Quantitative evaluation of PSMA PET imaging using a realistic anthropomorphic phantom and shell-less radioactive epoxy lesions

Background Positron emission tomography (PET) with prostate specific membrane antigen (PSMA) have shown superior performance in detecting metastatic prostate cancers. Relative to [18F]fluorodeoxyglucose ([18F]FDG) PET images, PSMA PET images tend to visualize significantly higher-contrast focal lesions. We aim to evaluate segmentation and reconstruction algorithms in this emerging context. Specifically, Bayesian or maximum a posteriori (MAP) image reconstruction, compared to standard ordered subsets expectation maximization (OSEM) reconstruction, has received significant interest for its potential to reach convergence with minimal noise amplifications. However, few phantom studies have evaluated the quantitative accuracy of such reconstructions for high contrast, small lesions (sub-10 mm) that are typically observed in PSMA images. In this study, we cast 3 mm–16-mm spheres using epoxy resin infused with a long half-life positron emitter (sodium-22; 22Na) to simulate prostate cancer metastasis. The anthropomorphic Probe-IQ phantom, which features a liver, bladder, lungs, and ureters, was used to model relevant anatomy. Dynamic PET acquisitions were acquired and images were reconstructed with OSEM (varying subsets and iterations) and BSREM (varying β parameters), and the effects on lesion quantitation were evaluated. Results The 22Na lesions were scanned against an aqueous solution containing fluorine-18 (18F) as the background. Regions-of-interest were drawn with MIM Software using 40% fixed threshold (40% FT) and a gradient segmentation algorithm (MIM’s PET Edge+). Recovery coefficients (RCs) (max, mean, peak, and newly defined “apex”), metabolic tumour volume (MTV), and total tumour uptake (TTU) were calculated for each sphere. SUVpeak and SUVapex had the most consistent RCs for different lesion-to-background ratios and reconstruction parameters. The gradient-based segmentation algorithm was more accurate than 40% FT for determining MTV and TTU, particularly for lesions $$\le$$ ≤ 6 mm in diameter (R2 = 0.979–0.996 vs. R2 = 0.115–0.527, respectively). Conclusion An anthropomorphic phantom was used to evaluate quantitation for PSMA PET imaging of metastatic prostate cancer lesions. BSREM with β = 200–400 and OSEM with 2–5 iterations resulted in the most accurate and robust measurements of SUVmean, MTV, and TTU for imaging conditions in 18F-PSMA PET/CT images. SUVapex, a hybrid metric of SUVmax and SUVpeak, was proposed for robust, accurate, and segmentation-free quantitation of lesions for PSMA PET.

Excitatory-Inhibitory Homeostasis and Diaschisis: Tying the Local and Global Scales in the Post-stroke Cortex

Maintaining a balance between excitatory and inhibitory activity is an essential feature of neural networks of the neocortex. In the face of perturbations in the levels of excitation to cortical neurons, synapses adjust to maintain excitatory-inhibitory (EI) balance. In this review, we summarize research on this EI homeostasis in the neocortex, using stroke as our case study, and in particular the loss of excitation to distant cortical regions after focal lesions. Widespread changes following a localized lesion, a phenomenon known as diaschisis, are not only related to excitability, but also observed with respect to functional connectivity. Here, we highlight the main findings regarding the evolution of excitability and functional cortical networks during the process of post-stroke recovery, and how both are related to functional recovery. We show that cortical reorganization at a global scale can be explained from the perspective of EI homeostasis. Indeed, recovery of functional networks is paralleled by increases in excitability across the cortex. These adaptive changes likely result from plasticity mechanisms such as synaptic scaling and are linked to EI homeostasis, providing a possible target for future therapeutic strategies in the process of rehabilitation. In addition, we address the difficulty of simultaneously studying these multiscale processes by presenting recent advances in large-scale modeling of the human cortex in the contexts of stroke and EI homeostasis, suggesting computational modeling as a powerful tool to tie the meso- and macro-scale processes of recovery in stroke patients.

Local Assessment of the Immunohistochemical Expression of Foxp3 + Regulatory T Lymphocytes in the Different Pathological Forms Associated with Bovine Paratuberculosis

