Assessment Of Tissue Perfusion Research Articles

Hyperspectral Imaging (HSI) in Acute Mesenteric Ischemia to Detect Intestinal Perfusion Deficits

BackgroundAcute mesenteric ischemia is a life-threatening acute condition, which requires an interdisciplinary approach, including vascular recanalization and surgical treatment. Visual evaluation of intestinal perfusion might be misleading, and therefore, additional tools are necessary to reliably be able to resect the ischemic intestine. Hyperspectral imaging (HSI) has been shown to be feasible and safe for real-time assessment of tissue perfusion in visceral surgery but has never been used in cases of acute mesenteric ischemia. Therefore, we applied HSI in acute mesenteric ischemia to evaluate it for potential aid in the objectively discriminating ischemic and well-perfused intestine during explorative laparotomy. MethodsWe recorded HSI measurements in 11 cases of acute mesenteric ischemia during explorative laparotomy. We evaluated the recorded images for macroscopic visual perfusion quality and divided it into three groups. Of those three groups, we calculated and compared the HSI indexes of tissue saturation, near-infrared perfusion index, organ hemoglobin index, and tissue water index, as well as the reflectance spectra. ResultsWe found significant differences in tissue saturation (0.7% versus 0.45%; P = 0.002) and near-infrared perfusion index (0.58 versus 0.23; P < 0.001) in poorly perfused intestinal segments compared with the viable intestine. Furthermore, we could detect an increasing peak at 630 nm of the reflectance spectra in less viable tissues, indicating a maximum in necrotic tissues. We attributed this peak to an increase in met-hemoglobin content in necrotic tissues, which is supported by the increase in the HSI organ hemoglobin index. ConclusionsHSI is able to discriminate tissue perfusion in acute mesenteric ischemia reliably and therefore might be helpful for resection. In addition, HSI gives information on tissue viability via reflectance spectra.

Abstract 159: Deformity After Prepectoral Versus Subpectoral Implant-based Breast Reconstruction: A Clinical Outcomes And Differential Costs Analysis

Purpose: Prepectoral implant-based breast reconstruction after mastectomy has regained popularity over subpectoral implant placement in recent years. With the advent of novel tissue replacement matrices and tissue perfusion assessment technologies, prepectoral implant placement has been shown to confer multiple advantages over subpectoral placement, such as reduced animation deformity, decreased pain, and improved muscular function. However, prepectoral implant placement does carry certain disadvantages such as contour deformity and rippling. This study evaluated deformity and revision surgery after prepectoral versus subpectoral breast reconstruction in post-mastectomy patients. Methods: This was an Institutional Review Board-approved retrospective analysis of mastectomy patients undergoing implant-based reconstruction at our institution between October 2016 and July 2019. Medical records were reviewed for patients’ clinical/demographic characteristics, surgeries, outcomes/revisions, and surgical charges. Two-tailed chi square tests and Student’s t test analyses were used where appropriate to compare prepectoral and subpectoral implant groups. Hierarchical multivariate regression was used to generate crude and adjusted odds ratios and 95 percent confidence intervals for outcomes data. The two-tailed threshold for statistical significance was set at p values < 0.05. Results: One-hundred-eighty patients (296 breasts) met inclusion criteria during the study period, of whom, 76 (42.2%) received prepectoral implants and 104 (57.8%) received subpectoral implants. Mean follow-up was 212 days for patients with prepectoral implants and 203 days for subpectoral implants. After adjusting for clinical and demographic factors, a significantly-greater proportion of prepectoral implants developed skin rippling/wrinkling when compared to subpectorally-placed implants (46.5% versus 10.4%, p<0.0001). Similarly, prepectorally-placed implants demonstrated significantly-higher rates of superior pole contour deformity (59.4% versus 38.0%, p=0.02) than subpectoral implants. However, adjusted capsular contracture rates were similar between prepectoral and subpectoral implant cohorts. A significantly-greater proportion of patients with prepectoral implants received fat grafting upon initial implant placement (75.4% versus 37.8%, p<0.0001) as well as revision fat grafting (78.3% versus 42.17%, p=0.03). The mean number of revision surgeries for prepectoral implants was 1.4 (standard deviation: 0.8), which was significantly greater than the mean number of revision surgeries for subpectoral implants was 0.9 (standard deviation: 0.5; p=0.001). Total revision surgery(ies) costs were greater in patients with prepectoral implants than those with subpectoral implants, though this difference reached borderline significance ($3154 versus $1636 respectively, p=0.05). Lastly, upon multivariate hierarchical regression of individual breasts adjusting for anatomic placement of the implant (prepectoral versus subpectoral), lower body mass index independently predicted prepectoral implant contour deformity/rippling (odds ratio: 1.5, 95% confidence interval 1.2-1.8, p=0.02). Conclusion: In our cohort, prepectoral implants were associated with greater postoperative rippling/contour deformity and revision costs than subpectoral implants. Such information could help inform decision-making regarding breast reconstruction, when weighed against previous data demonstrating improved quality of life/decreased pain and narcotic-use following prepectoral placement. Further study is required to comprehensively evaluate cost-effectiveness of prepectoral versus subpectoral implant-based reconstruction, taking into consideration both long-term quality of life and costs.

