A chronic eyelid lesion in a child: multi-disciplinary approach to diagnosis, treatment and management of a highly atypical histiocytic lesion.

Malignant histiocytic neoplasm with histiocytic sarcoma phenotype is a rare malignant neoplasm, distinguished by malignant cells with phenotypic characteristics of mature tissue histiocytes. Histiocytic sarcoma typically presents as a primary malignancy, although can also present as a secondary malignancy, and is rarely seen in the pediatric population. Due to the rarity of this condition, diagnosis of histiocytic sarcoma is difficult and considered a diagnosis of exclusion. We describe a unique case of a chronic upper eyelid lesion with biopsy findings of a highly atypical histiocytic neoplasm initially concerning for histiocytic sarcoma; however, after integration of clinical findings, non-progressive and quiescent molecular profile, concluded to be an atypical juvenile xanthogranuloma in a child treated with excision and observation alone. This report highlights the importance of an integrated team approach to diagnosis of unusual histiocytic neoplasms.

Quantification and discriminative power of 18F-FE-PE2I PET in patients with Parkinson's disease.

RATIONALE: Dopamine transporter (DAT) imaging is an important adjunct in the diagnostic workup of patients with Parkinsonism. 18F-FE-PE2I is a suitable PET radioligand for DAT quantification and imaging with good pharmacokinetics. The aim of this study was to determine a clinical optimal simplified reference tissue-based image acquisition protocol and to compare the discriminatory value and effect size for 18F-FE-PE2I to that for 123I-FP-CIT scan currently used in clinical practice. METHODS: Nine patients with early Parkinson's disease (PD, 64.3 ± 6.8 years, 3M), who had previously undergone a 123I-FP-CIT scan as part of their diagnostic workup, and 34 healthy volunteers (HV, 47.7 ± 16.8 years, 13M) underwent a 60-min dynamic 18F-FE-PE2I PET-MR scan on a GE Signa 3T PET-MR. Based on dynamic data and MR-based VOI delineation, BPND, semi-quantitative uptake ratio and SUVR[t1-t2] images were calculated using either occipital cortex or cerebellum as reference region. For start-and-end time of the SUVR interval, three time frames [t1-t2] were investigated: [15-40] min, [40-60] min, and [50-60] min postinjection. Data for putamen (PUT) and caudate nucleus-putamen ratio (CPR) were compared in terms of quantification bias versus BPND and discriminative power. RESULTS: Using occipital cortex as reference region resulted in smaller bias of SUVR with respect to BPND + 1 and higher correlation between SUVR and BPND + 1 compared with using cerebellum, irrespective of SUVR [t1-t2] interval. Smallest bias was observed with the [15-40]-min time window, in accordance with previous literature. The correlation between BPND + 1 and SUVR was slightly better for the late time windows. Discriminant analysis between PD and HV using both PUT and CPR SUVRs showed an accuracy of ≥ 90%, for both reference regions and all studied time windows. Semi-quantitative 123I-FP-CIT and 18F-FE-PE2I values and relative decrease in the striatum for patients were highly correlated, with a higher effect size for 18F-FE-PE2I for PUT and CPR SUVR. CONCLUSION: 18F-FE-PE2I is a suitable radioligand for in vivo DAT imaging with high discriminative power between early PD and healthy controls. Whereas a [15-40]-min window has lowest bias with respect to BPND, a [50-60]-min time window at pseudoequilibrium can be advocated in terms of clinical feasibility with optimal discriminative power. The occipital cortex may be slightly preferable as reference region because of the higher time stability, stronger correlation of SUVR with BPND + 1, and lower bias. Moreover, the data suggest that the diagnostic accuracy of a 10-min static 18F-FE-PE2I scan is non-inferior compared with 123I-FP-CIT scan used in standard clinical practice.

ImmunoPET Imaging of CTLA-4 Expression in Mouse Models of Non-small Cell Lung Cancer.

