Whitney J. Palmer

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Reduced-dose CT is not only effective in imaging patients for kidney stones, but it also lowers the overall radiation exposure for individuals who might need repeated imaging. But, the protocols aren’t implemented as frequently as they should be, experts say.

Journal of the American College of Radiology

a team of investigators from Yale University School of Medicine pointed out that use of the protocol falls far below the “as low as reasonably achievable” goal. In their findings, they outlined the efficacy of the reduced-dose protocol and the impact greater utilization could have.

“Increased adoption of reduced-dose CT protocols will decrease the overall radiation burden associated with kidney stone CT, which often requires repeat imaging in relatively young patients,” said the team led by Christopher Moore, M.D., emergency medicine professor and emergency ultrasound section chief.

According to the National Kidney Foundation, more than a half million patients present to the emergency department each year with kidney stone symptoms – and the incidence has increased in the last 40 years. Between the late 1970s and 2014, the prevalence has risen from 3.8 percent to 10 percent, respectively. Most patients are young, average age of 30 for men and 35 for women, making the need to control dose even greater.

Of the patients impacted by kidney stones, 85 percent undergo CT imaging, Moore’s team said, and the average number of scans is between 1.4 and 1.7 per kidney stone occurrence, adding to their cumulative radiation exposure.

To increase use of the reduced-dose protocol, the team created an intervention – Dose Optimization for Stone Evaluation (DOSE) – that combined continuing education, consultation, and protocol recommendations. This is the first national study to examine the use of reduced-dose CT on kidney imaging, the team said, and they tested DOSE in 192 facilities, totaling 422,039 kidney stone CT scans between 2015 and 2019.

The team split the centers into a group that implemented DOSE and a group that did not, and they sub-divided the intervention group into those that had participated in the intervention (25 facilities) and those that had not (71 institutions). They, then, tracked the dose-length product (DLP) every year, beginning in 2015.

Based on their analysis, they found that the DLP fell by 16 percent between 2015 and 2017 in facilities that used the intervention. Overall, the average reduction throughout all years of the study was 14 percent.

In addition, their results showed that facilities began using reduced-dose CT protocols more frequently throughout the study timeframe. Facilities in the DOSE intervention saw a more significant bump in their percentages of these lower-dose scans -- they rose from 22 percent in 2015 to 36 percent in 2019.

These findings show implementing reduced-dose CT protocols is a feasible option for kidney stone imaging in the long-term, the team said. But, providers must be conscientious about using it on a wider scale.

“It is the shared responsibility of medical users of radiation dose or radiation dose-based imaging tests, such as CT, to ensure use of as low as reasonably achievable radiation doses,” the team said. “This is particularly true for an indication, such as kidney stone CT, in which there is unequivocal evidence that reduced-dose CT can be employed without adverse effects.”

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New research suggests use of reduced-dose CT scans could be as effective and reduce the need for re-imaging. 

Reduced-Dose CT Scans Could Be Effective for Kidney Stone Imaging

New research from a team at the Amsterdam University Medical Center suggests clinicians could use low-dose CT scans performed during lung cancer screenings to predict risk of cardiovascular mortality.

 investigators detailed how implementing a deep learning algorithm that is fueled with information captured during a low-dose CT exam for lung cancer screening can offer valuable details about calcification in the heart and the aorta.

Using LDCT in this way is a two-for-one opportunity to screen patients for both potentially deadly conditions. The scan is used to detect lung cancer in high-risk individuals, including heavy smokers, but for those individuals, cardiovascular disease actually surpasses lung cancer as the leading cause of death. By picking up these areas of calcification that are linked to plaque build-up, the scan can give providers a strong predictor of heart attacks, stroke, and mortality from cardiovascular disease.

Given the recent recommendation update from the U.S Preventive Services Task Force that opened up LDCT lung cancer screening to high-risk individuals ages 50-to-80 who have at least a 20-pack year smoking history, it is possible that providers will be able to pick up on cardiovascular disease mortality risk in an even wider population of patients, the team said.

