Surgically staged focal liver lesions: accuracy and reproducibility of dual-phase helical CT for detection and characterization

PURPOSE: To assess the accuracy and reproducibility of dual-phase helical computed tomography (CT) in enabling preoperative detection and characterization of surgically staged focal liver lesions. MATERIALS AND METHODS: Surgically and histopathologically proven liver lesions were evaluated by three experienced CT readers. These lesions were present in 77 patients who underwent dual-phase helical CT. Images were interpreted separately by the three blinded reviewers. Each lesion was graded on a nine-point scale of confidence, with 1 being definitely benign, 9 being definitely malignant, and 5 being indeterminate. The chi2 test was used to determine if the distribution of lesion classifications was different between readers. RESULTS: There was a total of 237 lesions: 73 were benign and 164 were malignant. Sensitivity for lesion detection was 69%, 70%, and 71% for the three reviewers, respectively. Specificity was 91%, 86%, and 90%, and the area under the curve for the alternative-free response receiver operating characteristic curve was 0.84, 0.83, and 0.85, respectively. The difference in the distributions of lesion classification between the three reviewers was not statistically significant (P =.67) as determined by chi2 analysis. CONCLUSION: Dual-phase CT has sensitivity of 69%-71% and high specificity (86%-91%) in enabling the detection and characterization of focal liver lesions. Interpretation is highly reproducible, as there is minimal variation between experienced reviewers.     

Pancreatic carcinoma: MR, MR angiography and dynamic helical CT in the evaluation of vascular invasion

OBJECTIVE: To assess the value of MR angiography in combination with contrast-enhanced MR imaging, and to compare MR imaging including MR angiography with dynamic contrast-enhanced dual phase helical CT in the preoperative assessment of vascular invasion in patients with suspected pancreatic carcinoma. METHODS AND MATERIAL: MR imaging only, MR imaging including MR angiography and dynamic contrast-enhanced dual phase helical CT images of 48 patients who were operated due to suspicion of pancreas cancer were correlated with the surgery results in terms of vascular invasion. Pathologic diagnosis were pancreatic adenocarcinoma in 31 patients of which nine had surgically confirmed vascular invasion. Sensitivity, specificity, predictive values (including 95% confidence intervals) and accuracy of MR imaging only, MR imaging including MR angiography and helical CT were calculated. RESULTS: Sensitivity, specificity, positive and negative predictive values and accuracy were 56, 100, 100, 85, 87%; 67, 100, 100, 88, 90% and 67, 100, 100, 88, 90%, respectively, for MR imaging only, MR imaging including MR angiography and helical CT in the adenocarcinoma group. The corresponding figures in the overall study group were 56, 97, 83, 90, 90%; 67, 97, 86, 93, 92% and 67, 97, 86, 93, 92%. Confidence intervals (95%) showed that the differences in the diagnostic efficacy of the techniques were not statistically significant in the overall study group, but the confidence intervals were undefined in the adenocarcinoma group due to the small sample size. CONCLUSION: Diagnostic efficacy of MR imaging when combined with MR angiography is equal to that of dynamic contrast-enhanced dual phase helical CT in the assessment of vascular invasion of pancreatic tumors.     

Hepatic and vascular enhancement at dual-phase helical CT: comparison of Iobitridol 300 and Iohexol 300 in a prospective randomized study

The purpose of this study was to determine hepatic and vascular enhancement, clinical tolerance, and iconographic quality of Iobitridol (300 mg/ml) at dual-phase helical CT and to compare it with Iohexol (300 mg/ml). One hundred forty-six patients were randomly divided into two groups. Each group received 120 ml of Iohexol (group A) or Iobitridol (group B). Mean enhancement of liver, aorta and portal vein was obtained at the arterial phase and at the portal-venous phase. Overall image quality was assessed by two independent blinded investigators. Adverse reactions were recorded. There were no significant differences in demographic characteristics and distribution of patient intrinsic parameters between the two groups, except for blood pressure but without statistical correlation between the difference in blood pressure and the impact on enhancement measurements. There was no significant difference in clinical tolerance and image quality. Mean liver as well as aortic and portal vein enhancement measurements did not show any significant difference. Iobitridol compares favorably with Iohexol. Both products have similar safety, tolerance, and efficacy. Both contrast media have equivalent blood pool concentration and interstitial compartment diffusion.     

