Different histopathological subtypes of Hodgkin lymphoma show significantly different levels of FDG uptake

Update on FDG-PET in pediatric lymphoma

Lymphoma represent the third most common malignant disease in childhood and adolescence. They are divided into pediatric Hodgkin lymphoma (P-HL) and pediatric non-Hodgkin lymphoma (P-NHL). In P-HL, excellent cure rates are achieved through combined modality treatment using chemotherapy and radiotherapy. For more than 20 years, FDG-PET has been an integral part of the treatment and guides its intensity through improved staging and precise assessment of chemotherapy response. In P-NHL, good cure rates are achieved with chemotherapy alone. At present FDG-PET plays only a subordinate role in the treatment setting. Its potential to contribute to treatment management is far from being fully utilised. In this article, the current status of FDG-PET in pediatric lymphoma is presented in detail. The core elements are the sections on staging and response assessment. In addition, challenges and pitfalls are discussed and future developments are outlined.

A preliminary investigation of the relationship between 18F-FDG PET/CT metabolic parameters and prognosis in angioimmunoblastic T-cell lymphoma

Purpose

The goal of the study was to determine the prognostic significance of metabolic parameters in baseline ¹⁸F-FDG PET/CT images obtained from patients with angioimmunoblastic T-cell lymphoma (AITL).

Methods

Forty patients with pathologically diagnosed AITL who had baseline ¹⁸F-FDG PET/CT between May 2014 and May 2021 were assessed as part of this study. Maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), and total metabolic tumor volume (TMTV) were obtained and analyzed. In addition, many relevant features were evaluated, including sex, age, staging, International Prognostic Index (IPI), prediction index for T-cell lymphoma (PIT), Ki-67, and so on. Estimates of progression-free survival (PFS) and overall survival (OS) were determined using the log-rank test and Kaplan-Meier.

Results

The median follow-up was 30.2 months (interquartile range 9.82-43.03). Throughout the follow-up period, 29 (72.5%) deaths occurred and 22 (55.0%) patients made progress. The rates for 2- and 3-year PFS were 43.6% and 26.4%, respectively. The 3- and 5-year OS were 42.6% and 21.5%. For TMTV, TLG, and SUVmax, the cut-off values were 87.0 cm3, 711.1, and 15.8, respectively. Poorer PFS and OS were substantially correlated with high SUVmax and TLG. An increased TMTV suggested a shorter OS. TLG performed independently as OS predictors in multivariate analysis. The risk score for predicting the prognosis of AITL includes the TMTV, TLG, SUVmax, and IPI scores, with 4.5 for TMTV, 2 for TLG, 1.5 for IPI scores, and 1 for SUVmax. Three risk categories of patients with AITL had 3-year OS rates of 100.0%, 43.3%, and 25.0%, respectively.

Conclusion

Baseline TLG was a strong predictor of OS. Here a new prognostic scoring system for AITL based on the clinical indicators and PET/CT metabolic parameters was constructed, which might make stratification of prognosis easy and also help to individualize treatment.

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.

PET Imaging for Hematologic Malignancies

Hematologic malignancies are a broad category of cancers arising from the lymphoid and myeloid cell lines. The 2016 World Health Organization classification system incorporated molecular markers as part of the diagnostic criteria and includes more than 100 subtypes. This article focuses on the subtypes for which imaging with positron emission tomography/computed tomography (PET/CT) has become an integral component of the patient's evaluation, that is, lymphoma and multiple myeloma. Leukemia and histiocytic and dendritic cell neoplasms are also discussed as these indications for PET/CT are less common, but increasingly seen in clinic.

Comparison of 18F-labelled fluoro-2-deoxyglucose-PET with conventional computed tomography for staging and response assessment in paediatric and adult patients with nodular lymphocyte-predominant Hodgkin's lymphoma

BACKGROUND

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is an uncommon subtype of Hodgkin lymphoma. Data are limited regarding 18F-labelled fluoro-2-deoxyglucose (FDG)-PET use in NLPHL. We are reporting our experience with FDG-PET utility in staging and response assessment NLPHL patients.

METHODS

We retrospectively studied a population of all newly diagnosed or relapsed/refractory patients who underwent both pre-treatment contrast-enhanced computed tomography (CeCT) and an FDG-PET and also at the end of planned treatment.

RESULTS

We identified 68 patients found to have in total 312 scans, 78 paired pre-therapeutic and post-treatment CeCT and FDG-PET scans. Among them, 55 were male, with a median follow-up was 48 months. Median SUV-max was 8.3 (2.0-21.0). FDG-PET and CeCT were concordant in 80% (62/78) of staging scans. In 20% (16/78) of patients in whom a discordance was observed, FDG-PET resulted in upstaging in 13 scans and downstaging in 3 scans. The sensitivity of CeCT was 92% for nodal staging and 42% for extralymphatic staging when compared to FDG-PET. The specificity of CeCT was 98% as compared to FDG-PET. For response assessment, there was poor agreement between the CeCT and FDG-PET in assigning complete remission of disease scores as FDG-PET was able to identify the absence of disease despite the presence of a radiologically evident residual mass on CeCT. The sensitivity for CeCT compared to FDG-PET was 100% while the specificity was 43% for detection of post-treatment response.

CONCLUSION

For NLPHL, pre-therapeutic FDG-PET scan is better than CeCT staging. FDG-PET has much better specificity for response assessment than CeCT.

Baseline total metabolic tumor volume combined with international peripheral T-cell lymphoma project may improve prognostic stratification for patients with peripheral T-cell lymphoma (PTCL)

Purpose

The aim of this study was to explore the prognostic value of total metabolic tumor volume (TMTV) at baseline ¹⁸F-FDG PET/CT in patients diagnosed with peripheral T-cell lymphoma (PTCL).

Materials and methods

Eighty-four newly diagnosed PTCL patients who underwent baseline ¹⁸F-FDG PET/CT prior to treatment between March 2009 and January 2019 were enrolled in this retrospective study. The FDG-avid lesions in each patient were segmented using semiautomated software to calculate the maximum standardized uptake value (SUVmax), total metabolic tumor volume (TMTV), and total lesion glycolysis (TLG) values using the boundaries of voxels presenting with the 41% SUVmax threshold method. Progression-free survival (PFS) and overall survival (OS) were used as end points to evaluate patient prognosis. The log-rank test and Cox regression analyses were used to evaluate PFS and OS.

