Prostate Cancer and Its Mimics—A Pictorial Review

Simple Summary This review focuses on the potential challenges encountered in the interpretation of multiparametric prostate MRI (mpMRI). While mpMRI is accurate in the diagnosis of prostate cancer, false positive and false negative results can occur. The review discusses anatomical structures and benign conditions that may mimic prostate cancer, including prostatitis, ectopic and stromal benign prostate hyperplasia nodules, post-biopsy hemorrhage, and abscesses. The article provides suggestions on avoiding these pitfalls and emphasizes the importance of image quality in achieving accurate interpretations. Radiologists need to be aware of these pitfalls to enhance diagnostic accuracy in the increasingly prevalent use of mpMRI for prostate evaluation. Abstract Background: Multiparametric prostate MRI (mpMRI) is gaining wider recommendations for diagnosing and following up on prostate cancer. However, despite the high accuracy of mpMRI, false positive and false negative results are reported. Some of these may be related to normal anatomic structures, benign lesions that may mimic cancer, or poor-quality images that hamper interpretation. The aim of this review is to discuss common potential pitfalls in the interpretation of mpMRI. Methods: mpMRI of the prostates was performed on 3T MRI scanners (Philips Achieva or Siemens Magnetom Vida) according to European Society of Urogenital Radiology (ESUR) guidelines and technical requirements. Results: This pictorial review discusses normal anatomical structures such as the anterior fibromuscular stroma, periprostatic venous plexus, central zone, and benign conditions such as benign prostate hyperplasia (BPH), post-biopsy hemorrhage, prostatitis, and abscess that may imitate prostate cancer, as well as the appearance of prostate cancer occurring in these locations. Furthermore, suggestions on how to avoid these pitfalls are provided, and the impact of image quality is also discussed. Conclusions: In an era of accelerating prostate mpMRI and high demand for high-quality interpretation of the scans, radiologists should be aware of these potential pitfalls to improve their diagnostic accuracy.


Introduction
Prostate cancer (PCa) is one of the most common malignant tumors in men, with an incidence of over 1.4 million worldwide [1]. Multiparametric prostate MRI (mpMRI) is commonly used in the detection, staging, active surveillance, and follow-up after treatment of PCa. This technique combines excellent morphological images (T1, T2-weighted) with functional imaging: diffusion-weighted imaging (DWI) and dynamic contrast enhanced imaging (DCE). Recent trials have also revealed the great potential of mpMRI for performing pre-biopsy diagnosis [2][3][4][5][6]. As a result, the latest 2023 European Association of Urology Table 1. Summary of prostate cancer mimics in relation to the anatomic location [14][15][16][17].

Type Location
Anatomic structures Multiparametric MRIs of the prostates were performed on 3T MRI scanners (Philips Achieva 3.0 T Tx, Best, Netherlands or Siemens 3T Magnetom Vida, Erlangen, Germany) according to European Society of Urogenital Radiology (ESUR) guidelines and technical requirements [18] and PI-RADS ver. 2.1 [11]. Examinations were performed with superficial phase array coils (a 32-channel cardiac coil on Philips or a Contour 24 coil on Siemens). The prostate mpMRI protocol consisted of high-resolution T2-weighted images in three planes, T1-weighted images, diffusion-weighted imaging (DWI), which consisted of 6 b values (0-2000 s/mm 2 ) on Philips or 4 b values (50-2000 s/mm 2 ) on Siemens, and dynamic contrast-enhanced (DCE) imaging. Throughout the article, lesions were assigned PI-RADS assessment categories according to PI-RADS version 2.1 [11].

