The T1 sequence consists of a T1-weighted (T1W) Fast Spin Eco (FSE) from the aortic bifurcation to the symphysis pubis, assessed on the axial plane (Figure 1). The T1W sequence cannot discriminate various prostate gland zones and therefore its main utility is in detecting the presence of post-biopsy bleeding (a common cause of false positives in PCa diagnosis) (Figure 2), nodal disease, and bone metastasis[13].

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Figure 1 Normal prostate anatomy on magnetic resonance imaging - T1 and T2-weighted images. A: T1-weighted axial image of a normal prostate: Homogeneous gland, isointense to the adjacent pelvic muscles. It is not possible to differentiate any anatomical detail; B: Axial image of the prostate shows peripheral zone (PZ - black arrow) as a hyperintense area with a U-shape. The transitional zone (TZ - white asterisk) has a hypointense multinodular pattern (“organized chaos”). Anterior fibromuscular stroma (white arrow) is seen as a hypointense area anterior to the TZ and medial to both anterior PZ horns. The “capsule” (arrowhead) is seen as a hypointense rim surrounding the gland; C: Coronal image shows the hyperintense seminal vesicles located cephalad to the base of the prostate (black arrows). Ampulla of vas deferens (VD - black arrowhead) can be seen as paired structures medial to both seminal vesicles (SV). Prostate central zone (asterisk) is seen as a hypointense area located in the base of the prostate gland. Urethra (white arrow), levator ani muscle (white asterisk) and external sphincter (white arrowhead) are also shown; D: Sagittal image shows the vas deferens (black arrow), seminal vesicles (arrowhead) and the ejaculatory duct (white arrow).

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Figure 2 T1 (A) and T2-weighted images (B) of the midgland of the prostate. The left peripheral zone has a hyperintense area (white arrow, A) in T1-weighted image that correlates with a hypointensity (white arrow in B) in T2-weighted image, suggestive of bleeding in a patient with a recent transrectal ultrasound prostate biopsy.

The T2 sequence consists of a T2-weighted (T2W) FSE sequence that includes the prostate gland and seminal vesicles (Figure 1B-D). The T2W sequence is normally performed in three spatial planes (axial, coronal, and sagittal). T2W sequence is capable of discriminating various anatomic zones of the prostate, including the peripheral, central, and transitional zones, as well as the anterior fibromuscular stroma, neurovascular plexus, surgical pseudocapsule, and the prostate capsule. In normal prostates, the peripheral zone is homogeneous and hyperintense on MRI (Figure 1B). In adults, the transitional zone is larger, with a heterogenous signal and hyperplastic nodules of varying appearance, thus this zone can sometimes present diagnostic difficulties[13].

Cancerous prostate lesions usually appear as nodules or hypointense areas on T2W images, with less well-defined margins at the transitional zone. A limitation of the T2W sequence is that benign and malignant alterations often overlap. According to the Prostate Imaging Reporting and Data System (PIRADS) v2 model (see PIRADS reporting and interpretation model, version 2), the T2W sequence is key to the diagnosis of PCa in the transition zone[11] (Figure 3A). It is also useful in the diagnosis of local dissemination[14].

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Figure 3 A 71-year-old patient. A: T2-weighted axial image at the level of the midgland of the prostate shows a hypointense nodular lesion at the transitional zone/anterior fibromuscular stroma, with a diameter of 26 mm (arrow); B and C: ADC map (B) and DWI image (C) show a marked hypo- and hyperintensity, respectively, in relation to restriction of diffusion (white arrows); D: DCE image with significant enhancement of the lesion (arrow). The characteristics of the nodule are compatible with a PIRADS 5 lesion and the marked restriction of the diffusion suggests a high-grade clinically significant prostate carcinoma, confirmed by the results of a MRI-guided transrectal ultrasound prostate biopsy (Gleason 4 + 4).

Diffusion sequences [diffusion-weighted MRI (DW-MRI) and apparent diffusion coefficient (ADC)] are performed in the axial plane and include the prostate and seminal vesicles (Figure 3B and C). These sequences are used primarily to evaluate the movement of the free water molecules in the interstitial space and through the cellular membrane. The behavior of lesions on DW-MRI and ADC is conditioned by cell density, the extracellular space, the integrity of cell membranes, and the extent of glandular organization. A correct assessment is based on a qualitative (high b-value DWI) and quantitative (ADC map) evaluation of the images. In PCa, the presence of impeded diffusion appears as a high signal intensity on the DWI and low intensity on the ADC map[13].

