2-[18F]fluoro-2-deoxyglucose positron-emission tomography in staging, response evaluation, and treatment planning of lymphomas

Multimodality radionuclide imaging in fever of unknown origin presenting with a solitary spleen lesion

Background

Fever of unknown origin (FUO) still represents a serious challenge for clinicians, since it can be related to a wide spectrum of disorders, ranging from infections to malignancies. In this scenario, nuclear medicine can be of value to achieve a correct diagnosis both through positron emission computed tomography (PET/CT) and 99mTc labeled hexamethylpropylene amine oxime (HMPAO) white blood cell (WBC) scintigraphy.

Case presentation

We are presenting the case of 65-year-old male, who was referred to our hospital due to prolonged unexplained fever. He was submitted to abdomen ultrasonography (US) that did not disclose relevant pathological findings. Subsequently, he underwent PET/CT scan with 18F-fluorodeoxyglucose (18F-FDG) that revealed an area of increased tracer uptake in splenic inferior pole. In order to solve differential diagnosis between tumor and infection, he was submitted to 99mTc-HMPAO WBC scintigraphy that resulted negative for sites of pathologic radiolabeled cells’ accumulation but revealed a photopenic area in the splenic inferior pole. The pattern of mismatched uptake between 18F-FDG PET/CT and 99mTc-HMPAO WBC scintigraphy was considered highly suspicious for spleen tumor localization. The patient was scheduled for splenectomy and histology resulted positive for non-Hodgkin lymphoma (NHL) of diffuse large B cell type. After splenectomy, a further 18F-FDG PET/CT revealed the appearance of hypermetabolic hepatic lesions. The patient underwent chemotherapy with complete remission.

Conclusion

Nuclear medicine provides valuable tools for differential diagnosis in FUO. In case of patients presenting solitary lesion of the spleen, the combined use of 18F-FDG PET/CT and 99mTc-HMPAO WBC scintigraphy can provide relevant information to aid clinicians to a correct diagnosis.

Clinical Analysis of 50 Cases of Primary Pulmonary Lymphoma: A Retrospective Study and Literature Review

Objective: This study aimed at to raise the awareness understanding of primary pulmonary lymphoma (PPL) by analyzing the clinical manifestation, imaging, pathology, diagnosis, treatment, and prognostic features of 50 cases of PPL. Methods: The study of 50 individuals with PPL diagnosed at the First affiliated hospital of Nanchang university between January 2009 and December 2019 was performed. Results: Overall, 27 males and 23 females were enrolled, with an average age of 57.6 ± 15.6 years. The primary symptoms included, cough (n = 37), expectoration (n = 25), sputum with blood (n = 12), and chest pain (n = 12). Two individuals had Hodgkin's lymphoma and 48 patients had non-Hodgkin's lymphoma (NHL). We divided the NHL cases into mucosa-associated lymphoid tissue lymphoma (MALT) (n = 21), diffuse large B-cell lymphoma (n = 12), small lymphocytic lymphoma (n = 2), mantle B-cell lymphoma (n = 2), follicular lymphoma (n = 1), B-cell lymphoma without further classification (n = 8), and T-cell lymphoma (n = 2). The imaging findings revealed that unilateral lung involvement was more common among the patients. The longest follow-up duration up to December 2019 was 123 months with 40 surviving patients. The 5-year overall survival and progression-free survival were 46.7% and 44.4%, respectively. Age was an independent predictive factor for the 5-year survival (hazard ratio, 8.900; P = .038), (P < .05). Conclusion: PPL is a uncommon disease with atypical clinical manifestations and is often misdiagnosed. Immunohistochemistry is currently the standard used in pathologic evaluation of PPL. MALT prognosis is better in contrast with other kinds of PPL. Surgery or radiotherapy can be considered in patients with limited lesions, and chemotherapy is the first treatment option for diffuse lesions. Age of ≥ 60 years was reported as an independent adverse predictive factor.

18F-FDG PET/CT performed immediately after percutaneous ablation to evaluate outcomes of the procedure: preliminary results

Objective

To determine whether ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography performed immediately after percutaneous ablation (_iPA¹⁸F-FDG PET/CT) is useful in evaluating the outcomes of the procedure.

