The usefulness of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) and a comparison of (18)F-FDG-pet with (67)gallium scintigraphy in the evaluation of lymphoma: relation to histologic subtypes based on the World Health Organization classification

Role of Novel Quantitative Imaging Techniques in Hematological Malignancies

Hematological malignancies exhibit a widespread distribution, necessitating evaluation of disease activity over the entire body. In clinical practice, visual analysis and semiquantitative parameters are used to assess 18F-FDGPET/CT imaging, which solely represents measurements of disease activity from limited area and may not adequately reflect global disease assessment. An efficient method for assessing the global disease burden of hematological malignancies is to employ PET/computed tomography based novel quantitative parameters. In this article, we explored novel quantitative parameters on PET/CT imaging for assessing global disease burden and the potential role of artificial intelligence (AI) to determine these parameters in evaluation of hematological malignancies.

Evaluating 64Cu-DOTA-rituximab as a PET agent in patients with B-cell lymphoma: a head-to-head comparison with 18F-fluorodeoxyglucose PET/computed tomography

BACKGROUND

This study aimed to evaluate the biodistribution of 64Cu-DOTA-rituximab and its diagnostic feasibility for lymphoma using CD20-targeted 64Cu-DOTA-rituximab PET/computed tomography (PET/CT).

METHODS

A prospective study involving six patients diagnosed with lymphoma was conducted between January 2022 and January 2023. These patients underwent 18F-fluorodeoxyglucose (18F-FDG) and 64Cu-DOTA-rituximab PET/CT scans. 64Cu-DOTA-rituximab PET/CT images were acquired at 1, 24, and 48 h after administering 64Cu-DOTA-rituximab to assess the biodistribution and dosimetry over time. The observed lymph nodes were categorized into specific regions, including cervical and supraclavicular, axillary and infraclavicular, mediastinal, hilar, abdominal paraaortic and retroperitoneal, iliac, mesenteric, and inguinal regions, to compare the diagnostic ability of 18F-FDG and 64Cu-DOTA-rituximab PET/CT in detecting lymphoma lesions. Furthermore, the tumor-to-background ratio was calculated and compared with the maximum standardized uptake (SUVmax) of the tumors and the mean standardized uptake (SUVmean) of normal organs. Internal radiation dosimetry was determined using the OLINDA/EXM software.

RESULTS

64Cu-DOTA-rituximab uptake in lymph nodes associated with lymphoma progressively increased from 1 to 48 h after injection. In contrast, 64Cu-DOTA-rituximab uptake in normal organs, such as blood, lung, kidney, bladder, muscle, bone, and brain, decreased over time, whereas it increased in the liver and spleen. When it comes to the comparison between 64Cu-DOTA-rituximab and 18F-FDG, the SUVmax of tumors was higher on 64Cu-DOTA-rituximab PET/CT (18.1 ± 8.3) than on 18F-FDG PET/CT (5.2 ± 1.5). Additionally, the tumor-to-background ratio, measured using the SUVmean of normal muscles, was higher on 64Cu-DOTA-rituximab PET/CT (55.7 ± 31.0) than on 18F-FDG PET/CT (8.6 ± 2.8). No adverse events related to 64Cu-DOTA-rituximab injection were reported.

CONCLUSION

The results of this study demonstrate the feasibility of using 64Cu-DOTA-rituximab PET/CT to evaluate the CD20 expression. The increased 64Cu-DOTA-rituximab uptake in lymph nodes associated with tumors, higher SUVmax, and tumor-to-muscle ratios observed with 64Cu-DOTA-rituximab PET/CT compared with 18F-FDG PET/CT, highlight the diagnostic potential of this imaging modality.

18 F-FDG-PET/CT imaging in diagnostic workup of pediatric precursor B-cell lymphoblastic lymphoma

18 F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) imaging is currently not used in standard diagnostics for B-cell precursor lymphoblastic lymphoma (BCP-LBL), and it is unknown whether PET/CT imaging would lead to agreement between detection of lesions with the gold standard imaging methods. Therefore, we performed a retrospective cohort study in which we included 32 pediatric BCP-LBL patients and determined localizations by reviewing local imaging reports. There was a disagreement between protocol-based imaging and PET/CT in 59% of the patients, and the discrepancies mostly comprise of additional lesions detected with PET/CT, typically in lymph node and bone or the absence of bone marrow involvement with PET/CT. If PET/CT was leading in determining definite stage of disease, this would lead to a different stage and therapy branch in 31% and 28% of the patients, respectively.

64 Cu-DOTA-Rituximab PET/CT of B-Cell Non-Hodgkin Lymphoma for Imaging the CD20 Expression

ABSTRACT

64 Cu-DOTA-rituximab PET/CT was performed on a 62-year-old and a 71-year-old men diagnosed with B-cell non-Hodgkin lymphoma. Compared with 18 F-FDG PET/CT, lesions could be detected more sensitively, and it was confirmed that there was no discernible 64 Cu-DOTA-rituximab uptake in the tumor other than lymphoma. 64 Cu-DOTA-rituximab PET/CT could be a powerful tool for the diagnosis and monitoring treatment response of lymphoma because of imaging the CD20 expression.

The diagnosis and management of suspected lymphoma in general practice

With rapid advancements in diagnosis and treatment of malignancies, the gap between generalists and subspecialists continues to widen, particularly in cancers like lymphoma where the spectrum of disease varies from indolent to rapidly progressive. Prior to establishing with a hematologist/oncologist, patients must be accurately and comprehensively diagnosed and managed for lymphoma in the generalist setting. In the following manuscript, we review the common clinical presentations in which should raise concern for lymphoma. We summarize the literature regarding the role of laboratory studies including complete blood count and peripheral blood flow cytometry, the recommendations for lymph node sampling, the role and selection of imaging modalities, and ideal patient monitoring for high-risk clinical syndromes that may be encountered in lymphoma.

PET-CT in Clinical Adult Oncology: I. Hematologic Malignancies

PET-CT is an advanced imaging modality with many oncologic applications, including staging, assessment of response to therapy, restaging and evaluation of suspected recurrence. The goal of this 6-part series of review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for the more common adult malignancies. In the first article of this series, hematologic malignancies are addressed. The classification of these malignancies will be outlined, with the disclaimer that the classification of lymphomas is constantly evolving. Critical applications, potential pitfalls, and nuances of PET-CT imaging in hematologic malignancies and imaging features of the major categories of these tumors are addressed. Issues of clinical importance that must be reported by the imaging professionals are outlined. The focus of this article is on [¹⁸F] fluorodeoxyglucose (FDG), rather that research tracers or those requiring a local cyclotron. This information will serve as a resource for the appropriate role and limitations of PET-CT in the clinical management of patients with hematological malignancy for health care professionals caring for adult patients with hematologic malignancies. It also serves as a practical guide for imaging providers, including radiologists, nuclear medicine physicians and their trainees.

