18F-FDG PET/CT in Lymphoma: Has Imaging-Directed Personalized Medicine Become a Reality?

Positron emission tomography to detect bone marrow involvement for patients with follicular lymphoma: a systematic review and meta-analysis

Detection of bone marrow involvement (BMI) for patients with follicular lymphoma (FL) is of great significance for staging and treatment. The clinical value of positron emission tomography/computed tomography (PET/CT) in assessing BMI is still under debate and investigation. PubMed, Embase, Web of Science, and Cochrane Library databases were systematically searched to identify studies evaluating PET/CT in detecting BMI in FL patients. Data extraction and quality evaluation were independently conducted by two reviewers, and nine eligible studies were selected as final quantitative analysis. Nine studies comprising 1119 FL patients were included. The pooled sensitivity was 0.67 (95% CI, 0.38-0.87), and the pooled specificity was 0.82 (95% CI, 0.75-0.87). The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 3.7 (95% CI, 2.1-6.3), 0.4 (95% CI, 0.18-0.91), and 9 (95% CI, 2-33), respectively. The area under the curve of PET/CT to detect BMI in FL patients was 0.83 (95% CI, 0.8-0.86). Current evidence suggests that PET/CT cannot replace bone marrow biopsy to detect BMI, but it is still of partial clinical significance for the prognosis of patients with follicular lymphoma.

Metabolic tumor parameters complement clinicopathological factors in prognosticating advanced stage Hodgkin Lymphoma

Objectives

Advanced Hodgkin Lymphoma has a higher probability of relapse and recurrence. Classical clinicopathological parameters including the International Prognostic Score (IPS) have not been reliable in predicting prognosis or tailoring treatment. Since FDG PET/CT is the standard of care in staging Hodgkin Lymphoma, this study attempted to evaluate the clinical utility of baseline metabolic tumor parameters in a cohort of advanced Hodgkin lymphoma (stage III and IV).

Methods

Histology-proven advanced Hodgkin Patients presenting to our institute between 2012-2016 and treated with chemo-radiotherapy (ABVD / AEVD) were followed up till 2019. Quantitative PET/CT and clinicopathological parameters were used to estimate the Event Free Survival (EFS) in 100 patients. Kaplan-Meier method with log-rank test was used to compare the survival times of prognostic factors.

Results

At a median follow-up of 48.83 months (IQR:33.31-63.05 months), the five-year-EFS was 81%. Of the 100 patients, 16 had relapsed (16%) and none died at the last follow-up. On Univariate analysis, among non-PET parameters bulky disease (P=0.03) and B-symptoms (P=0.04) were significant while among PET/CT parameters SUV_max (p=0.001), SUV_mean (P=0.002), WBMTV2.5 (P<0.001), WBMTV41% (P<0.001), WBTLG2.5 (P<0.001) and WBTLG41% (P <0.001) predicted poorer EFS. 5-year EFS for patients with low WBMTV2.5 [<1038.3 cm3] was 89% and 35% for patients with high WBMTV2.5 [≥1038.3 cm3] (p <0.001). In a multivariate model, only WBMTV2.5 (P=0.03) independently predicted poorer EFS.

Conclusion

PET-based metabolic parameter (WBMTV2.5) was able to prognosticate and complement the classical clinical prognostic factors in advanced Hodgkin Lymphoma. This parameter could have a surrogate value for prognosticating advanced Hodgkin lymphoma. Better prognostication at baseline translates to tailored or risk-modified treatment and hence higher survival.

The Prognostic Utility of 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography-Based Analyses of Metabolic Response Rates in Newly Diagnosed Diffuse Large B Cell Lymphoma Patients

Background

Roughly one third of diffuse large B cell lymphoma (DLBCL) patients experience relapsed or refractory disease, and their prognosis is unsatisfactory. It is thus important to identify patients who respond poorly to first-line treatment. Some studies have evaluated the prognostic value of interim PET-CT (iPET-CT) or end-of-treatment PET-CT (ePET-CT) in lymphoma patients, but there have been few studies exploring the prognostic value of metabolic response rates in the evaluation of DLBCL patients.

Methods

Consecutive newly diagnosed DLBCL patients were screened from March 2013 to June 2020. Patients received at least four cycles of chemotherapy, and underwent baseline, iPET-CT and ePET-CT scanning. Kaplan-Meier survival curves with log-rank tests were employed to assess survival outcomes including overall survival (OS) and progression-free survival (PFS). Independent predictors of survival were identified through univariable and multivariable Cox regression analyses.

Results

307 patients were evaluated. At the time of iPET-CT scanning, 250, 45, and 12 patients exhibited complete response (CR), partial response (PR), and stable disease (SD)/progressive disease (PD), respectively. The percentage of negative iPET-CT was 81.4% (250/307). Among 295 patients with ePET-CT, 262 (88.8%) achieved negativity and 33 (11.2%) exhibited positivity including 26 PR and 7 PD. The 2-year PFS and 2-year OS for patients with iPET-CT positivity were 50.7% and 76.5%, respectively, and were significantly shorter than those for patients with iPET-CT negativity (2-year PFS 82.7%, p&lt;0.001; 2-year OS 94.2%, p&lt;0.001). Patients with ePET-CT positivity had significant poorer 2-year PFS (48.1%) and 2-year OS (78.5%) compared with those ePET-CT negativity (2-year PFS 83.8%, p&lt;0.001; 2-year OS 94.9%, p&lt;0.001). The positivity rates on iPET-CT and ePET-CT evaluation were significantly higher in patients in the high/high-intermediate risk group compared with patients in the low/low-intermediate group. In a multivariable analysis, high/high-intermediate international prognostic index (IPI) and ePET-CT positivity were independently associated with poor PFS and OS.

