Use of magnetic resonance imaging in psychiatry.

The authors report four cases in which magnetic resonance imaging (MRI) provided diagnostic information not apparent by X-ray CAT in clinical investigations of patients with neuropsychiatric disorders. The relative capabilities and contraindications for MRI and CAT are reviewed. The authors suggest that MRI is indicated 1) instead of CAT when there is suspicion of neuropathology that is better visualized by MRI because of its type or location and 2) after CAT when an atypical psychiatric symptom or presentation has not been definitively evaluated by means of CAT.

Computerized axial tomography: clinicopathologic correlation.

Between August 1973 and April 1974 more than 750 patients had computerized axial tomography (CT) scans at the Massachusetts General Hospital. Ten brains from previously CT-scanned patients in this group were sectioned in the plane of the scan. Nearly exact correlation was found between the anatomic location and extent of intracranial lesions demonstrated by CT scan and the findings on gross and microscopic pathologic examination in cases of primary intracranial tumors, obstructive hydrocephalus, intracerebral hemorrhage, ischemic and hemorrhagic infarctions, pineal tumor, and thermal-burn encephalopathy. Determination of absorption values (mu) of 47 pathologically verified processes showed that high-absorption intracerebral hemorrhage and calcium-containing tumors are readily separable from other processes on the basis of mu values alone. However, the abnormal mu values of primary brain tumor, edema, and infarction are difficult to distinguish from those of normal spinal fluid and white matter.

Nuclear magnetic resonance imaging in central nervous system disease.

From the preliminary work of many investigators, it appears that proton nuclear magnetic resonance (NMR) imaging will have wide application in the diagnostic assessment (and potential management) of patients with vascular, neoplastic, and demyelinating diseases of the central nervous system (CNS). Findings in isolated cases and small series suggest that NMR imaging may play a role in the evaluation of patients with other CNS conditions including hydrocephalus, malformations, infections, developmental and metabolic disorders, and degenerative processes. Because of the dynamic nature of disease processes involving the CNS, the precise meaning of NMR image parameters (rho, T1, and T2) remains unclear. A comprehensive study correlating NMR images in neurologic disease with precise neuropathologic examination is required. In the future, with accurate quantitative measurements of these NMR parameters, in vivo imaging may provide insight into the dynamic nature of neurologic disease.

Orbital fracture evaluation by coronal computed tomography.

Coronal computed tomography produces orbital scans in a plane that is analogous to Caldwell-view x-ray films. Coronal computed tomography permits simultaneous visualization of the orbital walls and the orbital soft tissues, including all extraocular muscles. Using coronal computed tomography, we studied a series of patients with radiographically proven orbital floor fractures. We studied in detail three of these patients, one with a linear orbital floor fracture, one with a depressed orbital floor fracture, and one with a severely comminuted orbital floor. In two patients, coronal computed tomography showed inferior rectus muscle entrapment, which was confirmed at the time of surgery. In each patient, some bone fragments could be seen more discreetly on coronal computed tomography than on conventional polytomes. Coronal computed tomography may be used to help confirm extraocular muscle entrapment in patients with orbital floor fractures. Coronal computed tomography can also be used to examine patients with possible intraorbital foreign bodies, unexplained reduction of vision, or severely displaced bone fragments.

Intraventricular noncolloid neuroepithelial cysts.

Symptomatic intraventricular developmental cysts of neuroepithelial origin occurring in the lateral and fourth ventricles are extremely rare. We report the clinical, radiologic, and computed tomographic (CT) findings in three such cases, two occurring in the lateral ventricles and one in the fourth ventricle. Within lateral ventricles, these cysts are distinguished from colloid cysts by their large size, more posterior locations, and CSF-equivalent CT attenuation of their contents. Lack of contrast enhancement on CT and angiographic avascularity are also features. Fenestration in two cases and partial cyst excision in the third case relieved the predominant symptoms. The symptomatology and theories of histogenesis are reviewed and the differential diagnosis discussed.

