Improved Positron Emission Tomography Quantification: Evaluation of a Maximum-Likelihood Scatter Scaling Algorithm.

Incorrect scatter scaling of positron emission tomography (PET) images can lead to halo artifacts, quantitative bias, or reconstruction failure. Tail-fitted scatter scaling (TFSS) possesses performance limitations in multiple cases. This study aims to investigate a novel method for scatter scaling: maximum-likelihood scatter scaling (MLSS) in scenarios where TFSS tends to induce artifacts or are observed to cause reconstruction abortion. [68Ga]Ga-RGD PET scans of nine patients were included in cohort 1 in the scope of investigating the reduction of halo artifacts relative to the scatter estimation method. PET scans of 30 patients administrated with [68Ga]Ga-uPAR were included in cohort 2, used for an evaluation of the robustness of MLSS in cases where TFSS-integrated reconstructions are observed to fail. A visual inspection of MLSS-corrected images scored higher than TFSS-corrected reconstructions of cohort 1. The quantitative investigation near the bladder showed a relative difference in tracer uptake of up to 94.7%. A reconstruction of scans included in cohort 2 resulted in failure in 23 cases when TFSS was used. The lesion uptake values of cohort 2 showed no significant difference. MLSS is suggested as an alternative scatter-scaling method relative to TFSS with the aim of reducing halo artifacts and a robust reconstruction process.

IRDye800CW labeled uPAR-targeting peptide for fluorescence-guided glioblastoma surgery: Preclinical studies in orthotopic xenografts.

Glioblastoma (GBM) is a devastating cancer with basically no curative treatment. Even with aggressive treatment, the median survival is disappointing 14 months. Surgery remains the key treatment and the postoperative survival is determined by the extent of resection. Unfortunately, the invasive growth with irregular infiltrating margins complicates an optimal surgical resection. Precise intraoperative tumor visualization is therefore highly needed and molecular targeted near-infrared (NIR) fluorescence imaging potentially constitutes such a tool. The urokinase-type Plasminogen Activator Receptor (uPAR) is expressed in most solid cancers primarily at the invading front and the adjacent activated peritumoral stroma making it an attractive target for targeted fluorescence imaging. The purpose of this study was to develop and evaluate a new uPAR-targeted optical probe, IRDye800CW-AE344, for fluorescence guided surgery (FGS). Methods: In the present study we characterized the fluorescent probe with regard to binding affinity, optical properties, and plasma stability. Further, in vivo imaging characterization was performed in nude mice with orthotopic human patient derived glioblastoma xenografts, and we performed head-to-head comparison within FGS between our probe and the traditional procedure using 5-ALA. Finally, the blood-brain barrier (BBB) penetration was characterized in a 3D BBB spheroid model. Results: The probe effectively visualized GBM in vivo with a tumor-to-background ratio (TBR) above 4.5 between 1 to 12 h post injection and could be used for FGS of orthotopic human glioblastoma xenografts in mice where it was superior to 5-ALA. The probe showed a favorable safety profile with no evidence of any acute toxicity. Finally, the 3D BBB model showed uptake of the probe into the spheroids indicating that the probe crosses the BBB. Conclusion: IRDye800CW-AE344 is a promising uPAR-targeted optical probe for FGS and a candidate for translation into human use.

Urokinase-Type Plasminogen Activator Receptor (uPAR) PET/MRI of Prostate Cancer for Noninvasive Evaluation of Aggressiveness: Comparison with Gleason Score in a Prospective Phase 2 Clinical Trial.

The aim of this study was to evaluate the correlation between uptake of the PET ligand 68Ga-NOTA-AE105, targeting the urokinase-type plasminogen activator receptor (uPAR), and Gleason score in patients undergoing prostate biopsy. Methods: Patients with clinical suspicion of prostate cancer (PCa) or previously diagnosed with PCa were prospectively enrolled in this phase 2 trial. A combination of uPAR PET and multiparametric MRI (mpMRI) was performed, and the SUV in the primary tumor, as delineated by mpMRI, was measured by 2 independent readers. The correlation between the SUV and the Gleason score obtained by biopsy was assessed. Results: A total of 27 patients had histologically verified PCa visible on mpMRI and constituted the study population. There was a positive correlation between the SUVmax and the Gleason score (Spearman ρ = 0.55; P = 0.003). Receiver operating characteristic analysis showed an area under the curve of 0.88 (95% CI, 0.67-1.00) for discriminating a Gleason score of greater than or equal to 3 + 4 from a Gleason score of less than or equal to 3 + 3. A cutoff for the tumor SUVmax could be established with a sensitivity of 96% (79%-99%) and a specificity of 75% (30%-95%) for detecting a Gleason score of greater than or equal to 3 + 4. For discriminating a Gleason score of greater than or equal to 4 + 3 from a Gleason score of less than or equal to 3 + 4, a cutoff could be established for detecting a Gleason score of greater than or equal to 4 + 3 with a sensitivity of 93% (69%-99%) and a specificity of 62% (36%-82%). Conclusion: SUV measurements from uPAR PET in primary tumors, as delineated by mpMRI, showed a significant correlation with the Gleason score, and the tumor SUVmax was able to discriminate between low-risk Gleason score profiles and intermediate risk Gleason score profiles with a high diagnostic accuracy. Consequently, uPAR PET/MRI could be a promising method for the noninvasive evaluation of PCa and might reduce the need for repeated biopsies (e.g., in active surveillance).

