Evaluating tumor response with FDG PET: updates on PERCIST, comparison with EORTC criteria and clues to future developments

Treatment of patients with carcinomas in advanced stages with 5-fluorouracil, folinic acid and pyridoxine in tandem

The effect of high-dose pyridoxine (PN) on activity of 5-fluorouracil (FUra) and folinic acid (FA)-containing regimens was studied in 50 patients including 14 with digestive tract, and 36 with breast carcinomas (BC) in advanced stages with poor prognostic characteristics. Patients with colorectal, and pancreas adenocarcinoma received oxaliplatin, irinotecan, FUra, FA (Folfirinox), and patients with squamous cell carcinoma of the esophagus had paclitaxel, carboplatin, FUra, FA (TCbF). Patients with BC received AVCF (doxorubicin, vinorelbine, cyclophosphamide, FUra, FA) followed by TCbF or TCbF only, and patients who overexpressed HER2 received TCbF plus trastuzumab and pertuzumab. PN (1000-3000 mg/day iv) preceded each administration of FUra and FA. 47 patients (94%) responded, including 16 (32%) with CR. Median tumor reduction was 93%. Median event-free survival (EFS) was 37.7 months. The 25 patients with tumor shrinkage ≥ 91% had EFS of 52% from 42 months onwards. Unexpected toxicity did not occur. PN enhances potency of chemotherapy regimens comprising FUra and FA.

Imaging of Pheochromocytomas and Paragangliomas

Pheochromocytomas/paragangliomas are unique in their highly variable molecular landscape driven by genetic alterations, either germline or somatic. These mutations translate into different clusters with distinct tumor locations, biochemical/metabolomic features, tumor cell characteristics (eg, receptors, transporters), and disease course. Such tumor heterogeneity calls for different imaging strategies in order to provide proper diagnosis and follow-up. This also warrants selection of the most appropriate and locally available imaging modalities tailored to an individual patient based on consideration of many relevant factors including age, (anticipated) tumor location(s), size, and multifocality, underlying genotype, biochemical phenotype, chance of metastases, as well as the patient's personal preference and treatment goals. Anatomical imaging using computed tomography and magnetic resonance imaging and functional imaging using positron emission tomography and single photon emission computed tomography are currently a cornerstone in the evaluation of patients with pheochromocytomas/paragangliomas. In modern nuclear medicine practice, a multitude of radionuclides with relevance to diagnostic work-up and treatment planning (theranostics) is available, including radiolabeled metaiodobenzylguanidine, fluorodeoxyglucose, fluorodihydroxyphenylalanine, and somatostatin analogues. This review amalgamates up-to-date imaging guidelines, expert opinions, and recent discoveries. Based on the rich toolbox for anatomical and functional imaging that is currently available, we aim to define a customized approach in patients with (suspected) pheochromocytomas/paragangliomas from a practical clinical perspective. We provide imaging algorithms for different starting points for initial diagnostic work-up and course of the disease, including adrenal incidentaloma, established biochemical diagnosis, postsurgical follow-up, tumor screening in pathogenic variant carriers, staging and restaging of metastatic disease, theranostics, and response monitoring.

Repeatability of 18F-FDG uptake in metastatic bone lesions of breast cancer patients and implications for accrual to clinical trials

BACKGROUND

Standard measures of response such as Response Evaluation Criteria in Solid Tumors are ineffective for bone lesions, often making breast cancer patients that have bone-dominant metastases ineligible for clinical trials with potentially helpful therapies. In this study we prospectively evaluated the test-retest uptake variability of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) in a cohort of breast cancer patients with bone-dominant metastases to determine response criteria. The thresholds for 95% specificity of change versus no-change were then applied to a second cohort of breast cancer patients with bone-dominant metastases.

METHODS

For this study, nine patients with 38 bone lesions were imaged with 18F-FDG in the same calibrated scanner twice within 14 days. Tumor uptake was quantified by the most commonly used PET parameter, the maximum tumor voxel normalized by dose and body weight (SUVmax) and also by the mean of a 1-cc maximal uptake volume normalized by dose and lean-body-mass (SULpeak). The asymmetric repeatability coefficients with confidence intervals for SUVmax and SULpeak were used to determine the limits of 18F-FDG uptake variability. A second cohort of 28 breast cancer patients with bone-dominant metastases that had 146 metastatic bone lesions was imaged with 18F-FDG before and after standard-of-care therapy for response assessment.

RESULTS

The mean relative difference of SUVmax and SULpeak in 38 bone tumors of the first cohort were 4.3% and 6.7%. The upper and lower asymmetric limits of the repeatability coefficient were 19.4% and - 16.3% for SUVmax, and 21.2% and - 17.5% for SULpeak. 18F-FDG repeatability coefficient confidence intervals resulted in the following patient stratification using SULpeak for the second patient cohort: 11-progressive disease, 5-stable disease, 7-partial response, and 1-complete response with three inevaluable patients. The asymmetric repeatability coefficients response criteria for SULpeak changed the status of 3 patients compared to the standard Positron Emission Tomography Response Criteria in Solid Tumors of ± 30% SULpeak.

CONCLUSION

In evaluating bone tumor response for breast cancer patients with bone-dominant metastases using 18F-FDG SUVmax, the repeatability coefficients from test-retest studies show that reductions of more than 17% and increases of more than 20% are unlikely to be due to measurement variability. Serial 18F-FDG imaging in clinical trials investigating bone lesions in these patients, such as the ECOG-ACRIN EA1183 trial, benefit from confidence limits that allow interpretation of response.

The value of 18F-FDG PET/CT in Langerhans cell histiocytosis

OBJECTIVE

To investigate the value of 18F-FDG PET/CT in diagnosis and disease evaluation of Langerhans cell histiocytosis (LCH).

METHODS

A retrospective analysis of 31 patients with LCH confirmed by histopathology was performed. A systematic analysis of the PET/CT imaging manifestations of LCH was performed, recording patients who were treated and receiving PET/CT for efficacy evaluation. In addition, clinical and laboratory data of LCH patients were collected, and the correlation between these data and PET/CT metabolic parameters was initially investigated.

RESULTS

Of the 31 patients, thirty had at least 1 PET/CT positive lesions (96.7%), and one had only skin damage without abnormalities on PET/CT. Of 31 patients, fifteen (48.4%) had single system (SS) disease (9 cases with a single site and 6 cases with multiple sites) and 16 (51.6%) had multisystem (MS) disease (6 low risk and 10 high risk cases). The incidence of LCH lesions in the bone, lymphatic system, pituitary gland, liver, soft tissue, thyroid gland, thymus, and lungs was 20 cases (64.5%), 12 cases (38.7%), 3 cases (9.7%), 2 cases (6.5%), 2 cases (6.5%), 1 case (3.2%), 1 case (3.2%), and 8 cases (25.8%), respectively. A total of 21 PET/CT follow-up scanning were performed in 13 patients receiving chemotherapy, with 13 (61.9%) partial metabolic remission (PMR), 6 (28.6%) progressive metabolic disease (PMD), and 2 (9.5%) stable metabolic disease (SMD), according to PET Response Evaluation Criteria in Solid Tumors (PRECIST) 1.0. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and Lactic Dehydrogenase (LDH) were positively correlated with TTLG (total TLG) (R2 = 0.3256, 0.2409, 0.4205, P < 0.05). The Re-examine SUVmax is positively correlated with re-examine LDH (R2 = 0.7285, P < 0.05).

CONCLUSIONS

18F-FDG PET/CT is an effective way to diagnose and evaluate LCH. PET metabolic parameters were associated with laboratory inflammatory markers, suggesting that 18F-FDG PET/CT may be helpful in evaluating disease activity of LCH.

Frontline and Relapsed Rhabdomyosarcoma (FAR-RMS) Clinical Trial: A Report from the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG)

The Frontline and Relapsed Rhabdomyosarcoma (FaR-RMS) clinical trial is an overarching, multinational study for children and adults with rhabdomyosarcoma (RMS). The trial, developed by the European Soft Tissue Sarcoma Study Group (EpSSG), incorporates multiple different research questions within a multistage design with a focus on (i) novel regimens for poor prognostic subgroups, (ii) optimal duration of maintenance chemotherapy, and (iii) optimal use of radiotherapy for local control and widespread metastatic disease. Additional sub-studies focusing on biological risk stratification, use of imaging modalities, including [18F]FDG PET-CT and diffusion-weighted MRI imaging (DWI) as prognostic markers, and impact of therapy on quality of life are described. This paper forms part of a Special Issue on rhabdomyosarcoma and outlines the study background, rationale for randomisations and sub-studies, design, and plans for utilisation and dissemination of results.

