Safety and Efficacy of 68Ga-DOTATATE PET/CT for Diagnosis, Staging, and Treatment Management of Neuroendocrine Tumors.

UNLABELLED: Our purpose was to evaluate the safety and efficacy of (68)Ga-DOTATATE PET/CT compared with (111)In-pentetreotide imaging for diagnosis, staging, and restaging of pulmonary and gastroenteropancreatic neuroendocrine tumors. METHODS: (68)Ga-DOTATATE PET/CT and (111)In-pentetreotide scans were obtained for 78 of 97 consecutively enrolled patients with known or suspected pulmonary or gastroenteropancreatic neuroendocrine tumors. Safety and toxicity were measured by comparing vital signs, serum chemistry values, or acquisition-related medical complications before and after (68)Ga-DOTATATE injection. Added value was determined by changes in treatment plan when (68)Ga-DOTATATE PET/CT results were added to all prior imaging, including (111)In-pentetreotide. Interobserver reproducibility of (68)Ga-DOTATATE PET/CT scan interpretation was measured between blinded and nonblinded interpreters. RESULTS: (68)Ga-DOTATATE PET/CT and (111)In-pentetreotide scans were significantly different in impact on treatment (P < 0.001). (68)Ga-DOTATATE PET/CT combined with CT or liver MRI changed care in 28 of 78 (36%) patients. Interobserver agreement between blinded and nonblinded interpreters was high. No participant had a trial-related event requiring treatment. Mild, transient events were tachycardia in 1, alanine transaminase elevation in 1, and hyperglycemia in 2 participants. No clinically significant arrhythmias occurred. (68)Ga-DOTATATE PET/CT correctly identified 3 patients for peptide-receptor radiotherapy incorrectly classified by (111)In-pentetreotide. CONCLUSION: (68)Ga-DOTATATE PET/CT was equivalent or superior to (111)In-pentetreotide imaging in all 78 patients. No adverse events requiring treatment were observed. (68)Ga-DOTATATE PET/CT changed treatment in 36% of participants. Given the lack of significant toxicity, lower radiation exposure, and improved accuracy compared with (111)In-pentetreotide, (68)Ga-DOTATATE imaging should be used instead of (111)In-pentetreotide imaging where available.

Prone Versus Supine Breast FDG-PET/CT for Assessing Locoregional Disease Distribution in Locally Advanced Breast Cancer.

RATIONALE AND OBJECTIVES: Prone (18)F fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may have advantages for breast imaging because of improved separation of deep anatomic structures. There are limited data on whether prone and supine FDG-PET/CT provide similar information regarding breast and axillary disease in the setting of locally advanced breast cancer (LABC). The purpose of this study was to compare the information on locoregional disease distribution provided by prone versus supine FDG-PET in newly diagnosed LABC. MATERIALS AND METHODS: In an Institutional Review Board-approved prospective trial, 24 patients with newly diagnosed LABC underwent both supine and prone FDG-PET/CT at the same scanning session. Three readers performed an independent review of all scans and categorized the locoregional disease distribution as breast only (BO)-unifocal, BO-multifocal, BO-multicentric, or breast + axillary involvement. For breast + axillary disease, the readers also assessed the number of involved axillary lymph nodes. Interobserver discrepancies were resolved at a consensus reading session. RESULTS: Two scanning sessions were excluded because the prone scan had omitted part of the axilla from the field of view. In the remaining 22 patients, the consensus categorization of anatomic disease distribution was concordant between prone and supine scanning in 21 patients (linear kappa 0.91, 95% confidence interval [0.79-1]). In the 16 patients with breast + axillary disease, equal numbers of involved lymph nodes were identified on prone and supine scanning in 12 patients, whereas in the remaining four patients, prone scanning resulted in a higher number of visualized lymph nodes. CONCLUSIONS: Prone and supine FDG-PET/CT provided statistically identical information on locoregional disease distribution in LABC. However, prone scanning may perform better than supine for assessing the number of involved lymph nodes. Prone FDG-PET/CT may be useful in future clinical and research efforts, including hybrid PET-magnetic resonance imaging (MRI) applications.

