肝结核瘤的MRI征象

目的 分析肝结核瘤的MRI表现，探讨MRI在鉴别诊断中的价值。资料与方法 10例肝结核瘤患者行MR自旋回波序列T1WI、T2WI和快速多层面干扰梯度回波序列动态增强扫描。结果 10例共12个病灶，MRI表现：（1）自旋回波序列：T1WT上所有病灶为低信号，T2WI上10个病灶为不均匀低信号（8个病灶为中心低信号而边缘为环形或片状的高信号，2个为低信号中见到点状高信号），另2个病灶为高信号。（2）增强扫描：动脉期10个病灶无强化,2个病灶边缘有轻度强化。门脉期和延迟期所有病灶均有不同方式的强化，主要为边缘强化和分隔强化。结论 MRI可反映肝结核瘤的病理改变过程，在诊断和鉴别诊断中有重要价值。     

肝胆管囊腺瘤的影像学表现

目的 探讨肝胆管囊腺瘤CT、MRI及B超表现,提高其诊断准确率.方法 回顾性分析9例经病理证实的肝胆管囊腺瘤患者,螺旋CT检查7例,MRI检查4例,B超检查5例.结果 7例患者CT平扫表现为多房囊性病变,囊内可见线状分隔,囊壁均匀增厚,壁光滑;MRI检查4例患者中,病变T1WI呈低信号多房囊性占位,T2WI病灶呈高信号为主混杂信号,囊内分隔呈低信号,增强后动脉期囊壁及分隔轻度强化,门脉期及延迟期继续强化.B超检查5例患者表现为肝内无回声暗区,边界清楚,内见多条强回声带,可见分隔或乳头状隆起.结论 平扫加动态增强CT、MRI及B超能够特征性反映肝胆管囊腺瘤的影像学特点,提高该疾病的诊断准确率.     

肝脏局灶性结节增生的MRI征象分析

目的:探讨肝局灶性结节增生(FNH)的典型及不典型MRI表现及与病理特点的相关性,提高FNH诊断的准确性。方法:回顾性分析33例(共40个病灶)经手术病理证实的FNH的MRI平扫和增强表现。结果:28例为单发,5例为多发病灶。40个病灶在T1WI呈等或稍低信号,在T2WI呈等或稍低信号,增强扫描动脉期31个病灶(94%)明显强化,门脉期及延迟期呈稍高或等信号;1例动脉期未见明显强化,门脉期及延迟期可见强化;1例动脉期边缘明显强化,门脉期及延迟期逐渐强化。12个病灶(30%)中心可见纤维瘢痕,11个延迟期强化,1个未见明显强化。3个病灶(8%)边缘见假包膜,延迟期可见强化。结论:MRI能较好地反映FNH内部组织学情况及血供特点,充分认识FNH的典型征象及不典型表现能帮助我们准备地做出诊断,从而避免不必要的活检及手术。     

肝脏上皮样血管内皮瘤的CT和MRI表现

目的 总结肝脏上皮样血管内皮瘤(HEHE)的CT和MRI表现.方法 搜集经手术或穿刺活检后病理证实的HEHE 11例,所有的病例均行CT检查,其中5例行CT平扫及双期增强扫描(动脉期+门静脉期),其他6例行CT平扫及三期增强扫描(动脉期+门静脉期+延迟期).11例中有5例加做MRI平扫及动态增强扫描.回顾性分析病变的生长方式、分布特点、密度(信号)特点、强化方式及邻近组织情况.结果 11例均表现为肝内多发病灶,大部分病灶位于肝包膜下,根据生长方式分为三型:结节型(5例),匍匐生长型(1例)和混合型(5例).CT平扫,病灶均呈低密度,直径＞2 cm的病灶内见类圆形更低密度.MRI平扫:病灶呈T1WI低信号、T2WI高信号,直径＞2 cm的病灶信号不均匀(T1WI内见更低信号,T2WI内见更高信号).其他影像学征象包括“棒棒糖征”(6例)、包膜退缩征(6例).增强扫描:病灶直径＜1 cm的表现为轻度较均匀强化;病灶直径为1～2 cm主要表现为轻度较均匀强化;病灶直径＞2 cm的多为不均匀渐进性强化.结论 HEHE的CT和MRI表现具有一定的特征性,其强化方式与病灶的大小相关.     

