Prostate MRI is powerful helpful tool for early detection of prostatic cancer, special techniques are used to improve the early detection of prostate cancer such as DWI, dynamic-contrast enhanced MRI and MR spectroscopy.
Carcinoma of the prostate is the commonest form of human carcinoma, found at autopsy in 30% of men at the age of 50 and in over 80% of men in their 90s.
The number of cases of prostate cancer will rise further as the population at risk (older men) grows with lengthening of life expectancy.
The following patients should have MRI at first diagnosis:
1. Symptomatic patients.
2. Patients at higher risk of local / meta-static spread.
3. Potential surgical candidates.
4. Patients with palpable apical tumors.
When MRI is used for newly diagnosed patients, the objectives for its usage are:
1. To delineate the intra- and extra-prostatic extent of the local disease.
2. Prostatic cancer is often multifocal, and the detection of the dominant prostatic cancer nodule.
3. To detect the presence of cancer at the prostatic apex.
4. To detect the presence and location(intra- versus extra-pelvic) of metastatic nodal involvement.
5. To detect the presence of bone metastases.
Sample case showing the entire Prostate MRI Exam process we perform at our center
1.Example of total imaging matrix capability.
This 56-year-old male patient had 3 negative transrectal ultrasound (TRUS) guided biopsies for rising serum PSA levels over 2–3 years. In May 2006 the PSA level was 5.8 and now it had risen to 14.6 ng/ml.
A multifunctional study was undertaken. Morphology, DW-MRI, DCE-MRI and MRSI examinations were all obtained within a 1-hour examination time on Siemens 1.5T MAGNETOM SATS – Symphony scanner with Tim (Total imaging matrix) capability using surface coils only.
Evaluations of data obtained were done on Siemens Leonardo Workstation (MMWP) using Viewing, MRP with fusion, MeanCurve and Spectroscopy Taskcards.
1A -Viewing TaskCard. Top-Left:
T2-weigthed image shows some low signal in the peripheral zone at the base of the prostate gland in the midline. No central gland abnormality is shown.
Top-right: ADC map (calculated from b-value 0t, 50t, 100t, 250t, 500t and 750t images) shows restricted diffusion in the left central gland measuring 1.3 cm (arrow).
Bottom-left: Fusion image (b 1200 trace+T2-weighted) with 50% opacity confirms that the restricted diffusion is co-located in the left central gland indicating high cellularity.
2. Anatomic and functional imagingRising PSA MPR TaskCard.
Anatomical and functional images are co-localised using advanced, non-rigid software algorithms with false colour overlays of high b-value (b1200t) images. The TaskCard shows the prostate in 3 planes and indicates the site of high cellularity which can be used to indicate where to biopsy and can guide focal therapies.
3. Analysis of dynamic contrast enhancement 1C- The MeanCurve TaskCard
can be used to analyze dynamic contrast enhanced images (DCE-MRI). High spatial. resolution DCE-MRI data were acquired every 30 seconds (twice before and 5 times post 0.1 mmol/kg Gd-DTPA).
Top-left: Regions of interest (ROIs) are placed in the region of the restricted diffusion (red ROI), in the right peripheral zone (yellow ROI) and in ischio-rectal fat.
Top-Right: Graphic depiction of con- trast-enhancement with time shows marked early enhancement of the mass in the left central zone with some wash- out (red line).
Bottom-left: Subtraction image depicts more clearly the enhancing regions and can be used to place ROIs.
Bottom-right: Late post contrast enhanced T1-weighted image with fat-suppression.
The area of high enhancement is difficult to see.
1D- Spectroscopy TaskCard.
MR spectroscopic imaging (5 x 5 mm voxel) from the left central gland lesion shows abnormal spectrum with high choline and low citrate levels (Choline: citrate ration: 0.72).
The information obtained with these tools indicates a highly suspicious lesion suggestive of prostate cancer in the left central gland (mass, high cellularity, high perfusion and abnormal metabolism).
This area was specifically targeted for biopsy and a cancer was diagnosed.
5. Nodal evaluation with Diffusion Weighted MRI Rising PSA MPR Nodal evaluation with diffusion- weighted MRI
72-year-old male patient with new diagnosis of prostate cancer. This is the same patient as in figure 5.
3A- Top-left: There is an equivocally enlarged lymph node (7 mm) in the right internal iliac region (circled).
Top-right: on b0 images, the lymph node is difficult to see because of adjacent hyper- intensity in vascular structures. Note the hyperintense signal in the bladder anteriorly.
Bottom-left: b 1400 trace image shows persistent hyperintensity of the lymph node; all other pelvic structures are no longer hyper- intense.
Bottom-right: ADC maps show moderate restriction of water diffusion in the node (1170 x 10-5 mm2/s). Taken together these findings are suggestive of metastatic invasion.
PI-RADS (Prostate Imaging Reporting and Data System)
refers to a structured reporting scheme for evaluating the prostate for prostate cancer. It is designed to be used in a pre-therapy patient.
PI-RADS 1: very low (clinically significant cancer is highly unlikely to be present)
PI-RADS 2: low (clinically significant cancer is unlikely to be present)
PI-RADS 3: intermediate (the presence of clinically significant cancer is equivocal)
PI-RADS 4: high (clinically significant cancer is likely to be present)
PI-RADS 5: very high (clinically significant cancer is highly likely to be present)
I: TZ with stromal & glandular hyper-plasia without focal hypointense nodular or oval-shaped
II: Round hypointense lesion with signs of well-defined capsule. Band-shaped hypoin-tense regions
III: Changes not falling into categories 1+2 & 4+5
IV: Oval-shaped anterior hypointense lesion without evidence of capsular involvement, “charcoal sign”: homogeneous hypointense lesions with loss of matrix + ill-defined margins
V: Oval-shaped or round mass with compression/retraction/
extension of the anterior capsule.
mass with architectural disintegration, invasion into adjacent structures
- The most powerful gradient in its class. SQ Gradient 45 mT/m @ 200 T/m/s.
- 48 Channels X 204 elements Tim 4G system for increased signal and speed.
- Advanced Applications Suite such as wholeSpine, Body Imaging, Advanced Neuro, Cardiac, Oncology, Prostate, Liver.
- Unparalleled magnet homogeneity producing superior Body and large parts images.
- Advanced sequences for motion correction, increased speed, metal artifact reduction, noise reduction, free breathing body imaging.
- High diagnostic confidence due to exceptional magnet homogeneity for excellent fat saturation
- Large 50 cm Field-of-View
- Siemens-unique TimCT technology with Continuous Table movement for CT-like scanning