Positron-emission tomography-based staging is cost-effective in early-stage follicular lymphoma

The objective was to assess the cost-effectiveness of staging PET/CT in early-stage follicular lymphoma (FL) from the Canadian health-care system perspective. Methods: The study population was FL patients staged as early-stage using conventional CT imaging and planned for curative-intent radiation therapy (RT). A decision analytic model simulated the management after adding staging PET/CT versus using staging CT alone. In the no-PET/CT strategy, all patients proceeded to curative-intent RT as planned. In the PET/CT strategy, PET/CT information could result in an increased RT volume, switching to a noncurative approach, or no change in RT treatment as planned. The subsequent disease course was described using a state-transition cohort model over a 30-y time horizon. Diagnostic characteristics, probabilities, utilities, and costs were derived from the literature. Baseline analysis was performed using quality-adjusted life years (QALYs), costs (2019 Canadian dollars), and the incremental cost-effectiveness ratio. Deterministic sensitivity analyses were conducted, evaluating net monetary benefit at a willingness-to-pay threshold of $100,000/QALY. Probabilistic sensitivity analysis using 10,000 simulations was performed. Costs and QALYs were discounted at a rate of 1.5%. Results: In the reference case scenario, staging PET/CT was the dominant strategy, resulting in an average lifetime cost saving of $3,165 and a gain of 0.32 QALYs. In deterministic sensitivity analyses, the PET/CT strategy remained the preferred strategy for all scenarios supported by available data. In probabilistic sensitivity analysis, the PET/CT strategy was strongly dominant in 77% of simulations (i.e., reduced cost and increased QALYs) and was cost-effective in 89% of simulations (i.e., either saved costs or had an incremental cost-effectiveness ratio below $100,000/QALY). Conclusion: Our analysis showed that the use of PET/CT to stage early-stage FL patients reduces cost and improves QALYs. Patients with early-stage FL should undergo PET/CT before curative-intent RT.

Relative clinical utility of simultaneous 18F-fluorodeoxyglucose PET/MRI and PET/CT for preoperative cervical cancer diagnosis

Objective

To investigate the utility of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) for the preoperative diagnosis of cervical cancer.

Methods

We retrospectively analyzed 114 patients who were diagnosed with cervical cancer and underwent PET/MRI (n = 59) or PET/computed tomography (PET/CT) (n = 65) before surgery. The maximal standardized uptake value (SUV_max) and mean SUV (SUV_mean) were determined for regions of interest in the resultant radiographic images.

Results

Relative to PET/CT, ¹⁸F-FDG PET/MRI exhibited higher specificity and sensitivity in defining the primary tumor bounds and higher sensitivity for detection of bladder involvement. The SUV_max and SUV_mean of PET/MRI were remarkably higher than those of PET/CT as a means of detecting primary tumors, bladder involvement, and the lymph node status. However, no significant differences in these values were detected when comparing the two imaging approaches as a means of detecting vaginal involvement or para-aortic lymph node metastasis.

Conclusions

These outcomes may demonstrate the capability of ¹⁸F-FDG PET/MRI to clarify preoperative cervical cancer diagnoses in the context of unclear PET/CT findings. However, studies directly comparing SUVs in different lesion types from patients who have undergone both PET/MRI and PET/CT scans are essential to validate and expand upon these findings.

Assessment of naive indolent lymphoma using whole-body diffusion-weighted imaging and T2-weighted MRI: results of a prospective study in 30 patients

Background

We prospectively evaluated the diagnostic utility of whole-body diffusion-weighted imaging with background body signal suppression and T2-weighted short-tau inversion recovery MRI (WB-DWIBS/STIR) for the pretherapeutic staging of indolent lymphoma in 30 patients.

Methods

This prospective study included 30 treatment-naive patients with indolent lymphomas who underwent WB-DWIBS/STIR and conventional imaging workup plus biopsy. The pretherapeutic staging agreement, sensitivity, and specificity of WB-DWIBS/STIR were investigated with reference to the multimodality and multidisciplinary consensus review for nodal and extranodal lesions excluding bone marrow.

Results

In the pretherapeutic staging, WB-DWIBS/STIR showed very good agreement (κ = 0.96; confidence interval [CI], 0.88–1.00), high sensitivity (93.4–95.1%), and high specificity (99.0–99.4%) for the whole-body regions. These results were similar to those of ¹⁸F-FDG-PET/CT, except for the sensitivity for extranodal lesions. For extranodal lesions, WB-DWIBS/STIR showed higher sensitivity compared to ¹⁸F-FDG-PET/CT for the whole-body regions (94.9–96.8% vs. 79.6–86.3%, P = 0.058).

Conclusion

WB-DWIBS/STIR is an effective modality for the pretherapeutic staging of indolent lymphoma, and it has benefits when evaluating extranodal lesions, compared with ¹⁸F-FDG-PET/CT.

Is Limited-Stage Mantle Cell Lymphoma Curable and How Is It Best Managed?

Limited-stage (stage I-II) mantle cell lymphoma (MCL) is rarely encountered. There is no standard approach to treatment and available data to guide management decisions mainly are retrospective studies. A thorough staging evaluation, including positron emission tomography/computed tomography, bone marrow biopsy, and gastrointestinal evaluation, should be completed because disseminated disease is common. Radiation therapy is effective for local control, and, although prolonged remission can be achieved, distant relapses are common and there are insufficient data to say that patients can be cured using this treatment. This article reviews literature pertaining to management of patients with limited-stage MCL and discusses approach to treatment.

Oncological outcome and recurrence pattern analysis after involved-field irradiation in combination with rituximab for early-stage nodal and extranodal follicular lymphoma

Purpose

Combined radioimmunotherapy (RIT) in follicular lymphomas (FL) has shown promising treatment efficacy in the Mabthera® and Involved field Radiation (MIR) study. Aim of this study was to analyze treatment efficacy and recurrence patterns after RIT in early-stage nodal and extranodal FL.

Methods

We reviewed 107 patients who were treated with combined RIT in two centers. Treatment consisted of 4 × rituximab followed by RIT with 4 × rituximab and involved field (IF) radiotherapy with 30/40 Gy. Median follow-up period was 71 months. In contrast to the MIR study, extranodal involvement and grade 3A histology were included in the analysis.

Results

Extranodal involvement and grade 3A histology were present in 21.8% and 13.1%, respectively. Overall response rate (ORR) after 4 × rituximab, after completion of RIT, and after 6 months was 78.1%, 98.8%, and 98.8%, respectively, with increasing rates of complete remissions (CR). Predictive factors associated with superior PFS were tumor size, completely excised lymphomas, and response to first 4 × rituximab. 5‑year PFS rate was 87.3%, with mostly outfield recurrences (94.1%). Second-line treatment was effective, with 53.3% CR and 46.7% partial remissions (PR). 5‑year OS was 98.1%. RIT was tolerated well, with mainly grade 1–2 acute side effects.

Conclusion

The real-world efficacy of RIT is comparable with the results of the MIR study. Additionally, this analysis shows that extranodal involvement and grade 3A histology are not associated with inferior PFS.

Clinical analysis of adrenal lesions larger than 5 cm in diameter (an analysis of 251 cases)

Background

To describe the pathological distribution, imaging manifestations, and surgical managements and prognosis of large adrenal tumors (LATs) ≥ 5 cm

Methods

A total of 251 patients with LATs were analyzed on the basis of pathological or clinical diagnosis. Regarding surgery, open adrenalectomy was performed on 89 patients, and laparoscopic adrenalectomy was performed on 89 patients. Thirty-two patients with bilateral tumors were analyzed in terms of clinical characteristics. The survival rate was determined for 43 patients with adrenal metastases and 29 patients with primary adrenal malignancies. The CT characteristics including tumor diameter, shape, edge, heterogeneity, necrosis, calcification, pre-contrast attenuation, and contrast attenuation were analyzed for 117 patients.

