What’s new in Cardiothoracic Imaging – September 2020

2 months ago
The Growth Rate of Subsolid Lung Adenocarcinoma Nodules at Chest CT

Constance de Margerie-MellonLong H NgoRitu R GillAntonio C Monteiro FilhoBenedikt H HeidingerAllison OnkenMayra A MedinaPaul A VanderLaanAlexander A Bankier

https://pubs.rsna.org/doi/10.1148/radiol.2020192322

Researchers from Harvard University and the University of Vienna seek to validate the exponential growth model for partially solid nodules (PSN’s) and ground glass nodules (GGN’s) in a cohort of patients with pathologically proven adenocarcinoma. Using their vast tissue data base, the researchers identified 74 nodules out of a total of 750 adenocarcinomas which met their inclusion/exclusion criteria of having CT scans from 3 different time points and were either partially solid or ground glass nodules. Researchers split these 74 nodules into GGN (50 or 68%) and PSN (24 or 32%). In this retrospective review, 2 blinded radiologists utilized a commercially available soft tissue kernel segmentation software to automatically segment the GGN’s and PSN’s to estimate baseline overall volume and track nodule growth through at least 3 time points prior to resection. A linear mixed-effect model was applied to simulate the data’s mean and the variance/covariance of the volume growth curves. Using these data, standard growth models were applied to simulate linear, exponential, quadratic and power law models of growth. Analysis was performed by r2 (adjusted R2) and root mean square error (RMSE), where the best fit model would have the highest r2 and lowest RMSE. The exponential growth curve proved the best fit line in modeling the growth of both the GGN’s (r2= 0.89, RSME= 688) and PSN’s (r2=0.95, RSME=146). The utilization of sequential CT examinations allowed for growth velocities to be estimated for GGN’s and PSN’s, which revealed interesting associations with CT morphological, clinical and histological characteristics. For instance, GGN’s were noted to grow at a faster rate than PSN’s, with the slope of GGN’s being nearly twice that of PSN’s. Doubling times for adenocarcinoma in situ was significantly longer than that of invasive adenocarcinoma (939 days vs 679 days, P= .01). Several other interesting associations were observed. The researchers did note that no one model of growth perfectly fit that of the tumors, which were interrogated. They offer a reasonable explanation in that tumors are innately heterogeneous and no two may grow exactly alike. Differences may be chalked up to differences in baseline aggressive features or the architectural growth pattern. As the exponential model does perform the best, the researchers propose that this model should still be used to estimate tumor growth with the caveat that due to inherent heterogeneity small differences are to be expected and that one should use analogous features to get a more complete picture of how these adenocarcinomas are behaving in situ.

 

Timely Diagnosis and Treatment Shortens the Time to Resolution of Coronavirus Disease (COVID-19) Pneumonia and Lowers the Highest and Last CT Scores From Sequential Chest CT

Guoquan Huang, Tao Gong, Guangbin Wang, Jianwen Wang, Xinfu Guo, Erpeng Cai, Shirong Li, Xiaohu Li, Yongqiang Yu, and Liangjie Lin

American Journal of Roentgenology 2020 215:2, 367-373

https://www-ajronline-org.liboff.ohsu.edu/doi/full/10.2214/AJR.20.23078

Researchers from Wuhu, China have put forth an upgraded CT classification system for following patients infected with the novel Coronavirus. It is widely known that the typical CT manifestations of COVID-19 are peripheral ground glass opacities (GGO’s). As the disease progresses, a crazy paving pattern appears amongst areas of GGO, which then progresses to consolidation. This new system augments the standard classification system in order to account for this expected clinical course by augmenting the score +1 for the presence of crazy paving and +2 for the consolidation, increasing the max lobar score from 5 to 7, and thus the total score from 25 to 35. Using this new system, in a retrospective review, a patient population of 30 COVID-19 positive patients were split into two different groups. Group A are those that were diagnosed and treated early, meaning less than or equal to 3 days after first symptom onset; while Group B presented later than 3 days after first symptom onset. There was no statistical difference in sex or age between groups. Once split, Group A and B’s sequential CT scans underwent this modified scoring system; time to disease resolution, max CT score and last CT score were used as study endpoints.  Sequential CT scores for each patient were interpolated and time to disease resolution was estimated using the time point of the highest value on the curve. The variation tendencies of sequential CT scores for Group A and Group B were plotted using Lorentzian lineshape fitting to the mean CT scores of each group. The last CT scores for Groups A and B were analyzed using a Mann Whitney test. Of the 25 patients enrolled into the study (14 in Group A and 11 in Group B), early diagnosis and treatment was positively correlated to maximum CT score, time to disease resolution and last CT score. For patients in whom diagnosis and treatment was made in less than 3 days of symptom onset, patient’s had a statistically different smaller max CT score (10 compared to 16), had a shorter time course to resolution of disease (6 days compared to 13 days) and a smaller last CT score (3.14 +/- 2.41 vs. 5.54 +/- 1.20). These results indicate that early identification and treatment, even if this is just supportive care, is critical to limit the severity and longevity of disease. By utilizing sequential CT scans and their novel scoring system, researchers were able to quantitatively and accurately describe the evolution of COVID pneumonia from GGO, to GGO with crazy paving, to consolidation and validate that earlier diagnosis and treatment positively correlates with disease severity and time course to resolution. A study with increased power would be welcome to validate these findings in a larger cohort.

