PET/CT in malignant lymphoma: basic information, clinical application, and proposal

Predictive Significance of a New Prognostic Score for Patients With Diffuse Large B-Cell Lymphoma in the Interim-Positron Emission Tomography Findings

We hypothesized that the objective treatment response of patients with diffuse large B-cell lymphoma (DLBCL) was affected by many factors such as pathophysiological, biological, and pharmaceutical mechanisms. This retrospective study aimed to evaluate the predictive significance of clinical prognostic factors and interim fluorine-18-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT), and to find a new prognostic predictor significantly associated with DLBCL patients' outcome. A total of 105 adult patients with DLBCL were reviewed. Each patient underwent an interim F-FDG PET/CT scan after the second chemotherapy cycle. The visual method based on the Deauville 5-point scale was used to evaluate the interim-PET/CT scans. The relationships among the prognostic factors, the 3-year progression-free survival (PFS) rate and overall survival (OS) rate were analyzed with Kaplan-Meier plots. The predictive value of the newly constructed prognostic score was analyzed with multivariate analysis (Cox proportional hazard regression model). The visual analysis showed statistically significant differences in both PFS and OS between the patients with a negative interim-PET/CT and those with a positive interim-PET/CT. Advanced age, advanced stage, and DLBCL subtype were also significantly associated with outcome. A new prognostic score that composed of the above 4 factors was obtained. New prognostic score stratified patients into 4 risk groups with 3-year PFS of 98.5%, 73.9%, 11.1%, and 0%, and 3-year OS of 100%, 91.3%, 55.6%, and 0% (P < 0.001 for PFS and OS). Multivariate analysis showed that the new prognostic score had the greatest ability to predict relapse (P < 0.001) and death (P < 0.001). In DLBCL patients, interim F-FDG PET/CT can provide significant independent prognostic information. Our work illustrates that the new prognostic score has the strongest potential for accurately prognostication, for stratification in clinical trials, and for design of novel strategies for DLBCL patients in the high-risk group.

Whole-body MRI with diffusion-weighted imaging: a valuable alternative to contrast-enhanced CT for initial staging of aggressive lymphoma

AIM

To compare the accuracy of whole-body magnetic resonance imaging (Wb-MRI) with diffusion-weighted imaging (DWI) to that of contrast-enhanced computed tomography (CE-CT) and 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) positron-emission tomography co-registered with low dose-CT (PET-CT) in defining lymphoma disease stage.

MATERIALS AND METHODS

From February 2010 to May 2014, 41 lymphoma patients underwent Wb-MRI-DWI, CE-CT, and (18)F-FDG PET-CT. Histological subtypes included aggressive B-cell (n=11), follicular (n=13), mantle cell (n=3), and Hodgkin's (n=14) lymphoma. To compare the procedures, the reference standard (RS) assessment was defined by combining the results from (18)F-FDG PET-CT, CE-CT, and bone marrow (BM) histology, modifications after therapy, and histological re-assessments of uncertain lesions.

RESULTS

Among 1025 nodal sites, 217 had disease involvement according to the RS. CE-CT yielded 23 false-negative and 11 false-positive errors. Wb-MRI-DWI failed to recognise 17 localisations and had six false-positive errors; (18)F-FDG PET-CT had no errors. Among 458 extranodal sites, 37 were positive according to the RS. (18)F-FDG PET-CT yielded four false-negative and two false-positive results. CE-CT yielded 17 false-negative errors. Wb-MRI-DWI yielded a single false-negative error. Wb-MRI-DWI was the most reliable imaging technique for BM evaluation. Considering each procedure alone, the final stage would have been missed in four cases using (18)F-FDG PET-CT, 12 cases using CE-CT, and none using Wb-MRI-DWI.

CONCLUSION

The present data support Wb-MRI-DWI as a sensitive and specific imaging technique for lymphoma evaluation, supporting its use in place of CE-CT for staging.

Prognostic significance of interim PET/CT based on visual, SUV-based, and MTV-based assessment in the treatment of peripheral T-cell lymphoma

Backgrounds

The role of interim PET/CT in peripheral T-cell lymphoma (PTCL) is less identified compared to other subtype of lymphoma. This study prospectively investigated the prognostic accuracy of sequential interim PET/CT using visual and quantitative assessment to determine whether it provided prognostic information for the treatment of PTCL.