Background Mycobacterium avium subsp. paratuberculosis infected animals show a variety of granulomatous lesions: from focal forms, restricted to the gut-associated lymphoid tissue (GALT), related to latency and resistance, to diffuse lesions, with abundant (multibacillary) or scant (paucibacillary) bacteria, seen in clinical stages. Factors that determine the response to the infection and responsible for the occurrence of the different types of lesion are still not fully determined. It has been seen that regulatory T cells (Treg) play an important role in the progress of various diseases where they act on the limitation of the immunopathology associated with the immune response. In the case of paratuberculosis (PTB) the role of Treg lymphocytes in the immunity against Map is far away to be completely understood; therefore, several studies addressing this subject have appeared recently. The aim of this work was to assess, by immunohistochemical methods, the presence of Foxp3+ T lymphocytes in intestinal samples with different types of lesions seen in cows with PTB. Methods Intestinal samples of twenty cows showing the different pathological forms of PTB were evaluated: uninfected controls (n = 5), focal lesions (n = 5), diffuse paucibacillary (n = 5) and diffuse multibacillary (n = 5) forms. Foxp3+ lymphocyte distribution was assessed by differential cell count in intestinal lamina propria (LP), gut-associated lymphoid tissue (GALT) and mesenteric lymph node (MLN). Results A significant increase in the number of Foxp3+ T cells was observed in all infected animals, but this increase was only significant in cows with focal lesions and, to a lesser extent, in animals with diffuse paucibacillary forms. The former showed the highest numbers, significantly different from those found in cows with diffuse lesions, where no differences were noted between the two forms. No specific distribution pattern was observed within the granulomatous lesions in any of the groups. Conclusions The increase of Foxp3+ T cells in focal forms, that have been associated with latency or resistance to infection, suggest an anti-inflammatory action of these cells at these stages, helping to prevent exacerbation of the inflammatory response, as occurs in diffuse forms, responsible for the appearance of clinical signs.

Interleukin-10 knockout mice do not reliably exhibit macroscopic inflammation: a natural history endoscopic surveillance study

Background: Interleukin (IL)-10 knockout (KO) mice, used as a model for inflammatory bowel disease (IBD), develop chronic enterocolitis. Endoscopy, the gold standard for evaluation of human mucosal health, is not widely available for murine models. We aimed to assess the natural history of left-sided colitis in IL-10 KO mice via serial endoscopies. Methods: BALB/cJ IL10 KO mice underwent regular endoscopic assessments from 2 up to 8 months of age. Procedures were recorded and blindly evaluated using a 4-component endoscopic score: mucosal wall transparency, intestinal bleeding, focal lesions and perianal lesions (0-3 points each). An endoscopic score ≥1 point was considered as the presence of colitis/flare. Results: IL-10 KO mice (N=40, 9 female) were assessed. Mean age at first endoscopy was 62.5±2.5 days; average number of procedures per mouse was 6.0±1.3. A total of 238 endoscopies were conducted every 24.8±8.3 days, corresponding to 124.1±45.2 days of surveillance per mouse (13.6 years cumulative surveillance). Thirty-three endoscopies in 24 mice (60%) detected colitis, mean endoscopy score 2.5±1.3 (range: 1-6.3). Nineteen mice (47.5%) had one episode of colitis and 5 (12.5%) had 2-3 episodes. All exhibited complete spontaneous healing on subsequent endoscopies. Conclusions: In this largest endoscopic surveillance study of IL-10 KO mice, 40% of mice did not develop endoscopic left-sided colitis. Furthermore, IL-10 KO mice did not exhibit persistent colitis and universally exhibited complete spontaneous healing without treatment. The natural history of colitis in IL-10 KO mice may not be comparable with that of IBD in humans and requires careful consideration.

THE RESULTS OF SURGICAL TREATMENT OF VARIOUS FORMS OF FOCAL LESIONS OF THE LIVER

Объем резекции очень важен при хирургическом лечении очаговых заболеваний печени. Операции с использованием современного технического оборудования позволили снизить количество осложнений с 42,9% до 19,7%, а при масштабных резекциях - с 54,9% до 20,9%. Общая послеоперационная смертность снизилась с 7,1% до 2,5%. Долгосрочные улучшения результатов (с 74,3% до 89,6%) и снижение неудовлетворительных результатов с 17,6% до 5,8% могут быть достигнуты путем применения радикальных методов хирургического лечения различных форм очаговых поражений печени. У пациентов с заболеваниями печени может быть возможно улучшить выживаемость два и три года с 37,5% до 53,3% и с 25 до 40%. The volume of resection is very important in the surgical treatment of focal liver diseases. Operations using modern technical equipment allowed to reduce the number of complications from 42.9% to 19.7%, and with large-scale resections - from 54.9% to 20.9%. Total postoperative mortality decreased from 7.1% to 2.5%. Long-term improvement of results (from 74.3% to 89.6%) and a decrease in unsatisfactory results from 17.6% to 5.8% can be achieved by applying radical methods of surgical treatment of various forms of focal liver lesions. In patients with liver disease, it may be possible to improve survival for two and three years from 37.5% to 53.3% and from 25 to 40%.

