MRI appearances of calcified regions within intracranial tumours

The MRI appearances of calcification within intracranial tumours was assessed by reviewing MR images of 11 calcified tumours documented by CT. The signal intensity of the calcified regions was varied and nonspecific on both T1-and T2-weighted images. They were seen as signal void exclusively on T2-weighted images in only 2 patients. Gadolinium enhancement of the calcified portion occurred in 7 of 10 patients. These findings reflect the presence of tumour parenchyma within the calcified region, as proved in 5 lesions examined histologically.     

Atypical demyelinating lesions in patients with multiple sclerosis

We describe an atypical MRI appearance of multiple sclerosis (MS). Lesions characterized on T2-weighted images by a well-defined rim of increased signal intensity and a concentric region of higher signal intensity were seen in 6 of 132 patients with MS. On T1-weighted images these lesions were evident as regions of low signal intensity, often with a rim of contrast enhancement or increased signal intensity. These appearances tended to be shown by new, evolving lesions.     

Suprasellar cavernous haemangioma: an important differential diagnosis in the diencephalic tumours

We present three cases of suprasellar cavernous haemangioma with characteristic high-field MRI features. Clinical, CT and MRI data were retrospectively analysed. The patients had progressive neurological, endocrinological and visual complaints. In the three cases CT revealed a high-density suprasellar mass. In all cases the combination of a reticulated core of mized signal intensity with a surrounding rim of decreased signal on T1- and T2-weighted MRI scans suggested the presence of a cavernous haemangioma. Two patients underwent surgical biopsy after their first MRI examination. Cavernous haemangiomas located in the suprasellar area may show typical MRI features. Correspondence to: B. Suarez     

Magnetic resonance imaging characteristics with pathological correlation of cavernous malformation in cavernous sinus

OBJECTIVE: To analyze extracerebral cavernous malformation located in the cavernous sinus and correlate their magnetic resonance imaging (MRI) features to pathological findings. MATERIALS AND METHODS: Nineteen patients (5 men and 14 women; mean age, 50.6 years; range, 32-71 years) with surgically verified cavernous malformations in the cavernous sinus were reviewed. MRI including T1-weighted, T2-weighted, and postcontrasted T1-weighted imaging was carried out in all instances with a 1.5-T superconductive system (Signa; General Electric Medical Systems, Milwaukee, WI). RESULTS: All these lesions measured from 2.5 cm to 6 cm (average, 4.3 cm) with 13 lesions located to the right side and 6 to the left side. Magnetic resonance images showed that 18 cases were hypointense to white matter on T1-weighted images with only one case showed mixed hypointensity and hyperintensity. On T2-weighted images, 17 cases showed marked homogeneous hyperintensity, 1 case showed marked hyperintensity with some signal void structures and 1 with mixed intensity. Marked homogeneous enhancement after contrast material administration was found in 7 cases, and the remaining 12 showed marked heterogeneous enhancement. Pathologically, these lesions can be classified as type A, type B, and type C. Type A was sponge-like with intact pseudocapsule; type B was mulberry-like with the pseudocapsule incomplete or absent; and type C was composed of both mulberry-like composition and sponge-like composition. Lesions with homogeneous contrast enhancement on MRI correlated with type A pathological findings, whereas those with heterogeneous enhancement correlated with type B and type C pathological findings. Asymmetrical dumbbell-shaped masses of 13 cases involving the sellar and round masses of 6 cases with 2 protruding into the sellar were found. All of the cavernous malformations displaced the adjacent temporal lobe without adjacent brain edema. The internal carotid arteries were displaced or encased in all cases. CONCLUSIONS: If a well-demarcated, homogeneous high signal intensity lesion on T2-weighted images with a dumbbell configuration involving both parasellar and sellar regions with marked heterogeneous or homogeneous enhancement is found, the diagnosis of cavernous sinus cavernous malformation should be entertained.     

