Evaluation of LAT1 Expression in Patients With Lung Cancer and Mediastinal Tumors: 18F-FBPA PET Study With Immunohistological Comparison.

PURPOSE OF THE REPORT: L-type amino acid transporter-1 (LAT1) is a tumor-specific transporter expressed in various tumor types, with minimal expression in normal organs. We previously demonstrated 18F-fluoro-borono-phenylalanine (18F-FBPA) as a selective PET probe for LAT1 in a preclinical study. Herein, we evaluated LAT1 expression in preoperative patients with lung or mediastinal tumors using 18F-FBPA PET and immunofluorescence staining. PATIENTS AND METHODS: The study population included patients with histopathological diagnosis (n = 55): primary lung cancers (n = 21), lung metastases (n = 6), mediastinal tumors (n = 15), and benign lesion (n = 13). PET scanning was performed 1 hour after the injection of 18F-FBPA (232 ± 32 MBq). Immunofluorescence staining was performed on the resected tumor sections using LAT1 antibody. LAT1 staining was graded on a 4-grade scale and compared with the SUVmax on 18F-FBPA PET. RESULTS: A positive correlation was observed between the SUVmax of 18F-FBPA PET and LAT1 expression by immunofluorescence staining (r = 0.611, P < 0.001). The SUVmax of 18F-FBPA was 3.92 ± 1.46 in grade 3, 3.21 ± 1.82 in grade 2, 2.33 ± 0.93 in grade 1, and 1.50 ± 0.39 in grade 0 of LAT1 expression. Although 18F-FBPA PET showed variable uptake in lung cancers and mediastinal tumors, benign lesions showed significantly lower SUVmax than those in malignant lesions (P < 0.01). CONCLUSIONS: Uptake on 18F-FBPA PET reflected the expression level of LAT1 in lung and mediastinal tumors. It was suggested that 18F-FBPA PET can be used for the precise characterization of the tumor in pretreatment evaluation.

Exploration of the threshold SUV for diagnosis of malignancy using 18F-FBPA PET/CT.

BACKGROUND: The goal of the study was to evaluate the diagnostic ability of 18F-FBPA PET/CT for malignant tumors. Findings from 18F-FBPA and 18F-FDG PET/CT were compared with pathological diagnoses in patients with malignant tumors or benign lesions. METHODS: A total of 82 patients (45 males, 37 females; median age, 63 years; age range, 20-89 years) with various types of malignant tumors or benign lesions, such as inflammation and granulomas, were examined by 18F-FDG and 18F-FBPA PET/CT. Tumor uptake of FDG or FBPA was quantified using the maximum standardized uptake value (SUVmax). The final diagnosis was confirmed by cytopathology or histopathological findings of the specimen after biopsy or surgery. A ROC curve was constructed from the SUVmax values of each PET image, and the area under the curve (AUC) and cutoff values were calculated. RESULTS: The SUVmax for 18F-FDG PET/CT did not differ significantly for malignant tumors and benign lesions (10.9 ± 6.3 vs. 9.1 ± 2.7 P = 0.62), whereas SUVmax for 18F-FBPA PET/CT was significantly higher for malignant tumors (5.1 ± 3.0 vs. 2.9 ± 0.6, P < 0.001). The best SUVmax cutoffs for distinguishing malignant tumors from benign lesions were 11.16 for 18F-FDG PET/CT (sensitivity 0.909, specificity 0.390) and 3.24 for 18F-FBPA PET/CT (sensitivity 0.818, specificity 0.753). ROC analysis showed significantly different AUC values for 18F-FDG and 18F-FBPA PET/CT (0.547 vs. 0.834, p < 0.001). CONCLUSION: 18F-FBPA PET/CT showed superior diagnostic ability over 18F-FDG PET/CT in differential diagnosis of malignant tumors and benign lesions. The results of this study suggest that 18F-FBPA PET/CT diagnosis may reduce false-positive 18F-FDG PET/CT diagnoses.

