Evaluation of a semi-automated approach for FDG PET image analysis for routine clinical application in patients with multiple myeloma

BACKGROUND

FDG PET/CT is a tool for assessing response to therapy in various cancers, and may provide an earlier biomarker of clinical response. We developed a novel semi-automated approach for analyzing FDG PET/CT images in patients with multiple myeloma (MM) to standardize FDG PET application.

METHODS

Patients (n = 8) with relapsed/refractory MM from the Phase 2 study (NCT02899052) of venetoclax plus carfilzomib and dexamethasone underwent FDG PET/CT at baseline and up to two timepoints during treatment. Images were processed using an established automated segmentation algorithm, with the modification that a red marrow region in an unaffected lumbar vertebra was used to define background standardized uptake value normalized to lean body mass (SUL) threshold above which uptake was considered disease-specific uptake. This approach was compared to lesion segmentation, and to International Myeloma Working Group (IMWG) response criteria, including minimal residual disease (MRD).

RESULTS

The two FDG PET analysis techniques agreed on evaluation of patient-level SULpeak for 67% of scans. In the metabolic response assessment per PET Response Criteria in Solid Tumors (PERCIST), the two techniques agreed in 75% of patients. Differences between techniques occurred in low-uptake lesions due to greater reader sensitivity to lesions with uptake marginally above background. PERCIST outcomes were generally in agreement with IMWC and MRD.

CONCLUSIONS

This semi-automated analysis was in high agreement with standard approaches for detecting response to MM therapy. This proof-of-concept study suggests that larger studies should be conducted to confirm how FDG PET analysis may aid early response detection in MM.

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.

Criterios PERCIST, Hopkins y parámetros metabólicos de la PET/TC como factores pronósticos en el cáncer escamoso de cabeza y cuello

AIM

To assess the clinical utility of PERCIST and Hopkins criteria and changes in [¹⁸F]FDG PET/CT quantitative parameters as prognostic factors for progression-free survival (PFS) and cancer-specific survival (CSS) in patients with head and neck squamous cell carcinoma treated by chemoradiotherapy.

MATERIAL AND METHODS

Forty patients (34 men) diagnosed with head and neck squamous cell carcinoma were retrospectively assessed over an interval of 8 years. PERCIST and Hopkins criteria were used to assess response to treatment. Variations in the metabolic parameters maximum SUV (ΔSUVmax), metabolic tumor volume (ΔMTV) and total lesion glycolysis (ΔTLG) between pre- and post-treatment PET/CT studies were also determined. The Cox regression model, ROC curves and the Kaplan-Meier method were used for the analysis of prognostic factors and survival curves.

RESULTS

The mean follow-up was 39.4 months, with 24 progressions and 22 deaths. Both PERCIST and Hopkins criteria and the three metabolic parameters were predictive factors in the univariate analysis and only ΔSUVmax was in the multivariate analysis. Survival analysis showed statistically significant differences in PFS and CSS curves for the five parameters considered.

CONCLUSION

Application of PERCIST and Hopkins criteria as well as ΔSUVmax, ΔMTV and ΔTLG from PET/CT studies proved to be prognostic factors for survival in patients in our setting for treating head and neck cancer. The results may help to personalize treatment.

Radioembolization-Induced Changes in Hepatic [(18)F]FDG Metabolism in Non-Tumorous Liver Parenchyma

Background: [18F]FDG-PET/CT is increasingly used for response assessments after oncologic treatment. The known response criteria for [18F]FDG-PET/CT use healthy liver parenchyma as the reference standard. However, the [18F]FDG liver metabolism results may change as a result of the given therapy. The aim of this study was to assess changes in [18F]FDG liver metabolism after hepatic 90Y resin radioembolization. Methods: [18F]FDG-PET/CT scans prior to radioembolization and one and three months after radioembolization (consistent with the PERCIST comparability criteria), as well as 90Y-PET/CT scans, were analyzed using 3 cm VOIs. The FDG activity concentration and absorbed dose were measured. A linear mixed-effects logistic regression model and logistic mixed-effects model were used to assess the correlation between the FDG-activity concentration, absorbed dose, and biochemical changes. Results: The median SULVOI,liver at baseline was 1.8 (range = 1.2−2.8). The mean change in SULVOI,liver per month with an increase in time was 0.05 (95%CI 0.02−0.09) at p < 0.001. The median absorbed dose per VOI was 31.3 Gy (range = 0.1−82.3 Gy). The mean percent change in ΔSULVOI,liver for every Gy increase in the absorbed dose was −0.04 (95%CI −0.22−0.14) at p = 0.67. The SULblood and SULspleen results showed no increase. Conclusions: The [18F]FDG metabolism in the normal liver parenchyma is significantly but mildly increased after radioembolization, which can interfere with its use as a threshold for therapy response.

Differences and Similarities in the Pattern of Early Metabolic and Morphologic Response after Induction Chemo-Immunotherapy versus Induction Chemotherapy Alone in Locally Advanced Squamous Cell Head and Neck Cancer

Background: In head and neck cancer patients, parameters of metabolic and morphologic response of the tumor to single-cycle induction chemotherapy (IC) with docetaxel, cis- or carboplatin are used to decide the further course of treatment. This study investigated the effect of adding a double immune checkpoint blockade (DICB) of tremelimumab and durvalumab to IC on imaging parameters and their significance with regard to tumor cell remission. Methods: Response variables of 53 patients treated with IC+DICB (ICIT) were compared with those of 104 who received IC alone. Three weeks after one cycle, pathologic and, in some cases, clinical and endoscopic primary tumor responses were evaluated and correlated with a change in 18F-FDG PET and CT/MRI-based maximum-standardized uptake values (SUVmax) before (SUVmaxpre), after treatment (SUVmaxpost) and residually (resSUVmax in % of SUVmaxpre), and in maximum tumor diameter (Dmax) before (Dmaxpre) and after treatment (Dmaxpost) and residually (resD). Results: Reduction of SUVmax and Dmax occurred in both groups; values were SUVmaxpre: 14.4, SUVmaxpost: 6.6, Dmaxpre: 30 mm and Dmaxpost: 23 mm for ICIT versus SUVmaxpre: 16.5, SUVmaxpost: 6.4, Dmaxpre: 21 mm, and Dmaxpost: 16 mm for IC alone (all p < 0.05). ResSUVmax was the best predictor of complete response (IC: AUC: 0.77; ICIT: AUC: 0.76). Metabolic responders with resSUVmax ≤ 40% tended to have a higher rate of CR to ICIT (88%; n = 15/17) than to IC (65%; n = 30/46; p = 0.11). Of the metabolic nonresponders (resSUVmax > 80%), 33% (n = 5/15) achieved a clinical CR to ICIT versus 6% (n = 1/15) to IC (p = 0.01). Conclusions: ICIT and IC quickly induce a response and 18F-FDG PET is the more accurate modality for identifying complete remission. The rate of discrepant response, i.e., pCR with metabolic nonresponse after ICIT was >30%.

An evaluation of the response to neoadjuvant chemotherapy for osteosarcoma of extremities: PERCIST versus RECIST 1.1 criteria after long-term follow-up

OBJECTIVE

The aim of this study was to compare the recent Positron emission tomography (PET) Response Criteria in Solid Tumors (PERCIST) and Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria for evaluating the response of osteosarcoma to neoadjuvant chemotherapy of the extremities.

METHODS

We retrospectively reviewed patients with osteosarcoma of the extremities who received neoadjuvant chemotherapy and then surgical resection at Peking University People's Hospital. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and magnetic resonance imaging (MRI) were performed prior to chemotherapy and before surgical resection. Therapeutic response was assessed separately by the PERCIST and RECIST 1.1 criteria. The association between the data acquired by the PERCIST and RECIST 1.1 criteria was then analyzed by Wilcoxon's signed-rank test. The association between the PERCIST criteria and the pathological necrosis rate was analyzed by Fisher's exact test. Finally, the impact of a range of clinicopathological factors on overall survival (OS) and event-free survival (EFS) was analyzed by Cox proportional hazards regression.

RESULTS

We recruited 68 patients with a median follow-up of 74 months (range 45-102 months). The evaluations resulting from the RECIST 1.1 and PERCIST criteria were significantly different (p = 0.000). Only two responders were identified according to the RECIST 1.1 criteria. However, 34 responders were identified by the PERCIST criteria. Data arising from the PERCIST criteria were in accordance with the pathological necrosis rate. Survival analysis showed that metastasis at diagnosis, poor pathological response, and disease progression (according to the RECIST 1.1 or PERCIST criteria) were all associated with a poor prognosis (p < 0.05).

CONCLUSION

Our data indicate that the PERCIST criteria are significantly more sensitive than RECIST 1.1 criteria to identify more responders when evaluating the response of osteosarcoma to neoadjuvant chemotherapy.

Combined 177 Lu-PSMA-617 PRLT and abiraterone acetate versus 177 Lu-PSMA-617 PRLT monotherapy in metastatic castration-resistant prostate cancer: An observational study comparing the response and durability

OBJECTIVE

The aim of present study was to determine and compare the overall response rates, progression-free survival (PFS), overall survival (OS), and clinical toxicity of the combination of 177Lu-PSMA-617 radioligand therapy (PRLT) and abiraterone acetate (AA) versus 177Lu-PSMA-617 PRLT as monotherapy in metastatic castration-resistant prostate cancer (mCRPC) patients.

MATERIALS AND METHODS

The mCRPC patients who received at least one cycle of ¹⁷⁷ Lu-PSMA-617 PRLT with or without AA therapy, were included and analyzed in the present study. The patients were divided into two major groups. Group 1 received only ¹⁷⁷ Lu-PSMA PRLT and Group 2 received combined ¹⁷⁷ Lu-PSMA PRLT + AA therapy. Therapeutic dose of ¹⁷⁷ Lu-PSMA-617 PRLT was 4.4-5.55 GBq per patient per cycle administered at intervals of 10-12 weeks in both groups. The Group 2 patients additionally received a dose of 1000 mg of AA once daily and 5 mg of prednisone twice daily. Treatment response in two groups was evaluated under four broad categories (a) symptomatic, (b) biochemical (serum prostate-specific antigen level), (c) objective molecular imaging (⁶⁸ Ga-PSMA-11 and ¹⁸ F-FDG PET/CT), and (d) objective anatomical imaging (computed tomography). For assessing treatment response, patients in two groups were categorized into responders (complete response [CR], partial response [PR], and stable disease [SD]) and nonresponders (progressive disease [PD]). The Kaplan-Meier product-limit method was used to calculate PFS and OS following first ¹⁷⁷ Lu-PSMA PRLT in the two groups. Univariate analysis was used to compare the patients' characteristics in two groups using a χ² or Fisher exact test. The Kaplan-Meier curves of PFS and OS between two groups were compared by using the log-rank test (p < 0.05 significant).

