Patrick J. Peller

Clinical Significance of Diffusely Increased 18F-FDG Uptake in the Thyroid Gland

Our purpose was to determine the clinical significance of diffusely increased 18F-FDG uptake in the thyroid gland as an incidental finding on PET/CT. Methods: All patients who were found to have diffuse thyroid uptake on 18F-FDG PET/CT in our institution between November 2004 and June 2006 were investigated and compared with an age- and sex-matched control group. The 18F-FDG uptake in the thyroid was semiquantified using maximum standardized uptake value and correlated to the available serum thyroid-stimulating hormone (TSH) and thyroid peroxidase (TPO) antibody levels using regression analysis. Results: Of the 4,732 patients, 138 (2.9%) had diffuse thyroid uptake. Clinical information was available for 133 of the 138 patients. Sixty-three (47.4%) had a prior diagnosis of hypothyroidism or autoimmune thyroiditis, of whom 56 were receiving thyroxine therapy. In the control group, consisting of 133 patients with no thyroid uptake, there were 13 (9.8%) with a prior diagnosis of hypothyroidism, 11 of whom were receiving thyroxine therapy. In the study group, 38 (28.6%) of 133 patients did not undergo any further investigation for thyroid disease, whereas 32 (24.1%) of 133 patients were examined for thyroid disease after PET. Nineteen were found with autoimmune thyroiditis or hypothyroidism, and replacement therapy was initiated in 12. No significant correlation was found between maximum standardized uptake value and TSH (P = 0.09) or TPO antibody (P = 0.68) levels. Conclusion: The incidental finding of increased 18F-FDG uptake in the thyroid gland is associated with chronic lymphocytic (Hashimotos) thyroiditis and does not seem to be affected by thyroid hormone therapy. SUV correlated neither with the degree of hypothyroidism nor with the titer of TPO antibodies.

PET/CT of Cancer Patients: Part 1, Pancreatic Neoplasms

OBJECTIVE Pancreatic cancer continues to have a poor prognosis despite impressive improvements in the outcomes of many other types of cancer, often because most pancreatic neoplasms are found to be unresectable at diagnosis. The purpose of this review is to provide an overview of pancreatic cancer and the role of modern imaging in its diagnosis and management with an emphasis on (18)F-FDG PET/CT fusion imaging. CONCLUSION Multimodality imaging is critical in the diagnosis and management of pancreatic cancer. PET/CT is increasingly viewed as a useful, accurate, and cost-effective modality in diagnosing and managing pancreatic cancer, but further studies are warranted. Early data suggest that contrast-enhanced PET/CT performed with modern PET/CT scanners yields high-resolution anatomic information for surgical and radiotherapeutic planning and functional information for whole-body staging in the care of patients with this disease.

Fluorodeoxyglucose–Positron-Emission Tomography Imaging of Head and Neck Squamous Cell Cancer

SUMMARY: The hybrid technique of PET/CT has significantly impacted the imaging and management of HNSCC since its introduction in 2001 and has become the technique of choice for imaging of this cancer. Diagnostic FDG-PET/CT is useful for identification of an unknown primary tumor, delineation of extent of primary tumor, detection of regional lymph node involvement even in a normal-sized node, detection of distant metastases and occasional synchronous primary tumor, assessment of therapy response, and long-term surveillance for recurrence and metastases. The role of PET/CT is evolving in radiation therapy planning. Combined diagnostic PET/CT provides the best anatomic and metabolic in vivo information for the comprehensive management of HNSCC.

Fluorodeoxyglucose F18 Positron Emission Tomography in Progressive Apraxia of Speech and Primary Progressive Aphasia Variants

