Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for the staging of low-grade non-Hodgkin's lymphoma (NHL)

Whole-body diffusion-weighted MRI and (18)F-FDG PET/CT can discriminate between different lymphoma subtypes

AIM

To determine whether combined 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) positron-emission tomography (PET)/computed tomography (CT) and diffusion-weighted imaging (DWI) can be used for characterisation of different lymphoma subtypes, i.e., indolent versus aggressive lymphoma, and also to assess the prognostic value of different quantitative parameters of whole-body (WB) DWI and (18)F-FDG PET/CT.

MATERIALS AND METHODS

Pre-therapeutic WB magnetic resonance imaging (MRI) including DWI and (18)F-FDG PET/CT were performed in lymphoma patients. Different quantitative DWI and (18)F-FDG PET/CT parameters were evaluated for characterisation of different lymphoma subtypes. These parameters were also correlated, both separately and in combination, against overall survival (OS) and progression-free survival (PFS). A lesion-by-lesion analysis was performed for correlation analysis between maximum standardised uptake value (SUVmax), mean standardised uptake value (SUVmean) and mean apparent diffusion coefficient (ADC).

RESULTS

Fifty patients were included in the study and divided into three groups: Hodgkin's lymphoma (HL), n=12; aggressive non-Hodgkin's lymphoma (NHL), n=29 (including 20 patients with diffuse large B-cell lymphoma, DLBCL); and indolent NHL, n=9. Indolent NHL showed significantly lower mean ADC values than the other two lymphoma groups (p=0.013). Aggressive NHL had a higher SUVmax than HL. The OS analysis of all patients showed a relationship (p=0.006) between increased mean ADC and longer OS. A model with both SUVmean and mean ADC, strengthened the possibility to predict PFS; however, a separate analysis of the DLBCL patients showed that none of the quantitative parameters could predict OS or PFS.

CONCLUSION

ADC can discriminate between indolent and aggressive NHL. This finding can be useful in assessing possible transformation from indolent to aggressive NHL. ADC, ADC/SUV, and SUV cannot predict OS/PFS independent of lymphoma subtype.

Diffuse Large B-Cell Lymphoma Infiltrating Limb Bones With a Few Lymphadenopathy Revealed on Whole-Body 18F-FDG PET/CT

A 74-year-old man presented to our hospital for a 2-month history of worsening feet and left hand swelling pain. Computed tomography reconstruction image and sagittal images of the left foot demonstrated multiple and irregular bone destruction. Orthopedic surgeon suspected tuberculosis or primary skeletal malignancy. ¹⁸F-FDG PET/CT revealed bone destruction and abnormal activity mainly in bones of both upper and lower extremities and a few lymphadenopathy at the region of left axilla and groin. Diagnosis of diffuse large B-cell lymphoma was eventually made. Subsequently, the patient was transferred to the department of oncology and responded well to antilymphoma therapy.

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

CONTEXT AND OBJECTIVE

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

DESIGN AND SETTING

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

METHODS

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

RESULTS

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

CONCLUSION

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

The use of FDG-PET in diffuse large B cell lymphoma (DLBCL): predicting outcome following first line therapy

Positron emission tomography (PET) using 18fluoro-2-deoxyglucose (FDG) has become a standard clinical tool for staging and response assessment in aggressive lymphomas. The use of PET scans in clinical trials is still under exploration, however. In this review, we examine current data regarding PET in DLBCL, and its potential applicability to development of a surrogate endpoint to expedite clinical trial conduct. Interim PET scanning in DLBCL shows mixed results, with qualitative assessment variably associated with outcome. Addition of quantitative assessment might improve predictive power of interim scans. Data from multiple retrospective studies support that PET-defined response at end of treatment correlates with outcome in DLBCL. Optimal technical criteria for standardization of acquisition and criteria for interpretation of scans require further study. Prospective studies to define the correlation of PET-defined response and time-dependent outcomes such as progression free survival (PFS) and overall survival (OS), critical for development of PET as a surrogate endpoint for clinical trials, are ongoing. In conclusion, evolving data regarding utility of PET in predictcing outcome of patients with DLBCL show promise to support the use of PET as a surrogate endpoint in clinical trials of DLBCL in the future.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Use of positron emission tomography-computed tomography in the management of patients with chronic lymphocytic leukemia/small lymphocytic lymphoma

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) cells typically have low 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG) avidity, and patients with CLL have an increased risk of developing FDG-avid aggressive lymphomas, second malignancies and infections. We hypothesized that FDG positron emission tomography-computed tomography (PET-CT) of the trunk is a sensitive method of detecting these complications in patients with CLL. Of the of 2299 patients with CLL seen in the Division of Hematology at Mayo Clinic Rochester between 1 January 2006 and 31 December 2011, 272 (11.8%) had 526 PET-CT scans and 472 (89.7%) of these were reported as abnormal. Among the 293 (55.7%) PET-CT scans used for routine evaluation of CLL, the PET component was of clinical value in only one instance. In contrast, in 83 (30.5%) patients, PET-CT scans used to evaluate new clinical complications localized high FDG-avidity lesions for biopsies. This resulted in clinically relevant new diagnoses in 32 patients, including those with more aggressive lymphoma (n = 16), non-hematological malignancies (n = 8) and opportunistic infections (n = 3). Twenty-seven patients had high FDG-avidity CLL, which was associated with prominent lymph node proliferation centers, an increased frequency of poor prognostic factors (17p13 deletion, unmutated immunoglobulin heavy chain variable gene [IGHV], expression of ZAP-70 and CD38) and a shorter overall survival. We conclude that FDG PET scans should not be used for routine surveillance of patients with CLL. However PET-CT scans are sensitive, but not specific, for detection of aggressive lymphomas, other cancers and systemic infections in patients with CLL.

