Prognostic value of baseline, interim and end-of-treatment 18F-FDG PET/CT parameters in extranodal natural killer/T-cell lymphoma: A meta-analysis

Appropriate timing to perform an interim 18F-FDG PET/CT in patients with nasal-type extranodal natural killer/T cell lymphoma

Interim 18F-FDG PET/CT (I-PET) has a role in response evaluation and treatment guidance in patients with nasal-type extranodal natural killer/T cell lymphoma (ENKTL). However, there was no agreement on the timing of I-PET performed, after chemotherapy or after chemoradiotherapy. We aimed to find the appropriate timing for I-PET by assessing the prognostic value of I-PET in response evaluation in ENKTL patients. Two hundred and twenty-seven ENKTL patients who had undergone I-PET were retrospectively included. All patients were grouped based on their therapeutic strategy received, chemotherapy or chemoradiotherapy. The Deauville 5-point score (DS) was used to interpret the I-PET images. The hazard ratio (HR) and C-index were used to measure the discriminatory and prognostic capacities of I-PET performed at different times. One hundred and six patients underwent the I-PET after chemotherapy (chemotherapy group), while I-PET was performed after chemoradiotherapy in 121 patients (chemoradiotherapy group). Eighty-seven patients were classified as metabolic remission (DS score of 1-3), while the other 140 were classified as non-metabolic remission (DS score of 4-5) according to the Deauville criteria. There were no significant survival differences between patients in metabolic remission and in non-metabolic remission in either progression-free survival (PFS, p = 0.406) or overall survival (OS, p = 0.350). In the chemotherapy group, patients in metabolic remission had significantly superior PFS than patients in non-metabolic remission (p = 0.012). For OS, a discriminative trend was also found on the survival curve between patients in metabolic remission and in non-metabolic remission (p = 0.082). In the chemoradiotherapy group, there was no significant difference in PFS (P = 0.185) or OS (P = 0.627) between patients in metabolic remission and in non-metabolic remission. I-PET after chemotherapy yields higher discriminative power and has the ability for prognostic prediction in nasal-type ENKTL patients. I-PET after radiochemotherapy has no prognostic value. Thus, the appropriate timing for I-PET is after chemotherapy but before radiotherapy for response evaluation in nasal-type ENKTL patients.

Prognostic Value of 18F-FDG PET/CT Radiomics in Extranodal Nasal-Type NK/T Cell Lymphoma

OBJECTIVE

To investigate the prognostic utility of radiomics features extracted from 18F-fluorodeoxyglucose (FDG) PET/CT combined with clinical factors and metabolic parameters in predicting progression-free survival (PFS) and overall survival (OS) in individuals diagnosed with extranodal nasal-type NK/T cell lymphoma (ENKTCL).

MATERIALS AND METHODS

A total of 126 adults with ENKTCL who underwent 18F-FDG PET/CT examination before treatment were retrospectively included and randomly divided into training (n = 88) and validation cohorts (n = 38) at a ratio of 7:3. Least absolute shrinkage and selection operation Cox regression analysis was used to select the best radiomics features and calculate each patient's radiomics scores (RadPFS and RadOS). Kaplan-Meier curve and Log-rank test were used to compare survival between patient groups risk-stratified by the radiomics scores. Various models to predict PFS and OS were constructed, including clinical, metabolic, clinical + metabolic, and clinical + metabolic + radiomics models. The discriminative ability of each model was evaluated using Harrell's C index. The performance of each model in predicting PFS and OS for 1-, 3-, and 5-years was evaluated using the time-dependent receiver operating characteristic (ROC) curve.

RESULTS

Kaplan-Meier curve analysis demonstrated that the radiomics scores effectively identified high- and low-risk patients (all P < 0.05). Multivariable Cox analysis showed that the Ann Arbor stage, maximum standardized uptake value (SUVmax), and RadPFS were independent risk factors associated with PFS. Further, β2-microglobulin, Eastern Cooperative Oncology Group performance status score, SUVmax, and RadOS were independent risk factors for OS. The clinical + metabolic + radiomics model exhibited the greatest discriminative ability for both PFS (Harrell's C-index: 0.805 in the validation cohort) and OS (Harrell's C-index: 0.833 in the validation cohort). The time-dependent ROC analysis indicated that the clinical + metabolic + radiomics model had the best predictive performance.

CONCLUSION

The PET/CT-based clinical + metabolic + radiomics model can enhance prognostication among patients with ENKTCL and may be a non-invasive and efficient risk stratification tool for clinical practice.