PCa presents architectural changes that restrict water diffusion. The more aggressive the tumour, the more pronounced these changes tend to be. For this reason, diffusion sequences are valuable not only to characterise lesions likely to be malignant, but also to help to predict the Gleason score of the lesions[15,16] (Figure 3). Benign lesions, such as those occurring secondary to prostatitis, usually present less diffusion restriction (Figure 4)[17].

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Figure 4 Prostate magnetic resonance imaging of a 64-year-old patient. A: T2-weighted image shows an area of hypointensity in the right peripheral zone of the midgland of the prostate (black arrow); B: A discrete restriction of diffusion in ADC map (white arrow); C: DWI image (white arrow); D: Enhancement on DCE image (white arrow), suggestive of prostatitis, confirmed by transrectal ultrasound biopsy.

According to the PIRADS v2 model, diffusion sequences are crucial to the diagnosis of PCa in the peripheral zone and in characterising indeterminate lesions in the transition zone[12] (Figure 5B and C).

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Figure 5 An 82-year-old patient with PIRADS 5 lesion in the basal left peripheral zone showing hypointensity (white arrows) in T2-weighted image (A), restriction of diffusion in apparent diffusion coefficient map (B) and diffusion-weighted magnetic resonance image (C), DCE shows significant early enhancement of the suspicious area (D). MRI-guided transrectal ultrasound biopsy confirmed a clinically significant prostatic carcinoma (Gleason 5 + 4). DCE: Dynamic contrast enhancement; MRI: Magnetic resonance imaging.

Dynamic contrast-enhanced (DCE)-MRI is performed in the axial plane and includes the prostate and seminal vesicles. This sequence is performed prior to endovenous gadolinium administration and up to 4 min afterwards (Figure 5D).

In malignant lesions, the most common phenomenon observed on DCE-MRI is early uptake of the contrast material and early washout (Figure 5D). However, this behaviour is relatively variable and sometimes overlaps with that of benign lesions. According to PIRADS v2, although DCE sequences have a secondary value, their main value is in their contribution to the characterization of indeterminate lesions in the peripheral zone[12].

Pharmacokinetic models of DCE-MRI perfusion allow us to quantify various parameters to evaluate contrast perfusion, including k^trans (the volume transfer constant, which reflects the efflux rate of gadolinium contrast from the vascular compartment through the endothelium to the interstitial space), k_ep (rate of return to the vascular space), and Ve (the fractional volume of the extracellular tumour space). Using these data, it is possible to build parametric maps that represent the intratumoral heterogeneity of the spatial distribution of these parameters. However, at present, no conclusive results are available to support the use of these parameters for diagnostic purposes.

MRI is the imaging technique of choice to determine whether the tumor is organ-confined or extra-glandular. In the year 2012, the ESUR proposed a 5-point scale to establish the probability of extracapsular extension (ECE) based on direct and indirect signs[14] (Table 1 and Figure 6).

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Figure 6 Prostate carcinoma with extracapsular extension in a 72-year-old patient. A: T2-weighted axial image of the pelvis at the level of midgland of the prostate shows a marked hypointensity in the left peripheral zone and disruption of the “capsule”, distorting the normal anatomy of the left neurovascular bundle with measurable extracapsular extension (ESUR Score 5); B and C: ADC map (B) and DWI-images (C) demonstrate a significant restriction of diffusion, with hypointensity in the ADC and hyperintensity in the DWI-images that extend beyond the prostate “capsule” (arrows). Surgical specimen confirmed a pT3a prostate carcinoma. ADC: Apparent diffusion coefficient; DWI: Diffusion-weighted magnetic resonance imaging.

Schieda et al[18] evaluated the ability of this 5-point scoring system to predict ECE compared to a “non-standardized” reporting modality. Those authors concluded that the optimal sensitivity/specificity was achieved with a score of “≥ 3”. In addition, the scale was more sensitive than the non-standardized modality (59.5% vs 24.5%, P = 0.01) without significant differences in specificity (68.0% vs 75.0%, P = 0.06).

