True Margin Research Articles

How far are we off? Analyzing the accuracy of surgical margin relocation in the head and neck.

Positive surgical margin rates remain high in head and neck cancer surgery. Relocation is challenging given the complex, three-dimensional (3D) anatomy. Prospective, multi-institutional study to determine accuracy of head and neck surgeons and pathologists relocating margins on virtual 3D specimen models using written descriptions from pathology reports. Using 3D models of 10 head and neck surgical specimens, each participant relocated 20 mucosal margins (10 perpendicular, 10 shave). A total of 32 participants, 23 surgeons and 9 pathologists, marked 640 margins. Of the 320 marked perpendicular margins, 49.7% were greater than 1 centimeter from the true margin with a mean relocation error of 10.2 mm. Marked shave margins overlapped with the true margin a mean 54% of the time, with no overlap in 44 of 320 (13.8%) shave margins. Surgical margin relocation is imprecise and challenging even for experienced surgeons and pathologists. New communication technologies are needed.

MP47-01 LIMITATIONS OF PARENCHYMAL VOLUME ANALYSIS (PVA) FOR ESTIMATING SPLIT RENAL FUNCTION (SRF) & NEW BASELINE GFR (NBGFR) AFTER RADICAL NEPHRECTOMY (RN)

You have accessJournal of UrologyCME1 Apr 2023MP47-01 LIMITATIONS OF PARENCHYMAL VOLUME ANALYSIS (PVA) FOR ESTIMATING SPLIT RENAL FUNCTION (SRF) & NEW BASELINE GFR (NBGFR) AFTER RADICAL NEPHRECTOMY (RN) Kieran Lewis, Carlos Munoz-Lopez, Worapat Attawettayanon, João Pedro Emrich Accioly, Nityam Rathi, Zaeem Lone, Rebecca Campbell, Jihad Kaouk, Georges-Pascal Haber, Mohamad Eltemamy, Venkatesh Krishnamurthi, Robert Abouassaly, Christopher Weight, and Steven Campbell Kieran LewisKieran Lewis More articles by this author , Carlos Munoz-LopezCarlos Munoz-Lopez More articles by this author , Worapat AttawettayanonWorapat Attawettayanon More articles by this author , João Pedro Emrich AcciolyJoão Pedro Emrich Accioly More articles by this author , Nityam RathiNityam Rathi More articles by this author , Zaeem LoneZaeem Lone More articles by this author , Rebecca CampbellRebecca Campbell More articles by this author , Jihad KaoukJihad Kaouk More articles by this author , Georges-Pascal HaberGeorges-Pascal Haber More articles by this author , Mohamad EltemamyMohamad Eltemamy More articles by this author , Venkatesh KrishnamurthiVenkatesh Krishnamurthi More articles by this author , Robert AbouassalyRobert Abouassaly More articles by this author , Christopher WeightChristopher Weight More articles by this author , and Steven CampbellSteven Campbell More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003293.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Accurate prediction of NBGFR after RN can be important for counseling about RN vs. partial nephrectomy in some patients. SRF-based models have been shown to be most accurate for predicting NBGFR after RN, and PVA appears to be superior to nuclear renal scans (NRS) for this purpose. However, data regarding the potential limitations of PVA remain sparse. Our objective was to identify factors associated with PVA inaccuracy. METHODS: 241 RCC patients who underwent RN (2006-2021) with preop. CT/MRI and NRS were included for analysis. Our SRF-based model was: Predicted NBGFR=1.25(Global GFRPre-RN)(SRFContra), with SRF determined by PVA or NRS. Patients were grouped by PVA accuracy: PVAO (PVA over predicted NBGFR by >20%), PVAU (PVA under predicted NBGFR by >20%) and PVAA (PVA accurately predicted NBGFR). Accuracy of NRS was also studied in a similar manner. RESULTS: Six patients (2.5%) were excluded from PVA due to severely altered renal architecture (e.g. PCKD). PVA accurately predicted NBGFR for 83% (196/235) of patients and over/underpredicted NBGFR in 7% and 9%, respectively. NRS only accurately predicted NBGFR for 66% of patients and over/under predicted NBGFR in 22% and 13% of patients, respectively. PVAO had more patients with active/recent hydronephrosis compared to both PVAU /PVAA (29% vs 14% vs 10%, p=0.05). Prior renal infarct (p=0.01) and infiltrative renal mass (IRM) (p=0.002) were associated with PVA inaccuracy in both directions. In contrast, NRS inaccuracy was random and did not associate with hydronephrosis, prior renal infarct, or IRM (all p>0.3). Overall, 30% of patients fell into cohorts where accuracy of PVA was less reliable, but even in these situations PVA was non-inferior to NRS. CONCLUSIONS: PVA accuracy is reduced for IRMs likely due to difficulty distinguishing the true margins of the tumor and, in about 3% of patients, severe disruption of the architecture rendered PVA impossible (e.g. PCKD). Disease processes that distort the volume/function relationship, such as active/recent hydronephrosis, can lead to PVAO, because measured mass may not function optimally. Awareness of cohorts where PVA can be less accurate has clinical utility. However, even in these cohorts, PVA was still non-inferior to NRS, and it remains a cost effective tool for determining SRF/NBGFR. Further study of other processes that can affect the volume/function relationship, such as active or chronic pyelonephritis, or that can affect the degree of renal functional compensation, such as extremes of age, will be required. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e642 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kieran Lewis More articles by this author Carlos Munoz-Lopez More articles by this author Worapat Attawettayanon More articles by this author João Pedro Emrich Accioly More articles by this author Nityam Rathi More articles by this author Zaeem Lone More articles by this author Rebecca Campbell More articles by this author Jihad Kaouk More articles by this author Georges-Pascal Haber More articles by this author Mohamad Eltemamy More articles by this author Venkatesh Krishnamurthi More articles by this author Robert Abouassaly More articles by this author Christopher Weight More articles by this author Steven Campbell More articles by this author Expand All Advertisement PDF downloadLoading ...

