Early detection of relapse by whole-body positron emission tomography in the follow-up of patients with Hodgkin's disease

Hodgkin lymphoma and liquid biopsy: a story to be told

Hodgkin lymphoma (HL) represents a neoplasm primarily affecting adolescents and young adults, necessitating the development of precise diagnostic and monitoring tools. Specifically, classical Hodgkin lymphoma (cHL), comprising 90% of cases, necessitating tailored treatments to minimize late toxicities. Although positron emission tomography/computed tomography (PET/CT) has enhanced response assessment, its limitations underscore the urgency for more reliable progression predictive tools. Genomic characterisation of rare Hodgkin Reed-Sternberg (HRS) cells is challenging but essential. Recent studies employ single-cell molecular analyses, mass cytometry, and Next-Generation Sequencing (NGS) to unveil mutational landscapes. The integration of liquid biopsies, particularly circulating tumor DNA (ctDNA), extracellular vesicles (EVs), miRNAs and cytokines, emerge as groundbreaking approaches. Recent studies demonstrate ctDNA's potential in assessing therapy responses and predicting relapses in HL. Despite cHL-specific ctDNA applications being relatively unexplored, studies emphasize its value in monitoring treatment outcomes. Overall, this review underscores the imperative role of liquid biopsies in advancing HL diagnosis and monitoring.

Imaging recommendations in pediatric lymphoma: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) are both malignancies originating in the lymphatic system and both affect children, but many features differ considerably, impacting workup and management. This paper provides consensus-based imaging recommendations for evaluation of patients with HL and NHL at diagnosis and response assessment for both interim and end of therapy (follow-up).

Clinical value of 18F-FDG PET/CT in the management of HIV-associated lymphoma

HIV is still a major public health problem. At present, HIV-associated lymphoma remains the leading cause of deaths among people living with HIV, which should be paid more attention to. ¹⁸F-fluorodeoxglucose (FDG) PET/CT has been recommended in the initial staging, restaging, response assessment and prognostic prediction of lymphomas in general population. HIV-associated lymphoma is, however, a different entity from lymphoma in HIV-negative with a poorer prognosis. The ability to accurately risk-stratify HIV-infected patients with lymphoma will help guide treatment strategy and improve the prognosis. In the review, the current clinical applications of ¹⁸F-FDG PET/CT in HIV-associated lymphoma will be discussed, such as diagnosis, initial staging, response evaluation, prognostic prediction, PET-guided radiotherapy decision, and surveillance for recurrence. Moreover, future perspectives will also be presented.

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.

Lugano classification: response evaluation criteria for positron emission tomography/computed tomography in lymphoma follow-up

Background

The purpose of this study is to assess the role of 18 fluorodeoxyglucose positron emission tomography/computed tomography (18FDG PET-CT) in the follow-up of patients with lymphoma after finishing therapy.

Results

This study included 42 lymphomas (25 non-Hodgkin’s lymphoma and 17 Hodgkin’s lymphoma); patients ranging in age from 18 to 70 years were examined by 18FDG PET-CT after therapy and analyzed retrospectively. Confirmatory biopsy was mandatory in cases of suspected disease recurrence and follow-up in cases of complete metabolic response. Positron emission tomography/computed tomography in assessment of lymphoma treatment response reveals significant statistical significance (P < 0.05). It shows 100% sensitivity, 92.8% specificity, and 95.2% accuracy in the prediction of response.

Conclusion

Positron emission tomography/computed tomography plays an important role in detection of response to treatment of lymphoma after finishing therapy.

Utility of Routine Surveillance Laboratory Testing in Detecting Relapse in Patients With Classic Hodgkin Lymphoma in First Remission: Results From a Large Single-Institution Study

PURPOSE

Classic Hodgkin lymphoma is highly curable with contemporary therapy. Although the limited role of surveillance imaging to detect early relapse for patients in complete remission at the end of therapy is well established, there is a paucity of data regarding role of laboratory testing in this setting.

METHODS

Patients with newly diagnosed classic Hodgkin lymphoma uniformly treated with the Stanford V regimen from 1998-2014 and in complete remission for at least 3 months were identified in a single-center institutional database. Laboratory tests categorized by Common Terminology Criteria for Adverse Events v4.03 as grade 2 or higher were considered abnormal. Primary analysis included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of surveillance laboratory tests for predicting relapse in the first 3 years after end of treatment.

