Author + information
- Emile R. Mohler III, MD⁎ (, )
- Abass Alavi, MD and
- Robert L. Wilensky, MD
- ↵⁎Hospital of the University of Pennsylvania, Department of Medicine, Cardiovascular Division, 11-103 Translational Research Center, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104
We read with great interest the article on coronary artery calcification by Dweck et al. (1) recently published in the Journal. Although the authors claimed that this communication was the first on this topic in the literature, we would direct the readership to our original article, “Detection and global quantification of cardiovascular molecular calcification by fluoro18-fluoride positron emission tomography/computed tomography—a novel concept” (2) and accompanying editorial, “Assessing global cardiovascular molecular calcification with 18F-fluoride PET/CT: will this become a clinical reality and a challenge to CT calcification scoring?” (3), published earlier on the same topic.
In addition, we take issue with a number of points made by the authors (1). Although we agree with them that it is feasible to detect cardiac calcifications using 18F–sodium fluoride far in advance of visualizing this phenomenon with x-ray computed tomography (CT), attempts to image coronary artery calcification by visualizing the artery on CT scan are challenging for a variety of reasons. First, it is extremely difficult to localize the coronary arteries without the assistance of contrast dye. The administration of x-ray contrast agent is not practical for screening of individuals at risk, given the potential toxicity of these agents. As noted by the investigators (1), it is necessary to assign regions of interest on clearly visualized calcifications on CT scan for detecting the ongoing calcification. Because the power of 18F–sodium fluoride technology lies in its early ability to detect molecular calcification in advance of structural abnormalities observed on CT scan, assigning a region of interest based on coronary artery calcification is not feasible in early disease in younger patients. Second, the authors (1) failed to address the need for partial volume correction, which is of importance in such small structures as coronary arteries because loss of signal or spillover from adjacent signal may occur when a relatively small region of interest is evaluated. Particularly, motion artifacts due to the cardiac cycle further degrades the spatial resolution and necessitates partial volume correction. Third, the blood pool correction for background activity of tracer adds further complexity and potential error.
We believe that a methodology independent of recognition of vascular distribution, a global assessment, will be of great value in detecting early disease before calcification is apparent on electron beam CT imaging. The methodology that we presented in publications predating the recent article by Dweck et al. (1) describes a global assessment of molecular calcification detected with 18F–sodium fluoride. Although the methodology described in this article (1) appears to be reproducible by the investigators involved, this may not be the case for inexperienced practitioners. A global assessment of cardiac calcification obviates the need for partial volume correction and therefore is essential in assessing overall calcification in the heart. In addition, a global approach allows for delayed imaging of 2 to 3 h after the administration of sodium fluoride, which would obviate the need for blood pool correction.
There is certainly a dire need for visualizing atherosclerotic disease in early stages and 18F–sodium fluoride imaging may realize this objective. Prospective, randomized clinical trials are needed to determine the feasibility and clinical benefit of 18F–sodium fluoride imaging for early atherosclerotic disease.
- American College of Cardiology Foundation