Orbital lymphoma. Role of CT and MRI

CT and MRI have made it possible to make a strongly presumptive diagnosis of orbital lymphoid tumors. Orbital lymphomas are usually homogeneous masses of relatively high density and sharp margins. The lesions mold themselves to pre-existing structures without eroding the bone. On MR imaging, they appear as relatively hypointense images, particularly in T1-weighted MR scans.     

Computed tomography and magnetic resonance imaging findings of solitary fibrous tumors in the pelvis: Correlation with histopathological findings

Objective

We aimed to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of pelvic solitary fibrous tumors (SFTs) and to improve the diagnostic efficacy for such tumors.

Methods

Six cases of pelvic SFTs confirmed by histopathology were analyzed retrospectively. Of the 6 patients, 4 had undergone CT scanning, and 2 had undergone magnetic resonance imaging. All the patients had undergone unenhanced and contrast-enhanced examinations, and 2 had also undergone dynamic CT enhancement examination. Image characteristics such as shape, size, number, edge, attenuation or intensity for each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors.

Results

All the 6 cases showed oval or rounded and well-defined masses. Unenhanced CT images showed heterogeneous masses with patchy, necrotic foci in 3 cases and homogeneous mass in 1 case. None of the tumors showed calcification. Contrast-enhanced CT images showed marked, heterogeneous enhancement in the first and second cases. Dynamic enhancement scan demonstrated mild homogeneous enhancement in the third case and mild prolonged, delayed enhancement and washout in the fourth case. T1-weighted MR images showed heterogeneous mild hypointense lesion with linear hyperintensity in 1 case, and homogeneous isointensity in the other. T2-weighted images showed heterogeneous mixed intensity in 1 case and mostly hyperintensive lesion with hypointense foci in another case. A case showed marked heterogeneous enhancement and another showed marked homogeneous enhancement on contrast-enhanced T1-weighted images.

Conclusion

Radiological findings of pelvic SFTs are variable and nonspecific. However, a well-defined, ovoid or rounded mass with hypointense on MR T2-weighted images and variable enhancement on CT and MR images may suggest the diagnosis of SFTs. Pelvic SFTs should be included in the differential diagnosis of regional tumors.     

Radiologic-Pathologic Correlation of Unusual Lingual Masses: Part II: Benign and Malignant Tumors

Because the tongue is superficially located and the initial manifestation of most diseases occurring there is mucosal change, lingual lesionscan be easily accessed and diagnosed without imaging analysis. Some lingual neoplasms, however, may manifest as a submucosal bulge and be located in a deep portion of the tongue, such as its base; their true characteristics and extent may be recognized only on cross-sectional images such as those obtained by CT or MRI.Some uncommon tongue neoplasms may have characteristic radiologic features, thus permitting quite specific radiologic diagnosis. Lipomas typically manifest at both CT and MR imaging as homogeneous nonenhancing lesions. Relative to subcutaneous fat they are isoattenuating on CT images, and all MR sequences show them as isointense. Due to the paramagnetic properties of melanin, metastases from melanotic melanoma usually demonstrate high signal intensity on T1-weighted MR images and low signal intensity on T2-weighted images.Although the radiologic findings for other submucosal neoplasms are nonspecific, CT and MR imaging can play an important role in the diagnostic work-up of these unusual tumors. Delineation of the extent of the tumor, and recognition and understanding of the spectrum of imaging and the pathologic features of these lesions, often help narrow the differential diagnosis.     

Castleman's disease in the retropharyngeal space: CT and MR imaging findings

We report CT and MR imaging findings in a case of Castleman's disease involving the retropharyngeal space in a middle-aged woman. On CT scans, a well-marginated, homogeneous, and densely enhancing mass was detected in the right retropharyngeal space. The mass was isointense to the muscle on T1-weighted MR images, hyperintense to the muscle on T2-weighted MR images, and showed homogeneous, strong enhancement on contrast-enhanced T1-weighted MR images. The linear hypointense signal in an arborizing pattern was observed within the mass on all pulse sequences.     

