Interim FDG-PET analysis to identify patients with aggressive non-Hodgkin lymphoma who benefit from treatment intensification: a post-hoc analysis of the PETAL trial

The randomized PETAL trial failed to demonstrate a benefit of interim FDG-PET (iPET)-based treatment intensification over continued standard therapy with CHOP (plus rituximab (R) in CD20-positive lymphomas). We hypothesized that PET analysis of all lymphoma manifestations may identify patients who benefitted from treatment intensification. A previously developed neural network was employed for iPET analysis to identify the highest pathological FDG uptake (max-SUVAI) and the mean FDG uptake of all lymphoma manifestations (mean-SUVAI). High mean-SUVAI uptake was determined separately for iPET-positive and iPET-negative patients. The endpoint was time-to-progression (TTP). There was a significant interaction of additional rituximab and mean-SUVAI in the iPET-negative group (HR = 0.6, p < 0.05). Patients with high mean-SUVAI had significantly prolonged TTP when treated with 6xR-CHOP + 2 R (not reached versus 52 months, p < 0.05), whereas max-SUVmanual failed to show an impact of additional rituximab. In the iPET-positive group, patients with high mean-SUVAI had a significantly longer TTP with (R-)CHOP than with the Burkitt protocol (14 versus 4 months, p < 0.01). Comprehensive iPET evaluation may provide new prognosticators in aggressive lymphoma. Additional application of rituximab was associated with prolonged TTP in iPET-negative patients with high mean-SUVAI. Comprehensive iPET interpretation could identify high-risk patients who benefit from study-specific interventions.

Time after Synthesis and Time after Injection Do Not Affect Diagnostic Quality of [18F]F-PSMA 1007 PET

Simple Summary

The total number of PSMA-PET-CT examinations for the staging of prostate cancer patients has increased in recent years, following its superior imaging properties. Fluorinated PSMA ligands can be produced in larger amounts, facilitating higher patient throughput compared to the initially developed gallium labelled PSMA-tracers; allowing PET in only a few patients per synthesis. This results in a longer time after, typically early morning, radiochemical synthesis (TaS) of [¹⁸]F-PSMA when the PSMA-PET scan is performed. Moreover, novel fluorinated-PSMA compounds are injected around two hours before PET-CT and the time after injection (TaI) might show significant deviation. [18F]-PSMA PET offers improved detection rates in the proximity of the urinary tract; however, it has the disadvantage of more unspecific uptake, e.g., in the skeleton. This article focusses on the question whether TaS or TaI have an influence on uptake patterns in malignant lesions and healthy tissue.

Abstract

PET imaging using PSMA ligands is increasingly used for staging in prostate cancer patients in different clinical indications. Unlike [⁶⁸Ga]Ga-labeled PSMA ligands, fluorinated compounds can be produced in large amounts; thus, they can be used for a higher number of patients. One concern is that in patients studied a long time after synthesis (TaS) or time after injection (TaI), the specific activity may decline; thus, the signal may be lower in these patients. In this study, we investigated a potential effect of TaS and TaI on image quality. In total, 134 consecutive patients were included in this retrospective analysis on the effect of TaS and TaI on uptake in prostate cancer lesions. All the patients underwent [¹⁸F]F-PSMA-1007 PET-CT from 99 min up to 549 min after tracer quality control. TaS and TaI were compared to the quantitative tumoral uptake parameters SUVmax and SUVpeak. In a second exploratory part of the analysis, TaS and TaI were correlated to a physiological tracer uptake in different organs. TaS and TaI did not affect the SUVmax and SUVpeak in tumor lesions in [¹⁸F]F-PSMA-1007 PET. The physiological uptake in salivary glands, lacrimal glands and the ganglia, spleen and urine was not significantly correlated to TaS or TaI; in contrast to the mean liver uptake, showing a weak, but significant correlation to TaS. The [¹⁸F]F-PSMA-1007 uptake in prostate cancer lesions is not significantly dependent on the TaS and TaI. These results are extremely reassuring when performing [¹⁸F]F-PSMA-1007 PET a considerable time after synthesis.

Prostate-specific membrane antigen and fibroblast activation protein distribution in prostate cancer: preliminary data on immunohistochemistry and PET imaging

Introduction

Fibroblast activation protein (FAP) has been recently presented as new imaging target for malignant diseases and offers high contrast to surrounding normal tissue. FAP tracer uptake has been reported in various tumor entities. The aim of this study was to compare FAP and Prostate-specific membrane antigen (PSMA) expression in primary prostate cancer employing histological analyses and PET imaging in two small patient collectives.

Methods

Two independent small patient collectives were included in this study. For cohort A, data of 5 prostate cancer patients and 3 patients with benign prostate hyperplasia were included. Patients with prostate cancer were initially referred for PSMA PET staging. Radical prostatectomy was performed in all patients and prostate specimen of patients and biopsies of healthy controls were available for further evaluation. Histological workup included HE and immunohistochemistry using PSMA Ab, FAP Ab. Cohort B consists of 6 Patients with diagnosed mCRPC and available PSMA as well as FAP PET.

Results

Patients with proven prostate cancer infiltration exhibited strong positivity for PSMA in both primary tumors and lymph node metastases while stainings for FAP were found positive in some cases, but not all (2/5). Controls with BPH presented moderate PSMA staining and in one case also with a positive FAP staining (1/3). PET imaging with FAP seemed to result in more precise results in case of low PSMA expression than PSMA-PET.

Conclusions

While PSMA staining intensity is a valid indicator of prostate cancer in both primary tumor and lymph node metastases, the expression of FAP seems to be heterogeneous but not necessarily linked to cancer-associated fibroblasts. It is also present in inflammation-associated myofibroblasts. Therefore, its ultimate role in prostate cancer diagnosis remains a subject of discussion.

Evaluation of 68Ga-PSMA-11 PET-MRI in Patients with Advanced Prostate Cancer Receiving 177Lu-PSMA-617 Therapy: A Radiomics Analysis

¹⁷⁷Lutetium PSMA-617 (Lu-PSMA) therapy in patients with metastatic castration resistant prostate cancer (mCRPC) has gained visibility through the ongoing phase III trial. The data on prediction of therapy outcome and survival out of pretherapeutic imaging parameters is still sparse. In this study, the predictive and prognostic value of radiomic features from ⁶⁸Ga-PSMA-11 PET-MRI are analyzed. In total, 21 patients with mCRPC underwent ⁶⁸Ga-PSMA-11 PET-MRI before Lu-PSMA therapy. The PET-positive tumor volume was defined and transferred to whole-body T2-, T1- and contrast-enhanced T1-weighted MRI-sequences. The radiomic features from PET and MRI sequences were extracted by using a freely available software package. For selecting features that allow differentiation of biochemical response (PSA decrease > 50%), a stepwise dimension reduction was performed. Logistic regression models were fitted, and selected features were tested for their prognostic value (overall survival) in all patients. Eight patients achieved biochemical response after Lu-PSMA therapy. Ten independent radiomic features differentiated well between responders and non-responders. The logistic regression model, including the feature interquartile range from T2-weighted images, revealed the highest accuracy (AUC = 0.83) for the prediction of biochemical response after Lu-PSMA therapy. Within the final model, patients with a biochemical response (p = 0.003) and higher T2 interquartile range values in pre-therapeutic imaging (p = 0.038) survived significantly longer. This proof-of-concept study provides first evidence on a potential predictive and prognostic value of radiomic analysis of pretherapeutic ⁶⁸Ga-PSMA-11 PET-MRI before Lu-PSMA therapy.

Total tumor volume reduction and low PSMA expression in patients receiving Lu-PSMA therapy

Background: [¹⁷⁷Lu]-PSMA-617 (Lu-PSMA) therapy is a promising therapeutic option for end-stage prostate cancer patients. Early treatment response at the first restaging after two therapy cycles might correlate with high treatment efficacy and long overall survival (OS). Therefore, the aim of this study was to evaluate whether early reduction in tumor volume is a positive prognosticator for OS. To this end, PSMA PET prior to therapy (baseline) and at first restaging after two therapy cycles (interim; i.e., 12 weeks) were compared.

Methods: Patients with metastatic castration-resistant prostate cancer who received Lu-PSMA therapy were reviewed for this analysis. All patients with available baseline and interim [⁶⁸Ga]-PSMA-11 PET/CT were included in this analysis (n = 33). All PSMA avid metastases in baseline and interim PETs were semi-automatically segmented. The average PSMA expression (mean SUV_max of all metastases), total tumor volume (PSMA-TV) and TLQ (quotients of tumor volume and SUV_mean summed over all metastases) were quantified at baseline and interim timepoints. Response in PSMA-TV was assumed when a decline > 30% was present. OS and biochemical response were available for all patients.

Results: Baseline PSMA-TV was a statistically significant prognosticator of OS (HR = 1.618 95%CI: 1.117 - 2.343, p = 0.011). Reduction in PSMA-TV was not a statistically significant positive prognosticator of OS in the total cohort (HR = 0.829 95%CI: 0.559 - 1.230, p = 0.352). Likewise, there was no statistical difference in survival time comparing patients with PSMA-TV response to those without (13.2 vs. 15.6 months, p = 0.1). In the subgroup of patients with PSMA-TV response, mean SUV_max was a statistically significant prognosticator of OS (binarized by median; HR = 0.15; 95%CI: 0.03 - 0.83; p < 0.05). If patients with low PSMA expression at baseline were excluded from the analysis, reduction in PSMA-TV became a positive prognosticator of OS in uni- and multivariable Cox regression (HR = 0.290; 95%CI: 0.108 - 0.782; p = 0.015).

Conclusion: PSMA-TV reduction was a positive prognosticator of OS only if patients with low PSMA expression were excluded. This might indicate that the PSMA-PETs of patients with low PSMA expression may not be suited for assessing PSMA-TV reduction. Future studies investigating the interplay of PSMA-TV and low PSMA expression response are warranted.

