A Literature Review and Case Series of DVT Patients with Absent IVC Treated with Thrombolysis.

BACKGROUND: Congenital absence of the inferior vena cava is related to deep venous thrombosis (DVT) in 5% of cases with no other risk factors. DVT is normally diagnosed by Duplex, whereas computerized tomography or magnetic resonance imaging is required to visualize this absence, and so, it is often missed but ought to be considered in young patients. There are many existing cases in the literature illustrating this link, but these patients were often managed conservatively with anticoagulation. CASE SERIES: We report five cases presenting with a DVT who were found to have an absent inferior vena cava after imaging and were treated successfully with thrombolysis and consequently managed with lifelong anticoagulation, between January 2014 and January 2019. CONCLUSIONS: Anomalies of the inferior vena cava can cause unprovoked DVT. These anomalies are often incidental findings after CT but could change the management plan in these patients. Treatment can be with anticoagulants only, thrombolysis, thrombectomy, balloon angioplasty or stents, and long-term or lifelong anticoagulation to prevent DVT recurrence.

Massive avascular malformations causing life threatening portal hypertension.

 We present an unusual case of extensive avascular malformations (AVMs) causing non-cirrhotic portal hypertension. This phenomenon, though previously described, is a rare clinical entity which, in the setting of life threatening portal hypertension, may require vascular decompression either by surgery or a transjugular intrahepatic portosystemic shunt.

Two- and three-dimensional sonographic diagnosis of fetal intra-abdominal umbilical vein varix: a case report.

Fetal intra-abdominal umbilical vein varix is a rare condition characterized by focal dilatation of the umbilical vein of the fetus. We report a case of fetal intra-abdominal umbilical vein varix associated with additional sonographic abnormalities and detected at 31 weeks' gestation. Several follow-up sonographic examinations were performed, and the prenatal findings were confirmed on postnatal ultrasound. The diagnosis was facilitated by the use of three-dimensional power Doppler sonography.

Endovascular selective hypothermia facilitates giant aneurysm clipping: illustrative case.

BACKGROUND: The authors present a case of selective hypothermia used for neuroprotection during clipping of a giant partially thrombosed middle cerebral artery (MCA) aneurysm. Although these cases have traditionally required deep hypothermic cardiac arrest, this case illustrates a novel and entirely endovascular solution that avoids cardiac standstill and whole-body cooling. OBSERVATIONS: This is, to the authors' knowledge, the first case in human surgery of a catheter-based selective hypothermic circuit used to facilitate MCA trapping for almost 30 minutes. Core temperatures never dropped below 34°C, and the patient recovered uneventfully and has been well for over 5 years. LESSONS: The technical nuances and physiological changes unique to selective hypothermia are discussed.

Endovascular Hepatic Artery Stents in the Modern Management of Postpancreatectomy Hemorrhage.

Background: Postoperative hemorrhage is a potentially lethal complication of pancreatoduodenectomy. This study reports on the use of endovascular hepatic artery stents in the management of postpancreatectomy hemorrhage. Methods: This is a retrospective analysis of a prospectively maintained, consecutive dataset of 440 patients undergoing pancreatoduodenectomy over 68 months. Data are presented on bleeding events and outcomes, and contextualized by the clinical course of the denominator population. International Study Group of Pancreatic Surgery terminology was used to define postpancreatectomy hemorrhage. Results: Sixty-seven (15%) had postoperative hemorrhage. Fifty (75%) were male and this gender difference was significant (P = 0.001; 2 proportions test). Postoperative pancreatic fistulas were more frequent in the postoperative hemorrhage group (P = 0.029; 2 proportions test). The median (interquartile range [IQR]) delay between surgery and postoperative hemorrhage was 5 days (2-14 days). Twenty-six (39%) required intervention comprising reoperation alone in 12, embolization alone in 5, and endovascular hepatic artery stent deployment in 5. Four further patients underwent more than 1 intervention with 2 of these having stents. Endovascular stent placement achieved initial hemostasis in 5 of 7 (72%). Follow-up was for a median (IQR) of 199 days (145-400 days) poststent placement. In 2 patients, the stent remained patent at last follow-up. The remaining 5 stents occluded with a median (IQR) period of proven patency of 10 days (8-22 days). Conclusions: This study shows that in the specific setting of postpancreatoduodenectomy hemorrhage with either a short remnant gastroduodenal artery bleed or a direct bleed from the hepatic artery, where embolization risks occlusion with compromise of liver arterial inflow, endovascular hepatic artery stent is an important hemostatic option but is associated with a high risk of subsequent graft occlusion.

