This article reviews MRI findings of parasitic diseases of the central nervous system (CNS), with emphasis on neurocysticercosis, which is by far the most common CNS parasitic infection worldwide. MRI findings of neurocysticercosis are various, depending on the location (parenchymal, cisternal, ventricular, and spinal forms), and temporal evolutional stages (vesicular, colloid vesicular, granular nodular, and nodular calcified stages) of the worm. Classical findings of each location and stage are presented. Characteristic MRI findings of cerebral toxoplasmosis frequently seen in patients with acquired immunodeficiency syndrome (AIDS), paragonimiasis, and sparganosis that have most commonly been reported in East Asia are also illustrated. MRI is superior to CT scan in the evaluation of most CNS parasitic infections and is nearly diagnostic, particularly in endemic areas. Contrast-enhanced study is essential not only for specific diagnosis of the disease, but also for assessment of the inflammatory activity.

Amebiasis↗

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Nontraumatic prolapse of the orbital contents into the ethmoid sinus: evaluation with screening sinus CT.

PURPOSE: The purpose of this study is to evaluate the incidence and CT features of nontraumatic prolapse of the orbital content into the ethmoid sinus, which may be a cause of orbital complication of ethmoidectomy. MATERIALS AND METHODS: CT of 1,024 consecutive patients with subjective sinonasal symptoms who underwent screening sinus CT were reviewed and analyzed. The 573 men and 451 women were between the ages of 5 and 79 years old. The patients with a history of sinus surgery of facial trauma were excluded from this study. The incidence and CT features of dehiscence and/or bowing of the lamina papyracea with prolapse of the orbital content in each age group and differences between the age groups were analyzed. RESULTS: Ethmoidal prolapse of the orbital content was found in 67 patients (6.5%). There was a tendency of increasing incidence with increasing age. The incidence in the juvenile age group was significantly low (1.9%) as compared with that of adult. Four patients (0.4%) had bilateral lesions. Twenty-nine lesions showed prolapse of moderate to severe degree, and deformity of the medial rectus muscle on coronal CT image was associated in 21 lesions. Inflammatory change of adjacent ethmoid sinus was indicated in 19 lesions, and there was no statistical difference in incidence from that of the opposite side. CONCLUSIONS: The incidence of nontraumatic prolapse of the orbital content is far beyond general expectations, and detailed structural information with CT for this anatomic alteration may be important before endoscopic sinus surgery to avoid possible complication. The higher incidence in adult may suggest age-related acquired etiologic factors besides congenital dehiscence or weakness of the lamina papyracea.

Adolescent↗

PubMedDate not supplied

Progeroid syndrome: association with connective tissue disease?

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Connective Tissue Diseases↗

PubMedDate not supplied

Malignant melanoma of the sinonasal cavity: explanation of magnetic resonance signal intensities with histopathologic characteristics.

PURPOSE: To evaluate the magnetic resonance (MR) findings of malignant melanoma of the sinonasal cavity and compare these findings with those of the histopathological examination. MATERIALS AND METHODS: The MR images of 11 patients with malignant melanoma of the sinonasal cavity were retrospectively reviewed. Ten patients had primary malignant melanoma of the sinonasal cavity and one had a local recurrence. The imaging findings were evaluated with special attention given to the signal intensity of the tumor, internal characteristics, and growth pattern on MR. Signal intensity and enhancement patterns of the tumors were compared with the histopathological findings. RESULTS: On T1-weighted image, 6 tumors were hyperintense (5 melanotic and one amelanotic melanoma), and 5 tumors were isointense or hypointense (4 amelanotic and one melanotic). On T2-weighted images, 2 amelanotic tumors showed hyperintensity, and 5 melanotic tumors showed hypointensity. Four tumors (one melanotic and 3 amelanotic) were isointense. Four of the 7 tumors with hyperintensity on T1-weighted images showed patchy, higher-signal intensity areas. In 3 of them, patchy areas of a higher degree of pigmentation were found on histopathological examination. There were multiple linear dark signal intensities on T2-weighted images and/or linear-enhancing areas on enhanced T1-weighted images within the masses in 5 of the 11 patients. These findings could be explained as intratumoral vessels in 4 tumors and fibrous septa in one tumor on histopathological examinations. CONCLUSION: Malignant melanoma of the sinonasal cavity shows characteristic MR signal intensity, which is mainly attributable to the degree and distribution of melanin pigmentation, and partly attributable to hemorrhage within the mass. The linear, low-signal intensity on T2-weighted images or enhanced lines are intratumoral vessels or fibrous septa.

Adult↗

PubMedDate not supplied

Non-Hodgkin lymphoma of the central skull base: MR manifestations.

