Role of Positron Emission Tomography in Lymphoma

End-of-treatment 18[F]-FDG PET can predict early progression in patients receiving bendamustine-rituximab for follicular lymphoma in first relapse: a prospective West Japan hematology Study Group (W-JHS) NHL01 trial

Response determined by 18[F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)-CT after induction therapy can predict progression-free survival (PFS) in follicular lymphoma (FL). However, little prospective research has examined the significance of PET after second-line therapy. We conducted a prospective multicenter phase II trial (W-JHS NHL01) of bendamustine plus rituximab (BR) without rituximab maintenance for FL in first relapse. This study aimed to evaluate the usefulness of end-of-treatment (EOT)-PET for predicting PFS in FL patients in first relapse. EOT-PET examinations were performed between 6 and 8 weeks from the start of the last BR cycle. The primary endpoint was 1-year PFS. Key secondary endpoints were overall response rate (ORR), complete response rate (CRR), and 1-year overall survival (OS). Seventy-five patients were enrolled, and 8 were excluded from analysis. ORR was 86.6% and CRR was 59.7%. One-year PFS was 88.9% (95% confidence interval [CI] 80.7-94.3%) and 1-year OS in 75 patients was 97.3% (95% CI 89.6-99.3%). One-year PFS was significantly inferior in EOT-PET-positive patients (n = 9) compared with PET-negative patients (n = 58) (77.8% vs. 93.1%; p = 0.02). We confirmed that EOT-PET after second-line BR therapy could predict early progression in FL patients in first relapse.

PET/CT in Hodgkin Lymphoma: An Update

¹⁸F-FDG-PET/CT is now an integral part of the workup and management of patients with Hodgkin's lymphoma (HL). PET/CT is currently routinely performed for staging and for response assessment at the end of treatment. Interim PET/CT is typically performed after 1-4 of 6-8 chemo/chemoimmunotherapy cycles ± radiation for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics such as the standardized uptake value (SUV), metabolic tumor volume, total lesion glycolysis, and their changes with treatment 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. This review highlights the most relevant applications of PET/CT in HL, its strengths and limitations, as well as recent efforts to implement PET/CT-based metrics as promising tools for precision medicine. Finally, the value of PET/CT for response assessment to immunotherapy is discussed.

Interim FDG-PET/CT for therapy monitoring and prognostication in Hodgkin's Lymphoma

The aim of the study was to assess the predictive value of interim FDG-PET/CT (iPET) in patients with Hodgkin's lymphoma (HL) treated with Adriamycin, bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy. A total of 245 consecutive patients with de novo HL between 12/2013 and 12/2017 were evaluated retrospectively. All patients were treated with upfront ABVD, performed PET/CT scans at baseline, after 2 cycles (interim PET, iPET2) or 4 cycles (iPET4) and at the end of therapy, and followed up for at least 6 months after therapy. The response status on iPET was defined according to the standard five-point Deauville scores (DS) as follows: complete metabolic response (CMR, DS 1-3) and non-complete metabolic response (nCMR) (DS 4 and 5). End-of-treatment (EoT) response was assessed by FDG-PET/CT and if needed biopsy confirmation of PET-positive findings. The association between iPET and EoT response was investigated using logistic regression analysis. Survival analysis was performed using the Cox regression hazard model and Kaplan-Meier methods. Sixty-nine patients underwent iPET-2 and 176 iPET-4. No association was found between the timing of iPET and iPET response status (P-value = 0.71). Two hundred and one patients (82%) had iPET-CMR and 44 (18%) iPET -nCMR. iPET was strongly associated with EoT response status: 194/201 (96 .5%) of iPET-CMR had a complete response at the EoT while only 21/44 (47.7%) of patients with iPET-nCMR presented a complete response at EoT (P-value < 0.0001). The median follow-up was 32 months (range 6-81). Patients with iPET-CMR presented a better outcome with 91% 3 y event-free-survival (EFS) and 95% 3 y overall survival (OS) than those with iPET-nCMR (41 and 86%, respectively, P-value < 0.0001). In multivariable analyses, iPET retained an independent prognostic factor of EFS and OS (P-value < 0.0001 and P-value = 0.002, respectively). iPET is highly predictive of outcome of HL patients treated with ABVD and allows to tailor therapy to the individual patient.

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.

Current and future best practice in imaging, staging, and response assessment for Non-Hodgkin's lymphomas: the Specialist Integrated Haematological Malignancy Imaging Reporting (SIHMIR) paradigm shift

Non-Hodgkin's lymphoma (NHL) encompasses over 40 different haematological malignancies, including low and high-grade neoplasms, such as follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) respectively. A key clinical issue in the context of NHL is delayed and inaccurate diagnosis, which contributes adversely to patient morbidity and mortality. This article will address relevant imaging aspects, with particular reference to advancements in NHL imaging, including computed tomography (CT), integrated positron-emission tomography (PET)-CT, and magnetic resonance imaging (MRI). We provide multiparametric (anato-functional) imaging display items, including histological correlation. We will also introduce our original concept of "Specialist Integrated Haematological Malignancy Imaging Reporting" (SIHMIR), a paradigm shift in lymphoma radiology.

