Positron emission tomography/computed tomography in the management of Hodgkin and B-cell non-Hodgkin lymphoma: An update

¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is now an integral part of lymphoma staging and management. Because of its greater accuracy compared with CT alone, PET/CT is currently routinely performed for staging and for response assessment at the end of treatment in the vast majority of FDG-avid lymphomas and is the cornerstone of response classification for these lymphomas according to the Lugano classification. Interim PET/CT, typically performed after 2 to 4 of 6 to 8 chemotherapy/chemoimmunotherapy cycles with or without radiation, is commonly performed for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-adapted or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics, such as the standardized uptake value, changes (Δ) in the standardized uptake value, metabolic tumor volume, and total lesion glycolysis, are being investigated as more reproducible and potentially more accurate predictors of response and prognosis. Despite the progress made in standardizing the use of PET/CT in lymphoma, challenges remain, particularly with respect to its limited positive predictive value, emphasizing the need for more specific molecular probes. This review highlights the most relevant applications of PET/CT in Hodgkin and B-cell non-Hodgkin lymphoma, its strengths and limitations, as well as recent efforts at implementing PET/CT-based metrics as promising tools for precision medicine.

PET/CT and contrast-enhanced CT: making a difference in assessment and staging of patients with lymphoma

Background

The aim of this study is to evaluate the diagnostic performance of contrast-enhanced computed tomography (CECT) and 2-[Fluorine-18] fluoro-2-deoxy-d-glucose positron emission tomography combined to computed tomography (18 F-FDG PET/CT) in assessment of lymphoma.

Methods

Hundred patients, pathologically proven as lymphoma, were evaluated by CECT and 18F-FDG PET/CT for initial assessment and staging of the disease. The number of lesions and the disease stage detected by each modality was calculated and further analyzed to be compared.

Results

18F-FDG PET/CT diagnosed a total number of 545 lymphoma involved regions with sensitivity 96.6%, specificity 98.8%, and accuracy 99% that was higher than CECT which diagnosed a total number of 439 lymphomatous regions with sensitivity 87.5%, specificity 85.7%, and accuracy 88%. Discordant staging by both modalities was found in 23% of the patients. Lymphoma was upstaged by PET/CT in 17% of the patients; with major changes in 12% of them and downstaged in 6% of the patients.

Conclusion

18F-FDG PET/CT scan has a better diagnostic performance, represented by sensitivity, specificity, and accuracy, than CECT scan in the initial assessment of lymphoma regarding its nodal and extra-nodal lesions that could lead to alteration of disease staging which in turn markedly affecting the decision of treatment regimens.

PET/CT in Disease Detection and Follow-up of Subcutaneous Involvement in Marginal Zone Lymphoma

BACKGROUND

The value of positron emission tomography/computed tomography (PET/CT) in the staging and assessment of treatment response in marginal zone lymphoma (MZL) lymphomas remains controversial. We investigated radiologic characteristics of subcutaneous MZL as imaged on PET/CT scans.

PATIENTS AND METHODS

From the records of a single medical center, for the years 2008 and 2017, we identified subcutaneous lesions in PET/CT scans of patients with histopathologically confirmed MZL in sites other than subcutaneous tissue.

RESULTS

Of 571 scans of 178 patients, subcutaneous lesions were found in 20 (11%). Lesions were located in soft tissue structures, mainly along the lateral aspects of the buttocks, thighs and lower and upper back areas, the flank, and the shoulders. Median lengths of the long and short axes of the lesions were 2.0 (range, 1.1-6.0) cm and 0.8 (range, 0.3-2.0) cm, respectively. Median standardized maximum uptake value was 2.3 (range, 0.9-7.6). In 12 patients (60%), MZL was diagnosed at an early stage; 15 (75%) had lymph node involvement and 10 (50%) extranodal involvement. One had spleen and 2 had cutaneous involvement; none had gastric findings.

CONCLUSION

The findings of this study support the usefulness of PET/CT in the detection of subcutaneous MZL as well as in staging and treatment decisions.

A comparison of clinical staging using the Lugano versus Ann Arbor classifications in Japanese patients with Hodgkin lymphoma

AIMS

The Lugano classification is a novel staging system for lymphomas established in 2014. In this staging system, ¹⁸ F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) was formally incorporated into standard staging for FDG-avid lymphomas, including Hodgkin lymphoma (HL). We retrospectively analyzed patients with HL who were newly diagnosed and treated at our institution to evaluate the utility of the Lugano classification compared to the Ann Arbor classification in Japanese patients with this type of lymphoma.

METHODS

Patients newly diagnosed with HL between 2005 and 2011 were identified through our departmental database. Data from neck-chest-abdomen-pelvis CT scans, BM examinations, and FDG-PET/CT that were routinely performed for staging at our clinical practice were retrieved and analyzed.

RESULTS

Fifty-four patients with a median age of 35.5 years (range: 15-78 years) were investigated in this retrospective study. The Lugano stage matched the Ann Arbor stage in 46 patients (85%). Six patients (11%) were upstaged while two (4%) were downstaged per the Lugano classification. Four patients (7%) were converted from early stage to advanced stage, but none was converted in the reverse. Among 11 patients (20%) with PET-positive bone/bone marrow lesions, only one (2%) exhibited biopsy-proven bone marrow involvement of HL cells.