Several clinical nomograms are available to predict the likelihood of ECE. The two most common nomograms are the Partin tables (which include several variables: PSA, biopsy-based Gleason score, and clinical stage)[19] and the nomogram developed at the Memorial Sloan-Kettering (MSK) Cancer Center (which adds prostate biopsy results - specifically, the percentage of positive cylinders)[20]. Recently, Feng et al[21] conducted a retrospective study of 112 patients who underwent mpMRI prior to RP to determine if mpMRI could improve the predictive capacity of the Partin tables and the MSK nomogram for ECE. The authors found that the area under the curve (AUC) for the Partin and MSK nomograms for predicting ECE was 0.85 and 0.86, respectively. When mpMRI was added, the AUC increased, respectively, to 0.92 and 0.94.

In the most recent guidelines published by the European Society of Urology, mpMRI has been included as a local staging technique in the following patient risk groups: High-risk disease; intermediate risk disease with predominantly Gleason pattern 4; and low-risk disease if mpMRI is considered necessary for treatment planning[11].

The diagnosis of metastatic disease is essential to ensure proper therapeutic management and MRI has proven its value as a diagnostic tool for metastasis (Figure 7). In a recently published meta-analysis, Shen et al[22] compared the relative utility of choline PET/CT, MRI, and bone scintigraphy in the diagnosis of bone metastasis in patients with PCa. The authors reported sensitivity values, respectively of 91%, 97%, and 79% and specificity values of 99%, 95%, and 82%. These differences between these imaging modalities were statistically significant, with bone scintigraphy significantly less sensitive and less specific than the other two techniques. By contrast, MRI presented the highest diagnostic sensitivity for detecting metastasis.

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Figure 7 A 54-year-old patient with recently diagnosed prostate carcinoma. A: T2-weighted axial image of the pelvis shows an ill-defined hyperintense area in the right pubis (arrow); B and C: ADC map (B) and DWI images (C) show restriction of diffusion in the same area (arrow); D: DCE image presents enhancement of the lesion after IV gadolinium (arrow). MRI findings were suspicious for pelvic bone metastasis, with no evidence of such lesion on staging abdomino-pelvic CT scan performed a week earlier (E) and in a previous bone scintigraphy (not shown). Bone metastasis was confirmed on clinical evolution. MRI: Magnetic resonance imaging; DCE: Dynamic contrast-enhanced; CT: Computed tomography.

Lecouvet et al[23] evaluated 100 patients at a high risk of metastasis to compare the diagnostic yield of whole-body DW-MRI vs CT and bone scintigraphy with Technetium Tc 99m (supported by simple X-ray when necessary) in the diagnosis of bone and nodal metastasis. Bone scintigraphy (± X-ray) plus CT had a sensitivity of 84% vs 91%-94% for whole-body DW-MRI (P < 0.05); specificity values were, respectively, 94%-97% vs 91%-96% (P > 0.05). The authors conclude that one-step, whole-body MRI can effectively assess nodal and bone metastasis in patients with high-risk PCa, thus eliminating the need for multimodal diagnosis (Figure 8).

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Figure 8 A 51-year-old patient with a history of Gleason 4 + 5 prostate carcinoma treated with hormone therapy. A: Re-staging bone scintigraphy was negative for bone metastases; B and C: Sagittal (B) and coronal (C) images of abdominal CT scan show a diffuse axial bone altered density that could not rule out bone metastases, along with multiple retroperitoneal and pelvic enlarged nodes suggesting malignant adenopathies (white arrows in C); D and E: Sagittal (D) and coronal (E) whole-body MRI images clearly show multiple bone metastases and adenopathies, along with hepatic nodules (black arrows in F, axial abdominal MRI) suspicious for metastatic disease. MRI: Magnetic resonance imaging.

Conde-Moreno et al[24] compared whole-body DW-MRI to choline PET/CT in the diagnosis of metastatic disease, finding that choline PET/CT had a greater sensitivity whereas whole-body DW-MRI had a greater specificity. Given these findings, the authors conclude that these techniques are complementary.

The value of MRI in the diagnosis of bone and nodal metastasis has been recognized by the ESUR[14]. The European Society of Urology also contemplates the use of MRI as an alternative technique to detect possible metastasis in intermediate and high-risk patients[11].

Reported 5-year biochemical relapse rates after radiotherapy range from 15% in low-risk patients to 67% in high-risk cases[9]. Both DW-MRI and DCE-MRI allow us to detect recurrences after radiotherapy. In a group of 24 patients who developed biochemical relapse following radiotherapy, Kim et al[25] performed prostate mpMRI at 3T (phased array coil), followed by TRUS-guided biopsy. They assessed the diagnostic performance of both DW-MRI and DCE-MRI to detect recurrent disease. The sensitivity, specificity, and diagnostic accuracy of DW-MRI were 49%, 93%, and 82%, respectively, vs 49%, 92% and 81% for DCE-MRI. Combined DW-MRI and DCE-MRI resulted in a sensitivity, specificity, and diagnostic accuracy of 59%, 91% and 83%, respectively.

