PET/CT in HD: Seeing More, Clearly
Case Study: UT Southwestern Medical Center
High-definition is the goal in PET/CT imaging. HD met PET/CT last year when Siemens Medical Solutions introduced a new technology designed to bring significant improvements to PET/CT image quality. High Definition PET (HD•PET) brings the promise of sharper and more clearly defined images across the entire field of view, as well as the potential to provide greater accuracy in lesion detection, especially small lesions, and thus improve cancer staging and more targeted treatment.
Clinically released this month, HD•PET is available on all Biograph TruePoint PET•CT solutions and as an upgrade for current Biograph TruePoint systems. It enables visualization of structures with 2 millimeter resolution and 100% improvements in signal to noise across the entire field of view. It’s the wave of the future—that is making a difference in clinical practice today.
Blazing the trail for new technology
The UT Southwestern Medical Center in Dallas, Texas, is a leader in hybrid imaging technology, having deployed the first HD•PET system in clinical practice for use in oncology and neurology. UT Southwestern’s faculty and residents annually provide inpatient hospital care to nearly 92,000 people. Each year it completes about 1,500 PET/CT scans.
Dedicated to improving healthcare by offering state-of-the-art, image-based technology in all areas of clinical radiology, the PET Facility within the Bill and Rita Clements Advanced Medical Imaging Building offers high-resolution PET scanning of organ systems and whole-body scans for neurological, oncological and psychiatric applications. To offer a consistent high quality of care with state-of-the-art technologies, the facility purchased a 64-slice PET•CT scanner to do both respiratory and cardiac CT and PET gating for cardiac imaging and radiation therapy planning.
This opened an opportunity for Siemens to collaborate with a highly qualified partner in testing imaging products across the spectrum of modalities for the first clinical installation of HD•PET technology. In 2006, the PET facility introduced the Biograph 64 PET•CT scanner. In December 2007, HD technology was introduced to compare the image quality of HD•PET to standard PET reconstruction methods.
Historically, intrinsic image quality degrades with distance from the center of the field of view. HD•PET reduces this effect, providing increased diagnostic confidence to improve the staging of disease through uniform image resolution across the transverse field of view.
Siemens developed “this approach to improve image quality, especially at the edge of the field of view,” says Dana Mathews, MD, PhD, medical director of the PET facility. Traditionally, the best resolution for PET has always been at the center of the field of view and the image quality tends to degrade towards the periphery.
UT Southwestern has employed standard methods of reconstruction for PET, as well as HD•PET, on every patient scanned at the facility. “We’re performing both scans on every patient—so that we can compare both methods side by side,” Mathews says. Since the installation, the facility has imaged close to 400 patients, comparing standard PET and HD•PET and providing feedback to the Siemens engineering team.
“PET technology has achieved widespread acceptance in oncology, neurology and cardiology,” Mathews says. Currently, UT Southwestern’s efforts in HD reconstruction methods are applied to 95% of the oncology patients. The remaining 5% of studies are neurological in nature, including patients with brain tumors, dementia and epilepsy.
“For oncology patients, a post-therapy or post-surgery PET study using 18F-FDG, is used for monitoring treatment effects, and for differentiating tissue necrosis from new or recurrent viable tumor,” Mathews says. For neurology patients, PET can help to evaluate changes in metabolism indicative of various types of dementia, and epilepsy. She points out that the overall HD•PET approach results in better image quality than traditional reconstruction methods.
HD•PET improves image quality in larger patients, too. “The image quality is excellent for patients weighing more than 250 pounds, with increased small lesion visualization that can often be problematic with patients of this size,” she says. HD•PET improves spatial resolution to 2 millimeters throughout the entire field of view which helps in small lesion detection, especially in peripherally located lesions.
HD•PET is having a positive impact on patient care—without affecting patient workflow. Scanning time remains the same for patients and staff since image reconstruction is completed after the scan is done. “A technologist can either do HD•PET first or traditional reconstruction first—the two techniques don’t interfere with each other and do not take a large amount of time to do,” Mathews says. HD•PET also doesn’t add time for image interpretation either.
Many of UT Southwestern’s patients are repeat visitors. Because of this, it is important to have an exact comparison between standardized uptake values (SUV) of FDG accumulation. “If we bring back patients whom we have scanned before, HD facilitates the direct comparison with old scans. Using HD technology, it is possible to review and/or reprocess older scans, to directly compare HD SUVs, as long as the PET raw data were saved,” she says.
While HD•PET has its advantages in lesion detection, it is important to note that the calculation of the SUV tends to be higher, especially for small lesions, compared to the traditional way of processing images, Mathews notes. This is not necessarily a drawback, but is something clinicians should be aware of when they compare images reconstructed using different methods. The SUVs tend to be higher because the small lesions are more accurately resolved and show higher signal to noise ratio with HD•PET, compared to traditional methods.
