MR imaging of neurocysticercosis

Twenty-six patients with neurocysticercosis were studied with MR imaging to correlate their clinical presentation with the location and appearance of their neurocysticercosis lesions. Intraventricular cysts were present in 14 patients (54%), parenchymal cysts were present in 18 (69%), and intraventricular together with parenchymal cysts were present in six (23%). Intraventricular cysts were detected by mass effect, ventricular obstruction, detection of a cyst rim, and/or CSF flow void adjacent to the cyst. The intensity of most intraventricular and parenchymal cysts presumed to be viable was similar to that of CSF on both T1- and T2-weighted sequences. Cysts presumed to be degenerated had increased signal intensity on T1-weighted images, probably resulting from increased protein content. Pericystic high signal intensity surrounding lesions of various ages was seen on both proton-density- and T2-weighted images and represents gliosis, edema, and inflammation. Patients with parenchymal cysts had symptoms of seizures, while those with intraventricular cysts generally had symptoms related to obstructive hydrocephalus. Aqueductal stenosis, seen in 10 patients (38%), was possibly due to ependymal inflammation or adhesions caused by prior ventricular infection by neurocysticercosis. One patient with the racemose form of neurocysticercosis demonstrated abundant cyst wall proliferation resulting in obstructive hydrocephalus. In six patients scanned 1-6 months after oral praziquantel therapy, there was no change in the MR appearance of intraventricular cysts, while some parenchymal cysts showed evidence of degeneration. We found MR to be useful in detecting the cysts of neurocysticercosis and the accompanying signs of cyst degeneration and pericystic inflammation. MR was inferior to CT in the detection of parenchymal calcifications.     

MR imaging of intracranial cysticercosis: comparison with CT and anatomopathologic features

Eight patients with neurocysticercosis were studied with CT and magnetic resonance (MR) imaging. Two cysts were shown better with MR than with CT. A conspicuous, high-intensity mural nodule containing the scolex allowed specific identification of intraventricular and parenchymal cysticerci. CT evidence of calcification and metrizamide enhancement in the nodule was also noted in one case. Racemose cysts were seen in the cerebellopontine angle and under the anterior septum pellucidum. Fluid in apparently live cysticerci and in racemose cysts had MR signal properties closely paralleling CSF. A thin subependymal or subpial rim of high signal intensity around the intraventricular and one of the racemose cysts was consistent with tissue reaction and aided diagnosis. While MR showed only one of numerous calcifications, it may be more sensitive than CT in the recognition of perifocal edema and of parenchymal and subarachnoid cysts, may replace invasive ventriculography in the diagnosis of intraventricular cysts, and may be useful in determining the viability of cysts and their response to therapy.     

脑囊虫病的MRI诊断

目的：评价脑囊虫病磁共振表现。材料和方法：对9例脑囊虫病MRI回顾性分析。结果：9例中7例可见明显的囊虫结节，1例合并右大脑中动脉闭塞，1例合并蛛网膜下腔囊虫。另2例中，1例表现为白质脱髓鞘改变，1例表现为两顶叶肉芽肿样改变。结论：脑囊虫病分四型、四期。四型包括脑实质型、脑室型、软脑膜型及混合型。四期包括存活期、退变期、坏死期及钙化期。脑实质型MRI较具特征性，可见典型的囊虫结节，即圆形或类圆形、大小约1～10毫米的囊性病灶，其内有偏心或附壁的囊虫头节。存活期囊虫结节MRI表现为囊液T1WI信号与CSF相同，大部分可见偏心或附壁的头节，无囊壁可见，无明显水肿。退变、坏死二期MRI难于区分，此时表现为囊液T1WI信号略高于CSF并随病程延长而信号逐渐增高，囊壁逐渐增厚，一般无头节可见，增强可表现为环状及结节状强化，周围水肿明显。钙化期CT比MR优越。     