Successful salvage surgery of the residual tumor after boron neutron capture therapy (BNCT): A case report.

Salvage surgery after radiation therapy is known to be associated with a high incidence of postoperative complications. We describe a case of a successful salvage surgery after BNCT. In our patient with head and neck carcinoma, cervical lymph node recurrence with adhesion to a large vessel occurred after conventional radiotherapy. This lesion responded well to BNCT. Salvage surgery was subsequently performed to remove the residual tumor. Histopathologically, the isolated tissue contained tumor cells in its center and the surrounding tissue showed severe fibrosis. However, the tissue outside of the irradiation area had almost no fibrosis. BNCT may facilitate salvage surgery after radiotherapy because it causes less injury to the surrounding tissue than conventional radiotherapy. Our experience suggests that BNCT may be a feasible preoperative treatment in patients with inoperable lesions or in those who strongly desire preservation of function.

Comprehensive evaluation of dosimetric impact against position errors in accelerator-based BNCT under different treatment parameter settings.

BACKGROUND: Patients who undergo accelerator-based (AB) boron neutron capture therapy (BNCT) for head and neck cancer in the sitting position are generally uncomfortably immobilized, and patient motion during this treatment may be greater than that in other radiotherapy techniques. Furthermore, the treatment time of BNCT is relatively long (up to approximately 1 h), which increases the possibility of patient movement during treatment. As most BNCT irradiations are performed in a single fraction, the dosimetric error due to patient motion is of greater consequence and needs to be evaluated and accounted for. Several treatment parameters are required for BNCT dose calculation. PURPOSE: To investigate the dosimetric impacts (DIs) against position errors using a simple cylindrical phantom for an AB-BNCT system under different treatment parameter settings. METHODS: The treatment plans were created in RayStation and the dose calculation was performed using the NeuCure® dose engine. A cylindrical phantom (16 cm diameter × 20 cm height) made of soft tissue was modeled. Dummy tumors in the form of a 3-cm-diameter sphere were arranged at depths of 2.5 and 6.5 cm (denoted by T2.5 and T6.5 , respectively). Reference plans were created by setting the following parameters: collimator size = 10, 12, or 15 cm in diameter, collimator-to-surface distance (CSD) = 4.0 or 8.0 cm, tumor-to-blood ratio (T/B ratio) using 18 F-fluoro-borono-phenylalanine = 2.5 or 5.0, and 10 B concentration in blood = 20, 25, or 30 ppm. The prescribed dose was D95%  ≥ 20 Gy-eq for both T2.5 and T6.5 . Based on the reference plans, phantom-shifted plans were created in 26 directions [all combinations of left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions) and three distances (1.0, 2.0, and 3.0 cm). The DIs were evaluated at D80% of the tumors. The shift direction dependency of the DI in the LR, AP, and SI directions was evaluated by conducting a multiple regression analysis (MRA) and other analyses where required. RESULTS: The coefficients of the MRA of the DIs for LR, AP, and SI shifts were -0.08, 2.16, and -0.04 (p-values = 0.084, <0.01, and 0.334) for T2.5 and -0.05, 2.08, and 0.15 (p-values = 0.526, <0.01, and 0.065) for T6.5 , respectively. The analysis of variance showed that DIs due to the AP shift were significantly greater for smaller collimator sizes on T2.5 and smaller CSD on T6.5 . Dose reduction due to SI or LR (lateral) shifts was significantly greater for smaller collimator sizes on both T2.5 and T6.5 and smaller CSD on T2.5 , according to the Student's t-test. There were no significant differences in the DIs against both the AP shift and the lateral shift between the different T/B ratios and 10 B concentrations. CONCLUSION: The DIs were largely affected by the shift in the AP direction and were influenced by the different treatment parameters.

Nociceptor-derived Reg3γ prevents endotoxic death by targeting kynurenine pathway in microglia.

