Evaluation of complicated renal cyst: a comparison of CT and MR imaging]

We report 12 cases of renal cystic lesions that could not be diagnosed preoperatively. Sonography, computed tomography (CT), magnetic resonance (MR) imaging, and angiography were performed in all cases. Angiography was not helpful in evaluating cystic lesions, because all cystic lesions were hypovascular or avascular within the cystic mass. CT was useful in depicting the fine structural abnormalities, and especially bolus-contrast CT study was useful in the differentiation of cystic renal cell carcinoma from simple renal cyst. However, there were 5 false positive cases. MR imaging is superior to CT in distinguishing a hemorrhagic cyst or multiloculated cystic mass. In conclusion, CT is currently the primary imaging modality for evaluating complicated renal cysts, and surgical exploration is warranted for the undiagnosed cystic lesion by CT. However, MR imaging also has an important role in detecting the benign complicated cyst. Therefore if complicated cyst is thought to be benign by MR imaging, parenchyma-sparing surgery should be considered preoperatively.     

Skull base amyloidoma. Case report.

A mass lesion of amyloid involving the central nervous system is a rare finding. A 64-year-old woman presented with a large amyloidoma at the skull base causing neural tissue compression. The only accompanying disease was an asymptomatic renal cyst. The mass had caused destruction of the bone elements and pathological calcification as seen on x-ray films, computerized tomography (CT) scans, and magnetic resonance (MR) images, and was enhanced after injection of contrast medium on both CT scans and MR imaging.     

Stereotactic management of colloid cysts: factors predicting success

Stereotactic aspiration is a valuable surgical alternative for colloid cysts when used alone or in conjunction with microsurgical resection. Since 1981, the authors have performed computerized tomography (CT)-guided stereotactic aspiration as the initial procedure in 22 patients with colloid cysts; stereotactic aspiration alone was successful in 11 patients (50%). Of the 11 patients in whom aspiration failed, stereotactic endoscopic resection was attempted in three and was successful in one. Seven patients required a craniotomy and microsurgical removal of the cyst performed via a transcortical approach. The preoperative CT appearance in eight cases of a hypodense or isodense cyst correlated favorably with successful aspiration of the cyst in six patients. A hyperdense appearance on the preoperative CT scan in 14 cases was associated with subtotal aspiration in 13 patients; five required craniotomy for removal. Preoperative magnetic resonance (MR) imaging in eight patients provided excellent anatomical definition of the cyst and its relationship to other structures of the third ventricle, but it was not possible to correlate successful aspiration with cyst appearance on MR images with short or long relaxation time sequences. The authors' 9-year experience suggests that preoperative CT studies accurately determine size, predict viscosity, and help to define a group of colloid cyst patients for whom stereotactic cyst aspiration will likely be successful. Unsuccessful stereotactic aspiration was related to two features: the high viscosity of the intracystic colloid material (nine patients), or deviation of the cyst away from the aspiration needle due to small cyst volume (two patients). Because of its simplicity and low risk, stereotactic surgery can be offered to selected patients as the initial procedure of choice. Craniotomy can be reserved for those whose imaging studies predict failure or for those whose cyst cannot be aspirated.     

Posterior fossa epidermoid cysts presenting with unusual radiological appearances--two case reports

Intracranial epidermoid cysts generally appear as hypodense on computed tomography (CT), hypointense on T(1)-weighted magnetic resonance (MR) imaging, and hyperintense on diffusion-weighted MR imaging. We report two cases of posterior fossa epidermoid cysts with unusual radiological features. A 49-year-old male presented with facial dysesthesia and a 12-year-old male presented with diplopia and internuclear ophthalmoplegia. CT of both cases revealed hyperdense lesions. MR imaging showed the first case as hypointense in the posterior part and hyperintense in the anterior part of the tumor on diffusion-weighted imaging, and the second case as hyperintense on diffusion-weighted and T(1)-weighted MR imaging. Surgical exploration revealed that the tumors consisted of creamy materials, instead of the usual semi-solid or flaky texture in epidermoid cysts. Xanthochromic serous fluid was also contained in the superoposterior half of the cyst of the first case. These unusual contents of the cyst may be responsible for the unusual neuroimaging findings. Histological examination showed both cysts were lined with stratified squamous epithelium and contained keratinaceous materials. Therefore, epidermoid cysts can occasionally present with unusual radiological characteristics giving rise to a diagnostic pitfall.     

