Assessment of liver tissue after radiofrequency ablation: findings with different imaging procedures.

Our goal was to assess the typical appearance of normal liver tissue immediately after radiofrequency ablation (RF-ablation) when imaged with contrast-enhanced ultrasound, CT, MRI, 18F-FDG PET, and PET/CT. METHODS: Nineteen RF-ablation sessions were performed on nontumorous liver tissue of 10 G?ttingen Mini Pigs. CT, ultrasound, MRI, 18F-FDG PET, and PET/CT were performed immediately after the intervention. All imaging procedures were evaluated qualitatively for areas of increased contrast enhancement (morphologic imaging) and regions of elevated tracer uptake (functional imaging). Images were assessed quantitatively by determination of ratios (r(p/p)) comparing contrast enhancement/tracer uptake in the periphery of the necrosis with contrast enhancement/tracer uptake of normal liver parenchyma. RESULTS: On morphologic imaging, an increase in contrast enhancement surrounding the ablative necrosis was detected in all lesions. Quantification of this area of increased contrast enhancement revealed ratios of r(p/p) = 1.57 +/- 0.2 for CT and r(p/p) = 1.57 +/- 0.19 for MRI. On PET and PET/CT, homogeneous tracer utilization was found surrounding all lesions. There were no areas of a focal or rim-like increase in glucose metabolism. The ratio r(p/p) was found to be 1.05 +/- 0.08 for functional data. Histologic examination revealed pooling of blood in the sinusoids of the lesion's periphery that was caused by outflow obstruction due to the central necrosis. CONCLUSION: On morphologic imaging, a rim-like increase of contrast enhancement was found immediately after RF-ablation resembling peripheral hyperperfusion. This area of contrast enhancement may hamper detection of residual tumor. On the basis of homogeneous tracer distribution surrounding the area of necrosis, PET and PET/CT may serve for early assessment of patients after RF-ablation.     

Solitary hepatic infantile hemangioendothelioma: dynamic gadolinium-enhanced MR imaging findings

We report the MRI findings of a solitary hepatic infantile hemangioendothelioma (IHE) diagnosed in a 14-day-old girl. To the best of our knowledge, only one report has illustrated the dynamic gadolinium-enhanced MR imaging features of IHE previously. Compounding the rarity of presentation as a solitary mass, the gadolinium-enhanced MRI appearance in our case is unique, because the IHE showed an early rim-like pseudocapsular enhancement followed by progressive fill-in of the lesion on delayed imaging.     

Computed tomography, management, and follow-up in infantile hemangioendothelioma of the liver in infants and children

Hepatic hemangioma (hemangioendothelioma) is a rare but most common benign vascular tumor of the pediatric age group. Prompt diagnosis and treatment prevent complications. Familiarity with various CT patterns should facilitate correct diagnosis of hemangioendothelioma of the liver in infants and children and avert angiography.     

螺旋CT双期增强扫描诊断边缘型肝胆管癌

目的 :探讨螺旋CT双期扫描诊断边缘型肝胆管癌的价值。材料和方法 :回顾性分析经病理证实的 16例边缘型肝胆管癌的螺旋CT资料。所有病例均于注药后 3 0 ,65s分别获得肝动脉及门静脉双期图像。结果 :肿块直径 4.2～ 8.0cm ,以边缘不规则的低密度为主。增强扫描 11例于双期出现肿块周边菲薄、不连续的环形增强 ,3例周边厚的连续环形增强 ,1例肝动脉期均匀增强 ,1例无明显增强。 3例肿瘤内见线样分隔 ,12例在肝动脉期及门静脉期无明显差异。结论 :边缘型肝胆管癌的特征性CT表现为肝动脉期及门静脉期菲薄、不连续的环形轻度增强 ,在双时相间变化不明显。     

肝内胆管癌的螺旋CT表现及病理基础(附20例分析)