Cysticercosis of the brain shown by magnetic resonance imaging

Fifteen patients in whom the diagnosis of cysticercosis of the brain was suggested by computed tomography (CT) were further studied with magnetic resonance imaging (MRI). Besides lesions in the substance of the hemispheres, cysts were found adjacent to and within the ventricles, the brainstem, cerebellum and subarachnoid space. Magnetic resonance imaging showed brain involvement out of proportion to what was shown by CT. The eccentrically placed mural nodule within a cyst, the pathognomonic lesion of cysticercosis, was seen in all cases with MRI. The various stages of development of the cysticercus larva were seen in one individual. An attempt is made to illustrate the various stages of development by means of MR images, and a possible pathological explanation is offered. The authors believe that MRI provides diagnostic information in this disease and dispenses with the need for enhanced CT examination.     

MR imaging of intraventricular cysticercosis

Three cases of cysticercosis with cysts located in the cerebral ventricles were studied with magnetic resonance (MR) imaging. This technique proved to be diagnostically superior to CT. In fact, MR can effectively replace metrizamide CT ventriculography in the detection of intraventricular cysticercosis.     

Computed tomography in intracranial cysticercosis

The computed tomography (CT) scans and other radiographic studies of 23 patients with cerebral cysticercosis were reviewed. Parenchymal calcifications, the most common finding, are somewhat better seen on CT scans than on skull films. Ventricular cysts may be suspected by disproportionate enlargement of the involved ventricle. Cysts in subarachnoid cisterns are best detected by performing both CT and pneumoencephalography. Contrast enhancement was not seen with cisternal or ventricular cysts but may be with parenchymal cysticercus lesions.     

血管母细胞瘤的CT、MRI表现

目的:探讨血管母细胞瘤的CT和MRI影像学特征。方法:回顾性分析37例血管母细胞瘤的CT和MRI表现,25例行CT平扫和增强扫描,其中2例行CTA三维重建。14例行MRI检查,其中2例作MRI平扫,12例作MRI平扫加增强,其中1例3D TOF MRA检查。结果:37例共43个病灶。35例单发病灶中,发生于小脑半球者23例,小脑蚓部9例,第四脑室1例,延髓背侧1例,左桥小脑角区1例。其中囊结节型29例,实质型3例,囊实型2例,单纯囊性1例。2例为多发病灶,均位于后颅窝,其中1例有6处病灶,实质型和囊结节型混合存在。CT平扫囊结节型肿瘤壁结节显示率仅为54.6%。增强扫描壁结节及实质型、囊实型肿瘤均明显均匀或不均匀强化;23.1%显示肿瘤周围有增粗迂曲的血管。CTA示肿瘤为富血管的团块。MRI平扫肿瘤壁结节显示率100%。肿瘤周围流空血管显示率达57.9%。与CT比较此两项指标差异有统计学意义。增强扫描示壁结节及实质型、囊实型肿瘤明显均匀或不均匀强化。MRA显示肿瘤区域丰富的紊乱血管。结论:CT、MRI可作为血管母细胞瘤的首选检查方法。     

Cystic intracranial lesions: magnetic resonance imaging

Thirty-three patients with cystic intracranial lesions were examined with both magnetic resonance (MR) imaging and CT scanning. The abnormalities imaged included 11 arachnoid cysts, 10 cystic tumors, six postoperative cysts, and three colloid cysts. The intensity patterns of the cyst contents as encoded with routine spin-echo imaging sequences enabled subdivision of the cysts into three categories. Arachnoid and postoperative cysts had an intensity pattern identical to cerebrospinal fluid. More proteinaceous cysts, including inflammatory cysts and nonhemorrhagic tumoral cysts, had an intermediate intensity pattern with characteristically low intensity on the short TR sequence (0.5 sec), but had clearly higher intensity than cerebrospinal fluid on the long TR sequences (2 sec). Finally, three cystic tumors with hemorrhagic fluid and three colloid cysts had a distinctly different pattern of high intensity on all four MR sequences through the same section. MR was superior to CT in characterizing intracranial cystic lesions because of its ability to categorize cysts into these three groups on the basis of the intensity pattern of cyst contents, thereby improving diagnostic specificity and patient management.     

