Positron emission tomography scanning in the assessment of patients with lymphoma

Managing lymphoma with non-FDG radiotracers: current clinical and preclinical applications

Nuclear medicine imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have played a prominent role in lymphoma management. PET with [(18)F]Fluoro-2-deoxy-D-glucose (FDG) is the most commonly used tool for lymphoma imaging. However, FDG-PET has several limitations that give the false positive or false negative diagnosis of lymphoma. Therefore, development of new radiotracers with higher sensitivity, specificity, and different uptake mechanism is in great demand in the management of lymphoma. This paper reviews non-FDG radiopharmaceuticals that have been applied for PET and SPECT imaging in patients with different types of lymphoma, with attention to diagnosis, staging, therapy response assessment, and surveillance for disease relapse. In addition, we introduce three radiolabeled anti-CD20 antibodies for radioimmunotherapy, which is another important arm for lymphoma treatment and management. Finally, the relatively promising radiotracers that are currently under preclinical development are also discussed in this paper.

Revisiting the Marrow Metabolic Changes after Chemotherapy in Lymphoma: A Step towards Personalized Care

Purpose. The aims were to correlate individual marrow metabolic changes after chemotherapy with bone marrow biopsy (BMBx) for its potential value of personalized care in lymphoma. Methods. 26 patients (mean age, 58 ± 15 y; 13 female, 13 male) with follicular lymphoma or diffuse large B-cell lymphoma, referred to FDG-PET/CT imaging, who had BMBx from unilateral or bilateral iliac crest(s) before chemotherapy, were studied retrospectively. The maximal standardized uptake value (SUV) was measured from BMBx site over the same area on both initial staging and first available restaging FDG-PET/CT scan. Results. 35 BMBx sites in 26 patients were evaluated. 12 of 35 sites were BMBx positive with interval decrease in SUV in 11 of 12 sites (92%). The remaining 23 of 35 sites were BMBx negative with interval increase in SUV in 21 of 23 sites (91%). The correlation between SUV change over the BMBx site before and after chemotherapy and BMBx result was significant (P < 0.0001). Conclusions. This preliminary result demonstrates a strong correlation between marrow metabolic changes (as determined by FDG PET) after chemotherapy and bone marrow involvement proven by biopsy. This may provide a retrospective means of personalized management of marrow involvement in deciding whether to deliver more extended therapy or closer followup of lymphoma patients.

Cross-sectional evaluation of thoracic lymphoma

Thoracic lymphomas most frequently involve mediastinal lymph nodes in the anterior mediastinum and paratracheal areas. The lymphomas may also involve lung, thymus, pleura, pericardium, chest wall, and the breast and their radiologic manifestations are diverse. Lymphomas (mostly BALT lymphoma and large B-cell lymphoma) may arise primarily from the lung with various imaging features including single or multiple nodule(s) and area(s) of consolidation. CT is currently the most important imaging modality for the evaluation of thoracic lymphoma but FDG PET also plays a crucial role in the clinical management of these cases.

FDG PET and PET/CT in the Management of Pediatric Lymphoma Patients

Fluorodeoxyglucose (FDG) PET has an ever-increasing role in the management of Hodgkin's and non-Hodgkin's lymphomas, which has been demonstrated in numerous studies in the adult population. In children and adolescents, however, only a limited number of studies have investigated the role of FDG PET in lymphoma. This article reviews the currently available literature on the clinical application of FDG PET in the management of childhood lymphoma. The authors believe that FDG PET (and especially PET/CT) is a valuable imaging modality in the initial diagnosis, response assessment, and post-therapy residual evaluation of Hodgkin's and FDG-avid non-Hodgkin's lymphomas in children and adolescents, and will have a significant impact on the clinical management of pediatric lymphoma.

Cross-sectional evaluation of thoracic lymphoma

In patients who have lymphoma, the presence and distribution of thoracic involvement is important in both tumor staging and treatment. Thoracic involvement in Hodgkin lymphoma (HL) is more common than in non-Hodgkin lymphoma (NHL). In HL, mediastinal lymphadenopathy with contiguous spread is a hallmark, and lung parenchymal involvement at the initial presentation is almost always associated with mediastinal lymphadenopathy. NHL is more heterogeneous and generally presents at a more advanced stage than HL. Most often, mediastinal involvement occurs as a disseminated or recurrent form of extrathoracic lymphoma. Bulky mediastinal disease with compression of adjacent structures can occur, particularly with high-grade subtypes of NHL and isolated lung disease without mediastinal lymphadenopathy can occur in contrast to HL.