Nociceptors can fine-tune local or systemic immunity, but the mechanisms of nociceptive modulation in endotoxic death remain largely unknown. Here, we identified C-type lectin Reg3γ as a nociceptor-enriched hormone that protects the host from endotoxic death. During endotoxemia, nociceptor-derived Reg3γ penetrates the brain and suppresses the expression of microglial indoleamine dioxygenase 1, a critical enzyme of the kynurenine pathway, via the Extl3-Bcl10 axis. Endotoxin-administered nociceptor-null mice and nociceptor-specific Reg3γ-deficient mice exhibit a high mortality rate accompanied by decreased brain HK1 phosphorylation and ATP production despite normal peripheral inflammation. Such metabolic arrest is only observed in the brain, and aberrant production of brain quinolinic acid, a neurotoxic metabolite of the kynurenine pathway, causes HK1 suppression. Strikingly, the central administration of Reg3γ protects mice from endotoxic death by enhancing brain ATP production. By identifying nociceptor-derived Reg3γ as a microglia-targeted hormone, this study provides insights into the understanding of tolerance to endotoxic death.

Evaluation of a treatment planning system developed for clinical boron neutron capture therapy and validation against an independent Monte Carlo dose calculation system.

Boron neutron capture therapy (BNCT) for the treatment of unresectable, locally advanced, and recurrent carcinoma of the head and neck cancer has been approved by the Japanese government for reimbursement under the national health insurance as of June 2020. A new treatment planning system for clinical BNCT has been developed by Sumitomo Heavy Industries, Ltd. (Sumitomo), NeuCure® Dose Engine. To safely implement this system for clinical use, the simulated neutron flux and gamma ray dose rate inside a water phantom was compared against experimental measurements. Furthermore, to validate and verify the new planning system, the dose distribution inside an anthropomorphic head phantom was compared against a BNCT treatment planning system SERA and an in-house developed Monte Carlo dose calculation program. The simulated results closely matched the experimental results, within 5% for the thermal neutron flux and 10% for the gamma ray dose rate. The dose distribution inside the head phantom closely matched with SERA and the in-house developed dose calculation program, within 3% for the tumour and a difference of 0.3 Gyw for the brain.

Imaging Assessment of Tumor Response in the Era of Immunotherapy.

Assessment of tumor response during treatment is one of the most important purposes of imaging. Before the appearance of immunotherapy, response evaluation criteria in solid tumors (RECIST) and positron emission tomography response criteria in solid tumors (PERCIST) were, respectively, the established morphologic and metabolic response criteria, and cessation of treatment was recommended when progressive disease was detected according to these criteria. However, various types of immunotherapy have been developed over the past 20 years, which show novel false positive findings on images, as well as distinct response patterns from conventional therapies. Antitumor immune response itself causes 18F-fluorodeoxyglucose (FDG) uptake in tumor sites, known as "flare phenomenon", so that positron emission tomography using FDG can no longer accurately identify remaining tumors. Furthermore, tumors often initially increase, followed by stability or decrease resulting from immunotherapy, which is called "pseudoprogression", so that progressive disease cannot be confirmed by computed tomography or magnetic resonance imaging at a single time point. As a result, neither RECIST nor PERCIST can accurately predict the response to immunotherapy, and therefore several new response criteria fixed for immunotherapy have been proposed. However, these criteria are still controversial, and also require months for response confirmation. The establishment of optimal response criteria and the development of new imaging technologies other than FDG are therefore urgently needed. In this review, we summarize the false positive images and the revision of response criteria for each immunotherapy, in order to avoid discontinuation of a truly effective immunotherapy.

In vivo evaluation of percutaneous carbon dioxide treatment for improving intratumoral hypoxia using 18F-fluoromisonidazole PET-CT.