CT and MR imaging of giant cell granuloma of the craniofacial bones

BACKGROUND AND PURPOSE: Giant cell granuloma (GCG) is a rare lesion. The purpose of this study was to determine the CT characteristics and describe possible MR imaging features of GCG of the craniofacial bones. METHODS: We retrospectively reviewed 7 CT studies and 1 MR imaging study of 7 histologically proved cases of GCG in 2 men, 3 women, and 2 patients of unknown gender, aged 12-51 years, during a period of 10 years, from 1995 to 2005. RESULTS: The granulomas predominantly involved the maxilla in 3 patients, the mandible in 2 patients, the temporal bone in 1 patient, and the nasal cavity in 1 patient. These lesions on imaging were expansile masses that demonstrated adjacent bone wall thinning, and most were associated with lytic bone destruction. They were predominantly masses with soft-tissue attenuation on CT scans and may have infiltrated the surrounding soft-tissue structures. The patient with an MR imaging had a lesion that was hypointense on both T1- and T2-weighted MR images. The lesions revealed avid homogeneous contrast enhancement. CONCLUSION: The imaging features of GCG are nonspecific. However, this entity should be included in the differential diagnosis of expansile lesions in the craniofacial bones.     

Middle ear cholesteatoma extending into the petrous apex: evaluation by CT and MR imaging

CT and MR imaging findings were reviewed in four cases of acquired cholesteatoma of the middle ear that extended medially into the petrous apex and middle cranial fossa. In one case the lesion further extended anteromedially into the sphenoid sinus. CT demonstrated the lesions as nonenhancing hypodense masses with bone destruction, extending medially from the middle ear cavity to the petrous apex region. On MR imaging, the lesion was slightly hypointense relative to brain on T1-weighted images and hyperintense on T2-weighted images. MR imaging clearly delineated the extraaxial location of the lesion and associated brain displacement. The medial extension of the cholesteatomas seems to have proceeded via a detour around the bony labyrinth into the petrous apex region by following normal pathways of temporal bone pneumatization.     

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.     

Neuroradiologic-pathologic correlation in a neurenteric cyst of the clivus

A 28-year-old woman presented with left-sided frontotemporal headache lasting 6 wk. Head CT and MR imaging revealed a clival mass, which was interpreted as a chondrosarcoma. The lesion was removed at endoscopic endonasal surgery; histologic and immunohistochemical findings proved it to be neurenteric cyst. On CT scans, the lesion was lytic, with an intact cortex; it was uniformly hyperintense relative to gray matter on T1-weighted MR images and iso- to hypointense relative to CSF on T2-weighted MR images.     

Tongue abscesses: MR imaging findings

BACKGROUND AND PURPOSE: A lingual abscess is difficult to diagnose in the absence of physical signs. MR imaging may provide an excellent and invaluable adjunct to clinical examination, but the literature is incomplete in defining the various MR imaging findings of abscess. The objective of this study was to determine the MR imaging features of tongue abscesses. METHODS: Seven surgically proved tongue abscesses were evaluated with MR imaging. Four patients underwent MR imaging because of suspected tumor, and 3 patients, to show the extent and precise anatomic location of the lesion. Lesions were assessed with regard to the location, size, signal-intensity characteristics, and pattern of contrast enhancement. RESULTS: Five lesions were located in the anterior tongue and 2, in the posterior tongue. The central parts of 4 anterior tongue abscesses were hypointense, surrounded by a hyperintense wall on T1-weighted precontrast images. On postcontrast images, marked wall enhancement was detected. On T2-weighted images, a markedly hyperintense central part surrounded by a hypointense rim was seen. In 2 of these patients, there was a hypointense halo surrounding the wall (target sign). In 3 patients, a perilesional hyperintense area that enhanced diffusely after contrast administration was detected on T2-weighted images. The smallest lesion located in the anterior tongue was hypointense on T1-weighted images and enhanced diffusely on postcontrast images. On T2-weighted images, a markedly hyperintense central part surrounded by a mildly hyperintense peripheral part was depicted. Posterior tongue lesions appeared as polypoid ill-defined masses and were hypointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images. On postcontrast images, the lesion in 1 patient showed diffuse and heterogeneous contrast enhancement, whereas the lesion in another patient enhanced peripherally. The lesions were totally excised in 4 patients and drained with surgical incisions in 3 patients. No recurrence was detected on follow-up. CONCLUSION: An abscess typically presents as a cystic lesion surrounded by an enhancing capsule formation, but lesions may also present as solid masses that enhance diffusely or peripherally.     

T2-weighted MR characteristics of internal auditory canal masses.