Diagnostic efficiency of hybrid imaging using PSMA ligands, PET/CT, PET/MRI and MRI in identifying malignant prostate lesions

OBJECTIVE

The objective of this study was to assess the accuracy of 68Ga-PSMA-11 PET/MRI, 18F-PSMA-1007 PET/CT, 68Ga-PSMA-11 PET/CT, and multiparametric (mp)MRI for the delineating of dominant intraprostatic lesions (IPL).

MATERIALS AND METHODS

35 patients with organ-confined prostate cancer who were assigned to definitive radiotherapy (RT) were divided into three groups based on imaging techniques: 68Ga-PSMA-PET/MRI (n = 9), 18F-PSMA-PET/CT (n = 16) and 68Ga-PSMA-PET/CT (n = 10). All patients without PSMA-PET/MRI received an additional mpMRI. PSMA-PET-based automatic isocontours and manual contours of the dominant IPLs were generated for each modality. The biopsy results were then used to validate whether any of the prostate biopsies were positive in the marked lesion using Dice similarity coefficient (DSC), Youden index (YI), sensitivity and specificity. Factors that can predict the accuracy of IPLs contouring were analysed.

RESULTS

Diagnostic performance was significantly superior both for manual and automatic IPLs contouring using 68Ga-PSMA-PET/MRI (DSC/YI SUV70%-0.62/0.51), 18F-PSMA-PET/CT (DSC/YI SUV70%-0.67/0.53) or 68Ga-PSMA-PET/CT (DSC/YI SUV70%-0.63/0.51) compared to mpMRI (DSC/YI-0.47/0.41; p < 0.001). The accuracy for delineating IPLs was not improved by combination of PET/CT and mpMRI images compared to PET/CT alone. Significantly superior diagnostic accuracy was found for large prostate lesions (at least 15% from the prostate volume) and higher Gleason score (at least 7b) comparing to smaller lesions with lower GS.

CONCLUSION

IPL localization was significantly improved when using PSMA-imaging procedures compared to mpMRI. No significant difference for delineating IPLs was found between hybrid method PSMA-PET/MRI and PSMA-PET/CT. PSMA-based imaging technique should be considered for the diagnostics of IPLs and focal treatment modality.

Imaging and liquid biopsy in the prediction and evaluation of response to PRRT in neuroendocrine tumors: implications for patient management

Purpose

The aim of this narrative review is to give an overview on current and emerging imaging methods and liquid biopsy for prediction and evaluation of response to PRRT. Current limitations and new perspectives, including artificial intelligence, are discussed.

Methods

A literature review of PubMed/Medline was performed with representative keywords. The search included articles published online through August 31, 2020. All searches were restricted to English language manuscripts.

Results

Peptide radio receptor therapy (PRRT) is a prospectively evaluated and approved therapy option in neuroendocrine tumors (NETs). Different ligands targeting the somatostatin receptor (SSTR) are used as theranostic pairs for imaging NET and for PRRT. Response assessment in prospective trials often relies on the morphological RECIST 1.1 criteria, based on lesion size in CT or MRI. The role of SSTR-PET and quantitative uptake parameters and volumetric data is still not defined. Monoanalyte tumor marker chromogranin A has a limited value for response assessment after PRRT. New emerging liquid biopsy techniques are offering prediction of response to PRRT and prognostic value.

Conclusions

New response criteria for NET patients undergoing PRRT will comprise multiparametric hybrid imaging and blood-based multianalyte markers. This represents tumor biology and heterogeneity.

TSPO imaging-guided characterization of the immunosuppressive myeloid tumor microenvironment in patients with malignant glioma

BACKGROUND

Tumor-associated microglia and macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) are potent immunosuppressors in the glioma tumor microenvironment (TME). Their infiltration is associated with tumor grade, progression, and therapy resistance. Specific tools for image-guided analysis of spatiotemporal changes in the immunosuppressive myeloid tumor compartments are missing. We aimed (i) to evaluate the role of fluorodeoxyglucose (18F)DPA-714* (translocator protein [TSPO]) PET-MRI in the assessment of the immunosuppressive TME in glioma patients, and (ii) to cross-correlate imaging findings with in-depth immunophenotyping.

METHODS

To characterize the glioma TME, a mixed collective of 9 glioma patients underwent [18F]DPA-714-PET-MRI in addition to [18F]fluoro-ethyl-tyrosine (FET)-PET-MRI. Image-guided biopsy samples were immunophenotyped by multiparametric flow cytometry and immunohistochemistry. In vitro autoradiography was performed for image validation and assessment of tracer binding specificity.

RESULTS

We found a strong relationship (r = 0.84, P = 0.009) between the [18F]DPA-714 uptake and the number and activation level of glioma-associated myeloid cells (GAMs). TSPO expression was mainly restricted to human leukocyte antigen D related-positive (HLA-DR+) activated GAMs, particularly to tumor-infiltrating HLA-DR+ MDSCs and TAMs. [18F]DPA-714-positive tissue volumes exceeded [18F]FET-positive volumes and showed a differential spatial distribution.

CONCLUSION

[18F]DPA-714-PET may be used to non-invasively image the glioma-associated immunosuppressive TME in vivo. This imaging paradigm may also help to characterize the heterogeneity of the glioma TME with respect to the degree of myeloid cell infiltration at various disease stages. [18F]DPA-714 may also facilitate the development of new image-guided therapies targeting the myeloid-derived TME.

PSMA PET total tumor volume predicts outcome of patients with advanced prostate cancer receiving [177Lu]Lu-PSMA-617 radioligand therapy in a bicentric analysis

INTRODUCTION

[177Lu]Lu-PSMA-617 (Lu-PSMA) radioligand therapy is an emerging treatment option for patients with end-stage prostate cancer. However, response to Lu-PSMA therapy is only achieved in approximately half of patients. It is clinically important to identify patients at risk of poor outcome. Therefore, the aim of this study was to evaluate pretherapeutic PSMA PET derived total tumor volume and related metrics as prognosticators of overall survival in patients receiving Lu-PSMA therapy.

METHODS

A total number of 110 patients form the Departments of Nuclear Medicine Münster and Essen were included in this retrospective analysis. Baseline PSMA PET-CT was available for all patients. Employing a previously published approach, all tumor lesions were semi-automatically delineated in PSMA PET-CT acquisitions. Total lesion number, total tumor volume (PSMA-TV), total lesion uptake (PSMA-TLU = PSMA-TV * SUVmean), and total lesion quotient (PSMA-TLQ = PSMA-TV / SUVmean) were quantified for each patient. Log2 transformation was used for regressions.

RESULTS

Lesion number, PSMA-TV, and PSMA-TLQ were prognosticators of overall survival (HR = 1.255, p = 0.009; HR = 1.299, p = 0.005; HR = 1.326, p = 0.002). In a stepwise backward Cox regression including lesion number, PSMA-TV, PSA, LDH, and PSMA-TLQ, only the latter two remained independent and statistically significant negative prognosticators of overall survival (HR = 1.632, p = 0.011; HR = 1.239, p = 0.024). PSMA-TLQ and LDH were significant negative prognosticators in multivariate Cox regression in contrast to PSA value.

CONCLUSION

PSMA-TV was a statistically significant negative prognosticator of overall survival in patients receiving Lu-PSMA therapy. PSMA-TLQ was an independent and superior prognosticator of overall survival compared with PSMA-TV.

Pain in survivors of Ewing sarcoma: Prevalence, associated factors and prediction of recurrence

BACKGROUND

While the prognosis of patients with Ewing sarcoma (EwS) is improving, little is known about the frequency of pain and its risk factors in survivors of EwS. This study aims to analyse the prevalence and risk factors of pain and its predictive value for recurrence.

PATIENTS AND METHODS

In patients with remission after treatment of EwS, frequency and characteristics of pain within the first 5 years of follow up were assessed retrospectively.

RESULTS

Of 80 patients, 37 (46%) presented with at least one episode of pain. Chronic pain (>3 months) was observed in 10 patients (13%). Experience of at least one episode of pain was associated with prior combined local treatment (surgery and radiation compared to surgery alone; odds ratio [OR] 5.83, 95% confidence interval [CI] 1.43-34.9, P = .007). A total of 59 episodes of pain were observed, including 47 acute and 12 chronic episodes. Lower limb pain accounted for 46% (27/59) of all episodes of pain, and was associated with primary tumour of the pelvis or lower extremity (OR 4.29, 95% CI 1.18-18.21, P = .025), which represented 64% (51/80) of all EwS. The positive predictive value of pain for recurrence was only 12%.

CONCLUSION

Pain is a common problem in survivors of EwS, which mostly affects the lower extremity, and should be regularly assessed. Interventions to reduce pain may be particularly important in patients with combined local treatment with surgery and radiation, who seem to be at considerably increased risk for pain. Patients presenting with pain should be examined for recurrence.

Do fasting or high caloric drinks affect the physiological uptake of fluorine-18 prostate-specific membrane antigen-1007 in liver and bowel?

Recently introduced fluorine-18 prostate-specific membrane antigen-1007 (¹⁸F-PSMA-1007) for imaging prostate cancer has an intense physiologic liver uptake and biliary excretion. The aim of the present study was to evaluate the effect of different dietary conditions on this physiological uptake. Forty consecutive prostate cancer patients were scanned with ¹⁸F-PSMA-1007 positron emission tomography/computed tomography at different dietary conditions. In addition to a blinded read scoring, tracer uptake intensities (standardized uptake values [SUVs]) were measured in the liver and small bowel. There was no significant difference in liver and small-bowel uptake between different patient groups. Wilcoxon signed-rank tests revealed no significant difference of the median mean SUV of the liver or maximum SUV of the horizontal part of the duodenum between different dietary conditions groups. A dietary preparation of patients by fasting or the attempt to clear liver activity by high caloric drinks does not have a significant effect on tracer uptake in the liver or in the small bowel.

