Andrew Winterbottom

Measuring stone volume – three-dimensional software reconstruction or an ellipsoid algebra formula?

To determine the optimal method for assessing stone volume, and thus stone burden, by comparing the accuracy of scalene, oblate, and prolate ellipsoid volume equations with three‐dimensional (3D)‐reconstructed stone volume. Kidney stone volume may be helpful in predicting treatment outcome for renal stones. While the precise measurement of stone volume by 3D reconstruction can be accomplished using modern computer tomography (CT) scanning software, this technique is not available in all hospitals or with routine acute colic scanning protocols. Therefore, maximum diameters as measured by either X‐ray or CT are used in the calculation of stone volume based on a scalene ellipsoid formula, as recommended by the European Association of Urology.

Imaging After Nellix Endovascular Aneurysm Sealing: A Consensus Document

Endovascular aneurysm sealing (EVAS) using the Nellix system is a new and different method of abdominal aortic aneurysm repair. Normal postoperative imaging has unique appearances that change with time; complications also have different and specific appearances. This consensus document on the imaging findings after Nellix EVAS is based on the collective experience of the sites involved in the Nellix EVAS Global Forward Registry and the US Investigational Device Exemption Trial. The normal findings on computed tomography (CT), duplex ultrasound, magnetic resonance imaging, and plain radiography are described. With time, endobag appearances change on CT due to contrast migration to the margins of the hydrogel polymer within the endobag. Air within the endobag also has unique appearances that change over time. Among the complications after Nellix EVAS, type I endoleak usually presents as a curvilinear area of flow between the endobag and aortic wall, while type II endoleak is typically small and usually occurs where an aortic branch artery lies adjacent to an irregular aortic blood lumen that is not completely filled by the endobag. Procedural aortic injury is an uncommon but important complication that occurs as a result of overfilling of the endobags during Nellix EVAS. The optimum imaging surveillance algorithm after Nellix EVAS has yet to be defined but is largely CT-based, especially in the first year postprocedure. However, duplex ultrasound also appears to be a sensitive modality in identifying normal appearances and complications.

Endovascular aneurysm repair (EVAR) follow-up imaging: the assessment and treatment of common postoperative complications.

Endovascular abdominal aortic aneurysm repair (EVAR) is a well-established procedure, which has long-term mortality rates similar to that of open repair. It has the additional benefit of being less invasive, making it the favoured method of treating abdominal aortic aneurysms in elderly and high-risk patients with multiple co-morbidities. The main disadvantage of EVAR is the higher rate of re-intervention, due to device-related complications, including endoleaks, limb occlusion, stent migration, kinking, and infection. As a result lifelong surveillance is required. In order to avoid missing these complications, intricate knowledge of stent graft design, good-quality diagnostic ultrasound skills, multiplanar reformatting of CT images, and reproducible investigations are important. Most of these complications can be treated via an endovascular approach using cuff extensions, uncovered stents, coils, and liquid embolic agents. Open surgery is reserved for complex complications, where an endovascular approach is not feasible.

Initial clinical evaluation of a non‐contrast‐enhanced MR angiography method in the distal lower extremities

To report the initial experience and diagnostic performance applying a novel flow‐dependent non‐contrast‐enhanced MR angiography (NCE‐MRA) method, in patients with suspected peripheral vascular disease, in comparison with established contrast‐enhanced MRA (CE‐MRA).

Endovascular aortic stent graft infection with Streptococcus equi: the first documented case.

Streptococcus equi is a common equine infectious disease, but transmission to man is rare and confined to those who commonly come into close contact with horses. Similarly, prosthetic stent graft infection is a rare complication of endovascular aortic aneurysm repair. We describe the first reported case of aortic stent graft with S. equi occurring in a professional racehorse trainer. Clinical presentation, investigations, imaging and management of this case are described. In conclusion, clinicians should consider infection with rare organisms in patients with prosthetic implants who regularly come into contact with horses and other ruminants.

