Conjoined right hepatic artery from branches of the common hepatic and gastroduodenal arteries: a rare anatomic variant.

PURPOSE: To describe a previously unreported anatomical variant of the hepatic arterial supply: a conjoined right hepatic artery, formed by branches of the common hepatic artery and gastroduodenal artery. METHOD: A 54-year-old female with oligometastatic colorectal cancer with metastases to the liver presented for planning stage arteriography in preparation for Y90 radioembolization. RESULTS: Arteriography of the common hepatic artery demonstrated bifurcation into a right hepatic artery and gastroduodenal artery. The gastroduodenal artery gave rise to a proximal branch, from which the left hepatic artery originated and then continued to anastomose in the hilum of the liver to the right hepatic artery originating from the common hepatic artery. It was initially identified on visceral artery arteriography and then retrospectively recognized on pre-procedural CT scan. CONCLUSION: Anatomical variants of the hepatic arterial supply are important to recognize during planning stage arteriography in preparation for Y90 radioembolization. Knowledge of these variants is also important for pre-operative planning.

Plasma trial: Pilot randomized clinical trial to determine safety and efficacy of plasma transfusions.

BACKGROUND: Plasma is frequently administered to patients with prolonged INR prior to invasive procedures. However, there is limited evidence evaluating efficacy and safety. STUDY DESIGN AND METHODS: We performed a pilot trial in hospitalized patients with INR between 1.5 and 2.5 undergoing procedures conducted outside the operating room. We excluded patients undergoing procedures proximal to the central nervous system, platelet counts <40,000/µl, or congenital or acquired coagulation disorders unresponsive to plasma. We randomly allocated patients stratified by hospital and history of cirrhosis to receive plasma transfusion (10-15 cc/kg) or no transfusion. The primary outcome was change in hemoglobin concentration within 2 days of procedure. RESULTS: We enrolled 57 patients, mean age 56.0, 34 (59.6%) with cirrhosis, and mean INR 1.92 (SD = 0.27). In the intention to treat analysis, there were 10 of 27 (38.5%) participants in the plasma arm with a post procedure INR <1.5 and one of 30 (3.6%) in the no treatment arm (p < .01). The mean INR after receiving plasma transfusion was -0.24 (SD 0.26) lower than baseline. The change from pre-procedure hemoglobin level to lowest level within 2 days was -0.6 (SD = 1.0) in the plasma transfusion arm and -0.4 (SD = 0.6) in the no transfusion arm (p = .29). Adverse outcomes were uncommon. DISCUSSION: We found no differences in change in hemoglobin concentration in those treated with plasma compared to no treatment. The change in INR was small and corrected to less than 1.5 in minority of patients. Large trials are required to establish if plasma is safe and efficacious.

Conditional survival analysis of hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide with an approximate 5-year survival of greater than 50% in patients after surgical resection. Survival estimates have limited utility for patients who have survived several years after initial treatment. We analyzed how conditional survival (CS) after curative-intent surgery for HCC predicts survival estimates over time. METHODS: NCDB (2004-2014) was queried for patients undergoing definitive surgical resection for HCC. Cumulative overall survival (OS) was calculated using the Kaplan-Meier method, and CS at x years after diagnosis was calculated as CS1 = OS (X+5) /OS(X) . RESULTS: The final analysis encompassed 11 357 patients. Age, negative margin status, grade severity and radiation before surgery were statistically significant predictors of cumulative overall conditional survival (P ≤ .0001). Overall unconditional 5-year survival was 65.7%, but CS estimates were higher. A patient who has already survived 3 years has an additional 2-year, or 5-year CS, estimate of 86.96%. CONCLUSION: Survival estimates following hepatic resection in HCC patients change according to survival time accrued since surgery. CS estimates are improved relative to unconditional OS. The impact of different variables influencing OS is likewise nonlinear over the course of time after surgery.

Replaced right and common hepatic arteries with lienogastric trunk: a rare variant of celiaco-mesenteric anatomy.

We report a rare variant in mesenteric arterial anatomy: replacement of the right hepatic and common hepatic arteries to the SMA in a patient treated for hepatocellular carcinoma. The potential clinical implications of this unusual variation of celiaco-mesenteric anatomy will be discussed.

Aberrant arc between the common hepatic artery and a replaced right hepatic artery resulting in misperfusion in a patient with a hepatic arterial infusion pump.