Methods

Sixty-three patients with newly diagnosed PTCL were enrolled, and 59 patients underwent interim PET/CT after three or four courses of induction treatment. The response of interim PET/CT was assessed by three parameters: the Deauville five-point scale (5-PS), ΔSUVmax, and ΔMTV2.5.

Results

Over a median follow up of 40.3 months, each assessment of interim PET/CT using the 5-PS, ΔSUVmax, and ΔMTV2.5 had predictive value for progression-free survival. To increase the predictive accuracy of interim PET/CT, we divided patients into three groups according to the sum of scores for three adverse responses based on the visual, SUV-based and MTV-based assessment: favorable, intermediate, and poor responder. The clinical outcome of patients in the favorable group was significantly superior to patients in the poor or intermediate group.

Conclusion

Visual, quantitative SUV-based, and MTV-based assessment in interim PET/CT are valuable for early treatment response assessment in patients with PTCL, and the combined approach using the three parameters was more efficient in discriminating between patients with different survival outcomes compared with single-parameter assessment.

Trial registration

NCT01470066.

Upfront autologous stem-cell transplantation with melphalan, cyclophosphamide, etoposide, and dexamethasone (LEED) in patients with newly diagnosed primary central nervous system lymphoma

Treatment of primary central nervous system lymphoma (PCNSL) improved in recent years. However, the high neurotoxicity and low survival rates associated with this condition remain unresolved. We report 13 consecutive patients with PCNSL for whom upfront melphalan, cyclophosphamide, etoposide, and dexamethasone (known as LEED) followed by autologous stem-cell transplantation (ASCT) was planned at the Anjo Kosei Hospital. All patients were pathologically diagnosed with diffuse large B-cell lymphoma and were negative for human immunodeficiency virus. All patients were to receive three cycles of high-dose methotrexate-based induction chemotherapy, two cycles of high-dose AraC-based chemotherapy, and LEED followed by ASCT. All 13 patients achieved a partial response, and the 3-year overall survival (OS) rate was 76.2 %. Seven of the 13 patients were alive at the last follow-up, without any adverse events, including neurotoxicity. Six of the 13 (46.2 %) patients underwent ASCT and the 3-year OS rate was 80.0 %. Although this study included only a limited number of patients, these preliminary signs of efficacy and tolerability merit further consideration. To make further improvements in survival, the rate of patients undergoing ASCT should be increased. Other prospective studies involving greater numbers of patients are required to confirm these findings.

Assessment of the nature of residual masses at end of treatment in lymphoma patients using volume perfusion computed tomography

OBJECTIVES

To determine the diagnostic benefit of volume perfusion computed tomography (VPCT) at end of treatment for response assessment in lymphoma patients.

METHODS

Seventy-five patients with different lymphoma subtypes were included: 50/75 patients had residual masses at end of treatment, 26/50 patients underwent VPCT at baseline and at end of treatment, and 24/50 patients only had end-of-treatment VPCTs. We evaluated the size of the main lymphoma mass, its blood flow (BF), blood volume (BV) and k-trans, calculated ratios (baseline and end of treatment) as well as sensitivity/specificity/negative (NPV)/positive predictive values (PPV). For VPCT at end of treatment, a cutoff threshold between responders and non-responders was calculated.

RESULTS

For patients undergoing VPCT at baseline and end of treatment, reduction in size, BF, BV and k-trans was significant (P < 0.001). Identification of non-response was reached at: <53% reduction in size (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/62.5%/80.77%/84.21%/71.43%), <15% reduction of BF (sensitivity/specificity/accuracy/PPV/NPV of 100%/37.5%/80.77%/0.26%/100%), or <45% reduction of k-trans (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/75%/84.62%/88.89%/75%). In the subgroup undergoing VPCT at end of treatment, BF >18.51 ml/100 ml indicated non-responsiveness (sensitivity 92.86%, specificity 72.73%, accuracy 84%, PPV 81.25%, NPV 88.89%).

CONCLUSIONS

VPCT seems adequate for assessment of lymphoma response at end of treatment. The degree of residual lymphoma perfusion at end of treatment helps to identify patients likely to remain in remission 1 year after completion of therapy.

KEY POINTS

• Volume perfusion computed tomography (VPCT) offers measurements for assessing tumour response. • Perfusion parameter changes measured by VPCT correlate with antitumour therapy response. • In lymphoma, baseline and end-of-treatment perfusion parameter ratios can predict response. • Perfusion measurements after treatment identify patients likely to remain in remission.