Thoracic positron emission tomography: 18F-fluorodeoxyglucose and beyond

Ongoing technologic and therapeutic advancements in medicine are now testing the limits of conventional anatomic imaging techniques. The ability to image physiology, rather than simply anatomy, is critical in the management of multiple disease processes, especially in oncology. Nuclear medicine has assumed a leading role in detecting, diagnosing, staging and assessing treatment response of various pathologic entities, and appears well positioned to do so into the future. When combined with computed tomography (CT) or magnetic resonance imaging (MRI), positron emission tomography (PET) has become the sine quo non technique of evaluating most solid tumors especially in the thorax. PET/CT serves as a key imaging modality in the initial evaluation of pulmonary nodules, often obviating the need for more invasive testing. PET/CT is essential to staging and restaging in bronchogenic carcinoma and offers key physiologic information with regard to treatment response. A more recent development, PET/MRI, shows promise in several specific lung cancer applications as well. Additional recent advancements in the field have allowed PET to expand beyond imaging with ¹⁸F-flurodeoxyglucose (FDG) alone, now with the ability to specifically image certain types of cell surface receptors. In the thorax this predominantly includes ⁶⁸Ga-DOTATATE which targets the somatostatin receptors abundantly expressed in neuroendocrine tumors, including bronchial carcinoid. This receptor targeted imaging technique permits targeting these tumors with therapeutic analogues such as ¹⁷⁷Lu labeled DOTATATE. Overall, the proper utilization of PET in the thorax has the ability to directly impact and improve patient care.     

Positron emission tomography with computed tomography imaging of neuroinflammation in experimental autoimmune encephalomyelitis

2-[(18)F]Fluoro-2-deoxy-d-glucose positron emission tomography ([(18)F]FDG PET) detection of the up-regulated glycolysis associated with malignant transformation is a noninvasive imaging technique used extensively in cancer diagnosis. Although striking similarities exist in glucose transport and metabolism between tumor cells and activated immune cells, the potential use of [(18)F]FDG PET for the diagnosis and evaluation of autoimmune disorders has not been systematically investigated. Here we ask whether [(18)F]FDG PET in conjunction with computed tomography (CT) could be used to monitor a complex autoimmune disorder such as murine experimental autoimmune encephalomyelitis (EAE) and whether this approach is sensitive enough to evaluate therapeutic interventions. We found that (i) coregistration of metabolic (i.e., microPET) and high-resolution anatomical (i.e., CT) images allows serial quantification of glycolysis with [(18)F]FDG in various spinal column segments; (ii) [(18)F]FDG PET/CT can detect the increased glycolysis associated with paralysis-causing inflammatory infiltrates in the spinal cord; and (iii) the [(18)F]FDG measure of glycolysis in the spinal cord is sensitive to systemic immunosuppressive therapy. These results highlight the potential use of serial [(18)F]FDG PET/CT imaging to monitor neuroinflammation in EAE and suggest that similar approaches could be applied to the diagnosis and evaluation of other autoimmune and inflammatory disorders in animal models and in humans.     

Functional Imaging Methods for Assessment of Minimal Residual Disease in Multiple Myeloma: Current Status and Novel ImmunoPET Based Methods

Imaging plays a key role in assessment of myeloma. Osteolytic bone lesions are optimally assessed using structural imaging, however the structural changes lag the functional changes in the disease. Functional imaging with fluoro deoxy glucose (FDG) positron emission tomography (PET) computerized tomography (CT) is useful in assessment of high-risk myeloma. FDG PET provides prognostic information and is helpful in monitoring response to therapy. However, it is nonspecific and may not be optimal in assessing treatment response to immunotherapeutic agents. Imaging with targeted agents may allow for better assessment of changes from therapy, that is based on the specific targeted mechanism. ImmunoPET imaging is a novel method to assess targeting of specific antigen by therapeutic antibodies. This review summarizes the role of functional imaging and development of novel immunoPET agents for assessment of treatment response and residual disease.     

How do we image patients with multiple myeloma and precursor states?

