identification of tumors smaller than 10 mm is still limited.     

Correlation of three-dimensional gradient echo dynamic MR imaging with CT during hepatic arteriography in patients with hypervascular hepatocellular carcinomas: preliminary clinical experience

The purpose of this study is to elucidate the usefulness of dynamic MR study of the whole liver using 3DFISP with double dose gadolinium (Gd) enhancement in detecting enhancing lesions in 20 patients. Twenty patients with hepatocellular carcinoma (HCC) underwent 3DFISP dynamic study with double dose Gd. The demonstration of enhancing hypervascular lesions regardless of etiology was evaluated on a segment-by-segment basis with receiver operating characteristic (ROC) analysis, using findings on CT during hepatic arteriography as a gold standard. Diagnostic accuracy of 3DFISP in the detection of HCC was also evaluated. As to the demonstration of enhancing lesions, the Az value of the ROC curve was 88%. The detection rate of HCC with 3DFISP was 98%. 57% of enhancing pseudolesions were not detected on 3DFISP. We concluded that Dynamic MR study of the whole liver using 3DFISP with double dose Gd enhancement is a useful method to demonstrate hypervascular HCC.     

Dysplastic hepatic nodules: Radiological abnormalities and histopathological correlations

Pathological studies of explanted cirrhotic livers have made it possible to define precisely the principal morphological characteristics of the transitional stages of the regenerative nodule to dysplastic nodule to hepatocellular carcinoma.The aim of our study was to examine the imaging features of histologically proven dysplastic nodules and to compare them with their histopathological features.A large majority (63%) of the dysplastic nodules in our series was hypervascular and 16% had the classic appearance of hepatocellular carcinoma. Even if the management of a high-grade dysplastic nodule differs little from that of a hepatocellular carcinoma, it is important to remember that not all hypervascular nodules in a cirrhotic liver are necessarily a hepatocellular carcinoma or a high-grade dysplastic nodule.     

Evaluation of optimal timing of arterial phase imaging for the detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography

PURPOSE: We evaluated the optimal timing of arterial phase imaging for detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography. MATERIALS AND METHODS: Forty-nine patients with 90 hypervascular hepatocellular carcinomas (3 to 50 mm in diameter; mean, 18.7 mm) underwent triple arterial phase imaging of the whole liver using a multidetector-row helical computed tomography. At 20 seconds, 30 seconds, and 40 seconds after intravenous administration of 100 mL of 300 mgI/mL of nonionic contrast medium at a rate of 4 mL/s, early, middle, and late arterial phase images were obtained serially during a single breath-hold with an interscan delay of 5 seconds. Detector-row configurations of 4 mm x 4, scan pitch of 5.5, and scan time of 5 seconds for each phase were used. Forty prospective reconstruction images of 5-mm thickness for each phase were obtained. The images from each phase were interpreted separately for detection of hypervascular hepatocellular carcinoma by 3 observers independently who were unaware of tumor burden in the liver. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve values for each arterial phase were calculated and compared statistically. RESULTS: The mean sensitivity and positive predictive values for hypervascular hepatocellular carcinoma diagnosis of blind readers were 37% and 87% for the early arterial phase, 73% and 85% for the middle arterial phase, and 49% and 81% for the late arterial phase, respectively. The middle arterial phase imaging showed significantly superior sensitivity compared with the early and late arterial phase for detecting hepatocellular carcinoma (P < 0.05). Mean area under the receiver operating characteristic curve value of the middle arterial phase imaging (0.84) was significantly higher that that of the early (0.56) or late arterial phase (0.62; P < 0.05). CONCLUSION: If a single arterial phase is used for diagnosis of hypervascular hepatocellular carcinoma, the middle phase (delay time of 30 seconds) is optimal.     

CT of benign hypervascular liver nodules in autoimmune hepatitis

OBJECTIVE: The purpose of this report is to describe the frequency and histopathologic basis of benign hypervascular liver nodules seen on CT in patients with autoimmune hepatitis. CONCLUSION: Benign hypervascular liver nodules may be seen on CT in patients with cirrhosis due to autoimmune hepatitis and may represent large regenerative nodules. This phenomenon is important to recognize because of the potential for confusion with hepatocellular carcinoma.     

CT during hepatic arteriography and portography: an illustrative review.