FDG PET and evaluation of posttherapeutic residual tumors in pediatric oncology: preliminary experience

INTRODUCTION

Residual masses are an important problem in oncology. The determination of their nature (fibrosis or active tumor) is crucial. The place of 18F-fluorodeoxyglucose -positron emitting tomography (PET) as a new imaging device remains to be determined in this context.

OBJECTIVES

To evaluate the place of 18F-fluorodeoxyglucose -PET in the prediction of the nature of residual masses in children with solid tumors.

PATIENTS AND METHODS

Between January 2004 and January 2006, 238 PETs were performed in children followed up in the pediatric oncology and hematology departments. This was a monocentric retrospective review of the medical files of 18 children, in whom the main objective of the PET was to evaluate a residual mass. The sex ratio was 1/5; the median age 100 months (range, 34 to 180 mo). The underlying diseases were Hodgkin disease (n=5), lymphomas (n=5), osteosarcomas (n=3), rhabdomyosarcomas (n=2), and others (n=3). The final diagnostic (remission or persistent disease) was given by follow-up (median, 18 mo; range, 18 to 40), together with clinical, radiologic, and biopsy (in 6 cases) data.

RESULTS

PET was negative in 13 cases and positive in 5, among them 4 patients relapsed. Among the 13 negative PETs, there was 1 relapse and 12 remissions. The respective value of PET sensibility and specificity were 0.8 and 0.92, respectively. Positive and negative predictive values were 0.8 and 0.92, respectively.

CONCLUSION

On the basis of these preliminary results, PET seems to be an interesting tool to assess the nature of posttherapeutic residual masses in children, regardless of the underlying malignancy. Its role needs to be confirmed and further explored by multicentric studies tailored according to the underlying disease.

18F-FDG PET for posttherapy assessment of Hodgkin's disease and aggressive Non-Hodgkin's lymphoma: a systematic review

Although studies have shown that (18)F-FDG PET, when used to assess the response of malignant lymphoma after treatment, has a strong ability to predict relapse, its diagnostic accuracy in clinical practice remains unclear. The aim of this study was to systematically review the diagnostic accuracy of (18)F-FDG PET in detecting residual disease at the completion of first-line therapy of Hodgkin's disease (HD) and aggressive non-Hodgkin's lymphoma (NHL).

METHODS

We searched relevant articles from 1966 to July 2006 using MEDLINE, EMBASE, SCOPUS, Biological Abstracts, bibliographies, review articles, and textbooks without language restriction. One assessor (for non-English-language studies) or 2 assessors (for English-language studies) independently reviewed each article to abstract relevant study characteristics and results. Relevant individual patient data or subgroup data were provided by the investigators if they were unavailable from the publications. We estimated summary receiver operating characteristic curves and confidence regions for summary sensitivity and specificity.

RESULTS

Nineteen studies consisting of 474 HD and 254 aggressive NHL patients were included. These studies had heterogeneity and suboptimal methodologic quality and reporting. Reported ranges for the sensitivity and specificity of (18)F-FDG PET in predicting disease relapse were 0.50-1.00 and 0.67-1.00, respectively, for HD and 0.33-0.77 and 0.82-1.00, respectively, for NHL. These estimates were similar when conventional imaging tests showed a residual mass. For HD studies, the summary receiver operating characteristic curves were similar irrespective of whether a residual mass was detected by conventional tests. Factors explaining the variability of diagnostic estimates were not identified.

CONCLUSION

Although currently available evidence is still limited, (18)F-FDG PET seems to have good diagnostic accuracy for assessing residual HD at the completion of first-line treatment. Clinical data on this use of (18)F-FDG PET for aggressive NHL are more limited. Prospective studies with a more rigorous research design, conduct, and reporting would more reliably reveal the clinical diagnostic accuracy of this imaging modality.

PET and PET/CT in management of the lymphomas

Within recent years, F-18 fluorodeoxyglucose (FDG) PET has become the most important nuclear medicine and radiology imaging modality in the management of lymphoma. FDG-PET detects more disease sites and involved organs than conventional staging procedures, including CT, and has a large influence on staging. FDG-PET performed during and after therapy seems to provide considerable prognostic information. The impact on patient outcome is not clear, however, because no controlled trials have yet been conducted and follow-up periods are generally short.

The role of FDG PET in the management of lymphoma: what is the evidence base?