Advances in morphological and functional imaging have led to superior detection of early bone disease, bone marrow infiltration, paramedullary and extramedullary involvement in multiple myeloma. The two functional imaging modalities that are most widely used and standardized are 18F-fluorodeoxyglucose–Positron emission tomography/computed tomography (FDG PET/CT) and whole-body magnetic resonance imaging with diffusion-weighted imaging (WB DW-MRI). Both prospective and retrospective studies have demonstrated that WB DW-MRI is more sensitive than PET/CT in the detection of baseline tumour burden and to assess response after therapy. In patients with smouldering multiple myeloma, WB DW-MRI is now the preferred imaging modality to rule out two or more unequivocal lesions which would be considered a myeloma-defining event by the updated international myeloma working group (IMWG) criteria. In addition to sensitive detection of baseline tumour burden, both PET/CT and WB DW-MRI have been successfully used for monitoring response to therapy and provide information that is complementary to IMWG response assessment and bone marrow minimal residual disease. In this article, we present 3 vignettes illustrating how we approach the use of modern imaging in the management of patients with multiple myeloma and precursor states, with a specific focus on recent data that have emerged since the publication of the IMWG consensus guideline on imaging. We have utilized data from prospective and retrospective studies to provide a rationale for our approach to imaging in these clinical scenarios and highlighted knowledge gaps requiring future investigation.     

F-18 FDG uptake of bone marrow on PET/CT scan: it’s correlation with CD38/CD138 expressing myeloma cells in bone marrow of patients with multiple myeloma

The percentage of myeloma cells in bone marrow is subsequently an important index of disease in patients with multiple myeloma (MM). Bone marrow myeloma cells can be detected by strong CD38/CD138 positivity and light scatter characteristics using flow cytometry. The aim of the study was to evaluate the relationship between the degree of F-18 fluorodeoxyglucose (F-18 FDG) uptake and the percentage of CD38/CD138 expressing myeloma cells in the bone marrow of patients with MM. A total of 31 patients with MM (14 females and 17 males, mean age 59.5 ± 1.9 years, range 29–80 years) were included in the study. All patients underwent FDG-positron emission tomography/computed tomography (PET/CT) scan within 2 weeks after the completion of the usual staging workup for MM, consisting of X-ray skeletal survey and hematological/biochemical parameters including complete blood count, liver and kidney function test, erythrocyte sedimentation rate, serum immunoglobulins, urine light chain excretion, C-reactive protein, β2-microglobulin, and bone marrow plasma cell infiltration. In all patients, flow cytometry was performed for assessing the percentage of CD38/CD138 expressing myeloma cells in the bone marrow samples. The extent of bone marrow FDG uptake on PET/CT scans was visually graduated using a qualitative scoring system as extension score (E-score) and also a semiquantitative scoring system defined as mean standardized uptake value (mSUV) of both femora. There was a statistically significant positive correlation between the percentage of CD38/CD138 expressing plasma cells in bone marrow and both mean qualitative (r = 0.616) and semiquantitative (r = 0.755) results of F-18 FDG uptakes. mSUV and E-score of bone marrow FDG uptake values were also correlated with serum beta-2-microglobulin levels (r = 0.523 and r = 479, respectively). mSUV of bone marrow FDG uptake values were also negatively correlated with serum albumin levels (r = −0.424), whereas there was no correlation between E-score and albumin levels. In conclusion, our results indicate that increased F-18 FDG uptake of bone marrow is related to the percentage of plasma cell infiltration of bone marrow in patients with MM. Therefore, F-18 FDG-PET/CT study may be a useful tool for predicting the levels of myeloma cells in bone marrow, and an additional analysis of FDG uptake of bone marrow on FDG-PET/CT scans should be performed in patients undergoing PET studies during the initial staging, evaluating the therapy response, and monitoring patients with MM.     

