Stereotactic histologic correlations of computed tomography- and magnetic resonance imaging-defined abnormalities in patients with glial neoplasms.

In 39 patients who harbored previously untreated astrocytomas (21 patients), oligoastrocytomas (9 patients), or oligodendrogliomas (9 patients), computed tomographic (CT) and magnetic resonance imaging (MRI) findings were correlated with stereotactic serial biopsy findings. The 39 patients were classified as having one of three types of tumor: type I (1 patient), which consisted only of circumscribed tumor tissue; type II (26 patients), which consisted of tumor tissue and isolated tumor cells; or type III (11 patients), which consisted of intact parenchyma infiltrated by isolated tumor cells. (In one patient, the biopsy sampling was inadequate for determining the type of tumor.) In high-grade lesions, tumor tissue was obtained from CT contrast-enhancing regions, and the area of enhancement accurately defined the tumor tissue volume. In low-grade lesions, tumor tissue was hypodense and indistinguishable from parenchyma infiltrated by isolated tumor cells on both CT and MRI. Isolated tumor cells usually extended as far as the prolongation of T2 on T2-weighted MRI of high-grade and low-grade tumors. CT and MRI detection of boundaries and stereotactic serial biopsies are necessary for the demarcation of glial neoplasms into tumor tissue and isolated tumor cell volumes as well as for the determination of the spatial extent of each component. This information is important for determining appropriate treatment.

Digital angiography: introducing digital techniques to clinical cerebral angiography practice.

Digital subtraction angiography provides a computerized radiographic method of imaging the vascular system. These computer techniques may be used with arterial catheterization (digital arterial angiography) and with intravenous contrast injection (digital venous angiography). Both methods are changing the diagnostic evaluation and therapeutic follow-up of patients with cerebrovascular disease.

Magnetic resonance imaging in a routine clinical setting.

The results of magnetic resonance imaging (MRI) examinations in the first 1,000 consecutive patients who were studied by this technique at our institution were reviewed to determine the disease states encountered, the sensitivity and accuracy of results, and the value of the examination as compared with computed tomography and other imaging procedures. The MRI device was a 0.15-tesla resistive magnet that used a variety of saturation recovery, spin echo, and inversion recovery pulse sequences to produce images. MRI was found equal to or superior to other imaging techniques in most cases. Exceptions included organs or body regions that are prone to excessive respiratory or vascular motion, lesions that necessitate exquisite spatial resolution for diagnosis, and lesions in which angulation of the viewing plane is necessary for optimal depiction. Fresh blood and calcification within a lesion were also difficult to detect with use of MRI.

The accuracy and limitations of intravenous digital subtraction angiography in the evaluation of atherosclerotic cerebrovascular disease: angiographic and surgical correlation.

Intravenous digital subtraction angiography (IV-DSA) and subsequent conventional selective carotid angiographic examinations were reviewed in 78 patients who were suspected of having cerebrovascular disease, and the results were correlated with surgical findings in 53 patients. The impact of the information provided by each of these examinations on subsequent therapy was reviewed. IV-DSA examinations of acceptable quality accurately depict atherosclerotic lesions in the cervical carotid arteries. We found IV-DSA to be deficient for detection of intracranial vascular disease.

Radiation exposure from conventional and digital subtraction angiography of cerebral vessels.

Patients with atherosclerotic cerebrovascular disease were studied to determine the radiation exposure associated with conventional and digital subtraction angiography of the cerebral vessels. The median exposure-area product was 3198 R cm2 (range, 616-5665 R cm2) in the conventional angiography group and 1831 R cm2 (range, 366-4198 R cm2) in the IV digital subtraction angiography (DSA) group. This difference in exposure resulted from increased use of fluoroscopy in the conventional screen-film angiography group. The actual difference in exposure between the radiographic and digital imaging portions of the examinations was much smaller. The contributions of fluoroscopy to the radiation exposure in conventional angiography and IV-DSA in this study were 37% (range, 8.8-76%) and 6% (range, 1.5-25%), respectively.

Computed tomography-based stereotactic third ventriculostomy: technical note.

This report describes a computed tomography-based computer-assisted stereotactic technique for performing 3rd ventriculostomy. The procedure has been performed on seven patients with acquired obstructive hydrocephalus of various etiologies. None of these patients have yet required shunting.

Imaging-based stereotaxic serial biopsies in untreated intracranial glial neoplasms.

Forty patients with previously untreated intracranial glial neoplasms underwent stereotaxic serial biopsies assisted by computerized tomography (CT) and magnetic resonance imaging (MRI). Tumor volumes defined by computer reconstruction of contrast enhancement and low-attenuation boundaries on CT and T1 and T2 prolongation on MRI revealed that tumor volumes defined by T2-weighted MRI scans were larger than those defined by low-attenuation or contrast enhancement on CT scans. Histological analysis of 195 biopsy specimens obtained from various locations within the volumes defined by CT and MRI revealed that: contrast enhancement most often corresponded to tumor tissue without intervening parenchyma; hypodensity corresponded to parenchyma infiltrated by isolated tumor cells or in some instances to tumor tissue in low-grade gliomas or to simple edema; and isolated tumor cell infiltration extended at least as far as T2 prolongation on magnetic resonance images. This information may be useful in planning surgical procedures and radiation therapy in patients with intracranial glial neoplasms.