18F-FDG PET/CT in extranodal natural killer/T-cell lymphoma: a comprehensive evaluation method

Extranodal NK/T-cell lymphoma (ENKTL) is an uncommon subtype of non-Hodgkin's lymphoma that is closely related to Epstein-Barr virus (EBV) infection. ENKTL exhibits distinctive clinicopathological features among lymphomas and has poor overall survival in the absence of effective treatment. The timely and accurate diagnosis of ENKTL is crucial for effective treatment and a positive prognosis. 18F-Fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) has emerged as an invaluable diagnostic modality for staging, curative effect evaluation, and prognosis analysis in ENKTL. We herein provide a comprehensive overview of the advances in the application of 18F-FDG PET/CT in patients with ENKTL.

Prognostic Value of End-of-Treatment PSMA PET/CT in Patients Treated with 177Lu-PSMA Radioligand Therapy: A Retrospective, Single-Center Analysis

Our objective was to evaluate the prognostic value of end-of-treatment prostate-specific membrane antigen (PSMA) PET/CT (PSMA-PET) in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with 177Lu-PSMA radioligand therapy (PSMA-RLT). Methods: This was a single-center retrospective study. mCRPC patients who underwent PSMA-RLT with available baseline PSMA-PET (bPET) and end-of-treatment PSMA-PET (ePET) within 6 mo of the last PSMA-RLT cycle were eligible. Overall survival (OS) and prostate-specific antigen (PSA) progression status at the time of ePET (by Prostate Cancer Clinical Trials Working Group 3 criteria) were collected. PSMA-PET tumor segmentation was performed to obtain whole-body PSMA tumor volume (PSMA-VOL) and define progressive (≥20% increase) versus nonprogressive disease. Pairs of bPET and ePET were interpreted for appearance of new lesions. Response Evaluation Criteria in PSMA-PET/CT (RECIP) 1.0 were also applied to define progressive versus nonprogressive disease. The associations between changes in PSMA-VOL, new lesions, RECIP 1.0, and PSA progression status at the time of ePET with OS were evaluated by Kaplan-Meier analysis. Results: Twenty mCRPC patients were included. The median number of treatment cycles was 3.5 (interquartile range [IQR], 2-4). The median time between bPET and cycle 1 of PSMA-RLT was 1.0 mo (IQR, 0.7-1.8 mo). The median time between the last cycle of PSMA-RLT and ePET was 1.9 mo (IQR, 1.2-3.5 mo). Twelve of 20 patients (60%) had died at the last follow-up. The median follow-up time from ePET for survivors was 31.2 mo (IQR, 6.8-40.7 mo). The median OS from ePET was 11.4 mo (IQR, 6.8-30.7 mo). Patients with new lesions on ePET had shorter OS than those without new lesions (median OS, 10.7 mo [95% CI, 9.2-12.2] vs. not reached; P = 0.002). Patients with progressive PSMA-VOL had shorter OS than those with nonprogressive PSMA-VOL (median OS, 10.7 mo [95% CI: 9.7-11.7 mo] vs. not reached; P = 0.007). Patients with progressive RECIP had shorter OS than those with nonprogressive RECIP (median OS, 10.7 mo [95% CI, 9.7-11.7 mo] vs. not reached; P = 0.007). PSA progression at the time of ePET was associated with shorter OS (median, 10.9 mo [95% CI, 9.4-12.4 mo] vs. not reached; P = 0.028). Conclusion: In this retrospective study of 20 mCRPC patients treated with PSMA-RLT, progression on ePET by the appearance of new lesions, changes in PSMA-VOL, and RECIP 1.0 was prognostic for OS. Validation in larger, prospective multicentric clinical trials is warranted.

Prognostic prediction by 18F-FDG-PET/CT parameters in patients with neuroblastoma: a systematic review and meta-analysis

Purpose

Neuroblastoma is a solid malignant tumor with high malignancy and high risk for metastasis. The prognosis of neuroblastoma ranges from spontaneous regression to insensitivity to therapies and widespread metastasis. There is a non-invasive, panoramic imaging technique called ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET/CT), which can provide both complete anatomical information via CT and extent of FDG uptake value in tumors via positron emission detection. PET/CT is a powerful approach to estimating tumoral metabolic activities, and PET/CT parameters have been demonstrated to be associated with the prognosis of various tumors. However, the predictive performance of PET/CT for the prognosis of neuroblastoma remains unclear. This meta-analysis aims to assess the predictive values of maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for progression-free survival (PFS), event-free survival (EFS), and overall survival (OS) in neuroblastoma patients.