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is expressed on the surface of activated T cells and some tumor cells, and is the target of the clinically approved monoclonal antibody ipilimumab. In this study, we investigate specific binding of radiolabeled ipilimumab to CTLA-4 expressed by human non-small cell lung cancer cells in vivo using positron emission tomography (PET). Ipilimumab was radiolabeled with 64Cu (t1/2 = 12.7 h) through the use of the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) to formulate 64Cu-DOTA-ipilimumab. CTLA-4 expression in three non-small cell lung cancer (NSCLC) cell lines (A549, H460, and H358) was verified and quantified by Western blot and enzyme-linked immunosorbent assays (ELISA). A receptor binding assay was utilized to monitor the binding and internalization of 64Cu-DOTA-ipilimumab in the NSCLC cell lines. Next, the biodistribution of 64Cu-DOTA-ipilimumab was mapped by longitudinal PET imaging up to 48 h after injection. Ex vivo biodistribution and histological studies were employed to verify PET results. By in vitro analysis, CTLA-4 was found to be expressed on all three NSCLC cell lines with A549 and H358 showing the highest and lowest level of expression, respectively. PET imaging and quantification verified these findings as the tracer accumulated highest in the A549 tumor model (9.80 ± 0.22%ID/g at 48 h after injection; n = 4), followed by H460 and H358 tumors with uptakes of 9.37 ± 0.26%ID/g and 7.43 ± 0.05%ID/g, respectively (n = 4). The specificity of the tracer was verified by injecting excess ipilimumab in A549 tumor-bearing mice, which decreased tracer uptake to 6.90 ± 0.51%ID/g at 48 after injection (n = 4). Ex vivo analysis following the last imaging session also corroborated these findings. 64Cu-DOTA-ipilimumab showed enhanced and persistent accumulation in CTLA-4-expressing tissues, which will enable researchers further insight into CTLA-4 targeted therapies in the future.

Evaluation of response after SBRT for liver tumors.

Stereotactic body radiotherapy (SBRT) has developed over the last few years for the treatment of primary and metastatic hepatic tumors. The tumoral and adjacent peritumoral modifications caused by this radiosurgery limit the evaluation of response by anatomic imaging and dimensional criteria alone, such as with RECIST. This suggests that it is of interest to also take into account the residual enhancement and hyper metabolism of these hepatic targets. We have reviewed the English language literature regarding the response of hepatic lesions treated by SBRT, and found that only seven articles were specifically concerned with this problem. The response of the hepatocellular carcinoma after SBRT has been studied specifically with multiphase enhanced CT-scan. Criteria set by the European Association of Study of the Liver better estimate response at each time point of follow up than RECIST does. Non-enhancement, reflecting tumor necrosis, is additionally an early indicator of response with extended response in time and a best non-enhancement percentage is observed at 12 months. The response after treatment by SBRT of cholangiocarcinoma has not yet generated a specific report. Use of RECIST criteria is also inadequate in the evaluation of response after SBRT for hepatic metastases. Response of liver metastases to SBRT is better assessed with a combination of size and enhancement pattern. The occurrence of a lobulated enhancement during follow up is efficient to predict local progression in a specific, reproducible, and sensitive way. Patients with FDG-avid hepatic metastases are also better evaluated with PET-CT and functional criteria than routine imaging and metric evaluation alone.

Fractionated stereotactic radiotherapy plus bevacizumab after response to bevacizumab plus irinotecan as a rescue treatment for high-grade gliomas.

AIM: To evaluate the possibility of implementing a new scheme of rescue treatment after relapse or progression of high-grade glioma (HGG) treated at the first-line with bevacizumab and irinotecan (BVZ+CPT11), evaluating the response and toxicity of associating BVZ and fractionated stereotactic radiotherapy (BVZ+FSRT). MATERIALS AND METHODS: We retrospectively analysed data from 59 patients with relapse of HGG. Nine patients with HGG relapse after treatment using the Stupp protocol that were treated with BVZ+CPT11 for progression between July 2007 and August 2012, after which the response was assessed according to the Revised Assessment in Neuro-Oncology (RANO) criteria. BVZ was administered at a dose of 10 mg/kg and FSRT up to a prescribed dose of 30 Gy, 500 cGy per fraction, three days a week. The median follow-up was 38 months. RESULTS: The treatment was well-tolerated by all patients. The response after nuclear magnetic resonance imaging (MRI) at 3-6 months was progression in two patients, stable disease in four, and three patients had a partial response. The median overall survival (OS) from diagnosis until death or the last control was 36.8 months. The median progression-free survival (PFS) was 10.8 months. The results from tumour sub-group analysis indicated that the PFS was not statistically significant although it seemed that it was higher in grade-III. The OS was higher in grade-III gliomas. CONCLUSIONS: The combination of BVZ+FSRT as a second-line HGG relapse rescue treatment is well-tolerated and seems to offer promising results. We believe that multi-centre prospective studies are needed to determine the long-term efficacy and toxicity of this therapeutic approach.

