Phantom study of a self-shielded X-ray bone age assessment instrument against scattered radiation in children.

Hand-wrist radiography is the most common and accurate method for evaluating children's bone age. To reduce the scattered radiation of radiosensitive organs in bone age assessment, we designed a small X-ray instrument with radioprotection function by adding metal enclosure for X-ray shielding. We used a phantom operator to compare the scattered radiation doses received by sensitive organs under three different protection scenarios (proposed instrument, radiation personal protective equipment, no protection). The proposed instrument showed greater reduction in the mean dose of a single exposure compared with radiation personal protective equipment especially on the left side which was proximal to the X-ray machine (≥80.0% in eye and thyroid, ≥99.9% in breast and gonad). The proposed instrument provides a new pathway towards more convenient and efficient radioprotection.

Hemodynamic Effects of Tortuosity and Stenosis in Superficial Temporal Artery-Middle Cerebral Artery Bypass for Moyamoya Disease.

BACKGROUND: Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery has been widely adopted in treating moyamoya disease (MMD). Geometric variations including high tortuosity and stenosis exist in many cases, but the hemodynamic effects have not been comprehensively evaluated. We aim to evaluate the hemodynamic effects of bypass geometry variations based on patient-specific data. METHODS: In total, 17 patients with MMD who underwent STA-MCA bypass surgery with highly tortuous bypass geometry were included. For each patient, the original 3-dimensional structure of STA-MCA bypass was reconstructed from clinical imaging data. The bypass structure was virtually improved by removing the tortuosity and stenosis. Computational fluid dynamics simulation was performed on both bypass structures under identical patient-specific condition. The simulated hemodynamic parameters of the bypass and its distal branches were compared between the original and virtually improved bypass geometries in all cases using paired t-test or Wilcoxon signed-rank test. The changes of hemodynamic parameters were compared between the cases with and without mild-to-moderate stenosis (44.0-70.3% in diameter) in the bypass using t-test or Mann-Whitney U test. RESULTS: The virtual improvement of bypass geometry significantly increased the flow rate of the bypass and its distal branches (P < 0.05) and decreased the transcranial flow resistance (P < 0.05). The hemodynamic changes in cases with stenosis removal were significantly greater than those without stenosis (P < 0.05). CONCLUSIONS: High tortuosity and stenosis can significantly change the hemodynamics of STA-MCA bypass, and the optimization of bypass geometry deserves further consideration.

Effect of preoperative pulmonary artery pressure on the prognosis of end-stage heart failure patients after heart transplantation.

OBJECTIVE: To evaluate the effect of preoperative pulmonary artery pressure on perioperative outcome of end-stage heart failure patients undergoing heart transplantation. METHODS: Retrospective analysis was undertaken on the clinical data of patients receiving heart transplantation in the Department of Cardiovascular Surgery of our hospital from March 2017 to March 2022. A ROC curve analysis was developed between mean pulmonary artery pressure (mPAP) and postoperative mortality using mPAP as diagnostic criteria. Patients were divided into groups based on this threshold to determine the best mPAP threshold value for predicting postoperative nosocomial mortality, and the differences in preoperative and intraoperative data, postoperative complications, and clinical prognosis of patients in the two groups were compared. Patients were followed up to draw the survival curve of patients in the two groups. RESULTS: The study enlisted the participation of 105 patients. ROC curve research revealed that preoperative pulmonary artery pressure was substantially linked with death following heart transplantation, with mPAP = 30.5mmHg being the best threshold. The group with mPAP ≥ 30.5mmHg had a greater incidence of postoperative ECMO support (28.2% vs. 10.6%, P = 0.021) and a higher incidence of in-hospital mortality (15.4% vs. 1.5%, P = 0.019) than the group with mPAP < 30.5mmHg. The postoperative survival rates of 105 patients were 91.3%, 88.7%, 81.6%, and 77.5% at 1, 2, 3, and 4 years, respectively, however, there was no significant difference between the two groups of patients in the postoperative intermediate-far survival rate (P = 0.431). CONCLUSIONS: Preoperative pulmonary artery pressure in patients with end-stage heart failure is intimately correlated with perioperative prognosis of heart transplant recipients. The optimal cut-off mPAP value in predicting perioperative prognosis of heart transplant recipients is 30.5mmHg. In the high mPAP group, perioperative ECMO support rate and perioperative mortality rate are high, which do not affect the medium and long-term prognosis of the recipients undergoing heart transplantation.