MRI FISTULOGRAM

What is an MRI Fistulogram?

MRI Fistulogram Overview

An MRI Fistulogram is a specialized, advanced medical imaging test designed to provide highly detailed pictures of fistula tracts and their surrounding tissues. At Cadabams Diagnostics, we utilize this powerful diagnostic tool to help clinicians accurately identify, map, and assess the complexity of fistulas, particularly intricate ones like perianal fistulas. This non-invasive procedure employs Magnetic Resonance Imaging (MRI) technology, which uses strong magnetic fields and radio waves to generate cross-sectional images without the use of ionizing radiation. The clarity and detail offered by an MRI Fistulogram are crucial for effective diagnosis, precise surgical planning, and monitoring treatment outcomes, ensuring patients receive the most appropriate care.

Imaging Process

An MRI Fistulogram is a diagnostic imaging technique that uses the principles of Magnetic Resonance Imaging to visualize fistulas within the body. An MRI scanner contains a powerful magnet that creates a strong magnetic field. When you are inside the scanner, radio waves are sent and received by the machine, interacting with the protons in your body. A computer then processes these signals to create detailed, cross-sectional images—like slices—of the specific area being examined, such as the pelvis for a suspected anal fistula.

This advanced imaging allows for a meticulous look at the fistula's precise path, its relationship to adjacent anatomical structures (for instance, how an anal fistula interacts with the sphincter muscles), and the presence of any associated complications like abscesses (collections of pus) or inflammation. To further enhance the visibility of active inflammation and the intricate network of fistula tracts, a gadolinium-based contrast dye may be administered intravenously (into a vein) during the MRI Fistulogram. This contrast agent helps highlight areas of increased blood flow, which are characteristic of active inflammation, making the fistula tracts stand out more clearly on the images. Understanding gained from an MRI Fistulogram is paramount for effective treatment.

Types of MRI Fistulogram

Contrast and Sequences

The term "MRI Fistulogram" primarily refers to an MRI scan of the pelvis or another specific anatomical region, with imaging protocols (sequences) tailored to optimally visualize the suspected fistula tract and its surrounding structures. While the core principle remains the same, variations in technique can be employed:

• With or without intravenous gadolinium contrast: The use of contrast is very common for an MRI Fistulogram because it significantly enhances the delineation of active fistula tracts, inflammation, and associated abscesses. Non-contrast scans may be performed if there are contraindications to contrast administration.
• Specific MRI sequences: Radiologists utilize a combination of MRI sequences optimized for fistula imaging. These often include:
  • T2-weighted images: These are excellent for showing fluid, so they highlight the fistula tract itself and any fluid collections or edema (swelling). Fat-suppressed T2-weighted images are particularly useful for making fluid-filled tracts stand out against surrounding fatty tissues.
  • Post-contrast T1-weighted images: After gadolinium injection, T1-weighted images (often with fat suppression) clearly show areas of enhancement, indicating active inflammation within the fistula wall and surrounding tissues.
• Dynamic Contrast-Enhanced (DCE-MRI) sequences: In some cases, DCE-MRI may be used. This involves taking rapid images before, during, and after contrast injection to assess how quickly and intensely tissues enhance, which can help evaluate the activity of inflammation, particularly in conditions like Crohn's disease.
• MR Fistulography (less common): Occasionally, instead of or in addition to intravenous contrast, a dilute contrast agent (like saline or gadolinium mixed with saline) may be gently instilled directly into the external opening of the fistula tract before the MRI scan. This technique, known as MR fistulography, can sometimes help outline the tract directly but is less commonly performed than standard MRI Fistulogram with IV contrast.

Specific Parameters

The specific type and combination of sequences used for your MRI Fistulogram at Cadabams Diagnostics will be determined by our radiologists based on your clinical symptoms and the information your doctor is seeking.

