BackgroundPhase-contrast magnetic resonance imaging (PC-MRI) enables quantification of cerebrospinal fluid (CSF) flow and total cerebral blood (tCBF) flow and may be of value for the etiological diagnosis of neurodegenerative diseases. This investigation aimed to study CSF flow and intracerebral vascular flow in patients with Alzheimer's disease (AD) and patients with amnesic mild cognitive impairment (a-MCI) and to compare the results with patients with idiopathic normal pressure hydrocephalus (NPH) and with healthy elderly volunteers (HEV).MethodsTen a-MCI and 9 mild AD patients were identified in a comprehensive neurological and neuropsychological assessment. They underwent brain MRI; PC-MRI pulse sequence was performed with the following parameters: two views per segment; flip angle: 25° for vascular flow and 20° for CSF flow; field-of-view (FOV): 14 × 14 mm²; matrix: 256 × 128; slice thickness: 5 mm; with one excitation for exams on the 3 T machine, and 2 excitations for the 1.5 T machine exams. Velocity (encoding) sensitization was set to 80 cm/s for the vessels at the cervical level, 10 or 20 cm/s for the aqueduct and 5 cm/s for the cervical subarachnoid space (SAS). Dynamic flow images were analyzed with in-house processing software. The patients' results were compared with those obtained for HEVs (n = 12), and for NPH patients (n = 13), using multivariate analysis.ResultsArterial tCBF and the calculated pulsatility index were significantly greater in a-MCI patients than in HEVs. In contrast, vascular parameters were lower in NPH patients. Cervical CSF flow analysis yielded similar values for all four populations. Aqueductal CSF stroke volumes (in μl per cardiac cycle) were similar in HEVs (34 ± 17) and AD patients (39 ± 18). In contrast, the aqueductal CSF was hyperdynamic in a-MCI patients (73 ± 33) and even more so in NPH patients (167 ± 89).ConclusionOur preliminary data show that a-MCI patients present with high systolic arterial peak flows, which are associated with higher mean total cerebral arterial flows. Aqueductal CSF oscillations are within normal range in AD and higher than normal in NPH. This study provides an original dynamic vision of cerebral neurodegenerative diseases, consistent with the vascular theory for AD, and supporting primary flow disturbances different from those observed in NPH.

OBJECT Stereotactic biopsy procedures are an everyday part of neurosurgery. The procedure provides an accurate histological diagnosis with the least possible morbidity. Robotic stereotactic biopsy needs to be an accurate, safe, frameless, and rapid technique. This article reports the clinical results of a series of 100 frameless robotic biopsies using a Medtech ROSA device. METHODS The authors retrospectively analyzed their first 100 frameless stereotactic biopsies performed with the robotic ROSA device: 84 biopsies were performed by frameless robotic surface registration, 7 were performed by robotic bone fiducial marker registration, and 9 were performed by scalp fiducial marker registration. Intraoperative flat-panel CT scanning was performed concomitantly in 25 cases. The operative details of the robotic biopsies, the diagnostic yield, and mortality and morbidity data observed in this series are reported. RESULTS A histological diagnosis was established in 97 patients. No deaths or permanent morbidity related to surgery were observed. Six patients experienced transient neurological worsening. Six cases of bleeding within the lesion or along the biopsy trajectory were observed on postoperative CT scans but were associated with transient clinical symptoms in only 2 cases. Stereotactic surgery was performed with patients in the supine position in 93 cases and in the prone position in 7 cases. The use of fiducial markers was reserved for posterior fossa biopsy via a transcerebellar approach, via an occipital approach, or for pediatric biopsy. CONCLUSIONS ROSA frameless stereotactic biopsies appear to be accurate and safe robotized frameless procedures.

Objective: To establish the impact of the imaging modality, registration method and use of intraoperative computed tomography (CT) scan on the accuracy of the ROSA® stereotactic robot. Methods: Using a dedicated phantom device, we measured the accuracy of the stereotactic robot for 20 targets as a function of the registration method (frameless, FL, or frame-based, FB) and the reference imaging modality (3T magnetic resonance imaging, MRI, CT scanner or flat-panel CT, fpCT). We performed a retrospective study of the accuracy of the first 26 FB and 31 FL robotized stereotactic surgeries performed in our department. Results: In a phantom study, the mean target accuracy was 1.59 mm for 3T MRI-guided FL surgery, 0.3 mm for fpCT-guided FL surgery and 0.3 mm for CT-guided FB surgery. In our retrospective series, the mean accuracy was 0.81 mm for FB stereotactic surgery, 1.22 mm for our 24 stereotactic surgery procedures with FL (surface recognition) registration and 0.7 mm for our 7 stereotactic surgery procedures with FL fiducial marker registration. Intraoperative fpCT fully corrected all the registration errors. Conclusions: The ROSA stereotactic robot is highly accurate. Robotized FB stereotactic surgery is more accurate than robotized FL stereotactic surgery.

BACKGROUND AND PURPOSE:Patients with aqueductal stenosis (AS) present with various clinical and radiologic features. Conventional MR imaging provides useful information in AS but depends on a subjective evaluation by the neuroradiologist. The purpose of this study was to evaluate the support of the phase-contrast MR imaging (PC-MR imaging) technique (sensitive to CSF flows) for the diagnosis of AS.

No abstract