Faculty Bibliography

Pyrite FeS2 has long been considered a potentially ideal photovoltaic material, but solar cells utilizing pyrite exhibit low open-circuit voltages (VOC) and have failed to achieve conversion efficiencies >3%. The recent discovery of a conductive p-type surface layer on n-type pyrite single crystals raises the intriguing possibility that the low VOC results from a leaky internal p-n junction between the surface and interior. Here, we reveal this internal junction, for the first time, through horizontal electronic transport measurements on sulfur vacancy (VS)- and Co-doped n-type pyrite single crystals. We observe a steep increase in resistance upon cooling heavily VS-doped crystals below ∼200 K, as the dominant charge transport crosses over from interior to surface conduction. The frequently employed two-resistor equivalent circuit model for lightly-doped pyrite crystals cannot reproduce this steep rise, but it can be accounted for, quantitatively, and with high fidelity, by adding an internal Schottky junction resistance between the surface and the interior. The average extracted Schottky barrier height is 320 meV (varying from 130-560 meV), significantly below expectations from band bending calculations (>750 meV) but similar in magnitude to VOC values reported for pyrite heterojunction solar cells. This internal p-n junction is thus implicated as the potential origin of the long-standing low-VOC problem in pyrite.

PURPOSE/OBJECTIVE:The right ventricular outflow tract (RVOT) velocity time integral (VTI), an echocardiographic measure of stroke distance, correlates with cardiac index. We sought to determine the prognostic significance of low RVOT VTI on clinical outcomes among patients with acute pulmonary embolism (PE). MATERIALS AND METHODS/METHODS:We conducted a retrospective review of echocardiograms on Pulmonary Embolism Response Team (PERT) activations at our institution. The main outcome was a composite of death, cardiac arrest, or hemodynamic deterioration. RESULTS:Of 188 patients, 30 met the combined outcome (16%) and had significantly lower RVOT VTI measurements (9.0 cm v 13.4 cm, p < 0.0001). The AUC for RVOT VTI at a cutoff of 10 cm was 0.78 (95% CI 0.67-0.90) with a sensitivity, specificity, negative predictive value, and positive predictive value of 0.72, 0.81, 0.94, and 0.42, respectively. Fifty-two patients of the cohort were classified as intermediate-high-risk PE and 21% of those met the combined outcome. RVOT VTI was lower among outcome positive patients (7.3 cm v 10.7 cm, p = 0.02). CONCLUSIONS:Low RVOT VTI is associated with poor clinical outcomes among patients with acute PE.

Background We observed a high number of patients with COVID-19 pneumonia who had barotrauma related to invasive mechanical ventilation at our institution. Purpose To determine if the rate of barotrauma in patients with COVID-19 infection was greater than other patients requiring invasive mechanical ventilation at our institution. Methods In this retrospective study, clinical and imaging data of patients seen between 03/01/2020 and 04/06/2020 who tested positive for COVID-19 and experienced barotrauma associated with invasive mechanical ventilation were compared to patients without COVID-19 infection during the same period. Historical comparison was made to barotrauma rates of patients with acute respiratory distress syndrome (ARDS) from 02/01/2016 to 02/01/2020 at our institution. Comparison of patient groups was performed using categorical or continuous statistical testing as appropriate with multivariable regression analysis. Patient survival was assessed using Kaplan-Meier curves analysis. Results 601 patients with COVID-19 infection underwent invasive mechanical ventilation (63 ± 15 years, 71% men). There were 89/601 (15%) patients with one or more barotrauma events, for a total of 145 barotrauma events (24% overall events) (95% CI 21-28%). During the same period, 196 patients without COVID-19 infection (64 ± 19 years, 52% male) with invasive mechanical ventilation had 1 barotrauma event (.5% 95% CI, 0-3%, p<.001 vs. the group with COVID-19 infection). Of 285 patients with ARDS over the prior 4 years on invasive mechanical ventilation (68 ± 17 years, 60% men), 28 patients (10%) had 31 barotrauma events, with overall barotrauma rate of 11% (95% CI 8-15%, p<.001 vs. the group with COVID-19 infection). Barotrauma is an independent risk factor for death in COVID-19 (OR=2.2, p=.03), and is associated with longer hospital length of stay (OR=.92, p<.001). Conclusion Patients with COVID-19 infection and invasive mechanical ventilation had a higher rate of barotrauma than patients with ARDS and patients without COVID-19 infection.

