18F-FDG PET in malignant lymphoma: significance of positive findings

Foreign Body Granuloma Masquerading as Remnant Lymphoma on 18F-FDG PET/CT

ABSTRACT

A 54-year-old man complained of a growing nodule in the left upper arm, which was diagnosed as diffuse large B-cell lymphoma by postsurgical pathology. For baseline assessment, FDG PET/CT revealed intense uptake in the left upper arm, in addition to FDG-avid pleura lesions and regional, axillary, cervical, and mediastinal lymph nodes. After chemotherapy, the restaging scan showed complete remission of most involved lesions except for increased activity in the prior surgical site. The patient eventually underwent surgical resection again, and the diagnosis was confirmed as foreign body granuloma.

Incidental Acute Appendicitis on Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F-FDG PET/CT) Imaging: Radiology From a Different Perspective

Although Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F-FDG PET/CT) is routinely used in oncological imaging, the F-18 fluorodeoxyglucose (18F-FDG) avidity is not tumor-specific. Numerous benign infective and inflammatory processes may also show increased radiotracer activity. Similarly, abnormal 18F-FDG uptake in an inflamed appendix can pose a diagnostic challenge for the interpreter of oncologic 18F-FDG PET/CT. We present the case of an 18-year-old female with classic Hodgkin's lymphoma who had 18F-FDG PET/CT while undergoing chemoradiotherapy. The scan demonstrated a complete metabolic response to treatment. However, there was increased 18F-FDG uptake in the right iliac region, projecting over the appendix, which, if interpreted as a lymphomatous involvement, would have upscaled the treatment response to progressive disease. The patient was called for additional workup, which included an ultrasound abdomen.

The scan revealed classic features of acute appendicitis. However, there was no appendicolith or luminal obstruction. Upon additional questioning, the patient mentioned mild intermittent abdominal pain and anorexia eased by pain relievers for the preceding few days. On deep palpation of her abdomen, there was rebound tenderness in the right iliac region. According to the Alvarado score, it was graded 7 points suggesting probable/likely appendicitis. After collective evaluation of the clinical, laboratory, and imaging findings, the appendicular 18F-FDG uptake was deemed secondary to uncomplicated acute appendicitis rather than a lymphomatous lesion. Our patient refused surgery as she did not have severe abdominal pain. She was hemodynamically stable without signs of luminal obstruction. She was non-operatively managed with broad-spectrum antibiotics for six days. The results of the follow-up complete blood counts and ultrasound examination were negative. Our patient was symptom-free and recovering normally at a two-week follow-up appointment.

We present a follow-up case of classic Hodgkin's lymphoma with incidental uptake in the appendix, which resembled submucosal lymphomatous cell infiltration of the appendix. Careful scrutiny, clinical correlation, physical examination, blood tests, and additional imaging offered helpful insight and led to the correct, benign diagnosis of the 18F-FDG avid appendix.

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

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

Cat-Scratch Disease: A Pitfall for Lymphoma Evaluation by FDG-PET/CT

FDG-PET/CT is a standard of care in staging and response assessment of Hodgkin lymphoma. Hence, it is important to recognize pitfalls owing to the potential therapeutic impact. We report a case of a 29-year-old woman affected by stage III bulky Hodgkin lymphoma. The interim FDG-PET/CT showed a complete metabolic response. After three new cycles of chemotherapy, the patient showed fever and lymphadenopathy at clinic examination, PET/CT revealed several FDG uptakes at lymph nodes in inguinal and iliac region. Pathologic analyses, after biopsy and serologic examinations, led to the diagnosis of cat-scratch disease.

Clinical significance of post-treatment 18F-fluorodeoxyglucose uptake in cervical lymph nodes in patients with diffuse large B-cell lymphoma

OBJECTIVES

We assessed the clinical significance of FDG uptake in cervical lymph nodes after treatment of patients with DLBCL.