Somatostatin Receptor-Targeted Radioligand Therapy in Head and Neck Paraganglioma

OBJECTIVE

Surgical resection is the therapy of choice in head and neck paraganglioma but is associated with considerable morbidity. For treatment of inoperable or progressive disease, less aggressive adjuvant options are warranted. This study assessed effectiveness and safety of peptide receptor radionuclide therapy (PRRT) with lutetium-177-DOTATATE for head and neck paraganglioma with emphasis on response assessment.

METHODS

A retrospective analysis of 7 patients with head and neck paraganglioma treated with PPRT between May 2014 and October 2016 was performed. Three patients had jugulotympanic paraganglioma, 3 patients had carotid body tumors, and 1 patient had a combination of both. Patients underwent PRRT after discussion in the local tumor board regarding progressive disease, inoperability, or lack of other adjuvant options. All patients underwent 3-5 cycles of PRRT. Treatment response was evaluated by gallium-68-DOTATATE positron emission tomography/computed tomography and contrast-enhanced computed tomography or magnetic resonance imaging. Outcome measures were two-dimensional tumor diameters and total tumor volumes.

RESULTS

Median patient age was 60 years (interquartile range: 14-84 years). All patients had stable disease at posttherapy assessment. Decreasing tumor volumes were found in 4 patients. Clinical symptoms improved in 2 patients. No progression or adverse events occurred during a median follow-up of 39 months (interquartile range: 35-47 months).

CONCLUSIONS

Somatostatin receptor-targeted therapy using lutetium-177-DOTATATE shows promising effectiveness with a high safety profile. Patients in whom surgical morbidity outweighs oncologic benefit should be informed about PRRT as a treatment option.

Response assessment of somatostatin receptor targeted radioligand therapies for progressive intracranial meningioma

BACKGROUND

 In somatostatin receptor (SSTR) expressing progressive meningioma, peptide receptor radionuclide therapy (PRRT) has shown effect in small clinical series. However, standardized treatment and response assessment protocols are lacking. We present our experience on PPRT with ¹⁷⁷Lu-DOTATATE in progressive meningioma with a special emphasis on state-of-the-art response assessment.

METHODS

 Retrospective analysis on PRRT with ¹⁷⁷Lu-DOTATATE from 2015 to 2019. Pre- and post-therapy imaging was performed using MRI and ⁶⁸Ga-DOTATATE-PET for standard bidimensional and volumetric analyses, respectively, following novel RANO guidelines.

RESULTS

 Seven patients with progressive intracranial meningioma (median age 73 years, interquartile range 60-76; 5 WHO II, 2 WHO I; 5 multifocal) received a median of 4 cycles 2 3 4 of PRRT with ¹⁷⁷Lu-DOTATATE in eight-week intervals. Three patients did not undergo post-therapy ⁶⁸Ga-DOTATATE-PET due to early symptomatic progression and subsequent cessation of PRRT. After completion of 4 PRRT cycles volumetric PET imaging showed stable disease in two of four patients. According to bidimensional MRI response assessment, only one patient was stable. Progression free survival at six months was 42.9 %.

CONCLUSION

 In this heterogeneous collective of seven patients with progressive meningioma, 177Lu-DOTATATE therapies showed heterogeneous effectiveness. PET-based volumetric assessment should be used for response assessment in PRRT additionally to bidimensional imaging.

Analysis of PSMA expression and outcome in patients with advanced Prostate Cancer receiving 177Lu-PSMA-617 Radioligand Therapy

Rationale: PSMA-PET-CT enables measuring molecular expression of prostate-specific membrane antigen (PSMA) in vivo, which is the target molecule of ¹⁷⁷Lu-PSMA-617 (Lu-PSMA) therapy. However, the correlation of PSMA expression and overall survival (OS) in patients treated with Lu-PSMA therapy is currently unclear; especially with regard to coexistence of high and low PSMA expressing metastases. To this end, this retrospective single arm study elucidates the correlation of PSMA expression and overall survival in patients treated with Lu-PSMA therapy. Additionally, PET based criteria to define low PSMA expression were explored. Methods: Eighty-five patients referred to Lu-PSMA therapy were included in the analysis. Pretherapeutic ⁶⁸Ga-PSMA-PET-CT scans were available for all patients. SUV_max of the highest PSMA expressing metastasis (PSMA_max), SUV_max of the lowest PSMA expressing metastasis (PSMA_min), and average SUV_max of all metastases (PSMA_average) amongst other PET parameters were measured for each patient. A log-rank cutoff-finder was used to determine low (lowPSMA_average) and high (highPSMA_average) average PSMA expression as well as low (lowPSMA_min) and high (highPSMA_min) minimal PSMA expression. Results: PSMA_average was a significant prognosticator of overall survival in contrast to PSMA_max (HR: 0.959; p = 0.047 vs. HR: 0.992; p = 0.231). Optimal log rank cut-offs were: PSMA_average = 14.3; PSMA_min = 10.2. Patients with low average PSMA expression (lowPSMA_average) had significantly shorter survival compared to those with high average expression (highPSMA_average) (5.3 vs. 15.1 months; p < 0.001; HR: 3.738, 95%CI = 1.953-7.154; p < 0.001). Patients with low PSMA expressing metastases (lowPSMA_min) had shorter survival compared to those without a low PSMA expressing metastasis (highPSMA_min) (p = 0.003; 7.9 months vs. 21.3; HR: 4.303, 95%CI = 1.521-12.178; p = 0.006). Patients that were classified as highPSMA_average but with lowPSMA_min had an intermediate overall survival (11.4 months; longer compared to lowPSMA_average, 5.3 months, p = 0.002; but shorter compared to highPSMA_min, 21.3 months, p = 0.02). Conclusion: Low average PSMA expression is a negative prognosticator of overall survival. Absence of low PSMA expressing metastases is associated with best overall survival and the maximum PSMA expression seems not suited to prognosticate overall survival. Low PSMA expression might therefore be a negative prognosticator for the outcome of patients treated with Lu-PSMA therapy. Future studies are warranted to elucidate the degree of low PSMA expression tolerable for Lu-PSMA therapy.

Molecular analysis of circulating tumor cells of metastatic castration-resistant Prostate Cancer Patients receiving 177Lu-PSMA-617 Radioligand Therapy

Rationale: Lu-177-PSMA-617 radioligand therapy (RLT) is currently under approval for treatment of metastatic castration resistant prostate cancer (mCRPC) patients with late stage disease. However, previous studies demonstrated both heterogeneity of prostate specific membrane antigen (PSMA) expression, as well as response to PSMA treatment among mCRPC patients. Thus, there is an unmet need for identifying predictive parametres prior or under PSMA-RLT treatment. We therefore aimed to correlate several clinical and molecular parameters with response to PSMA treatment in a cohort of mCRPC patients undergoing PSMA RLT followed by a detailed analysis of promising candidates.

Methods: Nineteen patients, median age 68.8 years (range: 56.9 - 83.3) with mCRPC were included in this study. We performed baseline analysis of clinical parameters based on PSMA PET/CT, (metabolic tumor volume (MTV), total tumor volume (TTV)), serum PSA, ALP, LDH and gene expression analysis of circulating tumor cells (expression of AR full length (AR-FL), AR splice variant 7 (AR-V7), PSA and PSMA) as well as common markers for neuroendocrine differentiation (NED).

Results: Patients presented with bone, lymph node, and visceral metastases (89%, 68%, and 21%, respectively). All patients were pretreated with docetaxel, either abiraterone or enzalutamide, or both. Biochemical response in terms of PSA decline ≥50 or ≥30% was observed in 42% and 63%, respectively. There were significant correlations between PSA and PSMA mRNA expression, as well as tumor volumes (both MTV and TTV), AR-FL and AR-V7 mRNA expression. However, there was no correlation with response to PSMA treatment. Furthermore, none of these parameters was significantly correlated with baseline serum PSA values. Common NED markers were shown to be specifically high expressed and revealed impact on OS independent from AR-V7 gene expression.

Conclusion: We demonstrate that AR-FL and its splice variant AR-V7 might serve as prognostic biomarkers displaying high tumor burden in mCRPC patient prior to PSMA-RLT. Contrary, PSMA, which has been discussed as a biomarker for PSMA targeted treatment, does not display strong prognostic ability - at least on the mRNA level. Surprisingly, none of these parameters correlates to response to PSMA treatment. In contrast, commom NED markers such as SYP and ENO2 as well as FOXA1 expression level seem to predict OS, but not PFS, more reliably. We admit that a limitation of our study is the focus on mRNA expression of potential biomarkers only. Further investigations analyzing the potential role of protein expression of these markers are therefore warranted.

