The structure of the prostate on MRI

MRI of the pelvis in the diagnosis of prostate diseases

MRI of the pelvis in the diagnosis of prostate diseases

In the diagnosis of prostate diseases, the role of MRI is especially great. In economically developed countries, prostate cancer occupies one of the first places in the structure of oncological diseases, so the interest in methods for its early detection is especially great.

MRI is most often used for the detection and differential diagnosis of prostate cancer, as well as for the diagnosis of other diseases of the prostate and seminal vesicles.

Let's consider some diseases of the prostate gland and seminal vesicles detected by MRI examination of the pelvis:

1. Benign prostatic hyperplasia

This is an adenomatous enlargement of the transition zone of the prostate. Typically occurs in men over 50 years of age, most often progresses over time. Clinically manifested by dysuric phenomena, weakening of the urine stream, chronic Urinary retention.

Rarely causes prostate cancer.

A) T2-tra b) T2-sag The zonal anatomy of the prostate is well visualized, pronounced hyperplasia of the transition zone of an inhomogeneous structure, compression of the peripheral zone against this background. The transition zone protrudes into the lumen of the bladder (b).

2. Prostate cancer.

Adenocarcinoma is the most common malignant tumor of the prostate, usually occurring in the peripheral zone. In men, it is the most common malignant tumor. Clinically, an asymptomatic course is characteristic for a long time; palpation, as a rule, only large, peripherally located tumors are determined. Urinary retention, infravesical obstruction - late complications of adenocarcinoma. Deterioration of the general condition in patients occurs with metastatic prostate cancer.

The frequency of occurrence increases with age. Screening, including determination of the level of PSA and digital rectal examination of the prostate, should begin at age 50.

A) T2-axial image b) T2-coronal image.

Male, 62 years old. Verified prostate cancer. In the posterior-lateral sections of the peripheral zone of the left lobe of the gland (on the border of the central and apical parts of the prostate), an area of pathologically reduced MR signal is visualized. The intact capsule of the gland is preserved (stage T2a).

T2-VI, axial plane. Ca (cancer) is a small focus of a pathologically reduced MR signal.

The area of the pathologically reduced MR signal is determined in the peripheral zone of the left lobe of the prostate (the central part of the gland). In this case, a violation of the integrity of the capsule of the prostate gland (T3a stage) is visualized.

A) T2-cor b) T2-tra c) T1FS din+C

A large tumor of the right lobe of the prostate gland with invasion of its capsule, spreading to the paraprostatic tissue (arrows) is determined. With intravenous dynamic contrast (c), a pronounced, diffusely inhomogeneous enhancement of tumor tissue is determined in the arterial phase.

A) T2-axial image b) T2-coronal image

The tumor of the left lobe of the prostate is determined with signs of spread to the base of the left seminal vesicle (arrows, b).

3. Acute prostatitis.

Acute prostatitis is an acute inflammatory process in the prostate gland, characterized by signs of general intoxication, pain in the perineum and inguinal region, as well as painful sensations when emptying the bladder and frequent urge to urinate (especially at night). The pain syndrome leads to difficulty urinating, sometimes to acute urinary retention.

In some cases, whitish or colorless purulent discharge from the urethra is possible.

Male, 45 years old. Acute prostatitis. On the presented tomograms in T2-WI, the axial plane (a) and T2 with fat suppression in the coronal plane, an increase in the volume of the peripheral zone, its swelling is determined.

4. Prostate abscess.

The reason for the formation of a prostate abscess is pathogenic bacteria that caused the development of prostatitis, and in the case of a hematogenous abscess, bacteria that contributed to the development of the main focus of infection in the body.

The following forms of prostate abscess are distinguished:

• Primary - in the presence of an infectious process outside the genitourinary system;
• Secondary - as a complication of prostatitis.

Prostate abscess is characterized by all the symptoms of prostatitis, but to a greater extent. The general condition is severe, the temperature is high with chills, tachycardia, profuse sweating. Sharp, pulsating, unilateral (because an abscess often affects one side of the organ in isolation), pain radiating to the rectum is characteristic.Pain syndrome leads to difficulty in defecation and urination, including acute urinary retention. In the event of an abscess rupture, cloudy urine is noted, or the presence of pus in the feces.

A) T2-tra b) T1-tra+C c)DW

On the T2-axial image (a), an irregularly rounded focus of increased MR signal intensity in the central zone of the left lobe of the prostate gland is determined. With intravenous contrasting (b), there is a peripheral enhancement of this focus (capsule), with non-contrasting central sections. On the diffusion-weighted image, signs of diffusion limitation from a given cavity formation (abscess) are determined.

