Exploring different imaging technologies for prostate cancer

Exploring different imaging technologies for prostate cancer
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Did you know that estimates from published studies indicate that 50% of men older than 50 years of age have prostate cancer? Learn more about the technologies for prostate cancer.

New technologies, such as biomedical imaging, for the early detection of prostate cancer can save lives. Here, we delve into the different imaging technologies for prostate cancer.

The prostate

Found only in men, the prostate is a small gland in the pelvis. It is located between the penis and the bladder, surrounding the urethra. Prostate cancer is currently the most common cancer in men and the second leading cause of cancer related deaths among men in the United States. In 2017, it was estimated that prostate cancer accounted for 19.3% of all new cancer cases, and 8.4% of the cancer deaths in American men. Previous studies have found that autopsy studies indicate that 50% of men older than 50 years of age have prostate cancer.

It is important to mention that there may be no signs for numerous years due to the fact that the cancer can develop slowly. As a result, symptoms do not usually appear until the prostate has become large enough to affect the urethra. When this happens, symptoms can include an increased need to urinate and/or a need to strain whilst urinating.

When it comes to the detection of prostate cancer, typically a systematic transrectal ultrasound (TRUS) guided prostate biopsy is used. According to a previous study: “the current 12-core template biopsy technique has a significant sampling error and a low sensitivity (24–52%), and it can miss up to 30% of cancers. As a result, a patient may have a ‘negative’ biopsy but may be harbouring an occult cancer. Alternatively, a diagnosis of cancer may have been made, but the patient is under-staged, because the most aggressive histologic region of the tumour has not been sampled.”

As an alternative method for prostate cancer diagnosis, it has been proposed that the method of ‘Molecular image-directed, 3D ultrasound-guided biopsy’ should be used instead.

Research has discovered that this method “represents a new trend for the diagnosis of prostate cancer and for monitoring of prostate cancer for patients on active surveillance. MRI/TRUS fusion targeted biopsy is a new standard of care, approved by U.S. Food and Drug Administration. Positron emission tomography (PET) and ultrasound fusion targeted biopsy is a new direction that can have an immediate impact on future patient care.”

Introducing molecular image-directed, 3D ultrasound-guided biopsy

Continuing on from this, “for patients who select active surveillance and whose biopsy result shows a low-grade, non-clinically significant tumour, an accurate biopsy can help to reduce their anxiety that often increases due to possible sampling error and the uncertainty associated with the current biopsy technique. As a false negative result may delay treatment, an accurate biopsy is extremely important for those active surveillance patients and for those patients undergone focal therapy for a small volume prostate cancer.

“Unfortunately, 2D ultrasound provides imprecise location of the abnormal findings, and it is not possible to be certain that the same area has been sampled by the repeat biopsy. 3D ultrasound image-guided biopsy is able to record the 3D location of the biopsy sites for follow-up examinations and thus will change the management of these atypical small acinar proliferation (ASAP) patients. If the targeted biopsy improves cancer detection rate, many patients would not need repeated biopsies, and the total number of prostate biopsies could [therefore] be reduced.

“Furthermore, it will also reduce the potential morbidities of life-threatening sepsis and transrectal bleeding, both of which are associated with biopsy procedures. The use of PET/ultrasound fusion targeted biopsies within the diagnostic pathway may result in an enhanced detection of clinically significant disease, fewer men biopsied overall, and fewer needle deployments; thus, it could transform prostate cancer management and change clinical practice from ‘blind’ to ‘targeted’ biopsy.”

PET-Directed Biopsy’s explained

In terms of a ‘PET-Directed Biopsy’, this refers to the method of using PET molecular imaging information to direct the biopsy to the suspicious lesion. PET can depict metabolic and functional information about prostate cancer. Various PET agents were developed or are under development for prostate cancer detection. PET with new molecular imaging radiotracers, such as choline, prostate-specific membrane antigen, and fluciclovine, has had promising results in the detection and localisation of prostate cancer in humans. For patients with previous negative biopsy results but elevated prostate- specific antigen (PSA) levels, PET-guided biopsy can have an important role in the management of prostate cancer. PET can depict metabolic and functional information about prostate cancer.

In patients with biochemical failure after prior therapy, PET has an important role with the added value of accurate whole body staging compared to conventional imaging.13 At the beginning of 2019, Fei et al reported a study assessing “the feasibility and cancer detection rate of fluciclovine positron emission tomography-ultrasound fusion targeted biopsy vs standard template biopsy in the same patient with biochemical failure after nonsurgical therapy for prostate cancer.”

Fluciclovine Positron Emission Tomography/Ultrasound Fusion Targeted Biopsy

Fei, B et al (2019) reported that a “template biopsy was positive for malignancy in 6 of 21 patients (28.6%), including 10 of 124 regions and 11 of 246 cores, vs targeted biopsy in 10 of 21 (47.6%), including 17 of 50 regions and 40 of 125 cores”. In addition to this, it was found that “five of 21 patients had positive findings on targeted biopsy only and one of 21 had positive findings on template biopsy only. An additional case was upgraded from Grade Group 2 to 3 on targeted biopsy. Extraprostatic disease was detected in eight of 21 men (38.1%) with histological confirmation in all three who underwent lesion biopsy.”