CONCLUSION

Our data revealed a high concordance rate between the Lugano and Ann Arbor staging system in Japanese patients with HL. Because of its low diagnostic value, routine bone marrow examination might be unnecessary for staging when FDG-PET/CT is used as a substitute.

End-of-Treatment PET/Computed Tomography Response in Diffuse Large B-Cell Lymphoma

"PET imaging with fluorodeoxyglucose (FDG), integrated with PET/computed tomography (FDG-PET/CT), is an effective management tool of diffuse large B-cell lymphoma (DLBCL). The results of end-of-treatment (EOT) FDG-PET/CT are more accurate for detection of active disease with residual masses on CT. Complete response defined by EOT FDG-PET/CT (PET-CR) correlates with long-term outcome of patients. Treatment efficacy is determined using EOT PET/CT rather than progression-free survival (PFS) for clinical trials assessing novel drugs. If the correlation of EOT PET/CT with PFS is further proven in large studies and meta-analyses, EOT PET-CR could serve as an expedited novel endpoint replacing PFS."

Detection of bone marrow involvement with FDG PET/CT in patients with newly diagnosed lymphoma

Background

Bone marrow involvement (BMI) affects the lymphoma stage, survival, and treatment. Bone marrow biopsy (BMB) and fluorodeoxyglucose (FDG) positron emission tomography- computed tomography (PET/CT) are useful techniques to detect BMI. Both have advantages and disadvantages. We aimed to identify factors that could be used to predict BMI with positive and negative results on PET/CT compare them with BMB in newly diagnosed patients with lymphoma.

Methods

We included 22 non-Hodgkin and 16 Hodgkin lymphoma patients in this single center study. All patients had PET/CT examination and BMB before treatment. BMI in BMB was reported as negative or positive. Bone marrow was classified into 3 types by FDG uptake on PT/CT; diffuse involvement, focal involvement, and normal bone marrow.

Results

PET/CT and BMB results were concordant (7 positive, 15 negative) in 22 patients (57%). We evaluated concordant and discordant patient characteristics and risk-stratified patients for BMI. Our findings suggest that patients with diffuse FDG uptake on PET/CT, especially patients with advanced age and low platelet and white blood cell counts, are likely to have BMI and could potentially forego BMB. Patients with negative PET/CT findings and no significant laboratory abnormalities are very unlikely to have BMI.

Conclusion

Our results suggest that BMI should not be decided solely based PET/CT or BMB findings. It is reasonable to use both diagnostic assays along with clinical and laboratory findings. PET/CT result, clinical and laboratory findings could be useful for predicting BMI in patient for whom BMB is contraindicated.

Effect of PET/CT on the Management and Outcomes of Participants with Hodgkin and Aggressive Non-Hodgkin Lymphoma: A Multicenter Registry

Purpose To determine the relationship of PET/CT staging to the management and outcomes of participants with apparent limited-stage (LS) Hodgkin lymphoma (HL) or aggressive non-HL (ANHL) treated with curative intent. Materials and Methods This prospective multicenter registry included 850 participants (467 men and 383 women; median age, 54.1 years) from nine centers who had LS HL or ANHL on the basis of clinical data and CT, or with equivocal CT for advanced stage, who were considered for curative-intent first-line therapy. Participants were recruited between May 1, 2013, and December 31, 2015. Pre-PET/CT treatment plan was compared with treatment provided. Survival and second-line therapy initiation were compared with an historical control pool staged by using CT alone. Administrative data sources were used to control for baseline characteristics. Outcomes were assessed by using adjusted Cox proportional hazards regression and propensity score matching. Results PET/CT helped to upstage 150 of 850 participants (17.6%). There was a change in planned therapy in 224 of 580 (38.6%) of participants after PET/CT. There was a lower 1-year mortality for participants with ANHL in the PET/CT versus CT cohort (hazard ratio, 0.63; 95% confidence interval: 0.40, 1.0; P < .05) and for those with LS at PET/CT compared with those with LS at CT (hazard ratio, 0.40; 95% confidence interval: 0.21, 0.74; P = .004). For participants with HL, no 1-year outcome difference was found (P = .16). Conclusion PET/CT helped to upstage approximately 18% of participants and planned management was frequently altered. Participants with aggressive non-Hodgkin lymphoma whose first-line therapy was guided by PET/CT had significantly better survival compared with participants whose treatment was guided by CT. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Scott in this issue.

FDG PET in response evaluation of bulky masses in paediatric Hodgkin's lymphoma (HL) patients enrolled in the Italian AIEOP-LH2004 trial

PURPOSE

We present the results of an investigation of the role of FDG PET in response evaluation of bulky masses in paediatric patients with Hodgkin's lymphoma (HL) enrolled in the Italian AIEOP-LH2004 trial.

METHODS

We analysed data derived from 703 patients (388 male, 315 female; mean age 13 years) with HL and enrolled in 41 different Italian centres from March 2004 to September 2012, all treated with the AIEOP-LH2004 protocol. The cohort comprised 309 patients with a bulky mass, of whom 263 were evaluated with FDG PET at baseline and after four cycles of chemotherapy. Responses were determined according to combined functional and morphological criteria. Patients were followed up for a mean period of 43 months and for each child we calculated time-to-progression (TTP) and relapse rates considering clinical monitoring, and instrumental and histological data as the reference standard. Statistical analyses were performed for FDG PET and morphological responses with respect to TTP. Multivariate analysis was used to define independent predictive factors.

