Comparison study of intraoperative surface acquisition methods on registration accuracy for soft-tissue surgical navigation.

Purpose: To study the difference between rigid registration and nonrigid registration using two forms of digitization (contact and noncontact) in human in vivo liver surgery. Approach: A Conoprobe device attachment and sterilization process was developed to enable prospective noncontact intraoperative acquisition of organ surface data in the operating room (OR). The noncontact Conoprobe digitization method was compared against stylus-based acquisition in the context of image-to-physical registration for image-guided surgical navigation. Data from n=10 patients undergoing liver resection were analyzed under an Institutional Review Board-approved study at Memorial Sloan Kettering Cancer Center. Organ surface coverage of each surface acquisition method was compared. Registration accuracies resulting from the acquisition techniques were compared for (1) rigid registration method (RRM), (2) model-based nonrigid registration method (NRM) using surface data only, and (3) NRM with one subsurface feature (vena cava) from tracked intraoperative ultrasound (NRM-VC). Novel vessel centerline and tumor targets were segmented and compared to their registered preoperative counterparts for accuracy validation. Results: Surface data coverage collected by stylus and Conoprobe were 24.6%±6.4% and 19.6%±5.0%, respectively. The average difference between stylus data and Conoprobe data using NRM was -1.05 mm and using NRM-VC was -1.42 mm, indicating the registrations to Conoprobe data performed worse than to stylus data with both NRM approaches. However, using the stylus and Conoprobe acquisition methods led to significant improvement of NRM-VC over RRM by average differences of 4.48 and 3.66 mm, respectively. Conclusion: The first use of a sterile-field amenable Conoprobe surface acquisition strategy in the OR is reported for open liver surgery. Under clinical conditions, the nonrigid registration significantly outperformed standard-of-care rigid registration, and acquisition by contact-based stylus and noncontact-based Conoprobe produced similar registration results. The accuracy benefits of noncontact surface acquisition with a Conoprobe are likely obscured by inferior data coverage and intrinsic noise within acquisition systems.

Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model.

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

Unspoken Truths: Mental Health Among Academic Surgeons.

OBJECTIVE: To characterize the current state of mental health within the surgical workforce in the United States. BACKGROUND: Mental illness and suicide is a growing concern in the medical community; however, the current state is largely unknown. METHODS: Cross-sectional survey of the academic surgery community assessing mental health, medical error, and suicidal ideation. The odds of suicidal ideation adjusting for sex, prior mental health diagnosis, and validated scales screening for depression, anxiety, post-traumatic stress disorder (PTSD), and alcohol use disorder were assessed. RESULTS: Of 622 participating medical students, trainees, and surgeons (estimated response rate=11.4%-14.0%), 26.1% (141/539) reported a previous mental health diagnosis. In all, 15.9% (83/523) of respondents screened positive for current depression, 18.4% (98/533) for anxiety, 11.0% (56/510) for alcohol use disorder, and 17.3% (36/208) for PTSD. Medical error was associated with depression (30.7% vs. 13.3%, P <0.001), anxiety (31.6% vs. 16.2%, P =0.001), PTSD (12.8% vs. 5.6%, P =0.018), and hazardous alcohol consumption (18.7% vs. 9.7%, P =0.022). Overall, 13.2% (73/551) of respondents reported suicidal ideation in the past year and 9.6% (51/533) in the past 2 weeks. On adjusted analysis, a previous history of a mental health disorder (aOR: 1.97, 95% CI: 1.04-3.65, P =0.033) and screening positive for depression (aOR: 4.30, 95% CI: 2.21-8.29, P <0.001) or PTSD (aOR: 3.93, 95% CI: 1.61-9.44, P =0.002) were associated with increased odds of suicidal ideation over the past 12 months. CONCLUSIONS: Nearly 1 in 7 respondents reported suicidal ideation in the past year. Mental illness and suicidal ideation are significant problems among the surgical workforce in the United States.

The use of an educational time-out in thyroid and parathyroid surgery to move the needle in periprocedural education.