Multidetector helical CT of the liver for tumor detection and characterization

Multidetector-row CT (MDCT) scanners have been recently introduced into clinical practice. Major attributes that are improved are the z-axis coverage speed and the longitudinal resolution. These improvements translate into rapid hepatic imaging and allow new imaging protocols. Thin sections can now be used on a routine basis in single-breath-hold technique. This results in improved lesion detection and the nearly isotropic image acquisition provides high-resolution multiplanar reformations. Furthermore, the ability to scan through the entire liver in 10 s or less allows acquisition of two separate sets of CT images of the liver within the time generally regarded as the hepatic arterial dominant phase in monoslice CT; thus, MDCT may demonstrate three clear separate distinct hepatic circulatory phases with a triple-pass technique. Multidetector-row CT with the improvements in morphological and functional information compared with single-slice CT enables a comprehensive approach to hepatic imaging within a single examination.     

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.     

胰腺癌:多排螺旋CT三期增强及曲面重建的评价

目的探讨多排螺旋CT三期扫描及曲面重建对胰腺癌显示与胰周血管侵犯评价的价值。方法对54例临床怀疑胰腺癌患者采用多排螺旋CT行薄层三期动态增强扫描,其中经手术或临床随访证实23例胰腺癌入选本研究,并采用胰腺期图像沿胰胆管以及胰周主要血管行曲面重建,分析肿瘤在三期图像上显示以及胰周血管受累情况。结果肿瘤于胰腺期图像上与胰腺实质密度差异最大,肿瘤-胰腺CT值差于动脉期、胰腺期及门脉期,分别为28.02±11.13,35.67±11.60和24.52±13.13,胰腺期高于动脉期和门脉期(p<0.01),而动脉期与门脉期差别无统计学意义(p>0.05)。曲面重建能直接显示肿瘤与周围解剖结构的关系以及血管受侵的情况。结合横断位图像,曲面重建共检出64条血管受侵,对6例手术患者血管无受累作出正确评价。结论多排螺旋CT动态增强胰腺期有利于肿瘤显示和胰周血管侵犯的评价。曲面重建可以直观显示肿瘤与周围结构的关系及血管受侵情况,并且能加强与临床医生间的信息传递。     

Pretransplantation diagnosis and staging of hepatocellular carcinoma in patients with cirrhosis: value of dual-phase helical CT

OBJECTIVE: The objective of our study was to prospectively evaluate the results of helical CT in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis undergoing orthotopic liver transplantation. SUBJECTS AND METHODS. Eighty-five patients with cirrhosis were studied preoperatively with biphasic helical CT. Arterial, portal, and equilibrium phase images were obtained after injection of 170 mL of contrast material at 5 mL/sec. The prospective CT interpretation was compared with pathologic results on a lesion-by-lesion basis. RESULTS: Pathologic examination found 85 cases of HCC in 51 patients. Helical CT enabled a correct diagnosis of HCC in 67 of 85 lesions for a sensitivity of 78.8%. HCC nodules were hypervascular in the arterial phase and hypovascular in the equilibrium phase in 63.5% (54/85) of patients. The false-negative rate was 21% (n = 18), and the positive predictive value was 88%. We had nine false-positive findings (11.8%) related to hemangiomas, transient hepatic attenuation differences, and regenerative nodules. Helical CT detected 61% (23/38) of lesions smaller than 2 cm and 93.6% (44/47) of lesions 2 cm or larger. CONCLUSION: Helical CT is a useful preoperative imaging technique in cirrhotic patients who are candidates for orthotopic liver transplantation, although it is relatively insensitive for detection of small lesions (< 2 cm).     