目的:探讨肝内胆管癌螺旋CT增强扫描表现与病理学的关系,以及螺旋CT的诊断价值。方法:经手术病理证实的20例肝内胆管癌行常规上腹部平扫和增强扫描,增强扫描在注入对比剂后20s和60s分别行动脉期和门静脉期扫描,另有14例加做4～15min的延迟期扫描,分析肝内胆管癌影像特征和病理基础。结果:病灶肿块型16例,浸润狭窄型2例,胆管内生长型2例。增强早期边缘无强化者6例,边缘强化者14例,延迟增强后内部不均匀强化者8例,均匀强化者2例,无强化者4例。病理学上周边强化是由于肿瘤边缘存在活癌组织,而延迟强化是由于肿瘤中心部分存在丰富的纤维组织。此外螺旋CT还清楚显示了肝内胆管扩张,肝叶萎缩,病灶周围异常强化区等间接现象。结论:肝内胆管癌的CT表现与病理密切相关,早期病灶边缘轻度强化,延迟期中心部强化是诊断肝内胆管癌的重要影像依据。     

肝内周围型胆管细胞癌CT和MRI诊断及病理基础研究

目的研究肝内周围型胆管细胞癌(IHPCC)的CT、MRI诊断及其病理基础。方法回顾性分析经病理证实的IHPCC病人32例，29例行CT平扫和增强扫描，5例做了MR检查，2例行MR动态增强扫描。结果CT上病灶呈肿块型18例、浸润狭窄型7例、腔内生长型4例，有3例未见明确肿块。病灶增强早期强化不明显者13例(44．8％)、周边强化者8例(27．6％)；延迟后内部无强化7例(24．1％)、不均匀强化8例(27．6％)、均匀性强化5例(17．2％)。组织病理学上见肿瘤外周以存活的肿瘤细胞为主，形成早期边缘强化，而肿瘤中央以纤维成分为主，是产生延迟强化的病理基础。结论动态增强扫描是诊断IHPCC的关键技术，早期边缘强化、延迟后内部强化是其影像诊断重要依据。     

胆管细胞型肝癌的CT诊断

目的探讨CT增强及延迟扫描诊断胆管细胞型肝癌的价值。方法对21例经病理证实的胆管细胞型肝癌做了CT平扫、增强及延迟扫描。结果CT平扫全部病灶为低密度,其中14例为囊性,7例为实质性且病灶内见胆管扩张。增强扫描14例囊性病变中有10例出现病灶边缘不连续的较薄环形增强,3例连续环行强化,门静脉期13例均无变化;1例无增强表现。7例实质性病变在增强1 m in后病灶轻度强化,3~8 m in后病灶出现延迟增强,密度等于或大于同层肝组织,扩张的胆管无变化。结论CT增强扫描囊性病灶边缘连续或不连续的薄环形强化且门静脉期无变化,实质性病灶延迟强化及病灶内胆管扩张是胆管型肝癌的特征性表现。     

婴儿型肝脏血管内皮瘤的影像诊断

目的 总结婴儿型肝脏血管内皮细胞瘤的临床与影像学表现. 资料与方法 回顾性分析6例婴儿型肝脏血管内皮细胞瘤的临床与影像学表现,所有的病例均经穿刺病理证实.5例行CT扫描,1例行MRI平扫. 结果 CT平扫表现为肝内低密度灶,1例出现钙化,增强扫描动脉期肿瘤均呈不均匀环形强化,4例中央部位出现结节样强化;门静脉期全部病例由周边向中心强化,强化范围扩大;延迟期病灶密度稍高于或等于正常肝实质.1例MR表现为肝内多发结节,T1WI低信号,T2WI高信号,增强扫描动脉期部分结节呈环形强化,部分结节呈全瘤均匀强化,延迟期全部结节呈全瘤强化. 结论 本病的CT与MRI表现有一定的特征性,有助于诊断本病.     

Epithelioid hemangioendothelioma mimicking a nerve sheath tumor clinically and on MR imaging

Epithelioid hemangioendothelioma is a tumor of the soft tissues arising from the vascular endothelium. It is considered an intermediate grade malignancy. A 42-year-old female patient presented with pain and tingling down her right arm and a mass at the right medial upper extremity. MRI revealed an oblong mass along the course of the neurovascular bundle. Given the clinical and MR findings, a nerve sheath tumor was suspected. At surgery, the mass was adherent to both the brachial artery medially and the median nerve posteriorly. Pathology revealed epithelioid hemangioendothelioma. The imaging characteristics of epithelioid hemangioendothelioma on ultrasound, CT, and MRI are reviewed. Epithelioid hemangioendothelioma can mimic a nerve sheath tumor clinically and radiologically and should be considered in the differential diagnosis of tumors involving or adjacent to a neurovascular bundle.     

