Abstract 1912: Evaluation of Myocardial Microvascular Permeability and Fractional Vascular Volume Using 64-Slice Helical CT
PURPOSE: Cardiovascular diseases induce subtle changes in myocardial microvascular function. Microvascular permeability (μP) and fractional vascular volume (FVV) can be noninvasively evaluated by electron beam CT (EBCT), but the feasibility of assessing these parameters with the 64-slice multidetector CT (CT-64) is unknown.
METHODS: We studied 12 pigs with both EBCT and CT-64 in randomized order 1-week apart, before and during IV adenosine infusion (400 μg/kg/min). Changes in myocardial attenuation in the anterior cardiac wall were assessed after a central venous injection of iopamidol (0.3 ml/kg/2 sec). EBCT scans (50 msec/image) were ECG-triggered at end-diastole, whereas CT-64 scans (330 msec/image) were acquired continuously, and end-diastolic images manually selected. Time attenuation curves were analyzed using both the indicator dilution and the Patlak models to calculate μP and FVV.
RESULTS: CT-64 and EBCT assessments of μP obtained by the Patlak method were similar both at baseline (0.37 ± 0.03 vs. 0.37 ± 0.04 AU, p = ns) and in response to adenosine (+19 ± 8% and +20 ± 14%, respectively), and correlated significantly (Figure⇓). Patlak FVV was similar between CT-64 and EBCT at baseline (0.08 ± 0.02 vs. 0.07 ± 0.02 ml blood/cc, p = ns) and during adenosine, and correlated well (r = 0.97, p < 0.01). μP and FVV estimated by the indicator-dilution method were not significantly correlated (r = 0.26 and r = 0.31, respectively).
CONCLUSION: CT-64 assessments of myocardial μP and FVV may not be reliable when using indicator-dilution analysis, likely due to its sensitivity to temporal resolution, but are feasible using the Patlak model and potentially applicable in clinical practice.