Localizing and characterizing clinically-significant lung nodules, a potential precursor to lung cancer, at the lowest achievable radiation dose is demanded to minimize the stochastic radiation effects from x-ray computed tomography (CT). A minimal dose level is heavily dependent on the image reconstruction algorithms and clinical task, in which the tissue texture always plays an important role. This study aims to investigate the dependence through a task-based evaluation at multiple dose levels and variable textures in reconstructions with prospective patient studies. 133 patients with a suspicious pulmonary nodule scheduled for biopsy were recruited and the data was acquired at120kVp with three different dose levels of 100, 40 and 20mAs. Three reconstruction algorithms were implemented: analytical filtered back-projection (FBP) with optimal noise filtering; statistical Markov random field (MRF) model with optimal Huber weighting (MRF-H) for piecewise smooth reconstruction; and tissue-specific texture model (MRF-T) for texture preserved statistical reconstruction. Experienced thoracic radiologists reviewed and scored all images at random, blind to the CT dose and reconstruction algorithms. The radiologists identified the nodules in each image including the 133 biopsy target nodules and 66 other non-target nodules. For target nodule characterization, only MRF-T at 40mAs showed no statistically significant difference from FBP at 100mAs. For localizing both the target nodules and the non-target nodules, some as small as 3mm, MRF-T at 40 and 20mAs levels showed no statistically significant difference from FBP at 100mAs, respectively. MRF-H and FBP at 40 and 20mAs levels performed statistically differently from FBP at 100mAs. This investigation concluded that (1) the textures in the MRF-T reconstructions improves both the tasks of localizing and characterizing nodules at low dose CT and (2) the task of characterizing nodules is more challenging than the task of localizing nodules and needs more dose or enhanced textures from reconstruction.

Artificial intelligence (AI) is a broad field of computational science that includes many subsets. Today the most widely used subset in medical imaging is machine learning (ML). Many articles have focused on the use of ML for pattern recognition to detect and potentially diagnose various pathologies. However, AI algorithm development is now directed toward workflow management. AI can impact patient care at multiple stages of their imaging experience and assist in efficient and effective scheduling, imaging performance, worklist prioritization, image interpretation, and quality assurance. The purpose of this manuscript was to review the potential AI applications in radiology focusing on workflow management and discuss how ML will affect cardiothoracic imaging.

OBJECTIVE. The response to coronavirus disease (COVID-19) is evolving in New York City. We would like to share our experiences, thoughts, and perspectives on coping with the pandemic. CONCLUSION. This article presents experiences that are meant to help foster discussion as the wave of COVID-19 continues. Thoughtful leadership and careful continuous communication will help us minimize anxiety and frustration during this difficult time.