Hepatic arterial infusion pumps are increasingly utilized as an option for liver directed therapy in the treatment of metastatic colorectal carcinoma. After skeletonization of the hepatic artery through the ligation of extra-hepatic branches, these pumps are implanted surgically with their tip placed in the common hepatic artery. Subsequently, a nuclear medicine pump study is performed to ensure homogeneous perfusion of the liver and detect any extrahepatic perfusion. We report a peripheral arc between the superior mesenteric artery and celiac axis, which caused misperfusion on the SPECT nuclear medicine scan.

Predictors of Survival after Yttrium-90 Radioembolization for Colorectal Cancer Liver Metastases.

PURPOSE: To identify clinical parameters that are prognostic for improved overall survival (OS) after yttrium-90 radioembolization (RE) in patients with liver metastases from colorectal cancer (CRC). MATERIALS AND METHODS: A total of 131 patients who underwent RE for liver metastases from CRC, treated at 2 academic centers, were reviewed. Twenty-one baseline pretreatment clinical factors were analyzed in relation to OS by the Kaplan-Meier method along with log-rank tests and univariate and multivariate Cox regression analyses. RESULTS: The median OS from first RE procedure was 10.7 months (95% confidence interval [CI], 9.4-12.7 months). Several pretreatment factors, including lower carcinoembryonic antigen (CEA; ≤20 ng/mL), lower aspartate transaminase (AST; ≤40 IU/L), neutrophil-lymphocyte ratio (NLR) <5, and absence of extrahepatic disease at baseline were associated with significantly improved OS after RE, compared with high CEA (>20 ng/mL), high AST (>40 IU/L), NLR ≥5, and extrahepatic metastases (P values of <.001, <.001, .0001, and .04, respectively). On multivariate analysis, higher CEA, higher AST, NLR ≥5, extrahepatic disease, and larger volume of liver metastases remained independently associated with risk of death (hazard ratios of 1.63, 2.06, 2.22, 1.48, and 1.02, respectively). CONCLUSIONS: The prognosis of patients with metastases from CRC is impacted by a complex set of clinical parameters. This analysis of pretreatment factors identified lower AST, lower CEA, lower NLR, and lower tumor burden (intra- or extrahepatic) to be independently associated with higher survival after hepatic RE. Optimal selection of patients with CRC liver metastases may improve survival rates after administration of yttrium-90.

A Comparison of Yttrium-90 Microsphere Radioembolization to Hepatic Arterial Infusional Chemotherapy for Patients with Chemo-refractory Hepatic Colorectal Metastases.

OPINION STATEMENT: Patients with unresectable hepatic colorectal metastases who become chemo-refractory have limited treatment options. Systemic chemotherapies such as TAS102 and regorafenib have been used in the refractory setting, but with only modest improvement in overall survival compared to best supportive care. In patients with liver-only or liver-dominant disease, direct chemotherapy to the liver such as hepatic artery infusional (HAI) chemotherapy and radioembolization (yttrium-90 (Y90)) should be considered. Due to the difficulty of HAI therapy post Y90 for technical reasons, we recommend HAI therapy prior to Y90.

Pilot study of angiogenic response to yttrium-90 radioembolization with resin microspheres.

PURPOSE: To investigate the impact of radioembolization with yttrium-90 resin microspheres on the regulation of angiogenesis through observation of serial changes in a spectrum of angiogenic markers and other cytokines after therapy. MATERIALS AND METHODS: This prospective pilot study enrolled 22 patients with liver-dominant disease deriving from biopsy-proven hepatocellular carcinoma (HCC) (n = 7) or metastatic colorectal carcinoma (mCRC) (n = 15). Circulating angiogenic markers were measured from serum samples drawn at baseline and at time points after therapy ranging from 6 hours to 120 days. Using multiplex enzyme-linked immunosorbent assay, several classic angiogenesis factors (vascular endothelial growth factor [VEGF], angiopoietin-2 [Ang-2], basic fibroblast growth factor [bFGF], platelet-derived growth factor subunit BB [PDGF-BB], thrombospondin-1 [Tsp-1]) and nonclassic factors (follistatin, leptin, interleukin [IL]-8) were evaluated. RESULTS: Increases in cytokine levels ≥ 50% over baseline were observed in more than half of all patients studied for many cytokines, including classic angiogenic factors such as VEGF, Ang-2, and Tsp-1 as well as nonclassic factors IL-8 and follistatin (range, 36%-82% for all cytokines). Baseline cytokine levels in patients with overall survival (OS) < 6 months differed significantly from patients with longer survival for Ang-2 (P = .033) and IL-8 (P = .041). Patients with OS ≤ 6 months exhibited transient increases in VEGF and PDGF-BB after therapy compared with patients with OS > 6 months. CONCLUSIONS: Radioembolization is associated with early transient increases in many angiogenic cytokines. In this small sample size, some of these changes were associated with worse OS. This research has important implications for future studies of radioembolization with antiangiogenic therapy performed during and after the procedure.