Radiological Evaluation

During the interpretation of an MRI Fistulogram, the radiologist at Cadabams Diagnostics meticulously evaluates several key parameters to provide a comprehensive assessment. These include:

• Fistula Tract Anatomy:
  • Identification: Detecting the presence of primary fistula tract(s) and any secondary branches, extensions, or ramifications (e.g., horseshoe fistulas).
  • Course and Trajectory: Mapping the precise path of the tract(s). For anal fistulas, this involves classifying them according to their relationship with the anal sphincter muscles (e.g., intersphincteric, transsphincteric, suprasphincteric, extrasphincteric – often described using the Parks classification system).
  • Openings: Identifying the location of the internal opening (usually within the anal canal or rectum) and any external opening(s) on the skin.
• Relationship to Surrounding Structures:
  • Sphincter Muscle Involvement: Assessing whether the fistula tract involves or passes through the internal anal sphincter and/or the external anal sphincter. This is crucial for surgical planning to preserve continence.
  • Proximity to Other Organs: Determining the fistula's relationship to nearby structures like the levator ani muscles, rectum, vagina (in rectovaginal fistulas), bladder, or other pelvic organs depending on the fistula's location.
• Associated Findings:
  • Abscesses or Fluid Collections: Identifying the presence, size, and exact location of any associated abscesses or fluid collections, which often require drainage.
  • Evidence of Active Inflammation: Looking for signs like thickening of the fistula wall, increased signal on T2-weighted images (edema), and enhancement after gadolinium contrast administration, which indicates active inflammation.
  • Chronic Changes: Noting signs of chronic disease, such as fibrosis (scarring) in and around the fistula tract.
• Activity Assessment:
  • Degree of Contrast Enhancement: Evaluating the intensity and pattern of contrast enhancement within the fistula tract walls and surrounding tissues. Greater enhancement typically signifies more active inflammation. This is particularly important for conditions like Crohn's disease where assessing disease activity guides medical management.

Diagnostic Purposes

There are several compelling reasons why your doctor might recommend an MRI Fistulogram:

• Accurate Diagnosis and Mapping: To precisely diagnose the presence of a fistula and to map its complete anatomy, including its course, relationship to surrounding structures, and any associated complications. This is essential for MRI for anal fistula detection and for understanding other types of fistulas.
• Surgical Planning: To provide a detailed "roadmap" for surgeons. Knowing the exact path of the fistula, the location of its openings, and its relationship to structures like the anal sphincter muscles allows surgeons to choose the most appropriate surgical procedure. This helps minimize the risk of fistula recurrence and potential complications like incontinence.
• Assessing Fistulizing Crohn's Disease: For patients with Crohn's disease, an MRI Fistulogram is crucial for evaluating the extent and activity of fistulizing disease. This information helps guide medical management, including decisions about biologic therapies.
• Evaluating Recurrent or Unresponsive Fistulas: If a fistula has recurred after previous treatment or has not responded to initial therapies, an MRI Fistulogram can help identify reasons for treatment failure, such as missed tracts or undrained abscesses.
• Differential Diagnosis: To differentiate a fistula from other conditions that may cause similar symptoms in the perianal or pelvic region, such as a pilonidal sinus, hidradenitis suppurativa (if the location is atypical), or other inflammatory processes.
• Monitoring Treatment Response: An MRI Fistulogram can be used to monitor the response to medical or surgical treatment, assessing for healing, a reduction in inflammation, or the closure of fistula tracts.

When and Who Needs to Take an MRI Fistulogram?

Indications for the Test

An MRI Fistulogram is typically recommended when a fistula is suspected or has been confirmed, and detailed anatomical information is required for treatment planning. Common indications for this specialized scan include:

• Suspected or confirmed fistulas: This is particularly common for perianal fistulas (abnormal tracts near the anus), but also includes rectovaginal fistulas (between the rectum and vagina), enterocutaneous fistulas (between the bowel and skin), and other complex fistula types.
• Symptoms prompting the test: Patients experiencing symptoms such as chronic pain, persistent discharge (pus, stool, or blood) from an opening near the anus or elsewhere on the body, recurrent abscesses in the perianal or pelvic region, or unexplained inflammation may be candidates for an MRI Fistulogram.
• Specific patient groups:
  • Individuals with Crohn's disease often develop fistulas, and an MRI Fistulogram is a key tool in managing this complication. MRI for anal fistula detection is especially critical in this population.
  • Patients with a history of recurrent anal abscesses.
  • Those who have experienced complications from previous fistula surgery.
  • Cases where other imaging methods (like ultrasound or CT scan) have been inconclusive or do not provide sufficient detail.
• Pre-operative planning and post-operative assessment: The MRI Fistulogram is invaluable for pre-operative planning, providing surgeons with a detailed roadmap to guide their surgical approach, which can minimize the risk of recurrence and complications like sphincter damage. It is also used for post-operative assessment to evaluate healing or to investigate suspected recurrence of the fistula.