Overall, this study found that “Fluciclovine positron emission tomography real-time ultrasound fusion guidance for biopsy is feasible in patients with biochemical failure after nonsurgical therapy for prostate cancer. It identifies more recurrent prostate cancer using fewer cores compared with template biopsy in the same patient.

Fluciclovine PET images and real-time ultrasound images were combined to guide fusion targeted biopsy of the prostate in patients with biochemical failure after nonsurgical therapy of prostate cancer. In this feasibility prospective study PET-ultrasound fusion targeted biopsy had a higher cancer detection rate than standard TRUS guided biopsy in patients with recurrent disease and it did so with fewer regions and cores sampled”.

Multi-parametric magnetic resonance imaging

Another method that is regularly used for the diagnosis of prostate cancer is multi-parametric magnetic resonance imaging (mpMRI). This technique “provides excellent soft-tissue contrast and is clinically used for the detection, localisation, characterisation, staging, biopsy guidance, and active surveillance of prostate cancer. MpMRI has proven to be an effective technique for localising high-risk prostate cancer. It can also help to guide biopsies in order to achieve a higher tumour detection rate.”

However, it should be noted that because of the “large amount of mpMRI data and the variations in MR scanners, sequences, protocols, and patient motion, and etc., the detection can be affected by multiple factors such as observer variability as well as the visibility and complexity of the lesions. In order to improve the quantitative assessment of the disease and reduce the reporting time, various computer-aided diagnosis (CAD) systems have been designed to help radiologists identify lesions.

“There is a growing need to localise prostate cancers on mpMRI in order to facilitate the use of image-guided biopsy, focal therapy, and active surveillance follow-up. CAD systems may help to make a clinical decision in a fast, effective, and reliable way. It may also improve the quantitative assessment of the disease. Currently, most CAD systems using prostate MRI focus on local, suspicious lesions and discrimination between benign and malignant lesions within the entire grand.”

References

  1. Fei B, Nieh PT, Master VA, et al, Molecular imaging and fusion targeted biopsy of the prostate. Clin Transl Imaging. 2017 Feb;5(1):29-43. doi: 10.1007/s40336-016-0214-7.
  2. Fei B. Computer-aided diagnosis of prostate cancer with MRI. Curr Opin Biomed Eng. 2017 Sep;3:20-27. doi: 10.1016/j.cobme.2017.09.009.
  3. Siegel, RL, Miller, K.D and Jemal, A. 2017. Cancer statistics, 2017. CA Cancer J Clin 2017, 67:7–30.
  4. Roehrborn, C.G., Andriole G.L, and Wilson, T.H et al. 2011. Effect of dutasteride on prostate biopsy rates and the diagnosis of prostate cancer in men with lower urinary tract symptoms and enlarged prostates in the combination of Avodart and tamsulosin trial. Eur Urol 59(2):244–249
  5. Rosette, J., Wink, M.H and Mamoulakis, C et al. 2009. Optimizing prostate cancer detection. 8 versus 12-core biopsy protocol. J Urol 182(4):1329–1335
  6. Presti, J.C, O’Dowd, G.J and Miller, M.C et al. 2003. Extended peripheral zone biopsy schemes increase cancer detection rates and minimize variance in prostate specific antigen and age related cancer rates: results of a community multipractice study. J Urol 169(1):125–129
  7. Pondman, K.M, Futterer, J.J and Haken. B et al. 2008. MR-guided biopsy of the prostate: an overview of techniques and a systematic review. Eur Urol 54(3):517–527
  8. Hricak, H. 2005. MR imaging and MR spectroscopic imaging in the pre-treatment evaluation of prostate cancer.
  9. Radiol, B.J and Franks, L.M. 1973. Proceedings: etiology, epidemiology, and pathology of prostatic cancer. Cancer 32(5):1092–1095
  10. Holund, B. 1980. Latent prostatic cancer in a consecutive autopsy series. Scand J Urol Nephrol 14(1):29–35
  11. Fei B, Abiodun-Ojo OA, Akintayo AA, et al. Feasibility and Initial Results: Fluciclovine Positron Emission Tomography/Ultrasound Fusion Targeted Biopsy of Recurrent Prostate Cancer. J Urol. 2019 Aug;202(2):413-421. doi:10.1097/JU.0000000000000200

Baowei Fei
Professor
Cecil H. and Ida Green Chair in Systems Biology Science
University of Texas at Dallas and UT Southwestern Medical Center
+1 972 883 7239
bfei@utdallas.edu
Baowei.Fei@utsouthwestern.edu
https://fei-lab.org/baowei-fei/

This article will appear in SciTech Europa Quarterly Issue 33, which will be available to read in December 2019

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