Dynamic MRI of Bladder Cancer: Evaluation of Staging Accuracy
Dynamic MRI of Bladder Cancer: Evaluation of Staging Accuracy
Objective: The purpose of this study was to evaluate the accuracy of gadoliniumenhanced MRI in staging bladder cancer in a series of patients with surgically proven bladder cancer.
Materials and Methods: Seventy-one patients with biopsy-proven bladder cancer underwent MRI on a 1.5-T scanner with a phased-array pelvic coil. Conventional T1-weighted spin-echo, T2-weighted spin-echo, and unenhanced and enhanced (0.1 mmol/kg gadolinium) fast spoiled gradient-echo images with fat suppression were obtained. Two blinded reviewers evaluated the MR images and assigned a stage that was compared with the pathologic stage (n = 67) or with clinical follow-up for at least 2 years after MRI (n = 4).
Results: Agreement among the reviewers was good in assigning a radiologic stage for bladder cancer (kappa = 0.80). On a stage-by-stage basis, MRI accuracy was 62%, and overstaging was the most common error (32%). Staging accuracy improved to 85% and 82% in differentiating superficial from invasive tumors and organ-confined from non-organ-confined tumors, respectively. The time interval between MRI and transurethral resection (≤ 60 days and ≥ 61 days) was not a statistically significant factor in differentiating superficial from invasive and organ-confined from non-organ-confined tumors (p > 0.05). MRI accuracy in staging transitional cell carcinoma was not significantly different from that obtained in staging non–transitional cell carcinoma (p > 0.05).
Conclusion: MRI shows good reproducibility between reviewers for staging bladder cancer. Although overall staging accuracy was only moderate, the accuracy for differentiating superficial versus invasive disease and organ-confined versus non-organ-confined disease was high.
Carcinoma of the urinary bladder is one of the more common malignant tumors of the urinary tract in both male and female patients. Accurate preoperative staging is the most important factor in determining the appropriate management of bladder carcinoma because the therapeutic method chosen and prognosis depend on the clinical and radiologic stage at presentation. Superficial tumors can be treated by local endoscopic resection with or without adjuvant installation of chemotherapeutic agents, whereas invasive tumors are treated by curative cystectomy or by palliative chemotherapy or radiation therapy. Clinical staging can differentiate superficial tumors from invasive tumors. However, clinical staging is not reliable for determining tumor extension beyond the bladder wall; therefore, imaging of the urinary bladder and the extravesical pelvis is needed. Patients with extravesical tumors show significantly higher recurrence rates and worse survival than those with organ-confined tumors. Therefore, distinguishing between organ-confined and non-organ-confined tumors is essential.
Prior studies have reported that CT was a valuable tool in staging bladder carcinoma. MRI with dynamic contrast administration has been shown to be superior to CT, particularly in detecting superficial and multiple tumors and in detecting extravesical tumor extension and surrounding organ invasion.
The purposes of this study were to evaluate the overall accuracy of state-of-the-art dynamic gadolinium-enhanced MRI in staging bladder cancer on a stage-by-stage basis and to determine the usefulness of MRI in determining organ-confined versus non-organ-confined disease, which is the main objective of imaging these patients.
Objective: The purpose of this study was to evaluate the accuracy of gadoliniumenhanced MRI in staging bladder cancer in a series of patients with surgically proven bladder cancer.
Materials and Methods: Seventy-one patients with biopsy-proven bladder cancer underwent MRI on a 1.5-T scanner with a phased-array pelvic coil. Conventional T1-weighted spin-echo, T2-weighted spin-echo, and unenhanced and enhanced (0.1 mmol/kg gadolinium) fast spoiled gradient-echo images with fat suppression were obtained. Two blinded reviewers evaluated the MR images and assigned a stage that was compared with the pathologic stage (n = 67) or with clinical follow-up for at least 2 years after MRI (n = 4).
Results: Agreement among the reviewers was good in assigning a radiologic stage for bladder cancer (kappa = 0.80). On a stage-by-stage basis, MRI accuracy was 62%, and overstaging was the most common error (32%). Staging accuracy improved to 85% and 82% in differentiating superficial from invasive tumors and organ-confined from non-organ-confined tumors, respectively. The time interval between MRI and transurethral resection (≤ 60 days and ≥ 61 days) was not a statistically significant factor in differentiating superficial from invasive and organ-confined from non-organ-confined tumors (p > 0.05). MRI accuracy in staging transitional cell carcinoma was not significantly different from that obtained in staging non–transitional cell carcinoma (p > 0.05).
Conclusion: MRI shows good reproducibility between reviewers for staging bladder cancer. Although overall staging accuracy was only moderate, the accuracy for differentiating superficial versus invasive disease and organ-confined versus non-organ-confined disease was high.
Carcinoma of the urinary bladder is one of the more common malignant tumors of the urinary tract in both male and female patients. Accurate preoperative staging is the most important factor in determining the appropriate management of bladder carcinoma because the therapeutic method chosen and prognosis depend on the clinical and radiologic stage at presentation. Superficial tumors can be treated by local endoscopic resection with or without adjuvant installation of chemotherapeutic agents, whereas invasive tumors are treated by curative cystectomy or by palliative chemotherapy or radiation therapy. Clinical staging can differentiate superficial tumors from invasive tumors. However, clinical staging is not reliable for determining tumor extension beyond the bladder wall; therefore, imaging of the urinary bladder and the extravesical pelvis is needed. Patients with extravesical tumors show significantly higher recurrence rates and worse survival than those with organ-confined tumors. Therefore, distinguishing between organ-confined and non-organ-confined tumors is essential.
Prior studies have reported that CT was a valuable tool in staging bladder carcinoma. MRI with dynamic contrast administration has been shown to be superior to CT, particularly in detecting superficial and multiple tumors and in detecting extravesical tumor extension and surrounding organ invasion.
The purposes of this study were to evaluate the overall accuracy of state-of-the-art dynamic gadolinium-enhanced MRI in staging bladder cancer on a stage-by-stage basis and to determine the usefulness of MRI in determining organ-confined versus non-organ-confined disease, which is the main objective of imaging these patients.