Value of 18FDG PET scan in staging of ocular adnexal lymphomas: a large single-center experience

Fluorine 18 deoxyglucose positron emission tomography ((18)FDG PET) is widely used in staging of non-Hodgkin's lymphomas (NHL), but very few studies have focused on its role in the initial staging of patients with ocular adnexal lymphoma (OAL). The aim of this study was therefore to evaluate the role of (18)FDG PET in the diagnosis of ophthalmologic lymphoma. A retrospective review of all imaging records, including computed tomography (CT), magnetic resonance imaging (MRI), and FDG PET, was performed. Forty-one OAL patients were included in the study. A pathologic review according to the World Health Organization classification showed 32 low-grade lymphoma patients (78%), including 26 mucosa-associated lymphoid tissue lymphomas (63%). Ophthalmologic sites were intra-orbital + lacrimal gland in 24 patients (59%), conjunctival in 13 patients (32%), multiple in 4 cases, and bilateral in 6 patients. (18)FDG PET was positive in orbital and conjunctival sites in 68 and 35% of cases, respectively. (18)FDG PET positivity was correlated with pathologic sites detected by MRI in 22/30 patients (73%); (18)FDG PET positivity was correlated with pathologic sites detected by CT in 25/34 patients (73%). This study shows that (18)FDG PET has a lower sensitivity than MRI to detect ophthalmologic lymphoma, particularly in non-conjunctival sites.     

Direct comparison of 18F-fluorodeoxyglucose coincidence gamma camera tomography with gallium scanning for the staging of lymphoma

BACKGROUND: The present study compared the performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) using a coincidence dual-head gamma camera (FDG Co-PET) with 67gallium scinti graphy (GS) in pretreatment staging of lymphoma. METHODS: A total of 46 patients underwent FDG Co-PET, computed tomography (CT) scanning and GS for pretreatment staging of lymphoma (40 newly diagnosed and recurrence) between November 1997 and December 1999. RESULTS: Histological subgroups comprised low grade (8 patients), intermediate grade (25) high-grade (3) non-Hodgkin's lymphoma and Hodgkin's disease (10). Based on clinical assessment, CT scan findings and biopsy, 100 nodal sites and 15 extra-nodal sites were deemed positive. FDG Co-PET was superior to GS in nodal site positivity rate (97%vs 79%, P < 0.0001). Compared with GS, FDG Co-PET detected 39 more abnormal sites in 22 patients (48%), of which 28 sites were validated by biopsy, CT and/or progress FDG Co-PET scanning. There was only one proven false negative FDG site in the spleen. CT + FDG Co-PET led to upstaging in 2 patients (4%), compared to CT + GS. CONCLUSION: FDG Co-PET shows potential for providing an accurate means for pretreatment staging of lymphoma and can detect extra sites of disease activity compared to GS.     

FDG‐PET/CT in the management of lymphomas: current status and future directions

FDG‐PET/CT is the current state‐of‐the‐art imaging in lymphoma and plays a central role in treatment decisions. At diagnosis, accurate staging is crucial for appropriate therapy selection: FDG‐PET/CT can identify areas of lymphoma missed by CT alone and avoid under‐treatment of patients with advanced disease stage who would have been misclassified as having limited stage disease by CT. Particularly in Hodgkin lymphoma, positive interim FDG‐PET/CT scans are adversely prognostic for clinical outcomes and can inform PET‐adapted treatment strategies, but such data are less consistent in diffuse large B‐cell lymphoma. The use of quantitative FDG‐PET/CT metrics using metabolic tumour volume, possibly in combination with other biomarkers, may better define prognostic subgroups and thus facilitate better treatment selection. After chemotherapy, FDG‐PET/CT response is predictive of outcome and may identify a subgroup who benefit from consolidative radiotherapy. Novel therapies, in particular immunotherapies, exhibit different response patterns than conventional chemotherapy, which has led to modified response criteria that take into account the risk of transient pseudo‐progression. In relapsed lymphoma, FDG‐PET/CT after second‐line therapy and prior to high‐dose therapy is also strongly associated with outcome and may be used to guide intensity of salvage therapy in relapsed Hodgkin lymphoma. Currently, FDG‐PET/CT has no role in the routine follow‐up after complete metabolic response to therapy, but it remains a powerful tool for excluding relapse if patients develop clinical features suggestive of disease relapse. In conclusion, FDG‐PET/CT plays major roles in the various phases of management of lymphoma and constitutes a step towards the pursuit of personalized treatment.     