Assessment of tissue perfusion and vascular function in mice by scanning laser Doppler perfusion imaging

Post-occlusive reactive hyperemia (PORH) is a key feature of physiological vasomotion to appropriately match the supply/demand ratio of tissues. This adaptive mechanism is severely disturbed in endothelial dysfunction with a reduced flow-mediated dilation (FMD). Reduced PORH and FMD are powerful prognostic risk factors in cardiovascular diseases. While these parameters are frequently determined in human beings, comparable methods applicable to mouse models are sparse. We aimed to evaluate the applicability and accuracy of scanning laser Doppler perfusion imaging (LDPI) to measure PORH in the mouse hindlimb. Changes in mean perfusion in response to vasoactive drugs and PORH (assessed by scanning LDPI) were compared with changes in diameter and blood flow in the femoral artery, as assessed by high-resolution ultrasound. We found that the measured LDPI signal significantly correlated with changes of inflow into the femoral artery. Vasodilation induced by administration of nitroglycerine and acetylcholine increased vessel diameter, blood flow and mean perfusion, while vasoconstriction following administration of epinephrine decreased all three parameters. PORH was induced by temporal occlusion of the femoral artery with an external cuff. During occlusion, mean perfusion decreased to a condition of zero-perfusion and release of the cuff induced an immediate increase in blood flow that was followed by femoral artery dilation driving PORH/perfusion. Surgical removal of the femoral artery decreased mean perfusion to a zero-perfusion level and fully abolished PORH. Importantly, the measurement of the PORH response by scanning LDPI is highly reproducible as determined by repeated measurements and intra/interobserver variation analysis. Last, we found that the PORH response was dependent on nitric oxide synthase and cyclooxygenase and declined with age. Thus, we here provide novel and robust non-invasive methods to serially measure tissue perfusion at baseline and during physiological and pharmacological modulation of vasomotor tone in the hindlimb of mice. The application of these LDPI scanning and ultrasound-based methods may be useful for testing the effects of drugs affecting vasomotor function or future elucidation of mechanisms leading to vasomotor dysfunction in mice in vivo.

Indocyanine Green Angiography in Breast Reconstruction: Utility, Limitations, and Search for Standardization.

A comprehensive literature search of articles pertaining to ICGA in breast reconstruction surgery was performed. The overall findings of the articles are outlined here by surgical procedure: skin-sparing and nipple-sparing mastectomy, implant-based reconstruction, and autologous reconstruction. Overall, there were 133 articles reviewed, describing the use of ICGA in breast reconstruction surgery. We found that ICGA can provide valuable information that aids in flap design, anastomotic success, and perfusion assessment. We also included example photographs and videos of ICGA use at our institution. ICGA can reduce postoperative tissue loss and aid in intraoperative flap design and inset. Despite the benefits of ICGA, its technical use and interpretation have yet to be standardized, limiting its widespread acceptance.

Value of Indocyanine Green Angiography to Guide Wound Management and Prevent Necrosis in a Robotic Surgical Procedure.