BACKGROUND: As surgical training shifts toward a competency-based paradigm, deliberate practice for procedures must be a point of focus. The purpose of this study was to assess the impact of an educational time-out intervention on educational experience and operative performance in endocrine surgery. METHODS: For 12 months, third-year general surgery residents used the educational time-out to establish an operative step of focus for thyroidectomy and parathyroidectomy procedures. Data were collected using the System for Improving and Measuring Procedural Learning application and post-rotation surveys. The Zwisch scale was used to classify supervision, with meaningful autonomy defined as passive help or supervision only. RESULTS: Eight residents and 3 attending surgeons performed the educational time-out for a total of 211 operations (93% completion rate). At the end of each rotation, there was improvement in the frequency of goal setting. There was strong agreement (90%) that the intervention strengthened the educational experience. For most cases (52%), the residents were rated at active help. Residents performed a median of 3/6 thyroidectomy steps at meaningful autonomy and a median of 2/5 parathyroidectomy steps at meaningful autonomy. Review of the qualitative data revealed that optimal feedback was provided in 46% of cases. CONCLUSION: The educational time-out strengthened educational experiences. Stepwise procedural data revealed the varying levels of supervision that exist within an operation. Broader implementation of this intervention could facilitate competency-based procedural education.

Fireside Chats: A Novel Wellness Initiative for Medical Students in the COVID-19 Era.

To supplement preexisting wellness programming for the surgery clerkship, a faculty surgeon at Vanderbilt initiated Fireside Chats (FC) in 2015. Inspired by Franklin Roosevelt's Depression-era radio broadcasts, FC features small group sizes, off-campus excursions, and a reimagining of the mentor-mentee relationship that eschews hierarchy in favor of deep, mutualistic connections in both personal and professional domains. Here we describe the rationale and implementation of FC and present survey data that demonstrate the warm reception of FC and its efficacy in stewarding the mental health of medical students. Moreover, unlike large group activities such as "learning communities," FC continues to meet in-person during COVID-19 and preserves social engagement opportunities that may alleviate pandemic-induced isolation and distress.

Effect of Donor Transaminase Levels on Graft Survival Following Liver Transplant: An Analysis of the Organ Procurement and Transplantation Network Database.

OBJECTIVES: Despite data showing equivalent outcomes between grafts from marginal versus standard criteria deceased liver donors, elevated donor transaminases constitute a frequent reason to decline potential livers. We assessed the effect of donor transaminase levels and other characteristics on graft survival. MATERIALS AND METHODS: We performed a retrospective cohort analysis of adult first deceased donor liver transplant recipients with available transaminase levels registered in the Organ Procurement and Transplantation Network database (2008-2018). We used Cox proportional hazards regression to determine the effects of donor characteristics on graft survival. RESULTS: Of 53 913 liver transplants, 52 158 were allografts from donors with low transaminases (≤ 500 U/L; group A) and 1755 were from donors with elevated transaminases (> 500 U/L; group B). Group A recipients were more likely to be hospitalized (P = .01) or in intensive care (P < .001) or to have mechanical assistance (P < .001), portal vein thrombosis (P = .01), diabetes mellitus (P = .003), or dialysis the week before liver transplant (P = .004). Multivariable analysis (controlling for recipient characteristics) showed donor risk factors of graft failure included diabetes mellitus (P < .001), donation after cardiac death (P < .001), total bilirubin > 3.5 mg/dL (P < .001), serum creatinine > 1.5 mg/dL (P = .01), and cold ischemia time > 6 hours (P < .001). Regional organ sharing showed lower risk of graft failure (P = .02). Donor transaminases > 500 U/L were not associated with graft failure (relative risk, 1.02; 95% CI, 0.91-1.14; P = .74). CONCLUSIONS: Donor transaminases > 500 U/L should not preclude the use of liver grafts. Instead, donor total bilirubin > 3.5 mg/dL and serum creatinine > 1.5 mg/dL appear to be associated with higher likelihood of graft failure after liver transplant.