Imaging of multiple myeloma and related plasma cell dyscrasias.

Multiple myeloma (MM) is an incurable plasma cell malignancy of the bone marrow. MM has 3 components: diffuse marrow infiltration, focal bone lesions, and soft-tissue (extramedullary) disease. The hallmark biomarker in blood or urine is a monoclonal immunoglobulin, the monoclonal protein. Waldenstrom macroglobulinemia is a similar disease with secretion of IgM. Staging is classically performed with the 1975 Durie-Salmon system, which includes conventional radiographs. Recently updated, the Durie-Salmon Plus staging system includes CT, MRI, and (18)F-FDG PET/CT. The hallmark radiographic lesion of symptomatic MM is a well-demarcated, focal osteolytic bone lesion. The number of focal bone lesions correlates inversely with outcome. Extramedullary disease is typically an aggressive, poorly differentiated form of MM that confers inferior outcome, with median survival of less than 1 y if present at diagnosis. Achievement of a complete response on (18)F-FDG PET before stem-cell transplantation correlates with a superior outcome.

New imaging tools for the diagnosis of infection.

Infection imaging became widespread in 1971 with the release of 67Ga citrate. Multiphase skeletal scintigraphy and radiolabeled white blood cells (WBCs) have since become the most widespread clinically used agents for the imaging of infection. A wide variety of other radiolabeled probes are under investigation, based on antibodies, cytokines, assorted proteins and other molecules, alone or in various combinations. However, these latter agents, with a few exceptions, are not routinely used clinically. Radiolabeled ciprofloxacin represents the first attempt to develop an infection-specific imaging agent (most infection-imaging probes localized nonspecifically to inflammation as well), but it has not proven superior to radiolabeled WBCs or 18F-fluoro-deoxy-glucose (FDG) PET. Because of the ability to combine exquisite anatomic detail with focal uptake of 18F-FDG, PET-computed tomography has achieved great success in the detection and localization of infection, including in clinically adverse conditions. Despite these advances, at this time an infection-specific imaging agent does not exist.

Diagnosis of infection of implantable central venous catheters by [18F]fluorodeoxyglucose positron emission tomography.

OBJECTIVE: The aim of this study was to evaluate the role of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging in the diagnosis of infection of implantable vascular catheters. METHODS: We evaluated six patients with haematological cancer and infection of their implantable vascular catheter and who underwent FDG PET imaging around the time of their infection. RESULTS: Six patients with multiple myeloma who developed infection of their implantable device (five port pocket infections and one tunnel infection) were identified. FDG PET revealed increased uptake at the site of the implantable catheter (SUV 2.7-4.5) in all six patients, even in the absence of signs or symptoms of infection at the site of the device (three), and the presence of severe neutropenia (four). The three patients who did not have local inflammation at the site of the device were profoundly neutropenic. The FDG PET diagnosis led to removal of the device in two patients. CONCLUSION: FDG PET is a safe, rapid and accurate tool for diagnosing infection of an implantable catheter, including among those patients not exhibiting local signs and symptoms of infection, and in whom the diagnosis of infected device may be difficult. FDG PET may help prevent the unnecessary removal of implantable intravascular catheters and the unwarranted use of antibiotics.

Introduction to PET imaging with emphasis on biomedical research.

Medical imaging is migrating from anatomic imaging to functional imaging and fused anatomic/functional imaging. The technology is being adapted for biomedical research using both clinical and small animal scanners. The ability to externally image real-time physiologic processes in both normal and deranged conditions, including various models to image gene expression, apoptosis, or drug biodistribution, has powerful impact on the exploration of biomedical and fundamental biological research. Positron emission tomography (PET) has a unique ability to not only provide such images but also to do so with high resolution (typically 1-2mm resolution for small animal scanners) and to provide both relative and absolute quantitation. This technology is revolutionizing biomedical and biological research. This article reviews the underlying principles involved in this technology, gives a brief history of its development, and then introduces the interested researcher to some of the important techniques that could be of use.