骨母细胞瘤的CT和MRI诊断(附12例报告)

目的探讨CT及MR对骨母细胞瘤的诊断价值,提高对本病的认识。方法回顾分析经病理学证实的12例骨母细胞瘤的临床、CT、MR I及病理学资料。结果(1)行CT检查6例,均表现为膨胀性溶骨性破坏区伴随不同程度的钙化或骨化,瘤灶边缘呈反应性骨硬化缘,边缘光整。(2)行MR I扫描10例(包括4例已做CT检查的病人),表现为膨胀性的骨改变,瘤灶信号混杂,内有分隔,T1W I呈略低或等信号,T2W I呈高信号9例,1例以低信号为主。其中8例瘤灶周边可见清楚的T1、T2低信号缘,2例邻近组织呈片状模糊高信号。(3)增强扫描均呈中度以上强化,内夹杂片状低信号不强化区。结论骨母细胞瘤有较为典型的CT表现,MR I表现缺乏特征性。     

Magnetic resonance imaging of retained surgical sponges case report

The magnetic resonance imaging (MRI) features of sponges retained postsurgically in three patients are described. MRI depicted these as well-defined round masses, which were of low signal intensity on T1-weighted images and very high signal intensity on T2-weighted images. We scrutinized these masses on T2-weighted images. MRI revealed the low-signal-intensity structures to have wavy, striped, and/or spotted appearances, which raised the suspicion that they might be retained surgical sponges within mass lesions.     

Germinoma originating in the basal ganglia

A case of germinoma originating in the basal ganglia is presented. Preoperative MRI showed an area of a reticulated core of mixed signal intensity with a surrounding rim of low signal intensity in the right basal ganglia on T2-weighted image. This finding was reported to be characteristic of cavernous angioma, but the tumor was histopathologically identified to be a germinoma with old hemorrhage. The pitfall of MRI in diagnosing brain tumors is discussed.     

Desmoplastic small round cell tumor: imaging findings associated with clinicopathologic features

PURPOSE: To describe imaging findings of desmoplastic small round cell tumor (DSCRT) and to clarify the relation between radiologic appearances and clinicopathologic features. MATERIALS AND METHODS: CT scans and MRI examinations of four male patients with histologically confirmed DSCRT (mean age = 20 years) were retrospectively analyzed. RESULTS: The common imaging finding was multiple peritoneal masses with regular contour situated within mesentery. Tumors showed central low attenuation in 75% of patients on nonenhanced CT. All tumors showed inhomogeneous enhancement on CT. Small foci of punctate calcification were identified in a part of the tumor in all patients. Bone metastases were identified on enhanced CT in two patients 2 and 8 months after diagnosis, respectively. Pleural dissemination was identified in all patients, and one patient had double-sided dissemination. T2-weighted MRI showed inhomogeneous high signal intensity, and small cysts were identified in two patients. Fluid-fluid levels were identified in six tumors on T2-weighted images, which suggested the presence of hemorrhage. Tumors had inhomogeneous signal intensity low or isointense relative to skeletal muscle on T1-weighted images. Two lesions exhibited inhomogeneous enhancement with central low intensity consistent with necrosis. CONCLUSION: Imaging studies can depict disseminated characteristics and disease extent during the clinical course of DSRCT.     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

Cerebral vascular malformations: applications of magentic resonance imaging to differential diagnosis

Summary Twelve patients with cerebral vascular malformations (5 cavernous angiomas, 1 thrombosed arteriovenous malformation, and 6 venous angiomas) were studied with magnetic resonance (MR) imaging. All lesions were clearly depicted. Characteristic MR findings were obtained mainly on T2-weighted images: a markedly low intensity area was always seen. The margins of arteriovenous malformation (AVM) and venous angioma were irregular while those of cavernous angioma were smooth in all planes on T2-weighted images. Gradient-echo (GrE) pulse sequences were more sensitive than T2-weighted spin echo (SE) in lesion detection. MR imaging could play an important role in the differential diagnosis of cerebral vascular malformations.     