RESULTS

Overall, response evaluation revealed 238 PET-negative patients (90.5%) and 25 PET-positive patients (9.5%), with a significant difference in TTP between these groups (mean TTP: 32.67 months for negative scans, 23.8 months for positive scans; p < 0.0001, log-rank test). In the same cohort, computed tomography showed a complete response (CR) in 85 patients (32.3%), progressive disease (PD) in 6 patients (2.3%), and a partial response (PR) in 165 patients (62.7%), with a significant difference in TTP between patients with CR and patients with PD (31.1 months and 7.9 months, respectively; p < 0.001, log-rank test). Similarly, there was a significant difference in relapse rates between PET-positive and PET-negative patients (p = 0000). In patients with PR, there was also a significant difference in TTP between PET-positive and PET-negative patients (24.6 months and 34.9 months, respectively; p < 0.0001). In the multivariate analysis with correction for multiple testing, only the PET result was an independent predictive factor in both the entire cohort of patients and the subgroup showing PR on CT (p < 0.01).

CONCLUSION

After four cycles of chemotherapy, FDG PET response assessment in paediatric HL patients with a bulky mass is a good predictor of TTP and disease outcome. Moreover, in patients with a PR on CT, PET was able to differentiate those with a longer TTP. In paediatric HL patients with a bulky mass and in patients with a PR on CT, response on FDG PET was an independent predictive factor.

Utility of PET-CT for Evaluation of Patients With Peripheral T-cell Lymphoma

BACKGROUND

Fluorine-18 fluorodeoxyglucose (FDG) avidity varies in peripheral T-cell lymphoma (PTCL). We evaluated FDG avidity of pretreatment positron emission tomography/computed tomography (P-PET/CT), to appraise the prognostic significance of interim PET/CT (I-PET/CT) and end of treatment PET/CT (E-PET/CT) in PTCL.

PATIENTS AND METHODS

We performed a retrospective cohort study of patients with newly diagnosed or relapsed PTCL who had received any chemotherapy regimen from 2008 to 2015 in a tertiary center. P-PET/CT, I-PET/CT, and E-PET/CT studies were centrally reviewed. The primary outcomes were the prognostic role of I-PET/CT and E-PET/CT on progression-free survival (PFS) and overall survival (OS). The secondary outcomes were P-PET/CT avidity, the prognostic role of other baseline characteristics, and the correlation between the PET/CT and bone marrow biopsy findings.

RESULTS

We included 40 patients in the present analysis. The median OS and PFS for the whole cohort was 39 and 16 months, respectively. Of the 40 patients, 36 had positive P-PET/CT findings. A total of 23 patients underwent I-PET/CT, with positive findings for 10. Of the 40 patients, 34 underwent E-PET/CT, 26 of which had positive findings. The sensitivity, specificity, and negative predictive value of P-PET/CT for bone marrow involvement was 40%, 83%, and 89%, respectively. The factors significantly associated with PFS and OS on univariate analysis included elevated lactate dehydrogenase, and low lymphocyte, hemoglobin, and albumin levels. On multivariate analysis, only lymphopenia remained prognostic for PFS and OS. The E-PET/CT and I-PET/CT results were not prognostic for PFS or OS.

CONCLUSION

Our study has shown that 90% of PTCL cases will be FDG avid. However, PET/CT was not predictive for PFS or OS at any point. The only predictive factor was the presence of lymphopenia.

PET-CT in Staging, Response Evaluation, and Surveillance of Lymphoma

OPINION STATEMENT

Lymphoma represents a broad spectrum of diseases with diverse biology, clinical behavior, and imaging features. Functional imaging with 18-F-fluorodeoxyglucose (FDG)-positron emission tomography combined with computed tomography (PET-CT) is widely recognized as the most sensitive and specific imaging modality for patients with lymphoma and is used as part of staging, response evaluation, and surveillance in patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL). Recent efforts at standardizing the conduct and consensus interpretation of PET-CT have facilitated its use in patients on clinical studies and beyond. The role of PET-CT has been affirmed in some clinical situations, such as staging and end-of-treatment evaluation in Hodgkin lymphoma and diffuse large B cell lymphoma (DLBCL), and in the evaluation of aggressive transformation of an indolent lymphoma. However, the role of functional imaging in other histologies and clinical settings is not as clear given the higher rate of false positive results and the costs inherent to PET-CT. There is little evidence to suggest its utility or impact on outcome in most indolent lymphomas, or in the setting of post-treatment surveillance. In addition, there remains controversy about the value of PET-CT in early response assessment during active therapy, particularly in DLBCL. This review will evaluate the evidence surrounding the role of PET-CT in staging, response evaluation and surveillance of Hodgkin and non-Hodgkin lymphoma.