Current role of FDG PET/CT in lymphoma

The management approach in Hodgkin's (HL) and high-grade non-Hodgkin's lymphomas (NHL) has shifted towards reducing the toxicity and long-term adverse effects associated with treatment while maintaining favorable outcomes in low-risk patients. The success of an individualized treatment strategy depends largely on accurate diagnostic tests both at staging and during therapy. In this regard, positron emission tomography (PET) using fluorodeoxyglucose (FDG) with computed tomography (CT) has proved effective as a metabolic imaging tool with compelling evidence supporting its superiority over conventional modalities, particularly in staging and early evaluation of response. Eventually, this modality was integrated into the routine staging and restaging algorithm of lymphomas. This review will summarize the data on the proven and potential utility of PET/CT imaging for staging, response assessment, and restaging, describing current limitations of this imaging modality.

Clinical impact of PET/MR imaging in patients with cancer undergoing same-day PET/CT: initial experience in 134 patients--a hypothesis-generating exploratory study

PURPOSE

To compare the clinical impact of combined positron emission tomography (PET) and magnetic resonance (MR) imaging to that of combined PET and computed tomography (CT) performed on the same day in patients with cancer.

MATERIALS AND METHODS

This HIPAA-compliant retrospective study was approved by the institutional review board. Patients gave written informed consent for study enrollment, including the possibility to use their imaging and clinical data in future evaluations. A total of 134 patients with cancer with a non-central nervous system primary neoplasm underwent same-day fluorodeoxyglucose (FDG) PET/CT and FDG PET/MR imaging. PET/CT and PET/MR studies were independently interpreted by teams of radiologists and nuclear medicine physicians. Four readers, divided into two teams composed of one radiologist and one nuclear medicine physician each, read all 134 studies. The referring physician classified discordance between PET/CT and PET/MR observations either as findings affecting clinical management or as findings not affecting clinical management. Data were compared with the χ(2) test.

RESULTS

Findings affecting clinical management were noted for PET/CT studies but not for PET/MR studies in two (1.5%) of 134 patients and for PET/MR studies but not for PET/CT studies in 24 (17.9%) of 134 patients. The discrepancies between findings affecting clinical management detected with PET/MR imaging over those detected with PET/CT were significant (P < .001).

CONCLUSION

In these patients, PET/MR imaging alone contributed to clinical management more often than did PET/CT alone. PET/MR imaging provides information that affects the care of patients with cancer and is unavailable from PET/CT. Online supplemental material is available for this article.

State-of-the-Art Research on "Lymphomas: Role of Molecular Imaging for Staging, Prognostic Evaluation, and Treatment Response"

Lymphomas are heterogeneous but potentially curable group of neoplasms. Treatment of lymphomas has rapidly evolved overtime with significant improvement in the cure rate and reductions in treatment-related toxicities. Despite excellent results, treatment programs are continued to be developed to achieve better curative and safety profiles. In these patients individualized therapy schemes can be devised based on a well-defined risk categorization. The therapy efficacy can be increased early during therapy in non-responding patients with escalated therapy protocols or with the addition of radiation therapy, particularly, in advanced-stage or unfavorable risk patients. The increasing availability of positron emission tomography using 18F-fluorodeoxyglucose, particularly fused with computed tomography (FDG-PET/CT) has lead to the integration of this modality into the routine staging and restaging for lymphoma with convincing evidence that it is a more accurate imaging modality compared with conventional imaging techniques. FDG-PET/CT is also is a promising surrogate for tumor chemosensitivity early during therapy. This review will summarize published data on the utility of FDG-PET/CT imaging in the staging, restaging, and predicting therapy response in patients with lymphoma.

2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography examination in patients with chronic lymphocytic leukemia may reveal Richter transformation

The significance of positron emission tomography/computed tomography (PET/CT) in chronic lymphocytic leukemia (CLL) has not yet been systematically studied. This prospective study was aimed at assessing the benefit of PET/CT in patients with newly diagnosed or relapsed CLL and Richter transformation (RT). PET/CT examination was performed in 23 patients with newly diagnosed disease, 13 with relapsed disease and eight with suspected or histopathologically confirmed RT. In all patients, the maximum standardized uptake value (SUV(max)) was calculated. The median SUV(max) was 3.4 (range: 1.5-6.3) and 3.1 (range: 1.2-5.9) in newly diagnosed and relapsed patients, respectively. The median SUV(max) of patients with suspected or confirmed RT reached 16.5 (range: 7.2-25.3), a value different from that of the previous groups (p < 0.001). 2-[18F]fluoro- 2-deoxy-D-glucose ((18)F-FDG) PET/CT revealed inflammatory lesions in seven patients (16%) and synchronous tumors in two newly diagnosed patients. (18)F-FDG PET/CT may be a beneficial imaging method when used in individuals with CLL and suspected RT.

