Liver lesions: manganese-enhanced MR and dual-phase helical CT for preoperative detection and characterization comparison with receiver operating characteristic analysis

PURPOSE: The purpose of this study was to compare, by means of receiver operating characteristic (ROC) analysis, dual-phase helical computed tomography (CT) and manganese-enhanced magnetic resonance (MR) imaging in the detection and characterization of hepatic lesions in patients prior to surgery. MATERIALS AND METHODS: Twenty-five patients known to have or suspected of having hepatic lesions who were eligible for surgery underwent dual-phase (ie, arterial and portal phase) helical CT and phased-array MR imaging (ie, unenhanced fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging performed before and after administration of mangafodipir trisodium). All images were reviewed independently by three off-site blinded reviewers who separately reviewed the CT scans and MR images. The standard of reference was findings at surgery, intraoperative ultrasonography (US), and histopathologic examination. ROC curves were established to analyze the results for each reader and modality. RESULTS: Ninety-four lesions (77 malignant and 17 benign) were revealed at surgery, intraoperative US, and/or histopathologic examination. The overall rate of lesion detection for the three readers at CT was 81.9% +/- 7.8, 90.4% +/- 5.9, and 76.6% +/- 8.6. At MR imaging, the detection rates were 72.3% +/- 9.0, 71.3% +/- 9.1, and 69.1% +/- 9.3 (P =.001 for the difference between MR and CT). The average rate of false-positive diagnoses in patients was 14.1% at CT and 6.4% at MR imaging (P =.06 for the difference between MR and CT). The mean areas under the alternative-free-response ROC curves were 0.74 for MR and 0.72 for CT (P =.751, not significant). CONCLUSION: In detection and characterization of liver lesions, manganese-enhanced MR imaging and dual-phase helical CT were not statistically different.     

Detection of hepatic lesions in candidates for surgery: comparison of ferumoxides-enhanced MR imaging and dual-phase helical CT

OBJECTIVE: The purpose of this study was to compare the use of phased array MR imaging of the liver at 1.5 T with and without ferumoxides with dual-phase helical CT for the detection of hepatic lesions in candidates for hepatic surgery. SUBJECTS AND METHODS: Patients with known or suspected hepatic lesions who were eligible for surgery underwent dual-phase helical CT at 20 and 70 sec after the start of contrast material injection and phased array MR imaging using fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging before and after ferumoxides infusion of 0.56 mg of iron per kilogram of body weight. Three observers who were unaware of the surgical findings separately reviewed the CT scans and unenhanced and enhanced MR images of 24 patients who completed the protocol. The observers' findings were compared with results obtained at surgery using intraoperative sonography and having histopathologic confirmation. Statistical analysis was performed using a segment-by-segment analysis. RESULTS: Eighty-two lesions were found at surgery. The sensitivity of CT, unenhanced MR imaging, and enhanced MR imaging for blinded observers was 60.4%, 62.0%, and 68.2%, respectively. The specificity was 89.2%, 81.9%, and 81.6%, respectively. Five lesions in three patients were not detected preoperatively using any of the techniques. MR imaging found additional lesions not detected on CT in four patients; CT detected one additional lesion not seen on MR imaging. CONCLUSION: Ferumoxides-enhanced MR imaging of the liver shows a trend toward increased sensitivity compared with dual-phase helical CT. Specificity of helical CT was superior to that of enhanced MR imaging for most observers.     

Focal liver lesions: comparison of dual-phase CT and multisequence multiplanar MR imaging including dynamic gadolinium enhancement