Detection of hepatocellular carcinoma: value of adding delayed phase imaging to dual-phase helical CT

OBJECTIVE: The purpose of the study was to compare power Doppler sonography with intraarterial CO(2)-enhanced sonography for revealing vascularity in treated and untreated hepatic tumors. SUBJECTS AND METHODS: Fifty-five patients with 93 liver tumors were prospectively examined with power Doppler sonography and CO(2)-enhanced sonography. These tumors included 29 hepatocellular carcinomas in patients with no previous treatment, 26 treated hepatocellular carcinomas, and 38 hemangiomas. The vascular depiction of power Doppler sonography was compared with that obtained in the early phase of CO(2)-enhanced sonography. The results of angiography were also recorded for comparison. RESULTS: In the hepatocellular carcinomas, power Doppler sonography was the same as CO(2)-enhanced sonography in 18 (62%) of 29 tumors, was inferior to CO(2)-enhanced sonography in nine (31%) of 29 tumors, and was superior to CO(2)-enhanced sonography in two (7%) of 29 tumors. In the treated hepatocellular carcinomas, power Doppler sonography was the same as CO(2)-enhanced sonography in 15 (58%) of 26 tumors and was inferior in 11 (42%) of 26 tumors. In hemangiomas, the same vascularity was found in both studies in 15 (39%) of 38 tumors, CO(2)-enhanced sonography was superior in 22 (58%) of 38 tumors, and power Doppler sonography was superior in one (3%) of 38 tumors. As a whole, 45% of the 93 tumors showed better vascular depiction on CO(2)-enhanced sonography. However, 19.4% of tumors were hypovascular using power Doppler sonography but hypervascular using CO(2)-enhanced sonography. CONCLUSION: Power Doppler sonography is a useful technique for screening hepatic tumor vascularity. CO(2)-enhanced sonography is superior to power Doppler sonography in depicting tumor vascularity in treated hepatocellular carcinomas and in hemangiomas, especially small hemangiomas.     

Using thoracic helical CT to assess iodine concentration in a small volume of nonionic contrast medium during vascular opacification: a prospective study

OBJECTIVE: The goal of the study was to assess whether, using thoracic helical CT, diagnostic mediastinal and hilar vascular enhancement can be obtained with a small amount of nonionic contrast material (80 ml) injected at a relatively slow rate (2 ml/sec). SUBJECTS AND METHODS: One hundred twenty patients (60 in their fourth decade of life and 60 in their seventh decade of life) referred for contrast-enhanced thoracic CT for malignancies or infections prospectively entered the study. They were randomly assigned to be given one of three iodine concentrations of a nonionic contrast material: 250 mg/ml (1250), 300 mg/ml (1300), and 350 mg/ml (1350). Two radiologists independently graded perivenous artifacts and arterial enhancement of mediastinal and hilar vessels on a 4-point scale: 1, poor; 2, fair; 3, good; and 4, excellent. Measurements of arterial attenuation values (quantitative assessment) were obtained on the aorta and pulmonary artery. RESULTS: Mean scores were equal to or greater than 3 for all vessels only using 1350. The higher the iodine concentration was, the higher the mean score, but there was a statistically significant difference only between scores obtained with 1350 and those obtained with 1300 or 1250. Mean scores were higher for the patients in their seventh decade of life than those in their fourth decade; however, there was no statistically significant difference between scores of the two decade groups. We found a highly significant statistical relationship between scores and arterial attenuation values. CONCLUSION: During contrast-enhanced helical CT examinations for general thoracic evaluations, good opacification of central vascular structures is obtained with a low volume of high iodine concentration nonionic contrast medium.     