Fat Quantification Imaging and Biophysical Modeling for Patient-Specific Forecasting of Microwave Ablation Therapy.

Computational tools are beginning to enable patient-specific surgical planning to localize and prescribe thermal dosing for liver cancer ablation therapy. Tissue-specific factors (e.g., tissue perfusion, material properties, disease state, etc.) have been found to affect ablative therapies, but current thermal dosing guidance practices do not account for these differences. Computational modeling of ablation procedures can integrate these sources of patient specificity to guide therapy planning and delivery. This paper establishes an imaging-data-driven framework for patient-specific biophysical modeling to predict ablation extents in livers with varying fat content in the context of microwave ablation (MWA) therapy. Patient anatomic scans were segmented to develop customized three-dimensional computational biophysical models and mDIXON fat-quantification images were acquired and analyzed to establish fat content and determine biophysical properties. Simulated patient-specific microwave ablations of tumor and healthy tissue were performed at four levels of fatty liver disease. Ablation models with greater fat content demonstrated significantly larger treatment volumes compared to livers with less severe disease states. More specifically, the results indicated an eightfold larger difference in necrotic volumes with fatty livers vs. the effects from the presence of more conductive tumor tissue. Additionally, the evolution of necrotic volume formation as a function of the thermal dose was influenced by the presence of a tumor. Fat quantification imaging showed multi-valued spatially heterogeneous distributions of fat deposition, even within their respective disease classifications (e.g., low, mild, moderate, high-fat). Altogether, the results suggest that clinical fatty liver disease levels can affect MWA, and that fat-quantitative imaging data may improve patient specificity for this treatment modality.

Primary Heptaic Melanoma or Melanoma of Unknown Primary?

Melanoma is the deadliest malignancy of the skin with an estimated 91 000 new annual cases with 9300 deaths in 2018. Metastatic disease generally presents with identification of known primary lesion; however, in 3.2% of patients, metastatic disease is discovered with unknown primary lesion/site. Rarely, melanoma is diagnosed as a primary lesion in visceral organs. Suspected primary hepatic melanoma is exceedingly rare and described in only a few case reports. We present the case of a 69-year-old Caucasian male who was found to have a hepatic melanoma on final pathology after resection of suspected primary hepatic malignancy. After a thorough postoperative workup, a primary lesion was unable to be identified. As such, a visceral primary lesion is considered.

Living vs deceased donor liver transplantation in cholestatic liver disease: An analysis of the OPTN database.

BACKGROUND: Living donor liver transplantation (LDLT) and donation after circulatory death (DCD) can expand the donor pool for cholestatic liver disease (CLD) patients. We sought to compare the outcomes of deceased donor liver transplant (DDLT) vs LDLT in CLD patients. METHODS: Retrospective cohort analysis of adult CLD recipients registered in the OPTN database who received primary LT between 2002 and 2018. Cox proportional hazards regression models with mixed effects were used to determine the impact of graft type on patient and graft survival. RESULTS: Five thousand, nine hundred ninety-nine DDLT (5730 donation after brain death [DBD], 269 DCD) and 912 LDLT recipients were identified. Ten-year patient/graft survival rates were DBD: 73.8%/67.9%, DCD: 74.7%/60.7%, and LDLT: 82.5%/73.9%. Higher rates of biliary complications as a cause of graft failure were seen in DCD (56.8%) than LDLT (30.5%) or DBD (18.7%) recipients. On multivariable analysis, graft type was not associated with patient mortality, while DCD was independently associated with graft failure (P = .046). CONCLUSION: DBD, DCD, and LDLT were associated with comparable overall patient survival. No difference in the risk of graft failure could be observed between LDLT and DBD. DCD can be an acceptable alternative to DBD with equivalent patient survival, but inferior graft survival likely related to the high rate of biliary complications.

A Preoperative Educational Time-Out is Associated with Improved Resident Goal Setting and Strengthens Educational Experiences.

