Article Figures & Data
Figures
- FIGURE 1.
Count-based regional radioactivity in last frame of 82Rb scan in patient with myocardial infarction before (A) and after (B) wavelet denoising. x-axis represents eight ROIs in each plane (from inferior region 1 counterclockwise to septal), y-axis represents average radioactivity (nCi/pixel/s) in ROI, and z-axis represents short-axis planes (from base to apex). Regional radioactivity in original dataset for entire heart was distorted by inherent noise (A). Wavelet approach maintained smoothness and continuity among regions but still preserved regional variation (B).
- FIGURE 2.
Median estimate-to-error ratios derived from 82Rb data before (original) and after wavelet denoising at rest and during hyperemia. Wavelet approach improved estimate-to-noise ratio (P < 0.001 for both). Values are expressed as mean ± SD.
- FIGURE 3.
Distribution of differences between flows derived from 82Rb studies and those from H215O studies. (A) Differences in resting flows with original protocol (0.05 ± 0.80 mL/g/min) and wavelet protocol (−0.09 ± 0.20 mL/g/min). (B) Differences in hyperemic flows with original protocol (0.53 ± 1.57 mL/g/min) and wavelet protocol (−0.04 ± 0.56 mL/g/min). Wavelet protocol reduced differences between two measurements (P < 0.001 for both). Values are expressed as mean ± SD.
- FIGURE 4.
Estimate-to-error ratios (A) and COVs of flow estimates (B) derived from H215O data before and after wavelet-based noise reduction at rest and during hyperemia. Wavelet approach improved precision and reduced regional variation (P < 0.001 for both). Values are expressed as mean ± SD.
- FIGURE 5.
Estimate-to-error ratios (A) and COVs of flow estimates (B) derived from 13NH3 data before and after wavelet-based noise reduction at rest and during hyperemia. Wavelet approach improved precision and reduced regional variation (P < 0.001 for both). Values are expressed as mean ± SD.
- FIGURE 6.
Flow estimates in normal and infarcted regions in patients with myocardial infarction using 82Rb at rest. Before wavelet denoising (Original), flow estimates had wide distributions and significant overlap. After wavelet denoising (Wavelet), flow estimates in normal and infarcted regions were clearly separated. Values are expressed as mean ± SD. MBF = myocardial blood flow.
Tables
- TABLE 1.
Estimates of Global Flow with Original Protocol and After Wavelet Protocol Processing for Each Flow Tracer in Healthy Volunteers
Study Global flow* (mL/g/min) 82Rb H215O 13NH3 Original Wavelet n Original Wavelet n Original Wavelet n Rest 1.15 ± 0.46 0.82 ± 0.26 18 0.92 ± 0.19 0.90 ± 0.17 18 0.62 ± 0.16 0.59 ± 0.16 7 Stress 2.50 ± 0.54 1.85 ± 0.56 17 1.89 ± 0.50 1.84 ± 0.52 17 1.89 ± 0.67 1.76 ± 0.67 7 ↵* Mean ± SD.
Same subjects received 82Rb and H215O, whereas seven different subjects received 13NH3. Mean flow decreased after wavelet protocol with 82Rb because of improved estimates.