FDG-PET/CT imaging findings of hepatic tumors and tumor-like lesions based on molecular background

The usefulness of whole-body 18-fluoro-2-deoxyglucose (FDG)-fluorodeoxyglucose positron emission (PET)/computed tomography (CT) is established for assessment of disease staging, detection of early disease recurrence, therapeutic evaluation, and predicting prognosis in various malignancies; and for evaluating the spread of inflammation. However, the role of FDG-PET/CT for the liver is limited because CT and magnetic resonance imaging (MRI) can provide an accurate diagnosis of most tumors. In addition, in other potentially useful roles there are several pitfalls in the interpretation of FDG uptake in PET/CT imaging. Accurate evaluation demands knowledge of the FDG uptake of each lesion, including potential negative and positive uptakes, and requires an understanding of the underlying background of the molecular mechanisms. The degree of FDG uptake is dependent on cellular metabolic rate and the expression of glucose transporter, hexokinase, and glucose-6-phosphatase, which in turn are closely affected by biological characteristics such as pathological category (e.g., adenocarcinoma, squamous cell carcinoma, small cell cancer, transitional cell cancer, neuroendocrine tumor, sarcoma, lymphoma), tumor differentiation, histological behavior (e.g., solid, cystic, mucinous), and intratumoral alterations (e.g., necrosis, degeneration, hemorrhage). Correlation with the CT and MRI findings, which also precisely depict the pathological findings, is important to avoid misdiagnosis.

FDG-PET/CT Assessment of Pulmonary Sarcoidosis: A Guide for Internists

BACKGROUND

18F-fluorodeoxyglucose positron emission tomography integrated with computed tomography (18-F-FDG-PET/CT) is getting wide consensus in the diagnosis and staging of neoplastic disorders and represents a useful tool in the assessment of various inflammatory conditions.

DISCUSSION

Sarcoidosis is an uncommon disease characterized by the systemic formation of noncaseating granulomas. Lungs are the sites most often affected, and investigation with high resolution computed tomography and biopsy is essential to achieve a correct diagnosis. 18-F-FDGPET/ CT is effective in the assessment of pulmonary sarcoidosis by demonstrating pulmonary and extrathoracic involvement and findings correlate well with pulmonary function in patients affected.

CONCLUSION

This review would illustrate the usefulness and limits of 18-F-FDG-PET/CT in the assessment of pulmonary sarcoidosis.

Surrogate Endpoints and Risk Adaptive Strategies in Previously Untreated Follicular Lymphoma

Follicular lymphoma is the second most common subtype of non-Hodgkin lymphoma with an estimated 3.18 cases per 100,000 people. Despite the prolongation of survival with chemoimmunotherapy, variability in response to initial treatment and outcome still exists. Whereas prolonging overall survival is important, it is generally an unreasonable primary endpoint in the front-line setting. The long follow-up needed and the influence of subsequent therapies creates a potential bias. Thus, clinical trials require approximately 5 to 8 years from activation to completion and analysis of outcomes. This duration results in enormous cost and a delay in developing newer therapies. Thus, there is a need to identify markers or surrogate endpoints that can be used in clinical trials to expedite the development of new treatments. This review will discuss various clinical, radiologic, and laboratory measures used to assess outcomes and overall survival in patients with untreated follicular lymphoma, and gauge their utility in clinical trials as surrogate endpoints.

WIDEN: A tool for medical image management in multicenter clinical trials

Background It has been proposed that in clinical trials in which the therapeutic strategy is driven by functional imaging, central review of the images should be done in real time. Purpose We report our experience with a new tool for image exchange and review, called Web-Based Imaging Diagnosis by Expert Network (WIDEN), which we implemented for the HD0607 prospective multicenter Italian clinical trial in which Hodgkin lymphoma treatment was adapted based on results of an interim positron emission tomography (PET) scan performed after the first two cycles of chemotherapy. Methods We used WIDEN for general management of the clinical trial, site imaging qualification, image exchange, workflow control, blinded independent central review, inter-observer variability assessment, consensus creation, audit, and statistical analysis. Results As of February 2013, the interim PET was available for 512 patients; upon central review, 103 of the scans were judged to be positive and 409 to be negative. The median scan uploading and downloading times were 1 min, 25 s and 1 min, 55 s, respectively; the average and median times for diagnosis exchange were 47 h, 53 min and 37 h, 43 min, respectively. The binary concordance between pairs of reviewers (Cohen's kappa) ranged from 0.72 to 0.85. The 5-point scale concordance among all reviewers (Krippendorf's alpha) was 0.77. Conclusions WIDEN proved to be an effective tool for medical imaging exchange and online review. Data security, simplicity, feasibility, and prompt scan review were demonstrated. Central reviews were completed promptly.

Targeted PET imaging strategy to differentiate malignant from inflamed lymph nodes in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma in adults. DLBCL exhibits highly aggressive and systemic progression into multiple tissues in patients, particularly in lymph nodes. Whole-body ¹⁸F-fluodeoxyglucose positron emission tomography ([¹⁸F]FDG-PET) imaging has an essential role in diagnosing DLBCL in the clinic; however, [¹⁸F]FDG-PET often faces difficulty in differentiating malignant tissues from certain nonmalignant tissues with high glucose uptake. We have developed a PET imaging strategy for DLBCL that targets poly[ADP ribose] polymerase 1 (PARP1), the expression of which has been found to be much higher in DLBCL than in healthy tissues. In a syngeneic DLBCL mouse model, this PARP1-targeted PET imaging approach allowed us to discriminate between malignant and inflamed lymph nodes, whereas [¹⁸F]FDG-PET failed to do so. Our PARP1-targeted PET imaging approach may be an attractive addition to the current PET imaging strategy to differentiate inflammation from malignancy in DLBCL.