Multiple objective planning for thermal ablation of liver tumors.

PURPOSE: Preoperative treatment planning is key to ensure successful thermal ablation of liver tumors. The planning aims to minimize the number of electrodes required for complete ablation and the damage to the surrounding tissues while satisfying multiple clinical constraints. This is a challenging multiple objective planning problem, in which the trade-off between different objectives must be considered. METHODS: We propose a novel method to solve the multiple objective planning problem, which combines the set cover-based model and Pareto optimization. The set cover-based model considers multiple clinical constraints and generates several clinically feasible treatment plans, among which the Pareto optimization is performed to find the trade-off between different objectives. RESULTS: We evaluated the proposed method on 20 tumors of 11 patients in two different situations used in common thermal ablation approaches: with and without the pull-back technique. Pareto optimal plans were found and verified to be clinically acceptable in all cases, which can find the trade-off between the number of electrodes and the damage to the surrounding tissues. CONCLUSION: The proposed method performs well in the two different situations we considered: with or without the pull-back technique. It can generate Pareto optimal plans satisfying multiple clinical constraints. These plans consider the trade-off between different planning objectives.

Geometrically variable three-dimensional ultrasound for mechanically assisted image-guided therapy of focal liver cancer tumors.

PURPOSE: Image-guided focal ablation procedures are first-line therapy options in the treatment of liver cancer tumors that provide advantageous reductions in patient recovery times and complication rates relative to open surgery. However, extensive physician training is required and image guidance variabilities during freehand therapy applicator placement limit the sufficiency of ablation volumes and the overall potential of these procedures. We propose the use of three-dimensional ultrasound (3D US) to provide guidance and localization of therapy applicators, augmenting current ablation therapies without the need for specialized procedure suites. We have developed a novel scanning mechanism for geometrically variable 3D US images, a mechanical tracking system, and a needle applicator insertion workflow using a custom needle applicator guide for targeted image-guided procedures. METHODS: A three-motor scanner was designed to use any commercially available US probe to generate accurate, consistent, and geometrically variable 3D US images. The designed scanner was mounted on a counterbalanced stabilizing and mechanical tracking system for determining the US probe orientation, which was assessed using optical tracking. Further exploiting the utility of the motorized scanner, an image-guidance workflow was developed that moved the probe to any identified target within an acquired 3D US image. The complete 3D US guidance system was used to perform mock targeted interventional procedures on a phantom by selecting a target in a 3D US image, navigating to the target, and performing needle insertion using a custom 3D-printed needle applicator guide. Registered postinsertion 3D US images and cone-beam computed tomography (CBCT) images were used to evaluate tip targeting errors when using the motors, tracking system, or mixed navigation approaches. Two 3D US image geometries were investigated to assess the accuracy of a small-footprint tilt approach and a large field-of-view hybrid approach for a total of 48 targeted needle insertions. 3D US image quality was evaluated in a healthy volunteer and compared to a commercially available matrix array US probe. RESULTS: A mean positioning error of 1.85 ± 1.33 mm was observed when performing compound joint manipulations with the mechanical tracking system. A combined approach for navigation that incorporated the motorized movement and the in-plane tracking system corrections performed the best with a mean tip error of 3.77 ± 2.27 mm and 4.27 ± 2.47 mm based on 3D US and CBCT images, respectively. No significant differences were observed between hybrid and tilt image acquisition geometries with all mean registration errors ≤1.2 mm. 3D US volunteer images resulted in clear reconstruction of clinically relevant anatomy. CONCLUSIONS: A mechanically tracked system with geometrically variable 3D US provides a utility that enables enhanced applicator guidance, placement verification, and improved clinical workflow during focal liver tumor ablation procedures. Evaluations of the tracking accuracy, targeting capabilities, and clinical imaging feasibility of the proposed 3D US system, provided evidence for clinical translation. This system could provide a workflow for improving applicator placement and reducing local cancer recurrence during interventional procedures treating liver cancer and has the potential to be expanded to other abdominal interventions and procedures.

Automatic Radiofrequency Ablation Planning for Liver Tumors With Multiple Constraints Based on Set Covering.

