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Biomedical subjects

R D Zimmerman

Publications and source records attributed to R D Zimmerman.

At least 37 records · Page 2Linked to original sources
PubMed1989

MR imaging of brain abscesses.

The MR images and CT scans of 14 patients with surgically verified pyogenic cerebral abscesses were reviewed. The MR findings correlated well with those seen on CT and were believed to be sufficiently characteristic to allow early and accurate diagnosis with MR alone. These features include (1) peripheral edema producing mild hypointensity on short TR/short TE and marked hyperintensity on long TR/intermediate to long TE scans; (2) central necrosis with abscess fluid hypointense relative to white matter and hyperintense relative to CSF on short TR/short TE scans and hyperintense relative to gray matter on long TR/intermediate to long TE scans (the fluid had concentric zones of varying intensity in seven cases, a finding not previously identified in other lesions); (3) extraparenchymal spread (intraventricular or subarachnoid), which was detected more easily on MR than on CT and was manifested by increased intensity relative to normal CSF on both short TR/short TE and long TR/intermediate TE scans; and (4) visualization of the abscess capsule, which was iso- to mildly hyperintense relative to brain on short TR/short TE scans and iso- to hypointense relative to white matter on long TR/intermediate to long TE scans. On the long TR scans, the relative hypointensity of the rim allowed for visualization of the typical morphologic features of the capsule, which in turn aided in differentiation of abscesses from other lesions (as it does on CT). To investigate the cause of the capsular intensity, pathologic studies of the capsules were reviewed when available (10 cases). Fibrosis was identified in all mature abscess capsules, but the combination of the intensities seen on short TR/short TE and long TR/intermediate to long TE scans as well as the temporal changes in intensity were believed to be incompatible with fibrosis as a cause of the capsular changes. Intensity patterns were suggestive of hemorrhage, but neither acute nor chronic hemorrhage was identified on routine H and E stains, while iron stain revealed scant hemorrhage in only two of the eight patients in whom these stains were used. We believe the capsular intensity (in particular the hypointense rims on long TR scans) may reflect paramagnetic T1, and to a greater extent T2, shortening, possibly due to the presence of heterogeneously distributed free radicals that are products of the respiratory burst produced by actively phagocytosing macrophages in the capsule wall. Distinctive MR features of pyogenic abscesses should afford early and accurate diagnosis.

Brain↗
PubMed1988

Magnetic resonance imaging in amateur boxers.

Nine amateur boxers who participated in the 1985 and 1986 New York City Golden Gloves competition underwent detailed neurologic examinations and magnetic resonance (MR) scanning. All nine boxers were medically suspended secondary to a knockout or excessive head blows. Neurologic examination results and MR scans were normal in all nine boxers. Failure to detect abnormalities on the MR scan, by neurologic examination, or both in these amateur boxers may reflect several factors, including a small sample size, the duration between their last bout and neurologic evaluation, and the lower exposure to head trauma among amateur boxers compared with professionals.

Adolescent↗
PubMed1988

Malignant extradural spinal tumors: MR imaging with Gd-DTPA.

Magnetic resonance (MR) imaging with gadolinium diethylenetriaminepentaacetic acid (DTPA) was performed in 12 patients with neoplasia of the spine and epidural space. Postcontrast images were compared with precontrast images. Gd-DTPA MR images did not improve the detection of tumors affecting the epidural space of the spine. In fact, many lesions were isointense when compared with the intensity of the surrounding bone marrow and were difficult to see. Because of this, contrast material-enhanced images were not sufficient; however, when they were combined with precontrast images, the use of Gd-DTPA improved the delineation and characterization of certain lesions. Gd-DTPA MR images were helpful in differentiating disk herniation from epidural tumors, indicating regions of more active tumor for biopsy, outlining areas of spinal cord compression, and demonstrating tumor response to therapy. Therefore, while it may be unlikely that Gd-DTPA will be used routinely in every case of suspected neoplasia of the epidural space, contrast-enhanced images will undoubtedly have an adjunctive role in certain clinical applications.

Adult↗
PubMed1988

Acute intracranial hemorrhage: intensity changes on sequential MR scans at 0.5 T.