Early Cancer of the Stomach Arising after Successful Treatment of Gastric MALT Lymphoma in Patients with Autoimmune Disease

Background: Extranodal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT lymphoma) arises in lymphoid tissue acquired through chronic antigenic stimulation as exemplified by Helicobacter pylori. Secondary development of gastric cancer, however, is thought to be a rare event. The detection of a signet ring cell carcinoma during follow-up endoscopy after successful therapy of MALT lymphoma in a patient with Sjogren's syndrome prompted us to analyse the frequency of subsequent gastric cancer in patients with underlying autoimmune disease (AD). Methods: Patients with early stage MALT lymphoma and an underlying AD were evaluated for the occurrence of a secondary gastric cancer during the course of follow-up. Data analysed included the type of AD, stage of MALT lymphoma, H. pylori status, treatment for MALT lymphoma and response, follow-up, the presence of a secondary cancer, and time to development of cancer. In all patients, histologic samples were reassessed for the extent of gastritis, presence of intestinal metaplasia or focal atrophy at the time of lymphoma diagnosis. Results: A total of eight patients with overt AD at the time of diagnosis of MALT lymphoma were identified. All patients were women aged between 56 and 77 years; 5 had Sjogren's syndrome, 2 had autoimmune thyroiditis (1 along with psoriasis) and 1 suffered from polymyalgia rheumatica. All patients had early stage MALT lymphoma restricted to the mucosa and submucosa at the time of diagnosis, and the presence of H. pylori was found in all cases. Two of these patients achieved complete remission (CR) of the lymphoma following H. pylori eradication, while six were judged unresponsive and underwent chemotherapy, resulting in CR in all cases. One patient died from stroke while being in CR for 2 months following chemotherapy. Two patients (25%) developed early cancer limited to the gastric mucosa while being in CR from lymphoma for 9 and 27 months, respectively, and underwent partial gastrectomy. Final staging of gastric cancer revealed pTlpNOMO in both cases. Of the remaining 5 cases, 1 patient had a local lymphoma relapse 18 months after CR and was salvaged with radiotherapy. In the remaining 4 patients, no evidence of lymphoma recurrence or a second malignancy has been found so far by regular follow-up every 3 months for a time-span between 52 and 63 months after initial diagnosis. Conclusion: Patients with concurrent MALT lymphoma and an underlying autoimmune condition show not only an impaired response to H. pylori eradication but might also be at increased risk for the development of gastric cancer. In view of this, such patients should be followed closely by regular endoscopies after remission of MALT lymphoma.     

Long-term follow up of gastric low-grade mucosa-associated lymphoid tissue lymphoma by endosonography emphasizing the application of a miniature ultrasound probe

BACKGROUND AND AIMS: Endoscopic ultrasonography (EUS) is a useful tool for the evaluation of gastric wall infiltration including gastric lymphoma. The aims of this study were to characterize gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphoma according to EUS findings and to evaluate the role of a miniature ultrasound probe in the long-term follow up. METHODS: From January 1994 to March 2002, 20 patients were proven to have gastric low-grade MALT lymphoma. Endoscopic ultrasonography was performed with a conventional echoprobe and/or a miniature ultrasound probe for initial staging and a miniature ultrasound probe was performed during follow up. All patients positive for Helicobacter pylori received a 2-week course of omeprazole, amoxicillin and clarithromycin. RESULTS: Helicobacter pylori infection was found in 17 (85%) patients. In all patients, H. pylori was eradicated after treatment. Initial EUS showed significantly greater wall thickness (6.1 +/- 3.0 mm) in MALT lymphoma patients when compared with control (2.8 +/- 0.3 mm). The infiltrative patterns included wall thickening (3.5-14.1 mm) in 18 patients: stage E-I1 in 16 (mucosa and/or submucosa), stage E-I2 in one and stage E-II in one. Complete regression of MALT lymphoma following treatment for H. pylori was noted in 14 patients, with a mean duration of 11.3 +/- 9.1 months. Follow-up miniature ultrasound probe sonography showed comparative reduction in wall thickness (P < 0.05). CONCLUSIONS: Endoscopic ultrasonography plays a valuable role in the initial staging and long-term follow up of gastric low-grade MALT lymphoma. The application of a miniature ultrasound probe enables adequate evaluation in the majority of these patients, with additional benefits.     

