MR evaluation of epiglottic disruption.

Epiglottic disruption is an uncommon injury usually associated with significant supraglottic trauma. This injury may be overlooked because of the difficulty in examining the larynx or other associated severe injuries. We present two cases of clinically unsuspected epiglottic disruption that were first seen on MR images of the neck.

Optimizing three-dimensional time-of-flight MR angiography with variable repetition time.

PURPOSE: To implement and evaluate a variable repetition time (TR) modification of three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography. MATERIALS AND METHODS: Variable- and constant-TR 3D TOF MR angiography of the intracranial vasculature was performed in 20 healthy volunteers and 10 patients with known or suspected cerebrovascular disease. Total acquisition time was short and held constant for all studies. Frequency-selective fat saturation (FS) and magnetization transfer saturation (MTS) pulses were applied. The associated maximum-intensity projection (MIP) images were evaluated quantitatively for contrast-to-noise (C/N) and qualitatively for depiction of vessels that exhibit slow flow. RESULTS: Variable-TR MIP images exhibited improved C/N and depiction of small peripheral vessels and venous structures when compared with constant-TR MIP images. These observations were consistent for all studies. CONCLUSIONS: The variable-TR modification improved the depiction of intracranial vessels that exhibit slow flow.

The postoperative lumbar spine: imaging considerations.

MRI with intravenous contrast has recently become the imaging modality of choice in the evaluation of patients developing recurrent back pain or symptoms following laminectomy and/or discectomy. The normal postoperative appearance is important to recognize because a number of changes occur normally throughout the healing period. The difference between epidural scar and recurrent disc herniation can usually be determined on MRI. Postoperative fluid collections may also develop. Disc space infection, although uncommon, is a critical diagnosis, but can be confused with degenerative end plate changes. Arachnoiditis and spinal stenosis also show characteristic imaging findings.

Toxin production in Clostridium botulinum as demonstrated by electron microscopy.

Spheroplasts of Clostridium botulinum 62A were prepared with the use of lysozyme. These spheroplasts were then exposed to ferritin-labeled type A antitoxin. Ultrathin sections of these specimens revealed the ferritin-labeled antibody symmetrically arranged around the outer spore coats but not within the spore cortex. The ferritin-labeled antibody was also observed in the bacterial cytoplasm. Here it was arranged in aggregates and strands, although it was not associated with any identifiable cell structure. Controls included sections of C. botulinum spheroplasts treated with a 1.5% solution of ferritin as well as spheroplasts of C. roseum and Bacillus subtilis treated with conjugated type A antitoxin or a 1.5% solution of ferritin. No intracellular or extracellular ferritin was demonstrable in these specimens.