Faculty Bibliography

Low field strength (0.12 Tesla resistive) and high field strength (1.0, 1.4, or 1.5 Tesla superconductive) magnetic resonance imagers were compared for their ability to detect central nervous system lesions. Sixteen adult patients with known lesions and three normal volunteers were studied. Contrast-enhanced computed tomography was used as the standard. The data demonstrate that imaging at high magnetic field strength is superior to low field strength imaging for the detection and delineation of lesions. This finding can be explained by the superior signal-to-noise ratio achievable at the higher magnetic field strengths. High field MR imaging was also found to outperform CT in demonstrating anatomic details and relationships. It is predicted that the use of low saturation (e.g., long TR spin echo technique) will make the gain in contrast-to-noise ratio even more significant

Six patients with pituitary abnormalities and three normal volunteers were evaluated by high field superconductive (1.0, 1.4, or 1.5 Tesla) magnetic resonance (MR) imaging, low field resistive (0.12 Tesla) MR imaging, and contrast-enhanced, high-resolution CT. Four macroadenomas, one microadenoma, and one empty sella were demonstrated. Their morphology and anatomic relationship to the visual pathway and the internal carotid and anterior cerebral arteries were best demonstrated by high field MR imaging. The low field resistive MR studies were least effective in showing the lesions

Gadolinium-DTPA, a paramagnetic contrast agent that distributes throughout the body in a manner similar to diatrizoate, was intravenously administered to a monkey with a hematogenously induced experimental intracranial abscess. Contrast enhanced computed tomography (CT) and gadolinium enhanced saturation-recovery nuclear magnetic resonance (NMR) were both performed immediately and repeated after a 30 min delay. The NMR images revealed marked ring enhancement at a time when CT showed a nodule. Both imaging modalities were analyzed with respect to the pathological specimen. Gadolinium-DTPA may be an effective agent for imaging alterations of the blood-brain barrier

Four dogs were immunized with a mixture of spinal cord homogenate and complete Freund's adjuvant. One of these dogs developed hyperacute allergic encephalomyelitis. Cranial computed tomography in this animal demonstrated a low absorption area in the internal capsule that corresponded to the pathologic lesion. Computed tomography scanning may be a useful tool in monitoring experimental allergic encephalomyelitis

Seven patients presented with neonatal arteriovenous malformation and vein of Galen aneurysms. Six had a large degree of vascular steal demonstrated by cerebral angiography and all had significant parenchymal loss on initial CT. Angiographically, the steal affected the ophthalmic artery and branches of the middle and anterior cerebral arteries. Repeat CT in two patients, one of whom was untreated for 7 months, revealed pronounced atrophy. Patients with neonatal vein of Galen aneurysms present with parenchymal loss on CT which is related to vascular steal and may be progressive

Sixty-nine patients with 91 separate abnormal findings were studied by both intra-arterial digital subtraction arteriography (ADSA) and conventional film screen subtraction arteriography (CFSA) in the same projection, with the same magnification. Digital subtraction arteriography has distinct advantages over CFSA in the form of reduced contrast utilization, better patient tolerance of arteriography because of reduced contrast concentration, superior contrast resolution, and rapid, on-line visualization of the abnormalities. Digital subtraction arteriography is limited by its availability in only a single plane, by decreased spatial resolution which affected the image quality for intracranial blood vessels at an image intensifier (I.I.) field of 12 inches, and by relatively limited field of view both intracranially and extracranially for I.I. fields of 6 and 9 inches

Over a 6-month period, 157 patients, 89 of whom had central nervous system tumors, were examined on a prototype 0.12 T resistive nuclear magnetic resonance (NMR) imaging unit. All of the patients had computed tomography (CT), which was used as a standard to which the NMR findings were compared. Studies were done primarily by saturation-recovery technique with short repetition times. The signal intensity with saturation-recovery technique did not allow differentiation among most tumor types. Location, extent, and morphology helped to some extent in attempts at differentiation. In the multiplanar mode, NMR compared favorably to CT with regard to lesion detection. Limited early experience suggests that NMR also may detect some lesions when the CT is negative and may detect additional lesions when one or more are present. The NMR examination was well tolerated by selected patients

The neuroradiologist and the clinician are partners in the search for pathology; the clinician must help the radiologist tailor the study by indicating where pathology is likely to be. The orbit, the sellar and parasellar regions, and new imaging modalities and interventional techniques are discussed in this light

In a study of the possible mechanisms of the clinical side effects of metrizamide, it was applied to several in vitro model preparations. It was shown that, although high metrizamide concentrations are without noticeable effect on many basic neuronal functions, metrizamide does interfere with cholinergic mechanisms. At concentrations equivalent to, or significantly lower than, those probably achieved during clinical procedures, metrizamide is both an inhibitor of the enzyme acetylcholinesterase and an antagonist of cholinergic transmission. These data suggest the possibility that some of the side effects resulting from clinical procedures employing metrizamide may be explained by its actions on cholinergic synapses