Immunoscintigraphy of aortic dissection with 99mTc-labeled murine anti-smooth muscle myosin monoclonal antibody in rats.

UNLABELLED Aortic dissection is among the most common of fatal conditions of the aorta. Prompt and accurate diagnosis of the site and extent of the lesion is necessary for adequate therapy. However, this catastrophic disease, characterized by extensive damage to smooth muscle cells, lacks specific signs and symptoms. As a result, the diagnosis is still frequently missed today and a new diagnostic method to specifically identify aortic dissection would be attractive. The purpose of this study was to examine the feasibility of radioimmunoscintigraphy using 99mTc-anti-smooth muscle myosin monoclonal antibody (SM-MAb) for the noninvasive diagnosis of aortic dissection in the rat experimental model. METHODS The accumulation of 99mTc-anti-SM-MAb was studied, and scintigraphic imaging with 99mTc-anti-SMMAb was performed in rats immediately after experimental aortic dissection and 1 and 2 wk later. RESULTS The radioactivity of 99mTc-anti-SM-MAb in the dissected aorta showed a significant increase compared both with the normal portion of the aorta and with blood 6 h after injection of the radiotracer; the ratio of the percentage injected dose per gram (%lD/g) in the lesion to that retained in the normal portion was 4.17 +/- 1.47. Scintigraphic imaging with 99mTc-anti-SM-MAb allowed distinct visualization of the dissected aorta with specific accumulation of antibody 6 h after tracer injection. Selective accumulation of the tracer in the dissected portion of the aorta persisted even 1 wk after aortic injury, allowing clear visualization of the dissected lesion by scintigraphy. CONCLUSION Radioimmunoscintigraphy using anti-SM-MAb is a potentially useful noninvasive diagnostic method for imaging aortic dissection.