Towards uniform case-identification criteria in observational studies on peripheral arterial disease: A scoping review

OBJECTIVE

The diagnosis peripheral arterial disease (PAD) is commonly applied for symptoms related to atherosclerotic obstructions in the lower extremity, though its clinical manifestations range from an abnormal Ankle Brachial Index to critical limb ischemia. Subsequently, management and prognosis of PAD vary widely with the disease stage. A critical aspect is how this variation is addressed in administrative databases-based studies that rely on diagnosis codes for case identification. The objective of this scoping review is to inventory the identification strategies used in studies on PAD that rely on administrative databases, to map the pros and cons of the ICD codes applied, and propose a first outline for a consensus framework for case identification in administrative databases.

METHODS

Registry-based reports published between 2010 to 2021 were identified through a systematic PubMed search. Studies were sub-categorized on the basis of the expressed study focus: claudication, critical limb ischemia, or general peripheral arterial disease and the ICD code(s) applied for case identification mapped.

RESULTS

Ninety studies were identified, of which thirty-six (40%) did not specify the grade of PAD studied. Forty-nine (54%) articles specified PAD grade studied. Five (6%) articles specified different PAD subgroups in methods and baseline demographics, but not in further analyses. Mapping of the ICD codes applied for case identification for studies that specified the PAD grade studied indicated a remarkable heterogeneity, overlap, and inconsistency.

CONCLUSION

A large proportion of registry-based studies on PAD fails to define the study focus. In addition, inconsistent strategies are used for PAD case-identification in studies that report a focus. These findings challenge study validity, and interfere with inter-study comparison. This scoping review provides a first initiative for a consensus framework for standardized case selection in administrative studies on PAD. It is anticipated that more uniform coding will improve study validity, and facilitate inter-study comparisons.

Diagnostic accuracy of the maximal systolic acceleration to detect peripheral arterial disease

BACKGROUND

Diagnosing peripheral arterial disease (PAD) can be challenging owing to medial arterial calcification (MAC) in patients with diabetes mellitus (DM) and chronic kidney disease (CKD). Current bedside tests, such as the ankle-brachial index and toe-brachial index, are often insufficient. The maximal systolic acceleration (ACCmax) is a velocimetric Doppler-derived parameter and could be a new promising test in the diagnostic workup of these patients. The primary aim of this study was to evaluate the diagnostic performance of the ACCmax to detect PAD.

METHODS

A retrospective cohort study was performed in a tertiary referral hospital. Patients ≥18 years old with suspected PAD who underwent ACCmax measurement(s) along with computed tomography angiography of the abdominal aorta and lower extremities (reference test) were eligible for inclusion. ACCmax measurements of the posterior tibial artery, anterior tibial artery and peroneal artery were collected. Diagnostic performance was assessed by using sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and area under the curve (AUC).

RESULTS

In total, 340 patients (618 limbs) were included. Approximately 40% suffered from DM and 30% had CKD. Diagnostic performance of the ACCmax to detect PAD for the posterior tibial artery showed a sensitivity of 90%, specificity of 93%, positive likelihood ratio of 12.83, and negative likelihood ratio of 0.11 (AUC, 0.953). For the anterior tibial artery, these results were 94%, 97%, 32.06, and 0.06 (same sequence as presented before) with an AUC of 0.984. The peroneal artery had a performance of 86%, 89%, 7.51, and 0.16, respectively (AUC, 0.893). Diagnostic accuracy of the ACCmax did not diminish in subgroup analysis for patients with DM or CKD.

CONCLUSIONS

The ACCmax showed excellent diagnostic performance to detect PAD, independent of patients prone to medial arterial calcification.

Therapeutic management of in-stent thrombosis after thoracic endovascular aortic repair for blunt thoracic aortic injury in a coronavirus disease 2019 patient

A 27-year-old man underwent thoracic endovascular aortic repair for blunt thoracic aortic injury. Fourteen months later, he presented with intermittent paraplegia, congestive heart failure, and a decline of kidney function as a result of high-grade aortic stenosis caused by in-stent thrombosis. He had a concurrent infection with coronavirus disease 2019. The patient was successfully treated using axillofemoral bypass, followed by stent relining 2 weeks later. The possible risk factors and the optimal therapeutic approach for in-stent thrombosis remain unknown, because only a limited number of cases describing this rare complication have been reported.

The association between sarcopenia and adverse outcomes after complex endovascular aortic repair

BACKGROUND

Sarcopenia is identified as a predictive factor for adverse outcomes after complex endovascular aortic repair (complex EVAR). Consensus on preferred parameters for sarcopenia is not yet reached. The current study compares three CT-assessed parameters on their association with adverse outcomes after complex EVAR.

METHODS

This was a single-center retrospective cohort study. Psoas Muscle Index (PMI), Skeletal Muscle Index (SMI), and lean psoas muscle area (LPMA) were examined by CT-segmentation. PMI, SMI, and LPMA were analyzed as continuous variables. In addition, cut-off values from previous research were used to diagnose patients as sarcopenic or non-sarcopenic. Outcomes were: all-cause mortality, major adverse events (MAE), length of hospital stay, and non-home discharge. A sub-analysis was made for severe sarcopenia; sarcopenia combined with low physical performance (gait speed, Time Up and Go test, Metabolic Equivalent of Task-score).

RESULTS

We included 101 patients. A higher PMI (HR=0.590, CI: 0.374-0.930, P=0.023), SMI (HR=0.453, CI: 0.267-0.768, P=0.003), and LPMA (HR=0.559, CI: 0.333-0.944, P=0.029) were associated with a lower risk of mortality. Sarcopenia based on cut-off values for PMI and LPMA was not significantly associated with survival. Sarcopenia based on SMI did present a higher mortality risk (P=0.017). A sub-analysis showed that severely sarcopenic patients were at even higher risk of mortality (P=0.036). None of the parameters were significantly associated with the other outcomes.

CONCLUSIONS

SMI had a slightly stronger association with mortality compared to PMI and LPMA. High-risk patients were selected by adding physical performance scores. Future research could focus on complex EVAR-specific PMI and LPMA cut-off values.

Persistent High Long-term Excess Mortality After Elective AAA Repair Especially in Women: A Large Population-based Study

OBJECTIVE

The aim of this time-trend analysis is to estimate long-term excess mortality and associated cardiovascular risk for abdominal aortic aneurysm (AAA) patients after elective repair while addressing the changes in AAA management and patient selection over time.

BACKGROUND

Despite the intensification of endovascular aneurysm repair and cardiovascular risk management, Swedish population data suggest that AAA patients retain a persistently high long-term mortality after elective repair. The question is whether this reflects suboptimal treatment, a changing patient population over time, or a national phenomenon.

METHODS

Nationwide time-trend analysis including 40,730 patients (87% men) following elective AAA repair between 1995 and 2017. Three timeframes were compared, each reflecting changes in the use of endovascular aneurysm repair and intensification of cardiovascular risk management. Relative survival analyses were used to estimate disease-specific excess mortality. Competing risk of death analysis evaluated the risk of cardiovascular versus noncardiovascular death. Sensitivity analysis evaluated the impact of changes in patient selection over time.

RESULTS

Short-term excess mortality significantly improved over time. Long-term excess mortality remained high with a doubled mortality risk for women (relative excess risk=1.87, 95% CI: 1.73-2.02). Excess mortality did not differ between age categories. The risk of cardiovascular versus noncardiovascular death remained similar over time, with a higher risk of cardiovascular death for women. Changes in patient population (ie, older and more comorbid patients in the latter period) marginally impacted excess mortality (2%).

CONCLUSIONS

Despite changes in AAA care, patients retain a high long-term excess mortality after elective repair with a persistent high cardiovascular mortality risk. In this, a clear sex - but no age - disparity stands out.

Use of Omniflow® II Biosynthetic Graft for the Treatment of Vascular Graft and Endograft Infections

BACKGROUND

Vascular graft/endograft infection is a rare but life-threatening complication of cardiovascular surgery and remains a surgical challenge. Several different graft materials are available for the treatment of vascular graft/endograft infection, each having its own advantages and disadvantages. Biosynthetic vascular grafts have shown low reinfection rates and could be a potential second best after autologous veins in the treatment of vascular graft/endograft infection. Therefore, the aim of our study was to evaluate the efficacy and morbidity of Omniflow® II for the treatment of vascular graft/endograft infection.

METHODS

A multicenter retrospective cohort study was performed to evaluate the use of Omniflow® II in the abdominal and peripheral region to treat vascular graft/endograft infection between January 2014 and December 2021. Primary outcome was recurrent vascular graft infection. Secondary outcomes included primary patency, primary assisted patency, secondary patency, all-cause mortality, and major amputation.