Materials and Methods

This was a retrospective study of 20 patients (13 males, 7 females; mean age, 65.8 ± 12.1 years) submitted to percutaneous ablation of metastases. All of the lesions treated had shown focal uptake on a ¹⁸F-FDG PET/CT scan obtained at baseline. The primary tumors were mainly colorectal cancer (in 45%) or lung cancer (in 40%). _iPA¹⁸F-FDG PET/CT was performed to identify any residual viable tumor cells. The treatment was considered a success (no viable tumor cells present) if no uptake of ¹⁸F-FDG was noted on the _iPA¹⁸F-FDG PET/CT scan.

Results

Twenty-six lesions were submitted to percutaneous ablation with either cryoablation (n = 7) or radiofrequency ablation (n = 19). The mean lesion diameter was 2.52 ± 1.49 cm. For the detection of viable tumor cells, _iPA¹⁸F-FDG PET/CT had a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 66.7%, 95%, 88.5%, 80%, and 90.5%, respectively. There was a significant correlation between the _iPA¹⁸F-FDG PET/CT findings and the results of the follow-up studies (kappa = 0.66; p < 0.01).

Conclusion

_iPA¹⁸F-FDG PET/CT studies appear to constitute a useful means of evaluating the outcomes of percutaneous ablation. By detecting residual viable tumor cells, this strategy might allow early re-intervention, thus reducing morbidity. Studies involving larger numbers of patients are needed in order to confirm our findings.

Outcome of patients with early-stage follicular lymphoma staged with 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) and treated with radiotherapy alone

PURPOSE/OBJECTIVE(S)

To evaluate the impact of positron emission tomography (PET) staging on overall survival (OS) and progression-free survival (PFS) in patients with early-stage (stages I and II) follicular lymphoma (ESFL) treated with radiation therapy alone.

MATERIALS/METHODS

Eighty-five patients with ESFL treated with curative-intent radiation therapy (RT) between December 2000 and May 2011 were identified. Of those, 13 who had no PET staging and 25 who received additional systemic therapy were excluded from the analysis. Thus, we analyzed 47 patients with PET-staged ESFL treated with definitive radiation therapy alone (dose > 23Gy). Tumour features, pre-treatment computed tomography (CT) and PET stage, dose fractionation, and radiation therapy field extent were recorded. The Kaplan-Meier method was used to estimate the OS and PFS. Patterns of failure were assessed as cumulative incidences assuming competing risks.

RESULTS

Median age was 57 years (range 24-83); 43% were females. Most were PET stage 1 (76.6%). Median maximum nodal diameter was 3 cm. Median pre-treatment lactate dehydrogenase (LDH) was 327.5 (range 123-607, upper normal limit = 220). Twenty-six patients (55.3%) had infra-diaphragmatic disease. All received 30-36Gy in 15-24 fractions, with 59.6% treated with involved-field radiation therapy (IFRT) techniques. There was no significant difference in PFS between CT stage I and stage II (HR 1.30 95% CI [0.25-6.72], p = 0.75) with a 5-year PFS of 77% and 78% respectively. However, stage I on PET staging had a significantly better PFS than stage II (HR 4.66 95% CI [1.15-18.8], p = 0.038), with 5-year PFS of 84% and 60% respectively. Ten patients had recurrent disease, with distant disease being the first site of failure in seven patients. Seven-year OS was 91% (95% CI 79-100) for the whole cohort.

CONCLUSION

FDG-PET should be considered an essential element in the evaluation of patients with ESFL being considered for RT.

Pulmonary mucosa-associated lymphoid tissue lymphoma: 18F-FDG PET/CT and CT findings in 28 patients

OBJECTIVE

The aim of the study was to evaluate the CT and fluorine-18-fluorodeoxyglucose positron emission tomography/CT (¹⁸F-FDG PET/CT) imaging findings of lung mucosa associated lymphoid tissue (MALT) lymphoma.

METHODS

28 patients with histologically confirmed pulmonary MALT lymphoma who underwent a chest CT and ¹⁸F-FDG PET/CT for staging were retrospectively analysed. The CT images were evaluated to determine morphological pattern of appearance, laterality, localization, number, size, presence of thoracic lymphadenopaties and secondary/combined findings. PET images were analysed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio and lesion-to-blood pool SUVmax ratio. The relationship between qualitative and semi-quantitative features at ¹⁸F-FDG PET/CT and CT findings were also analysed.