OBJECTIVE: The purpose of this study was to assess the impact of a preoperative Educational Time-Out (ETO) with structured postoperative feedback on resident preoperative goal-setting and the educational experience of a clinical rotation. DESIGN: A preoperative ETO was developed during which trainees and faculty jointly identified an operative goal and discussed the trainee's operative autonomy. Postoperative feedback with a smartphone application was encouraged. From November 2016 to October 2017, the intervention was piloted with 1 surgical service. Outcomes included ETO completion rate, goal setting rate, and subjects' perception of the impact of the ETO on identification of performance deficits, trainee autonomy, and receipt of feedback. Data were analyzed using descriptive statistics. SETTING: This study was performed in an institutional hospital setting. PARTICIPANTS: Third-year general surgery residents and surgical faculty in the Department of Hepatobiliary Surgery and Liver Transplantation at Vanderbilt University Medical Center took part in the intervention. RESULTS: Seven residents and 7 attending surgeons participated in this study. Residents performed a median of 15 procurements during an average of 6.5 weeks each on service. The ETO completion rate was 83%. Resident-reported preoperative goal setting increased after the intervention (from 36% to 78%, p = 0.015). Subjects reported a positive impact of the intervention, with high resident agreement that the ETO helped identify deficits (82% median agreement), increased autonomy (82% median agreement), and increased receipt of feedback (84% median agreement). Residents and attendings agreed that the educational experience was stronger due to the ETO (median 81% and 77%, respectively). CONCLUSIONS: The ETO intervention improved rates of resident preoperative goal setting and strengthened perceived educational experiences. Resident participants also reported improvements in autonomy and rates of postoperative feedback. Broader implementation of this brief preoperative pause is an easy way to emphasize procedural education in the operating room.

Obesity in Liver Transplantation: A Risk Factor for Unplanned Reoperation and Prolonged Operative Time.

Selection of orthotopic liver transplantation (OLT) candidates is increasingly inclusive of patients with high BMI. We aim to characterize the influence of obesity on the surgical outcome measures of prolonged operative time and unplanned reoperation. We reviewed the records of obese and normal weight OLT recipients over a 10-year period from a single institution. Variables that trended (P < 0.1) with endpoints on univariate analysis were put into multivariate logistic regression models to determine independent association (P < 0.05). We included 195 obese and 171 normal weight OLT recipients in our study. On multivariate analysis, obesity was the only preoperative risk factor that trended with unplanned reoperation (odds ratio 2, P = 0.05). Similarly, only obesity remained independently associated with prolonged length of operation (defined as ≥275 minutes) on multivariate analysis (odds ratio 1.7, P = 0.04). In summary, obesity may make OLT more technically challenging and, thus, represents an independent risk factor for unplanned reoperations and prolonged operative time.

The Abdominal Transplant Surgery Workforce: Current state and future trends.

Transplant surgical workforce concerns have arisen in the last 5 years as reflected in challenges securing job opportunities for new fellows. The present survey was designed by the ASTS Membership and Workforce Committee to describe the current practice characteristics of transplant centers in order to estimate changes in the workforce. The survey questionnaire requested information about the transplant programs, the transplant surgeons involved in the program, and the estimated changes in the staffing of the program over the next 3 years. Seventy-one transplant centers responded from a total of 235 identified and queried (30.2% response rate), with median responding centers per UNOS region of 7 (IQR 4.5-8.5). The recruitment outlook for the next 3 years forecasts a positive inflow of surgeons at a 2:1 rate (incoming:leaving). The new female transplant workforce within the responding cohort has increased from 3.7% in 1980 to 18.4% in 2010. Currently, 13.1% of practicing US transplant surgeons in this survey are female which is higher than many other surgical specialties. This report represents the most up-to-date view into the abdominal transplant surgical workforce. The positive job recruitment outlook for transplant surgeons and the narrowing gender gap are new findings from this study.

Preoperative goal setting and perioperative communication in an academic training institution: Where do we stand?

