MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules

BACKGROUND AND PURPOSE: Rathke's cleft cysts often may be difficult to differentiate from other intrasellar or suprasellar masses on radiologic studies. The purpose of this study was to describe the significance of intracystic nodules, a diagnostic characteristic found in Rathke's cleft cysts, on MR images. METHODS: A retrospective review of MR studies was conducted for 13 patients who, after pathologic analysis, were diagnosed as having Rathke's cleft cyst. These patients underwent unenhanced and contrast-enhanced T1- and T2-weighted axial and coronal spin-echo sequential imaging. The signal intensity and incidence of the intracystic nodules on T1- and T2-weighted images were analyzed. The signal intensity of the nodule was compared with that of white matter and surrounding cyst fluid. The signal intensity of cyst fluid was compared with the intraoperative appearance of the cyst fluid. Biochemical and pathologic analyses of the intracystic nodules were conducted in two cases. RESULTS: An intracystic nodule having high signal intensity on T1-weighted images and low signal intensity on T2-weighted images was observed in 10 (77%) of the cases. At surgery, intracystic nodules were yellow, waxy, solid masses. Pathologic analysis showed this nodule to be a mucin clump. Biochemical analysis of the intracystic nodules showed cholesterol and proteins as the main constituents. In the Rathke's cleft cyst with intracystic nodules, cyst fluid revealed low signal intensity to isointensity relative to the intensity of the nodules on T1-weighted images, and isointensity to high signal intensity on T2-weighted images. Intracystic nodules were clearly visible on T2-weighted images. CONCLUSION: Because cyst fluid of Rathke's cleft cysts shows variable intensities on MR images, the specific diagnosis is often difficult when based on MR signal intensity values alone. The presence of an intracystic nodule with characteristic signal intensities on MR images may be indicative of the diagnosis of Rathke's cleft cyst.     

Rathke cleft cyst: MR and biomedical analysis of cyst content

PURPOSE: At least one type of Rathke cleft cyst has unique MR findings, specifically, high intensity on T1-weighted images and iso- to low intensity on T2-weighted images relative to white matter. To clarify the influence of cyst content on MR images, we analyzed the cyst content by biomedical methods after surgical removal. METHOD: We studied five patients diagnosed with Rathke cleft cyst, whose MR images showed high intensity on T1-weighted images and iso- to low intensity on T2-weighted images. After surgery, total protein and cholesterol levels were quantified, and correlations of protein and cholesterol content with T1 and T2 signal intensities were performed in vitro. RESULTS: All five cysts had very high concentrations of protein (11,700-26,600 mg/dl, mean 17,940 mg/dl) with nearly no cholesterol (at most 2.0 mg/dl). Along with increases in protein concentration in vitro, the signal intensity of T1-weighted images increased, while that of T2-weighted images decreased. In contrast, the cholesterol concentration sequence influenced the signal intensity of neither T1- nor T2-weighted images. CONCLUSION: The unique MR finding of Rathke cleft cysts--high signal intensity on T1-weighted images and low signal intensity on T2-weighted images--might depend mainly on protein concentration, not on cholesterol.     

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.     

MR imaging of nasopalatine duct cysts

We describe the magnetic resonance (MR) features of two cases of nasopalatine duct cyst (NPDC), including the first presentation of T1-weighted images (WI). The signal intensity of the cases of NPDC showed homogeneous high signal intensity on both on T1 and T2WI, although most cysts of maxillofacial regions demonstrate low to intermediate signal intensity on T1WI. NPDC may commonly be of high signal intensity on T1WI, which is consistent with keratin and viscous fluids.     

Rathke cleft cysts: correlation of enhanced MR and surgical findings.

PURPOSETo describe the gadolinium-enhanced MR findings of Rathke cleft cyst correlate them with the surgical findings, and define those preoperative findings that differentiate this lesion from other sellar and juxtasellar tumors.METHODSWe studied 18 patients who were diagnosed as having Rathke cleft cyst pathologically. These patients were imaged with T1- and T2-weighted coronal and sagittal spin-echo sequences. Fifteen of these patients received gadopentetate dimeglumine.RESULTSIn eight patients, the cyst showed low intensity on T1-weighted images and high intensity on T2-weighted images. At surgery, the cyst fluid was cerebrospinal fluid-like or light brown in five patients, motor oil-like in one patient, and milky in two patients. In 10 patients, cysts showed isointensity to high intensity on T1-weighted images and had various intensity on T2-weighted images. All 10 contained milky fluid. In three patients the intensity of fluid was heterogeneous. A waxy nodule was found in two patients. The position of the normal pituitary gland confirmed by surgery in all cases coincided with enhancement on MR imaging. The variable position of the normal pituitary gland was clearly identified in the sagittal images. The cyst walls showed no enhancement by gadopentetate dimeglumine.CONCLUSIONSBecause Rathke cleft cysts show variable intensities on MR, the diagnosis is often difficult when based on MR signal intensity values alone. MR imaging with gadopentetate dimeglumine does assist in the diagnosis of Rathke cleft cysts. Diagnostic clues include the lack of cyst wall enhancement and displacement of the normal pituitary gland.     