Radiofrequency ablation (RFA) is now a widely used minimally invasive treatment method for hepatic tumors. Preoperative planning plays a vital role in RFA therapy. With increasing tumor size, multiple overlapping ablations are needed, which are challenging to optimize while considering clinical constraints. In this paper, we present a new automatic RFA planning method. First, a 2-steps set cover-based model is formulated, which can integrate multiple clinical constraints for optimization of overlapping ablations. To ensure that the planning model can be solved in a reasonable time, a search space reducing strategy is then proposed. We also developed an algorithm for automatic RFA electrode selection, which provides a proper electrode ablation zone for the planning model. The proposed method was evaluated with 20 tumors of varying sizes (0.92 cm3 to 28.4 cm3). Results showed that the proposed method can generate clinical feasible RFA plans with a minimum number of RFA electrodes and ablations, complete tumor coverage and minimized ablation of normal tissue.

Deep learning segmentation of general interventional tools in two-dimensional ultrasound images.

PURPOSE: Many interventional procedures require the precise placement of needles or therapy applicators (tools) to correctly achieve planned targets for optimal diagnosis or treatment of cancer, typically leveraging the temporal resolution of ultrasound (US) to provide real-time feedback. Identifying tools in two-dimensional (2D) images can often be time-consuming with the precise position difficult to distinguish. We have developed and implemented a deep learning method to segment tools in 2D US images in near real-time for multiple anatomical sites, despite the widely varying appearances across interventional applications. METHODS: A U-Net architecture with a Dice similarity coefficient (DSC) loss function was used to perform segmentation on input images resized to 256 × 256 pixels. The U-Net was modified by adding 50% dropouts and the use of transpose convolutions in the decoder section of the network. The proposed approach was trained with 917 images and manual segmentations from prostate/gynecologic brachytherapy, liver ablation, and kidney biopsy/ablation procedures, as well as phantom experiments. Real-time data augmentation was applied to improve generalizability and doubled the dataset for each epoch. Postprocessing to identify the tool tip and trajectory was performed using two different approaches, comparing the largest island with a linear fit to random sample consensus (RANSAC) fitting. RESULTS: Comparing predictions from 315 unseen test images to manual segmentations, the overall median [first quartile, third quartile] tip error, angular error, and DSC were 3.5 [1.3, 13.5] mm, 0.8 [0.3, 1.7]°, and 73.3 [56.2, 82.3]%, respectively, following RANSAC postprocessing. The predictions with the lowest median tip and angular errors were observed in the gynecologic images (median tip error: 0.3 mm; median angular error: 0.4°) with the highest errors in the kidney images (median tip error: 10.1 mm; median angular error: 2.9°). The performance on the kidney images was likely due to a reduction in acoustic signal associated with oblique insertions relative to the US probe and the increased number of anatomical interfaces with similar echogenicity. Unprocessed segmentations were performed with a mean time of approximately 50 ms per image. CONCLUSIONS: We have demonstrated that our proposed approach can accurately segment tools in 2D US images from multiple anatomical locations and a variety of clinical interventional procedures in near real-time, providing the potential to improve image guidance during a broad range of diagnostic and therapeutic cancer interventions.

Three-dimensional therapy needle applicator segmentation for ultrasound-guided focal liver ablation.

PURPOSE: Minimally invasive procedures, such as microwave ablation, are becoming first-line treatment options for early-stage liver cancer due to lower complication rates and shorter recovery times than conventional surgical techniques. Although these procedures are promising, one reason preventing widespread adoption is inadequate local tumor ablation leading to observations of higher local cancer recurrence compared to conventional procedures. Poor ablation coverage has been associated with two-dimensional (2D) ultrasound (US) guidance of the therapy needle applicators and has stimulated investigation into the use of three-dimensional (3D) US imaging for these procedures. We have developed a supervised 3D US needle applicator segmentation algorithm using a single user input to augment the addition of 3D US to the current focal liver tumor ablation workflow with the goals of identifying and improving needle applicator localization efficiency. METHODS: The algorithm is initialized by creating a spherical search space of line segments around a manually chosen seed point that is selected by a user on the needle applicator visualized in a 3D US image. The most probable trajectory is chosen by maximizing the count and intensity of threshold voxels along a line segment and is filtered using the Otsu method to determine the tip location. Homogeneous tissue mimicking phantom images containing needle applicators were used to optimize the parameters of the algorithm prior to a four-user investigation on retrospective 3D US images of patients who underwent microwave ablation for liver cancer. Trajectory, axis localization, and tip errors were computed based on comparisons to manual segmentations in 3D US images. RESULTS: Segmentation of needle applicators in ten phantom 3D US images was optimized to median (Q1, Q3) trajectory, axis, and tip errors of 2.1 (1.1, 3.6)°, 1.3 (0.8, 2.1) mm, and 1.3 (0.7, 2.5) mm, respectively, with a mean ± SD segmentation computation time of 0.246 ± 0.007 s. Use of the segmentation method with a 16 in vivo 3D US patient dataset resulted in median (Q1, Q3) trajectory, axis, and tip errors of 4.5 (2.4, 5.2)°, 1.9 (1.7, 2.1) mm, and 5.1 (2.2, 5.9) mm based on all users. CONCLUSIONS: Segmentation of needle applicators in 3D US images during minimally invasive liver cancer therapeutic procedures could provide a utility that enables enhanced needle applicator guidance, placement verification, and improved clinical workflow. A semi-automated 3D US needle applicator segmentation algorithm used in vivo demonstrated localization of the visualized trajectory and tip with less than 5° and 5.2 mm errors, respectively, in less than 0.31 s. This offers the ability to assess and adjust needle applicator placements intraoperatively to potentially decrease the observed liver cancer recurrence rates associated with current ablation procedures. Although optimized for deep and oblique angle needle applicator insertions, this proposed workflow has the potential to be altered for a variety of image-guided minimally invasive procedures to improve localization and verification of therapy needle applicators intraoperatively.