Methods

Literature in PubMed, Embase, Cochrane Library, and Web of Science from January 1985 to June 2023 was searched for studies evaluating predictive values of PET/CT parameters for the prognosis of neuroblastoma. Search items mainly included "Positron Emission Tomography Computed Tomography" and "Neuroblastoma". Hazard ratio (HR) was used as a pooled statistic to assess the association of SUVmax, MTV, and TLG with PFS, EFS, and OS in neuroblastoma patients. Heterogeneity test and sensitivity analysis were performed.

Results

There were eight studies included, with 325 participants. Meta-analysis showed that higher SUVmax was associated with shorter OS [HR = 1.27, 95% CI (1.11, 1.45), p = 0.001], while no association with PFS [HR = 1.03, 95% CI (0.99, 1.07), p = 0.222] and EFS [HR = 2.58, 95% CI (0.37, 18.24), p = 0.341] was presented. MTV showed no association with OS [HR = 2.46, 95% CI (0.34, 18.06), p = 0.376] and PFS [HR = 2.60, 95% CI (0.68, 9.88), p = 0.161]. There was a statistically significant association between TLG and OS [HR = 1.00, 95% CI (1.00, 1.00), p = 0.00], while the HR was 1, so the association could not be concluded, and TLG showed no association with PFS [HR = 1.00, 95% CI (0.99, 1.00), p = 0.974].

Conclusion

High SUVmax indicates poor OS in patients with neuroblastoma. The MTV and TLG are potential prognostic predictors that need to be further validated by more well-designed studies.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier 340729.

Multimodality imaging evaluation of primary testicular extranodal natural killer/T-cell lymphoma: two case reports

Background

Extranodal natural killer/T-cell lymphoma (ENKTCL) is a distinct pathological entity and accounts for ~10% of T-cell lymphomas. The histological features of ENKTCL include angiodestruction and coagulative necrosis and the association with EBV infection. ENKTCL is typically aggressive and mainly affects the nasal cavity and nasopharyngeal region. However, some patients can present with distant nodal or extranodal involvement such as the Waldeyer ring, gastrointestinal tract, genitourinary organs, lung, thyroid, skin, and testes. Compared to ENKTCL of nasal type, primary testicular ENKTCL is very rare and has a lower age of onset and faster clinical progression, with tumor cell dissemination occurring early in the disease.

Case report

Case 1: A 23-year-old man presented with 1 month of right testicular pain and swelling. Enhancement CT revealed increased density in the right testis, uneven increased enhancement, discontinuity of the local envelope, and multiple trophoblastic vessels in the arterial phase. Testicular ENKTCL was diagnosed by post-operative pathology. The patient underwent a follow-up ¹⁸F-FDG PET/CT imaging 1 month later and found elevated metabolism in the bilateral nasal, left testicular, and right inguinal lymph nodes. Unfortunately, the patient received no further treatment and died 6 months later. Case 2: A 2-year-old male child presented with an enlarged right testicle, MRI showed a mass in the right epididymis and testicular area, which showed low signal on T1WI, high signal on T2WI and DWI, and low signal on ADC. Meanwhile, CT showed soft tissue in the lower lobe of the left lung and multiple high-density nodules of varying sizes in both lungs. Based on the post-operative pathology, the lesion was diagnosed with primary testicular ENKTCL. The pulmonary lesion was diagnosed as hemophagocytic lymphohistiocytosis associated with EBV infection. The child was given SMILE chemotherapy, but pancreatitis was induced during chemotherapy, then he died 5 months later after chemotherapy.

Conclusion

Primary testicular ENKTCL is very rare in clinical practice, typically presenting as a painful testicular mass, which can mimic inflammatory lesions and cause diagnostic challenges. ¹⁸F-FDG PET/CT plays pivotal roles in the diagnosis, staging, evaluation of treatment outcomes and prognosis evaluation in patients with testicular ENKTCL, and it is helpful to assist clinical practice to better formulate individualized treatment plans.

The Diagnostic Performance of Maximum Uptake Value and Apparent Diffusion Coefficient in Differentiating Benign and Malignant Ovarian or Adnexal Masses: A Meta-Analysis

Objective

The purpose of this meta-analysis was to provide evidence for using maximum uptake value (SUVmax) and apparent diffusion coefficient (ADC) to quantitatively differentiate benign and malignant ovarian or adnexal masses, and to indirectly compare their diagnostic performance.

