Advances in Condition Monitoring of Railway Infrastructure.

In recent years, there has been a notable surge in investments directed towards developing new railway lines and revitalising existing ones, reflecting a global commitment to enhance transportation infrastructure [...].

Zero TE MRI applications to transcranial MR-guided focused ultrasound: Patient screening and treatment efficiency estimation.

BACKGROUND: The high acoustic impedance of the skull limits the performance of transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) therapy. Subject suitability screening is based on skull parameters estimated from computed tomography (CT) scans. PURPOSE: To assess the feasibility of screening for tcMRgFUS based on zero echo time (ZTE) MRI, and to explore the influence of measurable skull parameters in treatment performance. STUDY TYPE: Retrospective. POPULATION: Sixteen patients treated with tcMRgFUS thalamotomy for tremor. SEQUENCE: ZTE on a 3.0T GE scanner. ASSESSMENT: Baseline CT and ZTE images were processed to extract skull measures associated with treatment success: skull density ratio (SDR), skull thickness, and angle of incidence. Eight new metrics were proposed. CT and ZTE-based measures were compared. Each subject's energy-temperature curve was processed to extract a global estimate of efficiency and a measure of nonlinearity. These parameters were then correlated with the skull measures. STATISTICAL TESTS: Linear regression analysis to compare ZTE vs. CT-based measures, measures vs. efficiency, and measures vs. nonlinearity. Paired t-test to assess nonlinearity. RESULTS: CT and ZTE-based measures were significantly correlated (P < 0.01). In particular, classical metrics were robustly replicated (P < 0.001). The energy-temperature curves showed a nonlinear (logarithmic) relationship (P < 0.01). This nonlinearity was greater for thicker skulls (P < 0.01). Efficiency was correlated with skull thickness (P < 0.001) and SDR (P < 0.05). DATA CONCLUSION: The feasibility of ZTE-based screening has been proven, potentially making it possible to avoid ionizing radiation and the extra imaging session required for CT. The characterization of the influence that skull properties have on tcMRgFUS may serve to develop patient-specific heating models, potentially improving control over the treatment outcome. The relationship of skull thickness with efficiency and nonlinearity empowers the role of this metric in the definition of such models. In addition, the lower association of SDR with the energy-temperature curves emphasizes the need of revisiting this metric. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1583-1592.

Cystic meningiomas: Radiological and pathological correlation with surgical implications. / Meningiomas quísticos: correlación radiológica y patológica con implicaciones quirúrgicas.

INTRODUCTION: Meningiomas associating prominent cystic changes (CM) have challenged neurosurgeons since the beginning of this surgical discipline. We present the experience in the diagnostic and therapeutic management of this entity in our institution. MATERIAL AND METHODS: A review of our patient database was carried out, searching for those CM that were operated on in the last 15 years. Relevant clinical data were recorded and analyzed for each case, with special emphasis in the correlation of radiological and pathological findings. Cystic changes were classified according to the scheme proposed by Nauta et al. RESULTS: A total of 11 patients were gathered, which represents 1.8% of the meningiomas operated on in our department during the period studied. All were adults, predominantly female patients (8 cases). Among the clinical symptoms a high rate of epileptic seizures was observed while only one patient developed acute intracranial hypertension. Morphologically, most tumors corresponded to type 2 CMs, followed by types 1, 3 and 4. In only five patients an unequivocal radiological diagnosis of meningioma could be made. All neoplasms were surgically removed and there were no records of recurrence (mean follow-up: 52.8 months). Microscopic findings were consistent with the pathological diagnosis of atypical meningioma in 4 cases, while the remaining tumors corresponded to OMS grade I neoplasms with variable microscopic patterns. CONCLUSIONS: Meningiomas can exceptionally associate cystic changes, both intra and/or extratumoral, in variable number and size. When cystic changes become too prominent (a large number or big-sized cysts), a serious preoperative diagnostic dilemma may arise. The surgical management of those CMs displaying a peripheral, thin-walled cyst (types 2 and 3) is especially complex, as contrast enhancement of the tumor wall did not correlate strictly with neoplastic invasion; even in the absence of this feature free floating islands of meningothelial cells intermixed with cyst fluid can be found. Consequently both surgical biopsy of every suspicious tissue and copious irrigation of the surgical cavity are strongly recommended for these CM types.