MRI Blood-Flow Imaging Predicts Bladder Cancer Aggressiveness Without Contrast

A prospective single-center study of 68 patients with pathologically confirmed bladder urothelial carcinoma reports that a contrast-free MRI approach combining arterial spin labeling perfusion imaging with diffusion-weighted imaging can noninvasively assess tumor aggressiveness and muscular invasion before surgery. The findings are published in BMC Medical Imaging.

All patients underwent preoperative RESOLVE diffusion-weighted imaging and 3D pseudo-continuous arterial spin labeling (3D-pCASL) MRI. The cohort included 22 patients with muscle-invasive bladder cancer (MIBC) and 46 with non-muscle-invasive disease (NMIBC). Pathological grading and muscle invasion status are critical determinants of treatment strategy and prognosis in bladder cancer, and noninvasive, contrast-free multiparametric imaging approaches capable of preoperatively characterizing tumor biology are clinically needed.

The study found that high-grade tumors showed higher tumor blood flow and lower apparent diffusion coefficient (ADC) values than low-grade tumors. Blood flow measured 94.2 ± 38.4 versus 38.9 ± 14.6 mL/min/100 g, and ADC values were 0.954 (0.803–1.047) versus 1.206 (1.097–1.295) × 10⁻³ mm²/s, with both differences reaching P < 0.0001.

Blood flow was also significantly higher in muscle-invasive tumors than in non-muscle-invasive tumors, at 83.90 (51.75–113.75) versus 50.00 (34.25–68.50) mL/min/100 g (P = 0.0059). In contrast, ADC showed no significant difference between the invasion groups (P = 0.6695), indicating that perfusion, rather than diffusion, carried the signal for muscular invasion in this cohort.

To predict tumor grade, the researchers built a multivariable logistic regression model integrating ADC and blood flow, validated internally with 2,000 bootstrap resamples. The combined ADC–BF model achieved an area under the curve of 0.980 (95% CI: 0.954–1.000), with 91.7% sensitivity and 96.9% specificity. Bootstrap validation yielded an optimism-corrected AUC of 0.976.

The combined model outperformed ADC alone (DeLong test, P = 0.0004) but was not significantly better than blood flow alone (P = 0.0597). Blood flow by itself achieved an AUC of 0.931 for tumor grading and 0.736 for predicting muscular invasion.

The imaging measures also correlated with molecular markers of tumor biology. ADC was negatively correlated with Ki-67, a marker of cell proliferation, while blood flow was positively correlated with CD34 expression, a marker associated with tumor vascularity. This supports the interpretation that diffusion reflects tumor cellularity and perfusion reflects vascular supply.

The authors conclude that RESOLVE DWI and 3D-pCASL MRI provide complementary noninvasive biomarkers supporting preoperative assessment of bladder cancer grade and muscle invasion.

The study’s limitations are substantial: it was conducted at a single center with 68 patients, and the authors state that further validation in larger multicenter cohorts is required to confirm the generalizability of these findings. The reported performance figures derive from internal validation rather than independent external testing.

Subject of Research: Arterial spin labeling MRI for noninvasive assessment of bladder tumor grade and muscle invasion

Article Title: Exploring arterial spin labeling for bladder cancer: noninvasive assessment of tumor aggressiveness and muscular invasion

Article References: Qin, S., Hong, Y., Fu, C., Kuehn, B., & Lv, Q. (2026). Exploring arterial spin labeling for bladder cancer: noninvasive assessment of tumor aggressiveness and muscular invasion. BMC Medical Imaging. https://doi.org/10.1186/s12880-026-02956-2

Image Credits: AI Generated

DOI: 10.1186/s12880-026-02956-2

Keywords: bladder cancer, arterial spin labeling, MRI, diffusion-weighted imaging, tumor grading, muscle invasion, perfusion imaging, ADC, biomarkers, radiology, Exploring, arterial