Material and Methods

The association between SUVmax, ADC and ovarian or adnexal benign and malignant masses was searched in PubMed, Cochrane Library, and Embase databases until October 1, 2021. Two authors independently extracted the data. Studies included in the analysis were required to provide data for the construction of a 2 × 2 contingency table to evaluate the diagnostic performance of SUVmax or ADC in differentiating benign and malignant ovarian or adnexal masses. The quality of the enrolled studies was evaluated by Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) instrument, and the meta-analysis was conducted using Stata software version 14.0. Forest plots were generated according to the sensitivity and specificity of SUVmax and ADC, and meta-regression analysis was further used to assess heterogeneity between studies.

Results

A total of 14 studies were finally included in this meta-analysis by gradually excluding duplicate literatures, conference abstracts, guidelines, reviews, case reports, animal studies and so on. The pooled sensitivity and specificity of SUVmax for quantitative differentiation of benign and malignant ovarian or adnexal masses were 0.88 and 0.89, respectively, and the pooled sensitivity and specificity for ADC were 0.87 and 0.80, respectively.

Conclusion

Quantitative SUVmax and ADC values have good diagnostic performance in differentiating benign and malignant ovarian or adnexal masses, and SUVmax has higher accuracy than ADC. Future prospective studies with large sample sizes are needed for the analysis of the role of SUVmax and ADC in the differentiation of benign and malignant ovarian or adnexal masses. 

Towards Next Generation Biomarkers in Natural Killer/T-Cell Lymphoma

Natural killer/T-cell lymphoma (NKTCL) is an Epstein-Barr virus-associated non-Hodgkin lymphoma linked to an aggressive clinical course and poor prognosis. Despite an improvement in survival outcomes with the incorporation of novel agents including immune checkpoint inhibitors in the treatment of NKTCL, a significant proportion of patients still relapse or remain refractory to treatment. Several clinical prognostic models have been developed for NKTCL patients treated in the modern era, though the optimal approach to risk stratification remains to be determined. Novel molecular biomarkers derived from multi-omic profiling have recently been developed, with the potential to improve diagnosis, prognostication and treatment of this disease. Notably, a number of potential biomarkers have emerged from a better understanding of the tumor immune microenvironment and inflammatory responses. This includes a recently described 3'UTR structural variant in the PD-L1 gene, which confers susceptibility to checkpoint immunotherapy. In this review, we summarize the biomarker landscape of NKTCL and highlight emerging biomarkers with the potential for clinical implementation.

Regional Brain Glucose Metabolism and Its Prognostic Value in Pretreatment Extranodal Natural Killer/T-Cell Lymphoma Patients

Objective

To explore regional brain glucose metabolic abnormalities of pretreatment stage I/II extranodal natural killer/T-cell lymphoma (ENKTL) patients using positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (¹⁸F-FDG PET/CT) and assess its prognostic value.

Methods

Sixty pretreatment stage I/II ENKTL patients were enrolled in this retrospective study and divided into survival (n = 45) and death (n = 15) groups according to their status at the end of follow-up. A control group consisted of 60 healthy subjects. Regional cerebral glucose metabolism was evaluated on a voxel-by-voxel basis using statistical parametric mapping (SPM8) under a certain significance level (P < 0. 001) and voxel threshold (K = 100 voxels).

Results

Decreased metabolism was noted in patients, involving the bilateral prefrontal and orbitofrontal cortex, partial parietal and occipital cortex, cingulate gyrus and cerebellum; the sensorimotor cortex was largely spared. Increased metabolism was observed in the bilateral putamen, amygdala, and parahippocampal gyrus. Compared with the survival group, the death group had higher metabolism in the bilateral amygdala, putamen, left thalamus, uncus, and parahippocampal gyrus. Only B symptoms were associated with the increased metabolism of basal ganglia and thalamus (BGT). Patients with high metabolic tumor volume, total lesion glycolysis (TLG) and BGT metabolism had a poor prognosis. TLG and maximum standardized uptake value (SUVmax) LBGT/SUVmaxRight cerebellum were associated with Eastern Cooperative Oncology Group (ECOG) and prognostic index of natural killer lymphoma and Epstein-Barr virus-DNA (PINKE) scores. In multivariate analysis, only ECOG was an independent prognostic factor of both progression-free survival (PFS) and overall survival (OS). PINKE was an independent prognostic factor of OS.