Tamada et al[26] demonstrated the diagnostic value of mpMRI to assess recurrence after brachytherapy, reporting a sensitivity of 77%, specificity of 92%, and diagnostic accuracy of 90%.

Several studies have evaluated the impact of mpMRI staging on PCa risk group classification and on treatment decisions for EBRT (Table 2). Couñago et al[6] assessed 274 patients staged initially by DRE and TRUS and subsequently by 3T mpMRI prior to the final EBRT treatment decision. The risk group classification shifted after mpMRI in 32.8% of cases after all factors (PSA, Gleason score and T-stage) were considered. In addition, in 43.8% of cases (52.5% depending on criteria used to indicate or not ADT in intermediate-risk patients), this led to a change in some aspect(s) of the radiotherapy treatment (treatment volume, dose, and ADT). Finally, the mpMRI results were validated in the subgroup of surgical patients, showing a 70.0% sensitivity and 93.8% specificity for ECE.

Panje et al[8] evaluated 122 patients staged using 1.5T or 3T (38% of sample) phased-array-body coil MRI. Most (53.3%) patients had received ADT prior to the mpMRI. The authors found that the use of mpMRI resulted in risk group modification in 28.7% of cases. Because the influence of 1.5T MRI and the use of ADT prior to mpMRI on the results is not known, it is difficult to perform a direct comparison with other studies.

Liauw et al[27] evaluated the role of endorectal coil mpMRI at 3T prior to EBRT in a group of 122 PCa patients, finding that mpMRI resulted in a change in therapeutic approach (indication for active surveillance, brachytherapy in monotherapy and dose modification, treatment volume, and use of ADT in EBRT) in 18% of patients. Recently, Pullini et al[28] prospectively evaluated 44 patients with PCa to determine the impact of mpMRI at 3T on staging and treatment decisions for EBRT, finding that staging by mpMRI resulted in a change in risk group classification in 41% of patients, thus potentially impacting the EBRT treatment decision.

Based on the studies described above, it is clear that mpMRI staging has a significant impact on radiotherapy treatment decisions, with risk group modifications ranging from 18% to 41% of patients, depending on the study. This wide variability may be attributable to numerous different factors, including the following: The MRI (magnet and coil, protocol used, experience of the radiologist); the initial clinical staging (experience of the clinician with DRE/TRUS, the use of CT to evaluate pelvic lymph nodes, etc.); the clinical characteristics of the patient cohort; the treatment protocol at each centre (dose, fractionation, target volume, indication for ADT, use of brachytherapy, etc.); the use of ADT prior to MRI; and finally the inclusion (or not) of metastatic patients in the final results.

Despite this heterogeneity, one finding common to all these studies is that a large percentage of patients staged by mpMRI are upstaged compared to conventional clinical staging. As a consequence, mpMRI staging implies that more patients will be classified as intermediate risk, high-to-very high risk, or metastatic patients. Nevertheless, it is worth noting that risk group downgrading has been reported in a small percentage (4%-12%) of patients[8,28].

Despite the clear influence of mpMRI staging on EBRT treatment decisions, numerous questions remain unresolved. For instance, we do not know which patient groups would benefit most, in terms of cost-effectiveness, from mpMRI staging. Nor is it clear if changes in therapeutic management based on MRI findings will increase survival and/or quality of life in these patients. The clearest example of this can be seen in low-risk patients in which upstaging after mpMRI is common (20%-50%) even though long-term biochemical control in this risk cohort (staged exclusively by conventional DRE) and treated with EBRT is excellent (93% at 10 years’ follow up)[29]. Therefore, we must exercise caution with regard to the changes in tumour stage that can result from the use of these newer, more precise imaging tests. In this sense, more prospective, multicentric studies are needed to better clarify the role of mpMRI prior to EBRT.