Application of PET imaging delta radiomics for predicting progression-free survival in rare high-grade glioma

This study assesses the feasibility of using a sample-efficient model to investigate radiomics changes over time for predicting progression-free survival in rare diseases. Eighteen high-grade glioma patients underwent two L-3,4-dihydroxy-6-[18F]-fluoro-phenylalanine positron emission tomography (PET) dynamic scans: the first during treatment and the second at temozolomide chemotherapy discontinuation. Radiomics features from static/dynamic parametric images, alongside conventional features, were extracted. After excluding highly correlated features, 16 different models were trained by combining various feature selection methods and time-to-event survival algorithms. Performance was assessed using cross-validation. To evaluate model robustness, an additional dataset including 35 patients with a single PET scan at therapy discontinuation was used. Model performance was compared with a strategy extracting informative features from the set of 35 patients and applying them to the 18 patients with 2 PET scans. Delta-absolute radiomics achieved the highest performance when the pipeline was directly applied to the 18-patient subset (support vector machine (SVM) and recursive feature elimination (RFE): C-index = 0.783 [0.744-0.818]). This result remained consistent when transferring informative features from 35 patients (SVM + RFE: C-index = 0.751 [0.716-0.784], p = 0.06). In addition, it significantly outperformed delta-absolute conventional (C-index = 0.584 [0.548-0.620], p < 0.001) and single-time-point radiomics features (C-index = 0.546 [0.512-0.580], p < 0.001), highlighting the considerable potential of delta radiomics in rare cancer cohorts.

The Predictive Value of FDG PET/CT for Determining Progression-Free Survival in Advanced Stage III-IV BRAF -Mutated Melanoma Patients Treated With Targeted Therapy-What Can Be Learned From Progression?

PURPOSE

The aims of this study were to investigate whether (early) PERCIST response monitoring with 18 F-FDG PET/CT is predictive for progression-free survival (PFS) in unresectable stage III or IV melanoma patients treated with BRAF/MEK inhibitor (MEKi) and to define dissemination patterns at progression with a lesion-based evaluation in direct comparison to baseline to improve our understanding of 18 F-FDG PET/CT during BRAF/MEKi.

PATIENTS AND METHODS

This prospective multicenter single-arm study included 70 patients with unresectable stage III/IV BRAF -mutated melanoma who underwent contrast-enhanced CT and 18 F-FDG PET/CT at baseline and 2 and 7 weeks during treatment with vemurafenib plus cobimetinib and at progression if possible. Tumor response assessment was done with RECIST1.1 and PERCIST. Follow-up PET/CT scans were visually compared with baseline to assess dissemination patterns.

RESULTS

Using RECIST1.1, PFS was not significantly different between the response groups ( P = 0.26). At 2 weeks, PERCIST median PFS was 15.7 months for patients with complete metabolic response (CMR) versus 8.3 months for non-CMR ( P = 0.035). The hazards ratio (HR) for progression/death in non-CMR versus CMR was 1.99 (95% confidence interval [CI], 1.03-3.84; P = 0.040) and 1.77 (95% CI, 0.91-3.43; P = 0.0935) when adjusting for lactate dehydrogenase (LDH). At 7 weeks, median PFS for PERCIST CMR was 16.7 months versus 8.5 months for non-CMR ( P = 0.0003). The HR for progression/death in the non-CMR group was significantly increased (HR, 2.94; 95% CI, 1.60-5.40; P = 0.0005), even when adjusting for LDH (HR, 2.65; 95% CI, 1.43-4.91; P = 0.0020). At week 7, 18 F-FDG PET/CT was false-positive in all 4 (6%) patients with new FDG-avid lesions but CMR of known metastases. When 18 F-FDG PET/CT was performed at progressive disease, 18/22 (82%) patients had progression of known metastases with or without new 18 F-FDG-avid lesions.

CONCLUSIONS

This study shows that PERCIST response assessment at week 7 is predictive for PFS, regardless of LDH. At 2 weeks, patients with CMR have longer PFS than patients with non-CMR, but different PET parameters should be investigated to further evaluate the added value of early 18 F-FDG PET/CT. Disease progression on PET/CT is predominated by progression of known metastases, and new 18 F-FDG-avid lesions during BRAF/MEKi are not automatically a sign of recurrent disease.

CYFRA 21-1, CA 125 and CEA provide additional prognostic value in NSCLC patients with stable disease at first CT scan

BACKGROUND

Serum tumor markers (STM) may complement imaging and provide additional clinical information for patients with non-small cell lung cancer (NSCLC).

OBJECTIVE

To determine whether STMs can predict outcomes in patients with stable disease (SD) after initial treatment.

METHODS

This single-center, prospective, observational trial enrolled 395 patients with stage III/IV treatment-naïve NSCLC; of which 263 patients were included in this analysis. Computed Tomography (CT) scans were performed and STMs measured before and after initial treatment (two cycles of chemotherapy and/or an immune checkpoint inhibitor or tyrosine kinase inhibitor); analyses were based on CT and STM measurements obtained at first CT performed after cycle 2 only PFS and OS were analyzed by Kaplan-Meier curves and Cox-proportional hazard models.

RESULTS

When patients with SD (n = 100) were split into high- and low-risk groups based on CYFRA 21-1, CEA and CA 125 measurements using an optimized cut-off, a 4-fold increase risk of progression or death was estimated for high- vs low-risk SD patients (PFS, HR 4.17; OS, 3.99; both p < 0.0001). Outcomes were similar between patients with high-risk SD or progressive disease (n = 35) (OS, HR 1.17) and between patients with low-risk SD or partial response (n = 128) (PFS, HR 0.98; OS, 1.14).

CONCLUSIONS

STMs can provide further guidance in patients with indeterminate CT responses by separating them into high- and low-risk groups for future PFS and OS events.

Impact of retention index on the neoadjuvant chemotherapy effect and the prognosis in oesophageal cancer

OBJECTIVE

The relationship between retention index calculated from dual-time point 18F-fluorodeoxyglucose positron emission tomography-computed tomography and oesophageal cancer prognosis remains unknown. This study aimed to determine usefulness of retention index as a predictor of long-term prognosis of oesophageal cancer and neoadjuvant chemotherapy efficacy.

METHODS

A total of 151 patients with oesophageal cancer who underwent esophagectomy were evaluated retrospectively in this study. We acquired positron emission tomography scans 60 and 120 min (SUVmax1 and SUVmax2, respectively) after the intravenous administration of 3.7 Mbq/kg 18F-fluorodeoxyglucose. The patients were divided into two groups: high-retention index (retention index ≥29%, 107 patients) and low-retention index (retention index <29%, 44 patients). Retention index was calculated as follows: retention index (%) = [(SUVmax2 - SUVmax1)/SUVmax1] × 100.

RESULTS

The overall survival and relapse-free survival rates in the high-retention index group were significantly lower than those in the low-retention index group (P < 0.001). Our multivariate analysis identified that the high-retention index group contained independent risk factors for overall survival (hazard ratio: 2.44, P = 0.009) and relapse-free survival (hazard ratio: 2.61, P = 0.002). The high-retention index group exhibited a lower partial response rate to neoadjuvant chemotherapy evaluated by computed tomography (P < 0.001) and a lower pathological therapeutic effect in the resected specimen (P = 0.019) than the low-retention index group.

CONCLUSIONS

The retention index was associated with neoadjuvant chemotherapy responses and long-term prognosis for oesophageal cancer.

Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study

INTRODUCTION

Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3 months of MTX therapy correlate with response to treatment.

METHODS

We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12 months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12 months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship between changes in the SUVmax and MTXPG(n) concentrations.

RESULTS

We included 42 sarcoidosis patients treated with MTX (15 mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax.

CONCLUSION

These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

The Pattern of Metastatic Breast Cancer: A Prospective Head-to-Head Comparison of [18F]FDG-PET/CT and CE-CT

The study aimed to compare the metastatic pattern of breast cancer and the intermodality proportion of agreement between [18F]FDG-PET/CT and CE-CT. Women with metastatic breast cancer (MBC) were enrolled prospectively and underwent a combined [18F]FDG-PET/CT and CE-CT scan to diagnose MBC. Experienced nuclear medicine and radiology physicians evaluated the scans blinded to the opposite scan results. Descriptive statistics were applied, and the intermodality proportion of agreement was used to compare [18F]FDG-PET/CT and CE-CT. In total, 76 women with verified MBC were enrolled in the study. The reported number of site-specific metastases for [18F]FDG-PET/CT vs. CE-CT was 53 (69.7%) vs. 44 (57.9%) for bone lesions, 31 (40.8%) vs. 43 (56.6%) for lung lesions, and 16 (21.1%) vs. 23 (30.3%) for liver lesions, respectively. The proportion of agreement between imaging modalities was 76.3% (95% CI 65.2-85.3) for bone lesions; 82.9% (95% CI 72.5-90.6) for liver lesions; 57.9% (95% CI 46.0-69.1) for lung lesions; and 59.2% (95% CI 47.3-70.4) for lymph nodes. In conclusion, bone and distant lymph node metastases were reported more often by [18F]FDG-PET/CT than CE-CT, while liver and lung metastases were reported more often by CE-CT than [18F]FDG-PET/CT. Agreement between scans was highest for bone and liver lesions and lowest for lymph node metastases.

