菲立磁增强MRI在肝脏局灶性病变诊断中的价值

目的 评价菲立磁增强MRI在肝脏实性占位性病变诊断中的应用价值。材料与方法 对21例怀疑有肝脏局灶性占位病变患者行MR平行及菲立磁增强MRI检查。扫描序列包括频率选择脂肪抑制及非脂肪抑制ASTE T2WI、True FISP T2WI、频率选择脂肪抑制FLASH T1WI。比较增强前后T2WI及T2WI病灶及肝脏的信噪比（SNR）及对比噪声比（CNR）;观察增强前后病灶数量及形态;结合MR平扫及增强MRI表现进行定性诊断。结果 菲立磁增强T2WI及T2WI肝脏信号强度较平扫明显下降,病灶与肝脏的CNR较平扫明显提高,差异具有统计学意义。结论 菲立磁增强T2WI及T2WI可明显提高肝脏实性占位性病灶的检出率。菲立磁增强T1WI在脏局灶性病变的定性诊断中具有潜在价值,有待于进一步开发与研究。     

菲立磁增强MRI检测肝脏占位病变与三期动态增强CT扫描的比较研究

目的　比较菲立磁增强MRI和增强CT扫描在肝脏实性占位病变检测中的应用价值。方法　对 18例肝内局灶性占位患者行MR平扫及菲立磁增强扫描。观察肝脏与病灶信号强度变化 ,形态及数目 ,比较增强前后T2 WI病灶及肝脏的信噪比 (SNR)及对比噪声比 (CNR) ,做出MRI定性诊断 ,并与增强CT扫描诊断进行比较。其中肝细胞肝癌 4例 ,复发性肝癌 4例 ,转移瘤 4例 ,肝血管瘤 6例。结果　菲立磁增强明显降低正常肝组织信号强度 ,而恶性肿瘤的信号强度无强化 ,病灶—肝脏信噪比增加可清晰显示病变 ,并发现新病灶。肝血管瘤的血池效应与增强CT扫描比较有鉴别诊断意义。结论　做为增强CT扫描和Gd -DTPAMR增强的补充方法 ,SPIO增强MRI对肝脏占位病变的显示 ,小病灶发现和定性诊断中有重要的临床意义     

肝脏发育不良结节癌变的CT、MRI评价

目的 探求肝脏发育不良结节(dysplastic nodule，DN)癌变的CT、MRI特点，提高对：DN癌变的诊断水平。方法 对11例13个经病理证实的DN癌变灶的影像学资料进行回顾性分析，所有病例接受螺旋CT三期增强扫描、MR平扫及MR动态增加扫描，2例接受枯否细胞特异性对比剂菲立磁增强扫描，1例接受肝细胞特异性对比剂钆贝酸葡甲胺(Gd-BOPTA)增强扫描。结果 MR平扫及动态增强扫描检出10个DN癌变病灶，而螺旋CT增强扫描仅检出6个病灶。在T1WI上，6个病灶表现为略高信号，2个病灶为略低信号，5个病灶因等信号未检出；在T2WI上，3个病灶为略高信号，4个病灶表现为“结节中结节”，3个病灶为略低信号，3个病灶因等信号而未检出。在MR动态增强扫描动脉期10个病灶有明显动脉血供增加。2个病灶摄取菲立磁的能力降低，1个病灶摄取对比剂的能力降低。结论 对于DN癌变灶的检出，MR优于螺旋CT。MR可以作为DN癌变检出和鉴别诊断的首选影像学方法。     

多层螺旋CT与钆贝葡胺增强MRI对肝癌诊断价值比较

目的 比较多层螺旋CT与钆贝葡胺（Gd-BOPTA）增强MRI对肝癌的诊断价值。资料与方法 对19例同组患者依次行多层螺旋CT双期增强扫描、MR平扫及Gd-BOPTA动态、延迟扫描。比较多层螺旋CT动态增强扫描、MR平扫＋Gd-BOPTA动态扫描及联合MRI3种方法病灶检出的敏感性及对肝癌病灶定性诊断的敏感性、特异性和准确性。结果 3组病灶检出的敏感性及对肝癌病灶诊断的准确性以联合MRI组较高,差异有统计学意义。结论 Gd-BOPTA增强MRI对病灶检出的敏感性及肝癌病灶诊断的准确性优于多层螺旋CT。     

