BackgroundThe Phase coordination index (PCI), a temporal gait measure that quantifies consistency and accuracy in generating the anti-phased left-right stepping pattern, assesses bilateral coordination of gait in various cohorts (e.g., Parkinson's disease, post stroke). As PCI is based on mean values calculated across a series of gait cycles, individuals are required to perform lengthy walking trials, prolonging gait assessments which cause discomfort to some of them. This study introduces an algorithm to identify the required number of strides to obtain a reliable, characteristic PCI value.MethodsSimulated data sets, as well as physiological data (obtained from healthy elderly and young persons, from over ground and treadmill trials) were used in this research. A series of N-1 PCI values was calculated for i = 2,3,4…N gait cycles for each participant. There is a value i = k, representing certain number of cycles, for which no significant change in PCI occurs as additional cycles are added, termed point of stabilization (POS). The algorithm presented here uses a 2-stage iterative process to determine POS. Stage 1 searches for the gross location of the interval of PCI values containing the POS. In stage 2, the algorithm performs a high-resolution recursive, iterative process within this interval to find the exact point. The criterion for defining stability within a window of PCI values is a coefficient of variation (CV) of ≤ 5%.ResultsOur recursive, iterative algorithm indicates that ~23 strides on average should be captured to attain a characteristic PCI.ConclusionsGait trials with at least 23 strides on average should suffice to obtain a reliable estimation of PCI in healthy young adults. While this methodology may be considered generic, future studies should obtain POS values based on additional cohorts (e.g., disabled participants, fixed walking speeds).

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Background Accurate and swift tissue diagnosis is extremely important for the timely initiation of treatment in pediatric oncology. In our department, ultrasound‐guided core needle biopsy (US‐guided CNB) is used for tissue diagnosis. In 2016, we added on‐site cytology, allowing for an immediate primary diagnosis. We retrospectively reviewed our performance in terms of safety and accuracy for CNBs and on‐site cytology. Methods All pediatric biopsies performed in our hospital between February 2016 and December 2020, were included. Patient clinical, procedural and follow‐up data were collected. CNB pathology and cytology results were compared to the final pathologic diagnosis. Results We included 71 patients for which 72 biopsies with on‐site touch imprint (TI) cytology were performed; the average latency time to biopsy was 1 day. Altogether, we had 61 tumors, (58 malignant, 3 benign) and 11 other lesions. On‐site cytology diagnosed 58 malignant tumors, 3 benign tumors and 11 non‐tumor tissues. The cytologist correctly differentiated tumor from inflammation in all cases, and diagnosed the precise tumor type in 57 cases, with an accuracy of 94% for final diagnosis. We had no complications related to the procedure or sedation. Conclusion US‐guided CNB with on‐site TI cytology for suspected malignancy in the pediatric population is highly available, safe, and accurate, with real‐time diagnosis in most cases. This accelerated diagnostic route has a huge impact on patient care.

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