The combination of computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) has been used for evaluation of hepatic neoplasms before partial hepatic resection. Focal hepatic lesions that can be demonstrated with CTAP and CTHA include regenerative nodules, dysplastic nodules, dysplastic nodules with malignant foci, hepatocellular carcinoma, cholangiocarcinoma, hemangioma, and metastases. CTAP is considered the most sensitive modality for detection of small hepatic lesions, particularly small hepatic tumors such as hepatocellular carcinoma and metastatic tumors. CTHA can demonstrate not only hypervascular tumors but also hypovascular tumors and can help differentiate malignant from benign lesions. However, various types of nontumorous hemodynamic changes are frequently encountered at CTAP or CTHA and appear as focal lesions that mimic true hepatic lesions. Such hemodynamic changes include several types of arterioportal shunts, liver cirrhosis, Budd-Chiari syndrome, inflammatory changes, pseudolesions due to an aberrant blood supply, and laminar flow in the portal vein. Familiarity with the CTAP and CTHA appearances of various hepatic lesions and nontumorous hemodynamic changes allows the radiologist to improve the diagnostic accuracy.     

Multidetector CT: diagnostic impact of slice thickness on detection of hypervascular hepatocellular carcinoma

OBJECTIVE: The objective of our study was to evaluate the diagnostic impact of varying slice thickness on multidetector CT to optimize detection of hypervascular hepatocellular carcinoma. MATERIALS AND METHODS: Forty-three patients with 87 hypervascular hepatocellular carcinomas (diameter: range, 3-80 mm; mean, 22 mm) and 19 patients with either chronic hepatitis or liver cirrhosis and without hepatocellular carcinoma who had undergone early arterial and late arterial phase imaging of the entire liver on multidetector CT were retrospectively enrolled in this study. The detector row configuration was 2.5 x 4 mm, the pitch was 6, and the scanning time was 10.5 sec for each phase. All patients received contrast medium (2 mL/kg of body weight) at a rate of 5 mL/sec; the mean scanning delay for the early arterial phase was 19.0 sec, and the mean delay for the late arterial phase was 34.5 sec. Eighty 2.5-mm-thick reconstruction images, forty 5-mm-thick reconstruction images, and twenty-six 7.5-mm-thick reconstruction images were obtained for each phase. Each image set was interpreted separately by three observers to detect hypervascular hepatocellular carcinoma by viewing images on a workstation monitor. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve (A(z)) were calculated. We used retrospectively excellent follow-up and imaging or pathologic proof as the gold standard. RESULTS: The mean sensitivity and positive predictive value for hypervascular hepatocellular carcinoma were 76% and 69% on 2.5-mm images, 73% and 69% on 5-mm images, and 67% and 76% on 7.5-mm images, respectively. No significant difference in sensitivity among the images was detected, except by one observer who reported a significant difference in the sensitivity between 2.5- and 7.5-mm images (p < 0.05) and between 5- and 7.5-mm images (p < 0.05). The mean A(z) values were 0.79, 0.80, and 0.78 for 2.5-, 5-, and 7.5-mm images, respectively. No significant difference in A(z) values among the images obtained with different slice thicknesses was detected. CONCLUSION: For multidetector CT identification of hypervascular hepatocellular carcinoma, we found little or no advantage in reducing slice thickness to less than 5 mm.     

Optimal phase of dynamic CT for detecting hypervascular hepatocellular carcinoma: evaluation of double arterial phases

PURPOSE: To investigate the appropriate time of arterial phase for the detection of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-two hypervascular HCCs of 36 patients were evaluated on double arterial-phase images of the liver. The first and second arterial-phase images were obtained 10 sec after aortic peak enhancement time as determined by test bolus injection. Patients received a low or high concentration of contrast medium, according to their body weight, that was administered intravenously at a rate of 4 mL/sec and injection duration of 23 sec. Three radiologists evaluated the images separately. RESULTS: Sensitivity in detecting hypervascular HCCs was higher in the first arterial phase than in the second arterial phase (p = 0.039). HCCs were not detected as hypervascular nodules in one of 20 cases during 31 or fewer sec, or in 8 of 19 cases during 48 or more sec after the initiation of contrast medium injection. All nodules were detected as hypervascular lesions between 32 and 47 sec after the initiation of contrast medium injection. CONCLUSION: When a single arterial phase is obtained to detect hypervascular HCCs with a 23-sec injection time and an injection rate of 4 mL/sec, a protocol is recommended in which scanning is started at 35 sec and ended within 47 sec after initiating the injection of contrast medium.     