Image-Guided Precision Medicine in the Diagnosis and Treatment of Pheochromocytomas and Paragangliomas

In this comprehensive review, we aimed to discuss the current state-of-the-art medical imaging for pheochromocytomas and paragangliomas (PPGLs) diagnosis and treatment. Despite major medical improvements, PPGLs, as with other neuroendocrine tumors (NETs), leave clinicians facing several challenges; their inherent particularities and their diagnosis and treatment pose several challenges for clinicians due to their inherent complexity, and they require management by multidisciplinary teams. The conventional concepts of medical imaging are currently undergoing a paradigm shift, thanks to developments in radiomic and metabolic imaging. However, despite active research, clinical relevance of these new parameters remains unclear, and further multicentric studies are needed in order to validate and increase widespread use and integration in clinical routine. Use of AI in PPGLs may detect changes in tumor phenotype that precede classical medical imaging biomarkers, such as shape, texture, and size. Since PPGLs are rare, slow-growing, and heterogeneous, multicentric collaboration will be necessary to have enough data in order to develop new PPGL biomarkers. In this nonsystematic review, our aim is to present an exhaustive pedagogical tool based on real-world cases, dedicated to physicians dealing with PPGLs, augmented by perspectives of artificial intelligence and big data.

Advancements and Future Outlook of PET/CT-Guided Interventions

Advancements in minimally invasive technology, coupled with imaging breakthroughs, have empowered the field of interventional radiology to achieve unparalleled precision in image-guided diagnosis and treatment while simultaneously reducing periprocedural morbidity. Molecular imaging, which provides valuable physiological and metabolic information alongside anatomical localization, can expand the capabilities of image-guided interventions. Among various molecular imaging techniques, positron emission tomography (PET) stands out for its superior spatial resolution and ability to acquire quantitative data. PET has emerged as a crucial tool for oncologic imaging and plays a pivotal role in both staging and the assessment of treatment responses. Typically used in combination with computed tomography (CT) (PET/CT) and occasionally with magnetic resonance imaging MRI (PET/MRI), PET as a hybrid imaging approach offers enhanced insights into disease progression and response. In recent years, PET has also found its way into image-guided interventions, especially within the rapidly expanding field of interventional oncology. This review aims to explore the current and evolving role of metabolic imaging, specifically PET, in interventional oncology. By delving into the unique advantages and applications of PET in guiding oncological interventions and assessing response, we seek to highlight the increasing significance of this modality in the realm of interventional radiology.

PET/CT reading for relapse in non-small cell lung cancer after chemoradiotherapy in the PET-Plan trial cohort

BACKGROUND

Current studies indicate that fluorine-18-fluorodeoxyglucose positron emission tomography/ computed tomography ([¹⁸F]FDG PET/CT) is the most accurate imaging modality for the detection of relapsed locally advanced non-small cell lung cancer (NSCLC) after curatively intended chemoradiotherapy. To this day, there is no objective and reproducible definition for the diagnosis of disease recurrence in PET/CT, the reading of which is relevantly influenced by post radiation inflammatory processes. The aim of this study was to evaluate and compare visual and threshold-based semi-automated evaluation criteria for the assessment of suspected tumor recurrence in a well-defined study population investigated during the randomized clinical PET-Plan trial.

METHODS

This retrospective analysis comprises 114 PET/CT data sets of 82 patients from the PET-Plan multi-center study cohort who underwent [¹⁸F]FDG PET/CT imaging at different timepoints for relapse, as suspected by CT. Scans were first analyzed visually by four blinded readers using a binary scoring system for each possible localization and the associated reader certainty of the evaluation. Visual evaluations were conducted repeatedly without and with additional knowledge of the initial staging PET and radiotherapy delineation volumes. In a second step, uptake was measured quantitatively using maximum standardized uptake value (SUVmax), peak standardized uptake value corrected for lean body mass (SULpeak), and a liver threshold-based quantitative assessment model. Resulting sensitivity and specificity for relapse detection were compared to the findings in the visual assessment. The gold standard of recurrence was independently defined by prospective study routine including external reviewers using CT, PET, biopsies and clinical course of the disease.

RESULTS

Overall interobserver agreement (IOA) of the visual assessment was moderate with a high difference between secure (ĸ = 0.66) and insecure (ĸ = 0.24) evaluations. Additional knowledge of the initial staging PET and radiotherapy delineation volumes improved the sensitivity (0.85 vs 0.92) but did not show significant impact on the specificity (0.86 vs 0.89). PET parameters SUVmax and SULpeak showed lower accuracy compared to the visual assessment, whereas threshold-based reading showed similar sensitivity (0.86) and higher specificity (0.97).

CONCLUSION

Visual assessment especially if associated with high reader certainty shows very high interobserver agreement and high accuracy that can be further increased by baseline PET/CT information. The implementation of a patient individual liver threshold value definition, similar to the threshold definition in PERCIST, offers a more standardized method matching the accuracy of experienced readers albeit not providing further improvement of accuracy.

Response Monitoring in Metastatic Breast Cancer: A Prospective Study Comparing 18F-FDG PET/CT with Conventional CT

This study aimed to compare contrast-enhanced CT (CE-CT) and 18F-FDG PET/CT for response monitoring in metastatic breast cancer using the standardized response evaluation criteria RECIST 1.1 and PERCIST. The objective was to examine whether progressive disease was detected systematically earlier by one of the modalities. Methods: Women with biopsy-verified metastatic breast cancer were enrolled prospectively and monitored using combined CE-CT and 18F-FDG PET/CT every 9-12 wk to evaluate response to first-line treatment. CE-CT scans and RECIST 1.1 were used for clinical decision-making without accessing the 18F-FDG PET/CT scans. At study completion, 18F-FDG PET/CT scans were unmasked and assessed according to PERCIST. Visual assessment was used if response criteria could not be applied. The modality-specific time to progression was defined as the time from the baseline scan until the first scan demonstrating progression. Paired comparative analyses for CE-CT versus 18F-FDG PET/CT were applied, and the primary endpoint was earlier detection of progression by one modality. Secondary endpoints were time to detection of progression, response categorization, visualization of changes in response over time, and measurable disease according to RECIST and PERCIST. Results: In total, 87 women were evaluable, with a median of 6 (1-11) follow-up scans. Progression was detected first by 18F-FDG PET/CT in 43 (49.4%) of 87 patients and first by CE-CT in 1 (1.15%) of 87 patients (P < 0.0001). Excluding patients without progression (n = 32), progression was seen first on 18F-FDG PET/CT in 78.2% (43/55) of patients. The median time from detection of progression by 18F-FDG PET/CT to that of CE-CT was 6 mo (95% CI, 4.3-6.4 mo). At baseline, 76 (87.4%) of 87 patients had measurable disease according to PERCIST and 51 (58.6%) of 87 patients had measurable disease according to RECIST 1.1. Moreover, 18F-FDG PET/CT provided improved visualization of changes in response over time, as seen in the graphical abstract. Conclusion: Disease progression was detected earlier by 18F-FDG PET/CT than by CE-CT in most patients, with a potentially clinically relevant median 6-mo delay for CE-CT. More patients had measurable disease according to PERCIST than according to RECIST 1.1. The magnitude of the final benefit for patients is a perspective for future research.

Advances in PET and MRI imaging of tumor hypoxia

Tumor hypoxia is a complex and evolving phenomenon both in time and space. Molecular imaging allows to approach these variations, but the tracers used have their own limitations. PET imaging has the disadvantage of low resolution and must take into account molecular biodistribution, but has the advantage of high targeting accuracy. The relationship between the signal in MRI imaging and oxygen is complex but hopefully it would lead to the detection of truly oxygen-depleted tissue. Different ways of imaging hypoxia are discussed in this review, with nuclear medicine tracers such as [¹⁸F]-FMISO, [¹⁸F]-FAZA, or [⁶⁴Cu]-ATSM but also with MRI techniques such as perfusion imaging, diffusion MRI or oxygen-enhanced MRI. Hypoxia is a pejorative factor regarding aggressiveness, tumor dissemination and resistance to treatments. Therefore, having accurate tools is particularly important.

