Evaluation and Utilization of Flow Artifacts at CT.

Flow artifacts are commonly encountered at contrast-enhanced CT and can be difficult to discern from true pathologic conditions. Therefore, radiologists must be comfortable distinguishing flow artifacts from true pathologic conditions. This is of particular importance when evaluating the pulmonary arteries and aorta, as a flow artifact may be mistaken for a pulmonary embolism or dissection flap. Understanding the mechanics of flow artifacts and how these artifacts are created can help radiologists in several ways. First, this knowledge can help radiologists appreciate how the imaging characteristics of flow artifacts differ from true pathologic conditions. This information can also help radiologists better recognize the clinical conditions that predispose patients to flow artifacts, such as pneumonia, chronic lung damage, and altered cardiac output. By understanding when flow artifacts may be confounding the interpretation of an examination, radiologists can then know when to pursue other troubleshooting methods to assist with the diagnosis. In these circumstances, the radiologist can consider several troubleshooting methods, including adjusting the imaging protocols, recommending when additional imaging may be helpful, and suggesting which imaging study would be the most beneficial. Finally, flow artifacts can also be used as a diagnostic tool when evaluating the vascular anatomy, examples of which include the characterization of shunts, venous collaterals, intimomedial flaps, and alternative patterns of blood flow, as seen in extracorporeal membrane oxygenation circuits. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Subclavian Artery: Anatomic Review and Imaging Evaluation of Abnormalities.

The subclavian artery is an important structure that may be overlooked at CT of the chest and neck, in part because of its anatomic location at the periphery of the field of view but also because the clinical indication for CT examinations infrequently directs attention specifically to evaluation of the subclavian artery. As with all arteries, the subclavian artery has the potential to be involved in a variety of abnormalities, including pseudoaneurysms, dissections, stenosis or thrombosis, and vasculopathies. In addition, the subclavian artery can be secondarily involved as a collateral pathway because of an abnormality elsewhere. The subclavian artery may also be involved in surgical procedures to supply blood to other sites in the body or as an arterial access site. In these cases, recognizing the postsurgical appearance of the subclavian artery has become increasingly complex because of the use of the artery in an increasing number of procedures. Recognizing expected postoperative changes remains important to avoid mistaking them for abnormalities. The authors describe the imaging appearance of the normal anatomy of the subclavian artery and its anatomic variants, related abnormalities, and important postsurgical considerations. ©RSNA, 2022.

Impact of Pretransplantation CT on Liver Donation in Potential Deceased Organ Donors.

BACKGROUND: Computed tomography (CT) is routinely used to determine the suitability of potential living donor liver transplants, providing important information about liver size, vascular anatomy, and the presence of other diseases that would preclude it from safe donation. CT is not routinely used, however, when evaluating eligible deceased organ donors after brain death, a group which comprises most orthotopic liver transplants. After the installation of a CT scanner at a local procurement facility, CTs have been performed on potential deceased organ donors and used, in conjunction with other evaluative protocols, to help direct donation decisions and assist in procurement procedures. STUDY DESIGN: A retrospective analysis of data from 373 cases spanning 5 years was systematically collected and analyzed, including information pertaining to patient's medical histories, biopsy results, operative findings, and CT results. RESULTS: CT findings directly impacted the directive decision-making process in 29% of cases in this patient cohort, likely an underestimate, and reliably evaluated important factors including variant vascular anatomy and the presence and severity of hepatic steatosis and cirrhosis. CONCLUSION: Overall, this study suggests that CT has the potential to play a significant role in procurement procedures and the directive decision-making process, thereby improving the efficiency and accuracy by which potential deceased organ donors are evaluated.

Tumor Staging of Lung Cancer: Essential Concepts for the Radiologist.

Several important modifications have been proposed for the tumor (T) descriptor for lung cancers. New size cutoffs have been determined and there are new T descriptors for adenocarcinoma in situ, minimally invasive adenocarcinoma, and part-solid adenocarcinomas with a solid component > 0.5 cm to 3 cm (T1a, T1b, T1c). There are also recommendations for multifocal adenocarcinoma, which are classified by the lesion with the highest level T descriptor, and the number of lesions is indicated. Knowledge of these changes is important in the appropriate clinical staging of patients with lung cancer.