MRI has proven to be highly useful in radiation oncology in improving the accuracy of treatment volume delineation. The use of MRI allows for more precise identification of the prostate gland location and thus more accurate contouring, especially of the prostate apex, which can help to avoid over- or under-estimation of the microscopic volume that commonly occurs with CT-based contouring[30].

mpMRI can also help to rule out the presence of high-grade disease in the transition zone at the anterior base, thus allowing for lower doses to the bladder neck. In addition, MRI is highly useful in identifying the anatomic structures involved in erections: The internal pudenda artery, the periprostatic nerve fibers, and the penile bulb. The improved anatomic definition of these structures with mpMRI could help to limit the radiation dose to these areas, which could potentially lead to higher rates of erectile function preservation and, consequently, better quality of life[30]. Therefore, compared to CT-based treatment volumes, MRI allows for the delineation of a smaller clinical target volume (CTV), distinguishing the CTV from normal tissue, suggesting that MRI-based contouring can reduce treatment-related toxicity in PCa[8].

The reliability of mpMRI in tumour staging plays an increasingly important role in advanced radiotherapy techniques such as intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). In these highly-conformal techniques with narrow treatment margins, it is vitally important to accurately detect the presence of extracapsular disease or seminal vesicle invasion and to include these areas within the treatment volume to avoid geographic loss and, consequently, underdosing[8].

Multiple authors have investigated the capacity of mpMRI to detect post-prostatectomy relapses, with detection rates ranging from 84%-95% in series that use endorectal coil MRI in patients with median PSA > 1 ng/mL, many of whom also had palpable disease on DRE[9,35,36]. Other studies carried out in patients with lower PSA levels (median PSA, 0.3-0.59 ng/mL) by endorectal coil MRI[37,38] and/or pelvic MRI have reported recurrence rates ranging from 24%-91%[39-42] (Table 3). This variability among studies is likely due to several factors, including: Retrospective study design; sample size and sample heterogeneity; differences in the radiologists’ experience level; the use of different MRI sequencing modalities; and difference in relapse criteria.

Results from a retrospective study[43] and from a meta-analysis[44] suggest that the ¹¹C or ¹⁸F-choline PET/CT has a higher detection rate for local, nodal, or metastatic recurrences post RP when the PSADT is < 6 mo and PSA values are > 1 ng/mL. By contrast, in patients with lower PSA values, mpMRI has proven to be more sensitive in detecting local recurrences[22,45-48] and in small-sized (< 10 mm) local relapses[47]. Other authors have found that diagnostic rates for visible pelvic relapses are higher when mpMRI and PET/CT are combined vs MRI or choline PET/CT alone[49-51]. Recently, studies that investigated the use of PET/CT with PSMA (prostate-specific membrane antigen) ligands have reported higher detection rates for local relapse compared to choline PET/CT, even in cases with low PSA levels[52]. However, other authors, including Freitag et al[53], have found that adding MRI to PET provides additional value even when 68Ga-PSMA-11 is used as a tracer in PET/CT.

Several factors, including PSA levels at recurrence, the PSADT, and the presence of compromised resection margins, have all been significantly associated with mpMRI findings. Several authors have defined pre-radiotherapy PSA cut-off values, ranging from > 0.3[37] to > 0.5[40] or ≥ 0.54[39] ng/mL, as clinical predictors of MRI positivity. Eifler et al[19] reported a higher probability of visible local relapse in patients with PSADT > 14 mo. In addition, a PSADT < 6 mo has been associated with higher incidence of nodal relapse, even with PSA levels < 1 ng/mL. Hernández et al[41] reported a median PSADT of 5.12 mo in patients with nodal recurrence vs 12.7 mo in patients without evidence of nodal disease on MRI (P = 0.17). Finally, a study that used MRI lymphography (ferumoxtran-10) to assess nodal involvement found that patients with positive lymphography presented a median PSADT of 3.8 mo[54].

Most local recurrences occur in the peri-anastomotic and retrovesical regions[41,55,56], although up to 22% of recurrences have been diagnosed at the resection site of the vas deferens[57].

Data on the efficacy of MRI to detect nodal relapses after RP are scant, particularly in patients with low PSA values. However, an incidence between 5%-10% has been estimated[37,41], most commonly involving the external iliac lymph node chains. It has been suggested that DW-MRI could increase the detection of nodal relapses, with a reported 90% efficacy rate in nodes < 1 cm[58] (Figure 10).

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Figure 10 Lymph node study. A: Axial T2-weighted fast-spin echo image shows right external iliac lymph nodes; B and C: Axial diffusion sequences; C: Restricted diffusion in ADC map; D: Axial gradient-echo T1-weighted perfusion image showing a high peak enhancement; E: Color map; F: Curve; ADC: Apparent diffusion coefficient.