RESULTS

Among 235 eligible patients, 24 (10.2%) patients ultimately relapsed. In the first 3 years after end of therapy, the mean number of surveillance blood draws per patient was 7.1, (range, 1-13). These 1,661 surveillance blood draws included 4,684 individual laboratory tests, comprising 1,609 CBCs, 1,578 metabolic panels, and 1,497 erythrocyte sedimentation rates. None of the biopsies confirming relapses were prompted by any abnormal laboratory finding. The sensitivity of any surveillance laboratory test for detecting relapse within 3 years of end of treatment was 72.7% (95% CI, 49.8% to 89.3%), specificity 22.6% (95% CI, 17.2% to 28.9%), yielding a PPV of 8.9% (95% CI, 7.0% to 11.3%) and NPV of 88.9% (95% CI, 79% to 94%).

CONCLUSION

Our study found limited clinically meaningful utility for routine surveillance laboratory testing in detecting relapse in patients with complete remission at end of treatment. Our results warrant consideration of modifications to current practice guidelines.

FDG-PET Imaging for Hodgkin and Diffuse Large B-Cell Lymphoma-An Updated Overview

Since the mid-1990s, ¹⁸F-fluorodeoxglucose (FDG)-positron emission tomography (PET) in combination with computed tomography has come to play a prominent role in the management of malignant lymphomas. One of the first PET applications in oncology was the detection of lymphoma manifestations at staging, where it has shown high sensitivity. Nowadays, this imaging modality is also used during treatment to evaluate the individual chemosensitivity and adapt further therapy accordingly. If the end-of-treatment PET is negative, irradiation in advanced-stage Hodgkin lymphoma patients can be safely omitted after highly effective chemotherapy. Thus far, lymphoma response assessment has mainly been performed using visual criteria, such as the Deauville five-point scale, which became the international standard in 2014. However, novel measures such as metabolic tumor volume or total lesion glycolysis have recently been recognized by several working groups and may further increase the diagnostic and prognostic value of FDG-PET in the future.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Post-treatment surveillance imaging in lymphoma

Appropriate post-treatment management of patients with lymphoma has been controversial, with imaging frequently performed as post-treatment surveillance. The goal of post-treatment imaging is to identify relapse prior to clinical symptoms, when the burden of disease is lower and the possibility of effective salvage therapy and cure are greater. However, little data exist to support the performance of surveillance imaging after completion of treatment, with the vast majority of studies suggesting there is no clinical benefit to surveillance imaging in asymptomatic patients. Ongoing efforts seek to identify a subset of patients with a higher risk of relapse that might benefit from surveillance imaging, though financial and other costs associated with imaging are non-negligible and must be considered. Here we summarize the current data regarding post-treatment surveillance imaging in lymphoma.

Surveillance Scans in Lymphoma: Friend or Foe?

OPINION STATEMENT

Advancements in the treatment of lymphoma over the last few decades have allowed more patients to achieve a remission after the completion of therapy. Due to the improvement in response rates, methods to detect recurrence early and accurately during follow-up, especially in patients with potential curable aggressive lymphomas, are a key. Observation has always involved close clinical follow-up with the use of physical exams and routine labs, but rapid changes in technology have allowed CT scans, PET scans, and MRIs to become an integral part of managing patients with lymphoma. While the utility of scans in initial staging and immediately after completion of therapy is well established, the use of these imaging modalities for monitoring recurrence in lymphoma patients is still controversial. Patient advocacy groups and other regulatory committees have questioned the frequency and in some cases even the need for these tests in patients without evidence of active disease given the concern for radiation-associated health risks. Additionally, the extent to which this form of testing impacts the psyche of our patients is not completely known. Given the numerous questions raised about the benefits, safety, and cost-effectiveness of CT imaging, firm guidelines are needed at this time in standard practice and within our clinical trials to limit the use of surveillance imaging. Such efforts are expected to improve the utility of these scans in asymptomatic patients, reduce healthcare costs, and reduce patient exposure to radiation.

The role of FDG-PET in Hodgkin lymphoma

18-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) is currently the most valuable imaging technique in Hodgkin lymphoma. Since its first use in lymphomas in the 1990s, it has become the gold standard in the staging and end-of-treatment remission assessment in patients with Hodgkin lymphoma. The possibility of using early (interim) PET during first-line therapy to evaluate chemosensitivity and thus personalize treatment at this stage holds great promise, and much attention is now being directed toward this goal. With high probability, it is believed that in the near future, the result of interim PET-CT would serve as a compass to optimize treatment. Also the role of PET in pre-transplant assessment is currently evolving. Much controversy surrounds the possibility of detecting relapse after completed treatment with the use of PET in surveillance in the absence of symptoms suggestive of recurrence and the results of published studies are rather discouraging because of low positive predictive value. This review presents current knowledge about the role of 18-FDG-PET/CT imaging at each point of management of patients with Hodgkin lymphoma.

