Current Staging Procedures in Urinary Bladder Cancer

Abstract

Currently computed tomography (CT) represents the most widely used standard imaging modality in muscle-invasive urinary bladder cancer. Visualization of local tumor or depth of invasion as well as lymph node staging, however, is often impaired. Magnetic resonance imaging (MRI) with diffusion-weighted sequences, determination of apparent diffusion coefficient (ADC) values or utilization of superparamagnetic iron nanoparticles potentially exhibits advantages in the assessment of local tumor or lymph node involvement and therefore might play a role in routine staging of urinary bladder cancer in the future. Likewise, positron emission tomography (PET) with the currently utilized tracers (18)F-FDG, (11)C-choline and (11)C-acetate is investigated in bladder cancer patients-mostly in combination with diagnostic CT. Although promising results could be obtained for these PET/CT examinations in smaller series, their true value cannot be determined at present.

Keywords: FDG; MRI; PET/CT; actetate; choline; urinary bladder cancer.

Figure 1

Large bladder tumor visualized by contrast enhanced computed tomography (CT) reaching the acetabulum on the left side and infiltrating the perivesical fatty tissue (A). Note there is an additional spinal metastasis in L5 (B, sagittal reformatted CT), seen as a destructive lesion in L5 with sintering of the vertebra. This is confirmed by MRI: the lesion is seen hypointense in T1w, confirming infiltration of the bone marrow by tumor tissue (C, T1w sagittal).

Figure 2

Bladder tumor at dorsal bladder wall visualized by CT as a wall thickening with contrast enhancement (A). Of note, soft tissue contrast is superior in MRI compared to CT (B, T2w axial). Additional diffusion weighted imaging (DWI; C–F) improves delineation of the tumor mass as a hyperintense mass in the b-value images (D, b800 image) and allows evaluating apparent diffusion coefficient (ADC) values (C) as potential marker of tumor cellularity. Moreover, DWI might be helpful for evaluating lymph node metastasis, as metastatic lymph nodes usually also show lower ADC values (F, b800 image showing a hyperintense iliacal lymph node on the right; E, low ADC value suggests malignancy).

Figure 3

Bladder tumor with tracer uptake in the right posterior-lateral bladder wall as visualized by ¹¹Choline-PET/CT. Note that there is excellent delineation of tumor and bladder lumen due to the fact that ¹¹C-Choline is usually not excreted by the urine (A: fused dataset). However, anatomical detail is superior in the contrast enhanced CT part of the PET/CT (B). Note the hypervascularized tumor involving the right ureteral orifice with consecutive dilatation of the right ureter.