Strain Ultrasound Elastography of Aneurysm Sac Content after Randomized Endoleak Embolization with Sclerosing vs. Non-sclerosing Chitosan-based Hydrogels in a Canine Model.

PURPOSE: To compare the mechanical properties of aneurysm content after endoleak embolization with a chitosan hydrogel (CH) with that with a chitosan hydrogel with sodium tetradecyl sulfate (CH-STS) using strain ultrasound elastography (SUE). MATERIALS AND METHODS: Bilateral common iliac artery type Ia endoleaks were created in 9 dogs. Per animal, 1 endoleak was randomized to blinded embolization with CH, and the other, with CH-STS. Brightness-mode ultrasound, Doppler ultrasound, SUE radiofrequency ultrasound, and computed tomography were performed for up to 6 months until sacrifice. Radiologic and histopathologic studies were coregistered to identify 3 regions of interest: the embolic agent, intraluminal thrombus (ILT), and aneurysm sac. SUE segmentations were performed by 2 blinded independent observers. The maximum axial strain (MAS) was the primary outcome. Statistical analysis was performed using the Fisher exact test, multivariable linear mixed-effects models, and intraclass correlation coefficients (ICCs). RESULTS: Residual endoleaks were identified in 7 of 9 (78%) and 4 of 9 (44%) aneurysms embolized with CH and CH-STS, respectively (P = .3348). CH-STS had a 66% lower MAS (P < .001) than CH. The ILT had a 37% lower MAS (P = .01) than CH and a 77% greater MAS (P = .079) than CH-STS. There was no significant difference in ILT between treatments. The aneurysm sacs embolized with CH-STS had a 29% lower MAS (P < .001) than those embolized with CH. Residual endoleak was associated with a 53% greater MAS (P < .001). The ICC for MAS was 0.807 (95% confidence interval: 0.754-0.849) between segmentations. CONCLUSIONS: CH-STS confers stiffer intraluminal properties to embolized aneurysms. Persistent endoleaks are associated with increased sac strain, an observation that may help guide management.

Use of cardiovascular magnetic resonance in the evaluation of a giant right atrial appendage aneurysm: a case report and review of the literature.

BACKGROUND: Right atrial appendage aneurysms are rare entities that may have significant clinical consequences. When co-existing with atrial fibrillation, patients are at risk of developing pulmonary or paradoxical systemic emboli. CASE PRESENTATION: An elderly patient presented to medical attention with symptoms of acute diverticulitis. On abdominal computed tomography, a massively enlarged right atrial appendage aneurysm was discovered incidentally. The aneurysm caused marked compression of the right ventricle and contained an area of hypoenhancement concerning for an intraluminal thrombus. Gadolinium-enhanced cardiovascular magnetic resonance was performed and first-pass perfusion images demonstrated that the area of hypoenhancement was in fact poorly mixing blood. The patient was therefore managed medically. CONCLUSION: Right atrial appendage aneurysms are infrequently encountered cardiac abnormalities. In the literature, surgery has been offered to patients who are young, symptomatic, or have evidence of thrombotic disease, although whether this practice pattern is associated with superior clinical outcomes is unclear. In the present case, gadolinium-enhanced cardiovascular magnetic resonance imaging was used to exclude the presence of intraluminal thrombus in an elderly patient, which helped orient the patient's treating team towards medical-rather than surgical-therapy.

Chitosan-doxycycline hydrogel: An MMP inhibitor/sclerosing embolizing agent as a new approach to endoleak prevention and treatment after endovascular aneurysm repair.

The success of endovascular repair of abdominal aortic aneurysms remains limited due to the development of endoleaks. Sac embolization has been proposed to manage endoleaks, but current embolizing materials are associated with frequent recurrence. An injectable agent that combines vascular occlusion and sclerosing properties has demonstrated promise for the treatment of endoleaks. Moreover, the inhibition of aneurysmal wall degradation via matrix metalloproteinases (MMPs) may further prevent aneurysm progression. Thus, an embolization agent that promotes occlusion, MMP inhibition and endothelial ablation was hypothesized to provide a multi-faceted approach for endoleak treatment. In this study, an injectable, occlusive chitosan (CH) hydrogel containing doxycycline (DOX)-a sclerosant and MMP inhibitor-was developed. Several CH-DOX hydrogel formulations were characterized for their mechanical and sclerosing properties, injectability, DOX release rate, and MMP inhibition. An optimized formulation was assessed for its short-term ability to occlude blood vessels in vivo. All formulations were injectable and gelled rapidly at body temperature. Only hydrogels prepared with 0.075M sodium bicarbonate and 0.08M phosphate buffer as the gelling agent presented sufficient mechanical properties to immediately impede physiological flow. DOX release from this gel was in a two-stage pattern: a burst release followed by a slow continuous release. Released DOX was bioactive and able to inhibit MMP-2 activity in human glioblastoma cells. Preliminary in vivo testing in pig renal arteries showed immediate and delayed embolization success of 96% and 86%, respectively. Altogether, CH-DOX hydrogels appear to be promising new multifunctional embolic agents for the treatment of endoleaks. STATEMENT OF SIGNIFICANCE: An injectable embolizing chitosan hydrogel releasing doxycycline (DOX) was developed as the first multi-faceted approach for the occlusion of blood vessels. It combines occlusive properties with DOX sclerosing and MMP inhibition properties, respectively known to prevent recanalization process and to counteract the underlying pathophysiology of vessel wall degradation and aneurysm progression. After drug release, the biocompatible scaffold can be invaded by cells and slowly degrade. Local DOX delivery requires lower drug amount and decreases risks of side effects compared to systemic administration. This new gel could be used for the prevention or treatment of endoleaks after endovascular aneurysm repair, but also for the embolization of other blood vessels such as venous or vascular malformations.

