Faculty Bibliography

INTRODUCTION: Extra-corporeal membrane oxygenation (ECMO) is a treatment modality known to alter drug pharmacokinetics (PK). The PK changes can result from drug binding to the oxygenator, alterations in clearance, and drug adsorption or sequestration. Levels of drug absorption by polymers, silicone rubber and other materials have been linked to the drugs' lipophilicity and the published literature is mostly outdated. Additionally, 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 remdesivir (RDV) in contemporary ECMO circuits.
METHOD(S): One 1/4-in. and one 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, one 1/4-in. and one 3/8- in. closed loop ECMO circuits were assembled without an oxygenator in series. RDV 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. RDV was also maintained in a glass vial and samples obtained at the same time periods for control purposes. RDV samples were analyzed by liquid chromatography tandem mass spectrometry.
RESULT(S): For the 3/8-in. circuit with and without an oxygenator, there was a 60-70% RDV loss during the study period. For the 1/4-in. circuits with an oxygenator, there was a 35-60% RDV loss during the study period. For the 1/4-in. circuits without an oxygenator, there was a 5-20% RDV loss during the study period.
CONCLUSION(S): There was RDV loss within the circuit during the study period and the RDV loss was more pronounced with the larger 3/8-in circuit when compared with the 1/4-in. circuit. This preliminary data suggests RDV dosing may need to be adjusted for concern of drug loss via the ECMO circuit. Additional single and multiple dose studies are needed to validate these findings

PURPOSE/OBJECTIVE:To evaluate ablation zone sizes in patients undergoing pulmonary tumor cryoablation with 14-gauge cryoablation probes. MATERIALS AND METHODS/METHODS:Single-center retrospective analysis of all consecutive patients who underwent cryoablation of pulmonary tumors with one or more 14-gauge probes (August 2017-June 2020) was performed. Intraprocedural and 1-2 month post-procedural chest CTs were evaluated to characterize pulmonary lesions, ice balls, and ablation zones. Single-probe 14-gauge ablation zone volumes were compared to manufacturer reference isotherms, and to single- and two-probe ablation zones from a prior investigation of 17-gauge probes. Overall and local recurrence-free survival were calculated to 3 years. RESULTS:) (all p<0.001). Three-year overall and local recurrence-free survival were 69% (95% CI: 53-89%) and 87% (95% CI: 74-100%), respectively. CONCLUSIONS:14-gauge probes generate larger ablation volumes than 17-gauge probes. Manufacturer-reported isotherms are significantly larger than actual cryoablation zones. Cryoablation can attain low rates of local recurrence.

PURPOSE/OBJECTIVE:To evaluate detection and characterization of groundglass and fibrosis-like opacities imaged by non-contrast 0.55 Tesla MRI, and versus clinically-acquired chest CT images, in a cohort of post-Covid patients. MATERIALS AND METHODS/METHODS:64 individuals (26 women, mean age 53 ± 14 years, range 19-85) with history of Covid-19 pneumonia were recruited through a survivorship registry, with 106 non-contrast low-field 0.55 T cardiopulmonary MRI exams acquired from 9/8/2020-9/28/2021. MRI exams were obtained at an average interval of 9.5 ± 4.5 months from initial symptom report (range 1-18 months). Of these, 20 participants with 22 MRI exams had corresponding clinically-acquired CT chest imaging obtained within 30 days of MRI (average interval 18 ± 9 days, range 0-30). MR and CT images were reviewed and scored by two thoracic radiologists, for presence and extent of lung opacity by quadrant, opacity distribution, and presence versus absence of fibrosis-like subpleural reticulation and subpleural lines. Scoring was performed for each of four lung quadrants: right upper and middle lobe, right lower lobe, left upper lobe and lingula, and left lower lobe. Agreement between readers and modalities was assessed with simple and linear weighted Cohen's kappa (k) coefficients. RESULTS:Inter-reader concordance on CT for opacity presence, opacity extent, opacity distribution, and presence of subpleural lines and reticulation was 99%, 78%, 97%, 99%, and 94% (k 0.96, 0.86, 0.94, 0.97, 0.89), respectively. Inter-reader concordance on MR, among all 106 exams, for opacity presence, opacity extent, opacity distribution, and presence of subpleural lines and reticulation was 85%, 48%, 70%, 86%, and 76% (k 0.57, 0.32, 0.46, 0.47, 0.37), respectively. Inter-modality agreement between CT and MRI for opacity presence, opacity extent, opacity distribution, and presence subpleural lines and reticulation was 86%, 52%, 79%, 93%, and 76% (k 0.43, 0.63, 0.65, 0.80, 0.52). CONCLUSION/CONCLUSIONS:Low-field 0.55 T non-contrast MRI demonstrates fair to moderate inter-reader concordance, and moderate to substantial inter-modality agreement with CT, for detection and characterization of groundglass and fibrosis-like opacities.

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.

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.