Carbon dioxide (CO2) treatment is reported to have an antitumor effect owing to the improvement in intratumoral hypoxia. Previous studies were based on histological analysis alone. In the present study, the improvement in intratumoral hypoxia by percutaneous CO2 treatment in vivo was determined using 18F-fluoromisonidazole positron emission tomography-computed tomography (18F-FMISO PET-CT) images. Twelve Japanese nude mice underwent implantation of LM8 tumor cells in the dorsal subcutaneous area 2 weeks before percutaneous CO2 treatment and 18F-FMISO PET-CT scans. Immediately after intravenous injection of 18F-FMISO, CO2 and room air were administered transcutaneously in the CO2-treated group (n=6) and a control group (n=6), respectively; each treatment was performed for 10 minutes. PET-CT was performed 2 h after administration of 18F-FMISO. 18F-FMISO tumor uptake was quantitatively evaluated using the maximum standardized uptake value (SUVmax), tumor-to-liver ratio (TLR), tumor-to-muscle ratio (TMR), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Mean ± standard error of the mean (SEM) of the tumor volume was not significantly different between the two groups (CO2-treated group, 1.178±0.450 cm3; control group, 1.368±0.295 cm3; P=0.485). Mean ± SEM of SUVmax, TLR, MTV (cm3) and TLG were significantly lower in the CO2-treated group compared with the control group (0.880±0.095 vs. 1.253±0.071, P=0.015; 1.063±0.147361 vs. 1.455±0.078, P=0.041; 0.353±0.139 vs. 1.569±0.438, P=0.015; 0.182±0.070 vs. 1.028±0.338, P=0.015), respectively. TMR was not significantly different between the two groups (4.520±0.503 vs. 5.504±0.310; P=0.240). In conclusion, 18F-FMISO PET revealed that percutaneous CO2 treatment improved intratumoral hypoxia in vivo. This technique enables assessment of the therapeutic effect in CO2 treatment by imaging, and may contribute to its clinical application.

Astrocyte metabolism in multiple sclerosis investigated by 1-C-11 acetate PET.

This study was aimed at evaluating the metabolism of reactive astrocytes in the brains of patients with multiple sclerosis by quantitative 1-C-11 acetate positron emission tomography (PET). Magnetic resonance imaging and 1-C-11 quantitative PET were performed in eight patients with multiple sclerosis and 10 normal control subjects. The efflux rate (k2) of 1-C-11 acetate, which reportedly reflects the metabolic rate of 1-C-11 acetate, was calculated based on the one-tissue compartmental model. Fractional anisotropy was also determined to evaluate the integrity of the neuronal tracts. The values of k2 in the patients with multiple sclerosis were significantly higher than those in the normal control subjects, in both the white matter (p = 0.003) and the gray matter (p = 0.02). In addition, the white matter/gray matter ratio of k2 was significantly higher in the multiple sclerosis patients than in the normal control subjects (p = 0.02). Voxel-based statistical analysis revealed most prominent increase in k2 in the neuronal fiber tracts, as well as decrease in fractional anisotropy in them in the multiple sclerosis patients. The present study clarified that the pathological changes associated with astrocytic reactivation in multiple sclerosis patients could be visualized by quantitative 1-C-11 acetate PET.

Enhanced immune reaction resulting from co-vaccination of WT1 helper peptide assessed on PET-CT.

It has become evident that positron emission tomography/computed tomography (PET-CT) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) (FDG PET-CT) can detect anti-tumor immune response induced by various immunotherapies. To evaluate whether FDG PET-CT could detect anti-cancer immune response caused by cancer vaccine therapy, we performed a retrospective analysis of FDG PET-CT imaging of patients who were treated with Wilms Tumor 1 (WT1) vaccine therapy in Osaka University during July 2008 and June 2018. Increased FDG uptakes were detected in WT1-vaccinated skin and their draining lymph nodes during the repeated vaccination. While the FDG uptakes seemed to decrease with time after the cessation of WT1 peptide vaccinations, persistence of FDG uptakes for years in WT1-vaccinated skin were also observed in 2 cases who showed good clinical course. Moreover, the FDG uptakes of patients treated with the combination vaccine of WT1 specific cytotoxic T cell (CTL) and helper peptides were significantly stronger than of those treated with the WT1 CTL peptide alone. Since it is evident that the combination vaccine can induce a more robust anti-tumor immunity than can CTL peptide vaccine alone, the FDG uptakes in WT1-vaccinated skin might reflect the degree of immune response. These results suggest that PET-CT might be a good tool for prediction of anti-tumor immune response induced by WT1 vaccine therapy. Larger scale prospective studies therefore seem to be warranted.