In the past, data pulled from CT images has been used in conjunction with other risk factors, such as cholesterol levels, blood pressure, and self-reported history of illness. But, for this study, the team, led by Bob D. de Vos, Ph.D., from Amsterdam University Medical Center and the Image Sciences Institute at the University Medical Center Utrecht, drew upon deep learning to create an automated method that can quickly predict five-year cardiovascular disease mortality without putting a heavier work burden on providers.

“We have shown that five-year cardiovascular disease mortality can be predicted for lung screening participants in less than half a second, using only site-specific calcium scores automatically derived from lung screening low-dose CT,” the team said. “Hence, the proposed image-based analysis could aid in identification of lung screening participants at risk for cardiovascular disease mortality, without relying on self-reported participant data.”

Low-dose CT (LDCT) isn’t just for lung cancer screening. Data gathered from the scans can also help predict a patient’s five-year risk of death from cardiovascular disease.

 investigators from The Netherlands detailed how implementing a deep learning algorithm that is fueled with information captured during a low-dose CT exam for lung cancer screening can offer valuable details about calcification in the heart and the aorta.

For the study, they pulled data from LDCT scans conducted between August 2002 and April 2004 on 4,451 participants with an average age of 61 who were part of the National Lung Screening Trial. Using those details, the team trained their deep learning method to quantify six types of vascular calcification: thoracic aorta calcification (TAC), aortic and mitral valve calcification, coronary artery calcification (CAC) of the left main, the left anterior descending, and the right coronary artery. After training, they tested their method on data gleaned from 1,113 participants.

The team compared the methods with semi-automatic baseline prediction using self-reported participant characteristics, such as age, smoking history, and history of illness. According to their analysis, the prediction model using calcium scores performed better than the baseline model.

Specifically, the prediction model that used calcium scores reached a C statistic of 0.74 while the baseline model that relied on only participant characteristics achieved 0.69. The model had the best results, they said, when all variables were combined – a 0.76 C statistic.

“The analysis shows we found predictors that are typically not described in a literature, possibly because we performed analysis in lung cancer screening participants we are already at high risk of cardiovascular disease from a history of heaving smoking and the presence of extensive arterial calcification,” de Vos explained.

The method works in two stages, he said, first using deep learning to pinpoint the amount and location of arterial calcification in the coronary arteries and aorta. The second stage relies on a more conventional statistical approach to mortality prediction and identifies features that are most predictive of five-year mortality.

Incorporating the deep learning method into lung cancer screening would be simple, de Vos said, because it requires no special equipment and does not tack on any exam time. And, the benefits to providers and patients could be immense.

“The method uses only image information, it is fully automatic, and it is fast. The method obtains calcium scores in a complete chest CT in less than half a second. This means that the method should be easy to implement to routine patient work ups and screening,” he said. “Lung screening studies show that heavy smokers die from cardiovascular disease as much as from lung cancer. But, we also see that some people with very high calcium scores survive, while others with low scores do suffer from major cardiac events.”

Their results point to a need for additional research that can more specifically point to calcifications that are dangerous. To date, they have developed several automatic scoring methods that can use varied types of data, but they are continuing on with development. Now, de Vos said, they are concentrating on creating a calcium-scoring method that can use low-quality data, such as data affected by cardiac motion, low image resolution, and high noise level, to detect arterial calcification.

“We developed a method, for example, that can detect coronary calcification even when the lesions are below the clinically used threshold,” he said. “This way, we hope to increase the reproducibility of calcium scoring and enable more accurate prediction.”

But, for now, he said, their work has shown that it is possible to achieve real-time mortality prediction with lung screening chest CT by using only data from automatic deep learning-quantified arterial calcium.