Results

ROC curve analysis indicated an ideal TMTV cut-off value of 228.8 cm³. During the 4–131 months (29.2 ± 28.5 months) follow-up period, high TMTV was significantly associated with worse PFS and OS. TMTV and the international peripheral T-cell lymphoma project score (IPTCLP) were independent predictors of PFS and OS with multivariate analysis. The combination of TMTV and the IPTCLP may provide significantly better risk substratification in PFS and OS of PTCL patients.

Conclusions

Both TMTV and IPTCLP are independent predictors of PTCL patient survival outcomes. Moreover, the combination of TMTV and IPTCLP improved patient risk stratification and may contribute to personalized therapeutic regimens.

Prognostic value of metabolic tumour volume on baseline 18F-FDG PET/CT in addition to NCCN-IPI in patients with diffuse large B-cell lymphoma: further stratification of the group with a high-risk NCCN-IPI

PURPOSE

The purpose of this study was to determine the prognostic value of metabolic volumetric parameters as a quantitative index on pre-treatment ¹⁸F-FDG PET/CT in addition to the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) in patients with diffuse large B-cell lymphoma (DLBCL).

METHODS

A total of 103 consecutive patients with DLBCL and baseline FDG PET/CT were retrospectively evaluated. Quantitative metabolic parameters, including total metabolic tumour volume (TMTV) using a standardized uptake value (SUV) of ≥2.5 as the threshold, were estimated. Receiver operating characteristic curve analysis was used to determine the optimal cut-off values for the metabolic parameters. The relationships between study variables and patient survival were tested using Cox regression analysis. Patient survival rates were derived from Kaplan-Meier curves and compared using the log-rank test.

RESULTS

Median follow-up was 34 months. In patients with a low TMTV (<249 cm³), the 3-year progression free survival (PFS) rate was 83% and the overall survival (OS) rate was 92%, in contrast to 41% and 57%, respectively, in those with a high TMTV (≥249 cm³). In univariate analysis, a high TMTV and NCCN-IPI ≥4 were associated with inferior PFS and OS (P < 0.0001 for all), as was a high total lesion glycolysis (P = 0.004 and P = 0.005, respectively). In multivariate analysis, TMTV and NCCN-IPI were independent predictors of PFS (hazard ratio, HR, 3.11, 95% confidence interval, CI, 1.37-7.07, P = 0.007, and HR 3.42, 95% CI 1.36-8.59, P = 0.009, respectively) and OS (HR 3.41, 95% CI 1.24-9.38, P = 0.017, and HR 5.06, 95% CI 1.46-17.60, P = 0.014, respectively). TMTV was able to separate patients with a high-risk NCCN-IPI of ≥4 (n = 62) into two groups with significantly different outcomes; patients with low TMTV (n = 16) had a 3-year PFS rate of 75% and an OS rate of 88%, while those with a high TMTV had a 3-year PFS rate of 32% and an OS rate of 47% (χ² = 7.92, P = 0.005, and χ² = 8.26, P = 0.004, respectively). However, regardless of TMTV, patients with a low-risk NCCN-IPI of <4 (n = 41) had excellent outcomes (3-year PFS and OS rates of 85% and 95%, respectively).

CONCLUSION

Pretreatment TMTV was an independent predictor of survival in patients with DLBCL. Importantly, TMTV had an additive prognostic value in patients with a high-risk NCCN-IPI. Thus, the combination of baseline TMTV with NCCN-IPI may improve the prognostication and may be helpful guide the decision for intensive therapy and clinical trials, especially in DLBCL patients with a high-risk NCCN-IPI.

Multiple Cavitary Lung Lesions in an Adolescent: Case Report of a Rare Presentation of Nodular Lymphocyte Predominant Hodgkin Lymphoma

A 14-year-old male patient presented with a nonproductive cough, weight loss, fatigue, and malaise. A chest radiograph showed large bilateral cavitary lung lesions in both upper and lower lobes that failed to improve with antibiotics and anti-inflammatory medications. Infectious and rheumatologic work-ups were negative. Thoracoscopic lung biopsies were diagnostic for nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). The patient received combination chemotherapy and immunotherapy based on current treatment standards with an excellent clinical response. NLPHL is a rare B-cell lymphoma that typically presents as peripheral lymph nodal disease, clinically distinct from classical Hodgkin lymphoma. The prognosis of NLPHL in children is favorable, although relapse rates are high. This case details several unique features of NLPHL and describes the presentation, diagnosis, and treatment of an adolescent male with a rare pulmonary and cervical NLPHL, the first such case described in a pediatric patient.

Metabolic Tumor Volume Metrics in Lymphoma

Although visual assessment using the Deauville criteria is strongly recommended by guidelines for treatment response monitoring in all FDG-avid lymphoma histologies, the high rate of false-positives and concerns about interobserver variability have motivated the development of quantitative tools to facilitate objective measurement of tumor response in both routine and clinical trial settings. Imaging studies using functional quantitative measures play a significant role in profiling oncologic processes. These quantitative metrics allow for objective end points in multicenter clinical trials. However, the standardization of imaging procedures including image acquisition parameters, reconstruction and analytic measures, and validation of these methods are essential to enable an individualized treatment approach. A robust quality control program associated with the inclusion of proper scanner calibration, cross-calibration with dose calibrators and across other scanners is required for accurate quantitative measurements. In this section, we will review the technical and methodological considerations related to PET-derived quantitative metrics and the relevant published data to emphasize the potential value of these metrics in the prediction of patient prognosis in lymphoma.

Prognostic value of baseline, interim and end-of-treatment 18F-FDG PET/CT parameters in extranodal natural killer/T-cell lymphoma: A meta-analysis

METHODS

We searched the PubMed, EMBASE, Cochrane Library and Medline databases for eligible articles. SUVmax, MTV, and TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT were regarded as efficacy data. Combined hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were estimated using RevMan 5.3 software.

RESULTS

Nine trials with a total of 535 ENKTL patients were included. SUVmax, MTV and TLG on B-PET/CT were significantly associated with PFS with HRs of 2.78 (95%CI 1.54-5.03), 3.61 (95%CI 1.96-6.65) and 5.62 (95%CI 1.94-16.33), respectively, and with OS with HRs of 4.78 (95%CI 2.29-9.96), 3.20 (95%CI 1.55-6.60) and 7.76 (95%CI 1.79-33.58), respectively. For the DS on I-PET/CT, the HRs for PFS and OS were 5.15 (95%CI 2.71-9.80) and 5.80 (95%CI 2.28-14.73), respectively. Similarly, the DS on E-PET/CT was a significant predictor of PFS and OS with HRs of 3.65 (95%CI 2.13-6.26) and 3.32 (95%CI 1.79-6.15), respectively.

