Colliculus hemorrhage

We report the case of a patient with mesencephalic hematoma involving only the quadrigeminal plate. One case of superior and 3 cases of inferior colliculus hematoma have already been reported. Involvement of the quadrigeminal plate frequently follows a pontine or an anterior mesencephalic hemorrhage. The cause of these hematomas may be due to cryptic malformations of the quadrigeminal plate or primitive small size hemorrhages possibly related to the nature of the arterial system. Patients with inferior colliculus lesions present a typical symptomatology consisting of trochlear nerve palsy contralateral to the lesion or bilateral, contralateral hemiparesthesiae and acuphenes. Superior colliculus lesion causes upgaze palsy, visual blurring, dizziness and left upper lip paresthesiae. The cause of the different signs and symptoms in both types of lesion are discussed.     

Quantum entanglement and the Bell matrix

We present a class of maximally entangled states generated by a high-dimensional generalisation of the cnot gate. The advantage of our constructive approach is the simple algebraic structure of both entangling operator and resulting entangled states. In order to show that the method can be applied to any dimension, we introduce new sufficient conditions for global and maximal entanglement with respect to Meyer and Wallach’s measure.     

Impact of the inversion time on regional brain perfusion estimation with clinical arterial spin labeling protocols

Objective

Evaluating the impact of the Inversion Time (TI) on regional perfusion estimation in a pediatric cohort using Arterial Spin Labeling (ASL).

Materials and methods

Pulsed ASL (PASL) was acquired at 3 T both at TI 1500 ms and 2020 ms from twelve MRI-negative patients (age range 9–17 years). A volume of interest (VOIs) and a voxel-wise approach were employed to evaluate subject-specific TI-dependent Cerebral Blood Flow (CBF) differences, and grey matter CBF Z-score differences. A visual evaluation was also performed.

Results

CBF was higher for TI 1500 ms in the proximal territories of the arteries (PTAs) (e.g. insular cortex and basal ganglia — P < 0.01 and P < 0.05 from the VOI analysis, respectively), and for TI 2020 ms in the distal territories of the arteries (DTAs), including the watershed areas (e.g. posterior parietal and occipital cortex — P < 0.001 and P < 0.01 from the VOI analysis, respectively). Similar differences were also evident when analyzing patient-specific CBF Z-scores and at a visual inspection.

Conclusions

TI influences ASL perfusion estimates with a region-dependent effect. The presence of intraluminal arterial signal in PTAs and the longer arterial transit time in the DTAs (including watershed areas) may account for the TI-dependent differences. Watershed areas exhibiting a lower perfusion signal at short TIs (~ 1500 ms) should not be misinterpreted as focal hypoperfused areas.