Conclusions

Our results suggest that the speed of metabolic response to treatment is of limited prognostic value in newly diagnosed DLBCL patients. Patients exhibiting PR at iPET-CT evaluation should carefully consider whether to change chemotherapy regimen.

Interobserver Agreement on Automated Metabolic Tumor Volume Measurements of Deauville Score 4 and 5 Lesions at Interim 18F-FDG PET in Diffuse Large B-Cell Lymphoma

Metabolic tumor volume (MTV) on interim PET (I-PET) is a potential prognostic biomarker for diffuse large B-cell lymphoma (DLBCL). Implementation of MTV on I-PET requires a consensus on which semiautomated segmentation method delineates lesions most successfully with least user interaction. Methods used for baseline PET are not necessarily optimal for I-PET because of lower lesional SUVs at I-PET. Therefore, we aimed to evaluate which method provides the best delineation quality for Deauville score (DS) 4-5 DLBCL lesions on I-PET at the best interobserver agreement on delineation quality and, second, to assess the effect of lesional SUVmax on delineation quality and performance agreement. Methods: DS 4-5 lesions from 45 I-PET scans were delineated using 6 semiautomated methods: a fixed SUV threshold of 2.5 g/cm3, a fixed SUV threshold of 4.0 g/cm3, an adaptive threshold corrected for source-to-local background activity contrast at 50% of the SUVpeak, 41% of SUVmax per lesion, a majority vote including voxels detected by at least 2 methods, and a majority vote including voxels detected by at least 3 methods (MV3). Delineation quality per MTV was rated by 3 independent observers as acceptable or nonacceptable. For each method, observer scores on delineation quality, specific agreement, and MTV were assessed for all lesions and per category of lesional SUVmax (<5, 5-10, >10). Results: In 60 DS 4-5 lesions on I-PET, MV3 performed best, with acceptable delineation in 90% of lesions and a positive agreement of 93%. Delineation quality scores and agreement per method strongly depended on lesional SUV: the best delineation quality scores were obtained using MV3 in lesions with an SUVmax of less than 10 and using SUV4.0 in more 18F-FDG-avid lesions. Consequently, overall delineation quality and positive agreement improved by applying the most preferred method per SUV category instead of using MV3 as the single best method. The MV3- and SUV4.0-derived MTVs of lesions with an SUVmax of more than 10 were comparable after exclusion of visually failed MV3 contouring. For lesions with an SUVmax of less than 10, MTVs using different methods correlated poorly. Conclusion: On I-PET, MV3 performed best and provided the highest interobserver agreement regarding acceptable delineations of DS 4-5 DLBCL lesions. However, delineation-method preference strongly depended on lesional SUV. Therefore, we suggest exploration of an approach that identifies the optimal delineation method per lesion as a function of tumor 18F-FDG uptake characteristics, that is, SUVmax.

Excellent response to very-low-dose radiation (4 Gy) for indolent B-cell lymphomas: is 4 Gy suitable for curable patients?

Two doses of VLDRT at 2 Gy are associated with an impressive overall response rate of 90% across diverse indolent B-cell lymphomas.

Patients with early-stage, potentially[AQ4] curable disease had outcomes similar to those treated with 4 Gy as part of a novel RT strategy.

Radiotherapy plays an important role in managing highly radiosensitive, indolent non-Hodgkin lymphomas, such as follicular lymphoma and marginal zone lymphoma. Although the standard of care for localized indolent non-Hodgkin lymphomas remains 24 Gy, de-escalation to very-low-dose radiotherapy (VLDRT) of 4 Gy further reduces toxicities and duration of treatment. Use of VLDRT outside palliative indications remains controversial; however, we hypothesize that it may be sufficient for most lesions. We present the largest single-institution VLDRT experience of adult patients with follicular lymphoma or marginal zone lymphoma treated between 2005 and 2018 (299 lesions; 250 patients) using modern principles including positron emission tomography staging and involved site radiotherapy. Outcomes include best clinical or radiographic response between 1.5 and 6 months after VLDRT and cumulative incidence of local progression (LP) with death as the only competing risk. After VLDRT, the overall response rate was 90% for all treated sites, with 68% achieving complete response (CR). With a median follow-up of 2.4 years, the 2-year cumulative incidence of LP was 25% for the entire cohort and 9% after first-line treatment with VLDRT for potentially curable, localized disease. Lesion size >6 cm was associated with lower odds of attaining a CR and greater risk of LP. There was no suggestion of inferior outcomes for potentially curable lesions. Given the clinical versatility of VLDRT, we propose to implement a novel, incremental, adaptive involved site radiotherapy strategy in which patients will be treated initially with VLDRT, reserving full-dose treatment for those who are unable to attain a CR.

Assessment of cardiac tumors by 18F-FDG PET/CT imaging: Histological correlation and clinical outcomes

BACKGROUND

To evaluate the diagnostic value of 18F-FDG PET/CT in distinguishing benign versus malignant cardiac tumors as well as to assess its prognostic value.

METHODS

We analyzed 38 patients with cardiac tumors who underwent 18F-FDG PET/CT and followed for median 8.5 ± 12.5 months. SUVmax and TBRmax (maximum tumor-to-background ratio) by receiver-operating characteristic (ROC) curve analysis were used to obtain threshold for the diagnosis of malignancy as defined by histology (n = 38). Survival was assessed and correlated with the dignity of the lesions and PET parameters.