Anterior Fibromuscular Stroma
The anterior fibromuscular stroma is the most anterior part of the prostate. It is located anteriorly to the transitional zone in the midline and paramidline between the two lobes. It extends from the apex to the base of the prostate. AFMS consists of muscle cells and dense connective tissue, without glandular tissue. It merges with the prostate capsule but, in 89% of cases, is not covered by the capsule and, as a result, is the most outer layer of the anterior prostate [19].
On MRI, AFMS appears homogenously hypointense on T2-weighted images due to its histologic composition (comparably with the muscles). Usually, it is slightly more hypointense than prostate cancer, which presents the "erased charcoal" signal pattern. However, when AFMS is hypertrophied, especially asymmetrically, it may mimic PCa and have a similar appearance on T2-weighted images [11,20]. On the contrary to cancer, AFMS never restricts diffusion-it may be hypointense on the ADC map due to the T2-dark through effect but is never hyperintense on DWI and does not show early enhancement on DCE [21] (Figure 1). These two parameters are crucial in distinguishing AFMS hypertrophy from cancer, which usually presents diffusion restriction and may show early focal enhancement on DCE ( Figure 2).
Additionally, examining AFMS in three planes in T2-w images (axial, sagittal, and coronal) is highly recommended to confirm the continuity with benign tissue [14]. About 20% of all prostate cancers are located anteriorly. An amount of 53.3% of PCa situated in the transition zone occupies the anterior one-third of the T and may abut and infiltrate AFMS. A total of 87.7% of all T PCa are located in the anterior two-thirds of the T [21]. About 20% of all prostate cancers are located anteriorly. An amount of 53.3% of PCa situated in the transition zone occupies the anterior one-third of the TZ and may abut and infiltrate AFMS. A total of 87.7% of all TZ PCa are located in the anterior two-thirds of the TZ [21].

Periprostatic Venous Plexus
The periprostatic veins that form the periprostatic venous plexus are located on both lateral sides of the prostate gland. They connect with the venous plexus anterior to the prostate and drain into the internal iliac veins [15,22]. The size of the periprostatic venous plexus varies among individuals, with a tendency to decrease in size with age [23] and be more prominent in men with prostatitis [15].
The periprostatic venous plexus runs near the anatomical capsule of the gland and may eventually be embedded within it on the lateral side within some distance [22]. On T2-w images, veins usually appear as bright, tubular structures; nevertheless, their signal intensity may be variable due to turbulent flow or different blood flow velocities [24].
Eventually, periprostatic veins may present as tubular or round structures (if axially imaged) that are hypointense on T2-w images with enhancement on DCE and sometimes mildly hyperintense on DWI owing to a slow velocity of blood flow and therefore mimic prostate carcinoma [14]. However, careful examination of these structures in all three planes should reveal their continuity with the rest of the vessels (Figure 3).

Periprostatic Venous Plexus
The periprostatic veins that form the periprostatic venous plexus are located on both lateral sides of the prostate gland. They connect with the venous plexus anterior to the prostate and drain into the internal iliac veins [15,22]. The size of the periprostatic venous plexus varies among individuals, with a tendency to decrease in size with age [23] and be more prominent in men with prostatitis [15].
The periprostatic venous plexus runs near the anatomical capsule of the gland and may eventually be embedded within it on the lateral side within some distance [22]. On T2-w images, veins usually appear as bright, tubular structures; nevertheless, their signal intensity may be variable due to turbulent flow or different blood flow velocities [24].
Eventually, periprostatic veins may present as tubular or round structures (if axially imaged) that are hypointense on T2-w images with enhancement on DCE and sometimes mildly hyperintense on DWI owing to a slow velocity of blood flow and therefore mimic prostate carcinoma [14]. However, careful examination of these structures in all three planes should reveal their continuity with the rest of the vessels ( Figure 3).