Comparison of FDG-PET, PET/CT and MRI for follow-up of colorectal liver metastases treated with radiofrequency ablation: initial results

PURPOSE: Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA. METHODS AND MATERIALS: Sixteen patients showed 25 FDG-positive colorectal liver metastases in pre-interventional PET/CT. Post-interventional PET/CT was performed 24h after ablation and was repeated after 1, 3 and 6 months and then every 6 months. PET and PET/CT data were compared with MR data sets acquired within 14 days before or after these time points. Either histological proof by biopsy or resection, or a combination of contrast-enhanced CT at fixed time points and clinical data served as a reference. RESULTS: The 25 metastases showed a mean size of 20mm and were treated with 39 RFA sessions. Ten lesions which developed LTP received a second round of RFA; four lesions received three rounds of treatment. The mean follow-up time was 22 months. Seventy-two PET/CT and 57 MR examinations were performed for follow-up. The accuracy and sensitivity for tumor detection was 86% and 76% for PET alone, 91% and 83% for PET/CT and 92% and 75% for MRI, respectively. CONCLUSIONS: In comparison to PET alone, PET/CT was significantly better for detecting LTP after RFA. There were no significant differences between MRI and PET/CT. These preliminary results, however, need further verification.     

Neuroradiologic characteristics of astroblastoma

Introduction Astroblastoma is a rare glial tumor of uncertain origin. Only a few scattered case reports and one small case series have described the radiologic appearance of this uncommon tumor. Many features previously identified are similar to those of other primary malignant brain tumors. We report the largest imaging series to date and further delineate the CT and MRI features of astroblastoma. We identify those features that may be useful in distinguishing astroblastoma from other neoplasms. Methods The radiologic images, pathology reports, and clinical information of 12 patients with pathology-confirmed astroblastoma were retrospectively reviewed. CT and MRI findings including location, morphology, signal intensity, and presence and patterns of enhancement were tabulated. Results Patients ranged in age from 0 (newborn) to 50 years with a mean of 20 years at the time of initial diagnosis. A striking female preponderance (11:1) was found. All tumors were supratentorial. There were multiple intratumoral cysts in 7 (58%) of the 12 patients. Nine (75%) showed strong rim enhancement and 3 (25%) showed no rim enhancement. Conclusion The imaging features of astroblastoma are identified in 12 previously unreported cases. Distinguishing features that can be used to narrow the differential diagnosis with more common primary brain neoplasms reflect a combination of age, anatomic location, and specific imaging findings such as demarcation, heterogeneous tumor enhancement, rim enhancement, and a multicystic “bubbly” appearance. Intraventricular location, intratumoral hemorrhage with a fluid-fluid level, and dural “tails” are less common but important additions to the imaging spectrum.     

肝癌电磁波热凝治疗消融术后的CT表现分析

目的:分析肝癌电磁波热凝治疗(微波固化或射频消融)后的常见和特殊CT表现,提高对电磁波热凝治疗消融后肝脏形态改变和局部并发症的认识。方法:26例消融治疗后的肝癌患者,术后2周行CT扫描,3个月内复查CT,结合临床症状和实验室检查指标,分析射频消融治疗后肝脏形态的一般变化和出现局部并发症时的特殊征象。结果:电磁波热凝治疗消融后18例病灶呈术后正常改变,CT平扫为边界清楚、均质的低密度区,增强扫描无强化,而坏死区周边可见薄的环形强化,病灶范围较治疗前稍大,随治疗后的时间延长坏死区周边的环形强化逐渐减弱至消失,而中心坏死区仍为低密度,无强化,病灶较前逐渐缩小。消融后复发4例,CT表现为消融治疗区域周边的新发低密度灶。胆道损伤2例,CT表现为消融治疗区域周边肝内胆管扩张。肝内假性囊肿形成1例,CT示消融治疗区旁边缘锐利无强化的囊性灶;皮肤瘘道形成并胸腔积液1例,CT表现为消融治疗的针道不愈合,肝脏内病灶坏死区与体表相连通。结论:CT可准确地反映原发性肝癌电磁波热凝治疗消融后肝脏的形态学改变,有效观察局部并发症的发生情况,有助于提高对电磁波热凝治疗术后征象的认识。     

