Faculty Bibliography

Quantitative radiomic and iodine imaging features have been explored for diagnosis and characterization of tumors. In this work, we invistigate combined whole-lesion radiomic and iodine analysis for the differentiation of pulmonary tumors on contrast-enhanced dual-energy CT (DECT) chest images. 100 biopsy-proven solid lung lesions on contrast-enhanced DECT chest exams within 3 months of histopathologic sampling were identified. Lesions were volumetrically segmented using open-source software. Lesion segmentations and iodine density volumes were loaded into a radiomics prototype for quantitative analysis. Univariate analysis was performed to determine differences in volumetric iodine concentration (mean, median, maximum, minimum, 10th percentile, 90th percentile) and first and higher order radiomic features (n = 1212) between pulmonary tumors. Analyses were performed using a 2-sample t test, and filtered for false discoveries using Benjamini-Hochberg method. 100 individuals (mean age 65 ± 13 years; 59 women) with 64 primary and 36 metastatic lung lesions were included. Only one iodine concentration parameter, absolute minimum iodine, significantly differed between primary and metastatic pulmonary tumors (FDR-adjusted p = 0.015, AUC 0.69). 310 (FDR-adjusted p = 0.0008 to p = 0.0491) radiomic features differed between primary and metastatic lung tumors. Of these, 21 features achieved AUC ≥ 0.75. In subset analyses of lesions imaged by non-CTPA protocol (n = 72), 191 features significantly differed between primary and metastatic tumors, 19 of which achieved AUC ≥ 0.75. In subset analysis of tumors without history of prior treatment (n = 59), 40 features significantly differed between primary and metastatic tumors, 11 of which achieved AUC ≥ 0.75. Volumetric radiomic analysis provides differentiating capability beyond iodine quantification. While a high number of radiomic features differentiated primary versus metastatic pulmonary tumors, fewer features demonstrated good individual discriminatory utility.

Lung nodules are frequently encountered while interpreting chest CTs and are challenging to detect, characterize, and manage given they can represent both benign or malignant etiologies. An understanding of features associated with malignancy and causes of interpretive pitfalls is helpful to avoid misdiagnoses. This review addresses pertinent topics related to the etiologies for missed lung nodules on radiography and CT. Additionally, CT imaging technical pitfalls and challenges in addition to issues in the evaluation of nodule morphology, attenuation, and size will be discussed. Nodule management guidelines will be addressed as well as recent investigations that further our understanding of lung nodules.

Acute pulmonary embolism (PE) is a critical, potentially life-threatening finding on contrast-enhanced cross-sectional chest imaging. Timely and accurate diagnosis of thrombus acuity and extent directly influences patient management, and outcomes. Technical and interpretive pitfalls may present challenges to the radiologist, and by extension, pose nuance in the development and integration of artificial intelligence support tools. This review delineates imaging considerations for diagnosis of acute PE, and rationale, hurdles and applications of artificial intelligence for the PE task.

INTRODUCTIONS: ECMO is a treatment modality known to alter drug pharmacokinetics (PK). The purpose of this study was to determine the impact of the Quadrox-i pediatric and adult oxygenators on the PK of peramivir (PRV) in contemporary ECMO circuits.
METHOD(S):Two 1/4-in. and two 3/8-in. closed loop ECMO circuits were prepared using custom tubing with polyvinylchloride and superTygon (Medtronic Inc., Minneapolis, MN) and a Quadrox-i adult or pediatric oxygenator (Maquet). Additionally, two 1/4-in. and two 3/8-in. closed loop ECMO circuits wer assembled without an oxygenator in series. The circuits were carbon dioxide primed, evacuated, and then crystalloid primed. After debubbling the circuit, 50 mL of 5% albumin was added and then displaced with the priming solution (whole blood), tromethamine, heparin, and calcium gluconate. The circuit pH was adjusted to a range of 7.35-7.45. The closed-loop design was established by connecting the ends of the arterial and venous cannulae to a reservoir bag, allowing continuous flow of the priming fluid around the circuit. PRV was added to the circuit and levels were obtained pre-and post-oxygenator at the following time intervals; 5 mins, 1, 2, 3, 4, 5, 6, 8, 12, and 24 hrs. PRV was also maintained in a glass vial and samples obtained at the same time periods for control purposes. PRV samples were analyzed by liquid chromatography tandem mass spectrometry.
RESULT(S): For the 3/8-in. circuits with an oxygenator, there was < 15% PRV loss during the study period. For the 3/8-in. circuits without an oxygenator, there was < 3% PRV loss during the study period. For the 1/4-in. circuits with an oxygenator, there was < 15% PRV loss during the study period. For the 1/4-in. circuits without an oxygenator, there was < 3% PRV loss during the study period.
CONCLUSION(S): There was no significant PRV loss over the 24-hour study period in either the 1/4-in. or 3/8-in circuit, regardless of the presence of the oxygenator. The concentrations obtained pre- and post-oxygenator appeared to approximate each other suggesting there may be no drug loss via the oxygenator. This preliminary data suggests PRV dosing may not need to be adjusted for concern of drug loss via the oxygenator. Additional single and multiple dose studies are needed to validate these findings