Purpose: To evaluate the cryoablation zones generated in human subjects during the treatment of pulmonary tumors using 14-gauge cryoablation probes; current understanding of in vivo pulmonary cryoablation zone volumes stems predominantly from study of 17-gauge probes
Material(s) and Method(s): A single-center database of all adult patients who underwent CT-guided cryoablation of pulmonary tumors between August 2017 and June 2020 was compiled. All patients were treated using one or more 14-gauge cryoablation probes. Intraprocedural and 1- to 2-month post-procedural chest CTs were evaluated to characterize pulmonary lesions, procedural ice balls, and follow-up ablation zones. Comparison of single-probe ablation zone volumes to manufacturer reference values, and to previously published data on 17-gauge probes was performed using the Wilcoxon rank-sum test. Comparison of ablation zone volume to the number of probes used, distance of the pulmonary lesion to the pleura, and distance of the pulmonary lesion to the nearest >=3 mm vessel, were performed using Kruskal-Wallis and Pearson correlation tests.
Result(s): Pulmonary cryoablation was performed on 47 pulmonary lesions (64% primary adenocarcinoma) across 45 unique procedures on 42 patients (Female: 50%; Mean age: 75.2 +/- 11.5 years). Mean intraprocedural ice ball volume when 1, 2, or 3 probes were used was 5.4 +/- 3.8, 8.0 +/- 4.8, and 22.9 +/- 10.8 cm³, respectively. Mean cryoablation zone volume at 1-2 months when 1, 2, or 3 probes were used was 5.0 +/- 2.3, 37.5 +/- 20.5, and 28.4 cm³, respectively (n = 1 for 3 probes). Mean single-probe ablation zone volume (5.0 +/- 2.3 cm³) was significantly larger than that previously reported for 17-gauge probes (3.0 +/- 0.3 cm³) (P = 0.014)¹, but significantly smaller than manufacturer-reported in vitro 0degreeC, -20degreeC, and -40degreeC isotherms (all P < 0.0001). The number of probes was significantly associated with ablation zone volume (P = 0.0033). Mean cryoablation zone volume was not significantly associated with lesion distance to pleura (P=0.40) or lesion distance to the nearest >=3 mm vessel (P = 0.60).
Conclusion(s): Single-probe pulmonary cryoablation with 14-gauge probes generates significantly larger ablation zone volumes than with 17-gauge probes. In vivo pulmonary cryoablation generates significantly smaller ablation zone volumes than manufacturer-reported in vitro isotherms. Use of multiple probes significantly increased ablation zone volume compared with use of a single probe.
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Purpose: To determine yield of subsolid lesion core biopsy, and factors influencing yield
Material(s) and Method(s): A retrospective review of percutaneous lung biopsies from 1/1/2013 to 2/31/2019 was performed, resulting 2350 cases. Imaging was reviewed to classify lesions by attenuation; of which 363 lesions were subsolid. Subsolid lesions were defined as those with any ground-glass component. Each lesion was characterized by lobar location, long and short axis length, percent solid component, and presence of cystic components. Procedure reports were reviewed to determine needle gauge, number of passes, and patient position. Histopathology was reviewed to determine whether sampling was diagnostic, and if so, whether results benign, neoplastic, or equivocal. All lesions with benign/equivocal results underwent subsequent chart review. Of diagnostic samples, accuracy for malignancy was calculated among those for which definitive diagnosis was established. Linear regression analysis was performed to evaluate influence of lesion features on biopsy yield,.05 significance level.
Result(s): The cohort included 215 women (59%), with average age 72 years (range 19-94). 99% of core biopsies were obtained with 20-gauge needle. Core biopsies of subsolid lesions were diagnostic in 318/363 (88%) cases, of which 266/318 (84%) resulted neoplastic pathology, 29 (9%) benign, and 23 equivocal (7%). Of the benign lesions, 20/29 were confirmed (resolution, stability >24 months, and/or resection), 1 lesion was neoplastic, and 8 lacked sufficient follow-up. Of the equivocal core biopsies, 8/23 proved neoplastic, 1 benign, and 14 indeterminate. Of 45 non-diagnostic samples, 15 subsequently proved neoplastic (4 by concurrent FNA and 11 by resection), 1 benign (resolution), and the remainder indeterminate. Of 296 diagnostic samples for which there was sufficient follow-up/intervention to confirm diagnosis, sensitivity of subsolid lesion core biopsy for diagnosis of malignancy was 97%, with specificity of 100%. For lesions in which solid component was graded less than 50% of total lesion size, diagnostic yield decreased to 80% (144/179). ANOVA demonstrated solid component size to be an independent predictor of diagnostic core biopsy. Lesion location, size, percent solid component, lucencies, patient position, and number of passes were not significant factors influencing diagnostic yield.
Conclusion(s): Diagnostic yield of 20-guage core biopsy for subsolid lesions is influenced by solid component size. Sensitivity of subsolid lesion core biopsy for diagnosis of malignancy is high.
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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.

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.