Malignant meningiomas: CT and histologic criteria, including a new CT sign.

Histologic features that could be correlated with malignancy were assessed by reviewing the microscopic slides of 167 meningiomas. Six tumors had shown two or more recurrences. In three having three or more recurrences, the number of mitoses counted under high power was higher than in those meningiomas showing clinically benign behavior. The radiologic and histologic features of seven meningiomas showing malignant clinical behavior and/or malignant histologic features were also evaluated and correlated. On computed tomography (CT), most of the malignant meningiomas were moderately hyperdense before contrast enhancement, but showed no or minimal calcification. Marked perifocal edema was common. Indistinct tumor margins or, occasionally, deeply extending fringes of tumor interdigitating with brain substance, marked bone destruction, or prominent pannus or tumor, extending well away from the globoid mass, termed "mushrooming," is described for the first time and seems to be the most useful correlate of histologic or clinical malignancy. This sign occurred in five of the seven cases and was absent in about 250 benign meningiomas reviewed. It was visible only at surgery in one additional case.

MR imaging of pituitary adenomas using a prototype resistive magnet: preliminary assessment.

Magnetic resonance (MR) images were obtained with a prototype resistive magnet system in 10 patients, all of whom had been shown to have pituitary tumors by enhanced high-resolution computed tomography (CT). Histologic verification was obtained in eight cases. Inversion-recovery (IR) T1-weighted images revealed the tumor in six of nine cases; saturation-recovery (SR) images with less T1 weighting identified seven of nine tumors; Carr-Purcell-Meiboom-Gill (CPMG) spin-echo T2-weighted images revealed two of four tumors. MR images failed to demonstrate three microadenomas: 5 X 5 X 8 mm, 6 X 6 X 6 mm, and one less than 5 mm in estimated size. In the last pretreatment study, CT had demonstrated a 13 mm maximum diameter adenoma. Repeat CT at the time of MR imaging also showed a partially empty sella and did not resolve the residual adenoma. The larger adenomas were identified readily by MR imaging, which, unlike CT, suggested old tumor hemorrhage in two cases, which was confirmed at surgery and histologic examination. MR and CT images were also compared for relative effectiveness in identifying important perisellar structures.

The detection of intracranial calcifications by MR.

Twenty patients in whom CT had unequivocally demonstrated the presence of calcification in a diversity of lesions and who had undergone MR, performed at 0.6 T and with standard T1- and T2-weighted pulse sequences, were retrospectively studied to determine the MR signal-intensity characteristics of the calcifications and to assess the ability of MR to detect the presence of this abnormality. CT proved superior to MR in detecting and characterizing calcification. In seven of 20 cases, the apparent extent of calcification was equal by both imaging techniques, and in 13 of the 20 cases, CT showed more extensive abnormality. In five of the 20 cases, the calcifications were seen by MR as regions of profoundly reduced signal intensity, approximately equal to cortical bone, in all pulse sequences. In 12 of the 20 cases, the signal intensity was profoundly reduced in one or more, but not all, pulse sequences. T2-weighted pulse sequences were most sensitive in detecting calcification of signal void. Reviewed without knowledge of the CT findings, the MR images were interpreted as definitely indicative of the presence of calcification in three of the 20 cases. In seven of the 20 cases, the MR images raised the possibility of calcification but were less definitive than the CT findings. In 10 of the 20 cases, MR was judged indeterminate for the presence of calcification.

Preliminary clinical results of proton (1H) imaging of cranial neoplasms: in vivo measurements of T1 and mobile proton density.

Proton nuclear magnetic resonance (NMR) images reflecting T1 relaxation time and approximating proton density were acquired and used to generate T1 rate (1/T1) maps. By region-of-interest selection, measurements of T1 relaxation time were made from discrete volumes of the imaging plane. Such techniques were applied to the study of human cranial neoplasia and associated conditions of differential diagnostic importance (e.g., postoperative changes, radiation necrosis). Inversion-recovery NMR images exhibit a high lesion-detection sensitivity. In all patients, the specificity of NMR imaging is low since all abnormal areas appear as lesions darker than surrounding normal brain, reflecting a decreased proton density, prolonged T1 values, or both. T1 relaxation times are prolonged within neoplastic foci; however, absolute T1 values overlap with those found in other lesions.