Comparative evaluation of intracranial epidermoid tumors with computed tomography and magnetic resonance imaging

The diagnosis of intracranial epidermoid tumors with computed tomography (CT) is often difficult because of indistinct margins, close proximity to the skull base, and a density similar to that of cerebrospinal fluid (CSF). Recent experience with six histologically confirmed epidermoid tumors served to emphasize the value of magnetic resonance (MR) imaging in studying these lesions. MR images were obtained using varying spin echo and inversion recovery techniques with a 0.5-tesla superconducting magnet. CT with and without enhancement had been performed in each case. In Case 1, CT showed an ill-defined left cerebellopontine angle hypodensity. MR imaging clearly showed the presence of abnormal tissue at that location. Case 2 showed a CSF density mass in the right upper posterior fossa. MR imaging of that area showed a variegated signal of a mass extending supratentorially. CT of Case 3 showed a left medial middle fossa hypodensity with an enhancing rim. MR imaging showed a clearly extraaxial mass in that location. In Case 4, a diffuse cerebellar hemispheric hypodensity was observed on CT and was clearly demarcated by MR studies. A huge lesion, thought initially to be an arachnoid cyst on CT of Case 5, was seen on MR imaging to be a large, extraventricular mass displacing the temporal lobe. Finally, CT in Case 6 was suggestive of a poorly demarcated right cerebellopontine angle lesion, which was seen on MR images to be extraaxial, displacing the brain stem. Various MR images more clearly demonstrate the extent of abnormal tissue than CT of epidermoid tumors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of computerized tomography and magnetic resonance imaging for the postoperative assessment of residual acoustic tumor

Ten patients with surgically confirmed residual cerebellopontine angle neuromas, imaged by both computerized tomography (CT) with iodine contrast and magnetic resonance (MR) with and without gadolinium enhancement, are reviewed to identify the strengths and limitations of MR as compared with CT imaging. MR imaging offers superior anatomic resolution in multiple imaging planes without ionizing radiation, but it is expensive and has adverse effects on some patients. CT imaging offers good anatomic resolution, but in only one or two planes. CT is both less expensive and generally well tolerated, but allergy to the iodine contrast is not uncommon. The cases presented demonstrate the adequacy of CT imaging of residual tumor. However, in some cases MR imaging provided important additional detail. MR imaging also demonstrated postoperative changes within the brain stem and cerebellum. In our experience, CT imaging remains a satisfactory, unambiguous approach to the assessment of known postoperative residual cerebellopontine angle neuromas. MR imaging provides superior resolution, however, and should be used when better definition of tumor detail is needed for management decisions or when multiple follow-up scans are anticipated, so that the exposure to ionizing radiation is limited. MR is also useful to investigate postoperative neurologic dysfunction. Postoperative changes and residual tumors are more difficult to interpret on MR than on CT. Guidelines are proposed to help distinguish residual tumor from postoperative changes and scarring.     

Ameloblastic carcinoma of the mandible resembling odontogenic cyst in a panoramic radiograph.

Ameloblastic carcinoma is a rare odontogenic tumor exhibiting histologic evidence of malignancy in the primary or recurrent tumor, regardless of whether it has metastasized or not. Most ameloblastic carcinomas are presumed to have arisen de novo, with few cases of malignant transformation of ameloblastoma being apparent. A case is reported of a 21-year-old caucasian female with ameloblastic carcinoma in the left angulus area of the mandible resembling an odontogenic cyst in the panoramic radiograph. In addition to the panoramic radiograph, computerized tomography (CT) and magnetic resonance (MR) images were taken preoperatively. This report demonstrates that CT or MR examinations may be crucial in differentiating odontogenic tumors from cysts.     

Comparison of computerized tomographic and radionuclide methods in determining intracranial cystic tumor volumes

The dosimetry of radioactive phosphorus (32P) for intracavitary treatment of cystic brain tumors is dependent upon accurate determination of the cyst volume. The authors have used both high-resolution computerized tomography (CT) scanning and an isotope dilution technique with technetium-99m (99mTc) sulfur colloid to determine cyst volumes in an experimental model and in six patients with intracerebral cystic tumors. In six separate comparisons using an experimental phantom "cyst," no significant differences between CT and 99mTc values were detected. In six patients with cystic neoplasms varying from 3 to 6.7 ml in volume, the percent differences between values obtained by CT and isotope dilution ranged from -17.26% to +13.13%. In individual patients, these differences proved to be of little significance for planning dosimetry. In both experimental and clinical trials comparing isotope dilution and CT measurement techniques, the CT technique using the standard software of the scanner and 5-mm thick slices proved to be a highly accurate method of determining cyst volume. The authors now base dosimetric calculations for intracavitary radiation with 32P on CT technique alone.     

