MR of the pituitary gland postsurgery: serial MR studies following transsphenoidal resection.

PURPOSE: To determine the MR appearance of the pituitary gland in the early and late postoperative periods in order to distinguish operative complications more effectively and to establish a postoperative baseline. METHODS: Ten patients were prospectively studied with MR following transsphenoidal resection of a pituitary tumor. Early postoperative studies were obtained at 2 to 8 days following surgery, late studies at 4 to 9 months in all patients and also at 12 to 16 months in five. Major observations were height of the pituitary mass and appearance of the surgical packing. RESULTS: Within 8 days following surgery, the height of the pituitary mass was unchanged in two cases, increased in three, and only minimally decreased in five. All decreased in height (average 54%) by 4 to 9 months. Gelfoam packing completely (five) or nearly completely (three) resorbed leaving a normal-size, although deformed, pituitary gland. Fat-packed resection defects persisted (two). CONCLUSIONS: In the early postoperative period, the appearance of the pituitary gland is similar in size to its preoperative appearance. Subsequent involution with packing resorption yields a smaller, deformed pituitary gland.

Lymphocytic hypophysitis: occurrence in two men.

Two men undergoing transsphenoidal exploration for pituitary adenoma were found to have lymphocytic hypophysitis. Both presented with frontal headaches, lethargy, and diminished libido. Laboratory investigations showed markedly depressed serum testosterone, and magnetic resonance imaging demonstrated pituitary enlargement, with optic chiasm involvement. Intraoperatively, the dura was adherent to the pituitary in each case. The resected glands were effaced by a dense lymphoplasmacytic infiltrate and fibrosis, without granulomas. Nonspecific peripheral enhancement on imaging suggested a diagnosis other than adenoma, but more experience with peripheral enhancement in lymphocytic hypophysitis is needed. The diagnosis was histological and required surgical intervention. Long-term pituitary replacement therapy is usually required.

Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation.

We performed magnetic resonance imaging on sixty-seven individuals who had never had low-back pain, sciatica, or neurogenic claudication. The scans were interpreted independently by three neuro-radiologists who had no knowledge about the presence or absence of clinical symptoms in the subjects. About one-third of the subjects were found to have a substantial abnormality. Of those who were less than sixty years old, 20 per cent had a herniated nucleus pulposus and one had spinal stenosis. In the group that was sixty years old or older, the findings were abnormal on about 57 per cent of the scans: 36 per cent of the subjects had a herniated nucleus pulposus and 21 per cent had spinal stenosis. There was degeneration or bulging of a disc at at least one lumbar level in 35 per cent of the subjects between twenty and thirty-nine years old and in all but one of the sixty to eighty-year-old subjects. In view of these findings in asymptomatic subjects, we concluded that abnormalities on magnetic resonance images must be strictly correlated with age and any clinical signs and symptoms before operative treatment is contemplated.

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation.

Previous investigations with plain radiography, myelography, and computed tomography have shown that degenerative disease of the cervical spine frequently occurs in the absence of clinical symptoms. We studied the magnetic resonance-imaging scans of sixty-three volunteers who had no history of symptoms indicative of cervical disease. The scans were mixed randomly with thirty-seven scans of patients who had a symptomatic lesion of the cervical spine, and all of the scans were interpreted independently by three neuroradiologists. The scans were interpreted as demonstrating an abnormality in 19 per cent of the asymptomatic subjects: 14 per cent of those who were less than forty years old and 28 per cent of those who were older than forty. Of the subjects who were less than forty, 10 per cent had a herniated nucleus pulposus and 4 per cent had foraminal stenosis. Of the subjects who were older than forty, 5 per cent had a herniated nucleus pulposus; 3 per cent, bulging of the disc; and 20 per cent, foraminal stenosis. Narrowing of a disc space, degeneration of a disc, spurs, or compression of the cord were also recorded. The disc was degenerated or narrowed at one level or more in 25 per cent of the subjects who were less than forty years old and in almost 60 per cent of those who were older than forty. The prevalence of abnormal magnetic-resonance images of the cervical spine as related to age in asymptomatic individuals emphasizes the dangers of predicating operative decisions on diagnostic tests without precisely matching those findings with clinical signs and symptoms.

The use of diagnostic imaging to assess spinal arthrodesis.

Despite advances in surgical techniques and internal fixation devices, pseudarthrosis remains a significant factor in the clinical failure of attempted fusions in the cervical, thoracic, and lumbar spine. This article reviews the use of diagnostic imaging in the assessment of spinal fusion, with a focus on the accuracy of different imaging modalities based on surgical exploration. A cost-effective strategy for the radiographic follow-up of patients after spinal fusion surgery also is presented.

Cerebral mucormycosis: a case report.

Mucormycosis is an unusual complication in immunosuppressed and diabetic patients. Disseminated mucormycosis is even more unusual. One patient with both pulmonary and cerebral mucormycosis is presented. The clinical course is outlined and computed tomographic (CT) findings are presented.

Primary central nervous system lymphoma versus toxoplasmosis in AIDS.

The imaging studies of 16 patients with acquired immunodeficiency syndrome (AIDS) and proved primary central nervous system (CNS) lymphoma were reviewed. All studies included computed tomography (CT); six also included magnetic resonance (MR) imaging. A periventricular lesion was seen in 50% of patients. At least one such lesion exhibited subependymal spread or ventricular encasement in 38%. One-third of lesions in three of five patients who underwent nonenhanced CT were hyperattenuating. Five lesions were at least in part hypointense on T2-weighted MR images. The specificity of these findings was evaluated with a similar review of the imaging studies in 28 patients with AIDS and proved toxoplasmosis. Only 3% of lesions were periventricular. None exhibited subependymal spread or encasement. None were hyperattenuating on nonenhanced CT scans. Similar findings in other CNS lesions in AIDS patients could not be found in the literature. A focal enhancing mass with subependymal spread on CT or MR images and hyperattenuation at nonenhanced CT were the most reliable features in distinguishing between primary CNS lymphoma and toxoplasmosis in AIDS patients.

