Article Figures & Data
Figures
- FIGURE 1.
Semiquantitative visual grading. Both planar and SPECT images are used to visually score degree of cardiac amyloidosis. Amount of 99mTc-pyrophosphate uptake in myocardium is compared with that in ribs. Grade 0 (normal) = no myocardial uptake and normal bone uptake; grade 1 (equivocal) = myocardial uptake less than rib uptake; grade 2 (abnormal and suggestive of cardiac amyloidosis) = myocardial and rib uptake equal; grade 3 (abnormal and strongly suggestive of cardiac amyloidosis) = myocardial uptake greater than rib uptake; PYP = pyrophosphate.
- FIGURE 2.
Correct region-of-interest placement for H/CL ratio. To accurately calculate H/CL ratio, circular region of interest (ROI) is placed over myocardium on 3-h anterior planar 99mTc-pyrophosphate image (blue circle). Size of heart region should be maximized to cover entire myocardium. For contralateral lung, equal-sized ROI is placed on opposite side of sternum on flat area of ribs (white circle). H/CL ratio is calculated by dividing heart region mean counts by contralateral chest region mean counts. (Courtesy of Saurabh Malhotra, MD, MPH.)
- FIGURE 3.
H/CL ratio incorrect region-of-interest placement. Three-hour anterior planar 99mTc-pyrophosphate images were used to demonstrate impact of incorrect region-of-interest placement on H/CL ratio. (A) Correct heart and contralateral-lung region-of-interest placement resulted in H/CL ratio of 1.18, which is negative for amyloidosis. (B) Incorrect heart region-of-interest placement including sternal activity but correct contralateral-lung region-of-interest placement. H/CL ratio was falsely elevated at 1.91, suggesting cardiac amyloidosis. (C) Correct heart region-of-interest placement but incorrect contralateral-lung region-of-interest placement over curvature of ribs resulting in falsely decreased ratio of 0.94 because of increased activity in contralateral-lung region of interest. (D) Correct heart region-of-interest placement but incorrect contralateral region-of-interest placement including sternal activity. Calculated H/CL ratio was falsely decreased at 0.67. Heart region of interest = 1. Contralateral-lung region of interest = 2.
- FIGURE 4.
99mTc-pyrophosphate image comparison at 1 vs. 3 h. (A) Anterior (left) and left anterior oblique (right) images acquired 1 h after injection. (B) Anterior (left) and left anterior oblique (right) images acquired 3 h after injection. Images acquired 3 h after injection demonstrate better soft-tissue clearance and greater bone uptake and definition than images acquired 1 h after injection. Hardly any bone uptake is discernable in 1-h images. In addition, myocardial uptake is similar on both 1- and 3-h images because peak myocardial uptake of 99mTc-pyrophosphate occurs about 1 h after injection. Peak bone uptake occurs 2–3 h after injection.
- FIGURE 5.
Planar vs. SPECT blood pool. On planar 99mTc-pyrophosphate images, blood pool cannot be differentiated from myocardial uptake. (A) Anterior planar image demonstrating diffuse uptake assumed to be myocardial uptake. Planar-only imaging cannot be used to differentiate blood-pool uptake from myocardial uptake. (B) SPECT images immediately after acquisition of planar images showing that 99mTc-pyrophosphate uptake is not localized to myocardium but is within ventricular cavity blood pool. Circle denotes coronal image best demonstrating residual blood pool. (Reprinted from (1).)
Tables
Parameter Characteristics Standard/optional/preferred Camera type Large-field-of-view γ-camera Standard Cadmium zinc telluride Optional* Energy peak 140 keV Standard Energy window 15%–20% Standard Collimator Low-energy, all-purpose Standard Patient position Supine Standard Field of view Heart/chest Standard Injection-to-imaging time 3 h Standard 1 h Optional Planar Acquisition type Static Standard Whole-body imaging Optional† Detector configuration 90° Standard Views Anterior and left lateral Standard Number of views 2 Standard Counts per view 750,000 Standard Matrix 256 × 256 Standard Magnification 1.46 SPECT or SPECT/CT* Acquisition type Step and shoot or continuous Standard Patient position Supine Standard Upright Optional Orbit 180°/90° Standard 360°/180° Optional Matrix 128 × 128 (minimum, 64 × 64) Standard Magnification 1.46 (180° orbit) Standard 1.0 (360° orbit) Optional Pixel size 2.3–6.5 mm Standard Projections per detector 40/32 Standard Time per projection 20 s/25 s Standard CT attenuation correction Heart Preferred ↵* Parameters defined for γ-cameras as parameters for cadmium-zinc-telluride cameras have not been firmly established.
↵† Whole-body imaging is not useful when imaging with 99mTc-pyrophosphate. However, when using 99mTc-hydroxymethylenediphosphonate or 99mTc-DPD, whole-body imaging is useful to demonstrate soft-tissue uptake.
- TABLE 2.
Semiquantitative Visual Scoring of 99mTc-Pyrophosphate Uptake in Myocardium Versus Ribs
Grade Description 0 No myocardial uptake and normal bone uptake 1 Myocardial uptake less than rib uptake 2 Myocardial uptake equal to rib uptake 3 Myocardial uptake greater than rib uptake, with mild or absent rib uptake Measure Description Formula Sensitivity Probability that result will be positive when disease is present TP/(TP + FN) Specificity Probability that result will be negative when disease is absent TN/(TN + FP) Accuracy Number of correct findings (TP + TN)/(TP + TN + FP + FN) Positive predictive value Probability that patients with positive result truly have disease TP/(TP + FP) Negative predictive value Probability that patients with negative result do not have disease TN/(TN+FN) TP = patients with positive result who have disease; FN = patients with negative result who have disease; TN = patients with negative result who do not have disease; FP = patients with positive result who do not have disease.
In this issue
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- Article
- Abstract
- BRIEF REVIEW OF CARDIAC AMYLOIDOSIS
- PROCEDURE EVOLUTION
- CURRENT RECOMMENDED PROTOCOL
- ACQUISITION
- PROCESSING AND QUANTIFICATION
- INTERPRETATION
- TECHNICAL CONSIDERATIONS
- 99MTC-PYROPHOSPHATE KINETICS
- INJECTION-TO-IMAGING DELAY OF 1–3 HOURS
- PLANAR IMAGING VERSUS SPECT
- TECHNICAL CONSIDERATIONS IN APPLICATION
- CONCLUSION
- DISCLOSURE
- Footnotes
- REFERENCES
- Figures & Data
- Info & Metrics