Alveolar echinococcosis: MR findings in the liver

PURPOSE: To clarify the magnetic resonance (MR) imaging findings of alveolar echinococcosis in the liver. MATERIALS AND METHODS: Thirty-five patients with 50 lesions histologically proven to be alveolar echinococcosis were evaluated with MR imaging. Lesions were assessed with regard to the distribution pattern of solid and cystic components and pattern of contrast material enhancement. RESULTS: Cystic components exhibited two patterns at T2-weighted MR imaging: small round cysts and large and/or irregular cysts. Forty-eight lesions (96%) contained small round cysts. Twenty-six lesions (52%) had large and/or irregular cysts. Forty-five lesions (90%) were associated with a solid component. MR imaging characteristics were categorized into five types: multiple small round cysts without a solid component (two lesions [4%], type 1), multiple small round cysts with a solid component (20 lesions [40%], type 2), a solid component surrounding large and/or irregular cysts with multiple small rounds cysts (23 lesions [46%], type 3), a solid component without cysts (two lesions [4%], type 4), and a large cyst without a solid component (three lesions [6%], type 5). In most cases (97%), contrast enhancement was weak. CONCLUSION: The MR findings of alveolar echinococcosis in the liver are multiple small round cysts with a weakly enhanced solid component. The cystic component can be a large and/or irregular lesion, and such lesions are depicted clearly at T2-weighted MR imaging.     

Alveolar echinococcosis of the liver: Diffusion-weighted MRI findings and potential role in lesion characterisation

Purpose

To report the diffusion-weighted MRI findings in alveolar echinococcosis (AE) of the liver and evaluate the potential role of apparent diffusion coefficients (ADCs) in the characterisation of lesions.

Materials and methods

We retrospectively included 22 patients with 63 AE liver lesions (≥1 cm), examined with 3-T liver MRI, including a free-breathing diffusion-weighted single-shot echo-planar imaging sequence (b-values = 50, 300 and 600 s/mm²). Two radiologists jointly assessed the following lesion features: size, location, presence of cystic and/or solid components (according to Kodama's classification system), relative contrast enhancement, and calcifications (on CT). The ADC_total, ADC_min and ADC_max were measured in each lesion and the surrounding liver parenchyma.

Results

Three type 1, 19 type 2, 17 type 3, three type 4 and 21 type 5 lesions were identified. The mean (±SD) ADC_total, ADC_min and ADC_max for all lesions were 1.73 ± 0.50, 0.76 ± 0.38 and 2.63 ± 0.76 × 10⁻³ mm²/s, respectively. The mean ADC_total for type 1, type 2, type 3, type 4 and type 5 lesions were 1.97 ± 1.01, 1.76 ± 0.53, 1.73 ± 0.41, 1.15 ± 0.42 and 1.76 ± 0.44 × 10⁻³ mm²/s, respectively. No significant differences were found between the five lesion types, except for type 4 (p = 0.0363). There was a significant correlation between the presence of a solid component and low ADC_min (r = 0.39, p = 0.0016), whereas an inverse correlation was found between the relative contrast enhancement and ADC_total (r = −0.34, p = 0.0072).

Conclusion

The ADCs of AE lesions are relatively low compared to other cystic liver lesions, which may help in the differential diagnosis. Although ADCs are of little use to distinguish between the five lesion types, their low value reflects the underlying solid component.     

Alveolar soft part sarcoma: MR and angiographic findings

Objective. To present the MR and angiographic findings of alveolar soft part sarcoma (ASPS). Design and patients. MR examinations (12 tumors of 10 patients) of ASPS performed at multiple hospitals were retrospectively reviewed. The tumors were found in the thigh (n=4), lower leg (n=4), femur (n=2, local metastasis), scalp (n=1) and arm (n=1). The MR signal characteristics including signal intensity, homogeneity and signal void of lesions and bony invasion including direct invasion or local metastasis were evaluated. Angiographic findings (n=4) and post-embolotherapy follow-up MR imaging (n=2) findings were also assessed. Results. Local bony metastasis was found in two cases. Seven tumors showed heterogeneous high signal intensity on T1- and T2-weighted images with good enhancement. One tumor had a very high signal on T1-weighted images. Eight tumors (67%) showed numerous signal voids in or near the tumors. All four angiographic studies showed numerous enlarged vessels, arteriovenous shunts and delayed washout. Two cases mimicked arteriovenous malformations on angiographic studies but MR images demonstrated solid soft tissue components as well as tortuous vessels. Conclusions. High signal on T1-weighted image and numerous signal voids are highly suggestive of ASPS, although they are not universal as has been suggested and arteriovenous malformation should be included in the differential diagnosis. Local bony metastases in ASPS were seen in two cases and should be carefully investigated. Received: 12 April 2000 Revision requested: 27 June 2000, 8 August 2000 Revision received: 2 August 2000, 21 August 2000 Accepted: 22 August 2000     