Patterns of use and survival outcomes of positron emission tomography for initial staging in elderly follicular lymphoma patients

The role of positron emission tomography (PET) in the initial assessment of follicular lymphoma (FL) has been a topic of debate. We examined the patterns of utilization of PET staging in FL and assessed the association of PET with survival. Using the SEER-Medicare database, we identified 5712 patients diagnosed with first primary FL between 2000 and 2009. Older age, African-American race, poor performance status, B-symptoms and history of anemia were negatively associated with PET staging. Receipt of PET staging was positively associated with treatment at institutions affiliated with research networks and with residence in areas with higher concentrations of nuclear medicine specialists. PET was associated with improved lymphoma-related (HR 0.69, 95% CI: 0.58-0.82) and overall (HR 0.75, 95% CI: 0.68-0.83) survival. Our findings substantiate the use of PET as the standard of care for imaging in FL patients. Further investigation is warranted to identify mechanisms underlying the apparent survival advantage associated with PET staging in FL.

18F-FDG PET/CT in the clinical management of patients with lymphoma

The aim of this work was to review the current recommendations for staging and response assessment of patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) in routine clinical practice after chemotherapy and/or stem cell transplantation. A five-point scale (5-PS) from the First International Workshop on PET in Lymphoma in Deauville, France, in 2009, was recommended as the standard tool to score imaging to assess treatment response in patients with lymphoma using ¹⁸F-Fluorodeoxyglucose (FDG) PET/CT. Following the recommendations of the 11th and 12th International Conferences on Malignant Lymphoma held in Lugano (Switzerland), in 2011 and 2013, respectively, a consensus (the so-called Lugano Classification) was reached regarding the use of PET/CT for staging and response assessment in FDG-avid lymphomas. As a result, ¹⁸F-FDG PET/CT was formally incorporated into standard staging for FDG-avid lymphomas. A bone marrow biopsy is no longer indicated for the routine staging of HL and most diffuse large B-cell lymphomas. PET/CT will be used to assess response in FDG-avid histologies using the 5-point scale. The recent introduction of biological agents with immune mechanisms requires flexibility in interpretations of the Lugano criteria due to tumour flare or a pseudo-progression effect produced by these agents. Provisional criteria have been proposed (Lymphoma Response to Immunomodulatory Therapy Criteria) with the introduction of the term 'Indeterminate Response' in order to identify this phenomenon until confirmed as flare/pseudoprogression or true progression. All these recommendations will improve evaluations of patients with lymphoma, and allow comparison of results from clinical practice and trials.

The Emerging Role of PET/MR Imaging in Gynecologic Cancers

This article summarizes recent advances in PET/MR imaging in gynecologic cancers and the emerging clinical value of PET/MR imaging in the management of the 3 most common gynecologic malignancies: cervical, endometrial, and ovarian cancers. PET/MR imaging offers superior soft tissue contrast, improved assessment of primary tumor involvement because of high-resolution multiplanar reformats, and functional MR techniques such as diffusion-weighted MR imaging and dynamic contrast-enhanced MR imaging. This article discusses the challenges, future directions, and technical advances of PET/MR imaging, and the emerging new multimodality, multiparametric imaging techniques for integrating morphologic, functional, and molecular imaging data.

Advancing Precision Nuclear Medicine and Molecular Imaging for Lymphoma

PET with fluorodeoxyglucose F 18 (¹⁸F FDG-PET) is a meaningful biomarker for the detection, targeted biopsy, and treatment of lymphoma. This article reviews the evolution of ¹⁸F FDG-PET as a putative biomarker for lymphoma and addresses the current capabilities, challenges, and opportunities to enable precision medicine practices for lymphoma. Precision nuclear medicine is driven by new imaging technologies and methodologies to more accurately detect malignant disease. Although quantitative assessment of response is limited, such technologies will enable a more precise metabolic mapping with much higher definition image detail and thus may make it a robust and valid quantitative response assessment methodology.

The Evolving Role of Medical Imaging in Lymphoma Management: The Clinician's Perspective

Hodgkin and non-Hodgkin lymphomas are a heterogeneous group of hematologic neoplasms which arise from malignant lymphocytes. Imaging plays an important role in management of lymphoma patients during diagnosis, staging, and response assessment. Functional imaging may also provide prognostic information and improve the ability to detect extranodal disease. This article provides an overview of the evolving role of various imaging techniques in lymphoma from the clinician's perspective. It serves as an introduction to the other articles in this issue that focus on specific areas of lymphoma imaging.

PET-CT for staging and early response: results from the Response-Adapted Therapy in Advanced Hodgkin Lymphoma study

International guidelines recommend that positron emission tomography-computed tomography (PET-CT) should replace CT in Hodgkin lymphoma (HL). The aims of this study were to compare PET-CT with CT for staging and measure agreement between expert and local readers, using a 5-point scale (Deauville criteria), to adapt treatment in a clinical trial: Response-Adapted Therapy in Advanced Hodgkin Lymphoma (RATHL). Patients were staged using clinical assessment, CT, and bone marrow biopsy (RATHL stage). PET-CT was performed at baseline (PET0) and after 2 chemotherapy cycles (PET2) in a response-adapted design. PET-CT was reported centrally by experts at 5 national core laboratories. Local readers optionally scored PET2 scans. The RATHL and PET-CT stages were compared. Agreement among experts and between expert and local readers was measured. RATHL and PET0 stage were concordant in 938 (80%) patients. PET-CT upstaged 159 (14%) and downstaged 74 (6%) patients. Upstaging by extranodal disease in bone marrow (92), lung (11), or multiple sites (12) on PET-CT accounted for most discrepancies. Follow-up of discrepant findings confirmed the PET characterization of lesions in the vast majority. Five patients were upstaged by marrow biopsy and 7 by contrast-enhanced CT in the bowel and/or liver or spleen. PET2 agreement among experts (140 scans) with a κ (95% confidence interval) of 0.84 (0.76-0.91) was very good and between experts and local readers (300 scans) at 0.77 (0.68-0.86) was good. These results confirm PET-CT as the modern standard for staging HL and that response assessment using Deauville criteria is robust, enabling translation of RATHL results into clinical practice.