超顺磁性氧化铁诊断肝脏小病灶的临床应用价值初探

目的：探讨超顺磁性氧化铁（商品名为菲立磁,Feridex)对肝脏小病灶的临床应用价值,以及滴注后的最佳扫描时间。方法：17例经B超或CT检查发现肝脏内小病灶患者,经常规MR平扫和增强扫描1－3d后,经静脉滴注菲立 （0.05ml/kg),并于0.5,3.6h后进行扫描。主观目测菲立磁增强后肝脏小病灶的显示情况,定量分析菲立磁增强后肝脏信号下降情况。结果;菲立磁增强后扫描可显著肝脏内直径小于1cm的病灶21个,明显多于常规MR检查（8个）。菲立磁应用后小肝癌和容易与肝癌混淆的局灶性结节增生和再生结节信号变化明显不同。菲立磁增强后扫描,肝脏T2WI,T1WI信号均较增强前下降（P＜0．01）,滴注菲立磁后0.5,3,6h扫描,T2WI各时间点的脏脏信号下降统计学上差异无显著性意义（P＞0．05）。结论：菲立磁能显著提高肝脏小病灶的检出率,而且对肝脏小病灶的鉴别诊断可提供有利的依据。     

菲立磁增强磁共振成像在肝脏疾病诊断中的价值

目的　评价菲立磁增强MRI在肝脏疾病诊断中的应用价值。方法　对 31例经CT或MRI检查确定或怀疑有肝脏病变者进一步行菲立磁增强MRI检查 ,分别测量增强前后肝脏、病变及背景噪声的T2 WI信号强度 ,计算增强前后肝脏及病变的信噪比(SNR)、对比噪声比 (CNR)。分析平扫及增强后扫描检测的病灶数目。结果　菲立磁增强后肝脏的SNR明显降低 (Ρ <0 .0 1) ;恶性病灶的SNR变化不明显 (Ρ >0 .0 5 ) ;病灶 -肝脏CNR明显增高 (Ρ <0 .0 1)。增强后病变的检出数量增加 ( χ2 =8.5 7,Ρ <0 .0 1)。结论　菲立磁能显著提高肝脏恶性肿瘤的检出率 ,而且对肝脏小病灶的鉴别诊断提供有利的依据     

菲立磁增强MRI对肝脏局灶性病变诊断的临床意义初探

目的　探讨菲立磁增强MRI检查对肝脏局灶性病变的诊断价值。方法　对 2 4例经CT和MRI检查确定或怀疑有肝脏病变者 ,进行菲立磁增强MRI检查 ,包括原发性肝癌 6例 ,肝转移瘤 7例 ,肝血管瘤 3例 ,肝硬化 5例 ,肝囊肿 1例和肝局灶增生结节 2例。全部病例均经手术、病理证实。分别测量增强前、后肝脏病变及背景噪声的信号强度 ,计算病灶 -肝脏背景信号强度对比值。结果　菲立磁增强后 ,①所有病例肝脏背景信号均明显减低 (Ρ <0 .0 1) ;② 4例原发性肝癌 ,3例肝转移瘤 ,2例肝硬化病人发现了更多的病灶 ;③病灶 -肝脏背景信号强度对比值测量中发现 ,原发性肝癌、肝转移瘤对比值明显升高 (Ρ <0 .0 1) ,肝血管瘤对比值降低(Ρ <0 .0 5 ) ,而肝硬化结节则无明显变化。结论　菲立磁增强MRI检查对肝局灶性病变的检出及定性诊断具有一定的临床意义     

菲立磁增强MRI检测肝脏局灶性病变的初步报告

目的 探讨菲立磁增强磁共振在肝脏局灶性病变中的诊断价值。材料与方法 对21例怀疑肝脏肿瘤的患者进行常规肝脏平扫和菲立磁增强扫描,分析增强前后T2WI检测病灶数目以及肝脏、病灶、脾脏信号强度的变化。结果 菲立磁增强明显降低正常肝脏的信号强度、而病灶的信号强度无明显变化,病灶－肝脏的信号强度比增加;菲立磁增强可清晰地显示病变并可发现更多的病变。结论 菲立磁增强在检测肝脏局灶性病变中敏感性高。     

