MR Fusion Transperineal Prostate Biopsy: Who is it suitable for, and how is it performed?

In men with suspected prostate cancer, biopsy is the most critical step in the diagnostic process. In recent years, advancements in imaging technology have made the biopsy procedure both more accurate and safer. Leading these advances is MR fusion transperineal prostate biopsy, a modern technique in which MRI images are combined with real-time ultrasound, and the procedure is performed through the perineum (groin area) rather than the rectum.

Why is a Prostate Biopsy Performed?

A urologist may recommend a prostate biopsy when one or more of the following conditions apply:

• PSA (prostate-specific antigen) levels are higher than expected
• A suspicious nodule or hardness is detected during a digital rectal examination (DRE)
• A suspicious region (lesion) for cancer is identified on prostate MRI imaging
• Clinical suspicion persists despite a previous negative biopsy
• Monitoring disease progression during active surveillance

The standard practice prior to a biopsy is now performing a multiparametric prostate MRI (mpMRI) first. Suspicious areas identified on MRI are scored from 1 to 5 according to the PI-RADS (Prostate Imaging-Reporting and Data System) criteria; as the score increases, the probability of cancer rises. Regions categorized as PI-RADS 3–5 are specifically targeted during the biopsy.

What is MR Fusion Biopsy?

In a conventional biopsy, the urologist visualizes the prostate with an ultrasound probe placed in the rectum and systematically samples the gland (usually from 12 distinct points)—however, ultrasound cannot directly display cancerous tissue; it merely provides an anatomical map.

In MR fusion biopsy, previously acquired MRI images are fused with real-time ultrasound images during the procedure using specialized software. This allows the physician to mark the exact suspicious point identified on the MRI onto the live ultrasound image and guide the needle directly to that region. Both targeted samples and systematic samples scanning the entire prostate are taken together; this combination significantly reduces the risk of missing clinically significant cancer.

The Transperineal Approach: How Does it Differ from Transrectal Biopsy?

Traditionally, the biopsy needle is advanced through the wall of the rectum (the terminal portion of the large intestine) to reach the prostate. The primary disadvantage of this method is the risk of introducing bacteria from the intestinal flora into the prostate or bloodstream, which can cause rare but severe cases of infection and sepsis.

In the transperineal technique, the needle is directed into the prostate through the skin region between the scrotum and anus (perineum) without entering the rectum. The prominent advantages of this approach include:

• The risk of infection is significantly lower because the needle does not come into contact with intestinal flora
• Sampling from the anterior (front) and apical (tip) regions of the prostate is more effective; cancers in these areas are sometimes missed in transrectal biopsies
• Thanks to specialized access systems developed today, the procedure can now be performed in outpatient units under local anesthesia without the need for general anesthesia

Recent studies demonstrate that there is no significant difference between transperineal and transrectal approaches in terms of cancer detection rates; however, the transperineal method stands out regarding infection safety.

How is the Procedure Performed?

1. Preparation: The patient is placed in a supine position with leg supports. Special fasting is generally not required; prophylactic antibiotics may be administered prior to the procedure.
2. Anesthesia: Local anesthetic is injected into the perineal area and around the prostate. Adequate time is given for the onset of anesthesia.
3. Imaging and Fusion: The prostate is visualized using an ultrasound probe placed in the rectum; previously obtained MRI images are fused with this live feed.
4. Sampling: Utilizing a thin guide needle introduced through the perineal skin, a total of 12–25 (or more in certain cases) tissue samples are collected from both the MRI-targeted suspicious zones and different prostate regions.
5. Completion: The entire procedure takes approximately 20–30 minutes; a pressure dressing is applied to the site.

In clinical studies, the majority of patients describe the procedure performed under local anesthesia as “mild to moderate and tolerable”; only a small fraction opt for general anesthesia.

Advantages of the Method

• Increases diagnostic accuracy by directly targeting cancerous tissue
• Substantially reduces the risk of infection and sepsis compared to the transrectal method
• Provides superior sampling of easily missed areas, such as the anterior and apical regions of the prostate
• Can be performed on an outpatient basis under local anesthesia in equipped centers
• Allows re-targeting of previously suspicious areas in patients under active surveillance

Potential Risks and Side Effects

As with any biopsy procedure, certain risks exist:

• Transient blood in the urine or semen (hematuria/hematospermia)
• Mild pain, bruising, or tenderness in the perineal region
• Rarely, temporary difficulty urinating (urinary retention)
• Extremely rare incidence of infection (markedly lower compared to the transrectal method)
• Possibility of a false-negative result. Cancer cells may still be present in the prostate even if the biopsy is negative

If symptoms such as fever (above 38°C), chills, excessive sweating, or an inability to urinate occur, patients are advised to contact the treating medical center without delay.

Why Choose Hospitals with Interventional Radiology Units?

The success of an MR fusion transperineal biopsy depends heavily on the technical quality of the image fusion. Fusing MRI and ultrasound images with millimeter precision is a process that requires advanced imaging expertise. Therefore, it is strongly recommended to have the procedure performed in multidisciplinary hospitals equipped with dedicated interventional radiology units. The advantages offered by such centers include:

• Radiology and urology teams jointly evaluate the MRI images to formulate a unified biopsy plan
• Fusion software and imaging equipment undergo regular calibration and quality control
• Immediate, under-one-roof intervention capability in the event of potential post-procedure complications (e.g., bleeding or suspected infection)
• An experienced interventional radiology team enhances targeted sampling accuracy, especially in small or anatomically challenging lesions