Optical palpation for tumor margin assessment in breast-conserving surgery.

Intraoperative margin assessment is needed to reduce the re-excision rate of breast-conserving surgery. One possibility is optical palpation, a tactile imaging technique that maps stress (force applied across the tissue surface) as an indicator of tissue stiffness. Images (optical palpograms) are generated by compressing a transparent silicone layer on the tissue and measuring the layer deformation using optical coherence tomography (OCT). This paper reports, for the first time, the diagnostic accuracy of optical palpation in identifying tumor within 1 mm of the excised specimen boundary using an automated classifier. Optical palpograms from 154 regions of interest (ROIs) from 71 excised tumor specimens were obtained. An automated classifier was constructed to predict the ROI margin status by first choosing a circle diameter, then searching for a location within the ROI where the circle was ≥ 75% filled with high stress (indicating a positive margin). A range of circle diameters and stress thresholds, as well as the impact of filtering out non-dense tissue regions, were tested. Sensitivity and specificity were calculated by comparing the automated classifier results with the true margin status, determined from co-registered histology. 83.3% sensitivity and 86.2% specificity were achieved, compared to 69.0% sensitivity and 79.0% specificity obtained with OCT alone on the same dataset using human readers. Representative optical palpograms show that positive margins containing a range of cancer types tend to exhibit higher stress compared to negative margins. These results demonstrate the potential of optical palpation for margin assessment.

Reliability of biopsy margin status for basal cell carcinoma: a retrospective study.

The reporting of biopsy margin status for basal cell carcinoma (BCC) varies among dermatopathologists. For biopsy specimens with seemingly negative margins, the question arises if the tumor extends beyond the margin in unexamined sections. We sought to determine the reliability of negative margin status for BCC and identify if any factors were predictive of positive true margins. We examined BCC biopsy specimens initially determined to have negative margins after routine sectioning and re-evaluated the margin status after complete tissue block sectioning of the initial biopsy specimen was performed. Our findings remind clinicians of the limitations of margin assessment and provide impetus for dermatopathologists to consider modifying how margin status is reported.