肝转移瘤高场MRI诊断

目的:探讨高场MRI在肝转移瘤(HMs)中的检出、诊断与鉴别诊断价值。方法:收集经临床、影像证实的HMs 43例,所有病例均进行高场MRI平扫和动脉期、门脉期、延迟期扫描,其中23例尚做螺旋CT平扫、动脉期、门脉期扫描,分析记录HMs螺旋CT、高场MRI平扫及多期增强扫描特征。结果:共计174枚瘤灶在MRI平扫上呈长T2长T1信号,动脉期122枚瘤灶不强化,门脉期174枚瘤灶均呈环状强化,延迟期108枚瘤灶呈向心性充填;23例79枚瘤灶螺旋CT平扫均呈低密度,动脉期49枚瘤灶不强化,30枚呈环状强化,门脉期73枚呈环状强化,4枚呈向心性充填;43例HMs高场MRI均准确诊断,螺旋CT漏检2例,误诊7例。结论:高场MRI对HMs的检出、诊断与鉴别诊断具重要价值,可作为HMs的首选检查方法。     

肝脏局灶性结节增生的螺旋CT诊断

目的探讨肝脏局灶性结节增生的螺旋CT影像表现,旨在提高对该病的诊断准确性。方法经手术病理证实的肝脏局灶性结节增生19例均经螺旋CT平扫与增强扫描,对其影像特征回顾性分析。结果肝脏局灶性结节增生多发生于青壮年患者,主要分布在肝脏表面,病变边界清晰,动态增强肝动脉期病灶总体显著强化,病灶内见点状、小星状、大片放射状低密度中央瘢痕影,其中大片放射状中央瘢痕延时扫描可见轻度-中度强化。结论螺旋CT动态增强扫描对肝脏局灶性结节增生的定性诊断有较高价值。     

Preoperative detection of malignant hepatic tumors: comparison of combined methods of MR imaging with combined methods of CT

OBJECTIVE: We compared radiologists' performance on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging with their performance on helical CT during arterial portography (CTAP) and biphasic CT during hepatic arteriography (CTHA) for the preoperative detection of malignant hepatic tumors. SUBJECTS AND METHODS: MR images and CT scans obtained in 33 patients were retrospectively analyzed. Images of the liver were reviewed on a segment-by-segment basis; a total of 261 segments with 39 hepatocellular carcinomas and 21 metastases were independently reviewed by three radiologists who were invited from outside institutions. Unenhanced and gadolinium-enhanced MR images were reviewed first, then ferumoxides-enhanced MR images were added for combined review. CTAP images and biphasic CTHA images were reviewed together. RESULTS: Sensitivity for the detection of hepatic tumors was analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images (86%) and for combined CTAP images and biphasic CTHA images (87%). Specificity was higher with MR images (95%, p < 0.01) than with CT images (91%). Radiologists' performances were improved (Az = 0.962, p = 0.0502) by combining ferumoxides-enhanced MR images with unenhanced and gadolinium-enhanced MR images (Az = 0.950), and were analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images and for combined CTAP images and biphasic CTHA images (Az = 0.959). CONCLUSION: Radiologists' performances on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging compared with their performances on combined helical CTAP and biphasic CTHA are analogous for the preoperative detection of malignant hepatic tumors. Such a dedicated combination of MR imaging may obviate the need for more invasive angiographically assisted helical CT for the preoperative detection of malignant hepatic tumors.     

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.     

Hepatic lesion detection and characterization: value of nonenhanced MR imaging, superparamagnetic iron oxide-enhanced MR imaging, and spiral CT-ROC analysis

PURPOSE: To determine the accuracy for detection and characterization of focal hepatic lesions of nonenhanced, superparamagnetic iron oxide (SPIO)-enhanced, or a combination of nonenhanced and SPIO-enhanced MR imaging and contrast-enhanced spiral computed tomography (CT). MATERIALS AND METHODS: Spiral CT and T2-weighted SPIO-enhanced (ferucarbotran-enhanced) MR imaging were performed in 35 patients within 2 weeks before surgery for malignant hepatic lesions. Only malignant lesions with histopathologic proof were considered. A total of 875 images with and 800 images without focal lesions were presented to five readers, who were asked to assess the presence and characterization of lesions by using a five-point confidence scale. Receiver operating characteristic analysis was performed. RESULTS: Nonenhanced and SPIO-enhanced images together and SPIO-enhanced images alone yielded the best performance for lesion detection. No differences were found among all imaging techniques with regard to lesion characterization (benign vs malignant). The combined approach resulted in larger area under the ROC curve (A(z) = 0.9062) and accuracy (85.3%) (P < 0.02), as compared with SPIO-enhanced MR imaging (A(z) = 0.8667; accuracy, 73.1%). CONCLUSION: SPIO-enhanced T2-weighted MR imaging was more accurate than nonenhanced T1-weighted and T2-weighted MR imaging and contrast-enhanced spiral CT for the detection of focal hepatic lesions. The combined analysis of nonenhanced and SPIO-enhanced images was more accurate in the characterization of focal hepatic lesions than was review of SPIO-enhanced images alone.     