RESULTS

A total of 57 pulmonary lesions were identified by CT: 37 areas of consolidation, 4 masses, 12 nodules and 4 ground-glass opacities. Solitary and multiple lesions were detected in 10 and 18 patients, respectively; among patients with multiple lesions, 16 were bilateral and 2 unilateral. ¹⁸F-FDG PET/CT revealed increased ¹⁸F-FDG uptake in 47/57 lesions, in 26/28 patients. 18F-FDG avidity was significantly associated only with tumour size.

CONCLUSIONS

Pulmonary MALT lymphoma is ¹⁸F-FDG avid in most cases and ¹⁸F-FDG avidity is correlated with tumour size. Consolidation is the most frequent morphological pattern of disease presentation. Advances in knowledge: This study demonstrated that lung MALT lymphoma are ¹⁸F-FDG avid in most cases depending on tumour size. Single or multiple areas of consolidation are the most common pattern of presentation of lung MALT lymphoma at CT.

18F-FDG PET/CT in gastric MALT lymphoma: a bicentric experience

PURPOSE

The role of 18F-FDG-PET/CT in evaluating gastric MALT lymphoma is still controversial. In the literature the detection rate of 18F-FDG-PET/CT in patients with gastric MALT lymphoma is variable, and the reason for this heterogeneity is not still clear. Our aim was to investigate the particular metabolic behavior of these lymphoma.

MATERIALS AND METHODS

Sixty-nine patients (26 female, 43 male) with histologically confirmed gastric MALT lymphoma who underwent a 18F-FDG-PET/CT for initial staging from two centers were included. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio and compared with Ann Arbor stage, epidemiological (age, sex), histological (presence of gastritis, ulcer, H. pylori infection, plasmacytic differentiation, Ki-67 index), and morphological (tumor size, superficial lesions or mass-forming) characteristics.

RESULTS

Thirty-six patients (52 %) had positive PET/CT (average SUVmax was 9±6.7; lesion-to-liver SUVmax ratio 3.7±2.6, lesion-to-blood pool SUVmax ratio 4.8±3.3) at the corresponding gastric lesion; the remaining 33 were not 18F-FDG-avid. In the univariate analysis, 18F-FDG avidity was significantly associated with morphological features (mass forming p<0.001 and high maximum diameter p<0.001), Ann Arbor stage (p=0.010), and Ki67 index (p<0.001) and not correlated with age, sex, presence of gastritis, ulcer, Helicobacter pylori infection, and plasmacytic differentiation. In the multivariate analysis, the correlations with gross morphological appearance, Ann Arbor stage, and Ki-67 score were confirmed. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio correlated significantly only with Ki67 index (p=0.047; p=0.012; p=0.042).

CONCLUSIONS

18F-FDG avidity was noted in 52 % of gastric MALT lymphoma and this avidity is correlated with gross morphological characteristics, tumor stage, and Ki-67 index. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio are correlated only with Ki-67 index, and only lesion-to-liver SUVmax ratio was independently associated with Ki-67 score.

Imaging of Tumor Metabolism Using Positron Emission Tomography (PET)

Molecular imaging employing PET/CT enables in vivo visualization, characterization, and measurement of biologic processes in tumors at a molecular and cellular level. Using specific metabolic tracers, information about the integrated function of multiple transporters and enzymes involved in tumor metabolic pathways can be depicted, and the tracers can be directly applied as biomarkers of tumor biology. In this review, we discuss the role of F-18-fluorodeoxyglucose (FDG) as an in vivo glycolytic marker which reflects alterations of glucose metabolism in cancer cells. This functional molecular imaging technique offers a complementary approach to anatomic imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) and has found widespread application as a diagnostic modality in oncology to monitor tumor biology, optimize the therapeutic management, and guide patient care. Moreover, emerging methods for PET imaging of further biologic processes relevant to cancer are reviewed, with a focus on tumor hypoxia and aberrant tumor perfusion. Hypoxic tumors are associated with poor disease control and increased resistance to cytotoxic and radiation treatment. In vivo imaging of hypoxia, perfusion, and mismatch of metabolism and perfusion has the potential to identify specific features of tumor microenvironment associated with poor treatment outcome and, thus, contribute to personalized treatment approaches.