RESULTS

Fifty-two patients were included with a median follow-up duration of 26.5 (10.8-54.8) months. Nine (17%) grafts were implanted in intracavitary position and 43 (83%) in peripheral position. Most grafts were used as femoral interposition (n = 12, 23%), femoro-femoral crossover (n = 10, 19%), femoro-popliteal (n = 8, 15%), and aorto-bifemoral (n = 8, 15%) graft. Fifteen (29%) grafts were implanted extra-anatomically and 37 (71%) in situ. Eight patients (15%) presented with reinfection during follow-up, most of these patients received an aorto-bifemoral graft (n = 3, 38%). Intracavitary vascular grafting had a 33% (n = 3) reinfection rate and peripheral grafting 12% (n = 5; P = 0.025). The estimated primary patencies at 1, 2, and 3 years were 75%, 72%, and 72% for peripherally located grafts and 58% (at all timepoints) for intracavitary grafts (P = 0.815). Secondary patencies at 1, 2, and 3 years were 77% (at all timepoints) for peripherally located prostheses and 75% (at all timepoints) for intracavitary prostheses (P = 0.731). A significantly higher mortality during follow-up was observed in patients who received an intracavitary graft compared to patients with a peripheral graft (P = 0.003).

CONCLUSIONS

This study highlights the efficacy and safety of the Omniflow® II biosynthetic prosthesis for the treatment of vascular graft/endograft infection, in absence of suitable venous material, with acceptable reinfection, patency, and freedom of amputation prevalences, especially in replacing peripheral vascular graft/endograft infection. However, a control group with either venous reconstruction or another alternative graft is needed to make firmer conclusions.

Quantification of indocyanine green near-infrared fluorescence bowel perfusion assessment in colorectal surgery

BACKGROUND

Indocyanine green near-infrared fluorescence bowel perfusion assessment has shown its potential benefit in preventing anastomotic leakage. However, the surgeon's subjective visual interpretation of the fluorescence signal limits the validity and reproducibility of the technique. Therefore, this study aimed to identify objective quantified bowel perfusion patterns in patients undergoing colorectal surgery using a standardized imaging protocol.

METHOD

A standardized fluorescence video was recorded. Postoperatively, the fluorescence videos were quantified by drawing contiguous region of interests (ROIs) on the bowel. For each ROI, a time-intensity curve was plotted from which perfusion parameters (n = 10) were derived and analyzed. Furthermore, the inter-observer agreement of the surgeon's subjective interpretation of the fluorescence signal was assessed.

RESULTS

Twenty patients who underwent colorectal surgery were included in the study. Based on the quantified time-intensity curves, three different perfusion patterns were identified. Similar for both the ileum and colon, perfusion pattern 1 had a steep inflow that reached its peak fluorescence intensity rapidly, followed by a steep outflow. Perfusion pattern 2 had a relatively flat outflow slope immediately followed by its plateau phase. Perfusion pattern 3 only reached its peak fluorescence intensity after 3 min with a slow inflow gradient preceding it. The inter-observer agreement was poor-moderate (Intraclass Correlation Coefficient (ICC): 0.378, 95% CI 0.210-0.579).

CONCLUSION

This study showed that quantification of bowel perfusion is a feasible method to differentiate between different perfusion patterns. In addition, the poor-moderate inter-observer agreement of the subjective interpretation of the fluorescence signal between surgeons emphasizes the need for objective quantification.

Near-Infrared Fluorescence Imaging With Indocyanine Green to Predict Clinical Outcome After Revascularization in Lower Extremity Arterial Disease

Contemporary quality control methods are often insufficient in predicting clinical outcomes after revascularization in lower extremity arterial disease (LEAD) patients. This study evaluates the potential of near-infrared fluorescence imaging with indocyanine green to predict the clinical outcome following revascularization. Near-infrared fluorescence imaging was performed before and within 5 days following the revascularization procedure. Clinical improvement was defined as substantial improvement of pain free walking distance, reduction of rest- and/or nocturnal pain, or tendency toward wound healing. Time-intensity curves and 8 perfusion parameters were extracted from the dorsum of the treated foot. The quantified postinterventional perfusion improvement was compared within the clinical outcome groups. Successful near-infrared fluorescence imaging was performed in 72 patients (76 limbs, 52.6% claudication, 47.4% chronic limb-threatening ischemia) including 40 endovascular- and 36 surgical/hybrid revascularizations. Clinical improvement was observed in 61 patients. All perfusion parameters showed a significant postinterventional difference in the clinical improvement group (P-values <.001), while no significant differences were seen in the group without clinical improvement (P-values .168-.929). Four parameters demonstrated significant differences in percentage improvement comparing the outcome groups (P-values within .002-.006). Near-infrared fluorescence imaging has promising additional value besides clinical parameters for predicting the clinical outcome of revascularized LEAD patients.

Elastic Deformation Measurement Using Duplex Ultrasound for the Detection of High Aneurysm Sac Pressure Following EVAR

PURPOSE

To describe the concept of aortic elastic deformation (ED) measurement using duplex ultrasonography (DUS) as a tool for detection of high aneurysm sac pressure following endovascular aortic repair (EVAR).

TECHNIQUE

High aneurysm sac pressure, with or without proven endoleak, will result in a less compressible aneurysm. Using the dual image function in B-mode of the DUS device and a standardized amount of applied probe pressure, ED can be measured. It is defined as the percentage of deformation of the aneurysm sac on probe pressure application. We hypothesize that less ED of the aneurysm sac can be related with high aneurysm sac pressure and possibly the presence of clinically relevant endoleak. In this note, we describe the technical details of the procedure and report on the applicability and results of ED measurements in the framework of aortic aneurysm and EVAR follow-up in a cohort of 109 patients.

CONCLUSION

ED measurement is the first noninvasive pressure-based method in the quest to find a practical and reliable diagnostic tool to exclude high aneurysm sac pressure. In our patient cohort, patients with proven endoleak showed a smaller ED (less compressible), implying the presence of high aneurysm sac pressure. Further research should confirm whether ED measurement using DUS could reliably exclude endoleak after EVAR and further explore its potential for clinical application in EVAR follow-up.

CLINICAL IMPACT

For the first time, a simple, fast, and inexpensive diagnostic tool is presented in this study for detecting high sac pressure following EVAR. High sac pressure is typically caused by clinically significant endoleaks, which can have significant consequences. Currently, computed tomography scanning is the most common method used to identify and characterize endoleaks. However, measuring elastic deformation may potentially replace more invasive and expensive modalities, such as the computed tomography in the future.

Nutcracker syndrome: challenges in diagnosis and surgical treatment

BACKGROUND

Nutcracker syndrome (NCS) is an uncommon syndrome that presents with signs and symptoms caused by compression of the left renal vein (LRV), whereas 'nutcracker phenomenon' is solely used to refer to the anatomical configuration without clinical symptoms. Treatment for NCS may include non-operative management, open surgical intervention and in some instances endovascular stenting. We present a single-center retrospective case series of patients who presented with NCS managed with open surgical interventions.

METHODS

Single-center, retrospective review of patients managed from 2010-2021. We diagnosed NCS via a thorough clinical examination and additional cross-sectional imaging studies including magnetic resonance venography (MRV) and/or computed tomography venography (CTV). For further confirmation of the diagnosis, duplex ultrasound was frequently combined with contrast venography.

RESULTS

Thirty-eight patients were included in our study from 2010-2021 . Twenty-one (55.3%) patients presented with symptoms including flank pain, abdominal pain, hematuria and fatigue. The remaining 17 (44.7%) patients had nutcracker phenomenon. Within the group of patients diagnosed with NCS, 11 patients underwent LRV transposition. Symptoms related to NCS improved in 10 patients. Hematuria in one patient did not improve.

CONCLUSION

Transposition of the LRV is an effective treatment for NCS. Non-operative management is an option for those patients experiencing less severe or nonspecific clinical symptoms.

A quantitative assessment of perfusion of the gastric conduit after oesophagectomy using near-infrared fluorescence with indocyanine green

INTRODUCTION

Anastomotic leakage is a severe complication after oesophageal resection with gastric conduit reconstruction. Poor perfusion of the gastric conduit plays an important role in the development of anastomotic leakage. Quantitative near-infrared (NIR) fluorescence angiography with indocyanine green (ICG-FA) is an objective technique that can be used for perfusion assessment. This study aims to assess perfusion patterns of the gastric conduit with quantitative ICG-FA.

METHODS

In this exploratory study, 20 patients undergoing oesophagectomy with gastric conduit reconstruction were included. A standardized NIR ICG-FA video of the gastric conduit was recorded. Postoperatively, the videos were quantified. Primary outcomes were the time-intensity curves and nine perfusion parameters from contiguous regions of interest on the gastric conduit. A secondary outcome was the inter-observer agreement of subjective interpretation of the ICG-FA videos between six surgeons. The inter-observer agreement was tested with an intraclass correlation coefficient (ICC).

RESULTS

In a total of 427 curves, three distinct perfusion patterns were recognized: pattern 1 (steep inflow, steep outflow); pattern 2 (steep inflow, minor outflow); and pattern 3 (slow inflow, no outflow). All perfusion parameters were significantly different between the perfusion patterns. The inter-observer agreement was poor - moderate (ICC:0.345,95%CI:0.164-0.584).

