Radiotracer imaging of peripheral vascular disease

Abstract

Peripheral vascular disease (PVD) is an atherosclerotic disease affecting the lower extremities, resulting in skeletal muscle ischemia, intermittent claudication, and, in more severe stages of disease, limb amputation and death. The evaluation of therapy in this patient population can be challenging, as the standard clinical indices are insensitive to assessment of regional alterations in skeletal muscle physiology. Radiotracer imaging of the lower extremities with techniques such as PET and SPECT can provide a noninvasive quantitative technique for the evaluation of the pathophysiology associated with PVD and may complement clinical indices and other imaging approaches. This review discusses the progress in radiotracer-based evaluation of PVD and highlights recent advancements in molecular imaging with potential for clinical application.

Keywords: PET; SPECT; angiogenesis; perfusion; peripheral vascular disease.

FIGURE 1.

Arteriography (A) demonstrates unilateral PVD, which is confirmed by abnormal ²⁰¹Tl SPECT stress perfusion profile curves of anterior and posterior tibial muscle components of the left leg (B) as well as visual inspection of ²⁰¹Tl SPECT transverse images (C; perfusion defect noted by arrow). (Reprinted from (24).)

FIGURE 2.

Multimodality evaluation with ankle-brachial indices (A), CT angiography (B), and hybrid ^99mTc-tetrofosmin SPECT/CT (C) reveals impaired lower-extremity pressures and tissue perfusion in PVD patient with previously implanted aortoiliac stents (B). Segmentation of muscle groups into 3-dimensional regions of interest by CT attenuation images (D) confirmed differences in regional tissue perfusion between legs (E). Red 5 gastrocnemius; yellow 5 soleus; green 5 tibialis; purple 5 fibularis; ABI 5 ankle–brachial index; PPG 5 photoplethysmograph; PVR 5 pulse volume recording; TBI 5 toe–brachial index.

FIGURE 3.

Lower-extremity PET H₂¹⁵O imaging of healthy subject and PVD patient during selective adenosine infusion into left leg (A). Baseline and adenosine stress blood flow was assessed, and flow reserve was expressed as ratio of adenosine flow to baseline flow (B). Flow reserve was significantly lower in PVD patients than in healthy subjects. (Reprinted from (32).).

FIGURE 4.

PET/CT imaging with ⁶⁴Cu-DOTA–C-type atrial natriuretic factor–comb (A) and ⁶⁴Cu-DOTA–comb (B) in mouse model of hind limb ischemia, 7 d after femoral artery occlusion. ⁶⁴Cu-DOTA–C-type atrial natriuretic factor–comb uptake was significantly higher than uptake of ⁶⁴Cu-DOTA–comb in ischemic limb when percentage injected tracer dose per gram of tissue (C) or ischemic-to-nonischemic leg ratios (D) were examined. (Reprinted from (52).) CANF 5 C-type atrial natriuretic factor.

FIGURE 5.

Analysis of mean (A) and maximum (B) ¹⁸F-FDG tumor-to-background ratios within multiple arterial regions on day 1 (solid bars) and 14 d later (hatched bars). No significant differences were observed within arterial regions across time. Carotid artery uptake was significantly higher than ¹⁸F-FDG uptake within lower-extremity arteries on days 1 and 14. ¹⁸F-FDG PET (C, middle) fused with CT imaging (C, right) revealed similar uptake in femoral arteries on days 1 and 14 (noted by arrows). CFA 5 common femoral artery; SFA 5 superficial femoral artery; TBR 5 tumor-to-background ratio. *P < 0.001. (Reprinted from (58).)