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.     

CT myelography in spinal cysticercosis

Four cases of spinal cysticercosis were found in a series of 356 cases of CNS cysticercosis studied neuroradiologically. Cysticercal cysts were seen to migrate within the spinal subarachnoid space on myelographic studies. All four patients presented initially with hydrocephalus, which supports the notion that spinal leptomeningeal cysts have migrated from an intracranial site of origin. Computed tomographic myelography (metrizamide) allowed better localization and definition of the spinal cysticercal lesions.     

Intracranial cysts.

While CT scanning is useful for diagnosis of hydrocephalus and fluid-containing intracranial cysts, air studies are often necessary to determine whether the cysts communicate with the ventricular or subarachnoid space. When obstructive hydrocephalus results, decompression of the cyst is normally adequate. Hydrocephalus not caused by a cyst still requires decompression, but in addition the cyst has to be treated. Until the exact pathways of absorption of water-soluble contrast media such as metrizamide are fully understood, it may be advisable not to administer them into the ventricles in patients with obstructive hydrocephalus. A combination of CT and air studies may offer information not obtainable with either modality alone.     

MRI and in vivo proton MR spectroscopy in a racemose cysticercal cyst of the brain

Racemose cysticercal cyst is the subarachnoid manifestation of the larvae of Taenia solium. On MRI the cysts may resemble other cystic masses. We report the magnetic resonance spectroscopy (MRS) features of a case on in vivo proton spectroscopy and discuss its role in the diagnosis of intracranial cysts of parasitic aetiology.     

Intraosseous leptomeningeal cysts of the posterior cranial fossa.

Post-traumatic leptomeningeal cysts involving the occipital bone are intraosseous lesions which do not erode through the outer table, in contradistinction to leptomeningeal cysts elsewhere in the calvaria. In two of four reported cases, communicating hydrocephalus was associated with the intraosseous cyst. The clinical and radiological findings suggest that intraosseous leptomeningeal cyst of the posterior fossa represents a distinct entity. Resection of the cyst and closure of the dural defect may be less important than treatment of the communicating hydrocephalus.     

T2 relaxometry of ring lesions of the brain

AIM: To differentiate two common aetiologies of "ring lesions," tuberculomas and cysticercal cysts, using T2 relaxometry. MATERIALS AND METHODS: Fifty-five ring-enhancing lesions of the brain (32 cysticercal cysts; 23 tuberculomas) in 27 patients with focal seizures were studied for T2 relaxation times. RESULTS: The mean T2 relaxation times of cysticercal cysts was 617 ms (range 305-1365 ms; SD 272.2) and that of tuberculomas 161 ms (range 83-290 ms; SD 60.3; 95% confidence). CONCLUSION: T2 relaxometry is a simple, reliable and valuable non-invasive magnetic resonance imaging (MRI) technique to differentiate between intracranial cysticercal cysts and tuberculomas, and may be incorporated in routine diagnostic protocols.     

Improved detection of intraventricular cysticercal cysts with the use of three-dimensional constructive interference in steady state MR sequences

BACKGROUND AND PURPOSE: Before the advent of MR imaging, intraventricular cysts were difficult to diagnose noninvasively. Among the invasive procedures used were contrast ventriculography and CT ventriculography. MR imaging, with its multiplanar imaging capabilities, excellent depiction of tissue contrast, and versatile parameters, is an important tool in the assessment of intraventricular cystic lesions. We investigated the role of three-dimensional constructive interference in steady state (3D-CISS) MR sequences in the evaluation of intraventricular cysticercal cysts. METHODS: The study group comprised 11 patients with intraventricular cysticercal cysts. MR studies included spin-echo (SE) T1-weighted, turbo-SE T2-weighted, and 3D-CISS sequences. All images were obtained on a superconducting 1.5-T MR unit. The routine and 3D-CISS sequences were reviewed and interpreted separately by two neuroradiologists. RESULTS: All patients underwent surgery for excision of intraventricular cysticercal cysts. Eight patients had cysts in the fourth ventricle, two in the lateral ventricle, and one in the third ventricle. SE T1-weighted images showed the cystic wall in nine cases, the scolex in four, and the cystic fluid in two. Turbo-SE T2-weighted images showed the cystic wall and scolex in three and four cases, respectively. The routine sequences did not show the scolex, cystic wall, or cystic fluid together in any of the 11 patients. 3D-CISS images showed the scolex in all 11 patients and the cystic wall and cystic fluid in eight patients each. In seven of the 11 patients, 3D-CISS images showed the scolex, cystic wall, and fluid together. CONCLUSION: The 3D-CISS sequence is more sensitive and specific than routine SE sequences in the diagnosis of intraventricular cysticercal cysts.     

