What’s new in Cardiothoracic Imaging – May 2021

8 months ago

 

Prevalence of Abnormal Coronary Findings on Coronary Computed Tomography Angiography Among Young Adults Presenting With Chest Pain 

Jeremy R. Burt, MD, Matthew Cody O’Dell, MD, Basel Yacoub, MD, Jordan Chamberlin, BS, Jeffrey Waltz, MD, Charlotte Wallace, MD, Madison Kocher, MD, Michael Sacerdote, MD, Antonio Gonzalez, MD, Nicholas Feranec, MD, Manuel Hernandez, MD, Ali Agha, MD, and Bo Liu, MD 

Journal of Thoracic Imaging; Vol 36, Number 2, March 2021 

A group of researchers from MUSC, UT-Houston, AdventHealth, and Baptist Hospital of Miami, FL sought to investigate the role of abnormal imaging findings on coronary computed tomography angiography (CCTA) among patients aged 18-30 years old presenting with chest pain.  Roughly half the time a young adult presents to an emergency room with chest pain, they are given a nonspecific diagnosis usually due to lack of risk factors.  This study in particular examined atheroscleroric coronary artery disease, myocardial bridging (MB), and anatomic coronary anomalies (CA).  884 patients were included in the study if a CCTA was performed for a chief complaint of chest pain between ages 18-30 years old.  Exclusion criteria included: known congenital heart disease, kawasaki’s disease, history of cardiac surgery, pregnancy, or if information was missing from the medical chart.  CCTAs were obtained using either a Siemens or Philips 128 row scanner, with either 80-100 cc’s of iodinated contrast at 3-7 cc/hr injection.  Coronary calcium score scan parameters included: 120 kVp, 0.28 sec rotation time, 128 x 0.6 mm collimation.  CCTA scan parameters included: 100 or 120 kVp, 0.28 sec rotation time, and 128 x 0.6 mm collimation, and ECG triggered dose modulation.  CCTAs were read by one of two experienced readers, then a second review by one of five cardiac fellowship trained readers. If atherosclerotic disease was detected, it was characterized as stenosed or non-stenosed, graded degree of luminal narrowing according to CAD-RADS, and as calcified or noncalcified.  Coronary anomalies were characterized as potentially obstructive (shunting, ischemia, or sudden cardiac death anomalies) or nonobstructive.   

Of the 884 patients included, 356 women and 528 men, with median ages 27 for women and 28 for men. No evidence of hypertension upon presentation or in medical history.  Average BMI for both groups was considered obese (women 34, men 31). 22.1% of the 884 scans were considered as abnormal.  Coronary anomalies were more common in men than women (25.2% vs 17.4%.  Myocardial bridging was the most common abnormality overall, present in 17.3% of patients.  Atherosclerotic CAD was present in 4.4% of cases, and CA in 1.5% of cases. 1.1% of cases had more than one abnormality with frequency of abnormalities found to be significantly different between men and women (P <0.05).  2.8% of patients had coronary artery stenosis on CCTA, more common in atherosclerotic disease than MB (35.9% vs 5.2%).  Men were more commonly to have stenosis than women (4.1% vs 1.1%).  Left anterior descending artery was most commonly affected by stenosis (19 patients); followed by the right coronary artery (2 patients), and left circumflex artery (1 patient).  Overall, most degrees of stenosis according to CAD-RAD were minimal or mild; with 4 pts having moderate stenosis, and 3 pts with severe stenosis.  Of the risk factors for atherosclerotic CAD, age was significantly associated, with no atherosclerotic disease at 27, but at 29 it was present.   

Overall, given the lower prevalence of pathology in younger patients presenting with chest pain, discretion should be utilized prior to performing ionizing radiation studies. Although, in patients with significant cardiovascular risk factors, risk of radiation should not be a limiting factor.   Limitations for this study include: retrospective nature of study participants who presented for chest pain, inability to calculate HEART or TIMI score due to incomplete documentation in the medical record, and likely higher than normal prevalence of coronary anomalies due to presenting chest pain symptomatology. Page Break 

 

Real-World Lung Cancer CT Screening Performance, Smoking Behavior, and Adherence to Recommendations: Lung-RADS Category and Smoking Status Predict Adherence 