METHODS

In total, 87 patients with DLBCL were enrolled. All patients had newly appeared FDG uptake in cervical lymph nodes on PET/CT during follow-up after cessation of therapy. Cervical lymph nodes were finally diagnosed as benign or malignant according to histopathological findings or follow-up PET. Clinical characteristics and PET findings were compared between groups and factors associated with malignant lesions were evaluated.

RESULTS

Only 8 (9.2 %) patients with cervical lymph nodes with FDG uptake ultimately had malignancy. FDG uptake lymph nodes appeared significantly earlier in the malignant group than in patients with benign FDG uptake (p = 0.013). Primary nodal lymphoma was more frequent in patients with cancer spread than in those with benign FDG uptake in lymph nodes (p < 0.001).

CONCLUSION

Most cervical lymph nodes with FDG uptake (about 91 %) appearing after treatment of malignant DLBCL were ultimately benign. The elapsed time between the end of therapy and the appearance of cervical lymph nodes with FDG uptake and the primary sites of lymphomas are helpful clues in determining which cases are malignant.

KEY POINTS

• About 91 % appearing after treatment of DLBCL were benign. • Elapsed time between therapy and FDG uptake was associated with malignancy. • Primary sites of lymphoma are helpful clues to determine malignancy.

Nonossifying fibroma: A possible pitfall in F18-FD-PET/CT imaging of Hodgkin's disease

A 14-year-old girl was examined for a right lateral neck swelling and radiographic mediastinal widening. Biopsy of a right supraclavicular lymph node demonstrated the nodular sclerosing form of Hodgkin's lymphoma. An 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (F18-FDG-PET/CT) study showed several pathological areas of lymph-node uptake in the upper mediastum and right distal tibia. Radiography of the tibia revealed a nonossifying fibroma in the site corresponding to the distal tibial uptake. The PET appearance of benign fibro-osseous lesions may be similar to those of skeletal metastases. Information obtained by the CT component of the PET/CT study and by conventional radiography can be useful in preventing erroneous interpretations of F18-FDG-PET uptake.

Precursor T-cell lymphoblastic lymphoma extensively involving the mediastinum, pleura and pericardium: A case report

Precursor T-cell lymphoblastic lymphoma (T-LBL) is a rare type of malignant lymphoma, with clinical manifestations including diaphragmatic lymph node enlargement, accompanied by local oppression and/or systemic lymphoma symptoms. However, extensive involvement of the mediastinum, pleura and pericardium is rare in T-LBL cases. This is the case report of a T-LBL extensively involving the mediastinum, pleura and pericardium in a 54-year-old woman. The patient complained of anhelation, chest tightness and tiredness for ~3 months. A computed tomography (CT) scan of the chest revealed a diffuse mass of soft tissue density involving the mediastinum, pleura and pericardium. Several thoracocenteses indicated inflammatory changes and cytological examination of the pleural fluid and pleural biopsy under CT guidance identified no heterotypic cells. As ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging revealed a diffused moderate FDG uptake (maximum standard uptake value of 4) by the mediastinum, pleura and cardiac sac, we diagnosed a malignant lymphoma. We subsequently successfully performed needle biopsy under PET/CT guidance according to the PET/CT images and the diagnosis of T-LBL was pathologically confirmed.

Dual-time-point F-18 FDG PET/CT imaging for differentiating the lymph nodes between malignant lymphoma and benign lesions

Purpose

The purpose of the present study is to evaluate the clinical value of dual-time-point F-18 FDG PET/CT imaging to differentiate malignant lymphoma (ML) from benign lymph node (BLN).

Materials and methods

The subjects were 310 lymph nodes in 84 patients (195 ML lesions in 30 patients and 115 BLN in 54 patients associated with various etiologies.). F-18 FDG PET/CT scan was performed at 50 min (early scan) and at 100 min (delayed scan) after the injection. First, the maximum standardized uptake value (SUVmax) of each lesion at early and delayed scans was calculated. Second, we estimated the difference between early and delayed SUVmax (D-SUVmax) and the retention index (RI-SUVmax) to evaluate the change of tracers in the lesions. Furthermore, proper cut-off values of them were evaluated using receiver operating characteristic analysis. The efficacy of each parameter was analyzed with ANOVA.