Conclusion

Pretreatment stage I/II ENKTL patients exhibited abnormal regional cerebral glucose metabolism. Higher pretreatment glucose metabolism in BGT could predict a relatively poor prognosis but did not surpass the predictive values of ECOG and PINKE in stage I/II ENKTL patients.

The exact Deauville score, NABS score and high SUVmax predicts outcome in extranodal natural killer/T-cell lymphoma

OBJECTIVE

Natural killer T-cell lymphoma (NKTCL) is an aggressive type of non-Hodgkin's lymphoma. While FDG-PET/CT imaging has been increasingly utilized for disease assessment, its prognostic value and potential utility in NKTCL patient stratification remain controversial. We aim to investigate the prognostic utility of FDG-PET/CT and its role in complementing clinical indices.

METHODS

We conducted a retrospective review of 72 patients from a tertiary National Cancer Centre with biopsy-proven NKTCL and available FDG-PET/CT data (either baseline, end of treatment or both). Survival analysis was performed using the Kaplan-Meier method and multivariable Cox proportional regression.

RESULTS

High initial SUVmax was significantly associated with advanced Ann-Arbor stage (p = 0.0352), elevated LDH levels (p = 0.0059) and plasma EBV DNA detection (p = 0.0278). SUVmax correlated with worse progression-free survival (PFS) (HR 3.68, 95% CI 1.56-8.69, p = 0.0030) and a trend toward worse overall survival (OS) (HR 2.06, 95% CI 0.95-4.45, p = 0.0676). End of treatment Deauville scores of 4-5, as compared to scores of 1-3, was associated with worse PFS (HR 2.72, 95% CI 1.04-7.12, p = 0.0419). Notably, while all patients with scores of 5 developed progressive disease, only 2 of 5 patients with scores of 4 eventually relapsed. Clinical indices (NABS score) were still able to stratify survival outcomes regardless of end-of-treatment Deauville scores.

CONCLUSIONS

A Deauville score of 5 is more diagnostic of true disease progression than a score of 4, and NABS score may be used in patients who achieve Deauville scores of 1-3 for further risk stratification. A higher SUVmax at baseline portends a worse prognosis in NKTCL.

Comparison of Nasopharyngeal MR, 18 F-FDG PET/CT, and 18 F-FDG PET/MR for Local Detection of Natural Killer/T-Cell Lymphoma, Nasal Type

Objectives

The present study aims to compare the diagnostic efficacy of MR, ¹⁸F-FDG PET/CT, and ¹⁸F-FDG PET/MR for the local detection of early-stage extranodal natural killer/T-cell lymphoma, nasal type (ENKTL).

Patients and Methods

Thirty-six patients with histologically proven early-stage ENKTL were enrolled from a phase 2 study (Cohort A). Eight nasopharyngeal anatomical regions from each patient were imaged using ¹⁸F-FDG PET/CT and MR. A further nine patients were prospectively enrolled from a multicenter, phase 3 study; these patients underwent ¹⁸F-FDG PET/CT and PET/MR after a single ¹⁸F-FDG injection (Cohort B). Region-based sensitivity and specificity were calculated. The standardized uptake values (SUV) obtained from PET/CT and PET/MR were compared, and the relationship between the SUV and apparent diffusion coefficients (ADC) of PET/MR were analyzed.

Results

In Cohort A, of the 288 anatomic regions, 86 demonstrated lymphoma involvement. All lesions were detected by ¹⁸F-FDG PET/CT, while only 70 were detected by MR. ¹⁸F-FDG PET/CT exhibited a higher sensitivity than MR (100% vs. 81.4%, χ² = 17.641, P < 0.001) for local detection of malignancies. The specificity of ¹⁸F-FDG PET/CT and MR were 98.5 and 97.5%, respectively (χ² = 0.510, P = 0.475). The accuracy of ¹⁸F-FDG PET/CT was 99.0% and the accuracy of MR was 92.7% (χ² = 14.087, P < 0.001). In Cohort B, 72 anatomical regions were analyzed. PET/CT and PET/MR have a sensitivity of 100% and a specificity of 92.5%. The two methods were consistent (κ = 0.833, P < 0.001). There was a significant correlation between PET/MR SUVmax and PET/CT SUVmax (r = 0.711, P < 0.001), and SUVmean (r = 0.685, P < 0.001). No correlation was observed between the SUV and the ADC.

Conclusion

In early-stage ENKTL, nasopharyngeal MR showed a lower sensitivity and a similar specificity when compared with ¹⁸F-FDG PET/CT. PET/MR showed similar performance compared with PET/CT.