Extensive Extranodal Involvement of Rare Sites in Non Hodgkin's Lymphoma Detected on (18)F- FDG PET-CT: A Case Report

We present a case of a 23 year-old male treated for Hodgkin's lymphoma who developed diffuse large B-cell lymphoma (DLBCL) 8 years after achieving remission. (18)F-fluorodeoxyglucose positron emission tomography computed tomography ((18)F-FDG PET-CT) was done, which revealed extensive extranodal involvement of bilateral atria, bilateral kidneys, ileo-caecal junction and left testis along with mesenteric and retroperitoneal lymph nodal involvement. Renal and cardiac lesions were not detected by contrast-enhanced CT. Simultaneous lymphomatous involvement of rare sites such as heart, kidneys and testis in a single patient has not been reported before.

Positron emission tomographic scans in lymphoma: convention and controversy

The use of sensitive and specific imaging techniques for accurate initial staging and evaluation of response to therapy in patients with lymphoma is essential for their optimal management. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) integrated with computed tomography (CT) has emerged as a powerful imaging tool and is being routinely used in staging, response evaluation, and posttreatment surveillance in patients with non-Hodgkin lymphoma and Hodgkin lymphoma. PET/CT is currently widely used in clinical practice, but the established clinical benefit is currently restricted to the posttreatment evaluation of Hodgkin lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma. Although used in other histologic subtypes and in other clinical situations including response assessment, its impact on patient outcome remains to be demonstrated. We performed a literature search of PubMed from 1999 to 2011 using the following keywords: PET scan, FDG-PET, PET/CT, lymphoma. This review addresses the challenges and controversies in the use of PET/CT scans in the management of patients with lymphoma.

My treatment approach to patients with diffuse large B-cell lymphoma

My favored treatment approach for patients with diffuse large B-cell lymphoma continues to evolve. Diffuse large B-cell lymphoma can now be cured in more than 50% of patients. This is a result of improved definitions of the disease, improved diagnostic capabilities, better staging and restaging techniques, a useful prognostic index to guide therapeutic decisions, and the development of increasingly effective therapies. Positron emission tomographic scans have improved the accuracy of both staging and restaging. Findings on a positron emission tomographic scan at the end of therapy are the best predictors of a good treatment outcome. Numerous subtypes of diffuse large B-cell lymphoma have been identified that require specific treatment approaches. For example, plasmablastic lymphoma typically lacks CD20 and does not benefit from treatment with rituximab. Diffuse large B-cell lymphoma originating in specific extranodal sites such as the central nervous system, testes, and skin presents special problems and requires specific treatment approaches. A subgroup of diffuse large B-cell lymphoma with a very high proliferative rate seems to have a poor outcome when treated with CHOP-R and does better with regimens used for patients with Burkitt lymphoma. New insights into the biology of these disorders are likely to further change treatment approaches. Recognition that diffuse large B-cell lymphoma is not one disease, but a variety of clinicopathologic syndromes provides the opportunity to further improve our ability to benefit patients.

Hodgkin's lymphoma therapy: past, present, and future

IMPORTANCE OF THE FIELD

The treatment of Hodgkin's lymphoma (HL) with the use of radiotherapy and systemic chemotherapy has been one of the success stories of modern oncology. HL therapy has been the paradigm for the systematic evaluation of different curative modalities, resulting in cure for the majority of patients. The current focus is on designing initial therapeutic strategies that retain efficacy and minimize long-term toxicity. Appropriate use of pathologic, clinical, biologic and radiologic prognostic factors in identification of aggressive HL is paramount in designing a successful therapeutic strategy.

AREAS COVERED IN THIS REVIEW

This review addresses the current and future use of prognostic tools, including PET scanning and other biomarkers, in identifying patients with aggressive HL, with reference to publications from the last two decades. The current standard approaches with the use of combined modality therapy and systemic chemotherapy as well as the promising role of future response-adapted strategies is reviewed.

WHAT THE READER WILL GAIN

The reader will obtain a comprehensive review of risk assessment strategies as well as current and investigational therapeutic approaches in the management of HL.

TAKE HOME MESSAGE

In HL, appropriate utilization of risk assessment strategies is required to maximize therapeutic outcomes while minimizing toxicity, especially long-term toxicity. Response-adapted therapy utilizing PET has the potential to profoundly improve the therapeutic landscape in HL.

