Photoacoustic Imaging of the Bladder

ladder cancer is the second most common cancer of the genitourinary tract, accounting for 7% of all new cancer cases in men and 2% of new cancer cases in women.1 Patients typically present with hematuria, which may be gross or microscopic, and can have symptoms of urinary frequency, urgency, or dysuria.1 Pathologic stage T1 tumors are treated with complete transurethral resection and often with intravesical immunotherapy or chemotherapy, whereas pathologic stage T2 tumors are generally treated with radical cystectomy. Currently, clinical staging is limited by the lack of accuracy in available preoperative imaging modalities, such as transabdominal sonography, computed tomography, and magnetic resonance imaging, with overall staging accuracy ranging from 40% to 85% for computed tomography and 50% to 90% for magnetic resonance imaging.2,3 The biggest limitation of imaging is determining the presence of muscularis propria invasion.4 Because transurethral resection of pathologic T1 bladder tumors may result in considerable understaging,5 second-look transurethral resection procedures are routinely performed to eliminate this possibility.6 However, deep biopsy of bladder tumors may lead to bladder perforation, requiring surgical repair and increasing the risk of tumor seeding. If an imaging modality existed that could lessen the understaging errors inherent to transurethral resection, the surgeon could proceed directly to radical cystectomy in patients with pathologic T2 tumors. Therefore, there is a need for accurate staging of bladder cancer to assess tumor depth to help guide appropriate treatment and obviate the need for invasive procedures. Aya Kamaya, MD, Srikant Vaithilingam, MS, Benjamin I. Chung, MD, Omer Oralkan, PhD, Butrus T. Khuri-Yakub, PhD