SPECT/CT: Defining a Niche in Infection Imaging

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SPECT/CT is making notable inroads in imaging infection. It allows the detection of unsuspected infectious foci, especially in areas that are not well investigated by other imaging modalities. It is improving diagnostic performance and treatment management for specific infections such as in bone, the diabetic foot, post-device implantation, fever of unknown origin (FUO), orthopedics and in post transplant patients. A wide cross-section of physicians are starting to take notice—and referring more cases to gain the combined strengths of SPECT and CT to investigate infection.

SPECT/CT is an integral part of infection imaging. “Just like PET/CT, we no longer do SPECT without the CT,” says Jerry Froelich, MD, director, nuclear medicine and molecular imaging at the Imaging Center for the University of Minnesota in Minneapolis.

“I cannot imagine going back to do SPECT without the CT now that I do it every day or all the time,” says Froelich.

SPECT/CT’s imaging advantage

SPECT/CT combines the advantages of molecular imaging to detect infection and anatomical imaging to localize it, says Anne Hitzel, MD, Nuclear Medicine Department, University Hospital of Toulouse, Place du Docteur Baylac, Toulouse, France. The new generation of SPECT/CT scanners with iterative reconstruction allows us to find smaller areas of lower activity that relates to infection or disease, adds Froelich.

SPECT/CT allows the detection of unsuspected infectious foci, especially in areas that are not well investigated by planar scans—such as areas surrounding prothesis or infected areas without abscess, vascular prosthesis or left-ventricular-assist devices, Hitzel says. “We frequently use it to help the surgeons determine what is the next logical step to do with the patient, be it aspiration biopsy or even surgery,” adds Froelich. In pediatric populations, neuroblastomas can be located with mIBG (meta-iodobenzylguanidine) scans as they are not FDG positive and SPECT/CT provides information on where the neuroblastoma is located, while PET/CT cannot, he says.

Moreover, conventional planar and SPECT images are often unable to precisely locate the site of infection. Hybrid SPECT/CT system delivers the high sensitivity of scinitigraphic technology with the high specificity of CT and overcomes the partial limitations of each technology alone. SPECT/CT has been widely used to detect and localize