This study, "

Deep Learning–Quantified Calcium Scores for Automatic Cardiovascular Mortality Prediction at Lung Screening Low-Dose CT

A deep-learning algorithm could help clinicians identify patients at increased risk of death from cardiovascular disease within the next 5 years based on the presence of vascular calcification. 

CT Scans from Lung Cancer Screenings Can Help Predict Risk of Cardiovascular Mortality

 were more likely to experience the neurological complications, including bleeding in the brain and stroke, that come with the virus.

Based on CT and MRI images, investigators from the Perelman School of Medicine at the University of Pennsylvania determined that these chronic conditions could play a role in which patients are impacted by more than just the hallmark lung inflammation that comes with viral infection.

“COVID-19’s effects extend far beyond the chest,” said lead study author Colbey W. Freeman, M.D., chief resident in the Penn Medicine radiology department. “While complications in the brain are rare, they are an increasingly reported and potentially devastating consequence of COVID-19 infection.”

Freeman’s team will present their findings during this year’s Radiological Society of North America (RSNA) annual meeting. 

In an effort to better understand how COVID-19 impacts the body, they examined head CT and/or MRI images for patients positive for the virus who presented to the University of Pennsylvania health system from January 2020-April 2020.

A total of 81 of the 1,357 COVID-19-positive patients who were admitted underwent a brain scan prompted by either altered mental state or focal neurological deficits, including speech and vision problems.

Based on the team’s analysis, 18 patients – slightly over 20% – had findings that were considered critical, such as strokes, brain bleeds, or blocked blood vessels. And, of that group, at least half also had a pre-existing history of high blood pressure or type 2 diabetes.

“COVID-19 is associated with neurological manifestations, and hypertension and type 2 diabetes mellitus are common in individuals who develop these manifestations,” Freeman said. “These populations may be at higher risk for neurologic complications and should be monitored closely.”

The team also found that two-thirds of the patients who had critical findings were African American, indicating COVID-19 positive patients in that minority group should be monitored more closely. And, among the entire group of 18 with emergent findings, three died while in the hospital, the team said.

Although this study revealed a role for high blood pressure and type 2 diabetes in the neurological impact of the virus, investigators still do not know exactly what causes those complications.

The mechanisms could be multi-factorial, and the generally accepted belief is that infection-associated inflammation is responsible, they said. In this study, in particular, they reported blood markers for inflammation were high in patients who had critical results.

“When your body is in an inflammatory state, it produces all these molecules called cytokines to help recruit the immune system to perform its function,” Freeman said. “Unfortunately, if cytokines are over-produced, the immune response actually starts doing damage.”

Using data from this study, the team is also looking at the how frequently COVID-19-positive patients on extracorporeal membrane oxygenation (ECMO) – a pump system that circulates and replenishes oxygen in the blood – experience neurological complications. Many patients included in this study required ECMO during hospitalization.

Future plans include a larger prospective study to investigate delayed, long-term, and chronic neurologic manifestations that have not currently been identified, but that might manifest later.

Diabetes, Hypertension May Increase Risk of COVID-19 Brain Complications

About 20% of 81 positive patients experienced critical neurological complications; further, half had a pre-existing history of high blood pressure or type 2 diabetes.

Diabetes, Hypertension Linked to COVID-19-Related Neurological Complications

Conducting a contrast-enhanced cardiac MRI with a patient carries a very low risk of allergic reactions or other adverse events, but outcomes can vary based on various contrast agent characteristics, according to results of a new study.

In the study, investigators from the University Medical Center in Goettingen, Germany, focused on how a decision made by the European Medicines Agency (EMA) in 2017 affected patients undergoing this exam. Most contrast-enhanced cardiac MRIs use intravenous gadolinium-based contrast agents (GBCAs), and the EMA’s decision mandated the use of macrocyclic gadolinium contrast agent because it is less likely to accumulate in the body.