SURG-07. DETECTION OF GLIOMA INFILTRATION AT THE TUMOR MARGIN USING QUANTITATIVE STIMULATED RAMAN SCATTERING MICROSCOPY

Abstract BACKGROUND Differentiating neoplastic tumor tissues from normal brain at the infiltrative tumor margin remains challenging. Stimulated Raman scattering microscopy (SRM) is a rapid, label-free technique that provides microscopic imaging of unprocessed tissues. However, it has never been studied as a tool to enhance extent of resection. METHODS In this single center study, patients with WHO II-IV gliomas undergoing surgical resection were included. Margin samples were taken with corresponding stereotactic coordinates. Each tumor margin sample was analyzed using (1) H&E, (2) SRM, and (3) immunohistochemical (IHC) stains for IDH1-R132H or p53. Specimens were imaged fresh with SRM, inked for orientation and placed in formalin for routine processing. Stained slides were scored by 3-neuro-pathologists using a semiquantitative 2-tiered scoring system for the presence or absence of residual tumor. SRM microscopy images were segmented into cellularity. The intraobserver measure of agreement between modalities for each pathologist was calculated using Cohen’s kappa. RESULTS A total of 31 patients and 179 margin specimens were acquired. Postoperative MRI confirmed that 169 (94%) of glioma margin sample coordinates were indeed at the tumor margins (10 of 179 were not true margins). All 10 samples which were not true margins were identified as having residual tumor by SRM. IHC semiquantitative scoring of margin specimen confirmed 72 of 128 samples (56%) had residual tumor. Similarly, H&E-scoring confirmed 82 of 169 samples (49%) and 82 of 167 samples (49%) by SRM-scoring had residual tumor. Intraobserver agreements between all 3 modalities confirmed agreement: IHC-SRM was near perfect (K-0.84, CI-0.750-0.94); IHC-H&E substantial, (K-0.67 CI-0.54-0.80); SRM-H&E agreement substantial (K-0.72 CI-0.62-0.83). Margin samples with residual tumor demonstrated higher tissue cellularity when compared with samples without tumor (p< 0.0001). CONCLUSIONS SRM allows for identification of residual microscopic disease at the infiltrative tumor margin and therefore may be a promising tool to enhance extent of resection.

COVID-19-Associated Coagulopathy: Safety and Efficacy of Prophylactic Anticoagulation Therapy in Hospitalized Adults with COVID-19

Background:COVID-19-associated coagulopathy increases mortality in patients with COVID-19 infection. The International Society of Thrombosis and Hemostasis (ISTH) has published a guidance document recommending thromboprophylaxis with low-molecular weight heparin (LMWH) for all hospitalized patients with COVID-19. Despite standard dose LMWH thromboprophylaxis, arterial and venous thrombotic events occur in up to 30-40% of COVID-19 patients admitted to the intensive care unit (ICU). It is not known if patients with coagulopathy from COVID-19 benefit from higher levels of prophylactic anticoagulation therapy. No data exist regarding the comparative safety or efficacy of intermediate dose versus standard prophylactic dose LMWH.Study Design and Methods:This is a multi-center, randomized, open-label study (NCT04360824) comparing standard prophylactic dose enoxaparin (40 mg SC daily if BMI < 30 kg/m2; 30 mg SC twice daily or 40 mg SC twice daily if BMI ≥ 30 kg/m2) versus intermediate-weight adjusted dose enoxaparin (1 mg/kg SC daily if BMI < 30 kg/m2 or 0.5 mg/kg SC twice daily if BMI ≥ 30 kg/m2) in hospitalized patients with laboratory-confirmed SARS-CoV-2 infection who are either admitted to an intensive care unit or have a modified ISTH Overt DIC score ≥ 3.Objectives:The primary endpoint is to compare all-cause 30-day mortality of patients treated with standard prophylactic dose versus intermediate-dose enoxaparin. The secondary endpoints are to determine whether the use of standard prophylactic dose versus intermediate dose enoxaparin impacts major bleeding, arterial thrombosis, venous thrombosis, time to intubation or transfusion of blood products. The exploratory endpoints are to determine the effects of SARS-CoV-2 infection on laboratory coagulation parameters to better understand the mechanism of COVID-19 coagulopathy compared to healthy control subjects; parameters include citrullinated histone H3 (H3Cit), a component of neutrophil extracellular traps. The null hypothesis is that intermediate dose enoxaparin (intervention arm) will have a mortality rate that is not less than standard prophylactic dose enoxaparin (standard of care arm). Assuming a true margin of 20%, a sample size of 82 patients in each arm of the study is required to have 80% power when testing for a difference.Baseline Data:Three centers are currently enrolling patients. As of August 1, 2020, we have enrolled 52 patients (28 males and 24 females) with a median age of 61 years (range 24-80). 51% were Caucasian, 36% Hispanic, and 16% other ethnicities. Median BMI was 31 kg/m2 (range 20-52). Baseline D-Dimer was elevated in 95% of participants with a median of 2.23 mg/mL (range 0.39-40.32). The majority of participants had normal baseline PT, PTT, and platelet levels. All patients had fibrinogen levels over 100 mg/dL with a median of 607 mg/dL. Plasma H3Cit was elevated significantly in patients with COVID-19 (n = 21) vs healthy control subjects (n = 10) (6.48 vs 1.09 ng/mL, P = 0.001).Conclusion:Baseline data for the first 52 patients enrolled confirm the presence of multiple risk factors for thrombosis such as elevated BMI, D dimer, and plasma markers of neutrophil extracellular traps. In contrast to initial reports from China, the prevalence of thrombocytopenia and hypofibrinogenemia was very low in our cohort. Hispanics represented 36% of our study population, compared with 19% of overall COVID-19 infections in the region, suggesting a higher severity of illness in this subpopulation. The enrollment of this trial is ongoing with the addition of sites that have larger African American populations. As safety and efficacy data mature, this study will help clarify the optimum dose of prophylactic enoxaparin to prevent COVID-19 associated coagulopathy.DisclosuresNo relevant conflicts of interest to declare.