ACR Appropriateness Criteria® Diffuse Large B-Cell Lymphoma

The management of diffuse large B-cell lymphoma depends on the initial diagnosis including molecular and immunophenotypic characteristics, Ann Arbor staging, and International Prognostic Index (IPI score). Treatment approaches with different chemotherapy regimens used is discussed in detail. The role of radiation as a consolidation is discussed including: (1) the prerituximab randomized trials that challenged the role of radiation, (2) recent prospective studies (UNFOLDER/RICOVER-60), and (3) retrospective studies; the last 2 showed a potential benefit of radiation both for early and advanced stage. The document also discusses the role of positron emission tomography/computed tomography for predicting outcome and potentially guiding therapy. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Clinical factors indicating the presence of malignant lymphoma before lymph node dissection

CONCLUSION

Lymph node swelling in the neck is one of the initial symptoms of malignant lymphoma (ML). The present study showed that clinical factors including higher age, higher level of maximum standardized uptake value (SUV-max) of positron-emission tomography, elevated serum lactate dehydrogenase (LDH), and elevated serum soluble interleukin-2 receptor (sIL-2R) were all useful indicators to suggest the diagnosis of ML, so may be helpful in the selection of patients for lymph node dissection.

OBJECTIVE

Lymph node dissection is essential for the diagnosis of ML. The factors important for the diagnosis of ML were investigated, to establish surgical indicators.

METHODS

Preoperative data including age, number and side of lymph nodes, SUV-max, serum LDH, serum sIL-2R, and size of lymph nodes were obtained from medical records. The cut-off level for each factor was calculated using the Youden Index for logistic regression analysis.

RESULTS

Multivariate logistic regression analysis showed that the following factors were associated with ML: higher age (≥ 53 years), higher level of SUV-max (≥ 9.0), elevated serum LDH (≥ 203 U/L), elevated serum sIL-2R (≥ 2590 U/ml), with odds ratios of 3.7, 4.9, 3.7, and 11.9, respectively.

Role of imaging in the staging and response assessment of lymphoma: consensus of the International Conference on Malignant Lymphomas Imaging Working Group

PURPOSE

Recent advances in imaging, use of prognostic indices, and molecular profiling techniques have the potential to improve disease characterization and outcomes in lymphoma. International trials are under way to test image-based response–adapted treatment guided by early interim positron emission tomography (PET)–computed tomography (CT). Progress in imaging is influencing trial design and affecting clinical practice. In particular, a five-point scale to grade response using PET-CT, which can be adapted to suit requirements for early- and late-response assessment with good interobserver agreement, is becoming widely used both in practice- and response-adapted trials. A workshop held at the 11th International Conference on Malignant Lymphomas (ICML) in 2011 concluded that revision to current staging and response criteria was timely.

METHODS

An imaging working group composed of representatives from major international cooperative groups was asked to review the literature, share knowledge about research in progress, and identify key areas for research pertaining to imaging and lymphoma.

RESULTS

A working paper was circulated for comment and presented at the Fourth International Workshop on PET in Lymphoma in Menton, France, and the 12th ICML in Lugano, Switzerland, to update the International Harmonisation Project guidance regarding PET. Recommendations were made to optimize the use of PET-CT in staging and response assessment of lymphoma, including qualitative and quantitative methods.

CONCLUSION

This article comprises the consensus reached to update guidance on the use of PET-CT for staging and response assessment for [18F]fluorodeoxyglucose-avid lymphomas in clinical practice and late-phase trials.

Role of 2-Deoxy-2-[18F]-fluoro-d-glucose-PET/Computed Tomography in Lymphoma

The role of PET and PET/computed tomography (CT) has evolved significantly in the last few decades. 2-Deoxy-2-[18F]-fluoro-d-glucose (FDG)-PET/CT is now an integral part of the management of patients with lymphoma. FDG-PET/CT at the time of initial staging can help in appropriate staging of the patients. Both interim and end-of-therapy PETs have significant prognostic value in patients with Hodgkin lymphoma and aggressive non-Hodgkin lymphoma and more accurately assess for the presence of residual malignancy than anatomic imaging. The impact of interim FDG-PET/CT on risk-adapted strategies is an area of active investigation and the results of ongoing clinical trials will be informative.

Prognostic factors for diffuse large B-cell lymphoma in the R(X)CHOP era

BACKGROUND

The introduction of rituximab (R) to conventional CHOP chemotherapy for newly diagnosed diffuse large B-cell lymphoma (DLBCL) led to an unequivocal improvement in survival, establishing RCHOP as the standard of care. Still, nearly 40% of DLBCL patients will eventually die of relapsed disease. Efforts to improve outcomes by addition of new biologic agents (X) to the RCHOP backbone are underway. In this era of R(X)CHOP, it is imperative to develop prognostic and predictive markers, not only to identify patients who will suffer a particularly aggressive course, but also to accurately select patients for clinical trials from which they will most benefit.

