The human image represented an individual who had dermatomyositis a skin disease often associated with undiagnosed cancer. One-third of the cases of dermatomyositis occurring in older individuals are associated with an undiagnosed or a known underlying cancer. The patient in the Image of the Year received a whole body FDG PET scan even though he had no symptoms of cancer. The FDG-PET revealed a very active lesion in the lung, representing a lung cancer.
According to Dr. Peter Conti, who introduced the image at the Society of Nuclear Medicine briefing, it demonstrated the type of situation in which a screening PET might be appropriate--since PET is so valuable in the diagnosis of cancer.
The basic science Image of the Year showed a mouse who had a dopamine transporter gene introduced in one leg, and a control agent in another. The researchers were able to image the introduced gene using a high resolution SPECT camera and a radiotracer designed to bind to the dopamine transporter protein. Alternations in dopamine are known to play a role in Parkinson's disease.
The Society of Nuclear Medicine is an international scientific and professional organization with more than 13,000 members dedicated to promoting the science, technology, and practical applications of nuclear medicine. The SNM is based in Reston, VA. For more information visit the SNM website at www.snm.org.
Paraneoplastic Syndroms: Detection of Underlying Malignancy Using 18F-FDG-PET
Authors: U. Berner, C. Menzel, D. Rinne, N. Doebert, R. Kaufmann, F. Gruenwald,
Hospital of the Johann Wolfgang Goethe
University, Hospital, Frankfurt, Germany
Objectives: Paraneoplastic syndromes (PS) comprise a variety of clinical symptomes and diseases associated with underlying malignancy. Essential for patient management is a differentiation towards benign autoimmune diseases, that requires cost- and time-consuming diagnostic methods. The aim of this study was the evaluation of F-18-fluoro-deoxy-glucose positron emission tomography (F-18-FDG-PET) for screening of malignancies in these patients.
Methods: From 1996 to 2001 a total of 30 patients with suspected PS (m:f = 17:13, mean age 55, range 22-76 years) were investigated with F-18-FDG-PET. Diagnoses were cerebellar degeneration, erythrodermia, dermatomyositis, polneuropathia and others. PET-Scans were evaluated for convincing or suspicious signs of malignant metabolism and the results were compared to histopathologic (N=14), radiologic and follow up data (N=16).
Results: An underlying malignancy could be detected in 8 / 30 Patients (27%). F-18-FDG-PET found 7 out of 8 malignant neoplasms. There were also one benign neoplasm and two inflammatory diseases. The remaining patients did not demonstrate a malignancy neither in the performed diagnostic procederes nor in their clinical follow up.
Conclusion: The application of F-18-FDG-PET as a screening tool for the detection of malignancy in suspected paraneoplastic syndromes seems to be of reasonable value.
Quantification of Dopamine Transporters in the Mouse Brain Using Ultra-High Resolution Single Photon Emission Tomography
Authors:Paul D. Acton Ph.D., Alberto Auricchio M.D., Karl Plössl Ph.D., James M. Wilson M.D. Ph.D., Hank F. Kung Ph.D.
Department of Radiology and Institute for Human Gene Therapy
University of Pennsylvania Philadelphia, PA 19104
Objective: Functional imaging of small animals, such as mice and rats, using ultra-high resolution PET and SPECT is becoming a valuable tool for studying animal models of human disease. While several studies have shown the utility of PET imaging in small animals, few have used SPECT in real research applications. In this study we aim to demonstrate the feasibility of ultra-high resolution SPECT in quantitative studies of dopamine transporters (DAT) in the mouse brain.
Methods: Four healthy CD-1 male mice were injected with 704 +/- 154 MBq 99mTc-TRODAT-1, and scanned using an ultra-high resolution SPECT system equipped with pinhole collimators (spatial resolution 0.83 mm at 3 cm radius of rotation). Each mouse had two studies, to provide an indication of test-retest reliability. Reference tissue kinetic modeling analysis of the time-activity data in the striatum and cerebellum was used to quantitate the availability of DAT. A simple equilibrium ratio of striatum-to-cerebellum provided another measure of DAT binding. The SPECT imaging results were compared against ex-vivo biodistribution data from the striatum and cerebellum.
Results: The mean distribution volume ratio (DVR) from the reference tissue kinetic model was 2.17 +/- 0.34, with a test-retest reliability of 2.63 +/- 1.67 %. The ratio technique gave similar results (DVR = 2.03 +/- 0.38, test-retest = 6.64 +/- 3.86 %), and the ex-vivo analysis gave DVR = 2.32 +/- 0.20. Correlation between the kinetic model and the ratio technique (R2 = 0.86, p < 0.001) and the ex-vivo data (R2 = 0.92, p = 0.04) were both excellent.
Conclusion: This study has demonstrated clearly that ultra-high resolution SPECT of small animals is capable of accurate, repeatable and quantitative measures of DAT binding, and should open up the possibility of further studies of cerebral binding sites in mice using pinhole SPECT.