High-spec SPECT/CT offers research appeal

While the use of clinical hardware and pharmaceuticals can hike the cost of research, techniques that emerge as a result may then transfer to patients more rapidly. Little wonder that researchers are eyeing the latest SPECT/CT technology for large animal studies.

Medical imaging researchers at Johns Hopkins University in Baltimore last year used a SPECT system with integral CT to track the migration of a novel cardiac therapy. They now hope to continue this work on the department's new 16-slice system, if sufficient funding can be found.

The project is aimed at finding a minimally invasive method of delivering stem cells to the heart to repair areas of damage caused by myocardial infarction. Intravenous injection is the preferred option, but researchers need to know that the cells have reached their destination.

The initial experiment involved injection of canine mesenchymal stem cells into six dogs that had undergone heart attack triggered by a minimally invasive percutaneous method. Cells were tagged with a radioisotope tracer and MRI contrast agent to enable short- and longer term follow-up on SPECT/CT and MRI.1

"With such small areas lighting up on the chest, on conventional SPECT it would be hard to say 'Is it in the heart?', let alone 'What part of the heart is it in?'" said Dr. Dara Kraitchman, an associate professor of radiology at Johns Hopkins. "By using the CT as well, we were able to have a very high confidence about what we were seeing."

The cells remained visible on SPECT/CT until seven days after injection. Imaging revealed, however, that many had traveled to the liver, bone marrow, and spleen as well as the heart.

Future preclinical studies may look at delivering the stem cells in multiple doses, Kraitchman said. Researchers also want to be sure that radiolabeled cells retain their reparative functionality.

Reference

1. Kraitchman DL, Tatsumi M, Gilson WD, et al. Dynamic imaging of allogeneic mesenchymal stem cells trafficking to myocardial infarction. Circulation 2005;112(10):1451-1461.