DESIGN

The following review was undertaken to describe prognostic factors in DLBCL, with emphasis on markers that are accurate, relatively available, and clinically applicable in 2014.

RESULTS

The International Prognostic Index retains its validity in the era of RCHOP, although with limited ability to predict those with <50% chance of long-term survival. Gene expression profiling has provided novel insights into the biology of DLBCL and led to the development of immunohistochemistry (IHC) algorithms that are in routine practice. Identification of a 'double-hit' (DH) lymphoma by fluorescent in situ hybridization with aberrations involving MYC and/or BCL2 and BCL6 genes has important implications due to its extremely dismal prognosis with RCHOP. Other markers such as the absolute lymphocyte count (ALC), serum immunoglobulin free light chains, vitamin D levels, serum cytokines/chemokines, and imaging with positron emission tomography (PET) have all shown promise as future predictive/prognostic tests.

CONCLUSIONS

The future for new treatment options in DLBCL is promising with current clinical trials testing novel targeted agents such as bortezomib, lenalidomide, and ibrutinib as the 'X' in R(X)CHOP. Predictive factors are required to select and randomize patients appropriately for these trials. We envision the day when 'X' will be chosen based on the biological characteristics of the tumor.

Prognostic value of interim positron emission tomography in patients with peripheral T-cell lymphoma

The definition of the role of positron emission tomography (PET) in peripheral T-cell lymphomas (PTCLs) is still under investigation. The purpose of the present observational retrospective study was to assess the early prognostic value of PET after the first three cycles of therapy (PET+3), evaluating visual data in de novo PTCL patients treated in first line with standard chemotherapy and followed by both PET and computed tomography scan. Of 27 PET+3-negative patients, 19 also had a negative PET at the end of treatment (PET+6), whereas 8 of 27 had a positive final one; 6 of 7 PET+3-positive patients had a positive PET+6, whereas only 1 patient had a negative PET+6. Estimated overall survival plotted according to PET+3 results showed 78.6% for negative patients and 21.4% for positive patients at 88.7 months with a significant difference. Patients with negative PET+3 had superior progression-free survival of 72.6% compared with 16.7% of PET+3-positive patients. At the time of this analysis, 17 of 19 (89.5%) patients with negative PET+3 are in continuous complete response (CCR) and only 1 of 7 (14.2%) patients with positive PET+3 is still in CCR. In conclusion, our results indicate that positive PET+3 is predictive of a worse outcome in PTCL, and this significant statistical difference between the two curves could be clinically informative. Larger and prospective studies and harmonization of PET reading criteria are needed.

An update on criteria for assessing tumor response to treatment

Standardized tumor response criteria have been developed over time since the advent of cytotoxic anticancer therapies. The criteria have evolved and continue to do so as the understanding of the therapeutic basis of various anticancer agents increases and as novel therapeutic agents are developed. Currently, the criteria can be divided into the following main categories: anatomical-based criteria; tumor- and therapy-specific criteria; metabolic-based criteria; and response assessment of lymphomas. The standardized criteria are critical to the successful conduct of clinical trials during the development of cancer therapeutic agents as they offer uniform end points that facilitate comparison of therapeutic agents and interpretation of studies. The criteria are also relevant in clinical practice as they standardize how radiologists select, measure, and report lesions in oncology patients, and they provide standardized definitions for tumor response categories. To remain relevant in a rapidly evolving oncology field and provide up-to-date imaging information that meets the needs of oncologists in both research trials and clinical practice, radiologists need to familiarize themselves with the various standardized tumor response criteria.

Diffuse lymphadenopathy as the presenting manifestation of systemic lupus erythematosus

We report the case of a 27-year-old African American man who presented with 6 months of generalized lymphadenopathy and nothing in his history or examination to suggest systemic lupus erythematosus (SLE). He was thought to have lymphoma, syphilis, or tuberculosis, and an extensive workup was done. Laboratory investigation finally revealed leukopenia (4.0), proteinuria (1.87 g), antinuclear antibodies (640 speckled), anti-double-stranded DNA (640), anticardiolipin immunoglobulins G and M, anti-Smith, Coombs, anti-Ro, anti-La, CK (531 U/L), aldolase (8.5 U/L), high erythrocyte sedimentation rate (130 mm/h), and low complement (C3 15 mg/dL and C4 3 mg/dL). A kidney biopsy showed diffuse proliferative glomerulonephritis, International Society of Nephrology class IV. Generalized lymphadenopathy as the first and only manifestation for 6 months made the diagnosis of SLE challenging. Generalized diffuse lymphadenopathy has been associated with SLE but is much less frequent now than in the past. The differential diagnosis of lymphadenopathy relevant to rheumatologists includes Kikuchi histiocytic necrotizing lymphadenitis, Castleman disease, syphilis, tuberculosis, sarcoidosis, and lymphoma.