[18F]Fluorodeoxyglucose positron emission tomography (18F-FDG PET) is playing an increasing role in the management of both Hodgkin and non-Hodgkin lymphoma, offering potential advantages in the accuracy of disease assessment at a number of points in the management pathway. This review evaluates the current level of confidence in the use of PET technology in (1) initial staging, (2) the assessment of early response to chemotherapy, (3) the assessment of residual masses at completion of initial treatment, (4) follow-up, and (5) radiotherapy planning.

False-positive restaging PET scans involving the spleen in two patients with aggressive non-Hodgkin lymphoma

We report 2 patients with aggressive non-Hodgkin lymphoma who had positive restaging PET scans limited to the spleen and no significant uptake in nodal areas of previously known disease. Examination of the resected spleens from both patients revealed extensive inflammation surrounding necrotic tumor with no evidence of viable lymphoma or active infection. It is suggested that close observation of such patients for evidence of progressive disease may be considered as opposed to immediate intervention.

Value of PET restaging after chemotherapy for non-Hodgkin’s lymphoma: Implications for consolidation radiotherapy

PURPOSE/OBJECTIVE

Patients treated for non-Hodgkin's Lymphoma (NHL) frequently are restaged for response using positron emission tomography (PET) scanning. This study investigates the role of subsequent consolidation radiation therapy (CRT) based on PET response to chemotherapy.

MATERIALS/METHODS

An IRB-approved database was queried for patients who underwent PET scans after chemotherapy for NHL between 1995 and 2004; 77 patients were identified. To determine benefit of CRT, overall survival and local control were assessed with median follow-up of 39.8 months (range, 2-125 months).

RESULTS

Median age of patients was 53 (range, 18-82 years). Multivariate analysis adjusted for age, indolent vs. aggressive histology, and time from chemotherapy to PET revealed PET positive scans (RR = 30.5; 95%CI = 5.9, 156.4), lack of RT (RR = 5.25; 95%CI = 1.26, 21.79), and Stage III/IV presentation (RR = 4.35; 95%CI = 1.03, 20) predicted increased likelihood of recurrence. Patients with positive PET scans after chemotherapy had significantly higher risk of relapse than those with negative scans (58.1% vs. 15.2%; p < 0.0001), although not everyone with positive scans recurred. Patients with positive PET scans receiving RT were not protected from relapse (63.2% relapse with RT, 50% relapse without RT; p = 0.71); in fact, over half the relapses in patients receiving RT for persistently positive PET scans were in-field. Crude 2 year OS was significantly different between PET positive and PET negative cohorts (p < 0.01).

CONCLUSIONS

While RT may control relapse in PET negative patients, NHL patients who remain PET positive after chemotherapy are not well managed by RT alone.

Positron emission tomography imaging for lymphoma

PURPOSE OF REVIEW

To review the current role and the limitations of F-fluorodeoxygenase positron emission tomography in the management of lymphoma, with a particular focus on studies published since January 2004.

RECENT FINDINGS

F-fluorodeoxygenase positron emission tomography should be routinely performed at the initial diagnosis of patients with suffering from Hodgkin's disease because it adds useful informations to conventional staging techniques. Residual F-fluorodeoxygenase uptake is an important prognostic factor after one or a few cycles of chemotherapy, but it is clearly too early to change patient treatment on the basis of F-fluorodeoxygenase positron emission tomography results. F-fluorodeoxygenase positron emission tomography is the best noninvasive imaging technique after treatment; however, it is always indicated to correlate positron emission tomography findings with clinical data, other imaging modalities, a biopsy, or all three to reduce the risk of false positive results. There are some concerns about the positive predictive value of positron emission tomography after treatment, especially in childhood lymphoma. Clinicians should be aware of positron emission tomography findings in specific clinical conditions in this patient population. F-fluorodeoxygenase positron emission tomography combined with computed tomography offers advantages over the two used separately and read side by side. It may be particularly useful for the planning of radiation therapy or for the planning of a surgical biopsy. Several studies have shown that F-fluorodeoxygenase positron emission tomography is definitively superior to Ga scintigraphy. New radiotracers such as F-fluorothymidine may be useful for the noninvasive assessment of proliferation in vivo.

SUMMARY

F-fluorodeoxygenase positron emission tomography has become the most important nuclear medicine imaging modality in the field of lymphoma. It should be routinely used in the treatment of lymphoma patients.

Clinical features and management of tumors affecting the lacrimal drainage apparatus

PURPOSE

To report the clinical features of a series of patients with lacrimal drainage apparatus tumors and present guidelines for management based on histopathology.