Intradiploic arachnoid cyst identified by diffusion-weighted magnetic resonance imaging--case report

A 72-year-old woman presented with an intradiploic arachnoid cyst in the occipital intradiploic space which was found incidentally by magnetic resonance (MR) imaging. Computed tomography revealed a widened diploic space and thinning of the inner and outer tables of the occipital bone. The cyst appeared as isointense to the cerebrospinal fluid on both T1- and T2-weighted images. The differential diagnosis of intradiploic epidermoid cyst could be excluded because the lesion was low intensity on diffusion-weighted MR images. Arachnoid cyst is a benign lesion, so exploratory surgery should be avoided unless the cyst is symptomatic. Diffusion-weighted MR imaging is an effective modality to distinguish diploic epidermoid cysts from arachnoid cysts.     

An extramedullary spinal cord tumor associated with syringomyelia: a case report

A 53-year-old woman presenting weakness in the left hand for ten years was diagnosed seven years ago as having juvenile muscular atrophy of the unilateral upper extremity. Afterwards, her left forearm and hand gradually became weaker. A neurologist pointed out syringomyelia in the film of MR imaging. However, the cause of syringomyelia was not demonstrated until gadolinium-DTPA-enhanced MR imaging disclosed a spinal tumor. Through an operation it was found that it was an intradural extramedullary tumor at C7 level. Histological diagnosis of the tumor was meningioma. Only 12 reports of syringomyelia associated with extramedullary intraspinal tumors were found. Among them each tumor in three cases was diagnosed by delayed metrizamide computed tomography, only one case by MR imaging. Though in our case myelography, postmyelographic CT, intravenous enhanced CT and MR imaging were performed, gadolinium-DTPA-enhanced MR imaging was eventually most useful in diagnosing this tumor. The pathophysiologic mechanism by which the syrinx fills, and the differentiation in MR imaging between syrinx and tumor cyst were reviewed.     

Diagnostic Medical Radiation Dose in Patients After Laparoscopic Bariatric Surgery

Background  

The purpose of this study was to estimate the cumulative radiation dose from computed tomography (CT) scans and upper gastrointestinal fluoroscopic exams in the post-bariatric-surgery population and correlate these values with current concepts of potential radiation-induced cancer risk.     

Imaging of the hip joint. Computed tomography versus magnetic resonance imaging.

The authors reviewed the applications and limitations of computed tomography (CT) and magnetic resonance (MR) imaging in the assessment of the most common hip disorders. Magnetic resonance imaging is the most sensitive technique in detecting osteonecrosis of the femoral head. Magnetic resonance reflects the histologic changes associated with osteonecrosis very well, which may ultimately help to improve staging. Computed tomography can more accurately identify subchondral fractures than MR imaging and thus remains important for staging. In congenital dysplasia of the hip, the position of the nonossified femoral head in children less than six months of age can only be inferred by indirect signs on CT. Magnetic resonance imaging demonstrates the cartilaginous femoral head directly without ionizing radiation. Computed tomography remains the imaging modality of choice for evaluating fractures of the hip joint. In some patients, MR imaging demonstrates the fracture even when it is not apparent on radiography. In neoplasm, CT provides better assessment of calcification, ossification, and periosteal reaction than MR imaging. Magnetic resonance imaging, however, represents the most accurate imaging modality for evaluating intramedullary and soft-tissue extent of the tumor and identifying involvement of neurovascular bundles. Magnetic resonance imaging can also be used to monitor response to chemotherapy. In osteoarthrosis and rheumatoid arthritis of the hip, both CT and MR provide more detailed assessment of the severity of disease than conventional radiography because of their tomographic nature. Magnetic resonance imaging is unique in evaluating cartilage degeneration and loss, and in demonstrating soft-tissue alterations such as inflammatory synovial proliferation.     

Congenital dacryocystocele with intranasal extension: correlation of computed tomography and magnetic resonance imaging

A case of dacryocystocele with intranasal extension is described by magnetic resonance imaging (MRI) characteristics, which are correlated with the appearance on computed tomography (CT) scans. Computed tomography and MRI are equally sensitive in detecting dacryocystocele. Magnetic resonance imaging has the advantages of characterizing the cyst contents, allowing multiplanar imaging without the need for manipulation of the patient, and the absence of radiation exposure. Computed tomography has the advantage of detecting bone changes involving the bony nasolacrimal canal. Clinically, these abnormalities usually resolve spontaneously and only rarely require surgical intervention.     