Applications of positron emission tomography in neuro-oncology: a clinical approach.

The field of neuro-oncology is concerned with some of the most challenging and difficult to treat conditions in medicine. Despite modern therapies patients diagnosed with primary brain tumours often have a poor prognosis. Imaging can play an important role in evaluating the disease status of such patients. In addition to the structural information derived from MRI and CT scans, positron emission tomography (PET) provides important quantitative metabolic assessment of brain tumours. This review describes the use of PET with radiolabelled glucose and amino acid analogues to aid in the diagnosis of tumours, differentiate between recurrent tumour and radiation necrosis and guide biopsy or treatment. [(18)F]Fluorodeoxyglucose (FDG) is the tracer that has been used most widely because it has a 2 h half life and can be transported to imaging centres remote from the cyclotron and radiochemistry facilities which synthesise the tracers. The high uptake of FDG in normal grey matter however limits its use in some low grade tumours which may not be visualised. [(11)C] methionine (MET) is an amino acid tracer with low accumulation in normal brain which can detect low grade gliomas, but its short 20 min half life has limited its use to imaging sites with their own cyclotron. The emergence of new fluorinated amino acid tracers like [(18)F]Fluoroethyl-l-tyrosine (FET) will likely increase the availability and utility of PET for patients with primary brain tumours. PET can, further, characterise brain tumours by investigating other metabolic processes such as DNA synthesis or thymidine kinase activity, phospholipid membrane biosynthesis, hypoxia, receptor binding and oxygen metabolism and blood flow, which will be important in the future assessment of targeted therapy.

Retrospective analysis of thyroid incidentalomas detected by [68Ga]Ga-PSMA-11 PET/CT.

BACKGROUND: Prostate cancer patients, undergo imaging procedures, with [68Ga]Ga-PSMA-11 PET/CT (prostate-specific membrane antigen based positron emission tomography/computed tomography) utilized for primary and secondary staging. PSMA thyroid incidentalomas (PTI) are discovered in the thyroid gland while imaging prostate cancer patients with [68Ga]Ga-PSMA-11 PET/CT. AIMS: The aim of the study was to determine the clinical significance of PTIs detected on [68Ga]Ga-PSMA-11 PET/CT. Another goal was to identify a possible threshold for the maximum standardized uptake value (SUVmax), above which a malignant growth could be suspected. STUDY DESIGN: A retrospective cross-sectional study. METHODS: 769 patients with prostat cancer who underwent [68Ga]Ga-PSMA-11 PET/CT scans in the nuclear medicine department of a tertiary care hospital between January 2020 and December 2022 were retrospectively screened in this study. We analyzed 67 patients in whom PTI was detected. Patients who exceeded the inclusion criteria had their thyroid ultrasonography and ultrasonography -guided fine needle aspiration findings analyzed. RESULTS: PTI was discovered in 67 patients (8%). 42 patients who met the inclusion and exclusion criteria were included in the study. Of the 4 malignant patients (9.5%) in the study population, 2 were classified as TIRADS 3 and 2 were classified as TIRADS 4. The cut-off SUVmax value was found to be 5.6. With 100% sensitivity and 47.37% specificity, a cutoff SUVmax of 5.3 was determined through receiver-operator characteristic analysis in order to predict malignant cytology. CONCLUSION: PTI is a significant clinical finding; most of diffuse and focal uptakes are frequently related to benign diseases. Each center should establish its own a possible SUVmax cut-off over which a malignant lesion should be suspected.

Myocardial Abscess After Myocarditis: Advantages of Multimodal Imaging Detecting the Rare Case of Fungal Abscess.