DISCUSSION

This was the first study to describe perfusion patterns of the complete gastric conduit after oesophagectomy. Three distinct perfusion patterns were observed. The poor inter-observer agreement of the subjective assessment underlines the need for quantification of ICG-FA of the gastric conduit. Further studies should evaluate the predictive value of perfusion patterns and parameters on anastomotic leakage.

Learning Curve Analysis of Complex Endovascular Aortic Repair

BACKGROUND

When introducing new techniques, attention must be paid to learning curve. Besides quantitative outcomes, qualitative factors of influence should be taken into consideration. This retrospective cohort study describes the quantitative learning curve of complex endovascular aortic repair (EVAR) in a nonhigh-volume academic center and provides qualitative factors that were perceived as contributors to this learning curve. With these factors, we aim to aid in future implementation of new techniques.

METHODS

All patients undergoing complex EVAR in the Leiden University Medical Center (LUMC) between July 2013 and April 2021 were included (n = 90). Quantitative outcomes were as follows: operating time, blood loss, volume of contrast, hospital stay, major adverse events (MAE), 30-day mortality, and complexity. Patients were divided into 3 temporal groups (n = 30) for dichotomous outcomes. Regression plots were used for continuous outcomes. In 2017, the treatment team was interviewed by an external researcher. These interviews were reanalyzed for factors that contributed to successful implementation.

RESULTS

Length of hospital stay (P = 0.008) and operating time (P = 0.010) decreased significantly over time. Fewer cardiac complications occurred in the third group (3: 0% vs. 2: 17% vs. 1: 17%, P = 0.042). There was a trend of increasing complexity (P = 0.076) and number of fenestrations (P = 0.060). No significant changes occurred in MAE and 30-day mortality. Qualitative factors that, according to the interviewees, positively influenced the learning curve were as follows: communication, mutual trust, a shared sense of responsibility and collective goals, clear authoritative structures, mutual learning, and team capabilities.

CONCLUSIONS

In addition to factors previously identified in the literature, new learning curve factors were found (mutual learning and shared goals in the operating room (OR)) that should be taken into account when implementing new techniques.

Exploring the surgical personality

Surgery is a demanding field, requiring determination and emotional stability. This review explores the surgical personality, addressing international personality differences between surgical and non-surgical specialties. Across the globe, surgically-interested individuals (i.e., medical students, residents, surgeons) generally scored higher on conscientiousness, open mindedness, and extraversion, and lower on neuroticism compared to non-surgically-interested contemporaries. Extraversion was inversely correlated to burnout in surgical residents and open mindedness to reduced competence in giving feedback. Although additional region- and/or country-specific research is warranted, being or becoming a surgeon appears to correlate to personality traits such as high conscientiousness and low neuroticism.

Evaluation of the Angiosome Concept Using Near-Infrared Fluorescence Imaging with Indocyanine Green

BACKGROUND

The angiosome concept is defined as the anatomical territory of a source artery within all tissue layers. When applying this theory in vascular surgery, direct revascularization (DR) is preferred to achieve increased blood flow toward the targeted angiosome of the foot in patients with lower extremity arterial disease (LEAD). This study evaluates the applicability of the angiosome concept using quantified near-infrared (NIR) fluorescence imaging with indocyanine green (ICG).

METHODS

This study included patients undergoing an endovascular- or surgical revascularization of the leg between January 2019 and December 2021. Preinterventional and postinterventional ICG NIR fluorescence imaging was performed. Three angiosomes on the dorsum of the foot were determined: the posterior tibial artery (hallux), the anterior tibial artery (dorsum of the foot) and the combined angiosome (second to fifth digit). The angiosomes were classified from the electronic patient records and the degree of collateralization was classified based on preprocedural computed tomography angiography and/or X-ray angiography. Fluorescence intensity was quantified in all angiosomes. A subgroup analysis based on endovascular or surgical revascularized angiosomes, and within critical limb threatening ischemia (CLTI) patients was performed.

RESULTS

ICG NIR fluorescence measurements were obtained in 52 patients (54 limbs) including a total of 157 angiosomes (121 DR and 36 indirect revascularizations [IR]). A significant improvement of all perfusion parameters in both the directly and indirectly revascularized angiosomes was found (P-values between <0.001-0.007). Within the indirectly revascularized angiosomes, 90.6% of the scored collaterals were classified as significant. When comparing the percentual change in perfusion parameters between the directly and indirectly revascularized angiosomes, no significant difference was seen in all perfusion parameters (P-values between 0.253 and 0.881). Similar results were shown in the CLTI patients subgroup analysis, displaying a significant improvement of perfusion parameters in both the direct and indirect angiosome groups (P-values between <0.001 and 0.007), and no significant difference when comparing the percentual parameter improvement between both angiosome groups (P-values between 0.134 and 0.359). Furthermore, no significant differences were observed when comparing percentual changes of perfusion parameters in directly and indirectly revascularized angiosomes for both endovascular and surgical interventions (P-values between 0.053 and 0.899).

CONCLUSIONS

This study proves that both DR and IR of an angiosome leads to an improvement of perfusion. This suggests that interventional strategies should not only focus on creating in-line flow to the supplying angiosome. One can argue that the angiosome concept is not applicable in patients with LEAD.

The big five: Studying the surgical personality

BACKGROUND

The challenging nature of performing surgery on a personal and professional level demands specific characteristics. Personality traits play an important role in the nature and behavior of humans, which are studied using the five-factor model. Therefore, we investigated the personality of 3 surgical generations.

METHODS

Three distinct surgical populations were approached. The Dutch Big Five Inventory-2 was sent out online to 126 surgical residents (response: n = 69) and 104 surgeons (response: n = 60) in a teaching region in the Netherlands. Moreover, medical students interested in surgery were approached via the students' surgical society (response: n = 54). To obtain a normative Dutch population sample, the Longitudinal Internet studies for the Social Sciences panel was used, creating groups of the following age categories: 18 to 25 (n = 84), 26 to 35 (n = 101), 36 to 67 (n = 432). One-way analysis of variance with Bonferroni correction was used to assess differences in personality scores.

RESULTS

Individuals interested in surgery (ie, surgically-oriented medical students, surgical residents, and surgeons) generally scored significantly higher on extraversion, conscientiousness, agreeableness, open-mindedness, and lower on negative emotionality compared with the normative population sample. Across the surgical generations, surgical residents scored significantly lower on open-mindedness (3.60) compared with surgeons (3.92) and surgically-oriented medical students (3.82). Surgically-oriented medical students scored significantly higher in negative emotionality (2.44) compared with surgical residents (2.12) and surgeons (2.07).

CONCLUSION

Being a surgeon demands particular levels of determination and emotional stability. The surgical population shows a distinct personality pattern compared with the normative population, and more modest differences exist between persons in different stages of their surgical career.

Near-Infrared Fluorescence with Indocyanine Green to Assess Bone Perfusion: A Systematic Review

Background: Adequate perfusion of a bone flap is essential for successful reconstruction of osseous defects. Unfortunately, complications related to inadequate bone perfusion are common. Near-infrared fluorescence (NIRF) imaging enables intraoperative visualization of perfusion. NIRF has been investigated in reconstructive surgery to aid the surgeon in clinical perioperative assessment of soft tissue perfusion. However, little is known on the beneficial use of NIRF to assess bone perfusion. Therefore, the aim of this review was to search for studies evaluating NIRF to assess bone perfusion. Methods: A systematic review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, was performed. Studies up to October 2021 were included. We extracted data regarding the study population, size and design, reported objective fluorescence parameters and the methodology used for fluorescence imaging and processing. Results: Ten articles were included. Studies reported unevenly on the protocol used for NIRF imaging. Five studies reported objective parameters. Absolute and relative perfusion parameters and parameters derived from maximum fluorescence were reported. The clinical significance of these parameters has not been evaluated in humans. Conclusion: The evidence on bone perfusion as measured with NIRF is limited. More clinical studies are required.

Functional Performance After Complex Endovascular Aortic Repair: A Single-Center Retrospective Cohort Study

Purpose

Complex endovascular aortic repair (EVAR) procedures provide a treatment option for patients with aortic aneurysms involving visceral branches. Good technical results and short-term outcomes have been reported. Whether complex EVAR provides acceptable functional outcomes is not clear. The current study aims to describe postoperative functional outcomes in complex EVAR patients—an older and relatively frail patient group.