RESULTS

Optimal cut-off values indicating malignancy were as follows: SUVmax = 3.44, with 100% sensitivity and 92.9% specificity, and TBRmax = 1.55, with 95.8% sensitivity and 92.9% specificity. A significant difference of 18F-FDG uptake was observed between primary benign (n = 14, SUVmax = 2.35 ± 1.31, TBRmax = 1.05 ± 0.50) compared to primary malignant cardiac tumors (n = 11, SUVmax = 8.90 ± 4.23, TBRmax = 3.82 ± 1.44) as well as cardiac metastases and lymphoma (n = 13, SUVmax = 14.37 ± 8.05, TBRmax = 6.19 ±  3.38) (all P < .001). Survival rate was significantly lower in patients with malignant as compared to benign cardiac tumors (P < .05). Regression analysis revealed that the lesion dignity determined by the cut-off value of SUVmax was an independent predictor for death in patients with cardiac tumors (P < .05).

CONCLUSION

18F-FDG uptake in cardiac tumors can differentiate between benign and malignant cardiac tumors and predicts survival.

The effect of hypothyroidism on referential background metabolic activity on 18F-FDG PET/CT

Background

Background uptake activity is used as a reference to assess treatment response by positron emission tomography-computed tomography (PET/CT) with 2-deoxy-2-[F-18]fluoro- D-glucose (¹⁸F-FDG). Prior studies have reported decreased liver and increased muscle ¹⁸F-FDG uptake in patients with hyperthyroidism. We hypothesized that hyperthyroidism and hypothyroidism might have inverse effects on ¹⁸F-FDG uptake on PET/CT.

Methods

We recruited 36 patients with hypothyroidism and 36 age and gender-matched euthyroid participants. We recorded patient factors and background mean standardized uptake values normalized by lean body mass from the aortic blood pool, liver, and muscle. We compared the patient factors and background standardized uptake values normalized by lean body mass between hypothyroidism patients and the controls. We performed a multivariate analysis to determine the best predictors of the 3 different background standardized uptake values normalized by lean body mass.

Results

Patients with hypothyroidism had higher liver standardized uptake values normalized by lean body mass (1.77±0.33 vs. 1.58±0.26, P=0.009) and aortic blood-pool standardized uptake values normalized by lean body mass (1.21±0.22 vs. 1.11±0.20, P=0.040) than the controls. In contrast, the muscle standardized uptake value normalized by lean body mass (0.50±0.09 vs. 0.54±0.09, P=0.044) of the patients with hypothyroidism was lower than that of the controls. The serum level of thyroid-stimulating hormone was an independent predictor of liver standardized uptake values normalized by lean body mass (β=0.356, P<0.001) and blood-pool standardized uptake values normalized by lean body mass (β=0.288, P=0.001). The serum level of free triiodothyronine was an independent predictor of muscle standardized uptake values normalized by lean body mass (β=0.310, P=0.002).

Conclusions

PET/CT scans showed that hypothyroidism patients had increased liver and blood-pool ¹⁸F-FDG uptake and decreased skeletal muscle ¹⁸F-FDG uptake compared with euthyroid individuals. These alterations should be noted when a metabolic response to cancer treatment on PET/CT is determined.

Is it time for PET-guided therapy in follicular lymphoma

18F-fluorodeoxyglucose (FDG) Positron Emission Tomography-Computerised Tomography (PET) is now established as the gold-standard imaging modality for both staging and response assessment of follicular lymphoma (FL). In this Perspective, we propose where PET can, and cannot, guide clinicians in their therapeutic approach. PET at diagnosis/pre-treatment is important for staging, with greater sensitivity compared to standard CT and consequent improved outcomes in truly limited stage FL. Small datasets suggesting a high baseline SUVmax identifies de-novo histologic transformation (HT) are not corroborated by data from GALLIUM, the largest prospective study using modern therapies for FL. Nonetheless, the role of baseline quantitative PET measures requires further clarification. The median survival of patients with newly diagnosed FL is now potentially beyond 20 years. Treatment of symptomatic FL aims to achieve remission and optimise quality of life for as long as possible, with many patients achieving a "functional cure" at the cost of unwanted treatment effects. Several studies have identified that end-of-induction (EOI) PET after initial chemoimmunotherapy for patients with high tumour burden is strongly predictive of both progression-free and overall survival, and EOI PET is being evaluated as a platform for response-adapted treatment. There remain unmet needs: improving the inferior survival for patients remaining PET-positive; and quantifying the PFS and time to next treatment advantage, and additional toxicity of anti-CD20 maintenance in patients achieving complete metabolic remission. In the absence of an overall survival advantage for frontline maintenance, the question of using PET to guide our therapeutic approach is more important than ever in the context of the COVID-19 pandemic.

Prognostic Value of Baseline Radiomic Features of 18F-FDG PET in Patients with Diffuse Large B-Cell Lymphoma

This study investigates whether baseline ¹⁸F-FDG PET radiomic features can predict survival outcomes in patients with diffuse large B-cell lymphoma (DLBCL). We retrospectively enrolled 83 patients diagnosed with DLBCL who underwent ¹⁸F-FDG PET scans before treatment. The patients were divided into the training cohort (n = 58) and the validation cohort (n = 25). Eighty radiomic features were extracted from the PET images for each patient. Least absolute shrinkage and selection operator regression were used to reduce the dimensionality within radiomic features. Cox proportional hazards model was used to determine the prognostic factors for progression-free survival (PFS) and overall survival (OS). A prognostic stratification model was built in the training cohort and validated in the validation cohort using Kaplan-Meier survival analysis. In the training cohort, run length non-uniformity (RLN), extracted from a gray level run length matrix (GLRLM), was independently associated with PFS (hazard ratio (HR) = 15.7, p = 0.007) and OS (HR = 8.64, p = 0.040). The International Prognostic Index was an independent prognostic factor for OS (HR = 2.63, p = 0.049). A prognostic stratification model was devised based on both risk factors, which allowed identification of three risk groups for PFS and OS in the training (p < 0.001 and p < 0.001) and validation (p < 0.001 and p = 0.020) cohorts. Our results indicate that the baseline ¹⁸F-FDG PET radiomic feature, RLN_GLRLM, is an independent prognostic factor for survival outcomes. Furthermore, we propose a prognostic stratification model that may enable tailored therapeutic strategies for patients with DLBCL.

