MR imaging of malignant mesenchymal tumors of the liver

Magnetic resonance (MR) features of five primary malignant mesenchymal neoplasms (plasmocytoma, leiomyosarcoma, undifferentiated sarcoma, epithelioid hemangioendothelioma, and angiosarcoma) of the liver were reported. All tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. No halo and intravenous extension were noted. A target appearance was revealed in epithelioid hemangioendothelioma. MR findings of angiosarcoma were essentially the same as those of cavernous hemangiomas (markedly hyperintense with hypointense linear septa on T2-weighted images). MR findings of these rare hepatic malignancies were nonspecific, although they were quite different from those of typical hepatocellular carcinomas. This study suggested that MR differentiation of primary hepatic mesenchymal tumors from other common benign and malignant neoplasms was difficult; however, the number of studied cases was limited.     

Focal nodular hyperplasia of the liver: detection and characterization with plain and dynamic-enhanced MRI

Background: We compared nonenhanced and dynamic gadolinium (Gd)–enhanced magnetic resonance imaging (MRI) appearances of hepatic focal nodular hyperplasia (FNH) as depicted with breath-hold MR sequences and assessed the detectability of the individual MR sequences used. Methods: We retrospectively reviewed 48 consecutive patients with FNH. All patients underwent nonenhanced (T1 fast low-angle shot [FLASH] and T2 half-Fourier acquisition [HASTE]) and dynamic Gd-enhanced (T1 FLASH) MRI between December 1997 and March 2000. Individual MR sequences were analyzed separately for number of lesions, signal intensity features, dynamic enhancement pattern, and the presence and enhancement profile of a central scar. Ninety-five percent confidence intervals of absolute discrepancy were calculated to define differences in lesion detection. Results: Seventy-seven lesions were found in 48 patients. Nonenhanced FLASH imaging depicted 59 (76.6%) lesions in 45 patients. HASTE images showed 55 (71.4%) lesions in 44 patients. On T1- and T2-weighted images, lesions appeared predominantly hypointense (69.5%) and hyperintense (72.7%), respectively. Arterial and portal venous dominant phase Gd-enhanced MRI demonstrated all 77 lesions (100%), most of which showed hypervascular (94.8%), homogeneous (97.4%), and incomplete (except the central scar: 58.4%) enhancement in the arterial phase. Portal venous phase images showed lesion isointensity (50.6%) or moderate hyperintensity (46.8%) with complete enhancement (central scar: 94.8%). A central scar was detected on nonenhanced T1-weighted images (hypointense: 100%), T2-weighted images (hyperintense: 100%), arterial phase (hypointense: 59.7%) and portal venous phase (hyperintense: 71.4%) Gd-enhanced images in 78%, 69.1%, 77.9%, and 75.3% of tumors, respectively. Conclusion: Arterial and portal venous phase Gd-enhanced T1-weighted sequences are superior to nonenhanced images in the detection of FNH. Typical MRI appearances include hypointensity on T1-weighted and hyperintensity on nonenhanced T2-weighted images. Most commonly, FNH shows a homogeneous (without scar) and strong enhancement during the arterial phase, with lesion isointensity or slight hyperintensity during the portal venous phase. Received: 15 May 2001/Revision accepted: 22 August 2001     

Association of multiple liver cell adenomas with spontaneous intrahepatic portohepatic shunt

The association of multiple liver cell adenomas containing foci of focal nodular hyperplasia with a spontaneous intrahepatic portohepatic venous shunt is reported in a 13-year-old male patient. At least eight nodules less than 10 cm in diameter were recognized and proved by means of surgical resection or surgical biopsies. These lesions were heterogeneous and hypodense on precontrast computed tomographic (CT) scans, and were slightly enhanced after injection of contrast medium. At magnetic resonance (MR) imaging, the signal intensity of these nodules varied. It was either hyperintense or hypointense on T1-weighted SE images. Sonography and angiography demonstrated a portohepatic venous shunt and hepatic arterialization was observed. These findings emphasize the hypothesis that hepatic arterialization may cause the development of liver cell adenomas. Moreover, it is suggested that liver cell adenoma and focal nodular hyperplasia have a common pathogenesis.     