肝脏炎性假瘤的CT及MRI征象

目的:探讨肝脏炎性假瘤的CT和MRI表现。方法:8例经手术病理证实的肝脏炎性假瘤。男5例,女3例,年龄35~65岁,平均53岁。8例均作CT平扫及增强扫描,其中3例行MR对比检查。结果:CT表现为1 个病灶6 例,2个病灶2例,共发现病灶10个。平扫9个病灶表现为低密度,1 个病灶表现为稍高密度。动态增强扫描2 个病灶动脉期显著强化,门脉期及延迟期中度强化;8个病灶动脉期无明显强化,门脉期及延迟期有不同方式的强化,主要表现为周边完整或不完整的环形或结节状强化,中心核心样强化及线状或不规则分隔样强化。MRI表现为2 例病灶T1WI呈低信号,T2WI呈稍高信号,1例病灶T1WI及T2WI均为等信号,动态增强扫描与CT相仿。结论:肝脏炎性假瘤的CT及MRI表现因其病理阶段不同而表现各异,诊断需结合临床,确诊尚依靠病理检查。     

结节样周围型胆管细胞癌的CT和MRI表现

目的:分析结节样周围型胆管细胞癌(PCC)的CT和MRI表现及其病理基础.方法:15例经病理证实的结节样PCC患者,11例行多层螺旋CT平扫及动态增强扫描,6例行MRI平扫和动态增强扫描.结合病理结果分析其CT和MRI表现.结果:15例共检出病灶19个,直径(2.8±1.4)cm,于肝左、右叶均见分布.CT共检出15个病灶,增强扫描示14个病灶动脉期呈周边强化,门脉期显示8个病灶内对比剂向中央扩散强化,6个病灶未见上述强化方式;1个病灶CT动态增强扫描呈"快进快出"改变.4个病灶见邻近肝包膜凹陷,2个病灶伴随胆管轻度扩张.6例MRI共检出6个病灶,T2WI示5个病灶呈不规则低信号,动态增强扫描示相应区域均见强化;另1例病灶增强扫描动脉期有异常强化,门脉期及延迟期呈等信号.结论:结节样周围型胆管细胞癌的CT和MRI表现多样,与病灶内各种成分的比例和分布相关,其动态增强表现有一定特征性.     

肝胆管囊腺癌的MRI表现

目的:探讨肝胆管囊腺癌(HBCAC)的MRI表现,提高肝胆管囊腺癌的诊断准确性.方法:回顾性分析9例经病理证实的肝胆管囊腺癌的MRI表现,所有患者均行MR平均和三期动态增强扫描.结果:9例中单囊性病灶8例,多囊性病灶1例.T1WI上6例表现为囊状低信号影,囊内分隔和囊壁厚薄不均,可见壁结节或乳头状突起;3例囊壁光滑,囊内呈稍高信号影,可见结节状软组织信号影.T2WI上病灶以高信号为主,囊内分隔、壁结节及软组织呈低信号.增强扫描动脉期示囊内分隔、壁结节和软组织明显强化,门脉期及延迟期强化仍较明显.结论:平扫及动态增强MRI能较好反映肝胆管囊腺癌的影像学特点,对本病的诊断及鉴别诊断有重要价值.     

肝胆管囊腺癌影像学表现

目的 探讨肝胆管囊腺癌的CT、MRI及B超表现,提高其诊断准确率.方法 回顾性分析18例经病理证实的肝胆管囊腺癌患者,螺旋CT检查6例、MRI检查5例,B超检查7例.结果 18例肝胆管囊腺癌患者中多囊性病灶2例,16例为单囊性病灶.CT平扫及MRI T1WI均表现为囊性占位,囊内可见分隔和乳头样、条状实性突起,囊壁不均匀增厚,T2WI病灶呈高信号为主,囊内分隔及乳头样、条状实性突起呈低信号,增强后动脉期囊壁、分隔及实性部分轻度强化,门脉期进一步强化,延迟期减退但仍有强化.B超均表现肝内液性为主的囊实性混合回声团块,边界较模糊,边缘高低不平,囊内有棉絮状或乳头状赘生物.结论 平扫加动态增强CT、MRI及B超能够一定程度反映肝胆管囊腺癌的影像学特点,对于提高该疾病的诊断具有一定参考价值.     

