Improving Diagnostic Accuracy with TRUS/MRI Fusion Guided Biopsy
2022-07-01
Special Thanks to the Urology Subprofessional Group, Department of Ultrasound medicine, The 10th People's Hospital affiliated to Tongji University.
Key Points
- Prostate cancers can appear isoechoic and be missed on standard grayscale TRUS imaging.
- MRI is highly sensitive for prostate cancer diagnosis, but MRI guided biopsies are complicated and expensive.
- Targeted prostate biopsy using TRUS/MRI iFusion guidance can improve diagnostic accuracy for prostate cancer.
Case Description
A 72 year-old man with a history of increased prostate specific antigen (PSA 7.9 ng/ml) was sent to the department of ultrasound at the 10th People’s Hospital affiliated to Tongji University for treatment. A transrectal ultrasound prostate examination (TRUS) and multiparameter MRI were performed with results as follows:?
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Multi-parameter MRI findings:?
- Suspected lesion in the right anterior lobe of the prostate (PI-RADS classification 4).
- Prostatic hyperplasia with calcifications and small prostatic cysts.
TRUS finding (figure 1):?
- Prostatic hyperplasia with calcifications and small prostatic cysts.
- Heterogeneous prostatic echotexture with no discrete lesion identified.
Preoperative discussion: As the suspicious lesion could not be identified on conventional ultrasound, the patient was scheduled for a targeted perineal prostate 12-point systemic needle biopsy under TRUS/MRI fusion guidance.
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TRUS/MRI Fusion guided biopsy protocol:
Step 1: The appropriate MRI sequence (Figure 2) was selected and the dataset imported onto the Resona 9 and into the live ultrasound exam.
Step 2:?Using Mindray’s iFusion software, the TRUS and MRI images were aligned and fused (Figure 3) and the target was labeled (Figure 4).
Step 3:?To verify the lesion location, a contrast enhanced ultrasound (CEUS) was performed using the MRI image for anatomical reference (Figure 5).
Step 4:?Under TRUS/MRI fusion guidance, a 12 core systemic biopsy was performed, followed by a targeted biopsy including 3 samples from the suspected lesion. (Figure 6) No complications were seen post procedure.
Pathology result: All 12 systemic punctures demonstrated benign prostatic hyperplasia. One of the three targeted punctures revealed prostatic adenocarcinoma.
Discussion and reflection
TRUS-guided biopsy combined with PSA is an important method for the diagnosis of prostate cancer (PCa). Peripheral zone hypoechoic nodules are a typical sign of PCa, however, in early PCa these lesions appear isoechoic in many cases which makes differentiation from prostatic hyperplasia and low-grade prostatic intraepithelial neoplasia difficult and can result in missed diagnosis [1]. In this case, PSA was increased, but no suspicious lesions were detected on TRUS imaging.
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Systemic biopsy is the current main diagnostic method for PCa. As the biopsy sites are standardized rather than targeted at a particular suspicious lesion, this method may also result in missed diagnosis or underestimation of disease. Multi parameter MRI has a high sensitivity and specificity for the diagnosis of PCa, however, MRI guided biopsy is complicated and expensive. Mindray iFusion software on the Resona 9 provides a solution by fusing the MRI dataset with live ultrasound imaging. Using bi-plane TRUS/MRI fusion guidance for targeted prostate biopsy improves the accuracy of clinical prostate cancer diagnosis [2].
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In this case, the suspicious lesion was detected on MRI and using iFusion navigation the corresponding plane and target area were labeled on ultrasound. A CEUS exam provided additional diagnostic information and three guided biopsies were performed into the suspect area. While the standard 12-point samples were negative, one of the targeted samples came back positive for PCa. This case clearly shows how biplane TRUS/MRI fusion targeted biopsy can help avoid missed diagnosis and improve diagnostic accuracy.
References:
1. HUANG Haiming, XU Haiyan, CHEN Yane, ZHANG Zhongxin. Application value of guided prostate puncture under ultrasonic magnetic resonance. JOURNAL OF MINIMALLY INVASIVE UROLOGY, 2021, 10(1): 50-54.
2.Moore CM, Robertson NL, Arsanious N, et al. Image-guided prostate biopsy using magnetic resonance imaging-derived targets: a systematic review. Eur Urol. 2013. 63(1): 125-140.