Interim PET Evaluation in Diffuse Large B-Cell Lymphoma Using Published Recommendations: Comparison of the Deauville 5-Point Scale and the ΔSUVmax Method

The value of interim ¹⁸F-FDG PET/CT (iPET)-guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the change-in-SUV_max (ΔSUV_max) approach-2 methods to assess early metabolic response to standard chemotherapy in DLBCL. Methods: Of 609 DLBCL patients participating in the PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas trial, iPET scans of 596 patients originally evaluated using the ΔSUV_max method were available for post hoc assessment of the Deauville score. A commonly used definition of an unfavorable iPET result according to the Deauville score is an uptake greater than that of the liver, whereas an unfavorable iPET scan with regard to the ΔSUV_max approach is characterized as a relative reduction of the SUV_max between baseline and iPET staging of less than or equal to 66%. We investigated the 2 methods' correlation and concordance by Spearman rank correlation coefficient and the agreement in classification, respectively. We further used Kaplan-Meier curves and Cox regression to assess differences in survival between patient subgroups defined by the prespecified cutoffs. Time-dependent receiver-operating-characteristic curve analysis provided information on the methods' respective discrimination performance. Results: Deauville score and ΔSUV_max approach differed in their iPET-based prognosis. The ΔSUV_max approach outperformed the Deauville score in terms of discrimination performance-most likely because of a high number of false-positive decisions by the Deauville score. Cutoff-independent discrimination performance remained low for both methods, but cutoff-related analyses showed promising results. Both favored the ΔSUV_max approach, for example, for the segregation by iPET response, where the event-free survival hazard ratio was 3.14 (95% confidence interval, 2.22-4.46) for ΔSUV_max and 1.70 (95% confidence interval, 1.29-2.24) for the Deauville score. Conclusion: When considering treatment intensification, the currently used Deauville score cutoff of an uptake above that of the liver seems to be inappropriate and associated with potential harm for DLBCL patients. The ΔSUV_max criterion of a relative reduction in SUV_max of less than or equal to 66% should be considered as an alternative.

5-Aminolevulinic Acid Fluorescence-Guided Resection of 18F-FET-PET Positive Tumor Beyond Gadolinium Enhancing Tumor Improves Survival in Glioblastoma

BACKGROUND

The value of early postoperative ¹⁸F-FET-PET in patients with glioblastoma (GBM) is unclear. Five-aminolevulinic acid (5-ALA) is used for fluorescence-guided resections in these patients and previous data suggest that fluorescence and ¹⁸F-FET-PET both demarcate larger tumor volumes than gadolinium enhanced magnet resonance imaging (MRI).

OBJECTIVE

To correlate fluorescence with enhancing volumes on postoperative MRI and ¹⁸F-FET-PET tumor volumes, and determine the value of postoperative ¹⁸F-FET-PET for predicting survival through observational study.

METHODS

GBM patients underwent fluorescence-guided resection after administration of 5-ALA followed by early postoperative MRI and ¹⁸F-FET-PET for determination of residual tissue volumes. All patients were treated with standard temozolomide radiochemotherapy and monitored for progression-free and overall survival (PFS, OS).

RESULTS

A total of 31 patients were included. For functional reasons, residual 5-ALA derived fluorescent tissue was left unresected in 18 patients with a median ¹⁸F-FET-PET volume of 17.82 cm³ (interquartile range 6.50-29.19). In patients without residual fluorescence, median ¹⁸F-FET-PET volume was 1.20 cm³ (interquartile range 0.87-5.50) and complete resection of gadolinium enhancing tumor was observed in 100% of patients. A ¹⁸F-FET-PET volume of above 4.3 cm³ was associated with worse OS (logrank P-value ≤ .05), also in patients with no residual contrast enhancing tumor on MRI. More patients in whom fluorescencing tissue had been removed completely had postoperative ¹⁸F-FET-PET tumor volumes below 4.3 cm³.

CONCLUSION

Postoperative ¹⁸F-FET-PET volumes predict OS and PFS. Resection of 5-ALA derived fluorescence beyond gadolinium enhancing tumor tissue leads to lower postoperative ¹⁸F-FET-PET tumor volumes and improved OS and PFS without additional deficits.

Baseline and interim PET-based outcome prediction in peripheral T-cell lymphoma: A subgroup analysis of the PETAL trial

The prospective randomized Positron Emission Tomography (PET)-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL) trial was designed to test the ability of interim PET (iPET) to direct therapy. As reported previously, outcome remained unaffected by iPET-based treatment changes. In this subgroup analysis, we studied the prognostic value of baseline total metabolic tumor volume (TMTV) and iPET response in 76 patients with T-cell lymphoma. TMTV was measured using the 41% maximum standardized uptake value (SUV_41max ) and SUV₄ thresholding methods. Interim PET was performed after two treatment cycles and evaluated using the ΔSUV_max approach and the Deauville scale. Because of significant differences in outcome, patients with anaplastic lymphoma kinase (ALK)-positive lymphoma were analyzed separately from patients with ALK-negative lymphoma. In the latter, TMTV was statistically significantly correlated with progression-free survival, with thresholds best dichotomizing the population, of 232 cm³ using SUV_41max and 460 cm³ using SUV₄ . For iPET response, the respective thresholds were 46.9% SUV_max reduction and Deauville score 1-4 vs 5. The proportion of poor prognosis patients was 46% and 29% for TMTV by SUV_41max and SUV₄ , and 29% and 25% for iPET response by ΔSUV_max and Deauville, respectively. At diagnosis, the hazard ratio (95% confidence interval) for poor prognosis vs good prognosis patients according to TMTV was 2.291 (1.135-4.624) for SUV_41max and 3.206 (1.524-6.743) for SUV₄ . At iPET, it was 3.910 (1.891-8.087) for ΔSUV_max and 4.371 (2.079-9.187) for Deauville. On multivariable analysis, only TMTV and iPET response independently predicted survival. Patients with high baseline TMTV and poor iPET response (22% of the population) invariably progressed or died within the first year (hazard ratio, 9.031 [3.651-22.336]). Due to small numbers and events, PET did not predict survival in ALK-positive lymphoma. Baseline TMTV and iPET response are promising tools to select patients with ALK-negative T-cell lymphoma for early allogeneic transplantation or innovative therapies.

Additional Local Therapy for Liver Metastases in Patients with Metastatic Castration-Resistant Prostate Cancer Receiving Systemic PSMA-Targeted Therapy

The aim of this study was to evaluate the efficacy of ¹⁷⁷Lu-prostate-specific membrane antigen (PSMA)-617 (¹⁷⁷Lu-PSMA) and selective internal radiation therapy (SIRT) for the treatment of liver metastases of castration-resistant prostate cancer. Methods: Safety and survival of patients with metastatic castration-resistant prostate cancer and liver metastases assigned to ¹⁷⁷Lu-PSMA alone (n = 31) or in combination with SIRT (n = 5) were retrospectively analyzed. Additionally, a subgroup (n = 10) was analyzed using morphologic and molecular response criteria. Results: Median estimated survival was 5.7 mo for ¹⁷⁷Lu-PSMA alone and 8.4 mo for combined sequential ¹⁷⁷Lu-PSMA and SIRT. ¹⁷⁷Lu-PSMA achieved discordant therapy responses with both regressive and progressive liver metastases in the same patient (best vs. worst responding metastases per patient: -35% vs. +63% diameter change; P < 0.05). SIRT was superior to ¹⁷⁷Lu-PSMA for the treatment of liver metastases (0% vs. 56% progression). Conclusion: The combination of ¹⁷⁷Lu-PSMA and SIRT is efficient and feasible for the treatment of advanced prostate cancer. ¹⁷⁷Lu-PSMA alone seems to have limited response rates in the treatment of liver metastases.

P14.67 Somatostatin receptor targeted radioligand therapyin head and neck paraganglioma

BACKGROUND

Surgical resection is the therapy of choice in head and neck paraganglioma. However, surgery is associated with significant morbidity depending on tumor size and localization. In case of progressive residual or recurrent disease, new and less aggressive therapeutic options are warranted. Somatostatin receptor (SSTR) targeted therapies pose a promising alternative, as SSTRs are upregulated in paragangliomas. Only few studies provide evidence on efficacy of 177Lu-DOTATATE therapy in these patients. The aim of this study was to evaluate the efficacy of peptide receptor radiotherapy (PPRT) with 177Lu-DOTATATE for head and neck paragangliomas.

METHODS

A total of seven consecutive patients (mean age: 60 years, range: 14–84) with progressive head and neck paragangliomas (3 carotid body tumors, 4 jugulotympanic paragangliomas), treated with PRRT using 177Lu-DOTATATE, were included in this retrospective analysis. Therapy response was assessed by interim and post-therapy 68Ga-DOTATATE-PET-CT and MRI according to morphological and SSTR imaging parameters. Therapeutic uptake was classified on177Lu-DOTATATE scintigraphies 48h p.i. according to the Krenning scale. Longer-term clinical and imaging-based outcome were evaluated.

RESULTS

Patients received a median of 4 cycles (range: 3 to 5) of PRRT with 177Lu-DOTATATE (mean injected dose 7.3 GBq). Interim and post-therapy staging showed at least stable disease in all patients. Tumor uptake in 48h p.i. 177Lu-scintigraphies was moderate to high in all patients (Krenning scale; median: 3; range: 2–4). Furthermore, none of the patients showed progressive disease during the median follow-up time of 28 months (range: 6–37 months).

CONCLUSION

SSTR targeted therapy using 177Lu-DOTATATE shows promising efficacy and may lead to long lasting stable disease.

Diagnostic Value of Diffusion Tensor Imaging and Positron Emission Tomography in Early Stages of Frontotemporal Dementia

BACKGROUND

Due to suboptimal sensitivity and specificity of structural and molecular neuroimaging tools, the diagnosis of behavioral variant frontotemporal dementia (bvFTD) remains challenging.

OBJECTIVE

Investigation of the sensitivity of diffusion tensor imaging (DTI) and fluorodeoxyglucose positron emission tomography (FDG-PET) to detect cerebral alterations in early stages of bvFTD despite inconspicuous conventional MRI.

METHODS

Thirty patients with early stages of bvFTD underwent a detailed neuropsychological examination, cerebral 3T MRI with DTI analysis, and FDG-PET. After 12 months of follow-up, all patients finally fulfilled the diagnosis of bvFTD. Individual FDG-PET data analyses showed that 20 patients exhibited a "typical" pattern for bvFTD with bifrontal and/or temporal hypometabolism (bvFTD/PET+), and that 10 patients showed a "non-typical"/normal pattern (bvFTD/PET-). DTI data were compared with 42 healthy controls in an individual and voxel-based group analysis. To examine the clinical relevance of the findings, associations between pathologically altered voxels of DTI or FDG-PET results and behavioral symptoms were estimated by linear regression analyses.

