In vivo and in vitro MR imaging of renal tumors: histopathologic correlation and pulse sequence optimization

Magnetic resonance (MR) imaging has given mixed results in the detection of renal masses. To identify the reasons for this and to determine the optimal pulse sequences for evaluating renal tumors, the authors imaged 12 primary renal tumors in vivo and 17 in vitro at 0.35 T. Histopathologic findings for each specimen were closely correlated with the MR images. Four of seven solid tumors imaged in vivo were isointense with surrounding normal renal parenchyma at all pulse sequences. The other three tumors were hyperintense in vivo at T2-weighted sequences. At heavily T2-weighted sequences eight solid tumors were hyperintense in vitro and four were hypointense. There was no correlation between signal intensity and specific tissue type or histologic pattern for solid tumors. The five cystic tumors were well seen both in vivo and in vitro on T2-weighted images. However, the signal intensity of the cyst fluid was an unreliable indicator of benignancy. SE MR imaging at 0.35 T has significant limitations in the detection of solid renal masses.     

Nocardia choroidal abscess in a patient with systemic lupus erythematosus

Purpose: Nocardia asteroides, a respiratory saprophyte in humans, may cause localized infection of the lungs in debilitated or immunosuppressed individuals. Haematogenous spread to the eye via the choroidal circulation may result in choroidal abscess formation. Method: We report the development of a choroidal abscess in the left eye of a woman treated with steroids and cyclophosphamide for systemic lupus erythematosus. Haematogenous spread of N. asteroides from a localized infection of the lung (empyema) is thought to have been the cause of the choroidal abscess. Results: Surgical drainage of the empyema combined with intravenously administered antibiotics resulted in resolution of the choroidal abscess and improvement of vision. Conclusions: A choroidal abscess, caused by haematogenous spread of N. asteroides, may respond to appropriate systemic antibiotic treatment alone and not require ocular treatment.     

A simple method of monitoring licking responses that is compatible with electrophysiological recording

A simple technique is described for the monitoring of drinking behavior that is compatible with concurrent recording of electrophysiological events. The technique involves transduction of the movement of a water spout induced by tongue contact during licking, to an electrical signal via a coil and magnet. An example of this technique is provided with simultaneous recording of hippocampal EEG in a rat. The advantages of this technique include simplicity of construction, low cost, and insensitivity to most extraneous factors in addition to its compatibility with electrophysiological recording.