Multimodal soft tissue markers for bridging high-resolution diagnostic imaging with therapeutic intervention.

Diagnostic imaging often outperforms the surgeon's ability to identify small structures during therapeutic procedures. Smart soft tissue markers that translate the sensitivity of diagnostic imaging into optimal therapeutic intervention are therefore highly warranted. This paper presents a unique adaptable liquid soft tissue marker system based on functionalized carbohydrates (Carbo-gel). The liquid state of these markers allows for high-precision placement under image guidance using thin needles. Based on step-by-step modifications, the image features and mechanical properties of markers can be optimized to bridge diagnostic imaging and specific therapeutic interventions. The performance of Carbo-gel is demonstrated for markers that (i) have radiographic, magnetic resonance, and ultrasound visibility; (ii) are palpable and visible; and (iii) are localizable by near-infrared fluorescence and radio guidance. The study demonstrates encouraging proof of concept for the liquid marker system as a well-tolerated multimodal imaging marker that can improve image-guided radiotherapy and surgical interventions, including robotic surgery.

Cell-Enriched Fat Grafting Improves Graft Retention in a Porcine Model: A Dose-Response Study of Adipose-Derived Stem Cells versus Stromal Vascular Fraction.

BACKGROUND: Cell-enrichment of fat grafts has produced encouraging results, but the optimal concentrations and types of added cells are unknown. The authors investigated the effects of enrichment with various concentrations of ex vivo-expanded adipose-derived stem/stromal cells and stromal vascular fraction on graft retention in a porcine model. METHODS: Adipose-derived stem/stromal cells were culture-expanded, and six fat grafts (30 ml) were prepared for each minipig (n = 13). The authors investigated grafts enriched with 2.5 × 10 to 20 × 10 adipose-derived stem cells/ml and stromal vascular fraction and nonenriched control grafts. Each pig served as its own control. Magnetic resonance imaging was performed immediately after grafting and 120 days postoperatively before the pigs were euthanized, and histologic samples were collected. RESULTS: The authors recorded an enhanced relative graft retention rate of 41 percent in a pool of all cell-enriched grafts compared to the nonenriched control (13.0 percent versus 9.2 percent; p = 0.0045). A comparison of all individual groups showed significantly higher graft retention in the 10 × 10-adipose-derived stem/stromal cells per milliliter group compared with the control group (p = 0.022). No significant differences were observed between the cell-enriched groups (p = 0.66). All fat grafts showed a significantly better resemblance to normal fat tissue in the periphery than in the center (p < 0.009), but no differences in overall graft morphology were observed between groups (p > 0.17). CONCLUSIONS: Cell-enriched fat grafting improved graft retention and was feasible in this porcine model. No significant differences in graft retention were observed among the various adipose-derived stem/stromal cell concentrations or between adipose-derived stem/stromal cell and stromal vascular fraction enrichment. Future studies using this model can help improve understanding of the role of adipose-derived stem/stromal cells in cell-enriched fat grafting.

Molecular Targeted NIR-II Probe for Image-Guided Brain Tumor Surgery.

Optical imaging strategies for improving delineation of glioblastoma (GBM) is highly desired for guiding surgeons to distinguish cancerous tissue from healthy and precious brain tissue. Fluorescence imaging (FLI) in the second near-infrared window (NIR-II) outperforms traditional NIR-I imaging with better tissue penetration, higher spatial and temporal resolution, and less auto fluorescence and scattering. Because of high expression in GBM and many other tumors, urokinase Plasminogen Activator Receptor (uPAR) is an attractive and well proven target for FLI. Herein we aim to combine the benefit of a NIR-II fluorophore with a high affinity uPAR targeting small peptide. A targeted NIR-II fluorescent probe was developed by conjugating an in-house synthesized NIR-II fluorophore, CH1055, and a uPAR targeting peptide, AE105. To characterize the in vivo distribution and targeting properties, a dynamic imaging was performed in orthotopic GBM bearing nude mice ( n = 8). Additionally, fluorescence guided surgery of orthotopic GBM was performed in living animals. CH1055-4Glu-AE105 was easily synthesized with >75% yield and >98% HPLC evaluated purity. The retention time of the probe on analytical HPLC was 15.9 min and the product was verified by mass spectrometry. Dynamic imaging demonstrated that the uPAR targeting probe visualized orthotopic GBM through the intact skull with a tumor-to-background ratio (TBR) of 2.7 peaking at 96 h. Further, the orthotopic GBM was successfully resected in small animals guided by the NIR-II FLI. By using a small uPAR targeting NIR-II probe, FLI allows us to specifically image and detect GBM. A real-time imaging setup further renders FLI guided tumor resection, and the probe developed in this work is a promising candidate for clinical translation.