The role of dual-phase helical CT in assessing resectability of carcinoma of the gallbladder

Our objective was to assess the ability of dual-phase helical CT (DHCT) to predict resectability of carcinoma of gallbladder (CaGB). Thirty-two consecutive patients suspected of having CaGB on clinical examination and sonography presented to our centre over 10-month period. All these 32 patients underwent DHCT. Fifteen patients were considered inoperable and 2 had xanthogranulomatous cholecystitis. The remaining 15 patients (10 women, 5 men; age range 33-72 years) underwent surgery and had histopathological confirmation of CaGB and were included in the study based on the following criteria: presence of mass in gallbladder fossa on sonography and DHCT, and confirmation at surgery and histopathological examination. Axial reconstructions of 2 mm were obtained (collimation 3 mm, table speed 4.5 mm/s) for arterial (scan delay 20 s) and venous (scan delay 60 s) phases on a helical scanner. The criteria used for unresectability were: distant metastasis (liver, peritoneum, lymph nodes), extensive local contiguous organ spread, involvement of secondary biliary confluence of both lobes of liver, tumoral invasion of main portal vein, or proper hepatic artery or simultaneous invasion of one side hepatic artery and the other side portal vein. The CT findings related to unresectability were correlated with surgical findings. On the basis of CT findings, 10 patients were unresectable and 5 were resectable. Of the 10 patients considered unresectable, 9 had tumours that were unresectable at surgery (sensitivity 100%, positive predictive value 90%). Five patients had more than one reason and 4 had one reason alone for being unresectable (lymph nodes, n=2; hepatic metastasis, n=1; and vascular invasion, n=1). All 5 patients considered resectable based on CT findings had resectable tumours at surgery (negative predictive value 100%). The overall accuracy of CT was 93.3%. Dual-phase helical CT comprehensively evaluates CaGB and may be a useful tool in preoperative staging of this tumour in determining resectability.     

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.     

Bladder cancer: analysis of multi-detector row helical CT enhancement pattern and accuracy in tumor detection and perivesical staging

PURPOSE: To evaluate the enhancement pattern of bladder cancer and the accuracy of multi-detector row helical computed tomography (CT) in the detection and staging of bladder cancer. MATERIALS AND METHODS: In 20 patients, the attenuation value of bladder cancer was measured on dynamic contrast material-enhanced multiphasic CT images obtained with scanning delays of 40, 60, 80, and 100 seconds. In 67 patients, CT data were obtained with a 60-second scanning delay that covered the bladder (section thickness, 2.5 mm; beam pitch, 1.5) and a 180-second scanning delay that covered the abdomen (section thickness, 5 mm; beam pitch, 1.5). We prospectively evaluated CT images and compared findings at CT with findings at histologic examination. We evaluated cancer detection rate, positive predictive value of cancer detection, and sensitivity and specificity in the diagnosis of perivesical invasion. RESULTS: The attenuation value of bladder cancers was significantly higher on 60- (105 HU +/- 16) and 80-second (97 HU +/- 15) delayed CT images than on the other images (P <.05). The cancer detection rate and positive predictive value for cancer detection were 97% and 95%, respectively, in 67 patients and increased to 100% and 100%, respectively, in 44 patients with a time interval of 7 or more days between transurethral resection of the bladder (TURB) and CT examination. Sensitivity and specificity in the diagnosis of perivesical invasion were 89% and 95%, respectively, in 67 patients and increased to 92% and 98%, respectively, in 44 patients with a time interval of 7 or more days between TURB and CT examination. CONCLUSION: Bladder cancer tends to show peak enhancement with the 60-second scanning delay. Multi-detector row helical CT is useful in the detection and staging of bladder cancer.     

胃间质瘤的MSCT征象与其危险度评估的对照分析

目的:探讨胃间质瘤(GIST)的MS CT征象与其危险度评估的关系.方法:回顾性分析21例GIST的临床、影像及病理资料.结果:21例中,极低危险度3例,低危险度9例,中危险度2例,高危险度7例.CT能明确肿瘤部位.极低危险度和低危险度的GIST肿瘤直径＜5 cm,形态规则,腔内生长,密度均匀,强化均匀;中危险度的GIST肿瘤直径＞5 cm,形态规则,密度较均匀;高危险度的GIST病灶直径多＞5 cm,多呈腔内外生长,形态不规则,密度不均匀,坏死区无强化.结论:CT扫描能清楚显示GIST的发生部位、肿块大小、形态、密度及生长方式,对GIST的定位、定性诊断有较高价值.