The purpose of this study was to compare dual-phase spiral computed tomography (CT) and magnetic resonance imaging (MRI) using dynamic gadolinium enhancement for liver lesion detection and characterization. Twenty-two consecutive patients underwent dual-phase spiral CT and MRI for the evaluation of focal liver disease within a 1-month period. Spiral CT and MR images were interpreted prospectively, in a blinded fashion by separate, individual, experienced investigators, to determine lesion detection and characterization. Liver lesions were confirmed by surgery and pathology in 6 patients, and by clinical and imaging follow-up in the other 16 patients. Pathological correlation of a primary extrahepatic malignancy was available in 5 of the 16 patients who had metastatic liver disease. Spiral CT and MRI detected 53 and 63 lesions, and characterized 39 and 62 true positive lesions, respectively. A kappa statistic test was applied to assess agreement between MR and CT results. MR versus CT for lesion detection resulted in a kappa statistic of 0.54 (95% confidence interval), indicating moderate agreement, and 0.32 (95% confidence interval) for lesion characterization, indicating only slight agreement. More lesions were detected on MR images than CT images in 6 (27%) patients, with lesions detected only on MR images in 4 (18%) patients. More lesions were characterized on MR images in 9 (41%) patients. In 9 patients with a discrepancy between MR and CT findings, the MR images added information considered significant to patient management in all 9 cases. MRI was moderately superior to dual-phase spiral CT for lesion detection, and was markedly superior for lesion characterization, with these differences having clinical significance.     

Discrimination of small hepatic hemangiomas from hypervascular malignant tumors smaller than 3 cm with three-phase helical CT

PURPOSE: To compare the appearance of small hepatic hemangiomas at nonenhanced and contrast material-enhanced helical computed tomography (CT) with that of small (<3-cm) hypervascular malignant liver tumors and to evaluate the accuracy of multiphase helical CT for differentiating small hemangiomas from small hypervascular malignant tumors. MATERIALS AND METHODS: Radiologists reviewed multiphase helical CT liver images in 86 patients with 37 hemangiomas and 49 malignant liver tumors. They evaluated lesion type and degree of enhancement for change from arterial to portal venous phase. They rated their confidence in the discrimination of hemangiomas from malignant tumors. RESULTS: At arterial phase CT, enhancement similar to aortic enhancement was observed in 19%-32% of hemangiomas and 0%-2% of malignant tumors; globular enhancement, in 62%-68% and 4%-12%, respectively. At portal venous phase CT, enhancement similar to blood pool enhancement was observed in 43%-54% of hemangiomas and 4%-14% of malignant tumors; globular enhancement, in 46%-49% and 0%-2%, respectively. For all readers and all phases of enhancement, the area under the receiver operating characteristic curves was 0.81-0.87, indicating that inherent accuracy of CT is high and that there was no significant difference (P >.28) in overall accuracy. Readers diagnosed hemangiomas with 47%-53% mean sensitivity with all enhancement phases and diagnosed malignant lesions with 95% mean specificity. CONCLUSION: Small hemangiomas frequently show atypical appearances at CT. Two-phase helical CT does not improve sensitivity but does improve specificity for differentiating hemangiomas from hypervascular malignant tumors.     

螺旋CT对微波凝固治疗肝细胞癌的疗效评价

目的 研究微波凝固治疗肝细胞癌后的螺旋CT表现，评价CT征象与疗效之间的关系。方法 分析经超声引导下行微波凝固治疗的原发性肝细胞癌病人22例、共26个病灶的螺旋CT征象。结果 21个病灶肝动、门脉双期病灶内和边缘部均未见强化。7个病灶肝动脉期病灶周围的肝组织见斑片状轻度至明显的强化。5个病灶肝动脉期病灶内或病灶边缘部见结节样强化。结论 螺旋CT的双期增强扫描可以准确地判断超声引导下微波凝固治疗肝细胞癌的治疗效果，当双期扫描病灶内无强化时，说明病灶无肿瘤残留；当动脉期病灶周围肝组织出现斑片状轻度至明显强化时，属于微波凝固治疗后的正常反应；当动脉期病灶内或病灶边缘部出现结节样强化时，说明病灶内肿瘤有残留复发。     

Pancreatic cystic lesions: discrimination accuracy based on clinical data and high resolution CT features

OBJECTIVE: To determine the accuracy of high-resolution computed tomography in discriminating among pancreatic cystic lesions with and without clinical history. METHODS: Multiphasic high-resolution computed tomographic scans of 100 proven cystic pancreatic lesions were retrospectively reviewed by 2 blinded imagers. Before and after a history of pancreatitis was revealed, readers classified lesions as either nontumor-related or tumor-related. Reviewers also classified lesions as benign or malignant and finally categorized each lesion as serous, mucinous, or other lesion. Diagnostic performance parameters for classification were calculated for each reader with and without history. RESULTS: Sixty-two lesions were tumor-related and 38 were not. Accuracy for classifying tumor-related from unrelated cysts for both reviewers increased (83%-92%, 85%-91%) when unblinded to pancreatitis history. Specificity also significantly increased (66%-88% and 84%) for both reviewers. CONCLUSIONS: Pancreatic-phase computed tomography enabled more than 80% accuracy in discriminating between tumor-related and unrelated lesions and increased with information of pancreatitis history.     

Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging: multicenter study comparing MR and dual-phase spiral CT

PURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were suspected of having focal liver lesions were included in a multicenter study and underwent dual-phase spiral CT and enhanced MR imaging. Image interpretations performed by independent experienced radiologists were compared with the final diagnosis that was based on all available clinical information (including histopathologic findings in 77 patients) and that was determined with consensus. Differences in classifications by using either enhanced MR imaging or dual-phase spiral CT were analyzed with the McNemar test, and receiver operating characteristic (ROC) curves were used to compare the diagnostic performance of enhanced MR imaging and dual-phase spiral CT. RESULTS: Lesion classification was correct in 108 (74%) patients with enhanced MR imaging and in 83 (57%) with dual-phase spiral CT (P =.001). Lesions were correctly classified as either malignant or benign in 123 (85%) patients with enhanced MR imaging and in 98 (68%) with dual-phase spiral CT (P =.001). Classification of lesions as either hepatocellular or nonhepatocellular was correct in 130 (90%) patients with enhanced MR imaging and in 93 (64%) with dual-phase spiral CT (P =.001). These differences remained when analyses were restricted to histopathologically confirmed diagnoses. Comparison of the ROC curves illustrated that enhanced MR imaging performance surpassed that of dual-phase spiral CT. CONCLUSION: Mn-DPDP-enhanced MR imaging is superior to dual-phase spiral CT in classification of focal liver lesions.     

Efficacy and safety of MR imaging with liver-specific contrast agent: U.S. multicenter phase III study

PURPOSE: To assess prospectively the efficacy and safety of postcontrast magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) compared with that of precontrast MR imaging in patients who are known to have or are suspected of having liver lesions and who are scheduled for hepatic surgery. MATERIALS AND METHODS: Investigational review board approval and written informed consent were obtained. HIPAA went into effect after data collection. A total of 172 patients were enrolled. After precontrast MR imaging, 169 patients (94 men, 75 women; mean age, 61 years; age range, 19-84 years) received an intravenous bolus of 25 micromol/kg Gd-EOB-DTPA and underwent dynamic gradient-recalled-echo and delayed MR imaging 20 minutes after injection. Arterial and portal phase computed tomography (CT) were performed within 6 weeks of MR imaging. The standard of reference was surgery with intraoperative ultrasonography (US) and biopsy and/or pathologic evaluation of resected liver segments and/or 3-month follow-up of nonresected segments if intraoperative US was not available. Three blinded reviewers and unblinded site investigators identified liver lesions on segment maps. The Wilcoxon signed rank test was used to compare differences in per-patient sensitivity of precontrast and postcontrast MR images. Adverse events were recorded, and patient monitoring and laboratory assay were performed at time of injection and up to 24 hours after contrast material administration. RESULTS: At MR imaging, 316 lesions were identified in 131 patients. In 77% (P = .012), 72% (P = .15), and 71% (P = .027) of patients for readers 1, 2, and 3, respectively, more lesions were seen at precontrast and postcontrast MR imaging combined than at precontrast MR imaging alone. Sensitivity values for blinded readings were significantly greater at postcontrast MR imaging than at precontrast MR imaging for two of three blinded readers. For all blinded readers, combined precontrast and postcontrast MR images showed no difference in sensitivity compared with helical CT scans. The use of MR imaging, however, yielded fewer patients with at least one false-positive lesion (37%, 31%, and 34% of patients for readers 1, 2, and 3, respectively) than did helical CT (45%, 36%, and 43% of patients for readers 1, 2, and 3, respectively). CONCLUSION: Compared with precontrast MR imaging, postcontrast MR imaging with Gd-EOB-DTPA demonstrated improved sensitivity for lesion detection in the majority of blinded readers, with no substantial adverse events.     