The power of genes: a case of unusually severe systemic toxicity after localized hepatic chemoembolization with irinotecan-eluted microspheres for metastatic colon cancer.

OBJECTIVE: To report a case of systemic irinotecan toxicity following regional transarterial chemoembolization with drug-eluting beads loaded with irinotecan (DEBIRI-TACE) in a patient later found to have a homozygous mutation for UGT1A1*28. CASE SUMMARY: An 80-year-old woman presented with a cecal colon cancer with synchronous metastases to the liver. After resection of the primary tumor, the patient underwent DEBIRI-TACE with 100 mg of irinotecan to treat the residual disease in the liver. A week after this procedure, the patient developed grade 4 neutropenia, and later, alopecia. Eventually, it was found that the patient had a mutation of UDP glucuronosyltransferase 1 family polypeptide A1 (UGT1A1), which provided a reasonable explanation for the observed reaction. DISCUSSION: The toxic effects of irinotecan are well understood. Patients with genetic polymorphisms of the genes encoding for the enzyme UGT1A1 may have increased incidence of irinotecan-associated toxicities because of decreased clearance of the active metabolite SN38 via the glucuronidation pathway. To date, there have been limited publications describing systemic adverse events following TACE or DEBIRI-TACE and, based on a thorough literature search, none following these procedures in patients with UGT1A1 polymorphisms. Based on the scoring results of the Naranjo algorithm (7), we are confident in attributing the observed reaction to the patient's genetic polymorphism. CONCLUSION: Although genetic testing prior to the initiation of irinotecan therapy is not currently recommended, assessment of UGT1A1 polymorphism is warranted when severe adverse events typical of systemic therapy manifest following DEBIRI-TACE.

Endoscopic Ultrasound-Guided Gallbladder Drainage Versus Percutaneous Drainage in Patients With Acute Cholecystitis Undergoing Elective Cholecystectomy.

INTRODUCTION: Cholecystectomy (CCY) is the gold standard treatment of acute cholecystitis (AC). Nonsurgical management of AC includes percutaneous transhepatic gallbladder drainage (PT-GBD) and endoscopic ultrasound-guided gallbladder drainage (EUS-GBD). This study aims to compare outcomes of patients who undergo CCY after having received EUS-GBD vs PT-GBD. METHODS: A multicenter international study was conducted in patients with AC who underwent EUS-GBD or PT-GBD, followed by an attempted CCY, between January 2018 and October 2021. Demographics, clinical characteristics, procedural details, postprocedure outcomes, and surgical details and outcomes were compared. RESULTS: One hundred thirty-nine patients were included: EUS-GBD in 46 patients (27% male, mean age 74 years) and PT-GBD in 93 patients (50% male, mean age 72 years). Surgical technical success was not significantly different between the 2 groups. In the EUS-GBD group, there was decreased operative time (84.2 vs 165.4 minutes, P < 0.00001), time to symptom resolution (4.2 vs 6.3 days, P = 0.005), and length of stay (5.4 vs 12.3 days, P = 0.001) compared with the PT-GBD group. There was no difference in the rate of conversion from laparoscopic to open CCY: 5 of 46 (11%) in the EUS-GBD arm and 18 of 93 (19%) in the PT-GBD group ( P value 0.2324). DISCUSSION: Patients who received EUS-GBD had a significantly shorter interval between gallbladder drainage and CCY, shorter surgical procedure times, and shorter length of stay for the CCY compared with those who received PT-GBD. EUS-GBD should be considered an acceptable modality for gallbladder drainage and should not preclude patients from eventual CCY.

Modern Management of Localized Renal Cell Carcinoma- Is Ablation Part of the Equation?