Early serum TARC reduction predicts prognosis in advanced-stage Hodgkin lymphoma patients treated with a PET-adapted strategy

Among patients with advanced-stage classical Hodgkin lymphoma (cHL) receiving ABVD chemotherapy, PET performed after the first two treatment cycles (PET-2) has prognostic value. However, 15% of patients with a negative PET-2 will experience treatment failure. Here we prospectively evaluated serum thymus and activation-regulated chemokine (TARC) levels, to improve risk assessment in patients treated according to HD0607 PET-driven trial (#NCT00795613). In 266 patients with available serum samples, who have agreed to participate in a sub-study for assessment of the role of TARC monitoring, serum TARC levels were measured at baseline and at time of PET-2 by commercially available ELISA test kits. The primary end-point was to evaluate the association between TARC after 2 ABVD cycles and PFS. Median TARC-2 values were significantly higher in PET-2-positive patients compared to PET-2-negative patients (P = .001), and in patients with treatment failure compared to those in continuous CR (P = .01). The 4-year PFS significantly differed between patients with TARC-2 >800 pg/mL vs ≤800 pg/mL (64% vs 86%, P = .0001). Moreover, among PET-2-negative patients, elevated TARC-2 identified those with a worse prognosis (74% vs 89%; P = .01). In multivariable analysis, TARC-2 >800 pg/mL was a significant independent predictor of PFS in the whole study population (HR 2.39, P = .004) and among the PET-2-negative patients (HR 2.49, P = .02). In conclusion, our results indicate that TARC-2 serum levels above 800 pg/mL suggest the need for a stringent follow-up in PET-2-negative patients, and the evaluation of new drugs in PET-2-positive, who will likely fail to respond to intensification with escalated BEACOPP.

Biomarker selection and imaging design in cancer: A link with biochemical pathways for imminent engineering

Malignant cells reprogram metabolic pathways to meet the demands of growth and proliferation. These altered manners of metabolism are now identified as hallmarks of cancer. Studies have revealed tumor cells alter specific pathways such as glycolysis, fatty acid synthesis and amino acid synthesis to support their proliferation. In this review, we provide a theoretical framework to understand metabolic reprogramming and the mechanisms accompanying distorted metabolism to tumor progression. How these alterations will be assisting in cancer diagnostics and advances in standard techniques in marker identification and imagining are also discussed.

Interim PET-results for prognosis in adults with Hodgkin lymphoma: a systematic review and meta-analysis of prognostic factor studies

BACKGROUND

Hodgkin lymphoma (HL) is one of the most common haematological malignancies in young adults and, with cure rates of 90%, has become curable for the majority of individuals. Positron emission tomography (PET) is an imaging tool used to monitor a tumour's metabolic activity, stage and progression. Interim PET during chemotherapy has been posited as a prognostic factor in individuals with HL to distinguish between those with a poor prognosis and those with a better prognosis. This distinction is important to inform decision-making on the clinical pathway of individuals with HL.

OBJECTIVES

To determine whether in previously untreated adults with HL receiving first-line therapy, interim PET scan results can distinguish between those with a poor prognosis and those with a better prognosis, and thereby predict survival outcomes in each group.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and conference proceedings up until April 2019. We also searched one trial registry (ClinicalTrials.gov).

SELECTION CRITERIA

We included retrospective and prospective studies evaluating interim PET scans in a minimum of 10 individuals with HL (all stages) undergoing first-line therapy. Interim PET was defined as conducted during therapy (after one, two, three or four treatment cycles). The minimum follow-up period was at least 12 months. We excluded studies if the trial design allowed treatment modification based on the interim PET scan results.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form according to the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS). Two teams of two review authors independently screened the studies, extracted data on overall survival (OS), progression-free survival (PFS) and PET-associated adverse events (AEs), assessed risk of bias (per outcome) according to the Quality in Prognosis Studies (QUIPS) tool, and assessed the certainty of the evidence (GRADE). We contacted investigators to obtain missing information and data.