Results

The majority of LATs were still benign, but they had a higher probability to be malignant. Benign LATs made up 68.13% of all cases, mainly adrenal cysts (19.52%), pheochromocytoma (18.73%), benign adenoma (16.73%), and myelolipoma (7.17%). Malignant LATs accounted for 28.69% of cases, mainly including adrenocortical carcinoma (8.76%) and metastases (17.13%). Laparoscopic surgery was found to involve less trauma than open surgery. It was also safer and postoperative recovery was faster, but it had drawbacks and could not completely replace open surgery. CT features had obvious specificity for the diagnosis of benign and malignant tumors. For example, benign adenomas had a smaller pre-contrast (< 10 Hu) whereas malignant adrenal tumors had, on the contrary, higher attenuation. Regarding adrenal malignant carcinoma, adrenal primary malignant tumors showed a better prognosis than adrenal metastases (mean survival of 19.17 months vs 9.49 months). Primary adrenal cortical carcinoma without metastasis had a better prognosis than primary adrenal cortical carcinoma metastasis (mean survival of 23.71 months vs 12.75 months), and adrenal solitary metastasis had a better prognosis than general multiple metastatic carcinoma (mean survival of 14.95 months vs 5.17 months).

Conclusion

LATs were more likely to be benign; however, they still had a high probability of being a malignant tumor. Understanding the clinicopathological characteristics of LATs can facilitate selection of more effective clinical treatment options.

18F-FDG PET/CT or PET Role in MALT Lymphoma: An Open Issue not Yet Solved-A Critical Review

Mucosa-associated lymphoid tissue (MALT) lymphoma involves the mucosa-associated lymphoid tissue potentially arising from any mucosal site, with the stomach as the most common site of involvement. MALT lymphoma is not usually an aggressive disease with a good prognosis except for selected cases. Fluorine-18 (¹⁸F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is a noninvasive imaging tool used for staging, restaging, and evaluation of the treatment response in non-Hodgkin and Hodgkin lymphoma. However, its effective role in MALT lymphoma is not yet clear. The open question is whether these lymphomas are ¹⁸F-FDG avid or not, with conflicting results reported in the literature. Consequently, the possible clinical role of ¹⁸F-FDG PET/CT for staging and restaging purposes is under debate. The aim of the present review was to analyze the reported data about the role of ¹⁸F-FDG PET or PET/CT in patients with MALT lymphoma. We performed a comprehensive computer literature search of the Scopus, Cochrane, PubMed/MEDLINE, and Embase databases, including articles reported up to August 2019. We included 32 studies that had analyzed ¹⁸F-FDG PET or PET/CT for patients with MALT lymphoma. We analyzed the metabolic behavior of MALT lymphoma using ¹⁸F-FDG PET and the effect of the PET findings in the staging, treatment response evaluation, and prognosis.

Therapy of nodal Follicular Lymphoma (WHO grade 1/2) in clinical stage I/II using response adapted Involved Site Radiotherapy in combination with Obinutuzumab (Gazyvaro) - GAZAI Trial (GAZyvaro and response adapted Involved-site Radiotherapy): a study protocol for a single-arm, non-randomized, open, national, multi-center phase II trial

BACKGROUND

Large field irradiation had been standard for early-stage follicular lymphoma (FL) for a long time. Although involved field radiotherapy (IF-RT) was recently favored because of the toxicity of large field irradiation, smaller irradiation fields have been accompanied with an increased risk of out-of-field recurrence. The MIR (MabThera® and Involved field Radiation) trial has shown that the combination of IF-RT at a dose of 30-40 Gy with the anti-CD20 antibody rituximab has led to similar efficacy compared with large field irradiation but with markedly reduced side effects. Immune modulating radiation therapy alone using low-dose radiotherapy (LDRT) of 2 × 2 Gy has been shown to be effective in FL. The GAZAI (GAZyvaro and response Adapted Involved-site Radiotherapy) trial aims to prove the efficacy of LDRT in combination with a novel anti-CD20 therapy.

METHODS/DESIGN

The GAZAI trial is a non-randomized, open, non-controlled, German, multi-center phase II trial that includes patients with early-stage (I and II) nodular FL (grades 1 and 2) confirmed by central histological review. A maximum of 93 patients will be included in the trial. Patients will receive a combined approach of immunotherapy with the fully humanized anti-CD20 antibody obinutuzumab (Gazyvaro®) and involved site radiotherapy (IS-RT) with 2 × 2 Gy. The primary endpoint of the trial is the rate of metabolic complete response (CR), based on fludeoxyglucose positron emission tomography/computed tomography, after obinutuzumab and 2 × 2 Gy IS-RT in week 18. Secondary endpoints are morphologic CR rate in weeks 7 and 18 and month 6, progression-free survival, toxicity, recurrence patterns, overall survival, and quality of life. Additionally, minimal residual disease response is assessed. The risk for a potentially higher recurrence rate after LDRT will be minimized by additional salvage radiation up to the "full dose" of 40 Gy for patients who have less than a metabolic CR and morphologic partial response/CR, which will be evaluated in week 18, offering a response-adapted approach.

DISCUSSION

The goal of this trial is a further reduction of the radiation dose in patients with nodal early-stage FL showing a good response to a combination of LDRT and anti-CD20 immunotherapy and a comparison with the currently published MIR trial.

TRIAL REGISTRATION

EudraCT number: 2016-002059-89. ClinicalTrials.gov identifier: NCT03341520 .

[Follicular lymphoma: first - line selection criteria of treatment]

Follicular lymphoma (FL) is a tumor that develops from the B cells of the germinal center; characterized by recurrent and remitting course of the disease, the transformation of a tumor into diffuse large B-cell lymphoma (DLBCL) is possible. In generalized lesions and progression of FL, the most commonly used courses are R-CHOP and R-B. The choice of therapy for different cytological types, clinical and laboratory parameters remains disputable.

AIM

To analyze the clinical, laboratory, morphological parameters of patients with FL, who got R-B and R-CHOP therapy; determine the criteria for selecting induction therapy.

MATERIALS AND METHODS

The study included 203 patients with FL from 2000 to 2018. R-CHOP treatment was initiated in 126 patients, 14 of whom later received high - dose therapy (HDT) (R-DHAP: rituximab, dexamethasone, cisplatin, cytarabine) without autologous stem cell transplantation (autoSCT), 21 - HDT with autoSCT; treatment of 89 patients was limited to courses of R-CHOP and maintenance therapy with rituximab, two patients (in whom the disease progressed, despite R-CHOP therapy) were assigned the mNHL-BFM-90 program. The efficacy of treatment on various treatment regimens was evaluated primarily by overall survival.