Central Zone
The central zone has a pyramidal or conical shape and is located bilaterally in the base of the prostate, surrounding the ejaculatory ducts and narrowing towards the level of verumontanum [17]. It contains about 20% of glandular tissue [11], but only 2.5-7% [12,13] of prostate cancers are reported to arise from this zone. However, those cancers tend to be more aggressive due to the early involvement of seminal vesicles and extraprostatic extension [12,13,15,17]. On T2-weighted images, the central zone looks like homogenous, symmetric, oval areas of low signal intensity located at the base of the prostate.
On the DWI/ADC sequence, it may show diffusion restriction and usually no or weak enhancement on DCE [14], usually with progressive (type 1) or plateau (type 2) enhancement curves [25] ( Figure 4A). These malignant-looking morphological and functional features may be mistaken for bilateral prostate cancer.
As the transitional zone becomes enlarged with benign prostatic hyperplasia (BPH), the central zone is compressed and displaced towards the base of the prostate [15,16]. Its shape resembles a mustache in the axial and coronal planes at the base of the prostate-the so-called "mustache sign" [14] ( Figure 4B). The main feature that suggests benignity is the symmetry of the findings-their oval, symmetric, well-defined shape, with a homogenously low-intensity signal on T2-weighted images. The coronal plane may be especially useful to show the normal anatomy of CZ.
On the contrary, prostate cancers tend to be more heterogeneous on T2-weighted images with ill-defined margins, which results in asymmetric irregularities in the central zone in T2-w images. If such a lesion additionally presents marked diffusion restriction and focal, early enhancement (more frequently, it is associated with a type 3 (washout) enhancement curve), it suggests a suspicious lesion [14,21] (Figure 5). Irregular hypertrophy of the transitional zone may lead to the asymmetric displacement of the central zone and present as a pseudolesion [16], making a correct diagnosis even more difficult. Irregular hypertrophy of the transitional zone may lead to the asymmetric displacement of the central zone and present as a pseudolesion [16], making a correct diagnosis even more difficult.

Hypointense Area in the Median Posterior Middle Gland or at the Base
Often, a focal area that is hypointense in T2-weighted images may be observed in the midline of the posterior middle gland or at the base of the prostate. It is usually symmetric and wedged in shape in T2-weighted images and may show moderate diffusion restriction and focal, slight contrast enhancement, thus mimicking cancer.
These areas may, however, correspond to the apex of the central zone (compressed between the transition zone and peripheral zone). As the central zone extends into the middle third of the prostate, its shape resembles a teardrop in the coronal plane-so called the "teardrop sign" [14,15]. In order to interpret this finding, it is necessary to visualize the continuity of hypointense areas of the median posterior middle gland with the central zone at the base of the prostate in the coronal plane and assess its symmetry and homogeneity.
Prostate cancer may also be located in this region, which is sometimes very difficult to differentiate from the image of the central zone. PCa is usually more heterogeneous on T2-weighted images, with ill-defined, fuzzy margins, marked diffusion restriction, and focal, early enhancement [14,15,17] (Figures 6 and 7). The finding of such a lesion should raise suspicion of PCa and require a biopsy.

Transition Zone-Benign Prostatic Hyperplasia
Benign Prostate Hyperplasia (BPH) affects more than 80% of men and increases with age [26].
BPH is defined as hyperplasia of glandular and fibromuscular stromal cells in the transition zone (T ) [17] that tends to form nodules of variable sizes and, as a result, causes enlargement of the T .
On MRI in T2-w images, benign prostate hyperplasia is depicted as an enlarged T of variable signal intensities resembling "organized chaos," often containing BPH nodules with variable signal intensity. Four types of BPH nodules are distinguished: stromal, glandular, cystic, and mixed [27].
BPH nodules, mainly composed of glandular tissue, are visualized as more hyperintense on T2-w images. In contrast, BPH nodules composed of fibrous stromal tissue and hyperplastic stromal tissue appear as hypointense on the T2-w sequence, sometimes making the differential diagnosis of prostate cancer difficult. In addition, BPH nodules may mildly/moderately restrict diffusion (appear bright on high b values at the DWI sequence and dark on the ADC map) and show rapid enhancement, sometimes with washout on the DCE-features that may resemble cancerous tissue [27][28][29].
According to PIRADS version 2.1, the dominant sequence to assess T is T2-w [11]. A typical BHP nodule is round or oval and completely encapsulated, and it should be assessed as PIRADS 1 [11] (Figure 8A(a,b),B). Partially encapsulated nodules ( Figure  8A(c)) and homogenous, circumscribed nodules without encapsulation or homogenous, mildly hypointense areas between the nodules without diffusion restriction are assessed as PIRADS 2 [11]. Hence, BPH nodules with DWI scores of 4 and 5 are now upgraded from the 2 to 3 PIRADS assessment categories [11] (Figure 9).

