[First intraoperative magnetic resonance imaging in a Spanish hospital of the public healthcare system: initial experience, feasibility and difficulties in our environment]. / Implantación de la primera resonancia magnética intraoperatoria en un hospital de la red sanitaria pública española: experiencia inicial, viabilidad y dificultades en nuestro entorno.

OBJECTIVE: Intraoperative MRI is considered the gold standard among all intraoperative imaging technologies currently available. Its main indication is in the intraoperative detection of residual disease during tumour resections. We present our initial experience with the first intraoperative low-field MRI in a Spanish hospital of the public healthcare system. We evaluate its usefulness and accuracy to detect residual tumours and compare its intraoperative results with images obtained postoperatively using conventional high-field devices. MATERIAL AND METHODS: We retrospectively reviewed the first 21 patients operated on the aid of this technology. Maximal safe resection was the surgical goal in all cases. Surgeries were performed using conventional instrumentation and the required assistance in each case. RESULTS: The mean number of intraoperative studies was 2.3 per procedure (range: 2 to 4). Intraoperative studies proved that the surgical goal had been achieved in 15 patients (71.4%), and detected residual tumour in 6 cases (28.5%). After comparing the last intraoperative image and the postoperative study, 2 cases (9.5%) were considered as "false negatives". CONCLUSIONS: Intraoperative MRI is a safe, reliable and useful tool for guided resection of brain tumours. Low-field devices provide images of sufficient quality at a lower cost; therefore their universalisation seems feasible.

Direct observation of human microcirculation during decompressive craniectomy after stroke.

OBJECTIVES: Most knowledge related to the pathophysiology of microcirculation in ischemic stroke comes from experimental research. Unfortunately, data on microcirculation in the human brain are limited, partially as a result of the lack of appropriate investigational techniques. The objective of our study was to test the hypothesis that cortical microcirculatory alterations in the brain, in terms of blood flow and vessel density, occur in patients with stroke who require surgical decompression compared with a control group. DESIGN: Prospective and observational study. SETTING: Third-level university hospital. PATIENTS: Six patients who had undergone decompressive surgery as a result of a space-occupying hemispheric infarction. These patients were compared with five patients who had undergone craniotomy for a disease not affecting the cortex. INTERVENTIONS: Cortical microcirculation in the brain was directly observed using sidestream dark-field imaging. All images were analyzed offline. MEASUREMENTS AND MAIN RESULTS: In patients with stroke with a space-occupying hemispheric infarction, 18 good-quality movie images were compared with 25 control group images. In the control group, cortical vessels showed a continuous flow in small, medium, and large vessels compared with patients with stroke who presented intermittent or no flow in all vessels. The proportion of perfused vessels was near 100% in control subjects and 63.44% in patients with stroke. The perfused vessel density index was also higher in control subjects (6.16 1/mm; interquartile range, 5.65-7.56) than in patients with stroke (2.77 1/mm; interquartile range, 1.75-3.86). CONCLUSION: Sidestream dark-field imaging allowed direct visualization of cerebral microcirculatory alterations in the operating room. This technique allowed the documentation of a significant blood flow reduction in the cortical microvascular and a decreased vascular density in patients with stroke compared with control subjects.

Direct observation during surgery shows preservation of cerebral microcirculation in patients with traumatic brain injury.

OBJECTIVE: To describe the alterations of the cortical microcirculation of the brain (blood flow and vessel density) in TBI patients who and compare them with a control group. METHODS: Prospective and observational study in a third-level university hospital. Cortical microcirculation in the brain was directly observed using sidestream dark-field (SDF) imaging in 14 patients who underwent surgery: 5 subdural hematomas (SDH) and 9 parenchymal lesions (contusions/hematomas). In this last set of patients, images were recorded in the "pericontusional" areas and in the "surrounding" brain (areas that were as far from the lesion as the craniotomy allowed). These patients were compared to five patients who underwent craniotomy for a disease that did not affect the cortex. RESULTS: There were fewer "pericontusional" images that could be analyzed due to the presence of subarachnoid hemorrhage. The proportion or perfused vessels was similar in all groups: control 99.5% ± 1.3%; SDH 98.6% ± 2.4%; "pericontusional" area 98.2% ± 2.4%; "surrounding" area 98.4% ± 2.5% (p = 0.145). The perfused vessel density index was smaller in the "pericontusional" area: control 6.5 ± 1.6 l/mm; SDH 6.5 ± 2.5 l/mm; "pericontusional" area 5.4 ± 2.6 l/mm; "surrounding" 6.6 ± 2.1 l/mm (p = 0.07). CONCLUSIONS: Although the analysis of pericontusional zone was difficult, there were fewer vessels than in the controls and there was no change in the flow. In the surrounding zone and in patients with SDH, we did not document alterations in the microcirculation. Direct imaging of cerebral microcirculation in TBI patients showed that despite serious brain injury the cerebral microcirculation was remarkably well preserved.

[Study of a brain microcirculation in cranioencephalic trauma using the Side Stream Field (SDF) system]. / Estudio de la microcirculación cerebral en el traumatismo craneoencefálico mediante el sistema Side Stream Dark Field (SDF).

Posttraumatic tissular hypoxia can be due to multiple causes, including microcirculation disturbances, which can be studied with the SDF (Side Stream Dark Field) system. This system is based on a small hand-held microscope that eliminates directly reflected green polarised light from an organ surface using an orthogonal analyser. It offers clear images of red and white blood cells flow through microcirculation. Specific software is later used to determine the length and density of microvessels. We present a case of a TBI patient who required surgical evacuation of a brain contusion. Images of the microcirculatory bed were recorded with the SDF microscope and compared with a normal pattern obtained from another patient who was operated on for an unruptured cerebral aneurysm. Both imaging and quantitative analyses showed significant differences in the cerebral microcirculatory status in these patients. Total length and density of vessels were markedly reduced in the TBI patient. SDF imaging allows direct and non-invasive in vivo observation of cerebral microcirculation, and may allow us to deepen our knowledge of the pathophysiology of posttraumatic brain ischemia.