Preliminary prediction for survival time of fuel rod under critical heat flux

In commercial water-cooled reactor safety analysis, the fuel rod is assumed to fail and release its fission gas inventory when it reaches critical heat flux (CHF). For this reason, CHF serves as a regulatory limit for all water-cooled reactors. However, according to existing in-pile experimental data, this assumption is conservative and may over-constrain the reactor core performance. With the advent of accident tolerant fuels (ATFs), particularly their ability to structurally withstand higher temperatures, the true margin to fuel failure after reaching CHF should be re-visited. To this end, preliminary fuel performance during CHF and Post-CHF is simulated and fuel rod survival time based on different cladding failure criteria is formulated. The post-CHF fuel performance is governed by cladding temperature, oxidation, pellet-clad mechanical interaction (PCMI) and hydride formation. The analysis includes impact of cladding temperature, fuel burnup and presence of Cr-coating as a near term ATF concept. The fuel performance analysis for fresh fuel implies that the cladding survival times of few days are possible and the cladding oxidation and plastic strain limit are the likely failure modes. For burned fuel, PCMI and hydride formation are the likely limiting failure modes that could decrease the survival time to less than a day. The addition of Cr coating reduces hydride formation and improves high temperature creep performance of the cladding and it can potentially prolong the survival times to several days. The estimated large survival times motivate further investigations, particularly, expansion of available data in areas of cladding mechanical performance and hydrogen pickup in the temperature range relevant to post-CHF film boiling regime to better inform the fuel performance predictions.

From Support Propagation to Belief Propagation in Constraint Programming

&#x0D; &#x0D; &#x0D; The distinctive driving force of constraint programming to solve combinatorial problems has been a privileged access to problem structure through the high-level models it uses. From that exposed structure in the form of so-called global constraints, powerful inference algorithms have shared information between constraints by propagating it through shared variables’ domains, traditionally by removing unsupported values. This paper investigates a richer propagation medium made possible by recent work on counting solutions inside constraints. Beliefs about individual variable-value assignments are exchanged between contraints and iteratively adjusted. It generalizes standard support propagation and aims to converge to the true marginal distributions of the solutions over individual variables. Its advantage over standard belief propagation is that the higher-level models featuring large-arity (global) constraints do not tend to create as many cycles, which are known to be problematic for convergence. The necessary architectural changes to a constraint programming solver are described and an empirical study of the proposal is conducted on its implementation. We find that it provides close approximations to the true marginals and that it significantly improves search guidance.&#x0D; &#x0D; &#x0D;

Negative predictive value of biopsy margins of dysplastic nevi: A single-institution retrospective review

Biopsies of dysplastic nevi processed by bread-loafing allow for limited margin assessment; however, reported biopsy margins often influence management. To evaluate the negative predictive value of biopsy margins of dysplastic nevi. A retrospective search of a single academic institution's pathology database was conducted to identify all biopsy specimens of dysplastic nevi between January 1, 2015, and December 31, 2017. Biopsy specimen margin assessments were compared with excision pathology reports to calculate negative predictive value and to assess the frequency of residual nevus on excision after positive biopsy margins. A total of 1245 dysplastic nevi from 934 patients were identified. Clear biopsy margins had a negative predictive value for the absence of residual nevus on excision of 87.3% for dysplastic nevi of moderate atypia or greater. Residual nevus was identified on excision in 29.41% of cases of dysplastic nevi of moderate atypia or greater when initial biopsy margins were positive. This was a retrospective, single-institution study. The calculations likely overestimate the true negative predictive value of biopsy margins because of processing of excision specimens by bread-loafing. This study provides additional evidence that reported biopsy margins are not representative of true margin status.