Results

Delayed SUVmax and D-SUVmax in ML were significantly higher than those in BLN. Proper cut-off value in delayed SUVmax was 4.0 and in D-SUVmax was 1.0. When the proper cut-off value in D-SUVmax was applied, the D-SUVmax yielded the role of diagnosis with sensitivity of 82.6 %, specificity of 65.2 %, positive predictive value of 80.1 % and negative predictive value of 68.8 %, respectively.

Conclusions

The delayed SUVmax and D-SUVmax were useful indices to differentiate ML from BLN, regardless of histologic subtype. Dual-time-point F-18 FDG PET/CT imaging may help to consider whether there is any need to proceed to more invasive tests, such as biopsy, in individual patients.

Role of [18F]-FDG-PET/MDCT in evaluating early response in patients with Hodgkin's lymphoma

PURPOSE

The authors evaluated the prognostic role of 18-fluoro-fluorodeoxyglucose positron emission tomography/multidetector computed tomography ([(18)F]-FDG PET/MDCT) in treating patients with Hodgkin's lymphoma (HL).

MATERIALS AND METHODS

We retrospectively evaluated 132 patients with HL studied with PET/MDCT before the start of chemotherapy (CTX) for staging purposes and again after two CTX cycles with [doxorubicin (Adriblastin), bleomycin, vinblastine, dacarbazine (ABVD_] (interim PET/MDCT), at least 30 days after the end of the last CTX cycle and/or 3 months after the end of radiotherapy, if delivered (final PET-MDCT).

RESULTS

Interim PET-MDCT was negative in 104/132 patients (79%), and their final PET-MDCT showed complete remission in 102/104 (98%) of cases, with disease recurrence/persistence in two (2%). In the remaining 28 (21%) patients, interim PET-MDCT revealed an early response in 68% of cases and chemoresistance with disease progression in 32% of cases; in these 28 patients, final PET-MDCT showed a lack of response to treatment in 43% of cases (43%) and complete remission in 57% of cases. Statistical analysis of these data showed that interim PET-MDCT had a negative predictive value of 98% and a positive predictive value of 42%, with values of sensitivity, specificity and diagnostic accuracy of 85.7%, 86.4% and 86.4%, respectively.

CONCLUSIONS

Interim PET-MDCT has a reliable prognostic role in diagnosis and treatment of patients with HL, as it helps predict which patients are more likely to achieve a complete response at the end of treatment. PET/MDCT may also lead to a change in treatment, with reduced treatment-related toxic effects and significantly reduced total costs.

Prognostication and Risk-Adapted Therapy of Hodgkin's Lymphoma Using Positron Emission Tomography

The use of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) for response assessment in lymphoma is now widespread. Prognostic information obtained from PET performed after two to three cycles of chemotherapy may guide more individualized, risk-adapted therapeutic strategies. Progress in the risk stratification of Hodgkin's lymphoma through midtreatment PET is reviewed, with a focus on management implications in newly diagnosed and relapsed disease. How to tailor treatment on the basis of the interim PET result is not yet defined but is the subject of ongoing trials.

Current methods to diagnose the unresponsive and complicated forms of coeliac disease

Coeliac disease is a common disorder. Due to the protean manifestations of the disease and the often mild but indolent course, the diagnosis is often missed. The method to diagnose this in principle reversible disease after the introduction of a gluten-free diet has attracted the attention of several scientific disciplines to find the simplest and most patient-friendly test. This has resulted in a noticeable impact on the clinical practice next to a general increased awareness of its existence, its pathogenesis, its course and recent evidence of increased mortality. Amendments made in the diagnostic criteria of coeliac disease over the last half century have simplified the diagnosis. However, the aspect most relevant to the specialist in internal medicine is related to its grave consequences when the disease fails to respond to a gluten-free diet. These refractory cases may culminate in severe complications with sombre endings and malignancy. Fortunately, current technology can offer the specialist in internal medicine more facilities to diagnose the cause of the complicated cases in order to attempt to intervene in the course of disease and hopefully save these patients. We review the available tools that now exist and their indications that can be practiced in a modern clinical setting for the diagnosis of the complicated forms of this disease.