Magnetic resonance imaging of the sella turcica and parasellar region. A clinical-radiographic evaluation with computed tomography

Thirty-one magnetic resonance (MR) scans and computed tomography (CT) scans were obtained on 25 patients in whom lesions involving the sella turcica or parasellar region were clinically suspected. Surgical pathologic studies were available in 19 cases. Twenty-two of the MR scans were of diagnostic value equivalent to that of the corresponding CT studies. In two small meningiomas, an empty sella, and a sphenoid-middle fossa tumor, MR technology failed to delineate the pathologic process adequately. In the remaining five patients, MR either more convincingly demonstrated the pathologic anatomy or yielded diagnostic information not present in the CT study. In view of the absence of ionizing radiation, high degree of tissue contrast and spatial resolution, and multiplanar capability, magnetic resonance scanning will probably become the initial imaging modality of choice in patients suspected of harboring sellar and parasellar tumors.     

Magnetic resonance imaging of the thyroid, thymus, and parathyroid glands

Magnetic resonance (MR) images of the neck were obtained in 16 patients with use of a variety of spin echo and inversion recovery pulse sequences. Anatomic resolution was best with high-resolution spin echo images obtained with the pulse sequence repetition rate equal to 2.0 seconds and the echo delay equal to 28 msec because this imaging technique offered excellent contrast between normal tissues and had the highest signal noise ratio. The spatial resolution of MR was nearly as good as state of the art computerized tomography (CT). However, streak artifacts caused by motion and x-ray beam hardening often limited CT but did not affect MR. Tumors and lymph nodes were more easily differentiated from muscle and blood vessels with MR than with CT because of the superior soft-tissue contrast of MR. Tissue characterization allowed MR differentiation of thyroid nodules, thyroid cysts, and parathyroid tumors from normal thyroid tissue. Thyroid cyst fluid had the greatest water content and longest T1 and T2 relaxation times of all tissues studied. However, nonspecifically increased T1 and T2 relaxation times overlapped for a variety of neoplastic and inflammatory conditions. With further experience, MR imaging is likely to become a useful technique for the evaluation of neck masses.     

Craniopharyngiomas: fluctuation in cyst size following surgery and radiation therapy

Patients with craniopharyngiomas who demonstrate cyst enlargement after surgery and radiation are often presumed to be treatment failures. Therapeutic approaches in various centers include repetitive cyst aspirations, surgical reexcision, and installation of cytotoxic agents such as methotrexate, 32P, or 198Au. Each intervention has associated severe or even lethal side effects. Not all patients with craniopharyngioma who have cystic enlargement after primary therapy require an intervention, as demonstrated by 4 patients recently managed in the University of Rochester Medical Center. Since 1978, when computed tomography was routinely in use, we have managed 11 patients with craniopharyngiomas who were treated with surgery followed by radiation therapy. Three of these patients demonstrated post-irradiation enlargement of the residual cystic component followed by a decrease in size without surgical intervention. An additional patient showed cystic growth followed by stabilization of size. It is noteworthy that the cyst enlarged within the first 5 months after radiation therapy in the 3 patients who subsequently demonstrated a diminution in the size of their cysts. This suggests that the mechanism for cyst formation remained intact and subsequently abated because of a radiation-induced lesion. We conclude that after treatment with surgery and radiation therapy, the cystic component of craniopharyngiomas may increase and, without intervention, subsequently decrease in size. Thus, in the asymptomatic patient who demonstrates cystic growth soon after primary therapy, close observation alone may be warranted.     

