Comparison of Readout-Segmented Echo-Planar Imaging and Single-Shot TSE DWI for Cholesteatoma Diagnostics.

BACKGROUND AND PURPOSE: The high diagnostic value of DWI for cholesteatoma diagnostics is undisputed. This study compares the diagnostic value of readout-segmented echo-planar DWI and single-shot TSE DWI for cholesteatoma diagnostics. MATERIALS AND METHODS: Thirty patients with newly suspected cholesteatoma were examined with a dedicated protocol, including readout-segmented echo-planar DWI and single-shot TSE DWI at 1.5T. Acquisition parameters of both diffusion-weighted sequences were as follows: b=1000 s/mm,2 axial and coronal section orientations, and section thickness of 3 mm. Image quality was evaluated by 2 readers on a 5-point Likert scale with respect to lesion conspicuity, the presence of susceptibility artifacts mimicking cholesteatomas, and overall subjective image quality. Sensitivity and specificity were calculated using histology results as the gold standard. RESULTS: Twenty-five cases of histologically confirmed cholesteatomas were included in the study group. Lesion conspicuity was higher and fewer artifacts were found when using TSE DWI (both P < .001). The overall subjective image quality, however, was better with readout-segmented DWI. For TSE DWI, the sensitivity for readers 1 and 2 was 92% (95% CI, 74%-99%) and 88% (95% CI, 69%-97%), respectively, while the specificity for both readers was 80% (95% CI, 28%-99%). For readout-segmented DWI, the sensitivity for readers 1 and 2 was 76% (95% CI, 55%-91%) and 68% (95% CI, 46%-85%), while the specificity for both readers was 60% (95% CI, 15%-95%). CONCLUSIONS: The use of TSE DWI is advisable for cholesteatoma diagnostics and preferable over readout-segmented DWI.

Intracranial self-stimulation site specificity: the myth of current spread.

Locus-specificity of intracranial self-stimulation (ICSS) was determined for 78 electrode placements using monophasic stimulation. ICSS rate comparisons between each pole of a bipolar electrode when each served as cathode were made when the anodal source was either the other pole of the bipolar electrode or a skull screw. In hypothalamic areas, medial forebrain bundle electrode tips elicited significantly higher rates than electrode tips of the same bipolar electrodes located in perifornical or far-lateral diencephalic placements. In turn, perifornical electrode tips elicited higher rates than more dorsally or medially placed tips. In dorsal pontine areas, locus coeruleus electrode tips elicited significantly higher rates than more medially or laterally placed tips. In periaqueductal midbrain and substantia nigra placements, tips located along the midline or in the substantia nigra elicited significantly higher rates than tips located lateral to or ventral to those respective structures. Anodal locus did not change these results. These results suggest that ICSS behavior is delimited by and corresponds to neuroanatomically discrete entities and that cathodal, rather than anodal factors seem to most crucially determine ICSS integrity.