While the gold-standard for management of localized renal cell carcinoma (RCC) is partial nephrectomy, recent ablative strategies are emerging as alternatives with comparable rates of complications and oncologic outcomes. Thermal ablation, in the form of radiofrequency ablation and cryoablation, is being increasingly accepted by professional societies, and is particularly recommended in patients with a significant comorbidity burden, renal impairment, old age, or in those unwilling to undergo surgery. Maturation of long-term oncologic outcomes has further allowed increased confidence in these management strategies. New and exciting ablation technologies such as microwave ablation, stereotactic body radiotherapy, and irreversible electroporation are emerging. In this article, we review the existing management options for localized RCC, with specific focus on the oncologic outcomes associated with the various ablation modalities.

Changes in liver and spleen volumes and liver function after radioembolization with yttrium-90 resin microspheres.

PURPOSE: To evaluate injury to normal liver parenchyma following radioembolization with yttrium-90 ((90)Y) resin microspheres as reflected by liver and spleen volume and liver function, and to investigate the influence of chemotherapy on these changes. MATERIALS AND METHODS: A retrospective review of a prospectively acquired database of patients undergoing (90)Y radioembolization with resin microspheres over a 24-month period was performed to assess for changes in liver and spleen volume and liver function. Patients undergoing whole-liver or sequential bilobar treatment with at least 3 months of follow-up were included in the study. Chemotherapy records were reviewed, and the influence of agents with known hepatotoxicity on liver and spleen volume and alteration in liver function was assessed. RESULTS: Thirty-seven patients were included in the analysis. Significant decrease in liver volume (12.5%; P = .002) and increase in spleen volume (63%; P = .003) were observed, as were trends for increases in serum bilirubin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels and decreases in platelet and white blood cell counts. Chemotherapy with agents with known hepatotoxicity administered before and after radioembolization increased the extent of liver injury, but this did not reach statistical significance. CONCLUSIONS: The normal liver is not spared radiation effects from (90)Y radioembolization as demonstrated by serial changes in liver and spleen volumes, as well as liver function. However, these changes were of limited clinical significance in the patients studied.

Textural kinetics: a novel dynamic contrast-enhanced (DCE)-MRI feature for breast lesion classification.

Dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) of the breast has emerged as an adjunct imaging tool to conventional X-ray mammography due to its high detection sensitivity. Despite the increasing use of breast DCE-MRI, specificity in distinguishing malignant from benign breast lesions is low, and interobserver variability in lesion classification is high. The novel contribution of this paper is in the definition of a new DCE-MRI descriptor that we call textural kinetics, which attempts to capture spatiotemporal changes in breast lesion texture in order to distinguish malignant from benign lesions. We qualitatively and quantitatively demonstrated on 41 breast DCE-MRI studies that textural kinetic features outperform signal intensity kinetics and lesion morphology features in distinguishing benign from malignant lesions. A probabilistic boosting tree (PBT) classifier in conjunction with textural kinetic descriptors yielded an accuracy of 90%, sensitivity of 95%, specificity of 82%, and an area under the curve (AUC) of 0.92. Graph embedding, used for qualitative visualization of a low-dimensional representation of the data, showed the best separation between benign and malignant lesions when using textural kinetic features. The PBT classifier results and trends were also corroborated via a support vector machine classifier which showed that textural kinetic features outperformed the morphological, static texture, and signal intensity kinetics descriptors. When textural kinetic attributes were combined with morphologic descriptors, the resulting PBT classifier yielded 89% accuracy, 99% sensitivity, 76% specificity, and an AUC of 0.91.

Fiducial marker migration following computed tomography-guided placement in the liver: a case report.

Radiation therapy for liver tumors has been shown to provide a local control and overall survival benefit in patients with primary or oligometastatic liver tumors. However, accurate delineation of the target volume in intraabdominal tumors can be limited by diaphragmatic motion. In addition to image guidance during radiation therapy, computed tomography (CT)-guided fiducial marker placement can improve the accuracy of radiation treatment and optimize tumor control. Fiducial marker placement is often indicated in stereotactic body radiation therapy (SBRT) due to the ablative doses used as well as in proton therapy given that these markers are clearly visible on orthogonal kV image guidance and studies have suggested that their placement in liver tumors offers improved local control. However, fiducial marker migration is a rare risk associated with fiducial placement for which literature remains scarce. We report two separate cases of fiducial marker migrations from the liver into the inferior vena cava and right atrium which occurred following CT-guided placement without any resultant toxicity. Imaging using contrast-enhanced or volume navigation ultrasound techniques during fiducial marker deployment may mitigate the risk of fiducial marker migration and potential end-organ injury. Alternative techniques for motion management such as inspiratory or expiratory breath hold or use of residual lipiodol on imaging in patients who have undergone transarterial chemoembolization (TACE) should be considered as well to avoid potential complications from fiducial marker placement.