BACKGROUND: We collected data regarding specific aspects of perioperative surgical education within our institution's Section of Surgical Sciences as a needs assessment. METHODS: Categorical general surgery residents and attending surgeons were queried regarding their perceptions of resident preoperative planning and perioperative communication. RESULTS: The overall response rate was 81%, with 35 resident and 54 faculty respondents. Residents reported selecting an operative learning objective a median of 50% (IQR 36-67) of the time, whereas attending surgeons perceived this to be the case a median of 26% (IQR 15-35) of the time (P < 0.001). The group reported median frequencies of 20% (IQR 9-31) for preoperative discussion of learning objectives, 12% (IQR 4-27) for preoperative discussion of competence and 27% (IQR 17-55) for postoperative debriefing. CONCLUSIONS: This study demonstrates deficits in resident goal setting and perioperative communication within our program, which are targets for future intervention. We share these results as a potential tool for other programs.

Characterization and correction of intraoperative soft tissue deformation in image-guided laparoscopic liver surgery.

Laparoscopic liver surgery is challenging to perform due to a compromised ability of the surgeon to localize subsurface anatomy in the constrained environment. While image guidance has the potential to address this barrier, intraoperative factors, such as insufflation and variable degrees of organ mobilization from supporting ligaments, may generate substantial deformation. The severity of laparoscopic deformation in humans has not been characterized, and current laparoscopic correction methods do not account for the mechanics of how intraoperative deformation is applied to the liver. We first measure the degree of laparoscopic deformation at two insufflation pressures over the course of laparoscopic-to-open conversion in 25 patients. With this clinical data alongside a mock laparoscopic phantom setup, we report a biomechanical correction approach that leverages anatomically load-bearing support surfaces from ligament attachments to iteratively reconstruct and account for intraoperative deformations. Laparoscopic deformations were significantly larger than deformations associated with open surgery, and our correction approach yielded subsurface target error of [Formula: see text] and surface error of [Formula: see text] using only sparse surface data with realistic surgical extent. Laparoscopic surface data extents were examined and found to impact registration accuracy. Finally, we demonstrate viability of the correction method with clinical data.

Surgery and Anesthesia Exposure Is Not a Risk Factor for Cognitive Impairment After Major Noncardiac Surgery and Critical Illness.

OBJECTIVE: The aim of this study was to determine whether surgery and anesthesia exposure is an independent risk factor for cognitive impairment after major noncardiac surgery associated with critical illness. SUMMARY OF BACKGROUND DATA: Postoperative cognitive impairment is a prevalent individual and public health problem. Data are inconclusive as to whether this impairment is attributable to surgery and anesthesia exposure versus patients' baseline factors and hospital course. METHODS: In a multicenter prospective cohort study, we enrolled ICU patients with major noncardiac surgery during hospital admission and with nonsurgical medical illness. At 3 and 12 months, we assessed survivors' global cognitive function with the Repeatable Battery for the Assessment of Neuropsychological Status and executive function with the Trail Making Test, Part B. We performed multivariable linear regression to study the independent association of surgery/anesthesia exposure with cognitive outcomes, adjusting initially for baseline covariates and subsequently for in-hospital covariates. RESULTS: We enrolled 1040 patients, 402 (39%) with surgery/anesthesia exposure. Median global cognition scores were similar in patients with surgery/anesthesia exposure compared with those without exposure at 3 months (79 vs 80) and 12 months (82 vs 82). Median executive function scores were also similar at 3 months (41 vs 40) and 12 months (43 vs 42). Surgery/anesthesia exposure was not associated with worse global cognition or executive function at 3 or 12 months in models incorporating baseline or in-hospital covariates (P > 0.2). Higher baseline education level was associated with better global cognition at 3 and 12 months (P < 0.001), and longer in-hospital delirium duration was associated with worse global cognition (P < 0.02) and executive function (P < 0.01) at 3 and 12 months. CONCLUSIONS: Cognitive impairment after major noncardiac surgery and critical illness is not associated with the surgery and anesthesia exposure but is predicted by baseline education level and in-hospital delirium.