Evaluation of the total distribution volume of 18F-FBPA in normal tissues of healthy volunteers by non-compartmental kinetic modeling.

OBJECTIVE: Boron neutron capture therapy (BNCT) is a noninvasive radiation therapy method for cancer treatment. In BNCT, 4-borono-2-[18F]-fluoro-L-phenylalanine (18F-FBPA) PET has been employed to estimate 10B accumulation in target tumors and normal tissues if 10B borono-L-phenylalanine (10B-BPA) is used as a boron carrier. The purpose of the current study was to evaluate the total distribution volume (Vt) of 18F-FBPA in normal organs of healthy volunteers by kinetic analysis and to estimate boron concentration in normal organs for the therapeutic dose of 10B-BPA using obtained Vt values. METHODS: Six healthy volunteers were injected with 18F-FBPA (3-5 MBq/kg), and 7 PET-CT scans were performed subsequently. 18F-FBPA radioactivity in whole blood and plasma was measured before, and eight times after the injection. PET images were analyzed by PMOD software. Twelve volumetric regions of interest including the brain, heart, right lung, spleen, liver, parotid salivary glands, esophagus, stomach, pancreas, intestines, and bone marrow were drawn manually for each subject and analyzed with the Logan plot and two Ichise multilinear analyses (MA1 and MA2). The better model was defined by several goodness-of-fit parameters and residual distribution. After Vt values had been derived, boron concentration was estimated in ppm for the 10B-BPA-fructose (10B-BPA-fr) dose 30 g 1 and 2 h post-injection using Vt and interpolated plasma activity data. RESULTS: The Ichise MA2 model showed the best fit among all models. Akaike Information Criterion (AIC) was the lowest for the Ichise's MA2 in all regions (mean AIC value - 14.0) comparing to the other models (Logan plot mean AIC 31.4; Ichise MA1 model mean AIC - 4.2). Mean Vt values of the Ichise MA2 model ranged from 0.94 ± 0.14 ml/ml in the pancreas to 0.16 ± 0.02 ml/ml in the right lung. Estimated boron concentration for 10B-BPA-fr had the highest value in the pancreas (14.0 ± 1.9 ppm 1 h after, and 5.7 ± 1.7 ppm 2 h after the 18F-FBPA administration) and the lowest value in the right lung (2.4 ± 0.3 ppm 1 h, and 1.0 ± 0.3 ppm 2 h post-injection). CONCLUSION: The 10B concentration in normal tissues was best estimated using Vt values of 18F-FBPA with the Ichise multilinear analysis 2 (MA2). TRAIL REGISTRY: The UMIN clinical trial number: UMIN000022850.

Prostacyclin Analogue-Loaded Nanoparticles Attenuate Myocardial Ischemia/Reperfusion Injury in Rats.

Intravenously injected ONO-1301-containing nanoparticles (ONO-1301NPs), unlike an ONO-1301 solution, selectively accumulated in the ischemia/reperfusion (I/R)-injured myocardium of rats and contributed to the prolonged retention of ONO-1301 in the targeted myocardial tissue. In the ischemic area, proangiogenic cytokines were up-regulated and inflammatory cytokines were down-regulated upon ONO-1301NP administration. Consequently, ONO-1301NP-injected rats exhibited a smaller infarct size, better-preserved capillary networks, and a better-preserved myocardial blood flow at 24 h after I/R injury, compared with those in vehicle-injected or ONO-1301 solution-injected rats. ONO-1301NPs attenuate the myocardial I/R injury via proangiogenic and anti-inflammatory effects of the drug.