Background: Inguinal lymph node dissection is performed in penile cancers and has a high complication rate with mostly wound-related complications. This case study demonstrates the use of robotic technique, tissue perfusion assessment, and negative pressure wound dressing to minimize wound-related complications. Case Presentation: A 67-year-old Maltese man was diagnosed with squamous cell carcinoma (SCC) in situ on biopsy of a self-detected penile lump. The patient underwent a partial penectomy and histopathology report confirmed moderately differentiated SCC with clear surgical margins. A positron emission tomography/CT scan was performed preoperatively, which showed several nodes in the right inguinal region with increased metabolic activity and nonspecific findings in the left inguinal region. The patient had a robotic right inguinal node dissection the following month. Assessment of the skin flap was performed using indocyanine green (ICG) angiography with the SPY system and there was excellent vascularity. Further treatment was performed 3 months later with a robotic left inguinal node dissection. Again, assessment of the skin flap was performed using the SPY system but showed an area of poor perfusion in the left femoral triangle, which suggested a high risk of inadequate wound healing and tissue necrosis. The clinical decision to use the negative pressure PICO dressing was made intraoperatively to enhance perfusion of the skin. When the PICO dressing was removed it revealed excellent tissue viability and vascularity of the skin flap. Histopathology analysis showed no evidence of malignancy in the nodes removed and patient was discharged to the outpatient care of their urologist. Conclusion: This case study demonstrates that the use of a tissue perfusion assessment tool avoided a potentially poor clinical outcome for the patient. Robotic inguinal lymph node dissection was performed in coordination with ICG angiography to guide the use of negative pressure wound therapy and facilitate good wound healing.

Preliminary Use of Indocyanine Green Fluorescence Angiography and Value in Predicting the Vascular Supply of Tissues Needed to Perform Cloacal, Anorectal Malformation, and Hirschsprung Reconstructions.

Reconstructive techniques for cloaca, anorectal malformations (ARM), and Hirschsprung disease (HD) may require intestinal flaps on vascular pedicles for vaginal reconstruction and/or colonic pull-throughs. Visual assessment of tissue perfusion is typically the only modality used. We investigated the utility of intraoperative indocyanine green fluorescence angiography (ICG-FA) and hypothesized that it would be more accurate than the surgeon's eye. Thirteen consecutive patients undergoing cloacal reconstruction (9), HD (3), and ARM repair (1) underwent ICG-FA laser SPY imaging to assess colonic, rectal, vaginal, and neovaginal tissue perfusion following intraoperative visual clinical assessment. Operative findings were correlated with healing at 6 weeks, 3 months, and 1 year postoperatively. ICG-FA resulted in a change in the operative plan in 4 of the 13 (31%) cases. In three cases, ICG-FA resulted in the distal bowel being transected at a level (>10 cm) higher than originally planned, and in one case the distal bowel was discarded, and the colostomy used for pull-through. ICG-FA correctly identified patients who might have developed a complication from poor tissue perfusion. Employing this technology to assess rectal or neovaginal pull-throughs in cloacal reconstructions, complex HD, and ARM cases may be a valuable technology.

A case of scalp avulsion with prolonged ischemic time: indocyanine green angiography can\xa0aid in predicting replant survival

BackgroundMicrosurgical replantation has become the most favorable treatment option for scalp avulsion. However, the accurate prediction of postoperative replant viability remains challenging.Case presentationIn this article, we showed that (indocyanine green angiography, ICGA) can provide a much more precise prediction of replant necrosis than conventional clinical assessment in a rare case of complete scalp avulsion with prolonged ischemia time.ConclusionClinical assessment of replant survival may be misleading in cases of complex tissue injuries and prolonged ischemic stress. This case provides insight into the promising utility of ICGA as an important adjuvant tool to better assess tissue perfusion and viability in scalp avulsion and possibly other types of replantation.

