Date of Award

January 2014

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Albert J. Sinusas

Subject Area(s)

Medicine

Abstract

STRESS AND REST SPECT/CT IMAGING FOR EVALUATION OF LOWER EXTREMITY PERFUSION. Nataly Sumarriva, Wunan Zhou, Mitchel R. Stacy, and Albert J. Sinusas. Section of Cardiology, Department of Internal Medicine, Yale University, School of Medicine, New Haven, CT.

Peripheral arterial disease (PAD) is a progressive atherosclerotic disease of the lower limbs affecting approximately 8 to 10 million Americans. Diabetic patients are twice as likely to develop PAD than are patients without diabetes mellitus (DM) and PAD progression is more rapid in DM patients. The primary goal of this study was to translate image analysis tools previously developed and validated for application to hybrid SPECT/CT imaging in preclinical models of peripheral arterial disease to patients, and to evaluate the reproducibility and feasibility of the approach for clinical imaging. Lower extremity tissue perfusion was analyzed in patients using 99mTc-tetrofosmin SPECT/CT imaging. Image analysis tools previously validated for murine and porcine models of hind limb ischemia were used to analyze and quantify specific lower extremity muscle groups in a pilot series of clinical SPECT/CT images. Using an image analysis program, the image quantification was done by drawing volumes of interest (VOIs) around each of five muscle groups in the calf (tibialis anterior, tibialis posterior, fibularis, soleus, and gastrocnemius) on the CT images. These ROIs were then copied onto the registered SPECT images to obtain an average intensity value for each muscle group an index of both microvascular and macrovascular perfusion. The results showed a statistically significant difference in intensity per volume per injected dose of radiotracer corrected for decay between rest and stress for all of the muscle groups between patients that had both rest and stress imaging (P=0.001). We demonstrated that our approach has a high interobserver reproducibility, with an R2 = 0.99 between the two sets of values. This method may be used to assess abnormality of both microvascular and macrovascular perfusion of patients with diabetes mellitus at higher risk for peripheral arterial disease in the future.

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This is an Open Access Thesis.

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