We discuss the rare case of a myocardial abscess of the left ventricle in a 42-year-old man on immunosuppressive therapy after fulminant myocarditis. Multimodal imaging detected the myocardial abscess along with other septic emboli caused by infection with aspergillus fumigatus, which could be treated effectively with antimycotic strategies. (Level of Difficulty: Intermediate.).

Anorexia and the hippocampus: A case report.

Eating disorders have been shown to be associated with epilepsy, typically associated with the temporal lobe and usually of non-dominant hemisphere origin. We report the case of a 56-year-old woman with drug resistant epilepsy, localized to the dominant left hippocampus. She experienced an increasing frequency of seizures over a two-year period associated with loss of appetite and substantial weight loss independent of antiseizure medication changes. Extensive workup eliminated gastrointestinal and paraneoplastic etiologies. There was no history of psychiatric illness, including anorexia nervosa. Pre-surgical workup showed mesial temporal sclerosis on MRI and video-EEG was consistent with ipsilateral medial temporal seizure onset. The patient underwent laser interstitial ablation of the left amygdala and hippocampus, which resulted in a cessation of seizures. Within 24 h of the laser ablation, her appetite returned to normal and, within 8 months she regained 26 lbs. To our knowledge, this is the first case report of a patient with dominant temporal lobe epilepsy with anorexia that was temporally associated with escalating seizure frequency and stopped with treatment and cessation of seizures, suggesting a causal and pathogenic relationship.

Imaging modalities for pulmonary tuberculosis in children: A systematic review.

Purpose: The optimal choice of protocol for diagnostic imaging in children with tuberculosis (TB) is a contemporary challenge due to the war in Ukraine, which potentially can create a steep rise in TB cases in Western Europe. We aimed to gather all primary research comparing imaging modalities and their diagnostic accuracies for pulmonary findings in children with suspected or confirmed pulmonary tuberculosis (PTB). Method: We searched the databases PubMed and Embase using pre-specified search terms, for English- and non-English published and un-published reports from the period 1972 to 2022. We retrieved reports via citation search in excluded literature reviews and systematic reviews. Studies were eligible if most of the study population was between 0 and 18 years of age with confirmed or suspected PTB, and study participants had described diagnostic images from two or more different imaging modalities. Results: A total of 15 studies investigated conventional chest X-Ray (CXR) and computed tomography (CT) in diagnosing PTB in children. Nine studies investigated the number of participants in where CT or CXR confirmed the diagnosis of TB, and all of them, including a total of 1244 patients, reported that findings compatible with TB were more frequently detected on CT than CXR. Only two studies did not include radiological findings as part of their diagnostic criteria for PTB, and combined they showed that CT diagnosed 54/54 (100 %) children with confirmed PTB, while CXR diagnosed 42/54 (78 %). Two studies compared magnetic resonance imaging (MRI) with CXR and showed that MRI diagnosed more children with PTB than CXR. One study reported a higher positive predictive value (PPV), sensitivity and specificity for PTB findings for MRI than CXR. One study compared CXR with high-kilovolt (high-kV) CXR, finding compatible sensitivity and specificity regarding confirmation of PTB. Two studies compared ultrasound (US) with CXR and found that US had a higher diagnostic yield and more often correctly identified consolidations, mediastinal LAP, and pleural effusion. Conclusion: CT showed a higher diagnostic accuracy for PTB findings than CXR, MRI and US, and should be the imaging modality of first choice when available. MRI had a higher sensitivity and specificity than CXR for LAP, pleural effusion, and cavitation. US was complimentary in initial diagnostic work-up and follow up. A diagnostic strategy for PTB in children according to local availability and expertise is proposed, as no evidence from this systematic review shows otherwise, in acknowledgement of the expertise in high TB-burdened countries. CT can be performed when in doubt, due to the higher diagnostic yield.

Towards modern post-coma care based on neuroscientific evidence.