Materials and Methods

A single-center retrospective cohort study was performed, using data from a computerized database of consecutive patients who underwent complex EVAR in the Leiden University Medical Center (LUMC, The Netherlands) between July 2013 and September 2020. As of May 2017, patients scheduled for complex EVAR were referred to a geriatric care pathway to determine (Instrumental) Activities of Daily Living ((I)ADL) scores at baseline and, if informed consent was given, after 12 months. For the total patient group, adverse functional performance outcomes were: discharge to a nursing home and 12-month mortality. For the patients included in geriatric follow-up, the additional outcome was the incidence of functional decline (defined by a ≥2 point increase in (I)ADL-score) at 12-month follow-up

Results

Eighty-two patients underwent complex EVAR, of which 68 (82.9%) were male. Mean age was 73.3 years (SD=6.3). Within 30 days postsurgery, 6 patients (7.3%) died. Mortality within 12 months for the total patient group was 14.6% (n=12). After surgery, no patients had to be discharged to a nursing home. Fifteen patients (18.3%) were discharged to a rehabilitation center. Twenty-three patients gave informed consent and were included in geriatric follow-up. Five patients (21.7%) presented functional decline 12 months postsurgery and 4 patients had died (17.4%) by that time. This means that 39.1% of the patients in the care pathway suffered an adverse outcome.

Conclusion

To our knowledge, this is the only study that examined functional performance after complex EVAR, using a prospectively maintained database. No patients were newly discharged to a nursing home and functional performance results at 12 months are promising. Future multidisciplinary research should focus on determining which patients are most prone to deterioration of function, so that efforts can be directed toward preventing postoperative functional decline.

Perfusion Parameters in Near-Infrared Fluorescence Imaging with Indocyanine Green: A Systematic Review of the Literature

(1) Background: Near-infrared fluorescence imaging is a technique capable of assessing tissue perfusion and has been adopted in various fields including plastic surgery, vascular surgery, coronary arterial disease, and gastrointestinal surgery. While the usefulness of this technique has been broadly explored, there is a large variety in the calculation of perfusion parameters. In this systematic review, we aim to provide a detailed overview of current perfusion parameters, and determine the perfusion parameters with the most potential for application in near-infrared fluorescence imaging. (2) Methods: A comprehensive search of the literature was performed in Pubmed, Embase, Medline, and Cochrane Review. We included all clinical studies referencing near-infrared perfusion parameters. (3) Results: A total of 1511 articles were found, of which, 113 were suitable for review, with a final selection of 59 articles. Near-infrared fluorescence imaging parameters are heterogeneous in their correlation to perfusion. Time-related parameters appear superior to absolute intensity parameters in a clinical setting. (4) Conclusions: This literature review demonstrates the variety of parameters selected for the quantification of perfusion in near-infrared fluorescence imaging.

Risk assessment in aortic aneurysm repair by medical specialists versus the American College of Surgeons National Surgical Quality Improvement Program risk calculator outcomes

Objective

The aim of this online clinical vignette-based survey study was to compare risk assessments by vascular surgeons, anaesthesiologists and interventional radiologists involved in treating patients with aortic aneurysms in the Netherlands with the NSQIP risk calculator outcomes.

Methods

Participants, recruited using purposive sampling, provided their estimation of the likelihood of postoperative complications and events following aortic surgery in five fictional cases. These cases were subsequently scored using the NSQIP calculator. The risk assessments were statistically analysed using the ANOVA and student t-test.

Results

All participating specialists i.e. twelve vascular surgeons, ten interventional radiologists and ten anaesthesiologists completed the survey. In the vast majority of outcomes and vignettes, no significant differences were found between various specialists, whereas significant differences were found between the NSQIP risk calculator outcomes and the combined risk assessments of the specialists. Overall, specialist risk assessments differ from the NSQIP, but neither particularly higher nor lower compared to the risk calculator.

Conclusions

Risk assessment by vascular surgeons, anaesthesiologists and interventional radiologists differs significantly with NSQIP risk calculator outcomes, within the framework of both endovascular and open aortic aneurysm repair. Based on these results, implementing the NSQIP risk calculator in preoperative workup could be of added value in both patient planning as well as adequately informing patients for obtaining consent.

Cell-Based Tracers as Trojan Horses for Image-Guided Surgery

Surgeons rely almost completely on their own vision and palpation to recognize affected tissues during surgery. Consequently, they are often unable to distinguish between different cells and tissue types. This makes accurate and complete resection cumbersome. Targeted image-guided surgery (IGS) provides a solution by enabling real-time tissue recognition. Most current targeting agents (tracers) consist of antibodies or peptides equipped with a radiolabel for Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT), magnetic resonance imaging (MRI) labels, or a near-infrared fluorescent (NIRF) dye. These tracers are preoperatively administered to patients, home in on targeted cells or tissues, and are visualized in the operating room via dedicated imaging systems. Instead of using these 'passive' tracers, there are other, more 'active' approaches of probe delivery conceivable by using living cells (macrophages/monocytes, neutrophils, T cells, mesenchymal stromal cells), cell(-derived) fragments (platelets, extracellular vesicles (exosomes)), and microorganisms (bacteria, viruses) or, alternatively, 'humanized' nanoparticles. Compared with current tracers, these active contrast agents might be more efficient for the specific targeting of tumors or other pathological tissues (e.g., atherosclerotic plaques). This review provides an overview of the arsenal of possibilities applicable for the concept of cell-based tracers for IGS.

Stent Graft Sizing for Endovascular Abdominal Aneurysm Repair Using Open Source Image Processing Software

INTRODUCTION

An important step to reach a favorable outcome of abdominal endovascular aneurysm repair (EVAR) is preoperative sizing of the stent graft using computed tomography angiography (CTA) images of the abdominal aorta. A variety of costly image processing software options is available to obtain the necessary aortic measurements. A package that can be used for EVAR sizing is OsiriX Lite®-an open source, freely downloadable image processing option. This study assesses the concurrent validity of OsiriX Lite® when compared with commercially available 3Mensio Vascular® and Siemens Syngo.via®.

METHODS

CTA scans of 20 patients that underwent EVAR for abdominal aneurysm were selected, 10 elective and 10 ruptured. For each scan, 6 observers determined 20 parameters needed for proper stent graft sizing, 2 using Osirix Lite®, 3 using 3Mensio Vascular®, and 1 using Siemens Syngo.via®. For each parameter, an intraclass correlation coefficient (ICC) and a P-value were calculated. Interrater agreement was interpreted using the Koo and Li Guidelines. Time needed to perform EVAR planning was compared.

RESULTS

Overall interrater agreement between the 3 sizing options was found to be either "good" or "moderate" for 16 out of 20 parameters (80%). Time needed to perform EVAR planning was not significantly different for Osirix Lite® (568 sec) when compared with 3Mensio Vascular® (603 sec) or Siemens Syngo.via® (659 sec) with a P-value of 0.88.

CONCLUSIONS

The authors conclude that Osirix Lite® is an accurate and time-effective image processing option for preoperative sizing of an EVAR stent graft when matched to 3Mensio Vascular® and Siemens Syngo.via®.

Vascular Surgeons' Views on Ejaculation Disorders After Abdominal Aortic Surgery: Results of a Dutch Survey

BACKGROUND

The aim of this study is to evaluate vascular surgeons' knowledge and appreciation of ejaculatory dysfunction after open aortic aneurysm repair and the knowledge of possible nerve-preserving techniques.

METHODS

A Dutch national survey was conducted on sexual counseling in the case of open aortic surgery. For this purpose, a designed questionnaire based on a review of the literature in the field and on other surveys aiming to analyze care for sexual health by medical specialists was used.

RESULTS

The response rate was almost 60%. All responders were familiar with the occurrence of postoperative neurogenic complications. Sixty percent preoperatively informs their patients, but only one-third inquires whether such complications have occurred postoperatively. Most respondents estimated the incidence of postoperative neurogenic complications due to dissection of the periaortic tissues between 5% and 25%. Almost 75% take nerve anatomy into consideration when exposing the abdominal aorta, but only 29% mention the correct structures, and only 37% mention possible correct nerve-sparing techniques.

CONCLUSIONS

Dutch vascular surgeons are well aware of the occurrence of postoperative sexual disorders after infrarenal aortic reconstruction. A gap in knowledge of pathophysiology and anatomy exists. Furthermore, a significant part of vascular surgeons seems to lack skills in sexual counseling. Therefore, more education should be offered during vascular surgical training.

WHAT THIS ARTICLE ADDS

This article addresses iatrogenic neurogenic complications affecting sexual health following open aortic surgery. It opens the discussion on possible gaps in modern training of vascular surgeons and on sexual health in relation to postoperative quality of life and shared decision-making.

A systematic review of the use of near-infrared fluorescence imaging in patients with peripheral artery disease

OBJECTIVE

In the diagnosis of peripheral artery disease (PAD), the ankle-brachial index plays an important role. However, results of the ankle-brachial index are unreliable in patients with severe media sclerosis. Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) can provide information about tissue perfusion and has already been studied in oncologic, reconstructive, and cardiac surgery. For patients with PAD, this technique might give insight into skin perfusion and thereby guide treatment. We performed a systematic review of the literature on the use of NIR fluorescence imaging in patients with PAD.