Breast PET/MRI Hybrid Imaging and Targeted Tracers

The recent introduction of hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) as a promising imaging modality for breast cancer assessment has prompted fervent research activity on its clinical applications. The current knowledge regarding the possible clinical applications of hybrid PET/MRI is constantly evolving, thanks to the development and clinical availability of hybrid scanners, the development of new PET tracers and the rise of artificial intelligence (AI) techniques. In this state-of-the-art review on the use of hybrid breast PET/MRI, the most promising advanced MRI techniques (diffusion-weighted imaging, dynamic contrast-enhanced MRI, magnetic resonance spectroscopy, and chemical exchange saturation transfer) are discussed. Current and experimental PET tracers (¹⁸ F-FDG, ¹⁸ F-NaF, choline, ¹⁸ F-FES, ¹⁸ F-FES, ⁸⁹ Zr-trastuzumab, choline derivatives, ¹⁸ F-FLT, and ⁶⁸ Ga-FAPI-46) are described in order to provide an overview on their molecular mechanisms of action and corresponding clinical applications. New perspectives represented by the use of radiomics and AI techniques are discussed. Furthermore, the current strengths and limitations of hybrid PET/MRI in the real world are highlighted. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Direct reconstruction for simultaneous dual-tracer PET imaging based on multi-task learning

BACKGROUND

Simultaneous dual-tracer positron emission tomography (PET) imaging can observe two molecular targets in a single scan, which is conducive to disease diagnosis and tracking. Since the signals emitted by different tracers are the same, it is crucial to separate each single tracer from the mixed signals. The current study proposed a novel deep learning-based method to reconstruct single-tracer activity distributions from the dual-tracer sinogram.

METHODS

We proposed the Multi-task CNN, a three-dimensional convolutional neural network (CNN) based on a framework of multi-task learning. One common encoder extracted features from the dual-tracer dynamic sinogram, followed by two distinct and parallel decoders which reconstructed the single-tracer dynamic images of two tracers separately. The model was evaluated by mean squared error (MSE), multiscale structural similarity (MS-SSIM) index and peak signal-to-noise ratio (PSNR) on simulated data and real animal data, and compared to the filtered back-projection method based on deep learning (FBP-CNN).

RESULTS

In the simulation experiments, the Multi-task CNN reconstructed single-tracer images with lower MSE, higher MS-SSIM and PSNR than FBP-CNN, and was more robust to the changes in individual difference, tracer combination and scanning protocol. In the experiment of rats with an orthotopic xenograft glioma model, the Multi-task CNN reconstructions also showed higher qualities than FBP-CNN reconstructions.

CONCLUSIONS

The proposed Multi-task CNN could effectively reconstruct the dynamic activity images of two single tracers from the dual-tracer dynamic sinogram, which was potential in the direct reconstruction for real simultaneous dual-tracer PET imaging data in future.

Criteria for the translation of radiomics into clinically useful tests

Computer-extracted tumour characteristics have been incorporated into medical imaging computer-aided diagnosis (CAD) algorithms for decades. With the advent of radiomics, an extension of CAD involving high-throughput computer-extracted quantitative characterization of healthy or pathological structures and processes as captured by medical imaging, interest in such computer-extracted measurements has increased substantially. However, despite the thousands of radiomic studies, the number of settings in which radiomics has been successfully translated into a clinically useful tool or has obtained FDA clearance is comparatively small. This relative dearth might be attributable to factors such as the varying imaging and radiomic feature extraction protocols used from study to study, the numerous potential pitfalls in the analysis of radiomic data, and the lack of studies showing that acting upon a radiomic-based tool leads to a favourable benefit-risk balance for the patient. Several guidelines on specific aspects of radiomic data acquisition and analysis are already available, although a similar roadmap for the overall process of translating radiomics into tools that can be used in clinical care is needed. Herein, we provide 16 criteria for the effective execution of this process in the hopes that they will guide the development of more clinically useful radiomic tests in the future.

SDHx mutations and temozolomide in malignant pheochromocytoma and paraganglioma

Malignant pheochromocytomas (PHEOs)/paragangliomas (PGLs) are rare tumors for which clinical outcomes remain poorly defined and therapeutic options are limited. Approximately 27% carry pathogenic germline succinate dehydrogenase (SDHx) mutations; the presence of such mutations has been correlated with response to temozolomide (TMZ). We aimed to investigate the association between germline mutations in SDHx and response to TMZ. We retrospectively identified patients with metastatic malignant PHEO/PGLs treated with TMZ- based chemotherapy at Dana-Farber Cancer Institute between 2003 and 2020. The correlation between response by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and PET Response Criteria in Solid Tumors (PERCIST) and the presence of SDHx mutations in the germline and tumor was evaluated. Nineteen patients received TMZ. Seventeen underwent germline assessment: 9 (53%) carried a pathogenic SDHx germline mutation. Fifteen patients were evaluable for response by RECIST 1.1: 6 (40%) partial response, 4 (27%) stable disease, and 5 (33%) progressive disease. Overall median progression-free survival was 2.2 years. Three-year overall survival (OS) was 58%. Median PFS was 1.3 years and 5.5 years for carriers and non-carriers, respectively and OS was 1.5 years and not estimable for carriers and non-carriers, respectively. The response by PERCIST criteria in nine patients correlated with the RECIST 1.1 assessment. Our series represents one of the largest analyses of patients with malignant PHEOs/PGLs treated with TMZ who have available germline data. The incidence of pathogenic germline SDHx mutations was similar to what has been previously published, though our analysis suggests that there may be a limited association between response to TMZ and pathogenic germline SDHx mutations.

A Scoring System for Predicting Neoadjuvant Chemotherapy Response in Primary High-Grade Bone Sarcomas: A Multicenter Study

Objective

Currently, there is a lack of good clinical tools for evaluating the effect of chemotherapy preoperatively on primary high‐grade bone sarcomas. Our goal was to investigate the predictive value of the clinical findings and establish a scoring system to predict chemotherapy response.

Methods

We conducted a retrospective multicenter cohort study and reviewed 322 patients with primary high‐grade bone sarcomas. Patients who routinely received neoadjuvant chemotherapy and underwent primary tumor resection with an assessment of tumor necrosis rate (TNR) were enrolled in this study. The medical records of patients were collected from November 1, 2011, to March 1, 2018, at Peking University People's Hospital (PKUPH) and Peking University Shougang Hospital (PKUSH). The mean age of the patients was 16.2 years (range 3–52 years), of whom 65.5% were male. The clinical data collected before and after neoadjuvant chemotherapy included the degree of pain, laboratory inspection, X‐ray, CT, contrast‐enhanced magnetic resonance (MR), and positron emission tomography‐computed tomography (PET‐CT). Several machine learning models, including logistic regression, decision trees, support vector machines, and neural networks, were used to classify the chemotherapy responses. Area under the curve (AUC) of the scoring system to predict chemotherapy response is the primary outcome measure.

Results

For patients without events, a minimum follow‐up of 24 months was achieved. The median follow‐up time was 43.3 months, and it ranged from 24 to 84 months. The 5 years progression‐free survival (PFS) of the included patients was 54.1%. The 5 years PFS rate was 39.7% for poor responders and 74.9% for good responders. Features such as longest diameter reduction ratio (up to three points), clear bone boundary formation (up to two points), tumor necrosis measured by magnetic resonance (up to two points), maximum standard uptake value (SUV_max) decrease (up to three points), and significant alkaline phosphatase decrease (up to 1 point) were identified as significant predictors of good histological response and constituted the scoring system. A score ≥4 predicts a good response to chemotherapy. The scoring system based on the above factors performed well, achieving an AUC of 0.893. For nonmeasurable lesions (classified by the revised Response Evaluation Criteria in Solid Tumors [RECIST 1.1]), the AUC was 0.901.

Conclusion

We first devised a well‐performing comprehensive scoring system to predict the response to neoadjuvant chemotherapy in primary high‐grade bone sarcomas.

Programmed cell death protein 1 axis blockade in locally advanced squamous cell carcinoma of the head and neck: Neoadjuvant and adjuvant approaches

Immunotherapy and in particular programmed cell death protein 1 (PD-1) inhibitors have been applied not only in the management of recurrent or metastatic disease but also as component of potentially curative treatment for many solid tumors. The incorporation of immunotherapy as neoadjuvant and /or adjuvant therapy in the treatment paradigm of locally advanced squamous cell carcinoma of the head and neck (SCCHN) is appealing with the goals of enhancing antitumor efficacy and, at the same time, reduce toxicity. This review analyzes the rationale for employing immunotherapy in the neoadjuvant and adjuvant settings, reviews the results of relevant clinical trials, and examines the potential benefits and caveats of neoadjuvant and/or adjuvant approaches in patients with SCCHN.

Gastrointestinal stromal tumors: a comprehensive radiological review

Gastrointestinal stromal tumors (GISTs) originating from the interstitial cells of Cajal in the muscularis propria are the most common mesenchymal tumor of the gastrointestinal tract. Multiple modalities, including computed tomography (CT), magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography, ultrasonography, digital subtraction angiography, and endoscopy, have been performed to evaluate GISTs. CT is most frequently used for diagnosis, staging, surveillance, and response monitoring during molecularly targeted therapy in clinical practice. The diagnosis of GISTs is sometimes challenging because of the diverse imaging findings, such as anatomical location (esophagus, stomach, duodenum, small bowel, colorectum, appendix, and peritoneum), growth pattern, and enhancement pattern as well as the presence of necrosis, calcification, ulceration, early venous return, and metastasis. Imaging findings of GISTs treated with antineoplastic agents are quite different from those of other neoplasms (e.g. adenocarcinomas) because only subtle changes in size are seen even in responsive lesions. Furthermore, the recurrence pattern of GISTs is different from that of other neoplasms. This review discusses the advantages and disadvantages of each imaging modality, describes imaging findings obtained before and after treatment, presents a few cases of complicated GISTs, and discusses recent investigations performed using CT and MRI to predict histological risk grade, gene mutations, and patient outcomes.