Dynamic and three-dimensional transcranial ultrasonography of an arachnoid cyst in the cerebral convexity. Technical note

Structural imaging of the brain, such as cerebral computerized tomography (CT) and magnetic resonance (MR) imaging, is state-of-the-art. Dynamic transcranial (dTC) ultrasonography and three-dimensional (3D) transcranial color-coded duplex (TCC) ultrasonography are complementary, noninvasive procedures with the capacity for real-time imaging, which may aid in the temporary management of space-occupying lesions. A 16-year-old woman presented with recurrent tension-type headaches. A space-occupying arachnoid cyst in the cerebral convexity was demonstrated on MR images. The patient underwent an examination for raised intracranial pressure. which was performed using a standard color-coded duplex ultrasonography system attached to a personal computer-based system for 3D data acquisition. Transcranial ultrasonography was used to identify the outer arachnoid membrane of the cyst, which undulated freely in response to rotation of the patient's head (headshake maneuver). Three-dimensional data sets were acquired and, using a multiplanar reformatting reconstruction algorithm, the authors obtained high-resolution images that corresponded to the initial MR image and a follow-up cranial CT scan. No detectable differences were observed on dTC or 3D TC ultrasonograms obtained at follow-up examinations performed 9 and 28 months later. Three-dimensional TCC and dTC ultrasonography may complement conventional diagnostic procedures such as MR and CT imaging. This report represents evidence of the high resolution and good reproducibility of 3D TC methods. Ultrasonography is a mobile and inexpensive tool and may be used to improve management and therapeutic strategies for patients with space-occupying brain lesions in selected cases.     

Post-traumatic peripheral facial nerve palsy: surgical and neuroradiological consideration in five cases of delayed onset

The facial nerve is frequently injured after head trauma with or without temporal bone fractures. Computed tomography (CT) is the best procedure for detecting the fracture line at the level of the facial nerve canal and for assessing any associated lesions within the temporal bone. Magnetic resonance (MR) is required if there is a facial nerve paralysis, unexplained by CT findings. We present five cases of delayed post-traumatic facial nerve palsy without evidence of temporal bone fractures on CT, thus studied on MR. MR was essential for diagnosing the nerve impairment. Neuroradiological findings, clinical presentation, and electrodiagnostic tests influenced the management of the patients.     

Radiologic characteristics and results of surgical management of Rathke's cysts in 43 patients.

Although Rathke's cysts are a relatively common autopsy finding, rarely have they been reported as a clinical entity. Because of recent improvements in neuroradiological imaging, cystic intrasellar and suprasellar lesions are discovered often, leading to questions about proper management. Against this background, we reviewed the data from 43 patients with Rathke's cysts treated by one neurosurgeon over a 13-year period, and present the results here. The 43 patients had a mean age of 34 years, and 77% were female. Headache was the most common symptom, followed by galactorrhea, visual field loss, and hypopituitarism. Computed tomographic (CT) scans were reviewed in 20 cases, magnetic resonance (MR) images were reviewed in 15, and both CT and MR studies were reviewed in 5 cases. Although all Rathke's cysts were discrete and well-defined by both CT and MR imaging, the diversity of locations, CT attenuations, and MR signal intensity make it difficult to establish the diagnosis by radiological criteria. Forty patients underwent transsphenoidal surgery and three underwent craniotomy. There was one recurrence at 25 months requiring a second operation, and the mean follow-up period was 62 months. Seven patients had persistent headaches. For symptomatic lesions suspected to be Rathke's cysts, the recommended treatment is simple drainage of the cyst with biopsy of the wall, when this can be done safely. Follow-up imaging should be minimal for asymptomatic patients, and radiation therapy is not indicated.     

Endoscopic Surgery for Hemorrhagic Pineal Cyst Following Antiplatelet Therapy: Case Report

Pineal cysts of the third ventricle presenting with acute obstructive hydrocephalus due to internal cystic hemorrhage are a rare clinical entity. The authors report a case of a 61-year-old man taking antiplatelet medication who suffered from a hemorrhagic pineal cyst and was treated with endoscopic surgery. One month prior to treatment, the patient was diagnosed with a brainstem infarction and received clopidogrel in addition to aspirin. A small incidental pineal cyst was concurrently diagnosed using magnetic resonance (MR) imaging which was intended to be followed conservatively. The patient presented with a sudden onset of headache and diplopia. On admission, the neurological examination revealed clouding of consciousness and Parinaud syndrome. Computerized tomography (CT) scans demonstrated a hemorrhagic mass lesion in the posterior third ventricle. The patient underwent emergency external ventricular drainage with staged endoscopic biopsy and third ventriculostomy using a flexible videoscope. Histological examination revealed pineal tissue with necrotic change and no evidence of tumor cells. One year later MR imaging demonstrated no evidence of cystic lesion and a flow void between third ventricle and prepontine cistern. In patients with asymptomatic pineal cysts who are treated with antiplatelet therapy, it is important to be aware of the risk of pineal apoplexy. Endoscopic management can be effective for treatment of hemorrhagic pineal cyst with obstructive hydrocephalus.