METHODS

PubMed, MEDLINE, Embase, and Cochrane were searched for articles and abstracts on the application of NIR fluorescence imaging using ICG as fluorescent dye in patients with PAD. Our search strategy combined the terms "fluorescence," "ICG," or synonyms and "peripheral artery disease" or synonyms. The extracted data included fluorescence parameters and test characteristics for diagnosis of PAD.

RESULTS

Twenty-three articles were found eligible for this review using 18 different parameters for evaluation of the fluorescence signal intensity. NIR fluorescence imaging was used for four main indications: diagnosis, quality control in revascularization, guidance in amputation surgery, and visualization of vascular structures. For the diagnosis of PAD, NIR fluorescence imaging yields a sensitivity ranging from 67% to 100% and a specificity varying between 72% and 100%. Significant increases in multiple fluorescence parameters were found in comparing patients before and after revascularization.

CONCLUSIONS

NIR fluorescence imaging can be used for several indications in patients with PAD. NIR fluorescence imaging seems promising in diagnosis of PAD and guidance of surgeons in treatment, especially in patients in whom current diagnostic methods are not applicable. Further standardization is needed to reliably use this modality in patients with PAD.

Effects of Liver Resection on Hepatic Short-Chain Fatty Acid Metabolism in Humans

AIM

To determine whether acute loss of liver tissue affects hepatic short-chain fatty acid (SCFA) clearance.

METHODS

Blood was sampled from the radial artery, portal vein, and hepatic vein before and after hepatic resection in 30 patients undergoing partial liver resection. Plasma SCFA levels were measured by liquid chromatography-mass spectrometry. SCFA exchange across gut and liver was calculated from arteriovenous differences and plasma flow. Liver volume was estimated by CT liver volumetry.

RESULTS

The gut produced significant amounts of acetate, propionate, and butyrate (39.4±13.5, 6.2±1.3, and 9.5±2.6 μmol·kgbw-1·h-1), which did not change after partial hepatectomy (p = 0.67, p = 0.59 and p = 0.24). Hepatic propionate uptake did not differ significantly before and after resection (-6.4±1.4 vs. -8.4±1.5 μmol·kgbw-1·h-1, p = 0.49). Hepatic acetate and butyrate uptake increased significantly upon partial liver resection (acetate: -35.1±13.0 vs. -39.6±9.4 μmol·kgbw-1·h-1, p = 0.0011; butyrate: -9.9±2.7 vs. -11.5±2.4 μmol·kgbw-1·h-1, p = 0.0006). Arterial SCFA concentrations were not different before and after partial liver resection (acetate: 176.9±17.3 vs. 142.3±12.5 μmol/L, p = 0.18; propionate: 7.2±1.4 vs. 5.6±0.6 μmol/L, p = 0.38; butyrate: 4.3±0.7 vs. 3.6±0.6 μmol/L, p = 0.73).

CONCLUSION

The liver maintains its capacity to clear acetate, propionate, and butyrate from the portal blood upon acute loss of liver tissue.

A Novel Murine Model of Arteriovenous Fistula Failure: The Surgical Procedure in Detail

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient remodeling and intimal hyperplasia from which the exact pathophysiology remains unknown. In order to unravel the pathophysiology a murine model of AVF-failure was developed in which the configuration of the anastomosis resembles the preferred situation in the clinical setting. A model was described in which an AVF is created by connecting the venous end of the branch of the external jugular vein to the side of the common carotid artery using interrupted sutures. At a histological level, we observed progressive stenotic intimal lesions in the venous outflow tract that is also seen in failed human AVFs. Although this procedure can be technically challenging due to the small dimensions of the animal, we were able to achieve a surgical success rate of 97% after sufficient training. The key advantage of a murine model is the availability of transgenic animals. In view of the different proposed mechanisms that are responsible for AVF failure, disabling genes that might play a role in vascular remodeling can help us to unravel the complex pathophysiology of AVF failure.

Optimization of near-infrared fluorescence cholangiography for open and laparoscopic surgery

BACKGROUND

During laparoscopic cholecystectomy, common bile duct (CBD) injury is a rare but severe complication. To reduce the risk of injury, near-infrared (NIR) fluorescent cholangiography using indocyanine green (ICG) has recently been introduced as a novel method of visualizing the biliary system during surgery. To date, several studies have shown feasibility of this technique; however, liver background fluorescence remains a major problem during fluorescent cholangiography. The aim of the current study was to optimize ICG dose and timing for NIR cholangiography using a quantitative intraoperative camera system during open hepatopancreatobiliary (HPB) surgery. Subsequently, these results were validated during laparoscopic cholecystectomy using a laparoscopic fluorescence imaging system.

METHODS

Twenty-seven patients who underwent NIR imaging using the Mini-FLARE image-guided surgery system during open HPB surgery were analyzed to assess optimal dosage and timing of ICG administration. ICG was intravenously injected preoperatively at doses of 5, 10, and 20 mg, and imaged at either 30 min (early) or 24 h (delayed) post-injection. Next, the optimal doses found for early and delayed imaging were applied to two groups of seven patients (n = 14) undergoing laparoscopic NIR fluorescent cholangiography during laparoscopic cholecystectomy.

RESULTS

Median liver-to-background contrast was 23.5 (range 22.1–35.0), 16.8 (range 11.3–25.1), 1.3 (range 0.7–7.8), and 2.5 (range 1.3–3.6) for 5 mg/30 min, 10 mg/30 min, 10 mg/24 h, and 20 mg/24 h, respectively. Fluorescence intensity of the liver was significantly lower in the 10 mg delayed-imaging dose group compared with the early imaging 5 and 10 mg dose groups (p = 0.001), which resulted in a significant increase in CBD-to-liver contrast ratio compared with the early administration groups (p < 0.002). These findings were qualitatively confirmed during laparoscopic cholecystectomy.

CONCLUSION

This study shows that a prolonged interval between ICG administration and surgery permits optimal NIR cholangiography with minimal liver background fluorescence.

Near-infrared fluorescence imaging of both colorectal cancer and ureters using a low-dose integrin targeted probe

BACKGROUND

Irradical tumor resections and iatrogenic ureteral injury remain a significant problem during lower abdominal surgery. The aim of the current study was to intraoperatively identify both colorectal tumors and ureters in subcutaneous and orthotopic animal models using cRGD-ZW800-1 and near-infrared (NIR) fluorescence.

METHODS

The zwitterionic fluorophore ZW800-1 was conjugated to the tumor specific peptide cRGD (targeting integrins) and to the a-specific peptide cRAD. One nmol cRGD-ZW800-1, cRAD-ZW800-1, or ZW800-1 alone was injected in mice bearing subcutaneous HT-29 human colorectal tumors. Subsequently, cRGD-ZW800-1 was injected at dosages of 0.25 and 1 nmol in mice bearing orthotopic HT-29 tumors transfected with luciferase2. In vivo biodistribution and ureteral visualization were investigated in rats. Fluorescence was measured intraoperatively at several time points after probe administration using the FLARE imaging system.

RESULTS

Both subcutaneous and orthotopic tumors could be clearly identified using cRGD-ZW800-1. A significantly higher signal-to-background ratio was observed in mice injected with cRGD-ZW800-1 (2.42 ± 0.77) compared with mice injected with cRAD-ZW800-1 or ZW800-1 alone (1.21 ± 0.19 and 1.34 ± 0.19, respectively) when measured at 24 h after probe administration. The clearance of cRGD-ZW800-1 permitted visualization of the ureters and also generated minimal background fluorescence in the gastrointestinal tract.

CONCLUSIONS

This study appears to be the first to demonstrate both clear tumor demarcation and ureteral visualization after a single intravenous injection of a targeted NIR fluorophore. As a low dose of cRGD-ZW800-1 provided clear tumor identification, clinical translation of these results should be possible.

Intraoperative near-infrared fluorescence imaging of parathyroid adenomas with use of low-dose methylene blue

BACKGROUND

Intraoperative identification of parathyroid adenomas can be challenging. We hypothesized that low-doses methylene blue (MB) and near-infrared fluorescence (NIRF) imaging could be used to identify parathyroid adenomas intraoperatively.

METHODS

MB was injected intravenously after exploration at a dose of 0.5 mg/kg into 12 patients who underwent parathyroid surgery. NIRF imaging was performed using the Mini-FLARE imaging system.

RESULTS

In 10 of 12 patients, histology confirmed a parathyroid adenoma. In 9 of these patients, NIRF could clearly identify the parathyroid adenoma during surgery. Seven of these 9 patients had a positive preoperative (99m) Tc-sestamibi single photon emission CT (SPECT) scan. Importantly, in 2 patients, parathyroid adenomas could be identified only using NIRF.

CONCLUSION

This is the first study to show that low-dose MB can be used as NIRF tracer for identification of parathyroid adenomas, and suggests a correlation with preoperative (99m) Tc-sestamibi SPECT scanning.

Near-infrared fluorescence-guided resection of colorectal liver metastases

BACKGROUND

The fundamental principle of oncologic surgery is the complete resection of malignant cells. However, small tumors are often difficult to find during surgery using conventional techniques. The objectives of this study were to determine if optical imaging, using a contrast agent already approved for other indications, could improve hepatic metastasectomy with curative intent, to optimize dose and timing, and to determine the mechanism of contrast agent accumulation.

