Safe Helicopter Landing on Unprepared Terrain Using Onboard Interferometric Radar.

This letter proposes a radar interferometric survey system for the ground surface of helicopter landing sites. This system generates high-quality three-dimensional terrain surface topography data and estimates the slope of the site with the required accuracy. This study presents the processing algorithms of the radar system for safe helicopter landing using an interferometric method and also demonstrates the efficiency of the proposed approach based on computer simulation results.

MRI of intracranial subependymomas.

Objective: We report imaging features of two cases of subependymoma, a relatively rare benign intraventricular neoplasm.

Materials And Methods: The first case was a lateral ventricular tumor, which grew to a large size before becoming symptomatic. The second case was a fourth ventricular subependymoma with extensive cisternal spread.

The value of MR in differentiating subligamentous from supraligamentous lumbar disk herniations.

Purpose: To determine the value of MR criteria in differentiating subligamentous from supraligamentous lumbar disk herniations.

Methods: A retrospective review of surgical reports and MR images of 50 patients undergoing first-time lumbar surgery was performed. Three MR imaging criteria were assessed: the presence and integrity of a low-signal-intensity line posterior to the disk herniation, the size of the disk herniation in comparison with the size of the spinal canal, and the presence of disk fragments.

Computed tomography in pulmonary tuberous sclerosis.

Pulmonary disease is a rare manifestation of tuberous sclerosis. Respiratory symptoms often progress to severe pulmonary insufficiency and death may ensue within a few years of diagnosis. We describe a case where a computerized tomographic scan aided early diagnosis in a patient with spontaneous pneumothorax and subtle, nonspecific changes on a plain x-ray film.