Postchemotherapy histiocyte-rich pseudotumor involving the spleen

We report 2 cases of splenic postchemotherapy histiocyte-rich pseudotumor. Each patient had a history of diffuse large B-cell lymphoma, treated with multiagent chemotherapy. Computed tomography scans performed on both patients showed splenic masses. A positron emission tomography scan performed on 1 patient showed increased metabolic activity. The preoperative diagnosis in both patients was recurrent lymphoma, prompting splenectomy. The splenectomy specimens showed multiple, tan-white, firm nodules, up to 3.5 cm in diameter, that were histologically composed of central necrotic B cells (CD20+/CD3-), consistent with necrotic lymphoma, surrounded by numerous lipid-laden (xanthomatous) histiocytes. Clinical staging studies at the time of splenectomy showed no other sites of disease. We conclude that these histologic and immunophenotypic findings represent chemotherapy-induced tumor necrosis with a florid histiocytic reaction mimicking residual viable lymphoma. Others have used descriptive terminology or the term xanthomatous pseudotumor for these lesions that have been only rarely reported in the spleen previously.

Early and late therapy response assessment with [18F]fluorodeoxyglucose positron emission tomography in pediatric Hodgkin's lymphoma: analysis of a prospective multicenter trial

PURPOSE

In adult Hodgkin's lymphoma (HL) risk stratification after early therapy response assessment with [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) seems to allow tailoring therapy with less toxicity for patients with adequate metabolic response. This study delivers the first prospective data on the potential of FDG-PET for response assessment in pediatric HL.

PATIENTS AND METHODS

FDG-PET was performed in 40 pediatric HL patients before polychemotherapy (PET-1), after two cycles of polychemotherapy (PET-2), and after completion of polychemotherapy (PET-3). Mean follow-up was 46 months (range, 26 to 72 months).

RESULTS

At early and late response assessment, the proportion of PET-negative patients was significantly higher compared with those patients with negative findings in conventional imaging methods (CIMs; PET-2, 26 of 40 v CIM-2, one of 40; P < .001; PET-3, 21 of 29 v CIM-3, four of 29; P < .001). Sensitivity and negative predictive value were 100% for early and late therapy response assessment by PET. Both patients suffering a relapse during follow-up were identified by PET-2/3, whereas one of these patients was not detected by CIM-3. PET was superior to CIMs with regard to specificity in early and late therapy response assessment (68% v 3%, and 78% v 11%, respectively; both P < .001). Specificity of early therapy response assessment by PET was improved to 97% by quantitative analysis of maximal standardized uptake value reduction using a cutoff value of 58%.

CONCLUSION

Pediatric HL patients with a negative PET in response assessment have an excellent prognosis while PET-positive patients have an increased risk for relapse.

Prognostic value of early 18 fluorodeoxyglucose positron emission tomography and gallium-67 scintigraphy in aggressive lymphoma: a prospective comparative study

The prognostic value of fluorodeoxyglucose positron emission tomography (FDG-PET) and gallium-67 scan (GS) performed early after chemotherapy was assessed in 40 patients with newly diagnosed aggressive lymphoma. FDG-PET and GS were performed before and after three cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) or two cycles of ACVBP (doxorubicin, cyclophosphamide, vindesine, bleomycin, prednisone), with or without rituximab. Thirty-five patients had diffuse large B-cell lymphoma (DLBCL), two had mantle-cell lymphoma and three had T-cell lymphoma. Four patients relapsed despite early negative FDG-PET and GS including all three patients with T-cell lymphoma. Nine patients stayed in remission despite positive FDG-PET and/or GS of whom five showed moderate intensity residual bone uptake. Seven of these nine early false positives had a negative exam at the end of treatment. In patients with DLBCL, the 2-year event-free survival was 85% for negative versus 30% for positive FDG-PET patients (P = 0.003) whereas it was 78% for negative versus 33% for positive GS patients (P = 0.018). Sensitivity, specificity and diagnostic accuracy of FDG-PET and GS were not significantly different: 90% versus 70%, 76 versus 80% and 80 versus 77%, respectively. We conclude that both FDG-PET and GS are valuable tools to early predict outcome in patients with DLBCL.