Typically, GBCAs are considered safe for this patient population, said the team led by Johannes Uhlig, MD, MPH, with adverse events being reported in 0.04 percent-to-2.2 percent of cases. But, there are questions around the impact of the likelihood that linear gadolinium will deposit in the body. In its decision, the EMA suspended linear gadolinium use except for liver imaging.

“Studies have demonstrated that the likelihood and extent of cerebral gadolinium depositions are increased after administration of linear GBCAs compared to macrocyclic GBCAs, although the clinical relevance of these depositions still needs to be determined,” he said.

To determine how the EMA decision affected the clinical impact of contrast-enhanced cardiac MRI, Uhlig’s team retrospectively reviewed MRI exams from 154,779 patients who were included in the European Society of Cardiovascular Radiology MRCT Registry from January 2013 to October 2019. Of the group, nearly 95 percent (145,855 patients) had a contrast-enhanced exam. Until 2017, 15.2 percent of exams used linear gadolinium, but that rate fell to less than 1 percent in 2018 and 2019.

Based on their analysis of patient outcomes, the team identified acute adverse events (AAEs) and classified them as mild, moderate, or severe. Overall, they discovered 556 AAEs among patients who had contrast-enhanced exams (0.38 percent), and only 47 were classified as severe or life-threatening. And, fewer AAEs were associated with macrocyclic GBCAs versus linear GBCAs (multivariable OR, 0.634, 95 percent CI: 0.452, 0.888, P=.008).

Among AAEs, the team said, allergic-like events were more common than physiologic ones, 71.58 percent and 28.42 percent, respectively, with the most common responses being wheezing and bronchospasms.

“Using a large-scale patient cohort from several European countries, our study demonstrates that the administration of GBCA for cardiac MRI is safe for the overwhelming majority of patients,” Uhlig said. “In particular, macrocyclic GBCAs exhibit a favorable acute safety profile, and should be considered for cardiac MRI examinations evaluating myocardial scarring, ischemia, cardiomyopathy, and myocarditis.”

But, GBCA administration was not responsible for all AAEs, he said. In fact, of the 8,924 cases that did not involve a contrast agent, there were 231 (2.59 percent) reported negative events. Most were related to anxiety and shortness of breath.

The team’s analysis also revealed more details about AAE incidence based on pharmacologic stressors, GBCA molecular structure, GBCA subtypes, and imaging indications, with the highest AAE incidence occurring in patients with known coronary artery disease. For instance, the team reported, patients who had stress cardiac MRIs were more likely to experience an AAE, and the highest rates occurred with the administration of dobutamine (1.78 percent) and regadenoson (1.26 percent). The lowest incidence appeared with the use of adenosine (0.53 percent). The longer half-life and different modes of action for regadenoson and dobutamine could be responsible for these differences, they said.

Additionally, the team also looked at outcomes based on GBCA subtypes. Overall, most AAEs occurred with patients who received gadoteridol (0.65 percent, 73 out of 11,161 patients). They also identified an increase among patients for whom a cardiac MRI was performed with gadobenate dimeglumine.

Ultimately, Uhlig’s team said, their findings point to the importance of pre-procedural assessments that can reveal any contraindications to MRI scanning and GBCA administration. Such an evaluation could provide insight into the likelihood of a GBCA-associated adverse event.

“Potentially vulnerable populations include those with orthostatic shortness of breath, prior adverse GBCA reactions, and terminal renal insufficiency,” Uhlig said.

Currently, there are no regulatory restriction on the use of linear GBCAs in the United States, but the U.S. Food & Drug Administration does advise providers to take gadolinium retention characteristics into consideration when selecting a GBCA for MRI scans.

Gadolinium-based Contrast Agents for Cardiac MRI: Use of Linear and Macrocyclic Agents with Associated Safety Profile from 154 779 European Patients

A recent study has found use of contrasting agents in cardiac MRIs carries a low risk for allergic reactions, vomiting, and other adverse events.