RESULTS

A total of 58 mCRPC patients (Group 1, 38 patients and Group 2, 20 patients) were included in this study analysis. The clinical and demographic characteristics of these patients (age, Gleason score, FDG avid disease, metastatic disease burden, and average number of ¹⁷⁷ Lu-PSMA PRLT cycles) in two groups were compared and found to be similar (p > 0.05). Post-treatment, symptomatic, biochemical, molecular, and anatomic imaging responders were found in 22 patients (58%) and 17 patients (85%), 22 patients (58%) and 16 patients (80%), 19 patients (54%) and 14 patients (78%), and 19 patients (54%) and 14 patients (78%) in Group 1 and Group 2, respectively. The median PFS of 7 months and median OS of 8 months were documented in Group 1, whereas median PFS was not reached and median OS of 16 months registered in Group 2. Transient hematological toxicity of Grades 1 and 2 was found in total seven patients (five patients in Group 1 and two patients in Group 2). On comparison of the treatment outcome between two groups, significant p value was found for symptomatic responders (58% in Group 1 vs. 85% in Group 2), median PFS (7 months in Group 1 vs. not reached in Group 2), and median OS (8 months in Group 1 vs. 16 months in Group 2), with better outcome in Group 2 patients for these variables.

CONCLUSION

In the present study, the combination of ¹⁷⁷ Lu-PSMA-617 PRLT and AA therapy showed significant improvement in mCRPC patients' symptomatic response, PFS, and OS as compared to ¹⁷⁷ Lu-PSMA-617 PRLT monotherapy.

Response Evaluation and Survival Prediction After PD-1 Immunotherapy in Patients with Non-Small Cell Lung Cancer: Comparison of Assessment Methods

Immunotherapy using programmed death-1 blockers is a promising modality for non-small cell lung cancer (NSCLC). Therefore, defining the most accurate response criteria for immunotherapy monitoring is of great importance in patient management. This study aimed to compare the correlation between survival outcome and response assessment by PERCIST, version 1.0; immunotherapy-modified PERCIST (imPERCIST); RECIST, version 1.1; and immunotherapy-modified RECIST (iRECIST) in NSCLC patients. Methods: Seventy-two patients with NSCLC who were treated with nivolumab or pembrolizumab and had baseline and follow-up ¹⁸F-FDG PET/CT data were analyzed. The patients were categorized into responders (complete or partial response) and nonresponders (stable or progressive disease) according to PERCIST1 and PERCIST5 (analyzing the peak SUV normalized by lean body mass [SUL_peak] of 1 or up to 5 lesions), imPERCIST1, imPERCIST5, RECIST, and iRECIST. The correlation between achieved response and overall survival (OS) was compared. Results: The overall response rate and the overall disease control rate of the study population were 29% and 74%, respectively. The OS and progression-free survival (PFS) of patients with complete and partial response were statistically comparable. The OS and PFS were significantly different between responders and nonresponders (20.3 vs. 10.6 mo, P = 0.001, for OS and 15.5 vs. 2.2 mo, P < 0.001, for PFS, respectively). Twenty-three (32%) patients with progressive disease according to PERCIST5 had controlled disease according to imPERCIST5; follow-up of patients showed that 22% of these patients had pseudoprogression. The overall incidence of pseudoprogression was 7%. The response rate was 25% and 24% according to PERCIST1 and PERCIST5 (P = 0.2) and 32% and 29% according to imPERCIST1 and imPERCIST5 (P = 0.5), respectively, indicating no significant difference between analyzing the SUL_peak of only the most ¹⁸F-FDG-avid lesion and analyzing up to the 5 most ¹⁸F-FDG-avid lesions. Conclusion: The achieved response by all conventional and immunotherapy-modified methods correlated strongly with patients' survival outcome, with significantly longer OS and PFS in responders than in nonresponders according to all assessed definitions. The most ¹⁸F-FDG-avid lesion according to PERCIST and imPERCIST accurately reflects the overall metabolic response.

Predicting tumor response and prognosis to neoadjuvant chemotherapy in esophageal squamous cell carcinoma patients using PERCIST: a multicenter study in Japan

PURPOSE

To investigate the usefulness of the positron emission tomography response criteria in solid tumors 1.0 (PERCIST1.0) for predicting tumor response to neoadjuvant chemotherapy and prognosis and determine whether PERCIST improvements are necessary for esophageal squamous cell carcinoma (ESCC) patients.

PATIENTS AND METHODS

We analyzed the cases of 177 ESCC patients and examined the association between PERCIST and their pathological responses. Associations of whole-PERCIST with progression-free survival (PFS) and overall survival (OS) were evaluated by a Kaplan-Meier analysis and Cox proportional hazards model. To investigate potential PERCIST improvements, we used the survival tree technique to understand patients' prognoses.

RESULTS

There were significant correlations between the pathologic response and PERCIST of primary tumor (p < 0.001). The optimal cutoff value of the primary tumors' SULpeak response to classify pathologic responses was -50.0%. The diagnostic accuracy of SULpeak response was 87.3% sensitivity, 54.1% specificity, 68.9% accuracy, positive predictive value 60.5%, and negative predictive value 84.1%. Whole-PERCIST was significantly associated with PFS and OS. The survival tree results indicated that a high reduction of the whole SULpeak response was significantly correlated with the patients' prognoses. The cutoff values for the separation of prognoses were - 52.5 for PFS and - 47.1% for OS.

CONCLUSION

PERCIST1.0 can help predict tumor responses and prognoses. However, ¹⁸F-FDG-PET/CT tends to underestimate residual tumors in histopathological response evaluations. Modified PERCIST, in which the partial metabolic response is further classified by the SULpeak response (-50%), might be more appropriate than PERCIST1.0 for evaluating tumor responses and stratifying high-risk patients for recurrence and poor prognosis.

One Versus Up-to-5 Lesion Measurements for Response Assessment by PERCIST in Patients with Lung Cancer

Purpose

The optimal number of lesions to measure for response assessment from fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) is not validated for lung cancer. We compared 1 lesion and up-to-5 lesion measurements for response assessment in lung cancer per PET Response Criteria in Solid Tumors (PERCIST).

Methods

Patients with lung cancer with pre- and post-treatment PET/CT images were included. The standard uptake value corrected for lean body mass (SUL_peak) of up-to-5 hottest target lesions was measured at each time point. The percent changes of SUL_peak of the single hottest lesion and the sum of up-to-5 hottest lesions were computed. Pearson correlation coefficient evaluated the strength of association between the percent changes of SUL_peak values from the 1 lesion and up-to-5 lesion analyses. Response categories were complete metabolic response (CMR) with no perceptible lesion; partial metabolic response (PMR), stable metabolic disease (SMD), or progressive metabolic disease (PMD) using the threshold of 30% and 0.8 unit change in SUL_peak; and unequivocal new lesion meant PMD. The concordance for response categorization was assessed by kappa statistics.

Results

A total of 40 patients (25 non-small cell lung cancer; 15 small cell lung cancer) were analyzed, all with ¹⁸F-FDG-avid lung cancer. Average of 3 target lesions were measured for up-to-5 lesion analysis. Pearson's r was 0.74 (P < 0.001) and increased to 0.96 (P < 0.001) when two outliers were excluded. Response categorization with 1 lesion and up-to-5 lesion analyses was concordant in 37 patients (92.5%, weighted kappa = 0.89).

Conclusion

Analyzing 1 lesion and up-to-5 lesions for response assessment by PERCIST showed high concordance in patients with lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-021-00697-4.

FDG-PET/CT for Response Monitoring in Metastatic Breast Cancer: The Feasibility and Benefits of Applying PERCIST

Background: We aimed to examine the feasibility and potential benefit of applying PET Response Criteria in Solid Tumors (PERCIST) for response monitoring in metastatic breast cancer (MBC). Further, we introduced the nadir scan as a reference. Methods: Response monitoring FDG-PET/CT scans in 37 women with MBC were retrospectively screened for PERCIST standardization and measurability criteria. One-lesion PERCIST based on changes in SULpeak measurements of the hottest metastatic lesion was used for response categorization. The baseline (PERCIST_baseline) and the nadir scan (PERCIST_nadir) were used as references for PERCIST analyses. Results: Metastatic lesions were measurable according to PERCIST in 35 of 37 (94.7%) patients. PERCIST was applied in 150 follow-up scans, with progression more frequently reported by PERCIST_nadir (36%) than PERCIST_baseline (29.3%; p = 0.020). Reasons for progression were (a) more than 30% increase in SUL_peak of the hottest lesion (n = 7, 15.9%), (b) detection of new metastatic lesions (n = 28, 63.6%), or both (a) and (b) (n = 9, 20.5%). Conclusions: PERCIST, with the introduction of PERCIST_nadir, allows a graphical interpretation of disease fluctuation that may be beneficial in clinical decision-making regarding potential earlier termination of non-effective toxic treatment. PERCIST seems feasible for response monitoring in MBC but prospective studies are needed to come this closer.

Consensus statements on PSMA PET/CT response assessment criteria in prostate cancer

PURPOSE

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) is used for (re)staging prostate cancer (PCa) and as a biomarker for evaluating response to therapy, but lacks established response criteria. A panel of PCa experts in nuclear medicine, radiology, and/or urology met on February 21, 2020, in Amsterdam, The Netherlands, to formulate criteria for PSMA PET/CT-based response in patients treated for metastatic PCa and optimal timing to use it.

METHODS

Panelists received thematic topics and relevant literature prior to the meeting. Statements on how to interpret response and progression on therapy in PCa with PSMA PET/CT and when to use it were developed. Panelists voted anonymously on a nine-point scale, ranging from strongly disagree (1) to strongly agree (9). Median scores described agreement and consensus.

RESULTS

PSMA PET/CT consensus statements concerned utility, best timing for performing, criteria for evaluation of response, patients who could benefit, and handling of radiolabeled PSMA PET tracers. Consensus was reached on all statements. PSMA PET/CT can be used before and after any local and systemic treatment in patients with metastatic disease to evaluate response to treatment. Ideally, PSMA PET/CT imaging criteria should categorize patients as responders, patients with stable disease, partial response, and complete response, or as non-responders. Specific clinical scenarios such as oligometastatic or polymetastatic disease deserve special consideration.

CONCLUSIONS

Adoption of PSMA PET/CT should be supported by indication for appropriate use and precise criteria for interpretation. PSMA PET/CT criteria should categorize patients as responders or non-responders. Specific clinical scenarios deserve special consideration.