肝脏上皮样血管内皮瘤的影像学特征

目的：提高对肝脏上皮样血管内皮瘤（EHE）的认识和影像诊断水平。方法：搜集经手术病理证实的5例肝脏上皮样血管内皮瘤患者的CT、MRI和病理学资料,分析和总结其影像学征象。结果：CT平扫示肝脏多个类圆形低密度灶,2例病灶边缘可见条状钙化灶。增强后动脉期主要表现为肿瘤周边轻度强化,延迟后肿瘤实质部分无明显对比剂进入,而中央更低密度区无强化。MRI显示肝内多个类圆形病灶T1WI呈低信号,T2WI呈高信号,病灶边缘有低信号晕环。结论：EHE具有一些特征性的影像学特点,CT和MRI检查能为临床诊断及鉴别诊断提供有价值的信息。     

Contrast-enhanced imaging features and differentiation of benign and malignant focal splenic lesions

To assess the value of imaging features for differentiating malignant from benign focal splenic lesions, 79 pathologically proved cases with contrast-enhanced CT or MRI were retrospectively studied. The morphological characteristics were assessed and the enhancement patterns were classified into five categories. After multivariate logistic analysis, the lesion margin and enhancement patterns were significantly different between benign and malignant lesions. The combination of ill-defined margin and hypovascular enhancement for suggesting malignant lesions had a good specificity (94.9%) and accuracy (89.9%). Morphological and enhancement characteristics on CT/MRI may be valuable in differentiating malignant from benign focal splenic lesions.     

肝细胞癌合并胆管癌栓的影像表现

目的 探讨胆管癌栓的影像表现,以提高影像诊断水平.方法 回顾性分析经手术病理证实的肝细胞癌(HCC)胆管癌栓13例患者资料,其中3例进行了CT和MR检查,2例仅行CT检查,8例仅行MR检查,7例进行了MR胰胆管成像检查,13例均进行了超声检查.采用四格表Fisher 确切概率检验方法比较超声与CT、MR诊断HCC胆管癌栓的准确性.结果 13例HCC肿瘤及胆管癌栓均在CT或MRI上显示.4例胆管癌栓在CT上表现为胆管内软组织块影,动脉期可见癌栓轻度增强,癌栓远端胆管扩张.11例胆管癌栓在T1 WI上均呈稍低信号,T2 WI为稍高信号,增强后可见轻、中度强化.MR胰胆管成像上胆管癌栓表现为:胆管阻塞中断、狭窄或不规则充盈缺损伴有梗阻上方胆管扩张,胆管突然截断或呈"鼠尾"状(5例);肝内胆管扩张,癌栓充满整个胆总管.胆总管不显示(2例).超声检查准确诊断胆管癌栓7例,误、漏诊6例.CT、MRI准确诊断12例,误诊4例,超声与CT、MRI诊断胆管癌栓差异无统计学意义(P=0.270).结论 CT或MRI对诊断HCC合并胆管癌栓及明确癌栓范围有价值.     

Imaging features of low-grade fibromyxoid sarcoma (Evans tumor)

Objective

To determine common imaging features of low-grade fibromyxoid sarcoma (LGFMS), a rare subtype of fibrosarcoma with a benign histological appearance but with a propensity for local recurrence and metastasis.

Materials and methods

By review of medical records, 29 patients (14 males, 15 females) with mean age of 41?years (range, 11–64?years) with diagnosis of LGFMS and imaging available in PACS were identified. The study included radiography (9/29), ultrasound (1/29), CT (14/29), and MRI (22/29). Imaging features evaluated included anatomic site, and lesion size, number, location, US echogenicity, CT attenuation, calcifications, MR signal intensity pattern, and contrast enhancement.