Chest X-ray image phase features for improved diagnosis of COVID-19 using convolutional neural network.

PURPOSE: Recently, the outbreak of the novel coronavirus disease 2019 (COVID-19) pandemic has seriously endangered human health and life. In fighting against COVID-19, effective diagnosis of infected patient is critical for preventing the spread of diseases. Due to limited availability of test kits, the need for auxiliary diagnostic approach has increased. Recent research has shown radiography of COVID-19 patient, such as CT and X-ray, contains salient information about the COVID-19 virus and could be used as an alternative diagnosis method. Chest X-ray (CXR) due to its faster imaging time, wide availability, low cost, and portability gains much attention and becomes very promising. In order to reduce intra- and inter-observer variability, during radiological assessment, computer-aided diagnostic tools have been used in order to supplement medical decision making and subsequent management. Computational methods with high accuracy and robustness are required for rapid triaging of patients and aiding radiologist in the interpretation of the collected data. METHOD: In this study, we design a novel multi-feature convolutional neural network (CNN) architecture for multi-class improved classification of COVID-19 from CXR images. CXR images are enhanced using a local phase-based image enhancement method. The enhanced images, together with the original CXR data, are used as an input to our proposed CNN architecture. Using ablation studies, we show the effectiveness of the enhanced images in improving the diagnostic accuracy. We provide quantitative evaluation on two datasets and qualitative results for visual inspection. Quantitative evaluation is performed on data consisting of 8851 normal (healthy), 6045 pneumonia, and 3323 COVID-19 CXR scans. RESULTS: In Dataset-1, our model achieves 95.57% average accuracy for a three classes classification, 99% precision, recall, and F1-scores for COVID-19 cases. For Dataset-2, we have obtained 94.44% average accuracy, and 95% precision, recall, and F1-scores for detection of COVID-19. CONCLUSIONS: Our proposed multi-feature-guided CNN achieves improved results compared to single-feature CNN proving the importance of the local phase-based CXR image enhancement. Future work will involve further evaluation of the proposed method on a larger-size COVID-19 dataset as they become available.

Time-aware deep neural networks for needle tip localization in 2D ultrasound.

PURPOSE: Accurate placement of the needle is critical in interventions like biopsies and regional anesthesia, during which incorrect needle insertion can lead to procedure failure and complications. Therefore, ultrasound guidance is widely used to improve needle placement accuracy. However, at steep and deep insertions, the visibility of the needle is lost. Computational methods for automatic needle tip localization could improve the clinical success rate in these scenarios. METHODS: We propose a novel algorithm for needle tip localization during challenging ultrasound-guided insertions when the shaft may be invisible, and the tip has a low intensity. There are two key steps in our approach. First, we enhance the needle tip features in consecutive ultrasound frames using a detection scheme which recognizes subtle intensity variations caused by needle tip movement. We then employ a hybrid deep neural network comprising a convolutional neural network and long short-term memory recurrent units. The input to the network is a consecutive plurality of fused enhanced frames and the corresponding original B-mode frames, and this spatiotemporal information is used to predict the needle tip location. RESULTS: We evaluate our approach on an ex vivo dataset collected with in-plane and out-of-plane insertion of 17G and 22G needles in bovine, porcine, and chicken tissue, acquired using two different ultrasound systems. We train the model with 5000 frames from 42 video sequences. Evaluation on 600 frames from 30 sequences yields a tip localization error of [Formula: see text] mm and an overall inference time of 0.064 s (15 fps). Comparison against prior art on challenging datasets reveals a 30% improvement in tip localization accuracy. CONCLUSION: The proposed method automatically models temporal dynamics associated with needle tip motion and is more accurate than state-of-the-art methods. Therefore, it has the potential for improving needle tip localization in challenging ultrasound-guided interventions.

Liver disease classification from ultrasound using multi-scale CNN.