Systematic review on the utility of magnetic resonance imaging for operative management and follow-up for primary sarcoma-lessons from extremity sarcomas.

Primary sarcomas of the vertebral column affect roughly 5 in every million persons annually, of which half to one-third are malignant. Treatment of these lesions requires multimodal management, often employing attempts at en bloc resection of the lesion with negative margins. This may be facilitated using magnetic resonance imaging for preoperative margin planning, but current literature is lacking regarding the use of such imaging to accurately predict planned surgical margins. Here we review prior studies describing the use of magnetic resonance imaging for en bloc resection of sarcomas of the extremities to identify learning points for application to the treatment of spinal neoplasms. We conducted a systematic review of the PubMed and EMBASE literature. Included studies described the accuracy of MRI for preoperative evaluation of tumor margins, intraoperative guidance for en bloc resection, or post-operative evaluation of residual or recurrent disease. All included studies described patients treated for osseous or soft tissue sarcoma of the limbs. We found 1,705 unique references of which 27 met criteria for inclusion. Seven studies reported MR had an overall diagnostic accuracy of 93.6-96% for preoperative margin evaluation with non-contrast T1 most accurately reflecting true margins. In the nine articles reporting results of MR-guided resection, negative margins were achieved in 88.8-100% of cases with a closest margin of 2-4 mm. Eleven articles combined reported the accuracy of MR for residual disease or local recurrence, with a mean sensitivity and specificity of 71.7% and 79.3%, respectively for residual disease and 87.9% and 85.9%, respectively for local recurrence. The current literature for appendicular musculoskeletal sarcoma suggests that MR is highly accurate for defining tumor margins preoperatively, guiding osteotomy cuts intraoperatively, and documenting recurrence or residual disease. Further evidence is necessary to evaluate the degree to which it can accurately guide osteotomy planning for en bloc resection of vertebral primaries.

Surface-Enhanced Resonance Raman Scattering-Guided Brain Tumor Surgery Showing Prognostic Benefit in Rat Models.

Glioma is the most frequent form of malignant brain tumors. Surgical debulking is a major strategy for glioma treatment. However, there is a great challenge for the neurosurgeons to intraoperatively identify the true margins of glioma because of its infiltrative nature. Tumor residues or microscopic satellite foci left in the resection bed are the main reasons leading to early recurrence as well as poor prognosis. In this study, a surface-enhanced resonance Raman scattering (SERRS) probe was developed to intraoperatively guide glioma resection. In this probe, molecular reporters with absorptive maxima at the near-infrared wavelength range were covalently functionalized on the surface of gold nanostars. This SERRS probe demonstrated an ultrahigh sensitivity with a detection limit of 5.0 pM in aqueous solution. By the development of glioma xenografts in a mouse dorsal skin window chamber, extravasation of this probe from leaky tumor vasculature as functions of time and distance to tumor boundary was investigated. Importantly, the invasive margin of the tumor xenograft was demarcated by this probe with a high signal-to-background ratio. Preoperative magnetic resonance imaging (MRI) first defined the position of orthotopic glioma xenografts in the brain of rat models, and the craniotomy plan was designed. The brain tumor was then excised intraoperatively step-by-step with the assistance of a handheld Raman scanner till the Raman signals of the probe completely disappeared in the resection bed. Notably, longitudinal MRI showed that SERRS-guided surgery significantly reduced the tumor recurrence rate and improved the overall survival of rat models compared with the white light-guided surgery. Overall, this work demonstrates the prognostic benefit of SERRS-guided glioma surgery in animal models. Because delineation of tumor-invasive margins is a common challenge faced by the surgeons, this SERRS probe with a picomolar detection limit holds the promise in improving the surgical outcome of different types of infiltrated tumors.