Percutaneous ablation therapy guided by contrast-enhanced sonography for patients with hepatocellular carcinoma

OBJECTIVE: The newly developed contrast-enhanced harmonic gray-scale sonography technique enables us to improve the real-time detectability of viable tumor tissue in hepatocellular carcinoma lesions. We evaluated the usefulness of real-time percutaneous ablation therapy under guidance with this method for patients with hepatocellular carcinoma that is not depicted on conventional sonography. SUBJECTS AND METHODS: We examined 30 patients with 56 hepatocellular carcinomas using real-time contrast-enhanced harmonic gray-scale sonography after injection of a galactose-palmitic acid contrast agent and compared the results with the findings of contrast-enhanced helical CT. We performed percutaneous ablation therapy guided by this modality for treatment of viable hepatocellular carcinoma lesions that could not be detected using conventional sonography. RESULTS: High detection rates of viable hepatocellular carcinoma lesions were obtained using real-time contrast-enhanced harmonic gray-scale sonography (52/56 lesions, 93%); these rates were comparable to those of helical CT (54/56 lesions, 96%). Nine (90%) of the 10 lesions that were not detected on conventional sonography but were depicted on real-time contrast-enhanced harmonic gray-scale sonography (incomplete local treatment, n = 4; small new lesion, n = 6) were successfully treated with percutaneous ablation therapy guided by this method. CONCLUSION: Real-time contrast-enhanced harmonic gray-scale sonography improved the sensitivity for the detection of viable hepatocellular carcinoma lesions. Percutaneous ablation therapy guided by this modality may be useful in patients with hypervascular hepatocellular carcinoma lesions that cannot be detected using conventional sonography.     

螺旋CT双期肝脏增强扫描对肝癌和肝转移瘤的诊断

目的：比较螺旋CT肝脏双期增强扫描的动脉期和门脉期对肝癌和肝转移瘤的检出率。材料和方法：对97例肝癌和47例肝转移瘤病人行螺旋CT双期增强扫描，造影剂注射速度为3ml／S，扫描延迟时间动脉期为30秒，门脉期为65秒。比较动脉期和门脉期对病灶的检出率。结果：207个肝癌病灶，动脉期和门豚期检出率分别为92％和83％，其中对于直径≤3cm病灶的检出率分别为83％和54％（P＜0．005）。482个转移瘤病灶，动脉期和门脉期的检出率分别为70％和96％，动脉期在7例病人中多检出17个病灶。结论：动脉期与门脉期相比，可以显著提高对肝癌和其它多血管肿瘤的检出率，对小的肝癌病灶检出的意义更大。     

Newly developed hepatocellular carcinoma (HCC) in chronic liver disease: MR imaging findings before the diagnosis of HCC

PURPOSE: The purpose of this work was to describe the initial magnetic resonance (MR) imaging findings obtained before an imaging diagnosis of overt hepatocellular carcinoma (HCC) in the chronically damaged liver. METHODS: One hundred fifty-two newly diagnosed HCCs diagnosed by dynamic computed tomography (n = 111) or by MR imaging (n = 41), in addition to digital subtraction hepatic arteriography, in 96 patients were subjected to analysis of their MR imaging features within the previous 2 years. RESULTS: Ninety-seven (64%) HCC cases showed no focal lesions distinguishable from background hepatic parenchyma in MR images taken before the indication of typical HCC. The remaining 55 (36%) lesions were readily identified in earlier images and were categorized into 3 groups: nonhypervascular lesions (category I, n = 6), lesions with partially hypervascular foci of "nodule-within-nodule" appearance (category II, n = 12), and homogeneously hypervascular and/or T2-weighted hyperintense lesions (category III, n = 37). The size and doubling time of category III lesions (0.7 cm, 154 days) were smaller and shorter than those of the other lesions (1.2 cm, 377 days). CONCLUSIONS: Before the imaging diagnosis of HCCs, the premalignant or early malignant lesions can be found on the prior MR images just in the minority of the lesions in the cirrhotic liver.     