Integrating mechanism-based modeling with biomedical imaging to build practical digital twins for clinical oncology

Digital twins employ mathematical and computational models to virtually represent a physical object (e.g., planes and human organs), predict the behavior of the object, and enable decision-making to optimize the future behavior of the object. While digital twins have been widely used in engineering for decades, their applications to oncology are only just emerging. Due to advances in experimental techniques quantitatively characterizing cancer, as well as advances in the mathematical and computational sciences, the notion of building and applying digital twins to understand tumor dynamics and personalize the care of cancer patients has been increasingly appreciated. In this review, we present the opportunities and challenges of applying digital twins in clinical oncology, with a particular focus on integrating medical imaging with mechanism-based, tissue-scale mathematical modeling. Specifically, we first introduce the general digital twin framework and then illustrate existing applications of image-guided digital twins in healthcare. Next, we detail both the imaging and modeling techniques that provide practical opportunities to build patient-specific digital twins for oncology. We then describe the current challenges and limitations in developing image-guided, mechanism-based digital twins for oncology along with potential solutions. We conclude by outlining five fundamental questions that can serve as a roadmap when designing and building a practical digital twin for oncology and attempt to provide answers for a specific application to brain cancer. We hope that this contribution provides motivation for the imaging science, oncology, and computational communities to develop practical digital twin technologies to improve the care of patients battling cancer.

Pharmacologic modulation of 5-fluorouracil by folinic acid and pyridoxine for treatment of patients with advanced breast carcinoma

High concentration pyridoxal 5’-phosphate, the cofactor of vitamin B6, potentiates cytotoxicity in cancer cells exposed to 5-fluorouracil (FUra) and folinic acid (FA). We studied the effect of high-dose pyridoxine on antitumor activity of regimens comprising FUra and FA in 27 advanced breast carcinoma patients. Of 18 previously untreated patients, 12 had tumors that did not overexpress HER2 (Group I), and 6 that overexpressed HER2 (Group II). Nine patients (Group III) had prior chemotherapy. Group I received AVCF (doxorubicin, vinorelbine, cyclophosphamide, FUra, FA) or FAC (doxorubicin, cyclophosphamide, FUra, FA) followed by TCbF (paclitaxel carboplatin, FUra, FA). Groups II, and III received TCbF. Pyridoxine iv (1000–3000 mg/day) preceded each FA and FUra. Group II also received trastuzumab and pertuzumab. 26 patients responded. Three patients in Group I had CRs and 9 had PRs with 62–98% reduction rates; 4 patients in Group II had CRs and 2 had PRs with 98% reduction. Of 7 measurable patients in Group III, 2 attained CRs, and 5 had PRs with 81–94% reduction rates. Median time to response was 3.4 months. Unexpected toxicity did not occur. This pilot study suggests that high-dose vitamin B6 enhances antitumor potency of regimens comprising FUra and FA.

Aumento de Captação Cardíaca de 18F-FDG Induzida por Quimioterapia em Pacientes com Linfoma: Um Marcador Precoce de Cardiotoxicidade?

Fundamento

Ainda não está estabelecido se a captação de fluorodesoxiglicose no miocárdio ocorre exclusivamente por características fisiológicas ou se representa um desarranjo metabólico causado pela quimioterapia.

Objetivo

Investigar os efeitos da quimioterapia no coração dos pacientes com linfoma por tomografia por emissão de pósitrons associada a tomografia computadorizada (PET/CT) com 2-[18F]-fluoro-2-desoxi-D-glicose (¹⁸F-FDG PET/CT) antes, durante e/ou após a quimioterapia.

Métodos

Setenta pacientes com linfoma submetidos a ¹⁸F-FDG PET/CT foram retrospectivamente analisados. O nível de significância foi de 5%. A captação de ¹⁸F-FDG foi avaliada por três medidas: captação máxima no ventrículo esquerdo ( standardized uptake value , SUV max), razão SUV cardíaco / aorta e SUV cardíaco / SUV no fígado. Também foram comparados peso corporal, glicemia de jejum, tempo pós-injeção e dose administrada de ¹⁸F-FDG entre os exames.

Resultados

A idade média foi de 50,4 ± 20,1 anos e 50% dos pacientes eram mulheres. A análise foi realizada em dois grupos – PET/CT basal vs. intermediário e PET/CT basal vs pós-terapia. Não houve diferença significativa entre as variáveis clínicas e do protocolo dos exames entre os diferentes momentos avaliados. Nós observamos um aumento na SUV máxima no ventrículo esquerdo de 3,5±1,9 (basal) para 5,6±4,0 (intermediário), p=0,01, e de 4,0±2,2 (basal) para 6,1±4,2 (pós-terapia), p<0,001. Uma porcentagem de aumento ≥30% na SUV máxima no ventrículo esquerdo ocorreu em mais da metade da amostra. O aumento da SUV cardíaca foi acompanhado por um aumento na razão SUV máxima no ventrículo esquerdo / SUV máxima na aorta e SUV média no ventrículo esquerdo /SUV média no fígado.

Conclusão

O estudo mostrou um aumento evidente na captação cardíaca de ¹⁸F-FDG em pacientes com linfoma, durante e após quimioterapia. A literatura corrobora com esses achados e sugere que a ¹⁸F-FDG PET/CT pode ser um exame de imagem sensível e confiável para detectar sinais metabólicos precoces de cardiotoxicidade.

The role of Ga68 PSMA PET/CT imaging in Lu177 PSMA treatment planning in metastatic castration-resistant prostate cancer

OBJECTIVE

Lutetium-177 (Lu¹⁷⁷) prostate-specific membrane antigen (Lu¹⁷⁷ PSMA) is a novel targeted treatment for patients with metastatic castration-resistant prostate cancer (CRPC). The purpose of the study was to determine the molecular volumetric Gallium-68 (Ga⁶⁸) PSMA PET/CT parameters that can predict patients who will respond to treatment.

METHODS

These single-center retrospective data were obtained from metastatic CRPC patients receiving intravenous 6.0-8.5 GBq Lu¹⁷⁷ PSMA treatment every 6-8 weeks for a maximum of 3-8 cycles, with baseline Ga⁶⁸ PSMA PET/CT scan, clinical data, and information on treatment responses. All lesions were divided into two groups according to the increase and decrease in PSMA expression levels of 600 bone lesions and 85 lymph nodes that were compatible with metastasis of 23 patients after the treatment. The primary endpoint of our study was the evaluation of the relation between the baseline SUVmax, PSMA TV, TL PSMA values, and the treatment response of the two groups. The threshold values were determined for the parameters that had significant relations. In the present study, the prostate-specific antigen (PSA) response and treatment-induced toxicities were also evaluated as the secondary endpoint.

RESULTS

It was found that SUVmax, PSMA TV, and TL PSMA values in bone metastases showed significant differences between the groups with decreased and increased PSMA expression levels after the treatment. The AUC value for SUVmax was significant (AUC = 0.677; p < 0.001). The cutoff value was > 10.50 (sensitivity = 91.8%, Specificity = 41.5%) for SUVmax, > 1.50 cm³ (sensitivity = 49.1%, specificity = 70%) for PSMA TV and > 8.50 g (sensitivity = %60.9, specificity = %72.2) for TL PSMA. The median SUVmax value before the treatment in all metastatic lymph nodes was found to be 7.1 (5.4-12.4), and the median SUVmax after the treatment was 2.5 (1.6-12.1) (p < 0.001).

CONCLUSION

It was shown in the present study that Lu¹⁷⁷ PSMA treatment response may be higher in CRPC patients with metastatic bone lesion with high baseline PSMA expression level, and better treatment response may be achieved in patients with lymph node metastases than in bone metastases.

Molecular Response Assessment with Immune Adaptive PERCIST in Lung Cancer Patients Treated with Nivolumab: Is It Better Than iRECIST?

Aims  We compared the immune response evaluation criteria in solid tumors (iRECIST) with immune adaptive positron emission tomography response criteria in solid tumors (imPERCIST) in lung cancer patients treated with nivolumab.

Materials and Methods  Twenty lung cancer patients underwent fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan at baseline (PET-0), after four cycles (PET-1) and six to eight cycles (PET-2) of nivolumab were included. Kappa coefficient ( k ) was derived to see the level of agreement in two response criteria. Progression-free survival (PFS) curves were computed by the Kaplan–Meier method and compared with the Log Rank test. Univariate and multivariate regression for the percentage change in the sum of diameters (SoD), standard uptake value maximum (SUVmax), sum of metabolic tumor volume (SoMTV), and sum of total lesion glycolysis (SoTLG) was computed. A p -value less than 0.05 was considered significant.