Evaluating surveillance imaging for diffuse large B-cell lymphoma and Hodgkin lymphoma

Up to 50% of patients with Hodgkin lymphoma and diffuse large B-cell lymphoma will relapse, requiring additional therapy. Although surveillance imaging is commonly performed in clinical practice, its ability to identify asymptomatic relapses and improve survival for patients is not well defined. We evaluated the surveillance imaging role in relapse detection and reviewed its impact on survival for relapsed patients, and found that current imaging approaches do not detect most relapses prior to clinical signs and symptoms or improve survival.

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.

Imaging of primary pediatric lymphoma of bone

BACKGROUND

Primary pediatric bone lymphoma is a rare form of non-Hodgkin lymphoma. Unlike nodal forms of lymphoma, imaging abnormalities in lymphoma of bone do not resolve rapidly in conjunction with treatment and radiologic findings can remain abnormal for years, making it difficult to evaluate treatment response.

OBJECTIVE

To evaluate the utility of imaging in assessment of patients with primary pediatric bone lymphoma.

MATERIALS AND METHODS

At our institution between 2004 and 2013, six cases of pathology-proven primary pediatric bone lymphoma were diagnosed. Retrospective chart review was performed to assess imaging utilization. Our data were qualitatively compared with existing literature to construct an algorithm for imaging patients with primary lymphoma of bone.

RESULTS

Imaging evaluation of patients with primary pediatric bone lymphoma was highly variable at our institution. Conventional imaging was routinely used to evaluate response to treatment, despite lack of appreciable osseous change. Imaging in the absence of symptoms did not alter clinical management. Only positron emission tomography CT (PET/CT) proved capable of demonstrating imaging changes from the pretreatment to the post-treatment scans that were consistent with the clinical response to treatment.

CONCLUSION

Surveillance imaging is likely unnecessary in patients with a known diagnosis of pediatric lymphoma of bone. Pretreatment and post-treatment PET/CT is likely sufficient to assess response. There is little data to support the use of interim and surveillance PET/CT.

Role of Surveillance Imaging in Patients With Peripheral T-Cell Lymphoma

INTRODUCTION

The role of surveillance imaging (SI) in patients with peripheral T-cell lymphoma (PTCL) in first complete remission (CR1) is unclear.

MATERIALS AND METHODS

Patients with PTCL were identified through prospectively maintained T-cell lymphoma databases from the National Cancer Centre Singapore/Singapore General Hospital and Weill-Cornell Medical College after institutional review board approval. Patients with leukemia or indolent, composite, and cutaneous lymphomas were excluded. The patients' medical records were retrospectively reviewed to determine the frequency and type of SI used. Of those with relapse, the method of relapse detection and data on symptoms, signs, and elevated lactate dehydrogenase LDH were extracted.

RESULTS

A total of 338 patients were included in the present study. In the first year after achieving CR1, patients had an average of 1.2 and a median of 1 SI performed (range, 0-4). In the second year after achieving CR1, they had an average of 0.78 and a median of 1 SI performed (range, 0-4). Of the 135 patients who achieved CR1, 61 (45%) developed a relapse. Relapses were detected before SI in 48 (84%), and 9 patients had relapses detected during routine SI. Of the 9 patients whose relapses were detected during planned SI, only 3 did not have any symptoms or signs suggestive of relapsed disease. Of these 3 patients, 2 had angioimmunoblastic T-cell lymphoma and 1 had natural killer/T-cell lymphoma.

CONCLUSION

Most PTCL relapses were detected before planned SI, and most patients had symptoms with relapse. Only 3 patients (5.2%) were completely asymptomatic at relapse, suggesting a limited utility of routine imaging for detecting PTCL relapses.

Rethinking clinical response and outcome assessment in a biologic age

Standardized response criteria for lymphoma are critical for the evaluation of new therapies. Widely adopted recommendations, most recently the Lugano classification, have been developed primarily for assessment of conventional chemotherapeutic regimens. More recently, several classes of drugs, including immunomodulatory agents, B cell receptor pathway targeting kinases, and checkpoint (PD-1, PDL-1) inhibitors have demonstrated impressive activity in a broad range of histologies. However, they may be associated with features during treatment suggestive of progressive disease despite clinical benefit. Immune response criteria have been proposed for solid tumors, and a modification is needed to be more applicable to lymphomas. Following treatment, conservative use of imaging is recommended based on clinical indications. As newer targeted agents with unique mechanisms of action are developed, current response and follow-up criteria must be made sufficiently flexible for optimal evaluation.