Plain and gadolinium-DTPA-enhanced MR imaging of hepatocellular carcinoma treated with transarterial chemoembolization

Background: To assess unenhanced and gadolinium-enhanced magnetic resonance (MR) imaging patterns of hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE). Methods: Thirty-two patients with 48 HCC lesions underwent MR imaging before and 15 days after TACE. Fifteen lesions were then surgically resected. The remaining 33 lesions were not removed and were followed up with MR imaging at 3, 6, 12, and 18 months after treatment. Spin echo (SE) T1- and T2-weighted and gadolinium-enhanced SE T1-weighted sequences were employed. Qualitative evaluation of signal intensity pattern of the treated lesions was performed in all cases. Histological evaluation and selective hepatic arteriography were considered the gold standard of the study for the 15 resected lesions and the 33 unresected lesions, respectively. Results: On follow-up enhanced T1-weighted images of the 15 resected lesions, seven showed no area of enhancement corresponding to complete necrosis at histologic examination. The remaining eight resected lesions showed areas of enhancement; in six of these cases, viable tumor tissue was found at histology; in the other two lesions, histologic examination revealed the presence of complete tumor necrosis. In the group of resected lesions, T2-weighted images showed no pattern characteristic of necrosis. In 24 of 33 unresected lesions, loss of enhancement on follow-up enhanced T1-weighted images was a characteristic finding, which correlated to devascularization at arteriography. Of these 24 lesions, 17 were completely hypointense on follow-up T2-weighted images; the remaining seven showed small foci of hyperintensity. The other nine unresected lesions showed enhanced portions on follow-up enhanced T1-weighted images, which corresponded to hyperintense areas on T2-weighted images. These findings correlated to persistence of hypervascular areas at arteriography. Conclusion: Gadolinium-enhanced T1-weighted MR imaging is a reliable method for evaluating the outcome of TACE treatment and is more accurate than unenhanced T2-weighted MR imaging. Received: 2 June 1995/Accepted: 18 July 1995     

MRI of Budd-Chiari syndrome

A retrospective study was undertaken to reassess the various magnetic resonance imaging (MRI) features of Budd-Chiari syndrome (BCS). MRI examinations of 22 patients with pathologically confirmed BCS were studied. Spin-echo (SE) T1- (TR = 300–450 ms/TE = 12–15 ms), and SE T2-weighted (TR = 1600–2000 ms/TE = 30–60/90–120 ms) MRI images were obtained in all patients. Gradient-recalled-echo (GRE) images (TR = 7–60 ms/TE = 3–19 ms, flip angle = 10–40°) were obtained in 14 patients. MRI showed thrombosis of three or two hepatic veins in 19 (86%) and 3 (14%) patients, respectively. Spontaneous intrahepatic anastomoses was depicted in five (23%) patients. Ascites appeared in 15 patients (68%). Thrombosis or external compression of the inferior vena cava (IVC) by an enlarged caudate lobe was depicted in six (27%) and five (23%) patients, respectively. Prominent azygos and hemiazygos veins were demonstrated in seven (32%) patients (six of whom had thrombosis of the IVC). MRI showed hepatomegaly in all patients and enlarged caudate lobe in 18 (82%) patients. SE T1- and SE T2-weighted MRI images revealed inhomogeneous signal intensity of hepatic parenchyma in 14 (64%) patients. SE T1- and SE T2-weighted MRI images showed homogeneous signal intensity of hepatic parenchyma in eight (36%) patients. Our results demonstrate that BCS displays various features on MRI images, and such information is important for diagnosis.     

Intrahepatic splenosis: imaging features

We report a patient who presented with asymptomatic focal liver lesions and in whom a diagnosis of intrahepatic splenosis was made. This rare condition mostly occurs in patients who previously underwent splenic trauma or surgery. Magnetic resonance imaging (MRI) characteristics suggesting this diagnosis are described. The lesions were mainly hypointense on T1- and hyperintense on T2-weighted images. After administration of small iron oxide particles (SPIO-Endorem), the lesions remained slightly hyperintense relative to the hypointense liver parenchyma but showed a 50% loss in signal intensity. Knowledge of these MRI characteristics may avoid the use of surgical interventions to arrive at the correct diagnosis of these rare liver lesions. Received: 14 June 1999/Accepted: 14 July 1999     

脑膜瘤的MRI表现与病理分类(附41例报告)

目的:探讨脑膜瘤的MRI表现及病理分类。材料与方法:对41例经手术病理证实的脑膜瘤病例MRI表现进行回顾性分析。结果:在MRISE-T1WI上,41例脑膜瘤病例中16例呈低或稍低信号占39%,25例呈等信号占61%。在SE-T2WI上,高或稍高信号31例占75.6%,等信号8例占19.5%,低或稍低信号2例占4.8%。结论:脑膜瘤的MRI表现特征明显,并且T2的信号强度差异对部分脑膜瘤的病理分类有一定帮助。     