Evaluation of decreased uptake of 18F-fluorodeoxyglucose in the cerebral cortex of patients with intracranial non-Hodgkin's lymphoma lesions through PET/CT

BACKGROUND

This study aims to investigate whether basal ganglia can be utilised as reference for measuring ratios between standardised uptake values (SUV), namely, SUV_max and SUV_mean, of 18F-fluoro-deoxyglucose (18F-FDG) uptake, in the ipsilateral cerebral cortex and basal ganglia of patients with non-Hodgkin's lymphoma lesions.

METHODS

Fifty-three patients with pathologically confirmed highly metabolic non-Hodgkin's lymphoma were retrospectively analysed; these patients were subjected to treatment strategy and underwent positron emission tomography/computed tomography (PET/CT). Nineteen of the patients who improved after the treatment were re-examined by PET/CT. PET/CT simultaneity was performed on 12 normal volunteers as the control group. SUV_max and SUV_mean in the cerebral cortex and basal ganglia (head of caudate nucleus and lenticular nucleus) were evaluated by ganglia was also calculated. The ratios were compared between patients and the control group as well as before and after the treatment.

RESULTS

The ratios between the SUV_max of 18F-FDG uptake were 1.03±0.16 (range 0.50-1.51, left) in the ipsilateral cerebral cortex and 1.02±0.16 (range 0.50-1.31, right) in the basal ganglia of 53 patients with non-Hodgkin's lymphoma; the corresponding ratios in the 12 controls were 1.09±0.11 (range 0.99-1.21, left) and 1.09±0.09 (range 1.00-1.24, right), respectively. The ratios between the SUV_mean and 18F-FDG uptake in the ipsolateral cerebral cortex and basal ganglia were 0.76±0.09 (range 0.50-1.07, left) and 0.76±0.09 (range 0.48-0.98, right), respectively, which were lower than those in the control group [0.93±0.06 (range 0.83-0.99, left) and 0.92±0.05 (range 0.84-0.99, right), respectively]. For patients effectively treated, the ratios between the SUV_max in the ipsolateral cerebral cortex and basal ganglia were 1.08±0.13 (range 0.94-1.36, left) and 1.08±0.13 (range 0.88-1.31, right) before the treatment; these values were similar to 1.11±0.13 (range 0.85-1.36, left) and 1.09±0.11 (range 0.90-1.32, right) obtained in the ipsolateral cerebral cortex and basal ganglia of the patients after the treatment, respectively. The ratios between the SUV_mean in the ipsolateral cerebral cortex and basal ganglia were 0.78±0.06 (range 0.68-0.93, left) and 0.78±0.06 (range 0.69-0.95, right) in the patients before the treatment; these ratios were lower than those in post-treatment patients [0.90±0.06 (range 0.74-1.00, left) and 0.90±0.07 (range 0.72-1.00, right), respectively], respectively.

CONCLUSION

High levels of 18F-FDG metabolism in patients with non-Hodgkin's lymphoma may decrease glucose uptake in the cerebral cortex (diversion of 18F-FDG from the cerebral tissue to the lymphoma tissue); this phenomenon may be reversed with effective therapy for lymphoma. The ratio with 18F-FDG metabolism in basal ganglia could be used as reference to quantify and monitor glucose metabolism in cerebral tissues during the course of lymphoma.

Diffuse Large B-Cell Lymphoma: Prospective Multicenter Comparison of Early Interim FLT PET/CT versus FDG PET/CT with IHP, EORTC, Deauville, and PERCIST Criteria for Early Therapeutic Monitoring

Purpose To compare the performance characteristics of interim fluorine 18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) (after two cycles of chemotherapy) by using the most prominent standardized interpretive criteria (including International Harmonization Project [IHP] criteria, European Organization for Research and Treatment of Cancer [EORTC] criteria, and PET Response Criteria in Solid Tumors (PERCIST) versus those of interim (18)F fluorothymidine (FLT) PET/CT and simple visual interpretation. Materials and Methods This HIPAA-compliant prospective study was approved by the institutional review boards, and written informed consent was obtained. Patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) underwent both FLT and FDG PET/CT 18-24 days after two cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone or rituximab, etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin. For FDG PET/CT interpretation, IHP criteria, EORTC criteria, PERCIST, Deauville criteria, standardized uptake value, total lesion glycolysis, and metabolic tumor volume were used. FLT PET/CT images were interpreted with visual assessment by two reviewers in consensus. The interim (after cycle 2) FDG and FLT PET/CT studies were then compared with the end-of-treatment FDG PET/CT studies to determine which interim examination and/or criteria best predicted the result after six cycles of chemotherapy. Results From November 2011 to May 2014, there were 60 potential patients for inclusion, of whom 46 patients (24 men [mean age, 60.9 years ± 13.7; range, 28-78 years] and 22 women [mean age, 57.2 years ± 13.4; range, 25-76 years]) fulfilled the criteria. Thirty-four patients had complete response, and 12 had residual disease at the end of treatment. FLT PET/CT had a significantly higher positive predictive value (PPV) (91%) in predicting residual disease than did any FDG PET/CT interpretation method (42%-46%). No difference in negative predictive value (NPV) was found between FLT PET/CT (94%) and FDG PET/CT (82%-95%), regardless of the interpretive criteria used. FLT PET/CT showed statistically higher (P < .001-.008) or similar NPVs than did FDG PET/CT. Conclusion Early interim FLT PET/CT had a significantly higher PPV than standardized FDG PET/CT-based interpretation for therapeutic response assessment in DLBCL. (©) RSNA, 2016 Online supplemental material is available for this article.