Intraoperative Quality Assessment of Tissue Perfusion with Indocyanine Green (ICG) in a Porcine Model of Mesenterial Ischemia

Introduction - Intestinal ischemia as life-threatening event must be rapidly diagnosed and treated, but still intraoperative evaluation of bowel perfusion remains subjective and treatment strategies depend on the surgeon's personal experience. Especially detection of resection margins is important to improve patients’ outcome.

P5 FEASIBILITY AND EFFICACY OF INDOCYANINE GREEN ANGIOGRAPHY DURING ESOPHAGECTOMY: A SYSTEMATIC REVIEW

Abstract Aim The aim of this review was to evaluate feasibility and effectiveness of Indocyanine green fluorescence angiography (ICGA) as an assessment tool for gastric tube (GT) perfusion during the construction of the esophago-gastric anastomosis, and as a predictor of anastomotic leakage (AL). Moreover, attention was given to attempts made to quantify this method in esophageal surgery. Background &amp; Methods After an esophagectomy, a GT is most commonly used to restore continuity of the upper gastrointestinal tract. Esophago-gastric anastomoses are known for their complications such as AL, associated with high morbidity and mortality. Graft perfusion is an important predictor for anastomotic integrity. Tissue perfusion assessment is currently based on subjective parameters as tissue color and vessel pulsations. Near infrared fluorescent (NIRF) imaging is an emerging medical imaging modality, requiring penetrating NIR light that excites a NIRF agent within the tissue, generating fluorescence that can then be captured by adapted cameras. Indocyanine green Angiography (ICGA) is such a NIRF imaging technique which can be used as a method to visualize anastomotic perfusion. For this review, 2 reviewers independently searched Pubmed and Embase for studies evaluating intraoperative ICGA perfusion assessment of the GT. Feasibility, complications, intraoperative surgical changes based on ICGA findings, quantification attempts, anatomical data and the impact of ICGA on postoperative anastomotic complications were documented and further analyzed. Results Nineteen studies were included for qualitative analyses. All described ICGA as a safe and easy method for gastric graft perfusion assessment. AL occurred in 13.8% of the entire cohort, 10% in the ICG guided group and 20.6% in the control group (p&lt;.001). AL in the well-perfused group was 6.3% vs. 20.5% in the control group without ICGA (p&lt; .001). The group with an altered surgical plan based on the ICG image had similar AL rates as the well perfused group (6.5% vs. 6.3%) and significantly less than the poorly perfused group (47.8%) (p&lt;.001), suggesting that the technique is able to identify and alter a potential bad outcome. Conclusion the present review suggest that ICGA is a safe and easy method for GT perfusion assessment. Differences in AL rate between the well perfused and poor perfused anastomotic sites suggest that a good fluorescent signal is a predictor of good outcome.

Rapid, label-free detection of cerebral ischemia in rats using hyperspectral imaging

BackgroundStroke is the third most common cause of disability and the second most common cause of death worldwide. Ischemia, one of the two broad categories of stroke, is characterized by a lack of sufficient amounts of blood in order to supply an adequate amount of oxygen and nutrients. It is important to assess the part of the brain that becomes ischemic and necrotic during neurosurgery or experiments in real time. However, there is currently no effective means to achieve this goal. New methodWe proposed a method based on hyperspectral imaging (HSI) for the real-time detection of a varied range of ischemic brain tissues in vivo or ex vivo and assessed the practical utility of a model of ischemic stroke in rats. ResultsThe results showed that hyperspectral images processed with a ratio of spectral reflectance at 545 and 560 nm (R545/R560) could identify early brain ischemia and accurately show regions of ischemia. Comparison with existing methodsWe verified the area imaged by HSI using hematoxylin and eosin (HE) and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining methods. This technique could precisely image the ischemic part of the brain in vivo and ex vivo. ConclusionsThese results demonstrate the practical utility of HSI for the real-time detection of cerebral ischemia in rats. By providing rapid assessment of brain tissue perfusion, HSI may help doctors recognize ischemic regions quickly and precisely during surgery as well as have great utility in the experimental process.

Indocyanine green guided mastectomy and immediate breast reconstruction.