METHODS

The high tissue penetration of near-infrared (NIR) light was exploited by use of the FLARE (Fluorescence-Assisted Resection and Exploration) image-guided surgery system and the NIR fluorophore indocyanine green in a clinical trial of 40 patients undergoing hepatic resection for colorectal cancer metastases.

RESULTS

A total of 71 superficially located (< 6.2 mm beneath the liver capsule) colorectal liver metastases were identified and resected using NIR fluorescence imaging. Median tumor-to-liver ratio was 7.0 (range, 1.9-18.7) and no significant differences between time points or doses were found. Indocyanine green fluorescence was seen as a rim around the tumor, which is shown to be entrapment around cytokeratin 7-positive hepatocytes compressed by the tumor. Importantly, in 5 of 40 patients (12.5%, 95% confidence interval = 5.0-26.6), additional small and superficially located lesions were detected using NIR fluorescence, and were otherwise undetectable by preoperative computed tomography, intraoperative ultrasound, visual inspection, and palpation.

CONCLUSIONS

NIR fluorescence imaging, even when used with a nontargeted, clinically available NIR fluorophore, is complementary to conventional imaging and able to identify missed lesions by other modalities.

Vascular remodeling and intimal hyperplasia in a novel murine model of arteriovenous fistula failure

OBJECTIVE

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient outward remodeling and intimal hyperplasia (IH) formation from which the exact mechanism is largely unknown. A suitable animal model is of vital importance in the unraveling of the underlying pathophysiology. However, current murine models of AVF failure do not incorporate the surgical configuration that is commonly used in humans. Because the hemodynamic profile is one of the key determinants that play a role in vascular remodeling in the AVF, it is preferable to use this same configuration in an animal model. Here we describe a novel murine model of AVF failure in which the configuration (end-to-side) is similar to what is most frequently performed in humans.

METHODS

An AVF was created in 45 C57BL/6 mice by anastomosing the end of a branch of the external jugular vein to the side of the common carotid artery with interrupted sutures. The AVFs were harvested and analyzed histologically at days 7, 14, and 28. Identical veins of unoperated-on mice served as controls. Intravenous near-infrared fluorescent fluorophores were used to assess the patency of the fistula.

RESULTS

The patency rates at days 7, 14, and 28 days were 88%, 90%, and 50%, respectively. The mean circumference increased up to day 14, with a maximum 1.4-fold increase at day 7 compared with the control group (1.82 ± 0.7 vs 1.33 ± 0.3 mm; P = .443). Between days 14 and 28, the circumference remained constant (2.36 ± 0.2 vs 2.45 ± 0.2 mm; P = .996). At 7 days after surgery, the intimal area consisted mainly of an acellular layer that was structurally analogous to a focal adherent thrombus. Starting at 14 days after surgery, venous IH increased significantly compared with the unoperated-on group (14 days: 115,090 ± 22,594 μm(2), 28 days: 234,619 ± 47,828 μm(2), unoperated group: 2368 ± 1056 μm(2); P = .001 and P < .001, respectively) and was mainly composed of cells positive for α-smooth muscle actin. We observed leukocytes in the adventitial side of the vein at all time points.

CONCLUSIONS

Our novel murine AVF model, which incorporates a clinically relevant configuration of the anastomosis, displays similar features that are characteristic of failing human AVFs. Moreover, our findings suggest that coagulation and inflammation could both potentially play an important role in the formation of IH and subsequent AVF failure. Near-infrared fluoroscopy was a suitable alternative for conventional imaging techniques. This murine AVF-model is a valuable addition to the AVF animal model arsenal.

Image-guided hepatopancreatobiliary surgery using near-infrared fluorescent light

Background

Improved imaging methods and surgical techniques have created a new era in hepatopancreatobiliary (HPB) surgery. Despite these developments, visual inspection, palpation, and intraoperative ultrasound remain the most utilized tools during surgery today. This is problematic, though, especially in laparoscopic HPB surgery, where palpation is not possible. Optical imaging using near-infrared (NIR) fluorescence can be used for the real-time assessment of both anatomy (e.g., sensitive detection and demarcation of tumours and vital structures) and function (e.g., assessment of luminal flow and tissue perfusion) during both open and minimally invasive surgeries.

Methods

This article reviews the published literature related to preclinical development and clinical applications of NIR fluorescence imaging during HPB surgery.

Results

NIR fluorescence imaging combines the use of otherwise invisible NIR fluorescent contrast agents and specially designed camera systems, which are capable of detecting these contrast agents during surgery. Unlike visible light, NIR fluorescent light can penetrate several millimetres through blood and living tissue, thus providing improved detectability. Applications of this technique during HPB surgery include tumour imaging in liver and pancreas, and real-time imaging of the biliary tree.

Conclusions

NIR fluorescence imaging is a promising new technique that may someday improve surgical accuracy and lower complications.

Intraoperative near infrared fluorescence guided identification of the ureters using low dose methylene blue: a first in human experience

PURPOSE

Near infrared fluorescence imaging is a promising technique that offers real-time visual information during surgery. In this study we report the first clinical results to our knowledge of ureteral imaging using near infrared fluorescence after a simple peripheral infusion of methylene blue. Furthermore, we assessed the optimal timing and dose of methylene blue.

MATERIALS AND METHODS

A total of 12 patients who underwent lower abdominal surgery were included in this prospective feasibility study. Near infrared fluorescence imaging was performed using the Mini-FLARE™ imaging system. To determine optimal timing and dose, methylene blue was injected intravenously at doses of 0.25, 0.5 or 1 mg/kg after exposure of the ureters. Imaging was performed for up to 60 minutes after injection.

RESULTS

In all patients both ureters could be clearly visualized within 10 minutes after infusion of methylene blue. The signal lasted at least up to 60 minutes after injection. The mean signal-to-background ratio of the ureter was 2.27 ± 1.22 (4), 2.61 ± 1.88 (4) and 3.58 ± 3.36 (4) for the 0.25, 0.5 and 1 mg/kg groups, respectively. A mixed model analysis was used to compare signal-to-background ratios among dose groups and times, and to assess the relationship between dose and time. A significant difference among time points (p <0.001) was found. However, no difference was observed among dose groups (p = 0.811).

CONCLUSIONS

This study demonstrates the first successful use of near infrared fluorescence using low dose methylene blue for the identification of the ureters during lower abdominal surgery.

Ex vivo sentinel node mapping in colon cancer combining blue dye staining and fluorescence imaging

BACKGROUND

The sentinel lymph node procedure has been proposed to improve nodal staging in colon cancer patients. The aim of this study was to assess the added value of near-infrared (NIR) fluorescence imaging to conventional blue dye staining for ex vivo sentinel lymph node mapping.

MATERIALS AND METHODS

We included 22 consecutive patients undergoing surgery for colon cancer. After tumor resection, we submucosally injected a premixed cocktail of the near-infrared lymphatic tracer HSA800 and blue dye around the tumor for detection of sentinel lymph nodes. We used the Mini-FLARE imaging system for fluorescence imaging.

RESULTS

In 95% of patients, we identified at least one sentinel lymph node. Overall, a total of 77 sentinel lymph nodes were identified, 77 of which were fluorescent (100%) and 70 of which were blue (91%). Sentinel lymph nodes that were located deeper in the mesenteric fat could easily be located by NIR fluorescence. In four of five patients with lymph node metastases, tumor cells were present in at least one of the sentinel lymph nodes.

CONCLUSIONS

This study shows the successful use and added value of the NIR fluorescence tracer HSA800 to conventional blue dye for the ex vivo sentinel lymph node procedure in colon cancer.

Near-infrared fluorescence sentinel lymph node mapping of the oral cavity in head and neck cancer patients

OBJECTIVES

Elective neck dissection is frequently performed during surgery in head and neck cancer patients. The sentinel lymph node (SLN) procedure can prevent the morbidity of a neck dissection and improve lymph node staging by fine pathology. Near-infrared (NIR) fluorescence imaging is a promising technique to identify the sentinel lymph node (SLN) intraoperatively. This feasibility study explored the use of indocyanine green adsorbed to human serum albumin (ICG:HSA) for SLN mapping in head and neck cancer patients.

MATERIALS AND METHODS

A total of 10 consecutive patients with oral cavity or oropharyngeal cancer and a clinical N0 neck were included. After exposure of the neck, 1.6 mL of ICG:HSA (500 μM) was injected at four quadrants around the tumor. During the neck dissection, levels I-IV were measured for fluorescence using the Mini-FLARE imaging system.

RESULTS

In all 10 patients, NIR fluorescence imaging enabled visualization of one or more SLNs. A total of 17 SLNs were identified. The mean contrast between the fluorescent signal of the lymph nodes and of the surrounding tissue was 8.7±6.4. In 3 patients, of which 1 was false-negative, lymph node metastases were found. After administration of ICG:HSA, the average number of fluorescent lymph nodes significantly increased over time (P<0.001).

