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MRI is the gold standard for confirming a pelvic lymph node metastasis diagnosis. Traditionally, medical radiologists have analyzed MRI image features of regional lymph nodes to make diagnostic decisions based on their subjective experience; this diagnosis lacks objectivity and accuracy. This study trained a faster region-based convolutional neural network (Faster R-CNN) with 28,080 MRI images of lymph node metastasis, allowing the Faster R-CNN to read those images and to make diagnoses. For clinical verification, 414 cases of rectal cancer at various medical centers were collected, and Faster R-CNN-based diagnoses were compared with radiologist diagnoses using receiver operating characteristic curves (ROC). The area under the Faster R-CNN ROC was 0.912, indicating a more effective and objective diagnosis. The Faster R-CNN diagnosis time was 20 s/case, which was much shorter than the average time (600 s/case) of the radiologist diagnoses. Faster R-CNN enables accurate and efficient diagnosis of lymph node metastases. .

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The last conduction time accounts entirely for differences between AA-recovery and HA-recovery curves that otherwise reflect the same underlying nodal functional state. Thus, a consistent assessment of rate-dependent changes in nodal function can be achieved with either measure of recovery time.

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The roles of changes in refractory and recovery properties of the atrioventricular node as affected by facilitation and fatigue in the genesis of Wenckebach periodicity were studied in isolated rabbit heart preparations. The contribution of nodal recovery time, facilitation, and fatigue to beat-to-beat changes in nodal conduction time (NCT) and effective (ERPN) and functional refractory periods of node (FRPN) occurring during stable 4:3 Wenckebach cycles was determined with premature stimulation protocols performed during these cycles. Fatigue prolonged, equally for each beat, NCT, ERPN, and FRPN, and therefore did not contribute to Wenckebach periodicity. Beat-to-beat increases in facilitation broadened the range of recovery times for which conduction was successful and decreased NCT, ERPN, and FRPN below the values expected from fatigue alone. However, ERPN and NCT increased overall from beat to beat because of NCT-induced (effects of NCT on ensuing refractoriness) increases in nodal refractoriness and consequent shortenings of the recovery time. These findings establish a complementary role for the recovery and refractory properties in generating the Wenckebach periodicity and demonstrate the modulating roles of facilitation and fatigue on this phenomenon.