Pyruvate: an in vivo marker of cestodal infestation of the human brain on proton MR spectroscopy

PURPOSE: To study intracranial cestodal cysts using in vivo proton magnetic resonance spectroscopy ((1)H MRS) in an effort to identify metabolite(s) that may help in recognizing the parasitic etiology and, perhaps, viability of such tapeworm cysts. Cestodal infestations of the human central nervous system (CNS)-cysticercosis and hydatidosis-are not rare. Identification of a scolex is considered diagnostic of cysticercosis on imaging. In its absence, however, the features are non-specific. MATERIALS AND METHODS: Three patients with intracranial hydatid cysts and 13 patients with intracranial cysticercal cysts (four intraventricular, seven parenchymal, and two subarachnoid racemose cysts) were studied on a 1.5-T MR system. In vivo (1)H MRS was performed by multivoxel two-dimensional hybrid chemical shift imaging technique (TE = 135 msec). In vitro (1)H NMR and mass spectroscopy (matrix assisted laser desorption/ionization [MALDI]) were performed on excised cysticercal and hydatid cyst fluid. MALDI spectra for pyruvate and succinate were also obtained. RESULTS: Alanine, pyruvate, and acetate were seen in all the three hydatid cysts. Lactate was seen in racemose cysticercal cysts. A large resonance at 2.4 ppm, confirmed as pyruvate at mass spectroscopy, was seen in 13 cestodal cysts. Pyruvate was not seen in one each of racemose, intraventricular, and parenchymal cysticercal cysts. CONCLUSION: Pyruvate is the predominant metabolite in cestodal cysts infesting the human CNS. It may be a marker of parasitic etiology and perhaps that of viability of such intracranial cysts.     

Complex renal cysts: findings on MR imaging.

OBJECTIVE: We retrospectively evaluated our experience with complex cystic renal masses on MR imaging, using T1-weighted, T2-weighted, and gadolinium-enhanced images, to determine whether imaging features could permit distinction between benign and malignant lesions. MATERIALS AND METHODS: Thirty-seven patients with complex cystic renal lesions were included in this retrospective study. The patients selected had undergone T1-weighted, T2-weighted, and gadolinium-enhanced MR imaging examinations using 1.5-T scanners, with at least one of the following findings: cyst fluid of heterogeneous signal intensity, mural irregularity, septa, mural masses or nodules, increased mural thickness, or intense mural enhancement. The diagnosis was established by histology in 19 patients and by follow-up studies in the remaining 18 patients. RESULTS: Fifty-five complex renal cystic lesions were present in the 37 patients. Among the 55 lesions, of 37 that contained fluid of a heterogeneous signal intensity, eight were malignant (22%); of 16 with irregular walls, 10 were malignant (63%); of four with septa, two were malignant (50%); of four with mural masses or nodules, three were malignant (75%); of 14 with a thick wall (>2 mm), 10 were malignant (71%); and of 32 with intense mural enhancement, 14 were malignant (44%). As independent variables, mural irregularity, mural masses or nodules, increased mural thickness, and intense mural enhancement each were highly associated with malignancy (p = .0003-.0022). The combination of mural irregularity and intense mural enhancement had the highest correlation with malignancy (p = .0002). CONCLUSION: The combination of mural irregularity and intense mural enhancement is a strong predictor of malignancy in renal cystic lesions. However, the appearance of benign and malignant lesions may overlap, suggesting that distinct separation of these entities is not currently possible in all cases with MR imaging.     

