MR appearance of Rathke's cleft cysts

Summary Two of three patients who proved to have symptomatic Rathke's cleft cysts presented with visual field deficit and all with diabetes insipidus. CT showed intra- and suprasellar cystic low density lesions with ring enhancement. MR showed intra-and suprasellar masses. On the T1-weighted images two of the three had hyperintense portions similar to fat and the other a hyperintense portion similar to white matter within the cysts. These portions were isointense to brain on the T2-weighted images in all cases. This characteristic intensity on MR images provides differentiation from cystic pituitary adenomas and cystic craniopharyngiomas, and leads to correct diagnosis of Rathke's cleft cyst.     

MR imaging of the ovaries: normal appearance and benign disease

MR imaging enables a physician to make an accurate diagnosis of various benign adnexal masses and helps to obviate unnecessary surgery.     

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.     

Human papillomavirus-associated plantar epidermoid cysts: MR and US imaging appearance

Epidermoid cysts are epithelial cysts that present as slow-growing intradermal or subcutaneous lesions. While recent epidemiological studies have isolated human papillomavirus (HPV) from plantar epidermoid cysts, imaging findings in HPV-associated epidermoid cysts have not been previously reported. We describe imaging findings in two patients with HPV-associated plantar epidermoid cysts. Magnetic resonance (MR) imaging and ultrasonography (US) showed linear arrangement of several adjacent globular cysts. This appearance is hypothesized to result from HPV-associated eccrine duct metaplasia leading to cyst formation and later traumatic rupture leading to formation of multiple adjacent cystic components. It may be useful to suggest assessing the presence of HPV antigen in plantar lesions having these imaging findings.     

MR appearance and cyst content of Rathke cleft cysts

The magnetic resonance signal intensity and cyst content were analyzed in 2 new and 17 previously reported cases of Rathke cleft cyst. Lesions displaying hypointensity on T1-weighted images (T1WI) and hyperintensity on T2-weighted images (T2WI) contained CSF-like fluid. Cases showing hyperintensity on T1WI and isointensity on T2WI frequently contained mucoid material. Hyperintensity on both T1WI and T2WI suggests the presence of blood. A small area of hypo- or isointensity indicates thickening of the cyst wall or collection of cellular debris.     

The MR appearance of cruciate ganglion cysts: a report of 16 cases

Intra-articular ganglion cysts arising from the cruciate ligaments are unusual lesions, there being only nine previously reported cases. We report 16 cases and describe their MR appearance. Nine ganglia originated from the posterior cruciate ligament, most often appearing as well-defined multilocular lesions. The seven ganglia arising from the anterior cruciate ligament most often appeared as fusiform cystic lesions extending along and interspersed within the fibers of the ligament. Although uncommon, intra-articular ganglion cysts arising from the knee appear to have a distinctive MR appearance which should allow their correct diagnosis.     

Variable MR findings in ovarian functional hemorrhagic cysts

PURPOSE: To describe the magnetic resonance (MR) findings in ovarian functional hemorrhagic cysts (FHC). MATERIALS AND METHODS: A total of 21 patients with 22 FHC, proven by follow-up ultrasound (US) in 11 women and surgery in 10 women, had US and MR examinations within 24 hours. The study was limited to cysts with obvious an echogenic pattern. All patients had T2-weighted fast spin echo (FSE), T1-weighted spin echo (SE), and T1-weighted SE fat-suppressed sequences. RESULTS: Four cysts (18%) were hypointense on T1-weighted-images without and with fat suppression, and hyperintense on T2-weighted-images. Five cysts (23%) were hypointense on T1-weighted images without and with fat suppression but heterogenous on T2-weighted images. Five cysts (23%) were hypointense on T1-weighted images but showed intermediate signal intensity on T1-weighted fat suppression images and heterogenous signal intensity on T2-weighted images. Two cysts (9%) were entirely intermediate on T1-weighted images. Five cysts (23%) displayed high signal intensity occupying less than 30% of the cystic content on T1-weighted images and one cyst (5%) displayed high signal intensity occupying more than 30% of the cystic content. CONCLUSION: Despite an obvious echogenic pattern on US, 64% of FHC were hypointense on T1-weighted images and 18% were also hyperintense on T2-weighted images. Only 36% demonstrated intermediate or high signal intensity on T1-weighted images.     

Polycystic ovaries: MR imaging

To determine the characteristic appearance of polycystic ovaries on magnetic resonance (MR) images, seven women with polycystic ovarian disease (PCOD) underwent MR examination of the pelvis. These MR images were compared with sonograms. Histologic material was available in two patients. Six of the seven women had characteristic, small peripheral cysts, best seen on T2-weighted MR images; these cysts were seen sonographically in only one case. The centers of nine of 14 ovaries were of low intensity with all MR pulse sequences; this low intensity corresponded with low echogenicity in six cases. Histologically, these areas correlated with hypertrophic cellular stroma. Coexisting central teratomas were seen in three ovaries. The ability of MR to display the findings of PCOD better than ultrasound and its ability to demonstrate coexisting pathologic conditions are valuable in imaging the female pelvis.     