Background: Understanding the mechanisms underlying human consciousness is pivotal to improve the prognostication and treatment of severely brain-injured patients. Consciousness remains an elusive concept and the identification of its neural correlates is an active subject of research, however recent neuroscientific advances have allowed scientists to better characterize disorders of consciousness. These breakthroughs question the historical nomenclature and our current management of post-comatose patients. Method: This review examines the contribution of consciousness neurosciences to the current clinical management of severe brain injury. It investigates the major impact of consciousness disorders on healthcare systems, the scientific frameworks employed to identify their neural correlates and how evidence-based data from neuroimaging research have reshaped the landscape of post-coma care in recent years. Results: Our increased ability to detect behavioral and neurophysiological signatures of consciousness has led to significant changes in taxonomy and clinical practice. We advocate for a multimodal framework for the management of severely brain-injured patients based on precision medicine and evidence-based decisions, integrating epidemiology, health economics and neuroethics. Conclusions: Major progress in brain imaging and clinical assessment have opened the door to a new era of post-coma care based on standardized neuroscientific evidence. We highlight its implications in clinical applications and call for improved collaborations between researchers and clinicians to better translate findings to the bedside.

Feasibility of biology-guided radiotherapy for metastatic renal cell carcinoma driven by PSMA PET imaging.

Background: Biology-guided radiotherapy (BgRT) is a novel treatment where the detection of positron emission originating from a volume called the biological tracking zone (BTZ) initiates dose delivery. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is a novel imaging technique that may improve patient selection for metastasis-directed therapy in renal cell carcinoma (RCC). This study aims to determine the feasibility of BgRT treatment for RCC. Material and methods: All consecutive patients that underwent PSMA PET/CT scan for RCC staging at our institution between 2014 and 2020 were retrospectively considered for inclusion. GTVs were contoured on the CT component of the PET/CT scan. The tumor-to-background ratio was quantified from the normalized standardized uptake value (nSUV), defined as the ratio between SUVmax inside the GTV and SUVmean inside the margin expansion. Tumors were classified suitable for BgRT if (1) nSUV was greater or equal to an nSUV threshold and (2) if the BTZ was free of any PET-avid region other than the tumor. Results: Out of this cohort of 83 patients, 47 had metastatic RCC and were included in this study. In total, 136 tumors were delineated, 1 to 22 tumors per patient, mostly in lung (40%). Using a margin expansion of 5 mm/10 mm/20 mm and nSUV threshold = 3, 66%/63%/41% of tumors were suitable for BgRT treatment. Uptake originating from another tumor, the kidney, or the liver was typically inside the BTZ in tumors judged unsuitable for BgRT. Conclusions: More than 60% of tumors were found to be suitable for BgRT in this cohort of patients with RCC. However, the proximity of PET-avid organs such as the liver or the kidney may affect BgRT delivery.

Imaging biomarkers to stratify lymph node metastases in abdominal CT - Is radiomics superior to dual-energy material decomposition?

Purpose: To assess the potential of radiomic features in comparison to dual-energy CT (DECT) material decomposition to objectively stratify abdominal lymph node metastases. Materials and methods: In this retrospective study, we included 81 patients (m, 57; median age, 65 (interquartile range, 58.7-73.3) years) with either lymph node metastases (n = 36) or benign lymph nodes (n = 45) who underwent contrast-enhanced abdominal DECT between 06/2015-07/2019. All malignant lymph nodes were classified as unequivocal according to RECIST criteria and confirmed by histopathology, PET-CT or follow-up imaging. Three investigators segmented lymph nodes to extract DECT and radiomics features. Intra-class correlation analysis was applied to stratify a robust feature subset with further feature reduction by Pearson correlation analysis and LASSO. Independent training and testing datasets were applied on four different machine learning models. We calculated the performance metrics and permutation-based feature importance values to increase interpretability of the models. DeLong test was used to compare the top performing models. Results: Distance matrices and t-SNE plots revealed clearer clusters using a combination of DECT and radiomic features compared to DECT features only. Feature reduction by LASSO excluded all DECT features of the combined feature cohort. The top performing radiomic features model (AUC = 1.000; F1 = 1.000; precision = 1.000; Random Forest) was significantly superior to the top performing DECT features model (AUC = 0.942; F1 = 0.762; precision = 0.800; Stochastic Gradient Boosting) (DeLong < 0.001). Conclusion: Imaging biomarkers have the potential to stratify unequivocal lymph node metastases. Radiomics models were superior to DECT material decomposition and may serve as a support tool to facilitate stratification of abdominal lymph node metastases.