A Novel Porcine Model for Future Studies of Cell-enriched Fat Grafting.

BACKGROUND: Cell-enriched fat grafting has shown promising results for improving graft survival, although many questions remain unanswered. A large animal model is crucial for bridging the gap between rodent studies and human trials. We present a step-by-step approach in using the Göttingen minipig as a model for future studies of cell-enriched large volume fat grafting. METHODS: Fat grafting was performed as bolus injections and structural fat grafting. Graft retention was assessed by magnetic resonance imaging after 120 days. The stromal vascular fraction (SVF) was isolated from excised fat and liposuctioned fat from different anatomical sites and analyzed. Porcine adipose-derived stem/stromal cells (ASCs) were cultured in different growth supplements, and population doubling time, maximum cell yield, expression of surface markers, and differentiation potential were investigated. RESULTS: Structural fat grafting in the breast and subcutaneous bolus grafting in the abdomen revealed average graft retention of 53.55% and 15.28%, respectively, which are similar to human reports. Liposuction yielded fewer SVF cells than fat excision, and abdominal fat had the most SVF cells/g fat with SVF yields similar to humans. Additionally, we demonstrated that porcine ASCs can be readily isolated and expanded in culture in allogeneic porcine platelet lysate and fetal bovine serum and that the use of 10% porcine platelet lysate or 20% fetal bovine serum resulted in population doubling time, maximum cell yield, surface marker profile, and trilineage differentiation that were comparable with humans. CONCLUSIONS: The Göttingen minipig is a feasible and cost-effective, large animal model for future translational studies of cell-enriched fat grafting.

The CPC Risk Calculator: A New App to Predict Prostate-specific Antigen Recurrence During Follow-up After Radical Prostatectomy.

BACKGROUND: It can be challenging to predict the risk of biochemical recurrence (BR) during follow-up after radical prostatectomy (RP) in men who have undetectable prostate-specific antigen (PSA), even years after surgery. OBJECTIVE: To establish and validate a contemporary nomogram that predicts the absolute risk of BR every year after RP in men with undetectable PSA while accounting for competing risks of death. DESIGN, SETTING, AND PARTICIPANTS: A total of 3746 patients from Rigshospitalet (Copenhagen, Denmark) and Stanford Urology (Stanford, CA, USA) who underwent RP between 1995 and 2013 were included. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Time to BR was defined as the first PSA result ≥0.2 ng/ml. BR risk was computed using multiple cause-specific Cox regression including preoperative PSA, pT category, RP Gleason score (GS), and surgical margin (R) status. Death without BR was considered a competing event. The nomogram presents the future risk of BR for a man who is alive and without BR at the time of follow-up. Validation assessed the discrimination and accuracy using time-dependent area under the curve and Brier scores. RESULTS AND LIMITATIONS: The nomogram predicts risk of BR up to 12 yr after RP at an individual level. As example, the risk of BR for a man with pT3a, R-, GS 3 + 4, and preoperative PSA ≤10 ng/ml followed for 5 yr with undetectable PSA is 18% for the next 5 yr. External validation demonstrated both high accuracy and discrimination. The CPC Risk Calculator is available as a free Android and iOS App. Declining discrimination and accuracy after 7 yr of follow-up is the main limitation. CONCLUSIONS: This nomogram can be used as a tool to inform men with undetectable PSA during follow-up after RP about their future risk of BR, and may aid in decisions on the necessity for further follow-up. The nomogram is the first to be available as a free app. PATIENT SUMMARY: We developed an easily interpretable nomogram to evaluate the risk of prostate-specific antigen elevation (cancer recurrence) following complete removal of the prostate (radical prostatectomy). The tool can aid both physicians and patients in evaluating the future risk of cancer recurrence during follow-up after surgery. The model is available as a free mobile app that can be downloaded from the App Store.

The risk of biochemical recurrence for intermediate-risk prostate cancer after radical prostatectomy.