Incidental carcinomas detected by PET/CT scans in patients with malignant lymphoma

According to the international working group response criteria for malignant lymphoma revised in 2007, 18F-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) combined with or without computed tomography (CT) is recommended for pre-treatment staging and response assessment among patients with diffuse large B-cell lymphoma and Hodgkin lymphoma. Recently, along with the widespread use of PET/CT, unexpected uptake and accumulation of ¹⁸FDG has been reported. Discussed in the present report are patients with malignant lymphoma and second primary carcinomas that were incidentally found by PET/CT. A total of 497 consecutive PET/CT were performed on 290 patients with malignant lymphoma in our institution from April 2008 through March 2010. Eight patients (2.8%) had pathologically confirmed second primary carcinomas consisting of 4 colon cancers, 3 lung cancers, and 1 pancreatic cancer. Two cases were diagnosed at the initial staging, and the others were detected after treatment for lymphoma. It is noteworthy that PET revealed high accumulations of ¹⁸FDG in 5 (62.5%) of the 8 patients without corresponding tumors in conventional CT. All of the 4 patients with colon carcinoma underwent curative surgery. The present study suggests that incidental findings by PET in malignant lymphoma can lead to early detection and successful treatment of second malignancies.     

The utility of positron emission tomography/computed tomography in the staging of extranodal natural killer/T-cell lymphoma

Natural killer (NK)/T-cell lymphoma cases are rarely discovered using positron emission tomography/computed tomography (PET/CT). We compared the utility of PET/CT and that of conventional methods (CMs; CT with IV contrast, biopsies from primary sites, and bone marrow examinations) in the staging of extranodal NK/T-cell lymphoma. Nineteen untreated patients with extranodal NK/T-cell lymphoma at three institutions were analyzed. PET/CT and CMs were applied for initial workups following diagnosis. PET/CT and CMs were compared and evaluated for their ability to detect tumor lesions and their influence on the staging and treatment strategies. In total, 116 lesions were detected by CM and PET/CT. Using PET/CT, 108 lesions (93%) were discovered. The number of nodal lesions was 28: all were positive by PET/CT and 26 (93%) by CMs. The number of extranodal lesions was 89: 84 (94%) and 54 (61%) lesions were positive by PET/CT and CMs, respectively. PET/CT was superior to CMs in detecting cutaneous lesions [31/31 lesions (100%) vs. 20/31 lesions (65%), respectively; P=0.042]. Bone marrow involvement was confirmed pathologically in only seven patients; four cases (57%) were positive by PET/CT. Using CMs, ten patients (53%) were stages I-II and nine (47%) were stages III-IV. Using PET/CT, eight patients (42%) were in stages I-II and 11 (58%) were in stages III-IV. PET/CT findings altered the stage and treatment strategy in two cases (11%). Our study demonstrated that PET/CT is a useful tool for detecting extranodal lesions in NK/T-cell lymphoma, particularly cutaneous lesions. PET/CT may therefore influence future staging and treatment strategies.     