SIE, SIES, GITMO revised guidelines for the management of follicular lymphoma

By using the GRADE system, we updated the guidelines for management of follicular cell lymphoma issued in 2006 from SIE, SIES, and GITMO group. We confirmed our recommendation to frontline chemoimmunotherapy in patients with Stage III-IV disease and/or high tumor burden. Maintenance rituximab was also recommended in responding patients. In patients relapsing after an interval longer than 12 months from frontline therapy, we recommended chemoimmunotherapy with non cross-resistant regimens followed by rituximab maintenance. High dose chemotherapy followed by hematopoietic stem cell transplant was recommended for young fit patients who achieve a response after salvage chemoimmunotherapy.

The role of FDG-PET scanning in assessing lymphoma in 2012

Positron emission tomography (PET) has a proven role in the assessment diffuse large B-cell lymphoma (DLBCL) and Hodgkin's lymphoma (HL). The clinical impact of PET carried out at the end of the patient's course of treatment is undeniable and recommendations must be followed in the interpretation of these examinations. PET is highly recommended as part of the initial investigations of these diseases because it can be used as a reference for the interpretation at treatment completion and allows disease spread to be assessed with greater sensitivity and specificity than when computed tomography (CT) is used. It seems to be certain that PET is useful for interim examinations too, in terms of assessing prognosis in DLBCL and HL, although its impact in terms of early changes to treatment is still to be determined. The criteria for interpreting the results of these early assessments are still evolving and the annual meetings in Menton, France, of groups of experts are leading towards a uniform interpretation method. In other types of lymphoma, PET can be useful for confirming local disease staging, especially in follicular lymphoma, and for guiding biopsy in patients with low-grade lymphoma that is suspicious for transformation into more aggressive disease. Several studies are in agreement that PET is valuable for assessing prognosis at treatment completion in FL and mantle cell lymphoma, but prospective studies are needed for this new indication to be validated.

Impact of [18F]Fluorodeoxyglucose Positron Emission Tomography Response Evaluation in Patients With High–Tumor Burden Follicular Lymphoma Treated With Immunochemotherapy: A Prospective Study From the Groupe d'Etudes des Lymphomes de l'Adulte and GOELAMS

Purpose

[18F]Fluorodeoxyglucose positron emission tomography (PET) is widely used for the staging and restaging of patients with aggressive lymphoma, but less is known about the utility of PET in patients with follicular lymphoma (FL). In a prospective study, we evaluated the prognostic value of PET performed during treatment and at the end of treatment in 121 patients with FL treated with first-line immunochemotherapy.

Patients and Methods

Patients with previously untreated high–tumor burden FL were treated with six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) plus two cycles of rituximab, without rituximab maintenance. PET was performed before treatment, after four cycles of R-CHOP (interim PET), and at the end of treatment (final PET). PET scans were centrally reviewed.

Results

The total number of patients included was 121. Median age was 57 years. After central review, interim PET (n = 111) was negative in 76% of patients, and final PET (n = 106) was negative in 78%. With a median follow-up of 23 months, 2-year progression-free survival rates were 86% for interim PET–negative versus 61% for interim PET–positive patients (P = .0046) and 87% for final PET–negative versus 51% for final PET–positive patients (P < .001), respectively. Two-year overall survival also significantly differed according to final PET results: 100% versus 88% (P = .0128).

Conclusion

PET performed either after four cycles of R-CHOP or at the end of therapy was strongly predictive of outcome in this prospective study. Therapeutic intervention based on PET results during or after inductive treatment should be evaluated.

Diagnostic role of 18F-fluorodeoxyglucose positron emission tomography for follicular lymphoma with gastrointestinal involvement

AIM

To investigate the capacity for 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) to evaluate patients with gastrointestinal lesions of follicular lymphoma.

METHODS

This retrospective case series consisted of 41 patients with follicular lymphoma and gastrointestinal involvement who underwent 18F-FDG-PET and endoscopic evaluations at ten different institutions between November 1996 and October 2011. Data for endoscopic, radiological, and biological examinations performed were retrospectively reviewed from clinical records. A semi-quantitative analysis of 18F-FDG uptake was performed for each involved area by calculating the maximum standardized uptake value (SUVmax). Based on the positivity of 18F-FDG uptake in the gastrointestinal lesions analyzed, patients were subdivided into two groups. To identify potential predictive factors for 18F-FDG positivity, these two groups were compared with respect to gender, age at diagnosis of lymphoma, histopathological grade, pattern of follicular dendritic cells, mitotic rate, clinical stage, soluble interleukin-2 receptor levels detected by 18F-FDG-PET, lactate dehydrogenase (LDH) levels, hemoglobin levels, bone marrow involvement, detectability of gastrointestinal lesions by computed tomography (CT) scanning, and follicular lymphoma international prognostic index (FLIPI) risk.