PET/CT显像在肺癌胰腺转移中的应用价值

目的评估肺癌胰腺转移瘤的CT表现及FDG代谢程度。方法对24例经确诊的肺癌胰腺转移瘤病例进行分析。所有患者都接受18F-FDG PET/CT显像,病灶FDG代谢程度增高(SUVmax2.5),则被视为阳性转移灶。结果 24例肺癌胰腺转移瘤中,腺癌10例(41.7%),鳞癌8例(33.3%),小细胞癌6例(25%)。16例为单发病灶,7例为多发病灶,1例为弥漫性病灶。病灶SUVmax:3.68~13.76不等,平均值为7.08,其中SUVmax≤5的5例、5SUVmax10的15例、SUVmax≥10的4例,病灶SUVmax 5~10之间发生率与其他区间差异具有统计学意义(P0.05)。结论 PET/CT在发现肺癌胰腺转移诊断正确率较高。     

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.     

The future in diagnosis and staging of lung cancer: positron emission tomography

Since its introduction in 1974, positron emission tomography (PET) has gained widespread use, especially in diagnosis and staging of lung cancer. In this respect, (18)F-fluorodeoxyglucose (FDG) is by far the most used PET tracer exploiting the increased glucose uptake and metabolism in malignant cells. A large number of studies have suggested that addition of FDG-PET to conventional workup can improve diagnosis and staging in patients with non-small cell lung cancer (NSCLC). In meta-analysis, the sensitivity and specificity of PET in diagnosing single pulmonary nodules and masses is found to be 96 and 78%, respectively. In mediastinal staging, the sensitivity and specificity of PET is estimated to be 83 and 92%. In order to achieve high diagnostic values from PET, it is necessary to pay attention to a number of pitfalls, e.g., the uptake of FDG by inflammatory cells causing false-positive results, as well as size and histology of the tumour in order to avoid false-negative results. In 2001, the first integrated PET/computed tomography (CT) was installed, and since then, the use of this modality has expanded steadily, thereby decreasing examination time and overcoming the lack of anatomical details on PET. Recently, PET and PET/CT have become increasingly integrated in therapy planning and evaluation: response evaluation during and after chemotherapy, restaging after neoadjuvant therapy, planning of radiotherapy and detection of recurrent disease are all examples of emerging indications for PET and PET/CT in managing patients with lung cancer.     

Molecular imaging of coronary inflammation

Coronary inflammation is related to atherosclerotic disease and, less frequently, systemic vasculitis. Regardless of the etiology, coronary inflammation is associated with adverse cardiac events. Molecular imaging with ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET/CT) allows in vivo assessment of coronary inflammation and evaluation of response to therapy. The aim of this review is to give an update on the recent development of FDG-PET/CT, discuss the potential roles of coronary inflammation imaging, review the limitations of FDG-PET/CT imaging, and give an overview of the new tracers available for PET/CT plaque imaging.     

Extensive Invasive Extramammary Paget Disease Evaluated by F-18 FDG PET/CT: A Case Report

Extramammary Paget disease (EMPD) is a rare cutaneous, intraepithelial adenocarcinoma. Because of its rarity, little is known about the value of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in evaluating this disease. Our case report aims to increase current knowledge of FDG PET/CT in EMPD as a noninvasive imaging tool for assessing the extension of the disease and detecting distant metastases.We reported a 64-year-old Chinese man who presented with a slowly progressive, ill-margined erythematous lesion with a crusted, eroded, and scaly surface involving multiple sites of penis, scrotum, left pelvic wall, hip, groin, and thigh for >4 years, which became extensive in the past 1 year. He was referred for an FDG PET/CT examination to further evaluate the lesions. A following skin biopsy was performed to obtain a definitive histological diagnosis.FDG PET/CT imaging revealed mild FDG uptake at the extensive cutaneous lesion with subcutaneous invasion, involvement of lymph nodes, and multiple intense FDG-avid of skeletal metastases. According to the appearance of FDG PET/CT, a provisional diagnosis of advanced cutaneous malignancy was made. Histopathology findings indicated characteristic of EMPD. The patient was treated with radiation therapy and died from complications 2 months after the last dose of radiotherapy.Our case highlighted that a whole-body FDG PET/CT should be incorporated into the diagnostic algorithm of EMPD to give a comprehensive assessment of this disease.     

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.     

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.     