Lymphomatous meningitis and steroid-induced epidural lipomatosis: CT evaluation.

A case of spinal cord compression secondary to steroid-induced epidural lipomatosis is reported. The epidural lipomatosis developed in a setting of spinal lymphomatous leptomeningitis secondary to adult T-cell leukemia/lymphoma, an unusual type of non-Hodgkin lymphoma with a high frequency of leptomeningeal involvement. Computed tomography was invaluable in diagnosing epidural lipomatosis, despite the concomitant spinal lymphomatous leptomeningitis. To our knowledge this is the first case of epidural lipomatosis following chemotherapy for a malignancy.

Lumbar spine after surgery for herniated disk: imaging findings in the early postoperative period.

Imaging the lumbar spine after surgery for disk herniation is all too often an unrewarding challenge. A constellation of findings is inevitable, and determining their significance is often impossible. The challenge is greatest during the first few months following surgery, when the rules of scar enhancement, deformity, and mass effect do not apply to differentiation of the abnormal from the normal. A clear understanding of normal postoperative healing is necessary to avoid overreaction to misleading findings. This report reviews imaging of the lumbar spine in the early postoperative period (i.e., the first 6 months after surgery), focusing on the normal healing process that so often mimics complicating or recurrent disease.

Glioblastoma oncometry.

A prospective study of 20 patients was conducted to determine changes in the computed tomography appearance of glioblastomas seen at the completion of radiation therapy. An interval CT was obtained after 4000 to 4500 cGy to the whole brain and was compared to a similar baseline study. The tumor volume increased in twelve patients by 13 to 878% (mean 126%) and decreased in seven by 13 to 73% (mean 37%). It remained unchanged in one patient. A broadening or thinning of the enhancing rim frequently accompanied the increased or decreased tumor, respectively. Volume change immediately after whole brain radiotherapy was no prognostic indicator. The volume increase seen in 60% of the patients had implications for treatment planning of the boost field. It translated into a potential field size increase of up to 5.6 cm (mean 3.5 cm) and could contribute to a geographic miss. It is concluded that following whole brain radiation therapy, a repeat CT scan or magnetic resonance imaging, depending on the initial exam, is necessary for optimal planning of the reduced radiation field.

Magnetic resonance imaging evidence of a focal pontine ischemia in sudden hearing loss and seventh nerve paralysis.

Sudden sensorineural hearing loss (SSHL) has been associated with many etiologies. However, determining the exact cause of SSHL remains elusive. Recent reports have demonstrated the usefulness of magnetic resonance imaging in identifying the site of lesion in SSHL. This report presents the case of a 68-year-old male who presented with right-sided SSHL associated with right-sided facial paralysis. Magnetic resonance imaging demonstrated a focal area of increased signal on T2-weighted image within the right inferior pons, suggestive of a postischemic edematous focus. Magnetic resonance imaging is becoming important in establishing the etiology of SSHL. Magnetic resonance imaging findings in cases of hearing loss are discussed.

Postoperative diskitis: distinguishing early MR imaging findings from normal postoperative disk space changes.

To distinguish early magnetic resonance (MR) imaging findings in postoperative diskitis from normal postoperative changes, a prospective study was performed in 15 asymptomatic patients (17 disk levels) who underwent uncomplicated lumbar diskectomy and seven patients with proved postoperative diskitis. On postoperative MR images, four of the asymptomatic patients had a finding that could also be seen in patients with diskitis. Gadolinium enhancement was useful in making the distinction and occurred as follows: (a) vertebral bone marrow: all seven diskitis patients and one asymptomatic patient; (b) disk space: five diskitis patients and three asymptomatic patients; and (c) posterior anulus fibrosus: all seven diskitis patients and 13 asymptomatic patients (14 of 17 levels). This entire triad of findings, which is strongly suggestive of postoperative diskitis, was not seen in any of the asymptomatic patients. Changes in the disk space and adjacent bone marrow on pre- and post-contrast MR images after routine diskectomy are uncommon and should not be assumed to be normal postoperative changes without careful consideration and analysis for early diskitis.

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.

Contrast-enhanced MR imaging performed after successful lumbar disk surgery: prospective study.

A prospective study was undertaken to establish the normal spectrum and timing of gadolinium-enhanced magnetic resonance (MR) imaging findings in 15 patients who had resolution of symptoms after successful lumbar disk surgery. Enhancement of the facet joints (in 88% of disk levels) and paraspinal muscles (100%) decreased gradually after surgery. Enhancement of the decompressed nerve root tracked proximally toward the conus medullaris in 62% at 3 weeks and was absent in all by 6 months postoperatively. Areas of intermediate signal intensity with peripheral enhancement and mass effect were seen on T1-weighted images at the site of the original disk herniation in 38% at 3 weeks and 12% at 3 months, despite complete relief of leg pain. These results reveal that even in successfully treated (asymptomatic) patients, residual mass effect on the neural elements may frequently simulate a recurrent or residual disk fragment. There is an orderly progression of imaging changes during the first 6 months after lumbar surgery that limits the interpretation of MR examinations during that period.