HD is the future of PET imaging
HD•PET is clearly making a clinical difference. It is improving spatial resolution to 2 millimeters throughout the entire field of view, thus helping with small lesion detection as well as to visualize lesions in larger patients. And it’s having a positive impact without changes to patient workflow or scanning time. Better images are accomplished in the same time period—and there is great potential for more improvements as clinicians continue to refine the technology’s true capabilities.
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Clinically released this month, HD•PET is available on all Biograph TruePoint PET•CT solutions and as an upgrade for current Biograph TruePoint systems. It enables visualization of structures with 2 millimeter resolution and 100% improvements in signal to noise across the entire field of view. It’s the wave of the future—that is making a difference in clinical practice today.
Blazing the trail for new technology
The UT Southwestern Medical Center in Dallas, Texas, is a leader in hybrid imaging technology, having deployed the first HD•PET system in clinical practice for use in oncology and neurology. UT Southwestern’s faculty and residents annually provide inpatient hospital care to nearly 92,000 people. Each year it completes about 1,500 PET/CT scans.
Dedicated to improving healthcare by offering state-of-the-art, image-based technology in all areas of clinical radiology, the PET Facility within the Bill and Rita Clements Advanced Medical Imaging Building offers high-resolution PET scanning of organ systems and whole-body scans for neurological, oncological and psychiatric applications. To offer a consistent high quality of care with state-of-the-art technologies, the facility purchased a 64-slice PET•CT scanner to do both respiratory and cardiac CT and PET gating for cardiac imaging and radiation therapy planning.
This opened an opportunity for Siemens to collaborate with a highly qualified partner in testing imaging products across the spectrum of modalities for the first clinical installation of HD•PET technology. In 2006, the PET facility introduced the Biograph 64 PET•CT scanner. In December 2007, HD technology was introduced to compare the image quality of HD•PET to standard PET reconstruction methods.
Historically, intrinsic image quality degrades with distance from the center of the field of view. HD•PET reduces this effect, providing increased diagnostic confidence to improve the staging of disease through uniform image resolution across the transverse field of view.
Siemens developed “this approach to improve image quality, especially at the edge of the field of view,” says Dana Mathews, MD, PhD, medical director of the PET facility. Traditionally, the best resolution for PET has always been at the center of the field of view and the image quality tends to degrade towards the periphery.
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| HD•PET study performed on a 64 year-old male with lymphoma to determine initial staging which showed matted hypermetabolic para-aortic lymph nodes. Linear increased uptake in the mid-line adjacent to the anterior abdominal wall was due to a wound infection. Source: University of Texas Southwestern Medical Center, Dallas, Texas. |
“PET technology has achieved widespread acceptance in oncology, neurology and cardiology,” Mathews says. Currently, UT Southwestern’s efforts in HD reconstruction methods are applied to 95% of the oncology patients. The remaining 5% of studies are neurological in nature, including patients with brain tumors, dementia and epilepsy.
“For oncology patients, a post-therapy or post-surgery PET study using 18F-FDG, is used for monitoring treatment effects, and for differentiating tissue necrosis from new or recurrent viable tumor,” Mathews says. For neurology patients, PET can help to evaluate changes in metabolism indicative of various types of dementia, and epilepsy. She points out that the overall HD•PET approach results in better image quality than traditional reconstruction methods.
HD•PET improves image quality in larger patients, too. “The image quality is excellent for patients weighing more than 250 pounds, with increased small lesion visualization that can often be problematic with patients of this size,” she says. HD•PET improves spatial resolution to 2 millimeters throughout the entire field of view which helps in small lesion detection, especially in peripherally located lesions.
HD•PET is having a positive impact on patient care—without affecting patient workflow. Scanning time remains the same for patients and staff since image reconstruction is completed after the scan is done. “A technologist can either do HD•PET first or traditional reconstruction first—the two techniques don’t interfere with each other and do not take a large amount of time to do,” Mathews says. HD•PET also doesn’t add time for image interpretation either.
Many of UT Southwestern’s patients are repeat visitors. Because of this, it is important to have an exact comparison between standardized uptake values (SUV) of FDG accumulation. “If we bring back patients whom we have scanned before, HD facilitates the direct comparison with old scans. Using HD technology, it is possible to review and/or reprocess older scans, to directly compare HD SUVs, as long as the PET raw data were saved,” she says.
While HD•PET has its advantages in lesion detection, it is important to note that the calculation of the SUV tends to be higher, especially for small lesions, compared to the traditional way of processing images, Mathews notes. This is not necessarily a drawback, but is something clinicians should be aware of when they compare images reconstructed using different methods. The SUVs tend to be higher because the small lesions are more accurately resolved and show higher signal to noise ratio with HD•PET, compared to traditional methods.
HD is the future of PET imaging
HD•PET is clearly making a clinical difference. It is improving spatial resolution to 2 millimeters throughout the entire field of view, thus helping with small lesion detection as well as to visualize lesions in larger patients. And it’s having a positive impact without changes to patient workflow or scanning time. Better images are accomplished in the same time period—and there is great potential for more improvements as clinicians continue to refine the technology’s true capabilities.