肝脓肿MRI征象分析

目的 探讨MRI对肝脓肿诊断的价值.方法 对临床及手术病理证实的29例肝脓肿MRI资料进行回顾性分析.结果 单发脓肿17例,多发12例,共58个病灶中,出现簇形征15例,肝段性或片状异常信号22例,花边样边缘及嵴状分隔17例,靶征或双环征8例,脓腔内出现气体3例,脓腔内组织碎屑沉积3例.10例增强扫描中,7例可见边缘强化征,5例见蜂窝网格状强化.结论 MRI能更好地显示肝脓肿的特征,平扫联合增强扫描在脓肿定位、定性及鉴别诊断上具有重要意义.＃     

肝肺吸虫病的影像学表现特征及病理基础

目的：探讨肝肺吸虫病的 MDCT 和 MRI 的表现特征及病理基础。方法回顾性分析经手术病理证实的19例肝肺吸虫病患者的 MDCT 和 MRI 的征象,并与病理结果进行对照;19例中,15例行 MDCT 扫描,2例行 MRI 扫描,2例同时行 MDCT 和MRI 扫描。结果所有病例共有22个病灶,均位于肝包膜下区,其中18个病灶与肝包膜直接相贴。根据增强后的影像特征,分为复杂性和单纯性2种病变类型。复杂性病变有13个,主要表现为内含多分隔或多房性肿块,病灶内无强化囊腔及窦道相互交通;单纯性病变有9个,其中管状病变2个、迂曲隧道样病变3个、类圆形实性病变4个。增强扫描各期病灶内分隔及边缘均为轻度强化,门脉期强化程度均高于动脉期。2个复杂性病变的强化分隔及边缘在 MRI 平扫 T1 WI 为稍高信号。结论复杂性病变及单纯性病变中的管状和迂曲隧道样病变可能是肝肺吸虫病的典型影像征象;MRI 平扫 T1 WI 显示为稍高信号分隔及边缘对肝肺吸虫病有较好的提示作用;认识这些影像征象有助于对该病早期正确诊断和避免不必要的外科手术。     

细菌性肝脓肿的低场MRI诊断

目的:探讨低场MRI在细菌性肝脓肿诊断中的临床应用价值.方法:回顾经手术病理或临床治疗证实的19例23个肝脓肿,分析低场MRI平扫及增强影像表现及病理基础.结果:23个肝脓肿14个位于肝右叶,9个位于肝左叶.典型肝脓肿7个,表现环征或双靶征,病灶中心液化坏死,脓肿内小泡状积气或气液平面,病灶周围水肿.不典型肝脓肿16个,不同时期影像表现各异,表现为簇状征,蜂窝征,蜘蛛足征等.结论:低场MRI能较好显示肝脓肿的病理过程中组织结构不同特征,能提高细菌性肝脓肿的诊断正确率.     

Differentiation of pyogenic and fungal brain abscesses with susceptibility-weighted MR sequences

Introduction

Conventional magnetic resonance imaging (MRI) techniques are insufficient to determine the causative agent of brain abscesses. We investigated: (1) the value of susceptibility-weighted MR sequences (SWMRS) in the differentiation of fungal and pyogenic brain abscesses; and (2) the effect of different SWMRS (susceptibility-weighted imaging (SWI) versus venous blood oxygen level dependent (VenoBOLD)) for the detection of specific imaging characteristics of pyogenic brain abscesses.

Methods

We studied six patients with fungal and ten patients with pyogenic brain abscesses. Imaging characteristics on conventional MRI, diffusion-weighted imaging (DWI) and SWMRS were recorded in all abscesses. All lesions were assessed for the presence of a “dual-rim sign” on SWMRS.

Results

Homogenously hyperintense lesions on DWI were present in 60 % of patients with pyogenic abscesses, whereas none of the patients with fungal abscesses showed such lesions. On SWMRS, 90 % of patients with pyogenic abscesses and 60 % of patients with fungal abscesses had only lesions with a low-signal-intensity rim. On SWI, the dual-rim sign was apparent in all pyogenic abscesses. None of the fungal abscesses on SWI (P?=?0.005) or any of the pyogenic abscesses on VenoBOLD (P?=?0.005) were positive for a dual-rim sign.

Conclusions

In fungal abscesses, the dual-rim sign is not present but a prominent peripheral rim or central susceptibility effects on SWI will be seen. The appearance of pyogenic abscesses on SWMRS depends on the used sequence, with the dual-rim sign a specific feature of pyogenic brain abscesses on SWI.     