Osler-Weber-Rendu disease: MR findings in the liver

We report the magnetic resonance (MR) findings in the liver of a patient with known Osler-Weber-Rendu disease, a rare disorder characterized by arteriovenous malformations involving multiple organ systems. To the best of our knowledge, the MR findings in liver involvement have not been previously reported.     

Diffusion-weighted MR imaging findings in a growing problem: Hepatic alveolar echinococcosis

Hepatic alveolar echinococcosis (AE) is a rare parasitic disease which simulates slow growing malignant processes. Cross-sectional imaging techniques play important role in differentiating between AE lesions and malignant processes such as cholangiocellular carcinoma (CCC) and hepatocellular carcinoma (HCC). Diffusion-weighted (DW) MRI is a non-invasive technique, which can be used for liver lesion detection and characterisation as benign or malignant in recent years. Both conventional MRI and non-contrast enhanced CT images may be insufficient the differential diagnosis in hepatic AE lesions particularly in solid components. In our study, we have performed to differentiate hepatic AE lesions from HCC and CCC lesions of the liver by using DW MRI and tried to define ADC value of hepatic AE lesions for differentiation from malignant hepatic lesions.     

Alveolar echinococcosis of the liver: correlative color Doppler US, CT, and MRI study

Purpose: To determine and compare the imaging features of hepatic alveolar Echinococcosis using color Doppler US, CT, and MRI.

Material and Methods: Abdominal CT and MRI with and without contrast agents and color Doppler US were performed on seven patients with hepatic alveolar Echinococcosis. The lesions were evaluated for location, features of echogenicity, intensity and density, calcification, and vascular, hilar, and perihepatic involvement. The diagnosis was confirmed histopathologically in all patients.

Results: Six patients had solitary lesions, and one displayed multiple lesions. The lesions were generally seen as heterogeneous and hyper- or hypoechoic when imaged with color Doppler US, hypodense with CT, and hypointense with MRI, in comparison with the liver parenchyma. Calcification, central necrosis, and small peripheral cysts were observed in six, seven, and four patients, respectively. Vascular flow or contrast enhancement was not observed in any of the cases. A look at the respective advantages of each method reveals that calcification was best rendered visible via CT, small peripheral cysts with T2-weighted MRI, central necrosis with CT and MRI, and perihepatic invasion with multiplanar MRI. Vascular involvement was revealed by all methods.

Conclusion: Color Doppler US, CT, and MR imaging function extremely well as complementary methods in the diagnosis of HAE. Color Doppler US should be performed in these patients owing to its ability to efficiently detect the disease. Knowledge of imaging characteristics makes it possible to radiologically ascertain an early diagnosis.     

Primary leiomyosarcoma of the liver MR findings

The magnetic resonance (MR) features of a 67-year-old woman with a surgically and pathologically proved primary leiomyosarcoma of the liver studied at 1.0 T, using T1- (TR/TE = 450/15), and T2-weighted (TR/TE = 2200/45 to 90) spin-echo (SE) images, are described. On T1-weighted SE images, the tumor was well defined, was slightly heterogeneous, and displayed hypointensity to the adjacent hepatic parenchyma, with an area displaying hyperintensity. On T2-weighted SE images, the tumor was encapsulated, was heterogeneous, and displayed marked hyperintensity.     

Cholangiolocellular carcinoma of the liver: CT and MR findings

The authors report two cases of surgically proved cholangiolocellular carcinoma of the liver. Marked contrast enhancement was observed at the periphery of the tumor on CTs and MRIs obtained during the hepatic arterial and portal venous phases, with concentric filling on the delayed images. On T1-weighted and T2-weighted MRIs, the tumor was, respectively, hypointense and hyperintense, with a central hypointense area. Therefore, helical CT and MRI features of these cholangiolocellular carcinomas were thought to be similar to those of cholangiocarcinoma.     

