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Driving Growth in Nuclear Medicine With Advancements in SPECT/CT

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Nuclear medicine has, unfortunately, been referred to as “unclear” medicine due to previous limitations in both the resolution of functional imaging studies and precise anatomic reference. With the emergence of high-resolution hybrid SPECT and CT systems, that misnomer no longer applies.

One of the first healthcare facilities in the world to install Discovery™ NM/CT 670 was Antwerp University Hospital (UZA), Belgium. “What we have seen with SPECT/CT and bone imaging is that we can now provide a very specific answer to the question that the clinician is asking,” says Tim Van den Wyngaert, MD, PhD, Professor of Nuclear Medicine. “In the past, bone scintigraphy did not always provide a specific and clear answer, which often led to a follow-up study to guide diagnosis and treatment. We now see highly specific requests that we are able to answer with high confidence because of SPECT/CT.”

Prior to installing the new system, Professor Van den Wyngaert says that approximately 11% of bone scan reports at UZA suggested additional imaging to characterize an equivocal finding. That percentage has now decreased to less than 1% with the use of SPECT/CT.

“I’m impressed with the images this system generates, particularly the SPECT and the SPECT volume, in addition to the quality of the CT images at very low radiation exposures,” Professor Van den Wyngaert adds.

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Figure 1. Bone SPECT/CT study for recurrent pain three years after lumbar spine fusion surgery of the L3-L4 segment, showing (A) axial CT, (B) axial fused, (C) coronal CT, (D) coronal fused and (E) 3D volume rendered images, clearly highlighting the extensive degenerative disc and facet joint disease in the adjacent segments below the fusion, allowing for a targeted therapeutic approach.

Samaritano Hospital in Rio de Janeiro is also utilizing the Discovery NM/CT 670 for hybrid imaging studies led by Léa Mirian Barbosa da Fonseca, MD, Professor, and Maria Carolina Pinheiro Pessoa Landesmann, Associate Professor, Department of Radiology, Federal University of Rio de Janeiro, both of whom are nuclear medicine physicians.

Dr. da Fonseca and Dr. Landesmann have found that capturing both morpho-structural and functional imaging data in a single examination by utilizing Discovery NM/CT 670 has led to an increase in spatial resolution and the ability for clinicians to detect and localize disease across diverse organs and tissues. “This technology has revolutionized our imaging diagnosis, benefitting patients with a more specific functional test and resulting in a lower cost to our public and private healthcare system,” says Dr. da Fonseca.

The hybrid technology enables more precision in the reporting, both in terms of the anatomical location and lesion characterization. This gives them the ability to deliver a differential diagnosis with possible attenuation artifacts. “Our clinical reports are more complete and with the image clarity and definition the reports are more beneficial to our referring physicians,” adds Dr. da Fonseca.

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Figure 2. Bone SPECT/CT study on patient with persistent pain 18 months after lumbar spine fusion surgery of the L4-L5-S1 segments. Fused (A) sagittal, (B) axial, and (D) coronal SPECT/CT images, (C) coronal CT image, and (E) 3D volume rendered SPECT/CT image shows pseudo-arthrosis of the L5-S1 segment caused by bilateral loosening of the S1 screws, guiding the approach for revision surgery.

Increased referrals for nuclear medicine

Nuclear medicine exams that were previously requested at a later stage in the diagnostic workup are now being requested as the first line imaging exam, leading to an increase in the number of SPECT/CT exams at Samaritano Hospital. The most significant increase has been with the inpatients for the evaluation of infection or digestive bleeding.

Dr. da Fonseca adds that hybrid SPECT/CT imaging helps in the investigation of inflammatory and infectious processes. The hospital serves a large elderly population and infections are a common health issue. Diagnosing these conditions is often stressful for the patients who may undergo multiple exams.

Figure 3. Scintigraphy with 99mTc labelled erythrocytes (“in vitro”): SPECT/CT of the abdomen confirmed the presence of gastrointestinal bleeding. The arrows show bleeding spots corresponding to the colon in the SPECT and fused SPECT/CT images.

“The leukocyte scintigraphy with a hybrid SPECT/CT has contributed greatly to the evaluation of infection with the added advantage of whole-body images giving us diagnostic accuracy,” says Dr. Landesmann.