Early cancer of the stomach arising after successful treatment of gastric MALT lymphoma in patients with autoimmune disease

BACKGROUND: Extranodal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT lymphoma) arises in lymphoid tissue acquired through chronic antigenic stimulation as exemplified by Helicobacter pylori. Secondary development of gastric cancer, however, is thought to be a rare event. The detection of a signet ring cell carcinoma during follow-up endoscopy after successful therapy of MALT lymphoma in a patient with Sj?gren's syndrome prompted us to analyse the frequency of subsequent gastric cancer in patients with underlying autoimmune disease (AD). METHODS: Patients with early stage MALT lymphoma and an underlying AD were evaluated for the occurrence of a secondary gastric cancer during the course of follow-up. Data analysed included the type of AD, stage of MALT lymphoma, H. pylori status, treatment for MALT lymphoma and response, follow-up, the presence of a secondary cancer, and time to development of cancer. In all patients, histologic samples were reassessed for the extent of gastritis, presence of intestinal metaplasia or focal atrophy at the time of lymphoma diagnosis. RESULTS: A total of eight patients with overt AD at the time of diagnosis of MALT lymphoma were identified. All patients were women aged between 56 and 77 years; 5 had Sj?gren's syndrome, 2 had autoimmune thyroiditis (1 along with psoriasis) and 1 suffered from polymyalgia rheumatica. All patients had early stage MALT lymphoma restricted to the mucosa and submucosa at the time of diagnosis, and the presence of H. pylori was found in all cases. Two of these patients achieved complete remission (CR) of the lymphoma following H. pylori eradication, while six were judged unresponsive and underwent chemotherapy, resulting in CR in all cases. One patient died from stroke while being in CR for 2 months following chemotherapy. Two patients (25%) developed early cancer limited to the gastric mucosa while being in CR from lymphoma for 9 and 27 months, respectively, and underwent partial gastrectomy. Final staging of gastric cancer revealed pT1pN0M0 in both cases. Of the remaining 5 cases, 1 patient had a local lymphoma relapse 18 months after CR and was salvaged with radiotherapy. In the remaining 4 patients, no evidence of lymphoma recurrence or a second malignancy has been found so far by regular follow-up every 3 months for a time-span between 52 and 63 months after initial diagnosis. CONCLUSION: Patients with concurrent MALT lymphoma and an underlying autoimmune condition show not only an impaired response to H. pylori eradication but might also be at increased risk for the development of gastric cancer. In view of this, such patients should be followed closely by regular endoscopies after remission of MALT lymphoma.     

Clinical study of 31 patients with primary gastric mucosa-associated lymphoid tissue lymphoma

BACKGROUND: The purpose of the present paper was to investigate the clinical, endoscopic and histological features of 31 patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma to enable correct, early stage diagnosis. METHODS: A retrospective study was undertaken of 31 patients with gastric MALT lymphoma. The cases were examined immunohistologically with anti-CD(20CY) and CD(45RO) antibodies for further diagnosis. Helicobacter pylori infection was also detected with modified Giemsa staining. RESULTS: Patients with MALT lymphoma were aged between 22 and 73 years (mean, 45.0 years), and the male:female ratio was 11:20. The patients presented with non-specific symptoms, but chronic epigastric pain was the common symptom in a large proportion of the cases. The gastric smaller curvature was involved in 83.9% of cases (26/31) and in 13/31 cases (41.9%) it was confined the antrum. Under endoscopy, large and deep ulcers were similar to cancers in the majority of patients. Only 29.0% of patients were diagnosed by endoscopy on first examination. CD(20CY) were expressed in all cases and CD(45RO) expressed in only one case among 10 cases of indefinite diagnosis. Helicobacter pylori infection was found in 87.1% of patients. CONCLUSIONS: These findings suggest that primary gastric MALT lymphoma has unique clinical, endoscopic and histological features. The diagnosis for primary gastric MALT lymphoma was delayed not only due to the non-specific symptoms but also due to lack of attention to its features. Endoscopy and submucosal multiple biopsy were the principal diagnostic tools in patients with gastric MALT lymphoma. CD(20CY) and CD(45RO) immunological staining are recommended, especially for patients with indefinite diagnosis of gastric MALT lymphoma.     