Clinical Indications

The report will describe:

• The location, size, type, and complexity of any fistula tracts detected.
• The relationship of the fistula(s) to surrounding anatomical structures, particularly the anal sphincter muscles if it's a perianal fistula.
• The presence and characteristics of any associated abscesses or fluid collections.
• Signs of active inflammation (e.g., based on edema or contrast enhancement).
• Any other relevant findings in the scanned area.

Benefits of MRI Fistulogram

Advantages of MRI Fistulograms

Opting for an MRI Fistulogram at Cadabams Diagnostics offers significant benefits in the evaluation of fistulous tracts:

• Superior Soft Tissue Contrast: MRI provides unparalleled detail of soft tissues compared to other imaging modalities like CT scans or traditional X-ray fistulography. This allows for excellent visualization of the fistula tract, associated inflammation, and its relationship with muscles and other pelvic structures.
• Non-Invasive Imaging: The procedure is non-invasive. Unlike X-rays or CT scans, an MRI Fistulogram does not use ionizing radiation, making it a safer option, especially if multiple scans are needed over time.
• Improved Surgical Planning and Outcomes: By providing a clear and detailed anatomical roadmap, the MRI Fistulogram helps surgeons plan their procedures more effectively. This can lead to a reduction in the number of surgical operations needed, lower rates of fistula recurrence, and improved overall treatment outcomes.
• Detection of Hidden Complications: The scan can identify occult (hidden) extensions of the fistula, secondary tracts, or associated abscesses that might not be apparent during a clinical examination or with other imaging techniques. Addressing these hidden elements is crucial for successful treatment.
• Reduced Risk of Complications: Accurate pre-operative assessment helps surgeons avoid inadvertent damage to important structures like the anal sphincter muscles, thereby reducing the risk of complications such as fecal incontinence.

Diagnosed Conditions with Fistulogram MRI Scan

Conditions Identified

The MRI Fistulogram is a key diagnostic tool for a range of conditions characterized by abnormal tracts. The most common illnesses and conditions diagnosed or assessed include:

• Perianal fistulas: This is the most frequent application, where the MRI Fistulogram helps classify the fistula (e.g., intersphincteric, transsphincteric) and identify associated abscesses. MRI for anal fistula detection is highly effective.
• Rectovaginal fistulas: Abnormal connections between the rectum and vagina.
• Enterocutaneous fistulas: Abnormal tracts between the bowel (intestine) and the skin surface.
• Fistulas related to Inflammatory Bowel Disease (IBD): Particularly Crohn's disease, which has a high incidence of complex fistulas. The MRI Fistulogram helps assess the extent and activity of these fistulas.
• Anal abscesses: Collections of pus near the anus, which are often the precursor to or associated with an anal fistula. The MRI can show the abscess and any connecting fistula tract.
• Complications of other conditions: Fistulas can sometimes arise as complications of diverticulitis, surgery, trauma, or certain infections. An MRI Fistulogram can aid in their evaluation.
• Hidradenitis suppurativa with deep tracts: In some severe cases, this skin condition can form tract-like structures that might mimic fistulas, and MRI can help in differentiation or assessing depth.
• Pilonidal disease with complex tracts: While typically distinct, complex or recurrent pilonidal sinuses can sometimes warrant MRI to assess their extent.

Pre-Scan Preparation

Proper preparation is important for a successful MRI Fistulogram. Here’s how to prepare for MRI fistulogram and what you need to know:

Specific Instructions Before the Test

• Diet: In most cases, no specific dietary restrictions are necessary for an MRI Fistulogram. However, sometimes, especially if intravenous contrast dye is planned, you may be asked to fast for 4-6 hours before your appointment. Our staff at Cadabams Diagnostics will provide you with specific instructions when you schedule your scan.
• Medication: Continue to take your usual medications unless specifically advised otherwise by your doctor or our imaging staff. It's important to inform the staff about all medications you are currently taking, including over-the-counter drugs and supplements.
• Clothing: Wear loose, comfortable clothing that does not have any metal components (such as zippers, snaps, metal buttons, or underwires in bras). You will most likely be asked to change into a hospital gown before the scan to ensure no metal objects interfere with the MRI machine.
• Hydration: Maintain normal hydration by drinking water as you usually would, unless instructed otherwise.
• Arrival Time: Please arrive at Cadabams Diagnostics 15-30 minutes before your scheduled appointment time. This allows ample time for check-in, completing any necessary paperwork, and pre-scan preparations.