CONCLUSION

This study demonstrated feasibility to detect draining lymph nodes in head and neck cancer patients using NIR fluorescence imaging. However, the fluorescent tracer quickly migrated beyond the SLN to higher tier nodes.

Near-infrared fluorescence imaging of a solitary fibrous tumor of the pancreas using methylene blue

A 67-year-old female presented with unexplained abdominal pain. A contrast-enhanced computed tomography scan of the abdomen incidentally revealed a mass in the uncinate process of the pancreas. This mass was resected and based on histopathological findings, diagnosed as a solitary fibrous tumor (SFT) of the pancreas. A SFT is an extremely rare benign mesenchymal tumor that in 65% of cases affects the visceral pleura but can also affect extra-pleural sites. The intraoperative demarcation of pancreatic tumors, such as SFTs, can be challenging. In this report, the first clear intraoperative identification of a SFT of the pancreas in a human was shown using near-infrared fluorescence and methylene blue.

Randomized comparison of near-infrared fluorescence lymphatic tracers for sentinel lymph node mapping of cervical cancer

OBJECTIVE

Near-infrared fluorescence imaging using indocyanine green (ICG) has recently been introduced as a novel technique for sentinel lymph node (SLN) mapping in early-stage cervical cancer. Although preclinical research has shown that ICG adsorbed to human serum albumin (ICG:HSA) improves its performance, the need for HSA has not yet been confirmed in cervical cancer patients. The current randomized study aims to determine whether ICG:HSA offers advantages over using ICG alone.

METHODS

Eighteen consecutive early-stage cervical cancer patients scheduled to undergo pelvic lymphadenectomy were included. Prior to surgery, 1.6 mL of 500 μM ICG:HSA or 500 μM ICG alone was injected transvaginally in 4 quadrants around the tumor. The Mini-FLARE imaging system was used for intraoperative NIR fluorescence detection and quantitation.

RESULTS

SLNs were identified intraoperatively in 78% of the patients. Patient and tumor characteristics were equally distributed over both treatment groups. No significant difference in signal-to-background ratio (9.3 vs. 10.1, P=.72) or average number of detected SLNs (2.9 vs 2.7, P=.84) was found between the ICG:HSA group and the ICG alone group, respectively.

CONCLUSIONS

In conclusion, this double-blind, randomized trial showed no advantage of ICG:HSA over ICG alone for the SLN procedure in early-stage cervical cancer. Further optimization is required to improve the intraoperative detection rate.

Randomized comparison of near-infrared fluorescence imaging using indocyanine green and 99(m) technetium with or without patent blue for the sentinel lymph node procedure in breast cancer patients

Background

Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) has the potential to improve sentinel lymph node (SLN) mapping of breast cancer. We performed a randomized clinical trial to assess the value of blue dyes when used in combination with NIR fluorescence. We also preliminarily examined the possibility of performing SLN mapping without radiotracers.

Methods

Clinical trial subjects were 24 consecutive breast cancer patients scheduled to undergo SLN biopsy. All patients received standard of care using 99^m technetium-nanocolloid and received 1.6 mL of 500 μM ICG injected periareolarly. Patients were randomly assigned to undergo SLN biopsy with or without patent blue. To assess the need for radiocolloids to localize the SLN or SLNs, the surgeon did not use the handheld gamma probe during the first 15 min after the axillary skin incision.

Results

SLN mapping was successful in 23 of the 24 patients. No significant difference was found in signal-to-background ratio between the groups with and without patent blue (8.3 ± 3.8 vs. 10.3 ± 5.7, respectively, P = 0.32). In both groups, 100 % of SLNs were radioactive and fluorescent, and in the patent blue group, only 84 % of SLNs were stained blue. In 25 % of patients, the use of the gamma probe was necessary to localize the SLN within the first 15 min.

Conclusions

This study shows that there is no benefit of using patent blue for SLN mapping in breast cancer patients when using NIR fluorescence and 99^m technetium-nanocolloid. NIR fluorescence imaging outperformed patent blue in all patients.

Open versus laparoscopic left lateral hepatic sectionectomy within an enhanced recovery ERAS® programme (ORANGE II-trial): study protocol for a randomised controlled trial

Background

The use of lLaparoscopic liver resection in terms of time to functional recovery, length of hospital stay (LOS), long-term abdominal wall hernias, costs and quality of life (QOL) has never been studied in a randomised controlled trial. Therefore, this is the subject of the international multicentre randomised controlled ORANGE II trial.

Methods

Patients eligible for left lateral sectionectomy (LLS) of the liver will be recruited and randomised at the outpatient clinic. All randomised patients will undergo surgery in the setting of an ERAS programme. The experimental design produces two randomised arms (open and laparoscopic LLS) and a prospective registry. The prospective registry will be based on patients that cannot be randomised because of the explicit treatment preference of the patient or surgeon, or because of ineligibility (not meeting the in- and exclusion criteria) for randomisation in this trial. Therefore, all non-randomised patients undergoing LLS will be approached to participate in the prospective registry, thereby allowing acquisition of an uninterrupted prospective series of patients. The primary endpoint of the ORANGE II trial is time to functional recovery. Secondary endpoints are postoperative LOS, percentage readmission, (liver-specific) morbidity, QOL, body image and cosmetic result, hospital and societal costs over 1 year, and long-term incidence of incisional hernias. It will be assumed that in patients undergoing laparoscopic LLS, length of hospital stay can be reduced by two days. A sample size of 55 patients in each randomisation arm has been calculated to detect a 2-day reduction in LOS (90% power and α = 0.05 (two-tailed)).

The ORANGE II trial is a multicenter randomised controlled trial that will provide evidence on the merits of laparoscopic surgery in patients undergoing LLS within an enhanced recovery ERAS programme.

Trial registration

ClinicalTrials.gov NCT00874224.

Optimization of near-infrared fluorescent sentinel lymph node mapping for vulvar cancer

OBJECTIVES

Near-infrared fluorescence imaging has the potential to improve sentinel lymph node mapping in vulvar cancer, which was assessed in the current study. Furthermore, dose optimization of indocyanine green adsorbed to human serum albumin was performed.

STUDY DESIGN

Nine vulvar cancer patients underwent the standard sentinel lymph node procedure using (99m)technetium-nancolloid and patent blue. In addition, intraoperative imaging was performed after peritumoral injection of 1.6 mL of 500, 750, or 1000 μM of indocyanine green adsorbed to human serum albumin.

RESULTS

Near-infrared fluorescence sentinel lymph node mapping was successful in all patients. A total of 14 sentinel lymph nodes (average, 1.6; range, 1-4) were detected: 14 radioactive (100%), 11 blue (79%), and 14 near-infrared fluorescent (100%).

CONCLUSION

This study demonstrates feasibility and accuracy of sentinel lymph node mapping using indocyanine green adsorbed to human serum albumin. Considering safety, cost, and pharmacy preferences, an indocyanine green adsorbed to human serum albumin concentration of 500 μM appears optimal for sentinel lymph node mapping in vulvar cancer.

The clinical use of indocyanine green as a near-infrared fluorescent contrast agent for image-guided oncologic surgery

Optical imaging using near-infrared (NIR) fluorescence provides new prospects for general and oncologic surgery. ICG is currently utilised in NIR fluorescence cancer-related surgery for three indications: sentinel lymph node (SLN) mapping, intraoperative identification of solid tumours, and angiography during reconstructive surgery. Therefore, understanding its advantages and limitations is of significant importance. Although non-targeted and non-conjugatable, ICG appears to be laying the foundation for more widespread use of NIR fluorescence-guided surgery.

Optical image-guided surgery--where do we stand?

In cancer surgery, intra-operative assessment of the tumor-free margin, which is critical for the prognosis of the patient, relies on the visual appearance and palpation of the tumor. Optical imaging techniques provide real-time visualization of the tumor, warranting intra-operative image-guided surgery. Within this field, imaging in the near-infrared light spectrum offers two essential advantages: increased tissue penetration of light and an increased signal-to-background-ratio of contrast agents. In this article, we review the various techniques, contrast agents, and camera systems that are currently used for image-guided surgery. Furthermore, we provide an overview of the wide range of molecular contrast agents targeting specific hallmarks of cancer and we describe perspectives on its future use in cancer surgery.

Abstract 4140: Preclinical optimization and clinical translation of near-infrared fluorescence imaging of colorectal liver metastases using indocyanine green

Background: Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) is a promising technique to obtain real-time assessment of the extent and number of colorectal liver metastases during liver surgery. The current study aims to optimize dosage and timing of ICG administration.