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.     

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.     

Tetraventricular hydrocephalus due to ruptured intracranial dermoid cyst

We present the MR imaging findings in a patient who developed tetraventricular hydrocephalus after massive rupture of dermoid cysts with generalized subarachnoid and ventricular spread of cyst contents. The development of tetraventricular hydrocephalus due to ruptured dermoid is a very unusual complication, and was attributed to cyst contents interfering with passage of cerebrospinal fluid through the arachnoid granulations and fourth ventricular outlet foramina. Received: 31 January 2000; Revised: 3 March 2000; Accepted: 16 March 2000     

Colloid cyst of the third ventricle: imaging-pathologic correlation

Colloid cysts are relatively rare intracranial lesions located in the rostral aspect of the third ventricle. They may produce acute hydrocephalus, brain herniation, and lead to death. Although the clinical and imaging features of colloid cysts are well known, their etiology and the factors responsible for their imaging features continue to be a subject of debate. We present the imaging-pathologic correlation of a patient with a colloid cyst as well as data supporting the fact that the presence of cholesterol is probably responsible for the MR imaging features exhibited by some colloid cysts.     

Suprasellar arachnoid cysts: 2. Evaluation of CSF dynamics

Suprasellar arachnoid cysts are an infrequent but surgically remediable cause of hydrocephalus and neurologic deficits. The optimal method of treatment varies according to whether the cyst communicates with the subarachnoid space; the presence or absence of associated hydrocephalus; and the exact site(s) and severity of intraventricular and extraventricular cerebrospinal fluid (CSF) obstruction. Eight patients with suprasellar arachnoid cysts are described to emphasize the importance of pretherapeutic investigation of CSF dynamics. The variability of the ventriculocisternal-cyst CSF dynamics and the value of metrizamide computed tomographic cisternography and ventriculography in investigation of the CSF pathways are stressed. A diagnostic approach to the evaluation of the CSF dynamics is outlined, based on whether hydrocephalic or compressive symptoms predominate.     

Unusual small choroid plexus cyst obstructing the foramen of monroe: case report

This is a case report of unusual case of choroid plexus cyst at the right foramen of Monro in the anterior third ventricle that caused unilateral obstructive hydrocephalus. The value of small-FOV thin-section MR imaging in the diagnosis of small lesions of the foramen of Monroe is demonstrated. The immunohistochemical findings in choroid epithelial cysts in comparison with those of other types of cysts at this location are discussed.     

MR ventriculography for the study of CSF flow

BACKGROUND AND PURPOSE: Various MR techniques have been used to assess CSF flow and to image the subarachnoid spaces and ventricles. Anecdotal reports describe the use of intrathecal and intraventricular gadolinium-based contrast agents in humans and animals. We sought to determine the clinical usefulness of gadolinium-enhanced MR ventriculography for assessing CSF flow in patients with various neurologic conditions. METHODS: Five patients (three female and two male patients aged 6 months to 65 years) were included in the study. After performing sagittal, coronal, and axial T1-weighted MR imaging of the brain, 0.02-0.04 mmol of gadodiamide was injected into the lateral ventricle. Sagittal, coronal, and axial T1-weighted imaging was repeated soon after the injection. We were specifically looking for the site of obstruction to CSF flow in those patients with hydrocephalus, communication between cysts and ventricles, elucidation of suspicious intraventricular lesions, and patency of third ventriculostomies. RESULTS: MR ventriculography showed good delineation of the ventricular system in all patients. In one patient with carcinomatosis and hydrocephalus, a block to contrast material flow was detected at the right foramen of Luschka. In another patient with hydrocephalus, partial block to the flow of contrast material was demonstrated at the right foramen of Monro. In a patient with hydrocephalus and a posterior fossa cyst, flow of contrast material was blocked between the third ventricle and the cyst, with a thin streak of contrast material in the aqueduct. As an assessment of the patency of a third ventriculostomy, MR ventriculography showed flow of contrast material into the suprasellar cisterns from the third ventricle in one patient and absence of flow in another. CONCLUSION: MR ventriculography is a safe technique for assessing CSF flow, with application in determining the site of obstruction in hydrocephalus, in assessing communication between cysts and the ventricle, and in determining the functioning status of endoscopic third ventriculostomies.     