CONCLUSION

Our results suggest that SUVmax, MTV, TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT may be significant prognostic indicators for PFS and OS in ENKTL patients. Moreover, TLG tends to be superior to SUVmax and MTV on B-PET/CT for predicting survival of ENKTL patients. Therefore, response monitoring and prognostication assessments based on multiple PET/CT parameters should be considered in the management of ENKTL patients.

Hodgkin's lymphoma and its association with EBV and HIV infection

Hodgkin's lymphoma (HL) constitutes a clonal expansion of what appears to be malignant B cells. Viruses are involved in its pathogenesis, such as the Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV). Since these viral infections have been shown to play key roles in the pathogenesis of HL, countries with a prevalence of HIV and EBV represent interesting population targets to study the pathogenesis of HL, linking the evolution of the disease with viral infections. Usually, patients present with late stage disease often involving the bone marrow at the time of diagnosis. The present paper discusses the role of viral infection in African countries, as HL is considered to be a malignant disease characterized by an inflammatory reaction to an aberrant B cell clone that is well known as the Reed-Sternberg cell (HRS).

Advanced stage nodular lymphocyte predominant Hodgkin lymphoma in children and adolescents: clinical characteristics and treatment outcome - a report from the SFCE & CCLG groups

Advanced stage nodular lymphocyte predominant Hodgkin lymphoma (nLPHL) is extremely rare in children and as a consequence, optimal treatment for this group of patients has not been established. Here we retrospectively evaluated the treatments and treatment outcomes of 41 of our patients from the UK and France with advanced stage nLPHL. Most patients received chemotherapy, some with the addition of the anti CD20 antibody rituximab or radiotherapy. Chemotherapy regimens were diverse and followed either classical Hodgkin lymphoma or B non-Hodgkin lymphoma protocols. All 41 patients achieved a complete remission with first line treatment and 40 patients are alive and well in remission. Eight patients subsequently relapsed and 1 patient died of secondary cancer (9 progression-free survival events). The median time to progression for those who progressed was 21 months (5·9-73·8). The median time since last diagnosis is 87·3 months (8·44-179·20). Thirty-six (90%), 30 (75%) and 27 (68%) patients have been in remission for more than 12, 24 and 36 months, respectively. Overall, the use of rituximab combined with multi-agent chemotherapy as first line treatment seems to be a reasonable therapeutic option.

Relapsed or poorly responsive nodular lymphocyte predominant Hodgkin lymphoma in children and adolescents - a report from the United Kingdom's Children's Cancer and Leukaemia Study Group

There is a paucity of data on the treatment outcome in children with relapsed or poorly responsive nodular lymphocyte predominant Hodgkin lymphoma (nLPHL). This retrospective report evaluates the treatment outcome in a national cohort of children with relapsed or poorly responsive nLPHL. A total of 37 patients, 22 with relapsed and 15 with poorly responding disease, are the subjects of this report. Of the 22 patients with relapsed nLPHL, 11 had relapsed after primary excision biopsy, 10 after chemotherapy and 1 after chemotherapy and involved field radiotherapy. The majority had localized disease at relapse. The median time to relapse was 8 months after chemotherapy and 11 months after excision biopsy. Seven of the 15 patients with poorly responding nLPHL had variant histology. Three patients with initial poor response did not receive any further treatment and have had no disease progression. Transformation to diffuse large B cell lymphoma, in addition to evolution from typical to variant nLPHL occurred in one patient each. Thirty-four patients have been successfully re-treated with second chemotherapy or radiotherapy. Multiple relapses were uncommon but treatable. Relapse or poorly responsive nLPHL is fully salvageable with either additional chemotherapy and or radiotherapy.

Influence of Software Tool and Methodological Aspects of Total Metabolic Tumor Volume Calculation on Baseline [18F]FDG PET to Predict Survival in Hodgkin Lymphoma

AIM

To investigate the respective influence of software tool and total metabolic tumor volume (TMTV0) calculation method on prognostic stratification of baseline 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG-PET) in newly diagnosed Hodgkin lymphoma (HL).

METHODS

59 patients with newly diagnosed HL were retrospectively included. [18F]FDG-PET was performed before any treatment. Four sets of TMTV0 were calculated with Beth Israel (BI) software: based on an absolute threshold selecting voxel with standardized uptake value (SUV) >2.5 (TMTV02.5), applying a per-lesion threshold of 41% of the SUV max (TMTV041) and using a per-patient adapted threshold based on SUV max of the liver (>125% and >140% of SUV max of the liver background; TMTV0125 and TMTV0140). TMTV041 was also determined with commercial software for comparison of software tools. ROC curves were used to determine the optimal threshold for each TMTV0 to predict treatment failure.

RESULTS

Median follow-up was 39 months. There was an excellent correlation between TMTV041 determined with BI and with the commercial software (r = 0.96, p<0.0001). The median TMTV0 value for TMTV041, TMTV02.5, TMTV0125 and TMTV0140 were respectively 160 (used as reference), 210 ([28;154] p = 0.005), 183 ([-4;114] p = 0.06) and 143 ml ([-58;64] p = 0.9). The respective optimal TMTV0 threshold and area under curve (AUC) for prediction of progression free survival (PFS) were respectively: 313 ml and 0.70, 432 ml and 0.68, 450 ml and 0.68, 330 ml and 0.68. There was no significant difference between ROC curves. High TMTV0 value was predictive of poor PFS in all methodologies: 4-years PFS was 83% vs 42% (p = 0.006) for TMTV02.5, 83% vs 41% (p = 0.003) for TMTV041, 85% vs 40% (p<0.001) for TMTV0125 and 83% vs 42% (p = 0.004) for TMTV0140.

CONCLUSION

In newly diagnosed HL, baseline metabolic tumor volume values were significantly influenced by the choice of the method used for determination of volume. However, no significant differences were found in term of prognosis.