Reliability-Based Design (RBD) For Everyone: (No Monte Carlo Simulation Required!)

In North America, the design of earth structures for transportation applications is most often carried out using load and resistance factor design (LRFD). In the U.S., the AASHTO LRFD Bridge Design Specifications are followed. In Canada, the primary code is the Canadian Highway Bridge Design Code. The premise behind LRFD is that when a limit state design equation is used with prescribed load and resistance factors, a minimum margin of safety, expressed as a reliability index b, or probability of failure, is assumed to be assured. Unless the design is at the point where the limit-state equation is satisfied, the true margin of safety in probabilistic terms is unknown. Furthermore, designers may have a choice of load and resistance models to use in a limit-state design equation. Because these models will have different accuracies, using different design models with the same load and resistance factors will result in different true margins of safety in probabilistic terms.

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation

Nipple-Sparing Mastectomy: Reliability of sub-areolar sampling and frozen section in predicting occult nipple involvement in breast cancer patients

IntroductionThe oncological safety of nipple-areolar complex (NAC) preservation is a concern in the mastectomies performed for cancer indication. The detection of tumor cells during the intraoperative frozen section examination (IE) of sub-areolar/nipple tissue (SAT) leads to the removal of NAC, but frequently the final histology of the nipple is negative for malignancy. This study aims to evaluate the accuracy of SAT examination in predicting occult NAC involvement in case of Nipple-Sparing Mastectomy (NSM). MethodsThe study includes 76 NSM. We evaluated the concordance between histopathologic features of frozen and paraffin-embedded SAT sections. Moreover, we examined the "true margin" (TM), defined as the measurement of the distance between the tumor margin and the edge of the SAT. A margin >1 mm was considered negative. ResultsIn 26/76 cases the IE of the SAT was positive. At the final histology, the NAC was negative in 57.7% of cases. The concordance between frozen and paraffin section examination of the SAT was 92.1%. The three false-positives were low-grade DCIS at the IE, and negative or DIN1a on permanent section. A negative TM seems to predict for a negative NAC (6/6). ConclusionsThe detection of a low-grade DCIS at the IE of the SAT may not be confirmed at the permanent section examination; we recommend caution in removing the NAC in these cases. The evaluation of the TM may improve the accuracy of SAT analysis in predicting occult NAC involvement; in our series, a TM wider than 1 mm correlates with a negative NAC.

The potential failure risk of the cone-beam computed tomography-based planning target volume margin definition for prostate image-guided radiotherapy based on a prospective single-institutional hybrid analysis

BackgroundThe purpose of this study was to evaluate the impact of markerless on-board kilovoltage (kV) cone-beam computed tomography (CBCT)-based positioning uncertainty on determination of the planning target volume (PTV) margin by comparison with kV on-board imaging (OBI) with gold fiducial markers (FMs), and to validate a methodology for the evaluation of PTV margins for markerless kV-CBCT in prostate image-guided radiotherapy (IGRT).MethodsA total of 1177 pre- and 1177 post-treatment kV-OBI and 1177 pre- and 206 post-treatment kV-CBCT images were analyzed in 25 patients who received prostate IGRT with daily localization by implanted FMs. Intrafractional motion of the prostate was evaluated between each pre- and post-treatment image with these two different techniques. The differences in prostate deviations and intrafractional motions between matching by FM in kV-OBI (OBI-FM) and matching by soft tissues in kV-CBCT (CBCT-ST) were compared by Bland-Altman limits of agreement. Compensated PTV margins were determined and compensated by references.ResultsMean differences between OBI-FM and CBCT-ST in the anterior to posterior (AP), superior to inferior (SI), and left to right (LR) directions were − 0.43 ± 1.45, − 0.09 ± 1.65, and − 0.12 ± 0.80 mm, respectively, with R2 = 0.85, 0.88, and 0.83, respectively. Intrafractional motions obtained from CBCT-ST were 0.00 ± 1.46, 0.02 ± 1.49, and 0.15 ± 0.64 mm, respectively, which were smaller than the results from OBI-FM, with 0.43 ± 1.90, 0.12 ± 1.98, and 0.26 ± 0.80 mm, respectively, with R2 = 0.42, 0.33, and 0.16, respectively. Bland-Altman analysis showed a significant proportional bias. PTV margins of 1.5 mm, 1.4 mm, and 0.9 mm for CBCT-ST were calculated from the values of CBCT-ST, which were also smaller than the values of 3.15 mm, 3.66 mm, and 1.60 mm from OBI-FM. The practical PTV margin for CBCT-ST was compensated with the values from OBI-FM as 4.1 mm, 4.8 mm, and 2.2 mm.ConclusionsPTV margins calculated from CBCT-ST might be underestimated compared to the true PTV margins. To determine a reliable CBCT-ST-based PTV margin, at least the systemic error Σ and the random error σ for on-line matching errors need to be investigated by supportive preliminary FM evaluation at least once.