Neurenteric cyst with alteration of signal intensity on follow-up MR images

SUMMARY: Intracranial neurenteric cysts are uncommon and usually have low intensity on T1-weighted MR images and high intensity on T2-weighted MR images. We report a case of a neurenteric cyst that was situated in front of the medulla oblongata and the size of which increased with alteration of MR signal from high to isointense compared with that of brain on T1-weighted images obtained 33 months after the initial MR images. We think that the signal change of the cyst was probably caused by a change of protein concentration.     

MR imaging of epithelial cysts of the oral and maxillofacial region

The aim of the present study was to review the magnetic resonance (MR) appearance of primary epithelial cysts in order to distinguish the cysts from other possible lesions. MR images were obtained in 27 cases of epithelial cysts, including 7 odontogenic keratocysts, 3 dentigerous cysts, 1 glandular odontogenic cyst, 10 radicular cysts, 4 nasopalatine duct cysts, and 2 nasolabial cysts. In addition, contrast enhanced MR imagings were performed in 12 cases, including 3 odontogenic keratocysts, 1 dentigerous cyst, 1 glandular odontogenic cyst, and 7 radicular cysts. We obtained the following results on the basis of the above MR and contrast enhanced MR findings. (a) Odontogenic keratocysts had a predilection for intermediate-high signal intensity (SI) on T1-weighted images (WI) and heterogeneous low-high SI on T2WI. (b) Dentigerous cysts, glandular odontogenic cyst, radicular cysts and nasolabial cysts showed the same predilection with the SI, which were homogeneous intermediate SI on T1WI and homogeneous high SI on T2WI. (c) The MR images of the nasopalatine duct cysts, which showed homogeneous high SI on T1WI, were specific. (d) The Gd-T1WI would be useful in decisively differentiating odontogenic cysts, which showed rim-enhancement, from tumors consisting of solid components. In conclusion, we were able to obtain more information from the MR and contrast enhanced MR images than from conventional radiograph findings.     

卵巢内膜异位性囊肿的MRI诊断

目的：评价MRI诊断卵巢内膜异位性囊肿的价值。材料和方法：记录14例患者的25个痛灶MRI形态及信号变化特点，并与手术病理结果相对照．结果：发现当囊肿在T1WI上呈均匀高信号，T2 WI上部分区域出现中等至低信号暗影，或T1 WI病灶由多个全为高信号的囊腔组成时，不管其T2 WI上的信号强度如何．基本可确诊为卵巢内膜异位性囊肿．当囊肿在T1WI和T2WI上呈高信号．或囊肿与邻近器官有粘连，囊腔周围有纤维被膜包绕，在T1WL及T2WI上形成-低信号带影时．应高度怀疑之。结论：MRI对内膜异位性囊肿诊断的敏感性及准确性分别可选96%和93%．     

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.     

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 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.     

MR findings of a giant Bartholin's duct cyst

We describe the case of a 63-year-old woman with a large Bartholin's duct cyst that showed high signal intensity on T1- and T2-weighted magnetic resonance (MR) images. Although Bartholin's duct cyst is the most frequent cystic lesion of the vulva, such a giant cyst is rare.     

MRI and ultrasound in solitary muscular and soft tissue cysticercosis

Solitary cysticercosis of muscles and soft tissue is a rare disease and can cause a diagnostic dilemma clinically. We present the MRI and ultrasound findings in six patients with solitary muscular and soft tissue cysticercosis. Five of them had clear cysts that displayed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Four of these cysts had scolices within them. One patient had an ill-defined hyperintense lesion on T2-weighted images without any clear cyst. Ultrasound performed in all patients showed similar findings, with the scolices being more clearly appreciated. MRI and ultrasound are useful in the diagnosis of solitary muscular and soft tissue cysticercosis and they reliably establish the diagnosis when a clear cyst with scolex is seen.     