Small (<or= 2 cm) hepatic lesions in colorectal cancer patients: detection and characterization on mangafodipir trisodium-enhanced MRI

OBJECTIVE: The purpose of this study was to evaluate whether mangafodipir trisodium (MnDPDP)-enhanced MRI improves the detection and characterization of small ( 2.0 cm). The differences between MnDPDP-enhanced MRI and helical CT with regard to the detection rates for hepatic lesions and metastases and with regard to the false-positive rates for hepatic metastases were analyzed using the McNemar test. The performances of MnDPDP-enhanced MRI and helical CT in indicating metastases of focal liver lesions were analyzed using receiver operating characteristic curves. RESULTS: No statistically significant differences were seen between MnDPDP-enhanced MRI and helical CT in the detection of all hepatic lesions (p = 0.383) and small lesions (p = 0.210). However, concerning the differentiation between benign and metastatic lesions, MnDPDP-enhanced MRI was superior to helical CT both for all hepatic lesions (p = 0.023) and for small lesions (p = 0.015), and remained better when the analyses were restricted to patients with histopathologic confirmation (p = 0.023 for both). MnDPDP-enhanced MRI changed the diagnosis of hepatic metastasis in nine (13.0%) of 69 patients. Of 12 metastases that were found on MnDPDP-enhanced MRI and missed on helical CT, 11 lesions (91.7%) were small. MnDPDP-enhanced MRI showed a significantly greater detection rate than helical CT for small hepatic metastases (p = 0.022). MnDPDP-enhanced MRI was better when the analyses were restricted to patients with histopathologic confirmation (p = 0.043). CONCLUSION: Although MnDPDP-enhanced MRI is equal to helical CT in detection of both all hepatic lesions and small lesions in patients with colorectal carcinoma, it is superior to CT in characterization of the lesions.     

Comparison of image quality and focal lesion detection in abdominopelvic CT: Potential dose reduction using advanced modelled iterative reconstruction

PurposeTo evaluate radiation dose exposure, diagnostic performance, and image quality of low-dose and ultralow-dose abdominopelvic CT using the advanced modelled iterative reconstruction (ADMIRE) algorithm for focal lesion detection.MethodsOne hundred thirty-nine consecutive patients underwent contrast-enhanced abdominopelvic CT using a third-generation dual-source scanner to obtain three data sets with the following tube loads: 33.3% (ultralow-dose CT), 66.7% (low-dose CT), and 100% (standard-dose CT). The diagnostic performances of standard-dose CT, low-dose CT, and ultralow-dose CT for focal lesion detection and characterization in organs of the abdominopelvic cavity were analyzed by two readers and compared with the reference standard. Image quality was measured subjectively and objectively.ResultsFocal lesion detection showed 96.5–100% sensitivity and 97.7–100% accuracy in all representative organs on low-dose CT with acceptable image quality; it showed 87.4% sensitivity and 97.9% accuracy in the liver and 80.0% sensitivity and 88.2% accuracy in the rectal shelf on ultralow-dose CT with suboptimal image quality. Indeterminate lesions were significantly more common in the liver, pancreas, and kidneys on ultralow-dose CT than on low-dose CT. Enlarged lymph nodes showed 100% sensitivity and accuracy on ultralow-dose CT. Mean effective radiation doses of low-dose CT and ultralow-dose CT were 2.6 mSv and 1.3 mSv, respectively.ConclusionsThe diagnostic performance of low-dose CT is similar to that of standard-dose abdominopelvic CT with acceptable image quality. Ultralow-dose CT cannot safely assess focal liver, pancreas, kidneys, and rectal shelf lesions but may be useful for the evaluation of enlarged lymph nodes.     

