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Background and Objectives: Hypertension increases the risk of developing atherosclerosis and arterial stiffness, with secondarily enhanced wall stress pressure that damages the artery wall. The coexistence of atherosclerosis and hypertension leads to artery stenosis and microvascular angiopathies, during which the intravascular mechanical hemolysis of red blood cells (RBCs) occurs, leading to increased platelet activation, dysfunction of the endothelium and smooth muscle cells due to a decrease in nitric oxide, and the direct harmful effects of hemoglobin and iron released from the red blood cells. This study analyzed the impact of hypertension and physical exercise on the risk of hemolysis in the left coronary artery. Methods: To analyze many different cases and consider the decrease in flow through narrowed arteries, a flow model was adopted that considered hydraulic resistance in the distal section, which depended on the conditions of hypertension and exercise. The commercial ANSYS Fluent 2023R2 software supplemented with user-defined functions was used for the simulation. CFD simulations were performed and compared with the FSI simulation results. Results: The differences obtained between the FSI and CFD simulations were negligible, which allowed the continuation of analyses based only on CFD simulations. The drops in pressure and the risk of hemolysis increased dramatically with increased flow associated with increased exercise. A relationship was observed between the increase in blood pressure and hypertension, but in this case, the increase in blood pressure dropped, and the risk of hemolysis was not so substantial. However, by far, the case of increased physical activity with hypertension had the highest risk of hemolysis, which is associated with an increased risk of clot formation that can block distal arteries and lead to myocardial hypoxia. Conclusions: The influence of hypertension and increased physical exercise on the increased risk of hemolysis has been demonstrated. [ABSTRACT FROM AUTHOR]

Background/Objective: Atherosclerosis is becoming increasingly common in modern society. Owing to the increasing number of complex angioplasty procedures, there is an increasing need for training in cases where the risk of periprocedural complications is high. Methods: A procedure was developed to obtain three-dimensional (3D) models and printing of blood vessels. The mechanical and optical properties of the printed materials were also examined. Angioplasty and stent implantation were tested, and the phantom was compared with the clinical data of patients who underwent interventional treatment. Both laser techniques and cone-beam computed tomography of the phantoms were used for comparison. Results: The printed material exhibited mechanical parameters similar to those of blood vessel walls. The refractive index of 1.473 ± 0.002 and high transparency allowed for non-invasive laser examination of the interior of the print. The printed models behaved similarly to human arteries in vivo, allowing training in treatment procedures and considering vessel deformation during the procedure. Models with stents can be analyzed using laser and cone-beam computed tomography to compare stents from different manufacturers. Conclusions: The developed methodology allows for simple and time-efficient production of personalized vessel phantoms. [ABSTRACT FROM AUTHOR]

Purpose: Prior to 90Y radioembolization procedure, a pretherapy simulation using 99mTc-MAA is performed. Alternatively, a small dosage of 90Y microspheres could be used. We aimed to assess the accuracy of lung shunt fraction (LSF) estimation in both high activity 90Y posttreatment and pretreatment scans with isotope activity of ~100 MBq, using different imaging techniques. Additionally, we assessed the feasibility of visualising hot and cold hepatic tumours in PET/CT and Bremsstrahlung SPECT/CT images. Materials and methods: Anthropomorphic phantom including liver (with two spherical tumours) and lung inserts was filled with 90Y chloride to simulate an LSF of 9.8%. The total initial activity in the liver was 1451 MBq, including 19.4 MBq in the hot sphere. Nine measurement sessions including PET/CT, SPECT/CT, and planar images were acquired at activities in the whole phantom ranging from 1618 MBq down to 43 MBq. The visibility of the tumours was appraised based on independent observers' scores. Quantitatively, contrast-to-noise ratio (CNR) was calculated for both spheres in all images. Results: LSF estimation. For high activity in the phantom, PET reconstructions slightly underestimated the LSF; absolute difference was <1.5pp (percent point). For activity <100 MBq, the LSF was overestimated. Both SPECT and planar scintigraphy overestimated the LSF for all activities. Lesion visibility. For SPECT/CT, the cold tumour proved too small to be discernible (CNR <0.5) regardless of the 90Y activity in the liver, while hot sphere was visible for activity >200 MBq (CNR>4). For PET/CT, the cold tumour was only visible with the highest 90Y activity (CNR>4), whereas the hot one was seen for activity >100 MBq (CNR>5). Conclusions: PET/CT may accurately estimate the LSF in a 90Y posttreatment procedure. However, at low activities of about 100 MBq it seems to provide unreliable estimations. PET imaging provided better visualisation of both hot and cold tumours. [ABSTRACT FROM AUTHOR]