Transition Zone-Benign Prostatic Hyperplasia
Benign Prostate Hyperplasia (BPH) affects more than 80% of men and increases with age [26].
BPH is defined as hyperplasia of glandular and fibromuscular stromal cells in the transition zone (TZ) [17] that tends to form nodules of variable sizes and, as a result, causes enlargement of the TZ.
On MRI in T2-w images, benign prostate hyperplasia is depicted as an enlarged TZ of variable signal intensities resembling "organized chaos," often containing BPH nodules with variable signal intensity. Four types of BPH nodules are distinguished: stromal, glandular, cystic, and mixed [27].
BPH nodules, mainly composed of glandular tissue, are visualized as more hyperintense on T2-w images. In contrast, BPH nodules composed of fibrous stromal tissue and hyperplastic stromal tissue appear as hypointense on the T2-w sequence, sometimes making the differential diagnosis of prostate cancer difficult. In addition, BPH nodules may mildly/moderately restrict diffusion (appear bright on high b values at the DWI sequence and dark on the ADC map) and show rapid enhancement, sometimes with washout on the DCE-features that may resemble cancerous tissue [27][28][29].
According to PIRADS version 2.1, the dominant sequence to assess TZ is T2-w [11]. A typical BHP nodule is round or oval and completely encapsulated, and it should be assessed as PIRADS 1 [11] (Figure 8(Aa,b),B). Partially encapsulated nodules (Figure 8(Ac)) and homogenous, circumscribed nodules without encapsulation or homogenous, mildly hypointense areas between the nodules without diffusion restriction are assessed as PIRADS 2 [11]. Hence, BPH nodules with DWI scores of 4 and 5 are now upgraded from the 2 to 3 PIRADS assessment categories [11] (Figure 9).    Typical PCa in TZ presents as an ill-defined, lenticular lesion with decreased signal intensity on T2-w images, often compared with an erased charcoal appearance, marked diffusion restriction, and focal, early enhancement that disrupts the "organized chaos" of BPH ( Figure 10). Typical PCa in T presents as an ill-defined, lenticular lesion with decreased signal intensity on T2-w images, often compared with an erased charcoal appearance, marked diffusion restriction, and focal, early enhancement that disrupts the "organized chaos" of BPH ( Figure 10).

Ectopic BPH Nodules
Ectopically located BPH nodules may simulate cancer, especially when they are located in the peripheral zone. On diffusion-weighted imaging and DCE, they may appear as lesions suspicious of malignancy with marked diffusion restriction and early enhancement [20], sometimes with washout. Despite the DWI, according to PI-RADS ver. 2.1, it is the dominant sequence in the peripheral zone [11]. In this particular case, the key sequence to distinguish them from cancer and make the proper diagnosis is the T2-weighted sequence. A T2-weighted image may reveal well-defined, encapsulated nodules that sometimes contain cysts, morphologically suggesting a BPH nodule (Figure 11).

Ectopic BPH Nodules
Ectopically located BPH nodules may simulate cancer, especially when they are located in the peripheral zone. On diffusion-weighted imaging and DCE, they may appear as lesions suspicious of malignancy with marked diffusion restriction and early enhancement [20], sometimes with washout. Despite the DWI, according to PI-RADS ver. 2.1, it is the dominant sequence in the peripheral zone [11]. In this particular case, the key sequence to distinguish them from cancer and make the proper diagnosis is the T2-weighted sequence. A T2-weighted image may reveal well-defined, encapsulated nodules that sometimes contain cysts, morphologically suggesting a BPH nodule ( Figure 11).  (e) enhancement curve in the lesion shows strong, early enhancement with washout-only in these sequences the lesion appear suspicious for malignancy. However, T2weighted image (f) revealed completely encapsulated BPH nodule, which should be scored as benign-PI-RADS 1.