"The Great Mimicker": An Unusual Etiology of Cytopenia, Diffuse Lymphadenopathy, and Massive Splenomegaly

Sarcoidosis is an idiopathic multisystem disease characterized by the formation of noncaseating granulomas. It frequently presents with pulmonary infiltrates and bilateral hilar and mediastinal lymphadenopathy. Splenic involvement is common, but massive splenomegaly is a rare occurrence. Sarcoidosis is known as "the great mimicker" (or "the great imitator") since it exhibits a myriad of symptoms, mimicking other inflammatory, infectious, and neoplastic conditions, including lymphoma. Herein, we report the case of a 44-year-old male patient who was found to have bicytopenia, hypercalcemia, diffuse lymphadenopathy, and massive splenomegaly, a constellation of findings suggestive of underlying lymphoma. Interestingly, lymph node biopsy showed noncaseating granulomas suggestive of sarcoidosis, without evidence of malignancy.

The importance of radiotherapy on diffuse large B cell lymphoma treatment: a current review

Diffuse large B cell lymphoma is recognized as a heterogeneous group of hematological malignancies; two main subtypes germinal center B and activated B cells are well defined although 15% of patients remain with unclassifiable disease. R-CHOP treatment has proven to provide very effective results in limited or advanced stage of the disease. However, treatment solely involving R-CHOP submits the patient to possible chemotherapy-induced toxicities, which may be avoided with the use of radiotherapy. Patients with early stage localized disease or who are particularly unresponsive to chemotherapy may be more suitable for mixed modality treatment with R-CHOP and consolidative radiotherapy. Although radiotherapy is being slowly phased out by other treatment strategies including chemotherapy and therapeutic drugs, it is still a highly important method of treatment. The different forms of radiotherapy can be used alongside these "new-age" treatment strategies to further improve prognostic outcomes and overall survival rates. The establishment of radiotherapy as a treatment strategy provides a highly beneficial prognostic advantage in early stage, localized disease.

Whole-body diffusion-weighted magnetic resonance imaging versus FDG-PET/CT for initial lymphoma staging: systematic review on diagnostic test accuracy studies

CONTEXT AND OBJECTIVE

Positron emission tomography with [18]F-fluoro-2-deoxyglucose (FDG-PET/CT) has been advocated as the method of choice for lymphoma staging, since it enables whole-body analysis with high sensitivity for detection of affected areas and because it combines capacities for anatomical and functional assessment. With technological advances, magnetic resonance imaging (MRI) has emerged as an alternative to FDG-PET/CT. This systematic review with meta-analysis aimed to compare whole-body diffusion-weighted MRI (WB-MRI) with FDG-PET/CT for lymphoma staging.

DESIGN AND SETTING

Systematic review on diagnostic test accuracy studies conducted at a public university.

METHODS

The Medline, Scopus, Embase and Lilacs databases were searched for studies published up to September 2013 that compared WB-MRI and FDG-PET/CT for lymphoma staging. The reference lists of included studies were checked for any relevant additional citations.

RESULTS

Six studies that evaluated the initial lymphoma staging in 116 patients were included. WB-MRI and FDG-PET/CT agreed in 90.5% of the cases (κ = 0.871; P < 0.0001). In most of the studies, when there was disagreement between the methods, WB-MRI overstaged in relation to FDG-PET/CT. The sensitivity of WB-MRI and FDG-PET/CT, in comparison with the clinical-radiological standard, ranged from 59 to 100% and from 63 to 100% respectively.

CONCLUSION

WB-MRI is a highly sensitive method for initial lymphoma staging. It has excellent agreement with FDG-PET/CT and is a great alternative for managing lymphoma patients, without using ionizing radiation or an intravenous contrast agent.

Comparison of (11)C-4'-thiothymidine, (11)C-methionine, and (18)F-FDG PET/CT for the detection of active lesions of multiple myeloma

Purpose

The aims of this study were to evaluate the possibility of using ¹¹C-methionine (¹¹C-MET) and ¹¹C-4′-thiothymidine (¹¹C-4DST) whole-body PET/CT for the imaging of amino acid metabolism and DNA synthesis, respectively, when searching for bone marrow involvement in patients with multiple myeloma (MM) and to compare these findings with those for ¹⁸F-FDG PET/CT and aspiration cytology.

Methods

A total of 64 patients with MM, solitary plasmacytoma, monoclonal gammopathy of undetermined significance, or an unspecified diagnosis were prospectively enrolled. All the patients underwent three whole-body PET/CT examinations within a period of 1 week. First, the tracer accumulation was visually evaluated as positive, equivocal, or negative for 55 focal lytic lesions visualized using CT in 24 patients. Second, the percentages of marrow plasma cells as calculated using a bone marrow aspiration smear and tracer accumulation were evaluated in the posterior iliac crests of 36 patients.