MAIN RESULTS

Our literature search yielded 11,277 results. In total, we included 23 studies (99 references) with 7335 newly-diagnosed individuals with classic HL (all stages). Participants in 16 studies underwent (interim) PET combined with computed tomography (PET-CT), compared to PET only in the remaining seven studies. The standard chemotherapy regimen included ABVD (16) studies, compared to BEACOPP or other regimens (seven studies). Most studies (N = 21) conducted interim PET scans after two cycles (PET2) of chemotherapy, although PET1, PET3 and PET4 were also reported in some studies. In the meta-analyses, we used PET2 data if available as we wanted to ensure homogeneity between studies. In most studies interim PET scan results were evaluated according to the Deauville 5-point scale (N = 12). Eight studies were not included in meta-analyses due to missing information and/or data; results were reported narratively. For the remaining studies, we pooled the unadjusted hazard ratio (HR). The timing of the outcome measurement was after two or three years (the median follow-up time ranged from 22 to 65 months) in the pooled studies. Eight studies explored the independent prognostic ability of interim PET by adjusting for other established prognostic factors (e.g. disease stage, B symptoms). We did not pool the results because the multivariable analyses adjusted for a different set of factors in each study. Overall survival Twelve (out of 23) studies reported OS. Six of these were assessed as low risk of bias in all of the first four domains of QUIPS (study participation, study attrition, prognostic factor measurement and outcome measurement). The other six studies were assessed as unclear, moderate or high risk of bias in at least one of these four domains. Four studies were assessed as low risk, and eight studies as high risk of bias for the domain other prognostic factors (covariates). Nine studies were assessed as low risk, and three studies as high risk of bias for the domain 'statistical analysis and reporting'. We pooled nine studies with 1802 participants. Participants with HL who have a negative interim PET scan result probably have a large advantage in OS compared to those with a positive interim PET scan result (unadjusted HR 5.09, 95% confidence interval (CI) 2.64 to 9.81, I² = 44%, moderate-certainty evidence). In absolute values, this means that 900 out of 1000 participants with a negative interim PET scan result will probably survive longer than three years compared to 585 (95% CI 356 to 757) out of 1000 participants with a positive result. Adjusted results from two studies also indicate an independent prognostic value of interim PET scan results (moderate-certainty evidence). Progression-free survival Twenty-one studies reported PFS. Eleven out of 21 were assessed as low risk of bias in the first four domains. The remaining were assessed as unclear, moderate or high risk of bias in at least one of the four domains. Eleven studies were assessed as low risk, and ten studies as high risk of bias for the domain other prognostic factors (covariates). Eight studies were assessed as high risk, thirteen as low risk of bias for statistical analysis and reporting. We pooled 14 studies with 2079 participants. Participants who have a negative interim PET scan result may have an advantage in PFS compared to those with a positive interim PET scan result, but the evidence is very uncertain (unadjusted HR 4.90, 95% CI 3.47 to 6.90, I² = 45%, very low-certainty evidence). This means that 850 out of 1000 participants with a negative interim PET scan result may be progression-free longer than three years compared to 451 (95% CI 326 to 569) out of 1000 participants with a positive result. Adjusted results (not pooled) from eight studies also indicate that there may be an independent prognostic value of interim PET scan results (low-certainty evidence). PET-associated adverse events No study measured PET-associated AEs.

AUTHORS' CONCLUSIONS

This review provides moderate-certainty evidence that interim PET scan results predict OS, and very low-certainty evidence that interim PET scan results predict progression-free survival in treated individuals with HL. This evidence is primarily based on unadjusted data. More studies are needed to test the adjusted prognostic ability of interim PET against established prognostic factors.

Prognostic impact of interim positron emission tomography in mantle cell lymphoma patients treated with frontline R-CHOP

Although ¹⁸F‐fluorodeoxyglucose positron emission tomography (¹⁸F‐FDG PET) is commonly used for initial staging and therapeutic response evaluation in aggressive lymphomas, its prognostic utility for mantle cell lymphoma (MCL) is controversial. Therefore, we retrospectively evaluated the correlations of interim PET (iPET) and end‐of‐treatment PET (ePET) response with survival outcomes in 89 consecutive advanced MCL patients treated with frontline R‐CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone). iPET positivity was strongly associated with inferior five‐year overall survival (OS) [hazard ratio (HR) 7·84, P < 0·0001] and poor five‐year progression‐free survival (PFS) (HR 3·34, P < 0·0001). OS and PFS were more favourable in the order early metabolic responder (iPET^neg → ePET^neg), delayed responder (iPET^pos → ePET^neg), loss‐metabolic responder (iPET^neg → ePET^pos), and never‐metabolic responder (iPET^pos → ePET^pos). In the autologous haematopoietic stem cell transplantation (auto‐HSCT)‐fit subgroup, OS was more favourable in the order early metabolic responders, delayed metabolic responders, and non‐metabolic responders, with a marginal trend toward statistical significance (HR 3·41, P = 0·051), and PFS was significantly superior in early metabolic responders (HR 4·43, P = 0·002). In a group that was ineligible for auto‐HSCT, OS and PFS were significantly superior in early metabolic responders. Our results suggested that iPET is of prognostic value and an independent predictor of survival in MCL patients receiving frontline R‐CHOP. Therefore, prospective clinical trials of iPET‐guided treatment strategies for these patients are warranted.

Prognostic Value of Pretreatment Radiomic Features of 18F-FDG PET in Patients With Hodgkin Lymphoma

PURPOSE

This study investigated whether a radiomic analysis of pretreatment F-FDG PET can predict prognosis in patients with Hodgkin lymphoma (HL).

METHODS

Forty-two patients who were diagnosed as having HL and underwent pretreatment F-FDG PET scans were retrospectively enrolled. For each patient, we extracted 450 radiomic features from PET images. The prognostic significance of the clinical and radiomic features was assessed in relation to progression-free survival (PFS) and overall survival (OS). Receiver operating characteristic curve, Cox proportional hazards regression, and Kaplan-Meier analyses were performed to examine the potential independent predictors and to evaluate the predictive value.

RESULTS

Intensity nonuniformity extracted from a gray-level run-length matrix and the Ann Arbor stage were independently associated with PFS (hazard ratio [HR] = 22.8, P < 0.001; HR = 7.6, P = 0.024) and OS (HR = 14.5, P = 0.012; HR = 8.5, P = 0.048), respectively. In addition, SUV kurtosis was an independent prognosticator for PFS (HR = 6.6, P = 0.026). We devised a prognostic scoring system based on these 3 risk predictors. The proposed scoring system further improved the risk stratification of the current staging classification (P < 0.001).

CONCLUSIONS

The radiomic feature intensity nonuniformity is an independent prognostic predictor of PFS and OS in patients with HL. We devised a prognostic scoring system, which may be more beneficial for patient risk stratification in guiding therapy compared with the current Ann Arbor staging system.

