Table 2

CT Technical Quality in the Assessment of Subclinical Leaflet Thrombosis

Quality ScoreDescriptionEvaluation for HALT
2D Assessment (Cross-Sectional 2D MPR)
Evaluation for RELM
4D Assessment (En face 4D-VR)
1Extremely poorHALT not clearly seen with considerable artifact (HALT inconclusive)RELM/HAM inconclusive
2PoorHALT not clearly seen with no significant artifact BUT leaflet coaptation cannot be seen on a 2D MPR diastolic phase or considerable scan artifact precludes definitive assessment (HALT inconclusive)RELM/HAM inconclusive
3BorderlineHALT clearly seen on cross-sectional 2D MPR in any phase OR no HALT and leaflet coaptation can be seen on a 2D MPR diastolic phase.Leaflet motion seen, but not clear through systolic phases (RELM/HAM inconclusive)
3+GoodAs aboveLeaflet motion seen, clear through all or most systolic phases but not clear through all phases
4Very goodAs aboveLeaflet motion seen clearly through all phases
5ExcellentAs aboveLeaflet motion seen very clearly through all phases

MPR = multiplanar reconstruction; VR = volume rendered.

  • A comprehensive assessment for subclinical leaflet thrombosis requires a structural and functional assessment of the leaflets. The presence of leaflet-associated hypoattenuation, also known as hypoattenuated leaflet thickening (HALT), assessed with 2D MPR, is correlated with reduced leaflet motion (RELM), which is assessed with 4D-VR CT. Borderline or better quality scans can evaluate for HALT, but scans must be good or better to determine severity of reduced leaflet motion.

  • Single or limited phase systolic phase CT demonstrating hypoattenuation on 2D MPR and reduced leaflet excursion on 4D VR is also considered borderline in technical quality for the assessment of leaflet motion. Single and limited diastolic phases without systolic phases cannot assess for leaflet motion.