Today, breast cancer is treated, and breast reconstruction is performed in specialized centers. Integrated surgical, oncological and reconstructive treatment and care should characterize the comprehensive pathway. In this setting, the women being diagnosed with breast cancer or genetic disposition thereto, should be offered the highest standard of care and treatment. The prerequisite for a successful reconstruction as well as timely onset of adjuvant treatment is uneventful healing. In addition, this may also yield an aesthetically acceptable or even pleasing result. When performing a breast reconstruction or oncoplasty, adequate viability of the tissues left behind and/or added to partially or totally reconstruct the breast, is of utmost importance for a successful outcome. Therefore, tools to assess tissue perfusion are excellent and valuable instruments for the breast reconstructive surgeon. Indocyanine green-angiography (ICG-A) has been shown to be beneficial in delayed and immediate breast reconstruction. The absolute prerequisite for a successful immediate reconstruction is the nipple-sparing or subcutaneous mastectomy using a sufficient incision to spare the perfusion of the native skin. Upon completion of the mastectomy perfusion assessment is performed and the breast reconstructed, using implants or expanders with or without acellular dermal matrix or autologous flaps. The perfusion of the autologous flap may also be assessed using ICG-A. Depending on the assessment score, the mastectomy flaps or the autologous flap are subsequently revised, thereby increasing the probability of saving the patient post-operative revision and take-back to surgery and thus ensuring uneventful healing.

Et si l’imagerie neurologique nous était expliquée ?

Brain CT Perfusion (CTP) is an X-ray imaging technique for the assessment of brain tissue perfusion, which can be used in several different entities. The aim of this study is the evaluation of the radiation dose to patients during a comprehensive brain CT prescription protocol (CPP) consisting of an unenhanced brain CT, a brain CT angiography and a CTP scan.Eighteen patients were studied using an 80-slice CT system, with an iterative reconstruction algorithm. The volume Computed Tomography Dose Index (CTDIvol) and dose length product (DLP) were recorded from the dose report of the system. The calculation of effective dose (ED) was accomplished using the DLP values.For the CTP examinations, the CTDIvol ranged from 116.0 to 134.8 mGy, with the mean value 119.5 mGy. The DLP ranged from 463.9 to 539.2 mGy·cm, with the mean value 478 mGy·cm. For the CPP, the total ED ranged from 3.31 to 5.07 mSv, with the mean value 4.37 mSv.These values are lower than the values reported in corresponding studies, including studies utilizing CT systems with more slices.

Optimizing Indocyanine Green Fluorescence Angiography in Reconstructive Flap Surgery: A Systematic Review and Ex Vivo Experiments.

Background. Indocyanine green angiography (ICGA) offers the potential to provide objective data for evaluating tissue perfusion of flaps and reduce the incidence of postoperative necrosis. Consensus on ICGA protocols and information on factors that have an influence on fluorescence intensity is lacking. The aim of this article is to provide a comprehensive insight of in vivo and ex vivo evaluation of factors influencing the fluorescence intensity when using ICGA during reconstructive flap surgery. Methods. A systematic literature search was conducted to provide a comprehensive overview of currently used ICGA protocols in reconstructive flap surgery. Additionally, ex vivo experiments were performed to further investigate the practical influence of potentially relevant factors. Results. Factors that are considered important in ICGA protocols, as well as factors that might influence fluorescence intensity are scarcely reported. The ex vivo experiments demonstrated that fluorescence intensity was significantly related to dose, working distance, angle, penetration depth, and ambient light. Conclusions. This study identified factors that significantly influence the fluorescence intensity of ICGA. Applying a weight-adjusted ICG dose seems preferable over a fixed dose, recommended working distances are advocated, and the imaging head during ICGA should be positioned in an angle of 60° to 90° without significantly influencing the fluorescence intensity. All of these factors should be considered and reported when using ICGA for tissue perfusion assessment during reconstructive flap surgery.

Dynamic contrast-enhanced magnetic resonance imaging perfusion characteristics in meningiomas treated with resection and adjuvant radiosurgery.