Case report: primary lymphoma of bone--MRI appearances with pathological correlation.

A case of primary lymphoma of bone involving the proximal tibia is presented. The magnetic resonance (MR) appearances were unusual for a primary malignant tumour, with predominantly low signal intensity on both T1- and T2-weighted images. This correlated with marked fibrosis on histology. These observations are discussed in the context of previous reports of MRI in bone lymphoma.     

Evaluation of MR imaging findings differentiating cavernous haemangiomas from schwannomas in the orbit

Objective

It is important to distinguish between orbital cavernous haemangioma and schwannoma because the treatments of choice for the two tumours are different. The aim was to evaluate MR imaging findings distinguishing the two tumours.

Methods

Magnetic resonance imaging including T1- and T2-weighted imaging and contrast-enhanced MR imaging was performed in 43 patients with cavernous haemangiomas and 16 patients with schwannomas confirmed by pathology. Location, configuration, margins, signal intensity, homogeneity and enhancement pattern of the tumour were retrospectively evaluated.

Results

There was a significant difference between cavernous haemangiomas and schwannomas regarding the location, configuration and margins of the mass, signal intensity and homogeneity on T1- and T2-weighted imaging, the spread pattern of contrast enhancement, the enhancement pattern and the type of time–intensity curve (P?<?0.05). Markedly homogeneous hyperintensity signal on T2-weighted imaging and the spread pattern of the contrast enhancement favoured cavernous haemangioma rather than schwannoma (P?<?0.01).

Conclusion

Cavernous haemangiomas and schwannomas have different MR imaging features that could be helpful in the differentiation between the tumours. The spread pattern of the contrast enhancement on dynamic contrast-enhanced MR imaging is the most reliable finding distinguishing cavernous haemangiomas from schwannomas.     

Adrenal phaeochromocytoma: correlation of MRI appearances with histology and function

The purpose of this study was to describe the range of appearances of adrenal phaeochromocytomas on T2-weighted MRI, correlate appearances with histopathology, and quantify the incidence of the previously described hyperintense appearance. The appearance and MR characteristics of 44 phaeochromocytomas were reviewed retrospectively. T2-weighted appearances were grouped: (1) ‘classical’, homogeneous, high signal intensity, isointense to CSF; (2) homogeneous, isointense or minimally hyperintense to spleen, hypointense to CSF; (3) heterogeneous, marbled appearance; (4) heterogeneous, multiple high signal intensity pockets. All 44 adrenal phaeochromocytomas were well circumscribed, 1.2–15 cm in maximum diameter, with no visual or quantitative signal loss on chemical shift imaging. On T2-weighted MRI 5/44 (11%) had group 1 appearance; 15/44 (34%) group 2, 7/44 (16%) group 3; and 17/44 (39%) group 4. Homogeneous group 1 and 2 lesions were smaller (mean 4.5 cm) than heterogeneous group 3 and 4 lesions (mean 6.3 cm). Increasing MRI heterogeneity correlated pathologically with increasing amounts of haemorrhage, necrosis and fibrosis. No MRI features were predictive of malignancy. Non-functioning phaeochromocytomas were larger than functioning lesions. No size difference was seen between syndrome and sporadic lesions. In this large series we report a wide range of appearances of adrenal phaeochromocytomas on T2-weighted MRI. The previously described classical hyperintense phaeochromocytoma is relatively uncommon.     

MRI of tuberculous pyomyositis.

PURPOSE: The purpose of this article is to describe the findings of MRI in tuberculous pyomyositis (PM). METHOD: The MR images of four proven cases of tuberculous PM were retrospectively reviewed and analyzed with clinical and laboratory findings. The location, signal intensity on T1- and T2-weighted spin echo images, presence of abscess, signal intensity of peripheral rim, patterns of contrast enhancement, and associated findings were evaluated. RESULTS: On MR images, all cases demonstrated low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in a single muscle. Abscess was seen in all cases. Peripheral rim showed subtle hyperintensity on T1-weighted images and hypointensity on T2-weighted images. After gadolinium infusion, peripheral rim enhancement was observed in all cases. Cellulitis was associated in one case. The patients clinically presented with a palpable mass of long duration. CONCLUSION: Tuberculous PM shows characteristic findings of a well demarcated abscess with rim enhancement at MRI and can be distinguished from other soft tissue masses.     