少血供小肝癌的螺旋CT表现并与病理对照

目的 研究螺旋CT双期增强扫描低密度小肝癌的CT表现及其病理学基础。方法 分析经手术病理证实的螺旋CT双期增强扫描表现为低密度的小肝癌25例共27个病灶的CT征象和病理学改变。结果 (1)平扫病灶边界模糊不清者有16个病灶，边界清楚者有11个病灶；增强后病灶边界模糊者只有7个病灶，边界清楚者有20个病灶，同时病灶边缘轮廓轻度不规整。(2)平扫瘤内呈均匀性低密度者有18个病灶，瘤内密度不均匀者有9个病灶；增强后瘤内密度均匀者只有6个病灶，瘤内密度不均匀、有多个小斑点状密度更低区者有21个病灶。结论 螺旋CT双期增强扫描低密度小肝癌的CT表现特点是：平扫病灶边界模糊，增强后病灶边界变清楚并呈轻度不规整，同时病灶内密度不均匀，有多个小斑点状密度更低区。根据该特点可以与肝脏的其他表现为低密度的病变进行鉴别。     

Improved detection of focal liver lesions at MR imaging: multicenter comparison of gadoxetic acid-enhanced MR images with intraoperative findings

PURPOSE: To evaluate the safety and efficacy of gadoxetic acid disodium-enhanced magnetic resonance (MR) imaging for the detection of focal liver lesions, with results of histopathologic examination and/or intraoperative ultrasonography used as a standard of reference. MATERIALS AND METHODS: One hundred sixty-nine patients who were known to have or suspected of having focal liver lesions and were scheduled for liver surgery were included in this study. Results in 131 patients could be included in the efficacy analysis. MR imaging was performed before and immediately and 20 minutes after bolus injection of 0.025 mmol/kg of the liver-specific hepatobiliary contrast agent gadoxetic acid. T1-weighted gradient-echo (with and without fat saturation and including dynamic data sets) and T2-weighted fast spin-echo/turbo spin-echo sequences were performed. All images were evaluated on site and by three independent and blinded off-site reviewers. Lesion matching based on the standard-of-reference results was performed. Differences in lesion detection with precontrast and with postcontrast MR images were assessed with the two-sided Wilcoxon signed rank test. RESULTS: Gadoxetic acid was well tolerated. In the on-site review, the number of patients in whom all lesions were correctly matched increased from 89 of 129 patients at precontrast MR imaging to 103 of 129 patients at postcontrast MR imaging. In the off-site evaluation, the number of patients in whom all lesions were correctly matched and the corresponding sensitivity values increased from 72 (55.8%), 68 (52.7%), and 66 (51.2%) with the precontrast images to 88 (68.2%), 69 (53.5%), and 76 (58.9%) with the postcontrast images for readers 1, 2, and 3, respectively. Two of the three blinded readers showed a statistically significant difference in lesion detection between precontrast and postcontrast MR imaging (P <.001 and P =.008). A large number of additionally correctly detected and localized lesions were smaller than 1 cm. CONCLUSION: MR imaging with gadoxetic acid is safe and improves lesion detection and localization.     

Meaning and etiopathogenesis of sectorial transient hepatic attenuation differences (THAD)

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

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.     

Detection and characterization of focal hepatic lesions: comparative study of MDCT and gadobenate dimeglumine-enhanced MR imaging

The aim of this study was to compare the diagnostic performance of multidetector row helical CT (MDCT) and gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging (in the detection and characterization of focal liver lesions. Two blind reviewers analyzed the MDCT and MR images of a total of 44 malignant and 85 benign lesions in 46 patients independently. Receiver operating characteristic curves were established to analyze the results for each reviewer and modality.     

Dynamic contrast-enhanced MR imaging and dual-phase helical CT in the preoperative assessment of suspected pancreatic cancer: a comparative study with receiver operating characteristic analysis.