Interrater Agreement and Reliability of PERCIST and Visual Assessment When Using 18F-FDG-PET/CT for Response Monitoring of Metastatic Breast Cancer

Response evaluation at regular intervals is indicated for treatment of metastatic breast cancer (MBC). FDG-PET/CT has the potential to monitor treatment response accurately. Our purpose was to: (a) compare the interrater agreement and reliability of the semi-quantitative PERCIST criteria to qualitative visual assessment in response evaluation of MBC and (b) investigate the intrarater agreement when comparing visual assessment of each rater to their respective PERCIST assessment. We performed a retrospective study on FDG-PET/CT in women who received treatment for MBC. Three specialists in nuclear medicine categorized response evaluation by qualitative assessment and standardized one-lesion PERCIST assessment. The scans were categorized into complete metabolic response, partial metabolic response, stable metabolic disease, and progressive metabolic disease. 37 patients with 179 scans were included. Visual assessment categorization yielded moderate agreement with an overall proportion of agreement (PoA) between raters of 0.52 (95% CI 0.44-0.66) and a Fleiss kappa estimate of 0.54 (95% CI 0.46-0.62). PERCIST response categorization yielded substantial agreement with an overall PoA of 0.65 (95% CI 0.57-0.73) and a Fleiss kappa estimate of 0.68 (95% CI 0.60-0.75). The difference in PoA between overall estimates for PERCIST and visual assessment was 0.13 (95% CI 0.06-0.21; p = 0.001), that of kappa was 0.14 (95% CI 0.06-0.21; p < 0.001). The overall intrarater PoA was 0.80 (95% CI 0.75-0.84) with substantial agreement by a Fleiss kappa of 0.74 (95% CI 0.69-0.79). Semi-quantitative PERCIST assessment achieved significantly higher level of overall agreement and reliability compared with qualitative assessment among three raters. The achieved high levels of intrarater agreement indicated no obvious conflicting elements between the two methods. PERCIST assessment may, therefore, give more consistent interpretations between raters when using FDG-PET/CT for response evaluation in MBC.

Predicting tumor response and outcome of second-look surgery with 18F-FDG PET/CT: insights from the GINECO CHIVA phase II trial of neoadjuvant chemotherapy plus nintedanib in stage IIIc-IV FIGO ovarian cancer

Background

This ancillary study aimed to evaluate ¹⁸F-FDG PET parameter changes after one cycle of treatment compared to baseline in patients receiving first-line neoadjuvant anti-angiogenic nintedanib combined to paclitaxel-carboplatin chemotherapy or chemotherapy plus placebo and to evaluate the ability of ¹⁸F-FDG PET parameters to predict progression-free survival (PFS), overall survival (OS), and success of second-look surgery.

Materials and methods

Central review was performed by two readers blinded to the received treatment and to the patients’ outcome, in consensus, by computing percentage change in PET metrics within a volume of interest encompassing the entire tumor burden. EORTC and PERCIST criteria were applied to classify patients as responders (partial metabolic response and complete metabolic response) or non-responders (stable metabolic disease and progressive metabolic disease). Also analyzed was the percentage change in metabolic active tumor volume (MATV) and total lesion glycolysis (TLG).

Results

Twenty-four patients were included in this ancillary study: 10 received chemotherapy + placebo and 14 chemotherapy + nintedanib. PERCIST and EORTC criteria showed similar discriminative power in predicting PSF and OS. Variation in MATV/TLG did not predict PFS or OS, and no optimal threshold could be found for MATV/TLG for predicting survival. Complete cytoreductive surgery (no residual disease versus residual disease < 0.25 cm/0.25–2.5 cm/> 2.5 cm) was more frequent in responders versus non-responders (P = 0.002 for PERCIST and P = 0.02 for EORTC criteria). No correlation was observed between the variation of PET data and the variation of CA-125 blood level between baseline sample and that performed contemporary to the interim PET, but a statistically significant correlation was observed between ΔSUL_peak and ΔCA-125 between baseline sample and that performed after the second cycle.

Conclusion

¹⁸F-FDG PET using EORTC or PERCIST criteria appeared to be a useful tool in ovarian cancer trials to analyze early tumor response, and predict second-look surgery outcome and survival. An advantage of PERCIST is the correlation of ΔSUL_peak and ΔCA-125, PET response preceding tumor markers response by 1 month. Neither MATV nor TLG was useful in predicting survival.

Trial registration

NCT01583322 ARCAGY/ GINECO GROUP GINECO-OV119, 24 April 2012

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-020-05092-3.

Comparison of Metabolic and Morphological Response Criteria for Early Prediction of Response and Survival in NSCLC Patients Treated With Anti-PD-1/PD-L1

Introduction/Aim: Immunotherapy with immune checkpoint inhibitors (ICIs) has positively changed the history of several malignant tumors. In parallel, new challenges have emerged in the evaluation of treatment response as a result of their peculiar anticancer effect. In the current study, we aimed to compare different response criteria, both morphological and metabolic, for assessing response and outcome in patients with advanced non-small cell lung cancer (NSCLC) treated with ICI. Materials and Methods: Overall, 52 patients with advanced NSCLC candidate to ICI were prospectively evaluated. Inclusion criteria comprised whole-body contrast-enhanced CT and 18F-FDG PET/CT at baseline and at the first response evaluation 3 or 4 cycles after ICI. Response assessment on CT was performed according to RECIST 1.1 and imRECIST criteria, whereas metabolic response on PET was computed by EORTC, PERCIST, imPERCIST, and PERCIMT criteria. The concordance between the different tumor response criteria and the performance of each criterion to predict progression-free survival (PFS) and overall survival (OS) were calculated. Results: Inclusion criteria were fulfilled in 35 out of 52 patients. We observed a low agreement between imRECIST and imPERCIST (κ = 0.143) with discordant response in 20 patients, particularly regarding stable disease and progressive disease groups. Fair agreement between imRECIST and EORTC (κ = 0.340), and PERCIST (κ = 0.342), and moderate for PERCIMT (κ = 0.413) were detected. All criteria were significantly associated with PFS, while only PERCIMT and imPERCIST were associated with OS. Of note, in patients classified as immune stable disease (iSD), imPERCIST, and PERCIMT well-differentiated those with longer PFS (p < 0.001, p = 0.009) and OS (p = 0.001, p = 0.002). In the multivariate analysis, performance status [hazard ratio (HR) = 0.278, p = 0.015], imRECIST (HR = 3.799, p = 0.026), and imPERCIST (HR = 4.064, p = 0.014) were predictive factors for PFS, while only performance status (HR = 0.327, p = 0.035) and imPERCIST (HR = 3.247, p = 0.007) were predictive for OS. Conclusions: At the first evaluation during treatment with ICI, imPERCIST criteria correctly evaluated treatment response and appeared able to predict survival. Moreover, in patients with iSD on CT, imPERCIST were able to discriminate those with longer survival. This advantage might allow for earlier therapy modification based on metabolic response.

Factors affecting the response to Y-90 microsphere therapy in the cholangiocarcinoma patients

OBJECTIVE

The aim of this study was to assess the early therapy response in patients with unresectable CCA who received Y-90 microsphere therapy for CCA and define the factors related to therapy response.

MATERIALS AND METHODS

Data of 19 patients [extrahepatic (n: 6) and intrahepatic (n: 13)] who received 24 sessions of Y-90 microsphere therapy [glass (n: 13) and resin (n: 11)] were retrospectively evaluated. Tumor load, tumor size, therapy response evaluation by RECIST1.1 criteria (n: 13), tumor lesion glycolysis (TLG), metabolic tumor volume (MTV), and metabolic therapy responses were evaluated (n: 8) using PERCIST1.0 criteria.

RESULTS

No significant relation was found between therapy response and tumor localization, treated liver lobe, type of Y90 microspheres, the presence of previous therapies, perfusion pattern on hepatic artery perfusion scintigraphy, or patient demographics. The mean overall survival (OS) was 11.9 ± 2.3 months and was similar after both resin and glass Y90 microspheres; however, it was longer RECIST responders (p: 0.005). MTV and TLG values significantly decreased after therapy, and ΔMTV (- 45.4% ± 12.1) was found to be positively correlated with OS. No statistical difference was found between iCCA and eCCA, in terms of OS and response to therapy. Although not quantitatively displayed, better-perfused areas on HAPS images had a better metabolic response and less perfused areas were prone to local recurrences.

CONCLUSIONS

Both resin and glass microsphere therapy can be applied safely to iCCA and eCCA patients. Early therapy response can be evaluated with both RECIST and PERCIST criteria. Both anatomical and metabolic therapy response evaluations give complementary information.

Usefulness of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography for predicting the prognosis and treatment response of neoadjuvant therapy for pancreatic ductal adenocarcinoma

BACKGROUND

The Response Evaluation Criteria in Solid Tumors (RECIST) for computed tomography (CT) is preoperatively used to evaluate therapeutic effects. However, it does not reflect the pathological treatment response (PTR) of pancreatic ductal adenocarcinoma (PDAC). The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) for positron emission tomography (PET)/CT is effective in other cancers. This study aimed to confirm the usefulness of PERCIST and the prognostic utility of PET/CT for PDAC.

METHODS

Forty-two consecutive patients with PDAC who underwent neoadjuvant therapy (NAT) and pancreatectomy at our institution between 2014 and 2018 were retrospectively analyzed. We evaluated the treatment response and prognostic significance of PET/CT parameters and other clinicopathological factors.

RESULTS

Twenty-two patients who underwent PET/CT both before and after NAT with the same protocol were included. RECIST revealed stable disease and partial response in 20 and 2 cases, respectively. PERCIST revealed stable metabolic disease, partial metabolic response, and complete metabolic response in 8, 9, and 5 cases, respectively. The PTR was G3, G2, and G1 in 8, 12, and 2 cases, respectively. For comparing the concordance rates between PTR and each parameter, PERCIST (72.7% [16/22]) was significantly superior to RECIST (36.4% [8/22]) (P = .017). The area under the curve survival values of PET/CT parameters were 0.777 for metabolic tumor volume (MTV), 0.500 for maximum standardized uptake value, 0.554 for peak standardized uptake value corrected for lean body mass, and 0.634 for total lesion glycolysis. A 50% cut-off value for the MTV reduction rate yielded the largest difference in survival between responders and nonresponders. On multivariate analysis, MTV reduction rates < 50% were independent predictors for relapse-free survival (hazard ratio [HR], 3.92; P = .044) and overall survival (HR, 14.08; P = .023).

CONCLUSIONS

PERCIST was more accurate in determining NAT's therapeutic effects for PDAC than RECIST. MTV reduction rates were independent prognostic factors for PDAC.