Neurocysticercosis

The neurocysticercosis is an infestation of the central nervous system by larvae of Taenia solium. The disease is endemic in a few countries of Latin America, Asia, and Africa and is becoming increasingly prevalent in the United States and Europe. The immigration of individuals from endemic areas and the tourism in these areas require a good knowledge of this disease. A retrospective study evaluating the neurocysticercosis lesions with MR and CT is proposed. Parenchymal, subarachnoid and intraventricular cysts are evaluated. We were able to recognise four CT and MR stages. MR was useful in detecting the cysts of neurocycticercosis in the first stage but was inferior in the detection of parenchymal calcifications.     

Intraventricular cysticercal cysts: further neuroradiologic observations and neurosurgical implications

Intraventricular cysticercosis is potentially lethal. Six of 46 patients died from acute hydrocephalus shortly after hospital admission. The need for early computed tomographic scanning in immigrants from endemic areas complaining of headaches is emphasized by this experience. If time has elapsed since the initial diagnosis, these cysts may migrate within the ventricular system. Reconfirmation of the location of an intraventricular cysticercal cyst is advisable before surgery. Contrast enhancement of an intraventricular cysticercal cyst implies associated granular ependymitis. Surgical removal of such cysts probably should not be attempted as long as the cysts are not causing significant mass effect with neurologic signs and symptoms. Shunting alone is advocated for the treatment of hydrocephalus.     

Neuroepithelial cysts of the lateral ventricles: MR appearance

The MR imaging appearance of neuroepithelial cysts in the lateral ventricle is reported. Two cases of proven and two of presumed intraventricular neuroepithelial cysts are presented. In one case, MR observations documented spontaneous regression of a large intraventricular cyst. Theories regarding the origin of neuroepithelial cysts are briefly reviewed. Standard T1- and T2-weighted spin-echo pulse sequences were used to study cysts in the lateral ventricles in axial, coronal, and sagittal planes. The cyst wall can be demonstrated reliably with MR images, eliminating the need for CT and/or contrast ventriculography. MR may also be useful in monitoring cyst size on serial examinations.     

MR findings in thyroglossal duct cysts: report of two cases

Two patients with thyroglossal duct cysts have been studied with CT and MR. The typical CT feature of these cystic upper-neck lesions are depicted in literature, conversely MR findings are not well known. The homogeneous high intensity on T1-weighted images, higher than simple cyst or fluid, is the most typical feature of the thyroglossal cyst.     

Complex and simple renal cysts: comparative evaluation with MR imaging

Magnetic resonance (MR) imaging was performed in two groups of patients to determine its usefulness in evaluating fluid-containing renal masses deemed complex with computed tomography (CT). Twenty-two patients in group 1 had indeterminate renal masses by CT, five of which were also indeterminate by ultrasound (US). The results in this group were compared with histologic findings. Group 2 consisted of 20 patients with simple renal cysts diagnosed according to rigid CT criteria. On MR imaging, 11 of the 23 masses in group 1 and 19 of the 20 in group 2 were diagnosed as benign cysts. Fluid within the cyst had long T1 and T2, resulting in a low signal intensity on T1-weighted images. In the 12 remaining lesions in group 1 and in one lesion in group 2, the fluid content was indeterminate and MR did not permit differentiation of cystic renal carcinoma from old hemorrhage or adenoma. When fluid within the cystic mass did not have the MR characteristics of simple fluid, MR was not helpful in characterizing the mass, but when the fluid intensity was similar to normal urine, the cyst was benign.     

Optic nerve cysticercosis: imaging findings

We present the imaging findings of retrobulbar optic nerve cysticercosis in a 50-year-old woman with a 6-month history of vision loss. Contrast-enhanced CT revealed an approximately 7-mm ring-enhancing cyst with a mural nodule located in the anterior portion of the left optic nerve. A contrast-enhanced MR imaging study revealed a cystic lesion with peripheral enhancement of the mural nodule. Sonography showed a cystic mass with a focal area of increased echogenicity corresponding to the mural nodule.     