Interaction of margin status and tumour burden determines survival after resection of colorectal liver metastases: A retrospective cohort study

PurposeWe sought to determine the impact of surgical margin status on overall survival (OS) and recurrence pattern stratified by tumor burden. Materials and methodsData were collected from patients undergoing resection for colorectal liver metastases (CRLM). Tumor burden was calculated according to a newly proposed Tumor Burden Score (TBS) system, defined as the distance from the origin on a Cartesian plane that incorporated maximum tumor size and number of liver lesions. Patients were divided into low tumor burden group and high tumor burden group accordingly, and the impact of resection margin on overall survival was examined. ResultsA total of 286 patients were available, among which R1 resection was observed in 88 patients. The median TBS for the entire cohort was 3.84. Metastases in the R1 group were characterized by more advanced disease and more complex resections. Compared with a R0 resection, a R1 resection offered an lower 5-year overall survival rate (46.8% vs. 22.1%, p = 0.001). Multivariate analysis identified R1 resection (p = 0.03), high TBS (p = 0.002), lymph nodes metastases (p = 0.003) and lymphovascular invasion (p = 0.03) of the primary colorectal tumor as the factors independently associated with worse survival. The survival benefit associated with negative margins was greater in patients with low TBS (55.7% vs. 21.7%, p = 0.021) than in patients with high TBS (31.8% vs. 24.5%, p = 0.116). R1 resection was associated with an increased true margin recurrence rate in patients with low TBS (32.3% vs. 13.4%; p = 0.014) and an increased risk of new intrahepatic metastases in patients with high TBS (43.9% vs. 26.7%; p = 0.034). ConclusionsNegative margin is an important determinant of survival. The impact of positive margins is more pronounced in patients with low tumor burden.

Medial iliosciatic plating via the Stoppa approach for complex acetabular fractures involving the posterior column

Objective To explore the clinical efficacy of medial iliosciatic plating via the Stoppa approach for complex acetabular fractures involving the posterior column. Methods Between February 2015 and February 2016, a total of 16 complex acetabular facture cases treated by the medial iliosciatic plate via the Stoppa approach were retrospectively analyzed in this study. This approach provided good exposure to a large region of the pelvis and acetabulum including pubis symphysis, pubic ramus, anterior and inner wall of acetabulum, quadrilateral surface, inner surface of posterior column, true pelvic margin, greater sciatic notch and sacroiliac articulation. The anterior and column was reduced and fixed by the anterior column plate and the medial iliosciatic plate. The screw direction and angle were adjusted according to the intraoperative X-ray. Surgical time, amount of bleeding, and relevant complications were recorded. The reduction of the posterior column fracture was evaluated by Matta scoring system on the plain X-ray of the pelvic post-surgery, and functional outcomes of the hip joint affected were evaluated one year post-surgery by the Merle d’Aubigne-Postel scoring system. All the cases were followed for at least 12 months. Results The reduction and fixation of the posterior column was accomplished in all the 16 patients. The average surgical time was 165.5 min (range, 130-270 min). The average blood loss was 1 245.6 ml (range, 600-5 600 ml). The intraoperative infusionof concentrated red blood cells averaged 6 units. According to the Matta scoring system, anatomical reduction was achieved in 12 cases, satisfactory reduction in 3, and poor reduction in one. The patients were followed from 12 to 22 months. According to the Merle d’Aubigne-Postel scoring system, there were 11 cases of excellent and 3 cases of good, yielding a good or excellent rate of 87.5%. The average Merle d’Aubigne-Postel score was 15.8 (range, 8-18). There were 1 case of external iliac vein rupture and 1 case of bladder rupture. Both were repaired during surgery. Superior gluteal artery rupture was found in 1 case and surgical ligation of the artery was performed during surgery. Conclusion In the treatment of complicated acetabular fractures involving the posterior column, the medial iliosciatic plating via the Stoppa approach is safe and effective, because it can provide a safe and sufficient operative field for surgeons to reduce and fix the posterior column fractures, and it leads to satisfactory recovery of the patients with limited complications. Key words: Acetabulum; Fractures, bone; Fracture fixation; Internal fixators

Is the routine microscopic examination of proximal and distal resection margins in colorectal cancer surgery justified?