PET-directed therapy in Hodgkin lymphoma: Ready for prime time?

Advances in chemotherapy and radiation therapy have allowed the vast majority of patients with Hodgkin lymphoma to be cured, but some of these patients develop treatment-related complications, including second malignancies, cardiovascular disease, and thyroid disease. Efforts to decrease exposure of patients to more chemotherapy or radiation therapy than is necessary to cure their disease have led to a trend toward shortened treatment regimens in patients with low-risk disease. Predicting which patients will relapse, and therefore might benefit from a more intense treatment regimen, has been a clinical challenge. PET has emerged as a useful modality in the diagnosis and management of Hodgkin lymphoma, and has been studied as a potential tool to help the oncologist to utilize the optimal chemotherapy and radiation therapy regimen for each patient.

Baseline and ongoing PET-derived factors predict detrimental effect or potential utility of 18F-FDG PET/CT (FDG-PET/CT) performed for surveillance in asymptomatic lymphoma patients in first remission

PURPOSE

To identify both clinical and FDG PET/CT-derived factors predicting the occurrence of relapse, or conversely, the likelihood of false positive findings in surveillance FDG-PET/CT studies (PETsv).

METHODS

The study included 149 asymptomatic patients with Hodgkin's lymphoma (HL) (n = 55) or diffuse large B cell lymphoma (DLBCL) (n = 94) in first remission. PETSv studies were performed 12, 18, 24 and 36 months thereafter. Logistic regression analysis was performed to identify clinical and imaging-derived predictors of either PET-detected relapse or false-positive (FP) results. Tested clinical variables were: 1) age, 2) HL vs. DLBCL, 3) stage of disease, 4) bulky disease, 5) previous radiotherapy. PET/CT-derived variables were: 1) maximum standardized uptake value at baseline, 2) size-incorporated maximum standardized uptake value (SIMaxSUV) at baseline, 3) positive interim PET(PET-2), 4) presence of hot spots likely to be unrelated to the disease in final PET, 5) residual non-FDG avid mass.

RESULTS

Accuracy was 88 % for PETsv1, 95 % for PETsv2, 95 % for PETsv3 and 91 % for PETsv4. However, PPV was relatively low in all PETsv. Best predictors of relapse were result of interim PET, HL versus NHL type, SIMaxSUV, age ≥ 60. Best predictors of FP were previous radiotherapy and hot spots unrelated to the disease in final PET.

CONCLUSIONS

The present study confirms the need of restricting the use of surveillance PET/CT to patients at high risk of relapse. Information derived from PET/CT performed at baseline (metabolic disease burden), in the course (PET2) and at the end of therapy (unrelated hot spots) can help to select high-risk patients and also to identify patients more likely to present equivocal findings at PETsv.

Value of surveillance studies for patients with stage I to II diffuse large B-cell lymphoma in the rituximab era

BACKGROUND

The role of surveillance studies in limited-stage diffuse large B-cell lymphoma (DLBCL) in the rituximab era has not been well defined. We sought to evaluate the use of imaging (computed tomography [CT] and positron emission tomography [PET]-CT) scans and lactate dehydrogenase (LDH) in surveillance of patients with stage I to II DLBCL.

METHODS

A retrospective analysis was performed of patients who received definitive treatment between 2000 and 2013.

RESULTS

One hundred sixty-two consecutive patients with stage I to II DLBCL were treated with chemotherapy +/- rituximab, radiation, or combined modality therapy. The 5-year rates of overall survival (OS) and freedom from progression (FFP) were 81.2% and 80.8%, respectively. Of the 162 patients, 124 (77%) were followed up with at least 1 surveillance PET scan beyond end-of-treatment scans; of those, 94 of 124 (76%) achieved a complete metabolic response on PET scan after completion of chemotherapy, and this was associated with superior FFP (P=.01, HR=0.3) and OS (P=.01, HR 0.3). Eighteen patients experienced relapse after initial response to therapy. Nine relapses were initially suspected by surveillance imaging studies (8 PET, 1 CT), and 9 were suspected clinically (5 by patient-reported symptoms and 4 by symptoms and physical examination). No relapses were detected by surveillance LDH. The median duration from initiation of treatment to relapse was 14.3 months among patients with relapses suspected by imaging, and 59.8 months among patients with relapses suspected clinically (P=.077). There was no significant difference in OS from date of first therapy or OS after relapse between patients whose relapse was suspected by imaging versus clinically. Thirteen of 18 patients underwent successful salvage therapy after relapse.