RESULTS

Involvement of follicular lymphoma in the stomach, duodenum, jejunum, ileum, cecum, colon, and rectum was identified in 1, 34, 6, 3, 2, 3, and 6 patients, respectively. No patient had esophageal involvement. In total, 19/41 (46.3%) patients exhibited true-positive 18F-FDG uptake in the lesions present in their gastrointestinal tract. In contrast, false-negative 18F-FDG uptake was detected in 24 patients (58.5%), while false-positive 18F-FDG uptake was detected in 5 patients (12.2%). In the former case, 2/19 patients had both 18F-FDG-positive lesions and 18F-FDG-negative lesions in the gastrointestinal tract. In patients with 18F-FDG avidity, the SUVmax value of the involved gastrointestinal tract ranged from 2.6 to 17.4 (median: 4.7). For the 18F-FDG-negative (n = 22) and -positive (n = 19) groups, there were no differences in the male to female ratios (10/12 vs 4/15, P = 0.186), patient age (63.6 ± 2.4 years vs 60.1 ± 2.6 years, P = 0.323), presence of histopathological grade 1 vs 2 (20/2 and 17/2, P = 1.000), follicular dendritic cell pattern (duodenal/nodal: 13/5 vs 10/3, P = 1.000), mitotic rate (low/partly high, 14/1 vs 10/3, P = 0.311), clinical stage according to the Ann Arbor system (stages IE and IIE/other, 15/7 vs 15/4, P = 0.499), clinical stage according to the Lugano system (stages I and II-1/other, 14/8 vs 14/5, P = 0.489), soluble interleukin-2 receptor levels (495 ± 78 vs 402 ± 83, P = 0.884), LDH levels (188 ± 7 vs 183 ± 8, P = 0.749), hemoglobin levels (13.5 ± 0.3 vs 12.8 ± 0.4, P = 0.197), bone marrow involvement (positive/negative, 1/8 vs 1/10, P = 1.000), detectability by CT scanning (positive/negative, 1/16 vs 4/13, P = 0.335), and FLIPI risk (low risk/other, 16/6 vs 13/6, P = 0.763), respectively in each case.

CONCLUSION

These findings indicate that it is not feasible to predict 18F-FDG-avidity. Therefore, 18F-FDG-PET scans represent a complementary modality for the detection of gastrointestinal involvements in follicular lymphoma patients, and surveillance of the entire gastrointestinal tract by endoscopic examinations is required.

SUV on dual-phase FDG PET/CT correlates with the Ki-67 proliferation index in patients with newly diagnosed non-Hodgkin lymphoma

PURPOSE

PET using 18F-FDG integrated with CT is beneficial for staging patients with non-Hodgkin lymphoma (NHL). The Ki-67 index is used to assess the proliferation potential of tumor cells. The aim of this study was to evaluate the correlation of the Ki-67 index in tissue samples with the SUV at different sites on dual-phase FDG PET/CT of patients with newly diagnosed NHL.

MATERIALS AND METHODS

From September 2009 to March 2011, patients with newly diagnosed NHL who had received dual-phase FDG PET/CT for staging and biopsy samples that were evaluated for the Ki-67 expression were enrolled. The SUVmax of the biopsy site, the tumorous lesion sites, and 3 different bone marrow sites (right iliac crest, sternum, and L1) were measured. The SUVmean of the liver and spleen were also measured.

RESULTS

There were a total of 27 patients in this study. Significant correlations were observed between the Ki-67 index and the SUVmax of the right iliac crest in patients with early-stage disease (stage I and II) patients, the SUVmax of the biopsy and whole-body lesion sites in patients with late-stage disease (stage III and IV), and the retention index of SUVmax of the right iliac crest in patients whose bone marrow were involved by lymphoma cells.

CONCLUSIONS

For patients with newly diagnosed NHL, the significant correlation between the Ki-67 index and the SUV in this study suggests that dual-phase FDG PET/CT may be used as a noninvasive measurement of tumor proliferation.

The accuracy of positron emission tomography in the detection of posttransplant lymphoproliferative disorder

We investigated sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 18F-fluorodeoxyglucose-positron emission tomography in 170 cases with suspected or biopsy-proven posttransplant lymphoproliferative disorder. All solid organ and hematopoietic stem cell transplant recipients who underwent an 18F-fluorodeoxyglucose-positron emission tomography scan between 2003 and 2010 in our center for the indication posttransplant lymphoproliferative disorder, were retrospectively reviewed and results were compared with tissue biopsy whenever possible. One hundred and seventy positron emission tomography scans in 150 patients were eligible for evaluation. In 45 cases, the patient had a biopsy-confirmed posttransplant lymphoproliferative disorder before positron emission tomography scanning and positron emission tomography was performed for staging purposes. In the remaining 125 cases, positron emission tomography was performed to differentiate between posttransplant lymphoproliferative disorder and other diseases. 18F-fluorodeoxyglucose-uptake was quantitatively expressed by calculation of maximum and mean standardized uptake value in the most intense lesion or, in the absence of attenuation corrected positron emission tomography scans, by comparing uptake in target lesion to liver and mediastinal uptake. We found an overall sensitivity of 89%, specificity of 89%, positive predictive value of 91% and negative predictive value of 87% for posttransplant lymphoproliferative disorder detection by 18F-fluorodeoxyglucose-positron emission tomography. In a subanalysis of the 125 scans performed for differentiating posttransplant lymphoproliferative disorder from other diseases, sensitivity, specificity, positive predictive value and negative predictive value were 90%, 89%, 85% and 93%, respectively. 18F-fluorodeoxyglucose-uptake in posttransplant lymphoproliferative disorder was generally high with a median mean and maximum standardized uptake value of 9.0 (range 2.0-18.6) and 17.4 (range 2.6-26.4). Posttransplant lymphoproliferative disorder often had an atypical presentation on positron emission tomography with high incidence of extranodal involvement. In conclusion, from these data, we can conclude that 18F-fluorodeoxyglucose-positron emission tomography is highly sensitive for detecting posttransplant lymphoproliferative disorder and has an excellent ability to differentiate posttransplant lymphoproliferative disorder from non-malignant diseases.

