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OBJECTIVE. Coronavirus disease (COVID-19) is a global pandemic. Studies in the radiology literature have suggested that CT might be sufficiently sensitive and specific in diagnosing COVID-19 when used in lieu of a reverse transcription-polymerase chain reaction test; however, this suggestion runs counter to current society guidelines. The purpose of this article is to critically review some of the most frequently cited studies on the use of CT for detecting COVID-19. CONCLUSION. To date, the radiology literature on COVID-19 has consisted of limited retrospective studies that do not substantiate the use of CT as a diagnostic test for COVID-19.

Hypophosphatasia (HPP) is the inborn-error-of-metabolism characterized enzymatically by insufficient activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP) and caused by either mono- or bi-allelic loss-of-function mutation(s) of the gene ALPL that encodes this cell surface phosphomonoester phosphohydrolase. In HPP, the natural substrates of TNSALP accumulate extracellularly and include inorganic pyrophosphate (PPi), a potent inhibitor of biomineralization. This PPi excess leads to rickets or osteomalacia in all but the most mild "odonto" form of the disease. Adults with HPP understandably often also manifest calcium PPi dihydrate deposition, whereas enthesopathy and calcific periarthritis from hydroxyapatite (HA) crystal deposition can seem paradoxical in face of the defective skeletal mineralization. In 2015, asfotase alfa (AA), a HA-targeted TNSALP, was approved multinationally as an enzyme replacement therapy for HPP. AA hydrolyzes extracellular PPi (ePPi) and in HPP enables HA crystals to grow and mineralize skeletal matrix. In direct contrast to HPP, deficiency of ePPi characterizes the inborn-errors-of-metabolism generalized arterial calcification of infancy (GACI) and pseudoxanthoma elasticum (PXE). In GACI and PXE, deficiency of ePPi leads to ectopic mineralization including vascular calcification (VC). Therefore, in HPP, ectopic mineralization including VC could hypothetically result from, or be exacerbated by, the persistently high circulating TNSALP activity that occurs during AA treatment. Herein, using a routine computed tomography (CT) method to quantitate coronary artery calcium, we found no ectopic mineralization in the heart of an elderly woman with HPP before or after 8 months of AA treatment. Subsequently, investigational high-resolution peripheral quantitative CT and dual-energy X-ray absorptiometry showed absence of peripheral artery and aortic calcium after further AA treatment. Investigation of additional adults with HPP could reveal if the superabundance of ePPi protects against VC, and whether long-term AA therapy causes or exacerbates any ectopic mineralization., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Chest computed tomography (CT) imaging is being increasingly used for potential lung donor assessment. However, the efficacy of CT imaging in this setting remains unknown. We hypothesize that chest CT imaging independently affects the decision-making process in donor lung utilization., Methods: We conducted a retrospective cohort study of all adult donation after brain death donors managed through our local organ procurement organization from June 2011 to November 2016. An experienced thoracic radiologist independently reviewed donor chest CT and chest x-ray images in a blinded, standardized manner to determine the presence of structural lung disease (eg, emphysema, interstitial lung disease [ILD]) and acute abnormalities (eg, traumatic lung injury [TLI]). Distinct models of lung utilization were fit to groups with initial partial pressure of oxygen (iPaO 2 ) ≤300 mm Hg (suboptimal) and iPaO 2 >300 mm Hg (optimal)., Results: The organ procurement organization managed 753 donors during the study period, with a lung utilization rate ([lung donors/all organ donors] × 100) of 36.5% (275 of 753). Four hundred forty-five (59.1%) donors received chest CT imaging, revealing emphysema (13.7%), ILD (2.5%), and TLI (7.2%). In univariate analysis, findings of TLI (odds ratio [OR], 2.23; 95% confidence interval [CI], 1.08-4.61) were positively associated with lung utilization, whereas findings of emphysema (OR, 0.18; CI, 0.08-0.40) were negatively associated with utilization. In multivariate analysis, CT findings of emphysema (OR, 0.21; CI 0.08-0.54) remained negatively associated with utilization. No potential donors with CT findings of ILD became lung donors. After controlling for chest x-ray findings, chest CT imaging findings of structural lung disease remained negatively associated with utilization (P = .0001). Lung utilization rate in the suboptimal and optimal iPaO 2 populations was 35.1% and 41.4%, respectively, and CT findings of emphysema had a significant association with nonutilization in both groups., Conclusions: In the evaluation of potential lung donors, chest CT imaging findings of structural lung disease, such as emphysema and ILD, have a significant negative association with lung utilization. Our findings suggest that chest CT imaging might be an important adjunct to conventional lung donor assessment criteria., (Copyright © 2018 The American Association for Thoracic Surgery. All rights reserved.)

