Dimitrios Kalkanis

FDG PET/CT of Extranodal Involvement in Non-Hodgkin Lymphoma and Hodgkin Disease

The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the lymph nodes. Almost any organ can be affected by lymphoma, with the most common extranodal sites of involvement being the stomach, spleen, Waldeyer ring, central nervous system, lung, bone, and skin. The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease has increased in the past decade. The imaging characteristics of extranodal involvement can be subtle or absent at conventional computed tomography (CT). Imaging of tumor metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) has facilitated the identification of affected extranodal sites, even when CT has demonstrated no lesions. More recently, hybrid PET/CT has become the standard imaging modality for initial staging, follow-up, and treatment response assessment in patients with lymphoma and has proved superior to CT in these settings. Certain PET/CT patterns are suggestive of extranodal disease and can help differentiate tumor from normal physiologic FDG activity, particularly in the mucosal tissues, bone marrow, and organs of the gastrointestinal tract. Familiarity with the different extranodal manifestations in various locations is critical for correct image interpretation. In addition, a knowledge of the differences in FDG avidity among the histologic subtypes of lymphoma, appropriate timing of scanning after therapeutic interventions, and use of techniques to prevent brown fat uptake are essential for providing the oncologist with accurate information.

[18F]-fluorodeoxyglucose positron emission tomography combined with computed tomography detection of asymptomatic late pulmonary toxicity in patients with non-Hodgkin lymphoma treated with rituximab-containing chemotherapy.

Rituximab is a chimeric anti-CD20 monoclonal antibody widely used in the treatment of B-cell non-Hodgkin lymphomas (NHL). Most adverse effects are due to infusion-related reactions, and severe respiratory complications are rare. We retrospectively reviewed clinical data and serial imaging studies of five patients with NHL treated with rituximab-containing chemotherapy who developed new pulmonary abnormalities on routine follow-up FDG-PET/CT imaging. None of the patients had pulmonary lymphoma or other pulmonary disease before therapy and all remained asymptomatic during follow-up. New pulmonary interstitial FDG-uptake was detected on follow-up FDG-PET/CT between 1 and 3 months post-treatment, preceded computed tomography abnormalities in one case, and persisted for several months. FDG uptake was linear, subpleural with maximum Standardized uptake value (SUV) from 2.0 to 5.84. Rituximab-containing chemotherapy for NHL may be associated with asymptomatic late pulmonary toxicity characterised by a distinct FDG uptake pattern. Awareness of this finding is important and should not be confused with lymphoma.

Oncologic 18F-FDG PET/CT: Referring Physicians’ Point of View

Oncologic 18F-FDG PET/CT is rapidly gaining acceptance in clinical practice. However, the referring physician’s attitude toward the usefulness of this diagnostic modality is unknown. This survey was undertaken to collect information regarding the current perspective of referring physicians on oncologic PET/CT. Methods: We conducted a prospective worldwide, Web-based survey of physicians who manage cancer patients. A total of 963 referring physicians completed a 20-question survey focused on their experience with oncologic 18F-FDG PET/CT. Attention was directed toward their confidence about indications, their satisfaction with related educational resources, the quality of interaction with interpreting physicians, and practical problems encountered. The respondents included oncologists (38.5%, n = 371), hematologists (16.4%, n = 158), radiation oncologists (9.0%, n = 87), surgeons (30.3%, n = 292), and other physicians (5.7%, n = 55). Results: Only 25.2% of respondents considered the oncologic 18F-FDG PET/CT indications to be well established and defined. Frequent uncertainty about the need for a PET scan was indicated by 62.3% of the respondents. High cost and overinterpretation of findings were the most commonly reported concerns (47.0% and 40.9%, respectively). The experience and skill level of the interpreting physician was considered very important by 96.8% of the surveyed physicians. Conclusion: Referring physicians expressed considerable uncertainty about the appropriate use of oncologic PET/CT. Additional major concerns are procedure costs and quality of interpretation. The responses suggest a strong need for efforts to educate referring and interpreting physicians about the appropriate use of 18F-FDG PET/CT in oncology.

Perceived Misinterpretation Rates in Oncologic 18F-FDG PET/CT Studies: A Survey of Referring Physicians

Because only pathologic examination can confirm the presence or absence of malignant disease in cancer patients, a certain rate of misinterpretation in any kind of imaging study is inevitable. For the accuracy of interpretation to be improved, determination of the nature, causes, and magnitude of this problem is needed. This study was designed to collect pertinent information from physicians referring patients for oncologic 18F-FDG PET/CT. Methods: A total of 662 referring physicians completed an 11-question survey focused on their experience with the interpretation of oncologic 18F-FDG PET/CT studies. The participants were oncologists (36.1%; n = 239), hematologists (14.5%; n = 96), radiation oncologists (7.4%; n = 49), surgeons (33.8%; n = 224), and other physicians (8.2%; n = 54). Questions were aimed at determining the frequency, nature, and causes of scan misinterpretations as well as potential solutions to reduce the frequency of misinterpretations. Results: Perceived misinterpretation rates ranged from 5% to 20%, according to most (59.3%) of the participants; 20.8% of respondents reported rates of less than 5%. Overinterpretation rather than underinterpretation was more frequently encountered (68.9% vs. 8.7%, respectively). Limited availability of a patient’s history and limited experience of interpreters were the major contributors to this phenomenon, according to 46.8% and 26.7% of the participants, respectively. The actions most commonly suggested to reduce misinterpretation rates (multiple suggestions were possible) were the institution of multidisciplinary meetings (59.8%), the provision of adequate history when ordering an examination (37.4%), and a discussion with imaging specialists when receiving the results of the examination (38.4%). Conclusion: Overinterpretation rather than underinterpretation of oncologic 18F-FDG PET/CT studies prevails in clinical practice, according to referring physicians. Closer collaboration of imaging specialists with referring physicians through more multidisciplinary meetings, improved communication, and targeted training of interpreting physicians are actions suggested to reduce the rates of misinterpretation of oncologic 18F-FDG PET/CT studies.

