Preliminary observations on magnetic resonance imaging in refractory epilepsy.

We are studying the use of magnetic resonance (MR) imaging in localization of epileptogenic foci in patients with medically refractory partial epilepsy. Imaging is performed using a prototype resistive unit operating at 0.15 T. All studies include 7 mm axial sections obtained with a partial saturation sequence (TR = 200 msec) in which signals are recovered with a spin echo (TE = 11 msec) and images reconstructed using a modified 2D Fourier transform technique. Since the temporal lobe and limbic system are the commonest site of seizure foci in this group of patients, examinations were performed with the plane of section parallel to the temporal horns of the lateral ventricles. Consensus interpretations by a radiologist, neurologist and neurosurgeon have recognized findings considered possibly abnormal in six of 11 epilepsy patients and none of six normal volunteers. These preliminary results indicate that further study is warranted in this group of patients. Critical evaluation of such findings must be carried out in a larger group including normals and patients with a variety of neurologic disorders.

Partial anomalous pulmonary venous drainage of the left upper lobe vs duplication of the superior vena cava: distinction based on CT findings.

OBJECTIVE: Partial anomalous pulmonary venous drainage of the left upper lobe and duplication of the superior vena cava have similar appearances on CT scans. The purpose of this study was to review their appearances and provide guidelines for differentiating between them. MATERIALS AND METHODS: A review of the CT reports for the preceding 4 years disclosed seven patients whose original diagnosis was duplication of the superior vena cava and one patient whose diagnosis was partial anomalous pulmonary venous drainage of the left upper lobe. The 14 CT examinations of these eight patients were reviewed in order to observe the CT findings in each anomaly. RESULTS: In only five of the seven patients whose original diagnosis was duplication of the superior vena cava were CT findings compatible with that diagnosis. In the other two, CT findings were compatible with partial anomalous pulmonary venous drainage of the left upper lobe, as they were in the one patient with that as his original diagnosis. Two CT findings allow consistent differentiation. In duplication of the superior vena cava, two vessels can be seen anterior to the left main bronchus, whereas no vessels are present in this location in partial anomalous pulmonary venous drainage of the left upper lobe. Additionally, careful inspection reveals that the intraparenchymal veins in the left upper lobe drain to the normally positioned left superior pulmonary vein in duplication of the superior vena cava, whereas they drain to the anomalous vessel in partial anomalous pulmonary venous drainage of the left upper lobe. CONCLUSION: Careful analysis of the CT scans with particular attention to these two features allows differentiation between partial anomalous pulmonary venous drainage of the left upper lobe and duplication of the superior vena cava.

Venous clots: evaluation with MR imaging.

In vitro and in vivo studies were performed to determine the proton relaxation and imaging characteristics of static blood and acute and organized clot in canine jugular veins. In vivo, it was found that two inversion recovery sequences using a short inversion time (100 msec) demonstrated better differentiation of signal intensity of intravascular clot from surrounding soft tissues than did standard T1- and T2-weighted sequences. In vitro, quantitative measurements showed marked reduction of both T1 and T2 relaxation time of acute clot compared with stagnant blood. In addition, the T1 relaxation time, and to a lesser extent the T2 relaxation time, shortened as the clot aged, indicating a potential role for magnetic resonance imaging in determining the age of venous thrombi.