Magnetic resonance imaging of benign prostatic hyperplasia

Abstract

Benign prostatic hyperplasia (BPH) is a histologic diagnosis showing glandular and stromal hyperplasia in the prostate. Its symptoms usually occur after the age of 40, and its prevalence reaches 50%-60% by the age of 60 (1). About 50% of men who have a histologic diagnosis of BPH have lower urinary tract symptoms including storage and voiding symptoms (2). Imaging plays an important role in evaluation of enlargement locations and nodules, estimation of prostatic volumes, and management of BPH patients. Ultrasonography (US) and magnetic resonance imaging (MRI) are used in evaluation of the prostate. US is the most common imaging modality in BPH patients, because it is relatively inexpensive and provides important information in most patients. Recently, MRI has been more commonly used in management of prostate cancer (3). Wasserman (4) described the US classification of BPH using findings on sagittal and axial images of transrectal US based on the pathologic classification (5). Following this, Wasserman et al. (6) implemented this classification to MRI. The classification for detecting BPH types is important, as patients with different BPH types may have different symptoms and treatment options.In this paper, we retrospectively evaluated MRI scans of BPH patients who were histologically diagnosed as BPH and presented the different types of BPH on T2-weighted MRI, since the prostatic parenchyma is best evaluated on T2-weighted images (6, 7). Additionally, the sagittal and axial images that are important for the classification of BPH were only available on T2-weighted images. In our practice, we perform prostate MRI on a 3.0 T scanner (AchievaTX; Philips) using an endorectal coil (Prostate eCoil, Medrad). Anatomy of the prostateIn previous studies (4,8), the anatomy of the prostate has been reviewed. There are three main glandular zones (central, transition, peripheral) and one stromal zone (anterior fibromuscular stroma). There is also a subsphincteric periurethral gland (PUG) region, which is a fraction of the size of the transition zone (TZ) (9). BPH mostly involves PUGs, TZ, and stromal ABSTRACTBenign prostatic hyperplasia (BPH) is a common condition in middle-aged and older men and negatively affects the quality of life. An ultrasound classification for BPH based on a previous pathologic classification was reported, and the types of BPH were classified according to different enlargement locations in the prostate. Afterwards, this classification was demonstrated using magnetic resonance imaging (MRI). The classification of BPH is important, as patients with different types of BPH can have different symptoms and treatment options. BPH types on MRI are as follows: type 0, an equal to or less than 25 cm 3 prostate showing little or no zonal enlargements; type 1, bilateral transition zone (TZ) enlargement; type 2, retrourethral enlargement; type 3, bilateral TZ and retrourethral enlargement; type 4, pedunculated enlargement; type 5, pedunculated with bilateral TZ and/or retrourethral enlargement; type 6, subtrigon...

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