Image-guided radiation therapy in lymphoma management

Image-guided radiation therapy (IGRT) is a process of incorporating imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), Positron emission tomography (PET), and ultrasound (US) during radiation therapy (RT) to improve treatment accuracy. It allows real-time or near real-time visualization of anatomical information to ensure that the target is in its position as planned. In addition, changes in tumor volume and location due to organ motion during treatment can be also compensated. IGRT has been gaining popularity and acceptance rapidly in RT over the past 10 years, and many published data have been reported on prostate, bladder, head and neck, and gastrointestinal cancers. However, the role of IGRT in lymphoma management is not well defined as there are only very limited published data currently available. The scope of this paper is to review the current use of IGRT in the management of lymphoma. The technical and clinical aspects of IGRT, lymphoma imaging studies, the current role of IGRT in lymphoma management and future directions will be discussed.

Cervical lymph node hyperplasia on [(18)F]-fluorodeoxyglucose positron emission tomography/computed tomography scan after treatment of children and adolescents with malignant lymphoma

PURPOSE

To define imaging manifestations and clinical prognosis of cervical lymph node hyperplasia using [(18)F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scanning after treatment of children and adolescents with malignant lymphoma.

METHODS

Children and adolescent patients with malignant lymphoma who had high FDG uptake in their cervical lymph nodes via PET/CT after treatment, which was not due to tumor recurrence or residue, were retrospectively analyzed.

RESULTS

Twenty-seven patients with a median age of 12 years were included; 11 had Hodgkin's disease and 16 had non-Hodgkin's lymphoma. The time from PET/CT scan to completion of therapy was 1-36 months, 85.2% (23/27) of which took place within 12 months. Three patients had confirmed lymph node follicular hyperplasia by biopsy, while all 27 patients achieved disease-free survival during the follow-up period. The maximum standardized uptake values (SUVmax) of cervical lymph nodes were 2.2-16.2 and the maximum short axis ranged from 0.3 to 1.2 cm. Cervical lymph node hyperplasia was noted in neck levels I-V, and neck level II bilaterally had the highest incidence (100%). Bilateral cervical lymph node hyperplasia was symmetrical in terms of both the SUVmax and affected locations. Thymic hyperplasia and nasopharyngeal lymphoid hyperplasia were both observed in 24 patients (88.9%). There was no relationship in terms of the SUVmax between cervical lymph nodes and thymic tissue, cervical nodes or nasopharyngeal lymphoid tissue.

CONCLUSION

Cervical lymph node hyperplasia with high FDG uptake on PET/CT scans found after treating children and adolescents with malignant lymphoma can be benign processes. Awareness of this possibility may help avoid invasive procedures and over-treatment.

Performance of FDG PET/CT at initial diagnosis in a rare lymphoma: nodular lymphocyte-predominant Hodgkin lymphoma

PURPOSE

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare Hodgkin lymphoma distinguished from classical Hodgkin lymphoma (cHL) by the nature of the neoplastic cells which express B-cell markers. We wanted to determine the diagnostic performance of FDG PET/CT in initial assessment and its therapeutic impact on staging.

METHODS

We retrospectively studied a population of 35 patients with NLPHL (8 previously treated for NLHPL, 27 untreated). All patients underwent an initial staging by pretherapeutic FDG PET/CT. The impact on initial stage or relapse stage was assessed by an independent physician.

RESULTS

In a per-patient analysis, the sensitivity of the pretherapeutic FDG PET/CT was 100%. In a per-site analysis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of pretherapeutic FDG PET/CT were 100%, 99%, 97%, 100% and 99%, respectively. Pretherapeutic FDG PET/CT led to a change in the initial stage/relapse stage in 12 of the 35 patients (34%). In contrast to previous results established without FDG PET/CT, 20% of patient had osteomedullary lesions.

CONCLUSION

Pretherapeutic FDG PET/CT has excellent performance for initial staging or relapse staging of NLPHL.

Kikuchi-Fujimoto disease mimicking malignant lymphoma with 2-[(18)F]fluoro-2-deoxy-D-glucose PET/CT in children

PURPOSE

Kikuchi-Fujimoto disease (KFD) is a benign disease, which is characterized by a cervical lymphadenopathy with fever, and it often mimics malignant lymphoma (ML). 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) is a powerful imaging modality for the diagnosis, staging and monitoring of ML, with the limitations including the nonspecific FDG uptake in infectious or inflammatory processes. This study compared clinical manifestations and PET/CT findings between KFD and ML patients.

METHODS

We retrospectively reviewed the medical records of 23 patients with KFD and 33 patients with ML, diagnosed histopathologically, between January 2000 and May 2013 at the Department of Pediatrics, Yeungnam University Medical Center. Among them, we analyzed the clinical manifestations, laboratory findings and characteristics, and the amount of (18)F-FDG uptake between 8 KFD and 9 ML patients who had (18)F-FDG PET/CT.

RESULTS

The (18)F-FDG PET/CT maximum standardized uptake values (SUVmax) ranged from 8.3 to 22.5 (mean, 12.0) in KFDs, and from 5.8 to 34.3 (mean, 15.9) in MLs. There were no significant differences in SUVmax between KFDs and MLs. (18)F-FDG PET/CT with ML patients showed hot uptakes in the extranodal organs, such as bone marrow, small bowel, thymus, kidney, orbit and pleura. However, none of the KFD cases showed extranodal uptake (P<0.001). (18)F-FDG PET/CT findings of KFD with nodal involvement only were indistinguishable from those of ML.

CONCLUSION

Patients who had extranodal involvement on PET/CT were more likely to have malignancy than KFD.

A prospective study of ¹⁸FDG-PET with CT coregistration for radiation treatment planning of lymphomas and other hematologic malignancies

PURPOSE

This prospective single-institution study examined the impact of positron emission tomography (PET) with the use of 2-[(18)F] fluoro-2-deoxyglucose and computed tomography (CT) scan radiation treatment planning (TP) on target volume definition in lymphoma.

METHODS AND MATERIALS

118 patients underwent PET/CT TP during June 2007 to May 2009. Gross tumor volume (GTV) was contoured on CT-only and PET/CT studies by radiation oncologists (ROs) and nuclear medicine physicians (NMPs) for 95 patients with positive PET scans. Treatment plans and dose-volume histograms were generated for CT-only and PET/CT for 95 evaluable sites. Paired t test statistics and Pearson correlation coefficients were used for analysis.