Post-Biopsy Hemorrhage
TRUS-guided biopsy remains the gold standard in the detection of prostate cancer in men with elevated PSA levels. However, one of the complications of the biopsy may be hemorrhage, which may lower the diagnostic performance of the MRI.
Post-biopsy hemorrhage resolves over time-hemorrhagic foci are seen in 72.2% of men four weeks after biopsy and decrease to 52% after six weeks [30]. Consequently, a delay of at least six weeks or a more extended period between biopsy and MRI is recommended to decrease hemorrhagic foci, which may hamper the diagnosis or staging of PCa in some cases [11,31].
The essential sequence to evaluate hemorrhage is the T1-weighted native sequence without contrast. The hemorrhagic foci (depending on the age of the blood) on MRI may present as hyperintense on T1-w, hypointense on T2-weighted, or hyperintense on T2weighted. They may restrict diffusion and produce a "pseudo enhancement", and in this manner, they may mimic PCa ( Figure 12). However, assessing the T1 native images usually resolves the uncertainty. Always look at the T1-w native sequence before assessing DCE to avoid confounding the hemorrhage with the enhancement.  ) (b,c). However, the native T1-w fat-saturated image reveals the hyperintense signal in this location (arrow), which corresponds to methemoglobin (the product of hemoglobin degradation) after biopsy (d). After contrast administration, "pseudo enhancement" is noted (arrow) (e). The combination of images is in favor of PI-RADS 2 lesion. The final histopathology did not reveal cancer in this region.
On the other hand, the "T1 hemorrhage exclusion sign" phenomenon was described as an area of decreased signal intensity within PZ that is surrounded by an area of high signal on T1-weighted images due to hemorrhage. If such a finding corresponds to a lesion of low signal intensity on T2-w images, which restricts diffusion, it is highly predictive of cancer (95% PPV) [23,32,33] (Figure 13).
The high citrate content in the peripheral zone explains this phenomenon. This metabolite has anticoagulant properties. As a result, a normal prostate peripheral zone may show an increased signal on T1W images due to hemorrhage, usually up to several weeks after the biopsy. Otherwise, prostate cancer shows reduced citrate levels, making it less likely to present prolonged hemorrhagic changes on MRI [32,34].

Prostatitis
Acute bacterial prostatitis is an acute inflammation of the prostate that causes urinary tract symptoms and pelvic pain [35,36]. The highest incidence of acute prostatitis is reported in patients aged 20-40 and in men over 70 years old [35]. The most common pathogen in acute bacterial inflammation is Escherichia Coli [37].
Chronic prostatitis may be a result of undertreated acute prostatitis, with a lifetime prevalence of 1.8% to 8.2% [16,38].
Prostatitis may occur as focal or diffuse, affecting both the P and T [16]. It is one of the most common prostate cancer mimics, and it may be impossible to reliably distinguish it from PCa only on MRI images [16], which makes prostate inflammation a major source of false-positive results on MRI [39].
On MRI, diffuse prostate inflammation presents as an area of decreased signal intensity on T2-weighted images, with usually mild to moderate diffusion restriction and increased perfusion on DCE [11,16] (Figure 14). However, in contrast to cancer, prostatitis usually appears as a more diffuse, lobar, or linear area with indistinct borders rather than a focal, rounded, or oval lesion [15]. In addition, the signal changes on T2-weighted images and DWI are usually mild to moderate and slightly less pronounced than in cancer [11]. Therefore, the patient's clinical history and follow-up after treatment are crucial in making the proper diagnosis [14,16].