Interdural cyst of the lumbosacral region.

The purpose of this report is to call attention to the clinical, myelographic, and computed tomographic appearance of a very rare type of dural cyst within the lumbosacral spinal canal. We report this condition in three unrelated boys who presented with symptoms of cauda equina compression. Our experience suggests that these cysts are congenital in origin. Anatomically, the cyst wall consisted of a dura-like layer without arachnoid. There was a small ventral defect allowing incomplete communication with the compressed subarachnoid space. Cerebrospinal fluid-like fluid accumulated within the interdural cyst as a result of this communication. Treatment consisted of obliteration of the point of entry between cyst and subarachnoid space in all cases and partial cyst wall excision in one case. After operation, the two patients who had presented with long-standing sphincter disturbance had partial improvement in function and the child with a pain syndrome was completely relieved of symptoms.

Angiographically occult arteriovenous malformations.

Eight cases of histopathologically proven arteriovenous malformations (AVM's) which were not visualized on angiography are presented. As is typical with these lesions, most of the patients in this series presented with hemorrhage, seizures, or episodic or progressive neurological symptoms suggestive of a neoplasm. The diagnosis of angiographically occult AVM was highly suspected preoperatively in each case based on the combination of computerized tomography (CT) and magnetic resonance (MR) findings. The CT scans in all cases showed moderately hyperdense lesions which enhanced mildly or moderately in a nonhomogeneous pattern with administration of contrast material. The MR image showed one or more bright areas interspersed with areas of low or absent signal peripherally or centrally on both T1- and T2-weighted images. The AVM was totally excised in seven patients and partially excised in one patient, with favorable results in all. The clinical management and differential diagnosis of angiographically occult AVM's are discussed. In patients with a clinical course and radiological studies suggestive of an occult AVM, removal of the lesion, if accessible, should be performed in order to rule out a neoplasm and prevent subsequent hemorrhage and progression of symptoms.

Spontaneous spinal subarachnoid hemorrhage and subdural hematoma. Report of two cases.

Two patients with spontaneous spinal subarachnoid hemorrhage are presented to emphasize the clinical and radiological features of this uncommon illness. Both had severe back pain at the onset. One patient had a subdural hematoma that compressed the conus medullaris and cauda equina, and was drained percutaneously; the other had clots in the subarachnoid space. The cerebrospinal fluid showed a polymorphonuclear pleocytosis that simulated septic meningitis. Complete spinal angiography failed to reveal a cause for the hemorrhages.

1H Nuclear magnetic resonance imaging in multiple sclerosis.

Major advances have been made in the diagnosis of MS by using NMR imaging, suggesting that this noninvasive method will permit staging of MS lesions and that conclusions from newer therapeutic trials may be drawn more accurately than heretofore possible.

Computed tomography in extra-dural epidermoid and xanthoma.

Two cases of extradural epidermoid cyst and one case of xanthoma are reported in order to describe the computed tomographic and other radiographic findings. Contrast enhancement of the margin was seen in all of the cases. Absorption values almost as low as those found with cerebrospinal fluid were present in the central region of the lesions.

CSF enhancement for computerized tomography.

Metrizamide cisternography, combined with hypocycloidal tomography, has been performed in 12 patients with possible posterior fossa or parasellar mass lesions with finely detailed images of the basal cisterns resulting. Computed tomography was performed in nine of these patients and produced exceptional images of the cisternal anatomy. The technique of cerebrospinal fluid enhancement may be efficacious in identifying small basal masses not shown with conventional computed tomography, and thus may form an important complement to enhancement by intravenous injection of contrast medium.