Imaging for diagnosis, staging and response assessment of Hodgkin lymphoma and non-Hodgkin lymphoma

Hodgkin lymphoma and non-Hodgkin lymphoma are common malignancies in children and are now highly treatable. Imaging plays a major role in diagnosis, staging and response using conventional CT and MRI and metabolic imaging with positron emission tomography (PET)/CT and PET/MRI. Cross-sectional imaging has replaced staging laparotomy and splenectomy by demonstrating abdominal nodal groups and organ involvement. [F-18]2-fluoro-2-deoxyglucose (FDG) PET provides information on bone marrow involvement, and MRI elucidates details of cortical bone and confirmation of bone marrow involvement. The staging system for Hodgkin lymphoma is the Ann Arbor system with Cotswald modifications and is based on imaging, whereas the non-Hodgkin staging system is the St. Jude Classification by Murphy or the more recent revised International Pediatric Non-Hodgkin Lymphoma Staging System (IPNHLSS). Because all pediatric lymphomas are metabolically FDG-avid and identify all nodal, solid organ, cortical bone and bone marrow disease, staging evaluations require FDG PET as PET/CT or PET/MRI in both Hodgkin and non-Hodgkin lymphoma. Both diseases have in common issues of airway compromise at presentation demonstrated by imaging. Differences exist in that Hodgkin lymphoma has several independent poor prognostic factors seen by imaging such as large mediastinal adenopathy, Stage IV disease, systemic symptoms, pleural effusion and pericardial effusion. Non-Hodgkin lymphoma includes more organ involvement such as renal, ovary, central nervous system and skin. Early or interim PET-negative scans are a reliable indicator of improved clinical outcome and optimize risk-adapted therapy and patient management; imaging may not, however, predict who will relapse. A recent multicenter trial has concluded that it is usually sufficient for pediatric lymphoma at staging and interim assessment to evaluate children with PET imaging from skull base to mid-thigh. Various systems of assessment of presence of disease or response are used, including the Deauville visual scale, where avidity is compared to liver; Lugano, which includes size change as part of response; or quantitative PET, which uses standardized uptake values to define more accurate response. Newer methods of immunotherapy can produce challenges in FDG PET evaluation because of inflammatory changes that may not represent disease.

Interim PET-results for prognosis in adults with Hodgkin lymphoma: a systematic review and meta-analysis of prognostic factor studies

BACKGROUND

Hodgkin lymphoma (HL) is one of the most common haematological malignancies in young adults and, with cure rates of 90%, has become curable for the majority of individuals. Positron emission tomography (PET) is an imaging tool used to monitor a tumour's metabolic activity, stage and progression. Interim PET during chemotherapy has been posited as a prognostic factor in individuals with HL to distinguish between those with a poor prognosis and those with a better prognosis. This distinction is important to inform decision-making on the clinical pathway of individuals with HL.

OBJECTIVES

To determine whether in previously untreated adults with HL receiving first-line therapy, interim PET scan results can distinguish between those with a poor prognosis and those with a better prognosis, and thereby predict survival outcomes in each group.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and conference proceedings up until April 2019. We also searched one trial registry (ClinicalTrials.gov).

SELECTION CRITERIA

We included retrospective and prospective studies evaluating interim PET scans in a minimum of 10 individuals with HL (all stages) undergoing first-line therapy. Interim PET was defined as conducted during therapy (after one, two, three or four treatment cycles). The minimum follow-up period was at least 12 months. We excluded studies if the trial design allowed treatment modification based on the interim PET scan results.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form according to the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS). Two teams of two review authors independently screened the studies, extracted data on overall survival (OS), progression-free survival (PFS) and PET-associated adverse events (AEs), assessed risk of bias (per outcome) according to the Quality in Prognosis Studies (QUIPS) tool, and assessed the certainty of the evidence (GRADE). We contacted investigators to obtain missing information and data.

MAIN RESULTS

Our literature search yielded 11,277 results. In total, we included 23 studies (99 references) with 7335 newly-diagnosed individuals with classic HL (all stages).Participants in 16 studies underwent (interim) PET combined with computed tomography (PET-CT), compared to PET only in the remaining seven studies. The standard chemotherapy regimen included ABVD (16) studies, compared to BEACOPP or other regimens (seven studies). Most studies (N = 21) conducted interim PET scans after two cycles (PET2) of chemotherapy, although PET1, PET3 and PET4 were also reported in some studies. In the meta-analyses, we used PET2 data if available as we wanted to ensure homogeneity between studies. In most studies interim PET scan results were evaluated according to the Deauville 5-point scale (N = 12).Eight studies were not included in meta-analyses due to missing information and/or data; results were reported narratively. For the remaining studies, we pooled the unadjusted hazard ratio (HR). The timing of the outcome measurement was after two or three years (the median follow-up time ranged from 22 to 65 months) in the pooled studies.Eight studies explored the independent prognostic ability of interim PET by adjusting for other established prognostic factors (e.g. disease stage, B symptoms). We did not pool the results because the multivariable analyses adjusted for a different set of factors in each study.Overall survivalTwelve (out of 23) studies reported OS. Six of these were assessed as low risk of bias in all of the first four domains of QUIPS (study participation, study attrition, prognostic factor measurement and outcome measurement). The other six studies were assessed as unclear, moderate or high risk of bias in at least one of these four domains. Nine studies were assessed as high risk, and three studies as moderate risk of bias for the domain study confounding. Eight studies were assessed as low risk, and four studies as high risk of bias for the domain statistical analysis and reporting.We pooled nine studies with 1802 participants. Participants with HL who have a negative interim PET scan result probably have a large advantage in OS compared to those with a positive interim PET scan result (unadjusted HR 5.09, 95% confidence interval (CI) 2.64 to 9.81, I² = 44%, moderate-certainty evidence). In absolute values, this means that 900 out of 1000 participants with a negative interim PET scan result will probably survive longer than three years compared to 585 (95% CI 356 to 757) out of 1000 participants with a positive result.Adjusted results from two studies also indicate an independent prognostic value of interim PET scan results (moderate-certainty evidence).Progression-free survival Twenty-one studies reported PFS. Eleven out of 21 were assessed as low risk of bias in the first four domains. The remaining were assessed as unclear, moderate or high risk of bias in at least one of the four domains. Eleven studies were assessed as high risk, nine studies as moderate risk and one study as low risk of bias for study confounding. Eight studies were assessed as high risk, three as moderate risk and nine as low risk of bias for statistical analysis and reporting.We pooled 14 studies with 2079 participants. Participants who have a negative interim PET scan result may have an advantage in PFS compared to those with a positive interim PET scan result, but the evidence is very uncertain (unadjusted HR 4.90, 95% CI 3.47 to 6.90, I² = 45%, very low-certainty evidence). This means that 850 out of 1000 participants with a negative interim PET scan result may be progression-free longer than three years compared to 451 (95% CI 326 to 569) out of 1000 participants with a positive result.Adjusted results (not pooled) from eight studies also indicate that there may be an independent prognostic value of interim PET scan results (low-certainty evidence).PET-associated adverse eventsNo study measured PET-associated AEs.