韧带样纤维瘤病的CT及MRI特征及病理对照

目的回顾性分析韧带样纤维瘤的CT及MRI特征表现及病理基础。方法收集经手术病理证实的韧带样纤维瘤共27例影像学及病理资料,CT检查12例,MRI检查14例,另1例行CT及MRI检查;全部病例均行增强扫描。结果27例共30个病灶,16个病灶发生于腹壁,14个病灶发生于腹壁外。形态：全部病灶均沿肌纤维长轴生长,20个呈梭形或类圆形,10个不规则形;7个边界较清,23个边界不清。与肌肉密度、信号相比：CT上10个病灶呈稍低密度,3个呈等密度,9个渐进性中度强化,4个不均匀性强化;T1WI上9个病灶呈等信号,9个病灶呈稍低信号;T2WI上15个呈高或稍高信号,3个呈混杂信号;STIR上均呈较高信号,15个内部见条片状低信号;增强扫描所有病灶不均匀性渐进性中度强化,其中12个内部条状斑片状的低信号未见明显强化。病理上肿瘤多呈浸润性生长,由纤维母细胞和肌纤维母细胞组成,内部见致密纤维组织及胶原组织,部分见黏液沉积。结论韧带样纤维瘤的CT、MRI表现有一定特征,肿瘤多呈浸润生长,瘤内出现特征性稍低密度或条带状低信号,无液化坏死区,渐进性中度强化。     

Nodular regenerative hyperplasia of the liver in Budd–Chiari syndrome: CT and MR features

We report the imaging findings of spiral computed tomography (CT), magnetic resonance (MR) imaging, and MR angiography in a patient with nodular regenerative hyperplasia of the liver associated with Budd–Chiari syndrome. Spiral CT showed multiple enhancing nodules during the hepatic arterial and portal venous phases. MR images showed multiple hyperintense nodules on T1-weighted images and hypointense or isointense nodules on T2-weighted images. MR angiography showed thrombotic occlusion of three hepatic veins, suggesting Budd–Chiari syndrome. Received: 25 June 1999/Revision accepted: 22 September 1999     

MR imaging of hepatocellular carcinoma at 1.5 Tesla

The authors investigated the magnetic resonance appearance of hepatocellular carcinoma using a 1.5-Tesla magnet. Twenty-four patients with pathologically proven hepatocellular carcinoma had magnetic resonance imaging (MRI) studies, which were retrospectively reviewed. All patients were imaged with at least two of the following techniques: (1) T1-weighted (T1W), (2) T1-weighted with Gd-DTPA enhancement (T1W-E), (3) T2-weighted (T2W), (4) proton density (PD), and (5) gradient-recalled echoes (GRE). T1W images were equal to T2W images for tumor detection using a grading system. T1W images were slightly better than T2W images for the total number of lesions detected. The other pulsing techniques (PD, T1W-E, and GRE) detected fewer lesions. Eight cases of hepatocellular carcinoma (33%) had nonhomogeneous increased signal intensity on both T1W and T2W images. The authors conclude that T1W images are equal to T2W images for detection of hepatocellular carcinoma. The authors also conclude that 33% of hepatocellular carcinomas have an imaging pattern with increased signal intensity on both T1W and T2W images. This pattern is atypical for most other hepatic masses and hence can be used to suggest the mass is hepatocellular carcinoma.     

正常足月新生儿脑的MRI信号特点

目的:研究正常足月新生儿脑的MRI信号特点。材料与方法:用0.15T磁共振成像设备SE序列对20例正常足月新生儿进行颅脑T_1和T_2加权成像。以孕期胎龄与出生后日龄之和做为新生儿的实际胎龄。结果与结论:①T_1加权成像脑白质表现低信号,髓鞘化区城为高信号,灰质为稍高信号。髓鞘化的范围和灰白质对比度与新生儿的实际胎龄成正相关;②T_2加权成像,脑白质为较高信号,灰质和髓鞘化区域呈明显的低信号,全组新生儿的灰白质对比均清晰明显;③全组新生儿的侧脑室前角和后角周围的小片白质均呈长T_1和T_2信号特点,与邻近的白质和灰质对比清楚。此属生理现象。     