Materials and methods: The Mini-FLARE imaging system was used for real-time identification of liver tumors in 18 rats. Liver tumors were measured at 24, 48, 72 or 96 hours after administration of 0.04, 0.08, or 0.16 mg ICG (0.13, 0.26 or 0.53 mg / kg, respectively). Guided by these results, intraoperative identification of liver metastases was performed in 12 patients undergoing liver resection. NIR fluorescence imaging was performed 24 or 48 hours after administration of 10 or 20 mg ICG (0.13 or 0.26 mg / kg, respectively). After intraoperative imaging, resection specimens were sliced to examine internal fluorescent patterns using the Mini-FLARE imaging system. Subsequently, frozen tissue sections were measured for fluorescence using the Nuance multispectral imager.

Results: Using NIR fluorescence imaging and ICG, all colorectal liver metastases (N = 34), could be identified in all rats. Average tumor-to-liver (TLR) ratio over all groups was 3.0 ± 1.2. Liver signal was lower in the 72 h time group compared to other time points, resulting in a significantly higher TLR. ICG dose did not significantly influence TLR, but a trend was found favoring the 0.08 mg dose group. Clinically, during intraoperative NIR fluorescence imaging, all superficially located metastases (&lt; 1 cm beneath liver capsule) were identified (N = 18). Average TLR was 11.1 ± 5.1 and no significant differences between time-points or doses were found. Liver signal was comparable to pre-injection signal at 24 to 48 hours post-injection, eliminating the need to test other time-points. In all patients, a fluorescent rim around the tumor was found, as described in earlier studies. Using fluorescence microscopy, this clear fluorescent rim was localized in stromal tissue in the transition area between tumor and normal liver tissue in all liver metastases. In this area, multiple cell types that are involved in tissue inflammation (e.g. granulocytes, lymphocytes) were found. In two patients, additional small (2 – 8 mm) metastases were identified using NIR fluorescence that were otherwise missed preoperatively and intraoperatively using only visual inspection and ultrasound.

Conclusions: This study demonstrates that colorectal cancer liver metastases can be clearly identified during surgery using ICG and the Mini-FLARE imaging system. NIR fluorescence imaging has the potential to improve intraoperative detection of in particular small and superficially located liver metastases and can therefore be seen as an addition to the conventional imaging modalities.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4140. doi:10.1158/1538-7445.AM2011-4140

Toward optimization of imaging system and lymphatic tracer for near-infrared fluorescent sentinel lymph node mapping in breast cancer

Background

Near-infrared (NIR) fluorescent sentinel lymph node (SLN) mapping in breast cancer requires optimized imaging systems and lymphatic tracers.

Materials and Methods

A small, portable version of the FLARE imaging system, termed Mini-FLARE, was developed for capturing color video and two semi-independent channels of NIR fluorescence (700 and 800 nm) in real time. Initial optimization of lymphatic tracer dose was performed using 35-kg Yorkshire pigs and a 6-patient pilot clinical trial. More refined optimization was performed in 24 consecutive breast cancer patients. All patients received the standard of care using ^99mTechnetium-nanocolloid and patent blue. In addition, 1.6 ml of indocyanine green adsorbed to human serum albumin (ICG:HSA) was injected directly after patent blue at the same location. Patients were allocated to 1 of 8 escalating ICG:HSA concentration groups from 50 to 1000 μM.

Results

The Mini-FLARE system was positioned easily in the operating room and could be used up to 13 in. from the patient. Mini-FLARE enabled visualization of lymphatic channels and SLNs in all patients. A total of 35 SLNs (mean = 1.45, range 1–3) were detected: 35 radioactive (100%), 30 blue (86%), and 35 NIR fluorescent (100%). Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN. Optimal injection dose of ICG:HSA ranged between 400 and 800 μM. No adverse reactions were observed.

Conclusions

We describe the clinical translation of a new NIR fluorescence imaging system and define the optimal ICG:HSA dose range for SLN mapping in breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-011-1566-x) contains supplementary material, which is available to authorized users.

Randomized, double-blind comparison of indocyanine green with or without albumin premixing for near-infrared fluorescence imaging of sentinel lymph nodes in breast cancer patients

Near-infrared (NIR) fluorescence imaging has the potential to improve sentinel lymph node (SLN) mapping in breast cancer. Indocyanine green (ICG) is currently the only clinically available fluorophore that can be used for SLN mapping. Preclinically, ICG adsorbed to human serum albumin (ICG:HSA) improves its performance as a lymphatic tracer in some anatomical sites. The benefit of ICG:HSA for SLN mapping of breast cancer has not yet been assessed in a clinical trial. We performed a double-blind, randomized study to determine if ICG:HSA has advantages over ICG alone. The primary endpoint was the fluorescence brightness, defined as the signal-to-background ratio (SBR), of identified SLNs. Clinical trial subjects were 18 consecutive breast cancer patients scheduled to undergo SLN biopsy. All patients received standard of care using (99m)Technetium-nanocolloid and patent blue. Patients were randomly assigned to receive 1.6 ml of 500 μM ICG:HSA or ICG that was injected periareolarly directly after patent blue. The Mini-Fluorescence-Assisted Resection and Exploration (Mini-FLARE) imaging system was used for NIR fluorescence detection and quantitation. SLN mapping was successful in all patients. Patient, tumor, and treatment characteristics were equally distributed over the treatment groups. No significant difference was found in SBR between the ICG:HSA group and the ICG alone group (8.4 vs. 11.3, respectively, P = 0.18). In both groups, the average number of detected SLNs was 1.4 ± 0.5 SLNs per patient (P = 0.74). This study shows that there is no direct benefit of premixing ICG with HSA prior to injection for SLN mapping in breast cancer patients, thereby reducing the cost and complexity of the procedure. With these optimized parameters that eliminate the necessity of HSA, larger trials can now be performed to determine patient benefit.

Near-infrared fluorescence imaging of liver metastases in rats using indocyanine green

BACKGROUND

Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) is a promising technique to obtain real-time assessment of the extent and number of colorectal liver metastases during surgery. The current study aims to optimize dosage and timing of ICG administration.

MATERIALS AND METHODS

Liver tumors were induced in 18 male WAG/Rij rats by subcapsular inoculation of CC531 rat colorectal cancer cells into three distinct liver lobes. Rats were divided in two groups: imaging after 24 and 48 h or 72 and 96 h after intravenous ICG administration. In each time group, rats were allocated to three dose groups: 0.04, 0.08, or 0.16 mg ICG. Intraoperative imaging and ex vivo measurements were performed using the Mini-FLARE imaging system and confirmed by fluorescence microscopy. Fluorescence intensity was quantified using the Mini-FLARE software and the difference between tumor signal and liver signal (tumor-to-liver ratio; TLR) was calculated.

RESULTS

In all 18 rats, all colorectal liver metastases (n = 34), some as small as 1.2 mm, were identified using ICG and the Mini-FLARE imaging system. Average tumor-to-liver ratio (TLR) over all groups was 3.0 ± 1.2. TLR was significantly higher in the 72 h time group compared with other time points. ICG dose did not significantly influence TLR, but a trend was found favoring the 0.08 mg dose group. Fluorescence microscopy demonstrated a clear fluorescent rim around the tumor.

CONCLUSIONS

This study demonstrates that colorectal cancer liver metastases can be clearly identified during surgery using ICG and the Mini-FLARE imaging system, with optimal timing of 72 h post-injection and an optimal dose of 0.08 mg (0.25 mg/kg) ICG. NIR fluorescence imaging has the potential to improve intraoperative detection of micrometastases and, thus, the completeness of resection.

Clinical translation of ex vivo sentinel lymph node mapping for colorectal cancer using invisible near-infrared fluorescence light

Background

Sentinel lymph node (SLN) mapping in colorectal cancer may have prognostic and therapeutic significance; however, currently available techniques are not optimal. We hypothesized that the combination of invisible near-infrared (NIR) fluorescent light and ex vivo injection could solve remaining problems of SLN mapping in colorectal cancer.

Methods

The FLARE imaging system was used for real-time identification of SLNs after injection of the NIR lymphatic tracer HSA800 in the colon and rectum of (n = 4) pigs. A total of 32 SLN mappings were performed in vivo and ex vivo after oncologic resection using an identical injection technique. Guided by these results, SLN mappings were performed in ex vivo tissue specimens of 24 consecutive colorectal cancer patients undergoing resection.

Results

Lymph flow could be followed in real-time from the injection site to the SLN using NIR fluorescence. In pigs, the SLN was identified in 32 of 32 (100%) of SLN mappings under both in vivo and ex vivo conditions. Clinically, SLNs were identified in all patients (n = 24) using the ex vivo strategy within 5 min after injection of fluorescent tracer. Also, 9 patients showed lymph node involvement (N1 disease). In 1 patient, a 3-mm mesenteric metastasis was found adjacent to a tumor-negative SLN.

Conclusions

The current pilot study shows proof of principle that ex vivo NIR fluorescence-guided SLN mapping can provide high-sensitivity, rapid, and accurate identification of SLNs in colon and rectum. This creates an experimental platform to test optimized, non-FDA-approved NIR fluorescent lymphatic tracers in a clinical setting.