Evaluation of the accuracy of gadobenate dimeglumine-enhanced MR imaging in the detection and characterization of focal liver lesions

OBJECTIVE. We evaluated the extent to which hepatic lesion characterization and detection is improved by using gadobenate dimeglumine for enhancement of MR images. MATERIALS AND METHODS. Eighty-six patients were imaged before gadobenate dimeglumine administration, immediately after the 2 mL/sec bolus administration of a 0.05 mmol/kg dose (dynamic imaging), and at 60-120 min after the IV infusion at 10 mL/min of a further 0.05 nmol/kg dose (delayed imaging). The accuracy for lesion characterization was assessed for a total of 107 lesions. Sensitivity for lesion detection was assessed for a total of 149 lesions detected on either intra-operative sonography, iodized oil CT, CT during arterial portography, or follow-up contrast-enhanced CT as the gold standard. RESULTS. The accuracy in differentiating benign from malignant liver lesions increased from 75% and 82% (the findings of two observers) on unenhanced images alone, to 89% and 80% on dynamic images alone (p<0.001, p = 0.8), and to 90.7% when combining the unenhanced and dynamic image sets (p<0.001, p = 0.023). Delayed images did not further improve accuracy (90% and 91%; p = 0.002, p< 0.05). A similar trend was apparent in terms of accuracy for specific diagnosis: values ranged from 49% and 62% on unenhanced images alone, to 76% and 70% on combined unenhanced and dynamic images (p<0.001, p = 0.06), and to 75% and 70% on inclusion of delayed images (p<0.001, p = 0.12). The sensitivity for lesion detection increased from 77% and 81% on unenhanced images alone, to 87% and 85% on combined unenhanced and dynamic images (p = 0.001, p = 0.267), and to 92% and 89% when all images were considered (p<0.001, p = 0.01). CONCLUSION. Contrast-enhanced dynamic MR imaging with gadobenate dimeglumine significantly increases sensitivity and accuracy over unenhanced imaging for the characterization of focal hepatic lesions, and delayed MR imaging contributes to the improved detection of lesions.     

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.     

Detection of hepatic metastases: comparison of contrast-enhanced CT, unenhanced MR imaging, and iron oxide-enhanced MR imaging

Diagnostic accuracy of contrast-enhanced CT, unenhanced MR imaging, and MR images enhanced with superparamagnetic iron oxide was evaluated in 10 patients with histologically proved hepatic metastases. First, diagnostic performance of the imaging technique with respect to the ability of radiologists to recognize the presence or absence of a metastasis was measured by using receiver-operating-characteristic (ROC) analysis of single images. Second, the total number of lesions (N = 108) detected by "complete" CT and MR examinations was counted. Finally, lesion-liver contrast-to-noise ratios (CNR) were measured in all MR sequences. The area under the ROC curve was .67 +/- .03 for contrast-enhanced CT, .81 +/- .07 for the unenhanced SE 260/14 sequence, and .92 +/- .01 for the iron oxide-enhanced SE 1500/40 sequence. The enhanced SE 1500/40 sequence yielded significantly (p less than .005) greater accuracy than did contrast-enhanced CT. The same sequence detected significantly (p less than .05) more lesions than all other imaging techniques (19% more than the best unenhanced MR sequence and 36% more than contrast-enhanced CT). The enhanced SE 1500/40 sequence also yielded the highest CNR value (19.5 +/- 10.2) of all MR sequences. These results indicate that iron oxide-enhanced MR imaging is a superior imaging technique for the detection of hepatic lesions.     