肝脏恶性纤维组织细胞瘤2例报告并文献复习

目的:提高对肝脏恶性纤维组织细胞瘤临床诊断的认识。方法:回顾2例经手术和病理检查证实的肝脏恶性纤维组织细胞瘤影像资料,并复习国内相关文献14篇(含18例)。结果:CT和MRI检查:2例肿瘤均位于肝右叶,肿瘤呈浸润性生长,与周围肝实质分界不清。CT平扫表现为不规则形低密度占位,CT值24~40 Hu,增强扫描动脉期肿瘤实质呈不均匀强化。MRI表现为:巨大的占位性病灶,T1WI像为低信号,T2WI像为高信号,信号不均匀,边界不清,形态不规则。动态增强扫描:动脉期、门脉期病灶明显不均匀强化,延迟期强化渐减退或仍见团片状强化。结论:肝脏恶性纤维组织细胞瘤的临床诊断较困难,其影像学表现主要为肿瘤向外浸润生长,边界不清,缺乏特征性征象。     

Hepatic mesenchymal sarcoma: MRI findings

Hepatic undifferentiated mesenchymal sarcoma is a rare pediatric malignant neoplasm. We present three children, aged 7, 8, and 12 years, with this tumor. Clinical presentation was abdominal pain, palpable mass, asthenia, anorexia, and weight loss. One had jaundice. All three lesions were detected on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). MRI localized the lesions more accurately than the other methods, with good resectability correlation. On MRI, these tumors were markedly hyperintense on long TR/TE spin-echo (SE) and short-time inversion recovery (STIR) sequences. This was due to the cystic areas with myxoid material and necrosis. The internal septations were hypointense on these sequences. On short TR/TE SE sequences the lesions presented a fibrous pseudocapsule (two cases), and internal hyperintense areas representing hemorrhage (two cases). MRI also detected vascular invasion (one case), biliary obstruction (one case), and biliar adenopathies (one case). The combination of hemorrhage (hyperintense on short TR/TE SE) and cystic or myxoid components (markedly hyperintense on long TR/TE SE and STIR sequences) is common in this tumor.     

MR imaging of intrahepatic cholangiocarcinoma

Background: The purpose of this study was to determine the magnetic resonance (MR) features of intrahepatic cholangiocarcinoma. Methods: MR imaging studies of seven cases of pathologically proven intrahepatic cholangiocarcinoma were retrospectively reviewed. Results: On MR images the tumors presented as a single mass (N = 5) or multiple nodules (N = 2), as welldelineated (N = 5) or ill-defined (N = 2), and as non-encapsulated (N = 7). Mean tumor diameter ranged from 6–14 cm (mean, 10 cm). On T1-weighted (TR/TE = 400–600/10–17 msec) images, the tumors were hypointense compared to the liver. The five tumors studied with dynamic MR imaging showed progressive centripetal filling-in after intravenous administration of a gadolinium chelate. On T2-weighted (TR/TE = 2000–2500/80–100 msec) images, all tumors were hyperintense compared to the liver; five were markedly hyperintense and two moderately hyperintense. Vascular encasement, bile duct dilatation within the tumor, and central scar were depicted on MR images in four, three, and two tumors respectively. Conclusion: The typical MR appearance of intrahepatic cholangiocarcinoma is a large well-delineated nonencapsulated tumor associated with intrahepatic venous encasement.     

MRI differential diagnosis of intrahepatic biloma from subacute hematoma

The magnetic resonance imaging (MRI) differential diagnosis of intrahepatic biloma from intrahepatic subacute hematoma has been reported in two cases. The biloma was heterogenously intense on T1-weighted images and homogenously hyperintense on T2-weighted images. The hematoma was hyperintense on the both T1-and T2-weighted MR images. The clinical significance of this MRI difference is that intrahepatic biloma needs drainage, whereas intrahepatic hematoma can heal spontaneously.     

Hepatic segmental atrophy and nodular elastosis: imaging features

Purpose

To evaluate the imaging features of hepatic segmental atrophy and nodular elastosis.

Materials and methods

In this Institutional review board (IRB)-approved, HIPAA-compliant study, we reviewed imaging features in six cases of histologically confirmed hepatic segmental atrophy (HSA) and nodular elastosis (NE). Retrospective review of ultrasound (US) in 2 patients, computed tomography (CT) in 5 patients, magnetic resonance imaging (MRI) in 4 patients, and positron emission tomography (PET) in 2 patients was performed. Location, size, and attenuation/density/signal intensity of these lesions were evaluated. Clinical presentation and coexistent conditions were also recorded.

