Generation of fluoroscopy-alike radiographs as alternative datasets for deep learning in interventional radiology.

In fluoroscopy-guided interventions (FGIs), obtaining large quantities of labelled data for deep learning (DL) can be difficult. Synthetic labelled data can serve as an alternative, generated via pseudo 2D projections of CT volumetric data. However, contrasted vessels have low visibility in simple 2D projections of contrasted CT data. To overcome this, we propose an alternative method to generate fluoroscopy-like radiographs from contrasted head CT Angiography (CTA) volumetric data. The technique involves segmentation of brain tissue, bone, and contrasted vessels from CTA volumetric data, followed by an algorithm to adjust HU values, and finally, a standard ray-based projection is applied to generate the 2D image. The resulting synthetic images were compared to clinical fluoroscopy images for perceptual similarity and subject contrast measurements. Good perceptual similarity was demonstrated on vessel-enhanced synthetic images as compared to the clinical fluoroscopic images. Statistical tests of equivalence show that enhanced synthetic and clinical images have statistically equivalent mean subject contrast within 25% bounds. Furthermore, validation experiments confirmed that the proposed method for generating synthetic images improved the performance of DL models in certain regression tasks, such as localizing anatomical landmarks in clinical fluoroscopy images. Through enhanced pseudo 2D projection of CTA volume data, synthetic images with similar features to real clinical fluoroscopic images can be generated. The use of synthetic images as an alternative source for DL datasets represents a potential solution to the application of DL in FGIs procedures.

Incomplete Third Nerve Palsy Due to a Carotid-Cavernous Fistula.

INTRODUCTION: The approach to oculomotor nerve palsies involves the exclusion of compressive, infective, inflammatory, or ischemic lesions. Dural arteriovenous fistulae, including carotid-cavernous fistulae (CCF), are known causes of third nerve palsy. However, diagnosis can sometimes be delayed or missed due to the various clinical presentations. CCF remains a rare but treatable cause of third nerve palsy. CASE REPORT: A 63-year-old Chinese female presented to our unit with gradual onset horizontal diplopia. Clinical examination revealed a partial left oculomotor nerve palsy without congestive eye symptoms. A cerebral angiogram revealed a left indirect CCF supplied by the inferolateral trunk of the left internal carotid artery. She underwent successful transvenous embolization. She improved postprocedure and was discharged well on day 10 of her admission. She was reviewed at 2 months follow-up and had recovered completely. CONCLUSION: Our case is a classic description of a CCF with posterior drainage into the inferior petrosal sinus. We hope this case and a review of the literature can serve as a reminder to clinicians of the varied presentations of CCF. We believe this case adds value to the clinicians in contributing to their diagnostic process and to our interventional colleagues in highlighting a case with a successful postembolization outcome.

A Tale of Two Organ Systems: Imaging Review of Diseases Affecting the Thoracic and Neurological Systems. Part 2.

In an era of rapidly expanding knowledge and sub-specialization, it is becoming increasingly common to focus on one organ system. However, the human body is intimately linked, and disease processes affecting one region of the body not uncommonly affect the other organ systems as well. Understanding diseases from a macroscopic perspective, rather than a narrow vantage point, enables efficient and accurate diagnosis. This tenet holds true for diseases affecting both the thoracic and neurologic systems; in isolation, the radiologic appearance of disease in one organ system may be nonspecific, but viewing the pathophysiologic process in both organ systems may markedly narrow the differential considerations, and potentially lead to a definitive diagnosis. In this article, we discuss a variety of disease entities known to affect both the thoracic and neurological systems, either manifesting simultaneously or at different periods of time. Some of these conditions may show neither thoracic nor neurological manifestations. These diseases have been systematically classified into infectious, immune-mediated/ inflammatory, vascular, syndromic/ hereditary and neoplastic disorders. The underlying pathophysiological mechanisms linking both regions and radiologic appearances in both organ systems are discussed. When appropriate, brief clinical and diagnostic information is provided. Ultimately, accurate diagnosis will lead to expedited triage and prompt institution of potentially life-saving treatment for these groups of complex disorders.

Interventional Radiology Procedures for COVID-19 Patients: How we Do it.

With astonishing speed, COVID-19 has become a global pandemic. As it is uncertain when the pandemic will be controlled, it is crucial for procedurists of all stripes to be familiar and confident in performing procedures for COVID-19 patients to prevent intra-hospital infection. In this article, we will detail our approach on how to perform interventional procedures for COVID-19 patients at the bedside in the isolation room and with the patient transferred to the interventional radiology centre. These workflows have been developed in conjunction with multiple other stakeholders within our hospital, drawing from valuable lessons we have learnt from the SARS outbreak of 2003.