OBJECTIVES To determine patterns of hypometabolism on fluorodeoxyglucose F18 positron emission tomography (FDG-PET) in patients with progressive apraxia of speech (PAS) and primary progressive aphasia (PPA) variants and to use these patterns to further refine current classification. DESIGN We identified all patients who had FDG-PET and PAS or PPA who were evaluated by an expert speech-language pathologist. Patterns of hypometabolism were independently classified by 2 raters blinded to clinical data. Three speech-language pathologists reclassified all patients into 1 of 7 operationally defined categories of PAS and PPA blinded to FDG-PET data. SETTING Tertiary care medical center. PATIENTS Twenty-four patients with PAS or PPA and FDG-PET. MAIN OUTCOME MEASURE Fluorodeoxyglucose F18 PET hypometabolic pattern. RESULTS Of the 24 patients in the study, 9 had nonfluent speech output; 14, fluent speech; and 1 was unclassifiable. Twenty-one patients showed FDG hypometabolism; the remaining 3 did not. Among the patients showing hypometabolism, 8 had a prerolandic pattern of which 7 had nonfluent speech including progressive nonfluent aphasia (n = 3), PAS (n = 1), and mixed nonfluent aphasia/apraxia of speech (n = 3); the other patient had PPA unclassifiable. The remaining 13 had a postrolandic pattern, all with fluent speech (P < .001), including logopenic progressive aphasia (n = 6), progressive fluent aphasia (n = 6), and semantic dementia (n = 1). Patterns of hypometabolism differed between the nonfluent variants and between the fluent variants, including progressive fluent aphasia. CONCLUSION Patterns of FDG-PET hypometabolism support the clinical categorizations of fluency, the distinction of apraxia of speech from progressive nonfluent aphasia, and the designation of a progressive fluent aphasia category.

North Central Cancer Treatment Group Phase I Trial N057K of Everolimus (RAD001) and Temozolomide in Combination With Radiation Therapy in Patients With Newly Diagnosed Glioblastoma Multiforme

BACKGROUND The mammalian target of rapamycin (mTOR) functions within the PI3K/Akt signaling pathway as a critical modulator of cell survival. On the basis of promising preclinical data, the safety and tolerability of therapy with the mTOR inhibitor RAD001 in combination with radiation (RT) and temozolomide (TMZ) was evaluated in this Phase I study. METHODS AND MATERIALS All patients received weekly oral RAD001 in combination with standard chemoradiotherapy, followed by RAD001 in combination with standard adjuvant temozolomide. RAD001 was dose escalated in cohorts of 6 patients. Dose-limiting toxicities were defined during RAD001 combination therapy with TMZ/RT. RESULTS Eighteen patients were enrolled, with a median follow-up of 8.4 months. Combined therapy was well tolerated at all dose levels, with 1 patient on each dose level experiencing a dose-limiting toxicity: Grade 3 fatigue, Grade 4 hematologic toxicity, and Grade 4 liver dysfunction. Throughout therapy, there were no Grade 5 events, 3 patients experienced Grade 4 toxicities, and 6 patients had Grade 3 toxicities attributable to treatment. On the basis of these results, the recommended Phase II dosage currently being tested is RAD001 70 mg/week in combination with standard chemoradiotherapy. Fluorodeoxyglucose (FDG) positron emission tomography scans also were obtained at baseline and after the second RAD001 dose before the initiation of TMZ/RT; the change in FDG uptake between scans was calculated for each patient. Fourteen patients had stable metabolic disease, and 4 patients had a partial metabolic response. CONCLUSIONS RAD001 in combination with RT/TMZ and adjuvant TMZ was reasonably well tolerated. Changes in tumor metabolism can be detected by FDG positron emission tomography in a subset of patients within days of initiating RAD001 therapy.

The Utility of 11C-Choline PET/CT for Imaging Prostate Cancer: A Pictorial Guide

OBJECTIVE The objective of this article is to provide an illustrative tutorial showing the utility of (11)C-choline PET/CT for imaging prostate cancer. CONCLUSION Carbon-11-labeled choline PET/CT is a powerful adjunct to the currently available imaging modalities for evaluating prostate cancer. As with any diagnostic method, false-positives and false-negatives occur. However, these diagnostic errors can be reduced if readers are familiar with the normal and abnormal patterns of (11)C-choline distribution in the body.

The Value of [18F]Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Extranodal Natural Killer/T—Cell Lymphoma

PURPOSE To our knowledge, there are no published data pertinent to the use of [(18F)]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with natural killer (NK)/T-cell lymphoma. The purpose of this study was to assess the value of FDG PET/CT in this aggressive type of non-Hodgkin lymphoma. PATIENTS AND METHODS All patients with NK/T-cell lymphoma referred for FDG PET/CT at our institution from July 2001 to July 2006 were retrospectively studied. PET/CT examinations were blindly reviewed by 2 experienced readers. The results were compared with the status of the disease, which was determined after evaluation of biopsy, laboratory, clinical and conventional imaging examination, and follow-up results. PET/CT results were thereby classified as true-positive, true-negative, false-positive, or false-negative. The degree of FDG uptake in the positive lesions was semiquantified using maximum standard uptake value (SUV(max)). RESULTS Twenty-one PET/CT examinations were performed in 10 patients with NK/T-cell lymphoma. For nasal disease, PET/CT was true-positive in 5 cases, true-negative in 15 cases, and positive but unconfirmed in 1 case. For extranasal disease, PET/CT was true-positive in 3 cases, true-negative in 16 cases, and false-negative in 2 cases. The mean SUV(max) in PET-positive lesions in nasal cavities or paranasal sinuses was 16 gm/mL (range, 5-25 gm/mL; median, 19.3 gm/mL). In extranasal disease, the mean SUV(max) was 10.9 gm/mL (range, 4.6-34.1 gm/mL; median, 5.6 gm/mL). CONCLUSION Viable NK/T-cell lymphoma is intensely FDG hypermetabolic. PET/CT appears to be sensitive for the detection of disease in the nasopharynx and, to a lesser extent, in extranasal sites.