OBJECTIVE: The purpose of this study was to compare dynamic contrast-enhanced MR imaging and dual-phase helical CT in the preoperative assessment of patients with suspected pancreatic carcinoma. SUBJECTS AND METHODS: Thirty-three consecutive surgical candidates (20 men, 13 women; 39-81 years old) were included. MR imaging comprised fast spin-echo (TR/TE 4000/91), fat-suppressed T1-weighted spin-echo (500/15), and T1-weighted breath-hold gradient-echo fast low-angle shot (100/4; flip angle, 80 degrees) images before and after the administration of gadopentetate dimeglumine. Helical CT used 5-mm collimation with a pitch of 1:1.5-1.7; images were obtained 20 and 65-70 sec after injection of 150 ml of contrast material. Two pairs of interpreters who were unaware of the results of the other imaging method independently scored each examination for the presence of a lesion and for surgical resectability using a five-point scale. Results were correlated with surgery (n = 25) or consensus review (n = 8). Receiver operating characteristic methodology was used to analyze the results for resectability, and positive predictive values were calculated. RESULTS: Both MR imaging and helical CT revealed 29 of 31 lesions. In determining lesion resectability, the mean areas under the receiver operating characteristic curves were 0.96 and 0.81 (p = .01) and the positive predictive values were 86.5% and 76% (p = .02) for MR imaging and helical CT, respectively. CONCLUSION: MR imaging and helical CT performed equally well in lesion detection. MR imaging was significantly better in the assessment of resectability of pancreatic tumors.     

Diagnosis and staging of pancreatic cancer: comparison of mangafodipir trisodium-enhanced MR imaging and contrast-enhanced helical hydro-CT

OBJECTIVE: The purpose of this study was to compare mangafodipir trisodium-enhanced MR imaging performed with a phased array coil and contrast-enhanced single-detector helical CT for accuracy in the detection and local staging of pancreatic adenocarcinoma and in the differentiation between cancer and focal pancreatitis. SUBJECTS AND METHODS: Forty-two patients with suspected pancreatic masses underwent contrast-enhanced helical CT and mangafodipir trisodium-enhanced MR imaging at 1.5 T. The images were assessed for the presence or absence of tumors; characterization of masses; and presence of vascular invasion, lymph node metastases, or liver metastases. Imaging findings were correlated with findings at laparotomy, laparoscopy, biopsy, or follow-up. RESULTS: Focal masses were present in 36 patients (cancer, n = 26; focal pancreatitis, n = 7; other, n = 3). The sensitivity for lesion detection of MR imaging was 100% and of CT, 94%. Two small malignant lesions were missed on CT. For the diagnosis of tumor nonresectability, the sensitivity of MR imaging and CT was 90% and 80%, respectively. Liver metastases were missed on MR imaging in one of the eight patients and on CT in four. For differentiation between adenocarcinoma and nonadenocarcinoma, the sensitivity of MR imaging was 100% (positive predictive value, 90%; negative predictive value, 100%), and the sensitivity of CT was 92% (positive predictive value, 80%; negative predictive value, 67%). Receiver operating characteristic analysis revealed that the mean area under the curve for MR imaging was 0.920 and for CT, 0.832 (not significant). CONCLUSION: Mangafodipir trisodium-enhanced MR imaging is as accurate as contrast-enhanced helical CT for the detection and staging of pancreatic cancer but offers improved detection of small pancreatic metastases and of liver metastases compared with CT.     

Value of contrast-enhanced sonography for the characterization of focal hepatic lesions in patients with diffuse liver disease: receiver operating characteristic analysis

OBJECTIVE: Our aim was to assess the diagnostic performance of contrast-enhanced agent detection sonographic imaging to characterize focal hepatic lesions in patients with diffuse liver disease in comparison with baseline sonographic images and to determine whether agent detection imaging can reduce the necessity of further diagnostic workup for lesion characterization. MATERIALS AND METHODS: Contrast-enhanced sonography using 4 g of Levovist at a concentration of 300 mg/mL was performed on 75 focal hepatic lesions in 75 patients with diffuse liver disease. Interval reviews for both baseline without and with contrast-enhanced sonography were performed independently by two radiologists. They were requested to determine the malignity of focal hepatic lesions using a 5-point confidence level and to record the specific diagnoses and the necessity for further imaging for lesion characterization. Radiologists' performances for lesion differentiation using baseline and contrast-enhanced sonography were evaluated using receiver operating characteristic (ROC) analysis. Interobserver agreement was also analyzed. RESULTS: When contrast-enhanced sonography was used, ROC analysis revealed a significant improvement for both reviewers (area under the receiver operating characteristic curve [A(z)] = 0.753 and 0.830 and 0.971 and 0.974 at baseline sonography and contrast-enhanced sonography, respectively; p < 0.002) for differentiating malignant and benign focal liver lesions. Contrast-enhanced sonography also improved specificity from 12% to 91% for reviewer 1 and from 26% to 85% for reviewer 2 compared with baseline sonography. Furthermore, excellent interobserver agreement was achieved for contrast-enhanced sonography (weighted kappa = 0.919), whereas only good agreement was achieved for baseline sonography (weighted kappa = 0.656). A better result for specific diagnosis was obtained by contrast-enhanced sonography (79% and 75%) than by baseline sonography (37% and 48%, p < 0.05). Contrast-enhanced sonography (72% and 63%) outperformed baseline sonography (35% and 28%, p < 0.05) as a confirmatory imaging technique. CONCLUSION: Contrast-enhanced agent detection sonography can be used to characterize focal hepatic lesions in patients with diffuse liver disease reliably and with a higher diagnostic confidence than baseline sonography. Furthermore, contrast-enhanced sonography reduced the need for further diagnostic workups for focal hepatic lesion characterization.     

