Brain ventricular wall movement assessed by a gated cine MR trueFISP sequence in patients treated with endoscopic third ventriculostomy.

The purpose of this study was to investigate the value of brain ventricular wall movement assessment with a gated cine trueFISP MR sequence for the diagnosis of endoscopic third ventriculostomy (ETV) patency. Sixteen healthy volunteers and ten consecutive patients with noncommunicating hydrocephalus were explored with a MR scanner (Siemens, Avanto 1.5 T) before, 1 week and 3 months after ETV. TrueFISP was evaluated qualitatively (ventricular wall movement and CSF flow through ETV) and quantitatively [distance moved (DMLT) during a cardiac cycle by the lamina terminalis]. The third ventricle volume (TVV) was assessed. Statistical analysis was performed using nonparametric tests. There was no motion of the lamina terminalis (LT) detected on preoperative data. A pulsatile motion of the LT was found for patients with a patent ETV and for controls. DMLT and TVV were correlated (r = 0.79, P = 0.006). A transient dysfunction of ETV was successfully diagnosed on the trueFISP sequence with no motion of the LT or CSF flow observed. The trueFISP sequence appears reliable for the diagnosis of ETV patency and provides non-invasive assessment of the movement of the ventricular wall related to CSF pressure changes.

Water diffusion compartmentation at high b values in ischemic human brain.

BACKGROUND AND PURPOSE: We studied the evolution of brain water compartments during the early stage of ischemic stroke. METHODS: Diffusion-weighted imaging was performed at 1.5 T in 10 volunteers and 14 patients with stroke. We used a single-shot echo-planar technique with 11 b values of 0-5000 s/mm(2). Regions of interest were selected in the white matter (WM) and striatum of the volunteers and in the ischemic core of the patients. Measurements were fitted on the basis of a biexponential decay with the b factor as follows: S(b) = S(0)[(f(slow) x exp(-b x ADC(slow)) + (f(fast) x exp(-b x ADC(fast))] where S(b) is the signal intensity in the presence of a diffusion gradient, S(0) is the signal intensity without diffusion sensitization, ADC(slow) and ADC(fast) are the respective apparent diffusion coefficients (ADCs) of slow diffusing compartments (SDCs) and fast diffusing compartments (FDCs), and f(slow) and f(fast) the respective contributions to the signal intensity of SDC and FDC. RESULTS: In healthy subjects, FDC represents 74.3 +/- 3.1% of brain water, with ADC(fast) = (124.6 +/- 12.0) x 10(-5) mm(2)/s and ADC(slow) = (15.5 +/- 3.9) x 10(-5) mm(2)/s. In stroke, decreased FDC (49.1% +/- 10.9%; P = 1.05 x10(-5)) and increased ADC(slow) ([22.4 +/- 8.1] x 10(-5) mm(2)/s; P = 8.07 x 10(-3)) were observed, but ADC(fast) was not significantly changed ([135.6 +/- 25.7] x 10 (-5) mm(2)/s; P =.151). CONCLUSION: The restricted diffusion observed in the early stroke is mainly related to a redistribution of water from the FDC to the SDC.