Volumetric and texture analysis on FDG PET in evaluating and predicting treatment response and recurrence after chemotherapy in follicular lymphoma.

PURPOSE: The purpose of this study was to determine if quantitative SUV-related, volumetric FDG PET parameters, and texture features (SPs, VPs, and TFs, respectively) were useful to evaluate and predict response and recurrence after chemotherapy in follicular lymphoma (FL). METHODS: Pre- and posttreatment FDG PET examinations in 45 FL patients were analyzed retrospectively. In addition to SPs in the representative lesion, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were calculated as VPs for the representative and whole-body lesions. Six TFs were calculated in the pretreatment representative lesion. Response results with reduction of SPs or VPs after treatment (Δ) were compared to the Lugano classification based on visual assessment. SPs, VPs, and Δ of them as well as TFs were also evaluated if they allow prediction of response and recurrence after chemotherapy. RESULTS: Quantitative assessment with SPs and VPs provided 89% and 93-96% concordant results, respectively, with Lugano classification. Among pretreatment PET parameters, low gray-level zone emphasis (LGZE) in TFs solely showed statistical significance to predict complete response. All of posttreatment and Δ of SPs and VPs were considered as the predictors of progression free survival in the univariate Cox regression analysis, but none of them was the predictor in the multivariate analysis. CONCLUSION: This study demonstrated that quantitative PET parameters were applicable to evaluate treatment response in FL. Texture analysis showed promise in predicting treatment response. Although posttreatment and Δ of PET parameters were the candidates, all of them proved to have limited value in predicting recurrence after chemotherapy.

Microvascular Dysfunction Related to Progressive Left Ventricular Remodeling due to Chronic Occlusion of the Left Anterior Descending Artery in an Adult Porcine Heart.

Occlusion of a major coronary artery induces myocardial infarction (MI), leading to left ventricle (LV) remodeling due to progressive microvasculature dysfunction. Irreversible impairment in microvascular function has been suggested to extend from the infarcted region into the infarct-border or remote regions, depending on the time to revascularization. Our aim was to determine whether the occlusion of a major coronary artery induces microvascular dysfunction in the adjacent area perfused by intact coronary arteries using a porcine model for chronic total occlusion of the left anterior descending artery (LAD). MI was induced via an ameroid constrictor ring around the LAD in adult Göttingen pigs (Sus scrofa domesticus, n = 5). Age-matched normal pigs were treated as controls (n = 3). Cardiac magnetic resonance showed reduced systolic regional wall motion in the left circumflex (LCx) and right coronary artery (RCA) territories, with a progressively worsening motion in the infarction-adjacent area over an eight-week period. On 13N-ammonia positron emission tomography (PET), myocardial blood flow (MBF) during hyperemia was significantly greater in the LCx and RCA territories (particularly in the infarction-adjacent area) compared to that in the LAD territory at four weeks after infarct induction. Subsequently, the flow significantly decreased, approaching that in the LAD territory at eight weeks after infarct induction. Fluoroscopy-guided pressure-wire studies showed significantly higher microvascular resistance in the LCx area at eight weeks compared to that in controls. Electron microscopy showed endothelium swelling and microvasculature disruption in areas adjacent to the LCx and RCA territories. Anterior MI caused coronary microvascular dysfunction in the adjacent area, associated with a reduced MBF and regional wall motion.

Simplified Dynamic Phantom for Pediatric Renography: A Description of Instrument and its Performance.