RESULTS

DTI voxel-based group analyses revealed microstructural degeneration in bifrontal and bitemporal areas in bvFTD/PET+ and bvFTD/PET- groups. However, when comparing the sensitivity of individual DTI data analysis with FDG-PET, DTI appeared to be less sensitive. Neuropsychological symptoms were considerably related to neurodegeneration within frontotemporal areas identified by DTI and FDG-PET.

CONCLUSION

DTI seems to be an interesting tool for detection of functionally relevant neurodegenerative alterations in early stages of bvFTD, even in bvFTD/PET- patients. However, at a single subject level, it seems to be less sensitive than FDG-PET. Thus, improvement of individual DTI analysis is necessary.

FDG-PET proves to be reliable in the diagnostic workup of a rare cardiac hemangioma

The noninvasive characterization of cardiac tumors is of clinical importance for surgical resection planning. Conventional radiological examinations like cardiac computed tomography (CT) or magnetic resonance imaging (MRI) may be misleading as benign cardiac lesions can present features suspicious for malignancy. Moreover, the low prevalence of cardiac tumors may additionally hamper a sound diagnosis. However, fluorodeoxyglucose-positron emission tomography (FDG-PET) has proven to be a reliable tool for cardiac tumor characterization. Here, FDG-PET/CT imaging of a 50-year-old man suffering from a cardiac tumor is presented. Despite CT and MRI signs of malignancy, FDG-PET characterized the tumor as benign. Histology confirmed the FDG-PET prediction and revealed a pericardial capillary hemangioma. Thereby, it seems important to integrate FDG-PET in the diagnostic workup of cardiac tumors.

Second line chemotherapy and visceral metastases are associated with poor survival in patients with mCRPC receiving 177Lu-PSMA-617

The purpose of this study was to identify previous treatments and biomarker profile features that prognosticate overall survival (OS) in patients with mCRPC receiving ¹⁷⁷Lu-PSMA-617.

Methods: 109 mCRPC patients treated with a median of 3 cycles of ¹⁷⁷Lu-PSMA-617 were included. Data were analyzed according to OS as well as PSA response patterns with regard to prior therapies, laboratory biomarkers and metastatic extent in univariate as well as multivariate Cox's proportional hazards models. PSA decline was assessed using the lowest PSA levels after the first cycle of therapy (initial PSA response) and during the entire observation period (best PSA response).

Results: In total, 54 patients (49.5%) died during the observation period. First and second line chemotherapy were performed in 85% and 26%, and Abiraterone and Enzalutamide were administered in 83% and 85%, respectively. Any initial PSA decline occurred in 55% while 25% showed a PSA decline of ≥50%. The median estimated OS was 9.9 months (95% CI: 7.2-12.5) for all patients. Any initial decline of PSA was associated with significantly prolonged OS (15.5 vs. 5.7 months, p = 0.002). Second line cabazitaxel chemotherapy (6.7 vs. 15.7 months, p = 0.002) and presence of visceral metastases (5.9 vs. 16.4 months, p<0.001) were associated with shorter OS. Only visceral metastases remained significant in a multivariate analysis.

Conclusion:¹⁷⁷Lu-PSMA-617 is an effective therapy for patients with mCRPC. However, the present data indicate that its beneficial effects on OS are strongly influenced by pretreatment (history of second line chemotherapy with cabazitaxel) and the presence of visceral metastases at onset of ¹⁷⁷Lu-PSMA-617 treatment.

Combined intracavitary thermotherapy with iron oxide nanoparticles and radiotherapy as local treatment modality in recurrent glioblastoma patients

Background

There is an increasing interest in local tumor ablative treatment modalities that induce immunogenic cell death and the generation of antitumor immune responses.

Methods

We report six recurrent glioblastoma patients who were treated with intracavitary thermotherapy after coating the resection cavity wall with superparamagnetic iron oxide nanoparticles (“NanoPaste” technique). Patients underwent six 1-h hyperthermia sessions in an alternating magnetic field and, if possible, received concurrent fractionated radiotherapy at a dose of 39.6 Gy.

Results

There were no major side effects during active treatment. However, after 2–5 months, patients developed increasing clinical symptoms. CT scans showed tumor flare reactions with prominent edema around nanoparticle deposits. Patients were treated with dexamethasone and, if necessary, underwent re-surgery to remove nanoparticles. Histopathology revealed sustained necrosis directly adjacent to aggregated nanoparticles without evidence for tumor activity. Immunohistochemistry showed upregulation of Caspase-3 and heat shock protein 70, prominent infiltration of macrophages with ingested nanoparticles and CD3⁺ T-cells. Flow cytometric analysis of freshly prepared tumor cell suspensions revealed increased intracellular ratios of IFN-γ to IL-4 in CD4⁺ and CD8⁺ memory T cells, and activation of tumor-associated myeloid cells and microglia with upregulation of HLA-DR and PD-L1. Two patients had long-lasting treatment responses > 23 months without receiving any further therapy.

Conclusion

Intracavitary thermotherapy combined with radiotherapy can induce a prominent inflammatory reaction around the resection cavity which might trigger potent antitumor immune responses possibly leading to long-term stabilization of recurrent GBM patients. These results warrant further investigations in a prospective phase-I trial.

Diagnostic performance of 18F-PSMA-1007 PET/CT in patients with biochemical recurrent prostate cancer

PURPOSE

The introduction of ligands targeting prostate-specific membrane antigen (PSMA), especially ⁶⁸Ga-PSMA-11, has changed the management of patients with prostate cancer (PCa). ¹⁸F-Labelled ligands can be produced in larger amounts and therefore can improve availability for a larger group of patients. The aim of this study was to evaluate the diagnostic performance of the recently introduced ¹⁸F-PSMA-1007 in patients with recurrent PCa.

METHODS

This retrospective analysis included 100 consecutive patients with biochemical relapse (mean age 68.75 ± 7.6 years) referred for PSMA PET/CT. Whole-body PET/CT imaging (from the lower limbs to the skull) was performed in all patients 120 min after injection of 338 ± 44.31 MBq ¹⁸F-PSMA-1007. Prostatectomy, radiation beam therapy of the prostate bed and androgen-deprivation therapy had been performed in 92%, 45% and 27% of the patients, respectively. Radiation beam therapy of the prostate bed had been performed in addition to surgery in 38 patients (38%) and 10 patients (10%) had received all three therapy modalities. The probability of a ¹⁸F-PSMA-1007 PET/CT scan suggestive of pathology was compared with the Gleason score (GS) and PSA level.

RESULTS

Of the 100 patients, 95 (95%) showed at least one pathological finding on ¹⁸F-PSMA-1007 PET/CT. The overall median PSA level was 1.34 ng/ml (range 0,04-41.3 ng/ml). The rates of pathological scans were 86%, 89%, 100% and 100% among patients with PSA levels ≤0.5, 0.51-1.0, 1.1-2.0 and > 2.0 ng/ml, respectively. The median GS was 7 (range 5-10). The majority of patients (70) with a GS available had a score in the range 7-9. The rate of pathological scans in these patients was 93% (65/70). The median SUV_max values of the pathological findings were 10.25, 14.32, 13.16 and 28.87 in patients with PSA levels ≤0.5, 0.51-1.0, 1.1-2.0 and >2.0 ng/ml, respectively. The median SUV_max in patients with a PSA level of >2.0 ng/ml was significantly higher than in all other PSA groups.

CONCLUSION

¹⁸F-PSMA-1007 PET/CT can detect recurrent PCa in a high percentage of patients with biochemical relapse. The probability of a pathological ¹⁸F-PSMA-1007 PET/CT scan seems to be high even in patients with a low PSA level ≤0.5 ng/ml, and this may have a significant impact on the management of this relevant group of patients.

Recurrence of Ewing sarcoma: Is detection by imaging follow-up protocol associated with survival advantage?

BACKGROUND

The Cooperative Ewing Sarcoma Study and the Late Effects Surveillance System of the Society for Paediatric Oncology and Haematology recommend a structured follow-up imaging protocol (FUIP) for patients with Ewing sarcoma (EwS) with decreasing frequency of imaging over the first 5 years. The present study aims to assess the effectiveness of the FUIP for EwS patients regarding survival after relapse.

PATIENTS AND METHODS

A retrospective multicenter analysis on 160 eligible patients with EwS recurrence was performed. Potential survival differences following recurrence diagnosis between patients with protocol-detected and symptomatic relapse were investigated using the Kaplan-Meier method. Additional subgroup analyses were performed on the relapse type. Overall survival (OS) was calculated from diagnosis of relapse to last follow-up or death.

RESULTS

In the multicenter analysis, recurrence was detected by FUIP in 77 of 160 patients (48%) and due to symptoms in 83 patients (52%). Regarding the entire study population, OS was significantly superior in patients with protocol-detected relapse compared to patients with symptomatic relapse (median, 2.4 vs. 1.2 years; P < 0.001). In the subgroup analyses, patients whose lung recurrences were detected by the FUIP experienced longer survival after recurrence than those whose recurrences were detected symptomatically (P = 0.023). In the 83 symptomatic patients, pain was the most prevalent symptom of relapse (72%).

CONCLUSION

FUIP may benefit survival in EwS relapse, especially in lung recurrence. Pain was the leading symptom of relapse.

Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL): A Multicenter, Randomized Phase III Trial

Purpose Interim positron emission tomography (PET) using the tracer, [¹⁸F]fluorodeoxyglucose, may predict outcomes in patients with aggressive non-Hodgkin lymphomas. We assessed whether PET can guide therapy in patients who are treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). Patients and Methods Newly diagnosed patients received two cycles of CHOP-plus rituximab (R-CHOP) in CD20-positive lymphomas-followed by a PET scan that was evaluated using the ΔSUV_max method. PET-positive patients were randomly assigned to receive six additional cycles of R-CHOP or six blocks of an intensive Burkitt's lymphoma protocol. PET-negative patients with CD20-positive lymphomas were randomly assigned or allocated to receive four additional cycles of R-CHOP or the same treatment with two additional doses rituximab. The primary end point was event-free survival time as assessed by log-rank test. Results Interim PET was positive in 108 (12.5%) and negative in 754 (87.5%) of 862 patients treated, with statistically significant differences in event-free survival and overall survival. Among PET-positive patients, 52 were randomly assigned to R-CHOP and 56 to the Burkitt protocol, with 2-year event-free survival rates of 42.0% (95% CI, 28.2% to 55.2%) and 31.6% (95% CI, 19.3% to 44.6%), respectively (hazard ratio, 1.501 [95% CI, 0.896 to 2.514]; P = .1229). The Burkitt protocol produced significantly more toxicity. Of 754 PET-negative patients, 255 underwent random assignment (129 to R-CHOP and 126 to R-CHOP with additional rituximab). Event-free survival rates were 76.4% (95% CI, 68.0% to 82.8%) and 73.5% (95% CI, 64.8% to 80.4%), respectively (hazard ratio, 1.048 [95% CI, 0.684 to 1.606]; P = .8305). Outcome prediction by PET was independent of the International Prognostic Index. Results in diffuse large B-cell lymphoma were similar to those in the total group. Conclusion Interim PET predicted survival in patients with aggressive lymphomas treated with R-CHOP. PET-based treatment intensification did not improve outcome.

Multimodal Imaging of Patients With Gliomas Confirms 11C-MET PET as a Complementary Marker to MRI for Noninvasive Tumor Grading and Intraindividual Follow-Up After Therapy

The value of combined L-( methyl-[¹¹C]) methionine positron-emitting tomography (MET-PET) and magnetic resonance imaging (MRI) with regard to tumor extent, entity prediction, and therapy effects in clinical routine in patients with suspicion of a brain tumor was investigated. In n = 65 patients with histologically verified brain lesions n = 70 MET-PET and MRI (T1-weighted gadolinium-enhanced [T1w-Gd] and fluid-attenuated inversion recovery or T2-weighted [FLAIR/T2w]) examinations were performed. The computer software "visualization and analysis framework volume rendering engine (Voreen)" was used for analysis of extent and intersection of tumor compartments. Binary logistic regression models were developed to differentiate between World Health Organization (WHO) tumor types/grades. Tumor sizes as defined by thresholding based on tumor-to-background ratios were significantly different as determined by MET-PET (21.6 ± 36.8 cm³), T1w-Gd-MRI (3.9 ± 7.8 cm³), and FLAIR/T2-MRI (64.8 ± 60.4 cm³; P < .001). The MET-PET visualized tumor activity where MRI parameters were negative: PET positive tumor volume without Gd enhancement was 19.8 ± 35.0 cm³ and without changes in FLAIR/T2 10.3 ± 25.7 cm³. FLAIR/T2-MRI visualized greatest tumor extent with differences to MET-PET being greater in posttherapy (64.6 ± 62.7 cm³) than in newly diagnosed patients (20.5 ± 52.6 cm³). The binary logistic regression model differentiated between WHO tumor types (fibrillary astrocytoma II n = 10 from other gliomas n = 16) with an accuracy of 80.8% in patients at primary diagnosis. Combined PET and MRI improve the evaluation of tumor activity, extent, type/grade prediction, and therapy-induced changes in patients with glioma and serve information highly relevant for diagnosis and management.

18F-PSMA-1007 PET/CT at 60 and 120 minutes in patients with prostate cancer: biodistribution, tumour detection and activity kinetics

PURPOSE

PSMA-targeted PET in patients with prostate cancer (PCa) has a significant impact on treatment decisions. By far the most frequently used PSMA ligand is ⁶⁸Ga-labelled PSMA-11. However, due to the availability of larger amounts of activity, ¹⁸F-labelled PSMA ligands are of major interest. The aim of the present study was to evaluate the biodistribution and performance of the novel ¹⁸F-labelled ligand PSMA-1007 at two different time points.

METHODS

This retrospective analysis included 40 consecutive patients (mean age 68.7 ± 8.1 years) referred for PSMA PET/CT. ¹⁸F-PSMA-1007 PET/CT was performed for localization of biochemical relapse, primary staging or therapy follow-up. Circular regions of interest were placed on representative slices of the liver, spleen, kidney, abdominal aortic blood pool, bone marrow (fourth lumbar vertebral body), urinary bladder and gluteus muscle at 60 and 120 min after injection. In malignant lesions the maximum standardized uptake (SUV_max) was measured within volumes of interest at both time points. All SUVs at 60 min were compared with those at 120 min after injection.

RESULTS

The activity in the blood pool, urinary bladder and gluteus muscle was very low and decreased significantly over time (P < 0.001). Uptake in the liver, spleen and kidney showed a significant increase over time and uptake in the bone marrow remained stable. Overall, 135 PCa lesions were detected at 60 min and 136 lesions at 120 min after injection. The median SUV_max increased significantly (P < 0.001) from 10.98 to 15.51 between 60 and 120 min.

CONCLUSION

PCa lesions show a significant increase in ¹⁸F-PSMA-1007 uptake at 120 min compared with 60 min after injection. In addition, accumulation of the tracer in the urinary bladder was very low leading to improved contrast of adjacent PCa lesions. Increasing accumulation in the liver may limit the sensitivity of the tracer in detecting liver metastases.

Pathogenetische Differenzierung des Skelettsuperscans mittels Knochenmarkszintigraphie

Die Beobachtung eines 54jährigen Patienten mit Prostatakarzinom wird beschrieben, bei dem eine bei Diagnosestellung bereits vorliegende multifokale Skelettmetastasierung unter Androgendeprivation zunächst gebessert wurde. Nach drei Jahren klagte der Patient über zunehmende Knochenschmerzen insbesondere in den Kniegelenken. Es zeigte sich szintigraphisch eine Skelettdarstellung als »Superscan«, mit allerdings ungewöhnlicher Betonung des peripheren Skelettes der Arme und Beine. Die Knochenmarkszintigraphie zeigte eine disseminierte Skelettmetastasierung mit vollständiger Verdrängung des zentralen Knochenmarks und erheblicher Eröffnung peripherer Knochenmarksräume als Ursache für den skelettszintigraphischen Befund.

The role of L-3-1-123-iodine-α-methyl tyrosine-SPECT in cerebral gliomas

L-3-1-123-iodine-a-methyltyrosine (IMT) is a 1-123-labelled amino acid which has been used for single photon emission computed tomography (SPECT) of cerebral gliomas for more than a decade. IMT-SPECT is able to detect tumor infiltration independent of disruptions of the blood-brain barrier which is often difficult with computed tomography or magnetic resonance tomography. The method is useful to detect tumor recurrences and helps to distinguish gliomas from non-neoplastic brain masses. IMT-SPECT is thus a valuable tool in the diagnostic evaluation and in therapy planning of patients with cerebral gliomas.

Lesion concordance, image quality and artefacts in PET/CT

Aim: This study had three major objectives: 1.) to record the number of concordant (both in PET and CT) pathological lesions in different body regions/organs, 2.) to evaluate the image quality and 3.) to determine both, the quantity and the quality of artefacts in whole body FDG PET/CT scans. Patients, methods: Routine whole body scans of 353 patients referred to FDG-PET/ CT exams at 4 university hospitals were employed. All potentially malignant lesions in 13 different body regions/organs were classified as either concordant or suspicious in FDG-PET or CT only. In the latter case the diagnostic relevance of this disparity was judged. The image quality in PET and CT was rated as a whole and separately in 5 different body regions. Furthermore we investigated the frequency and site of artefacts caused by metal implants and oral or intravenous contrast media as well as the subjective co-registration quality (in 4 body regions) and the diagnostic impact of such artefacts or misalignment. In addition, the readers rated the diagnostic gain of adding the information from the other tomographic method. Results: In total 1941 lesions (5.5 per patient) were identified, 1094 (56%) out of which were concordant. 602 (71%) out of the 847 remaining lesions were detected only with CT, 245 (29%) were only PET-positive. As expected, CT particularly depicted the majority of lesions in the lungs and abdominal organs. However, the diagnostic relevance was greater with PET-only positive lesions. Most of the PET/CT scans were performed with full diagnostic CT including administration of oral and intravenous contrast media (> 80%). The image quality in PET and CT was rated excellent. Artefacts occurred in more than 60% of the scans and were mainly due to (dental) metal implants and contrast agent. Nevertheless there was almost no impact on diagnostic confidence if reading of the non attenuation corrected PET was included. The co-registration quality in general was also rated as excellent. Misalignment mostly occurred due to patient motion and breathing and led to diagnostic challenges in about 4% of all exams. The diagnostic gain of adding PET to a CT investigation was rated higher than vice versa. Conclusions: As the image quality in both PET and CT was more than satisfying, CT-artefacts almost never led to diagnostic uncertainties and serious misalignment rarely occurred, PET/CT can be considered as suitable for routine use and may replace single PET- and CT-scans. However, additional reading of the non attenuation corrected PET is mandatory to assure best possible diagnostic confidence in PET. Since approximately half of all lesions found in PET/CT were not concordant, at least in a setting with a diagnostic CT the exams need to be reported by both a nuclear medicine physician and a radiologist in consensus.

Ewing sarcoma during follow-up

AIM

To evaluate the performance of a prospectively defined follow-up imaging protocol that includes FDG-PET(/CT) to detect tumour recurrence in Ewing sarcoma (EwS) before becoming symptomatic.