Results

Among the 55 lytic lesions, the ¹¹C-MET and ¹¹C-4DST findings tended to reveal more positive findings than the ¹⁸F-FDG findings. Based on the standard criteria for the diagnosis of active myeloma using the percentage of marrow plasma cells, significant differences were found between the ¹⁸F-FDG and ¹¹C-MET findings and between the ¹⁸F-FDG and ¹¹C-4DST findings, but no significant difference was observed between the ¹¹C-MET and ¹¹C-4DST findings.

Conclusion

The addition of ¹¹C-MET and ¹¹C-4DST to ¹⁸F-FDG when performing PET/CT enabled clearer evaluations of equivocal lesions. Based on cytological diagnostic criteria, ¹¹C-MET and ¹¹C-4DST were more sensitive than ¹⁸F-FDG for the detection of active lesions. ¹¹C-MET and ¹¹C-4DST were more useful than ¹⁸F-FDG for the detection of active lesions, especially during the early stage of disease.

Positron Emission Tomography (PET) in Oncology

Since its introduction in the early nineties as a promising functional imaging technique in the management of neoplastic disorders, FDG-PET, and subsequently FDG-PET/CT, has become a cornerstone in several oncologic procedures such as tumor staging and restaging, treatment efficacy assessment during or after treatment end and radiotherapy planning. Moreover, the continuous technological progress of image generation and the introduction of sophisticated software to use PET scan as a biomarker paved the way to calculate new prognostic markers such as the metabolic tumor volume (MTV) and the total amount of tumor glycolysis (TLG). FDG-PET/CT proved more sensitive than contrast-enhanced CT scan in staging of several type of lymphoma or in detecting widespread tumor dissemination in several solid cancers, such as breast, lung, colon, ovary and head and neck carcinoma. As a consequence the stage of patients was upgraded, with a change of treatment in 10%-15% of them. One of the most evident advantages of FDG-PET was its ability to detect, very early during treatment, significant changes in glucose metabolism or even complete shutoff of the neoplastic cell metabolism as a surrogate of tumor chemosensitivity assessment. This could enable clinicians to detect much earlier the effectiveness of a given antineoplastic treatment, as compared to the traditional radiological detection of tumor shrinkage, which usually takes time and occurs much later.

The role of FDG-PET imaging as a prognostic marker of outcome in primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBL) is a subtype of diffuse large B-cell lymphoma (DLBCL) that arises in the mediastinum from B-cells of thymic origin. Optimal management of patients with PMBL remains controversial. The present study evaluates outcomes of 27 PMBL patients treated with R-CHOP with or without radiation therapy (RT). It investigates the role of both interim and posttreatment fluorodeoxyglucose-positron emission tomography (FDG-PET) as prognostic markers of outcome. Additionally, it assesses postprogression therapies in the six patients who had progressive disease. At a median follow-up of 41.5 months (range: 6.1–147.2 months), OS was 95.5% (95% CI = 71.9–99.4) and progression-free survival (PFS) was 70.4% (95% CI = 49.4–83.9) for the entire cohort. The negative predictive values of interim and posttreatment FDG-PET scans were both 100%. Patients who failed initial therapy and were treated with salvage regimens and autologous stem cell transplantation (ASCT) all achieved and maintained CR. PMBL patients can achieve excellent outcomes with minimal toxicities when treated with R-CHOP with or without RT. Negative interim and negative posttreatment FDG-PET results identified PMBL patients who achieve long-term remission. However, the significance of both positive interim and positive posttreatment FDG-PET results needs to be better defined. Those who failed initial therapy were successfully treated with salvage regimens and ASCT.

Diffusion-weighted MRI for staging and evaluation of response in diffuse large B-cell lymphoma: a pilot study

The aim of this study was to compare diffusion-weighted MRI (DW-MRI) with positron emission tomography/computed tomography (PET/CT) for the staging and evaluation of the treatment response in patients with diffuse large B-cell lymphoma (DLBCL). Institutional review board approval was obtained for this study; all subjects gave informed consent. Twelve patients were imaged before treatment and eight of these were also imaged after two cycles of chemotherapy using both DW-MRI and PET/CT. Up to six target lesions were selected at baseline for response assessment based on International Working Group criteria (nodes > 1.5 cm in diameter; extranodal lesions > 1 cm in diameter). For pretreatment staging, visual analysis of the numbers of nodal and extranodal lesions based on PET/CT was performed. For interim response assessment after cycle 2 of chemotherapy, residual tumor sites were assessed visually and the percentage changes in target lesion size, maximum standardized uptake value (SUVmax ) and apparent diffusion coefficient (ADC) from pretreatment values were calculated. In 12 patients studied pretreatment, there were 46 nodal and 16 extranodal sites of lymphomatous involvement. Agreement between DW-MRI and PET/CT for overall lesion detection was 97% (60/62 tumor sites; 44/46 nodal and 16/16 extranodal lesions) and, for Ann Arbor stage, it was 100%. In the eight patients who had interim assessment, five of their 49 tumor sites remained abnormal on visual analysis of both DW-MRI and PET/CT, and there was one false positive on DW-MRI. Of their 24 target lesions, the mean pretreatment ADC value, tumor size and SUVmax were 772 µm(2) /s, 21.3 cm(2) and 16.9 g/mL, respectively. At interim assessment of the same 24 target lesions, ADC values increased by 85%, tumor size decreased by 74% and SUVmax decreased by 83% (all p < 0.01 versus baseline). DW-MRI provides results comparable with those of PET/CT for staging and early response assessment in patients with DLBCL.

