Bill S. Majdalany

ACR Appropriateness Criteria® Imaging for Transcatheter Aortic Valve Replacement

Although aortic valve replacement is the definitive therapy for severe aortic stenosis, almost half of patients with severe aortic stenosis are unable to undergo conventional aortic valve replacement because of advanced age, comorbidities, or prohibitive surgical risk. Treatment options have been recently expanded with the introduction of catheter-based implantation of a bioprosthetic aortic valve, referred to as transcatheter aortic valve replacement. Because this procedure is characterized by lack of exposure of the operative field, image guidance plays a critical role in preprocedural planning. This guideline document evaluates several preintervention imaging examinations that focus on both imaging at the aortic valve plane and planning in the supravalvular aorta and iliofemoral system. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria® on Upper Gastrointestinal Bleeding

Upper gastrointestinal bleeding is a significant cause of morbidity and mortality, affecting 36 to 48 per 100,000 persons annually. Aggressive resuscitation and upper endoscopy remain the cornerstones of therapy; however, in cases refractory to endoscopic diagnosis and management, radiology plays an increasingly vital and often lifesaving role, thanks to improvements in both imaging and interventional techniques. The various etiologies of upper gastrointestinal bleeding are discussed along with specific management recommendations based on an extensive literature review of current radiographic methods.

ACR Appropriateness Criteria Imaging in the Diagnosis of Thoracic Outlet Syndrome

Thoracic outlet syndrome is a clinical entity characterized by compression of the neurovascular bundle, and may be associated with additional findings such as venous thrombosis, arterial stenosis, or neurologic symptoms. The goal of imaging is to localize the site of compression, the compressing structure, and the compressed organ or vessel, while excluding common mimics. A literature review is provided of current indications for diagnostic imaging, with discussion of potential limitations and benefits of the respective modalities. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. In this document, we provided guidelines for use of various imaging modalities for assessment of thoracic outlet syndrome.

Ablation techniques for primary and metastatic liver tumors

Ablative treatment methods have emerged as safe and effective therapies for patients with primary and secondary liver tumors who are not surgical candidates at the time of diagnosis. This article reviews the current literature and describes the techniques, complications and results for radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation.

Improved quantitative 90Y bremsstrahlung SPECT/CT reconstruction with Monte Carlo scatter modeling

Purpose: In 90Y microsphere radioembolization (RE), accurate post‐therapy imaging‐based dosimetry is important for establishing absorbed dose versus outcome relationships for developing future treatment planning strategies. Additionally, accurately assessing microsphere distributions is important because of concerns for unexpected activity deposition outside the liver. Quantitative 90Y imaging by either SPECT or PET is challenging. In 90Y SPECT model based methods are necessary for scatter correction because energy window‐based methods are not feasible with the continuous bremsstrahlung energy spectrum. The objective of this work was to implement and evaluate a scatter estimation method for accurate 90Y bremsstrahlung SPECT/CT imaging. Methods: Since a fully Monte Carlo (MC) approach to 90Y SPECT reconstruction is computationally very demanding, in the present study the scatter estimate generated by a MC simulator was combined with an analytical projector in the 3D OS‐EM reconstruction model. A single window (105 to 195‐keV) was used for both the acquisition and the projector modeling. A liver/lung torso phantom with intrahepatic lesions and low‐uptake extrahepatic objects was imaged to evaluate SPECT/CT reconstruction without and with scatter correction. Clinical application was demonstrated by applying the reconstruction approach to five patients treated with RE to determine lesion and normal liver activity concentrations using a (liver) relative calibration. Results: There was convergence of the scatter estimate after just two updates, greatly reducing computational requirements. In the phantom study, compared with reconstruction without scatter correction, with MC scatter modeling there was substantial improvement in activity recovery in intrahepatic lesions (from > 55% to > 86%), normal liver (from 113% to 104%), and lungs (from 227% to 104%) with only a small degradation in noise (13% vs. 17%). Similarly, with scatter modeling contrast improved substantially both visually and in terms of a detectability index, which was especially relevant for the low uptake extrahepatic objects. The trends observed for the phantom were also seen in the patient studies where lesion activity concentrations and lesion‐to‐liver concentration ratios were lower for SPECT without scatter correction compared with reconstruction with just two MC scatter updates: in eleven lesions the mean uptake was 4.9 vs. 7.1 MBq/mL (P = 0.0547), the mean normal liver uptake was 1.6 vs. 1.5 MBq/mL (P = 0.056) and the mean lesion‐to‐liver uptake ratio was 2.7 vs. 4.3 (P = 0.0402) for reconstruction without and with scatter correction respectively. Conclusions: Quantitative accuracy of 90Y bremsstrahlung imaging can be substantially improved with MC scatter modeling without significant degradation in image noise or intensive computational requirements.