RESULTS

70 (74%) patients had non-Hodgkin lymphoma, 10 (11%) had Hodgkin lymphoma, 12 (10%) had plasma-cell neoplasm, and 3 (3%) had other hematologic malignancies. Forty-three (45%) presented with relapsed/refractory disease. Forty-five (47%) received no prior chemotherapy. The addition of PET increased GTV as defined by ROs in 38 patients (median, 27%; range, 5%-70%) and decreased GTV in 41 (median, 39.5%; range, 5%-80%). The addition of PET increased GTV as defined by NMPs in 27 patients (median, 26.5%; range, 5%-95%) and decreased GTV in 52 (median, 70%; range, 5%-99%). The intraobserver correlation between CT-GTV and PET-GTV was higher for ROs than for NMPs (0.94, P<.01 vs 0.89, P<.01). On the basis of Bland-Altman plots, the PET-GTVs defined by ROs were larger than those defined by NMPs. On evaluation of clinical TPs, only 4 (4%) patients had inadequate target coverage (D95 <95%) of the PET-GTV defined by NMPs.

CONCLUSIONS

Significant differences between the RO and NMP volumes were identified when PET was coregistered to CT for radiation planning. Despite this, the PET-GTV defined by ROs and NMPs received acceptable prescription dose in nearly all patients. However, given the potential for a marginal miss, consultation with an experienced PET reader is highly encouraged when PET/CT volumes are delineated, particularly for questionable lesions and to assure complete and accurate target volume coverage.

Symptom-oriented clinical detection versus routine imaging as a monitoring policy of relapse in patients with diffuse large B-cell lymphoma

This study aimed at evaluating the role of routine imaging versus symptom-directed unplanned early outpatient department (OPD) visits in patients with diffuse large B-cell lymphoma (DLBCL) in complete remission (CR) by analyzing the patterns and outcomes of OPD visits for disease monitoring. Patients with DLBCL in CR after treatment in the rituximab era with any OPD monitoring visit were analyzed. A total of 856 OPD visits were recorded: 501 visits were with routine imaging, 322 were without routine imaging and 33 visits (3.9%) were unplanned early visits due to abnormal symptoms. Of the 106 analyzed patients, 15 experienced a relapse (median follow-up duration of 38.1 months). Routine imaging showed an unsatisfactory positive predictive value due to frequent false-positive visits, and a substantial number of patients with false-positive imaging underwent unnecessary biopsies or additional scans. Compared with planned OPD visits, unplanned early visits were highly related to relapse.

F-18 FDG PET/CT quantization parameters as predictors of outcome in patients with diffuse large B-cell lymphoma

AIM

We evaluated the prognostic significance of standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) obtained by F-18 FDG PET/CT (PET/CT) in patients with diffuse large B-cell Lymphomas (DLBCL) presenting intermediate IPI score.

MATERIAL AND METHODS

Fifty-two patients (61 ± 13 yr) underwent PET/CT before the first-line chemotherapy. The mean SUVmax value, the summed MTV (cm(3) ; 42% threshold), and the cumulative TLG (g) were registered. The patients were followed up 18 months thereafter (range 3-41 months). The PET/CT results were compared to the event-free survival (EFS).

RESULTS

At univariate analysis, SUVmax and lactate dehydrogenase (LDH) levels were predictive, but discordantly. The Kaplan-Meier survival analysis for SUVmax showed a significant better EFS in patients presenting higher values as compared to those having lesser (P = 0.0002, HR 0.13). Summed MTV and cumulative TLG were not suitable for predicting EFS.

CONCLUSION

Despite the availability of new tools for the quantitative assessment of disease activity on PET/CT, the SUVmax rather than MTV and TLG remains the only predictor for EFS in DLBCL patients. The magnitude of glycolytic activity rather than the amount of metabolically active burden holds a predominant value for determining the response to chemotherapy in DLBCL.

Positive correlation between baseline PET or PET/CT findings and clinical parameters in multiple myeloma patients

Recently, positron emission tomography (PET) has been incorporated into a series of prospective studies as a predictor of outcomes in multiple myeloma (MM), and the number of (18)F-fluorodeoxuglucose (FDG)-avid focal lesions (FLs) and the intensity of tumor metabolism have been designated as important surrogate markers for predicting prognosis. Here, we compared initial clinical characteristics of MM patients with baseline PET parameters: the number of FLs and the maximum standardized uptake value (SUVmax). A total of 59 patients diagnosed with MM between August 2004 and February 2012 were reviewed. At diagnosis, 23 patients (40.0%) had ≤3 FLs, 11 patients (18.6%) 4-9 FLs, and 25 patients (42.4%) ≥10 FLs. The median SUVmax was 5.3 (range 0-24.3), and 40 patients (67.8%) showed a SUVmax >4. No clinical characteristics were significantly different between groups with a SUVmax ≤4 and a SUVmax >4. However, there were significant differences in several clinical indices between the FLs ≤3 and FLs >3 groups; elevated β2-microglobulin, elevated lactate dehydrogenase, anemia and more advanced disease by the Durie-Salmon stage corresponded to FLs >3 at baseline PET. Adverse baseline PET findings are positively correlated with prognostically relevant clinical parameters. Regarding PET parameters, FLs are more likely to be well correlated with disease aggressiveness and pathophysiology compared to SUVmax.

Gene Expression of Glucose Transporter 1 (GLUT1), Hexokinase 1 and Hexokinase 2 in Gastroenteropancreatic Neuroendocrine Tumors: Correlation with F-18-fluorodeoxyglucose Positron Emission Tomography and Cellular Proliferation

Neoplastic tissue exhibits high glucose utilization and over-expression of glucose transporters (GLUTs) and hexokinases (HKs), which can be imaged by ¹⁸F-Fluorodeoxyglucose-positron emission tomography (FDG-PET). The aim of the present study was to investigate the expression of glycolysis-associated genes and to compare this with FDG-PET imaging as well as with the cellular proliferation index in two cancer entities with different malignant potential. Using real-time PCR, gene expression of GLUT1, HK1 and HK2 were studied in 34 neuroendocrine tumors (NETs) in comparison with 14 colorectal adenocarcinomas (CRAs). The Ki67 proliferation index and, when available, FDG-PET imaging was compared with gene expression. Overexpression of GLUT1 gene expression was less frequent in NETs (38%) compared to CRAs (86%), P = 0.004. HK1 was overexpressed in 41% and 71% of NETs and CRAs, respectively (P = 0.111) and HK2 was overexpressed in 50% and 64% of NETs and CRAs, respectively (P = 0.53). There was a significant correlation between the Ki67 proliferation index and GLUT1 gene expression for the NETs (R = 0.34, P = 0.047), but no correlation with the hexokinases. FDG-PET identified foci in significantly fewer NETs (36%) than CRAs (86%), (P = 0.04). The gene expression results, with less frequent GLUT1 and HK1 upregulation in NETs, confirmed the lower metabolic activity of NETs compared to the more aggressive CRAs. In accordance with this, fewer NETs were FDG-PET positive compared to CRA tumors and FDG uptake correlated with GLUT1 gene expression.

