Resection control in brain tumor surgery can be achieved in real time with intraoperative MRI (iMRI). Arterial spin labeling (ASL), a technique that measures cerebral blood flow (CBF) non-invasively without the use of intravenous contrast agents, can be performed intraoperatively, providing morpho-physiological information. This study aimed to evaluate the feasibility, image quality and potential to depict residual tumor of a pseudo-continuous ASL (PCASL) sequence at 3 T. Seventeen patients with brain tumors, primary (16) or metastatic (1), undergoing resection surgery with iMRI monitoring, were prospectively recruited (nine men, age 56 ± 16.6 years). A PCASL sequence with long labeling duration (3000 ms) and postlabeling delay (2000 ms) was added to the conventional protocol, which consisted of pre- and postcontrast 3D T1 -weighted (T1w) images, optional 3D-FLAIR, and diffusion. Three observers independently assessed the image quality (four-point scale) of PCASL-derived CBF maps. In those with diagnostic quality (Scores 2-4) they evaluated the presence of residual tumor using the conventional sequences first, and the CBF maps afterwards (three-point scale). Inter-observer agreement for image quality and the presence of residual tumor was assessed using Fleiss kappa statistics. The intraoperative CBF ratio of the surgical margins (i.e., perilesional CBF values normalized to contralateral gray matter CBF) was compared with preoperative CBF ratio within the tumor (Wilcoxon's test). Diagnostic ASL image quality was observed in 94.1% of patients (interobserver Fleiss ¿ = 0.76). PCASL showed additional foci suggestive of high-grade residual component in three patients, and a hyperperfused area extending outside the enhancing component in one patient. Interobserver agreement was almost perfect in the evaluation of residual tumor with the conventional sequences (Fleiss ¿ = 0.92) and substantial for PCASL (Fleiss ¿ = 0.80). No significant differences were found between pre and intraoperative CBF ratios (p = 0.578) in patients with residual tumor (n = 7). iMRI-PCASL perfusion is feasible at 3 T and is useful for the intraoperative assessment of residual tumor, providing in some cases additional information to the conventional sequences.

Background Unilateral magnetic resonance-guided focused ultrasound (FUS) thalamotomy is efficacious for the treatment of medically refractory essential tremor (ET). Viability of bilateral FUS ablation is unexplored. Methods Patients diagnosed with medically refractory ET and previously treated with unilateral FUS thalamotomy at least 5 months before underwent bilateral treatment. The timepoints were baseline (before first thalamotomy) and FUS1 and FUS2 (4 weeks before and 6 months after second thalamotomy, respectively). The primary endpoint was safety. Efficacy was assessed through the Clinical Rating Scale for Tremor (CRST), which includes subscales for tremor examination (part A), task performance (part B) and tremor-related disability (part C). Results Nine patients were treated. No permanent adverse events were registered. Six patients presented mild gait instability and one dysarthria, all resolving within the first few weeks. Three patients reported perioral hypoesthesia, resolving in one case. Total CRST score improved by 71% from baseline to FUS2 (from 52.3 +/- 12 to 15.5 +/- 9.4, p<0.001), conveying a 67% reduction in bilateral upper limb A+B (from 32.3 +/- 7.8 to 10.8 +/- 7.3, p=0.001). Part C decreased by 81% (from 16.4 +/- 3.6 to 3.1 +/- 2.9, p<0.001). Reduction in head and voice tremor was 66% (from 1.2 +/- 0.44 to 0.4 +/- 0.54, p=0.01) and 45% (from 1.8 +/- 1.1 to 1 +/- 0.8, p=0.02), respectively. Conclusion Bilateral staged FUS thalamotomy for ET is feasible and might be safe and effective. Voice and head tremor might also improve. A controlled study is warranted.

Background During magnetic resonance-guided focused ultrasound for essential or parkinsonian tremor, adverse events (headache, nausea/vomiting, or anxiety) may alter the outcome of the procedure despite being mostly transient and mild. Objectives Our aim was to analyze the relationship between demographic, procedural, and anesthetic characteristics with magnetic resonance/ultrasound-related events. Methods This was a retrospective study at the Clinica Universidad de Navarra of patients undergoing thalamotomy with magnetic resonance-guided focused ultrasound between September 2018 and October 2019. The anesthesia protocol included headache and nausea/vomiting prophylaxis and rescue therapy. Dexmedetomidine was used for anxiolysis in some patients after thorough multidisciplinary assessment. Results A total of 123 patients were included. Headache was directly related to skull density ratio (P < 0.001) and skull thickness (P = 0.02). Patients with a skull density ratio less than 0.48 had 3 times the odds of experiencing moderate or severe headache (odds ratio [OR], 3.08; 95% confidence interval [CI], 1.21-7.82) and had a higher odds of aborting sonication due to pain. Sex was associated with increased nausea (P = 0.007). Women had 4 times the odds of nausea than men (OR, 4.4; 95% CI, 1.61-12.11). Dexmedetomidine did not reduce headache or nausea incidence. Patients who received dexmedetomidine had a higher number (P = 0.01) and total minutes of sonication (P = 0.01). Conclusions Patients with lower skull density ratios and higher skull thicknesses could benefit from an aggressive analgesic prophylaxis. Women are more likely to experience nausea. Dexmedetomidine did not reduce headache and nausea, but increased the number and duration of sonications. Its exact effect on tremor is still unclear.