CONCLUSIONS

A complete response on PET scan immediately after initial chemotherapy is associated with superior FFP and OS in stage I to II DLBCL. The use of PET scans as posttreatment surveillance is not associated with a survival advantage. LDH is not a sensitive marker for relapse. Our results argue for limiting the use of posttreatment surveillance in patients with limited-stage DLBCL.

(18)F-fluorodeoxyglucose positron-emission tomography-computed tomography to diagnose recurrent cancer

Background:

Sometimes the diagnosis of recurrent cancer in patients with a previous malignancy can be challenging. This prospective cohort study assessed the clinical utility of ¹⁸F-fluorodeoxyglucose positron-emission tomography-computed tomography (¹⁸F-FDG PET-CT) in the diagnosis of clinically suspected recurrence of cancer.

Methods:

Patients were eligible if cancer recurrence (non-small-cell lung (NSCL), breast, head and neck, ovarian, oesophageal, Hodgkin's or non-Hodgkin's lymphoma) was suspected clinically, and if conventional imaging was non-diagnostic. Clinicians were asked to indicate their management plan before and after ¹⁸F-FDG PET-CT scanning. The primary outcome was change in planned management after ¹⁸F-FDG PET-CT.

Results:

Between April 2009 and June 2011, 101 patients (age, median 65 years; 55% female) were enroled from four cancer centres in Ontario, Canada. Distribution by primary tumour type was: NSCL (55%), breast (19%), ovarian (10%), oesophageal (6%), lymphoma (6%), and head and neck (4%). Of the 99 subjects who underwent ¹⁸F-FDG PET-CT, planned management changed after ¹⁸F-FDG PET-CT in 52 subjects (53%, 95% confidence interval (CI), 42–63%); a major change in plan from no treatment to treatment was observed in 38 subjects (38%, 95% CI, 29–49%), and was typically associated with ¹⁸F-FDG PET-CT findings that were positive for recurrent cancer (37 subjects). After 3 months, the stated post-¹⁸F-FDG PET-CT management plan was actually completed in 88 subjects (89%, 95% CI, 81–94%).

Conclusion:

In patients with suspected cancer recurrence and conventional imaging that is non-diagnostic, ¹⁸F-FDG PET-CT often provides new information that leads to important changes in patient management.

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.

Recommendations for initial evaluation, staging, and response assessment of Hodgkin and non-Hodgkin lymphoma: the Lugano classification

The purpose of this work was to modernize recommendations for evaluation, staging, and response assessment of patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). A workshop was held at the 11th International Conference on Malignant Lymphoma in Lugano, Switzerland, in June 2011, that included leading hematologists, oncologists, radiation oncologists, pathologists, radiologists, and nuclear medicine physicians, representing major international lymphoma clinical trials groups and cancer centers. Clinical and imaging subcommittees presented their conclusions at a subsequent workshop at the 12th International Conference on Malignant Lymphoma, leading to revised criteria for staging and of the International Working Group Guidelines of 2007 for response. As a result, fluorodeoxyglucose (FDG) positron emission tomography (PET)–computed tomography (CT) was formally incorporated into standard staging for FDG-avid lymphomas. A modification of the Ann Arbor descriptive terminology will be used for anatomic distribution of disease extent, but the suffixes A or B for symptoms will only be included for HL. A bone marrow biopsy is no longer indicated for the routine staging of HL and most diffuse large B-cell lymphomas. However, regardless of stage, general practice is to treat patients based on limited (stages I and II, nonbulky) or advanced (stage III or IV) disease, with stage II bulky disease considered as limited or advanced disease based on histology and a number of prognostic factors. PET-CT will be used to assess response in FDG-avid histologies using the 5-point scale. The product of the perpendicular diameters of a single node can be used to identify progressive disease. Routine surveillance scans are discouraged. These recommendations should improve evaluation of patients with lymphoma and enhance the ability to compare outcomes of clinical trials.