FDG PET/CT in children and adolescents with lymphoma

The aim of this review is to give an overview of FDG PET/CT applications in children and adolescents with lymphoma. Today, FDG PET is used for tailoring treatment intensity in children with Hodgkin lymphoma within the framework of international treatment optimisation protocols. In contrast, the role of this method in children with Non-Hodgkin lymphoma is not well defined. This paper overviews clinical appearance and metabolic behaviour of the most frequent lymphoma subtypes in childhood. The main focus of the review is to summarise knowledge about the role of FDG PET/CT for initial staging and early response assessment.

GLUT1 expression patterns in different Hodgkin lymphoma subtypes and progressively transformed germinal centers

Background

Increased glycolytic activity is a hallmark of cancer, allowing staging and restaging with ¹⁸F-fluorodeoxyglucose-positron-emission-tomography (PET). Since interim-PET is an important prognostic tool in Hodgkin lymphoma (HL), the aim of this study was to investigate the expression of proteins involved in the regulation of glucose metabolism in the different HL subtypes and their impact on clinical outcome.

Methods

Lymph node biopsies from 54 HL cases and reactive lymphoid tissue were stained for glucose transporter 1 (GLUT1), lactate dehydrogenase A (LDHA) and lactate exporter proteins MCT1 and MCT4. In a second series, samples from additional 153 HL cases with available clinical data were stained for GLUT1 and LDHA.

Results

Membrane bound GLUT1 expression was frequently observed in the tumor cells of HL (49% of all cases) but showed a broad variety between the different Hodgkin lymphoma subtypes: Nodular sclerosing HL subtype displayed a membrane bound GLUT1 expression in the Hodgkin-and Reed-Sternberg cells in 56% of the cases. However, membrane bound GLUT1 expression was more rarely observed in tumor cells of lymphocyte rich classical HL subtype (30%) or nodular lymphocyte predominant HL subtype (15%). Interestingly, in both of these lymphocyte rich HL subtypes as well as in progressively transformed germinal centers, reactive B cells displayed strong expression of GLUT1. LDHA, acting downstream of glycolysis, was also expressed in 44% of all cases. We evaluated the prognostic value of different GLUT1 and LDHA expression patterns; however, no significant differences in progression free or overall survival were found between patients exhibiting different GLUT1 or LDHA expression patterns. There was no correlation between GLUT1 expression in HRS cells and PET standard uptake values.

Conclusions

In a large number of cases, HRS cells in classical HL express high levels of GLUT1 and LDHA indicating glycolytic activity in the tumor cells. Although interim-PET is an important prognostic tool, a predictive value of GLUT1 or LDHA staining of the primary diagnostic biopsy could not be demonstrated. However, we observed GLUT1 expression in progressively transformed germinal centers and hyperplastic follicles, explaining false positive results in PET. Therefore, PET findings suggestive of HL relapse should always be confirmed by histology.

Advances in oncologic imaging: update on 5 common cancers

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

Dual-time-point F-18 FDG PET/CT for evaluation in patients with malignant lymphoma

OBJECTIVE

The aim of this study was to evaluate the usefulness of F-18 fluorodeoxyglucose (FDG) dual-time-point (DTP) positron emission tomography (PET)/computed tomography (CT) with semiquantitative analyses for the initial staging in patients with malignant lymphoma.

METHODS

Forty-three patients had DTP PET/CT, with 60-min and 2-h scan [n = 8, Hodgkin's lymphoma (HL); n = 12, indolent non-Hodgkin lymphoma (NHL); n = 23, aggressive NHL].

RESULTS

A total of 524 lesions were evaluated (406 lymph nodes and 118 extra-nodal lesions). The maximum standardized uptake value (SUV(max)) on 2-h delayed scan (SUV(2)) was significantly higher than those on 1-h early scan (SUV(1)) for all groups (P < 0.0001 for HL; P < 0.0001 for indolent NHL; P < 0.0001 for aggressive NHL). Significant differences were detected between HL and indolent NHL, between indolent NHL and the aggressive NHL for both SUV(1) and SUV(2) (each P < 0.0001). No significant differences were detected between HL and aggressive NHL for both SUV(1) and SUV(2) (P = 0.6891 for SUV(1); P = 0.8828 for SUV(2)); however, significant differences were detected for the retention index of SUV(max) between these groups (P = 0.0238).

CONCLUSIONS

DTP F-18 FDG PET/CT with a semiquantitative technique may have the potential to provide the more accurate diagnoses for the staging of malignant lymphoma and the more important role in predicting the histological grades of malignancy compared with single-time-point F-18 FDG-PET scan.

No correlation between glucose metabolism and apparent diffusion coefficient in diffuse large B-cell lymphoma: a PET/CT and DW-MRI study

PURPOSE

Both positron emission tomography/computed tomography (PET/CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) are oncologic feasible techniques for evaluating the malignancy of tumors. Standardized uptake value (SUV) is a marker of tumor glucose metabolism detected by PET/CT. Apparent diffusion coefficient (ADC) measured by DWI can provide information about tissue cellularity. The aim of the study was to evaluate the correlation between SUV and ADC in untreated diffuse large B-cell lymphoma (DLBCL).

MATERIALS AND METHODS

Fifteen pre-therapy patients with histologically proven DLBCL underwent PET/CT and DWI examinations within two days. Tumor glucose metabolism was evaluated by the maximum and mean SUV (SUV(max) and SUV(mean)) on the PET/CT images. The mean ADC value was measured directly on the parametric ADC maps.

RESULTS

In total, 28 lymphoma lesions with best match PET/CT and DWI were identified and evaluated. The mean SUV(max) and SUV(mean) were 16.8 and 11.1, respectively; the mean ADC was 0.74 × 10(-3)mm(2)/s. There was no correlation between the mean ADC and the SUV(max) or SUV(mean).

CONCLUSION

SUV determined from PET/CT and ADC value measured from DWI are different indices for the diagnosis of tumor malignancy, they may provide complimentary functional information of tumor tissue.