Role of [18F]Fluorodeoxyglucose Positron Emission Tomography Scan in the Follow-Up of Lymphoma

Purpose

In lymphoma, [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) is routinely used for initial staging, early evaluation of treatment response, and identification of disease relapse. However, there are no prospective studies investigating the value of serial FDG-PET over time in patients in complete remission.

Patients and Methods

All patients with lymphoma who achieved the first complete remission were prospectively enrolled onto the study and scheduled for serial FDG-PET scans at 6, 12, 18, and 24 months; further scans were then carried out on an annual basis. Overall, the population included 421 patients (160 patients with Hodgkin's lymphoma [HL], 183 patients with aggressive non-Hodgkin's lymphoma [NHL], and 78 patients with indolent follicular NHL). All patients had a regular follow-up evaluation, including complete clinical and laboratory evaluation, and final assessment of any suspect FDG-PET findings using other imaging procedures (computed tomography [CT] scan) and/or biopsy and/or clinical evolution. FDG-PET findings were reported as positive for relapse, inconclusive (when equivocal), or negative for relapse.

Results

PET enabled documentation of lymphoma relapse in 41 cases at 6 months, in 30 cases at 12 months, in 26 cases at 18 months, in 10 cases at 24 months, and in 11 cases at more than 36 months. All 36 patients with inconclusive positive PET underwent biopsy; only 12 (33%) of 36 patients had a concomitant suggestion of positivity on CT. A lymphoma relapse was diagnosed in 24 (66%) of 36 patients.

Conclusion

Our results confirm FDG-PET as a valid tool for follow-up of patients with HL and NHL. In patients with inconclusive positive results, histologic confirmation plays an important role in identifying true relapse.

18F-fluorodeoxyglucose positron emission tomography/computed tomography in AIDS-related Burkitt lymphoma

This study aims to describe 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) findings in patients with AIDS-related Burkitt lymphoma, at various times of treatment, and to define its utility for a better patient management. We retrospectively studied 13 consecutive HIV-positive patients with Burkitt lymphoma who underwent one or more PET/CT. In 5 of 5 patients imaged before treatment, PET/CT confirmed all involved sites detected at conventional work-up and demonstrated additional sites in 4 of 5 patients. Lymph node involvement, which is known to be uncommon in endemic or sporadic Burkitt lymphoma, was present in 54% of patients. Additionally, in 3 patients, Burkitt lymphoma was predominantly located in parotid lymph nodes, which is also an unusual finding. A negative scan was encountered in 3 of 10 patients imaged during treatment and in 1 of 4 patients imaged after treatment completion and was always associated with lasting complete remission. Presence of residual area of uptake was related to both favorable and unfavorable outcome whether performed during treatment (5/7 and 2/7, respectively) or after (1/3 and 2/3, respectively). Areas of increased uptake could be observed in lung (4 cases) or esophagus (3 cases), and were clinically related to pneumonia or esophagitis. We recommend PET/CT for accurate initial staging of patients with AIDS-related Burkitt lymphoma. PET/CT is also useful to monitor treatment response, as regression of initial disease can be early observed. Furthermore, PET/CT appears to have prognostic value, as a negative scan was always associated with a favorable outcome.