FDG-PET/CT Versus Contrast-Enhanced CT for Response Evaluation in Metastatic Breast Cancer: A Systematic Review

18F-fluorodeoxyglucose positron emission tomography with integrated computed tomography (FDG-PET/CT) and contrast-enhanced computed tomography (CT) can be used for response evaluation in metastatic breast cancer (MBC). In this study, we aimed to review literature comparing the PET Response Criteria in Solid Tumors (PERCIST) with Response Evaluation Criteria in Solid Tumors (RECIST) in patients with MBC. We made a systematic search in Embase, PubMed/Medline, and Cochrane Library using a modified PICO model. The population was MBC patients and the intervention was PERCIST or RECIST. Quality assessment was performed using the QUADAS-2 checklist. A total of 1975 articles were identified. After screening by title/abstract, 78 articles were selected for further analysis of which 2 duplicates and 33 abstracts/out of focus articles were excluded. The remaining 43 articles provided useful information, but only one met the inclusion and none of the exclusion criteria. This was a retrospective study of 65 patients with MBC showing one-year progression-free survival for responders versus non-responders to be 59% vs. 27% (p = 0.2) by RECIST compared to 64% vs. 0% (p = 0.0001) by PERCIST. This systematic literature review identified a lack of studies comparing the use of RECIST (with CE-CT) and PERCIST (with FDG-PET/CT) for response evaluation in metastatic breast cancer. The available sparse literature suggests that PERCIST might be more appropriate than RECIST for predicting prognosis in patients with MBC.

FDG-PET/CT for Response Monitoring in Metastatic Breast Cancer: Today, Tomorrow, and Beyond

While current international guidelines include imaging of the target lesion for response monitoring in metastatic breast cancer, they do not provide specific recommendations for choice of imaging modality or response criteria. This is important as clinical decisions may vary depending on which imaging modality is used for monitoring metastatic breast cancer. FDG-PET/CT has shown high accuracy in diagnosing metastatic breast cancer, and the Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) have shown higher predictive values than the CT-based Response Evaluation Criteria in Solid Tumors (RECIST) for prediction of progression-free survival. No studies have yet addressed the clinical impact of using different imaging modalities or response evaluation criteria for longitudinal response monitoring in metastatic breast cancer. We present a case study of a patient with metastatic breast cancer who was monitored first with conventional CT and then with FDG-PET/CT. We retrospectively applied PERCIST to evaluate the longitudinal response to treatment. We used the one-lesion PERCIST model measuring SULpeak in the hottest metastatic lesion on consecutive scans. This model provides a continuous variable that allows graphical illustration of disease fluctuation along with response categories. The one-lesion PERCIST approach seems able to reflect molecular changes and has the potential to support clinical decision-making. Prospective clinical studies addressing the clinical impact of PERCIST in metastatic breast cancer are needed to establish evidence-based recommendations for response monitoring in this disease.

Development of sodium fluoride PET response criteria for solid tumours (NAFCIST) in a clinical trial of radium-223 in osteosarcoma: from RECIST to PERCIST to NAFCIST

Purpose

The development of osteosarcoma therapeutics has been challenging, in part because of the lack of appropriate criteria to evaluate responses. We developed a novel criteria in a clinical trial of radium-223 dichloride (²²³RaCl₂) for response assessment in osteosarcoma, NAFCIST (Na¹⁸F PET response Criteria in Solid Tumors).

Experimental design

Patients received one to six cycles of ²²³RaCl₂, and cumulative doses varied from 6.84 MBq to 57.81 MBq. Molecular imaging with technetium-99m phosphonate scintigraphy, fluorine-18-fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET) or sodium fluoride-18 (Na¹⁸F) PET was used to characterise the disease. Correlation of biomarkers and survival was analysed with NAFCIST measure from Na¹⁸F PET.

Results

Of the 18 patients, 17 had bone lesions visible in at least one of the imaging studies. In four of seven patients with multiple skeletal lesions (>5), FDG PET and NaF PET studies could be compared. The skeletal tumour locations varied in our patient population: cranium=2, extremities=7, pelvis=10, spine=12 and thorax=9. The ¹⁸F-FDG PET and Na¹⁸F PET studies could be compared in all four patients who had multiple lung lesions (>5). Overall the Response Evaluation Criteria in Solid Tumors response was seen in one patient, but four patients experienced mixed responses better defined by Na¹⁸F PET. Changes in NAFCIST were correlated with changes in bone alkaline phosphatase levels (r=0.54) and negatively with cumulative dose of ²²³RaCl₂ (r=- 0.53). NAFCIST correlated with overall survival (p value of 0.037) while the PERCIST (PET Response Criteria in Solid Tumors) did not (p value of 0.19).

Conclusions

Our results indicate that Na¹⁸F PET should be further studied in osteosarcoma staging. NAFCIST may be a promising criteria for high-risk osteosarcoma response evaluation and correlates with survival. Further validation studies are needed.

18F-FDG PET/CT for Monitoring of Ipilimumab Therapy in Patients with Metastatic Melanoma

Immune checkpoint inhibitors (ICIs) are now commonly used to treat patients with metastatic malignant melanoma. Although concerns have been raised that the inflammatory response induced by ICIs may limit the ability of ¹⁸F-FDG PET/CT to assess tumor response, systematic analyses on the use of ¹⁸F-FDG PET/CT in this setting are mostly lacking. Thus, we set out to evaluate the association between tumor response on ¹⁸F-FDG PET/CT and prognosis in patients with metastatic malignant melanoma treated with ipilimumab. Methods: We analyzed 60 consecutive patients with metastatic melanoma who underwent ¹⁸F-FDG PET/CT scans both before and after treatment to evaluate treatment response after completion of ipilimumab therapy. Tumor response was assessed by the change in the sum of SULpeak (voxels with the highest average SUL [SUV normalized to lean body mass]) of up to 5 lesions according to PERCIST5. New lesions on PET that appeared suggestive of metastases were considered progressive metabolic disease (PMD). Because immunotherapy may cause new inflammatory lesions that are detectable on ¹⁸F-FDG PET/CT, we also evaluated an immunotherapy-modified response classification (imPERCIST5). In this classification, new lesions do not define PMD per se; rather, PMD requires an increase in the sum of SULpeak by 30%. The correlation between tumor response according to these 3 definitions and overall survival (OS) was evaluated and compared with known prognostic factors. Results: In responders and nonresponders, the 2-y OS was 66% versus 29% for imPERCIST5 (P = 0.003). After multivariate analysis, imPERCIST5 remained prognostic (hazard ratio, 3.853; 95% confidence interval, 1.498-9.911; P = 0.005). New sites of focal ¹⁸F-FDG uptake occurred more often in patients with PMD (n = 24) by imPERCIST5 than in those with stable metabolic disease (n = 7) or partial metabolic response (n = 4). In patients with partial metabolic response, 2 of 4 isolated new lesions regressed spontaneously during follow-up. Conclusion: In patients with metastatic melanoma treated with ipilimumab, tumor response according to PERCIST was associated with OS. Our data suggest that PMD should not be defined by the appearance of new lesions, but rather by an increase in the sum of SULpeak.

Evaluation of RECIST, PERCIST, EORTC, and MDA Criteria for Assessing Treatment Response with Ga68-PSMA PET-CT in Metastatic Prostate Cancer Patient with Biochemical Progression: a Comparative Study

Purpose

The aim of the study was to compare response evaluation criteria in solid tumours 1.1 (RECIST 1.1), positron emission tomography response criteria in solid tumours (PERCIST), European organisation for research and treatment of cancer (EORTC), and MD Anderson (MDA) criteria for response assessment by Gallium 68-prostate-specific membrane antigen positron emission tomography-computed tomography (Ga68-PSMA PET-CT) in metastatic adenocarcinoma prostate cancer (mPCa) patients with biochemical progression.

Methods

Eighty-eight mPCa patients with pre and post treatment Ga68-PSMA PET-CT were included. A ≥ 25% increase and ≥ 2 ng/ml above the nadir if prostate specific antigen (PSA) drop or ≥ 2 ng/ml above the baseline if PSA does not drop was considered as biochemical progression. RECIST 1.1 and MDA criteria for morphology and PERCIST and EORTC criteria for molecular response were investigated. Percentages of progressive disease (PD), partial response (PR), and stable disease (SD) were calculated. Chi-square test was used for statistical significance.

Results

Proportion of PD, SD, and PR by RECIST 1.1 and MDA criteria were 44 (50.57%), 39 (44.83%), 4 (4.6%), and 33 (39.76%), 48 (57.83%), 2 (2.41%) respectively. Proportion of PD, SD, and PR by PERCIST and EORTC criteria were 71 (80.68%), 11 (12.50%), 6 (6.82%), and 74 (84.09%), 8 (9.09%), 6 (6.82%) respectively. Chi-square test showed statistically significant (P < 0.05) higher proportion of progression detected by both molecular criteria as compare to both morphological criteria.

Conclusion

We concluded that for Ga68-PSMA PET-CT response evaluation, molecular criteria performed better than morphological criteria in mPCa patient with PSA progression.

What 18F-FDG PET Response-Assessment Method Best Predicts Survival After Curative-Intent Chemoradiation in Non-Small Cell Lung Cancer: EORTC, PERCIST, Peter Mac Criteria, or Deauville Criteria?

The optimal methodology for defining response with ¹⁸F-FDG PET after curative-intent chemoradiation for non-small cell lung cancer (NSCLC) is unknown. We compared survival outcomes according to the criteria of the European Organization for Research and Treatment of Cancer (EORTC), PERCIST 1.0, the Peter Mac metabolic visual criteria, and the Deauville criteria, respectively. Methods: Three prospective trials of chemoradiation for NSCLC, involving baseline and posttreatment ¹⁸F-FDG PET/CT imaging, were conducted between 2004 and 2016. Responses were categorized as complete metabolic response (CMR), partial metabolic response, stable metabolic disease, or progressive metabolic disease. Cox proportional-hazards models and log-rank tests assessed the impact of each response on overall survival (OS). Results: Eighty-seven patients underwent ¹⁸F-FDG PET/CT before and after radical chemoradiation for NSCLC. Follow-up ¹⁸F-FDG PET/CT scans were performed at a median of 89 d (interquartile range, 79-93 d) after radiotherapy. Median follow-up and OS after PET response imaging were 49 and 28 mo, respectively. Interobserver agreements for EORTC, PERCIST, Peter Mac, and Deauville had κ values of 0.76, 0.76, 0.87, and 0.84, respectively. All 4 response criteria were significantly associated with OS. Peter Mac and Deauville showed better fit than EORTC and PERCIST and distinguished better between CMR and non-CMR. Conclusion: All 4 response criteria were highly predictive of OS, but visual criteria showed greater interobserver agreement and stronger discrimination between CMR and non-CMR, highlighting the importance of visual assessment to recognize radiation pneumonitis, changes in lung configuration, and patterns of response.