FDG-PET in Follicular Lymphoma Management

18-Fluoro-deoxyglucose positron emission tomography/computerised tomography (FDG PET/CT) is commonly used in the management of patients with lymphomas and is recommended for both initial staging and response assessment after treatment in patients with diffuse large B-cell lymphoma and Hodgkin lymphoma. Despite the FDG avidity of follicular lymphoma (FL), FDG PET/CT is not yet applied in standard clinical practice for patients with FL. However, FDG PET/CT is more accurate than conventional imaging for initial staging, often prompting significant management change, and allows noninvasive characterization to guide assessment of high-grade transformation. For restaging, FDG PET/CT assists in distinguishing between scar tissue and viable tumors in residual masses and a positive PET after induction treatment would seem to predict a shorter progression-free survival.

Primary follicular lymphoma of the duodenum with erosions as atypical macroscopic features

A 52-year-old Japanese woman who was eventually diagnosed with primary follicular lymphoma of the duodenum showed atypical endoscopic features, namely, erosions with peripheral whitish edematous mucosa. Initial biopsy specimens taken from the erosions revealed insufficient numbers of lymphoma cells for histological diagnosis. Subsequent biopsy specimens from the peripheral mucosa containing the whitish enlarged villi showed infiltration of the lymphoma cells forming lymphoid follicles, which led us to the appropriate diagnosis. This case indicates that endoscopists should take biopsy samples from the peripheral mucosa with whitish enlarged villi rather than erosions in the rare instances that erosions appear as the main macroscopic feature of intestinal follicular lymphoma.

Diagnostic value of software-based image fusion of computed tomography and F18-FDG PET scans in patients with malignant lymphoma

AIM

The purpose of this study was to evaluate the accuracy of 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) positron emission tomography (PET), computed tomography (CT), and software-based image fusion of both modalities in the imaging of non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD).

METHODS

77 patients with NHL (n = 58) or HD (n = 19) underwent a FDG PET scan, a contrast-enhanced CT, and a subsequent digital image fusion during initial staging or followup. 109 examinations of each modality were evaluated and compared to each other. Conventional staging procedures, other imaging techniques, laboratory screening, and follow-up data constituted the reference standard for comparison with image fusion. Sensitivity and specificity were calculated for CT and PET separately.

RESULTS

Sensitivity and specificity for detecting malignant lymphoma were 90% and 76% for CT and 94% and 91% for PET, respectively. A lymph node region-based analysis (comprising 14 defined anatomical regions) revealed a sensitivity of 81% and a specificity of 97% for CT and 96% and 99% for FDG PET, respectively. Only three of 109 image fusion findings needed further evaluation (false positive).

CONCLUSION

Digital fusion of PET and CT improves the accuracy of staging, restaging, and therapy monitoring in patients with malignant lymphoma and may reduce the need for invasive diagnostic procedures.

Comparison between endoscopic macroscopic classification and F-18 FDG PET findings in gastric mucosa-associated lymphoid tissue lymphoma patients

PURPOSE

The aim of this study was to compare endoscopic macroscopic classification with fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake in gastric mucosa-associated lymphoid tissue (MALT) lymphoma and to investigate the usefulness of F-18 FDG positron emission tomography (PET) for diagnosing gastric MALT lymphoma.

MATERIALS AND METHODS

Sixteen patients with gastric MALT lymphoma who underwent F-18 FDG PET and gastrointestinal imaging modalities were included in this study. Sixteen healthy asymptomatic participants undergoing both F-18 FDG PET and endoscopy for cancer screening were in the control group. We investigated the difference of F-18 FDG uptake between the gastric MALT lymphoma and the control group and compared the uptake pattern in gastric MALT lymphoma with our macroscopic classification.

RESULTS

The endoscopic findings of 16 gastric MALT lymphoma patients were classified macroscopically as chronic gastritis-like tumors (n = 6), depressed tumors (n = 5), and protruding tumors (n = 5). Abnormal gastric F-18 FDG uptake was observed in 63% of tumors in the gastric MALT lymphoma group and 50% of cases in the control group. The median maximum standardized uptake values for gastric MALT lymphoma patients and control group were 4.0 and 2.6, respectively, the difference of which was statistically significant (P = 0.003). F-18 FDG uptake results were positive for all protruding tumors but only 50% for chronic gastritis-like tumors and 40% for depressed-type tumors.

CONCLUSIONS

F-18 FDG PET may be a useful method for evaluating protrusion-type gastric MALT lymphoma. When strong focal or diffuse F-18 FDG uptake is detected in the stomach, endoscopic biopsy should be performed, even if the endoscopic finding is chronic gastritis.

FDG PET/CT predictive role in follicular lymphoma

PURPOSE

We present findings concerning (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) at end-treatment evaluation in follicular lymphoma (FL) in order to establish possible predictive factors for progression-free survival (PFS) and patient outcome.

METHODS

We retrospectively analysed data from 91 consecutive FL patients (M:F = 51:40, mean age 61) referred to our PET Unit at therapy completion: 38 with an indolent form (grade 1-2) and 53 with an aggressive FL (grade 3a and b) according to the World Health Organization (WHO) classification. A total of 148 FDG PET/CT scans were analysed and findings reported as positive or negative for disease. The overall response to treatment was assessed according to the revised International Workshop Criteria (IWC). The final outcome was defined as remission or disease by taking clinical, instrumental and histological data as standards of reference, with a mean follow-up period of 3 years (range 1-8). A statistical analysis was performed with respect to PFS and patient outcome for FDG PET result, tumour grading, Follicular Lymphoma International Prognostic Index (FLIPI), disease stage and number of relapses, on uni- and multivariate analyses, with p < 0.05 considered as significant.