Prostatitis
Acute bacterial prostatitis is an acute inflammation of the prostate that causes urinary tract symptoms and pelvic pain [35,36]. The highest incidence of acute prostatitis is reported in patients aged 20-40 and in men over 70 years old [35]. The most common pathogen in acute bacterial inflammation is Escherichia Coli [37].
Chronic prostatitis may be a result of undertreated acute prostatitis, with a lifetime prevalence of 1.8% to 8.2% [16,38].
Prostatitis may occur as focal or diffuse, affecting both the PZ and TZ [16]. It is one of the most common prostate cancer mimics, and it may be impossible to reliably distinguish it from PCa only on MRI images [16], which makes prostate inflammation a major source of false-positive results on MRI [39].
On MRI, diffuse prostate inflammation presents as an area of decreased signal intensity on T2-weighted images, with usually mild to moderate diffusion restriction and increased perfusion on DCE [11,16] (Figure 14). However, in contrast to cancer, prostatitis usually appears as a more diffuse, lobar, or linear area with indistinct borders rather than a focal, rounded, or oval lesion [15]. In addition, the signal changes on T2-weighted images and DWI are usually mild to moderate and slightly less pronounced than in cancer [11]. Therefore, the patient's clinical history and follow-up after treatment are crucial in making the proper diagnosis [14,16].
Focal prostatitis and granulomatous prostatitis may be indistinguishable from prostate cancer both on MRI, where they present as a focal lesion with low T2-signal, marked diffusion restriction, and early enhancement, and on clinical examination, where they present as a focal or diffuse area of stiffness of the gland and a raised PSA level [16]. According to PI-RADS ver. 2.1, the MRI lesions described above could be assessed as PI-RADS 4 or 5 [14]. Therefore, histopathological verification of such lesions is necessary to make an accurate diagnosis and exclude the presence of a neoplastic tumor [14] (Figures 15 and 16). sity on T2-weighted images, with usually mild to moderate diffusion restriction and increased perfusion on DCE [11,16] (Figure 14). However, in contrast to cancer, prostatitis usually appears as a more diffuse, lobar, or linear area with indistinct borders rather than a focal, rounded, or oval lesion [15]. In addition, the signal changes on T2-weighted images and DWI are usually mild to moderate and slightly less pronounced than in cancer [11]. Therefore, the patient's clinical history and follow-up after treatment are crucial in making the proper diagnosis [14,16].      For comparison, the diffuse infiltration of prostate cancer in almost the entire prostate gland, with the low signal intensity of an "erased charcoal" appearance, strong diffusion restriction, and early enhancement, is depicted in Figure 17. For comparison, the diffuse infiltration of prostate cancer in almost the entire prostate gland, with the low signal intensity of an "erased charcoal" appearance, strong diffusion restriction, and early enhancement, is depicted in Figure 17.

Prostatic Abscess
Prostatic abscess most commonly develops as a complication of acute prostatitis, biopsy, or other prostate procedures such as cryotherapy, brachytherapy, and intravesical

Prostatic Abscess
Prostatic abscess most commonly develops as a complication of acute prostatitis, biopsy, or other prostate procedures such as cryotherapy, brachytherapy, and intravesical BCG therapy [40]. In addition, it frequently affects men with diabetes or immunodeficiency disorders [40]. On MRI, it is visualized as a lesion with increased signal in T2-w images and iso-low signal in T1-w images, in the center showing strong diffusion restriction, a very low ADC value, and ring-type enhancement on DCE of the pseudocapsule on the periphery [41] ( Figure 18). In some cases, it may show an iso to slightly lower signal in T2-w images [14], which, together with the strong diffusion restriction, may be misleading. However, a very low ADC, ring-type enhancement, and usually high T2-w signal with a correlation with clinical data (e.g., fever, previous urological instrumentation) guide to a correct diagnosis. (f) after antibiotic treatment, the abscess persisted, but in T2-w images, its signal changed to intermediate intensity (arrow).

Quality of Images
Image quality, along with a radiologist's expertise, plays a crucial role in an accurate diagnosis. Images of poor quality, motion artifacts, rectal gas, and hip prostheses may lead to uncertainty or false positive or negative results, even when assessed by experienced radiologists. The Prostate Imaging Quality (PI-QUAL) score was invented to evaluate the diagnostic quality of images from mpMRI [42]. Firstly, obtaining high-resolution T2w images, high-quality diffusion-weighted imaging, and DCE is highly recommended according to PIRADS v. 2.1 guidelines [11,43]. Secondly, artifacts due to bowel motion and distention of the rectum should be eliminated-it has been reported that referral of a rectal enema and a special diet before, as well as administering anti-spasmodic drugs during the examination, should diminish these artifacts and improve the quality of the images [44][45][46].
A good signal-to-noise ratio should also be maintained [43]. DWI, which plays a crucial role in the detection of PCa in the peripheral zone, is the most susceptible to artifacts ( Figure 19). Recent MR acquisition techniques, e.g., parallel imaging and motion reduction techniques, as well as right-left phase encoding instead of anterior-posterior, may reduce those artifacts [27,43].