Thirty-seven patients underwent MR imaging at 0.5 T within 7 days of a CT-documented intracranial hemorrhage. A total of 57 hematomas were evaluated. Twelve patients underwent serial scanning and 12 patients had multiple hemorrhages into different intracranial compartments. The appearances of the hematomas on spin-echo (SE) images with a short repetition time (TR) of 500 msec and short echo time (TE) of 32 msec (SE 500/32), long TR/intermediate TE (SE 2000/60), and long TR/long TE (SE 2000/120) were carefully evaluated with specific attention to the precise time after ictus. Hematomas showed heterogeneous, complex, rapidly changing intensities. There was a significant amount of variation among patients, especially between the third and seventh days. Hematomas studied between 12 and 24 hr after hemorrhage were mildly hyperintense on short TR scans and markedly hyperintense on long TR (intermediate and long TE) scans (stage I). These findings in acute hemorrhage have received little prior attention. Over the next 1-2 days, hematomas became iso- to mildly hypointense on short TR scans and markedly hypointense on long TR scans (stage II). Hypointensity on long TR scans has previously been described at high field strengths; our communication demonstrates that this phenomenon is seen routinely at intermediate field strengths as well. Hematomas became markedly hyperintense on short TR scans beginning on approximately the fourth day postictus and redeveloped hyperintensity on long TR scans approximately 5-6 days after ictus (stage III). By the end of the first week they were hyperintense on all pulse sequences (stage IV). MR findings on the first day after intracranial hemorrhage (in particular, subtle hyperintensity on short TR scans) probably allow for a specific diagnosis, while the variable, hetergeneous, and rapidly changing intensities noted between days 2 and 7 are often less specific.

Acute Disease↗
PubMed1988

Gadolinium-DTPA in the evaluation of intradural extramedullary spinal disease.

Gadolinium-DTPA was used in MR imaging of the spine to determine the ability of a contrast agent to increase the detection and characterization of disease in the intradural extramedullary space. Although MR imaging, especially with recent technological improvements, has been shown to be at least competitive with, and often superior to, myelography and postmyelography CT in the study of intramedullary and extradural disease, its use in the assessment of intradural extramedullary disease has been questioned. We selected 12 patients with intradural extramedullary disease as demonstrated by positive CSF cytology and/or myelographic findings and performed MR examinations on them before and after administering gadolinium-DTPA (0.1 mmol/kg). Gadolinium-DTPA was extremely effective in depicting intradural extramedullary disease of the spine. Small nodules of 3 mm, virtually invisible on noncontrast MR scans, enhanced strongly and were easily detected. In addition, leptomeningeal spread of tumor along nerve roots was also visualized, sometimes more readily than by myelography and postmyelography CT. The remarkable sensitivity of gadolinium-DTPA to intradural extramedullary disease assures its role in future MR examinations of the spine.

Adult↗
PubMed1988

Intramedullary disease of the spine: diagnosis using gadolinium-DTPA-enhanced MR imaging.

Twenty-six patients with suspected lesions of the spinal cord were studied before and after administration of gadolinium-DTPA to assess whether contrast enhancement was useful in the MR evaluation of intramedullary disease. Nine patients had primary tumors, six had benign syringes, three had multiple sclerosis with cord involvement, three had thrombosed vascular malformations, three had probable intramedullary metastasis, and two were normal. Although all lesions were detected on noncontrast MR scans, gadolinium-DTPA was of great help in their delineation and characterization. Specifically, contrast material may be able (1) to localize tumor nidus and separate it from edema, in cases of hemangioblastomas and metastases; (2) to suggest regions of more active tumors, in cases of glioma, for surgical biopsy or removal; (3) to differentiate benign or reactive processes from neoplastic lesions, such as reactive cyst from tumor cyst or hematoma due to thrombosed malformation from tumor hemorrhage; and (4) possibly to differentiate active from inactive lesions, for example, in multiple sclerosis. Because of these advantages, gadolinium-DTPA probably will often be used routinely when intramedullary lesions are detected on noncontrast MR scans.

Adult↗
PubMed1988

The magnetic resonance imaging of infections and inflammatory diseases.

The MR features of inflammatory lesions of the central nervous system are reviewed in this article, and the sensitivity and specificity of MR and CT in the detection of these lesions are compared. The advent of CT dramatically improved the morbidity and mortality of inflammatory disease by facilitating earlier and more accurate diagnosis which, in turn, produced more timely medical and surgical intervention. The efficacy of MR in the evaluation of inflammatory lesions must, therefore, be compared to CT in order to accurately asses its role.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Hemorrhagic neoplasms: MR mimics of occult vascular malformations.

The MR scans of 24 patients who had findings previously reported to be characteristic of occult cerebral vascular malformations were reviewed to demonstrate that such findings may also occur in primary or secondary neoplasms. Eighteen of the 24 patients were found to have hemorrhagic neoplasms. Additional criteria, such as multiplicity of lesions and the presence of edema, were of some help in differentiating between occult vascular malformation and hemorrhagic neoplasm. In certain cases, CT was necessary to provide further information, such as the presence of calcification; however, an absolute and accurate diagnosis was impossible in several cases. The striking similarity on MR between cryptic vascular malformation and some hemorrhagic neoplasms is most likely due to the unifying mechanisms that underlie the evolution of extravascular intracerebral blood. Although the preponderance of neoplastic etiologies in our series may be partly due to the strong bias in our sample population toward patients with tumors, it seems clear that when an MR scan discloses findings "typical" of an occult vascular malformation, consideration must also be given to the generally more serious possibility of underlying neoplasm.

Adolescent↗
PubMed1986

Comparison of magnetic resonance imaging and computed tomography in the evaluation of head injury.