Midline cystic malformations of the brain: imaging diagnosis and classification based on embryologic analysis

This article describes a classification and imaging diagnosis of intracranial midline cystic malformations based on neuroembryologic analysis. Midline cystic malformations are classified into two categories from an embryologic point of view. In one category, the cyst represents expansion of the roof plate of the brain vesicle, and in the other the cyst consists of extraaxial structures such as an arachnoid membrane or migrating ependymal cells. Infratentorial cysts, such as the Dandy-Walker cyst or Blake's pouch cyst, and supratentorial cysts, such as a communicating interhemispheric cyst with callosal agenesis or a dorsal cyst with holoprosencephaly, are included in the first category. Infratentorial arachnoid cavities, such as the arachnoid cyst, arachnoid pouch, and mega cisterna magna, are in the second category. Noncommunicating interhemispheric cysts, such as interhemispheric arachnoid cyst or ependymal cyst, with callosal agenesis are also in the second category. A careful review of embryologic development is essential for understanding these midline cysts and for making a more accurate radiologic diagnosis. This work was presented as an educational lecture at the 64^th Japan Radiological Society meeting (April 2005) in Yokohama.     

Popliteal cysts: sonography evaluation after arthroscopic treatment

PURPOSE: To identify a set of sonomorphological parameters to evaluate the outcome of arthroscopic surgery for popliteal cysts by sonography. MATERIAL AND METHODS: We examined 30 patients (18 males, 12 females) before treatment and 3/6 months after arthroscopy. Patients were classified by clinical (4 groups) and sonographic criteria. The sonographic criteria were the morphological classification of the cysts (beak-shaped, X-shaped, grape-like, slit-shaped) and the volume measurement. RESULTS: Sonography identified beak-shaped popliteal cysts (the most frequent Baker cyst shape), 5 grape-like (the usual shape of complicated Baker cysts) and 1 X-shaped . The volume of cysts before treatment ranged from 5 to 38 cl. Most cysts were clinically rated as grade 2 (symptomatic and evident at physical examination, with a reduction of range of motion up to 20 degrees of flexion). No patient was rated as grade 0 (normal). After surgery the cyst was still evident at sonography. After 3 months we recorred a cyst volume decrease in all cases. Six months after surgery 29/30 cysts had a volume <5 cl with an almost virtual cavity that changed their appearance in to slit-shaped . In one case cyst volume increased. The clinical classification showed an increase of the grade 0 group unsymptomatic cysts (not detectable at physical examination). DISCUSSION AND CONCLUSIONS: Sonographic evaluation of popliteal cysts after arthroscopic surgical treatment allowed to recognize the cysts, which are not removed by this approach. The follow-up at 3 months showed a reduction in cyst volume. After six months, in the cases with a good surgical response, the cysts reached a volume <5 cl regardless of their original volume. The morphology of the cysts with a good surgical result, is slit-shaped with virtual cavity regardless of their original appearance. There is a high correlation between sonographic and clinical data. We believe that the volume reduction of the cyst three months after surgery is a good predictive element. After six months the preesence of a cyst with a volume <5 cl and a slit-shape with virtual cavity is a sign of good surgical result.     

"Daughter cyst" sign: a sonographic finding of ovarian cyst in neonates, infants, and young children

OBJECTIVE: The purpose of this study was to assess the value of the "daughter cyst" sign, a sonographic finding of neonatal ovarian cysts, in differentiating ovarian cysts from other cystic masses in neonates, infants, and young children. SUBJECTS AND METHODS: In a prospective study, 23 neonates, infants, and young children (age range, 1 day to 36 months) with a lower abdominal cystic mass underwent sonography. We defined the daughter cyst sign as the presence of a small cyst along the wall of a cystic mass. The diagnosis of ovarian cyst was made when this sign was present. Detailed pathologic correlation was available in four ovarian cysts. The size, wall thickness, and contents of the cysts were also evaluated. RESULTS: The 23 cystic lesions included ovarian cyst (n = 11), lymphangioma (n = 3), enteric duplication cyst (n = 3), enteric cyst (n = 1), meconium pseudocyst (n = 2), hydrometrocolpos (n = 2), and urachal cyst (n = 1). The daughter cyst sign was seen in nine (82%) of 11 ovarian cysts but in none of the other cystic lesions. Sensitivity, specificity, and positive predictive value of the daughter cyst sign for differentiating ovarian cysts from other cystic lesions were 82%, 100%, and 100%, respectively. The daughter cyst corresponded to an ovarian follicle on pathologic examination. CONCLUSION: The daughter cyst sign is a specific sonographic finding for an ovarian cyst and may be useful in differentiating uncomplicated ovarian cysts from other cystic masses in neonates, infants, and young children.     