Endovascular Occlusion of a Ruptured Popliteal Artery Aneurysm

Popliteal artery aneurysms are the most common of the peripheral aneurysms. Rupture is a rare complication of these aneurysms. Here we present a case of a ruptured popliteal aneurysm in a patient with severe joint disease and immobility due to rheumatoid arthritis. The condition was treated endovascularly with an Amplatzer arterial occlusion device. The aneurysm was successfully thrombosed without inducing critical limb ischemia, as the distal popliteal was chronically occluded. Ligation of peripheral aneurysms is an infrequent treatment without simultaneous bypass graft placement. Endovascular occlusion of ruptured popliteal aneurysms should be considered a valid therapeutic strategy where exclusion bypass is not required due to distal arterial occlusion.

Radiation dosage in the urolithiasis population: Do we over-radiate our patients?

Introduction: There is increasing concern about the amount of radiation that patients with urolithiasis receive. Ensuring patients are exposed to the minimum necessary radiation is imperative. Here we review the radiation dosages that newly diagnosed urolithiasis patients received in the year following their presentation, both those presenting acutely and those referred electively. Patients and methods: A retrospective study of 95 treatment-naïve patients (47 acute, 48 elective) referred for management of urolithiasis was undertaken. The analysis included all imaging modalities related to stone disease for both patient groups within one year following presentation. The total effective dose (mSV) in one year was calculated by summing the dose for each individual radiation exposure. Results: An average of 5.6 radiological investigations (range 1–14) was carried out for acute patients and 4.57 for elective patients (range 1–11). The mean total effective dose was 14.45 mSV for the acute cases and 12.87 mSV for the elective cases. The maximum radiation dose reached 30.1 mSV in acute patients and 36.51 mSV in elective ones. None of the patients exceeded the maximal annual dose recommended by the International Commission on Radiological Protection (ICRP) of 50 mSV. Conclusion: Management of acute and elective urolithiasis patients can be achieved with acceptable radiation dose exposure. It is extremely important to keep the hazards of radiation in mind whilst managing patients with urolithiasis and clinicians need to remember adherence to the ALARA principle.

Radiological Evaluation of Abdominal Endovascular Aortic Aneurysm Repair

Endovascular aortic aneurysm repair (EVAR) is an alternative to open surgical repair of aortic aneurysms offering lower perioperative mortality and morbidity. As experience increases, clinicians are undertaking complex repairs with hostile aortic anatomy using branched or fenestrated devices or extra components such as chimneys to ensure perfusion to visceral branch vessels whilst excluding the aneurysm. Defining the success of EVAR depends on both clinical and radiographic criteria, but ultimately depends on complete exclusion of the aneurysm from the circulation. Aortic stent grafts are monitored using a combination of imaging modalities including computed tomography angiography (CTA), ultrasonography, magnetic resonance imaging, plain films, and nuclear medicine studies. This article describes when and how to evaluate aortic stent grafts using each of these modalities along with the characteristic features of several of the main stent grafts currently used in clinical practice. The commonly encountered complications from EVAR are also discussed and how they can be detected using each imaging modality. As the radiation burden from serial follow up CTA imaging is now becoming a concern, different follow-up imaging strategies are proposed depending on the complexity of the repair and based on the relative merits and disadvantages of each imaging modality.

Branched Thoraco-Abdominal Aortic Aneurysm Repair with Branch Access Through a Transapical Left Ventricular Approach

Branched thoracic aortic aneurysm repair requires arterial access from above the diaphragm in order to insert the visceral branches. This is routinely performed from the subclavian, axillary or carotid arteries and less commonly direct thoracic aorta puncture. The left ventricular apex is an alternative access route which is commonly used for percutaneous aortic valve replacement and rarely used for EVAR, FEVAR and TEVAR access. Here we describe two patients for which the left ventricular apex was the most suitable available access to the visceral branches during a branched thoracic aortic aneurysm repair. This access should be considered as an alternative approach if conventional arterial access is not available.

Evaluation of velocity-sensitized and acceleration-sensitized NCE-MRA for below-knee peripheral arterial disease

To evaluate the diagnostic performance of velocity‐ and acceleration‐sensitized noncontrast‐enhanced magnetic resonance angiography (NCE‐MRA) of the infrageniculate arteries using contrast‐enhanced MRA (CE‐MRA) as a reference standard.