Quality of Images
Image quality, along with a radiologist's expertise, plays a crucial role in an accurate diagnosis. Images of poor quality, motion artifacts, rectal gas, and hip prostheses may lead to uncertainty or false positive or negative results, even when assessed by experienced radiologists. The Prostate Imaging Quality (PI-QUAL) score was invented to evaluate the diagnostic quality of images from mpMRI [42]. Firstly, obtaining high-resolution T2-w images, high-quality diffusion-weighted imaging, and DCE is highly recommended according to PIRADS v. 2.1 guidelines [11,43]. Secondly, artifacts due to bowel motion and distention of the rectum should be eliminated-it has been reported that referral of a rectal enema and a special diet before, as well as administering anti-spasmodic drugs during the examination, should diminish these artifacts and improve the quality of the images [44][45][46].
A good signal-to-noise ratio should also be maintained [43]. DWI, which plays a crucial role in the detection of PCa in the peripheral zone, is the most susceptible to artifacts ( Figure 19). Recent MR acquisition techniques, e.g., parallel imaging and motion reduction techniques, as well as right-left phase encoding instead of anterior-posterior, may reduce those artifacts [27,43]. (e) Figure 19. DWI sequence affected by artifacts from the gas in the rectum-rendering interpretation of the P in posterior gland impossible: (a) DWI b 2000; (b) ADC map. However, in this patient, a focal early enhancement is visible on DCE (arrow) (c), which corresponds to a poorly visible, hypointense focal lesion on T2-weigted image (arrow) (d), on the background of a larger area of reduced signal intensity; the lesion was reported as PI-RADS 4; (e) whole-mount histopathology after radical prostatectomy reveals prostate cancer GS 4 + 3 in this location in the right P (area outlined with black continuous line).

Conclusions
Recently, mpMRI has evolved as a pivotal diagnostic imaging modality to detect or rule out significant prostate cancer. However, despite the high accuracy of mpMRI in detecting and staging PCa, false positive and false negative results are reported, and potential pitfalls in interpretation exist. Therefore, radiologists reporting prostate mpMRI should be aware of those pitfalls to improve their diagnostic accuracy. Informed Consent Statement: Patient consent was waived due to the anonymized data used in the retrospective study.

Data Availability Statement:
The detailed data presented in this study are available from the corresponding author upon request.

Acknowledgments:
The authors would like to thank Tomasz Żurowski for image conversion and processing.

Conflicts of Interest:
The authors declare no conflict of interest.
Abbreviations mpMRI-multiparametric MRI; PCa-prostate cancer; GS-Gleason score; PSA-prostatespecific antigen; DWI-diffusion-weighted imaging; ADC-apparent diffusion coefficient; DCEdynamic contrast enhanced; P -peripheral zone; T -transition zone; AFMS-anterior fibromuscular stroma; PI-RADS-Prostate Imaging-Reporting and Data System; ROI -region of interest Figure 19. DWI sequence affected by artifacts from the gas in the rectum-rendering interpretation of the PZ in posterior gland impossible: (a) DWI b 2000; (b) ADC map. However, in this patient, a focal early enhancement is visible on DCE (arrow) (c), which corresponds to a poorly visible, hypointense focal lesion on T2-weigted image (arrow) (d), on the background of a larger area of reduced signal intensity; the lesion was reported as PI-RADS 4; (e) whole-mount histopathology after radical prostatectomy reveals prostate cancer GS 4 + 3 in this location in the right PZ (area outlined with black continuous line).

Conclusions
Recently, mpMRI has evolved as a pivotal diagnostic imaging modality to detect or rule out significant prostate cancer. However, despite the high accuracy of mpMRI in detecting and staging PCa, false positive and false negative results are reported, and potential pitfalls in interpretation exist. Therefore, radiologists reporting prostate mpMRI should be aware of those pitfalls to improve their diagnostic accuracy.