METHODS

A non-comparative retrospective chart review of the clinical, imaging, and pathologic findings of 37 patients presenting to four regional orbital surgery departments with tumors affecting the lacrimal drainage apparatus between 1990 and 2004.

RESULTS

There were 37 patients, of whom 62% were male. The mean age at referral was 54 years. Epiphora, a palpable mass, and dacryocystitis were the most common presentations. Two thirds of the tumors were epithelial, with carcinomas being the most frequent (38%), followed by papillomas (27%). Lymphomas were the most common nonepithelial malignancy (30%). Epithelial tumors were more common in men (87%), whereas lymphomas were more common in women (57%). Treatment modalities included surgery, in addition to radiotherapy and/or chemotherapy and immunotherapy. Mean follow-up was 38 months. Thirty-three patients (89%) remain alive without evidence of disease and 4 patients died of recurrence and/or metastases.

CONCLUSIONS

Lacrimal drainage apparatus tumors require careful initial management to ensure adequate local and systemic disease control. Atypical mucosa encountered during dacryocystorhinostomy should be biopsied and small papillomas or pedunculated tumors excised and analyzed with frozen sections. If a diffuse or infiltrative mass is encountered, it should be biopsied and managed on the basis of histopathology and extent of disease. Lymphomas should be treated according to protocols, whereas noninvasive carcinoma and extensive papillomas require complete excision of the system. Invasive disease requires en bloc excision. Long-term follow-up is essential for early detection of recurrence.

Utility of FDG-PET/CT in follow-up of children treated for Hodgkin and non-Hodgkin lymphoma

Positron emission tomography using F-flurodeoxyglucose (FDG-PET) is considered an excellent tool for staging and monitoring disease status in adults with lymphoma. We retrospectively reviewed results of PET/CT and diagnostic computed tomography (CT) scans performed during follow-up after completion of therapy in 41 children <18 years of age with Hodgkin lymphoma and non-Hodgkin lymphoma. PET/CT scan with uptake greater than that of the liver was considered positive. Uptake that increased over the background but less than in the liver was equivocal. Clinical outcomes were obtained from medical records. Thirteen (32%) had a positive PET/CT scan and an equal number had equivocal scans in a median follow-up of 2.3 years. Diagnostic CT scans revealed new findings in 13 (32%) and persistent abnormalities in 21 (51%) of the children. Five children developed recurrent disease, and one developed a second cancer. No children with equivocal positivity developed recurrent disease. PET/CT scan was 95% sensitive, with a positive predictive value (PPV) of 53%. Diagnostic CT was 79% sensitive, with a PPV of 52%. We conclude that a negative PET/CT scan during routine follow-up for lymphoma in children strongly suggests absence of recurrence but a positive PET/CT and diagnostic CT scans have low PPV and should be interpreted with caution in this setting.

18F-fluoro-deoxy-glucose positron emission tomography (18F-FDG-PET) visualizes follicular lymphoma irrespective of grading

BACKGROUND

18F-fluoro-deoxy-glucose positron emission tomography (18F-FDG-PET) has become a routine measure for staging and follow-up of patients with aggressive lymphoma. By contrast, its usefulness to visualize indolent lymphomas characterized by a lower cellular turnover has not clearly been defined. We have investigated accuracy and clinical usefulness of 18F-FDG-PET in patients with follicular lymphoma (FL).

PATIENTS AND METHODS

A total of 64 patients with FL WHO grade I - III (48, 5, and 11 patients) were imaged at our institution to assess the value of 18F-FDG-PET for imaging of FL of different gradings. A total of 115 scans (48 before therapy and 67 for response assessment after treatment) were performed, and findings were compared to conventional staging including CT-scan of thorax and abdomen, sonography of lymph nodes and bone marrow biopsy.

RESULTS

Overall, 18F-FDG-PET had a sensitivity of 98%, a specificity of 94%, a positive predictive value of 95% and a negative predictive value of 98%. These results were significantly more accurate (P = 0.023) than the conventional radiology studies. There was no significant difference (P = 0.093) in the accuracy between patients with indolent (WHO grade I and II) versus aggressive FL (WHO grade III).

CONCLUSION

18F-FDG-PET scan is a reliable method for staging and follow up of patients with nodal FL irrespective of tumor grading.

Combined positron emission tomography/computed tomography imaging of orbital lymphoma

PURPOSE

To report a case of orbital lymphoma with systemic dissemination that was identified and localized by combined positron emission tomography (PET)/computed tomography.