What to Inform the Staff About

It is crucial to inform our staff at Cadabams Diagnostics about certain medical conditions or circumstances before your MRI Fistulogram:

• Any known allergies, particularly to MRI contrast dye (gadolinium), iodine, or any other medications.
• A history of kidney disease, kidney failure, diabetes, or if you are on dialysis. This is especially important if contrast dye is planned, as your kidney function may need to be assessed.
• If you are pregnant or suspect you might be pregnant. MRI is generally avoided during the first trimester unless absolutely necessary.
• Any metal implants in your body. This includes but is not limited to:
  • Cardiac pacemaker or implantable defibrillator
  • Cochlear (ear) implant
  • Brain aneurysm clips
  • Artificial heart valves
  • Metallic joint replacements or prostheses
  • Surgical staples, screws, plates, or wires
  • Stents or filters
  • Insulin pumps or neurostimulators
  • Any shrapnel, bullets, or other metallic fragments.
• If you suffer from claustrophobia (fear of enclosed spaces).
• Any recent illness, surgery, or other medical conditions.

Pre-requisites

Required Conditions

Before undergoing an MRI Fistulogram at Cadabams Diagnostics, certain pre-requisites are typically needed:

• Doctor's Referral: A referral from your physician with a clear clinical question or indication for the scan is usually required. This helps ensure the MRI Fistulogram is appropriate for your condition and that protocol is tailored to answer specific diagnostic questions.
• Kidney Function Test (if contrast is used): If intravenous gadolinium contrast dye is planned, a recent blood test to check your kidney function (e.g., serum creatinine levels and estimated Glomerular Filtration Rate - eGFR) may be necessary, especially if you have a history of kidney disease, diabetes, or are over a certain age. Our team will advise if this is needed.
• MRI Safety Screening Questionnaire: You will be asked to complete a detailed MRI safety screening questionnaire. This form helps identify any metallic implants or conditions that might pose a risk during the MRI scan. It is vital to answer these questions accurately and thoroughly.
• Empty Bladder: Emptying your bladder just before the scan can improve image quality in the pelvic region and enhance your comfort during the procedure.

Best Time to Take the MRI Fistulogram

Scheduling Considerations

There is generally no specific physiological "best time of day" or "best time in a cycle" to undergo an MRI Fistulogram. The test can be performed at any time, and scheduling is usually based on:

• Clinical urgency: How quickly your doctor needs the information for diagnosis or treatment planning.
• Facility availability: The schedule of the MRI unit at Cadabams Diagnostics.
• Patient convenience: A time that works well for you.

Unless your doctor has specific instructions related to coordinating the MRI Fistulogram with other treatments (e.g., before starting a new medication or a surgical procedure), the timing is flexible.

Eligibility

Suitability for the Test

Most individuals can safely undergo an MRI Fistulogram. However, there are certain situations where an MRI may not be suitable:

Absolute Contraindications

• Patients with incompatible cardiac pacemakers or implantable cardioverter-defibrillators (ICDs). Some newer models are MRI-conditional, but this must be verified.
• Patients with certain older types of cerebral aneurysm clips (clips used to repair brain aneurysms).
• Individuals with metallic foreign bodies in or near the eyes (e.g., metal splinters).
• Some types of cochlear (ear) implants.

Relative Contraindications/Precautions

• Pregnancy: MRI is generally avoided during the first trimester of pregnancy unless the benefits clearly outweigh the potential risks. If you are pregnant or suspect you might be, please inform our staff at Cadabams Diagnostics and your referring doctor.
• Severe Claustrophobia: Patients with a significant fear of enclosed spaces may find the MRI scanner challenging. Options such as open MRI (if suitable for fistula imaging, though often closed bore is preferred for quality), sedation, or discussing coping strategies with our staff may be considered.
• Severe Kidney Impairment: If gadolinium contrast dye is deemed essential for the diagnostic quality of the MRI Fistulogram, patients with severe kidney disease may be at higher risk. The necessity of contrast will be carefully weighed against the risks, and alternative imaging or a non-contrast MRI might be considered.
• Inability to Lie Still: Patients who are unable to lie still for the required duration of the scan (typically 30-60 minutes) due to pain, involuntary movements, or other conditions may not be suitable candidates, as movement artifacts can degrade image quality.

