Spectral detector CT-derived reconstructions for assessment of extramural venous invasion in rectal cancer

To investigate the diagnostic performance of spectral detector CT (SDCT)-derived reconstructions, including iodine density overlay maps (IDOM) and virtual monoenergetic images at 40 keV (VMI_40keV), in assessing extramural venous invasion (EMVI) in rectal cancer.

Patients with rectal cancer who underwent preoperative SDCT and MRI followed by surgery were retrospectively enrolled. Two radiologists independently evaluated EMVI status using conventional images (CI), IDOM, VMI_40keV, and MRI, respectively. Sensitivity, specificity, and accuracy were calculated using histopathological findings as the reference standard.

Among the 78 enrolled patients (mean age, 60 years ± 13 [standard deviation]; 42 males), 22 had pathologically confirmed EMVI. IDOM demonstrated the highest sensitivity (68.2 %), followed by VMI_40keV and MRI (both 59.1 %), while CI showed a much lower sensitivity (27.3 %). Compared with CI, IDOM, VMI_40keV, and MRI showed significantly higher sensitivity (P = 0.004, 0.016, and 0.016, respectively). However, no significant differences were observed among IDOM, VMI_40keV, and MRI (all P > 0.05). Specificities ranged from 87.5 % to 94.6 % across all modalities, with no significant differences (all P > 0.05). IDOM showed the highest accuracy (85.9 %), followed by VMI_40keV (83.3 %), MRI (79.5 %), and CI (75.6 %). Compared with CI, all three modalities demonstrated significantly improved accuracy (P = 0.002, 0.008, and < 0.001, respectively), although no significant differences were found among IDOM, VMI_40keV, and MRI (all P > 0.05).

IDOM and VMI40_keV derived from SDCT, as well as MRI showed no statistically significant differences in diagnostic performance relative to one another. All three modalities were superior to CI in the detection of EMVI.