RESULTS AND DISCUSSION

R-B. 77 patients received R-B therapy. Complete remission of the disease was achieved in 47/77 (61%) patients (3 of them later developed a relapse of the disease), partial remission was achieved in 15/77 (19%) patients, in 13/77 (17%) cases progression was recorded tumors. 70 patients had 1-2 cytological type of tumor, 6 patients - 3A cytological type. In cases of progression, 3 of 13 patients (46%) were diagnosed with 3A cytological type FL. Median observation (at the time of analysis) - 34 months. R-CHOP. 89 patients with FL received high - dose therapy with R-CHOP (6-8 courses) and maintenance therapy with rituximab. In 39 (44%) patients, the disease remained in remission, and in 50 (56%), a relapse of the disease developed. 50 patients had 1-2 cytological types, 39 - 3 cytological types. In cases of recurrence of FL, a 3A cytologic type (36%) was diagnosed in 18/50 patients. Median observation - 93 months. R-CHOP + HDT and autoSCT. 21 patients after the R-CHOP courses continued (due to insufficient antitumor response) high - dose chemotherapy (HDT) and auto-SCT were performed. In 18/21 (86%) cases, complete remission of the disease was achieved and maintained, in 3 (14%) cases relapse developed. 16 patients had 1-2 cytological types, 5 - 3 cytological types. Median observation - 81 months. R-CHOP + HDT without autoSCT. 14 patients started therapy under the R-CHOP program as induction therapy, but then (due to insufficient antitumor response), the treatment was continued according to the HDT without autoSCT. 11 (79%) patients are currently in remission of the disease, in 3 (21%) - there was a relapse. 10 patients had 2 cytological types of PL, 4 - 3 cytological types. 11 (79%) patients are currently in remission of the disease, in 3 (21%) - there was a relapse. Median observation - 80 months. 7-year OS of patients with FL on RB therapy was 89% (95% CI 75-99), on R-CHOP therapy - 85% (95% CI 73-90), on R-CHOP + HDT and autoSCT - 87% (95% CI 57-100), on R-CHOP + HDT without autoSCT - 82%. 7-year PFS of FL patients on RB therapy was 70% (95% CI 75-99), on R-CHOP therapy - 44% (95% CI 73-90), on R-CHOP + HDT and autoSCT - 74% (95% CI 57-100), on R-CHOP + HDT without autoSCT - 80%.

CONCLUSION

The R-B is most effective in FL 1 and 2 cytological types. The cytological type does not correspond to the type of tumor growth: at 3A and 3A + 3B cytological types, nodular / nodular - diffuse and diffuse types of growth are found. When choosing an induction course, one should look at the cytological type of FL. A high proliferative activity index (according to Ki67) is a predictor of resistance to R-B therapy. The absence of an interfollicular T-cell reaction in tumor tissue FL is associated with tumor chemoresistance. The presence of the bulky factor is associated (in most patients) with the FLIPI index with values from 3 to 5, and is a predictor of a poor response to therapy. Patients with bulky, high (more than 35%) Ki67 index and FLIPI from 3 to 5 in the debut of the disease as the first line therapy, it is preferable to choose the R-CHOP mode, and in the absence of (after 4-6 courses) to complete or partial remission to continue conducting the HDT.

Tumour necrosis as assessed with 18F-FDG PET is a potential prognostic marker in diffuse large B cell lymphoma independent of MYC rearrangements

Objectives

MYC gene rearrangements in diffuse large B cell lymphomas (DLBCLs) result in high proliferation rates and are associated with a poor prognosis. Strong proliferation is associated with high metabolic demand and tumour necrosis. The aim of this study was to investigate differences in the presence of necrosis and semiquantitative ¹⁸F-FDG PET metrics between DLBCL cases with or without a MYC rearrangement. The prognostic impact of necrosis and semiquantitative ¹⁸F-FDG PET parameters was investigated in an explorative survival analysis.

Methods

Fluorescence in situ hybridisation analysis for MYC rearrangements, visual assesment, semiquantitative analysis of ¹⁸F-FDG PET scans and patient survival analysis were performed in 61 DLBCL patients, treated at a single referral hospital between 2008 and 2015.

Results

Of 61 tumours, 21 (34%) had a MYC rearrangement (MYC⁺). MYC status was neither associated with the presence of necrosis on ¹⁸F-FDG PET scans (necrosis^PET; p = 1.0) nor associated with the investigated semiquantitative parameters maximum standard uptake value (SUV_max; p = 0.43), single highest SUV_max (p = 0.49), metabolic active tumour volume (MATV; p = 0.68) or total lesion glycolysis (TLG; p = 0.62). A multivariate patient survival analysis of the entire cohort showed necrosis^PET as an independent prognostic marker for disease-specific survival (DSS) (HR = 13.9; 95% CI 3.0–65; p = 0.001).

Conclusions

MYC rearrangements in DLBCL have no influence on the visual parameter necrosis^PET or the semi-quantiative parameters SUV_max, MATV and TLG. Irrespective of MYC rearrangements, necrosis^PET is an independent, adverse prognostic factor for DSS.

Key Points

• Retrospective analysis indicates that MYC rearrangement is not associated with necrosis on¹⁸F-FDG PET (necrosis^PET) scans or semiquantitative¹⁸F-FDG PET parameters.

• Necrosis^PETis a potential independent adverse prognostic factor for disease-specific survival in patients with DLBCL and is not influenced by the presence of MYC rearrangements.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06178-9) contains supplementary material, which is available to authorized users.

Tumor Identification of Less Aggressive or Indolent Lymphoma With Whole-Body 11C-Acetate PET/CT

PURPOSE

The aim of this study was to investigate the diagnostic performance of whole-body [C]acetate PET/CT in less aggressive or indolent lymphomas, wherein [F]FDG PET/CT would exhibit limited sensitivity.

METHODS

Between September 2016 and May 2018, we prospectively evaluated 17 patients (9 men, 8 women; mean age [range], 71 [45-87] years) with pathologically proven less aggressive or indolent lymphomas according to Non-Hodgkin's Lymphoma Classification Project, using both [F]FDG PET/CT and [C]acetate PET/CT (performed on the same day). Detected nodal lesions were recorded according to the Ann Arbor classification. Extranodal (EN) lesions were also evaluated. We compared whole-body lesion detection between [F] FDG PET/CT and [C]acetate PET/CT using the McNemar test.

RESULTS

In all patients, significantly more nodal and EN lesions were detected using [C]acetate PET/CT than [F]FDG PET/CT (nodal: 84 vs 64 regions; P < 0.001; EN: 26 vs 19 regions, P = 0.039). Bone lesions were detected in 8 and 5 patients using [C]acetate PET/CT and [F]FDG PET/CT, respectively (P = 0.25). Among the 14 patients (82.4%) who underwent bone marrow biopsy, bone marrow involvement was detected with sensitivities of 100% (6/6 patients) and 80% (5/6 patients) using [C]acetate PET/CT and [F]FDG PET/CT, respectively. Multiple areas of focal uptake in the spleen of 1 patient were exhibited on [F]FDG PET/CT but not [C]acetate PET/CT.

CONCLUSIONS

[C]acetate PET/CT exhibited greater sensitivity than [F]FDG PET/CT for lesion detection in patients with less aggressive or indolent lymphomas, thus promising applicability as a physiological tracer in the study of such lesions.