 

Comparative study of Coronavirus in Younger and Older Adults

Zhu, Tingting MD, PhD*; Wang, Yujin MD*; Zhou, Shuchang MD, PhD*; Zhang, Na PhD†; Xia, Liming MD, PhD*

Journal of Thoracic Imaging: July 2020 – Volume 35 – Issue 4 – p W97-W101

https://journals.lww.com/thoracicimaging/Fulltext/2020/07000/A_Comparative_Study_of_Chest_Computed_Tomography.13.aspx

Researchers from Hubei province performed a retrospective review of 72 hospitalized symptomatic adult patients with confirmed cases of COVID-19. These 72 patients were split into two groups one of “older” adults defined as age > 60 and “younger” adults defined as < 60 years old. Fever (81.9%) and cough (38.9%) were the most common symptoms reported, with dyspnea and fatigue reported in similar numbers of patients in both groups. Chest CT examinations were reviewed and evaluated for 1) distribution of disease (central vs peripheral) 2) number of lobes involved, with the lingula included as its own discrete lobe 3) lesion density (pure ground glass opacities, ground glass opacities with consolidation, or consolidative opacities) 4) interstitial changes (reticulations, interlobular septal thickening, subpleural lines, etc.) 5) accompanying radiological signs such as vacuolation, air bronchograms or vascular engorgement 6) pleural reactions (pleural thickening, pleural traction and pleural thickening). Although the power of the study is relatively small with a cohort of only 72 patients, the researchers observe the most common presenting features of symptomatic COVID-19 in adults. The older patient group were noted to have a statistically significant difference in lung involvement with 67.9% of this group exhibiting involvement in all 6 lobes compared to only 36.4% of cases in the young patient group. Both groups exhibited similar lesion density with ground glass opacities with mixed consolidation predominating in a majority of patients (81.9%). The groups showed similar disease distribution with a peripheral predominant pattern noted in 70.3% of cases. Older patients exhibited subpleural lines (50%) and pleural thickening (71.4%) on their CT scans at a higher rate than their younger counterparts. These data suggest that findings of peripheral-predominant mixed ground glass and consolidative opacities as the most common presenting CT findings in symptomatic individuals is accurate. Older individuals routinely exhibited a more diffuse pattern of lung involvement when compared to the younger group, potentially suggesting an explanation for the observed discrepancy in mortality and morbidity in older patients infected with COVID-19. The authors propose that the other statistically significant findings of pleural thickening and subpleural lines found in older patient populations may relate to differences in response to lung parenchymal inflammation in the older cohort and may be a marker of disease progression.

 

Incidental Coronary Artery Calcification and Stroke Risk in Patients With Atrial Fibrillation

Dustin Hillerson, Thomas Wool, Gbolahan O. Ogunbayo, Vincent L. Sorrell, and Steve W. Leung

American Journal of Roentgenology 2020 215:2, 344-350

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22298

Researchers from the University of Kentucky aimed to determine whether the presence of incidental coronary artery calcifications identified in patients with atrial fibrillation (Afib) on routine chest CTs were associated with stroke independently of the CHA2DS2-VASc risk assessment. It is postulated that coronary artery calcifications (CACs) could be a surrogate for coronary artery disease (CAD) in patients with Afib. Two cohorts were established in this retrospective review, 203 patients who had a diagnosis of A-fib and subsequent encounter for stroke and 203 patients with Afib without stroke; importantly, each stroke case was one-to-one matched with a non-stroke case whereby the patients had identical risk factors. Routine chest CTs were reviewed for both cohorts to ascertain the presence of CACs, and the extent of CAC was graded as none, mild, moderate or severe. CACs were identified in 129 patients with stroke (63.5%) and in 121 patients without stroke (59.6%) with a P value of 0.46. However, COX regression analysis identified a significant temporal relationship between the presence of CACs and the likelihood of stroke with a Hazard Ratio (HR) of 1.47 (95% CI, 1.1-1.97 p <0.01). 124 of the 203 patients in the CAC group died during follow up, while only 60 of the patients without CAC died in the same time period producing a HR of 1.6 (95% CI 1.17-2.18, p<0.01). The authors postulate that incidental CAC could be added to the CHA2DS2VASc risk assessment tool as they have demonstrated a moderate association with stroke and mortality. The limitations of this study are possible bias from retrospective review and mortality befrom other confounding factors.

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