Robert J. McDonald’s research while affiliated with Mayo Clinic - Rochester and other places

IV contrast media improve the diagnostic power of radiology examinations. These media include gadolinium-based contrast media and iron-oxide nanoparticles for MRI, iodinated contrast material for CT, microbubbles for ultrasound, and radiopharmaceuticals for nuclear medicine. As for all medications, contrast media carry risks, which may be heightened in the conditions of pregnancy and lactation. Radiologists must understand the potential risks from contrast media exposure to the pregnant patient, fetus, and nursing infant, as well as understand these administrations' impact on examinations' clinical utility. This article reviews the available literature on these media, along with key regulatory bodies' and professional societies' current recommendations for their use, in the settings of pregnancy and lactation. This knowledge should help radiologists make well-reasoned risk-benefit analyses regarding contrast media administration and provide informed consent discussions with pregnant and nursing patients in whom contrast media administration is being considered. This information and analysis can also assist facilities in designing policies and standard operating procedures of possible clinical benefit to the pregnant patient, fetus, or nursing infant, balancing contrast media exposure considerations versus augmented diagnostic capabilities.

Extravasation of iodinated contrast material (ICM) is an uncommon complication (0.1%-1.2%) following intravenous injection for computed tomography exams and other procedures. Most cases of contrast extravasation are mild and resolve without treatment. Alternative injections sites are occasionally necessary among patients with difficult vascular access and are at increased risk of contrast extravasation and subsequent complications compared to the antecubital fossa. We describe a rare case of airway compromise necessitating intubation following iodinated contrast extravasation from an external jugular IV line. Additional care and monitoring must be performed during and after injection of contrast into these higher-risk vascular access sites.

Iodinated contrast material (ICM) has revolutionized the field of diagnostic radiology through improvements in diagnostic performance and expansion in clinical indications for radiographic and CT examinations. Historically, nephrotoxicity was a feared complication of ICM use, thought to be associated with a significant risk of morbidity and mortality. Such fears often precluded use of ICM in imaging evaluations, commonly at the expense of diagnostic performance and timely diagnosis. Over the past 20 years, the nephrotoxic risk of ICM has become a topic of debate, as more recent evidence from higher-quality studies now suggest that many cases of what was considered contrast-induced acute kidney injury (CI-AKI) were likely cases of mistaken causal attribution; most of these cases represented either acute kidney injury (AKI) caused by any of myriad other known factors that can adversely affect renal function and were coincidentally present at the time of contrast media exposure (contrast-associated AKI (CA-AKI)) or a manifestation of the normal variation in renal function that increases with worsening renal function. This review discusses the current state of knowledge on CI-AKI and CA-AKI including the incidence, risk factors, outcomes, and prophylactic strategies in the identification and management of these clinical conditions.

Purpose Dental amalgam contains mercury and is commonly used in dental restorations. The impact of MRI on mercury excretion from dental amalgam is not well understood across clinical field strengths, especially 7T. We investigated the effects of MRI exposure on mercury excretion using fresh, lab‐created dental amalgam restorations and in extracted teeth with old, pre‐existing restorations. Methods Donated, unfilled human teeth (n = 120) were restored with amalgam before being stored in saline, artificial saliva, or a dry box prior to MRI scanning. The teeth were placed in individual tubes of fresh artificial saliva and scanned at 1.5T, 3T, or 7T or left unscanned as controls. Mercury concentrations were measured 24–30 h later. Donated teeth with pre‐existing restorations (n = 40) were stored in artificial saliva, scanned at 7T or left unscanned as controls, and mercury concentration tested. Results For teeth extracted and restored in a laboratory, no significant difference was found (F = 2.42, P = 0.072) between mean mercury concentrations of unscanned teeth (13.72 μg/L) and teeth scanned at 1.5T (10.88 μg/L), 3T (12.65 μg/L), or 7T (8.88 μg/L). For teeth extracted with previously placed restorations, no significant difference (P = 0.288) was found between unscanned controls (4.28 μg/L) and teeth scanned at 7T (6.63 μg/L). Conclusion MRI of dental amalgam does not significantly increase mercury excretion at 1.5T, 3T, or 7T compared to unscanned teeth. This holds true for controlled laboratory restorations as well as for those placed and lived with prior to extraction and scanning, demonstrating no added risk to the clinical patient or research subject.

Objective: To examine follow-up care in patients with a history of acute allergic-like reaction to iodinated contrast material (ICM), including subsequent imaging management, allergy consultation, and repeat ICM exposure and reactions. Methods: All patients who had a moderate or severe acute allergic-like reaction to ICM following contrast-enhanced (CE)CT exam from June 1, 2009 -January 1, 2022 at our institution were included. Chart review was performed to determine 1) whether subsequent imaging was not performed or altered in these patients, 2) whether the patient underwent a subsequent CECT exam, and 3) whether the patient had an allergist consultation. Results: A total of 251 patients were identified. One-third of patients (90/251, 36%) had at least one change to their subsequent imaging management due to their reaction, including performing an unenhanced CT (62/251, 25%) or MRI (22/251, 8.8%) instead of a CECT, or not performing a CECT when otherwise clinically indicated (20/251, 8.0%). Patients with a prior severe reaction were more likely to have a change in management than patients with a prior moderate reaction (Severe: 22/32 (69%) vs. Moderate: 68/219 (31%), p<.0001). Only 17 patients (6.8%) had an allergy consult for their ICM reaction. A total of 90 patients underwent 274 subsequent CECT exams. Repeat allergic-like reactions were observed in one quarter of patients (24/90, 27%) and a tenth of CECT exams (29/274, 11%). Discussion: One-third of patients with a history of a moderate or severe allergic-like reaction to ICM had their subsequent imaging care modified due to their reaction.

Covid-19 has been front and center in the global landscape since the beginning of 2020. In response, the scientific field has dedicated enormous amounts of resources to researching the virus and its effects. The number of times Covid-19 publications are being cited throughout the literature appears remarkably high but has not been directly compared to non-Covid-19 papers in the same journals over an extended period. In our study, we use Clarivate’s Web of Science—Science Citation Index Expanded™ database to identify Covid-19 papers published in 24 major scientific journals over a period of 24 months from January 1, 2020 to December 31, 2021. We conduct our search using keywords “Covid-19”, “coronavirus”, and “sars-cov-2” to locate publications with these words in the title. We then quantify the number of citations these papers have received and compare rates to non-Covid-19 papers in the same journals over the same timeframe. We find that, across 24 open-access and subscription-based scientific journals, Covid-19 papers published in the past 2 years currently have a median citation rate of 120.79 compared to 21.63 for non-Covid-19 papers. When negative binomial regression is used to minimize the influence of other variables such as article number variation and field of research, Covid-19 papers have still experienced more than 80% increase in citations relative to non-Covid-19 papers. These novel findings demonstrate that Covid-19 papers are being cited at remarkably higher rates than non-Covid-19 articles contained within the same journals. This suggests that journal impact factor, which is a product of the number of citations that recently published articles receive, will likely be drastically influenced by the number of Covid-19 papers that a journal has included within its pages in the previous years.