Uptake of [18F]fluorodeoxyglucose in initial positron-emission tomography predicts survival in MALT lymphoma

The role of [¹⁸F]fluorodeoxyglucose (FDG) positron-emission tomography (PET) in mucosa-associated lymphoid tissue (MALT) of marginal zone lymphoma remains poorly defined. We correlated initial PET with pathology, clinical factors, and outcome. From January 2001 to July 2012, 173 MALT lymphoma patients with a biopsied lesion identified on PET within 90 days of tissue biopsy were analyzed. PET positivity and intensity of FDG uptake were correlated with clinical factors and patient outcome. Among 173 accrued cases, biopsied site was PET avid in 123 patients (71%); median standardized uptake value (SUV) was 6.0 (range: 0.7-28.0), and SUV >10.0 in 20 patients (16%). PET avidity varied by organ sites. PET positivity correlated with higher International Prognostic Index, but not with 5-year overall survival (OS; 96% vs 88%, PET negative vs positive, P = .229) or 5-year progression-free survival (67% vs 56%, P = .493). SUV was an independent prognostic factor of OS, and an increased SUV was associated with a decreasing 5-year OS. Patients who presented with SUV ≥10 had a higher rate of subsequent large cell transformation (20% vs 5%, P = .035) and inferior OS (78% vs 92%, P = .008). The exact role of FDG PET in the management of MALT lymphoma, beyond initial staging, remains to be defined.

Is True Whole-Body 18F-FDG PET/CT Required in Pediatric Lymphoma? An IAEA Multicenter Prospective Study

Guidelines recommend true whole-body ¹⁸F-FDG PET/CT scans from vertex to toes in pediatric lymphoma patients, although this suggestion has not been validated in large clinical trials. The objective of the study was to evaluate the incidence and clinical impact of lesions outside the "eyes to thighs" regular field of view (R-FOV) in ¹⁸F-FDG PET/CT staging (sPET) and interim (iPET) scans in pediatric lymphoma patients. Methods: True whole-body sPET and iPET scans were prospectively obtained in pediatric lymphoma patients (11 worldwide centers). Expert panel central review of sPET and iPET scans were evaluated for lymphoma lesions outside the R-FOV and clinical relevance of these findings. Results: A total of 610 scans were obtained in 305 patients. The sPET scans did not show lesions outside the R-FOV in 91.8% of the patients, whereas in 8.2% patients the sPET scans demonstrated lesions also outside the R-FOV (soft tissue, bone, bone marrow, and skin); however, the presence of these lesions did not change the clinical stage of any patient and did not affect treatment decision. Among the 305 iPET scans, there were no new positive ¹⁸F-FDG-avid lesions outside the R-FOV, when compared with their paired sPET scans. A single lesion outside the R-FOV on iPET occurred in 1 patient (0.3%), with the primary lesion diagnosed in the femur on sPET that persisted on iPET. Conclusion: The identification of additional lesions outside the R-FOV (eyes to thighs) using ¹⁸F-FDG PET/CT has no impact in the definition of the clinical stage of disease and minimal impact in the treatment definition of patients with pediatric lymphoma. As so, R-FOV for both sPET and iPET scans could be performed.

18F-FDG PET/CT in splenic marginal zone lymphoma

PURPOSE

The detection rate and the metabolic behavior of 18F-FDG-PET/CT in splenic marginal zone lymphoma (SMZL) are not yet clear. Our aim was to investigate the metabolic behavior of SMZL and whether the tumor stage (acc. Ann Arbor) epidemiological (age, gender), histological (Ki-67 index, plasmacytic differentiation), and morphological (splenic diameter maximum) features might be related to 18F-FDG PET/CT results.

METHODS

Fifty-one patients (34 male, 17 female; average age 70 years) with histologically confirmed SMZL who underwent a 18F-FDG PET/CT for initial staging were included: PET/CT images were analyzed visually and semi-quantitatively (SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio). Splenic uptake was divided as diffuse or focal.

RESULTS

Thirty-nine patients (76%) had FDG-avid SMZL (7 with focal splenic lesions and 32 with diffuse splenic uptake), while the remaining 12 had no increased splenic uptake. Among patients with FDG-avid lesions, average SUVmax was 4.3, lesion-to-liver SUVmax ratio 2.3, and lesion-to-blood pool SUVmax ratio 3. 18F-FDG avidity was significantly associated with Ki-67 index and not correlated with other features. Semiquantitative PET/CT parameters (SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio) did not correlate significantly with any variable. Progression-free survival time was not influenced by FDG avidity of SMZL.

CONCLUSIONS

18F-FDG avidity was noted in 76% of SMZL with diffuse splenic uptake as main pattern of presentation and is correlated with Ki-67 score only.

Lactate dehydrogenase levels and 18F-FDG PET/CT metrics differentiate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma

PURPOSE

This study aims to investigate whether clinical, laboratory, and fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT findings can discriminate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma (PMBCL).

PATIENTS AND METHODS

This retrospective study included 56 patients (42 with mediastinal Hodgkin's lymphoma and 14 with PBMCL). Differences in clinical, laboratory, and F-FDG PET/CT metrics were assessed between Hodgkin's lymphoma and PMBCL.

RESULTS

Lactate dehydrogenase (LDH) and F-FDG PET/CT-based maximum tumor diameter, lesion-to-liver ratio maximum standardized uptake value (SUVmax), and lesion-to-liver ratio peak standardized uptake value (SUVpeak) were all significantly higher (P<0.001) in PMBCL than in Hodgkin's lymphoma, and PMBCL also significantly more frequently (P=0.001) exhibited necrosis on F-FDG PET/CT than Hodgkin's lymphoma. LDH, maximum tumor diameter, lesion-to-liver ratio SUVmax, and lesion-to-liver ratio SUVpeak yielded areas under the receiver operating characteristic curve of 0.968 [95% confidence interval (CI): 0.923-1.000], 0.866 (95% CI: 0.765-0.968), 0.875 (95% CI: 0.776-0.975), and 0.874 (95% CI: 0.771-0.976), respectively. LDH (with cutoff of 236 U/l) achieved sensitivity and specificity of 81.6 and 100%, respectively; maximum tumor diameter (with cutoff of 9.98 cm) achieved sensitivity and specificity of 87.2 and 78.3%, respectively; lesion-to-liver ratio SUVmax (with cutoff of 7.12) achieved sensitivity and specificity of 94.9 and 64.3%, respectively; lesion-to-liver ratio SUVpeak (with cutoff of 11.45) achieved sensitivity and specificity of 97.4 and 64.3%, respectively; and the presence of necrosis achieved sensitivity and specificity of 78.6 and 74.4%, respectively, in discriminating PMBCL from Hodgkin's lymphoma.

CONCLUSION

LDH levels and several F-FDG PET/CT findings (tumor size, presence of necrosis, and degree of F-FDG uptake) are helpful in discriminating mediastinal Hodgkin's lymphoma from PMBCL.