A Clear Cell Tumor of the Lung Presenting as a Rapidly Growing Coin Lesion: Is It Really a Benign Tumor?

There are few reported cases of clear cell tumor of the lung, a very rare benign mesenchymal neoplasm. We describe a 41-year-old asymptomatic man who presented with a coin lesion in a routine chest roentgenogram that was absent in a roentgenogram performed a year earlier. After a thorough workup, including radionuclide scintigraphy, the diagnosis of cell tumor of the lung was established. Somatostatin receptor positivity was demonstrated, and this clear cell tumor of the lung had a rapid growth rate. Because of these features, the benign nature of such a tumor remains questionable.

FDG-PET/CT in primary large B-Cell lymphoma of the hard palate

Abstract: An immunocompetent 78-year-old man with a remote history of Hodgkin disease was found to have a protrusion in the hard palate during routine dental care. F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) combined with computed tomography (CT) was performed and demonstrated an intense hypermetabolic focus in the hard palate. Surgical biopsy of the lesion and further work-up with CT scans of the chest, abdomen, and pelvis were performed. The histopathology and immunohistochemistry findings were consistent with primary extranodal large B-cell lymphoma of the hard palate.

Correlation of spleen metabolism assessed by 18F-FDG PET with serum interleukin-2 receptor levels and other biomarkers in patients with untreated sarcoidosis.

BackgroundThe objective of our study was to assess the possible relationship between splenic F-18-fluorodeoxyglucose (18F-FDG) uptake and other established biochemical markers of sarcoidosis activity. Patients and methodsThirty treatment-naive sarcoidosis patients were prospectively enrolled in this study. They underwent biochemical laboratory tests, including serum interleukin-2 receptor (sIL-2R), serum C-reactive protein, serum angiotensin-I converting enzyme, and 24-h urine calcium levels, and a whole-body combined 18F-FDG PET/computed tomography (PET/CT) scan as a part of an ongoing study at our institute. These biomarkers were statistically compared in these patients. ResultsA statistically significant linear dependence was detected between sIL-2R and log-transformed spleen-average standard uptake value (SUVavg) (R2=0.488, P<0.0001) and log-transformed spleen-maximum standard uptake value (SUVmax) (R2=0.490, P<0.0001). sIL-2R levels and splenic size correlated linearly (Pearson’s r=0.373, P=0.042). Multivariate linear regression analysis revealed that this correlation remained significant after age and sex adjustment (&bgr;=0.001, SE=0.001, P=0.024). No statistically significant associations were detected between (a) any two serum biomarkers or (b) between spleen-SUV measurements and any serum biomarker other than sIL-2R. ConclusionOur analysis revealed an association between sIL-2R levels and spleen 18F-FDG uptake and size, whereas all other serum biomarkers were not significantly associated with each other or with PET 18F-FDG uptake. Our results suggest that splenic inflammation may be related to the systemic inflammatory response in sarcoidosis that may be associated with elevated sIL-2R levels.

F-18 Fdg Pet Positive Hilar and Mediastinal Lymphadenopathy Mimicking Metastatic Disease in a Melanoma Patient Treated With Interferon-alpha-2b

A 49-year-old man with a history of recurrent melanoma in the parotid was treated with parotidectomy, external beam radiation, and high-dose interferon-alpha-2b. Combined F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) performed for restaging demonstrated multiple bilateral hilar and mediastinal hypermetabolic foci corresponding to hilar and mediastinal lymphadenopathy. Cytologic specimens obtained by bronchoscopy were negative for malignancy, revealing reactive lymph nodes. Subsequent FDG PET/CT showed regression of the findings. Awareness of possible interferon-associated reaction in melanoma patients who undergo FDG PET is important to avoid pitfalls in the interpretation.

F-18 FDG PET/CT in the assessment of recurrent anaplastic T-cell lymphoma of the external auditory canal.

We report a case of pathologically proven recurrent cutaneous anaplastic T-cell lymphoma of the ear. The patient had been previously treated with local radiotherapy 3 years prior. Recently, the patient presented with worsening pain and swelling of the left external auditory meatus. The patient underwent a workup, which included clinical, radiologic, and pathologic correlation. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography confirmed metabolically active disease in the primary lesion and local lymph node involvement, which was subsequently proven to be recurrent anaplastic Tcell lymphoma.

18F-FDG PET/CT Imaging of Pulmonary Mucinous Cystadenocarcinoma with Signet Ring Cells

A 63-year-old male with a recently diagnosed right lung lesion was referred for staging. F-FDG PET/CT scan revealed a hypodense, cystic-like mass in the right upper lung lobe, which demonstrated low, diffuse 18F-FDG uptake, likely due to the presence of mucus, as well as intensely hypermetabolic right hilar and right paratracheal lymph nodes. Transbronchial biopsy revealed a primary pulmonary mucinous cystadenocarcinoma with the presence of signet ring cell carcinoma, a co-existence of two rare variants of lung adenocarcinoma. This case report demonstrates the metabolic phenotype along with the radiographic characteristics of this rare tumor and its metastases.