Atherosclerosis affects human health in many ways, leading to disability or premature death due to ischemic heart disease, stroke, or limb ischemia. Poststenotic blood flow disruption may also play an essential role in artery wall impairment linked with hemolysis related to shear stress. The maximum shear stress in the atherosclerotic plaque area is the main parameter determining hemolysis risk. In our work, a 3D internal carotid artery model was built from CT scans performed on patients qualified for percutaneous angioplasty due to its symptomatic stenosis. The obtained stenosis geometries were used to conduct a series of computer simulations to identify critical parameters corresponding to the increase in shear stress in the arteries. Stenosis shape parameters responsible for the increase in shear stress were determined. The effect of changes in the carotid artery size, length, and degree of narrowing on the change in maximum shear stress was demonstrated. Then, a correlation for the quick initial diagnosis of atherosclerotic stenoses regarding the risk of hemolysis was developed. The developed relationship for rapid hemolysis risk assessment uses information from typical non-invasive tests for treated patients. Practical guidelines have been developed regarding which stenosis shape parameters pose a risk of hemolysis, which may be adapted in medical practice. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate a modified method of calculating the 99mTc/90Y tumor-to-normal-liver uptake ratio (mT/N) based on SPECT/CT imaging, for use in predicting the overall response of colorectal liver tumors after radioembolization. A modified phantom-based method of tumor-to-normal-liver ratio calculation was proposed and assessed. In contrast to the traditional method based on data gathered from the whole tumor, gamma counts are collected only from a 2D region of interest delineated in the SPECT/CT section with the longest tumor diameter (as specified in RECIST 1.1). The modified tumor-to-normal-liver ratio (mT/N1) and 90Y predicted tumor absorbed dose (PAD) were obtained based on 99mTc-MAA SPECT/CT, and similarly the modified tumor-to-normal-liver ratio (mT/N2) and 90Y actual tumor absorbed dose (AAD) were calculated after 90Y-SPECT/CT. Tumor response was assessed on follow-up CTs. Using the newly proposed method, a total of 103 liver colorectal metastases in 21 patients who underwent radioembolization (between June 2009 and October 2015) were evaluated in pre-treatment CT scans and 99mTc-MAA-SPECT/CT scans and compared with post-treatment 90Y-SPECT/CT scans and follow-up CT scans. The results showed that the mT/N1 ratio (p = 0.012), PAD (p < 0.001) and AAD (p < 0.001) were predictors of tumor response after radioembolization. The time to progression was significantly lengthened for tumors with mT/N1 higher than 1.7 or PAD higher than 70 Gy. The risk of progression for tumors with mT/N1 lower than 1.7 or PAD below 70 Gy was significantly higher. The mT/N2 ratio had no significant correlation with treatment results. Conclusion: The mT/N1 ratio, PAD, and AAD can be used as predictors of tumor response to SIRT treatment, and SPECT/CT imaging can be used for dosimetric assessment of radioembolization. [ABSTRACT FROM AUTHOR]

BACKGROUND: Selective internal radiation therapy (SIRT) with 90Y-microspheres infusion into the hepatic artery is a novel method for palliative treatment of primary and metastatic liver cancer. The post-procedural 90Y dose estimation in the liver is very difficult because direct measurement of b particles is not possible with SPECT/CT. New methods are needed to assess the 90Y-microspheres liver distribution. In the present paper we evaluate the 90Y-PET for these purposes. MATERIALS AND METHODS: A GE Discovery ST PET/CT scanner with a copper ring protected the gantry was used for images acquisition. For SPECT/CT imaging, a GE Infinia VCHWK4 with HEPG collimators was used. The liver 90Y-microspheres (SIR-Spheres, SIRTEX, Australia) dose distribution after selective internal radiotherapy treatment was evaluated in three patients (9 lesions in total). The activity of 90Y-microspheres delivered into the liver ranged from 1.0 GBq to 2.2 GBq. The correlations between liver lesions detected with 90Y-PET, 99mTc-MAA and 90-bremsstrahlung were investigated and compared with CT images obtained before and after the procedure. RESULTS: The mean T/N ratio was 2.7 in 99mTc-MAA, 2.3 in 90Y-bremsstrahlung and 3.6 in 90Y-PET. The mean 90Y absorbed dose in tumor was 133 Gy, 112 Gy, and 187 Gy, respectively. The mean liver tissue radiation was 15.5 Gy. According to RECIST criteria, one PR (mCRC) and two SD were observed (mCRC and PC). Time to progression was 217 and 117 days in two patients with mCRC and 214 days in the patient with PC. CONCLUSIONS: 90Y-PET/CT images give crucial information regarding 90Y-microspheres distribution and dosimetry and may serve as a predictor of efficiency of radioembolisation. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the efficacy of superselective renal artery embolization in patients with bleeding into the urinary system., Material/methods: From 2007 to 2012, 20 patients were treated with superselective renal artery embolization for bleeding after percutaneous nephrolithotomy (PCNL), nephron-sparing surgery (NSS), including 1 patient with AVF after PCNL. During the procedure, embolization material was injected through a microcatheter to stop the bleeding. Embolization materials included a mixture of cyanoacrylate and lipiodol, embolization coils, and Spongostan. Clinical evaluation included remission of hematuria and normalization of blood morphotic elements., Results: The cause of bleeding into the urinary tract was damage to vessels (all cases): with coexisting false aneurism (8 cases); with coexisting arterio-venus fistula (1 case); and with coexisting intrarenal hematoma (3 cases). The bleeding occurred 2-5 days after PCNL and NSS, and 10 days after PCNL with AVF. The mean hematocrit level was 22%-24%. Technical success was achieved in 20 cases. Clinical success was achieved in 19 cases. One patient with hematuria after PCNL with AVF needed a second endovascular treatment to stop bleeding., Conclusions: Superselective renal artery embolization is an effective procedure in the treatment of iatrogenic bleeding into the urinary tract after PCNL and NSS.