RESULTS

Overall patients presented a mean PFS of 35 months (range 3-86), with a relapse rate of 42%. At final outcome, remission was achieved in 67 of 91 patients (74%). Of the different predictive factors, only FDG PET result significantly correlated with patient outcome (p = 0.0002). PET/CT performance at the end of treatment was as follows: 100% sensitivity, 99% specificity, 89% positive predictive value and 100% negative predictive value. The Kaplan-Meier analysis demonstrated a statistically significant correlation with PFS for FDG PET (p < 0.0001), FLIPI score (0-1 versus ≥ 2) (p = 0.0451) and number of relapses (none versus ≥ 1) (p = 0.0058). These findings were confirmed at the univariate analysis, whereas at the multivariate analysis only FDG PET (p = 0.0006892) and number of relapses (p = 0.01947) were independent predictive factors for PFS.

CONCLUSION

End-treatment PET/CT in FL has high accuracy and appears to be a good predictor of PFS and patient outcome, irrespective of grading. As expected, patients facing more than one relapse seem to have significantly shorter PFS in the presence of a positive FDG PET.

PET in T-Cell Lymphoma

Most non-Hodgkin lymphomas (NHL) are of B-cell origin; only about 10% are T-cell or NK-cell lymphomas. The clinical features of T/NK-cell lymphomas differ from those of B-cell lymphomas: advanced stage and extranodal disease are more common and the prognosis is worse. Several studies have confirmed that 2-[fluorine-18]fluoro-2-deoxy-D-glucose (18FDG) uptake varies among different subtypes of lymphoma, a disparity that can be explained by the differences in histology, proliferation of tumor cells, and the ratio of viable tumor and reactive cells in the environment. These observations are based on investigation of B-cell lymphomas. Positron emission tomography (PET)/computed tomography (CT) was found to be useful both at staging and at measuring the therapeutic outcome after two to three cycles of chemotherapy (interim PET/CT). Several meta-analyses have confirmed the role of PET in evaluating the viability of the residual tumor mass after treatment. 18FDG-PET has been proved to have an excellent negative predictive value. Conversely, only a few studies have investigated the role of FDG-PET in T/NK-cell lymphomas. This paper summarizes the current information regarding the potential use of PET/CT in patients with T-cell lymphoma.

Clinical features of 66 lymphoma patients presenting with a fever of unknown origin

OBJECTIVE

To investigate the clinical characteristics, diagnostic approaches, short-term efficacy of treatment and prognosis of lymphoma patients presenting with a fever of unknown origin (FUO).

METHODS

We reviewed the records of 132 patients finally diagnosed with lymphoma in Huashan Hospital, half of whom initially presented with a FUO. The other 66 lymphoma patients without a history of FUO were diagnosed within a month when several patients in the FUO group were also diagnosed.

RESULTS

The patients presenting with a FUO were predominantly young men (71.21%, p=0.35) characterized by a temperature ≥ 39°C (55/66, 83.33%). Compared with the non-FUO group, patients in the FUO group more often had pancytopenia and hypohepatia, 61.54% with hypoalbuminemia (p<0.0001), 15.50% with significantly elevated lactate dehydrogenase (LDH) (p<0.0001), 92.45% with elevated serum β(2) microglobulin (p=0.017), 93.48% with elevated urine β(2) microglobulin (p=0.002) and 30.77% with elevated alkaline phosphatase (p=0.001). Ninety-four percent of the FUO patients had aggressive lymphomas (p=0.012), with a poor performance status (96.97%, p=0.003), stage III/IV disease (96.97%, p<0.0001), night sweats (21.21%, p=0.026), unexplained weight loss (46.97%, p=0.002) and more than one extranodal site involved (65.15%, p=0.002). The patients in the FUO group also showed poor prognoses, and most of them were in the high-intermediate or high risk classification of the disease (96.61%, p<0.0001), with a low complete remission (CR) rate (61.11% vs. 93.75%, p=0.043). Twenty-one (15.91%) of all the patients were diagnosed based on the finding of lesion sites by Positron Emission Tomography/Computed Tomography (PET/CT) scanning, which had not been detected by conventional scans.

CONCLUSION

Lymphoma presenting as FUO has a rapid progression and poor prognosis, and is difficult to diagnose. PET/CT scans can provide complementary information for an etiological diagnosis of a FUO and biopsy examinations are significant to establish an early diagnosis for patients presenting with a FUO.

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

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

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

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

F-18 FDG PET for evaluation of bone marrow involvement in non-Hodgkin lymphoma: a meta-analysis

BACKGROUND

In recent years, the use of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has become widespread for the staging of lymphoma. In non-Hodgkin lymphoma (NHL), the bone marrow (BM) involvement is a sign of extensive disease, and the iliac crest BM biopsy (BMB) is the established method for the detection of BM infiltration. However, iliac crest BMB is associated with a high rate of false-negative results. We assess the ability of FDG PET or PET/CT scan to ascertain the presence of BM involvement in aggressive and indolent NHL.

METHODS

The authors conducted a systematic MEDLINE search of articles published (last update, May 2010). Two reviewers independently assessed the methodological quality of each study. A meta-analysis of the reported sensitivity and specificity of each study was performed.

RESULTS

Eight studies met the inclusion criteria. The studies had several design deficiencies. Pooled sensitivity and specificity for the detection of non-Hodgkin aggressive lymphoma were 0.74 (95% CI, 0.65-0.83) and 0.84 (95% CI, 0.80-0.89), respectively. Pooled sensitivity and specificity for the detection of non-Hodgkin indolent lymphoma were 0.46 (95% CI, 0.33-0.59) and 0.93 (95% CI, 0.88-0.98), respectively.

