"The specificity of bone scintigraphy--or bone scanning--is enhanced by combining SPECT with spiral CT," explained Wolfgang Römer, assistant professor and vice chair of the Clinic of Nuclear Medicine at the University of Erlangen/Nuremberg in Germany. "Because of this technology, the diagnostic process is shortened, reducing stress considerably for individuals waiting for a definite diagnosis," added the co-author of "Diagnostic Value of Tc-99m-DPD-SPECT/Spiral-CT Hybrid Imaging in Unclear Foci of Increased Bone Metabolism in Cancer Patients."
Römer said, "With SPECT/CT, the morphologic correlate (form and structure) can be visualized to further clarify findings on bone scintigraphy. We call our procedure 'SPECT-guided CT.' " He further explained, "From our study, we conclude that SPECT-guided CT is able to clarify more than 90 percent of findings that were classified as indeterminate in the analysis of SPECT alone. That could mean that in daily clinical practice, additional radiological examinations can be avoided in 90 percent of patients with indeterminate findings in bone scintigraphy." The German researchers also significantly reduced the CT radiation exposure, according to the study that Römer calls the first report on the benefit of SPECT/spiral CT in bone scintigraphy.
The combination of SPECT and CT was introduced about five years ago but provided non–diagnostic quality CT images, said Römer. "The recently introduced combination of SPECT and spiral CT scanners enables combined SPECT/CT images, which are diagnostic," he detailed. "With bone scintigraphy alone, it is not possible to differentiate bone metastases (spread) from benign processes causing enhanced bone metabolism," said Römer. Consequently, additional radiological examinations are regularly recommended to study the metabolic changes. These studies are performed separately and--most often--with a certain time delay, said the nuclear medicine physician and board-certified radiologist. In addition, a radiologist analyzing the separate CT examination may not have detailed information on the scintigraphic findings.
Bone scintigraphy reveals changes in bone metabolism rather than changes in bone structure. The tracer usually requires several hours to be absorbed into the bone and cleared from the remaining tissues of the body. By evaluating the images taken at different times after the administration of the tracer, information about bone metabolism and blood flow versus soft tissue (muscle, ligament, tendon) can be obtained. Spiral CT scanning is a painless procedure in which a special imaging machine rotates rapidly around the body, taking cross-sectional images. The term "spiral CT" comes from the shape of the path taken by the X-ray beam during scanning. The German researchers used the SPECT/CT system Symbia T2, provided by Siemens Medical Solutions for scientific evaluation.
Römer indicated that the number of patients included in the study was limited, and additional studies with larger patient populations should carefully address the cost efficiency of this new technology and its value in a real clinical setting.
Abstract: W. Römer, A. Noemayr and T. Kuwert, Clinic of Nuclear Medicine, University of Erlangen/Nuremberg, Erlangen, Germany; M. Uder and W. Bautz, Institute of Radiology, University of Erlangen/Nuremberg, Erlangen, Germany, "Diagnostic Value of Tc-99m-DPD-SPECT/Spiral-CT Hybrid Imaging in Unclear Foci of Increased Bone Metabolism in Cancer Patients," SNM's 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 251.
SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease, metabolic imaging for heart disease, neuroendocrine and brain imaging, new agents for imaging infection and inflammation, and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.
SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed resource in the field; sponsor research grants, fellowships and awards; host the premier annual meeting for medical imaging; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced--and continue to explore--biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.
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