CT of small pyogenic hepatic abscesses: the cluster sign

Of 36 consecutive patients with pyogenic liver abscesses evaluated by CT, five (14%) had multiple small abscesses less than 2 cm in size. The CT appearance of the small pyogenic abscesses was compared with that of 10 patients who had either fungal or mycobacterial abscesses and with that of 50 patients who had hepatic metastases. In all five patients who had small pyogenic abscesses, the abscesses appeared to cluster, or aggregate, in a pattern that suggested the beginning of coalescence into a single, larger abscess cavity (cluster sign). This cluster appearance was not seen in in any of the patients who had fungal or mycobacterial microabscesses. It was present in only one of the patients who had confirmed hepatic metastasis. Despite the small size of the abscesses, guided needle aspiration was successful in recovering pyogenic organisms in four of the five patients. In our experience, the presence of the cluster sign suggests that the lesions are pyogenic abscesses.     

簇形征——化脓性肝脓肿的早期重要征象

目的：描述肝脓肿的ＣＴ表现，总结簇形征在肝脓肿的早期诊断中的作用。方法：回顾分析经证实的１７例肝脓肿的ＣＴ表现，并与霉菌性、结核性肝脓肿及肝转移瘤的ＣＴ表现进行了比较。结果：６例（占３５．３％）有小于２ｃｍ的多发性小脓肿，在ＣＴ上表现为簇形征。结论：簇形征是早期肝脓肿诊断的重要线索之一。     

肝脓肿的MRI分型和诊断

认识肝脓肿ＭＲＩ典型及不典型征象，探讨ＭＲＩ分型的诊断意义。材料和方法：６７例８２个肝脓肿经手术病理和临床治疗证实，回顾性分析平扫和增强ＭＲＩ表现，并进行归类分型。结果：８２个肝脓肿可分成三种ＭＲＩ类型：房腔型占７１．９５％（５９／８２），特征是病灶体积的２０％以上由液化坏死的房腔和纤维肉芽的腔壁构成；肉芽型占２０．７３％（１７／８２），特征是病灶体积的８０％以上由纤维肉芽组织构成，间以细小液化或     

Sonographic features of amebic and pyogenic liver abscesses: a blinded comparison

We blindly compared the sonographic findings in amebic (112 lesions) and pyogenic (30 lesions) liver abscesses. Two sonographic features were significantly more prevalent in amebic abscesses: the lesions had a round or oval shape and the lesions had an echogenicity that was lower than that of normal liver and were internally homogeneous on high-gain scans. Amebic abscesses were round or oval in 92 instances (82%), while 18 pyogenic abscesses (60%) (p less than .01) had these shapes. Fifty-nine (58%) of 101 amebic abscesses displayed low echogenicity and homogeneous internal echoes with high-gain settings compared with nine (36%) of 25 pyogenic abscesses (p less than .04). Despite these different sonographic patterns, image findings alone were inadequate in distinguishing pyogenic from amebic liver abscesses. However, when the sonographic findings were coupled with clinical and laboratory data, a correct diagnosis was possible in 83 (86%) of 96 patients with amebic abscess. It appears that, although some sonographic features of amebic abscess differ from those of pyogenic abscess, these differences are not sufficient to allow a specific diagnosis on the basis of sonography alone. Sonography can expedite abscess detection and, when coupled with clinical and laboratory data, can aid in differentiating pyogenic from amebic liver abscesses.     

Ultrasound and magnetic resonance imaging in Crohn's disease: a comparison

The objective of this retrospective study was to compare MRI of the abdomen with ultrasound of the abdomen and gastrointestinal tract in patients with Crohn's disease. Forty-six patients were included in the study. We analyzed the localization of Crohn's lesions, the number of affected bowel segments, the number of stenoses, and the presence of abscesses, fistulae, and any additional findings. Findings were verified by means of one or more of the following: enteroclysis; surgical findings; and colonoscopy. The results show that MRI is superior to ultrasound in the localization of affected bowel segments (sensitivity: MRI 97.5%; US 76%) and in recognizing fistulae (sensitivity: MRI 87%; US 31%), stenoses (sensitivity: MRI 100%; US 58%) and abscesses (sensitivity: MRI 100%; US 89%). Magnetic resonance imaging of the abdomen should be obtained to clarify discrepant clinical and sonographic findings. In addition, despite its higher cost, MRI of the abdomen is justified in patients in whom Crohn's lesions are known or suspected in anatomic areas proximal to the terminal or neoterminal ileum and in cases with suspicion of fistulae and abscesses.     