AUTHORS' CONCLUSIONS

This review provides moderate-certainty evidence that interim PET scan results predict OS, and very low-certainty evidence that interim PET scan results predict progression-free survival in treated individuals with HL. This evidence is primarily based on unadjusted data. More studies are needed to test the adjusted prognostic ability of interim PET against established prognostic factors.

Is there a reliable size cut-off for splenic involvement in lymphoma? A [18F]FDG-PET controlled study

Purpose

Aim of present study was to determine whether the currently recommended 13-cm cranio-caudal diameter cut-off on CT for assessment of splenic involvement in lymphoma offers adequate sensitivity and specificity.

Materials and Methods

Patients with histologically proven lymphoma who had undergone [18F]FDG-PET/CT before therapy were included. Cranio-caudal diameters of the spleen were measured on the CT component of PET/CT, and ROC analyses with calculation of respective areas under the curve (AUC) were used to determine cut-off values of cranio-caudal measurements with their respective sensitivities and specificities, using [18F]FDG-PET as the reference standard.

Results

In 93 patients, we found a sensitivity of 74.1% and a specificity of 47% for the 13-cm splenic diameter cut-off.

Conclusions

Our results show reasonable, though far from perfect sensitivities and specificities for the currently recommend 13-cm splenic diameter cut-off.

18F-Deoxyglucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) Monitoring of Dynamic Growth Characteristics of Walker-256 Tumor Models in 3 Different Locations in Rats

BACKGROUND We explored the ideal method of establishing subcutaneous, breast, and liver tumor models using the same Walker-256 cells, and investigated the dynamic growth characteristics using ¹⁸F-deoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT), which provides basic information for choosing an experimental animal model. MATERIAL AND METHODS We established tumor models in 3 locations (subcutaneous, breast, and liver) in W256 Sprague-Dawley rats. ¹⁸F-FDG PET/CT imaging was performed from 6 days to 18 days after injecting the cells subcutaneously. Tumor volume of interest (VOI), maximum standard uptake value (SUVmax), and average standard uptake value (SUVavg) were obtained from the image. The difference of the growth characteristics in tumor volume and SUVs among the 3 groups were compared. Histopathology of the tumors was also analyzed. RESULTS The tumors in subcutaneous location grew fastest, followed by tumors located in the breast, and tumors in the liver grew slowest. Significant differences in tumor VOI (p=0.01) were observed. ¹⁸F-FDG uptake of the subcutaneous and breast tumors increased until day 10 and then decreased subsequently. ¹⁸F-FDG uptake of the liver tumor reached a peak at day 10, and necrosis peaked at day 12. The histopathology analysis results indicated that the necrosis was mainly located in the center of tumors while the viable tissues were located on the periphery. Similarly, CD 31 and Ki-67 were mainly expressed on the tumor periphery. CONCLUSIONS Subcutaneous, breast, and liver tumor models were easy to establish using Walker-256 cells. They showed fast growth and high uptake of ¹⁸F-FDG. These kinds of tumor models were optimal in evaluating anti-tumor efficacy by ¹⁸F-FDG PET/CT, but it may be essential to determine the best time-points at which to use it.

The rationale for combination therapy in patients with aggressive B-cell non-Hodgkin lymphoma: ten questions

Rituximab plus cyclophosphamide, doxorubicin, vincristine, prednisone immunochemotherapy remains standard of care for first-line treatment of diffuse large B-cell lymphoma (DLBCL). High-dose chemotherapy and stem cell transplantation is offered to most relapsing/refractory patients who respond to salvage therapy. This Q&A review evaluates recommended management strategies for second and subsequent lines of therapy in patients with DLBCL, outlining the relative efficacies of currently available options including novel agents such as ibrutinib and CAR-T cells. The combination of pixantrone and rituximab is currently under investigation as a second-line treatment for patients ineligible for stem cell transplantation, while pixantrone monotherapy is the only therapeutic option approved for multiply relapsed and refractory DLBCL beyond the second line at this time.