Interim FDG-PET Scan in Hodgkin's Lymphoma: Hopes and Caveats

FDG-PET has recently emerged as an important tool for the management of Hodgkins lymphoma. Although its use for initial staging and response evaluation at the end of treatment is well established, the place of interim PET for response assessment and subsequent treatment tailoring is still quite controversial. The use of interim PET after a few cycles of chemotherapy may allow treatment reduction for good responders, leading to lesser treatment toxicities as well as early treatment adaptation for bad responders with a potential higher chance for cure. Interpretation of interim PET is a rapidly moving field. Actually, visual interpretation is preferred over quantitative interpretation in this situation. The notion of minimal residual uptake emerged for faint persisting FDG uptake, but has evolved during the recent years. Guidelines using mediastinum and liver as references have been proposed at the expert meeting in Deauville 2009. Actually, several trials are ongoing both for localised and advanced disease to evaluate the FDG-PET potential for early treatment monitoring and tailoring. Until the results of these prospective randomized trials become available, treatment changes according to the interim PET results should remain inappropriate and limited to well-conducted clinical trials.

Does the addition of involved field radiotherapy to high-dose chemotherapy and stem cell transplantation improve outcomes for patients with relapsed/refractory Hodgkin lymphoma?

PURPOSE

To evaluate the value of adding involved field radiotherapy (IFRT) to patients with relapsed/refractory Hodgkin lymphoma (HL) undergoing high-dose chemotherapy (HDCT) and stem cell transplantation (SCT).

METHODS AND MATERIALS

Ninety-two patients with relapsed/refractory HL undergoing HDCT and SCT from 1995 to 2008 were analyzed in a case-control design. Forty-six HL patients treated with IFRT within 2 months of SCT were matched to 46 HL patients who did not receive IFRT based on age, stage at relapse, timing of relapse, histology, and year of SCT. All were evaluated for response, survival, and toxicity with a median followup of 63.5 months.

RESULTS

There was a trend for better disease control in patients receiving IFRT. Specifically, 10/46 IFRT patients (22%) relapsed/progressed after SCT compared with 17/46 control patients (37%). Of the failures after IFRT, 70% were inside the radiation field, all in sites of bulky disease. In patients with nonbulky disease, IFRT also resulted in significantly improved outcomes (failure rate 6% vs. 33%, respectively). When stratified by disease bulk, the use of IFRT was found to significantly improve DFS (p=0.032), but did not affect OS. In addition, IFRT and nonbulky disease were found to be positive prognostic indicators for DFS with hazard ratios of 0.357 (p=0.032) and 0.383 (p=0.034), respectively. Grade IV/V toxicities were significantly higher in the IFRT vs. non-IFRT group (28% vs. 2%; p<0.001), observed only in patients receiving a busulfan-based conditioning regimen.

CONCLUSION

Patients with refractory or relapsed HL undergoing HDCT and SCT have a high risk of relapse in sites of prior disease involvement, especially in sites of bulky disease. The use of IFRT is associated with a lower risk of disease progression in these sites; however bulky disease sites are still difficult to control. Toxicity risk is significant, particularly when busulfan-based conditioning is combined with IFRT, and alternative chemotherapy conditioning regimens should be considered.

Impact of 18F-fluoro-2-deoxyglucose positron emission tomography on treatment strategy and radiotherapy planning for stage I-II Hodgkin disease: a prospective multicenter study

PURPOSE

To quantify the impact of preradiotherapy 18F-fluoro-2-deoxyglucose positron-emission tomography (FDG-PET) on treatment strategy and radiotherapy planning for patients with Stage I/II Hodgkin disease included in a large prospective multicenter study.

PATIENTS AND METHODS

Conventional computed tomography and FDG-PET were performed just before the planned radiotherapy. The radiotherapy plan was first elaborated under blinded conditions for FDG-PET data. Then, the medical staff was asked to confirm or not confirm the treatment strategy and, if appropriate, to modify the radiotherapy plan based on additional information from FDG-PET.