Theranostic Radiolabeled Anti-CD20 sdAb for Targeted Radionuclide Therapy of Non-Hodgkin Lymphoma

Anti-CD20 radioimmunotherapy is an effective approach for therapy of relapsed or refractory CD20^pos lymphomas, but faces limitations due to poor tumor penetration and undesirable pharmacokinetics of full antibodies. Camelid single-domain Ab fragments (sdAb) might circumvent some of the limitations of radiolabeled full antibodies. In this study, a set of hCD20-targeting sdAbs was generated, and their capacity to bind hCD20 was evaluated in vitro and in vivo A lead sdAb, sdAb 9079, was selected on the basis of its specific tumor targeting and significant lower kidney accumulation compared with other sdAbs. SdAb 9079 was then radiolabeled with ⁶⁸Ga and ¹⁷⁷Lu for PET imaging and targeted therapy. The therapeutic potential of ¹⁷⁷Lu-DTPA-sdAb was compared with that of ¹⁷⁷Lu-DTPA-rituximab and unlabeled rituximab in mice bearing hCD20^pos tumors. Radiolabeled with ⁶⁸Ga, sdAb 9079 showed specific tumor uptake, with very low accumulation in nontarget organs, except kidneys. The tumor uptake of ¹⁷⁷Lu-DTPA-sdAb 9079 after 1.5 h was 3.4 ± 1.3% ID/g, with T/B and T/M ratios of 13.3 ± 4.6 and 32.9 ± 15.6. Peak tumor accumulation of ¹⁷⁷Lu-DTPA-rituximab was about 9 times higher, but concomitantly with high accumulation in nontarget organs and very low T/B and T/M ratios (0.8 ± 0.1 and 7.1 ± 2.4). Treatment of mice with ¹⁷⁷Lu-DTPA-sdAb 9079 significantly prolonged median survival compared with control groups and was as effective as treatment with rituximab or its ¹⁷⁷Lu-labeled variant. Taken together, sdAb 9079 displays promising features as a theranostic drug to treat CD20^pos lymphomas. Mol Cancer Ther; 16(12); 2828-39. ©2017 AACR.

Prognostic value of pre-transplant PET/CT in patients with diffuse large B-cell lymphoma undergoing autologous stem cell transplantation

Pre-transplant PET/CT may be prognostic in diffuse large B-cell lymphoma (DLBCL) patients undergoing autologous stem cell transplantation (ASCT). We reviewed relapsed and pre-transplant PET/CT scans of 32 patients with DLBCL treated with ASCT to determine the Deauville score and the maximum standardized uptake value (SUV_max). Patients with a Deauville score of 4 had a significantly inferior prognosis. The 3-year progression-free survival (PFS) for patients with Deauville 1-3 score was 64%, compared to 0% for Deauville 4, while the 3-year overall survival (OS) was 84% and 25%, respectively (p < .001, p = .002). The change in the SUV_max (>66 versus ≤66%) was not predictive of PFS or OS, but a high pre-transplant SUV_max (>6) demonstrated a trend towards an inferior PFS. Pre-transplant PET/CT is a tool for identifying DLBCL patients at high risk for treatment failure with ASCT and could be used to risk-stratify patients in prospective clinical trials of novel transplant strategies.

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

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

FDG-PET Scan: a new Paradigm for Follicular Lymphoma Management

In the present review, the reader will be led to the most relevant observations that prompted oncologists and haematologist to consider FDG-PET/CT as a new paradigm for FL management in clinical practice. The role of functional imaging in lymphoma staging, restaging, prognostication, and metabolic tumour volume computing will be reviewed in detail. Moreover, a special focus will be addressed to technical and practical aspects of PET scan reporting, which have been set during the last decade to ensure the reproducibility of the therapeutic results. Finally, the predictive role of PET/CT on long-term treatment outcome will be compared with another well-known prognosticator as minimal residual disease (MRD) detection by Immunoglobulin gene rearrangement assessment.

Recommendations for the management of adrenal incidentalomas: what is pertinent for radiologists?

Adrenal incidentalomas are unsuspected, asymptomatic adrenal masses detected on imaging. Most are non-functioning benign adrenocortical adenomas but can represent other benign lesions or lesions requiring therapeutic intervention including adrenocortical carcinoma, pheochromocytoma, hormone-producing adenoma or metastasis. This review summarizes and highlights radiological recommendations within the recently issued guidelines for the management of adrenal incidentalomas from the European Society of Endocrinology Clinical Practice in collaboration with the European Network for Study of Adrenal Tumours. Four pre-defined clinical questions were addressed in the guidelines and two have specific relevance and implications for radiologists: (1) how to assess risk of malignancy on imaging and (2) what follow-up is indicated if an adrenal incidentaloma is not surgically removed? The guidelines also include recommendations for frequently encountered special circumstances, including bilateral incidentalomas, incidentalomas in patients with extra-adrenal malignancy and in the young and elderly patients. This review highlights radiological recommendations within the guidelines and evidence used for formulating the guidelines.

Current Role of FDG-PET in Pediatric Hodgkin's Lymphoma

Hodgkin's lymphoma is one of the most curable pediatric cancers with long-term survival rates exceeding 90% following intensive treatment. Collaborative group studies worldwide aim on reduction or elimination of radiotherapy to avoid potentially life-limiting late effects especially second cancers and cardiovascular diseases. Large prospective trials have integrated early response FDG-PET scans to identify adequate responders to chemotherapy in whom radiotherapy may safely be omitted. The criteria for interpretation of early response PET have changed during the past years and will be further refined based on trial results. FDG-PET is also systematically used to assess initial disease involvement of pediatric Hodgkin's lymphoma and could replace bone marrow biopsy. This article summarizes the role of FDG-PET in staging and response assessment focusing on large pediatric trials, the criteria for PET interpretation and pitfalls.

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.

18F-fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

AIM

To compare ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) features in gastric lymphoma and gastric carcinoma.

METHODS

Patients with newly diagnosed gastric lymphoma or gastric carcinoma who underwent ¹⁸F-FDG PET/CT prior to treatment were included in this study. We reviewed and analyzed the PET/CT features of gastric wall lesions, including FDG avidity, pattern (focal/diffuse), and intensity [maximal standard uptake value: (SUVmax)]. The correlation of SUVmax with gastric clinicopathological variables was investigated by χ² test, and receiver-operating characteristic (ROC) curve analysis was performed to determine the differential diagnostic value of SUVmax-associated parameters in gastric lymphoma and gastric carcinoma.

RESULTS

Fifty-two patients with gastric lymphoma and 73 with gastric carcinoma were included in this study. Abnormal gastric FDG accumulation was found in 49 patients (94.23%) with gastric lymphoma and 65 patients (89.04%) with gastric carcinoma. Gastric lymphoma patients predominantly presented with type I and type II lesions, whereas gastric carcinoma patients mainly had type III lesions. The SUVmax (13.39 ± 9.24 vs 8.35 ± 5.80, P < 0.001) and SUVmax/THKmax (maximal thickness) (7.96 ± 4.02 vs 4.88 ± 3.32, P < 0.001) were both higher in patients with gastric lymphoma compared with gastric carcinoma. ROC curve analysis suggested a better performance of SUVmax/THKmax in the evaluation of gastric lesions between gastric lymphoma and gastric carcinoma in comparison with that of SUVmax alone.

CONCLUSION

PET/CT features differ between gastric lymphoma and carcinoma, which can improve PET/CT evaluation of gastric wall lesions and help differentiate gastric lymphoma from gastric carcinoma.