Results  Kappa coefficient showed a substantial level of agreement (k 0.769) in two response criteria. Mean PFS in partial response, stable disease, and progressive disease (PD) patients in iRECIST and imPERCIST was 27.3, 17.7, 4.2, and 23.3, 18.8, 3.8 months, respectively. The Kaplan–Meier method with the log rank test showed a significant difference in PFS on intracomparison within both criteria; however, it was not significant on intercomparison. On univariate analysis, the percentage change in SoD, SoMTV, SoTLG was significant. However, on multivariate analysis, only percentage change in SoD was a significant predictor.

Conclusions  We concluded that imPERCIST was equally effective as currently recommended criteria iRECIST for response evaluation of nivolumab in lung cancer patients.

Cancer Imaging in Immunotherapy

Immune therapeutics are revolutionizing cancer treatments. In tandem, new and confounding imaging characteristics have appeared that are distinct from those typically seen with conventional cytotoxic therapies. In fact, only 10% of patients on immunotherapy may show tumor shrinkage, typical of positive responses on conventional therapy. Conversely, those on immune therapies may initially demonstrate a delayed response, transient enlargement followed by tumor shrinkage, stable size, or the appearance of new lesions. Response Evaluation Criteria in Solid Tumors (RECIST) or WHO criteria, developed to identify early effects of cytotoxic agents, may not provide a complete evaluation of new emerging treatment response pattern of immunotherapeutic agents. Therefore, new imaging response criteria, such as the immune-related Response Evaluation Criteria in Solid Tumors (irRECIST), immune Response Evaluation Criteria in Solid Tumors (iRECIST), and immune-related Response Criteria (irRC), are proposed. However, FDA approval of emerging therapies including immunotherapies still relies on the current RECIST criteria. In this chapter, we review the traditional and new imaging response criteria for evaluation of solid tumors and briefly touch on some of the more commonly associated immunotherapy-induced adverse events.

Mitochondrial transcription factor B1 promotes the progression of hepatocellular carcinoma via enhancing aerobic glycolysis

Mitochondrial dysfunctions play crucial roles in the carcinogenesis of various human cancers. However, the molecular mechanisms leading to mitochondrial dysfunction and thus cancer progression remains largely unclear. TFB1M (mitochondrial transcription factor B1) is a mitochondrial DNA-binding protein that activates the transcription of mitochondrial DNA. Our bioinformatics analysis indicated a significant up-regulation of TFB1M in hepatocellular carcinoma (HCC). Here, we investigated its clinical significance and biological functions in this malignancy. Here, we found that TFB1M was significantly upregulated in HCC cells probably due to decreased miR-130a-3p expression. High TFB1M expression was positively associated with poor patient survival in HCC. TFB1M contributes to HCC growth and metastasis by promoting cell cycle progression, epithelia-mesenchymal transition (EMT), and inhibiting cell apoptosis. Mechanistically, the metabolic switch from oxidative phosphorylation to glycolysis contributed to the promotion of tumor growth and metastasis by TFB1M overexpression in HCC cells. In summary, we demonstrate that TFB1M plays a crucial oncogenic role in HCC progression, indicating TFB1M as a promising prognostic marker and therapeutic target in HCC.

Heterogeneous radiological response to chemotherapy is associated with poor prognosis in advanced non-small-cell lung cancer

Background

A heterogeneous radiological response is frequently observed in cancer patients and could reflect tumor heterogeneity. We investigated the prognostic impact of heterogeneous radiological responses in patients with advanced non‐small‐cell lung cancer (NSCLC) who received platinum‐based chemotherapy.

Methods

The treatment response according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria was evaluated in 212 patients with advanced NSCLC who received platinum‐based chemotherapy. Patients with partial response (PR) or stable disease (SD) were classified into “PR homo,” “PR hetero,” “SD homo,” and “SD hetero” by the presence of a heterogeneous radiological response, and survival was compared between groups. We also compared survival based on the presence of metabolic responses in lesions with heterogeneous radiological responses.

Results

Fifty‐two patients (24.5%) were classified as PR, 112 patients (52.8%) as SD, and 48 patients (22.7%) as progressive disease (PD). There was no significant difference in progression‐free survival (PFS) and overall survival (OS) between the PR homo and PR hetero groups. The SD homo group had a longer PFS and OS than the SD hetero group. In the SD hetero group, patients with increased maximum standardized uptake value (SUVmax) in lesions with heterogeneous radiological responses had a shorter PFS than those with a stable SUVmax.

Conclusions

The presence of lesions with radiological heterogeneity was associated with disease progression and poor prognosis in the SD group. Patients with heterogeneous radiological responses require careful monitoring.

18F-FDG-PET/CT as an imaging biomarker for regorafenib efficacy in metastatic colorectal cancer (JACCRO CC-12)

Introduction

Regorafenib is a multikinase inhibitor approved for the treatment of metastatic colorectal cancer (mCRC). Despite providing a statistically significant survival benefit, a substantial number of patients fail to respond to or continue with treatment, which has resulted in an unmet clinical need for a biomarker of regorafenib efficacy.

Methods

The JACCRO CC-12 study was a prospective, multicenter, single-arm phase II trial designed to evaluate the usefulness of [¹⁸F]fluorodeoxyglucose positron emission tomography (FDG-PET) as an imaging biomarker of regorafenib in patients with mCRC that progressed after standard chemotherapies. FDG-PET and contrast-enhanced computed tomography (CT) were performed before and after treatment with regorafenib 160 mg once daily 3 weeks on/1 week off. The primary end point was the change in the maximum standardized uptake value in the lesion with the highest uptake at pre-treatment FDG-PET. The secondary end points included overall survival (OS), progression-free survival (PFS), the objective response rate (ORR), safety, and the correlation between FDG-PET and CT.

Results

Twenty patients were enrolled from November 2014 to March 2016, 17 of whom were evaluated for metabolic and morphological changes. Metabolic response with FDG-PET was partial response (PR) in one case (5.9%), stable disease (SD) in four (23.5%), and progressive disease (PD) in 12 (70.6%). The metabolic response rate was 5.9%. On CT imaging, no complete response or PR was observed, and the ORR was 0%. Median PFS and OS were 1.7 and 9.8 months, respectively. The median PFS of patients who achieved PR or SD by FDG-PET was 3.7 months, whereas that of those assessed as PD was 1 month (p = 0.13). The median OS of patients who achieved PR or SD by FDG-PET was 13.0 months, whereas that of patients assessed as PD was 10.6 months (p = 0.43). Frequent adverse events were palmar–plantar erythrodysesthesia syndrome, hypertension, loss of appetite, and fatigue.

Conclusions

In this study, FDG-PET failed to demonstrate usefulness as an early imaging biomarker of regorafenib in patients with mCRC.

FDG positron emission tomography imaging and ctDNA detection as an early dynamic biomarker of everolimus efficacy in advanced luminal breast cancer

Biomarkers to identify patients without benefit from adding everolimus to endocrine treatment in metastatic breast cancer (MBC) are needed. We report the results of the Pearl trial conducted in five Belgian centers assessing ¹⁸F-FDG-PET/CT non-response (n = 45) and ctDNA detection (n = 46) after 14 days of exemestane-everolimus (EXE-EVE) to identify MBC patients who will not benefit. The metabolic non-response rate was 66.6%. Median PFS in non-responding patients (using as cut-off 25% for SUVmax decrease) was 3.1 months compared to 6.0 months in those showing response (HR: 0.77, 95% CI: 0.40–1.50, p = 0.44). The difference was significant when using a “post-hoc” cut-off of 15% (PFS 2.2 months vs 6.4 months). ctDNA detection at D14 was associated with PFS: 2.1 months vs 5.0 months (HR-2.5, 95% CI: 1.3–5.0, p = 0.012). Detection of ctDNA and/or the absence of ¹⁸F-FDG-PET/CT response after 14 days of EXE-EVE identifies patients with a low probability of benefiting from treatment. Independent validation is needed.

68Ga-DOTATATE PET/CT and MRI with Diffusion-Weighted Imaging (DWI) in Short- and Long-Term Assessment of Tumor Response of Neuroendocrine Liver Metastases (NELM) Following Transarterial Radioembolization (TARE)

Simple Summary

TARE with ⁹⁰Yttrium has become a valuable treatment option for patients with unresectable NELMs. However, early evaluation of therapy response remains challenging as size-based response assessments (such as RECIST) are known to be limited, especially in slow-growing tumors. Alternatives such as quantitative evaluation of SUV of ⁶⁸Ga-DOTATATE PET/CT and ADC of DWI-MRI have not been compared so far. We found that early percentage changes in SUV tumor-to-organ ratios on first follow-up after TARE could predict longer HPFS in patients with NELM and were superior to ΔSUVmax/SUVmean alone or to ΔADC.