Results

Twenty-two patients had imaging at initial diagnosis, and seven had imaging only at local recurrence. The majority of tumors (27/29) were deep in tissue, with mean size of 6.2?cm (range, 1.4–19.0?cm). Tumor was single at initial diagnosis and multiple at local recurrence; lower extremity was the most common site. On radiographs, tumor was visible in four of nine without bone erosion or calcification. Areas of CT attenuation hypodense to muscle were seen in 13/14 patients. Calcification was uncommon (3/14). On fluid-sensitive MRI sequences, the predominant signal intensity was hyperintense to muscle in 11/21 patients. In 13/21 patients, tumor displayed either a brain gyriform pattern of alternating hypointense and hyperintense signal intensity (9/13) or intralesional nodules (3/13); 1 case had both patterns. On US tumor was solid with heterogeneous echogenicity.

Conclusion

LGFMS is commonly single at initial diagnosis and multiple at local recurrence. LGFMS frequently shows areas of CT attenuation hypodense to muscle and gyriform patterns of signal intensity and contrast enhancement at MRI.     

Multifocal epithelioid hemangioendothelioma of the phalanges of the hand

Epithelioid hemangioendothelioma (EH) of bone is a rare vascular neoplasm characterized by epithelioid endothelial cells and a variable biologic behaviour. The principal sites of occurrence of this osteolytic tumor are the lower extremity and the axial skeleton. Approximately half of the cases present with multifocal disease. The latter feature can be helpful in suggesting the diagnosis of a vascular tumor; on the other hand, it strengthens the need for a skeletal survey or whole-body MRI/CT. We report on the clinical, histologic and radiologic features—including CT and MRI findings—of EH in a case of multifocal disease of the phalanges of the hand, a very uncommon anatomic site of affliction.     

Application of contrast agents in CT and MRI (NMR): their potential in imaging of brain tumors

Summary 21 patients with clinical and CT diagnoses of intracranial tumor were studied by MRI (NMR) prior to and after administration of intravenous Gadolinium-DTPA. Resultant MRI images were compared with corresponding CT sections with respect to lesion detection, contrast enhancement, tumor delineation and visualization of perifocal edema. All intracranial lesions shown on CT were identified on MRI. Contrast enhancement in MRI images was achieved in 19 out of 21 patients, as it was also with CT. In these cases improved differentiation between tumor, perifocal edema and adjacent brain structures were obtained. In most cases sufficient visualization of perifocal edema in MRI required T₂ weighted images (SE 1600/70) in addition to spin echo scans routinely performed prior to and after contrast medium (SE 400/30 or 800/30). No side effects were encountered following administration of Gadolinium-DTPA. The good tolerance and the efficacy justifies the use of Gadolinium-DTPA for contrast enhanced MRI imaging.Dedicated to Professor S. Wende on the occasion of his 60th birthday     

Diagnostic value of magnetic resonance imaging features of microvascular invasion in hepatocellular carcinoma: a meta-analysis

PURPOSEThis systematic review and meta-analysis of conventional enhanced magnetic resonance imaging (MRI) were conducted to evaluate the diagnostic performance of imaging features of microvascular invasion (MVI) prediction in hepatocellular carcinoma (HCC).METHODSRelevant studies on diagnosing MVI in HCC by MRI were searched in the MEDLINE, PUBMED, EMBASE, Cochrane library, and Web of Science databases. The pooled mean sensitivity and specificity were calculated using a random effects model. The corresponding positive likelihood ratio (PLR), negative likelihood ratio (NLR), and pooled diagnostic odds ratio (DOR) were calculated. The summary receiver operating characteristic (SROC) curve was used to summarize the overall diagnostic accuracy. Diagnostic performance was evaluated by determining the area under the curve (AUC). Regression analysis by subgroup and sensitivity analysis were used to explore potential sources of heterogeneity.RESULTSA total of 19 studies comprising 1920 HCC patients with 2033 tumors were ultimately enrolled. For the signs of the presence of peritumoral enhancement in the arterial phase, peritumoral hypointensity in the hepatobiliary phase, irregular non-smooth margin, and rim-like enhancement in the arterial phase, the pooled sensitivity values, the pooled specificity values, the pooled PLR values, the pooled NLR values, the pooled DOR values, and the values of the AUC of SROC curves were determined.CONCLUSIONThe conventional MRI features for predicting MVI showed poor diagnostic performance in HCC. Only signs of the presence of peritumoral enhancement in the arterial phase showed a moderate diagnostic accuracy.