Purpose: The aim of this prospective study is to investigate the effectiveness and safety of CT-guided percutaneous cryoablation of intercostal nerves for the treatment of postthoracotomy pain syndrome (PTPS). Materials: In this IRB-approved HIPAA compliant single-center study, eighteen patients with refractory post thoracotomy pain were recruited prospectively to receive CT-guided cryoablation between 2009 to 2013. Percutaneous ablations were performed with a PerCryo 17R device. The median patient age was 65.5 years (50-80), and 33% of patients were female. Pain level on a visual analog scale (scores 0-10) was recorded before and immediately after the procedure, as well as at 1 week, 1, 2, 3, 6, 9 and 12 months after the procedure. Complications if any were documented. 6 patients received repeat treatment within the 12-month follow-up period, and their preprocedural pain scores were used for analysis at follow-up time after the repeat treatment.
Result(s): Mean pain levels were 9.2 (95% CI 8.7-9.8) before interventions, and 0.28 (95%CI -0.13-0.69), 3.8 (95%CI 2.2-5.4), 4.8 (95% CI 3.3-6.4), 5.8 (95%CI 4.3-7.3), 6.9 (95%CI 5.4-8.3), 7.9 (95%CI 6.4-9.4) and 8.4 (95%CI 7.0-9.7) immediately after interventions, and at 1 week, 1, 3, 6, 9 and 12 months afterward. A Wilcoxon rank-sum test were performed and showed a statically significantly decreased pain level immediately after until 9 months after the procedures (P = 0.0001-0.042), but not at 12 months (P = 0.206). No procedure related complications were observed.
Conclusion(s): Cryoneurolysis is a safe and effective treatment option for chronic intercostal pain control up to 9 months. Repeat therapy may be considered for longer pain control.
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Purpose: To describe our experience with lung cryoablation and factors impacting procedural outcomes. Materials: We performed a retrospective review of all percutaneous lung cryoablation patients done at a single institution between August 2017 and May 2019. Procedures were performed using computed tomographic guidance and triple freeze-thaw protocol. Complications and intraprocedural imaging features of the ice balls were recorded. Tumor progression was determined via World Health Organization guidelines. Overall survival was calculated using Kaplan-Meier analysis.
Result(s): A total of 39 patients (mean age, 75.1 years; range 40-94 years), 61.5% (25/39) of whom were female, underwent a total of 45 procedures. The mean follow-up time was 398.4 days (range, 34-746). The mean pre-ablation size of the lung cancer was 19.0 x 13.4 mm. 48.9% (22/45) of tumors were ground glass or part solid. An average of 1.3 probes (range, 1-3) were used for each case (1.4 probe per cm of tumor). 5 cases were performed with a round 2.1 cm diameter ice device, while 40 were performed with an ovoid 2.1 cm diameter device. The immediate post ablation zone measured an average of 28.0 x 21.2 mm (range, 9.4-62.5 mm). At 1-month follow-up, the ablation zone measured 29.3 x 19.3 mm (range, 14.3-47.0 mm). Pneumothorax was the most common complication seen in 46.7% (21/45) of cases. Chest tube placement was required in 33.3% (15/45) of cases. Local recurrence was seen in 6.7% (3/45) of lesions during the follow-up period. There were no 30-day mortalities; however, there were 6 deaths recorded (15.3%) during the study period. 83.3% (5/6) of the deaths were patients with solid tumors. Mean tumor size in these patients was 21.8 x 17.3 mm (range, 15.0-33.0 mm). Mean overall survival probability by Kaplan-Meier was 88.8% (SE: 0.05) at 1 year and 73.2% (SE: 1.4) at 2 years.
Conclusion(s): Lung cryoablation remains a safe and effective therapy option for patients with early stage malignant lung tumors, including both ground glass and part solid tumors. Current cryoablation technologies provide adequate ablation zones for tumors up to 2.0 cm.
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OBJECTIVE:Guideline-concordant follow-up of incidental lung nodules (ILNs) is suboptimal. We aimed to improve communication and tracking for follow-up of these common incidental findings detected on imaging examinations. METHODS:We implemented a process improvement program for reporting and tracking ILNs at a large urban academic health care system. A multidisciplinary committee designed, tested, and implemented a multipart tracking system in the electronic health record (EHR) that included Fleischner Society management recommendations for each patient. Plan-do-study-act cycles addressed gaps in the follow-up of ILNs, broken into phases of developing and testing components of the conceived EHR toolkit. RESULTS:The program resulted in standardized text macros with discrete categories and recommendations for ILNs, with ability to track each case in a work list within the EHR. The macros incorporated evidence-based guidelines and also input of collaborating clinical referrers in the respective specialty. The ILN macro was used 3,964 times over the first 2 years, increasing from 104 to over 300 uses per month. Usage spread across all subspecialty divisions, with nonthoracic radiologists currently accounting for 80% (56 of 70) of the radiologists using the system and 31% (1,230 of 3,964) of all captured ILNs. When radiologists indicated ILNs as warranting telephone communication to provider offices, completion was documented in 100% of the cases captured in the EHR-embedded tracking report. CONCLUSION/CONCLUSIONS:An EHR-based system for managing incidental nodules enables case tracking with exact recommendations, provider communication, and completion of follow-up testing. Future efforts will target consistent radiologist use of the system and follow-up completion.