Pelvic cardiovascular magnetic resonance venography: venous changes with patient position and hydration status.

BACKGROUND: To determine the effect of hydration as well as prone versus supine positioning on the pelvic veins during cardiovascular magnetic resonance (CMR) venography.

METHODS: Under institutional review board approval, 8 healthy subjects were imaged with balanced steady state free precession, non-contrast CMR venography to measure common and external iliac vein volumes and common femoral vein cross-sectional area in the supine, prone and decubitus positions after dehydration and again following re-hydration. CMR venography from 23 patients imaged both supine and prone were retrospectively reviewed and measurements of common femoral and iliac veins areas were compared using Wilcoxon test.

RESULTS: Common femoral vein area on CMR venography increased with prone positioning (83 ± 35 mm2 ) compared to supine positioning (59 ± 21 mm2 ) (p = 0.02) and further increased with hydration to 123 ± 44 mm2 (p < 0.01). With right and left side down decubitus positioning, the common femoral vein area on dehydration increased from 29 ± 17 mm2 in the ante-dependent position to 134 ± 36 mm2 in the dependent position (p < 0. 001). Similarly, common and external iliac veins increased in volume with prone, 5.4 ± 1.9 cm3 and 5.8 ± 1.9 cm3 compared to supine positioning 4.6 ± 1.8 cm3 and 4.5 ± 1.9 cm3 (p = 0.01) and further increase with hydration to 6.7 ± 2.1 cm3 and 6.3 ± 1.9 cm3 (p = 0.01). CMR venography on patients also demonstrated an increase in mean common femoral vein luminal area from 103 ± 44 mm2 in supine position to 151 ± 52 mm2 with prone positioning (p < 0.001) as well as increases in common and external iliac vein volumes from 6.5 ± 2.6 cm3 and 8.0 ± 3.4 cm3 in the supine position to 7.5 ± 2.5 cm3 and 9.3 ± 3.6 cm3 with prone positioning (p < 0.01).

CONCLUSIONS: Common femoral and common/external iliac vein size on CMR venography may be affected by position and hydration status. Routine clinical CMR venography of the pelvis could include prone positioning and avoiding dehydration to maximize pelvic vein distension.