D'Arcy Little MD CCFP FCFP FRCPC, Radiologist, Orillia Soldiers' Memorial Hospital, Adjunct Clinical Lecturer, Department of Family and Community Medicine and Department of Medical Imaging, University of Toronto, Toronto, ON.

Abstract
Prostate cancer is a common cancer in men worldwide, and early detection is key to improved patient outcomes. Diagnosis typically involves a combination of clinical examination, prostate-specific antigen blood testing, and imaging studies. Radiology plays an important role, aiding in treatment planning, confirming the diagnosis by directing biopsy, staging the patient, and following treatment course. Imaging modalities for prostate cancer diagnosis include ultrasound, CT, nuclear medicine, and MRI. While MRI is the most sensitive imaging modality, ultrasound is still the preferred modality for measuring the prostate volume. Prostate-specific membrane antigen PET imaging has shown to have superior sensitivity and specificity compared to conventional imaging modalities in the detection of prostate cancer, especially in the context of low PSA. Clinical pearls include performing ultrasound-guided biopsy under local anesthesia to improve patient comfort, and the use of fusion MRI and ultrasound images to facilitate MRI/TRUS fusion-guided biopsy.
Key Words: Prostate cancer, imaging modalities, ultrasound, MRI, CT, PSMA PET.

Introduction:
Prostate cancer is the second most common cancer in men worldwide, with an estimated 1.4 million new cases diagnosed in 2020. The diagnosis of prostate cancer typically involves a combination of clinical examination with digital rectal examination, prostate-specific antigen (PSA) blood testing, and imaging studies. Radiology plays an important role, providing valuable information regarding the location and extent of the tumour, allowing confirmation of the diagnosis by directing biopsy, as well as aiding in treatment planning.

Clinical History:
The clinical presentation of prostate cancer can vary widely, with many patients unfortunately remaining asymptomatic until the disease is advanced. Common clinical symptoms include urinary symptoms such as hesitancy, frequency, and urgency, as well as possible erectile dysfunction and back pain. A digital rectal examination (DRE) may reveal an abnormal prostate gland, such as the presence of a prostate nodule, and PSA blood testing is often used to screen for prostate cancer. Elevated PSA levels can indicate the presence of prostate cancer, but further imaging studies are usually necessary to confirm the diagnosis and to determine the extent of the disease. Discussing the controversies of prostate cancer screening is beyond the scope of this article.

Radiology Diagnosis:
Imaging studies are an essential component of the diagnostic workup for prostate cancer. The most used imaging modalities include ultrasound, computed tomography (CT), nuclear medicine, and magnetic resonance imaging (MRI).