O. Petter Eldevik

Acoustic droplet vaporization for therapeutic and diagnostic applications

A phase shift droplet emulsion is introduced as an aid to unusual ultrasound (US) applications. The transpulmonary droplet emulsion (90% < 6 microm diameter) is made by mixing saline, bovine albumin and dodecafluoropentane. It has been observed that an acoustic pressure threshold exists, above which the droplets vaporize into bubbles approximately 25 times the original diameter. For frequencies between 1.5 and 8 MHz, the threshold decreases from 4.5 to 0.75 MPa peak rarefactional pressure. This paper presents preliminary results for droplet preparation and their evaporation as a function of applied acoustic pressure and frequency, as well as simulations of the lifetime of these gas bubbles based on gas diffusion. In vivo experiments were simulated by the evaporation of droplets in blood flowing under attenuating material. We propose that this agent might be useful for tissue occlusion in cancer treatment, as well as for phase aberration corrections in acoustic imaging.

Pentobarbital vs chloral hydrate for sedation of children undergoing MRI: efficacy and recovery characteristics.

Background : Chloral hydrate (CH) sedation for magnetic resonance imaging (MRI) is associated with significant failure rates, adverse events and delayed recovery. Pentobarbital (PB), reportedly produces successful sedation in 98% of children undergoing diagnostic imaging. This study compared the efficacy, adverse events and recovery characteristics of CH vs PB in children undergoing MRI.

Motor neuron disease due to neuropathy target esterase gene mutation: clinical features of the index families.

Recently, we reported that mutations in the neuropathy target esterase (NTE) gene cause autosomal recessive motor neuron disease (NTE‐MND). We describe clinical, neurophysiologic, and neuroimaging features of affected subjects in the index families. NTE‐MND subjects exhibited progressive lower extremity spastic weakness that began in childhood and was later associated with atrophy of distal leg and intrinsic hand muscles. NTE‐MND resembles Troyer syndrome, except that short stature, cognitive impairment, and dysmorphic features, which often accompany Troyer syndrome, are not features of NTE‐MND. Early onset, symmetry, and slow progression distinguish NTE‐MND from typical amyotrophic lateral sclerosis. NTE is implicated in organophosphorus compound–induced delayed neurotoxicity (OPIDN). NTE‐MND patients have upper and lower motor neuron deficits that are similar to OPIDN. Motor neuron degeneration in subjects with NTE mutations supports the role of NTE and its biochemical cascade in the molecular pathogenesis of OPIDN and possibly other degenerative neurologic disorders. Muscle Nerve, 2011

Magnetic resonance imaging of normal mengingeal enhancement at 1.5T

Rationale and Objectives. We examined patterns of intracranial meningeal enhancement on gadolinium chelate contrast media—enhanced 1.5-T spin-echo magnetic resonance (MR) imaging and developed criteria that might be useful for distinguishing between normal and abnormal meningeal enhancement. Methods. The convexity, falx cerebri, tentorium cerebelli, and suprasellar cistern regions of 204 patients were prospectively evaluated for contrast enhancement with a grading system ranging from 0 (no enhancement) to 5 (diffuse, irregular, thickened enhancement). Meningeal findings were correlated with other MR abnormalities and pertinent clinical histories that have been associated previously with meningeal enhancement. Results. Short-segment convexity meningeal enhancement was commonly seen and most likely represents intravascular contrast material in normal meningeal vessels. Such enhancement did not correlate with the presence of other MR abnormalities. Long-segment (> 3 cm) or diffuse convexity meningeal enhancement did correlate with other significant MR abnormalities and pertinent clinical history. Fine linear falcine and tentorial meningeal enhancement, as an isolated finding, did not correlate with other MR or clinical abnormalities. The suprasellar cistern and ventricular walls were rarely enhanced. Conclusion. Short-segment convexity meningeal contrast enhancement is a normal finding representing normal vascular structures. More extensive convexity meningeal enhancement is abnormal and should prompt careful examination of the remainder of an MR image as well as the patients clinical history for an etiology of the enhancement.

Cranial Nerve Clock

Abstract Rationale and Objectives The authors performed this study to compare a declarative memory paradigm developed to help teach medical students about the cranial nerves with a traditional text-based approach. Materials and Methods The authors designed a clock-based paradigm to help medical students learn about the cranial nerves. To enhance memorization and related brain activation, the paradigm uses visual, spatial, and word associations in the context of an analog clock face. Twenty-one undergraduate students were randomly divided into two groups. Group T viewed traditional text slides, and group C viewed text slides followed by the corresponding cranial clock slides. Subjects were tested before and after these sessions. Results Group C performed significantly better than group T in learning the names of the cranial nerves and their correct order ( P P = .005), V ( P = .04), and X ( P = .03). Conclusion Alternative teaching strategies may help improve declarative memory.

Cranial nerve clock: Part II: Functional MR imaging of brain activation during a declarative memory task

RATIONALE AND OBJECTIVES The authors performed this study to assess brain activation during encoding and successful recall with a declarative memory paradigm that has previously been demonstrated to be effective for teaching students about the cranial nerves. MATERIALS AND METHODS Twenty-four students underwent functional magnetic resonance (MR) imaging during encoding and recall of the name, number, and function of the 12 cranial nerves. The students viewed mnemonic graphic and text slides related to individual nerves, as well as their respective control slides. For the recall paradigm, students were prompted with the numbers 1-12 (test condition) intermixed with the number 14 (control condition). Subjects were tested about their knowledge of cranial nerves outside the MR unit before and after functional MR imaging. RESULTS Students learned about the cranial nerves while undergoing functional MR imaging (mean post- vs preparadigm score, 8.1 +/- 3.4 [of a possible 12] vs 0.75 +/- 0.94, bilateral prefrontal cortex, left greater than right; P < 2.0 x 10(-12)) and maintained this knowledge at I week. The encoding and recall paradigms elicited distributed networks of brain activation. Encoding revealed statistically significant activation in the bilateral prefrontal cortex, left greater than right [corrected]; bilateral occipital and parietal associative cortices, parahippocampus region, fusiform gyri, and cerebellum. Successful recall activated the left much more than the right prefrontal, parietal associative, and anterior cingulate cortices; bilateral precuneus and cerebellum; and right more than the left posterior cingulate. CONCLUSION A predictable pattern of brain activation at functional MR imaging accompanies the encoding and successful recall of the cranial nerves with this declarative memory paradigm.

A simple and effective postangiographic femoral artery pressure dressing

We describe a simple, inexpensive pressure dressing which supplements manual pressure and may be applied quickly and easily following femoral arterial puncture for angiography. This technique has been used on several thousand patients without complications.

Fusiform Aneurysmal Dilatation of Pericallosal Artery

Two cases of lipoma of the corpus callosum with aneurysmal dilatation of the pericallosal artery are reported. This appears to be a reliable sign of lipoma of the corpus callosum. Our cases and the literature reveal that 19 of 22 cases with illustrations of carotid angiography have demonstrated such an aneurysmal dilatation.