Early relapse in a patient with Hodgkin's disease and negative interim FDG-PET

The role of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the assessment of lymphoma patients is well established, and PET is routinely used for initial staging, early evaluation of treatment response, and identification of disease relapse. The early evaluation of response to therapy (interim PET) has been reported to be an accurate predictor of progression-free survival, and end-treatment PET has been suggested to be unnecessary if interim PET results are negative. We report on a patient with Hodgkin's disease with a positive PET scan at presentation and a negative interim PET (carried out after three cycles of adriamycin, bleomycin, vinblastine, and dacarbazine; ABVD). Despite uncomplicated clinical course, end-treatment PET (following six cycles) was positive, showing a very early relapse. For this reason, patient underwent further treatment; however, a complete remission was not obtained, and a poor prognosis is expected. This case testifies the possibility of early relapse of lymphoma even in the case of negative interim PET; it also supports the usefulness of end-treatment PET scan in lymphoma patients.

Excellent survival following two courses of COPAD chemotherapy in children and adolescents with resected localized B-cell non-Hodgkin's lymphoma: results of the FAB/LMB 96 international study

High cure rates are possible in children with localized mature B-cell lymphoma (B NHL) using a variety of chemotherapeutic strategies. To reduce late sequelae, the duration and intensity of chemotherapy has been progressively reduced. The Lymphome Malins de Burkitt (LMB) 89 study reported long-term survival in almost all children with localized resected disease treated with two courses of COPAD (cyclophosphamide, vincristine, prednisolone and doxorubicin). This study was designed to confirm the effectiveness of this approach in a larger number of patients in a multinational co-operative study. The patient cohort was part of an international study (French-American-British LMB 96), which included all disease stages and involved three national groups. Patients in this part of the study had resected stage I or completely resected abdominal stage II disease. Following surgery, two courses of COPAD were given, without intrathecal (IT) chemotherapy. One hundred and thirty-two children were evaluable. Two of 264 (0.9%) courses were associated with grade IV toxicity (one stomatitis and one infection). With a median follow up of 50.5 months, the 4 year event-free survival is 98.3% and overall survival is 99.2%. Children with resected localized B-NHL can be cured with minimal toxicity following two courses of low intensity treatment without IT chemotherapy.

F18 fluorodeoxyglucose uptake in progressive transformation of germinal centres

FDG-PET/CT is a widely established imaging modality for staging, restaging and monitoring therapy response in lymphoma patients. Progressive transformation of germinal centres (PTGC) is a benign condition presenting characteristically as asymptomatic lymphadenopathy. This paper presents a case of a 53-year-old man with a history of Hodgkin’s disease (HD) whose F¹⁸ FDG-PET/CT scan showed high uptake in left axillary lymph nodes (SUV 3.8). A subsequent, left axillary lymph node biopsy revealed PTGC. PTGC can present as a false positive finding on FDG-PET/CT in lymphoma patients and biopsy should be done in HD patients in clinical remission but have a positive FDG-PET/CT scan.

FDG PET in lymphoma: the need for standardization of interpretation. An observer variation study

OBJECTIVE

To measure and describe patterns of interobserver variation in visual interpretation of 18-FDG PET in malignant lymphoma.

METHODS

Eleven nuclear medicine physicians with different levels of PET experience independently reviewed 37 18F-FDG PET scans of lymphoma patients (10 obtained at presentation, 27 during or after therapy). They were requested to identify and localize suspicious lymphoma sites and to assign a stage to the baseline scans, and to interpret the remaining scans for the presence of viable lymphoma. Individual (extra-)nodal regions were assessed for the likelihood of malignancy as positive, negative or equivocal. These results were compared to expert readings after dichotomization in conservative and sensitive reading classifications.

RESULTS

Sixty-one percent and 56% (using sensitive and conservative reading, respectively) of the baseline scans were scored in accordance with the experts. Fourteen of the 27 scans obtained for therapy evaluation with viable tumour sites were scored in accordance with the experts in 82% and 94% of the patients, using conservative and sensitive reading, respectively. The 13 negative scans were scored in agreement with the experts in only 45% of the cases. False positivity pertained especially to the neck, periclavicular, axilla, mediastinum, lung and bone marrow. More experienced observers tended to have fewer false negative scores.