Fluoroscopic Targeting of Wallstents and Amplatzer Vascular Plugs in Sharp Recanalization of Chronic Venous Occlusions

Introduction/PurposeSharp recanalization of chronic venous occlusions is usually performed with targeting of wire-capture devices like loop snares or balloons. We describe sharp recanalization of chronic venous occlusions using self-expanding stents and vascular plugs.Material and MethodsWe retrospectively reviewed all sharp venous recanalization procedures performed over an 11-month period and found Wallstent and Amplatzer vascular plug (AVP) targeting was performed in 16 patients. Patient demographics, occlusion site, targeting device, technical success of the targeting, and overall procedural success were recorded.ResultsTechnical success was achieved in twelve (86%) Wallstent and two (67%) AVP deployments. Procedural success was achieved in 15 (94%). Three minor complications occurred.ConclusionWallstent and AVP targeting may be a useful technique when performing sharp recanalization for chronic venous occlusions. These devices expand the target space and present the same cross section viewed from any angle and can directly capture and extract the wire, features helpful in regions with crowded vascular anatomy.

Radiofrequency Wire Recanalization of Chronically Thrombosed TIPS

Radiofrequency (RF) guide wires have been applied to cardiac interventions, recanalization of central venous thromboses, and to cross biliary occlusions. Herein, the use of a RF wire technique to revise chronically occluded transjugular intrahepatic portosystemic shunts (TIPS) is described. In both cases, conventional TIPS revision techniques failed to revise the chronically thrombosed TIPS. RF wire recanalization was successfully performed through each of the chronically thrombosed TIPS, demonstrating initial safety and feasibility in this application.

ACR Appropriateness Criteria® Pulsatile Abdominal Mass Suspected Abdominal Aortic Aneurysm

Clinical palpation of a pulsating abdominal mass alerts the clinician to the presence of a possible abdominal aortic aneurysm (AAA). Imaging studies are important in diagnosing and categorizing the extent of the aneurysm and may aid in treatment planning. The consensus of the literature supports the use of ultrasound as the initial screening test in patients with suspected AAA. Population-based ultrasound screening studies have been recommended and have proved effective for male patients > 65 years of age. For diagnosis and pre-intervention evaluation, either multidetector CT or CT angiography is the optimal choice for detailed characterization of the aneurysm. MR angiography may be substituted if CT cannot be performed (for example, because the patient is allergic to iodinated contrast material). Invasive angiography has little role in the diagnosis of AAA and PET and CT remain experimental in patients with suspected aneurysms. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Abdominal Aortic Aneurysm: Interventional Planning and Follow-Up.

Abdominal aortic aneurysms (AAAs) are a relatively common vascular problem that can be treated with either open, surgical repair or endovascular aortic aneurysm repair (EVAR). Both approaches to AAA repair require dedicated preoperative imaging to minimize adverse outcomes. After EVAR, cross-sectional imaging has an integral role in confirming the successful treatment of the AAA and early detection of complications related to EVAR. CT angiography is the primary imaging modality for both preoperative planning and follow-up after repair. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Chylothorax Treatment Planning

Chylothorax is an uncommon but serious medical condition, which arises when intestinal lymphatic fluid leaks into the pleural space. Treatment strategies depend on the daily output and underlying etiology, which may be due to direct injury to lymphatic vessels or a nontraumatic disorder. Chest radiographs confirm the presence of pleural fluid and lateralize the process. In the setting of direct injury, lymphangiography can often be both diagnostic and facilitate a minimally invasive attempt at therapy. CT and MRI in this setting may be appropriate for cases when lymphangiography is not diagnostic. When the etiology is nontraumatic or unknown, CT or MRI can narrow the differential diagnosis, and lymphangiography is useful if a minimally invasive approach to treatment is desired. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.