Seminal vesicle cyst associated with ipsilateral renal agenesis and papillary carcinoma of the bladder

We report a case of seminal vesicle cyst associated with ipsilateral renal agenesis in a 37-year-old patient with papillary carcinoma of the bladder. Ultrasonography showed absence of the right kidney, a bladder tumour and a round retrovesical hypoechogenic mass with posterior acoustic enhancement. It showed low attenuation on CT, low signal intensity on T1-weighted MR images and high signal intensity on T2-weighted MR images. Intravenous urography (IVU) and cystoscopy were also performed. After surgery, it proved to be a seminal vesicle cyst. The embryology, imaging characteristics and differential diagnosis of seminal vesicle cysts are discussed. Associated findings are also described.     

Markedly high signal intensity lesions in the uterine cervix on T2-weighted imaging: differentiation between mucin-producing carcinomas and nabothian cysts.

PURPOSE: Both mucin-producing carcinomas and nabothian cysts in the cervix show very high signal intensity on T2-weighted images (WI). The purpose of this study was to evaluate the potential of MR imaging in differentiating mucin-producing carcinomas from nabothian cysts. MATERIALS AND METHODS: Forty-six patients who underwent hysterectomy and had very high signal intensity lesions in the uterine cervix on T2-WI were included in this study. The pathological diagnoses were mucin-producing carcinoma in 13 patients, non-mucin-producing carcinoma accompanied with nabothian cyst in four patients, and nabothian cyst in 29 patients. T1-WI, T2-WI, and Gd-T1-WI were obtained in all patients. Malignancies were diagnosed on Gd-T1-WI as follows: (1) an enhanced lesion, (2) an irregular margin, (3) iso-intensity on T1-WI. In contrast, high signal intensity on T1-WI was considered benign. RESULTS: Thirteen of 17 malignant lesions and three of 29 benign lesions were enhanced. Irregular margins were observed in 12 of 17 malignant lesions and four of 29 benign lesions. Nineteen benign lesions and seven malignant lesions demonstrated high signal intensity on supplemental T1-WI. Combining the lesion criteria of enhancement, irregular lesion margin, and iso-intensity on T1-WI, the overall accuracy, sensitivity, and specificity rates of diagnosing malignancy were 89%, 88%, and 90%, respectively (p < 0.01). CONCLUSION: MR imaging accurately differentiated mucin-producing carcinomas from nabothian cysts that showed high signal intensity on T2-WI in the cervical stroma. For diagnosing mucin-producing carcinomas and nabothian cysts when signal intensity was remarkably high on T2-WI, Gd-T1-WI findings provided key information for differentiation, and T1-WI was useful for improving specificity.     

MR imaging of Tornwaldt's cysts.

OBJECTIVE: The purpose of this study was to assess the characteristics of Tornwaldt's cysts as revealed by routine MR studies. MATERIALS AND METHODS: We retrospectively reviewed MR images of the brain in 1208 consecutive subjects who ranged in age from 3 weeks to 93 years (mean, 57.1 years). The signal intensity, shape, and size of Tornwaldt's cysts were assessed. Patients with Tornwaldt's cysts were then questioned about the presence of persistent nasal discharge, occipital headaches, and halitosis and an unpleasant taste in the mouth and about a history of adenoidectomy. RESULTS: Tornwaldt's cysts were found in 23 patients (1.9%) who ranged in age from 39 to 78 years (mean, 57.3 years). Of the 23 Tornwaldt's cysts, all were isointense to CSF on T2-weighted images and hyperintense to gray matter on the fluid-attenuated inversion-recovery images. The cysts showed high signal intensity compared with muscle on T1-weighted images. Nineteen cysts were round and four were oval. The mean size of the lesions was 6.0 mm in the major axis and 5.5 mm in the minor axis. Two patients with Tornwaldt's cysts had persistent nasal discharge and occipital headaches, and another patient had occipital headaches alone. None of the patients had undergone an adenoidectomy. CONCLUSION: Lesions consistent with Tornwaldt's cysts were found in 1.9% of the routine MR studies of the brain. The cysts had high signal intensity on T1-weighted, T2-weighted, and fluid-attenuated inversion-recovery images.     

Cysts of the prostate and seminal vesicles: MR imaging findings in 11 cases

Cysts of the prostate and seminal vesicles are confusing abnormalities because they are uncommon and their origin is uncertain. Several approaches to diagnosis have been used, most recently CT and transrectal sonography. In this study, we investigated the value of MR imaging in the diagnosis of six cases of prostatic cyst and five cases of cysts of the seminal vesicles. All patients were symptomatic. T1- and T2-weighted spin-echo images were obtained in all cases; pathologic confirmation was available in four patients. MR images were analyzed prospectively without knowledge of clinical data or the results of other imaging procedures. In all cases, low- and high-signal masses were observed on T1- and T2-weighted images, respectively. The cysts were unilocular with a sharply defined margin, ranging from 0.5 to 3.0 cm in diameter. The thin wall was of low signal intensity on T2-weighted images. Our experience suggests that MR imaging is useful in demonstrating the liquid content of prostatic and seminal-vesicle cysts and in establishing their size and location.     

Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts.

OBJECTIVE: The purpose of this study is to describe MR imaging features of an unusual type of meniscal cyst arising from tears of the posterior horn of the medial meniscus in 10 patients. MATERIALS AND METHODS: Retrospective review of MR examinations of the knee was performed of 10 patients (nine men, one woman; mean age, 39 years) in whom evidence of a meniscal tear and a cyst-like structure around the posterior cruciate ligament (PCL) was seen. RESULTS: An oval mass with low signal intensity on T1-weighted MR images and increased signal intensity on T2-weighted MR images posterior to the PCL, simulating a PCL ganglion cyst, was seen in all 10 patients. A tear of the posterior horn of the medial meniscus was also seen in all patients. The sites of communication between the cyst and meniscal tear were observed in sagittal MR images in eight patients. Septation within the cyst and associated joint effusion were seen in eight and four patients, respectively. Arthroscopy in eight patients and transmeniscal needle drainage in the other two patients confirmed both the meniscal tear and the pericruciate meniscal cyst. CONCLUSION: Pericruciate meniscal cysts cause fluid collections posterior to the PCL, simulating a PCL ganglion cyst. Careful analysis of the posterior horn of the medial meniscus should be performed when a cyst-like structure is seen adjacent to the PCL.     

Accuracy of abnormal paraspinal muscle findings on contrast-enhanced MR images as indirect signs of unilateral cervical root-avulsion injury

PURPOSE: To evaluate the accuracy of abnormal magnetic resonance (MR) findings in the paraspinal muscles as indirect signs of nerve-root avulsion injury. MATERIALS AND METHODS: Forty-three consecutive patients suspected of having unilateral root-avulsion injury underwent MR imaging and were evaluated. Paraspinal muscles were evaluated for abnormal signal intensity on T1- and T2-weighted images, abnormal enhancement on images obtained after contrast material enhancement, and muscle volume loss. MR images were interpreted independently by two observers for interobserver variability. MR findings were compared with findings of root continuity, determined with a combination of surgery and clinical evaluation. Sensitivities, specificities, and kappa values of the findings were calculated. RESULTS: Sensitivities of MR findings in the paraspinal muscles indicating root-avulsion injury were 88% (36 of 41 patients) for abnormal enhancement, 83% (34 of 41 patients) for high signal intensity on T2-weighted images, 37% (15 of 41 patients) for high signal intensity on T1-weighted images, and 71% (29 of 41 patients) for muscle volume loss. Specificities for all findings were 100% (two of two patients). Of the paraspinal muscles, findings in the multifidus muscle were the most accurate and provided the highest interobserver agreement (kappa = 0.81). CONCLUSION: Contrast material-enhanced abnormal MR findings in the paraspinal muscles are accurate in indicating root-avulsion injuries, and abnormal enhancement in the multifidus muscle is the most accurate among paraspinal muscle findings.     

Colloid Cysts of the Third Ventricle: Are MR Imaging Patterns Predictive of Difficulty with Percutaneous Treatment?

BACKGROUND AND PURPOSE: Colloid cysts of the third ventricle are rare benign brain tumors. The purpose of this study was to correlate their patterns on MR images with the probability of success of percutaneous treatment. METHODS: Nineteen patients underwent endoscopic treatment for colloid cysts of the third ventricle. The cases were divided into two groups based on difficulty of the aspiration procedure. We reviewed CT scans and MR images and divided cysts into groups based on their signal intensity on the MR images and their density on CT scans. Intensity and density were correlated with difficulty of aspiration during the endoscopic procedure. RESULTS: The aspiration procedure was difficult in 63% of the cases. Eighty-nine percent of hyperdense cysts on unenhanced axial CT scans were categorized as difficult, and 75% of hypodense cysts were categorized as easy. On T2-weighted MR sequences, 100% of low-signal cyst contents were difficult and nearly 63% of high-signal lesions were easy. There was a significant correlation between the T2-weighted sequences and the CT scans regarding the difficulty of the aspiration procedure. CONCLUSION: T2-weighted MR sequences are useful for predicting difficulty of aspiration during stereotactic or endoscopic procedures. A T2-weighted low-signal cyst is correlated with high-viscosity intracystic contents.