Occult nodal metastasis in patients with non‐small cell lung cancer at clinical stage IA by PET/CT

Background and objective: The introduction of ¹⁸F‐FDG PET/CT has enhanced the diagnostic accuracy of nodal staging for non‐small cell lung cancer (NSCLC). We analysed risk factors for occult nodal metastasis in patients with clinical stage IA NSCLC as determined by ¹⁸F‐FDG PET/CT. Methods: Data for 147 patients diagnosed as clinical stage IA NSCLC by PET/CT from 2005 to 2007 were retrospectively reviewed. All study patients underwent ¹⁸F‐FDG PET/CT for lung cancer staging. They also underwent cervical mediastinoscopy or systematic lymph node dissection. Results: Cervical mediastinoscopy was performed in 78 patients (53.1%), and N2 involvement was detected in 3.8% (3/78) of these patients. Thoracotomy with systematic lymph node dissection was done in 144 patients. Four patients (2.8%, 4/144) were diagnosed with N2 disease after systematic lymph node dissection. Total N2 involvement was 4.8% (7/147). As 9.5% (14/147) of study patients had N1 disease, 14.3% (21/147) of patients had occult nodal (N1 or N2) metastasis. In univariate analyses, larger tumour size and a higher primary tumour maximum standardized uptake value >7.3 (SUV_max) were associated with occult nodal metastasis. Multivariate analysis demonstrated that a primary tumour SUV_max >7.3 was an independent predictor of occult nodal metastasis (odds ratio: 7.574; P = 0.001). Conclusions: Preoperative PET/CT scans contribute to reduce the frequency of occult nodal metastasis compared with those reported in the pre‐PET/CT era. The higher SUV_max in primary tumour was an independent predictor of occult nodal metastasis in patients with clinical stage IA NSCLC by PET/CT.     

Transformed mucosa-associated lymphoid tissue lymphomas: A single institution retrospective study including polymerase chain reaction-based clonality analysis

Given the lack of consistent data regarding the clinico-pathological features and clonal lymphomagenesis of patients with mucosa-associated lymphoid tissue (MALT) lymphoma and histological transformation (HT), we have systematically analysed 379 patients (32% gastric, 68% extra-gastric; median follow-up 52 months) diagnosed with HT at the Medical University Vienna 1999–2017, and reassessed tissues of identified patients by polymerase chain reaction (PCR)-based clonality analysis. HT was documented in 12/379 patients (3·2%) and occurred at a median time of 22 months (range; 6–202 months) after diagnosis of MALT lymphoma. By PCR-based clonality analysis, we detected a clear-cut clonal relationship of MALT lymphoma and diffuse large B-cell lymphoma (DLBCL) in 8 of 11 analysed cases proving that the large majority of DLBCL following MALT lymphoma are clonally-related and constitute a real transformation. Interestingly, HT occurred within the first 2·5 years after diagnosis in patients with clonal relationship, whereas time to aggressive lymphoma was longer in patients identified as clonally-unrelated (most likely secondary) lymphoma (82–202 months), suggesting that HT is an early event in this disease. Survival of patients with HT was poor with 6/12 dying at 1·5–33 months after HT, however, patients with localized gastric transformation had a superior outcome with only 1/6 dying due to progression of lymphoma.     