OBJECTIVEThere is a need for advanced imaging biomarkers to improve radiation treatment planning and response assessment. T1-weighted dynamic contrast-enhanced perfusion MRI (DCE MRI) allows quantitative assessment of tissue perfusion and blood-brain barrier dysfunction and has entered clinical practice in the management of primary and secondary brain neoplasms. The authors sought to retrospectively investigate DCE MRI parameters in meningiomas treated with resection and adjuvant radiation therapy using volumetric segmentation.METHODSA retrospective review of more than 300 patients with meningiomas resected between January 2015 and December 2018 identified 14 eligible patients with 18 meningiomas who underwent resection and adjuvant radiotherapy. Patients were excluded if they did not undergo adjuvant radiation therapy or DCE MRI. Demographic and clinical characteristics were obtained and compared to DCE perfusion metrics, including mean plasma volume (vp), extracellular volume (ve), volume transfer constant (Ktrans), rate constant (kep), and wash-in rate of contrast into the tissue, which were derived from volumetric analysis of the enhancing volumes of interest.RESULTSThe mean patient age was 64 years (range 49-86 years), and 50% of patients (7/14) were female. The average tumor volume was 8.07 cm3 (range 0.21-27.89 cm3). The median Ki-67 in the cohort was 15%. When stratified by median Ki-67, patients with Ki-67 greater than 15% had lower median vp (0.02 vs 0.10, p = 0.002), and lower median wash-in rate (1.27 vs 4.08 sec-1, p = 0.04) than patients with Ki-67 of 15% or below. Logistic regression analysis demonstrated a statistically significant, moderate positive correlation between ve and time to progression (r = 0.49, p < 0.05). Furthermore, there was a moderate positive correlation between Ktrans and time to progression, which approached, but did not reach, statistical significance (r = 0.48, p = 0.05).CONCLUSIONSThis study demonstrates a potential role for DCE MRI in the preoperative characterization and stratification of meningiomas, laying the foundation for future prospective studies incorporating DCE as a biomarker in meningioma diagnosis and treatment planning.

A portable three-dimensional photoacoustic tomography system for imaging of chronic foot ulcers

Chronic leg ulcers affect approximately 6.5 million Americans and the disorder is associated with a range of serious complications. Since many chronic ulcers have underlying vascular insufficiency, accurate assessment of tissue perfusion is critical to treatment planning and post-surgical monitoring. However, existing clinical tests fail to meet this need in practice due to their low sensitivity or accuracy. In this paper, we introduce a portable photoacoustic tomography (PAT) system for wound assessment. Since hemoglobin serves as the major endogenous contrast at near-infrared wavelengths, PAT provides label-free, three-dimensional (3D) imaging of hemoglobin distribution, which is closely related to blood perfusion. The proposed system consists of a 128-element linear transducer array, a data acquisition (DAQ) system, and a pulsed Nd:YAG laser source, all mounted on a portable cart for easy clinical testing. We validated our system through both phantom and human imaging studies. The phantom imaging results indicate that the system's spatial resolution ranges from 0.5 mm along the axial direction to 1.3 mm along the elevational direction. The healthy volunteer result shows clear foot vasculature, indicating good perfusion. The preliminary patient imaging results agree very well with the clinical test, demonstrating that PAT has a high potential for assessing the circulation around the wound. We believe that our technique will be a valuable tool for assessing tissue perfusion and guiding wound treatment in vascular clinics.

Intraoperative SPY Reduces Post-mastectomy Skin Flap Complications: A Systematic Review and Meta-Analysis.

Indocyanine-green and laser-assisted fluorescence angiography, known as the SPY system, is a recently developed tool that has shown promise in assessing tissue perfusion. Its intraoperative use is becoming more common particularly in breast surgery. This systematic review aims to determine whether SPY technology can reduce postoperative complications related to tissue ischemia, specifically skin necrosis of the mastectomy native breast skin flaps. A systematic review of the literature was performed based on the PRISMA guideline. All studies that involved use of the SPY system to assess perfusion of postmastectomy skin flaps from January 1, 1960, to March 1, 2018 were included. Postoperative complications, including mastectomy skin flap necrosis were extracted from the selected studies. The perfusion-related complication rates and unexpected reoperation rates across multiple studies were then reviewed. Five relevant articles were identified including 902 patients undergoing mastectomy and native breast flap reconstructive procedures. Groups that used indocyanine-green angiography had statistically less incidence of native breast skin flap necrosis and unexpected reoperations due to perfusion-related complications compared with groups that monitored flaps with only clinical observation (odds ratio 0.54 for skin necrosis, and 0.36 for reoperation). In this systematic review, the incidence of native breast skin flap necrosis and unexpected reoperations were found to be statistically lower in cases where SPY was used. However, more prospective studies are required to establish SPY angiography as an accurate and cost-effective tool for assessment of tissue perfusion.