OBJECTIVE:To evaluate the impact of structured recommendations on follow-up completion for incidental lung nodules (ILNs). METHODS:Patients with ILNs before and after implementation of structured Fleischner recommendations and electronic tracking were sampled randomly. The cohorts were compared for imaging follow-up. Multivariable logistic regression was used to assess appropriate follow-up and loss to follow-up, with independent variables including use of structured recommendations or tracking, age, gender, race, ethnicity, setting of the index test (inpatient, outpatient, emergency department), smoking history, and nodule features. RESULTS:In all, 1,301 patients met final inclusion criteria, including 255 patients before and 1,046 patients after structured recommendations or tracking. Baseline differences were found in the pre- and postintervention groups, with smaller ILNs and younger age after implementing structured recommendations. Comparing pre- versus postintervention outcomes, 40.0% (100 of 250) versus 29.5% (309 of 1,046) of patients had no follow-up despite Fleischner indications for imaging (P = .002), and among the remaining patients, 56.6% (82 of 145) versus 75.0% (553 of 737) followed up on time (P < .001). Delayed follow-up was more frequent before intervention. Differences postintervention were mostly accounted for by nodules ≤ 8 mm in the outpatient setting (P < .001). In multivariable analysis, younger age, White race, outpatient setting, and larger nodule size showed significant association with appropriate follow-up completion (P < .015), but structured recommendations did not. Similar results applied for loss to follow-up. DISCUSSION/CONCLUSIONS:Consistent use of structured reporting is likely key to mitigate selection bias when benchmarking rates of appropriate follow-up of ILN. Emergency department patients and inpatients are at high risk of missed or delayed follow-up despite structured recommendations.

OBJECTIVE:To evaluate the inter-observer consistency for subsolid pulmonary nodule radiomic features. MATERIALS AND METHODS/METHODS:Subsolid nodules were selected by reviewing radiology reports of CT examinations performed December 1, 2015 to April 1, 2016. Patients with CTs at two time points were included in this study. There were 55 patients with subsolid nodules, of whom 14 had two nodules. Of 69 subsolid nodules, 66 were persistent at the second time point, yielding 135 lesions for segmentation. Two thoracic radiologists and an imaging fellow segmented the lesions using a semi-automated volumetry algorithm (Syngo.via Vb20, Siemens). Coefficient of variation (CV) was used to assess consistency of 91 quantitative measures extracted from the subsolid nodule segmentations, including first and higher order texture features. The accuracy of segmentation was visually graded by an experienced thoracic radiologist. Influencing factors on radiomic feature consistency and segmentation accuracy were assessed using generalized estimating equation analyses and the Exact Mann-Whitney test. RESULTS:Mean patient age was 71 (38-93 years), with 39 women and 16 men. Mean nodule volume was 1.39mL, range .03-48.2mL, for 135 nodules. Several radiomic features showed high inter-reader consistency (CV<5%), including entropy, uniformity, sphericity, and spherical disproportion. Descriptors such as surface area and energy had low consistency across inter-reader segmentations (CV>10%). Nodule percent solid component and attenuation influenced inter-reader variability of some radiomic features. The presence of contrast did not significantly affect the consistency of subsolid nodule radiomic features. Near perfect segmentation, within 5% of actual nodule size, was achieved in 68% of segmentations, and very good segmentation, within 25% of actual nodule size, in 94%. Morphologic features including nodule margin and shape (each p <0.01), and presence of air bronchograms (p = 0.004), bubble lucencies (p = 0.02) and broad pleural contact (p < 0.01) significantly affected the probability of near perfect segmentation. Stroke angle (p = 0.001) and length (p < 0.001) also significantly influenced probability of near perfect segmentation. CONCLUSIONS:The inter-observer consistency of radiomic features for subsolid pulmonary nodules varies, with high consistency for several features, including sphericity, spherical disproportion, and first and higher order entropy, and normalized non-uniformity. Nodule morphology influences the consistency of subsolid nodule radiomic features, and the accuracy of subsolid nodule segmentation.