Assessment of tumor response to chemoradiotherapy and predicting prognosis in patients with head and neck squamous cell carcinoma by PERCIST

PURPOSE

To evaluate therapeutic response to chemoradiotherapy and prediction of recurrence and death in patients with head and neck squamous cell carcinoma (HNSCC) using Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST).

MATERIALS AND METHODS

Forty-two patients (mean 63.4, range 20-79 years) with nasopharyngeal (n = 10), oropharyngeal (n = 13), hypopharyngeal (n = 11), or laryngeal (n = 8) cancer underwent fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) before and approximately 3 months (mean 95.0, range 70-119 days) after undergoing concurrent chemoradiotherapy. The effect of PERCIST regarding progression-free survival (PFS) and overall survival (OS) was examined using log-rank and Cox methods.

RESULTS

Complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease shown by PERCIST were seen in 30 (71.4%), 9 (21.4%), 3 (7.1%), and 0 patients, respectively. Fourteen (33.3%) developed recurrent disease (median follow-up 27.2, range 8.7-123.1 months) and 9 (21.4%) died (median follow-up 43.6, range 9.6-132.6 months). Furthermore, 4 (13.3%) of 30 patients with CMR developed recurrence, while 7 (77.8%) of 9 with PMR and all 3 (100%) with SMD developed recurrence. Two (6.7%) of 30 patients with CMR, 4 (44.4%) of 9 with PMR, and all 3 (100%) with SMD died. Patients who achieved CMR showed significantly longer PFS and OS as compared to those who did not (PMR and SMD) (both, p < 0.0001).

CONCLUSION

PERCIST is useful for evaluating therapeutic response to chemoradiotherapy and predicting recurrence and death in HNSCC patients.

Response to neoadjuvant chemotherapy for breast cancer judged by PERCIST - multicenter study in Japan

PURPOSE

The purpose of this study was to evaluate therapeutic response to neoadjuvant chemotherapy (NAC) and predict breast cancer recurrence using Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST).

MATERIALS AND METHODS

Fifty-nine breast cancer patients underwent fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) before and after NAC prior to planned surgical resection. Pathological complete response (pCR) of the primary tumor was evaluated using PERCIST, while effects of clinicopathological factors on progression-free survival (PFS) were examined using log-rank and Cox methods.

RESULTS

Fifty-six patients and 54 primary tumors were evaluated. Complete metabolic response (CMR), partial metabolic response, stable metabolic disease, and progressive metabolic disease were seen in 45, 7, 3, and 1 patients, respectively, and 43, 7, 3, and 1 primary tumors, respectively. Eighteen (33.3%) of the 54 primary tumors showed pCR. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PERCIST to predict pCR were 100% (18/18), 30.6% (11/36), 41.9% (18/43), 100% (11/11), and 53.7% (29/54), respectively. An optimal percent decrease in peak standardized uptake value for a primary tumor corrected for lean body mass (SULpeak) of 84.3% was found to have a sensitivity of 77.8% (14/18), specificity of 77.8% (28/36), PPV of 63.6% (14/22), NPV of 87.5% (28/32), and accuracy of 77.8% (42/54). Seven (12.5%) of the 56 patients developed recurrent disease (median follow-up 28.1 months, range 11.4-96.4 months). CMR (p = 0.031), pCR (p = 0.024), and early TNM stage (p = 0.033) were significantly associated with longer PFS.

CONCLUSION

PERCIST is useful for predicting pathological response and prognosis following NAC in breast cancer patients. However, FDG-PET/CT showed a tendency toward underestimation of the residual tumor, and relatively low specificity and PPV of PERCIST showed that a combination of other imaging modalities would still be needed to predict pCR.

The evolving landscape of criteria for evaluating tumor response in the era of cancer immunotherapy: From Karnofsky to iRECIST

The objective response is an important endpoint to evaluate clinical activity of new anticancer drugs. Standardized criteria for evaluating response are needed for comparing results of different trials and represent the basis for advances in cancer therapy. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 are the most used in clinical practice and in clinical trials; however, they are not able to capture atypical responses seen with immunotherapy drugs. We describe the evolution of response criteria with a special focus on the immune-related criteria.

Comparison of the EORTC criteria and PERCIST in solid tumors: a pooled analysis and review

Two sets of response criteria using PET are currently available to monitor metabolic changes in solid tumors: the criteria developed by the European Organization for Research and Treatment of Cancer (EORTC criteria) and the PET Response Criteria in Solid Tumors (PERCIST). We conducted this pooled study to investigate the strength of agreement between the EORTC criteria and PERCIST in the assessment of tumor response. We surveyed MEDLINE, EMBASE and PUBMED for articles with terms of the EORTC criteria and PERCIST between 2009 and January 2016. We searched for all the references of relevant articles and reviews using the ‘related articles’ feature in the PUBMED. There were six articles with the data on the comparison of the EORTC criteria and PERCIST. A total of 348 patients were collected; 190 (54.6%) with breast cancer, 81 with colorectal cancer, 45 with lung cancer, 14 with basal cell carcinoma in the skin, 12 with stomach cancer, and 6 with head and neck cancer. The agreement of tumor response between the EORTC criteria and PERCIST was excellent (k = 0.946). Of 348 patients, only 12 (3.4%) showed disagreement between the two criteria in the assessment of tumor response. The shift of tumor response between the EORTC criteria and PERCIST occurred mostly in patients with PMR and SMD. The estimated overall response rates were not significantly different between the two criteria (72.7% by EORTC vs. 73.6% by PERCIST). In conclusion, this pooled analysis demonstrates that the EORTC criteria and PERCIST showed almost perfect agreement in the assessment of tumor response.

PERCIST 1.0

PURPOSE

We compared the response classification systems Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) 1.0 for assessment of response to neoadjuvant chemotherapy in patients with esophageal cancer.

MATERIALS AND METHODS

Prior to planned surgical resection, 62 patients with esophageal cancer underwent fluorodeoxyglucose (FDG)-PET/CT and contrast-enhanced CT examinations before and after receiving neoadjuvant chemotherapy. Primary tumor largest diameter, maximum standardized uptake value (SUVmax), peak lean body mass SUV (SULpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were determined. Patients were divided into responders (grade 1b-3) and non-responders (grade 0-1a) according to pathological response.

RESULTS

Concordance between RECIST 1.1 and PERCIST 1.0 for response classification was seen in 28 (45.2%) patients. For 18 defined as responders, the number of metabolic responders (partial metabolic response + complete metabolic response) shown by PERCIST 1.0 was 17 and the number of anatomic responders (partial response + complete response) shown by RECIST 1.1 was 13. To distinguish responders from non-responders, the area under the receiver operating characteristics curve values for reduced primary tumor largest diameter, SUVmax, SULpeak, MTV, and TLG were 0.724, 0.775, 0.781, 0.756, and 0.759, respectively. An optimal percent decrease in largest diameter cut-off value of 39.2% was found to have 66.7% sensitivity and 70.5% specificity, while that for SULpeak of 55.8% was 77.8% and 75.0%, respectively.

CONCLUSIONS

As compared to RECIST 1.1, PERSIST 1.0 may be more suitable for evaluation of neoadjuvant therapeutic response to esophageal cancer.

Comparison of the RECIST and PERCIST criteria in solid tumors: a pooled analysis and review

The PET Response Criteria in Solid Tumors (PERCIST) is a new method for the quantitative assessment of metabolic changes in solid tumors. The assessments of tumor response between the RECIST and PERCIST have shown considerable difference in several studies. This pooled study was conducted to compare tumor response according to the two criteria in patients with solid tumors. We surveyed MEDLINE, EMBASE and PUBMED for articles with terms of the RECIST or PERCIST from 2009 and January 2016. There were six articles comparing the RECIST and PERCIST. A total of 268 patients were recruited; 81 with colorectal cancer, 60 with lung cancer, 48 with esophageal cancer, 28 with breast cancer, 14 with basal cell carcinoma, 12 with stomach cancer, 10 with head and neck cancer, and 16 with other rare cancers. The agreement of tumor response between the RECIST and PERCIST was moderate (k = 0.590). Of 268 patients, 101 (37.7%) showed discordance in the tumor responses between two criteria. When adopting the PERCIST, tumor response was upgraded in 85 patients and downgraded in 16. The estimated overall response rates were significantly different between two criteria (35.1% by RECIST vs. 54.1% by PERCIST, P < 0.0001). In conclusion, this pooled analysis demonstrates that the concordance of tumor responses between the RECIST and PERCIST criteria is not excellent. The PERCIST might be more suitable for assessing tumor response than the RECIST criteria.

EANM/EARL harmonization strategies in PET quantification: from daily practice to multicentre oncological studies

Quantitative positron emission tomography/computed tomography (PET/CT) can be used as diagnostic or prognostic tools (i.e. single measurement) or for therapy monitoring (i.e. longitudinal studies) in multicentre studies. Use of quantitative parameters, such as standardized uptake values (SUVs), metabolic active tumor volumes (MATVs) or total lesion glycolysis (TLG), in a multicenter setting requires that these parameters be comparable among patients and sites, regardless of the PET/CT system used. This review describes the motivations and the methodologies for quantitative PET/CT performance harmonization with emphasis on the EANM Research Ltd. (EARL) Fluorodeoxyglucose (FDG) PET/CT accreditation program, one of the international harmonization programs aiming at using FDG PET as a quantitative imaging biomarker. In addition, future accreditation initiatives will be discussed. The validation of the EARL accreditation program to harmonize SUVs and MATVs is described in a wide range of tumor types, with focus on therapy assessment using either the European Organization for Research and Treatment of Cancer (EORTC) criteria or PET Evaluation Response Criteria in Solid Tumors (PERCIST), as well as liver-based scales such as the Deauville score. Finally, also presented in this paper are the results from a survey across 51 EARL-accredited centers reporting how the program was implemented and its impact on daily routine and in clinical trials, harmonization of new metrics such as MATV and heterogeneity features.

EORTC PET response criteria are more influenced by reconstruction inconsistencies than PERCIST but both benefit from the EARL harmonization program

Background

This study evaluates the consistency of PET evaluation response criteria in solid tumours (PERCIST) and European Organisation for Research and Treatment of Cancer (EORTC) classification across different reconstruction algorithms and whether aligning standardized uptake values (SUVs) to the European Association of Nuclear Medicine acquisition (EANM)/EARL standards provides more consistent response classification.