A prospective evaluation of staging and target volume definition of lymph nodes by 18FDG PET/CT in patients with squamous cell carcinoma of thoracic esophagus

PURPOSE

To determine an optimal standardized uptake value (SUV) threshold for detecting lymph node (LN) metastases in esophageal cancer using (18)F-Fluorodeoxyglucose positron emission tomography/computer tomography (18FDG PET/CT) and to define the resulting nodal target volume, using histopathology as a "gold standard."

METHODS

Sixteen patients with esophageal squamous cell carcinoma who underwent radical esophagectomy and three-field LN dissection after 18FDG PET/CT and CT scans were enrolled into this study. Locations of LN groups were recorded according to a uniform LN map. Diagnostic performance of different SUV thresholds was assessed by receiver operating characteristic analysis. The optimal cutoff SUV was determined by plotting the false-negative rate (FNR) and false-positive rate (FPR), the sum of both error rates (FNR+FPR), and accuracy against a hypothetical SUV threshold. For each patient, nodal gross tumor volumes (GTVNs) were generated with CT alone (GTVNCT), PET/CT (GTVNPET), and pathologic data (GTVNpath). GTVNCT or GTVNPET was compared with GTVNpath by means of a conformity index (CI), which is the intersection of the two GTVNs divided by the sum of them minus the intersection, e.g., CICT&path=GTVNCT&path/(GTVNCT+GTVNpath-GTVNCT&path).

RESULTS

LN metastases occurred in 21 LN groups among the 144 specimens taken from the 16 patients. The area under the receiver operating characteristic curve was 0.9017±0.0410. The plot of error rates showed a minimum of FNR+FPR for an SUV of 2.36, at which the sensitivity, specificity, and accuracy were 76.19%, 95.93%, and 93.06%, respectively, whereas those of CT were 33.33%, 94.31%, and 85.42% (p values: 0.0117, 0.7539, and 0.0266). Mean GTVNCT, GTVNPET, and GTVNpath were 1.52±2.38, 2.82±4.51, and 2.68±4.16 cm3, respectively. Mean CICT&path and CIPET&path were 0.31 and 0.65 (p value=0.0352).

CONCLUSIONS

Diagnostic superiority of PET/CT at an SUV threshold of 2.36 over CT has potential value in nodal target volume definition, but whether this can contribute to better treatment outcomes needs prospective analyses of recurrences in a larger cohort of patients.

Concordance between four European centres of PET reporting criteria designed for use in multicentre trials in Hodgkin lymphoma

PURPOSE

To determine if PET reporting criteria for the Response Adapted Treatment in Hodgkin Lymphoma (RATHL) trial could enable satisfactory agreement to be reached between 'core' laboratories operating in different countries.

METHODS

Four centres reported scans from 50 patients with stage II-IV HL, acquired before and after two cycles of Adriamycin/bleomycin/vinblastine/dacarbazine. A five-point scale was used to score response scans using 'normal' mediastinum and liver as reference levels. Centres read scans independently of each other. The level of agreement between centres was determined assuming (1) that uptake in sites involved at diagnosis that was higher than liver uptake represented disease (conservative reading), and (2) that uptake in sites involved at diagnosis that was higher than mediastinal uptake represented disease (sensitive reading).

RESULTS

There was agreement that the response scan was 'positive' or 'negative' for lymphoma in 44 patients with a conservative reading and in 41 patients with a sensitive reading. Kappa was 0.85 (95% CI 0.74-0.96) for conservative reading and 0.79 (95% CI 0.67-0.90) for sensitive reading. Agreement was reached in 46 and 44 patients after discussion for the conservative and sensitive readings, respectively.

CONCLUSION

The criteria developed for reporting in the RATHL trial are sufficiently robust to be used in a multicentre setting.

FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease

The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the lymph nodes. Almost any organ can be affected by lymphoma, with the most common extranodal sites of involvement being the stomach, spleen, Waldeyer ring, central nervous system, lung, bone, and skin. The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease has increased in the past decade. The imaging characteristics of extranodal involvement can be subtle or absent at conventional computed tomography (CT). Imaging of tumor metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) has facilitated the identification of affected extranodal sites, even when CT has demonstrated no lesions. More recently, hybrid PET/CT has become the standard imaging modality for initial staging, follow-up, and treatment response assessment in patients with lymphoma and has proved superior to CT in these settings. Certain PET/CT patterns are suggestive of extranodal disease and can help differentiate tumor from normal physiologic FDG activity, particularly in the mucosal tissues, bone marrow, and organs of the gastrointestinal tract. Familiarity with the different extranodal manifestations in various locations is critical for correct image interpretation. In addition, a knowledge of the differences in FDG avidity among the histologic subtypes of lymphoma, appropriate timing of scanning after therapeutic interventions, and use of techniques to prevent brown fat uptake are essential for providing the oncologist with accurate information.

(18)F-FDG PET/CT bone/bone marrow findings in Hodgkin's lymphoma may circumvent the use of bone marrow trephine biopsy at diagnosis staging

PURPOSE

Accurate staging of Hodgkin's lymphoma (HL) is necessary in selecting appropriate treatment. Bone marrow trephine biopsy (BMB) is the standard procedure for depicting bone marrow involvement. BMB is invasive and explores a limited part of the bone marrow. (18)F-FDG PET/CT is now widely used for assessing response to therapy in HL and a baseline study is obtained to improve accuracy. The aim of this retrospective analysis was to assess whether routine BMB remains necessary with concomitant (18)F-FDG PET/CT.

METHODS

Data from 83 patients (newly diagnosed HL) were reviewed. All patients had received contrast-enhanced CT, BMB and (18)F-FDG PET/CT. Results of BMB were not available at the time of (18)F-FDG PET/CT imaging.

RESULTS

Seven patients had lymphomatous involvement on BMB. Four patients had bone involvement on conventional CT (two with negative BMB). All patients with bone marrow and/or bone lesions at conventional staging were also diagnosed on (18)F-FDG PET/CT scan. PET/CT depicted FDG-avid bone/bone marrow foci in nine additional patients. Four of them had only one or two foci, while the other had multiple foci. However, the iliac crest, site of the BMB, was not involved on (18)F-FDG PET/CT. Osteolytic/sclerotic lesions matching FDG-avid foci were visible on the CT part of PET/CT in three patients. MRI ordered in three other patients suggested bone marrow involvement. Interim and/or end-therapy (18)F-FDG PET/CT documented response of FDG-avid bone/bone marrow foci to chemotherapy in every patient.