OBJECTIVE: The aim of this study was to demonstrate the MR characteristics of non-Hodgkin lymphoma of the skull base to help in the differential diagnosis of this neoplasm from other conditions. MATERIALS AND METHODS: MR of five patients, 7-64 years old, with pathologically proved lymphomas of the skull base were reviewed. Three cases had primary skull base lesions involving the sphenoid bone and the cavernous sinus. One case with a nasal cavity lesion involving the skull base and one with a relapsing skull base lesion of previously treated tonsillar lymphoma were included. RESULTS: The lesions had signal intensities that were similar to that of gray matter of brain on both T1- and T2-weighted imaging. Bilateral cavernous sinuses were involved with encasement of internal carotid arteries in every case. Postcontrast MR showed homogeneous enhancement of the tumor with dural infiltration along the planum sphenoidale, clivus, or tentorium. The clivus was destroyed or replaced by tumors in adult cases but in two children the clivus was preserved with intact sphenooccipital synchondrosis. In one case the tumor extended to the extracranial portion through the jugular foramen. CONCLUSION: The MR findings of a permeative lesion of the skull base, invasion of the cavernous sinus without arterial narrowing, infiltration along the dural surface, and an iso- or hypointensity with brain on T2-weighted imaging should suggest lymphoma.

Cavernous Sinus↗

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Primary adenoid cystic carcinoma of the cervical trachea mimicking thyroid tumor: CT evaluation.

OBJECTIVE: Our goal was to describe the CT characteristics of adenoid cystic carcinomas of the trachea mimicking thyroid tumors. MATERIALS AND METHODS: Computed tomography of four patients with pathologically proved adenoid cystic carcinomas extending into the thyroid gland was retrospectively reviewed. One case was also examined with MR. RESULTS: The masses encircling the trachea and circumferential thickening of the tracheal wall were demonstrated in all four cases. The longitudinal extent of the tracheal wall thickening was also demonstrated in all cases. The tumors had a broad base on the trachea and convex margin on the thyroid gland. They were all homogeneous, generally smoothly marginated, and isoattenuating on postcontrast CT scans. CONCLUSION: Adenoid cystic carcinomas were usually seen on CT scans as homogeneous masses encircling the posterolateral trachea with thickening of the tracheal wall in the transverse and longitudinal planes. These CT characteristics may be helpful in the differential diagnosis of adenoid cystic carcinomas mimicking thyroid tumors.

Adult↗

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Prolonged ictal amnesia with transient focal abnormalities on magnetic resonance imaging.

A previously healthy woman had a prolonged amnestic state caused by complex partial status epilepticus with bilateral mesiotemporal lobe involvement confirmed by EEG with nasopharyngeal electrodes. A magnetic resonance imaging (MRI) scan obtained shortly after recovery from the amnesia showed reversible focal abnormalities consisting of increased signal intensity on T2-weighted scan in the mesiotemporal lobe.

Adult↗

PubMedDate not supplied

CT and MR imaging of head and neck tuberculosis.

Tuberculosis of the head and neck can involve the cervical lymph nodes, larynx, temporal bone, sinonasal cavity, eye, pharynx, thyroid gland, and skull base. Although computed tomography (CT) and magnetic resonance (MR) imaging can accurately demonstrate the sites, pattern, and extent of the disease, both modalities have limitations in the evaluation of head and neck tuberculosis. Imaging and clinical features of head and neck tuberculosis are often varied and nonspecific and frequently mistaken for those of carcinoma. However, tuberculous lymphadenitis is often characterized by areas of low attenuation or low signal intensity with rim enhancement or calcification, and laryngeal tuberculosis usually manifests as a diffuse bilateral lesion with or without a focal mass. A thorough knowledge of head and neck tuberculosis is important because early diagnosis and therapy may prevent a permanent loss of function or needless surgery.

Adolescent↗

PubMedDate not supplied

Usefulness of single voxel proton MR spectroscopy in the evaluation of hippocampal sclerosis.

OBJECTIVE: The purpose of our study was to determine the ability of H-1 MR spectroscopy (MRS) to lateralize the lesion in patients with hippocampal sclerosis. MATERIALS AND METHODS: Twenty healthy volunteers and 25 patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis were included. This diagnosis was based on the presence of unilateral atrophy and/or high T2 signal intensity of the hippocampus. Singlevoxel H-1 MRS was carried out on a 1.5-T unit using PRESS sequence (TE, 136 msec). Spectra were obtained from hippocampal areas bilaterally with volumes of interest (VOIs) of 6.0 cm(3) and 2.25 cm(3) in healthy volunteers, and of either 6.0 cm(3) (n = 14) or 2.25 cm(3) (n = 11) in patients. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from relative peak height measurements. The capability of MRS to lateralize the lesion and to detect bilateral abnormalities was compared with MR imaging diagnosis as a standard of reference. RESULTS: In healthy volunteers, NAA/Cho and NAA/Cr ratios were greater than 0.8 and 1.0, respectively. In patients, the mean values of these ratios were significantly lower on the lesion side than on the contralateral side, and lower than those of healthy volunteers (p <.05). The overall correct lateralization rate of MRS was 72% (18/25); this rate was lower with a VOI of 6.0 cm(3) than of 2.25 cm(3) (64% versus 82%, p <.05). Bilateral abnormalities on MRS were found in 24% (6/25) of cases. CONCLUSION: Although its rate of correct lateralization is low, single-voxel H-1 MRS is a useful and promising diagnostic tool in the evaluation of hippocampal sclerosis, particularly for the detection of bilateral abnormalities. To improve the diagnostic accuracy of H-1 MRS, further investigation, including the use of a smaller VOI and measurement of the absolute amount of metabolites, are needed.