Microscopic examination of the proximal and distal resection margins is part of the routine pathologic evaluation of colorectal surgical specimens removed for adenocarcinoma. Anastomotic donuts are frequently received and microscopically examined. We examined 594 specimens received over a period of 10 years and found only 3 cases of definitive direct involvement of a longitudinal margin by carcinoma. All 3 cases also showed tumor at the margin grossly. One case of margin involvement by adenocarcinoma was found in which the tumor was grossly 1.7 cm away; however, this finding was likely a tumor deposit, as the patient had diffuse metastatic disease. All 242 anastomotic donuts examined were free of carcinoma. Our study suggests that the proximal and distal margins of colorectal cancer specimens need not be examined microscopically in order to accurately assess margin status in cases where the tumor is at least 2 cm away from the margin of resection. Also, in cases in which anastomotic donuts are included with the case, these should be considered the true margins of resection and may be microscopically examined in place of the bowel specimen margins when margin examination is needed. Anastomotic donuts need not be examined if the tumor is more than 2 cm away from the margin. An exception to this rule would be cases of rectal adenocarcinoma where neoadjuvant therapy is given prior to surgery. In these cases, mucosal evidence of malignancy may be absent and microscopic examination of the margins is the only way to assure complete excision.

Gliomas: Motexafin Gadolinium-enhanced Molecular MR Imaging and Optical Imaging for Potential Intraoperative Delineation of Tumor Margins

To investigate the possibility of using motexafin gadolinium (MGd)-enhanced molecular magnetic resonance (MR) imaging and optical imaging to identify the true margins of gliomas. The animal protocol was approved by the institutional animal care and use committee. Thirty-six Sprague-Dawley rats with gliomas were randomized into six groups of six rats. Five groups were euthanized 15, 30, 60, 120, and 240 minutes after intravenous administration of 6 mg/kg of MGd, while one group received only saline solution as a control group. After craniotomy, optical imaging and T1-weighted MR imaging were performed to identify the tumor margins. One-way analysis of variance was used to compare optical photon intensity and MR imaging signal-to-noise ratios. Histologic analysis was performed to confirm the intracellular uptake of MGd by tumor cells and to correlate the tumor margins delineated on both optical and MR images. Both optical imaging and T1-weighted MR imaging showed tumor margins. The highest optical photon intensity (2.6 × 10(8) photons per second per mm(2) ± 2.3 × 10(7); analysis of variance, P < .001) and MR signal-to-noise ratio (77.61 ± 2.52; analysis of variance, P = .006) were reached at 15-30 minutes after administration of MGd, with continued tumor visibility at 2-4 hours. Examination with confocal microscopy allowed confirmation that the fluorescence of optical images and MR imaging T1 enhancement exclusively originated from MGd that accumulated in the cytoplasm of tumor cells. MGd-enhanced optical and MR imaging can allow determination of glioma tumor margins at the optimal time of 15-120 minutes after administration of MGd. Clinical application of these results may allow complete removal of gliomas in a hybrid surgical setting in which intraoperative optical and MR imaging are available.

Pinning out pathological specimens – are we risking an unnecessary escalation of treatment?

The importance of surgical resection margins is paramount, and it is vital that they are accurately delineated so that clinicians’ decisions about adjuvant treatment can be validated. Pathological specimens therefore are often pinned to aid orientation and maintain mucosal margins. However, in cadaveric resections of bovine tongues, pinning of the specimens significantly reduced the depth of tissue. In clinical practice, if results are affected by the fixation method and not based on the true margins, it could profoundly influence the use of adjuvant treatment in patients with cancer. Pinning the specimens with the mucosal surface against the board will maintain any theoretical benefit for the mucosa and does not compress the specimens.