Magnetic resonance imaging of neurohypophyseal germinomas

Article Abstract:

The majority of tumors of the pineal gland do not arise from pineal cells, but rather from cells of the germ line (cells normally located in the ovaries or testes that give rise to eggs or sperm). These tumors, called dysgerminomas (germinomas), may occur elsewhere in the brain, most notably the hypothalamus and the neural portion of the pituitary gland, the neurohypophysis. The germinoma develops preferentially in structures located along the midline of the brain. When such tumors are found in the pituitary gland, they are sometimes referred to as ectopic pinealomas. It is uncertain where such tumors originate. The authors discuss the use of magnetic resonance imaging (MRI) in evaluating seven patients with neurohypophyseal germinomas. The pituitary gland is connected to the hypothalamus by the slender infundibular stalk, which emerges from the brain at the site of the optic chiasm, where the optic nerves partially cross and enter the brain. The pituitary gland itself resides in a bony recess, the sella turcica. In six of the present patients, MRI clearly revealed the portion of the tumor within the sella. In two cases, the entire small germinoma was intrasellar. In four cases of large germinomas, major portions beneath the optic chiasm were visible on MRI, and large intrasellar portions of the tumor could also be identified in these patients. In the remaining case, the tumor was located on the infundibular stalk and within the hypothalamus itself, extending to the third ventricle within the hypothalamus. The most common form of pituitary tumor is the pituitary adenoma, a tumor arising in the anterior lobe of the pituitary. The neurohypophyseal germinoma, arising in the posterior lobe, may be distinguished on the basis of three factors. The dysgerminoma tends to occur in younger patients (often in adolescents, and rarely in patients over 30), the germinoma tends to cause excessive water loss from the kidneys (diabetes insipidus), and the germinoma has distinct appearances on magnetic resonance imaging, illustrated in this report. The rapid diagnosis of neurohypophyseal germinoma is important, since the tumor is especially sensitive to radiation therapy, and early treatment may result in long-term survival. (Consumer Summary produced by Reliance Medical Information, Inc.)

Germ cell tumors, Germinoma, Pituitary gland tumors, Pituitary tumors

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Gallbladder carcinoma: evaluation with MR imaging

Article Abstract:

Gallbladder cancer is rare, but it is often fatal when it does occur. It is highly treatable by surgical removal of the gallbladder when the cancer has not spread to other tissues, but this type of cancer grows and spreads quickly, and when it is discovered, it is only rarely confined to the gallbladder. Magnetic resonance imaging (MRI) is a diagnostic imaging technique that can produce highly differentiated images of tissues and organs. This study examined the characteristics of gallbladder cancer on magnetic resonance images to determine whether MRI was useful in evaluating this type of cancer. MRI was performed on 19 patients suffering from gallbladder cancer. All patients underwent surgery within one to two weeks following MRI examination. Surgical findings confirmed that in all patients, the cancer had spread beyond the gallbladder to some degree. MRIs revealed the main tumor on the gallbladder in all patients. For 11 patients, the tumor appeared as a large mass almost replacing the gallbladder. For eight patients, the tumor appeared to infiltrate the gallbladder with areas of wall thickening. MRI was able to detect cancerous invasion of the liver in 11 of 13 cases. In the two cases where MRI did not detect liver involvement, the invasion was minimal. Liver tumors were seen on MRIs from five patients. Tumors were found in three cases during surgery that were not detected by MRI. These tumors were all less than 2 cm in diameter. No spread of cancer to the intestines was found when MRI showed clearly defined high-intensity fatty tissue separating the main tumor from the intestine, but it was found in 6 of 10 cases where the fatty tissue separation was not clearly defined. MRI was also able to detect cancer spread to surrounding ligaments and blood vessels. These results indicate that MRI is useful in detecting and staging gallbladder cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Usage, Cancer, Gallbladder cancer

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Endometrial cysts: diagnosis with MR imaging

Article Abstract:

The endometrium is the mucous membrane layer that lines the wall of the uterus. Sometimes endometrial tissue grows abnormally outside the uterus, a condition known as endometriosis, and forms cysts on surrounding organs and tissues. These cysts are similar in appearance to cancerous tissue. Various imaging techniques have been evaluated for use in differentiating endometrial cysts from cancerous growths. Magnetic resonance imaging (MRI) is a diagnostic imaging technique that uses the different magnetic properties of various molecules to differentiate tissues and organs. This study examined the effectiveness of MRI in differentiating endometrial cysts from other abnormal growths. MRI was performed on 374 women who had abnormal gynecologic masses. Results were compared with findings at surgery for 293 patients and at clinical follow-up for 78 patients. Surgical exploration uncovered 86 endometrial cysts in 64 patients and 268 gynecologic masses that were not endometrial in nature in 239 patients. MRI correctly identified 77 of the 86 endometrial cysts. Of the other 268 masses, MRI incorrectly diagnosed only five as being endometrial cysts. MRI diagnosed endometrial cysts in 41 of the 78 patients that were only followed-up clinically. Follow-up in these cases had not shown any of the cysts to appear to be cancerous. Overall, MRI showed a sensitivity (accuracy in diagnosing positive cases) of 90 percent, a specificity (accuracy in identifying negative cases) of 98 percent, and an accuracy of 96 percent in diagnosing endometrial cysts. These results indicate that MR imaging is very useful in differentiating endometrial cysts from other gynecologic masses. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Abnormalities, Diagnosis, Endometriosis, Endometrium, Cysts

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