Baseline SUVmax of 18F-FDG PET-CT indicates prognosis of extranodal natural killer/T-cell lymphoma

To evaluate the prognostic value of the baseline SUVmax of F-FDG PET-CT in extranodal natural killer/T-cell lymphoma (NKTCL) patients.From January 2010 to December 2015, 141 extranodal NKTCL patients with staging F-FDG PET-CT scan were divided into two group based on SUVmax cutoff value obtained from operating characteristic (ROC) curves. All the patients received radiotherapy, chemotherapy or chemoradiation. Survival analysis was performed on the basis of SUVmax.The median baseline SUVmax of the tumors was 11.67 (range 2.6-34.6). The ROC curves showed that the optimal cutoff of the baseline SUVmax was 9.65. The patients were divided into two groups: low SUV group (SUVmax < 9.65) and high SUV group (SUVmax ≥ 9.65). Patients in high SUV group were more likely to have invasive disease outside the nasal cavity (P < .001), poorer ECOG scores (P = .012) and higher LDH levels (P = .034). The univariate survival analyses indicated that high SUVmax was a poor prognostic factor for overall survival (OS, P = .038), progression free survival (PFS, P = .006) and distant relapse free survival (DRFS, P = .001), but not for local recurrence free survival (LRFS, P > .05). These results were consistent with that of the survival analyses using the Kaplan-Meier method. The multivariate survival analyses showed that the baseline SUVmax was no longer a prognostic factor for OS (HR 1.99, 95% CI 0.81-4.88, P = .135), but it still indicated worse PFS (HR 2.6, 95% CI 1.24-5.46, P = .012) and DRFS (HR 4.58, 95% CI 1.83-11.46, P = .001) independent of other variables.For extranodal NKTCL patients, a higher baseline SUVmax of F-FDG PET-CT was associated with more aggressive clinical features. An SUVmax ≥ 9.65 was an independent poor prognostic factor for DRFS and PFS. Thus, the baseline SUVmax may be a valuable tool to help identify patients with a high risk of disease progression.

Current status and quality of radiomics studies in lymphoma: a systematic review

OBJECTIVES

To perform a systematic review regarding the developments in the field of radiomics in lymphoma. To evaluate the quality of included articles by the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), the phases classification criteria for image mining studies, and the radiomics quality scoring (RQS) tool.

METHODS

We searched for eligible articles in the MEDLINE/PubMed and EMBASE databases using the terms "radiomics", "texture" and "lymphoma". The included studies were divided into two categories: diagnosis-, therapy response- and outcome-related studies. The diagnosis-related studies were evaluated using the QUADAS-2; all studies were evaluated using the phases classification criteria for image mining studies and the RQS tool by two reviewers.

RESULTS

Forty-five studies were included; thirteen papers (28.9%) focused on the differential diagnosis of primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM). Thirty-two (71.1%) studies were classified as discovery science according to the phase classification criteria for image mining studies. The mean RQS score of all studies was 14.2% (ranging from 0.0 to 40.3%), and 23 studies (51.1%) were given a score of < 10%.

CONCLUSION

The radiomics features could serve as diagnostic and prognostic indicators in lymphoma. However, the current conclusions should be interpreted with caution due to the suboptimal quality of the studies. In order to introduce radiomics into lymphoma clinical settings, the lesion segmentation and selection, the influence of the pathological pattern and the extraction of multiple modalities and multiple time points features need to be further studied.

KEY POINTS

• The radiomics approach may provide useful information for diagnosis, prediction of the therapy response, and outcome of lymphoma. • The quality of published radiomics studies in lymphoma has been suboptimal to date. • More studies are needed to examine lesion selection and segmentation, the influence of pathological patterns, and the extraction of multiple modalities and multiple time point features.

Development and validation of an 18F-FDG PET radiomic model for prognosis prediction in patients with nasal-type extranodal natural killer/T cell lymphoma

OBJECTIVES

To identify an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) radiomics-based model for predicting progression-free survival (PFS) and overall survival (OS) of nasal-type extranodal natural killer/T cell lymphoma (ENKTL).

METHODS

In this retrospective study, a total of 110 ENKTL patients were divided into a training cohort (n = 82) and a validation cohort (n = 28). Forty-one features were extracted from pretreatment PET images of the patients. Least absolute shrinkage and selection operator (LASSO) regression was used to develop the radiomic signatures (R-signatures). A radiomics-based model was built and validated in the two cohorts and compared with a metabolism-based model.

