High‐resolution multipinhole single‐photon–emission computed tomography in experimental and human arthritis

Abstract

Objective. To image inflammatory arthritic lesions in experimental arthritis and in patients with arthritis, using a newly developed high-resolution multipinhole single-photon-emission computed tomography (MPH-SPECT) technique.Methods. Six interleukin-1 receptor antagonistdeficient mice with arthritis of the front and back paws and 2 control BALB/c mice were imaged with MPH-SPECT and scored macroscopically for arthritis. SPECT imaging was performed with a conventional gamma camera upgraded with a pyramidal lead collimator affixed with MPH apertures. All images were reconstructed, and uptake in the paws was quantified in counts/weight and injected activity. To transfer the imaging technique to humans we examined the clinically dominant hand of 6 individuals (3 with established rheumatoid arthritis [RA], 1 with early RA, 1 with osteoarthritis, and 1 healthy control).Results. MPH-SPECT images were highresolution 3-dimensional tomographic images, which allowed exact localization and quantifiable observation of increased bone metabolism. MPH-SPECT counts of inflamed joints in mice correlated with macroscopic scoring and histologic joint analysis postmortem. In humans, MPH-SPECT images depicted a detailed visualization of tracer accumulation in bony structures of hand and finger joints, and were also capable of imaging increased bone metabolism that had appeared normal with other imaging modalities, e.g., magnetic resonance imaging.Conclusion. The MPH-SPECT technique represents a new diagnostic tool in the detection of bone pathology in small-animal arthritis research. Compared with macroscopic scoring, this new method provides a more objective and higher-precision quantifiable measurement of bone reaction, allowing visualization of inflammatory processes of the whole skeleton in vivo. These results suggest that MPH-SPECT may be useful as a diagnostic instrument for monitoring experimental arthritis, with further potential for use in human studies of RA.

Imaging of activated macrophages in experimental osteoarthritis using folate-targeted animal single-photon-emission computed tomography/computed tomography

“…The introduction of high-resolution multipinhole SPECT systems provided submillimeter resolution and up to 50 times increased sensitivity compared to clinical SPECT and PET systems. This allows assessment and quantification of arthritic activity in small animals such as mice and rats (20). When SPECT is used in combination with microfocal computed tomography (micro-CT) as an anatomic reference, the radioactive signal can be located in the body in 3 dimensions.…”

Accumulation of ^99mTC-methylene diphosphonate radiotracer in rat's forelimb

“…Examination of the scanned photos shows that bone scintigraphy can diagnose the special bone disease conforming with other studies [6,12,15]. This study shows that scintigraphy of the rats has more resemblance with human bone scintigraphy [1,2].…”

“…So we must compare the numbers of counts only with the opposite organ at the same animal. Comparing the numbers of the same organs of different animals or with other organs of the same animal is not correct [14,15]. In this study, counts of the right structures were not significantly different from the left one in each of the rats (p > 0.05).…”

An enhanced high-resolution EMCCD-based gamma camera using SiPM side detection

“…The application of pinhole geometries leads to unsurpassed imaging capabilities in small-animal SPECT (Schramm et al 2003, Van der Have et al 2009 and is also applied for human SPECT imaging of specific regions-of-interest, e.g. brain, chest and extremities (Rowe et al 1993, Funk et al 2006, Ostendorf et al 2006. For introductions to pinhole and small-animal SPECT imaging see e.g.…”