Abstract 2232: 64-MDCT Provides Lower CT Numbers than EBCT in Coronary Artery Calcium Scans
Objective: To determine systematic differences in CT numbers between 64-slice multi-detector CT (64-MDCT) and electron beam CT (EBCT) using a calibration phantom that was scanned with the same patients on the same day on both scanners using coronary artery calcium (CAC) protocols.
Methods: As part of the community-based Epidemiology of Coronary Artery Calcification Study, a single calibration phantom was included in the scan field for 122 participants who underwent coronary CAC scanning on 64-MDCT and EBCT on the same day. The calibration phantom was placed under the participants’ body during scanning and moved between scanners with the participant. The calibration phantom had 3 sections with different concentrations of calcium hydroxyapatite (150, 75, 0 mg/cc). For all scans, the slice containing the origin of the left main (LM), the posterior descending coronary artery (PDA), and a location 9 mm below the diaphragm (DIA) were selected. For each section, CT numbers were measured at each selected level for 64-MDCT and EBCT, yielding a total of 9 comparisons (3 section x 3 anatomic levels). The CT numbers for 64-MDCT and EBCT were compared with a paired t-test.
Findings: CT numbers were significantly lower on 64-MDCT than EBCT for all 3 calcium densities at all 3 anatomic levels (p<0.0001 for all). Table 1⇓.
Conclusions: 64-MDCT produces lower CT numbers than EBCT for the same calcium concentrations. This may contribute to differences in the presence and quantity of CAC measured with 64-MDCT as compared to EBCT.