CONCLUSIONS

The diagnostic accuracy of FDG PET or PET/CT scans was slightly higher but without significant statistical difference (P = 0.1507) in patients with non-Hodgkin aggressive lymphoma as compared with those with non-Hodgkin indolent lymphoma. The sensitivity to detect indolent lymphoma BM infiltration was low for FDG PET or PET/CT.

Causes and imaging features of false positives and false negatives on F-PET/CT in oncologic imaging

BACKGROUND: 18F-FDG is a glucose analogue that is taken up by a wide range of malignancies. 18F-FDG PET-CT is now firmly established as an accurate method for the staging and restaging of various cancers. However, 18F-FDG also accumulates in normal tissue and other non-malignant conditions, and some malignancies do not take up F18-FDG or have a low affinity for the tracer, leading to false-positive and false-negative interpretations. METHODS: PET-CT allows for the correlation of two separate imaging modalities, combining both morphological and metabolic information. We should use the CT to help interpret the PET findings. In this article we will highlight specific false-negative and false-positive findings that one should be aware of when interpreting oncology scans. RESULTS: We aim to highlight post-treatment conditions that are encountered routinely on restaging scans that can lead to false-positive interpretations. We will emphasise the importance of using the CT component to help recognise these entities to allow improved diagnostic accuracy. CONCLUSION: In light of the increased use of PET-CT, it is important that nuclear medicine physicians and radiologists be aware of these conditions and correlate the PET and CT components to avoid misdiagnosis, over staging of disease and unnecessary biopsies.

Positron Emission Tomography–Computed Tomography (PET-CT) After Induction Therapy Is Highly Predictive of Patient Outcome in Follicular Lymphoma: Analysis of PET-CT in a Subset of PRIMA Trial Participants

Purpose

The utility of [18F]fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET-CT) in assessing response at the end of induction therapy is well documented in Hodgkin's and diffuse large B-cell lymphomas, but its role in follicular lymphoma (FL) remains undetermined. We investigated the prognostic significance of PET-CT performed after first-line therapy in patients with FL treated in the prospective Primary Rituximab and Maintenance (PRIMA) study.

Patients and Methods

Results of PET-CT scans performed after induction immunochemotherapy were recorded retrospectively. Patients went on to either observation or rituximab maintenance per protocol independent of the PET-CT result. Patient characteristics and outcomes were then evaluated.

Results

Of 122 PET-CT scans performed at the end of the induction immunochemotherapy, 32 (26%) were reported as positive by the local investigator. Initial demographic or disease characteristics did not differ between PET-CT–positive (PET-positive) and PET-CT–negative (PET-negative) patients. PET status correlated with conventional response criteria (P < .001). Patients remaining PET positive had a significantly (P < .001) inferior progression-free survival at 42 months of 32.9% (95% CI, 17.2% to 49.5%) compared with 70.7% (95% CI, 59.3% to 79.4%) in those who became PET negative. PET status, but not conventional response (complete response or complete response unconfirmed v partial response) according to IWC 1999, was an independent predictive factor for lymphoma progression. The risk of death was also increased in PET-positive patients (hazard ratio 7.0; P = .0011).

Conclusion

[18F]FDG PET-CT status at the end of immunochemotherapy induction in patients with FL is strongly predictive of outcome and should be considered a meaningful clinical end point in future studies.

The role of 18F-FDG PET/CT imaging in Waldenstrom macroglobulinemia

Disease assessment in WM is dependent on the quantification of the IgM monoclonal protein and percent involvement of the bone marrow. There is a need for imaging studies that objectively measure tumor load in these patients. In this study, we sought to examine the role of combined FDG-PET/CT imaging in the detection of tumor load and in the assessment of response to therapy. Thirty-five patients were enrolled on a prospective study using bortezomib and rituximab therapy and were included in this study because they completed a pre- and post-treatment FDG-PET/CT imaging at one facility (12 newly diagnosed and 23 relapsed/refractory). The use of combined FDG-PET/CT imaging showed positive findings in 83% of patients with WM, unlike prior studies using conventional imaging that indicate that only 20% of patients have lymphadenopathy or hepatosplenomegaly. Moreover, 43% of patients had abnormal bone marrow uptake on FDG-PET imaging that can potentially help in the assessment of their tumor load, especially with heterogenous sampling of the bone marrow. There was no statistical correlation between EORTC response criteria for FDG-PET/CT and response by monoclonal protein. This is the first study to examine the role of FDG-PET/CT imaging in WM. Future studies should examine the role of FDG-PET/CT in conjunction with monoclonal protein response in the assessment of progression-free survival in patients with WM.

Role of limited whole-body PET/CT in pediatric lymphoma

OBJECTIVE

Performing true whole-body FDG PET/CT is standard practice in pediatric lymphoma staging and follow-up. In adults, imaging is typically limited whole-body PET/CT, which has advantages over true whole-body PET/CT, primarily decreased scanning time and decreased radiation. We hypothesize that in pediatric lymphoma, limited whole-body PET/CT is sufficient for routine follow-up when disease on the true whole-body staging study is confined to the limited whole-body field of view (FOV).