Role of routine imaging in detecting recurrent lymphoma: A review of 258 patients with relapsed aggressive non-Hodgkin and Hodgkin lymphoma

After first-line therapy, patients with Hodgkin lymphoma (HL) and aggressive non-HL are followed up closely for early signs of relapse. The current follow-up practice with frequent use of surveillance imaging is highly controversial and warrants a critical evaluation. Therefore, a retrospective multicenter study of relapsed HL and aggressive non-HL (nodal T-cell and diffuse large B-cell lymphomas) was conducted. All included patients had been diagnosed during the period 2002-2011 and relapsed after achieving complete remission on first-line therapy. Characteristics and outcome of imaging-detected relapses were compared with other relapses. A total of 258 patients with recurrent lymphoma were included in the study. Relapse investigations were initiated outside preplanned visits in 52% of the patients. Relapse detection could be attributed to patient-reported symptoms alone or in combination with abnormal blood tests or physical examination in 64% of the patients. Routine imaging prompted relapse investigations in 27% of the patients. The estimated number of routine scans per relapse was 91-255 depending on the lymphoma subtype. Patients with imaging-detected relapse had lower disease burden (P = 0.045) and reduced risk of death following relapse (hazard ratio = 0.62, P = 0.02 in multivariate analysis). Patient-reported symptoms are still the most common factor for detecting lymphoma relapse and the high number of scans per relapse calls for improved criteria for use of surveillance imaging. However, imaging-detected relapse was associated with lower disease burden and a possible survival advantage. The future role of routine surveillance imaging should be defined in a randomized trial.

Midtreatment evaluation of lymphoma response to chemotherapy by volume perfusion computed tomography

OBJECTIVE

The aim of this study was to search for chemotherapy-induced perfusion changes of diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma at midtreatment versus baseline volume perfusion computed tomography (VPCT).

METHODS

Forty-five consecutive patients with untreated diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma received VPCT examinations of the tumor bulk at baseline and during chemotherapy (midtreatment). Blood flow (BF), blood volume (BV), and transit constant (K-trans) were determined. Treatment response was categorized according to the Cheson criteria into complete or partial remission and stable or relapsed/progressive disease.

RESULTS

Midtreatment follow-up showed a reduction in BF, BV, and K-trans in all lymphoma subtypes compared with baseline. The reduction in BV was less pronounced in larger tumors. Notably, BF, BV, and K-trans decreased in the responders (complete remission/partial remission) when compared with the nonresponders (stable or relapsed/progressive disease). Less than 10% reduction in BF was shown to be the best VPCT criterion for the identification of nonresponse.

CONCLUSIONS

Chemotherapy-induced perfusion changes in responders are recognizable at midtreatment VPCT.

Surveillance imaging for lymphoma: pros and cons

There is no international consensus on the optimal frequency or duration of computed tomography or positron emission tomography scanning for surveillance in patients who achieve complete remission after initial therapy for lymphoma. Although some clinical practice guidelines suggest periodic imaging is reasonable, others suggest little or no benefit to this practice. From a theoretical perspective, the frequency and duration of surveillance imaging is largely dependent upon the lymphoma subtype. Aggressive lymphomas with a fast growth rate will require surveillance more frequently and for a shorter duration compared to the indolent lymphomas. Historically, relapse has been detected in a majority of patients based upon clinically evident signs and symptoms. Currently, no study has demonstrated an overall survival difference for patients with relapse detected by imaging as opposed to clinical evaluation, although one study did demonstrate a lower second-line International Prognostic Index in patients with relapse detected by surveillance imaging. Enthusiasm for this finding has been tempered by recent studies highlighting the potential long-term risk of secondary malignancies because of ionizing radiation exposure from diagnostic imaging. These factors along with the significant costs associated with diagnostic imaging have contributed to an ongoing debate regarding the relative costs, risks, and benefits of radiographic surveillance. Herein we present perspectives for and against routine surveillance imaging in an effort to facilitate a better understanding of the issues relevant to what is ultimately a clinical decision made by an oncologist and his or her patient.

Relapse after treatment of pediatric Hodgkin lymphoma: outcome and role of surveillance after end of therapy

BACKGROUND

The outcome of treatment for pediatric Hodgkin lymphoma (HL) is excellent using chemotherapy and radiation. However, a minority of patients will relapse after treatment, but additional therapy achieves durable second remission in many cases. The optimal surveillance strategy after modern therapy for HL has not been well defined.

PROCEDURES

We reviewed the outcomes of pediatric patients with HL treated between 1990 and 2006 to determine the primary event that led to the detection of relapse. We determined the probability of relapse detection by routine follow-up procedures, including history, physical examination, laboratory tests, and imaging, and determined the impact of each of these screening methods on the likelihood of survival after relapse.

RESULTS

Relapse occurred in 64 of 402 evaluable patients (15.9%) at a median of 1.7 years from the time of diagnosis. The majority of relapses (60%) were diagnosed at a routine visit, and patient complaint was the most common initial finding that led to a diagnosis of relapse (47% of relapses). An abnormal finding on physical examination was the primary event in another 17% of relapses, and imaging abnormalities led to the diagnosis in the remaining 36%. Laboratory abnormalities were never the primary finding. The method of detection of relapse and timing (whether detected at a routine visit or an extra visit) did not impact survival.