The purpose of this study is to examine the association of sarcopenia as measured by psoas muscle area and outcomes in patients undergoing left ventricular assist device (LVAD) implantation. We retrospectively examined 333 consecutive patients who underwent implantation of a HeartMate II LVAD at our institution from June 2008 to August 2013. Patients were included if they had a perioperative computed tomography that spanned the L3-L4 vertebrae. Sarcopenia was defined as having the lowest tertile psoas muscle area by gender. The primary end point was the composite of inpatient death or prolonged length of stay of >30 days. One hundred patients met inclusion criteria. The psoas muscle area cut-off values for the lowest tertiles were 12.0 cm 2 for men and 6.5 cm 2 for women, resulting in 32 sarcopenic patients (32%). The primary outcome of inpatient death or prolonged length of stay occurred in 81% of patients in the sarcopenic versus 60% in the nonsarcopenic group (p = 0.043). There was a trend toward prolonged length of stay in sarcopenic patients but no difference in overall mortality. This demonstrates that sarcopenia as measured by psoas muscle area is associated with increased composite length of stay and mortality after LVAD implantation and may serve as correlate for frailty., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Advances in surgical and medical treatment for congenital heart disease have resulted in greater life expectancy. As a result, there has been an increase in the utilization of cross-sectional imaging for diagnosis and management of complex congenital heart disease. This manuscript describes a morphological and sequential segmental approach to deciphering the code of complex congenital heart defects in cross-sectional imaging, mostly computed tomography. This manuscript will review approaches to differentiate types of transposition, the anatomic relationships of cardiac structures, and the application of these relationships in the description of complex congenital heart disease.

Purpose: To mathematically model the relationship between CT measurements of emphysema obtained from images reconstructed using different section thicknesses and kernels and to evaluate the accuracy of the models for converting measurements to those of a reference reconstruction., Methods: CT raw data from the lung cancer screening examinations of 138 heavy smokers were reconstructed at 15 different combinations of section thickness and kernel. An emphysema index was quantified as the percentage of the lung with attenuation below -950 HU (EI950). Linear, quadratic, and power functions were used to model the relationship between EI950 values obtained with a reference 1 mm, medium smooth kernel reconstruction and values from each of the other 14 reconstructions. Preferred models were selected using the corrected Akaike information criterion (AICc), coefficients of determination (R2), and residuals (conversion errors), and cross-validated by a jackknife approach using the leave-one-out method., Results: The preferred models were power functions, with model R2 values ranging from 0.949 to 0.998. The errors in converting EI950 measurements from other reconstructions to the 1 mm, medium smooth kernel reconstruction in leave-one-out testing were less than 3.0 index percentage points for all reconstructions, and less than 1.0 index percentage point for five reconstructions. Conversion errors were related in part to image noise, emphysema distribution, and attenuation histogram parameters. Conversion inaccuracy related to increased kernel sharpness tended to be reduced by increased section thickness., Conclusions: Image reconstruction-related differences in quantitative emphysema measurements were successfully modeled using power functions.

Objective: To evaluate the use of inflation-fixed lung tissue for emphysema quantification with computed tomography (CT) and He magnetic resonance (MR) diffusion imaging., Methods: Fourteen subjects representing a range of chronic obstructive pulmonary disease severity who underwent complete or lobar lung resection were studied. Computed tomographic measurements of lung attenuation and MR measurements of the hyperpolarized 3He apparent diffusion coefficient (ADC) in resected specimens fixed in inflation with heated formalin vapor were compared with measurements obtained before fixation., Results: The mean (SD) CT emphysema indices were 56% (17%) before and 58% (19%) after fixation (P = 0.77; R = 0.76). Index differences correlated with differences in lung volume (R = 0.47). The mean (SD) 3He ADCs were 0.40 (0.15) cm/s before and 0.39 (0.14) cm/s after fixation (P = 0.03, R = 0.98). The CT emphysema index and the 3He ADC were correlated before (R = 0.89) and after fixation (R = 0.79)., Conclusions: Concordance of CT and 3He MR imaging measurements in unfixed and inflation-fixed lungs supports the use of inflation-fixed lungs for quantitative imaging studies in emphysema.

Objective: The purpose of this study was to assess the accuracy of emphysema measurements obtained from systematic samples of evenly spaced CT images compared with measurements obtained from the entire scan., Materials and Methods: Evenly spaced transverse sections from the CT studies of 136 heavy smokers who underwent screening for lung cancer in the National Lung Screening Trial and of 112 subjects who underwent imaging before lung volume reduction surgery were sampled retrospectively. The samples were acquired both by selection of specific numbers of evenly spaced images and by selection of images at specific distance intervals. The percentage of lung pixels with attenuation below specific thresholds was used as an emphysema index. The image sample error was determined as the difference in emphysema index between the image samples and the entire scan., Results: The largest absolute image sample errors in the National Lung Screening Trial cohort with image sample sizes of five, 10, and 20 were 2.2, 0.8, and 0.5 index percentage points, respectively, at 1-mm section thickness (-960 HU threshold), and 2.6, 1.1, and 0.5 index percentage points at 5-mm section thickness (-930 HU threshold). The largest errors in the lung volume reduction surgery cohort for image sample sizes of five and 10 were 5.6 and 2.3 index percentage points at 8- to 10-mm section thickness (-900 HU threshold). Image sample errors were equivalent for the two sampling methods., Conclusion: Systematic sampling resulted in very small errors in emphysema quantification and may be useful for decreasing radiation exposure in clinical research studies of emphysema.