MATERIALS AND METHODS

True whole-body PET/CT studies performed for staging and follow-up of pediatric lymphoma patients between November 2004 and July 2009 at two tertiary pediatric referral hospitals were retrospectively reviewed. Abnormalities on the limited whole-body and additional true whole-body FOV were documented.

RESULTS

One hundred seventy patients met the inclusion criteria (752 examinations). At staging, disease involved the limited whole-body FOV without involving the additional true whole-body FOV in 150. Of the 150, 145 had routine follow-up (508 examinations). In these patients, no new (18)F-FDG-avid disease was identified outside of the limited whole-body FOV on routine follow-up (positive predictive value, 0%, 95% CI, 0-0.02).

CONCLUSION

The limited whole-body PET/CT for routine follow-up when disease is confined to the limited whole-body FOV at staging is appropriate. Given its definite advantages over true whole-body PET/CT, it is preferred.

Outcomes of patients with non-Hodgkin's lymphoma treated with Bexxar with or without external-beam radiotherapy

PURPOSE

To compare the efficacy and toxicity of external-beam radiotherapy (EBRT) to sites of bulky lymphadenopathy in patients with chemotherapy-refractory low-grade non-Hodgkin's lymphoma (NHL) immediately before receiving Bexxar (tositumomab and (131)I) vs. in patients receiving Bexxar alone for nonbulky disease.

METHODS AND MATERIALS

Nineteen patients with chemotherapy-refractory NHL were treated with Bexxar at our institution (University of Florida, Gainesville, FL) from 2005 to 2008. Seventeen patients had Grade 1-2 follicular lymphoma. Ten patients received a median of 20 Gy in 10 fractions to the areas of clinical involvement, immediately followed by Bexxar (EBRT + Bexxar); 9 patients received Bexxar alone. The median tumor sizes before EBRT + Bexxar and Bexxar alone were 4.8 cm and 3.3 cm, respectively. All 5 patients with a tumor diameter >5 cm were treated with EBRT + Bexxar. A univariate analysis of prognostic factors for progression-free survival (PFS) was performed.

RESULTS

The median follow-up was 2.3 years for all patients and 3.1 years for 12 patients alive at last follow-up. Of all patients, 79% had a partial or complete response; 4 of the 8 responders in the EBRT + Bexxar group achieved a durable response of over 2 years, including 3 of the 5 with tumors >5 cm. Three of 9 patients treated with Bexxar alone achieved a durable response over 2 years. Actuarial estimates of 3-year overall survival and PFS for EBRT + Bexxar and Bexxar alone were 69% and 38% and 62% and 33%, respectively. The median time to recurrence after EBRT + Bexxar and Bexxar alone was 9 months. Having fewer than 4 involved lymph-node regions was associated with superior PFS at 3 years (63% vs. 18%). There was no Grade 4 or 5 complications.

CONCLUSIONS

Adding EBRT immediately before Bexxar produced PFS equivalent to that with Bexxar alone, despite bulkier disease. Hematologic toxicity was not worsened. EBRT combined with Bexxar adds a safe and effective therapeutic treatment for managing recurrent low-grade follicular NHL.

Role of Functional Imaging in the Management of Lymphoma

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

Imaging in follicular NHL

Imaging contributes to management of follicular lymphoma (FL) through guiding biopsy, determining disease stage and assessing therapeutic response. Molecular imaging with positron emission tomography (PET), especially when combined with computer tomography (PET/CT), is more accurate than conventional imaging and extends the role of imaging to lesion characterisation, including non-invasive assessment of high-grade transformation. There is strong data to support the use of FDG PET/CT for primary staging, resulting in significant management change. In patients with early stage follicular lymphoma (stage I or II), there is a clear role for PET/CT to avoid futile involved-field radiotherapy in patients with widespread disease and to optimise the treatment field in patients with confirmed localised disease. For restaging, use of PET/CT allows discrimination between scar tissue and viable tumour in residual masses. Molecular imaging is likely to play an increasing role in selection of patients for specific treatments and in prognostic stratification.

Whole-body diffusion-weighted imaging compared with FDG-PET/CT in staging of lymphoma patients

BACKGROUND

Diffusion-weighted imaging (DWI) has become increasingly valuable in lymph node imaging, yet the clinical utility of this technique in the staging of lymphoma has not been established.

PURPOSE

To compare whole-body DWI with FDG-PET/CT in the staging of lymphoma patients.

MATERIAL AND METHODS

Thirty-one patients, eight with Hodgkin lymphoma (HL) and 23 with non-Hodgkin's lymphoma (18 aggressive and five indolent) underwent both whole-body DWI, whole-body MRI (T1W and T2W-STIR) and FDG-PET/CT. Lesions on whole-body DWI were only considered positive if they correlated with lesions on T1W and T2W-STIR images. The staging given by each technique was compared, according to the Ann Arbor staging system. Differences in staging were solved using biopsy results, and clinical and CT follow-ups as standard of reference.

RESULTS

The staging was the same for DWI and FDG-PET/CT in 28 (90.3%) patients and different in three (9.7%). Of the 28 patients with the same staging, 11 had stage IV in both techniques and 17 had stages 0-III. No HL or aggressive non-Hodgkin's lymphoma patients had different staging. Three indolent small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) lymphoma had higher staging with DWI when compared with FDG-PET/CT. One small subcutaneous breast lymphoma was not seen but all other extranodal sites were detected by both techniques.

CONCLUSION

Whole-body DWI is a promising technique for staging of both (aggressive and indolent) non-Hodgkin's lymphoma and HL.

PET-CT Imaging of Lymphoma

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