METHODS

Imaging results and clinical data during follow-up were retrospectively analysed from all patients treated successfully within the EURO E.W.I.N.G. 99 trial at the University Hospital Münster, Germany. All patients received follow-up imaging according to a comprehensive protocol that included regular X-ray, CT, MRI, bone scan and PET(/CT), albeit not all on the same day and with varying intervals for the different modalities.

RESULTS

80 of 105 patients underwent follow-up at our institution after complete remission. 30 patients had recurrent tumour during the follow-up period of 3.6 years on average. 19 recurrences (63%) were detected by scheduled imaging before the advent of clinical symptoms. The majority of these recurrences (8 out of 19; 42%) was detected first by PET/ CT (and confirmed with additional imaging thereafter), even though the total number of PET/CTs was comparatively low (138) and PET/CT was not systematically scheduled before other imaging techniques. Recurrences detected by bone scan were also detectable by PET.

CONCLUSIONS

The implemented follow-up protocol was effective in the detection of EwS recurrence before the advent of symptoms. Most cases of those detected before onset of symptoms were detected by PET/CT first. This hybrid imaging modality should therefore be considered in the routine follow-up of EwS patients, as is standard in our hospital. In combination with PET, low-dose chest CT seems to be sufficient in the detection of small pulmonary nodules.

Clinical value of amino acid imaging in paediatric brain tumours

Purpose: To evaluate single photon emission computed tomography (SPECT) using the amino acid l-3-[123I]-α-methyl tyrosine (IMT) and contrast enhanced magnetic resonance imaging (MRI) as diagnostic tools in primary paediatric brain tumours in respect of non-invasive tumour grading. Patients, materials, methods: 45 children with primary brain tumours were retrospectively evaluated. IMT uptake was quantified as tumour/nontumour- ratio, a 4-value-scale was used to measure gadolinium enhancement on contrast enhanced MRI. Statistical analyses were performed to evaluate IMT uptake and gadolinium enhancement in low (WHO I/II) and high (WHO III/ IV) grade tumours and to disclose a potential relationship of IMT uptake to disruption of blood brain barrier as measured in corresponding MRI scans. Results: IMT uptake above background level was observed in 35 of 45 patients. IMT uptake was slightly higher in high grade tumours but the difference failed to attain statistical significance. Grading of individual tumours was neither possible by IMT SPECT nor by gadolinium enhanced MRI. Conclusion: IMT is accumulated in most brain tumours in children. Tumour grading was not possible using IMT or contrast enhancement as determined by MRI. Neither morphological nor functional imaging can replace histology in paediatric brain tumours.

1-123-Iodo-α-methyl tyrosine SPECT in non-parenchymal brain tumours

Purpose: Scintigraphy using I-123-iodo-α-methyl tyrosine (IMT) is useful in the preoperative characterization of gliomas, in detecting recurrent glioma and in the biological re-evaluation of residual or recurrent tumours. A systematic evaluation of non-parenchymal brain tumours has not yet been performed. The aim of the present study was to evaluate IMT SPECT in the management of intracerebral metastases and lymphomas. Patients and methods: IMT uptake was analyzed in 31 patients with 28 metastases of extracerebral solid tumours and 7 cerebral lymphomas. Histology revealed high grade lymphomas, melanomas, and carcinomas of the following origin: lung, unknown primary, breast, colon, renal cell, ovary, vagina, frontal sinus. IMT uptake was quantified as ratio between maximal tumour accumulation and average uptake in the contralateral hemisphere. Results: All tumours except two renal cell and one small cell lung carcinoma metastases accumulated IMT (91%). The highest IMT uptake was found in a metastasis of lung carcinoma. IMT uptake was highly variable and was similar in primary and in recurrent tumours. Conclusion: Significant accumulation of IMT is seen in the majority of tumours, so that this technique might be helpful for the management of cerebral metastases and lymphomas.

Iodine excretion during stimulation with rhTSH in differentiated thyroid carcinoma

Aim: Elevated iodine intake is a serious problem in the diagnostic and therapeutic application of 131iodine in patients with differentiated thyroid cancer. Therefore, iodine avoidance is necessary 3 months in advance. Additionally, endogenous stimulation requires withdrawal of thyroid hormone substitution for 4 weeks. Exogenous stimulation using recombinant human TSH (rhTSH) enables the continuous substitution of levothyroxine, which contains 65.4% of its molecular weight in iodine. Thus, a substantial source of iodine intake is maintained during exogenous stimulation. Although this amount of stable iodine is comparable to the iodine intake in regions of normal iodine supply, it may reduce the accumulation of radioiodine in thyroid carcinoma tissue. The aim of this study was to assess the iodine excretion depending on different ways of stimulation. Methods: Iodine excretion was measured in 146 patients in the long term follow up after differentiated thyroid carcinoma. Patients were separated into 2 groups, those on hormone withdrawal (G I) and rhTSH-stimulated patients on hormone substitution (G II). Results: Iodine excretion was significantly lower in hypothyroid patients (G I, median 50 μg/l, range: 25-600 μg/l) than in those under levothyroxine medication (G II, median 75 μg/l, 25-600 μg/l, p <0.027). TSH in G I (median 57.0 μU/ml, range: 14.4-183 μU/ml) was significantly lower (p <0.001) than in G II (117 μU/ml, 32.2-281 μU/ml). Conclusion: Iodine excretion was higher in patients under rhTSH-stimulation than after hormone withdrawal. This may indicate an increased iodine pool in rhTSH-stimulated patients (deiodination of levothyroxine), thus limiting the sensitivity of radioio-dine scanning to the level of endogenous stimulation despite significantly higher TSH levels during rhTSH-stimulation.

Malignant melanoma and 18F-FDG-PET: Should the whole body scan include the legs?

Aim: 18F-FDG-PET (FDG-PET) is established in staging and follow-up of malignant melanoma. The legs are affected in 10-40% at time of diagnosis even if the primary is at the arms and torso. Imaging including the legs may detect distant manifestations but increases duration of the scan by ~30 min. We intended to disclose the diagnostic benefit of scanning the legs and to evaluate the therapeutic benefit resulting. Patients, Methods: In this retrospective analyse 213 consecutive PET studies of 153 patients with suspected or recent malignant melanoma were re-evaluated for metastastic spread by a blinded investigator. Histopathological follow-up was assessed for confirmation. Results: Suspicious findings at the legs were depicted in 53 patients on 76 occasions. 38/53 showed pathologic uptake in the torso as well. In 15/53 patients it was restricted to the legs. One of them had a hitherto unknown, clinically relevant finding that was not apparent in palpation and inspection. In 6 other patients with primary location at the legs a validation of the positive PET findings was not possible up to now. Conclusion: Metastases and local recurrence of malignant melanoma at the legs were found in 41% of women and 27% of men. However, a long scan does not yield relevant additional data. We found isolated new manifestations at the legs in only 1/153 patients. We recommend performing a long scan only in patients with previous melanoma manifestations restricted to the legs. In all other cases a short scan of the torso and proximal thighs is sufficient. This allows a higher number of PET-scans without loss of diagnostic power and a shorter examination time.

Influence of PET/CT-introduction on PET scanning frequency and indications

Aim: To evaluate the influence of the introduction of combined PET/CT scanners into clinical routine. This investigation addresses the quantitative changes between PET/CT and stand alone PET. Methods: The study included all examinations performed on stand alone PET- or PET/CTscanners within 12 month prior to and after implementation of PET/CT. The final data analysis included five university hospitals and a total number of 15 497 exams. We distinguished exams on stand alone tomographs prior to and after installation of the combined device as well as PET/CT scans particularly with regard to disease entities. Various further parameters were investigated. Results: The overall number of PET scans (PET and PET/CT) rose by 146% while the number of scans performed on stand alone scanners declined by 22%. Only one site registered an increase in stand alone PET. The number of exams for staging in oncology increased by 196% while that of cardiac scans decreased by 35% and the number of scans in neurology rose by 47%. The use of scans for radiotherapy planning increased to 7% of all PET/CT studies. The increase of procedures for so-called classic PET oncology indications was moderate compared to the more common tumors. An even greater increase was observed in some rare entities. Conclusions: The introduction of PET/CT led to more than a doubling of overall PET procedures with a main focus on oncology. Some of the observed changes in scanning frequency may be caused by a rising availability of new radiotracers and advancements of competing imaging methods. Nevertheless the evident increase in the use of PET/CT for the most common tumour types demonstrates its expanding role in cancer staging. The combination of molecular and morphologic imaging has not only found its place but is still gaining greater importance with new developments in technology and radiochemistry.

Moyamoya syndrome: Impaired hemodynamics on ECD SPECT after EEG controlled hyperventilation

Background and purpose: Ischemic symptoms in children with Moyamoya syndrome are typically provoked by hyperventilation (HV) and are accompanied by the “re-build-up” phenomenon in EEG. The value of scintigraphic detection of HV-provoked perfusion deficits remains to be elucidated. Patients and methods: In seven children with Moyamoya syndrome regional cerebral blood flow was assessed by 99mTc-ethyl-cysteine-dimer (ECD) single photon emission computed tomography (SPECT) after HV and under baseline conditions to identify ischemia prone regions. Results: Regional marked hypoperfusion after HV was found in all patients. Predominant perfusion deficits were detected in the frontal lobes. Conclusion: ECD SPECT is a potential tool for the preoperative evaluation of cerebral hemodynamics and for monitoring angiosurgical therapies in Moyamoya disease.