Utility and costs of radiologist interpretation of perioperative imaging in patients with traumatic single-level thoracolumbar fractures.

OBJECTIVE The cost of spine management is rising. As diagnostic imaging accounts for approximately 10% of total patient care spending, there is interest in determining if economies could be made with regard to the routine consultation of radiology for image interpretation. In the context of spine trauma, both the spine surgeon and the radiologist interpret perioperative imaging. Authors of the present study investigated the impact of radiologist interpretation of perioperative imaging from patients with traumatic single-level thoracolumbar fractures given that spine surgeons are expected to be comfortable interpreting pathologies of the musculoskeletal system. METHODS The authors conducted a retrospective review of all patients presenting with a single-level thoracolumbar fracture treated at the McGill University Health Centre in the period from January 2003 to December 2010. The time between image capture and radiologist interpretation as well as the number of extraskeletal and/or incidental findings was extracted from the radiology reports on all perioperative images including radiographic, fluoroscopic, and CT images. The cost of interpretation was obtained from the provincial health insurance entity of Quebec. RESULTS Eighty-two patients met the study inclusion criteria. Radiologists took a median of 1 day (IQR 0-5.5 days) to interpret preoperative radiographs. Intraoperative fluoroscopic images and postoperative radiographs were read by the radiologist a median of 19 days (IQR 4-56.75 days) and 34 days (IQR 1-137.5 days) after capture, respectively (p < 0.05). Preoperative radiologist dictations reported extraskeletal and/or incidental findings for 8.1% of radiographs; there were no intraoperative or postoperative extraskeletal findings beyond those previously reported on the preoperative radiographs. Radiologists took a median of 1 day (IQR 0-1 day) to read both preoperative and postoperative CT scans; extraskeletal and/or incidental findings were present in 46.2% of preoperative reports and 4.5% of postoperative reports. There were no intraoperative or postoperative radiological findings that provoked reoperation. A total of 66 intraoperative fluoroscopy images and 225 postoperative radiographs were read for a cost of $1399.20 and $1867.50 (Canadian dollars), respectively, for radiologist interpretation. This cost amounted to 40.3% of all perioperative image interpretation spending. CONCLUSIONS In the management of single-level thoracolumbar fractures, radiologists add information to the diagnostic picture when interpreting preoperative radiographs and perioperative CT scans; however, the interpretation of intraoperative fluoroscopic images and postoperative radiographs comes with significant delay, does not add additional information, and represents an area of potential cost and professional-resource reduction.

Liver segmentation: indications, techniques and future directions.

OBJECTIVES: Liver volumetry has emerged as an important tool in clinical practice. Liver volume is assessed primarily via organ segmentation of computed tomography (CT) and magnetic resonance imaging (MRI) images. The goal of this paper is to provide an accessible overview of liver segmentation targeted at radiologists and other healthcare professionals. METHODS: Using images from CT and MRI, this paper reviews the indications for liver segmentation, technical approaches used in segmentation software and the developing roles of liver segmentation in clinical practice. RESULTS: Liver segmentation for volumetric assessment is indicated prior to major hepatectomy, portal vein embolisation, associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) and transplant. Segmentation software can be categorised according to amount of user input involved: manual, semi-automated and fully automated. Manual segmentation is considered the "gold standard" in clinical practice and research, but is tedious and time-consuming. Increasingly automated segmentation approaches are more robust, but may suffer from certain segmentation pitfalls. Emerging applications of segmentation include surgical planning and integration with MRI-based biomarkers. CONCLUSIONS: Liver segmentation has multiple clinical applications and is expanding in scope. Clinicians can employ semi-automated or fully automated segmentation options to more efficiently integrate volumetry into clinical practice. TEACHING POINTS: • Liver volume is assessed via organ segmentation on CT and MRI examinations. • Liver segmentation is used for volume assessment prior to major hepatic procedures. • Segmentation approaches may be categorised according to the amount of user input involved. • Emerging applications include surgical planning and integration with MRI-based biomarkers.