Evaluation of the biodistribution of 11C-methionine in children and young adults

The purpose of this study was to evaluate the biodistribution of (11)C-labeled methionine in non-tumor-involved organs in pediatric patients studied for malignant diseases.

METHODS

Ninety-three children and young adults with known or suspected malignancies underwent (11)C-methionine PET and CT scans. Imaging began 5-15 min after injection of 740 MBq (20 mCi) per 1.7 m(2) of body surface area. Images were acquired from the top of the head through the mid thighs. Standardized uptake values were determined using regions of interest drawn on the CT image and transferred to the corresponding transverse PET slice.

RESULTS

The highest concentrations of (11)C-methionine were found in the pancreas and liver. Less intense uptake was seen in other regions, such as the salivary glands, tonsils, and bone marrow. There was little uptake in the lungs, fat (including brown adipose tissue), and muscle. Uptake in bone marrow, parotid glands, and tonsils was slightly but statistically significantly higher in men than women. Testicular, bone marrow, and left ventricular uptake increased with age. There was little variability statistically between comparisons of uptake change and groupings of age, race, sex, and patients studied at the time of diagnosis versus previously treated patients.

CONCLUSION

High uptake of (11)C-methionine is reliably found in the pancreas and liver, consistent with the anabolic functions of these organs. Low uptake in the brain, neck, chest, pelvis, and extremities will facilitate tumor localization in those areas. However, intense uptake in the upper abdomen may limit the diagnostic utility of (11)C-methionine in that area.

Clinical implications of positron emission tomography-negative residual computed tomography masses after chemotherapy for diffuse large B-cell lymphoma

Response to primary treatment in diffuse large B-cell lymphoma (DLBCL) is highly predictive of long-term outcome. We evaluated the value of computed tomography (CT) findings relative to positron emission tomography (PET) findings, after the completion of chemotherapy. We retrospectively reviewed records from 491 patients with DLBCL at M. D. Anderson in 2001-2007; 22 patients were excluded for uncertain pathology and 169 for having received consolidative radiation, leaving 300 patients for the present analysis (median age, 61 years; 53% men, 47% women; 27% stage I-II, 73% stage III-IV; 73% completed 6-8 cycles of doxorubicin-based therapy). Factors associated with outcome on univariate analysis were response according to PET/CT and CT (p < 0.0001 for overall survival [OS], disease-specific survival [DSS] and progression-free survival [PFS]); number of chemotherapy cycles received (p < 0.0001 OS, p < 0.0001 DSS, p < 0.002 PFS); the combined presence of Ki-67 > 50%, PET SUV ≥ 13 and bulky (> 5 cm) disease (p = 0.005 OS, p = 0.001 DSS, p = 0.001 PFS); and International Prognostic Index (IPI) score (p = 0.004 OS, p = 0.005 DSS, p = 0.004 PFS). On multivariate analysis, PET/CT-negative, CT residual mass (> 2 cm) significantly influenced OS, DSS and PFS (p < 0.0001). The presence of a residual mass >2 cm on CT, coupled with negative findings on PET/CT, has prognostic value in DLBCL.

Predictive value of pretreatment positron emission tomography/computed tomography in patients with newly diagnosed extranodal natural killer/T-cell lymphoma

The role of (18)Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in extranodal natural killer/T-cell lymphoma (ENKL) is not well established. This study aimed to investigate the prognostic role of the pretreatment maximum standardized uptake value (SUV(max)) on PET/CT in patients with newly diagnosed ENKL. Among 364 consecutive patients with newly diagnosed ENKL, 81 patients were included and reviewed. The impact of SUV(max) on survival and the relationship between SUV(max) and other clinicopathological parameters were analyzed. The median SUV(max) was 14.6 (range 2.0-45.4). The optimal cutoff value of SUV(max) to predict overall survival (OS) was 15. Patients with high SUV(max) (SUVmax >15) were associated with bulky disease (P < 0.001), local invasion (P = 0.030), high score of Korean Prognostic Index (KPI, P = 0.046), resistance to primary treatment (P = 0.014), poor OS (P < 0.001), and unfavorable progression-free survival (P < 0.001). With a median follow-up of 25.0 months, the median OS was 63.0 months (range 2.0-99.0 months). Multivariate analyses revealed the following independent prognostic factors for OS: age >60 years (P = 0.001), stage III-IV (P = 0.023), SUV(max) >15 (P = 0.020), and bulky disease (>5 cm) (P = 0.002). By using the SUV(max), patients in most subgroups stratified by the KPI or the International Prognostic Index (IPI) were further discriminated in OS with significant statistical difference. Our results suggest the pretreatment SUV(max) is predictive of prognosis in patients with newly diagnosed ENKL. The SUV(max) may provide additional prognostic information for IPI and KPI.

Staging and monitoring in the treatment of lymphomas

Lymphoma staging systematically includes a CT scan of the cervical, thoracic and abdominopelvic regions. PET is indicated in diffuse large B cell lymphomas (DLBCL) and Hodgkin's disease. Evaluation of the response to treatment is based on Cheson's 1999 morphological criteria, which have been replaced by the 2007 IWC criteria, which combine morphological and metabolic responses. CT and FDG-PET are complementary in characterizing residual masses: if negative, a PET scan indicates the absence of residual disease, if positive; it directs a CT-guided biopsy to obtain the histological evidence. Monitoring clinical features and laboratory values is primordial following treatment. Imaging is performed as a second intention for investigating a relapse, if necessary associated with a PET scan. Multimodal imaging implies multidisciplinary consultation between haematologists, imaging specialists and histopathologists.