PURPOSE: Ultrasound (US) is the preferred modality for fatty liver disease diagnosis due to its noninvasive, real-time, and cost-effective imaging capabilities. However, traditional B-mode US is qualitative, and therefore, the assessment is very subjective. Computer-aided diagnostic tools can improve the specificity and sensitivity of US and help clinicians to perform uniform diagnoses. METHODS: In this work, we propose a novel deep learning model for nonalcoholic fatty liver disease classification from US data. We design a multi-feature guided multi-scale residual convolutional neural network (CNN) architecture to capture features of different receptive fields. B-mode US images are combined with their corresponding local phase filtered images and radial symmetry transformed images as multi-feature inputs for the network. Various fusion strategies are studied to improve prediction accuracy. We evaluate the designed network architectures on B-mode in vivo liver US images collected from 55 subjects. We also provide quantitative results by comparing our proposed multi-feature CNN architecture against traditional CNN designs and machine learning methods. RESULTS: Quantitative results show an average classification accuracy above 90% over tenfold cross-validation. Our proposed method achieves a 97.8% area under the ROC curve (AUC) for the patient-specific leave-one-out cross-validation (LOOCV) evaluation. Comprehensive validation results further demonstrate that our proposed approaches achieve significant improvements compared to training mono-feature CNN architectures ([Formula: see text]). CONCLUSIONS: Feature combination is valuable for the traditional classification methods, and the use of multi-scale CNN can improve liver classification accuracy. Based on the promising performance, the proposed method has the potential in practical applications to help radiologists diagnose nonalcoholic fatty liver disease.

Multi-feature Multi-Scale CNN-Derived COVID-19 Classification from Lung Ultrasound Data.

The global pandemic of the novel coronavirus disease 2019 (COVID-19) has put tremendous pressure on the medical system. Imaging plays a complementary role in the management of patients with COVID-19. Computed tomography (CT) and chest X-ray (CXR) are the two dominant screening tools. However, difficulty in eliminating the risk of disease transmission, radiation exposure and not being cost-effective are some of the challenges for CT and CXR imaging. This fact induces the implementation of lung ultrasound (LUS) for evaluating COVID-19 due to its practical advantages of noninvasiveness, repeatability, and sensitive bedside property. In this paper, we utilize a deep learning model to perform the classification of COVID-19 from LUS data, which could produce objective diagnostic information for clinicians. Specifically, all LUS images are processed to obtain their corresponding local phase filtered images and radial symmetry transformed images before fed into the multi-scale residual convolutional neural network (CNN). Secondly, image combination as the input of the network is used to explore rich and reliable features. Feature fusion strategy at different levels is adopted to investigate the relationship between the depth of feature aggregation and the classification accuracy. Our proposed method is evaluated on the point-of-care US (POCUS) dataset together with the Italian COVID-19 Lung US database (ICLUS-DB) and shows promising performance for COVID-19 prediction.

A link between stent radial forces and vascular wall remodeling: the discovery of an optimal stent radial force for minimal vessel restenosis.

Coronary and peripheral artery disease (PAD) continue to be primary causes of morbidity and mortality in western nations; percutaneous transluminal angioplasty (PTA) with stenting has become a popular treatment. Unfortunately, restenosis is a significant problem following intravascular stent placement. This study considers the contribution of stent forces in vascular stenosis and remodeling to develop an equation for identifying the optimal stent force. z-Type stents of three radial forces [low (3.4 N), high (16.4 N), and ultrahigh (19.4 N)] were deployed into the iliac arteries of a juvenile porcine model. Vessel diameters were measured before, after deployment, and again at 30 days. At 30 days animals were killed and the vessels fixed in situ. After implantation, there was a significant increase in total thickness and neointimal hyperplasia with increasing stent force. The model for vessel radius and experimental data was in agreement. The model shows that maximum late-term radius is achieved with a stent deployment stress of 480 kPa, which occurs at the end of the stress-strain curve nonlinear domain and beginning of the high-strain collagen domain. The results and calculations suggest that an optimal stent force exists that is subject to the geometry, structure, and mechanics of the target vessel. To achieve maximum late-term dilatation, stents should not produce stress in the vessel wall greater than the end of the transitional domain of the vessel's stress-strain curve. This finding is extremely important for vascular stent development and will be expanded to preliminary vessel wall injury and atherosclerotic models.