OBJECTIVES: Renography is used for the diagnostic evaluation of pediatric patients with a suspected obstruction of urinary tract or impaired renal function. The recommended dose for children have been released by the European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and Japanese Society of Nuclear Medicine. Since acquisition counts in dynamic scintigraphy are affected by the administered doses and sensitivity of the scintillation camera, the scan procedure should be determined independently. In this study, we constructed simplified dynamic phantom imitating pediatric renography and tested its performance. METHODS: Simplified dynamic phantom consisted of three components (i.e., infusion, imitated kidney, and drainage sections). The infusion rates (mL/min) were determined by comparing the time activity curves obtained from patients with normal renal function. The time-points of the maximum counts (Tmax), as well as the two-thirds and one-half of the maximum counts (T2/3 and T1/2) were measured in different doses using the phantom with the best-match infusion rate and duration, and low-energy general-purpose (LEGP) or low-energy high-resolution (LEHR) collimators and applying different attenuations. RESULTS: The best-match infusion rates of the phantom to imitate the time activity curve of the normal renal function were 42.0, 1.0, 0.6, and 0.3 mL/min in the arterial, secretory, early-excretory, and late-excretory phases, respectively. When 30 MBq, LEHR collimator and non-water-equivalent phantom were applied, Tmax, T2/3, and T1/2 were 242±15.3, 220±10.0 and 317±25.2 seconds, respectively. Using LEGP collimator and (3 MBq of activity) 5-cm water-equivalent phantom, Tmax, T2/3, and T1/2 values were estimated as 242±5.8, 213±11.5, and 310±17.3 sec, respectively. CONCLUSION: Our simplified dynamic phantom for pediatric renography could imitate the time activity curves obtained from patients with normal renal function. Tmax, T2/3, and T1/2 could be measured under various settings of dose, collimator, and tissue attenuation.

Preliminary feasibility study on differential diagnosis between radiation-induced cerebral necrosis and recurrent brain tumor by means of [18F]fluoro-borono-phenylalanine PET/CT.

OBJECTIVES: A previous study reported that a differential diagnosis between glioblastoma progression and radiation necrosis by 4-borono-2-[18F]-fluoro-phenylalanine ([18F]FBPA) PET can be made based on lesion-to-normal ratio of [18F]FBPA accumulation. Two-dimensional data acquisition mode PET alone system, with in-plane resolution of 7.9 mm and axial resolution of 13.9 mm, was used. In the current study, we aimed to confirm the differential diagnostic capability of [18F]FBPA PET/CT with higher PET spatial resolution by three-dimensional visual inspection and by measuring mean standardized uptake value (SUVmean), maximum SUV (SUVmax), metabolic tumor volume (MTV), and total lesion (TL) [18F]FBPA uptake. METHODS: Twelve patients of glioma (9), malignant meningioma (1), hemangiopericytoma (1), and metastatic brain tumor (1) were enrolled. All had preceding radiotherapy. High-resolution three-dimensional data acquisition mode PET/CT with in-plane resolution of 4.07 mm and axial resolution of 5.41 mm was employed for imaging. Images were three-dimensionally analyzed using the PMOD software. SUVmean and SUVmax of lesion and normal brain were measured. Lesion MTV and TL FBPA uptake were calculated. The diagnostic accuracy of [18F]FBPA PET/CT in detecting recurrence (n = 6) or necrosis (n = 6) was verified by clinical follow-up. RESULTS: All parameters showed significantly higher values for tumor recurrence than for necrosis. SUVmean in recurrence was 2.95 ± 0.84 vs 1.18 ± 0.24 in necrosis (P = 0.014); SUVmax in recurrence was 4.63 ± 1.23 vs 1.93 ± 0.44 in necrosis (P = 0.014); MTV in recurrence was 44.92 ± 28.93 mL vs 10.66 ± 8.46 mL in necrosis (P = 0.032); and mean TL FBPA uptake in recurrence was 121.01 ± 50.48 g vs 12.36 ± 9.70 g in necrosis (P = 0.0029). CONCLUSION: In this preliminary feasibility study, we confirmed the possibility of differentiating tumor recurrence from radiation necrosis in patients with irradiated brain tumors by [18F]FBPA PET/CT using indices of SUVmean, SUVmax, MTV, and TL 18FBPA uptake.

