Bladder cancer is a major health concern, ranking among the most common malignancies worldwide and one of the costliest to treat. Accurate imaging plays a crucial role in diagnosis and treatment planning.

The classification of bladder cancer into non-muscle-invasive (NMIBC) and muscle-invasive (MIBC) forms is based on whether the tumor has infiltrated the muscle layer. This distinction significantly influences clinical management strategies and prognosis. While NMIBC is typically managed through transurethral resection of bladder tumors (TURBT), MIBC often requires radical cystectomy as the standard treatment.

Staging currently relies on a combination of clinical evaluation, histology, and imaging, with TURBT remaining the gold standard for local assessment. Computed tomography (CT) and MRI are primarily employed to detect lymph node involvement or distant metastases.

However, TURBT presents a notable risk of understaging, particularly when the sample does not include detrusor muscle. This can lead to treatment delays or inadequate therapy, potentially worsening patient outcomes. Accurate assessment of muscle invasion is therefore crucial.

In recent years, multiparametric magnetic resonance imaging (mpMRI) has emerged as an essential tool for the diagnosis and staging of bladder tumors.

The Vesical Imaging Reporting and Data System (VI-RADS) introduced in 2018, provides a standardized framework for evaluating bladder tumors using mpMRI, by combining T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences, this system assigns a five-point score to estimate the likelihood of muscle invasion, thereby improving diagnostic accuracy and aiding clinical decision-making.

ANATOMIC OVERVIEW

• The bladder is a subperitoneal, hollow muscular organ that acts as a reservoir for urine. It is located in the lesser pelvis when empty and extends into the abdominal cavity when full
• Anatomically, the bladder is contiguous with the ureters above and the urethra below. It is divided into four anatomical parts: the apex or dome, body, fundus, and neck.
• The bladder is situated just posterior to the pubic symphysis. Posteriorly, the anterior wall of the vagina sits behind the bladder in females. In males, the rectum is located posterior to the bladder. Inferiorly, the muscles of the pelvic diaphragm support the bladder.

==>The bladder wall is made of many layers, including:

• Urothelium or transitional epithelium: This is the layer of cells that lines the inside of the kidneys, ureters, bladder, and urethra. Cells in this layer are called urothelial cells or transitional cells.
• Lamina propria: This is the next layer around the urothelium. It’s a type of connective tissue.
• Detrusor muscle (muscularis propria): This is the outer layer. It’s the thick smooth muscle tissue outside the lamina propria.
• Fatty connective tissue: This covers the outside of the bladder and separates it from other organs.