Materials and methods

Baseline (_PET1) and response assessment (_PET2) scans in 61 patients with non-small cell lung cancer were acquired in protocols compliant with the EANM guidelines and were reconstructed with point-spread function (PSF) or PSF + time-of-flight (TOF) reconstruction for optimal tumour detection and with a standardized ordered subset expectation maximization (OSEM) reconstruction known to fulfil EANM harmonizing standards. Patients were recruited in three centres. Following reconstruction, EQ.PET, a proprietary software solution was applied to the PSF ± TOF data (PSF ± TOF.EQ) to harmonize SUVs to the EANM standards. The impact of differing reconstructions on PERCIST and EORTC classification was evaluated using standardized uptake values corrected for lean body mass (SUL).

Results

Using OSEM_PET1/OSEM_PET2 (standard scenario), responders displayed a reduction of −57.5% ± 23.4 and −63.9% ± 22.4 for SUL_max and SUL_peak, respectively, while progressing tumours had an increase of +63.4% ± 26.5 and +60.7% ± 19.6 for SUL_max and SUL_peak respectively. The use of PSF ± TOF reconstruction impacted the classification of tumour response. For example, taking the OSEM_PET1/PSF ± TOF_PET2 scenario reduced the apparent reduction in SUL in responding tumours (−39.7% ± 31.3 and −55.5% ± 26.3 for SUL_max and SUL_peak, respectively) but increased the apparent increase in SUL in progressing tumours (+130.0% ± 50.7 and +91.1% ± 39.6 for SUL_max and SUL_peak, respectively).

Consequently, variation in reconstruction methodology (PSF ± TOF_PET1/OSEM_PET2 or OSEM _PET1/PSF ± TOF_PET2) led, respectively, to 11/61 (18.0%) and 10/61 (16.4%) PERCIST classification discordances and to 17/61 (28.9%) and 19/61 (31.1%) EORTC classification discordances. An agreement was better for these scenarios with application of the propriety filter, with kappa values of 1.00 and 0.95 compared to 0.75 and 0.77 for PERCIST and kappa values of 0.93 and 0.95 compared to 0.61 and 0.55 for EORTC, respectively.

Conclusion

PERCIST classification is less sensitive to reconstruction algorithm-dependent variability than EORTC classification but harmonizing SULs within the EARL program is equally effective with either.

Electronic supplementary material

The online version of this article (doi:10.1186/s40658-017-0185-4) contains supplementary material, which is available to authorized users.

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

Eighteen years ago, the EORTC PET criteria standardized for the first time response assessment by FDG PET. Response assessment by FDG PET has been further developed and refined by PERCIST (PET response criteria in solid tumors). This review describes the data underlying these two systems for assessing tumor response on FDG PET/CT. It also summarizes recent clinical studies that have compared EORTC criteria and PERCIST with each other as well as with the anatomically based "response criteria in solid tumors" (RECIST). These studies have shown that response assessment by EORTC criteria and PERCIST leads to very similar response classifications. In contrast, there are significant differences between response assessment by PERCIST and RECIST. Preliminary data also suggest that response assessment by PERCIST is better correlated with patient outcome and may be a better predictor for the effectiveness of new anti-cancer therapies than RECIST. If correct, this could have a significant impact on oncologic drug development. However, confirmation of the better predictive value of response assessment by PERCIST by data from randomized trials is still lacking.

Defining Clinical Response Criteria and Early Response Criteria for Precision Oncology: Current State-of-the-Art and Future Perspectives

In this era of precision oncology, there has been an exponential growth in the armamentarium of genomically targeted therapies and immunotherapies. Evaluating early responses to precision therapy is essential for “go” versus “no go” decisions for these molecularly targeted drugs and agents that arm the immune system. Many different response assessment criteria exist for use in solid tumors and lymphomas. We reviewed the literature using the Medline/PubMed database for keywords “response assessment” and various known response assessment criteria published up to 2016. In this article we review the commonly used response assessment criteria. We present a decision tree to facilitate selection of appropriate criteria. We also suggest methods for standardization of various response assessment criteria. The relevant response assessment criteria were further studied for rational of development, key features, proposed use and acceptance by various entities. We also discuss early response evaluation and provide specific case studies of early response to targeted therapy. With high-throughput, advanced computing programs and digital data-mining it is now possible to acquire vast amount of high quality imaging data opening up a new field of “omics in radiology”—radiomics that complements genomics for personalized medicine. Radiomics is rapidly evolving and is still in the research arena. This cutting-edge technology is poised to move soon to the mainstream clinical arena. Novel agents with new mechanisms of action require advanced molecular imaging as imaging biomarkers. There is an urgent need for development of standardized early response assessment criteria for evaluation of response to precision therapy.

18F-FDG PET as novel imaging biomarker for disease progression after ablation therapy in colorectal liver metastases

Purpose

Recurrent disease following thermal ablation therapy is a frequently reported problem. Preoperative identification of patients with high risk of recurrent disease might enable individualized treatment based on patients’ risk profile. The aim of the present work was to investigate the role of metabolic parameters derived from the pre-ablation ¹⁸F-FDG PET/CT as imaging biomarkers for recurrent disease in patients with colorectal liver metastases (CLM).

Methods

Included in this retrospective study were all consecutive patients with CLM treated with percutaneous or open thermal ablation therapy who had a pre-treatment baseline ¹⁸F-FDG PET/CT available. Multivariable cox regression for survival analysis was performed using different models for the metabolic parameters (SUL_peak, SUL_mean, SUL_max, partial volume corrected SUL_mean (cSUL_mean), and total lesion glycolysis (TLG)) corrected for tumour and procedure characteristics. The study endpoints were defined as local tumour progression free survival (LTP-FS), new intrahepatic recurrence free survival (NHR-FS) and extrahepatic recurrence free survival (EHR-FS). Clinical and imaging follow-up data was used as the reference standard.

Results

Fifty-four patients with 90 lesions were selected. Univariable cox regression analysis resulted in eight models. Multivariable analysis revealed that after adjusting for lesion size and the approach of the procedure, none of the metabolic parameters were associated with LTP-FS or EHR-FS. Percutaneous approach was significantly associated with a shorter LTP-FS. It was demonstrated that lower values of SUL_peak, SUL_max, SUL_mean , and cSUL_mean are associated with a significant better NHR-FS, independent of the lesion size and number and prior chemotherapy.

Conclusion

We found no association between the metabolic parameters on pre-ablation ¹⁸F-FDG PET/CT and the LTP-FS. However, low values of the metabolic parameters were significantly associated with improved NHR-FS. The clinical implication of these findings might be the identification of high-risk patients who might benefit most from adjuvant or combined treatment strategies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-017-3637-0) contains supplementary material, which is available to authorized users.

Effect of hyperglycemia on brain and liver 18F-FDG standardized uptake value (FDG SUV) measured by quantitative positron emission tomography (PET) imaging

PURPOSE

Blood glucose is routinely measured prior to ¹⁸F-fluorodeoxyglucose (FDG) administration in positron emission tomography (PET) imaging to identify hyperglycemia that may affect image quality. In this study we explore the effects of blood glucose levels upon semi-quantitative standardized uptake value (SUV) measurements of target organs and tissues of interest and in particular address the relationship of blood glucose to FDG accumulation in the brain and liver.

METHODS

436 FDG PET/CT consecutive studies performed for oncology staging in 229 patients (226 male) at the Ann Arbor Veterans Administration Healthcare System were reviewed. All patients had blood glucose measured (112.4±34.1mg/dL) prior to injection of 466.2±51.8MBq (12.6±1.4mCi) of FDG. SUV measurements of brain, aortic arch blood-pool, liver, and spleen were obtained at 64.5±10.2min' post-injection.

RESULTS

We found a negative inverse relationship of brain SUV with increasing plasma glucose, levels for both absolute and normalized (either to blood-pool or liver) values. Higher blood glucose levels had a mild effect upon liver and blood-pool SUV. By contrast, spleen SUV was independent of blood glucose, but demonstrated the greatest variability (deviation on linear regression). In contrast to other tissues, liver and spleen SUV normalized to blood-pool SUV were not dependent upon blood glucose levels.

CONCLUSION

The effects of hyperglycemia upon FDG uptake in brain and liver, over a range of blood glucose values generally considered acceptable for clinical PET imaging, may have measurable effects on semi-quantitative image analysis.

A Promising Future for Prostate Cancer Diagnostics

It has been estimated that globally there is a death attributable to prostate cancer every four minutes. As life expectancy in all world regions increases, so too incidence of this disease of the ageing male will increase. For many men diagnosis occurs after presentation with symptoms of altered urinary dynamics. Unfortunately, these changes, whilst also associated with benign disease, are evident quite late in the aetiology of prostate cancer. Early detection provides for better management and prognosis. This Special Issue provides an up to date view of the advances made towards early diagnosis and prognosis. It provides reviews of advanced imaging techniques (e.g., multiparametric MRI and protocols), and of biomaterials and molecular biomarkers currently being explored (e.g., microRNAs, proteomics) and the technologies that are revolutionizing this field. It describes the multi-disciplinary approaches that are essential to inexpensive, deliverable and accurate platforms for prostate cancer diagnostics.

The predictive value of 18F-FDG PET-CT for assessing the clinical outcomes in locally advanced NSCLC patients after a new induction treatment: low-dose fractionated radiotherapy with concurrent chemotherapy

Background

Patients with locally advanced non-small-cell lung cancer (LA-NSCLC) have poor prognosis despite several multimodal approaches. Recently, low-dose fractionated radiotherapy concurrent to the induction chemotherapy (IC-LDRT) has been proposed to further improve the effects of chemotherapy and prognosis. Until now, the predictive value of metabolic response after IC-LDRT has not yet been investigated. Aim: to evaluate whether the early metabolic response, assessed by ¹⁸F-fluoro-deoxyglucose positron emission-computed tomography (¹⁸F-FDG PET-CT), could predict the prognosis in LA-NSCLC patients treated with a multimodal approach, including IC-LDRT.

Methods

Forty-four consecutive patients (35males, mean age: 66 ± 7.8 years) with stage IIIA/IIIB NSCLC were retrospectively evaluated. Forty-four patients underwent IC-LDRT (2 cycles of chemotherapy, 40 cGy twice daily), 26/44 neo-adjuvant chemo-radiotherapy (CCRT: 50.4Gy), and 20/44 surgery. ¹⁸F-FDG PET-CT was performed before (baseline), after IC-LDRT (early) and after CCRT (final), applying PET response criteria in solid tumours (PERCIST). Patients with complete/partial metabolic response were classified as responders; patients with stable/progressive disease as non-responders. Progression free survival (PFS) and overall survival (OS) were assessed using Kaplan-Meyer analysis; the relationship between clinical factors and survivals were assessed using uni-multivariate regression analysis.