Usefulness of 64-detector row computed tomography for evaluation of intracoronary stents in symptomatic patients with suspected in-stent restenosis.

To determine whether 64-slice multidetector computed tomographic coronary angiography (MDCTA) can accurately assess the coronary artery lumen in symptomatic patients with previous coronary artery stents and potential in-stent restenosis (ISR). The primary aim was to determine the accuracy of binary ISR exclusion using MDCTA compared with invasive catheter angiography (ICA). Secondary aims were comparisons of stent dimensions measured using MDCTA and variables that affect accuracy. Forty patients with previous stent placement underwent both ICA and 64-slice MDCTA after elective presentation with chest pain, and ICA quantitative coronary angiographic data were used as the reference standard. Thirty-six men and 4 women (age 64 +/- 10 years; range 44 to 83) with 103 stents (2.8 +/- 1.6 stents/patient) were comparatively evaluated (stent exclusion rate 9.6%). There were 45 bare-metal and 58 drug-eluting stents (20 +/- 18 months after implantation) with an average diameter of 3.23 +/- 0.7 mm. Overall accuracy for the detection of significant ISR showed sensitivity, specificity, and positive and negative predictive values of 85%, 86%, 61%, and 96% for proximal stents > or =3 mm, which improved to 100%, 94%, 81%, and 100%; if the visible luminal diameter on MDCTA was <1.5 mm, accuracy decreased to 40%, 84%, 29%, and 90%, respectively. In conclusion, 64-slice MDCTA assessment of symptomatic patients with suspected clinically significant ISR is a realistic alternative to ICA if reference stent diameter is > or =2.5 mm and visible lumen cross-sectional diameter is > or =1.5 mm, for which a negative MDCTA result virtually excludes the presence of significant ISR.

3D ultrasound imaging in image-guided intervention.

Ultrasound imaging is used extensively in diagnosis and image-guidance for interventions of human diseases. However, conventional 2D ultrasound suffers from limitations since it can only provide 2D images of 3-dimensional structures in the body. Thus, measurement of organ size is variable, and guidance of interventions is limited, as the physician is required to mentally reconstruct the 3-dimensional anatomy using 2D views. Over the past 20 years, a number of 3-dimensional ultrasound imaging approaches have been developed. We have developed an approach that is based on a mechanical mechanism to move any conventional ultrasound transducer while 2D images are collected rapidly and reconstructed into a 3D image. In this presentation, 3D ultrasound imaging approaches will be described for use in image-guided interventions.

A 3D ultrasound scanning system for image guided liver interventions.