Current role of FDG PET/CT in lymphoma

The management approach in Hodgkin's (HL) and high-grade non-Hodgkin's lymphomas (NHL) has shifted towards reducing the toxicity and long-term adverse effects associated with treatment while maintaining favorable outcomes in low-risk patients. The success of an individualized treatment strategy depends largely on accurate diagnostic tests both at staging and during therapy. In this regard, positron emission tomography (PET) using fluorodeoxyglucose (FDG) with computed tomography (CT) has proved effective as a metabolic imaging tool with compelling evidence supporting its superiority over conventional modalities, particularly in staging and early evaluation of response. Eventually, this modality was integrated into the routine staging and restaging algorithm of lymphomas. This review will summarize the data on the proven and potential utility of PET/CT imaging for staging, response assessment, and restaging, describing current limitations of this imaging modality.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

Value of 18F-FDG PET versus iliac biopsy in the initial evaluation of bone marrow infiltration in the case of Hodgkin's disease: a meta-analysis

OBJECTIVE

We carried out a meta-analysis to evaluate the performance of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) PET and PET/CT against bone marrow biopsy (BMB) in the initial diagnosis of bone marrow infiltration (BMI) in patients with Hodgkin's disease (HD).

MATERIALS AND METHODS

Retrospective and prospective studies with direct comparison of (18)F-FDG PET with BMB in the initial evaluation of BMI in HD were included. Seven eligible studies were included in the meta-analysis comprising a total of 687 patients.

RESULTS

Both (18)F-FDG PET and BMB had excellent specificity in detecting BMI. However, (18)F-FDG PET had excellent pooled sensitivity (94.5%; 95% confidence interval: 89.0-97.8%) in detecting BMI in the initial staging of HD patients, whereas the pooled sensitivity of iliac BMB was very poor (39.4%; 95% confidence interval: 30.8-48.4%). The diagnostic odds ratio, a measure of the overall diagnostic power of the test, was much higher for PET (pooled value of 1591) than for iliac BMB (pooled value of 137).

CONCLUSION

(18)F-FDG PET significantly outperforms iliac BMB in the detection of BMI in the initial staging of HD patients and therefore should be used as a first-line study. Iliac BMB has low sensitivity and a high rate of false-negative findings. Thus, a negative BMB finding cannot rule out marrow involvement in HD patients on initial staging.

Not all that shines is cancer: pulmonary cryptococcosis mimicking lymphoma in [(18)] F fluoro-2-deoxy-D-glucose positron emission tomography

We report of a case of pulmonary cryptococcosis mimicking lymphoma in a positron emission tomography (FDG-PET) scan. A 62-year old man with diffuse large B-cell lymphoma had complete resolution of abdominal and pulmonary lesions after three cycles of rituximab-based chemotherapy (R-CHOP). However, FDG-PET showed new pulmonary nodules, suggesting active lymphoma. Chronic inflammatory granuloma was seen in the histopathological exam, with round-shaped structures compatible with fungus, later identified as Cryptococcus neoformans on culture. The lesions disappeared after 6 weeks of fluconazole therapy, and the patient could continue chemotherapy without further infectious complications.

The role of FDG-PET scanning in assessing lymphoma in 2012

Positron emission tomography (PET) has a proven role in the assessment diffuse large B-cell lymphoma (DLBCL) and Hodgkin's lymphoma (HL). The clinical impact of PET carried out at the end of the patient's course of treatment is undeniable and recommendations must be followed in the interpretation of these examinations. PET is highly recommended as part of the initial investigations of these diseases because it can be used as a reference for the interpretation at treatment completion and allows disease spread to be assessed with greater sensitivity and specificity than when computed tomography (CT) is used. It seems to be certain that PET is useful for interim examinations too, in terms of assessing prognosis in DLBCL and HL, although its impact in terms of early changes to treatment is still to be determined. The criteria for interpreting the results of these early assessments are still evolving and the annual meetings in Menton, France, of groups of experts are leading towards a uniform interpretation method. In other types of lymphoma, PET can be useful for confirming local disease staging, especially in follicular lymphoma, and for guiding biopsy in patients with low-grade lymphoma that is suspicious for transformation into more aggressive disease. Several studies are in agreement that PET is valuable for assessing prognosis at treatment completion in FL and mantle cell lymphoma, but prospective studies are needed for this new indication to be validated.

Advances in oncologic imaging: update on 5 common cancers

Imaging has become a pivotal component throughout a patient's encounter with cancer, from initial disease detection and characterization through treatment response assessment and posttreatment follow-up. Recent progress in imaging technology has presented new opportunities for improving clinical care. This article provides updates on the latest approaches to imaging of 5 common cancers: breast, lung, prostate, and colorectal cancers, and lymphoma.

Non-Hodgkin lymphoma

Lymphomas are solid tumours of the immune system. Hodgkin's lymphoma accounts for about 10% of all lymphomas, and the remaining 90% are referred to as non-Hodgkin lymphoma. Non-Hodgkin lymphomas have a wide range of histological appearances and clinical features at presentation, which can make diagnosis difficult. Lymphomas are not rare, and most physicians, irrespective of their specialty, will probably have come across a patient with lymphoma. Timely diagnosis is important because effective, and often curative, therapies are available for many subtypes. In this Seminar we discuss advances in the understanding of the biology of these malignancies and new, available treatments.

[Importance of PET/CT in lymphoma diagnostics]

CLINICAL/METHODICAL ISSUE

Staging or re-staging of lymphomas using conventional imaging modalities is based on morphological changes, usually on the diameter of lesions. However, vitality of tumors cannot be evaluated.

STANDARD RADIOLOGICAL METHODS

In this context computed tomography (CT) has been used as a standard modality.