Aortic Calcification Progression in Heterozygote Familial Hypercholesterolemia.

BACKGROUND: Patients with homozygous and heterozygous familial hypercholesterolemia (HeFH) develop severe aortic calcifications in an age- and gene dosage-dependent manner. The purpose of this study was to determine the rate of progression of aortic calcification in patients with HeFH. METHODS: We performed thoracoabdominal computed tomography scans and quantified aortic calcium (AoCa) score in 16 HeFH patients, all with the null low-density lipoprotein (LDL) receptor DEL15Kb mutation. Patients (12 men, 4 women) were rescanned an average of 8.2 ± 0.8 years after the first scan. RESULTS: Mean LDL cholesterol (LDL-C) during treatment was 2.53 mmol/L; all patients were receiving high-dose statin/ezetimibe; 5 of 16 were receiving evolocumab. Baseline LDL-C was 7.6 ± 1.3 mmol/L. Aortic calcifications increased in all patients in an exponential fashion with respect to age. Age was the strongest correlate of AoCa score. Cholesterol, LDL-C, or age × cholesterol did not correlate with AoCa score or its progression. Control patients (n = 31; 8 male, 23 female; mean age 61 ± 11 years) who underwent virtual colonoscopy were rescanned over the same period and showed an abdominal AoCa score of 1472 ± 2489 compared with 7916 ± 7060 Agatston U (P < 0.001) in patients with HeFH during treatment (mean age, 60 ± 14 years). The rate of progression was 159 vs 312 Agatston U/y in control participants vs those with HeFH. CONCLUSIONS: HeFH patients exhibit accelerated aortic calcification that increases exponentially with age. LDL-C at baseline or during treatment seems to have little effect on the rate of progression of AoCa score. Strategies to prevent aortic calcifications with statins have not met with clinical success and novel approaches are required; statins might also contribute to the process of arterial calcification.

Support infrastructure available to Canadian residents completing post-graduate global health electives: current state and future directions.

BACKGROUND: Global health electives offer medical trainees the opportunity to broaden their clinical horizons. Canadian universities have been encouraged by regulatory bodies to offer institutional support to medical students going abroad; however, the extent to which such support is available to residents has not been extensively studied. METHODS: We conducted a survey study of Canadian universities examining the institutional support available to post-graduate medical trainees before, during, and after global health electives. RESULTS: Responses were received from 8 of 17 (47%) Canadian institutions. Results show that trainees are being sent to diverse locations around the world with more support than recommended by post-graduate regulatory bodies. However, we found that the content of the support infrastructure varies amongst universities and that certain components-pre-departure training, best practices, risk management, and post-return debriefing-could be more thoroughly addressed. CONCLUSION: Canadian universities are encouraged to continue to send their trainees on global health electives. To address the gaps in infrastructure reported in this study, the authors suggest the development of comprehensive standardized guidelines by post-graduate regulatory/advocacy bodies to better ensure patient and participant safety. We also encourage the centralization of infrastructure management to the universities' global health departments to aid in resource management.

An enhanced recovery pathway reduces duration of stay and complications after open pulmonary lobectomy.

BACKGROUND: Few studies have investigated the effectiveness of enhanced recovery pathways (ERP) for lung resection. This study estimates the impact of an ERP for lobectomy on duration of stay, complications, and readmissions. METHODS: Patients undergoing open lobectomy were identified from an OR database between 2011 and 2013. Beginning September 2012, all patients were managed according to a 4-day multidisciplinary ERP with written daily patient education treatment plans, multimodal analgesia, early diet, structured mobilization and standardized drain management. Pre-pathway (PRE) and post-pathway (POST) patients were compared in terms of duration of stay, complications, and readmissions. RESULTS: We identified 234 patients (PRE, 127; POST, 107). Groups were similar with respect to age, gender, American Society of Anesthesiologists score, and baseline pulmonary function. Compared with the PRE group, the POST group had decreased duration of stay (median, 6 [interquartile range (IQR), 5-7] vs 7 [6-10] days; P < .05), total complications (40 [37%] vs 64 [50%]; P < .05), urinary tract infections (3 [3%] vs 15 [12%]; P < .05), and chest tube duration (median, 4 [IQR, 3-6] vs 5 [4-7] days; P < .05), with no difference in readmissions (7 [7%] vs 6 [5%]; P < .05) or chest tube reinsertion (4 [4%] vs 6 [5%]; P < .05). Decreased duration of stay was driven by patients without complications (median, 5 [IQR, 4-6] vs 6 [5-7] days; P < .05). CONCLUSION: Implementation of a multimodal ERP for lobectomy was associated with decreased duration of stay and complications with no difference in readmissions.