Results

Forty-four out of 44, 42/44 and 23/42 patients underwent baseline, early and final PET-CT, respectively. SUL_peak of primary tumour and lymph-node significantly (p = 0.004, p = 0.0002, respectively) decreased after IC-LDRT with a further reduction after CCRT (p = 0.0006, p = 0.02, respectively). At early PET-CT, 20/42 (47.6%) patients were classified as responders, 22/42 (52.3%) as non-responders. At final PET-CT, 19/23 patients were classified as responders (12 responders and 7 non-responders at early PET-CT), and 4/23 as non-responders (all non-responders at early PET-CT). Early responders had better PFS and OS than early non-responders (p ≤ 0.01). Early metabolic response was predictive factor for loco-regional, distant and global PFS (p = 0.02, p = 0.01, p = 0.005, respectively); surgery for loco-regional and global PFS (p = 0.03, p = 0.009, respectively).

Conclusions

In LA-NSCLC patients, ¹⁸F-FDG metabolic response assessed after only two cycles of IC-LDRT predicts the prognosis. The early evaluation of metabolic changes could allow to personalize therapy. This multimodality approach, including both low-dose radiotherapy that increases the effects of induction chemotherapy, and surgery that removes the disease, improved clinical outcomes. Further prospective investigation of this new induction approach is warranted.

Does PET SUV Harmonization Affect PERCIST Response Classification?

Pre- and posttreatment PET comparative scans should ideally be obtained with identical acquisition and processing, but this is often impractical. The degree to which differing protocols affect PERCIST classification is unclear. This study evaluates the consistency of PERCIST classification across different reconstruction algorithms and whether a proprietary software tool can harmonize SUV estimation sufficiently to provide consistent response classification.

METHODS

Eighty-six patients with non-small cell lung cancer, colorectal liver metastases, or metastatic melanoma who were scanned for therapy monitoring purposes were prospectively recruited in this multicenter trial. Pre- and posttreatment PET scans were acquired in protocols compliant with the Society of Nuclear Medicine and Molecular Imaging and the European Association of Nuclear Medicine (EANM) acquisition guidelines and were reconstructed with a point spread function (PSF) or PSF + time-of-flight (TOF) for optimal tumor detection and also with standardized ordered-subset expectation maximization (OSEM) known to fulfill EANM harmonizing standards. After reconstruction, a proprietary software solution was applied to the PSF ± TOF data (PSF ± TOF.EQ) to harmonize SUVs with the OSEM values. The impact of differing reconstructions on PERCIST classification was evaluated.

RESULTS

For the OSEM_PET1/OSEM_PET2 (OSEM reconstruction for pre- and posttherapeutic PET, respectively) scenario, which was taken as the reference standard, the change in SUL was -41% ± 25 and +56% ± 62 in the groups of tumors showing a decrease and an increase in ¹⁸F-FDG uptake, respectively. The use of PSF reconstruction affected classification of tumor response. For example, taking the PSF ± TOF_PET1/OSEM_PET2 scenario increased the apparent reduction in SUL in responding tumors (-48% ± 22) but reduced the apparent increase in SUL in progressing tumors (+37% ± 43), as compared with the OSEM_PET1/OSEM_PET2 scenario. As a result, variation in reconstruction methodology (PSF ± TOF_PET1/OSEM_PET2 or OSEM _PET1/PSF ± TOF_PET2) led to 13 of 86 (15%) and 17 of 86 (20%) PERCIST classification discordances, respectively. Agreement was better for these scenarios with application of the propriety filter, with κ values of 1 and 0.95 compared with 0.79 and 0.72, respectively.

CONCLUSION

Reconstruction algorithm-dependent variability in PERCIST classification is a significant issue but can be overcome by harmonizing SULs using a proprietary software tool.

Comparison of RECIST, EORTC criteria and PERCIST for evaluation of early response to chemotherapy in patients with non-small-cell lung cancer

PURPOSE

To compare the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, the European Organization for Research and Treatment of Cancer (EORTC) criteria and the Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) 1.0 using PET volume computer-assisted reading (PET VCAR) for response evaluation in patients with advanced non-small-cell lung cancer (NSCLC) treated with chemotherapy.

METHODS

A total of 35 patients with NSCLC were included in this prospective study. All patients received standard chemotherapy and underwent (18)F-FDG PET/CT scans before and after treatment. With the assistance of PET VCAR, the chemotherapeutic responses were evaluated according to the RECIST 1.1, EORTC criteria and PERCIST 1.0. Concordance among these protocols was assessed using Cohen's κ coefficient and Wilcoxon's signed-ranks test. Progression-free survival (PFS) was calculated using the Kaplan-Meier test.

RESULTS

RECIST 1.1 and EORTC response classifications were discordant in 20 patients (57.1 %; κ = 0.194, P < 0.05), and RECIST 1.1 and PERCIST 1.0 classifications were discordant in 22 patients (62.9 %; κ = 0.139, P < 0.05). EORTC and PERCIST 1.0 classifications were discordant in only 4 patients (11.4 %), resulting in better concordance (κ = 0.804, P > 0.05). Patients with a partial remission according to RECIST 1.1 had significantly longer PFS (P < 0.001) than patients with progressive disease, but not significantly longer than patients with stable disease (P = 0.855). According to both the EORTC criteria and PERCIST 1.0, patients with a partial metabolic response had a significantly longer PFS than those with stable metabolic disease and those with progressive metabolic disease (P = 0.020 and P < 0.001, respectively, for EORTC; both P < 0.001 for PERCIST 1.0).

CONCLUSION

EORTC criteria and PERCIST 1.0 are more sensitive and accurate than RECIST 1.1 for the detection of an early therapeutic response to chemotherapy in patients with NSCLC. Although EORTC criteria and PERCIST 1.0 showed similar results, PERCIST 1.0 is preferred because detailed and unambiguous definitions are given. We also found that response evaluations with PERCIST 1.0 using a single lesion and multiple lesions gave similar response classifications.

Quantitative Evaluation of Therapeutic Response by FDG-PET-CT in Metastatic Breast Cancer

PURPOSE

To assess the therapeutic response for metastatic breast cancer with (18)F-FDG position emission tomography (PET), this retrospective study aims to compare the performance of six different metabolic metrics with PERCIST, PERCIST with optimal thresholds, and an image-based parametric approach.

METHODS

Thirty-six metastatic breast cancer patients underwent 128 PET scans and 123 lesions were identified. In a per-lesion and per-patient analysis, the performance of six metrics: maximum standardized uptake value (SUVmax), SUVpeak, standardized added metabolic activity (SAM), SUVmean, metabolic volume (MV), total lesion glycolysis (TLG), and a parametric approach (SULTAN) were determined and compared to the gold standard (defined by clinical assessment and biological and conventional imaging according RECIST 1.1). The evaluation was performed using PERCIST thresholds (for per-patient analysis only) and optimal thresholds (determined by the Youden criterion from the receiver operating characteristic curves).

RESULTS

In the per-lesion analysis, 210 pairs of lesion evolutions were studied. Using the optimal thresholds, SUVmax, SUVpeak, SUVmean, SAM, and TLG were significantly correlated with the gold standard. SUVmax, SUVpeak, and SUVmean reached the best sensitivity (91, 88, and 83%, respectively), specificity (93, 95, and 97%, respectively), and negative predictive value (NPV, 90, 88, and 83%, respectively). For the per--patient analysis, 79 pairs of PET were studied. The optimal thresholds compared to the PERCIST threshold did not improve performance for SUVmax, SUVpeak, and SUVmean. Only SUVmax, SUVpeak, SUVmean, and TLG were correlated with the gold standard. SULTAN also performed equally: 83% sensitivity, 88% specificity, and NPV 86%.

CONCLUSION

This study showed that SUVmax and SUVpeak were the best parameters for PET evaluation of metastatic breast cancer lesions. Parametric imaging is helpful in evaluating serial studies.

Response Assessment Criteria and Their Applications in Lymphoma: Part 1

The effectiveness of cancer therapy, both in individual patients and across populations, requires a systematic and reproducible method for evaluating response to treatment. Early efforts to meet this need resulted in the creation of numerous guidelines for quantifying posttherapy changes in disease extent, both anatomically and metabolically. Over the past few years, criteria for disease response classification have been developed for specific cancer histologies. To date, the spectrum of disease broadly referred to as lymphoma is perhaps the most common for which disease response classification is used. This review article provides an overview of the existing response assessment criteria for lymphoma and highlights their respective methodologies and validities. Concerns over the technical complexity and arbitrary thresholds of many of these criteria, which have impeded the long-standing endeavor of standardizing response assessment, are also discussed.

The Impact That Number of Analyzed Metastatic Breast Cancer Lesions Has on Response Assessment by 18F-FDG PET/CT Using PERCIST

The PET Response Criteria in Solid Tumors (PERCIST) are not specific regarding the number of lesions that should be analyzed per patient. This study evaluated how the number of analyzed lesions affects response assessment in metastatic breast cancer.

METHODS

In 60 patients, response was assessed by the change in SUVpeak, normalized to lean body mass, of the most (18)F-FDG-avid lesion (PERCIST 1) and by the change in the sum of normalized SUVpeak for up to 5 lesions (PERCIST 5). The correlation between response by PERCIST and progression-free and disease-specific survival was evaluated.

RESULTS

In responders and nonresponders, the respective progression-free survival at 2 y was 37.26% and 6.43% for PERCIST 1 (P < 0.0001) and 33.65% and 7.14% for PERCIST 5 (P < 0.0001) and the respective disease-specific survival at 4 y was 58.96% and 25.44% for PERCIST 1 (P < 0.012) and 59.12% vs 20.01% for PERCIST 5 (P < 0.002).

CONCLUSION

The number of analyzed lesions does not appear to have a major impact on the prognostic value of response assessment with (18)F-FDG PET/CT in metastatic breast cancer.

Predictive and prognostic value of FDG-PET/CT imaging and different response evaluation criteria after primary systemic therapy of breast cancer

OBJECTIVES

(1) To predict pathological complete remission (pCR) and survival after primary systemic therapy (PST) in patients diagnosed with breast cancer by using two different PET/CT based scores: a simplified PERCIST-based PET/CT score (Method 1) and a combined PET/CT score supplemented with the morphological results of the RECIST system (Method 2) and (2) to assess the effect of different breast carcinoma subtypes on tumor response and its evaluation.

METHODS

Eighty-eight patients were enrolled in the study who underwent PET/CT imaging before and after PST. PET/CTs were evaluated by changes in maximum Standardized Uptake Value (SUVmax) and tumor size. Method 1 and 2 were applied to predict pathological complete remission (pCR). Kaplan-Meier analyses for survival were performed. Classification into biological subtypes was performed based on the pre-therapeutic tumor characteristics.