HASTE MRCP and MRI findings in alveolar echinococcosis of the liver

Alveolar echinococcosis is a rare mass-producing inflammatory process of the liver. Experience with MRI, and particularly magnetic resonance cholangiopancreatography (MRCP), demonstrates that features of this disease are limited. The HASTE (half-Fourier acquisition single-shot turbo spin echo) MRCP and MRI findings of alveolar echinococcosis of the liver are presented in this report. HASTE MRCP was used to define the biliary system and the biliary system-mass relationship. It was found that results were comparable with those of invasive techniques such as endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography.     

MR findings in eosinophilic infiltration of the liver

OBJECTIVE: This study describes the findings of magnetic resonance imaging (MRI) of focal eosinophilic infiltration of the liver. METHODS: Contrast-enhanced MR images of 8 patients with focal hepatic eosinophilic infiltration were reviewed retrospectively. We evaluated the signal intensity of focal lesions in T1-weighted and T2-weighted images and the pattern of enhancement in a dynamic contrast study. RESULTS: A total 22 focal hepatic lesions were observed; the lesions were isointense (55%) or hypointense (45%) on T1-weighted images and isointense (14%) or hyperintense (86%) on T2-weighted images. The arterial phase of the contrast study revealed 11 hyperintense lesions (50%). During the portal and delayed phases, 18 (82%) and 17 lesions (77%) were hyperintense, respectively. CONCLUSION: The focal eosinophilic infiltrations showed homogeneous enhancement in the portal and delayed phases in the dynamic contrast MR study. These findings should help to distinguish focal eosinophilic infiltration, especially from metastasis in patients with malignancy.     

Epithelioid hemangioendothelioma of the liver: MR and CT findings.

The MR imaging features in five patients with hepatic epithelioid hemangioendothelioma (EHE) were correlated with CT and pathologic findings. Two hemangioendotheliomas appeared as multiple nodular lesions with a predominantly peripheral location in the liver. In three more extensive cases, the tumors formed confluent peripheral lesions with macroscopic invasion of portal or hepatic veins (n = 3), signs of portal hypertension (n = 3), and nodular hypertrophy of uninvolved liver (n = 2). These findings, suggestive of EHE, were well demonstrated by MR imaging and CT. The internal architecture of the tumors was clearly depicted on T2-weighted MR images. Viable tumor peripheries appeared moderately hyperintense relative to liver. The center of the tumors consisted of one or several concentric zones. Hyperintense central zones were composed of loose, edematous connective tissue. Hypointense zones contained mainly coagulation necrosis, calcifications, and scattered hemorrhages. Except for the presence of calcifications, the internal architecture of EHE was better defined by MR imaging than by CT.     

Giant cavernous hemangioma of the liver: atypical CT and MR findings

The CT and MR appearance of giant cavernous hemangiomas can be confusing, and some atypical radiographic findings have been described. We report the CT and MR features of a giant cavernous hemangioma of the liver with atypical presentation. CT showed a large hypodense geographical lesion involving the majority of the liver and multiple scattered peripheral lesions. The T2-weighted MR images revealed a huge hyperintense lesion with multiple satellite nodules. Correspondence to: C. Valls     

Focal nodular hyperplasia of the liver: MR findings in 35 proved cases

MR images of 28 patients with 35 lesions of hepatic focal nodular hyperplasia were reviewed to determine the frequency of findings considered typical of this condition (isointensity on T1- and T2-weighted pulse sequences, a central hyperintense scar on T2-weighted images, and homogeneous signal intensity). Fifteen lesions were imaged at 0.6 T with T1- and T2-weighted spin-echo (SE) pulse sequences; 20 lesions were imaged at 1.5 T with T1-weighted SE and gradient-echo pulse sequences and T2-weighted SE pulse sequences. Diagnosis of focal nodular hyperplasia was made pathologically in 25 patients, with nuclear scintigraphy in four, and with follow-up imaging in six. Only seven lesions (20%) were isointense relative to normal liver on both T1- and T2-weighted images. On T1-weighted SE images, 21 lesions (60%) were isointense relative to normal liver, 12 (34%) were hypointense, and two (6%) were hyperintense. On T2-weighted SE images, 12 lesions (34%) were isointense and 23 (66%) were hyperintense relative to normal liver. A central scar was present in 17 lesions (49%) and was hypointense relative to the lesion on T1-weighted images and hyperintense on T2-weighted images. Twenty lesions (57%) were of homogeneous signal intensity throughout the lesion, except for the presence of a central scar. All three MR imaging characteristics were present in three cases (9%). We conclude that hepatic focal nodular hyperplasia has a wide range of signal intensity on MR imaging.     