Use of integrated FDG PET/CT imaging in pulmonary carcinoid tumours

BACKGROUND: Integrated positron emission tomography (PET)/computed tomography (CT) scanners have been recently introduced in the diagnostic work-up of suspected pulmonary malignancy and demonstrate encouraging results in the staging of nonsmall-cell lung cancer. OBJECTIVE: To evaluate the usefulness of integrated FDG PET/CT in pulmonary carcinoid tumours. SETTING: University hospital. METHODS: We studied 13 patients (mean age +/- 1 SD, 57 +/- 11 years) with pulmonary carcinoid tumours. All patients demonstrated a single pulmonary lesion. Integrated PET/CT scan and surgical resection were performed in all patients. RESULTS: The pulmonary lesion size ranged from 1.1 to 5.0 cm. Final histological diagnosis confirmed 12 typical and one atypical pulmonary carcinoid. Mean proliferation rate of the typical carcinoids was 1.7 +/- 1.4%. None of the patients had recurrent carcinoid disease or died during follow-up (864 +/- 218 days). Mean standardized uptake value (SUV) of (18)F-fluorodeoxyglucose (FDG) in typical carcinoids was 3.0 +/- 1.5 (range 1.2 - 6.6); SUV in the atypical carcinoid was remarkably high with a value of 8.5. The SUV was lower than 2.5 in 6 of 12 patients (50%). Mediastinal lymph node metastases or extrathoracic metastases were not detected in any patient. CONCLUSIONS: (18)F-fluorodeoxyglucose PET/CT imaging improves accurate localization of metabolic activity and thus the interpretation of pulmonary lesions on CT. FDG uptake in pulmonary carcinoid tumours is often lower than expected for malignant tumours. Therefore, surgical resection or biopsy of lesions suspected to be carcinoids should be mandatory, even if they show no hypermetabolism on FDG PET images.     

The utility of 99mTc depreotide compared with F-18 fluorodeoxyglucose positron emission tomography and surgical staging in patients with suspected non-small cell lung cancer

STUDY OBJECTIVES: The findings from conventional imaging modalities, such as chest CT, are frequently unreliable in patients with lung cancer. This study was designed to compare the relative diagnostic accuracies and utility of the two most widely used functional imaging examinations, F-18-2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and (99m)Tc depreotide scintigraphy, for the diagnosis and staging of lung cancer. DESIGN: Prospective, experimental investigation. SETTING: Academic medical center. PATIENTS: One hundred sixty-six subjects with suspected lung cancer were enrolled in the study. INTERVENTIONS: Whole-body and single-photon emission CT imaging of the chest was performed after IV administration of (99m)Tc depreotide. Attenuation-corrected FDG PET imaging was performed after IV administration of FDG. Image findings were compared with the biopsy results or clinical follow-up. Measurements and results: In 157 subjects with evaluable lung lesions, the sensitivities and specificities for detecting malignant disease (95% confidence intervals) of FDG PET are 96% (90 to 98%) and 71% (54 to 85%), and of (99m)Tc depreotide are 94% (88 to 98%) and 51% (34 to 68%). In the 139 subjects with available complete staging data, FDG PET correctly staged 76 of 139 patients (55%), and (99m)Tc depreotide correctly staged 63 of 139 patients (45%). CONCLUSIONS: The sensitivity for detection of lung cancer in the primary lesion is equally high for FDG PET and (99m)Tc depreotide. The specificity is superior for FDG PET. The staging accuracy of FDG PET and (99m)Tc depreotide is similar, but when read with the chest CT neither scintigraphic examination is sufficiently accurate to stage patients with non-small cell lung cancer.     

Usefulness of 18F-fluorodeoxyglucose positron emission tomography in differential diagnosis and staging of cholangiocarcinomas