Thirty-five patients who had incurred head trauma were studied with computed tomography (CT) and magnetic resonance imaging (MRI). CT was performed using a General Electric 8800 scanner. MRI was conducted with a Technicare Teslacon system using a 5.0 kG (0.5 T) magnetic field. Clinically, patients varied from those with mild concussions without focal neurological signs to those with severe neurological dysfunction including posttraumatic coma. MRI was superior to CT in imaging 23 of 41 extracerebral fluid collections, both in estimating the size of the collections and in diagnosing small collections. MRI was also superior to CT in distinguishing chronic subdural hematomas from hygromas. Further, MRI was superior to CT in visualizing nonhemorrhagic contusion in 15 of 21 lesions. Because of the potential failure of MRI to diagnose acute subarachnoid or acute parenchymal hemorrhage, CT remains the procedure of choice in diagnosing head injury less than 72 hours old.

Adolescent↗
PubMed1986

Delayed intracerebral hemorrhage after ventriculoperitoneal shunting.

A rare complication of ventriculoperitoneal shunting is presented. In this case, a moderate-sized intracerebral hemorrhage (3 to 5 cm in maximal diameter) occurred 1 week after operation for idiopathic hydrocephalus in a 43-year-old woman. The patient recovered fully without operative intervention. No other case of delayed intracerebral hemorrhage after a ventricular shunting procedure was found in a review of the literature. The presumed mechanism in the present case is delayed erosion of a cerebral blood vessel by the ventricular catheter.

Adult↗
PubMed1986

Periventricular hyperintensity as seen by magnetic resonance: prevalence and significance.

Periventricular hyperintensity was identified using long repetition and echo times in spin-echo magnetic resonance imaging of patients with white-matter disease (e.g., multiple sclerosis) caused by local demyelination and in hydrocephalic patients caused by transependymal migration of spinal fluid. A review of 365 consecutives studies revealed that some degree of periventricular hyperintensity is present in most patients (93.5%) regardless of diagnosis. Mild periventricular hyperintensity was seen in patients with no other evidence of intracranial pathology. Periventricular hyperintensity is a normal finding that should not be considered indicative of either demyelinating disease or hydrocephalus. More extensive and severe periventricular hyperintensity is associated with intracerebral pathology, but the finding often is nonspecific. For example, mild periventricular edema from hydrocephalus is impossible to differentiate from the increased periventricular hyperintensity seen in patients with multiple white-matter lesions. Thus, the pattern of periventricular hyperintensity has proven to be of limited value in the clinical assessment of hydrocephalic patients.

Adolescent↗
PubMed1986

Focal recurrent hemorrhage on magnetic resonance at 0.5 tesla. An aid to the diagnosis of cryptic cerebral vascular malformations.

The MR appearance of focal recurrent hemorrhage is characteristic and highly suggestive of an underlying cryptic vascular malformation. We reviewed the MR findings in 14 cases (3 biopsy proven), 9 in the brainstem and 5 supratentorial. CT in all cases demonstrated the lesion to be hyperdense before contrast with minimal to moderate enhancement post contrast. The angiograms were negative in all 14 cases demonstrating mass effect in some but no blush or neovascularity. MR showed focal hyperintensities on both short (T1) and long (T2) TR sequences surrounded by a well-circumscribed hypointense rim particularly on the long TR sequence. Focal central hyperintensity is felt to be secondary to the presence of methemoglobin and indicates relatively recent hemorrhage. In our experience hyperintensity in a solitary hemorrhage usually resolves in 4-6 weeks. In 8 cases serial MR studies over 2-3 years demonstrated evidence of repeated hemorrhage as manifested by increases in size and persistent or new hyperintensity. The intense rim due to a short T2 did not correlate with vessels angiographically nor with calcification on the pre-contrast CT and, therefore, does not represent the vascular malformation itself but rather some portion of the hematoma, possibly the hemosiderin laden capsule. Using CT and angiography alone it is difficult to differentiate cryptic arteriovenous malformations from a neoplasm particularly in the brainstem. MR's specific configuration of focal recurrent hemorrhage can make a more definitive diagnosis at 0.5 T as well as at 1.5 T.

Adult↗
PubMed1986

Computed tomographic demonstration of cerebral edema in a child with galactosemia.

An eight-day-old male infant with galactosemia presented with signs of increased intracranial pressure and no evidence of intracranial infection or hemorrhage. Computed tomographic scans demonstrated the presence of diffuse cerebral edema. With treatment, the edema gradually resolved, although it persisted longer within the white matter and was associated with transient bilateral pyramidal tract signs.

Brain Edema↗
PubMed1985

Nuclear magnetic resonance imaging of skull base lesions.

The basic principles of nuclear magnetic resonance (NMR) are reviewed and the appearances of some lesions of the skull base are discussed. NMR is a valuable diagnostic study for skull base lesions and it provides information that is not shown on the CT scan. The modern investigation of unusual skull base lesions should include both CT and NMR.

Adolescent↗