The two studies that used MRI with ferromagnetic contrast (ferumoxtran-10) to evaluate patients with biochemical relapse after RP reported positive nodes (< 1 cm) in 72% and 20% of patients, respectively, even with low PSA levels[54,59]. The main limitation of these studies is that ferumoxtran-10 was authorized only for research purposes.

Recent research suggests that the use of whole-body MRI (WB-MRI), together with WB-DW-MRI, may allow assessment of nodal recurrence and bone metastasis with a single imaging modality. These approaches show greater sensitivity and specificity than conventional imaging and will facilitate the evaluation and monitoring of response to systemic treatments[60].

Individualized treatment planning should assure that the relapse site is included within the CTV in accordance with published guidelines.

Irradiation (or not) of the lymph node stations: The benefits of elective pelvic irradiation in SRT is controversial since currently available data include only retrospective studies; however, findings from those studies suggest that pelvic irradiation increases both biochemical control[61] and biochemical relapse-free survival[62]. It has been suggested that RP may lead to changes in the lymphatic drainage pattern and that these are not adequately included in the CTV when contoured according to current recommendations[63,64].

Irradiation of oligometastatic bone disease: Currently, the decision to irradiate oligometastatic bone lesions is considered on an individual basis by consensus at multidisciplinary urological tumour boards, or in the context of a clinical trial.

It would be interesting to investigate the impact of irradiating only the nodal stations in patients with a short PSADT whose mpMRI images indicate the presence of nodal disease without prostate bed involvement. Similarly, it would also be interesting to conduct a study in which patients with a long PSADT (> 10 mo) and local disease alone received irradiation only to the local disease site. In both of these scenarios, the impact of ablative RT techniques such as stereotactic body radiotherapy (SBRT) should be investigated.

We hypothesize that treating the prostatectomy bed at conventional doses while simultaneously increasing the dose to the relapse site detected on MRI could improve outcomes without increasing toxicity[65]. In fact, high dose irradiation delivered exclusively to the relapse site could be curative and this approach would also minimize irradiation of healthy tissue, thus reducing the risk of side effects.

The addition of hormonotherapy to SRT remains controversial. In clinical practice, the trend is to administer combined treatment in patients with high-risk disease and/or poor prognostic factors. The RTOG 9601 study showed a significant increase in overall survival at 10 years in patients with post-RP biochemical relapse who were treated with SRT (64.8 Gy) plus bicalutamide 150 mg for 2 years vs patients who received RT alone [82% vs 78%, hazard ratio: 0.75 (95%CI: 0.58-0.98), P = 0.036][66]. The results of studies currently underway, such as RADICALS and RTOG 0534, should definitively determine the benefit of hormonotherapy in patients who undergo postoperative radiotherapy. However, it should be pointed out that none of the aforementioned trials have included mpMRI or PET/CT for the purpose of diagnosing and locating tumour recurrences. As we have suggested above, more intensive treatment at the relapse site could improve SRT outcomes, with or without hormonotherapy.

Various studies have shown the potential utility of ADC and K^trans to monitor response to radiotherapy in patients with PCa[67,68]. This application of MRI could be used to investigate the impact of new focal therapies administered early in patients with persistent disease or local relapse.

PET/MRI is a new multimodal imaging technique that improves diagnostic imaging, with a promising future in the evaluation of PCa. In addition to diagnosis and staging, PET/MRI plays an important role in detecting recurrences in patients with biochemical relapse. In bone metastasis, the use of PET/MRI improves the detection and characterization of bone lesions, especially with the use of new radiotracers (¹⁸F-FNa, PSMA, choline), providing functional information as well as greater anatomic information due to the incorporation of MRI[50,69,70]. These data are essential for ablative radiotherapy.

The future of imaging in PCa will be marked by improvements in equipment and in the sequences and antennas used, especially 3T equipment, diffusion sequences, and multichannel surface coils (≥ 128 channels).

It is worth highlighting the incipient but growing use of MRI in radiation oncology departments. MRI is used not only for simulations, workflow, and treatment planning, but it is also being incorporated into linear accelerators to guide radiotherapy treatment[71].

At least one study has been conducted showing that MRI and genetic testing can improve the reliability for risk stratification in patients with PCa[72].

Several studies have assessed the role of MRI-guided dose escalation (EBRT or brachytherapy) to the dominant intraprostatic lesion[73,74].