Background and Aim: ¹⁸F‐Fluoro‐2‐deoxy‐d ‐glucose positron emission tomography (¹⁸FDG‐PET) is promising for diagnosis and treatment of various malignancies. The aim of this study was to evaluate the clinical usefulness of ¹⁸FDG‐PET in differential diagnosis and staging of cholangiocarcinomas according to the intrahepatic, perihilar and common bile duct lesions and to compare with computerized tomography (CT) scan. Methods: From January 2000 to September 2003, 54 patients with suspected cholangiocarcinoma underwent abdominal CT scan and ¹⁸FDG‐PET within a 2‐week period. The PET images were analyzed visually and semiquantitatively. Results: The overall accuracy of ¹⁸FDG‐PET for discriminating malignant diseases of bile duct from benign conditions was slightly higher than that of CT scan (88.9% vs 81.5%). The sensitivity of ¹⁸FDG‐PET in perihilar cholangiocarcinoma was lower than the value of intrahepatic and common bile duct cancers (83.3% vs 91.3%, 90.9%); moreover, in cases of perihilar cancer, the sensitivity of ¹⁸FDG‐PET was lower than that of CT scans (83.3% vs 91.7%). ¹⁸FDG‐PET detected nine distant metastatic lesions not found by other imaging studies and excluded two patients who potentially had resectable condition in other imaging studies from unnecessary laparotomy. Conclusion: The clinical usefulness of ¹⁸FDG‐PET in differential diagnosis of bile duct cancers is related to the site of primary disease. Although it is a helpful method for differential diagnosis especially in cases of intrahepatic and common bile duct cancers, ¹⁸FDG‐PET can not provide confirmative clues in perihilar cholangiocarcinoma. ¹⁸FDG‐PET may hold promise in the detection of hidden distant metastasis and can play an additional role in the evaluation of resectability. ¹⁸FDG‐PET can be complementary to CT scan in diagnosing and staging of cholangiocarcinoma.     

Diagnosis and evaluation of gastric cancer by positron emission tomography

Gastric cancer is the second leading cause of cancer mortality worldwide.The diagnosis of gastric cancer has been significantly improved with the broad availability of gastrointestinal endoscopy.Effective technologies for accurate staging and quantitative evaluation are still in demand to merit reasonable treatment and better prognosis for the patients presented with advanced disease.Preoperative staging using conventional imaging tools,such as computed tomography(CT)and endoscopic ultrasonography,is inadequate.Positron emission tomography(PET),using 18F-fluorodeoxyglucose(FDG)as a tracer and integrating CT for anatomic localization,holds a promise to detect unsuspected metastasis and has been extensively used in a variety of malignancies.However,the value of FDG PET/CT in diagnosis and evaluation of gastric cancer is still controversial.This article reviews the current literature in diagnosis,staging,response evaluation,and relapse monitoring of gastric cancer,and discusses the current understanding,improvement,and future prospects in this area.     

Whole-body positron emission tomography using 18F-fluorodeoxyglucose for initial staging of patients with Hodgkin's disease

An accurate initial staging of patients with Hodgkin's disease (HD) is important for the evaluation of clinical stage and risk factors, which are crucial for the choice of an appropriate treatment. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is useful for detecting active tumor tissue in patients with lymphoproliferative diseases and may contribute to conventional staging methods in patients with HD. Twenty-two patients who presented with newly diagnosed HD underwent conventional staging methods including computed tomography (CT) as well as FDG PET. Lesions apparent in FDG PET and CT were correlated to each other. Seventy-seven lesions were observed either in PET or CT or in both. In 48 (62%) lesions PET and CT were both positive. In 20 (26%) sites, PET was positive and CT negative. Of 22 patients (18%) 4 were upstaged due to these positive PET findings, and as a result one patient received a different therapeutic regimen. PET failed to detect nine (12%) CT-positive sites in six patients. Statistically, these data are reflected by a sensitivity for PET and CT of 88% and 74%, respectively. Specificity of both imaging modalities was 100%. PET can contribute valuable information as an additional staging examination and led to an upstaging in some patients with primary HD. However, PET should not be used as the only imaging modality as it failed to detect CT-positive, active tumor regions in some cases.     

The role of FDG‐PET/CT in the evaluation of residual disease in paediatric non‐Hodgkin lymphoma

¹⁸F‐labelled–fluorodeoxyglucose positron emission tomography (FDG‐PET) findings are challenging to interpret for residual disease versus complete response in paediatric patients with non‐Hodgkin lymphoma (NHL). A biopsy is often warranted to confirm the presence or absence of viable tumour if there is clinical or radiographic evidence of residual disease. In this study, we compared conventional imaging and FDG‐PET/computerized tomography (CT) findings with biopsy results in 18 children with NHL. Our goal was to provide additional data to establish more reliable criteria for response evaluation. Residual disease was suspected after conventional imaging alone in eight patients, after FDG‐PET/CT alone in three and after both modalities in seven patients. Biopsy confirmed the presence of viable tumour in two patients. Two additional patients experienced progressive disease or relapse. The sensitivity and negative predictive value of FDG‐PET/CT using the London criteria to indicate residual tumour detectable by biopsy were 100%, but specificity was low (60%), as was the positive predictive value (25%). Thus, in this study, a negative FDG‐PET/CT finding was a good indicator of complete remission. However, because false‐positive FDG‐PET/CT findings are common, biopsy and close monitoring are required for accurate determination of residual disease in individual patients.     