Eduardo J. Mortani Barbosa, Jr., MD, Rochelle Yang, BA, Michelle Hershman, MD 

American Journal of Roentgenology;  216:919–926 

Researchers from the University of Pennsylvania sought to investigate the role of low dose CT lung cancer screening (LDCT LCS) performance and factors predictive of adherence to LCS recommendations. The US National Lung Screening Trial and the Dutch-Belgian Lung Cancer Screening Trial have shown a significant reduction in mortality with lung cancer screening patients.  This particular article was a 5 year retrospective where patients who underwent multiple (2+) LDCT LCS were included.  Exclusion criteria included treatment for any cancer other than nonmelanoma skin cancers or carcinoma in situ within the past 5 years, or any diagnostic chest CT in the past 12 months.  Images were not directly reviewed for this study, and evaluation relied upon dictated reports and the medical record. Imaging protocols varied but the effective dose for all studies was 1.5 mSv.  Using the dictated reports and EMR, patients were classified via the Lung-RADS v1.0 categories: 1 (no suspicious findings) and 2 (nodules with extremely low risk of malignancy) were considered negative examinations; and positive screening examinations included categories 3, 4A, 4B, and 4x.  Initially, 1334 patients were evaluated for the study, and after the exclusion criteria were applied, there were a total of 260 patients included.  Outside of imaging findings, patient demographics, smoking history, incidental findings, outcomes (cancer diagnosis or changes in smoking behavior) and adherence with screening recommendations were included in the analysis.  Performance metrics for the LCS program included sensitivity, specificity, positive predictive value, and negative predictive value.  Adherence was determined to be exam performed within 1 month of the expected date of follow up, or within 3 months if PET/CT or biopsy was recommended.   

As far as the results show, 117 of the 260 were former smokers.  143 patients were current smokers with 114 continuing to smoke over the course of the study.  29 patients quit before the last round of LDCT LCS.  7 patients were former smokers who started again after the baseline study and before the last recorded LCDT LCS.  After the final round of LDCT LCS, the current smoking group included 121 patients, and the former included 139 patients.  Lung nodule total number ranged from 0-50, with varying size from 0-22 mm.  Solid nodules were the most common subtype with 62%.  The remaining subtype percentages are as follows: no nodules 33%, ground glass nodules 4%, and subsolid nodules 1%.  Right upper lobe nodules were the most common at 23%.  Positive screening exams (Lung-RADS 3, 4A, 4B, and 4X) included 16.5% of patients (43/260).  Primary lung cancer was diagnosed in 3/260 patients. 6/16 patients in categories 4 underwent resection or biopsy with lung cancer being pathologically confirmed in 3 cases.  All cancers were detected in the second round of screening.  The 10 patients that underwent resection/biopsy without cancer diagnosis had benign pathology.   

Mean follow up length for negative scans 884 days, with adherence rate of 43%.  Statistical analysis showed that the 2 factors that increased adherence was the Lung-RADS category and smoking status.  Adherence rate increased with increased progressively depending on Lung-RADS criteria was higher (p < 0.001); i.e. category 4 was higher than 3, etc.  Positive screening exams had a higher adherence rate than negative exams (65.1% vs 41.2%, p <0.002).  Adherence rate was increased for former smokers compared to current smokers (50.0% vs 36.2%, p <0.001).   

In this real-world study, the rate of positive examinations (16.5%) was higher than expected compared to the Lung-RADS expectation (9%); however most positive exams were confirmed as not lung cancers.  This study showed high sensitivity and negative predictive value, but moderate specificity, and very low positive predictive value.  Ultimately, this study shows important demographics who should be targeted to ensure follow up however there are limitations.  This is a single center study and populations in Philadelphia may not be extrapolated across the US and world.  Additionally, cultural and socioeconomic factors play an important role in these studies which may be skewed by the study taking place in a northeast US city. A multifactorial approach between radiologists and primary physicians should be encouraged to increase education among patients that LDCT LCS is important for mitigating future risk of lung cancer development.   

 

Frequency and Reliability of the Reversed Halo Sign in Patients With Septic Pulmonary Embolism Due to IV Substance Use Disorder 

Renata R. Almeida, Edson Marchiori, Efren J. Flores 

American Journal of Roentgenology 2020; 214:59–67 

Researchers from Harvard University and Federal University of Rio De Janeiro sought to investigate the utility of the “reverse halo” sign in patients with septic pulmonary emboli due to intravenous drug use. The “reverse halo” sign is defined as a focal rounded area of central ground glass opacity surrounded by a ring of focal consolidation.  This sign has been associated with multiple infectious and noninfectious etiologies, such as organizing pneumonia, tuberculosis, and fungal infections. The morphology of the halo can be important to help differentiate infectious vs noninfectious etiologies, as described in the literature.  In regards to emboli, the reverse halo sign is used to refer to pulmonary infarct due to emboli.  This was a retrospective study that reviewed 15,000+ examinations through a radiology database, which through different search criterias, 78 chest CTs from 64 patients were identified that associated drug abuse and septic emboli.  Review of the medical record for these patients was completed to find acceptable documentation regarding IV drug use, positive blood cultures, or response of pulmonary findings to an antibiotic regimen to be included within the study cohort.  CT examinations were performed with both GE and Siemens scanners, 1.5-1.25 mm slice thickness, and 1.5 pitch.  60% of scans received iodinated contrast, 40% were without.  Inpatient and outpatient examinations for each patient were reviewed by thoracic trained radiologists.  Each study was assessed for the reverse halo sign and considered present if 2 radiologists agreed that it was present in at least 1 study for the patient.  Reverse halo sign frequency, contour, shape, location, and presence of central reticulations or low attenuation areas were assessed, as well as evolution changes on follow up examinations.  SPSS 2015 statistical software was used to perform all analysis. 

