Applying wavelet-transform on Internet-based radiologic brain images.

Wavelet-transform compression creates high-quality images of small file size by tuning its compression ratio between 10:1 and 80:1. We applied the wavelet-based compression technique to radiologic brain images on the Internet for image display purposes. Wavelet transform compression reduces file size up to 50%. Wavelet transform compression offers the advantage of retaining complete color information in digital images and faster Internet transmission than traditional Joint Photography Experts Group (JPEG) files of equivalent file size. The application of wavelet-based compression technique decreases storage requirements for images on Internet servers.

The display of photographic-quality images on the Web: a comparison of two technologies.

Downloading medical images on the Web creates certain compromises. The tradeoff is between higher resolution and faster download times. As resolution increases, download times increase. High-resolution (photographic quality) electronic images can potentially play a key role in medical education and patient care. On the Internet, images are typically formatted as Graphics Interchange Format (GIF) or the Joint Photographic Experts Group (JPEG) files. However, these formats are associated with considerable data loss in both color depth and image resolution. Furthermore, these images are available in a single resolution and have no capability of allowing the user to adjust resolution as needed. Images in the photo compact disc (PCD) format have higher resolutions than GIF or JPEG, but suffer the disadvantage of large file sizes leading to long download times on the Web. Furthermore, native web browsers are not currently able to read PCD files. The FlashPix format (FPX) offers distinct advantages over the PCD, GIF, and JPEG formats for display of high-resolution images on the Web. A Java applet can be easily downloaded for viewing FPX images. FPX images are higher resolution than JPEG and GIF images. FPX images offer rich resolutions comparable to PCD images with shorter download times.

Normalization of transcranial Doppler middle cerebral artery velocities after aneurysm clipping.

BACKGROUND: Factors that promote normalization of middle cerebral artery (MCA) velocities after cerebral aneurysm surgery may be important to identify in order to optimize management. Survival analysis of serial transcranial Doppler (TCD) MCA velocities in the setting of aneurysm surgery offers an additional means of analyzing outcome. METHODS: We retrospectively studied serial MCA velocities obtained via TCD in 113 patients who underwent cerebral aneurysm clipping to analyze which factors promoted normalization. The presence of bleeding, aneurysm location, age, gender, ethnicity, initial blood pressure, hemoglobin, and clinical condition were examined. RESULTS: Patients who did not bleed but were clipped still tended to have transient periods of abnormally elevated velocities. Of those patients who bled and were clipped, older patients normalized faster. Women showed a trend toward slower normalization only in the subarachnoid hemorrhage (SAH) absent group. Other parameters listed above did not effect normalization time. CONCLUSIONS: Our data suggest aneurysm surgery in and of itself may promote transient rises in MCA velocities. Age appears to be a significant factor in predicting normalization of MCA velocities after SAH.

Acute stroke therapies.

It is likely that thrombolytic agents will play a role in the management of acute ischemic stroke in well-selected patients, intravenous administration is most practicable. However, intra-arterial administration via superselective catheterization is an alternative option that may offer advantages is certain settings (e.g., angiography suite, intraoperatively). Tissue plasminogen activators appear safer than streptokinase. Fibrinolytic agents offer the unproven potential for improving stroke outcome with less risk of intracranial bleeding. LMWHs can be administrated subcutaneously with minimal blood monitoring. These agents may prove more useful for secondary stroke prevention rather than acute treatment. Introduction of other agents like monoclonal antibodies directed against leukocyte adhesion molecules, aspirin, or ticlopidine offer other potential approaches to improving stroke outcome.

MCA flow asymmetry is a marker for cerebrovascular disease.

Utilizing the UIC Vascular Laboratory Registry, we retrospectively analysed the significance of side to side middle cerebral artery (MCA) flow velocity differences. Side to side differences > 15 percent measured by transcranial Doppler were considered asymmetric. Asymmetric subjects had 5 times greater chance of having significant cervical carotid narrowing on either side on Duplex Doppler and a 3.7 times greater chance of having a stroke on brain CT or MRI. MCA flow velocity asymmetry is a marker for underlying carotid disease and stroke.

Converting laserdisc video to digital video: a demonstration project using brain animations.

Interactive laserdiscs are of limited value in large group learning situations due to the expense of establishing multiple workstations. The authors implemented an alternative to laserdisc video by using indexed digital video combined with an expert system. High-quality video was captured from a laserdisc player and combined with waveform audio into an audio-video-interleave (AVI) file format in the Microsoft Video-for-Windows environment (Microsoft Corp., Seattle, WA). With the use of an expert system, a knowledge-based computer program provided random access to these indexed AVI files. The program can be played on any multimedia computer without the need for laserdiscs. This system offers a high level of interactive video without the overhead and cost of a laserdisc player.

The Mental Status Expert (MSE): an expert system for scoring and interpreting the mental status examination.

The mental status examination is the most difficult and time-consuming portion of the neurological examination. A complete mental status examination requires the examiner to assess alertness, memory, language, praxis, gnosis, attention, and visual-spatial functions. Findings of the mental status need to be interpreted in terms of severity of deficits, nature of the deficits, likely etiology, and likely area of corresponding brain injury. The performance of an accurate, complete, and detailed mental status examination is a daunting task for the medical student or resident in training. Traditional mental status examinations show considerable inter-examiner variability for items administered and for interpretation of abnormalities. Even in academic settings, mental status examinations have little educational content.