Rationale and Objectives: Computed tomography (CT) section thickness and reconstruction kernel each influence CT measurements of emphysema. This study was performed to assess whether their effects are related to the magnitude of the measurement., Materials and Methods: Low-radiation-dose multidetector CT was performed in 21 subjects representing a wide range of emphysema severity. Images were reconstructed using 20 different combinations of section thickness and reconstruction kernel. Emphysema index values were determined as the percentage of lung pixels having attenuation lower than multiple thresholds ranging from -960 HU to -890 HU. The index values obtained from the different thickness-kernel combinations were compared by repeated measures analysis of variance and Bland-Altman plots of mean versus difference in all subjects, and correlated with quantitative histology (mean linear intercept, Lm) in a subset of resected lung specimens., Results: The effects of section thickness and reconstruction kernel on the emphysema index were significant (P < .001) and diminished as the index attenuation threshold was raised. The changes in index values from changing the thickness-kernel combination were largest for subjects with intermediate index values (10%-30%), and became progressively smaller for those with lower and higher index values. This pattern was consistent regardless of the thickness-kernel combinations compared and the HU threshold used. Correlations between the emphysema index values obtained with each thickness-kernel combination and Lm ranged from r = 0.55-0.68 (P = .007-.03)., Conclusion: The effects of CT section thickness and kernel on emphysema index values varied systematically with the magnitude of the emphysema index. All reconstruction techniques provided significant correlations with quantitative histology., (Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to determine the lobar distribution and associated radiologic/clinical findings of partial anomalous pulmonary venous return (PAPVR) in the adult population using multidetector computed tomography (MDCT)., Materials and Methods: The radiology information database was queried for patients with PAPVR diagnosed on chest computed tomography. Forty-seven cases of PAPVR were retrospectively identified from 45,538 contrast-enhanced chest computed tomography examinations performed over an 8-year period. Diagnostic findings were confirmed via consensus review by 2 cardiothoracic radiologists. Medical charts were evaluated for ancillary radiographic data, cardiopulmonary signs and symptoms, and subsequent surgical interventions., Results: Calculated disease prevalence was 0.1%, with mean patient age of 58 years and a 58% female predominance. PAPVR was observed with 47% frequency in the left upper lobe, 38% right upper lobe (RUL), 13% right lower lobe, and 2% left lower lobe. Among cases of RUL PAPVR, 42% were associated with sinus venosus atrial septal defect (ASD). Other reported anomalies were right-sided volume overload (47%), isolated upper lobe PAPVR (29% left and 5% right), bilateral PAPVR (4%), scimitar syndrome (13%), persistent left superior vena cava (9%), and azygos continuation of the inferior vena cava (4%). Reported cardiopulmonary signs/symptoms and imaging modalities other than MDCT were neither sensitive nor specific for PAPVR. Surgical repair was performed in 21% of cases and included ASD patching, intracardiac baffle, anomalous vein anastomosis, systemic vein translocation, and Warden procedure., Conclusions: This represents the largest and only consecutive retrospective study of PAPVR in adults to date. Left upper lobe PAPVR was the most frequent location detected on MDCT, whereas RUL PAPVR was slightly less common and moderately associated with sinus venosus ASD. Utilization of contrast-enhanced studies and MDCT technology has enabled improved detection and characterization of PAPVR for early diagnosis and/or intervention.

Objective: This study was performed to compare standard- and low-radiation-dose techniques in the CT quantification of emphysema., Materials and Methods: The study population consisted of 36 men and 20 women who were current or former heavy smokers and underwent standard-dose (effective tube current, 100-250 mAs) chest CT at our institution within 6 months of having undergone low-dose (effective tube current, 30-60 mAs) chest CT. All CT scans were reconstructed at 5-mm slice thickness with a smooth filter. CT-measured lung volume, mean and median lung attenuation, and percentage of lung volume with attenuation lower than multiple thresholds (emphysema index values) were compared by Pearson correlation, two-tailed and paired Student's t tests, and regression analysis., Results: There were no significant differences in mean attenuation (-848 vs -846 H, p > 0.35) for the low dose and the standard dose or in median lung attenuation (-879 vs -878 H, p > 0.66). Low- and standard-dose emphysema indexes were correlated at all attenuation thresholds (r = 0.86-0.97). Mean emphysema indexes were higher on the low-dose scans, but the mean difference at all thresholds was less than 3%. The differences were significant (p < 0.05) only at the lower index thresholds, correlated with differences in lung volume (r < or = 0.86), and increased with greater differences in dose., Conclusion: Low-dose technique has minimal effect on CT quantification of emphysema.

Currently, the literature lacks a solid body of research on decision and cost-effectiveness analysis of imaging strategies for adults and children suspected of having a brain neoplasm. This article describes the epidemiology and clinical presentation of brain neoplasms, reviews current diagnostic strategies, highlights gaps in the literature on decision and cost-effectiveness analysis, and suggests directions for future research.