RESULTS

The R-signatures were constructed with moderate predictive ability in the training and validation cohorts (R-signature_PFS: AUC = 0.788 and 0.473; R-signature_OS: AUC = 0.637 and 0.730). For PFS, the radiomics-based model showed better discrimination than the metabolism-based model in the training cohort (C-index = 0.811 vs. 0.751) but poorer discrimination in the validation cohort (C-index = 0.588 vs. 0.693). The calibration of the radiomics-based model was poorer than that of the metabolism-based model (training cohort: p = 0.415 vs. 0.428, validation cohort: p = 0.228 vs. 0.652). For OS, the performance of the radiomics-based model was poorer (training cohort: C-index = 0.818 vs. 0.828, p = 0.853 vs. 0.885; validation cohort: C-index = 0.628 vs. 0.753, p < 0.05 vs. 0.913).

CONCLUSIONS

Radiomic features derived from PET images can predict the outcomes of patients with ENKTL, but the performance of the radiomics-based model was inferior to that of the metabolism-based model.

KEY POINTS

• The R-signatures calculated by using ¹⁸F-FDG PET radiomic features can predict the survival of patients with ENKTL. • The radiomics-based models integrating the R-signatures and clinical factors achieved good predictive values. • The performance of the radiomics-based model was inferior to that of the metabolism-based model in the two cohorts.

Prognostic Values of Baseline 18F-FDG PET/CT in Patients with Peripheral T-Cell Lymphoma

Purpose

In the present study, we aimed to investigate whether the metabolic parameters on baseline ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) could be used to predict prognosis in peripheral T-cell lymphomas (PTCL).

Methods

A total of 51 nodal PTCL patients who underwent baseline ¹⁸F-FDG PET/CT were retrospectively evaluated in the present study. Total metabolic tumor volume (TMTV), total lesion glycolysis (TLG), and maximum standardized uptake value (SUV_max) were also assessed. Besides, the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) was also included. Log-rank test and Cox regression analysis were used to evaluate progression-free survival (PFS) and overall survival (OS).

Results

The median follow-up was 18 months. Patients with low TLG, TMTV, and SUV_max levels had a significantly better clinical outcome than those with high TLG, TMTV, and SUV_max levels. The 2-year PFS rates of the high- and low-TMTV groups were 34.62% and 80%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (p < 0.001), whereas the corresponding 2-year OS rates were 46.15% and 84.00%, respectively (n = 10), intermediate-risk group with TMTV > 62.405 or NCCN-IPI score of 4-8 (2-year PFS and OS were 52.4% and 66.7%, respectively, n = 10), intermediate-risk group with TMTV > 62.405 or NCCN-IPI score of 4-8 (2-year PFS and OS were 52.4% and 66.7%, respectively, n = 10), intermediate-risk group with TMTV > 62.405 or NCCN-IPI score of 4-8 (2-year PFS and OS were 52.4% and 66.7%, respectively,

Conclusions

Baseline TMTV and TLG were independent predictors of PFS and OS in PTCL patients, and SUV_max and NCCN-IPI scores were also independent predictors of OS. Moreover, the combination of TMTV and NCCN-IPI scores improved patient risk-stratification at the initial stage and might contribute to the adjustment of the therapeutic regime. This trial is registered with ChiCTR1900025526.

Investigating PSMA-Targeted Radioligand Therapy Efficacy as a Function of Cellular PSMA Levels and Intratumoral PSMA Heterogeneity

PURPOSE

Prostate-specific membrane antigen (PSMA) targeting radioligands deliver radiation to PSMA-expressing cells. However, the relationship between PSMA levels and intralesion heterogeneity of PSMA expression, and cytotoxic radiation by radioligand therapy (RLT) is unknown. Here we investigate RLT efficacy as function of PSMA levels/cell, and the fraction of PSMA⁺ cells in a tumor.

EXPERIMENTAL DESIGN

RM1 cells expressing different levels of PSMA (PSMA^-, PSMA⁺, PSMA⁺⁺, PSMA⁺⁺⁺; study 1) or a mix of PSMA⁺ and PSMA^- RM1 (study 2, 4) or PC-3/PC-3-PIP (study 3) cells at various ratios were injected into mice. Mice received ¹⁷⁷Lu- (studies 1-3) or ²²⁵Ac- (study 4) PSMA617. Tumor growth was monitored. Two days post-RLT, tumors were resected in a subset of mice. Radioligand uptake and DNA damage were quantified.