Prognostic significance of rituximab and radiotherapy for patients with primary mediastinal large B-cell lymphoma receiving doxorubicin-containing chemotherapy

Abstract The aim of this study was to evaluate the prognostic importance of rituximab and radiotherapy in patients with primary mediastinal large B-cell lymphoma (PMBCL) receiving doxorubicin-containing chemotherapy. Seventy-nine patients with PMBCL received CHOP chemotherapy with (n = 39) or without rituximab (n = 40), and 60 patients received additional radiotherapy. Patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) had significantly superior survival rates. The 5-year overall survival (OS) and progression-free survival (PFS) rates were 83.7% and 76.7% for R-CHOP, compared with 48.3% (p = 0.011) and 44.2% (p = 0.012) for CHOP, respectively. Similarly, the 5-year OS and PFS rates for early stage patients were 93.8% and 84.6% with R-CHOP, and 52.0% (p = 0.002) and 46.6% (p = 0.003) with CHOP, respectively. Patients treated with chemotherapy and radiotherapy had better survival and local control (LC) rates compared with chemotherapy alone. The 5-year OS, PFS and LC rates for early stage patients were 73.6%, 69.9% and 92.6% for chemotherapy and radiotherapy, and 50.8% (p = 0.076), 36.9% (p = 0.008) and 56.4% (p < 0.001) for chemotherapy alone, respectively. Early stage patients treated with R-CHOP and radiotherapy had 5-year OS, PFS and LC rates of 96.4%, 85.9% and 93.1%. R-CHOP plus consolidation radiotherapy was associated with excellent survival and LC rates.

[Quantitative and qualitative evaluation of the interim PET/CT in lymphoma treatment in the prediction of complete metabolic response]

OBJECTIVE

To compare two different methods for the interpretation of interim PET/CT (PET/CT-i) in lymphomas, and to establish which one best predicts a complete metabolic response (CMR) in the PET/CT study at the end of treatment (PET/CT-et).

MATERIAL AND METHODS

Retrospective longitudinal analysis of the PET/CT studies for staging (PET/CT-s), PET/CT-i and PET/CT-et of 65 patients, 35 Hodgkin's lymphoma (HL) and 30 Non-HL. The PET/CT-i was performed between the second and fourth chemotherapy cycle. It was interpreted using two different criteria: qualitative criteria (5 point visual scale), semiquantitative criteria (percentage difference between the lesion with more SUVmax in the PET/CT-s and PET/CT-i). We analyzed the likelihood of obtaining a CMR in the PET/CT-et according to the results obtained on the PET/CT-i with these two criteria.

RESULTS

We obtained sensitivity (S), specificity (Sp), positive predictive values (PPV), negative predictive values (NPV) and likelihood ratio (LR) for the qualitative/semiquantitative method of 91%/80%, 76.2%/67%, 88.9%/83.3%, 80%/60.9% and 32%/7.8%, respectively, to predict a CMR in the PET/CT-et. There were no statistically significant differences between the LR of both methods (p=0.1942).

CONCLUSION

We found clear differences in S, Sp, PPV and NPV between both interpretation criteria for the PET/CT-i to predict a CMR in the PET/CT-et. Nevertheless, we cannot confirm the superiority of the qualitative method over the semiqualitative method for this purpose as no statistically significance differences were found in their LR in our study.

Investigation of dose minimisation protocol for 18F-FDG PET-CT in the management of lymphoma postchemotherapy followup

INTRODUCTION

(18)F-FDG-PET-CT plays an important role in the management of lymphoma postchemotherapy followup. Some centres perform prechemotherapy baseline CT and postchemotherapy PETCT. With a concern of radiation burden, especially in young patients, this study aimed to assess if PETCT radiation dose could be reduced.

METHODS

Retrospective analysis of 100 lymphoma patients was performed to record sites of disease on prechemotherapy CT and postchemotherapy PETCT. The potential reduction in radiation and time achieved with PETCT limited to sites of known disease identified on prechemotherapy CT was calculated.

RESULTS

No FDG-uptake was seen in 72 cases. FDG uptake at known disease sites was seen in 24. Of the remaining 4, one had clinically significant pathology, a rectal adenocarcinoma. PETCT did not reveal any unexpected sites of lymphoma. Limiting PETCT to sites of known disease would have saved a mean radiation dose of 4 mSv (27.3%), with a mean time of 16 minutes.

CONCLUSION

Our study suggests that young patients may benefit from reduced radiation by limiting PETCT to sites of known disease with low risk of missing significant pathology. However, in older patients, with increased incidence of asymptomatic synchronous malignancies, whole-body PETCT is advisable unless prechemotherapy PETCT has been performed.

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.

The sarcoid-lymphoma syndrome

Whether a relationship exists between sarcoidosis and lymphoma is controversial. We present 4 patients diagnosed with sarcoidosis either during or after the treatment of lymphoma, review the data surrounding the entity known as "sarcoid-lymphoma syndrome" and discuss the diagnostic pitfalls it can present. As both entities are fluorine-18 fluorodeoxyglucose avid, histologic verification and clinical acumen are needed to avoid misdiagnosis before initiating therapy.