Discordant findings of skeletal metastasis between tc 99M MDP bone scans and F18 FDG PET/CT imaging for advanced breast and lung cancers--two case reports and literature review

Traditionally, Tc 99m methyl diphosphate (MDP) bone scintigraphy provides high-sensitivity detection of skeletal metastasis from breast and lung cancers in regular follow-up. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), based on the glucose metabolism of malignant cells, plays a role in describing tumor growth, proliferation of neoplasm and the extent of metastasis. In general, concordant findings of skeletal metastasis are seen on both types of image, especially in cases of breast and lung cancer. However, there were extremely discordant findings of skeletal metastasis between bone scans and F 18 FDG PET/CT imaging in two cases among 300 consecutive F 18 FDG PET/CT follow-up exams of patients with malignancies, during the past year, in our center. Both cases, one of breast cancer and one of lung cancer, had negative bone scintigraphic findings, but a diffusely high grade of F 18 FDG avid marrow infiltration in the axial spine, leading to the diagnosis of stage IV disease in both cases. Owing to variant genetic aberrance of malignance, F 18 FDG PET/CT reveals direct evidence of diffuse, rapid neoplasm metabolism in the bone marrow of the spine, but not of secondary osteoblastic reactions in vivo . F 18 FDG PET/CT should always be employed in the follow-up of patients with malignancies.     

Guidelines for the use of imaging in the management of patients with myeloma

The role of imaging in myeloma has gained increasing importance over the past few years. The recently revised definition of myeloma from the International Myeloma Working Group (IMWG) includes cross sectional imaging as a method to define bone disease and also incorporates its use in the disease definition for patients with suspected smouldering myeloma. The National Institute for Health and Care Excellence myeloma guidelines also recommend cross sectional imaging for patients with suspected myeloma. There is also increasing use of imaging in disease assessments and the International Myeloma Working Group has recently incorporated imaging in defining new response categories of minimal residual disease negativity, with or without imaging‐based evidence of disease. Plain X‐rays have previously been the standard imaging modality included in a myeloma work up at presentation but evidence is mounting for use of cross‐sectional modalities such as computed tomography (CT), magnetic resonance imaging (MRI) and ¹⁸fluoro‐deoxyglucose (¹⁸F‐FDG) positron emission tomography (PET)/CT. Funding and therefore availability of newer imaging techniques remains a barrier. Here, we propose an evidence‐based approach to the use and technical application of the latest imaging modalities at diagnosis and in the follow‐up of patients with myeloma and plasmacytoma.     

Role of imaging in multiple myeloma

With rapid advancements in the diagnosis and treatment of multiple myeloma (MM), imaging has become instrumental in detection of intramedullary and extramedullary disease, providing prognostic information, and assessing therapeutic efficacy. Whole-body low dose computed tomography (WBLDCT) has emerged as the study of choice to detect osteolytic bone disease. Positron emission tomography/computed tomography (PET/CT) combines functional and morphologic information to identify MM disease activity and assess treatment response. Magnetic resonance imaging (MRI) has excellent soft-tissue contrast and is the modality of choice for bone marrow evaluation. This review focuses on the imaging modalities available for MM patient management, highlighting advantages, disadvantages, and applications of each.     

FDG-positron emission tomography (PET) has a role to play in the diagnosis and therapy of infective endocarditis and cardiac device infection

In recent years, molecular imaging with positron emission tomography (PET) and more recently, PET coupled with computed tomography (CT) have made a valuable impact in various clinical arenas, primarily within the field of oncology, but also in cardiovascular medicine, particularly in detecting coronary artery disease and myocardial viability. More recently, PET imaging has been proven useful in the diagnosis and evaluation of inflammation and infection at different organ sites. Application of PET in the case of Infective Endocarditis (IE) is still in its infancy and indeed the value of this application in the detection of vegetations is debated primarily due to sensitivity issues of the tracer in cardiac tissue and small vegetations. Interestingly, however, reports are now emerging highlighting the role that this application has played in the diagnosis, assessment of complications such as emboli and metastatic infection and the monitoring of therapeutic treatment of IE. More recently, PET/CT has proven valuable in the diagnosis and assessment of cardiac implantable electronic device (CIED)-related infection and its use has highlighted the contribution that this imaging modality may play in assessing the need for surgery in patients with such infections. This article reviews the literature with regard to the potential value of 2-deoxy-2-[¹⁸F]fluoro-D-glucose (¹⁸FDG)-PET, as well as the pitfalls and limitations of this imaging modality, in relation to cardiac infection. The emerging role ¹⁸FDG-PET/CT has in the diagnosis and monitoring of IE, particularly prosthetic valve IE and CIED-related infections should be considered, particularly in difficult cases.     