Whole-body imaging of oncologic patients using 16-channel PET-CT

Aim: This study evaluated a MDCT protocol for contrast-enhanced 16-channel PET-CT with regard to scan range and duration of a whole-body 18F-FDG PET-CT examination, the occurrence of contrast-material induced artefacts and quantitative assessment of CT attenuation. Patients, methods: 205 patients (51.9 ± 12.4 years) with different malignant tumours underwent whole-body PET-CT; the study protocol had been approved by the institutional review board. Contrast-enhanced MDCT (16 ˟ 1.5 mm; 120 ml Iomeprol 3 ml/s, 50 ml saline chaser bolus, scan delay 70 s; oral contrast) was also used for attenuation correction. From MDCT data mean scan range and duration, occurrence of contrast media-induced artefacts, and mean CT densities of jugular (jv) and subclavian (scv), superior (vcs) and inferior (vci) caval, portal (pv), and bilateral external iliac veins, pulmonary (ap) and iliac arteries, descending thoracic and abdominal aorta, all cardiac chambers, as well as both liver lobes, spleen, adrenal glands and kidneys were determined. Results: Attenuation corrected PET images were free of contrast media-related image artefacts. Homogeneous contrast enhancement was found in the mediastinal veins (right/left jv 171 ± 34/171 ± 35, scv 127 ± 50/127 ± 40, vcs 153 ± 36 HU) and arteries (e.g. ap 145 ± 26/151 ± 26). Cardiac chambers, abdominal vessels (e.g. vci 138 ± 24, pv 159 ± 25 HU), and parenchymal organs revealed sufficient and homogenous contrast-enhancement in all cases. No beam-hardening artefacts occurred in the neighbourhood of the subclavian veins. Conclusion: The chosen whole-body 18F-FDG 16-slice PET-CT protocol allowed for craniocaudal CT scanning with high vessel and parenchymal contrast revealing no IV contrast-media induced artefacts in attenuation-corrected PET data sets.

Relevance of raised cerebrospinal fluid monocyte levels in patients with frontotemporal dementia

Frontotemporal dementia (FTD) is a heterogeneous neurodegenerative disorder. The contribution of the immune system to its pathogenesis remains incompletely understood. In this study, we performed comprehensive immune cell profiling in the cerebrospinal fluid (CSF) and peripheral blood of patients with FTD. Thirty-two patients with behavioral variant frontotemporal dementia and 25 patients with primary progressive aphasia were included and compared to 14 healthy elderly controls. All patients underwent neuropsychological examination, magnetic resonance imaging, voxel-based diffusion tensor imaging, and peripheral blood and CSF immune cell profiling by multiparameter flow cytometry. The percentage of CSF monocytes was significantly increased specifically in patients with primary progressive aphasia. The proportion of monocytes in the CSF of the total FTD patient group directly correlated with semantic language impairment and microstructural temporal lesions. Increased intrathecal numbers of monocytes suggest a specific response of the innate immune system in a subset of patients with FTD. The findings are of clinical relevance since monocyte levels in the CSF were correlated with typical neuropsychological deficits and microstructural patterns of temporal degeneration.

Imaging Workup of Suspected Classical Paraneoplastic Neurological Syndromes: A Systematic Review and Retrospective Analysis of 18F-FDG-PET-CT

RATIONALE AND OBJECTIVES

This study aimed to assess the clinical efficacy of positron emission tomography (PET) or combined PET-computed tomography (CT) with ¹⁸F-fluorodeoxyglucose (FDG) for whole-body cancer screening in patients with suspected paraneoplastic neurological syndromes (PNS). The following main research questions were addressed: What is the percentage of positive findings to be expected in whole-body FDG-PET-CT in adult patients with PNS? How many false positives can be expected as assessed by clinical and histopathological workup? Are there patients who present with a tumor despite initially negative findings?

MATERIALS AND METHODS

This is a systematic review of the literature and retrospective analysis of FDG-PET-CT and clinical follow-up data from 45 consecutive patients (age: 56.6 ± standard deviation 15.8 years, 14 female, 31 male). Suspicious lesions were identified and correlated with immediate workup and clinical follow-up.

RESULTS

Fourteen studies were included in the review. Eleven malignancies (24.4% of patients) were identified by FDG-PET-CT in this sample. This is a higher percentage of positive findings compared to most previous reports. There was one initially negative finding.

CONCLUSIONS

Whole-body FDG-PET-CT is suitable to identify additional malignancies in patients with suspected classical PNS referred to a tertiary medical center. The utility by means of true-positive findings is higher in classical PNS than suggested by studies in less select patient populations.

Gastrointestinal Stromal Tumor Showing Intense Tracer Uptake on PSMA PET/CT

A 70-year-old man with suspected prostate cancer was referred for Ga-PSMA-HBED-CC PET/CT (short PSMA PET/CT) for staging of tumor extent. Apart from vivid tracer uptake in the prostate gland and osseous metastasis, PSMA PET/CT revealed a large soft tissue mass with calcifications in the left upper abdomen showing intense tracer uptake. Histologic examination revealed the mass to be a gastrointestinal stromal tumor.

The Value of 5-Aminolevulinic Acid in Low-grade Gliomas and High-grade Gliomas Lacking Glioblastoma Imaging Features: An Analysis Based on Fluorescence, Magnetic Resonance Imaging, 18F-Fluoroethyl Tyrosine Positron Emission Tomography, and Tumor Molecular Factors

BACKGROUND:

Approximately 20% of grade II and most grade III gliomas fluoresce after 5-aminolevulinic acid (5-ALA) application. Conversely, approximately 30% of nonenhancing gliomas are actually high grade.

OBJECTIVE:

The aim of this study was to identify preoperative factors (ie, age, enhancement, 18F-fluoroethyl tyrosine positron emission tomography [¹⁸F-FET PET] uptake ratios) for predicting fluorescence in gliomas without typical glioblastomas imaging features and to determine whether fluorescence will allow prediction of tumor grade or molecular characteristics.

METHODS:

Patients harboring gliomas without typical glioblastoma imaging features were given 5-ALA. Fluorescence was recorded intraoperatively, and biopsy specimens collected from fluorescing tissue. World Health Organization (WHO) grade, Ki-67/MIB-1 index, IDH1 (R132H) mutation status, O⁶-methylguanine DNA methyltransferase (MGMT) promoter methylation status, and 1p/19q co-deletion status were assessed. Predictive factors for fluorescence were derived from preoperative magnetic resonance imaging and ¹⁸F-FET PET. Classification and regression tree analysis and receiver-operating-characteristic curves were generated for defining predictors.

RESULTS:

Of 166 tumors, 82 were diagnosed as WHO grade II, 76 as grade III, and 8 as glioblastomas grade IV. Contrast enhancement, tumor volume, and ¹⁸F-FET PET uptake ratio >1.85 predicted fluorescence. Fluorescence correlated with WHO grade (P < .001) and Ki-67/MIB-1 index (P < .001), but not with MGMT promoter methylation status, IDH1 mutation status, or 1p19q co-deletion status. The Ki-67/MIB-1 index in fluorescing grade III gliomas was higher than in nonfluorescing tumors, whereas in fluorescing and nonfluorescing grade II tumors, no differences were noted.

CONCLUSION:

Age, tumor volume, and ¹⁸F-FET PET uptake are factors predicting 5-ALA-induced fluorescence in gliomas without typical glioblastoma imaging features. Fluorescence was associated with an increased Ki-67/MIB-1 index and high-grade pathology. Whether fluorescence in grade II gliomas identifies a subtype with worse prognosis remains to be determined.

ABBREVIATIONS:

5-ALA, 5-aminolevulinic acid

CRT, classification and regression tree

¹⁸F-FET PET, 18F-fluoroethyl tyrosine positron emission tomography

FLAIR, fluid-attenuated inversion recovery

GBM, glioblastoma multiforme

O⁶-MGMT, methylguanine DNA methyltransferase

ROC, receiver-operating characteristic

SUV, standardized uptake value

WHO, World Health Organization

[Uncommon manifestation of prostate cancer : Sister Mary Joseph's nodule]

We report on the case of an 81-year-old man suffering from prostate cancer for several years. In recent months, PSA levels increased, and ⁶⁸Ga-PSMA-PET-CT (PSMA: prostate-specific membrane antigen) imaging demonstrated suspicious lesions in the paravesical area and an umbilical tumor mass. Local excision was performed. Histologically, the tumor mass was diagnosed as metastasis of the prostate cancer, which is also designated as Sister Mary Joseph's nodule. Umbilical metastases of primary prostate cancer are extremely rare; however, they are of clinical importance since they are commonly associated with tumor progress and with a particularly poor prognosis.

The diagnostic imaging of bone metastases

BACKGROUND

Skeletal metastases are the most common malignant tumor in bone. Certain types of cancer (e.g., of the prostate or breast) are particularly likely to give rise to skeletal metastases, with prevalences of up to 70%. The diagnosis of skeletal metastases has a major impact on the overall treatment strategy and is an important determinant of the course of illness and the quality of life. The goal of diagnostic imaging is to detect skeletal metastases early, whenever they are suspected on the basis of clinical or laboratory findings or in patients who are at high risk. Other important issues include assessment of the risk of fracture and the response to treatment.

METHODS

This review is based on selected pertinent articles published up to December 2013.

RESULTS

Projectional radiography (plain films) is still useful for the immediate investigation of symptomatic bone pain and for the assessment of stability. Skeletal scintigraphy, the classic screening test for patients with cancer who do not have bone pain (specificity 81%, sensitivity 86%), has now been supplemented-in some cases, replaced-by other techniques. CT, including lowdose CT, is used to detect changes in bone structure due to metastases of some types of primary tumor (specificity 95%, sensitivity 73%); whole-body MRI, to detect metastases in the bone marrow and extraosseous soft tissues, e.g., metastases compressing the spinal cord (specificity 95%, sensitivity 91%); PET-CT, to detect metabolically active tumors (specificity 97%, sensitivity 90%).

CONCLUSION

Different imaging modalities are often used in combination to detect bone metastases optimally. Owing to advances in modern tomographic imaging, the current trend is toward whole-body imaging in a single session. The choice of method is based on the clinical situation and the type of primary tumor. Further research should address the impact of these costly and laborintensive imaging methods on treatment strategies and on the course of illness.