PURPOSETo determine whether masses of the internal auditory canal are hypointense relative to cerebrospinal fluid, and therefore visible, on fast spin-echo T2-weighted MR images.METHODSForty-six patients had 50 masses of the internal auditory canal, identified initially on contrast-enhanced MR images, that were evaluated retrospectively for signal intensity of the mass with respect to cerebrospinal fluid and for visibility of the neural elements within the internal auditory canal on T2-weighted images.RESULTSForty-seven of 50 masses were clearly identified on T2-weighted images. Three small abnormalities (2 to 4 mm) were not seen with confidence on T2-weighted images. However, on close inspection of these three masses, the small abnormality on contrast-enhanced MR images corresponded to a hypointense focus on T2-weighted images. All 50 masses were hypointense relative to cerebrospinal fluid on T2-weighted images.CONCLUSIONAll masses of the internal auditory canal in this study were hypointense relative to cerebrospinal fluid on T-2 weighted images, and were therefore visible.     

MR imaging of adrenal myelolipomas

The magnetic resonance (MR) images in six patients with seven adrenal myelolipomas are presented. Four lesions involved the right gland, and three the left; they ranged from 3 to 12.5 cm in diameter. Magnetic resonance was able to image all lesions. Using T1-weighted sequences, three structural patterns were observed; (a) homogeneous masses with intensity equal to adjacent fat (three cases); (b) heterogeneous masses with fat intensity areas and areas similar to renal cortex (two cases); and (c) nodules quite different from fat, hypointense to the liver (two cases). On T2-weighted images, myelolipomas were slightly hypointense to fat and either hypo- or isointense to the liver. A comparison with the results of CT studies was possible in all cases, and good correlation with determination of the presence and quantity of fat density tissues within the lesions was observed. However, MR imaging did not seem to help in diagnosing adrenal myelolipoma in patients with equivocal CT findings, and needle biopsy is still needed in difficult cases.     

Evolution of central necrosis in a meningioma: CT and MR features

A 44-year-old patient underwent CT and magnetic resonance (MR) imaging and was found to have a typical appearing meningioma. The meningioma was of increased density relative to brain and enhanced homogeneously on CT. It was slightly hypointense on T1-weighted MR images and isointense on T2-weighted MR images relative to cortex. Thirty days later, repeat CT and MR scans showed change of the tumor consistent with central necrosis. An area of central low density developed on the CT scans, and a central high signal developed on the T2-weighted MR images. Pathological sectioning confirmed central necrosis of a syncytial meningioma.     

Granular cell myoblastoma of the cervical esophagus: MR findings.

Granular cell myoblastomas are uncommon, typically benign tumors. Involvement of the esophagus is rare, and frequently they are asymptomatic. We report a granular cell myoblastoma involving the cervical esophagus in a patient who had paralysis of the true vocal cord and progressive dysphagia. At MR imaging, the circumscribed mass was hypointense on T1-weighted images and mildly hyperintense on T2-weighted images, with homogeneous contrast enhancement.     

Infantile fibromatosis of the neck with intracranial involvement: MR and CT findings.

CT and MR imaging studies were performed in a 3-year-old boy with infantile fibromatosis arising from the infratemporal fossa and extending into the middle cranial fossa. On CT scans, the lesion was hyperattenuating (44-49 Hounsfield units [HU]), enhancing significantly after application of contrast material (63-66 HU). The MR images showed a multilobulated lesion of heterogeneous signal intensity. The tumor was markedly hypointense on T2-weighted images and slightly hypointense on T1-weighted images relative to brain tissue, iso- or slightly hyperintense relative to tongue muscle on both T2- and T1-weighted images, and enhanced strongly after administration of gadopentetate dimeglumine.     

Supratentorial Gangliocytoma Mimicking Extra-axial Tumor: A Report of Two Cases

We report two cases of supratentorial gangliocytomas mimicking an extra-axial tumor. MR imaging indicated that the tumors were extra-axial, and meningiomas were thus initially diagnosed. Relative to gray matter, the tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. On contrast-enhanced T1-weighted images, homogeneous enhancement was observed, while CT scanning revealed calcification in one of the two cases.     

CT and MR findings of basal cell adenoma of the parotid gland

We report a case of basal cell adenoma in the left parotid gland. A 34-year-old woman presented with a non-tender mass in the left parotid gland. She had first noted it 7- years previously, and it had been gradually increasing in size. The tumor was well-circumscribed with a smooth contour. On noncontrast-enhanced CT, the tumor showed homogeneous soft tissue attenuation. No cystic portion or calcification was seen. The tumor showed homogeneous moderate enhancement on contrast-enhanced CT. Capsule-like ring enhancement was demonstrated. On T1-weighted MR imaging, the tumor was homogeneously hypointense to the surrounding parotid tissue and isointense to muscle. On T2-weighted imaging the tumor was homogeneously hyperintense to muscle but slightly hypointense to the surrounding parotid tissue. On Gd-enhanced T1-weighted imaging, the tumor demonstrated homogeneous moderate enhancement. Capsule-like ring enhancement was also demonstrated. Salivary (technetium-99m-pertechnetate) scintigraphy did not show any uptake in the tumor.     