18F-labeled anti-human CD20 cys-diabody for same-day immunoPET in a model of aggressive B cell lymphoma in human CD20 transgenic mice

PURPOSE

Metabolic imaging using [¹⁸F]FDG is the current standard for clinical PET; however, some malignancies (e.g., indolent lymphomas) show low avidity for FDG. The majority of B cell lymphomas express CD20, making it a valuable target both for antibody-based therapy and imaging. We previously developed PET tracers based on the humanised anti-CD20 antibody obinutuzumab (GA101). Preclinical studies showed that the smallest bivalent fragment, the cys-diabody (GAcDb, 54.5 kDa) with a peak uptake at 1-2 h post-injection and a biological half-life of 2-5 h, is compatible with short-lived positron emitters such as fluorine-18 (¹⁸F, t_1/2 110 min), enabling same-day imaging.

METHODS

GAcDb was radiolabeled using amine-reactive N-succinimidyl 4-[¹⁸F]-fluorobenzoate ([¹⁸F]SFB), or thiol-reactive N-[2-(4-[¹⁸F]-fluorobenzamido)ethyl]maleimide ([¹⁸F]FBEM) for site-specific conjugation to C-terminal cysteine residues. Both tracers were used for immunoPET imaging of the B cell compartment in human CD20 transgenic mice (hCD20TM). [¹⁸F]FB-GAcDb immunoPET was further evaluated in a disseminated lymphoma (A20-hCD20) syngeneic for hCD20TM and compared to [¹⁸F]FDG PET. Tracer uptake was confirmed by ex vivo biodistribution.

RESULTS

The GAcDb was successfully ¹⁸F-radiolabeled using two different conjugation methods resulting in similar specific activities and without impairing immunoreactivity. Both tracers ([¹⁸F]FB-GAcDb and [¹⁸F]FBEM-GAcDb) specifically target human CD20-expressing B cells in transgenic mice. Fast blood clearance results in high contrast PET images as early as 1 h post injection enabling same-day imaging. [¹⁸F]FB-GAcDb immunoPET detects disseminated lymphoma disease in the context of normal tissue expression of hCD20, with comparable sensitivity as [¹⁸F]FDG PET but with added specificity for the therapeutic target.

CONCLUSIONS

[¹⁸F]FB-GAcDb and [¹⁸F]FBEM-GAcDb could monitor normal B cells and B cell malignancies non-invasively and quantitatively in vivo. In contrast to [¹⁸F]FDG PET, immunoPET provides not only information about the extent of disease but also about presence and localisation of the therapeutic target.

Metabolic Tumour Volume for Response Prediction in Advanced-Stage Hodgkin Lymphoma

Rationale: (18F)fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) for staging Hodgkin lymphoma may allow for accurate and reliable assessment of the metabolic tumour volume (MTV) as baseline risk factor. Our aim was to analyse the prognostic impact of MTV measurements, obtained by different means in advanced-stage Hodgkin lymphoma patients treated within the German Hodgkin Study Group HD18 trial. Methods: Within the German Hodgkin Study Group trial HD18, 310 patients underwent 18F-FDG PET/CT scanning for staging which was available to the central review panel for quantitative analysis. We calculated the MTV by four different thresholding methods and performed receiver operating characteristic (ROC) analysis to evaluate the potential for prediction of early response determined by PET after two cycles (PET-2) dose-escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (eBEACOPP). Logistic regression was used to evaluate its prognostic value concerning progression-free survival (PFS) and overall survival (OS). Results: All different MTV calculations used predicted PET-2 response to a moderate and comparable degree (area under the curve = 0.62-0.63, P = 0.01-0.06). With none of the measuring methods did the ROC curves point to any unique cut-off values, but indicated a wide range of possible cut-offs. However, none of the MTV measurements was prognostic for PFS (Hazard ratio 1.2-1.5, P = 0.15-0.52) or OS (Hazard ratio 1.0-1.5, P = 0.95 - 0.27). Conclusion: Baseline MTV as determined by different means, is a predictive factor for early response to eBEACOPP after two cycles. However, value as a prognostic factor after highly effective PET-2 adapted treatment strategy could not be observed.

Metabolic tumor volume changes assessed by interval 18fluorodeoxyglucose positron emission tomography-computed tomography for the prediction of complete response and survival in patients with diffuse large B-cell lymphoma

An early discrimination of survival probability is required for patients with diffuse large B cell lymphoma (DLBCL), which may identify patients that require other treatment options, for example clinical trials. To the best of our knowledge, the impact of interim evaluation with ¹⁸fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET/CT) has not yet been determined in this type of neoplasia. The aim of the present study was to determine the role of changes in metabolic tumor volume (MTV) between baseline and interim ¹⁸F-FDG PET/CT scans, following three courses of chemotherapy in order to predict complete response (CR) and overall survival (OS) in patients with DLBCL. Patients with previously untreated DLBCL who had received the standard 6–8 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone were included in the present study. A predictive model was constructed using changes in MTV and other clinical factors including age, gender, East Cooperative Oncology Group (ECOG) status, clinical stage, B symptoms, the presence of bulky disease and elevated lactate dehydrogenase levels, and data were analyzed using logistic regression analysis. In total, 50 patients with DLBCL were included in the present study. The majority of patients presented with stage III/IV disease (64%), B symptoms (72%) and bulky disease (58%). According to the International Prognostic Index score, 44% of patients were in the intermediate-high or high-risk categories for risk of relapse, and therefore considered to have poor prognosis. In total, ≥94% of patients achieving a decrease in total MTV had a 2-year OS rate of 95%, compared with the 58% OS rate of those with a suboptimal response. A multivariate model, including a change in MTV (a decrease of ≥94%), the ECOG performance status ≥2, a change in leukocyte counts and age, was used to predict CR. This model was used to define two groups according to the predicted probability of recurrence (cutoff, 0.69). The 2-year survival rates of the two groups were 95 and 59%, respectively. Analysis of changes in MTV in the interim ¹⁸F-FDG PET/CT revealed significant prognostic value for the prediction of CR and OS in patients with DLBCL.