Extracorporeal membrane oxygenation (ECMO) is known to alter drug pharmacokinetics (PK). The PK changes can result from drug binding to the oxygenator, alterations in clearance, and drug sequestration but the published literature is outdated. There is limited data regarding the impact of the oxygenator on drug changes in ECMO circuits in comparison to the other components of the ECMO circuit. The purpose of this study was to determine the impact of the Quadrox-i pediatric and adult oxygenators on the PK of peramivir (PRV) in contemporary ECMO circuits. Two of both 1/4-in. and 3/8-in. closed loop ECMO circuits were prepared with a Quadrox-i adult or pediatric oxygenator (Getinge) and two of both sizes without an oxygenator in series. The circuits were primed with 20 mL of 5% albumin, packed red blood cells, heparin, sodium bicarbonate and calcium gluconate. Circuits were run at 1L/minute continuously. PRV was added to the circuit and levels were obtained pre-and postoxygenator at the following time intervals; 5 mins,1, 2, 3, 4, 5, 6, 8,12, and 24 hrs. PRV was also maintained in a glass vial and samples obtained at the same time periods. The results were consistent in both circuit sizes with no significant PRV loss over the 24-hour study period (<15% loss with oxygenator and <3% loss without oxygenator). This preliminary data suggests PRV dosing may not need to be adjusted for concern of drug loss via the oxygenator. Additional single and multiple dose studies are needed to validate these findings

Diffuse lung disease, frequently referred to as interstitial lung disease, encompasses numerous disorders affecting the lung parenchyma. The potential etiologies of diffuse lung disease are broad with several hundred established clinical syndromes and pathologies currently identified. Imaging plays a critical role in diagnosis and follow-up of many of these diseases, although multidisciplinary discussion is the current standard for diagnosis of several DLDs. This document aims to establish guidelines for evaluation of diffuse lung diseases for 1) initial imaging of suspected diffuse lung disease, 2) initial imaging of suspected acute exacerbation or acute deterioration in cases of confirmed diffuse lung disease, and 3) clinically indicated routine follow-up of confirmed diffuse lung disease without acute deterioration. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Chest pain is a common reason that patients may present for evaluation in both ambulatory and emergency department settings, and is often of musculoskeletal origin in the former. Chest wall syndrome collectively describes the various entities that can contribute to chest wall pain of musculoskeletal origin and may affect any chest wall structure. Various imaging modalities may be employed for the diagnosis of nontraumatic chest wall conditions, each with variable utility depending on the clinical scenario. We review the evidence for or against use of various imaging modalities for the diagnosis of nontraumatic chest wall pain. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ABSTRACT/UNASSIGNED:Percutaneous computed tomography-guided transthoracic lung biopsy is an effective and minimally invasive procedure to achieve tissue diagnosis. Radiologists are key in appropriate referral for further workup, with percutaneous computed tomography-guided transthoracic lung biopsy performed by both thoracic and general interventionalists. Percutaneous computed tomography-guided transthoracic lung biopsy is increasingly performed for both diagnostic and research purposes, including molecular analysis. Multiple patient, lesion, and technique-related variables influence diagnostic accuracy and complication rates. A comprehensive understanding of these factors aids in procedure planning and may serve to maximize diagnostic yield while minimizing complications, even in the most challenging scenarios.