5. Agenesis of the seminal vesicle.

35. Male, 31 years old with infertility. The T2-axial image shows the absence of the left seminal vesicle in the presence of the left vas deferens (arrows).

6. Autosomal dominant polycystic kidney and seminal vesicles.

The presence of cysts in the seminal vesicles in autosomal dominant polycystic kidney disease is of great clinical significance. With ultrasound, this pathology can be erroneously interpreted as prostate cysts.

The clinical picture of polycystic disease may include hemospermia.

On the presented T2-WI with fat suppression, bilateral cysts of the seminal vesicles (a, axial plane) and enlargement of the kidneys due to multiple cysts (b, frontal plane) are determined.

37. a) T1-tra FS b) T2-tra c) T1-tra+contrast

Man, 31 years old. Hematuria. A cavitary inclusion of an irregularly oval shape is determined in the projection of the left seminal vesicle, which has signal characteristics different from liquid (hyperintense MR signal in T1-WI, a - a sign of hemorrhage). With intravenous contrast (c), there is no peripheral enhancement, which indicates the absence of infection of the cyst.

7. Festering cyst of the left seminal vesicle.

38 a) Т1-tra+С b) Т1-cor+С

Man, 78 years old. In the projection of the left seminal vesicle, a cystic inclusion is determined with non-bumpy contours and signs of peripheral contrast enhancement of the capsule (a festering cyst-abscess).

8. Mullerian duct cyst.

Müllerian duct cyst is more common in boys with hypospadias and in intersex people. Sizes vary considerably. Clinically, they often do not manifest themselves in any way, but in some cases there may be discomfort in the perineum, dysuria, hematuria, urinary retention, urinary tract infections, epididymitis, oligospermia.

38. Male, 72 years old with prostate cancer. Large cyst of the Mullerian duct. A fluid inclusion is seen between the rectum and the prostate in the midline. For such a cyst, localization along the midline is typical, which makes it possible to differentiate it from a seminal vesicle cyst.

9. Vesiculitis.

Vesiculitis is an inflammation of the seminal vesicles. Clinically characteristic is the appearance of pain above the pubis and in the perineum, which radiate to the lower back, groin or sacrum. Pain is aggravated by defecation and urge to urinate. During defecation, there is also a discharge of mucous contents from the urethra, sometimes with streaks of blood, this is the secret of vesicles. In addition, with vesiculitis, ejaculation becomes painful and traces of blood appear in the semen. There is an erection disorder. The general condition also suffers: weakness, headache, increased fatigue and temperature are characteristic. The accompanying symptoms of prostatitis are often exacerbated.

40 a) T2-tra b) T1-tra + contrast

Man, 34 years old with hematospermia. Pre-contrast T2-WI (a) and post-contrast T1-WI images (b) in the axial plane demonstrate diffuse thickening of the walls of the seminal vesicles, heterogeneity of their internal structure.

Detailed overview of prostate diagnostics using magnetic resonance

The prostate gland (PG) refers to the accessory glands of the male reproductive system, it is called the male uterus. The most dangerous of them is prostate cancer.

The methods of diagnosing the disease are varied: urological examination, ultrasound of the pelvic organs, blood test for tumor markers, magnetic resonance imaging. The most detailed information about the structure of the prostate gland and nearby organs is obtained with MRI of the prostate, using this method it is possible to detect tumors up to 5 mm in diameter, enlarged lymph nodes and metastases.

Prostate functions

The prostate has a muscular-glandular structure, a lobular structure, located around the upper part of the urethra, covers it eccentrically. It is closely adjacent to the bottom of the bladder and borders on the wall of the rectum. Participates in the control of urination in men, its muscular layer is the third involuntary sphincter.

The prostate glands produce a secret that dilutes the ejaculate. This biological fluid contains substances necessary for the life of spermatozoa: vitamins, enzymes, immunoglobulins, zinc, citric acid.

The work of the pancreas depends on the production of testosterone. The male gland affects the process of ejaculation, performs a protective function - it prevents the reproduction and spread of pathogenic microbes in the urinary tract. Diseases of this organ lead to a decrease or complete loss of the listed functions.