Hepatic arterial and portal venous phase helical CT in patients treated with transcatheter arterial chemoembolization for hepatocellular carcinoma: added value of unenhanced images

PURPOSE: To evaluate the additional diagnostic value of unenhanced computed tomographic (CT) images in the depiction of viable tumor in patients who were treated with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) and followed up with biphasic helical CT that included the acquisition of unenhanced images. MATERIALS AND METHODS: We performed helical CT (with unenhanced, arterial, and portal phases) in 54 patients who had been treated with TACE for HCC. Image analysis was first performed with only those images obtained in the arterial and portal venous phases of helical CT. A second analysis was then performed with unenhanced images, arterial images, and portal venous images that focused on the additional value of unenhanced images. The value of additional unenhanced images was evaluated by means of interobserver agreement (kappa statistic) and receiver operating characteristic (ROC) analysis. RESULTS: The two readers detected 128 and 129 lesions. Unenhanced images were valuable for 32 of 129 lesions (23 patients) for reader 1 and for 29 of 128 lesions (21 patients) for reader 2. Although there was no significant difference between biphasic CT alone and biphasic CT with unenhanced images, results of ROC analysis showed higher diagnostic performance with biphasic CT with unenhanced images than with biphasic CT alone for detecting viable tumor. CONCLUSION: The study data demonstrate the diagnostic value of unenhanced images interpreted in conjunction with biphasic CT images for follow-up of patients who have previously been treated with TACE for HCC.     

Efficacy and safety of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. Multicenter phase III clinical trials. Efficacy of early imaging

The efficacy of contrast-enhanced magnetic resonance imaging (MRI) for detecting and characterizing, or excluding, hepatic masses was assessed in 404 patients, following the intravenous administration of mangafodipir trisodium (MnDPDP) injection, a hepatic MRI contrast agent. An initial contrast-enhanced computed tomography (CT) examination was followed by unenhanced MRI, injection of MnDPDP (5 micromol/kg IV), and enhanced MRI at 15 minutes post injection. Agreement of the radiologic diagnoses with the patients' final diagnoses was higher for enhanced MRI and for the combined unenhanced and enhanced MRI evaluations than for unenhanced MRI alone or enhanced CT using the clinical diagnosis as the gold standard. Mangafodipir-enhanced MRI uniquely provided additional diagnostic information in 48% of the patients, and patient management was consequently altered in 6% of the patients. MnDPDP-enhanced MRI was comparable or superior to unenhanced MRI and enhanced CT for the detection, classification, and diagnosis of focal liver lesions in patients with known or suspected focal liver disease.     

Benign hepatic tumors: MRI features before and after administration of superparamagnetic contrast media

PURPOSE: To assess the yield of superparamagnetic iron oxide (SPIO)-enhanced MR images in the detection and characterization of benign hepatic tumors and to evaluate the potential role and safety of SPIO administration in the diagnosis of these tumors. MATERIAL AND METHODS: Eighteen patients underwent MRI before and after administration of SPIO particles. Spin echo (SE) T1, DP, T2 and Gradient echo (GE) T2* images were acquired with a.5 T superconductive unit. MR diagnosis was bioptically proved in 12 patients. In the remaining six patients, who had hemangiomas only, diagnosis was confirmed by at least two imaging techniques-such as MR, CT, ultrasonography, radio-labeled red cells scintigraphy-and by both clinical and imaging follow-up. RESULTS: Thirthy-four tumors were detected on the MR images: 29/34 (85,3%) before and 33/34 (97%) after SPIO administration - 6 focal nodular hyperplasias (FNH), 6 adenomas and 22 hemangiomas. One small tumor (adenoma) was detected on the unenhanced MR images only, while 4 lesions (3 adenomas, 1 FNH) were detected after SPIO administration only. DISCUSSION: SPIO-enhanced MRI increased the detection rate of benign hepatic tumors compared to non-enhanced MRI. Iron oxide was also useful in the characterization of such lesions as it was able to demonstrate any heterogeneity resulting from the presence of central scars or septa. Nevertheless, in our experience it was useful to compare baseline with SPIO-enhanced MRI, even if time consuming. Indeed the uptake of iron oxide particles by well-differentiated lesions and normal hepatic parenchyma, is comparable, so that well-differentiated lesions appear isointense and therefore undetectable. CONCLUSIONS: In our experience, although numerically limited, SPIO-enhanced MRI was clinically safe and more effective than non-enhanced MRI in both the detection and characterization of benign hepatic tumors, providing useful clues for diagnosis.