TRUS bests MRI for identifying prostate cancer

2017 06 15 10 31 55 42 Prostate 400

Combining ultrasound techniques on transrectal ultrasound (TRUS) better identifies prostate cancer than using these techniques alone -- and finds the disease more effectively than multiparametric MRI, according to a study published in the July issue of the Journal of Ultrasound in Medicine.

The findings suggest that a multiparametric ultrasound exam -- one that combines grayscale imaging, color Doppler imaging, shear-wave elastography (SWE), and contrast-enhanced ultrasound -- could be an effective tool for this application, wrote a team led by Dr. Mingbo Zhang of the General Hospital of the People's Liberation Army in Beijing.

"Early detection of localized prostate cancer plays a critical role in planning treatment with radical prostatectomy," the group wrote. "Conventional TRUS is widely used in the guidance of prostate biopsies. However, it is not recommended to use conventional TRUS alone in the diagnosis because of its low sensitivity in optimizing small prostate cancer lesions."

Prostate cancer is common among men around the world, and its incidence in China has increased in recent decades. Identifying it early is crucial, the group noted. Typically, a digital rectal examination, prostate-specific antigen (PSA) screening, and conventional transrectal ultrasound are used to diagnose prostate cancer, but their performance is limited.

Multiparametric MRI is another tool for diagnosing, staging, and monitoring prostate cancer, but it carries high costs, longer exam times than TRUS, and contraindications such as claustrophobia. That's why multiparametric TRUS could be a good option, the authors wrote.

To explore the use of combined TRUS for this application, the researchers conducted a study that included 78 patients imaged between April 2016 and July 2017. Of these, 40 had healthy prostates and 38 had localized prostate cancers. The ultrasound exams consisted of grayscale imaging, color Doppler imaging, SWE, and contrast-enhanced ultrasound; the MRI exams consisted of T2-weighted, diffusion-weighted, and dynamic contrast-enhanced MRI (J Ultrasound Med, July 2019, Vol. 38:7, pp. 1823-1830).

Zhang and colleagues found that multiparametric TRUS performed better than MRI, with higher sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and area under the curve (AUC). Of the 38 patients with prostate cancer, almost one-third (28.9%) had lesions invisible on conventional TRUS.

MRI vs. TRUS for detecting prostate cancer
Performance measure MRI TRUS
Sensitivity 94.7% 97.4%
Specificity 60% 92.5%
PPV 69.2% 88.5%
NPV 92.3% 96.9%
Accuracy 76.9% 87.2%
AUC 0.77 0.87

"None of the conventional TRUS, SWE, and CEUS methods alone could provide a valid diagnosis of prostate cancer. However, multiparametric TRUS had better diagnostic performance," the team wrote. "Although MRI showed high sensitivity and negative predictive value, the specificity and positive predictive value were lower than multiparametric TRUS."

The study results suggest that using multiparametric TRUS could improve prostate cancer patients' care and outcomes, according to the group.

"With the use of multiparametric TRUS, patients might avoid unnecessary biopsy and have reduced related medical costs and complications, although more data are needed to support this idea," the researchers concluded.

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