The role of magnetic resonance imaging (MRI) in the staging of prostate cancer

When staging prostate cancer, determining whether there is extracapsular invasion is an important indicator for distinguishing localized and progressive prostate cancer. There are great differences in the clinical treatment of these two types, so when selecting treatment methods for prostate cancer patients and evaluating the expected effects, it is necessary to first accurately identify whether there is extracapsular invasion.

Generally speaking, tumor growth into the fat surrounding the prostate is a more certain sign of capsule breakthrough. In addition, capsule thickening, irregular, and localized protrusions are also signs of capsule breakthrough. Literature reports that irregular capsule protrusions have a 75% chance of capsule breakthrough, while smooth protrusions have less than a 25% chance. The use of a 3.0TMR scanner to diagnose capsule invasion has further improved its effectiveness, and can reveal the range of

Other manifestations related to the staging of prostate cancer include: invasion of the neurovascular bundle around the prostate, invasion of the seminal vesicle, invasion of the pelvic floor muscles, lymph node metastasis, bone metastasis, etc. Magnetic resonance imaging can make a relatively accurate evaluation within the pelvic scanning range.

The neurovascular bundles at the posterior and lateral sides of the prostate are easily invaded by tumors, which is manifested by protruding soft tissue at the posterior and lateral sides of the prostate with the disappearance of normal neurovascular bundles, localized thickening of the neurovascular bundles or bilateral asymmetry, which can be better observed on axial T1WI. The sensitivity, specificity and accuracy of magnetic resonance imaging for diagnosing neurovascular bundle invasion are 68%-81%, 59%-72% and 64%-76%, respectively.

Localized T2WI signal reduction, wall thickening, and disappearance of the prostate seminal vesicle angle are manifestations of seminal vesicle invasion. Coronal and sagittal images are better for showing the invasion of the base of the seminal vesicle. Bleeding, endocrine therapy, and changes after radiotherapy can also cause a decrease in the T2WI signal of the seminal vesicle, which reduces the accuracy of diagnosis to a certain extent. It has been reported that the sensitivity of magnetic resonance imaging in predicting seminal vesicle invasion is 22% and the specificity is 88%.

Lymph node metastasis is the most common metastatic pathway for prostate cancer, and 7%-23% of prostate cancers can metastasize to the lymph nodes. Therefore, when performing MRI examinations on patients suspected of prostate cancer, the scanning range should include the entire pelvic cavity, from the pelvic floor to the level of the iliac vascular bifurcation, which is also the area where metastasis most often occurs. Axial fat-suppressed T2WI is more effective in observing lymph node metastasis, which manifests as high-signal nodules with clear edges, sometimes fused into lumps. Generally, lymph node metastasis can be considered when the minimum diameter is >1.0cm, but pathological results show