Cell Spray Transplantation of Adipose-derived Mesenchymal Stem Cell Recovers Ischemic Cardiomyopathy in a Porcine Model.

BACKGROUND: Allogeneic adipose-derived mesenchymal stem cells (ADSC) are promising cell sources for cell therapy to treat ischemic cardiomyopathy (ICM). We hypothesized that ADSC transplantation via the new cell spray method may be a feasible, safe, and effective treatment for ICM. METHODS: Human ADSCs were acquired from white adipose tissue. Porcine ICM models were established by constriction of the left anterior descending coronary artery. Adipose-derived mesenchymal stem cells were spread over the surface of the heart via cell spray in fibrinogen and thrombin solutions. The cardiac function was compared with that of the control group. RESULTS: Adipose-derived mesenchymal stem cells were successfully transplanted forming a graft-like gel film covering the infarct myocardium. Premature ventricular contractions were rarely detected in the first 3 days after transplantation. Echocardiography and magnetic resonance imaging revealed improved cardiac performance of the ADSC group at 4 and 8 weeks after transplantation. Systolic and diastolic parameters were significantly greater in the ADSC group at 8 weeks after transplantation. Histological examination showed significantly attenuated left ventricular remodeling and a greater vascular density in the infarct border area in the ADSC group. Moreover, the coronary flow reserve was maintained, and expression levels of angiogenesis-related factors in the infarct border and remote areas were significantly increased. CONCLUSIONS: Spray method implantation of allogenic ADSCs can improve recovery of cardiac function in a porcine infarction model. This new allogenic cell delivery system may help to resolve current limitations of invasiveness and cost in stem cell therapy.

Evaluation of the default-mode network by quantitative 15O-PET: comparative study between cerebral blood flow and oxygen consumption.

OBJECTIVE: Resting-state functional MRI (rs-fMRI) has revealed the existence of a default-mode network (DMN) based on spontaneous oscillations of the blood oxygenation level-dependent (BOLD) signal. The BOLD signal reflects the deoxyhemoglobin concentration, which depends on the relationship between the regional cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO2). However, these two factors cannot be separated in BOLD rs-fMRI. In this study, we attempted to estimate the functional correlations in the DMN by means of quantitative 15O-labeled gases and water PET, and to compare the contribution of the CBF and CMRO2 to the DMN. METHODS: Nine healthy volunteers (5 men and 4 women; mean age, 47.0 ± 1.2 years) were studied by means of 15O-O2, 15O-CO gases and 15O-water PET. Quantitative CBF and CMRO2 images were generated by an autoradiographic method and transformed into MNI standardized brain template. Regions of interest were placed on normalized PET images according to the previous rs-fMRI study. For the functional correlation analysis, the intersubject Pearson's correlation coefficients (r) were calculated for all pairs in the brain regions and correlation matrices were obtained for CBF and CMRO2, respectively. We defined r > 0.7 as a significant positive correlation and compared the correlation matrices of CBF and CMRO2. RESULTS: Significant positive correlations (r > 0.7) were observed in 24 pairs of brain regions for the CBF and 22 pairs of brain regions for the CMRO2. Among them, 12 overlapping networks were observed between CBF and CMRO2. Correlation analysis of CBF led to the detection of more brain networks as compared to that of CMRO2, indicating that the CBF can capture the state of the spontaneous activity with a higher sensitivity. CONCLUSIONS: We estimated the functional correlations in the DMN by means of quantitative PET using 15O-labeled gases and water. The correlation matrix derived from the CBF revealed a larger number of brain networks as compared to that derived from the CMRO2, indicating that contribution to the functional correlation in the DMN is higher in the blood flow more than the oxygen consumption.