Beyond the traditional utilization of nuclear medicine for infections, Dr. da Fonseca and Dr. Landesmann have begun to explore expanded clinical applications for SPECT/CT. This includes evaluation of digestive bleeding with red blood cells marked for more accurate location of bleeding outbreak; evaluating the function of parathyroid adenoma; detecting the spread of disease into the sentinel lymph node from breast, gynecological and melanoma tumors; visualization of neuroendocrine tumors and neural crest; and pulmonary scintigraphy for thromboembolism research. Even traditional myocardial scintigraphy has benefited by the attenuation correction protocol using CT, Dr. da Fonseca adds.

These expanded clinical applications of SPECT/CT have spurred growth in Samaritano Hospital’s nuclear medicine department. “We estimate that the increase in inpatient nuclear medicine exams is approximately 60% compared to the same period before the acquisition of the SPECT/CT. We also expect an increase of nearly 50% for outpatient referrals,” Dr. da Fonseca says. Challenging cases where SPECT/CT provided the clinical answer are also included in the hospital’s weekly educational rounds for the clinical staff, helping to further promote the application of this hybrid technology.

That demand for hybrid nuclear medicine exams was also a key factor for UZA acquiring a SPECT/CT system. Professor Van den Wyngaert says that referring physicians were actively requesting these types of studies. There is a further shift in referral indications for SPECT/CT in bone imaging at UZA, specifically in the post-operative setting for degenerative bone disease after prosthesis or lumbar spine fusion surgery.

For these two later indications, UZA has seen a two-fold increase in referrals over the last three years after the installation of the Discovery NM/CT 670.

While SPECT is extensively used for bone imaging, the addition of CT has opened up new imaging possibilities. At UZA, this includes utilizing SPECT/CT for guiding surgical excision of sentinel nodes in regions with complex anatomy, such as the head, neck and pelvis, and planning for and the assessment of radionuclide therapy; or in the planning of thoracic or hepatic surgery. In the liver, SPECT/CT helps provide information on the metabolic active volume for resection of the lobes.

Figure 4. Images of a patient who underwent a parathyroid scintigraphy exam demonstrate the precision of SPECT/CT in helping to localize the parathyroid adenoma in the lower right pole.

To help educate nuclear medicine physicians on the clinical value of SPECT/CT, Professor Van den Wyngaert is collaborating with the European Association of Nuclear Medicine/European School of Nuclear Medicine to develop a new multi-modality SPECT/CT course in musculoskeletal (MSK) imaging that could premiere as soon as Spring 2017. Professor Van den Wyngaert says the interactive hands-on course is designed as a multi-modality imaging educational project targeted for all European users regardless of country or region. During this one-and-a-half day session, participants will have a brief theoretical review intertwined with hands-on case reading and interactive panel discussions on a broad range of MSK SPECT/CT applications.

Targeted therapies

One of the most important issues in nuclear medicine is the emergence of quantitation, says Dr. da Fonseca. “New tracers have emerged and along with them the need for reliable quantitative analysis,” she explains. In addition to well-known tracers such as MIBG 123I for cardiac studies, this includes scintigraphy with 99mTc-TRODAT1 for evaluation of movement disorders and the evaluation of cardiac amyloidosis with 99mTc-DPD.

Figure 5. Scintigraphy with 99mTc-TRODAT1 for evaluation of the dopaminergic system: the SPECT/CT images allow the anatomic localization of the striatum, favoring better quantitation.

“Our priority has been to use the hybrid SPECT/CT technology not only for diagnosis but also in the followup of patients undergoing therapy with radionuclides, for example 177-lutetium-octreotate for the treatment of neuroendocrine tumors and radium-223 for the treatment of bone metastases of prostate cancer,” Dr. da Fonseca adds. The hospital is also utilizing the Discovery NM/CT 670 for research in the evaluation of lung tumors with glucose marked with 99mTc.

As a leading European academic research center, UZA is investigating how to utilize quantitation in nuclear medicine for improvements in patient care. “There is some preliminary data on how to use quantitation to measure changes in bone lesions, but we are not yet sure how to interpret these changes in clinical management,” says Professor Van den Wyngaert. “This is an active area of research and we hope to have more data in the coming years; the results look promising and could generate traction for further expansion of our hybrid applications.”

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