Prognostic significance of arterial phase CT for prediction of response to transcatheter arterial chemoembolization in unresectable hepatocellular carcinoma: a retrospective analysis

OBJECTIVE: The purpose of this study was to use hepatic arterial phase helical CT to assess tumor vascularity and predict the likelihood of response to transcatheter arterial chemoembolization in patients with hepatocellular carcinoma. MATERIALS AND METHODS: Helical CT findings for 57 patients with hepatocellular carcinoma were classified into one of three patterns of vascularity on the basis of the degree of tumor or liver enhancement during the hepatic arterial phase. Cases in which hypervascular lesions predominated were classified as a type 1 pattern. Cases in which hypovascular lesions predominated were classified as a type 2 pattern. Patients were classified as responders or nonresponders on the basis of the changes of tumor size revealed on CT after three transcatheter arterial chemoembolization treatments. RESULTS: We classified the 57 patients as 37 responders (65%) and 20 nonresponders (35%). A statistically significant correlation between the type 1 hypervascular pattern and response to transcatheter arterial chemoembolization was seen; conversely, the type 2 hypovascular pattern correlated with nonresponse to transcatheter arterial chemoembolization (chi-square = 7.85, p = 0.02). Patients classified as responders lived significantly longer than those classified as nonresponders with 12-, 24-, and 36-month survival rates of 90%, 67%, and 36%, respectively, for responders and 70%, 17%, and 10%, respectively, for nonresponders. CONCLUSION: We found that patients who responded to transcatheter arterial chemoembolization had prolonged survival (p < 0.01). Response correlated closely with tumor vascularity as shown on hepatic arterial phase helical CT.     

Contrast-enhanced harmonic ultrasound imaging in ablation therapy for primary hepatocellular carcinoma

The success rate of percutaneous radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) depends on correct targeting via an imaging technique. However, RF electrode insertion is not completely accurate for residual HCC nodules because B-mode ultrasound (US), color Doppler, and power Doppler US findings cannot adequately differentiate between treated and viable residual tumor tissue. Electrode insertion is also difficult when we must identify the true HCC nodule among many large regenerated nodules in cirrhotic liver. Two breakthroughs in the field of US technology, harmonic imaging and the development of second-generation contrast agents, have recently been described and have demonstrated the potential to dramatically broaden the scope of US diagnosis of hepatic lesions. Contrast-enhanced harmonic US imaging with an intravenous contrast agent can evaluate small hypervascular HCC even when B-mode US cannot adequately characterize tumor. Therefore, contrast-enhanced harmonic US can facilitate RF ablation electrode placement in hypervascular HCC, which is poorly depicted by B-mode US. The use of contrast-enhanced harmonic US in ablation therapy for liver cancer is an efficient approach.     

Transarterial chemoembolization with miriplatin-lipiodol emulsion for neuroendocrine metastases of the liver

Miriplatin, a cisplatin derivative with a high affinity for iodized oil, is a novel chemotherapeutic agent designed for use in the transarterial treatment of hepatocellular carcinoma. This case report describes our experience with transarterial chemoembolization (TACE) using miriplatin in 2 patients with neuroendocrine liver metastases. A 38-year-old man with multiple neuroendocrine liver metastases was treated by whole liver chemoembolization, and a 35-year-old woman with a single hepatic lesion was treated by superselective chemoembolization. No serious adverse events were noted during the interventional procedures, or during the observation period of 3 mo in either patient. Sufficient iodized oil uptake was observed in the hypervascular lesions on the unenhanced computed tomography (CT) at 7 d after the procedure. Contrast-enhanced CT obtained at 3 mo after chemoembolization revealed that all hepatic lesions were substantially reduced in size irrespective of tumor vascularity or degree of cystic degeneration, although iodized oil accumulation was only marginal for lesions with cystic degeneration. Thus, TACE with miriplatin can be a safe and effective therapeutic option for the treatment of neuroendocrine metastases of the liver.     

