Preoperative assessment of muscle invasion in bladder cancer is central to treatment planning. An analysis in Insights into Imaging compares a dual-energy CT-based model with the vesical imaging reporting and data system for this task. Because management differs sharply between non-muscle-invasive and muscle-invasive disease, reliable staging before surgery matters. Using a prospective patient cohort, the evaluation tests whether quantitative dual-energy CT parameters combined with tumour diameter can improve accuracy, particularly in equivocal cases, smaller lesions and situations where MRI cannot be performed.
Why Preoperative Staging Remains Difficult
Preoperative staging in bladder cancer depends on separating non-muscle-invasive disease from muscle-invasive disease. That distinction shapes treatment decisions, from local resection to more extensive surgery and systemic therapy. Transurethral resection remains central to diagnosis and staging because it provides tissue for pathological analysis, but it is invasive and may miss the full extent of tumour invasion because of sampling limits. Quality can also vary with surgical technique.
Must Read: MRI Model for Bladder Cancer Staging
MRI has improved this process through structured scoring. The vesical imaging reporting and data system uses a five-point scale to estimate the likelihood of muscle invasion and has shown strong diagnostic performance. Even so, it still depends on visual interpretation, which can make assessment less consistent in intermediate cases. MRI is also not suitable for every patient, including some with implants, severe claustrophobia or difficulty remaining still during scanning.
Dual-energy CT offers another option. By using two energy levels, it can better distinguish tissues that look similar on conventional CT. It also provides quantitative measurements that reflect tissue composition and tumour behaviour. That makes it a possible tool for improving preoperative staging in bladder cancer.
How the Model Performs
The dual-energy CT model combines tumour diameter with several quantitative imaging parameters. These include iodine concentration, normalised iodine concentration, spectral curve slope and effective atomic number, measured in the tumour and at the tumour base. These values help capture changes linked to invasive growth, especially where the tumour meets the bladder wall.
On its own, dual-energy CT showed moderate diagnostic performance. When tumour diameter was added, performance improved clearly. The combined model reached an area under the curve close to that of the MRI-based scoring system, while also delivering better specificity. That means it was better at reducing false-positive classifications.
The benefits were especially clear in harder cases. In lesions with intermediate MRI scores, where diagnosis is often uncertain, the combined dual-energy CT model performed better than the MRI-based system. It also showed strong results in lesions smaller than 3 cm, where accurate staging can be more difficult. These findings suggest that quantitative CT data can help reduce uncertainty when visual scoring alone is less reliable.
Value in Difficult Cases
Intermediate-score lesions are a major challenge because uncertainty can lead either to delayed treatment or to more aggressive treatment than needed. A quantitative model helps address that problem by adding objective measurements to the decision process. In this setting, the combined dual-energy CT model gave stronger and more stable results than standard visual assessment.
High specificity is an important strength here. Fewer false positives can help avoid overstaging and unnecessary aggressive treatment. In small lesions, the model also maintained a better balance between sensitivity and specificity than the MRI-based score alone. This suggests that quantitative imaging may be particularly useful when tumour size or appearance makes assessment less straightforward.
The approach may also be useful for patients who cannot undergo MRI. Dual-energy CT is already part of routine imaging pathways in many centres and does not depend on the same conditions as MRI. The article also describes a nomogram and a web-based risk calculator designed to support clinical use. Feature analysis identified tumour diameter and iodine concentration at the tumour base as the strongest predictors, pointing to the importance of tumour size and tumour-wall interaction in assessing invasion.
The dual-energy CT-based model provides a practical way to assess muscle invasion in bladder cancer before surgery. When combined with tumour diameter, it achieves diagnostic accuracy close to MRI-based scoring and improves specificity. Its value is especially clear in equivocal cases and in smaller lesions, where standard assessment may be less stable. For patients who cannot undergo MRI, it offers a credible imaging alternative for preoperative staging and risk assessment.
Source: Insights into Imaging
References:
Sun M, Wang J, Luo J et al. (2026) Assessment of multi-parameter dual-energy CT in predicting muscle invasion in bladder cancer: comparison with VI-RADS. Insights Imaging; 17, 96.