MR imaging in spinal echinococcosis

A case of spinal echinococcosis with dorsal spinal cord compression is presented and the findings on plain radiography, polytomography, myelography, CT, and magnetic resonance (MR) imaging are discussed. Although CT and MR are complementary studies for the diagnosis of spinal echinococcosis, MR is the study of choice for prolonged follow-up of complicated cases.     

Solitary necrotic nodule of the liver: MR findings in 33 pathologically proved lesions

Purpose

To determine characteristic magnetic resonance (MR) imaging features of solitary necrotic nodule of the liver.

Materials and methods

MR images features of thirty-two patients (17 men, 15 women; mean age, 43 years; range, 24–76 years) with pathologically proved solitary necrotic nodule of the liver were retrospectively analyzed for number, size, signal intensity features and enhancement patterns.

Results

A total of 33 lesions were identified. The mean diameter was 2.3 cm (range 1.0–4.5 cm). Thirty lesions (90.9%) were 1.0–3.0 cm in diameter and only 3 lesions (9.1%) were larger than 3.0 cm. On T1-weighted images, solitary necrotic nodule of the liver appeared hypointense in 31 lesions (93.9%) and isointense in 2 lesions (6.1%). On T2-weighted images, 12 (36.4%) lesions were hyperintense, 15 (45.4%) were isointense or invisible and 6 (18.2%) were hypointense. After injection of gadopentetate dimeglumine, all lesions were hypointense and none of them showed enhancement.

Conclusion

Solitary necrotic nodule of the liver is usually small with the size not exceed 3.0 cm in diameter. Absence of enhancement on all dynamic phase after gadopentetate dimeglumine administration may be most characteristic feature of solitary necrotic nodule of the liver on MR images, which may help discriminate this entity from metastatic liver tumors and intrahepatic cholangiocarcinoma.     

MR水成像技术诊断泡状棘球蚴病的价值

目的 探讨MR水成像(MRH)技术在泡状棘球蚴病临床诊断中的作用.方法 搜集34例临床怀疑为泡状棘球蚴病的患者,其中32例经手术和病理证实为泡状棘球蚴包虫病,均行常规MR和MRH检查,以病理结果为金标准,比较两种方法 的灵敏性、特异性和准确性.2种方法 结果符合率的比较采用U检验.结果32例泡状棘球蚴病患者的128个病灶中,常规MRI检查发现68个、MRH发现108个.常规MRI检查泡状棘球蚴的灵敏性为(53.13±0.04)%,特异性为(92.59±0.05)%,符合率为(60.00±0.03)%;MRH检查泡状棘球蚴病灶的灵敏度为(84.38±0.03)%,特异度(81.48±0.08)%,符合率为(83.87±0.03)%,常规MRI和MRH符合率比较,差异具有统计学意义(U=5.44,P<0.01).结论MRH技术可以提高泡状棘球蚴病病灶检出的灵敏性和符合率.     

MRI findings of hepatic alveolar echinococcosis

Diagnosis of liver infestation by alveolar echinococcosis (AE) is based on serologic, sonographic and computed tomography (CT) findings. Experience with magnetic resonance imaging (MRI) demonstrates that features of this disease are limited. CT and MRI findings of 14 cases with hepatic AE were compared in this report. We have described the MRI appearance of hepatic AE, which exhibits variable signal intensities on T1- and T2-weighted images. Fibrous and parasitic tissue showed low signal both on T1- and, generally, on T2-weighted images. In a few cases, a high signal on T2-weighted images may be observed, due either to central necrotic zones or to small peripheral cyst. MRI than by CT was more easily identified central necrosis. However, MRI seemed to be less effective than CT in allowing us to reach a positive diagnosis, due to its inability to show microcalcifications. In addition, MRI may not reveal small lesions. In most cases, T1-weighted images revealed more clearly than CT did the margins of the lesions and the hepatic extension, especially to hepatic veins, vena cava and perihepatic spaces.