Pyogenic hepatic abscesses: MRI findings on T1- and T2-weighted and serial gadolinium-enhanced gradient-echo images

The purpose of this study was to determine the magnetic resonance imaging (MRI) features of pyogenic hepatic abscesses on T1-weighted, T2-weighted, and serial gadolinium (Gd)-enhanced T1-weighted spoiled gradient-echo (SGE) images including images acquired in the immediate, intermediate, and late phases of enhancement. The MRI studies of 20 patients with pyogenic liver abscesses were retrospectively reviewed. All patients were examined on 1.5 (n = 19) and 1.0 (n = 1) T MR scanners. MR studies included T1-weighted, T2-weighted, and serial Gd-enhanced SGE images. The following determinations were made: signal intensity of the abscess cavity and perilesional liver tissue, and the presence of internal septations, layering material, or air in the abscess cavity. The pattern of enhancement of the abscess wall, internal septae and peri-abscess liver were evaluated on serial Gd-enhanced SGE images. A total of 53 abscesses were observed in the 20 patients. Fortyeight abscesses were hypointense on T1-weighted and hyperintense on T2-weighted images. Internal septations were present in four abscesses. Lower signal intensity material was observed in a dependent location on T2-weighted images in one abscess. Signal void foci of air located on the nondependent surface was observed in two abscesses. Two other abscesses contained signal void air that occupied the entire abscess cavity, observed on all imaging sequences. On serial gadolinium-enhanced images, all abscesses revealed early enhancement of the wall, which persisted with negligible change in degree of enhancement or thickness on delayed images. Abscess walls ranged in thickness from 2 to 5 mm. Internal septations ranged in thickness from 2 to 3 mm. Abscess walls and septations were relatively uniform in thickness with no evidence of focal nodularity. Periabscess liver tissue was mildly hypointense on T1-weighted and mildly hyperintense on T2-weighted images in 20 lesions, which were either circumferential (n = 12) or wedge-shaped (n = 8). All these regions enhanced more than the remainder of the liver on immediate post-gadolinium images and remained relatively hyperintense on late phase images. Periabscess liver parenchyma was isointense on both T1- and T2-weighted images in 18 lesions, and in these lesions wedge-shaped subsegmental (n = 6) or segmental (n = 12) enhancement was observed on immediate gadolinium-enhanced images, which faded to isointensity on intermediate phase images. No perilesional signal changes and enhancement difference was observed in 15 lesions. Characteristic features of abscesses include: intense mural enhancement on early gadolinium-enhanced images, which persists with negligible change in thickness and intensity on later post-gadolinium images, and the presence of periabscess increased enhancement on immediate post-gadolinium images. These MRI features may help to distinguish abscesses from other focal liver lesions during differential diagnosis.     

Solid organizing hepatic abscesses mimic hepatic tumor: Multiphasic computed tomography and magnetic resonance imaging findings with histopathologic correlation

OBJECTIVE: To describe the computed tomography (CT) and magnetic resonance imaging (MRI) findings of solid organizing hepatic abscesses and correlate them with the pathologic findings. METHODS: Ten patients with 10 pathologically proven solid organizing hepatic abscesses who underwent 3-phase CT (n = 10) or MRI (n = 7) were enrolled in this study. Images were retrospectively analyzed by consensus of 2 radiologists for attenuation (signal intensity), shape, and margin of the lesions as well as for their enhancement patterns. Their imaging findings were correlated with their pathologic findings. RESULTS: The main imaging finding on CT or MRI was the well-defined target appearance of a central enhancing area with a low-attenuation (signal intensity) rim on arterial and portal phases. On the delayed phase, most of lesions showed slightly low attenuation (signal intensity) with an enhancing rim, and 1 showed diffuse enhancement. Pathologically, the central areas and peripheral rims corresponded to granulation tissue and fibrosis, respectively. Nine lesions demonstrated a tiny necrotic cystic portion in the center. CONCLUSION: The target appearance of solid organizing hepatic abscesses on CT and MRI can be helpful in differentiating them from other focal liver lesions. These imaging findings are well correlated with the pathologic findings.     

肝脏原发性平滑肌瘤的影像表现

目的探讨肝脏原发性平滑肌瘤的影像特征。方法回顾性分析经病理证实的3例无免疫缺陷的肝脏原发性平滑肌瘤患者CT和MRI表现，及其与临床、病理间的联系。2例行CT检查，2例行MR检查。结果2例CT检查者病灶呈低密度，2例MRI检查者病灶呈长T1、长T2信号。1例密度和信号均匀，呈明显均匀强化；2例不均匀，1例增强后不均匀强化。3例均有假包膜征，无肝硬化和静脉瘤栓。病理示梭形肿瘤细胞增殖，毛细血管增生；1例伴中心玻璃样变，1例伴中心液化坏死。结论肝脏原发性平滑肌瘤是富血管性有假包膜的肿瘤，CT和MR检查对诊断有一定帮助。