CONCLUSIONS

In pediatric HL, most relapses are identified through history and physical examination. Frequent imaging of asymptomatic patients does not appear to impact survival and is probably not warranted.

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.

[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.

18F-FDG-PET/CT in lymphoma: two decades of experience

The use of (18)F-FDG-PET/CT has changed the management of patients with lymphoma for the last two decades. This technique improves initial staging of the disease, making a prognostic approach and appropriate treatment planning, as well as monitoring therapy response of lymphoma. However, there are still controversial issues in medical literature that impact on daily clinical practice. This comprehensive literature review summarizes the current information regarding the potential use of (18)F-FDG-PET/CT in patients with lymphoma, highlighting the main applications and the current dilemmas for the nuclear medicine physicians at the time of the evaluation of these studies, trying to standardize criteria for its assessment, particularly in restaging and therapy monitoring.

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.

Positron emission tomography/computed tomography surveillance in patients with Hodgkin lymphoma in first remission has a low positive predictive value and high costs

BACKGROUND

The value of performing post-therapy routine surveillance imaging in patients with Hodgkin lymphoma is controversial. This study evaluates the utility of positron emission tomography/computed tomography using 2-[18F]fluoro-2-deoxyglucose for this purpose and in situations with suspected lymphoma relapse.

DESIGN AND METHODS

We conducted a multicenter retrospective study. Patients with newly diagnosed Hodgkin lymphoma achieving at least a partial remission on first-line therapy were eligible if they received positron emission tomography/computed tomography surveillance during follow-up. Two types of imaging surveillance were analyzed: "routine" when patients showed no signs of relapse at referral to positron emission tomography/computed tomography, and "clinically indicated" when recurrence was suspected.

RESULTS

A total of 211 routine and 88 clinically indicated positron emission tomography/computed tomography studies were performed in 161 patients. In ten of 22 patients with recurrence of Hodgkin lymphoma, routine imaging surveillance was the primary tool for the diagnosis of the relapse. Extranodal disease, interim positron emission tomography-positive lesions and positron emission tomography activity at response evaluation were all associated with a positron emission tomography/computed tomography-diagnosed preclinical relapse. The true positive rates of routine and clinically indicated imaging were 5% and 13%, respectively (P = 0.02). The overall positive predictive value and negative predictive value of positron emission tomography/computed tomography were 28% and 100%, respectively. The estimated cost per routine imaging diagnosed relapse was US$ 50,778.

CONCLUSIONS

Negative positron emission tomography/computed tomography reliably rules out a relapse. The high false positive rate is, however, an important limitation and a confirmatory biopsy is mandatory for the diagnosis of a relapse. With no proven survival benefit for patients with a pre-clinically diagnosed relapse, the high costs and low positive predictive value make positron emission tomography/computed tomography unsuitable for routine surveillance of patients with Hodgkin lymphoma.

Impact of FDG-PET/CT in the management of lymphoma

Since the introduction of (67)Gallium-citrate 30 years ago, nuclear medicine has played an important role in the evaluation of malignant lymphoma. During that time, several radiotracers were evaluated as potential alternatives for the diagnosis of lymphoma, but the introduction of (18)F-fluorodeoxyglucose PET (FDG-PET) marked a major turning point. FDG-PET took over most of the role of gallium, and is now an essential tool in the diagnosis of lymphoma. FDG-PET is increasingly being used for assessment of the tumor staging prior to treatment, for evaluating the response to treatment, and for monitoring the early reactions to therapy to predict the final outcome. FDG-PET has been shown to have more accurate diagnostic capability than conventional CT and MRI for distinguishing the tumor necrosis and residual masses frequently seen after therapy in lymphoma patients without any clinical and biochemical manifestation. Malignant lymphoma is the first disease for which FDG-PET was adopted as a tool for response assessment in the international standard criteria. However, lymphoma does not always display a clear high uptake, and there are some pitfalls in assessing the response to therapy. This review will highlight the most important applications of FDG-PET in lymphoma, focusing on the advantages and pitfalls of this imaging, and past and ongoing efforts to standardize the use of FDG-PET, particularly in response to assessment and therapy monitoring.

Underperformance of gallium-67 scan is greater in relapse than in initial staging, compared with FDG PET

PURPOSE

The purpose of this study is to evaluate the performance of gallium-67 scan (GS) and F-18 fluorodeoxyglucose (FDG) PET scan in lymphoma staging and recurrence detection by comparing the 2 imaging studies in the same patient.