Malignant hepatic tumors: Changes on MRI after hepatic arterial chemoembolization – preliminary findings

This study describes the MR appearances of malignant hypervascular liver lesions pre- and post-hepatic-arterial chemoembolization, with correlation to serial imaging and clinical responses. Eight patients with malignant hypervascular liver lesions underwent pretreatment and posttreatment MR examination on a 1.5-T MR imager. MR sequences included T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed spin echo or turbo spin echo, and dynamic gadolinium-enhanced SGE images. All patients underwent pretreatment, initial posttreatment, and subsequent posttreatment MR studies. The histology of primary tumors included various types of hepatocellular carcinoma (HCC) (four patients: fibrolamellar HCC [one patient], HCC [two patients], mixed HCC/cholangiocarcinoma [one patient]) and liver metastases (four patients: untyped islet cell tumor [two patients], gastrinoma [one patient], carcinoid [one patient]). Response to chemoembolization was determined by three assessments: MR response, serial imaging response, and clinical response. The appearance of MR response to chemoembolization was determined based on the correlation with clinical and serial imaging response. The MR response of lesions that showed good clinical response included: increase in signal intensity on T1-weighted images (three patients), decrease in signal intensity on T2-weighted images (three patients), and negligible or minimal enhancement on immediate postgadolinium images (four patients) after chemoembolization. The most marked change in lesion appearance was observed in lesions < 1 cm, which had intense homogeneous enhancement on pretreatment MR studies and negligible enhancement on initial posttreatment MR examinations. MR response of lesions that showed moderate clinical response demonstrated a variety of lesion appearances from substantial change to minimal change. MR response of lesions that showed poor clinical response demonstrated no change in lesion appearances compared with the pretreatment MR study. Our results demonstrated change in appearance of liver lesions between pre- and post-hepatic-arterial chemoembolization MR studies. MR response correlated with response determined by serial imaging studies and clinical findings.     

Hypervascular hepatocellular carcinoma: detection with double arterial phase multi-detector row helical CT

PURPOSE: To assess whether double arterial phase imaging with multi-detector row helical computed tomography improves detection of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-one patients with 96 hypervascular HCCs underwent double arterial phase imaging of the entire liver. At measured delay after intravenous administration of 2 mL/kg of contrast medium at a rate of 5 mL/sec, the early and late arterial phase images were obtained serially during a single breath hold with interscan delay of 5.0 seconds. Detector row configuration of 2.5 x 4 mm, pitch of 6, and scanning time of 10.5 seconds for each phase were used. Forty 5-mm-thick reconstruction images were obtained for each phase. Each image set was interpreted separately by three observers, who were unaware of tumor burden in the liver, to detect hypervascular HCC. Sensitivity, positive predictive value, and area below the receiver operating characteristic curve (A(z)) for early and late arterial phases separately and together were calculated. RESULTS: Mean sensitivity and positive predictive value for hypervascular HCC were 54% and 85% for the early arterial phase, 78% and 83% for the late arterial phase, and 86% and 92% for the double arterial phase, respectively. Double arterial phase imaging showed significantly superior sensitivity compared with early or late arterial phase imaging alone for detecting HCC (P <.05). The mean A(z) value for double arterial phase was significantly higher than that for early or late arterial phase imaging alone (P <.05). Double arterial phase imaging showed the lowest number of false-positive lesions. CONCLUSION: Double arterial phase imaging is recommended to improve detection of hypervascular HCCs and reduce false-positive lesions.     

Pseudolesion of the liver observed on gadoxetate disodium-enhanced magnetic resonance imaging obtained shortly after transarterial chemoembolization for hepatocellular carcinoma

The purpose of this report was to describe pseudolesions of the liver that mimicked residual hypervascular hepatocellular carcinoma (HCC), as observed on gadoxetate disodium-enhanced magnetic resonance imaging (EOB-MRI) obtained shortly after transarterial chemoembolization (TACE). Between June 2008 and December 2008, three patients underwent MRI within 12 days after TACE to rule out remaining viable cancerous tissue or to assess the treatment effect. In all three patients, nontumorous liver tissue adjacent to the treated HCC exhibited focal arterial enhancement on dynamic phase and subsequent diminished uptake of gadoxetate disodium on hepatocellular phase images, which mimicked residual HCC. All three patients had mild postembolization syndrome at the time of EOB-MRI and showed no evidence of residual or recurrent tumors on follow-up. The findings of these areas may represent transient focal hyperemia and damage to the liver cell function caused by TACE. Radiologists should be aware that EOB-MRI obtained shortly after TACE may show pseudolesions around the treated tumors and should not mistake them for residual or recurrent tumors.