Rathke cleft cysts: CT, MR imaging, and pathologic features

The authors retrospectively reviewed the clinical, computed tomography (CT), and magnetic resonance (MR) imaging findings in seven patients with pathologically proved Rathke cleft cysts. All the cysts were located in the anterior sella turcica or the anterior suprasellar cistern. Five cysts had both intra- and suprasellar components, one was entirely intrasellar, and the other was predominantly suprasellar in location. The size of the cysts ranged from 8 to 20 mm. CT scans demonstrated low-density homogeneous lesions in four cases. On MR images of three of these four cases, the cysts had the same intensity as cerebrospinal fluid on T1- and T2-weighted images, while in the fourth case, the cyst was hyperintense on the T1-weighted images. In the remaining three cases, CT showed slight hyperdensity relative to brain parenchyma, suggestive of contrast enhancement. MR showed signal heterogeneity of these lesions with focal components of diminished signal intensity of T2-weighted images. These same foci appeared iso- to slightly hyperintense on T1-weighted images.     

Unusual imaging appearance of an intracranial dermoid cyst.

Intracranial dermoid cysts have characteristic CT and MR imaging findings that generally make preoperative diagnosis straightforward. Enhancement of uncomplicated intradural dermoid cysts on CT or MR studies has been reported but is rare. We present a case of a posterior fossa dermoid cyst that was not only hyperattenuating on CT scans but also contained a mural nodule with clear evidence of enhancement on MR images.     

Benign glial cysts of the pineal gland: unusual imaging characteristics with histologic correlation.

PURPOSETo describe the spectrum of MR and CT findings in clinically symptomatic pineal cysts and to determine whether there are certain diagnostic imaging features that allow one to distinguish a benign pineal cyst from other neoplasms of the pineal region.METHODSMR and CT scans of 19 patients with clinically symptomatic pineal cysts were retrospectively reviewed. Age range was 15 to 46 years with a mean age of 28 years. There were five male and 14 female patients.RESULTSPresenting features included headache (15 patients), diplopia (four), nausea and vomiting (four), papilledema (four), seizure (three), Parinaud syndrome (two), ataxia (one), and hemiparesis (one). All cysts were resected or biopsied to provide histopathologic confirmation of the diagnosis. Preoperative diagnoses included pineal neoplasm (14 of 19), pineal cyst (3 of 19), and dermoid cyst (2 of 19). The lesions ranged from 0.8 to 3.0 cm, with a mean diameter of 1.6 cm. Three cysts showed fluid/fluid levels consistent with hemorrhage. Slightly less than half (9 of 19) had evidence of hydrocephalus. The MR signal changes were variable but typically demonstrated low signal on T1-weighted images and high signal on T2-weighted images. More than half (7 of 12) demonstrated enhancement with gadolinium. Calcification of the cyst wall was observed in only four of nine patients who had CT studies but identified histologically in all cases.CONCLUSIONThe MR appearance of benign pineal cysts is variable, ranging from that of an uncomplicated cystic mass to a mass associated with hemorrhage, enhancement, or hydrocephalus. This variability may make them indistinguishable from other pineal-region tumors.     

MR and CT of masses of the anterosuperior third ventricle

Six patients with masses of the anterosuperior portion of the third ventricle were imaged with MR and CT. Four patients had proved colloid cysts, one patient had a proved astrocytoma, and one patient had a presumed colloid cyst. Multiplanar MR imaging provided accurate localization of the anterosuperior third-ventricle mass in all cases. The MR intensity characteristics of the colloid cysts varied and the astrocytoma could not be differentiated from the colloid cysts on MR. The astrocytoma contained a calcification that was clearly demonstrated on CT but was difficult to appreciate on MR. Neither MR nor CT was useful in predicting success of stereotactic aspiration of the colloid cysts in this small series, but the presence of thin, low-viscosity cyst contents could be suggested by both examinations.