Utility of Integrated Computed Tomography—Positron Emission Tomography for Selection of Operable Malignant Pleural Mesothelioma

BACKGROUND Malignant pleural mesothelioma (MPM) is a primary malignancy characterized by local invasion of the pleura and metastasis. Despite advances in computed tomography (CT) and magnetic resonance imaging (MRI), accurately staging patients remains challenging. Recent studies have examined the use of integrated CT-positron emission tomography (PET) for staging patients. MATERIALS AND METHODS Mayo Clinic databases were queried to identify cases with a histologic diagnosis of MPM from 2000 to 2006. Inclusion criteria were a diagnosis of MPM, an available CT scan, and an initial staging integrated CT-PET scan. A total of 35 patients were identified who met the inclusion criteria. Computed tomography and integrated CT-PET scans were reviewed by experienced radiologists. Laboratory parameters were reviewed. The Mayo Clinic tumor registry and Social Security database were queried for survival data in patients in which no follow-up was available. RESULTS Findings on integrated CT-PET excluded 14 of 35 patients from surgical intervention. Extrapleural pneumonectomies (EPPs) were performed in 8 patients, and partial pleurectomies were performed in 2 patients. Upstaging from integrated CT-PET occurred in 70% of the patients when surgical pathology was available, 2 cases to an inoperable stage. Although not statistically significant, median survival was 20 months for patients undergoing an EPP and 12 months for patients excluded from surgical intervention by integrated CT-PET. CONCLUSION Malignant pleural mesothelioma is a difficult disease to accurately stage. The most common reason for upstaging in our series was an increase in T (tumor; tumor-node-metastasis staging system) disease. Our data suggest that integrated CT-PET is excellent for detecting nodal and distant metastases. However, the ability of this imaging modality to correctly stage locoregional disease is not superior to the combination of CT and MRI as reported in the literature.

FDG PET/CT in patients with HIV.

OBJECTIVE This article will discuss the (18)F-FDG normal variant uptake and the role of FDG PET/CT in malignancies in HIV-infected patients, CNS manifestations of HIV, assessing fever of unknown origin in HIV patients, assessing response to highly active antiretroviral therapy and assessing complications. CONCLUSION FDG PET/CT is a valuable imaging study in the management of HIV-infected patients.

Application of the National Institute on Aging–Alzheimer’s Association AD criteria to ADNI

Objective: We describe the operationalization of the National Institute on Aging–Alzheimer’s Association (NIA-AA) workgroup diagnostic guidelines pertaining to Alzheimer disease (AD) dementia in a large multicenter group of subjects with AD dementia. Methods: Subjects with AD dementia from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) with at least 1 amyloid biomarker (n = 211) were included in this report. Biomarker data from CSF Aβ42, amyloid PET, fluorodeoxyglucose-PET, and MRI were examined. The biomarker results were assessed on a per-patient basis and the subject categorization as defined in the NIA-AA workgroup guidelines was determined. Results: When using a requirement that subjects have a positive amyloid biomarker and single neuronal injury marker having an AD pattern, 87% (48% for both neuronal injury biomarkers) of the subjects could be categorized as “high probability” for AD. Amyloid status of the combined Pittsburgh compound B–PET and CSF results showed an amyloid-negative rate of 10% in the AD group. In the ADNI AD group, 5 of 92 subjects fit the category “dementia unlikely due to AD” when at least one neuronal injury marker was negative. Conclusions: A large proportion of subjects with AD dementia in ADNI may be categorized more definitively as high-probability AD using the proposed biomarker scheme in the NIA-AA criteria. A minority of subjects may be excluded from the diagnosis of AD by using biomarkers in clinically categorized AD subjects. In a well-defined AD dementia population, significant biomarker inconsistency can be seen on a per-patient basis.