Abstract

The aim of this study was to evaluate the role of SUV and ADC in assessing early response in patients with NELM following TARE. Thirty-two patients with pre- and postinterventional MRI with DWI and ⁶⁸Ga-DOTATATE PET/CT were included. ADC and SUV of three target lesions and of tumor-free spleen and liver tissue were determined on baseline and first follow-up imaging, and tumor to spleen (T/S) and tumor to liver (T/L) ratios were calculated. Response was assessed by RECIST 1.1 and mRECIST on first follow-up, and long-term response was defined as hepatic progression-free survival (HPFS) over 6, 12, and <24 months. In responders, intralesional ADC values increased and SUV decreased significantly regardless of standard of reference for response assessment (mRECIST/RECIST/HPFS > 6/12/24 m). Using ROC analysis, ΔSUV T/S ratio (max/max) and ΔSUV T/L ratio (max/mean) were found to be the best and most robust metrics to correlate with longer HPFS and were superior to ΔADC. ΔT/S ratio (max/max) < 23% was identified as an optimal cut-off to discriminate patients with longer HPFS (30.2 m vs. 13.4 m; p = 0.0002). In conclusion, early percentage changes in SUV tumor-to-organ ratios on first follow-up seem to represent a prognostic marker for longer HPFS and may help in assessing therapeutic strategies.

Comparison of treatment response assessed by 18F-FDG PET/CT with the histopathological response using tumor regression grading on surgically resected specimen following neoadjuvant chemotherapy in squamous cell carcinoma of esophagus

BACKGROUND

For the response assessment after chemotherapy, gold standard is always the histopathological response. However, metabolic response can also guide further treatment. Herein, this study aimed to evaluate metabolic response assessment to neoadjuvant chemotherapy in squamous cell carcinoma esophagus using PET response criteria in solid tumors (PERCIST) criteria with taking histopathological response by tumor regression grading as the standard method.

METHODS

Total fifty-seven patients with squamous cell carcinoma esophagus were enrolled between April 2017 to December 2018 for this prospective study. All patients were undergone for baseline PET scan before going for neoadjuvant chemotherapy. Repeat PET scan was done after neoadjuvant chemotherapy. Operable patients were taken for surgery. Final histological response was assessed by Mandard grading. Three metabolic tools [maximum standardized uptake value (SUVmax), tumor regression grading, PERCIST] were compared.

RESULTS

The mean SULpeak of the primary lesion was 11.7 ± 5.5 (median, 10.2, range 5.5-31.8). The average percentage change (%Δ) in SUVmax was 42.9 ± 26.3. On histopathology, 5 (13.1%) patients showed complete pathological response, whereas grade II, III, IV and V in 8 (21.1%), 12 (31.6%), 10 (26.3%) and 3 (7.8%) respectively. On comparison of PERCIST with Mandard grading, agreement analysis showed that there was moderate agreement (k, 0.48). %ΔSUV peak change showed a strong correlation with %ΔSUVmax (P = 0.01) and percentage tumor to liver ratio change (P = 0.01). On comparison, these metabolic response tools showed a weak agreement (k, 0.28 with tumor to liver ratio, k, 0.38 with SUVmax).

CONCLUSION

After neoadjuvant chemotherapy, 18F-fluorodeoxyglucose PET/CT can help to assess the response and guide the treatment. However, a larger study is warranted to evaluate their correlation with pathological response.

18F-FDG PET/CT imaging biomarkers for early and late evaluation of response to first-line chemotherapy in patients with pancreatic ductal adenocarcinoma

Purpose: The purpose of this study was to evaluate ¹⁸F-FDG-PET/CT as an early and late interim imaging biomarker in patients with pancreatic ductal adenocarcinoma (PDAC) who undergo first-line systemic therapy. Methods: This was a prospective, single-center, single-arm, open-label study (IRB12-000770). Patient receiving first line chemotherapy were planned to undergo a baseline ¹⁸F-FDG-PET/CT (PET1), early interim ¹⁸F-FDG PET/CT (PET2) and late interim ¹⁸F-FDG-PET/CT (PET3). ROC selected and established (mPERCIST / RECIST1.1) cut-offs for metabolic and radiographic tumor response assessment were applied. Patients were followed to collect data on further treatments and overall survival (OS). Results: The study population consisted of 28 patients who underwent PET1. Twenty-three of these (82%) underwent PET2 and 21 (75%) PET3, respectively. Twenty-three deaths occurred during a median follow up period of 14 months (maximum follow up, 58.3 months). The median OS was 36.2 months (95%CI, 28-NYR) in early metabolic responders (6/23 (26%), P = 0.016) and 25.4 months (95%CI, 19.6-NYR) in early radiographic responders (7/23 (30%), P = 0.16). The median overall survival was 27.4 months (95%CI, 21.4-NYR) in late metabolic responders (10/21 (48%), P = 0.058) and 58.2 months (95%CI, 21.4-NYR) in late radiographic responders (7/21 (33%), P = 0.008). Conclusion: ¹⁸F-FDG PET may serve as early interim imaging biomarker (~ at 4 weeks) for evaluation of response to first-line chemotherapy in patients with PDAC. Radiographic changes might be sufficient for response evaluation after the completion of first line chemotherapy.

EANM guideline on the role of 2-[18F]FDG PET/CT in diagnosis, staging, prognostic value, therapy assessment and restaging of ovarian cancer, endorsed by the American College of Nuclear Medicine (ACNM), the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the International Atomic Energy Agency (IAEA)

In most patients with ovarian carcinoma, the diagnosis is reached when the disease is long past the initial stages, presenting already an advanced stage, and they usually have a very bad prognosis. Cytoreductive or debulking surgical procedures, platinum-based chemotherapy and targeted agents are key therapeutic elements. However, around 7 out of 10 patients present recurrent disease within 36 months from the initial diagnosis. The metastatic spread in ovarian cancer follows three pathways: contiguous dissemination across the peritoneum, dissemination through the lymphatic drainage and, although less importantly in this case, through the bloodstream. Radiological imaging, including ultrasound, CT and MRI, are the main imaging techniques in which management decisions are supported, CT being considered the best available technique for presurgical evaluation and staging purposes. Regarding 2-[¹⁸F]FDG PET/CT, the evidence available in the literature demonstrates efficacy in primary detection, disease staging and establishing the prognosis and especially for relapse detection. There is limited evidence when considering the evaluation of therapeutic response. This guideline summarizes the level of evidence and grade of recommendation for the clinical indications of 2-[¹⁸F]FDG PET/CT in each disease stage of ovarian carcinoma.

Image Registration of 18F-FDG PET/CT Using the MotionFree Algorithm and CT Protocols through Phantom Study and Clinical Evaluation

We evaluated the benefits of the MotionFree algorithm through phantom and patient studies. The various sizes of phantom and vacuum vials were linked to RPM moving with or without MotionFree application. A total of 600 patients were divided into six groups by breathing protocols and CT scanning time. Breathing protocols were applied as follows: (a) patients who underwent scanning without any breathing instructions; (b) patients who were instructed to hold their breath after expiration during CT scan; and (c) patients who were instructed to breathe naturally. The length of PET/CT misregistration was measured and we defined the misregistration when it exceeded 10 mm. In the phantom tests, the images produced by the MotionFree algorithm were observed to have excellent agreement with static images. There were significant differences in PET/CT misregistration according to CT scanning time and each breathing protocol. When applying the type (c) protocol, decreasing the CT scanning time significantly reduced the frequency and length of misregistrations (p < 0.05). The MotionFree application is able to correct respiratory motion artifacts and to accurately quantify lesions. The shorter time of CT scan can reduce the frequency, and the natural breathing protocol also decreases the lengths of misregistrations.

Efficacy and safety of peptide receptor radionuclide therapy in advanced radioiodine-refractory differentiated thyroid cancer and metastatic medullary thyroid cancer: a systematic review

Background

It has been shown that a subgroup of patients with differentiated thyroid cancer (DTC) and medullary thyroid carcinoma (MTC) would progress to advanced stages of thyroid cancer. Therefore, the present study was done to systematically review available evidence in order to investigate efficacy and safety of peptide receptor radionuclide therapy (PRRT) in the patients with advanced radioiodine refractory differentiated thyroid cancer (RR-DTC) and metastatic MTC.

Methods

For this purpose, relevant studies investigated safety and efficacy of PRRT in the patients with advanced RR-DTC and metastatic MTC were identified by searching Medline (Pubmed, Ovid, and Ebsco), Scopus, Embase, Web of Science, and Cochrane Library databases (from database inception to March 24, 2021). The review was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Searching was done independently by two investigators. Two researchers independently extracted the data and any disagreement was adjudicated by consensus. Quality of the studies was assessed using the tool of case reports/series in systematic reviews.

