Hotspot quantification of myocardial focal tracer uptake from molecular targeted SPECT/CT images: experimental validation

Yi-Hwa Liu; Zakir Sahul; Christopher A. Weyman; William J. Ryder; Donald P. Dione; Lawrence W. Dobrucki; Choukri Mekkaoui; Matthew P. Brennan; Xiaoyue Hu; Christi Hawley; Albert J. Sinusas

doi:10.1117/12.768985

17 March 2008 Hotspot quantification of myocardial focal tracer uptake from molecular targeted SPECT/CT images: experimental validation

Yi-Hwa Liu, Zakir Sahul, Christopher A. Weyman, William J. Ryder, Donald P. Dione, Lawrence W. Dobrucki, Choukri Mekkaoui, Matthew P. Brennan, Xiaoyue Hu, Christi Hawley, Albert J. Sinusas

Author Affiliations +

Proceedings Volume 6915, Medical Imaging 2008: Computer-Aided Diagnosis; 69150N (2008) https://doi.org/10.1117/12.768985
Event: Medical Imaging, 2008, San Diego, California, United States

Abstract

We have developed a new single photon emission computerized tomography (SPECT) hotspot quantification method incorporating extra cardiac activity correction and hotspot normal limit estimation. The method was validated for estimation accuracy of myocardial tracer focal uptake in a chronic canine model of myocardial infarction (MI). Dogs (n = 4) at 2 weeks post MI were injected with Tl-201 and a Tc-99m-labeled hotspot tracer targeted at matrix metalloproteinases (MMPs). An external point source filled with Tc-99m was used for a reference of absolute radioactivity. Dual-isotope (Tc-99m/Tl-201) SPECT images were acquired simultaneously followed by an X-ray CT acquisition. Dogs were sacrificed after imaging for myocardial gamma well counting. Images were reconstructed with CT-based attenuation correction (AC) and without AC (NAC) and were quantified using our quantification method. Normal limits for myocardial hotspot uptake were estimated based on 3 different schemes: maximum entropy, meansquared-error minimization (MSEM) and global minimization. Absolute myocardial hotspot uptake was quantified from SPECT images using the normal limits and compared with well-counted radioactivity on a segment-by-segment basis (n = 12 segments/dog). Radioactivity was expressed as % injected dose (%ID). There was an excellent correlation (r = 0.78-0.92) between the estimated activity (%ID) derived using the SPECT quantitative approach and well-counting, independent of AC. However, SPECT quantification without AC resulted in the significant underestimation of radioactivity. Quantification using SPECT with AC and the MSEM normal limit yielded the best results compared with well-counting. In conclusion, focal myocardial "hotspot" uptake of a targeted radiotracer can be accurately quantified in vivo using a method that incorporates SPECT imaging with AC, an external reference, background scatter compensation, and a suitable normal limit. This hybrid SPECT/CT approach allows for the serial non-invasive quantitative evaluation of molecular targeted tracers in the heart.

Citation Download Citation

Yi-Hwa Liu, Zakir Sahul, Christopher A. Weyman, William J. Ryder, Donald P. Dione, Lawrence W. Dobrucki, Choukri Mekkaoui, Matthew P. Brennan, Xiaoyue Hu, Christi Hawley, and Albert J. Sinusas "Hotspot quantification of myocardial focal tracer uptake from molecular targeted SPECT/CT images: experimental validation", Proc. SPIE 6915, Medical Imaging 2008: Computer-Aided Diagnosis, 69150N (17 March 2008); https://doi.org/10.1117/12.768985

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available