Comparison of 11C-Methionine and 18F-FDG PET/CT for Staging and Follow-up of Pediatric Lymphoma

Methionine transport across plasma membranes occurs via the large amino acid transporter, which is overexpressed in malignant cells, leading to tracer accumulation within tumors. We investigated the uptake of ¹¹C-methionine (¹¹C-MET) in children and young adults with Hodgkin lymphoma (HL) or non-Hodgkin lymphoma (NHL) and compared the biodistribution of ¹¹C-MET PET/CT with that of ¹⁸F-FDG PET/CT. Methods: Conducted under an investigational new drug authorization, we prospectively enrolled patients with newly diagnosed HL (n = 19) and NHL (n = 2) onto the Institutional Review Board-approved investigation of ¹¹C-MET PET/CT. After a minimum 4-h fast, patients received 740 MBq/1.7 m² (maximum, 740 MBq [20 mCi/1.7 m²; maximum, 20 mCi]) of ¹¹C-methionine intravenously. PET/CT was performed 5 min after injection from the vertex to thighs at 3 min per bed position. In a separate session, patients received 5.5 MBq/kg (maximum, 485 MBq [0.15 mCi/kg; maximum, 12 mCi]) of ¹⁸F-FDG with imaging initiated approximately 1 h after radiopharmaceutical administration. All studies were reviewed by consensus of 2 senior imaging specialists. The presence of metabolic activity on baseline studies was compared among 17 nodal groups. Results: Eighteen patients (11 male; median age, 15.2 y; age range, 9.5-22.6 y) comprised the study cohort. All had paired ¹¹C-MET PET/CT and ¹⁸F-FDG PET/CT studies at diagnosis. At baseline, 3 nodal groups demonstrating discordant metabolic activity by both ¹⁸F-FDG PET/CT and ¹¹C-MET PET/CT were Waldeyer's ring, paraaortic region, and the liver. All others were found to have concordant metabolic activity. Normal intense ¹¹C-MET uptake in the pancreas and liver reduced sensitivity for disease detection in these regions. At follow-up, 14 of 15 study pairs had concordant results. Conclusion:¹¹C-MET uptake is elevated in most regions involved with lymphoma at diagnosis and follow-up. Its utility in the abdomen is limited by uptake in normal structures.

Management of adrenal incidentalomas: European Society of Endocrinology Clinical Practice Guideline in collaboration with the European Network for the Study of Adrenal Tumors

: By definition, an adrenal incidentaloma is an asymptomatic adrenal mass detected on imaging not performed for suspected adrenal disease. In most cases, adrenal incidentalomas are nonfunctioning adrenocortical adenomas, but may also represent conditions requiring therapeutic intervention (e.g. adrenocortical carcinoma, pheochromocytoma, hormone-producing adenoma or metastasis). The purpose of this guideline is to provide clinicians with best possible evidence-based recommendations for clinical management of patients with adrenal incidentalomas based on the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. We predefined four main clinical questions crucial for the management of adrenal incidentaloma patients, addressing these four with systematic literature searches: (A) How to assess risk of malignancy?; (B) How to define and manage low-level autonomous cortisol secretion, formerly called 'subclinical' Cushing's syndrome?; (C) Who should have surgical treatment and how should it be performed?; (D) What follow-up is indicated if the adrenal incidentaloma is not surgically removed? SELECTED RECOMMENDATIONS: (i) At the time of initial detection of an adrenal mass establishing whether the mass is benign or malignant is an important aim to avoid cumbersome and expensive follow-up imaging in those with benign disease. (ii) To exclude cortisol excess, a 1mg overnight dexamethasone suppression test should be performed (applying a cut-off value of serum cortisol ≤50nmol/L (1.8µg/dL)). (iii) For patients without clinical signs of overt Cushing's syndrome but serum cortisol levels post 1mg dexamethasone >138nmol/L (>5µg/dL), we propose the term 'autonomous cortisol secretion'. (iv) All patients with '(possible) autonomous cortisol' secretion should be screened for hypertension and type 2 diabetes mellitus, to ensure these are appropriately treated. (v) Surgical treatment should be considered in an individualized approach in patients with 'autonomous cortisol secretion' who also have comorbidities that are potentially related to cortisol excess. (vi) In principle, the appropriateness of surgical intervention should be guided by the likelihood of malignancy, the presence and degree of hormone excess, age, general health and patient preference. (vii) Surgery is not usually indicated in patients with an asymptomatic, nonfunctioning unilateral adrenal mass and obvious benign features on imaging studies. We provide guidance on which surgical approach should be considered for adrenal masses with radiological findings suspicious of malignancy. Furthermore, we offer recommendations for the follow-up of patients with adrenal incidentaloma who do not undergo adrenal surgery, for those with bilateral incidentalomas, for patients with extra-adrenal malignancy and adrenal masses and for young and elderly patients with adrenal incidentalomas.

FDG-PET imaging in hematological malignancies

The majority of aggressive lymphomas is characterized by an up regulated glycolytic activity, which enables the visualization by F-18 FDG-PET/CT. One-stop hybrid FDG-PET/CT combines the functional and morphologic information, outperforming both, CT and FDG-PET as separate imaging modalities. This has resulted in several recommendations using FDG-PET/CT for staging, restaging, monitoring during therapy, and assessment of treatment response as well as identification of malignant transformation. FDG-PET/CT may obviate the need for a bone marrow biopsy in patients with Hodgkin's lymphoma and diffuse large B cell lymphoma. FDG-PET/CT response assessment is recommended for FDG-avid lymphomas, whereas CT-based response evaluation remains important in lymphomas with low or variable FDG avidity. The treatment induced change in metabolic activity allows for assessment of response after completion of therapy as well as prediction of outcome early during therapy. The five-point scale Deauville Criteria allows the assessment of treatment response based on visual FDG-PET analysis. Although the use of FDG-PET/CT for prediction of therapeutic response is promising it should only be conducted in the context of clinical trials. Surveillance FDG-PET/CT after complete remission is discouraged due to the relative high number of false-positive findings, which in turn may result in further unnecessary investigations. Future directions include the use of new PET tracers such as F-18 fluorothymidine (FLT), a surrogate biomarker of cellular proliferation and Ga-68 CXCR4, a chemokine receptor imaging biomarker as well as innovative digital PET/CT and PET/MRI techniques.

A Rare Case of Multilocular Thymic Cyst with Follicular Lymphoid Hyperplasia: Radiologic and Histopathologic Features

Multilocular thymic cysts are rare and acquired lesions induced by an inflammatory arising within the thymus. We report a rare case of multilocular thymic cyst with follicular lymphoid hyperplasia in a 59-year-old female. Chest CT and MRI revealed a large multilocular cystic mass, which contains thick septa and nodules in the thymus. F-18 FDG PET/CT showed almost no FDG uptake of the multilocular cystic mass but moderate FDG uptake of the solid nodules. Extended total thymectomy was performed. Histopathological findings revealed follicular lymphoid hyperplasia of thymic tissue but no neoplastic lesion. Based on these findings, diagnosis of multilocular thymic cyst with follicular lymphoid hyperplasia was made. This is a rare case that preoperatively was difficult to diagnose.

Radiation Dosimetry Study of [(89)Zr]rituximab Tracer for Clinical Translation of B cell NHL Imaging using Positron Emission Tomography

PURPOSE

We evaluated the dosimetry of [(89)Zr]rituximab, an anti-CD20 immunoPET tracer to image B cell non-Hodgkin's lymphoma (NHL) using a humanized transgenic mouse model that expresses human CD20 transgenic mice (huCD20TM).