Results

Among 2284 related papers, 41 papers met the inclusion criteria. A total of 157 patients with RR-DTC were treated with PPRT. Biochemical and objective responses (partial and complete) were observed in 25.3 and 10.5% of patients, respectively. Among 220 patients with metastatic MTC, biochemical and objective responses were observed in 37.2 and 10.6% of the patients, respectively.

Forty-six deaths were reported in 95 patients with advanced RR-DTC. In addition, 63 deaths were observed in 144 patients with metastatic MTC. Major side effects were reported in 124 patients treated with ⁹⁰Y -based agent. In the patients treated with 177Lu-DOTA-TATE and 111In-Octreotide, mild and transient hematologic or renal complications were reported.

Conclusion

Findings of the study revealed that in the absence of the established treatment for the patients with RR-DTC and metastatic MTC, PRRT could be effective with few adverse events.

Trial registration

PROSPERO registration number: CRD42019125245.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08257-x.

Study protocol of the LARK (TROG 17.03) clinical trial: a phase II trial investigating the dosimetric impact of Liver Ablative Radiotherapy using Kilovoltage intrafraction monitoring

BACKGROUND

Stereotactic Ablative Body Radiotherapy (SABR) is a non-invasive treatment which allows delivery of an ablative radiation dose with high accuracy and precision. SABR is an established treatment for both primary and secondary liver malignancies, and technological advances have improved its efficacy and safety. Respiratory motion management to reduce tumour motion and image guidance to achieve targeting accuracy are crucial elements of liver SABR. This phase II multi-institutional TROG 17.03 study, Liver Ablative Radiotherapy using Kilovoltage intrafraction monitoring (LARK), aims to investigate and assess the dosimetric impact of the KIM real-time image guidance technology. KIM utilises standard linear accelerator equipment and therefore has the potential to be a widely available real-time image guidance technology for liver SABR.

METHODS

Forty-six patients with either hepatocellular carcinoma or oligometastatic disease to the liver suitable for and treated with SABR using Kilovoltage Intrafraction Monitoring (KIM) guidance will be included in the study. The dosimetric impact will be assessed by quantifying accumulated patient dose distribution with or without the KIM intervention. The patient treatment outcomes of local control, toxicity and quality of life will be measured.

DISCUSSION

Liver SABR is a highly effective treatment, but precise dose delivery is challenging due to organ motion. Currently, there is a lack of widely available options for performing real-time tumour localisation to assist with accurate delivery of liver SABR. This study will provide an assessment of the impact of KIM as a potential solution for real-time image guidance in liver SABR.

TRIAL REGISTRATION

This trial was registered on December 7th 2016 on ClinicalTrials.gov under the trial-ID NCT02984566 .

A multi-institutional analysis of fractionated versus single-fraction stereotactic body radiotherapy (SBRT) in the treatment of primary lung tumors: a comparison between two antipodal fractionations

OBJECTIVES

Stereotactic body radiotherapy (SBRT) is a consolidate treatment for inoperable early-stage lung tumors, usually delivered in single or multi-fraction regimens. We aimed to compare these two approaches in terms of local effectiveness, safety and survival.

MATERIALS AND METHODS

Patients affected by medically inoperable early-stage lung tumor were treated at two Institutions with two different schedules: 70 Gy in ten fractions (TF) (BED10: 119 Gy) or 30 Gy in single fraction (SF) (BED10: 120 Gy).

RESULTS

73 patients were treated with SBRT delivered with two biological equivalent schedules: SF (44) and TF (29). The median follow-up was 34 months (range 3-81 months). Three-year Overall survival (OS) was 57.9%, 3-year cancer-specific survival (CSS) was 77.2%, with no difference between treatment groups. Three-year progression-free survival (LPFS) was 88.9% and did not differs between SF and TF. Overall, four cases (5.4%) of acute grade ≥ 3 pneumonitis occurred. No differences in acute and late toxicity between the two groups were detected.

CONCLUSION

SF and TF seems to be equally safe and effective in the treatment of primary inoperable lung tumors especially for smaller lesion. The SF may be preferentially offered to reduce patient access to hospital with no negative impact on tumor control and survival.

Magnetic resonance imaging for assessing treatment response in bone marrow metastases

Cancer metastasis to bone is a frequent observation in malignancy that may result in complications such as pathological fractures and spinal cord compression. Monitoring treatment effects is the main concern in oncology; however, the evaluation of treatment response in bone is particularly challenging as it lacks well-established criteria. In addition, bone metastases have traditionally been considered non-measurable manifestations of cancer. Magnetic resonance imaging (MRI) is one of the most specific and sensitive methods for imaging skeletal metastases. The aim of this article is to highlight the diagnostic performance of MRI in the treatment monitoring of bone metastases, to review the current literature, and to provide an overview of recommendations for the evaluation of treatment response in bone.

Physical characteristics of 68Ga DOTATATE PET/CT affecting small lesion detectability

BACKGROUND AND PURPOSE

⁶⁸Ga DOTATATE PET/CT protocols are similar to ¹⁸F FDG protocols despite differences in physical properties, biodistribution, and tumor uptake. The purpose of this study is to evaluate the impact of scan time (counts), and target activity on signal-to-noise ratio (SNR) in various sized targets, or lesions. To evaluate this, phantom experiments and analysis of clinical ⁶⁸Ga DOTATATE PET/CT studies were performed.

MATERIALS AND METHODS

⁶⁸Ga was first compared to ¹⁸F in phantom studies to evaluate recovery coefficients and SNR. ⁶⁸Ga phantom studies were also acquired in list mode, and at varying target activities to evaluate the effects of acquisition time and high target concentrations on SNR in clinically relevant small (8 mm) and larger targets (≥ 12 mm). Clinical studies (n = 50) were analyzed to determine if phantom target concentrations and SNR are present in clinical ⁶⁸Ga DOTATATE studies at similarly very high tumor activity concentrations (n = 159).

RESULTS

In phantoms, recovery coefficient and SUV_max for ⁶⁸Ga were ~87% of ¹⁸F. SNR for ⁶⁸Ga was ~65% of ¹⁸F. For the ⁶⁸Ga small target (8 mm) at standard T/B = 2.4, increasing scan time from 5 to 15 minutes increased SNR from < 1 to 1.6, and did not result in target identification. Increasing T/B from 2.4 to 10.9, however, dramatically increased SNR from < 1 to 22.3. Increased T/B resulted in clear visibility of the 8 mm target, even for 1-minute scans. In patients, high hepatic tumor SUV_max (27.3±29.6), resulted in high SNR (12.5±9.8). For extrahepatic tumors, high SUV_max (41.6±42.8), resulted in high SNR (43.8±49.9).

CONCLUSION

Very high target or T/B, even in small targets, can offset the physical limitations of ⁶⁸Ga. High target uptake and high T/B are primary factors influencing small lesion detectability.

Quantitation of cancer treatment response by 2-[18F]FDG PET/CT: multi-center assessment of measurement variability using AUTO-PERCIST™

Background

The aim of this study was to assess the reader variability in quantitatively assessing pre- and post-treatment 2-deoxy-2-[¹⁸F]fluoro-d-glucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) scans in a defined set of images of cancer patients using the same semi-automated analytical software (Auto-PERCIST™), which identifies tumor peak standard uptake value corrected for lean body mass (SUL_peak) to determine [¹⁸F]FDG PET quantitative parameters.

Methods

Paired pre- and post-treatment [¹⁸F]FDG PET/CT images from 30 oncologic patients and Auto-PERCIST™ semi-automated software were distributed to 13 readers across US and international sites. One reader was aware of the relevant medical history of the patients (read_reference), whereas the 12 other readers were blinded to history but had access to the correlative images. Auto-PERCIST™ was set up to first automatically identify the liver and compute the threshold for tumor measurability (1.5 × liver mean) + (2 × liver standard deviation [SD]) and then detect all sites with SUL_peak greater than the threshold. Next, the readers selected sites they believed to represent tumor lesions. The main performance metric assessed was the percent change in the SUL_peak (%ΔSUL_peak) of the hottest tumor identified on the baseline and follow-up images.

Results

The intra-class correlation coefficient (ICC) for the %ΔSUL_peak of the hottest tumor was 0.87 (95%CI: [0.78, 0.92]) when all reads were included (n = 297). Including only the measurements that selected the same target tumor as the read_reference (n = 224), the ICC for %ΔSUL_peak was 1.00 (95%CI: [1.00, 1.00]). The Krippendorff alpha coefficient for response (complete or partial metabolic response, versus stable or progressive metabolic disease on PET Response Criteria in Solid Tumors 1.0) was 0.91 for all reads (n = 380) and 1.00 including for reads with the same target tumor selection (n = 270).

Conclusion

Quantitative tumor [¹⁸F]FDG SUL_peak changes measured across multiple global sites and readers utilizing Auto-PERCIST™ show very high correlation. Harmonization of methods to single software, Auto-PERCIST™, resulted in virtually identical extraction of quantitative tumor response data from [¹⁸F]FDG PET images when the readers select the same target tumor.