Extended phase graphs with anisotropic diffusion.

The extended phase graph (EPG) calculus gives an elegant pictorial description of magnetization response in multi-pulse MR sequences. The use of the EPG calculus enables a high computational efficiency for the quantitation of echo intensities even for complex sequences with multiple refocusing pulses with arbitrary flip angles. In this work, the EPG concept dealing with RF pulses with arbitrary flip angles and phases is extended to account for anisotropic diffusion in the presence of arbitrary varying gradients. The diffusion effect can be expressed by specific diffusion weightings of individual magnetization pathways. This can be represented as an action of a linear operator on the magnetization state. The algorithm allows easy integration of diffusion anisotropy effects. The formalism is validated on known examples from literature and used to calculate the effective diffusion weighting in multi-echo sequences with arbitrary refocusing flip angles.

Bilateral internal carotid artery dissection mimicking inflammatory demyelinating disease.

BACKGROUND AND PURPOSE: Internal carotid artery (ICA) dissection (ICAD) may be extremely difficult to diagnose only on the basis of historical information and clinical signs, and even standard brain imaging (computed tomography [CT], T2-weighted magnetic resonance imaging [MRI]) may not be sufficient to delineate the underlying pathology clearly, as shown in this case. METHODS: The clinical presentation and parenchymal lesion pattern on CT were suggestive of inflammatory demyelinating disease, and additional multiparametric MRI was performed. RESULTS: Diffusion-weighted MRI, magnetic resonance angiography, and perfusion-weighted MRI revealed acute ischemic lesions, bilateral ICA obstruction, and bilateral hypoperfusion in the middle cerebral artery territories. Bilateral ICAD was confirmed by Doppler and duplex ultrasound, and anticoagulation therapy was initiated. A follow-up examination showed recanalization of the obstructed ICAs and the normalization of cerebral perfusion. CONCLUSION: This case illustrates the importance of demonstrating the pathology and the value of multiparametric MRI techniques for the diagnosis and monitoring of ICAD and its hemodynamic consequences.

[Significance of toxic metabolites of the fungus Trichothecium roseum Link ex Fr. for viticulture]. / Untersuchungen zur Bedeutung toxischer Stoffwechselprodukte des Pilzes Trichothecium roseum Link ex Fr. für den Weinbau.

The plant-pathogen fungus Trichothecium roseum produces in vitro as well as in vivo the toxic metabolites trichothecin, trichothecolone and rosenonolactone. Trichothecin is cytotoxic and inhibits the alcoholic fermentation. It is not metabolized by yeast during the alcoholic fermentation. All toxins showed a minor biological activity against microorganisms other than yeast. Trichothecin caused a bitter taste in wine at higher toxin concentrations (greater than 5 mg/l). Trichothecin was detected in a few samples of wine of higher quality.