RESULTS

A total of 30/88 patients showed pCR (34.1 %). Comparing pCR/non-pCR patient groups, significant differences were detected by changes in SUVmax (p < 0.001) and tumor size (p < 0.001) regarding the primary breast lesions. To predict pCR, Method 2 had higher sensitivity (72.4 % vs. 44.8 %) and negative predictive value (57.9 % vs. 45.8 %) with lower false negativity rate (16 vs. 32) than Method 1. pCR rate was higher in Her2-positive and triple negative tumors. Despite the significant differences detected between the biological subtypes regarding changes in primary tumor SUVmax (p = 0.007) and size (p = 0.015), the subtypes only had significant impact on response evaluation with Method 2 and not with Method 1. In our study, neither clinical nor pathological CR were predictors of longer progression-free survival.

CONCLUSIONS

Our results suggest that combined PET/CT criteria are more predictive of pCR. The effect of biological subtypes is significant on pCR rate as well as on the changes in FDG-uptake and morphological tumor response. Response evaluation with combined criteria was also able to reflect the differences between the biological behavior of breast tumor subtypes.

Usefulness of standardized uptake value normalized by individual CT-based lean body mass in application of PET response criteria in solid tumors (PERCIST)

Our aim in this study was to verify the usefulness of the standardized uptake value (SUV) normalized by individual CT-based lean body mass (LBMCT) in application of PET response criteria in solid tumors (PERCIST).We retrospectively investigated 14 patients (4 male and 10 female) with malignant lymphoma who were undergoing chemotherapy. (18)F-FDG PET/CT examinations were performed before and after chemotherapy. The LBMCT was calculated by estimation of fat weight from CT data (from skull base to pelvis). The mean ± standard deviation (SD) and the Bland-Altman plot were used for comparison among body weight, LBMCT, and LBM derived from a predictive equation (LBMPE). Indices for FDG uptake in the liver were: SUV, SUV based on LBMPE (SULPE), and SUV based on LBMCT (SULCT). Overall differences between the uptake values were analyzed by one-way ANOVA. If the ANOVA showed significance, differences between uptake values were investigated further by use of the Tukey-Kramer test. The mean values of body weight, LBMPE, and LBMCT were: 55.4 ± 14.9 (39.0-112.0), 43.0 ± 10.5 (31.3-75.2), and 35.3 ± 9.8 (23.4-75.8) kg, respectively. There was a wide dispersion between LBMPE and LBMCT (differences, 7.6 ± 3.6 kg; 95 % CI, 6.42-8.85). LBMPE was higher than LBMCT in all the cases except in Case 11. The mean uptake values significantly differed among SUV, SULPE, and SULCT (F = 68.3, p < 0.05). Whereas SULPE deviated from PERCIST criteria in seven patients, SULCT satisfied the criteria except in one case. These results suggest that liver SULCT is useful for application of PERCIST.

Positron emission tomography response criteria in solid tumours criteria for quantitative analysis of [18F]-fluorodeoxyglucose positron emission tomography with integrated computed tomography for treatment response assessment in metastasised solid tumours: All that glitters is not gold

For solid tumours, quantitative analysis of [(18)F]-fluorodeoxyglucose positron emission tomography with integrated computed tomography potentially can have significant value in early response assessment and thereby discrimination between responders and non-responders at an early stage of treatment. Standardised strategies for this analysis have been proposed, and the positron emission tomography response criteria in solid tumours (PERCIST) criteria can be regarded as the current standard to perform quantitative analysis in a research setting, yet is not implemented in daily practice. However, several exceptions and limitations limit the feasibility of PERCIST criteria. In this article, we point out dilemmas that arise when applying proposed criteria like PERCIST on an expansive set of patients with metastasised solid tumours. Clinicians and scientists should be aware of these limitations to prevent that methodological issues impede successful introduction of research data into clinical practice. Therefore, to deliver on the high potential of quantitative imaging, consensus should be reached on a standardised, feasible and clinically useful analysis methodology. This methodology should be applicable in the majority of patients, tumour types and treatments.

The role of (18)F-FDG positron emission tomography in the follow-up of liver tumors treated with (90)Yttrium radioembolization

In the last years, radioembolization (RE) has emerged as a novel technique for the treatment of malignant hepatic lesions using (90)Y embedded in spheres, which are infused directly into the hepatic arterial circulation. (90)Y-spheres, once implanted in liver, can release a significant radiation burden to neoplastic cells with a relative low dose to normal parenchyma. (90)Y RE results as a combination of embolization and radiation therapy, thus the standard radiologic follow up modalities may be not sufficiently accurate to assess tumor response to treatment. (18)Fluoro-deoxyglucose Positron Emission Tomography ((18)F-FDG PET) detects glucose uptake and metabolic activity in tumor cells. (18)F-FDG PET has become a well established diagnostic tool in many oncological scenarios. Furthermore, PET response criteria (PERCIST) have been recently introduced to categorize the metabolic response to therapy of cancer patients. Several semiquantitative parameters, such as SUVmax and its changes, the Functional Tumor Volume and the Total Lesion Glycolysis can be useful to accurately assess tumor changes after therapy. The purpose of this article is to present the literature on the role of (18)F-FDG PET in the evaluation of patients with primary and secondary liver tumors treated with (90)Y RE.

Assessment of treatment response using PET

This article reviews the major treatment response evaluation guidelines in the domain of cancer imaging and how the potential of PET imaging, particularly with fluorodeoxyglucose, is increasingly explored in this important aspect of cancer management. Certain disease-specific response criteria (such as in lymphoma) are also reviewed with emphasis on the changes made over time and the main areas of concern in PET interpretation. The major present clinical applications are illustrated and potential new areas are discussed with regard to clinical applications in the future. Finally, the evolving role of newer and novel PET metrics, which hold promise in treatment response evaluation, is illustrated with examples.

Early detection of disease progression after palliative chemotherapy in NSCLC patients by (18)F-FDG-PET

AIM

We investigated whether 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is capable of detecting renewed disease progression earlier than computed tomography (CT) in patients with inoperable non-small cell lung cancer (NSCLC) who have undergone chemotherapy as part of a palliative treatment plan.

PATIENTS, METHODS

18 patients were studied retrospectively. Three FDG-PET/CT scans for initial and follow-up diagnostic purposes were evaluated. Palliative chemotherapy was administered between the first FDG-PET/CT scan (t0) and the second (t1), followed by a treatment-free interval between the second FDG-PET/CT scan (t1) and the third (t2). Maximum standardized uptake values (SUVmax) and largest diameters of lesions were determined for PET scans and the corresponding CTs. Lesion-based and patient-based assessments were performed, as were assessments according to RECIST/PERCIST.

RESULTS

82 lesions were identified in 18 patients. In interval t1-t2, the increase in diameter in the lesion-based evaluation was 5.0% (non-significant), while the patient-based evaluation showed a non-significant reduction of 2.8%. Considering PET, both the lesion-based and patient-based evaluations found a significant increase in SUVmax by a median of 30.4 % and 45.8 %, respectively. PERCIST criteria at time point t2 identified ten more patients with progression than did RECIST.

CONCLUSION

In patients with NSCLC, renewed progression during the treatment-free interval after palliative chemotherapy can be detected earlier with PET than with CT. Thus, FDG-PET appears to be a useful diagnostic imaging procedure regarding this aspect. Its clinical relevance should be investigated in further studies.

CT versus FDG-PET/CT response evaluation in patients with metastatic colorectal cancer treated with irinotecan and cetuximab

We compared morphologic computed tomography (CT)-based to metabolic fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT-based response evaluation in patients with metastatic colorectal cancer and correlated the findings with survival and KRAS status. From 2006 to 2009, patients were included in a phase II trial and treated with cetuximab and irinotecan every second week. They underwent FDG-PET/CT examination at baseline and after every fourth treatment cycle. Response evaluation was performed prospectively according to Response Evaluation Criteria in Solid Tumors (RECIST 1.0) and retrospectively according to Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). Best overall responses were registered. Sixty-one patients were eligible for response evaluation. Partial response (PR) rate was 18%, stable disease (SD) rate 64%, and progressive disease (PD) rate 18%. Partial metabolic response (PMR) rate was 56%, stable metabolic disease rate 33%, and progressive metabolic disease (PMD) rate 11%. Response agreement was poor, κ-coefficient 0.19. Hazard ratio for overall survival for responders (PR/PMR) versus nonresponders (PD/PMD) was higher for CT- than for FDG-PET/CT evaluation. Within patients with KRAS mutations, none had PR but 44% had PMR. In conclusion, morphologic and metabolic response agreement was poor primarily because a large part of the patients shifted from SD with CT evaluation to PMR when evaluated with FDG-PET/CT. Furthermore, a larger fraction of the patients with KRAS mutations had a metabolic treatment response.

Comparison of EORTC criteria and PERCIST for PET/CT response evaluation of patients with metastatic colorectal cancer treated with irinotecan and cetuximab

The study aim was to compare European Organization for Research and Treatment of Cancer (EORTC) criteria with PET Response Criteria in Solid Tumors (PERCIST) for response evaluation of patients with metastatic colorectal cancer treated with a combination of the chemotherapeutic drug irinotecan and the monoclonal antibody cetuximab.

METHODS

From 2006 to 2009, patients with metastatic colorectal cancer were prospectively included in a phase II trial evaluating the combination of irinotecan and cetuximab every second week, as third-line treatment. (18)F-FDG PET/CT was performed between 1 and 14 d before the first treatment and after every fourth treatment cycle until progression was identified by CT with Response Evaluation Criteria in Solid Tumors (RECIST). Response evaluation with (18)F-FDG PET/CT was retrospectively performed according to both EORTC criteria and PERCIST, classifying the patients into 4 response categories: complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD). Individual best overall metabolic response (BOmR) was registered with both sets of criteria, as well as survival within response categories, and compared.

RESULTS

A total of 61 patients and 203 PET/CT scans were eligible for response evaluation. With EORTC criteria, 38 had PMR, 16 had SMD, and 7 had PMD as their BOmR. With PERCIST, 34 had PMR, 20 had SMD, and 7 had PMD as their BOmR. None of the patients had CMR. There was agreement between EORTC criteria and PERCIST in 87% of the patients, and the corresponding κ-coefficient was 0.76. Disagreements were confined to PMR and SMD. Median overall survival (OS) in months with EORTC criteria was 14.2 in the PMR group and 7.2 in the combined SMD + PMD group. With PERCIST, it was 14.5 in the PMR group and 7.9 in the SMD + PMD group.

CONCLUSION

Response evaluation with EORTC criteria and PERCIST gave similar responses and OS outcomes with good agreement on BOmR (κ-coefficient, 0.76) and similar significant differences in median OS between response groups. Compared with EORTC criteria, we find PERCIST unambiguous because of clear definitions and therefore more straightforward to use.