Impaired Post‐Occlusive Reoxygenation and Reperfusion in the Lower Legs of PAD Patients

Peripheral arterial disease (PAD) is a systemic atherosclerotic vascular disease that leads to demand ischemia and impaired mitochondrial function in the lower legs. Identifying the extent of non‐exercise related convective and diffusive oxygen transport impairments is important in furthering our understanding of microvascular impairments in this population.PurposeThe aim of this study was to determine the extent of reperfusion and reoxygenation impairments in the medial gastrocnemius (MG) and soleus (SOL) muscles of PAD patients.MethodsA novel functional MRI (fMRI) sequence was employed to simultaneously assess tissue perfusion, T2* relaxation time (used as an index of tissue oxygenation), and venous oxygen saturation (SvO2) in 3 patients with symptomatic PAD and 3 healthy age‐matched controls. Collecting these three parameters in a single scan was achieved by interleaving a gradient‐recalled‐echo (GRE) sequence into the post‐labeling‐delay of a pulsed‐arterial‐spin‐labeling sequence (total acquisition time of about 3.2 seconds). FMRI data were continuously collected during a reactive hyperemia protocol that consisted of a 2‐minute baseline, a 5‐minute period of occlusion, and a 5‐minute period of reactive hyperemia. Occlusion pressures ranged between 185 mmHg and 200 mmHg as tolerated by the subjects. Complete occlusion was verified in all subjects. Region of interest analyses were performed on the MG and SOL muscles of each subject. Perfusion and T2* were first converted to a delta score (AU), and then analyzed for peak responses (relative to baseline), time‐to‐peak (TTP, relative to end‐occlusion), and the slope of recovery. SvO2, expressed as a percentage of oxygen (%), responds in a biphasic pattern to reactive hyperemia. Specifically, SvO2 initially decreases (termed “washout”) upon cuff release, followed by a recovery that often surpasses baseline values. Accordingly, the peaks and slopes of washout and recovery are reported for SvO2. All variables were compared between groups using independent samples t‐tests.ResultsResults indicated that MG T2* TTP was longer (+40.5±11.1 seconds, t=−3.6, P=0.02), SOL peak perfusion was attenuated (−98.9±29.5 AU, t=3.3, P=0.02), and the slope of SvO2 washout was less steep in PAD patients compared to controls (−1.3±0.3, t=3.4, P=0.02). PAD patients also tended to exhibit a longer MG T2* recovery slope (0.07±0.02, t=2.6, P=0.057), and lower MG peak perfusion (−26.0±9.8 AU, t=2.6, P=0.057) compared to controls.ConclusionsThese data suggest that reperfusion and oxygenation responses to post‐occlusive reactive hyperemia are blunted and delayed in lower legs of PAD patients. More importantly, this highlights the severity of microvascular dysfunction in this population.Support or Funding InformationThis research was supported NIH P01 HL134609 (PI‐Sinoway).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Intraoperative Fluorescent Angiography Predicts Pharyngocutaneous Fistula After Salvage Laryngectomy.