CONCLUSION

There are substantial disparities among nuclear medicine physicians' interpretations of FDG PET scans of lymphoma patients, which may affect patient care and results of multi-institutional clinical trials. A well-defined set of criteria is urgently needed to improve consistency.

Imaging in staging of malignant lymphoma: a systematic review

Computed tomography (CT) is currently the most commonly used means for staging malignant lymphoma. 18F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET), FDG-PET/CT fusion, and whole-body magnetic resonance imaging (WB-MRI) are potential alternatives. The purpose of this study was to systematically review published data on the diagnostic performance of CT, FDG-PET, FDG-PET/CT fusion, and WB-MRI in staging of malignant lymphoma. In addition, technical aspects, procedures, advantages, and drawbacks of each imaging modality are outlined. Three CT studies, 17 FDG-PET studies, and 4 FDG-PET/CT fusion studies were included in this systematic review. The studies were of moderate methodological quality and used different scoring systems to stage malignant lymphoma. CT remains the standard imaging modality for initial staging of malignant lymphoma, while FDG-PET has an essential role in restaging after treatment. Early results suggest that FDG-PET/CT fusion outperforms both CT alone and FDG-PET alone. Data on the diagnostic performance of WB-MRI are lacking. Future well-designed studies, expressing their results according to the Ann Arbor staging system, are needed to determine which imaging modality is most accurate and cost-effective in staging malignant lymphoma.

Normal and Abnormal Patterns of 18F-Fluorodeoxyglucose PET/CT in Lymphoma

In spite of the high performance of 18F-fluorodeoxyglucose (FDG) PET for the evaluation of lymphoma, inherent limitations of this modality underscore the additional value of PET/CT as an important tool in the assessment of this disease. Accumulating data on the use of PET/CT in lymphoma indicate the contribution of hybrid imaging to improved interpretation accuracy of PET using FDG and CT. Knowledge of the normal and abnormal patterns of FDG-PET/CT imaging and their variability in patients with lymphoma is important to provide a comprehensive clinically significant interpretation that has an impact on patient management and potentially on outcome.

The role of FDG PET in the management of lymphoma: what is the evidence base?

[18F]Fluorodeoxyglucose positron emission tomography (18F-FDG PET) is playing an increasing role in the management of both Hodgkin and non-Hodgkin lymphoma, offering potential advantages in the accuracy of disease assessment at a number of points in the management pathway. This review evaluates the current level of confidence in the use of PET technology in (1) initial staging, (2) the assessment of early response to chemotherapy, (3) the assessment of residual masses at completion of initial treatment, (4) follow-up, and (5) radiotherapy planning.

Role for positron emission tomography in skeletal diseases

Imaging plays a prominent role in the diagnosis and management of rheumatic diseases. Conventional imaging methods provide high-resolution structural information but usually fail to distinguish between active lesions and residual changes. Positron emission tomography (PET) with the tracer 18F-fluorodeoxyglucose (18F-FDG) was recently introduced into clinical practice as a means of obtaining information on both structure and metabolic activity. 18F-FDG-PET is widely used in oncology and may be valuable in patients with infections or inflammatory diseases, most notably vasculitis. Although encouraging results have been published, the number of studies remains small, as 18F-FDG-PET is an expensive investigation that is not available everywhere. Further work is needed to determine the cost-effectiveness ratio of 18F-FDG-PET in patients with infections or inflammatory diseases. Imaging plays a prominent role in the diagnosis and management of many musculoskeletal diseases. Although considerable progress has been made recently, the structural information supplied by conventional imaging methods is inadequate in some patients. Positron emission tomography (PET) after injection of 18fluorodeoxyglucose (18F-FDG) provides information on tissue metabolism. The usefulness of 18F-FDG-PET in oncology is now widely recognized. Other uses are emerging, in part thanks to the development of new cameras that combine dedicated detectors and an X-scanner in order to ensure accurate three-dimensional localization of metabolically active lesions. However, the exact role for 18F-FDG-PET needs to be studied in larger populations of patients.