Main points

• We summarized four of the most common magnetic resonance imaging (MRI) signs for microvascular invasion (MVI) in hepatocellular carcinoma (HCC).
• A systematic evaluation of the diagnostic performance was performed to predict MVI in HCC using conventional enhanced MRI (non-functional or radiomics) of each sign.
• The diagnostic performance of conventional enhanced MRI was not good, and all the signs showed low-moderate diagnostic accuracy.

In hepatocellular carcinoma (HCC), microvascular invasion (MVI), which is considered microscopic evidence of cancer embolism in the portal vein or vascular space lined by endothelial cells, is a prognostic factor for poor overall survival and recurrence after hepatectomy or liver transplantation.^1,2 For patients with HCC who underwent curative surgical resection, detection of MVI plays an important role in clinical decision-making. Subsequent treatment approaches, such as postoperative adjuvant transcatheter arterial chemoembolization, are recently recommended for patients with MVI-positive HCC to prevent recurrence and improve the prognosis.^3,4 Unfortunately, with a high positive incidence rate of up to 57%, MVI can only be confirmed by postoperative pathological examination after extensive resection of the tumor,^5,6 which makes it difficult to predict MVI preoperatively.As a non-invasive examination, enhanced magnetic resonance imaging (MRI), especially hepatobiliary-specific contrast-enhanced MRI, is currently used for detecting MVI.⁷ Incomplete tumor capsules, irregular non-smooth margin, rim-like enhancement on the arterial phase, peritumoral enhancement on the arterial phase, and peritumoral hypointensity on the hepatobiliary phase (HBP) are considered as possible radiographic signs for MVI detection.⁸ Rim-like enhancement is defined as the irregular rim-like peripheral hyperintensity area of the tumor with hypointensity area in the center of the tumor on the arterial phase enhancement. Peritumoral enhancement is defined as the variable-shaped hyperintensity area outside the tumor in wide contact with the tumor margin on the arterial phase enhancement and iso-intensity area on the delayed phase. Peritumoral hypointensity is defined as a flame-like or “V-shaped” hypointense area outside the tumor margin on the HBP. Irregular non-smooth margin is defined as an indistinct or irregular tumor margin with a budding portion.⁹ However, the diagnostic performance, with respect to the accuracy, is still controversial. The systematic evaluation of the image prediction of MVI in HCC has been reported in recent studies^10-13 with variable pooled results of diagnostic values. There were obvious methodological differences such as different examination types [computed tomography (CT), ultrasound, MRI, or positron emission tomography/CT (PET/CT)] and confused methodology (conventional MRI or using radiomics) among these studies. In addition, the radiographic signs selection in the MRI subgroup was different, so it is uncertain for comparing the diagnostic performance of the specific image signs on MRI. Therefore, we conducted a systematic review and meta-analysis of conventional enhanced MRI to evaluate the diagnostic performance of imaging features for MVI prediction in HCC.     

原发性肝神经内分泌癌的影像表现

目的 探讨原发性肝神经内分泌癌的CT和MRI表现,提高影像诊断水平.方法 回顾性分析经手术病理证实的6例肝原发性神经内分泌癌患者资料,术前4例行CT平扫及增强扫描,2例行MR平扫及增强扫描.结果6例中肿瘤呈多发1例,表现为1个大肿瘤伴周围多个小结节灶,其余5例均为单发.CT平扫除1例病灶周边可见点状钙化外,均表现为肝内低密度占位,病灶中央见较大范围的不规则更低密度区,边界清晰.肿瘤在MR T1WI表现为不均匀低信号,T2WI表现为略高信号.增强扫描实质部分表现为早期轻中度持续强化,但强化程度有所下降,也可表现为门静脉期和延迟期呈轻度强化,中心更低密度或信号区多无明显强化;周围肝内血管呈受压推移改变,腹腔及后腹膜均未见明显肿大的淋巴结.结论CT和MRI能显示原发性肝神经内分泌癌的特征,在该病的诊断和鉴别诊断中有一定价值.