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Background and Purpose: Cervical spinal canal stenosis (cSCS) is a common cause of spinal impairment in the elderly. With conventional magnetic resonance imaging (MRI) suffering from various limitations, high‐resolution single‐shot T1 mapping has been proposed as a novel MRI technique in cSCS diagnosis. In this study, we investigated the effect of conservative and surgical treatment on spinal cord T1 relaxation times in cSCS. Methods: T1‐mapping was performed in 54 patients with cSCS at 3 Tesla MRI at the maximum‐, above and below the stenosis. Subsequently, intraindividual T1‐differences (ΔT1) intrastenosis were calculated. Twenty‐four patients received follow‐up scans after 6 months. Results: Surgically treated patients showed higher ΔT1 at baseline (154.9 ± 81.6 vs. 95.3 ± 60.7), while absolute T1‐values within the stenosis were comparable between groups (863.7 ± 89.3 milliseconds vs. 855.1 ± 62.2 milliseconds). In surgically treated patients, ΔT1 decreased inverse to stenosis severity. After 6 months, ΔT1 significantly decreased in the surgical group (154.9 ± 81.6 milliseconds to 85.7 ± 108.9 milliseconds, p =.021) and remained unchanged in conservatively treated patients. Both groups showed clinical improvement at the 6‐month follow‐up. Conclusions: Baseline difference of T1 relaxation time (ΔT1) might serve as a supporting marker for treatment decision and change of T1 relaxation time might reflect relief of spinal cord narrowing indicating regenerative processes. Quantitative T1‐mapping represents a promising additional imaging method to indicate a surgical treatment plan and to validate treatment success. [ABSTRACT FROM AUTHOR]

Although bilateral fimbria-fornix (FF) lesioning impairs spatial performance in animals, the literature is equivocal regarding its effects on hippocampal long-term potentiation (LTP). We examined the effects of FF lesioning on LTP induction in the Schaffer collateral-CA1 pathway in vivo with a protocol that delivered theta burst stimulation (TBS) trains of increasing length until a sufficient length was reached to induce LTP of the monosynaptic field excitatory postsynaptic potential (fEPSP). Experiments were performed in urethan-anesthetized Long-Evans rats either 4 or 12-16 wk after lesioning. In sham-operated controls, TBS trains ranging from 4 to 12 bursts were sufficient to induce robust LTP [170 +/- 10% (mean +/- SF) of control fEPSP slope; n = 8]. Four-week post -FF-lesioned animals also displayed clear LTP (167 +/- 12% of control fEPSP slope; n = 4) that did not differ from the shams (P > 0.05). In contrast, animals in the 12- to 16-wk post-lesion group showed a highly significant deficit in LTP induction (95 +/- 3% of control fEPSP slope; n = 8; < or =28 burst TBS trains tested; P < 0.001 vs. sham- and 4-wk post-FF-lesion groups). Other quantitative measures of synaptic excitability (i.e., baseline fEPSP slope and input-output relation) did not differ between the sham- and the 12- to 16-wk post-FF-lesion groups. These results indicate that the FF lesion leads to an enduring defect in hippocampal long-term synaptic plasticity that may relate mechanistically to the cognitive deficits characterized in this model. [ABSTRACT FROM AUTHOR]

We have observed thermal gating, i.e. electrostatic gating induced by hot electrons. The effect occurs in a device consisting of two capacitively coupled quantum dots. The double dot system is coupled to a hot electron reservoir on one side (QD1), while the conductance of the second dot (QD2) is monitored. When a bias across QD2 is applied we observe a current which is strongly dependent on the temperature of the heat reservoir. This current can be either enhanced or suppressed, depending on the relative energetic alignment of the QD levels. Thus, the system can be used to control a charge current by hot electrons. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) tracking allows localization of small EM sensors in a magnetic field of known geometry without line-of-sight. However, this technique requires a cable connection to the tracked object. A wireless alternative based on magnetic fields, referred to as transponder tracking, has been proposed by several authors. Although most of the transponder tracking systems are still in an early stage of development and not ready for clinical use yet, Varian Medical Systems Inc. (Palo Alto, California, USA) presented the Calypso system for tumor tracking in radiation therapy which includes transponder technology. But it has not been used for computer-assisted interventions (CAI) in general or been assessed for accuracy in a standardized manner, so far. In this study, we apply a standardized assessment protocol presented by Hummel et al (2005 Med. Phys.32 2371–9) to the Calypso system for the first time. The results show that transponder tracking with the Calypso system provides a precision and accuracy below 1 mm in ideal clinical environments, which is comparable with other EM tracking systems. Similar to other systems the tracking accuracy was affected by metallic distortion, which led to errors of up to 3.2 mm. The potential of the wireless transponder tracking technology for use in many future CAI applications can be regarded as extremely high. [ABSTRACT FROM AUTHOR]