CONCLUSION

(18)F-FDG PET/CT highly improves sensitivity for diagnosis of bone/bone marrow lesions in HL compared to conventional staging.

Overview of lymphoma diagnosis and management

The malignant lymphomas, including both Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), represent a diverse group of diseases that arise from a clonal proliferation of lymphocytes. Each of the more than 30 unique types of lymphoma is a disease with a distinct natural history. This biologic heterogeneity gives rise to marked differences among the lymphomas with respect to epidemiology, pathologic characteristics, clinical presentation, and optimal management. This article emphasizes the principles of diagnosis, including appropriate pathologic evaluation and staging considerations, and focuses on the clinical presentation, staging, and optimal management strategies for the most common types of lymphoma.

Correlation of apparent diffusion coefficients measured by 3T diffusion-weighted MRI and SUV from FDG PET/CT in primary cervical cancer

PURPOSE

Diffusion-weighted magnetic resonance imaging (DWI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) are oncological feasible techniques. Currently, apparent diffusion coefficient (ADC) measured by DWI and standard uptake value (SUV) from FDG PET/CT have similar applications in clinical oncology. The aim of this study was to assess the correlation between ADC and SUV in primary cervical cancer.

MATERIALS AND METHODS

Patients with documented primary cervical cancer were recruited. All participants underwent abdominopelvic DWI at 3T and FDG PET/CT within 2 weeks. For the primary tumor, ADC was measured as minimum ADC (ADC(min)) and mean ADC (ADC(mean)) within the whole tumor by DWI. Maximum SUV (SUV(max)) and mean SUV (SUV(mean)) were measured by FDG PET/CT.

RESULTS

A total of 33 patients were included. There was no significant correlation either between ADC(min) and SUV(max) or between ADC(mean) and SUV(mean). The relative ADC(min) (rADC(min)) defined as ADC(min)/ADC(mean) ratio was significantly inversely correlated with the relative SUV(max) (rSUV(max)) defined as SUV(max)/SUV(mean) ratio (r = -0.526, P = 0.0017) in all study patients. A significantly inverse correlation between rADC(min) and rSUV(max) was observed in patients with adenocarcinoma/adenosquamous carcinoma (r = -0.685, P = 0.0012) and those with well-to-moderate differentiated tumor (r = -0.631, P = 0.0050). No significant correlation was demonstrated in patients with squamous cell carcinoma or poorly differentiated tumor.

CONCLUSIONS

The significantly inverse correlation between rADC(min) and rSUV(max) in primary cervical tumor suggests that DWI and FDG PET/CT might play a complementary role for the clinical assessment of this cancer type.

[18F]EF3 is not superior to [18F]FMISO for PET-based hypoxia evaluation as measured in a rat rhabdomyosarcoma tumour model

PURPOSE

The aim of this investigation was to quantitatively compare the novel positron emission tomography (PET) hypoxia marker 2-(2-nitroimidazol-1-yl)-N-(3[(18)F],3,3-trifluoropropyl)acetamide ([(18)F]EF3) with the reference hypoxia tracer [(18)F]fluoromisonidazole ([(18)F]FMISO).

METHODS

[(18)F]EF3 or [(18)F]FMISO was injected every 2 days into two separate groups of rats bearing syngeneic rhabdomyosarcoma tumours. In vivo PET analysis was done by drawing regions of interest on the images of selected tissues. The resulting activity data were quantified by the percentage of injected radioactivity per gram tissue (%ID/g) and tumour to blood (T/B) ratio. The spatial distribution of radioactivity was defined by autoradiography on frozen tumour sections.

RESULTS

The blood clearance of [(18)F]EF3 was faster than that of [(18)F]FMISO. The clearance of both tracers was slower in tumour tissue compared with other tissues. This results in increasing T/B ratios as a function of time post tracer injection (p.i.). The maximal [(18)F]EF3 tumour uptake, compared to the maximum [(18)F]FMISO uptake, was significantly lower at 2 h p.i. but reached similar levels at 4 h p.i. The tumour uptake for both tracers was independent of the tumour volume for all investigated time points. Both tracers showed heterogeneous intra-tumoural distribution.

CONCLUSIONS

[(18)F]EF3 tumour uptake reached similar levels at 4 h p.i. compared with tumour retention observed after injection of [(18)F]FMISO at 2 h p.i. Although [(18)F]EF3 is a promising non-invasive tracer, it is not superior over [(18)F]FMISO for the visualisation of tumour hypoxia. No significant differences between [(18)F]EF3 and [(18)F]FMISO were observed with regard to the intra-tumoural distribution and the extra-tumoural tissue retention.

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

BACKGROUND

Although studies comparing conventional imaging modalities with (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) for the detection of lymphoma and although the relations between (18)F-FDG-PET and histologic types were reported previously, most studies were not systematic and involved relatively small numbers of patients.

METHODS

Two hundred fifty-five patients with lymphoma had their disease staged using (18)F-FDG-PET, and 191 of those patients also were assessed using gallium-67 scintigraphy ((67)Ga). Disease sites were identified on a site-by-site basis using computed tomography scans and/or magnetic resonance imaging. The results of these conventional imaging modalities were compared with the results from (8)F-FDG-PET and (67)Ga, and correlations between the imaging results and pathologic diagnoses were evaluated by using the World Health Organization classification system.

RESULTS

Of 913 disease sites in 255 patients, (18)F-FDG-PET identified >97% of disease sites of Hodgkin lymphoma (HL) and aggressive and highly aggressive non-Hodgkin lymphoma. For indolent lymphoma, the detection rate of (18)F-FDG-PET was 91% for follicular lymphoma (FL); 82% for extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue, irrespective of plasmacytic differentiation; and approximately 50% for small lymphocytic lymphoma (SLL) and splenic marginal zone lymphoma (SMZL). The results from (67)Ga were similar to those from (18)F-FDG-PET for most histologic subtypes. However, the sensitivity of (67)Ga was unexpectedly poor for FL, for mantle cell lymphoma (MCL), and for the nasal type of natural killer/T-cell lymphoma (NK/T-nasal), ranging from 30% to 38%.

CONCLUSIONS

(18)F-FDG-PET was useful for all histologic subtypes of lymphoma other than SLL and SMZL. Compared with (67)Ga, the authors strongly recommend the use of (18)F-FDG-PET in patients with FL, MCL, and NK-nasal.