PROCEDURES

Rituximab was conjugated to desferrioxamine (Df) for radiolabeling of Zirconium-89. [(89)Zr]rituximab (2.8 ± 0.2 MBq) was tail vein-injected into huCD20T mice. Positron emission tomography (PET)/CT imaging was performed on the two groups of mice (blocking = 2 mg/kg pre-dose of rituximab and non-blocking; n = 5) at eight time points (1, 4, 24, 48, 72, 96, 120, and 168 h) post injection.

RESULTS

The novel [(89)Zr]rituximab PET tracer had good immunoreactivity, was stable in human serum, and was able to specifically target human CD20 in mice. The human equivalents of highest dose (mean ± SD) organs with and without pre-dose are liver (345 ± 284 μSv/MBq) and spleen (1165 ± 149 μSv/MBq), respectively.

CONCLUSIONS

Dosimetry of the human patient whole-body dose was found to be 145 MBq per annum, and the patient dose-limiting organ will be the liver (with rituximab pre-dose blocking) and spleen for non-blocking. The [(89)Zr]rituximab (t½ = 78.4 h) imaging of B cell NHL patients could permit the observation of targeting lesions in NHL patients over an extended period due to longer half-life as compared to the [(64)Cu] rituximab (t½ = 12.7 h).

The Value of PET/CT in Detecting Bone Marrow Involvement in Patients With Follicular Lymphoma

Follicular lymphoma (FL) is the 2nd most common type of lymphoma diagnosed in the Western World. Bone marrow (BM) involvement is an adverse prognostic factor in FL, routinely assessed by an arbitrary biopsy of the iliac crest. This study was aimed to investigate the role of positron emission tomography/computed tomography (PET/CT) in identifying BM involvement by FL. In this retrospective, single-center study we reviewed the records of consecutive patients with FL at diagnosis or relapse who underwent staging/restaging workup visual assessment of BM uptake was categorized as either normal, diffusely increased, or focally increased. Quantitative BM fluorine-18-fluro-deoxyglucose (FDG) uptake was measured using mean standardized uptake value (BM-SUVmean). The diagnosis of BM involvement was based on either BM histological findings or disappearance of increased uptake at end-treatment PET/CT in patients who responded to treatment. Sixty eight cases with FL were included. Sixteen (23.5%) had BM involvement, 13 (19.1%) had a biopsy proven involvement, and 3 (4.4%) had a negative BM biopsy, but increased medullary uptake that normalized post-treatment. BM FDG uptake in these patients was diffuse in 8 (50%) and focal in 8 (50%). Focal increased uptake was indicative of BM involvement; however, diffuse uptake was associated with 17 false positive cases (32.7%). Overall, visual assessment of BM involvement had a negative predictive value (NPV) of 100% and a positive predictive value (PPV) of 48.5%. On a quantitative assessment, BM-SUVmean was significantly higher in patients with BM involvement (SUVmean of 3.7 [1.7-6] vs 1.4 [0.4-2.65], P < 0.001). On receiver operator curve (ROC) analysis, BM-SUVmean > 2.7 had a PPV of 100% for BM involvement (sensitivity of 68%), while BM-SUVmean < 1.7 had an NPV of 100% (specificity of 73%). Visual assessment of PET/CT is appropriate for ruling out BM involvement by FL. Although focal increased uptake indicates marrow involvement, diffuse uptake is nonspecific. SUV measurement improves PET/CT diagnostic accuracy, identifying additional 19% of patients with BM involvement that would have been otherwise missed.

PET/CT, MR, and PET/MR in Lymphoma and Melanoma

With the introduction of hybrid imaging technologies such as PET/CT and recently PET/MRI, staging and therapy-response monitoring have evolved. PET/CT has been shown to be of value for routine staging of FDG-avid lymphomas before as well as at the end of treatment. For interim staging, trials are ongoing to evaluate the use of PET/CT. In melanoma, PET/CT can be recommended for stages III and IV diseases for initial staging and before surgery. Studies investigating the use of PET/CT for early therapy response are promising. The role of PET/MR in lymphoma and melanoma imaging has to be defined because no larger studies exist so far. There may be an application of PET/MR in research especially for tumor characterization and therapy response. Furthermore, the potential role of non-FDG tracers is elucidated regarding the assessment of treatment response in targeted drug regimens.

From the radiologic pathology archives: gastrointestinal lymphoma: radiologic and pathologic findings

Gastrointestinal (GI) lymphoma encompasses a heterogeneous group of neoplasms that have a common lymphoid origin but variable pathologic and imaging features. Extranodal marginal zone B-cell lymphoma (ENMZL) and diffuse large B-cell lymphoma (DLBCL) are the most common. ENMZL usually occurs in the stomach, where it is associated with chronic infection by Helicobacter pylori, and is typically a superficial spreading lesion that causes mucosal nodularity or ulceration and mild wall thickening. DLBCL may arise de novo or from transformation of ENMZL or other low-grade lymphomas. This form of lymphoma produces extensive wall thickening or a bulky mass, but obstruction is uncommon. Mantle cell lymphoma is the classic cause of lymphomatous polyposis, but multiple polyps or nodules can also be seen with ENMZL and follicular lymphoma. Burkitt lymphoma is usually characterized by an ileocecal mass or wall thickening in the terminal ileum in young children, often in the setting of widespread disease. Primary GI Hodgkin lymphoma, which is rare, may be manifested by a variety of findings, though stenosis is more common than with non-Hodgkin lymphoma. Enteropathy-associated T-cell lymphoma is frequently associated with celiac disease and is characterized by wall thickening, ulceration, and even perforation of the jejunum. Accurate radiologic diagnosis of GI lymphoma requires a multifactorial approach based on the clinical findings, site of involvement, imaging findings, and associated complications.

Utility of interim and end-of-treatment PET/CT in peripheral T-cell lymphomas: A review of 124 patients

According to the updated guidelines for imaging in lymphoma, 18F-FDG positron emission tomography/computed tomography (PET/CT) is recommended for staging and evaluation of treatment response in FDG-avid lymphomas. The purpose of the study was to evaluate the utility of PET/CT in nodal peripheral T-cell lymphomas (PTCL). Patients with newly diagnosed nodal PTCL (peripheral T-cell lymphoma NOS, anaplastic large-cell lymphoma, or angioimmunoblastic T-cell lymphoma) seen at five Danish hematology centers during the period 2006 to 2012 were included, if they had been pretherapeutically staged with PET/CT. Medical records were reviewed for baseline clinical and follow-up information. Staging, interim (I-PET), and end-of-treatment PET/CT (E-PET) studies were centrally reviewed, and reported using the Deauville 5-point score (DS). A total of 124 patients fulfilled the inclusion criteria. The median age was 58 years, and 88% received CHOP/CHOP-like therapy. Five years PFS and OS of the study population was 36.8% (95% CI 27.3-46.4) and 49.7% (95% CI 38.9-59.6), respectively. The presence of PET/CT-ascertained lung and/or liver involvement was associated with a worse outcome. The sensitivity of PET/CT for detecting biopsy-defined bone marrow involvement was only 18% (95% CI 4-43). An interim DS >3 was not prognostic for worse OS and PFS among CHOP/CHOP-like treated patients in uni- or multivariate analyses. A DS >3 after treatment predicted a worse prognosis. In conclusion, I-PET was not predictive of outcome in CHOP/CHOP-like treated PTCL patients when using the DS. Prospective studies are needed to determine the optimal use of PET/CT in PTCL including the role of quantitative PET/CT analysis.