Choledochal cysts: classification and cholangiographic appearance

A classification scheme for choledochal cysts is outlined and their appearance on cholangiograms is illustrated. Choledochal cysts are uncommon anomalies of the biliary system and are probably congenital in origin. They are manifested by cystic dilatation of the extra- or intrahepatic biliary tree or both. The classification system described here divides choledochal cysts into one of five main types. The most common, which is manifested by cystic or focal segmental dilatation of the common bile duct or fusiform choledochal dilatation, accounts for 80-90% of cases.     

Sciatic endometriosis: MR appearance

Endometriosis of the sciatic nerve is a rare but important cause of sciatica. Early on, the symptoms may be cyclic and be treated with local excision of the endometrioma from the sciatic nerve. If left untreated, it can result in marked cicatricial change of the sciatic nerve and require more radical surgical treatment. Due to the hemorrhagic nature of endometriomas and their characteristic location, the MR imaging findings can permit a specific diagnosis of sciatic endometriosis to be suggested. Therefore, MR imaging is recommended for evaluation of sciatica if the symptoms vary with the menstrual cycle or if there is a history of endometriosis. Early recognition of this disorder will facilitate appropriate treatment and minimize permanent damage to the sciatic nerve. The first surgically proven case of sciatic endometriosis with preoperative MR imaging is presented.     

Hemispherical spondylosclerosis: MR appearance

We present a case of hemispherical spondylosclerosis (HSS) in a middle-aged woman with low back pain. The plain radiographic findings, CT and MR appearance, and pathological examination are described, and the difficulties encountered in differentiating HSS from malignancy and infection are discussed.     

Pineal cysts: MR imaging

MR brain scans of 672 consecutive patients were examined prospectively to determine the incidence of high-signal pineal glands on T2-weighted images. The scans were obtained on either a 0.15-T or 0.5-T unit. This finding was present in 29 patients, none of whom had hydrocephalus or symptoms of a pineal mass. A CT scan was available in 17 of these cases and none of these demonstrated a solid pineal mass. Because of the frequency of this observation (4.3%) and the absence of associated findings, it was concluded that benign pineal cysts are the most likely explanation for this high signal. It is important for the radiologist to consider benign cysts in the differential diagnosis of a bright pineal gland on T2-weighted MR images.     

Primary thyroid lymphoma: MR appearance

Magnetic resonance imaging was evaluated in six patients with primary thyroid lymphoma. Five patients had a solitary localized tumor and one had multiple tumors. These masses showed homogeneous iso- or high intensity compared with the uninvolved thyroid tissue on T1-weighted images and homogeneous high intensity on T2-weighted images. Diffuse lobulated goiter with homogeneous intensity was seen in the sixth case, where the differentiation between lymphoma and Hashimoto thyroiditis was impossible. Extrathyroidal tumor extension occurred in two cases and cervical lymphadenopathy in one case. In five of six cases, identification and staging of primary thyroid lymphoma were possible with MR imaging. Magnetic resonance imaging was comparable to CT in the detection of tumors (five cases), extrathyroidal extension (two cases), and cervical lymphadenopathy (one case). In three cases, the pseudocapsule (a low-intensity band forming the border between tumor and thyroid tissue) was detected only by MR imaging. In one case, the discrimination between tumor and uninvolved thyroid gland was clearer on MR imaging than on CT.     

Phalangeal microgeodic syndrome: MR appearance

The authors describe the MR features of a case of microgeodic phalangeal syndrome in a 9-year-old boy. Roentgenograms showed multiple small areas of osteolysis in the middle phalanx of the right index finger. T1-weighted MR images showed lesions with diffuse low signal intensity not only in this phalanx but also in other phalanges. These lesions exhibited high signal intensity on T2-weighted images. Contrast- enhanced T1-weighted images showed a wide non-enhancing area in the middle phalanx of the index finger. Received: 26 September 2000 Revision requested: 2 November 2000 Revision received: 25 November 2000 Accepted: 27 November 2000     

Raeder syndrome: MR appearance.

A 40-year-old woman presented with symptoms compatible with Raeder syndrome. MR demonstrated narrowing of the left cavernous carotid artery. The high cervical portion of the left internal carotid artery was not identified. Angiography confirmed the narrowing of the cavernous carotid artery and showed marked and irregular stenosis of the distal cervical internal carotid artery. Involvement of the left sympathetic plexus and of ipsilateral cavernous sinus arteries is believed to have been the cause of the Raeder syndrome in this patient.