Emerging research suggests that iodine density (ID) measurements derived from photon-counting detector computed tomography (PCD-CT) provide better differentiation of portal vein thrombosis (PVT) than conventional CT.
For the retrospective study, recently reported in European Radiology, researchers evaluated the use of PCD-CT for differentiating between bland PVT and neoplastic DVT in 104 patients (mean age of 65). The subgroups within the cohort included 29 patients with hepatocellular carcinoma (HCC) and neoplastic PVT; 18 patients with HCC and bland PVT; 31 patients with bland PVT and no malignancy; and 26 patients with neoplastic PVT from non-HCC malignancies, according to the study.
The study authors found that PCD-CT-derived ID achieved 100 percent sensitivity and 95.9 percent specificity in late arterial phase (LAP) imaging. In the portal venous phase (PVP), ID provided a 93.1 percent sensitivity and 100 percent specificity, according to the researchers. Iodine density with PCD-CT had 98 percent and 97 percent AUCs in the LAP and PVP respectively.
In contrast, the researchers noted that the CT feature-based score, incorporating vessel infiltration, thrombus extension and arterial hyperenhancement, offered sensitivity of 89.7 percent, specificity of 81.6 percent and an 86 percent AUC with a CT score threshold of > 1. For a CT score threshold of > 2, there was an 86.2 percent sensitivity rate, a 95.9 percent specificity rate and 91 percent AUC, according to the study authors.
“Accurate identification of neoplastic PVT has direct therapeutic implications, as its presence constitutes a decisive factor in the BCLC classification, precluding curative options such as resection or transplantation and guiding the choice toward systemic or locoregional treatments. Reliable PCD-CT-based differentiation of bland versus neoplastic thrombi may therefore improve treatment allocation and patient outcomes,” noted lead study author Lukas Muller, M.D., who is affiliated with the Department of Diagnostic and Interventional Radiology at the University Medical Center Mainz in Mainz, Germany, and colleagues.
Three Key Takeaways
- PCD-CT iodine density improves diagnostic accuracy. Iodine density (ID) measurements from photon-counting detector CT (PCD-CT) showed very high performance for differentiating bland vs. neoplastic portal vein thrombosis, with up to 100 percent sensitivity and 95.9 percent specificity in the late arterial phase and 93.1 percent sensitivity with 100 percent specificity in the portal venous phase.
- Outperforms conventional CT feature scoring. ID-based assessment demonstrated higher diagnostic accuracy (AUC 97–98 percent) compared with traditional CT feature-based scoring systems (AUC 86–91 percent), suggesting iodine density measurement with PCD-CT may be a more reliable diagnostic tool.
- Phase selection matters in non-HCC malignancies. For non-HCC tumors, iodine density measurements in the portal venous phase provide significantly better sensitivity than late arterial phase imaging.
For patients with non-HCC malignancies, the researchers emphasized ID measurements during the PVP in light of the reduced sensitivity for PCD-CT-derived ID in LAP in this cohort (69 percent vs. 92 percent for PVP).
“ … Non-HCC malignancies frequently exhibit enhancement patterns resembling those of their respective primary tumors and are therefore often hypodense relative to the surrounding liver parenchyma, whereas HCC typically demonstrates strong arterial hyperenhancement. Nevertheless, because non-HCC lesions represent solid structures with at least partial contrast uptake, ID tends to increase during the portal venous phase, which likely accounts for the improved sensitivity in this setting,” added Muller and colleagues.
(Editor’s note: For related content, see “Can Photon-Counting CT Enhance the Detection of Obstructive CAD?,” “Can Photon-Counting CT Bolster Myocardial Extracellular Volume Quantification Beyond EID-CT?” and “Photon-Counting Study Examines Impact of Scan Mode on Radiation Dosing for CCTA in Patients with Non-Acute Chest Pain.”)
Beyond the inherent limitations of a single-center retrospective study, the authors acknowledged that differences between the patient groups with respect to cirrhosis as well as underlying liver disease may have had an impact on iodine density measurements. The researchers also conceded that all PCCT scans were performed with one scanner and consistent use of contrast media.