Technology to assess tissue perfusion is exciting with translational potential, although data supporting its clinical applications have been lagging. Patients who have undergone radiation are at particular risk of poor tissue perfusion and would benefit from this expanding technology. We designed a prospective clinical trial using intraoperative indocyanine green angiography to evaluate for wound-healing complications in patients undergoing salvage laryngectomy after radiation failure. This prospective trial included patients undergoing salvage laryngectomy at a National Cancer Institute-designated tertiary cancer center between 2016 and 2018. After tumor extirpation and prior to reconstruction, 10mg indocyanine green dye was infused and the fluorescence (FHYPO) and ingress rate of the pharyngeal mucosa recorded. The primary outcome measure was formation of a pharyngocutaneous fistula (PCF). Patients who developed a PCF had significantly lower FHYPO (87 vs 172, p < 0.001) and ingress rates (6.7 vs 15.8, p = 0.043) compared with those who did not develop a fistula. There were no fistulas in patients with FHYPO > 150 (n = 21) or ingress > 15 (n = 15). There was a 50% fistula rate in patients with FHYPO ≤ 103 (n = 10) and ingress rate ≤ 6 (n = 6). Intraoperative indocyanine green angiography can assess hypoperfusion in patients and predict risk of PCFs after salvage laryngectomy, and can thus intraoperatively risk-stratify patients for postoperative wound-healing complications.

Single stage, direct to implant pre-pectoral breast reconstruction.

Given the current trends in skin preservation during mastectomy, improved biofilm reduction algorithms, and advancements in tissue bioengineering and perfusion assessment, acellular dermal matrix (ADM)-reinforced single stage, direct to implant insertion in the pre-pectoral space has become a viable alternative to two-stage expander-based, sub-pectoral reconstruction. The authors performed a retrospective review of their pre-pectoral cases evaluating outcomes for all single stage, direct to implant procedures. Outcomes reviewed included hematoma, seroma, infection, device loss or change, animation deformity and revisional procedures such as fat grafting. The anterior tenting surgical technique is also reviewed. The authors have carried out 305 direct to implant pre-pectoral breast reconstructions using an anterior tenting technique with low complication rates and superior clinical and functional outcomes. The benefits of this technique include less patient discomfort, no need for postoperative expansion, virtually no subjective negative impact on upper extremity function and elimination of animation deformity. Longer-term follow-up demonstrates maintenance of the integrity and quality of the reconstructions over time. The authors consider single stage, pre-pectoral direct to implant breast reconstruction to be a state-of-the-art breast reconstruction technique and have found it to be safe and reproducible. This technique is their primary choice for immediate implant-based reconstruction following mastectomy.

Intraoperative Tissue Perfusion Measurement by Laser Speckle Imaging: A Potential Aid for Reducing Postoperative Complications in Free Flap Breast Reconstruction.

Adequate tissue perfusion is essential to minimize postoperative complications following microsurgery. Intraoperative knowledge of tissue perfusion could aid surgical decision-making and result in reduced complications. Laser speckle imaging is a new, noninvasive technique for mapping tissue perfusion. This article discusses the feasibility of using laser speckle imaging during free flap breast reconstruction and its potential to identify areas of inadequate perfusion, thus reducing surgical complications. Adult patients scheduled to undergo free flap breast reconstruction were recruited into the study. Laser speckle images were obtained from the abdominal and breast areas at different stages intraoperatively. Zonal perfusion was compared with the Holm classification and clinical observations. Twenty patients scheduled to undergo free flap breast reconstruction were recruited (23 reconstructed breasts) (mean age, 50 years; range, 32 to 68 years). Flap zonal perfusion was 238 (187 to 313), 222 (120 to 265), 206 (120 to 265), and 125 (102 to 220) perfusion units for zones I, II, III, and IV, respectively (analysis of variance, p < 0.0001). Zonal area with perfusion below an arbitrary perfusion threshold were 20 (0.3 to 75), 41 (3 to 99), 49 (9 to 97), and 99 (25 to 100) percent, respectively (analysis of variance, p < 0.0001). One example is presented to illustrate potential intraoperative uses for laser speckle imaging. This study shows that laser speckle imaging is a feasible, noninvasive technique for intraoperative mapping of tissue perfusion during free flap breast reconstruction. Zonal tissue perfusion was reduced across the Holm classification. Observations indicated the potential for laser speckle imaging to provide additional information to augment surgical decision-making by detection of inadequate tissue perfusion. This highlights the opportunity for surgeons to consider additional aids for intraoperative tissue perfusion assessment to help reduce perfusion-related complications. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Diagnostic, IV.