PET in lymphoma

This review attempts to discuss the role of positron emission tomography (PET) imaging for staging, treatment response and follow-up of patients with lymphoma. The pitfalls and impact of PET imaging on the clinical management are also addressed.

False-positive axillary lymph node on FDG-PET/CT scan resulting from immunization

An initial CT of a 59-year-old man with increasing back pain and weight loss showed lymphadenopathy in multiple nodal beds. A biopsy showed diffuse, large B-cell lymphoma (DLBCL). After initial chemotherapy, residual disease prompted an autologous stem cell transplant. After a follow-up FDG-PET/CT scan showed no FDG-avid disease, a subsequent study showed FDG uptake in a nonenlarged left axillary lymph node. Questioning elicited a recent immunization history. A follow-up PET/CT scan showed no uptake in this lymph node and no disease recurrence. Without this history, an unnecessary biopsy or treatment may have ensued. Methods to avoid such occurrences are discussed.

FDG-PET/CT predicts outcome in patients with aggressive non-Hodgkin’s lymphoma and Hodgkin’s disease

Early therapy response assessment with metabolic imaging is potentially useful to determine prognosis in aggressive lymphoma and, thus, can guide first-line therapy. Forty-eight patients with aggressive lymphoma [24 Hodgkin's disease (HD); 24 non-Hodgkin's lymphoma (NHL)] underwent fluoro-deoxyglucose positron emission tomography (FDG-PET) before chemotherapy (PET1) and at mid-treatment (PET2). Therapeutic response was evaluated using conventional methods at mid-treatment. PET2 results were related to event-free survival (EFS) and overall survival (OS) using Kaplan-Meier analyses. PET1 was positive in all patients. PET2 was negative in 38 patients (18 NHL-20 HD) and positive in 10 (6 NHL-4 HD). Of the PET-negative patients, 61 and 65% achieved complete remission, and only 50 and 25% of PET-positive patients, respectively, for NHL and HD, achieved complete remission. Significant associations were found between PET2 and EFS (p = 0.0006) and OS (p = 0.04) for NHL, and EFS (p < 0.0001) for HD (but not for OS, because no HD patient died). FDG-PET at mid-treatment can predict the outcome of patients with aggressive lymphoma and should be a useful tool to modify an ineffective therapy.

Value of PET/CT versus PET and CT performed as separate investigations in patients with Hodgkin’s disease and non-Hodgkin’s lymphoma

PURPOSE

The aim of this study was to assess the clinical benefit of combined [(18)F]FDG PET/CT in patients with malignant lymphoma as compared to separately performed PET and CT.

METHODS

Overall, 100 patients with Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) were included in this study. Co-registered PET/CT with [(18)F]FDG and contrast medium was performed in 50 consecutive patients with NHL (n=38) or HD (n=12) for initial staging (IS) (n=12) or re-treatment staging (RS) (n=38). Another 50 patients with NHL (n=32) or HD (n=18) underwent separate PET and CT investigations within a time frame of 10 days for IS (n=22) or RS (n=28). Lymphoma involvement was separately evaluated for seven different regions in each patient. Each patient had clinical follow-up evaluation for >6 months. PET and CT data were analysed separately as well as side-by-side or in fused mode.

RESULTS

In the PET/CT group, region-based evaluation for lymphoma involvement suggested a sensitivity/specificity of 85%/91% for CT, 98%/99% for PET and 98%/99% for PET/CT. In the PET and CT group, region-based evaluation showed a sensitivity/specificity of 87%/80% for CT, 98%/99% for PET and 98%/100% for PET and CT read side by side.

CONCLUSION

PET was superior to CT alone and was improved further by side-by-side reading of both examinations. However, no significant difference was observed between PET/CT and separate PET and CT imaging in patients with lymphoma.