Intraocular tumors: evaluation with MR imaging

Sixty-seven ocular tumors were studied with magnetic resonance (MR) imaging and computed tomography (CT). These tumors included primary uveal melanoma (n = 55), circumscribed choroidal hemangioma (n = 3), diffuse choroidal hemangioma (n = 1), retinal capillary hemangioma (n = 1), medulloepithelioma (n = 1), choroidal nevus (n = 1), retinoblastoma (n = 1), and choroidal metastases (n = 4). MR imaging demonstrated all these lesions, while CT demonstrated 88%. Associated retinal detachment was more easily distinguished from the neoplasms with MR imaging. Extrascleral extension of melanoma and hemorrhagic cystic necrosis within the melanoma were clearly demonstrated with MR imaging, but not with CT. Ninety-three percent of melanomas were markedly hyperintense, compared with the intensity of the vitreous body, on T1-weighted images and hypointense on T2-weighted images. All metastatic lesions were isointense on T1-weighted images and hypointense on T2-weighted images. The circumscribed choroidal hemangiomas were hyperintense on T1-weighted images and isointense on T2-weighted images. MR imaging is superior to CT in detection of intraocular tumors and may be more specific in diagnosis.     

Metastatic liver tumor from cystic ovarian carcinomas: CT and MRI appearance.

OBJECTIVE: The initial and follow-up CT and MRI images of ten patients with hepatic metastases from ovarian tumors were retrospectively analyzed to establish their features and sequential changes in appearance. MATERIALS AND METHODS: Ten patients with hepatic metastasis from ovarian tumors received initial and follow-up CT and MRI examinations. Six patients were followed up every two to three weeks before surgical tumor resection. Both CT and MR images were analyzed by two radiologists. RESULTS: A total of fourteen lesions were detected by CT and MRI in 10 patients. All 14 lesions were demonstrated as areas of marked hyperintensity on T2-weighted MRI. Eleven cyst-like tumors were demonstrated as round or oval low density lesions on CT and as areas of hypointensity on T1-weighted imaging. Three lesions were shown as solid masses with slightly low attenuation at the initial CT examination and slightly low or iso-intensity areas on T1-weighted imaging, and these lesions showed early peripheral globular enhancement and delayed enhancement on contrast-enhanced CT and MR imaging. Cystic formation was observed two to three weeks later after initial study in all the 3 solid lesions. Rapid subcapsular effusion, which showed obvious enhancement on delayed Gd-DTPA enhanced MR imaging, was observed in two patients. CONCLUSION: The hepatic metastatic tumor from cystic ovarian carcinoma may manifest as a well-defined cystic lesion or as a solid mass, and the solid mass shows delayed enhancement on contrast-enhanced CT and MR imaging. Furthermore, rapid cystic formation and rapid subcapsular extension is frequently seen.     

Hibernoma of the left axilla; a case report and review of MR imaging

We present a case of a hibernoma arising from the left axilla in a 24-year-old woman. The imaging characteristics on both contrast-enhanced CT (attenuation similar to surrounding skeletal muscle) and T1-weighted MR imaging (signal intensity intermediate between those of skeletal muscle and subcutaneous fat) were inconsistent with a fatty mass. The diagnosis of hibernoma was only made after marginal excisional biopsy, which confirmed the presence of brown fat on histologic analysis. We briefly present the imaging findings in our case and compare the imaging characteristics of previously reported hibernomas. Although hibernomas classically contain brown fat, imaging characteristics on T1-weighted images typically demonstrate a mass that is hypointense to adjacent subcutaneous fat. Knowledge of its MR imaging characteristics may help to suggest hibernoma in the preoperative diagnosis, although other tumors should still be considered in the differential diagnosis     

Kikuchi disease: CT and MR findings.

Two cases of Kikuchi disease showed variable nodal enhancing features, including homogeneous enhancement and focal or extensive nodal necrosis on contrast-enhanced CT scans. At MR imaging, the area of central necrosis was isointense or hypointense on T1-weighted images and had a lower signal than nonnecrotic areas on T2-weighted images. The CT appearance of Kikuchi disease can be variable and can mimic not only lymphoma but various nodal diseases with nodal necrosis, including metastasis and tuberculosis.