Final cohort included 62 patients (54.8% women), who underwent 203 total examinations between inpatient and outpatient follow ups.  Average number of chest CTs per patient was 3.3, +/- 2.3 scans. All patients underwent echocardiography, and 63% were found to have valve vegetations. 91.9% of patients had positive blood cultures.  Lung nodules had 100% prevalence on scans reviewed, 91.9% of patients had cavitations, and 79% had pleural effusions.  Reverse halo sign was seen in 59.7% of patients, with a mean of 2.1 +/- 1.7; 46.7% of patients had more than 1 sign.  Most halo signs were seen in the periphery without lobar or shape preferences.  Central hypoattenuation was more common than central reticulations (65.4% vs 34.6%).  On follow up scans, the halo sign was characterized for evolution; showing cavitation 37.2% of the time, and consolidation 30.8% of the time.  12.8% of the time, the halo was seen to decrease in size without development of consolidation or cavitation.  Resolution was seen in 62.8% of patients at an average time of 84.9 days +/- 45.9 after the initial scan positive for reverse halo sign.   

Overall, the reverse halo sign was shown to be associated with septic emboli from IVDU; with more than half of patients within the cohort having the imaging findings.  This study suggests that the reverse halo sign is related to the healing process of pulmonary infarcts caused by septic PE.  This study did have a small sample size which is a limitation, however prior articles have shown that septic PE is associated with the reverse halo sign more often than traditional PE.  The initial results from this study are interesting and more research could be helpful in determining if this would be a good imaging biomarker for differentiating septic PE from other causes of PE.  Additional limitations for this study include likely under-reporting of patients with suspected IVDU and selection of patients with more severe manifestations which required imaging studies for clinical management. 

 

Can Chest CT Features Distinguish Patients With Negative From Those With Positive Initial RT-PCR Results for Coronavirus Disease (COVID-19)? 

Dandan Chen, Xinqing Jiang, Yong Hong, Zhihui Wen, Shuquan Wei, Guangming Peng, Xinhua Wei 

American Journal of Roentgenology, Issue 216, January 2021 

Researchers from Guangzhou First People’s Hospital in China investigated if there are any features on chest CT that can help distinguish patients that may have false negative PCR COVID-19 tests from patients that are initially positive. PCR tests are not perfect and a variety of reasons can lead to false negatives such as reagent issues, technique, or inadequate specimens. Chest CT was found early in the pandemic to be more sensitive for detection of findings that would raise concern for COVID-19 in the incubation period, prior to the virus being detectable via PCR. 

This study was done retrospectively and 21 patients were identified between January and February 2020 who eventually tested positive with PCR for COVID 19.  7 of these patients had initial negative PCR results, however tested positive with PCR 2 days later. Chest CT was performed supine with maximum inspiration. Siemens Somatom, Siemens Somatom emotions scanner, GE Optima, and Phillips Brilliance scanners were used.  Slice thickness varied from 1-2 mm, 120 kV tube voltage was used, tube current exposure time product was 100-200 mAs for each scanner except for GE Optima which was 200-300 mAs.  Two thoracic trained radiologists were blinded to clinical data and consensus was reached by the two radiologists.  fIf there was disagreement, a third radiologist evaluated the case as the final decision.  Imaging characteristics evaluated distribution of findings, attenuation (ground glass, consolidative), air bronchogram presence, vascular enlargement, interlobular septal thickening, mediastinal lymphadenopathy, pleural effusion, and pulmonary fibrosis. SPSS software was used for statistical analysis. 

21 patients, 9 men and 12 women, were included in the study with ages ranging from 26-90 years old with an average age of 49.7 years.  19/21 (90%) patients had exposure to a person with COVID-19, or had recently been to Wuhan.  Distribution of imaging findings on CT showed the wide majority of patients had bilateral findings (71%), while isolated left or right findings were seen in 14% each.  Multiple lobes were involved 67% of the time, while the other 33% were isolated into one lobe, more predominantly in the lower lobe.  Ground glass opacities were seen in 95% patients and 71% of patients had consolidation. 100% of the lesions were seen subpleural with 33% of patients additionally showing findings along the bronchovascular bundle.  Additional findings include air bronchograms in 57% of patients, vascular enlargement in 67%, interlobular septal thickening in 62%, and pleural effusions in 19%.  When comparing the 7 patients initially PCR negative to the 14 positive, there were more consolidative findings seen within the positive patients (p = 0.04).  Otherwise there were no significant differences between the two groups.   

Overall, this study has several limitations.  It is a retrospective study with a small case number, further evaluation with larger sample size could produce different results.  It was beneficial that patients were sent at multiple centers but at the same time, this was all from a single province in China.  As this is a pandemic, it would be interesting to see if these results would appear similar in other portions of the world.  Another limitation is the PCR methodology, this testing method can be affected by technique, reagents, and the inadequate specimens; negative exams could have had a variety of reasons besides viral load as to why it was initially negative.   

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