FDG-PET/CT in lymphoma

Molecular Imaging has played a prominent role in the assessment of lymphoma for now almost three decades since the introduction of (67)Ga-citrate imaging for staging and restaging of both Hodgkin's and non-Hodgkin's lymphoma (HL and NHL). Since then other molecular probes have been investigated for more accurate pre- and posttreatment assessment of lymphomas but none of these probes was widely accepted and utilized until the emergence of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). FDG-PET or FDG-PET/CT, which combines FDG-PET with CT scanning, is now widely utilized for response assessment of lymphoma after completion of therapy, for pretreatment staging, and, increasingly, also for assessment of response during therapy (therapy monitoring). Particularly for response assessment at therapy conclusion, FDG-PET has been shown to be considerably more accurate than CT or conventional MRI because of its ability to distinguish between viable tumor and necrosis or fibrosis in posttherapy residual mass (es) that are frequently present in patients with lymphoma without any other clinical or biochemical evidence of disease. FDG-PET/CT is therefore the noninvasive modality of choice for response classifications of HL and aggressive NHLs consistent with the recently revised, primarily FDG-PET/CT-based, response criteria for lymphoma. This review will highlight the most important applications of FDG-PET (FDG-PET/CT) in lymphoma emphasizing the strengths and pitfalls of this imaging approach, past and ongoing efforts to standardize the use of FDG-PET, particularly in response assessment and therapy monitoring. Other promising molecular probes for lymphoma imaging will also be briefly discussed.

Quantitative assessment of diffusion-weighted MR imaging in patients with primary rectal cancer: correlation with FDG-PET/CT

PURPOSE

The aim of the study was to assess correlations between parameters on diffusion-weighted imaging and 2-deoxy-2-[(18)F]fluoro-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in rectal cancer.

PROCEDURES

Thirty-three consecutive patients with pathologically confirmed rectal adenocarcinoma were included in this study. Apparent diffusion coefficient (ADC) maps were generated to calculate ADC(mean) (average ADC), ADC(min) (lowest ADC), tumor volume, and total diffusivity index (TDI). PET/CT exams were performed within 1 week of magnetic resonance imaging. Standardized uptake values (SUVs) were normalized to the injected FDG dose and body weight. SUV(max) (maximum SUV), SUV(mean) (average SUV), tumor volume, and total lesion glycolysis (TLG) were calculated using a 50% threshold.

RESULTS

Significant negative correlations were found between ADC(min) and SUV(max) (r = -0.450, p = 0.009), and between ADC(mean) and SUV(mean) (r = -0.402, p = 0.020). A significant positive correlation was found between TDI and TLG (r = 0.634, p < 0.001).

CONCLUSION

The significant negative correlations between ADC and SUV suggest an association between tumor cellularity and metabolic activity in primary rectal adenocarcinoma.

Positron emission tomography scanning in the setting of post-transplant lymphoproliferative disorders

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a serious complication of transplantation. We examined the role of positron emission tomography (PET) scanning in PTLD.

METHODS

All patients treated for PTLD from 2001-2006 who also underwent PET scans were reviewed.

RESULTS

Nineteen PTLD patients were included. Seventeen patients had PET scans for staging at diagnosis. Of these, two patients with primary central nervous system lymphoma and one patient with only bone marrow involvement after complete surgical resection of a bowel lesion had no abnormalities on CT or PET scan. The remaining patients had measurable, extracranial disease by CT scan and PET scan. The median maximum standard uptake value was 8.2 (range 3-30). Thirteen patients had a PET scan following treatment. Eleven of 13 patients had a complete response (CR). Two of 13 patients had persistent disease following therapy; in one of these patients, relapsed disease was documented by PET scan alone. Of the 11 patients with CR, three patients relapsed shortly thereafter. In each case, at the time of relapse, the PET scan confirmed recurrent disease regardless of histopathologic subtype.

CONCLUSIONS

PET scans may have a role in the staging and follow-up of patients with PTLD. Additional prospective studies are warranted.

Decreased brain FDG uptake in patients with extensive non-Hodgkin's lymphoma lesions

OBJECTIVE

Faint brain [(18)F]fluoro-2-deoxyglucose (FDG) uptake has sporadically been reported in patients with FDG-avid large or diffusely extended tumors. The purpose of this study was to investigate whether there is a correlation between massive tumor uptake and decreased brain uptake on FDG positron emission tomography/computed tomography (PET/CT).

METHODS

Sixty-five patients with histologically confirmed non-Hodgkin's lymphoma who underwent FDG-PET/CT were enrolled. Thirty control subjects were also included to evaluate normal brain FDG uptake. PET/CT examinations were retrospectively reviewed. The volumetric regions of interest were placed over lesions by referring to CT and PET/CT fusion images to measure mean standardized uptake value (SUVavg). The products of SUVavg and tumor volume were calculated as total glycolytic volume (TGV). The maximum SUV (SUVmax) and SUVavg were measured in the cerebrum and cerebellum. The values of TGV and brain FDG uptake were plotted and analyzed with a linear regression method.

RESULTS

In the lymphoma patients, there were statistically significant negative correlations between TGV and brain SUVs.

CONCLUSION

Demonstrating a significant negative correlation between TGV and brain uptake validated the phenomenon of decreased brain FDG uptake. Diversion of FDG from the brain to the lymphoma tissue may occur during the FDG accumulation process. Recognition of this phenomenon prevents unnecessary further neurological examinations in such cases.