MATERIALS AND METHODS

A total of 42 patients from the period between July 2002 and May 2006 were included in this study. Of the 42 patients, 6 had Hodgkin disease and 36 had non-Hodgkin lymphomas. All of them underwent one or more FDG PET scans and also underwent corresponding GS performed within 7 days of FDG PET, for staging or detection of lymphoma recurrence. Among the non-Hodgkin lymphoma cases, 18 were diffuse large B-cell lymphoma, 10 were follicular center cell lymphoma, and 8 were of other types. Of the total 46 pairs of imaging performed in these 42 patients, 27 were for staging, and 19 for restaging after recurrence.

RESULTS

In all these studies, FDG PET detected 230 lesion sites, whereas GS detected 85 lesion sites. All of the lesions detected by GS were noted on FDG PET, whereas GS detected only 37.0% of the lesions detected by FDG PET. Among the 27 studies for staging, FDG PET detected 120 lesions, whereas GS detected 68 lesions (56.7%). In the 19 images taken for relapse, FDG PET detected 110 lesions, whereas GS detected only 17 (15.5%).

CONCLUSIONS

FDG PET is superior to GS in staging and detecting all types of lymphoma. The difference is notably more significant in recurrence detection.

18F-FDG-PET/CT in the surveillance of patients with lymphoma: detection of asymptomatic recurrences

AIM

To assess the diagnostic accuracy of (18)F-FDG-PET/CT in detecting asymptomatic recurrences in patients with lymphoma. To define uptake patterns of recurrence indicative of recurrence.

MATERIAL AND METHODS

Those patients with lymphoma who fulfilled the following inclusion criteria of clinical complete remission and negative PET/CT study were included retrospectively and longitudinally. Conventional surveillance of these patients was performed only by (18)F-FDG PET/CT following a standardized procedure. Pathologic locations (supra- and infradiaphragmatic) and their character (single or multiple) were analyzed in order to determine reliable metabolic patterns of recurrence. The final diagnosis was established by histopathological analysis or clinical follow-up greater than 8 months.

RESULTS

A total of 199 explorations belonging to 106 patients with lymphoma were included. Of these patients, 59 had Hodgkin's lymphoma and 47 non-Hodgkin's lymphoma. There was suspicion of relapse from the metabolic point of view in 27 of the PET/CT scans. Of these, 14 (10 patients) were false positive (FP), and 13 (8 patients) true positive. The remaining studies were true negative, no false negatives being detected. The pattern most frequently related to recurrence was infradiaphragmatic lymph node involvement while most of the FP had isolated supradiaphragmatic involvement. Sensitivity, specificity, PPV, NPV and diagnostic accuracy of PET/CT parameters for the study were 100%, 92%, 48%, 100% and 93%, respectively.

CONCLUSION

(18)F-FDG-PET/CT is a sensitive technique in the detection of asymptomatic recurrences in patients with lymphoma during their follow-up. Multiple character and infradiaphragmatic locations were the patterns that best correlated to the diagnosis of recurrence.

Role of Functional Imaging in the Management of Lymphoma

18-F-fluorodeoxyglucose (FDG) –positron emission tomography (PET), and more recently PET/computed tomography (CT), is the most sensitive and specific imaging technique currently available for patients with lymphoma. Nevertheless, despite being increasingly used in pretreatment assessment, midtreatment evaluation of response, post-treatment restaging, and surveillance during follow-up of patients with lymphoma, its impact on clinical outcome in most clinical situations remains to be confirmed. PET/CT provides its greatest clinical benefit in the post-treatment evaluation of Hodgkin's lymphoma and diffuse large B-cell lymphoma; however, the role of metabolic imaging in other indications and in other histologies remains to be demonstrated. Ongoing risk-adapted studies will hopefully provide evidence for clinical improvement on the basis of altering treatment as a result of interim PET results. Efforts are ongoing to better standardize the conduct and interpretation of FDG-PET scans. FDG-PET has the potential to improve lymphoma patient management; however, its usefulness will likely vary by histology, stage, therapy, and clinical setting.

PET-CT Imaging of Lymphoma

PET-CT is now the mainstay for imaging lymphoma patients. The complimentary nature of the metabolic and anatomic information provided by a PET-CT examination has become an essential component of patient management, complimenting clinical and laboratory criteria used in staging, restaging, and therapy monitoring. The nature of a particular lymphoma subtype and the patient’s clinical presentation will determine the extent PET-CT imaging is best employed in a particular patient’s management.