PURPOSE: Two-dimensional ultrasound (2D US) imaging is commonly used for diagnostic and intraoperative guidance of interventional liver procedures; however, 2D US lacks volumetric information that may benefit interventional procedures. Over the past decade, three-dimensional ultrasound (3D US) has been developed to provide the missing spatial information. 3D US image acquisition is mainly based on mechanical, electromagnetic, and freehand tracking of conventional 2D US transducers, or 2D array transducers available on high-end machines. These approaches share many problems during clinical use for interventional liver imaging due to lack of flexibility and compatibility with interventional equipment, limited field-of-view (FOV), and significant capital cost compared to the benefits they introduce. In this paper, a novel system for mechanical 3D US scanning is introduced to address these issues. METHODS: The authors have developed a handheld mechanical 3D US system that incorporates mechanical translation and tilt sector sweeping of any standard 2D US transducer to acquire 3D images. Each mechanical scanning function can be operated independently or may be combined to allow for a hybrid wide FOV acquisition. The hybrid motion mode facilitates registration of other modalities (e.g., CT or MRI) to the intraoperative 3D US images by providing a larger FOV in which to acquire anatomical information. The tilting mechanism of the developed mover allows image acquisition in the intercostal rib space to avoid acoustic shadowing from bone. The geometric and volumetric scanning validity of the 3D US system was evaluated on tissue mimicking US phantoms for different modes of operation. Identical experiments were performed on a commercially available 3D US system for direct comparison. To replicate a clinical scenario, the authors evaluated their 3D US system by comparing it to CT for measurement of angle and distance between interventional needles in different configurations, similar to those used for percutaneous ablation of liver tumors. RESULTS: The mean geometrical hybrid 3D reconstruction error measured from scanning of a known string phantom was less than 1 mm in two directions and 2.5 mm in the scanning direction, which was comparable or better than the same measurements obtained from a commercially available 3D US system. The error in volume measurements of spherical phantom models depended on depth of the object. For a 20 cm(3) model at a depth of 15 cm, a standard depth for liver imaging, the mean error was 3.6% ± 4.5% comparable to the 2.3% ± 1.8% error for the 3D US commercial system. The error in 3D US measurement of the tip distance and angle between two microwave ablation antennas inserted into the phantom was 0.9 ± 0.5 mm and 1.1° ± 0.7°, respectively. CONCLUSIONS: A 3D US system with hybrid scanning motions for large field-of-view 3D abdominal imaging has been developed and validated. The superior spatial information provided by 3D US might enhance image-guidance for percutaneous interventional treatment of liver malignancies. The system has potential to be integrated with other liver procedures and has application in other abdominal organs such as kidneys, spleen, or adrenals.

Challenging management of a complex distal aortic arch pseudoaneurysm following previous aortic dissection repair.

The primary goals of surgery for acute aortic dissection are to resect or control the intimal flap, prevent distal malperfusion, protect the brain and have a viable patient. However, several technical measures are important to prevent early and late sequalae, including adequate aortic resection, creating a stable anastamotic suture line, appropriate graft measurement and tailoring and completely resecting inciting aortic aneurysms. Utilizing simultaneous sternotomy and thoracotomy incisions, we report the re-operative management of a patient with an expanding distal aortic arch pseudoaneurysm, extending into the left pleural space, superimposed upon severely kinked proximal ascending aortic grafts and an aneurysmal aortic root only 6 months after initial repair.

Transcatheter embolization of a renal arteriovenous fistula complicated by an aneurysm of the feeding renal artery.

Renal arteriovenous fistula (AVF) is rare. Renal AVF complicated by aneurysm of the feeding artery presents a technical challenge for endovascular treatment. We report a case managed by covered stenting of the renal artery aneurysm, coil embolization of the fistula, and bare stenting of the aorta.

Recanalization of an occluded infrainguinal vein graft complicated by graft aneurysm.

The technique of subintimal angioplasty has been described for the recanalisation of native vessels after occlusion of infrainguinal vascular bypass grafts. We report a case in which an attempt at such treatment resulted in inadvertent but successful recanalisation of the occluded vein graft instead. This was complicated by graft perforation and subsequent graft aneurysm which was successfully treated with a covered stent.

Percutaneous transhepatic use of a cutting balloon in the treatment of a benign common bile duct stricture.

Benign biliary strictures (BBS) are difficult to treat. The majority of them are treated either endoscopically or using percutaneous techniques either with stents or conventional angioplasty balloons. To our knowledge we present the first case of use of a cutting balloon in the treatment of BBS through a percutaneous approach.

Systemic septic embolisation secondary to an atrial myxoma in a young woman.

We present a case of a left atrial myxoma infected with Staphylococcus aureus in a 35-year-old woman who was found to have a retained tampon. Multiple systemic septic emboli were seen on computed tomography imaging of the brain, spleen and kidneys. She was successfully treated by surgical excision of the myxoma and 4 weeks of antibiotic therapy. We postulate that the source of this patient's S. aureus infection was tampon use, leading to a toxic shock syndrome and causing infection of an undiagnosed left atrial myxoma, which led to the embolisation. As far as the authors are aware, this is the first reported case of such an entity. In those with an underlying cardiac predisposition, tampon use may represent a risk of infection with S. aureus, and we intend to heighten clinical awareness of this potentially life-threatening association. We also discuss the diagnosis, complications and treatment of infected atrial myxoma and illustrate the imaging findings.