Fabio M. Paes

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.

Perineural Spread in Head and Neck Malignancies: Clinical Significance and Evaluation with 18F-FDG PET/CT

Certain tumors of the head and neck use peripheral nerves as a direct conduit for tumor growth away from the primary site by a process known as perineural spread. Perineural spread is associated with decreased survival and a higher risk of local recurrence and metastasis. Radiologists play an important role in the assessment and management of head and neck cancer, and positron emission tomography/computed tomography (PET/CT) with 2-[fluorine 18]fluoro-2-deoxy-d-glucose (FDG) is part of the work-up and follow-up of many affected patients. Awareness of abnormal FDG uptake patterns within the head and neck is fundamental for diagnosing perineural spread. The cranial nerves most commonly affected by perineural spread are the trigeminal and facial nerves. Risk of perineural spread increases with a midface location of the tumor, male gender, increasing tumor size, recurrence after treatment, and poor histologic differentiation. Focal or linear increased FDG uptake along the V2 division of the trigeminal nerve or along the medial surface of the mandible, or asymmetric activity in the masticator space, foramen ovale, or Meckel cave should raise suspicion for perineural spread. If FDG PET/CT findings suggest perineural spread, the radiologist should look at available results of other imaging studies, especially magnetic resonance imaging, to confirm the diagnosis. Knowledge of common FDG PET/CT patterns of neoplastic involvement along the cranial nerves and potential diagnostic pitfalls is of the utmost importance for adequate staging and treatment planning.

Utility of positron emission tomography scans in mantle cell lymphoma

Positron emission tomography (PET) scans are widely used in patients with lymphoma but little is known about their utility in mantle cell lymphoma (MCL). MCL patients were included from two prospective trials and one observational study at our institution. A total of 276 PET scans were performed among 52 patients. After a median follow‐up of 37.5 months, the 3‐year event‐free survival (EFS) and overall survival (OS) were 73% (95% confidence interval [CI]: 61–85%) and 92% (95% CI 85–100%), respectively. There were 34 pretreatment PET scans, 26 interim, 28 end‐of‐treatment, 162 surveillance, and 26 scans at relapse or beyond. Pretreatment PETs were positive in 94%. A negative interim or end‐of‐therapy PET scan was not significantly associated with better EFS or OS, but no deaths were observed in patients who had a negative interim or end‐of‐therapy PET. Surveillance PET scans had a high false positive rate (35%) and low positive predictive value (8%). PET scans contributed to an earlier diagnosis of relapse in only two out of the 18 patients (11%) who relapsed. PET scans did not meaningfully contribute to staging or surveillance of MCL patients in this study. There was a trend toward improved survival in patients who had a negative end‐of‐therapy PET scan. Am. J. Hematol., 2011.

Radiopharmaceuticals: When and How to Use Them to Treat Metastatic Bone Pain

Bone pain due to skeletal metastases constitutes the most common type of cancer-related pain. The management of bone pain remains challenging and is not standardized. In patients with multifocal osteoblastic metastases, systemic radiopharmaceuticals should be the preferred adjunctive therapy for pain palliation. The lack of general knowledge about radiopharmaceuticals, their clinical utility and safety profiles, constitutes the major cause for their underutilization. Our goal is to review the indications, selection criteria, efficacy, and toxicities of two approved radiopharmaceuticals for bone pain palliation: strontium-89 and samarium-153. Finally, a brief review of the data on combination therapy with bisphosphonates or chemotherapy is included.

[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.

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.

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.