RESULTS

Between January 2004 and January 2006, 137 patients were included (124 were available for analysis) in 11 centers (108 adults, 16 children). All but 1 patient had received chemotherapy before inclusion. Prechemotherapy work-up included FDG-PET for 61 patients, and data were available for elaboration of the first radiotherapy plan. Based on preradiotherapy FDG-PET data, the radiotherapy was cancelled in 6 patients (4.8%), and treatment plan modifications occurred in 16 patients (12.9%): total dose (11 patients), CTV volume (5 patients), number of beam incidences (6 patients), and number of CTV (6 patients). The concordance between the treatment strategies with or without preradiotherapy FDG-PET was 82.3%. Concordance results were not significantly different when prechemotherapy PET-CT information was available.

CONCLUSION

Preradiotherapy FDG-PET for treatment planning in Hodgkin lymphoma may lead to significant modification of the treatment strategy and the radiotherapy planning in patients with Stage I or II Hodgkin disease, even in those who have undergone FDG-PET as part of the prechemotherapy work-up.

Non-Hodgkin's lymphoma presenting as a primary bladder tumor: a case report

Introduction

Primary lymphoma of the bladder represents 0.2% of all bladder malignancies. Secondary involvement of the bladder by malignant lymphoma occurs in 10% to 50% of cases. Most lymphomas of the bladder are non-Hodgkin's lymphomas of the B-cell type, with preponderance among women. The impact of positron emission tomography (PET) on tumor staging has recently become very important due to its use in the study of diagnosis extension and individual therapy design.

Case presentation

We report the case of a 79-year-old Caucasian man with intermittent haematuria as the presenting symptom of non-Hodgkin's lymphoma of the bladder. He was first diagnosed with primary lymphoma of the bladder using the current staging method, but a positron emission tomography study subsequently revealed that he instead had a secondary involvement of the bladder.

Conclusion

The staging of non-Hodgkin's lymphomas, which is useful in order to plan accurate therapy, has been changing since the introduction of positron emission tomography scanning. Primary lymphomas of the bladder, although very rare, may be even more uncommon when this imaging technique is used to assess the extension of the disease. Although the interpretation of this technique has some limitations that should be taken into account, the extensive use of positron emission tomography should nonetheless help improve the diagnosis of this disease.

PET imaging in lymphoma

PET has become a cornerstone procedure in modern lymphoma management. This paper reviews, from a clinical point of view, the evidence for using PET in the different subtypes of lymphoma and the different steps of their management. The reader is given an overview of the current PET-based interventional lymphoma trials and an insight into possible future developments in the field, including new PET tracers.

18F-FDG-PET in patients with malignant lymphoma having long-term follow-up: staging and restaging, and evaluation of treatment response and recurrence

OBJECTIVE

The aim of this study was to evaluate the diagnostic accuracy of positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) for staging/restaging, evaluating the treatment response, and screening of recurrence in patients with malignant lymphoma (ML) during long-term follow-up, and to compare that with computer tomography (CT)/magnetic resonance imaging (MRI).

METHODS

The study was conducted in 59 ML patients who underwent whole-body 18F-FDG-PET examinations three times or more from October 1998 to August 2006. The location of the lesions in the patients with positive findings on 18F-FDG-PET and/or the corresponding CT/MRI was classified into supradiaphragmatic (n = 10), infradiaphragmatic (n = 7), and extranodal sites (n = 20), and the findings were compared on a site basis according to the gold standard, which consisted of all clinical information available, including follow-up results.

RESULTS

A total of 156 18F-FDG-PET examinations for which the corresponding CT/MRI images were also available were evaluated, and a total of 305 sites showed positive findings on 18F-FDG-PET and/or CT/MRI. Concordant positive findings were obtained in 76% for staging/restaging, 34% for evaluation of the treatment response, and 50% for screening of recurrence. The accuracy of 18F-FDG-PET versus CT/MRI was 92% versus 84% (P = 0.06) for staging/restaging, 84% versus 50% (P < 0.05) for the evaluation of the treatment response, and 83% versus 72% (P = 0.21) for the screening of recurrence. At pathologic sites with discrepant findings between 18F-FDG-PET and CT/MRI (n = 122), the frequency of accurate diagnosis by 18F-FDG-PET (76%) was higher than that by CT/MRI (24%), especially for the evaluation of the treatment response.

CONCLUSIONS

18F-FDG-PET is expected to play a significant role in the management of ML patients even after effective treatment is initiated.