Procedure for Taking an MRI Fistulogram

MRI Fistulogram Procedure Steps

Understanding the MRI fistulogram procedure steps can help you feel more prepared and at ease on the day of your scan at Cadabams Diagnostics. Here’s what typically happens:

Arrival and Preparation

• You'll check in at the reception desk.
• You may need to complete or review paperwork, including the MRI safety questionnaire.
• You will be asked to change into a hospital gown to ensure there are no metal items on your clothing.
• You must remove all metallic objects, including jewelry (rings, necklaces, earrings, watches), hairpins, eyeglasses, dentures, hearing aids, and any removable dental work. Lockers are usually provided for your valuables.

IV Line Insertion

• If your MRI Fistulogram requires gadolinium contrast dye, a technologist or nurse will insert a small intravenous (IV) catheter, usually into a vein in your arm or hand. This is similar to having a blood test.

Positioning

• You will be assisted onto a padded, movable examination table.
• The technologist will position you correctly for the scan, which is typically lying on your back.
• A special device called a "surface coil" may be placed over or around your pelvic and anal region. This coil acts as an antenna to help receive the MRI signals and improve the quality of the images of the fistula.

Entering the Scanner

• Once you are comfortably positioned, the table will slide slowly into the center of the large, tunnel-shaped (or sometimes open) MRI machine. Only the part of your body being scanned needs to be in the center of the magnet. For a pelvic MRI Fistulogram, your head may be near or outside the opening of the scanner.

During the Scan

• The MRI technologist will operate the scanner from an adjacent control room. They will be able to see you through a window, hear you, and speak with you via an intercom system throughout the scan. You will be given a call button to press if you need assistance.
• The MRI machine produces loud thumping, tapping, buzzing, or knocking noises as it acquires images. This is normal. You will be provided with earplugs or headphones to reduce the noise. Sometimes, you can listen to music through the headphones.
• It is extremely important to remain very still during each imaging sequence. Movement can blur the images and may require sequences to be repeated, prolonging the scan.
• You may be asked to hold your breath for short periods (e.g., 10-25 seconds) during certain parts of the scan to minimize motion from breathing. The technologist will guide you through this.
• If contrast dye is being used intravenously, it will be injected through the IV line partway through the scan. You might feel a cool sensation spreading up your arm, a temporary metallic taste in your mouth, or a feeling of warmth. These sensations are usually mild and pass quickly.

Duration

• The entire MRI Fistulogram procedure steps, from positioning to the last image, typically take between 30 to 60 minutes. The exact duration depends on the complexity of your case and the number of different imaging sequences required to fully evaluate the fistula.

Once the scan is complete, the table will slide out of the scanner, and the technologist will assist you. If an IV line was inserted, it will be removed. You can then change back into your clothes.

Caution Before Taking the Test

Safety Considerations

Before your MRI Fistulogram at Cadabams Diagnostics, it is absolutely critical to reiterate the following information to the MRI technologist or radiologist:

• Possibility of Pregnancy: If there is any chance you might be pregnant, inform the staff immediately. MRI scans are generally avoided in the first trimester unless medically urgent.
• Presence of ANY Metallic Implants, Devices, or Fragments: This is the most crucial safety aspect. Inform them of any metal in your body, no matter how small or how long ago it was implanted. Examples include:
  • Pacemakers or defibrillators
  • Aneurysm clips
  • Stents (coronary, carotid, etc.)
  • Artificial joints (hip, knee)
  • Surgical pins, screws, plates, or staples
  • Cochlear implants
  • Neurostimulators (for pain, bladder control, etc.)
  • Insulin pumps
  • Shrapnel, bullets, or metal fragments from injuries (especially near the eyes)
  • Permanent makeup or tattoos (some older inks contain metallic particles, though this is rare).
• Known Allergies: Especially any previous allergic reactions to MRI contrast agents (gadolinium), iodine, or other medications.
• History of Kidney Problems or Dialysis: This is vital if contrast dye is planned. Impaired kidney function can affect the body's ability to clear the contrast agent.
• Severe Claustrophobia: If you have a significant fear of enclosed spaces, discuss this beforehand. Options for managing anxiety or sedation can be explored with your referring doctor and our team at Cadabams Diagnostics.
• Details of Previous Surgeries: Inform the staff about any previous surgeries in the area being scanned (e.g., pelvic or perianal surgery), as this can be relevant to interpreting the images.