Coronary Flow Reserve, Inflammation, and Myocardial Strain: The CIRT-CFR Trial.

Inflammation is a key determinant of cardiovascular outcomes, but its role in heart failure is uncertain. In patients with cardiometabolic disease enrolled in the prospective, multicenter ancillary study of CIRT (Cardiovascular Inflammation Reduction Trial), CIRT-CFR (Coronary Flow Reserve to Assess Cardiovascular Inflammation), impaired coronary flow reserve was independently associated with increased inflammation and myocardial strain despite well-controlled lipid, glycemic, and hemodynamic profiles. Inflammation modified the relationship between CFR and myocardial strain, disrupting the association between cardiac blood flow and function. Future studies are needed to investigate whether an early inflammation-mediated reduction in CFR capturing microvascular ischemia may lead to heart failure in patients with cardiometabolic disease. (Cardiovascular Inflammation Reduction Trial [CIRT]; NCT01594333; Coronary Flow Reserve to Assess Cardiovascular Inflammation [CIRT-CFR]; NCT02786134).

Meningioma grading based on positron emission tomography: A systematic review and meta-analysis.

Introduction: Meningiomas are the most common central nervous system tumor in adults. Knowledge of the tumor grade can guide optimal treatment timing and shape personalized follow-up strategies. Positron emission tomography (PET) has been utilized for the metabolic assessment of various intracranial space-occupying lesions. Herewith, we set out to evaluate the diagnostic accuracy of PET for the noninvasive assessment of meningioma's grade. Materials and methods: The Medline, Scopus and Cochrane databases were systematically searched in March 2022 for studies that evaluated the sensitivity and specificity of PET compared to the gold standard of histological diagnosis in the grading of meningiomas. Summary statistics will be calculated and scatter plots, summary curve from the HSROC model and posterior predictions by empirical Bayes estimates will be presented. Results: Five studies consisting of 242 patients with a total of 196 low-grade (Grade 1) and 46 high grade (Grade 2/3) meningiomas were included in our analysis. Three of the included studies used 18F-FDG, one study used 18F-FLT and one used(Whiting et al., 2011) 18 F-FET as PET tracers. The pooled sensitivity was 76% (95% CI: 52%-91%) and the pooled specificity was 89% (95% CI: 83%-93%). The diagnostic odds ratio was 27.17 (95% CI: 9.22-80.06), the positive likelihood ratio was 7.18 (95% CI: 4.54-11.34) and the negative likelihood ratio was 0.26 (95% CI: 0.11-0.61). Conclusion: PET is a promising and viable option as a noninvasive imaging tool to differentiate the meningioma grades. However, currently it cannot overtake the gold standard of histological grade confirmation. More studies are required for further validation and refinement of this imaging technique and assessment of other radiotracers as well.

18F-DCFPyL (PSMA) PET as a radiotherapy response assessment tool in metastatic prostate cancer.

Background: Prostate Specific Membrane Antigen (PSMA) - positron emission tomography (PET) guides metastasis-directed radiotherapy (MDRT) in prostate cancer (PrCa). However, its value as a treatment response assessment tool after MDRT remains unclear. Importantly, there is limited understanding of the potential of radiotherapy (RT) to alter PSMA gene (folate hydrolase 1; FOLH1) expression. Methodology: We reviewed a series of 11 men with oligo-metastatic PrCa (25 metastasis sites) treated with MDRT before re-staging with 18F-DCFPyL (PSMA) PET upon secondary recurrence. Acute effects of RT on PSMA protein and mRNA levels were examined with qPCR and immunoblotting in human wild-type androgen-sensitive (LNCap), castrate-resistant (22RV1) and castrate-resistant neuroendocrine (PC3 and DU145) PrCa cell lines. Xenograft tumors were analyzed with immunohistochemistry. Further, we examined PSMA expression in untreated and irradiated radio-resistant (RR) 22RV1 (22RV1-RR) and DU145 (DU145-RR) cells and xenografts selected for survival after high-dose RT. Results: The majority of MDRT-treated lesions showed lack of PSMA-PET/CT avidity, suggesting treatment response even after low biological effective dose (BED) MDRT. We observed similar high degree of heterogeneity of PSMA expression in both human specimens and in xenograft tumors. PSMA was highly expressed in LNCap and 22RV1 cells and tumors but not in the neuroendocrine PC3 and DU145 models. Single fraction RT caused detectable reduction in PSMA protein but not in mRNA levels in LNCap cells and did not significantly alter PSMA protein or mRNA levels in tissue culture or xenografts of the other cell lines. However, radio-resistant 22RV1-RR cells and tumors demonstrated marked decrease of PSMA transcript and protein expression over their parental counterparts. Conclusions: PSMA-PET may be a promising tool to assess RT response in oligo-metastatic PrCa. However, future systematic investigation of this concept should recognize the high degree of heterogeneity of PSMA expression within prostate tumors and the risk for loss of PSMA expression in tumor surviving curative courses of RT.