Adult↗

PubMedDate not supplied

Radiologic-pathologic correlation of unusual lingual masses: Part I: congenital lesions.

Because the tongue is superficially located and the initial manifestation of most diseases occurring there is mucosal change, lingual these lesions can be easily accessed and diagnosed without imaging analysis. Most congenital lesions of the tongue, however, can manifest as a submucosal bulge and be located in a deep portion of that organ 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. In addition, because it is usually difficult to differentiate congenital lesions from other submucosal neoplasms on the basis of imaging findings alone, clinical history and physical examination should always be taken into consideration when interpreting CT and MR images of the tongue. Although the radiologic findings for congenital lesions are nonspecific, CT and MR imaging can play an important role in the diagnostic work-up of these unusual lesions. 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.

Bronchogenic Cyst↗

PubMedDate not supplied

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 lesions can 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.

Carcinoma, Adenoid Cystic↗

PubMedDate not supplied

Hippocampal sclerosis: correlation of MR imaging findings with surgical outcome.

OBJECTIVE: Atrophy and a high T2 signal of the hippocampus are known to be the principal MR imaging findings of hippocampal sclerosis. The purpose of this study was to determine whether or not individual MRI findings correlate with surgical outcome in patients with this condition. MATERIALS AND METHODS: Preoperative MR imaging findings in 57 consecutive patients with pathologically-proven hippocampal sclerosis who underwent anterior temporal lobectomy and were followed-up for 24 months or more were retrospectively reviewed, and the results were compared with the postsurgical outcome (Engel classification). The MR images included routine sagittal T1-weighted and axial T2-weighted spin-echo images, and oblique coronal T1-weighted 3D gradient-echo and T2-weighted 2D fast spin-echo images obtained on either a 1.5 T or 1.0 T unit. The images were visually evaluated by two neuroradiologists blinded to the outcome; their focus was the presence or absence of atrophy and a high T2 hippocampal signal. RESULTS: Hippocampal atrophy was seen in 96% of cases (55/57) [100% (53/53) of the good outcome group (Engel class I and II), and 50% (2/4) of the poor outcome group (class III and IV)]. A high T2 hippocampal signal was seen in 61% of cases (35/57) [62% (33/53) of the good outcome group and 50% (2/4) of the poor outcome group]. All 35 patients with a high T2 signal had hippocampal atrophy. 'Normal' hippocampus, as revealed by MR imaging, occurred in 4% of patients (2/57), both of whom showed a poor outcome (Engel class III). The presence or absence of hippocampal atrophy correlated well with surgical outcome (p<0.01). High T2 signal intensity did not, however, significantly correlate with surgical outcome (p>0.05). CONCLUSION: Compared with a high T2 hippocampal signal, hippocampal atrophy is more common and correlates better with surgical outcome. For the prediction of this, it thus appears to be the more useful indicator.

Adult↗

PubMedDate not supplied

Unusual acute encephalitis involving the thalamus: imaging features.

OBJECTIVE: To describe the brain CT and MR imaging findings of unusual acute encephalitis involving the thalamus. MATERIALS AND METHODS: We retrospectively reviewed the medical records and CT and/or MR imaging findings of six patients with acute encephalitis involving the thalamus. CT (n=6) and MR imaging (n=6) were performed during the acute and/or convalescent stage of the illness. RESULTS: Brain CT showed brain swelling (n=2), low attenuation of both thalami (n=1) or normal findings (n=3). Initial MR imaging indicated that in all patients the thalamus was involved either bilaterally (n=5) or unilaterally (n=1). Lesions were also present in the midbrain (n=5), medial temporal lobe (n=4), pons (n=3), both hippocampi (n=3) the insular cortex (n=2), medulla (n=2), lateral temporal lobe cortex (n=1), both cingulate gyri (n=1), both basal ganglia (n=1), and the left hemispheric cortex (n=1). CONCLUSION: These CT or MR imaging findings of acute encephalitis of unknown etiology were similar to a combination of those of Japanese encephalitis and herpes simplex encephalitis. In order to document the specific causative agents which lead to the appearance of these imaging features, further investigation is required.

Acute Disease↗

PubMedDate not supplied

Diffusion-weighted MR imaging in biopsy-proven Creutzfeldt-Jakob disease.

OBJECTIVE: To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. MATERIALS AND METHODS: We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. RESULTS: Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluid-attenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. CONCLUSION: Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.

Adult↗