Development of a new risk stratification system for patients with newly diagnosed multiple myeloma using R-ISS and 18F-FDG PET/CT

In multiple myeloma (MM), a high number of focal lesions (FL) detected using positron emission tomography/computed tomography (PET/CT) was found to be associated with adverse prognosis. To design a new risk stratification system that combines the Revised International Staging System (R-ISS) with FL, we analyzed the data of 380 patients with newly diagnosed MM (NDMM) who underwent 18F-fluorodeoxyglucose (18F-FDG) PET/CT upon diagnosis. The K-adaptive partitioning algorithm was adopted to define subgroups with homogeneous survival. The combined R-ISS with PET/CT classified NDMM patients into four groups: R-ISS/PET stage I (n = 31; R-ISS I with FL ≤ 3), stage II (n = 156; R-ISS I with FL > 3 and R-ISS II with FL ≤ 3), stage III (n = 162; R-ISS II with FL > 3 and R-ISS III with FL ≤ 3), and stage IV (n = 31; R-ISS III with FL > 3). The 2-year overall survival rates for stages I, II, III, and IV were 96.7%, 89.8%, 74.7%, and 50.3%. The 2-year progression-free survival rates were 84.1%, 64.7%, 40.8%, and 17.1%, respectively. The new R-ISS/PET was successfully validated in an external cohort. This new system had a remarkable prognostic power for estimating the survival outcomes of patients with NDMM. This system helps discriminate patients with a good prognosis from those with a poor prognosis more precisely.

Disrupted Functional Connectivity Within and Between Resting-State Networks in the Subacute Stage of Post-stroke Aphasia

Background: Post-stroke aphasia (PSA) results from brain network disorders caused by focal stroke lesions. However, it still remains largely unclear whether the impairment is present in intra- and internetwork functional connectivity (FC) within each resting-state network (RSN) and between RSNs in the subacute stage of PSA.Objectives: This study aimed to investigate the resting-state FC within and between RSNs in patients with PSA and observe the relationships between FC alterations and Western Aphasia Battery (WAB) measures.Methods: A total of 20 individuals with subacute PSA and 20 healthy controls (HCs) were recruited for functional MRI (fMRI) scanning, and only patients with PSA underwent WAB assessment. Independent component analysis was carried out to identify RSNs. Two-sample t-tests were used to calculate intra- and internetwork FC differences between patients with PSA and HCs. The results were corrected for multiple comparisons using the false discovery rate (FDR correction, p < 0.05). Partial correlation analysis was performed to observe the relationship between FC and WAB scores with age, gender, mean framewise displacement, and lesion volume as covariates (p < 0.05).Results: Compared to HCs, patients with PSA showed a significant increase in intranetwork FC in the salience network (SN). For internetwork FC analysis, patients showed a significantly increased coupling between left frontoparietal network (lFPN) and SN and decreased coupling between lFPN and right frontoparietal network (rFPN) as well as between lFPN and posterior default mode network (pDMN) (FDR correction, p < 0.05). Finally, a significant positive correlation was found between the intergroup difference of FC (lFPN-rFPN) and auditory-verbal comprehension (p < 0.05).Conclusion: Altered FC was revealed within and between multiple RSNs in patients with PSA at the subacute stage. Reduced FC between lFPN and rFPN was the key element participating in language destruction. These findings proved that PSA is a brain network disorder caused by focal lesions; besides, it may improve our understanding of the pathophysiological mechanisms of patients with PSA at the subacute stage.

Diagnostic Value of CEUS LI-RADS Version 2017 in Differentiating AFP-Negative Hepatocellular Carcinoma from Other Primary Malignancies of the Liver

Purpose: To explore the diagnostic value of Contrast-enhanced Ultrasound Liver Imaging Reporting and Data System version 2017 (CEUS LI-RADS v2017) in differentiating alpha-fetoprotein (AFP)-negative hepatocellular carcinoma (HCC) from other primary malignancies (OM) of the liver. Methods: The data of 99 patients with primary liver malignant tumors confirmed by surgical pathology and AFP-negative from January 2018 to January 2021 were retrospectively analyzed, and the lesions were divided into 61 cases in the AFP-negative HCC group and 38 cases in the OM group according to the pathological findings, the CEUS features of the lesions were analyzed and the lesions were classified according to the CEUS LI-RADS v2017. Comparison of CEUS features between the two groups was performed using the χ2 test. The sensitivity, specificity, positive predictive value, negative predictive value, and coincidence rate of CEUS LI-RADS v2017 for the diagnosis of AFP-negative HCC and OM were calculated using pathological findings as the gold standard. Results: The differences in features of arterial phase enhancement and wash-out between the HCC and OM groups were statistically significant (p < 0.05). The sensitivity of diagnosing HCC by LR-5 was 62.3% and the specificity was 92.1%. The sensitivity of diagnosing OM by LR-M was 92.1% and the specificity was 83.6%. Conclusions: When AFP is negative in patients with intrahepatic focal lesions, LR-5 has high specificity but low sensitivity in the diagnosis of HCC, and LR-M has high sensitivity and specificity in the diagnosis of OM. CEUS LI-RADS is a tool to differentiate AFP-negative HCC and OM effectively.