Semi-automated 18F-FDG PET segmentation methods for tumor volume determination in Non-Hodgkin lymphoma patients: a literature review, implementation and multi-threshold evaluation.

In the treatment of Non-Hodgkin lymphoma (NHL), multiple therapeutic options are available. Improving outcome predictions are essential to optimize treatment. The metabolic active tumor volume (MATV) has shown to be a prognostic factor in NHL. It is usually retrieved using semi-automated thresholding methods based on standardized uptake values (SUV), calculated from 18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG PET) images. However, there is currently no consensus method for NHL. The aim of this study was to review literature on different segmentation methods used, and to evaluate selected methods by using an in house created software tool. A software tool, MUltiple SUV Threshold (MUST)-segmenter was developed where tumor locations are identified by placing seed-points on the PET images, followed by subsequent region growing. Based on a literature review, 9 SUV thresholding methods were selected and MATVs were extracted. The MUST-segmenter was utilized in a cohort of 68 patients with NHL. Differences in MATVs were assessed with paired t-tests, and correlations and distributions figures. High variability and significant differences between the MATVs based on different segmentation methods (p < 0.05) were observed in the NHL patients. Median MATVs ranged from 35 to 211 cc. No consensus for determining MATV is available based on the literature. Using the MUST-segmenter with 9 selected SUV thresholding methods, we demonstrated a large and significant variation in MATVs. Identifying the most optimal segmentation method for patients with NHL is essential to further improve predictions of toxicity, response, and treatment outcomes, which can be facilitated by the MUST-segmenter.

Artificial intelligence to predict outcomes of head and neck radiotherapy.

Head and neck radiotherapy induces important toxicity, and its efficacy and tolerance vary widely across patients. Advancements in radiotherapy delivery techniques, along with the increased quality and frequency of image guidance, offer a unique opportunity to individualize radiotherapy based on imaging biomarkers, with the aim of improving radiation efficacy while reducing its toxicity. Various artificial intelligence models integrating clinical data and radiomics have shown encouraging results for toxicity and cancer control outcomes prediction in head and neck cancer radiotherapy. Clinical implementation of these models could lead to individualized risk-based therapeutic decision making, but the reliability of the current studies is limited. Understanding, validating and expanding these models to larger multi-institutional data sets and testing them in the context of clinical trials is needed to ensure safe clinical implementation. This review summarizes the current state of the art of machine learning models for prediction of head and neck cancer radiotherapy outcomes.

Endoscopic submucosal dissection of a tumor in the upper esophageal sphincter and piriform sinus.

Video 1Endoscopic submucosal dissection of a tumor in the upper esophageal sphincter and piriform sinus.

Pericardiectomy for Constrictive Pericarditis in a Young Patient With Erdheim-Chester Disease.

Erdheim-Chester Disease (ECD) is an extremely rare non-Langerhans histiocytosis that most often presents in the fifth to seventh decades of life. In this case report, we present a 34-year-old woman who underwent successful pericardiectomy for constrictive pericarditis secondary to ECD, which is the youngest reported patient with ECD to undergo pericardiectomy. (Level of Difficulty: Advanced.).