椎管内血管性病变的MRI诊断

目的 总结不同类型椎管内血管性病变的影像特点,以提高对该类疾病的诊断水平. 资料与方法 对33例经手术病理或DSA证实的椎管内血管性病变的影像及临床资料进行回顾性分析,其中海绵状血管瘤11例(髓内8例,髓外硬脊膜外3例),血管母细胞瘤4例(单发2例,多发2例),动静脉病变18例(动静脉瘘12 例,动静脉畸形6例).所有病例均行MR平扫和增强扫描. 结果 椎管内血管性病变好发年龄在40岁左右,临床多表现为渐进性的神经系统受损症状.海绵状血管瘤髓内较髓外相对多见,髓内病变颈段好发,病变多局限,病灶周围T2低信号环较具特征性,强化多不明显;硬脊膜外海绵状血管瘤少见,多发生在胸段,常为边界清楚梭型肿物,均匀明显强化.血管母细胞瘤较少见,可单发亦可多发,多发生在颈、胸段,当伴有较大范围脊髓空洞或囊变,并有明显强化结节时,诊断不难;动静脉病变最多见, MRI多能发现蜿蜒血管流空信号,较易诊断,但具体分型有赖于DSA或手术. 结论 椎管内不同类型的血管性病变具有相对特异的影像表现,MRI可较好地显示病变,并能准确定位,同时可以显示脊髓变性的程度和范围,有利于病变的诊治及判断预后.     

儿童臀部硬纤维瘤的影像表现

目的:探讨臀部硬纤维瘤的超声、CT、MRI表现特征。材料和方法:搜集10例经手术病理证实的儿童臀部硬纤维瘤病例,均行超声、CT平扫及增强扫描,5例行MRI检查,分析其影像学特点。结果:臀部硬纤维瘤主要累及臀部肌肉、筋膜、骨膜等,呈浸润性生长,易复发。超声表现为不规则低回声肿块。CT表现为低密度软组织肿块(9例),等高密度肿块(1例),强化程度不等。MRI表现为臀部肿块,T1WI等低信号,T2WI多为稍高信号夹杂斑片低信号(3例),或等低信号(2例),增强后可见不均匀强化。结论:超声、CT及MRI检查可显示硬纤维瘤的大小、形态;MRI能从多个切面显示肿瘤范围以及周围组织受侵情况,并可推断组织成分,为临床治疗提供重要信息。     

MRI of unusual lesions in the internal auditory canal

We report the MRI findings of six unusual lesions of the internal auditory canal: three haemangiomas, one lipoma, one metastasis and one traumatic neuroma. We compare the findings to those of 20 intracanalicular schwannomas. We noted the site and size of the tumour, its signal intensity, borders and the homogeneity of enhancement were studied on T1-weighted images before and after intravenous contrast medium and T2-weighted images. Most schwannomas were homogeneous lesions, isointense on T1- and T2-weighted images, and strongly enhancing. Spontaneous high signal on T1-weighted images, heterogeneous contrast enhancement and extranodular enhancement were helpful for recognising lesions other then schwannomas; site, size and signal on T2-weighted images were not. All the haemangiomas had a specific pattern of contrast enhancement, with an anterior core intensely enhancing portion and a posterior portion which enhanced moderately or not at all. Received: 4 November 1999/Accepted: 19 July 2000     

Magnetic resonance imaging of cavernous hemangioma of the liver: tissue-specific characterization