RESULTS

¹⁷⁷Lu-PSMA617 efficacy increased with increasing PSMA levels (study 1) and fractions of PSMA positive cells (studies 2, 3) in both, the RM1 and PC-3-PIP models. In tumors resected 2 days post-RLT, PSMA expression correlated with ¹⁷⁷Lu-PSMA617 uptake and the degree of DNA damage. Compared with ¹⁷⁷Lu-PSMA617, ²²⁵Ac-PSMA617 improved overall antitumor effectiveness and tended to enhance the differences in therapeutic efficacy between experimental groups.

CONCLUSIONS

In the current models, both the degree of PSMA expression and the fraction of PSMA⁺ cells correlate with ¹⁷⁷Lu-/²²⁵Ac-PSMA617 tumor uptake and DNA damage, and thus, RLT efficacy. Low or heterogeneous PSMA expression represents a resistance mechanism to RLT.See related commentary by Ravi Kumar and Hofman, p. 2774.

The predictive value of dynamic monitoring of peripheral blood lymphocyte to monocyte ratio in patients with extranodal NK/T cell lymphoma

Background

To investigate the value of dynamic monitoring peripheral blood lymphocyte-to-monocyte (LMR) ratio in evaluating the treatment response and prognosis of patients with extranodal NK/T cell lymphoma (ENKTL).

Methods

A total of 148 patients with ENKTL were retrospectively analyzed in the Affiliated Tumor Hospital of Zhengzhou University between March 2012 and March 2018. The optimal cut-off value of LMR was determined using the receiver operating characteristic curve (ROC) method, then patients were divided into low LMR group and high LMR group. The LMR level was dynamically measured at various time points, and the relationships between LMR and therapeutic response, and survival were analyzed.

Results

The complete remission rate (CR) was 85.7% in patients with high LMR at diagnosis, which was remarkably higher than that of patients with low LMR at diagnosis (64.9%) (P = 0.009). The 5-year overall survival (OS) and progression-free survival (PFS) were 49.28% and 44.89% in the low LMR group, respectively; 5-year OS and PFS in the high LMR group were 84.50% and 67.12%, respectively, significantly longer (P values were < 0.001 and 0.034, respectively). The OS and PFS of patients with elevated LMR after treatment were longer than those with decreased LMR after treatment (all P values < 0.05). The LMRs at relapse were significantly lower in both high and low LMR groups than those of the last follow-up (P values were 0.001 and 0.016, respectively). Univariate and multivariate analysis demonstrated that low LMR was an independent risk factor for poor prognosis in ENKTL patients (P values were < 0.001 and 0.009, respectively).

Conclusions

Lymphocyte to monocyte ratio can be used as an indicator of treatment response, prognosis and recurrence in patients with ENKTL. Low LMR before and after treatment is a poor prognostic factor.

Evolving Role of PET-Based Novel Quantitative Techniques in the Management of Hematological Malignancies

"The role of ¹⁸F-fluorodeoxyglucose PET/computed tomography in hematological malignancies continues to expand in disease diagnosis, staging, and management. A key advantage of PET over other imaging modalities is its ability to quantify tracer uptake, which can be used to determine degree of disease activity. Although tracer uptake with PET is conventionally measured in focal lesions, novel quantitative techniques are being investigated that set objective protocols and produce robust parameters that represent total disease activity portrayed by PET. This article discusses recent advances in PET quantification that can improve reliability and accuracy of characterizing hematological malignancies."

Positron emission tomography/computed tomography in the diagnosis, staging, and prognostic evaluation of natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTL) is a rare subtype of non-Hodgkin's lymphoma that is associated with Epstein-Barr virus infection. The clinicopathological features of NKTL are unique among lymphomas. NKTL is an aggressive disease with a poor prognosis in the absence of effective treatment. Accurate diagnosis and staging are essential to ensure an appropriate treatment strategy and accurate prognosis of NKTL. ¹⁸F-Fluorodexoyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a valuable technique in the diagnosis, staging, and prognostic evaluation of various types of malignant tumors, including NKTL. PET/CT imaging studies of patients with NKTL have shown that NKTL is ¹⁸F-FDG-avid and that PET/CT is superior to conventional methods in detecting cutaneous and extracutaneous lesions. We herein review recent PET/CT studies that have provided considerable insight into the diagnosis, staging, prognostic evaluation, and treatment effectiveness in patients with NKTL.