METHODICAL INNOVATIONS

Since the introduction of positron emission tomography (PET), evaluation of tumor vitality has become possible. Moreover PET/CT hybrid scanners were brought onto the market one decade ago.

PERFORMANCE

The fluorodeoxyglucose (FDG) PET/CT technique is now accepted as one of the most accurate modalities in the diagnosis of aggressive lymphomas due to a high FDG uptake (overall accuracy > 90%, sensitivity >90%). However, indolent lymphomas suffer from lower FDG uptake due to a moderate metabolic activity. After the introduction of PET/CT hybrid imaging the specificity of this diagnostic technique increased significantly compared to PET alone (from > 80% to > 90%). With the utilization of PET approximately 20% more lesions are detected when comparing to CT alone and in up to 15% of the patients this also results in a change of the therapeutic regime. As post-chemotherapy scar tissue usually persists for months, evaluation of vitality within residual bulks using FDG-PET can predict therapy response much earlier than CT, enabling therapy stratification. Other PET tracers apart from FDG have low impact in imaging of lymphomas and only the thymidine analogue fluorothymidine (FLT) is used in some cases for non-invasive measurement of proliferation.

ACHIEVEMENTS

Despite the capability of FDG-PET/CT there is no evidence that the improvement in diagnostics is translated into a better patient outcome and therefore warrants the high costs. False positive findings in PET can result in unnecessary treatment escalation with subsequent higher therapy-associated toxicity and costs.

PRACTICAL RECOMMENDATIONS

Some pitfalls can be avoided by scheduling PET scans carefully. As treatment-induced inflammation early after therapy can be misinterpreted as vital tumor tissue, it is recommended to wait at least 3 weeks between the last treatment cycle and the subsequent FDG-PET follow-up. Until the results of the prospective multicenter trials "PETAL" and "HD-18" become available, in Germany FDG-PET is only recommended generally for restaging Hodgkin's disease with a known rest bulk of  > 2.5 cm in justifiable individual cases or in clinical trials.

Positron emission tomographic scans in lymphoma: convention and controversy

The use of sensitive and specific imaging techniques for accurate initial staging and evaluation of response to therapy in patients with lymphoma is essential for their optimal management. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) integrated with computed tomography (CT) has emerged as a powerful imaging tool and is being routinely used in staging, response evaluation, and posttreatment surveillance in patients with non-Hodgkin lymphoma and Hodgkin lymphoma. PET/CT is currently widely used in clinical practice, but the established clinical benefit is currently restricted to the posttreatment evaluation of Hodgkin lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma. Although used in other histologic subtypes and in other clinical situations including response assessment, its impact on patient outcome remains to be demonstrated. We performed a literature search of PubMed from 1999 to 2011 using the following keywords: PET scan, FDG-PET, PET/CT, lymphoma. This review addresses the challenges and controversies in the use of PET/CT scans in the management of patients with lymphoma.

Radiation exposure and mortality risk from CT and PET imaging of patients with malignant lymphoma

Objective

To quantify radiation exposure and mortality risk from computed tomography (CT) and positron emission tomography (PET) imaging with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) in patients with malignant lymphoma (Hodgkin’s disease [HD] or non-Hodgkin’s lymphoma [NHL]).

Methods

First, organ doses were assessed for a typical diagnostic work-up in children with HD and adults with NHL. Subsequently, life tables were constructed for assessment of radiation risks, also taking into account the disease-related mortality.

Results

In children with HD, cumulative effective dose from medical imaging ranged from 66 mSv (newborn) to 113 mSv (15 years old). In adults with NHL the cumulative effective dose from medical imaging was 97 mSv. Average fractions of radiation-induced deaths for children with HD [without correction for disease-related mortality in brackets] were 0.4% [0.6%] for boys and 0.7% [1.1%] for girls, and for adults with NHL 0.07% [0.28%] for men and 0.09% [0.37%] for women.

Conclusion

Taking into account the disease-related reduction in life expectancy of patients with malignant lymphoma results in a higher overall mortality but substantial lower incidence of radiation induced deaths. The modest radiation risk that results from imaging with CT and ¹⁸F-FDG PET can be considered as justified, but imaging should be performed with care, especially in children.

Key Points

Survival of malignant lymphoma has improved dramatically over the past decades.

PET and CT currently play important roles for malignant lymphoma patients.

The potential hazard of ionising radiation has become an increasingly important issue.

When assessing radiation risks, disease-related reduction in life expectancy should be considered.

CT and¹⁸F-FDG PET create a modest radiation-induced mortality risk.

18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Management of Aggressive Non-Hodgkin's B-Cell Lymphoma

18-Fluorodeoxyglucose (FDG-PET/CT) is an established imaging modality that has been proven to be of benefit in the management of aggressive B-cell non-Hodgkin's lymphoma, such as diffuse large B-cell lymphoma and advanced stage follicular lymphoma. The combination of anatomic and functional imaging afforded by FDG-PET/CT has led to superior sensitivity and specificity in the primary staging, restaging, and assessment of response to treatment of hematological malignancies when compared to FDG-PET and CT alone. The use of FDG-PET/CT for posttreatment surveillance imaging remains controversial, and further study is needed to ascertain whether this modality is cost effective and appropriate for use in this setting.