Case report: Squamous carcinoma in an oesophageal foregut cyst

Cysts within the oesophageal wall may represent inclusion cysts, retention cysts or developmental cysts. Foregut duplications are developmental anomalies, which occur as a result of abnormal canalization of the foregut during intrauterine life. Malignant transformation is an extremely rare event occurring within oesophageal cysts, adenocarcinoma being the most common histology. We report a case of squamous cell carcinoma arising within an oesophageal cyst affecting the upper third of the oesophagus. The malignant cyst was not amenable to primary surgical resection and hence was treated using chemo-radiotherapy. The treatment gave good disease control, at the expense of a high oesophageal stricture. Chemo-radiotherapy is an alternative treatment modality to achieve long-term disease control in squamous cell carcinoma complicating oesophageal foregut cyst when primary surgical resection is not possible.     

Coexisting secondary intraneural and vascular adventitial ganglion cysts of joint origin: a causal rather than a coincidental relationship supporting an articular theory

Objective To introduce the clinical entity of an intraneural ganglion cyst coexisting with a vascular adventitial cyst arising from the same joint.Design Retrospective review.Patients Two patients presented with predominantly deep peroneal neuropathy due to complex superior tibiofibular joint-related cysts. In addition to having peroneal intraneural ganglion cysts, these patients had vascular adventitial cysts: one involving a capsular arterial branch, the other a capsular vein [as well as a large, recurrent, intramuscular (extraneural) ganglion]. We then reviewed MRIs of 12 other consecutive cases of intraneural ganglia (10 peroneal and 2 tibial) arising from the superior tibiofibular joint that we treated, as well as other reported cases in the literature to determine if there were other (unrecognized) examples supporting the combination of clinical findings and radiographic patterns.Results Retrospective analysis of MRIs in the two surgically proven cases of peroneal intraneural ganglia with vascular adventitial cyst extension showed a common imaging pattern that we have termed “the wishbone sign,” consisting of the connection of the ascending limb of the peroneal intraneural ganglion and the longitudinal limb of the vascular adventitial cyst in the axial plane. Our review suggests that vascular adventitial cyst extension occurs in a large proportion of cases of peroneal intraneural ganglia. A similar growth pattern was noted in a case of a tibial intraneural ganglion.Conclusions The combination of intraneural and vascular adventitial cysts is understandable given our knowledge of normal and pathologic anatomy of para-articular cysts. The combination of intraneural ganglia and vascular adventitial cysts broadens the spectrum of clinical presentations of these cysts and suggests that cysts and their content can dissect from a joint along neurovascular bundles. These cases provide important evidence to support the articular theory for the pathogenesis of not only neural but vascular adventitial cysts as well.     

Serial MR imaging of pineal cysts: implications for natural history and follow-up

OBJECTIVE: The purpose of this study was to examine the frequency of change in size of pineal cysts on serial MR studies. MATERIALS AND METHODS: Thirty-two patients (19 females, 13 males) with a diagnosis of pineal cyst at any time who underwent brain MR imaging more than once in a period of at least 6 months were identified by computerized search of radiology reports. Four patients underwent MR imaging to follow up pineal cysts, whereas the remaining patients were imaged for a variety of indications, including intracerebral neoplasms. Measurements of maximal cyst dimension on both initial and latest follow-up studies were obtained in all patients, and cyst volumes were calculated in 23 patients. RESULTS: Length of follow-up ranged from 6 months to 9 years. All cysts were considered incidental and none were treated. Maximal cyst dimensions ranged from 0.5 to 2.2 cm. On average, there was no significant change in cyst volume. The maximal dimension of the cyst did not change in 24 (75%) of 32 patients. Two cysts resolved completely on follow-up, three cysts decreased by 2-4 mm, two cysts enlarged by 2-3 mm, and one cyst formed and grew to 1.2 cm. CONCLUSION: Whereas the size of pineal cysts as a whole remained unchanged on serial MR studies, cysts may either form or involute in individual patients. Small increases in cyst size did occur but were not associated with specific clinical findings. These findings suggest that typical pineal cysts may be followed up on a clinical basis alone rather than on imaging.