Characterization of small liver lesions: Added role of MR after MDCT

OBJECTIVE: The purpose of this study is to evaluate the added role of magnetic resonance imaging (MR) in characterizing subcentimeter focal liver lesion(s) detected on multidetector row helical computed tomography (MDCT). MATERIALS AND METHODS: A retrospective analysis was performed in 59 noncirrhotic patients with focal subcentimeter liver lesion(s) detected on a 4- or 16-slice MDCT. All patients had a gadolinium enhanced liver MR on 1.5-T systems within 6 weeks after MDCT. Imaging diagnosis was graded on an ordinal scale of 0-5 (0, normal; 1, definitely benign; and 5, definitely malignant). The final diagnosis was established either by histopathology or follow-up imaging for a period of at least 6 months. Receiver operating characteristic analysis was performed to compare the performances of MDCT and MR in characterization of subcentimeter liver lesions. RESULTS: A total of 178 lesions were detected on MDCT in 59 patients. Of these lesions, 129 (72.5%) lesions were benign and the remaining 49 were malignant. The sensitivity, specificity, positive predictive value, and negative predictive value in differentiation of benign from malignant lesions on MDCT were 81.2%, 77.3%, 60.5%, 90.6 % and on MR were 83.3%, 97.5%, 92.1%, and 94.4 %, respectively. Comparative receiver operating characteristic analysis showed an area under curve for MDCT = 0.76 and MR = 0.95 (P < 0.001). CONCLUSIONS: Liver MR has significantly higher accuracy for characterization of subcentimeter focal liver lesions discovered on MDCT.     

Dual-phase versus single-phase helical CT to detect and assess resectability of pancreatic carcinoma

OBJECTIVE: The aim of this study was to compare dual-phase and single-phase helical CT for the detection and assessment of resectability of pancreatic adenocarcinoma. SUBJECTS AND METHODS: We studied 60 patients (31 men, 29 women; age range, 31-84 years; mean age, 62 years) with suspected pancreatic malignancy. Patients were randomly assigned to one of two groups. For group A (n = 30), unenhanced scans through the liver and pancreas were followed by two separate acquisitions (dual-phase) at 20-25 and at 60-80 sec after IV contrast administration. For group B (n = 30), unenhanced scans were followed by one set of scans (single-phase) acquired caudocranially (from the inferior hepatic margin to the diaphragm) starting 50 sec after IV contrast administration. Two observers independently scored images for the presence of tumor and for assessment of tumor resectability. RESULTS: Comparison of dual-phase versus single-phase helical CT for tumor detection showed a diagnostic accuracy for observer 1 of 87% and 90%, respectively, and for observer 2, of 90% and 87%, respectively. For both helical CT techniques, the overall agreement between the two observers was 83% (kappa = 0.73 +/- 0.03) for single-phase helical CT and 90% (kappa = 0.89 +/- 0.03) for dual-phase helical CT. The assessment of resectability was affected by the low number of resectable tumors (n = 8). CONCLUSION: Single-phase helical CT is effective for the diagnosis and assessment of resectability of patients with suspected pancreatic carcinoma. Advantages are the lower radiation dose and fewer images to film and store.