Twenty-one patients with hepatic hemangioma, five with hepatic cysts, and 25 with primary or metastatic cancer involving the liver were studied by magnetic resonance imaging (MRI). Benign lesions (hemangiomas, cysts) were diagnosed noninvasively by CT, radionuclide studies, and/or sonography and confirmed by follow-up examinations more than 1 year later. Malignant lesions were confirmed by liver biopsy in every case. Identical multisection/multiecho techniques were used in all patients to obtain T1-and T2-weighted spin-echo (SE) and inversion-recovery (IR) images. MRI detected more hemangiomas than any other imaging technique. Of 30 hemangiomas, 25 were spherical or ovoid with a homogeneous appearance and smooth, well defined margins. Cancer tended to have a heterogeneous appearance and poorly defined margins. On T2-weighted SE images obtained with 2000 msec TR and 60, 120, or 180 msec TE, hemangiomas had significantly greater contrast-to-noise ratios (C/N) than liver cancer (p less than 0.001). The SE 2000/120 sequence provided the single most useful image for distinguishing hemangiomas from cancers. When morphologic criteria are used in conjunction with measured C/N, MRI correctly distinguished cavernous hemangiomas from liver cancer with 90% sensitivity, 92% specificity, and an overall accuracy of 90%. Cysts had a low signal intensity on SE 500/30 images and could often be distinguished from hemangiomas and cancers that were nearly isointense relative to liver. IR images were sensitive for lesion detection but provided no tissue-specific information. The data indicate that T2-weighted SE imaging may become the procedure of choice for distinguishing cavernous hemangioma from liver cancer.     

Diffusion-weighted echo planar imaging of ovarian tumors: is it useful to measure apparent diffusion coefficients?

PURPOSE: Our goal was to test the hypothesis, as previously reported in other studies, that apparent diffusion coefficients (ADCs) provide specific information to diagnose ovarian tumors, especially to discriminate between benign and malignant lesions. METHOD: T1-and T2-weighted spin echo imaging and diffusion-weighted echo planar imaging were performed in 31 women with 61 cystic components of ovarian tumors. RESULTS: The lesions that showed typical watery intensity, hypointensity in T1-weighted imaging, and hyperintensity in T2-weighted imaging had similar ADCs, ranging from 1.54 to 1.84 x 10(-3) mm2 /s. The lesions that showed signal intensity different from typical watery intensity in conventional MRI tended to have low ADCs. In endometrial cysts, the mean ADC of the subgroup that showed typical watery intensity was higher than that of other subgroups. CONCLUSION: With conventional MRI, a tendency of ADCs could be predicted. ADCs may not provide additional information, especially to discriminate benign from malignant lesions.     

MRI diagnosis and follow-up of subcutaneous fat necrosis

The purpose of this report is to present the MRI features of subcutaneous fat necrosis (SFN) and the natural history of this process. We have seen 12 patients with SFN, one case of which was confirmed histopathologically. In six patients, a follow-up MRI study was performed. MRI findings were very similar in all of the cases: small, linear, and spiculated lesions with one or two components: a globular area yielding high signal intensity on T1-weighted images, intermediate to high signal intensity on fast SE T2-weighted images and focal signal void on short-inversion -time inversion recovery (STIR) sequence, corresponding to an area of fat necrosis; and a laminar starred component, with low signal intensity on T1 and fast SE T2-weighted images and high signal intensity on the STIR sequence, corresponding to reactive fibrous tissue. The follow-up MRI study of six patients showed either disappearance (n = 2) or decrease in size (n = 3) of the globular component; in one patient, no change was observed. A less prominent decrease of the laminar component also was seen in five patients. One patient did not present any change in this laminar component. The most characteristic MRI findings of this lesion are the high signal intensity areas on T1-weighted images, their small size (<3 cm), their linear spiculated shape with both laminar and globular components, and no contrast enhancement after injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection. We believe that the location, size, morphology, and MRI signal intensity of SFN may allow its differentiation from other types of soft tissue lesions.