Adult cerebellar medulloblastomas: the pathological, radiographic, and clinical disease spectrum.

The records of 34 patients over 16 years of age with cerebellar medulloblastoma were retrospectively reviewed. All patients were treated by surgery, and all surviving patients were given radiation therapy. The imaging characteristics of this rare entity were evaluated with regard to the tumor location in the cerebellum, and the prognostic effects of histological characteristics such as neuronal or glial differentiation and the presence of desmoplasia were investigated. Neither histological parameters nor tumor location (median, paramedian, or lateral cerebellar) affected patient survival. The desmoplastic variant was encountered in 38% of these adult medulloblastomas and occurred in all three cerebellar locations. The degree of surgical resection did not have a major effect on long-term survival; long-term survival was possible even in patients who had received only a biopsy. The extent of initial radiation therapy was positively correlated with recurrence-free survival; full neuraxis irradiation was associated with a 13% incidence of delayed spinal metastases, whereas 75% of patients treated with irradiation of only the posterior fossa and/or the whole brain developed spinal deposits. A similar local recurrence rate (12.5%) was noted in both irradiation groups. Chemotherapy resulted in palliation in some patients with metastatic disease.

Endodermal sinus tumor (yolk sac tumor) of the ear.

Endodermal sinus tumors (yolk sac tumors) are malignant germ cell tumors that usually arise in the gonads. We report what is, to our knowledge, the first known case of an endodermal sinus tumor of the ear. The tumor was present in a developmentally delayed child with an abnormal temporal bone and exhibited histopathologic and immunocytochemical features identical to those of endodermal sinus tumors of gonadal origin. The tumor resolved after chemotherapy, and the patient remained alive without evidence of disease at the time of this writing. The purpose of this report is to add a rare tumor to the differential diagnosis of neoplasms of the ear in children and to familiarize otorhinolaryngologists and head and neck surgeons with its pathologic features and clinical management.

Magnetic resonance imaging vs. computed tomography: advantages and disadvantages.

Magnetic resonance imaging (MRI) of the head and spine exceeds the sensitivity of computed tomography (CT) in detecting parenchymal lesions of the brain and spinal cord. MRI should be employed as a screening examination, particularly in patients suspected of having demyelinating diseases. CT continues to be the imaging technique of choice in evaluation of trauma, accurately depicting bony abnormalities and intracranial hemorrhage in evaluation of the spinal column and suspected disc herniation and in uncooperative patients.

Measurement of large or irregular-shaped septal perforations by computed tomography.

When a custom-made prosthesis is used to close a large (greater than 3 cm) or irregular-shaped septal perforation, the size and shape are important factors that determine how well the prosthesis fits. Computed tomography with reformatted images helps determine the size and shape of these perforations.

Complications of spinal cord arteriography: prospective assessment of risk for diagnostic procedures.

A prospective study was done of complications associated with 134 consecutive diagnostic spinal cord arteriograms in 96 patients (63 men and 33 women aged 17-78 years). Patients were examined for either arteriovenous malformation (n = 88) or tumor (n = 8), as indicated by myelography. Among the complications, 11 (8.2%) were local, five (3.7%) were systemic nonneurologic, and three (2.2%) were neurologic (two were associated with full recovery in less than 24 hours, and one was associated with full recovery in less than 1 week). No specific clinical or technical factors were significantly associated with the development of neurologic complications. Details of the clinical profile, angiographic technique, and pathologic findings for each patient were recorded and analyzed with respect to the potential risk for arteriographic complications. Diagnostic spinal cord arteriography had an acceptable risk within the range of other neuroangiographic diagnostic procedures.

Cryptic structural lesions in refractory partial epilepsy: MR imaging and CT studies.

Results of contrast material-enhanced computed tomography (CT) and T2-weighted spin-echo magnetic resonance (MR) imaging were correlated with pathologic findings in 25 patients treated surgically for refractory partial epilepsy. Of 12 lesions present, ten (83%) were detected by MR imaging and seven (58%) by CT scanning. Of nine low-grade gliomas, eight were detected by MR imaging and four by CT scanning. One posttraumatic scar and one case of temporal lobe atrophy were better demonstrated by MR imaging. A small, thrombosed arteriovenous malformation was the only lesion detected by CT scanning but not by MR imaging. No lesions were detected in 13 patients with mild gliosis and one patient with a 1.2-cm grade 1 astrocytoma. Although more sensitive than CT for detection of structural lesions in patients with refractory partial epilepsy, MR imaging resulted in a 25% false-negative diagnostic rate when a repetition time of 2,000 msec and echo time of 60 msec were used. Multi-echo imaging with at least one long echo time may be needed to increase the sensitivity of MR imaging in these patients.