Integrating multiparametric prostate MRI into clinical practice

Abstract

Multifunctional magnetic resonance imaging (MRI) techniques are increasingly being used to address bottlenecks in prostate cancer patient management. These techniques yield qualitative, semi-quantitative and fully quantitative biomarkers that reflect on the underlying biological status of a tumour. If these techniques are to have a role in patient management, then standard methods of data acquisition, analysis and reporting have to be developed. Effective communication by the use of scoring systems, structured reporting and a graphical interface that matches prostate anatomy are key elements. Practical guidelines for integrating multiparametric MRI into clinical practice are presented.

Figure 1

Communicating multifunctional MRI data at diagnosis and results of therapy monitoring. (a) A 67-year-old male with raised serum PSA (5.3 ng/ml). MRI scan before TRUS biopsy shows diffuse low signal intensity change in the peripheral zone bilaterally (yellow arrow) without focal features (T2-weighted score 3/5). The diffusion sequences show bilateral abnormalities on the high b-value image (b800 s/mm²) and ADC map (score 2/5) with no focal features. DCE-MRI early subtraction image shows diffuse enhancement with no focal features with washout curve (yellow line) (score 3/5). The MRSI image from the peripheral zone is normal (score 1/5). A small 6-mm tumour (red arrow) behind the anterior fibromuscular stroma is barely visible on T2-weighted images (2/5). The diffusion sequences are consistent with a focal tumour with an ADC value of 835 µm²/s (score 4/5). DCE-MRI shows the focal mass lesion which has a washout pattern (score 5/5). The MRSI is normal (1/5). Results of TRUS biopsy were small foci of Gleason 3 + 3 from the left side with prostatitis. It is clear that TRUS cannot sample the anterior gland tumour. The patient went onto an active surveillance program and received antibiotics for prostatitis. (b) Re-evaluation MRI after 1 year. The T2-weighted image again shows diffuse low signal intensity change in the peripheral zone bilaterally (yellow arrow) without focal features (T2-weighted score 3/5). The diffusion sequences show a bilateral abnormality on the b800 image and ADC map (score 2/5) with no focal features. DCE-MRI early subtraction image shows diffuse enhancement with no focal features but no washout is observed (yellow line) (score 2/5). The MRSI image from the peripheral zone remains normal (score 1/5). The anterior gland tumour has increased in size to 10 mm (T2-weighted score 3/5). The diffusion sequences show an enlarging tumour with an ADC value of 583 µm²/s (score 4/5). DCE-MRI shows a focal mass lesion with washout pattern (score 5/5). The MRSI remains normal (1/5). (c) Pictorial report of first year follow-up study (b) used to present the multifunctional MRI findings prior to template biopsy. Template biopsy of the left anterior lesion contained a 5-mm core of Gleason 3 + 4 cancer. Bilateral peripheral zone tumour foci (Gleason 3 + 3) were also seen. The patient opted for HIFU therapy of the anterior gland tumour. (d) Re-evaluation MRI after androgen deprivation therapy prior to HIFU therapy. The T2-weighted image shows prostate gland shrinkage. The T2-weighted image continues to show an abnormality at the site of the anterior gland lesion (score 3/5) which is not well seen on the DW image or ADC map (ADC 1355 µm²/s) (score 3/5). DCE-MRI show a plateau type curve at the location of the anterior tumour with a focal, asymmetric lesion still present (score 4/5) type. The peripheral zone shows slow washin only (score 1/5). There is marked metabolic atrophy on MRSI at both locations consistent with glandular atrophy induced by hormonal therapy.

Figure 1

Communicating multifunctional MRI data at diagnosis and results of therapy monitoring. (a) A 67-year-old male with raised serum PSA (5.3 ng/ml). MRI scan before TRUS biopsy shows diffuse low signal intensity change in the peripheral zone bilaterally (yellow arrow) without focal features (T2-weighted score 3/5). The diffusion sequences show bilateral abnormalities on the high b-value image (b800 s/mm²) and ADC map (score 2/5) with no focal features. DCE-MRI early subtraction image shows diffuse enhancement with no focal features with washout curve (yellow line) (score 3/5). The MRSI image from the peripheral zone is normal (score 1/5). A small 6-mm tumour (red arrow) behind the anterior fibromuscular stroma is barely visible on T2-weighted images (2/5). The diffusion sequences are consistent with a focal tumour with an ADC value of 835 µm²/s (score 4/5). DCE-MRI shows the focal mass lesion which has a washout pattern (score 5/5). The MRSI is normal (1/5). Results of TRUS biopsy were small foci of Gleason 3 + 3 from the left side with prostatitis. It is clear that TRUS cannot sample the anterior gland tumour. The patient went onto an active surveillance program and received antibiotics for prostatitis. (b) Re-evaluation MRI after 1 year. The T2-weighted image again shows diffuse low signal intensity change in the peripheral zone bilaterally (yellow arrow) without focal features (T2-weighted score 3/5). The diffusion sequences show a bilateral abnormality on the b800 image and ADC map (score 2/5) with no focal features. DCE-MRI early subtraction image shows diffuse enhancement with no focal features but no washout is observed (yellow line) (score 2/5). The MRSI image from the peripheral zone remains normal (score 1/5). The anterior gland tumour has increased in size to 10 mm (T2-weighted score 3/5). The diffusion sequences show an enlarging tumour with an ADC value of 583 µm²/s (score 4/5). DCE-MRI shows a focal mass lesion with washout pattern (score 5/5). The MRSI remains normal (1/5). (c) Pictorial report of first year follow-up study (b) used to present the multifunctional MRI findings prior to template biopsy. Template biopsy of the left anterior lesion contained a 5-mm core of Gleason 3 + 4 cancer. Bilateral peripheral zone tumour foci (Gleason 3 + 3) were also seen. The patient opted for HIFU therapy of the anterior gland tumour. (d) Re-evaluation MRI after androgen deprivation therapy prior to HIFU therapy. The T2-weighted image shows prostate gland shrinkage. The T2-weighted image continues to show an abnormality at the site of the anterior gland lesion (score 3/5) which is not well seen on the DW image or ADC map (ADC 1355 µm²/s) (score 3/5). DCE-MRI show a plateau type curve at the location of the anterior tumour with a focal, asymmetric lesion still present (score 4/5) type. The peripheral zone shows slow washin only (score 1/5). There is marked metabolic atrophy on MRSI at both locations consistent with glandular atrophy induced by hormonal therapy.

Figure 2

MRSI curve shape assessments. Representative spectra acquired at 3 T (no endorectal coil) with scores 1–5 (from left to right). Choline (Cho) + creatinine (Cr) to citrate (Ci) ratios of the individual spectra are given above each spectrum. The irregular line of each spectrum is the acquired data. The smooth lines are the corresponding fitted data from which the C + C/C ratio is calculated.