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.     

Utility of interim and end‐of‐treatment PET/CT in peripheral T‐cell lymphomas: A review of 124 patients

According to the updated guidelines for imaging in lymphoma, 18F‐FDG positron emission tomography/computed tomography (PET/CT) is recommended for staging and evaluation of treatment response in FDG‐avid lymphomas. The purpose of the study was to evaluate the utility of PET/CT in nodal peripheral T‐cell lymphomas (PTCL). Patients with newly diagnosed nodal PTCL (peripheral T‐cell lymphoma NOS, anaplastic large‐cell lymphoma, or angioimmunoblastic T‐cell lymphoma) seen at five Danish hematology centers during the period 2006 to 2012 were included, if they had been pretherapeutically staged with PET/CT. Medical records were reviewed for baseline clinical and follow‐up information. Staging, interim (I‐PET), and end‐of‐treatment PET/CT (E‐PET) studies were centrally reviewed, and reported using the Deauville 5‐point score (DS). A total of 124 patients fulfilled the inclusion criteria. The median age was 58 years, and 88% received CHOP/CHOP‐like therapy. Five years PFS and OS of the study population was 36.8% (95% CI 27.3–46.4) and 49.7% (95% CI 38.9–59.6), respectively. The presence of PET/CT‐ascertained lung and/or liver involvement was associated with a worse outcome. The sensitivity of PET/CT for detecting biopsy‐defined bone marrow involvement was only 18% (95% CI 4–43). An interim DS >3 was not prognostic for worse OS and PFS among CHOP/CHOP‐like treated patients in uni‐ or multivariate analyses. A DS >3 after treatment predicted a worse prognosis. In conclusion, I‐PET was not predictive of outcome in CHOP/CHOP‐like treated PTCL patients when using the DS. Prospective studies are needed to determine the optimal use of PET/CT in PTCL including the role of quantitative PET/CT analysis. Am. J. Hematol. 90:975–980, 2015. © 2015 Wiley Periodicals, Inc.     

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.     

(18)F-deoxyglucose PET: useful in the management of patients with stem cell transplantation for lymphoma?

(18)F-deoxyglucose (FDG) positron emission tomography (PET) and more recently FDG PET/computed tomography (CT) has become an important tool in the management of patients with Hodgkin and non-Hodgkin lymphoma. It adds metabolic and functional information to conventional anatomical imaging, mainly assessed by CT. Especially for the detection of early response to treatment and prognostic considerations, this type of information seems better suited than anatomical information. Consequently, the ability of FDG PET to predict the outcome in patients with stem cell transplantation (SCT) for lymphoma has been tested in several studies. Results in patients with autologous SCT have been promising, and pretransplant FDG PET is likely to become routine in this group of patients. The evaluated study investigates, for the first time, the predictive value of pretransplant FDG PET in allogeneic SCT, as well as the utility of FDG PET for the follow-up of these patients. All 80 patients included in the prospective study had reduced-intensity conditioning. In contrast to FDG PET before autologous SCT, there was no correlation at all between pretransplant FDG PET results and the outcome after allogeneic SCT. This reflects the fact that other or additional reasons, especially the graft-versus-leukemia effect, are substantial for the outcome of allogeneic SCT in comparison with autologous SCT. Follow-up with FDG PET after reduced-intensity allogeneic SCT was significantly more sensitive than CT to detect disease progression or relapse, and was useful in guiding treatment in the situation of disease relapse.