Lymphomatous involvement of gastrointestinal tract： Evaluation by positron emission tomography with ^18F-fluorodeoxyglucose

AIM: To demonstrate the 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) findings in patients with non-Hodgkin's lymphoma (NHL) involving the gastrointestinal (GI) tract and the clinical utility of modality despite of the known normal uptake of FDG in the GI tract. METHODS: Thirty-three patients with biopsy-proven gastrointestinal NHL who had undergone FDG-PET scan were inducted. All the patients were injected with 10-15 mCi FDG and scanned approximately 60 min later with a CTI/ Siemens HR (+) PET scanner. PET scans were reviewed and the maximum standard uptake value (SUVmax) of the lesions was measured before and after the treatment, if data were available and compared with histologic diagnoses. RESULTS: Twenty-five patients had a high-grade lymphoma and eight had a low-grade lymphoma. The stomach was the most common site of the involvement (20 patients). In high-grade lymphoma, PET showed focal nodular or diffuse hypermetabolic activity. The average SUVmax±SD was 11.58±5.83. After the therapy, the patients whose biopsies showed no evidence of lymphoma had a lower uptake without focal lesions. The SUVmax±SD decreased from 11.58±5.83 to 2.21± 0.78. In patients whose post-treatment biopsies showed lymphoma, the SUVmax±SD was 9.42±6.27. Low-grade follicular lymphomas of the colon and stomach showed diffuse hypermetabolic activity in the bowel wall (SUVmax 8.2 and 10.3, respectively). The SUVmax was 2.02-3.8 (mean 3.02) in the stomach lesions of patients with MALT lymphoma. CONCLUSION: 18F-FDG PET contributes to the diagnosis of high-grade gastrointestinal non-Hodgkin's lymphoma, even when there is the normal background FDG activity. Furthermore, the SUV plays a role in evaluating treatment response. Low-grade NHL demonstrates FDG uptake but at a lesser intensity than seen in high-grade NHL     

Positron emission tomography scanning in the assessment of patients with lymphoma

BACKGROUND: The detection of lymphoma by computed tomography (CT) scanning is known to be improved by positron emission tomography (PET) and/or gallium scanning, although the direct comparative accuracy of these imaging modalities remains a subject of ongoing review. AIMS: The aim of the present study was to compare PET scanning with conventional imaging (CT and/or gallium scanning) in patients with lymphoma. METHODS: A retrospective study of 38 patients (25 men; 13 women; median age 39.5 years; range 18.0-81.0 years) who had had PET scans (24 scans at initial staging and 46 scans at restaging, including suspected disease relapse) was carried out. Thirty-one concurrent gallium scans had been performed. Disease was validated with clinical follow up or biopsy. RESULTS: The sensitivities of PET and CT at initial staging were 96 and 71%, respectively. PET identified additional sites of disease compared with CT in 29% of patients. Of the 15 patients who had had all three imaging modalities, the sensitivities of PET, CT and gallium were 93, 67 and 87%, respectively. At treatment completion, the positive predictive values of PET, CT and gallium scans for relapse given a residual mass were 100, 33 and 0%, respectively (P = 0.006 for PET and CT comparison). The negative predictive values of PET, CT and gallium were 76, 0 and 70%, respectively (P-value not significant). In suspected disease relapse, PET results changed management in 50% of patients. CONCLUSION: Compared with CT and gallium scans, PET has superior accuracy in staging and restaging, and its greatest value lies in its positive predictive value for relapse in patients with residual masses.