DESIGN

Case report.

METHODS

A 75-year-old woman presented with a 6-month history of painless, progressive fullness of her right upper eyelid. A PET/computed tomography was obtained to provide functional and anatomic assessment of the orbits. An orbitotomy was performed with sub-total excision of the lesion to obtain histologic diagnosis.

RESULTS

The PET/computed tomography scan revealed intensive uptake of tracer in a right orbital mass measuring 2.3 x 1.8 x 2.6 cm. Foci of abnormal tracer uptake were also noted in the right neck, right hilar region, and central abdomen. Histopathologic findings were consistent with follicular cell lymphoma.

CONCLUSIONS

The combination of PET/computed tomography provides accurate and precise information in an expedited manner not offered by alternative imaging modalities. PET/computed tomography imaging should be considered in the evaluation of orbital neoplasms, especially if lymphoma is suspected.

Progress and promise of FDG-PET imaging for cancer patient management and oncologic drug development

2-[(18)F]Fluoro-2-deoxyglucose positron emission tomography (FDG-PET) assesses a fundamental property of neoplasia, the Warburg effect. This molecular imaging technique offers a complementary approach to anatomic imaging that is more sensitive and specific in certain cancers. FDG-PET has been widely applied in oncology primarily as a staging and restaging tool that can guide patient care. However, because it accurately detects recurrent or residual disease, FDG-PET also has significant potential for assessing therapy response. In this regard, it can improve patient management by identifying responders early, before tumor size is reduced; nonresponders could discontinue futile therapy. Moreover, a reduction in the FDG-PET signal within days or weeks of initiating therapy (e.g., in lymphoma, non-small cell lung, and esophageal cancer) significantly correlates with prolonged survival and other clinical end points now used in drug approvals. These findings suggest that FDG-PET could facilitate drug development as an early surrogate of clinical benefit. This article reviews the scientific basis of FDG-PET and its development and application as a valuable oncology imaging tool. Its potential to facilitate drug development in seven oncologic settings (lung, lymphoma, breast, prostate, sarcoma, colorectal, and ovary) is addressed. Recommendations include initial validation against approved therapies, retrospective analyses to define the magnitude of change indicative of response, further prospective validation as a surrogate of clinical benefit, and application as a phase II/III trial end point to accelerate evaluation and approval of novel regimens and therapies.

Evaluation of Therapy for Lymphoma

Positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) is the best noninvasive imaging technique for to assess response in patients suffering from lymphoma. Early response evaluation ("interim PET") after one, a few cycles, or at midtreatment can predict response, progression-free survival, and overall survival. We calculated from data of 7 studies an overall sensitivity to predict treatment failure of 79%, a specificity of 92%, a positive predictive value (PPV) of 90%, a negative predictive value (NPV) of 81%, and an accuracy of 85%. Although it is not yet indicated to change patient management based on residual (18)F-FDG uptake on interim scan in chemotherapy-sensitive patients, prospective studies evaluating the role of an interim PET in patient management clearly are warranted. (18)F-FDG PET also has an important prognostic role in relapsing patients after reinduction chemotherapy before high-dose chemotherapy (HCT) followed by autologous stem cell transplantation (ASCT). However, all chemotherapy-sensitive patients remain candidates for HCT followed by ASCT, even if (18)F-FDG PET showed residual (18)F-FDG uptake. We calculated from data of 3 studies an overestimated risk of relapse in 16% of all PET-positive patients. Some patients with residual (18)F-FDG uptake will have a good outcome after HCT followed by ASCT. (18)F-FDG PET is the imaging technique of choice for end-of-treatment evaluation. However, (18)F-FDG is not specific for tumoral tissue. Active inflammatory lesions and infectious processes can be falsely interpreted as malignant residual cells. However, a negative (18)F-FDG PET cannot exclude minimal residual disease. Consequently, it is always indicated to correlate PET findings with clinical data, other imaging modalities, and/or a biopsy. We calculated, from data of 17 studies in end-of-treatment evaluation, a sensitivity of 76%, a specificity of 94%, a PPV of 82%, a NPV 92%, and an accuracy of 89%.

Imaging of thymoma

Thymomas are the most common mediastinal tumors, usually diagnosed initially by CT. CT scanning can aid in characterization of thymoma and can successfully distinguish thymomas from other benign mediastinal tumors and from lymphoma. However, many of the primary mediastinal masses demonstrate overlap between imaging features and frequently resection is advisable for definitive characterization.