Indications for referral for examination

With the help of MRI of the prostate gland, inflammatory, proliferative, and oncological diseases of the prostate are diagnosed. They are characterized by the presence of complaints:

• Delay before starting urination.
• Thinning and reduced pressure of the urine stream.
• Intermittent, prolonged, difficult, frequent, painful urination.
• Feeling of incomplete emptying of the bladder.
• Pain and a feeling of heaviness in the suprapubic region, perineum, sacrum, glans penis.
• Night trips to the toilet.
• Erectile dysfunction.

Such complaints are experienced by men with prostatitis, adenoma, pancreatic cancer. Based on the results of magnetic resonance imaging, a reliable diagnosis is made at the earliest stages of the disease. Each of them has its own special features.

Scanning allows you to determine the state of the prostate gland: the structure of the organ, size, position, to distinguish benign formation from cancer, to detect changes that are not yet visible in the level of biochemical processes in the prostate.

Preparation for tomography

For a good diagnosis of the pelvic organs on magnetic resonance imaging, it is necessary to prepare the intestines on the eve of the study - in the evening, clean them with an enema or a special Normokol gel. Within two days before the MRI, it is recommended to exclude from the menu products that cause the formation of gases. If contrasting is expected - do not eat for eight hours before the procedure, conduct an allergy test with a contrast agent.

Scanning with a full bladder improves the quality of the image, whether it needs to be filled - find out when pre-scheduling a tomography. It all depends on the suspected prostate disease and the recommended examination technique. Proper preparation for MRI of the prostate is the key to reliable diagnosis.

Possible contraindications and limitations

There is a category of patients for whom magnetic resonance imaging of the prostate gland is contraindicated, its conduction can harm the patient or equipment. The decision on the admissibility of the study is made by the attending physician and a specialist in radiation diagnostics.

Absolute contraindications

Research is not possible for holders:

• artificial pacemaker;
• endoprostheses with ferromagnetic particles;
• metal clips on the vessels of the brain;
• devices for osteosynthesis, hearing restoration;
• insulin pumps and drug dispensers;
• metal objects and fragments in the body.

Relative contraindications

Research is possible if the benefit exceeds the risk under the following conditions:

• severe cardiovascular failure;
• the presence of metal brackets in the body, except for the brain, artificial hip joints, modern models of cava filters;
• claustrophobia;
• Severe renal impairment (for contrast-enhanced MRI).

The study is not contraindicated for people with the presence of suture material and small brackets, dentures, stents, artificial heart valves that do not contain ferroalloys.

Based on the data on the material of the metal object and its behavior in the electromagnetic field of the tomograph, radiation diagnostics doctors assess the risk of displacement, heating and disruption of its operation, in each case the decision is made individually.

Options for performing diagnostics and methods for their implementation

Of all the methods of radiation diagnostics, magnetic resonance imaging has the highest resolution in the study of soft tissues, an unlimited number of slice planes. The natural contrast from moving blood and fatty tissue is its important advantage. There are several types of MRI of the prostate, performed in the classical and additional versions:

• Classic technique.
• MRI with contrast.
• Endorectal MRI
• MR spectroscopy.
• MRI with dynamic contrast enhancement.
• Multiparametric.

MRI not only gives an idea of the topography of the prostate gland, the method allows you to visualize changes in its structure and surrounding tissues before the clinical manifestations of the disease.

Classic technique

For MRI of the prostate, modern systems with a magnetic field strength of 2-5 T of closed and open types and models of the older generation of 0.5-1.5 T are used.Scanning is performed with a full bladder using a pelvic coil.

The standard is the use of T1 and T2 weighted sequences, the main planes of slice orientation are transverse and frontal, the optimal thickness is 5-10mm. The quality of the images depends on the difference in contrast between the tissues of the prostate and the surrounding fatty tissue. Used to detect early stages of prostate cancer and clarify the prevalence of the process.

With contrast

Many factors affect the contrast of the image - the density of the tissue being examined, the strength of the magnetic field. MRI of the prostate with contrast significantly increases the intensity of the image of the parenchyma of the organ, which facilitates the accurate detection of tumor formations and metastases, they are stained more intensely against the background of healthy tissue.

As a contrast, paramagnetic substances are used - gadolinium chelates, which are administered intravenously, the rate of administration and the dose are calculated individually. Ten minutes after the injection, a scan is performed with a slice depth of 5-10 millimeters.

With endorectal coil

In the study of the male pelvic organs, the image quality improves when using endorectal coils - they play the role of receivers and transmitters of signals, they are located in the patient's rectum. This technique makes it possible to see the anatomy of the prostate by zones, the state of its capsule, the structure of the urethra and seminal ducts, and is indispensable in the diagnosis of prostate cancer. It is carried out on an empty stomach, after a preliminary enema 12 hours before the scan.