Results

All six patients were females. Mean age of presentation was 58.3 years (range 37–80). A single HSA and NE lesion in each patient was found. The mean size of the lesion was 18 mm (range: 3 mm to 36 mm). Most lesions were detected incidentally (5/6). On contrast-enhanced single-phase (portal venous) CT, most lesions were hypodense (4/5) and one lesion was hyperdense to fatty liver parenchyma. On MRI, the lesions were iso- to hyperintense on T2-weighted images, T1 hypointense, and hyperintense on diffusion-weighted images (DWI). Three lesions were hypointense on arterial, portal venous, and delayed phases. One lesion occurring in fatty liver appeared hyperintense on all three phases. Gd-EOB-DTPA-enhanced images were available in 2 patients and lesions were hypointense on the 20-min hepatobiliary phase. On PET, two lesions were isometabolic to the background hepatic parenchyma. On ultrasound, one lesion appeared hypoechoic and another lesion isoechoic to hepatic parenchyma.

Conclusions

Hepatic segmental atrophy and nodular elastosis is an uncommon benign lesion and can simulate metastases due to variable imaging features. Lack of FDG uptake on PET/CT may be a clue to the benign nature of the lesion and may suggest the possibility of HSA and NE.

     

黏液性脂肪肉瘤的CT、MRI表现

目的 探讨黏液性脂肪肉瘤的CT、MRI表现特征。 方法 回顾性分析经手术病理证实的24例黏液性脂肪肉瘤的CT、MRI表现特点。18例术前接受CT平扫,其中9例同时接受增强扫描;6例接受MR平扫,其中5例同时接受增强检查。 结果 24例黏液性脂肪肉瘤均表现为单发结节或肿块;发生于下肢(n=12)尤其大腿(n=9)最为多见,其次是腹膜后(n=7);发生于四肢的14例患者中,病变位于肌间隙10例(n=10),肌肉内2例(n=2),皮下脂肪层内2例(n=2);15例肿瘤形态规则,边界尚清,9例形态不规则,边界不光整,可见分叶等征象;病灶最大径2.0~38.0 cm,平均(12.5±8.0)cm。18例CT平扫CT值11.0~30.0 HU,平均(19.4±6.8)HU;6例MR平扫T1WI病变与肌肉相比以等或稍低信号为主,2例内见云絮状高信号;4例T2WI病变与皮下脂肪相比以明显高信号为主,内有稍高信号区和(或)线样低信号分隔,2例呈均匀显著高信号;14例CT和MR增强后病变均表现为明显不均匀强化;CT强化最显著区CT值35.0~112.0 HU,平均(62.7±27.0)HU。 结论 黏液性脂肪肉瘤的CT、MRI表现有一定特征,CT平扫多为囊样低密度影,MRI以T1WI低信号、T2WI显著高信号为主,T2WI可伴稍高信号区和(或)线样低信号分隔,增强后多呈显著不均匀强化。     

Bile duct involvement in hepatocellular carcinoma: MR demonstration

Background: To determine the magnetic resonance (MR) features of hepatocellular carcinoma (HCC) with associated bile duct involvement. Methods: MR examinations of six patients (mean age, 62 years) demonstrating bile duct involvement due to HCC were retrospectively reviewed and compared to surgical and pathologic findings. Results: Three of the tumors were solitary, and three were multifocal. In two patients, MR showed direct biliary duct invasion by tumor. On T1-weighted MR images, four tumors were hypointense compared to the liver and two were isointense. On T2-weighted MR images, four tumors were hyperintense, and two were isointense. The two tumors studied with dynamic T1-weighted MR images obtained after intravenous administration of a gadolinium chelate, displayed enhancement similar to that of the liver. There was no evidence of a tumor capsule on either unenhanced or enhanced MR images. Intrahepatic bile duct dilatation was seen in five patients. The extrahepatic bile duct was normal in all cases. Conclusion: Although rare, HCC should be included when considering the etiology of intrahepatic bile duct obstruction. Imaging features suggestive of the diagnosis by MR include intrabiliary tumor or bile duct obstruction with an associated hepatic mass.     

Brunnstrom stages and Wallerian degenerations: a study using MRI.

We studied the relationship between the Brunnstrom stages obtained after rehabilitations and Wallerian degenerations detected by magnetic resonance imaging (MRI). Forty-nine hemiplegic patients were retrospectively studied. The patients were grouped into a low stage group (30 patients) demonstrating Brunnstrom stages I approximately IV and a high stage group (19 patients) demonstrating stages V approximately VI. MRI detected Wallerian degenerations as changes of signal intensity in corticospinal tracts on T2-weighted images. The signals were hypointense or hyperintense compared to the normal side according to the intervals between the MRI examinations and the ictuses. MRI showed Wallerian degenerations in 27 of 30 patients in the low stage group and 5 of 19 patients in the high stage group. The difference between the two groups was significant (p less than 0.005).