OBJECTIVES: To report oncological outcomes including biochemical recurrence (BR) following radical prostatectomy (RP) from a large consecutive cohort operated in an 18-year period. Additionally, an in-depth analysis of outcomes among D'Amico intermediate-risk patients is presented. MATERIALS AND METHODS: A total of 2,091 patients with PCa who underwent RP at Department of Urology, Rigshospitalet, Copenhagen, Denmark between 1995 and 2013 were included. Univariate and multiple cause-specific Cox regression analyses for BR were applied using competing risk models. Death prior to BR was considered a competing event. BR was defined as the first PSA ≥0.2 ng/ml. No patient received adjuvant therapy prior to BR. RESULTS: Overall, the 5- and 10-years cumulative incidence of BR was 21.9% and 32.0%. The 10-year cumulative incidence of BR was 17.9%, 31.9% and 47.9% for D'Amico low-, intermediate- and high-risk patients, respectively. Among intermediate-risk patients, the 10-year cumulative incidence of BR was 24.0%, 39.9%, and 47.9% for patients harboring one, two or three risk factors, respectively (Gray test: p < 0.0001). In multivariate analysis, PSA, RP GS, pT category, and positive surgical margins were significantly associated with an increased risk of BR. CONCLUSIONS: The risk of BR among patients with intermediate-risk disease is not uniform and is highly dependent on the number of risk factors per patient. Intermediate-risk patients have a comparable risk of recurrence as high-risk patients, and this should be taken into consideration when counseling patients prior to RP.

Postoperative anemia and early functional outcomes after fast-track hip arthroplasty: a prospective cohort study.

BACKGROUND: Postoperative anemia is prevalent in fast-track hip arthroplasty (THA) where patients are mobilized and discharged early, but whether anemia impairs functional recovery after discharge has not been adequately evaluated previously. This study aimed to evaluate whether postoperative anemia influenced recovery of mobility and quality of life (Qol) during the first 2 weeks after discharge from THA. STUDY DESIGN AND METHODS: This was a prospective observational study in 122 THA patients more than 65 years of age. Mobility and Qol were assessed pre- and postoperatively by the 6-minute walk test (6MWT; primary outcome), the timed up-and-go test, and the FACT-anemia subscale. Twenty-four-hour mobility at home was assessed by activity monitoring on Days 1 to 6 after discharge. Hemoglobin (Hb) at discharge (HbD) and the Hb decrease from preoperatively (ΔHb) were compared to mobility and Qol the first 2 weeks after discharge using bivariate and multivariate linear regression. RESULTS: Mean (±SD) HbD and ΔHb values were 11.1 (±1.4) and 2.8 (±1.2) g/dL and correlated weakly to 6MWT 2 weeks after discharge (r = 0.23 and r = -0.20 respectively; p < 0.05) but HbD levels were not correlated to other mobility or Qol measures. After adjustment for preoperative patient-related factors, HbD explained 6% (95% confidence interval, 0%-9%; p < 0.05) of the variation in 6MWT recovery. CONCLUSION: Despite a weak, but significant, correlation between postoperative Hb and the recovery of 6MWT, all other mobility and Qol measures were not influenced by postoperative Hb. Thus, moderate postoperative anemia has limited impact on early postdischarge functional recovery after fast-track THA.

Delirium in fast-track colonic surgery.

BACKGROUND: Postoperative delirium (PD) is a common but serious problem after major surgery with a multifactorial pathogenesis including age, pain, opioid use, sleep disturbances and the surgical stress response. These factors have been minimised by the "fast-track methodology" previously demonstrated to enhance recovery and reduce morbidity. METHODS: Clinical symptoms of PD were routinely collected three times daily from preoperatively until discharge in a well-defined enhanced recovery program after colonic surgery in 247 consecutive patients. RESULTS: Total median length of hospital stay was 3 days. Seven patients (2.8%) developed clinical signs of PD most within the first 72 postoperative hours and only 1 patient with PD extending to 120 h postoperatively. Only 1 PD patient required treatment with serenase. PD patients were older (83 vs. 73 years) and had longer median stay (6 vs. 3 days). No difference in development of PD between open and laparoscopic operation could be demonstrated. Among the 7 patients with PD, 3 of these patients had later surgical complications. One patient had a subsequent strangulated small intestine, another an anastomotic leakage complicated by a bleeding gastric ulcer and death on day 12 and 1 with fever, abdominal pain and suspected but disproven anastomotic leakage (stay 21, 12 and 22 days, respectively). The remaining 4 PD patients stayed 4, 4, 5 and 6 days with an uncomplicated course. CONCLUSIONS: These data support that an enhanced postoperative recovery program may decrease the risk and duration of PD after colonic surgery.