Based on the data of endorectal MRI of the prostate, a conclusion is made about the presence of a malignant process, its boundaries of distribution, the state of neurovascular nodules in the fatty tissue surrounding the prostate gland, and the structure and size of the lymph nodes.

With this information, oncologists choose the optimal treatment protocol. Endorectal coil MRI is helpful in staging prostate cancer, but it cannot be done in patients with suspected recurrence after prostate removal.

MR spectroscopy

With the help of magnetic resonance spectroscopy, information is obtained on the concentrations of metabolites contained. This is a tomography of the biochemical processes occurring in the body. Allows you to detect small lesions of the pancreas that are not yet visualized.

Hydrogen and phosphorus, without using a biopsy, determine the amount of metabolites in tissues. The technique is of particular importance in the diagnosis of prostate cancer in the early stages of the disease. It is carried out using an endorectal coil on devices with a power of 3T or more, which have special programs, and allows targeted biopsy of neoplasms.

Multiparametric Survey

Multiparametric MRI of the prostate is a new method for examining the prostate gland to assess early involvement of malignant processes, especially in the anterior regions. The study is carried out on devices with a power of 1.5-3 Tl in three projections with a slice thickness of 2-5 mm, a coil for the body is used, contrasting with Gadobutrol (Gadovist). Scan duration 35-45 minutes.

Preliminary preparation, as with the classical method, plus a light carbohydrate breakfast on the day of the study, a minimum of liquid. 15-20 minutes before the procedure, it is recommended to drink 10 mg of Buscopan (if there is no constipation) or 40 mg of No-shpa (if the patient suffers from constipation).

Mp-MRI of the prostate combines several techniques into one, consists of obtaining:

• T2-VI, T1-VI.
• Diffusion-weighted images - detect changes in blood flow in pathological areas at the microcirculatory level.
• Dynamic Contrast-enhanced T1-WI Series is a dynamic contrast-enhanced magnetic resonance imaging that exploits the property of tumors to accumulate and release contrast faster than healthy cells.

With the help of Mp-MRI, intraprostatic cancer growth is diagnosed, its exact location, structure, size. The advantage of a multiparametric examination is that it provides the most complete and accurate information about the condition of the prostate using only a surface coil, without causing pain to the patient.

The technique is used to examine both primary oncological patients and those who have undergone various treatment protocols; in 80% of cases, it allows you to determine the stage of the process. The sensitivity of the multiparametric examination is 72%, the specificity is higher than that of a biopsy - 91%, with a saturation biopsy - 40%.

Transcript of results

A variety of MRI techniques for examining the prostate can be used to diagnose inflammatory urological diseases and uro-oncology:

• Acute and chronic prostatitis.
• Adenoma.
• Malignant neoplasms.
• Abscesses in progress.
• Prostate cancer staging
• Identification of affected pelvic lymph nodes, metastases.

Endorectal MRI and dynamic contrast enhancement are more commonly used for research in urology (MRI of the kidneys). These diagnostic methods are also used in uro-oncology, complemented by MR spectroscopy and multiparametric MRI.

MRI of the prostate gland is not associated with radiation exposure, is used repeatedly without restrictions, allows you to get several projections of a clear image, makes it possible to distinguish a benign process from cancer, determines the stage of diseases and the spread of metastases, is one of the most informative methods for examining soft tissues and parenchymal organs.

PROSTATE ANATOMY ABOUT MRI IMAGE

M RT combines the advantages of ultrasound and CT: the method is highly sensitive for detecting structural changes in the prostate gland and provides complete information about the state of surrounding tissues and organs. When using devices with a high magnetic field strength, it is possible to visualize various anatomical structures: the fibromuscular zone, the central, transitional and peripheral zones. Seminal vesicles, prostatic urethra, seminal tubercle and gland capsule are well differentiated. The most clearly zonal structure of the prostate gland is displayed on T2-WI. The peripheral zone has a high signal intensity, the transitional and fibromuscular zones have a low one, the central zone is represented by signals of medium intensity ( 16.6-16.8).

16.6. MRI of the prostate, T2-WI.

A - coronal plane, b - sagittal plane. Here and on 16.7, 16.8:

1 - gland capsule; 2 - urethra; 3 - anterior fibromuscular zones; 4 - seminal vesicles; 5 - peripheral zone.

16.7. MRI of the normal prostate. T2-VI. Axial plane.

16.8. MRI of the normal prostate. T2-VI.

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