Related Terms: interstitial magnetic resonance lymphangiography;
The Magnetic Resonance Imaging (MRI) is a method for viewing the human body. It allows physicians to see layered images of your internal organs in great detail from any angle. These images can help your doctor diagnose and treat a variety of conditions and diseases.
Felix Bloch and Edward Purcell, both of whom were awarded the Nobel Prize in 1952, discovered the magnetic resonance phenomenon independently in 1946. In the period between 1950 and 1970, NMR was developed and used for chemical and physical molecular analysis.
In 1971 Raymond Damadian showed that the nuclear magnetic relaxation times of tissues and tumors differed, thus motivating scientists to consider magnetic resonance for the detection of disease. In 1973 the x-ray-based computerized tomography (CT) was introduced by Hounsfield. This date is important to the MRI timeline because it showed hospitals were willing to spend large amounts of money for medical imaging hardware. Magnetic resonance imaging was first demonstrated on small test tube samples that same year by Paul Lauterbur. He used a back projection technique similar to that used in CT. In 1975 Richard Ernst proposed magnetic resonance imaging using phase and frequency encoding, and the Fourier Transform. This technique is the basis of current MRI techniques. A few years later, in 1977, Raymond Damadian demonstrated MRI called field-focusing nuclear magnetic resonance. In this same year, Peter Mansfield developed the echo-planar imaging (EPI) technique. This technique will be developed in later years to produce images at video rates (30 ms / image).
Edelstein and coworkers demonstrated imaging of the body using Ernst's technique in 1980. A single image could be acquired in approximately five minutes by this technique. By 1986, the imaging time was reduced to about five seconds, without sacrificing too much image quality. The same year people were developing the NMR microscope, which allowed approximately 10 m resolution on approximately one cm samples. In 1987 echo-planar imaging was used to perform real-time movie imaging of a single cardiac cycle. In this same year Charles Dumoulin was perfecting magnetic resonance angiography (MRA), which allowed imaging of flowing blood without the use of contrast agents. In 1991, Richard Ernst was rewarded for his achievements in pulsed Fourier Transform NMR and MRI with the Nobel Prize in Chemistry. In 1992 functional MRI (MRI) was developed. This technique allows the mapping of the function of the various regions of the human brain. Five years earlier many clinicians thought echo-planar imaging's primary applications was to be in real-time cardiac imaging. The development of MRI opened up a new application for EPI in mapping the regions of the brain responsible for thought and motor control. In 1994, researchers at the State University of New York at Stony Brook and Princeton University demonstrated the imaging of hyperpolarized 129Xe gas for respiration studies.
In 2003, Paul C. Lauterbur of the University of Illinois and Sir Peter Mansfield of the University of Nottingham were awarded the Nobel Prize in Medicine for their discoveries concerning magnetic resonance imaging. MRI is clearly a young, but growing science. (1)
Here are some of the conditions that an MRI can aid in diagnosing:
Although MRIs are offered through our Radiology department, an MRI uses strong magnetic fields and not radiation, so the test is completely safe and painless. The MRI complements other types of imaging procedures, such as X-rays and computed axial tomography (CAT) scanners.
Magnetic resonance imaging; Nuclear magnetic resonance (NMR) imaging
Magnetic resonance imaging (MRI) is a non-invasive way to take pictures of the body.
Unlike x-rays and computed tomographic (CT) scans, which use radiation, MRI uses powerful magnets and radio waves. The MRI scanner contains the magnet. The magnetic field produced by an MRI is about 10 thousand times greater than the earth's.
The magnetic field forces hydrogen atoms in the body to line up in a certain way (similar to how the needle on a compass moves when you hold it near a magnet). When radio waves are sent toward the lined-up hydrogen atoms, they bounce back, and a computer records the signal. Different types of tissues send back different signals. For example, healthy tissue sends back a slightly different signal than cancerous tissue.
Single MRI images are called slices. The images can be stored on a computer or printed on film. MRI can easily be performed through clothing. However, because the magnet is very, very strong, certain types of metal can cause significant errors, called artifacts, in the images.
You may be asked to war a hospital gown or clothing without metal fasteners (such as sweatpants and a t-shirt). You will be asked to lie on a narrow table, which slides into the middle of the MRI machine. If you have a fear of confined spaces (claustrophobia), tell your doctor before the exam. You may be prescribed a mild sedative, or your doctor may recommend an “open” MRI, in which the machine is not as close to the body.
Small devices, called coils, may be placed around the head, arm, or leg, or other areas to be studied. These devices help send and receive the radio waves, and improve the quality of the images.
Certain exams require that a special dye (contrast) be given before the test. The dye is usually given through an intravenous line (IV) in your hand or forearm. The contrast helps the radiologist see certain areas more clearly. During the MRI, the person who operates the machine will watch you from a room next door. Several sets of images are usually need, each taking from 2 to 15 minutes. Depending on the areas being studied and type of equipment, the exam may take 1 hour or longer.
An MRI can be performed immediately after other imaging studies. Depending on the area of interest, the patient may be asked to fast for 4 - 6 hours prior to the scan. Other preparations are usually not needed.
The strong magnetic fields created during an MRI can interfere with certain implants, particularly pacemakers.
Persons with cardiac pacemakers can not receive an MRI and should not enter an MRI area.
If you have any of the following metallic objects in your body, you should not get an MRI:
You will be asked to sign a consent form that says you do not have any of these items in your body.
Before an MRI, sheet metal workers or any person that may have been exposed to small metal fragments should receive a skull x-ray to check for metal in the eyes.
Because of the strong magnets, certain metallic objects are not allowed into the room.
When the MRI magnet is turned on, pens, pocketknives, and eyeglasses may fly across the room. This can be dangerous, so such items are not allowed into the scanner area.
An MRI exam causes no pain. Some people may become anxious when inside the scanner. If you have difficulty lying still or are very anxious, you may be given a mild sedative. Excessive movement can blur MRI images and cause errors.
The table may be hard or cold, but you can request a blanket or pillow. The machine produces loud thumping and humming noises when turned on. Ear plugs are usually given to help reduce the noise.
An intercom in the scanner allows you to speak to the person operating the exam at any time. Some MRIs have televisions and special headphones that you can use to help the time pass.
There is no recovery time, unless sedation was necessary. After an MRI scan, you can resume your normal diet, activity, and medications.
Combining MRIs with other imaging methods can often help the doctor make a more definitive diagnosis.
MRI images taken after a special dye (contrast) is delivered into the body may provide additional information about the blood vessels.
An MRA, or magnetic resonance angiogram, is a form of magnetic resonance imaging, which creates three-dimensional pictures of blood vessels. It is often used when traditional angiography cannot be done.
There is no ionizing radiation involved in MRI, and there have been no documented significant side effects of the magnetic fields and radio waves used on the human body to date.
The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions to the substance rarely occur. The person operating the machine will monitor your heart rate and breathing as needed.
MRI is usually not recommended for acute trauma situations, because traction and life-support equipment cannot safely enter the scanner area and the exam can take quite a bit of time.
People have been harmed in MRI machines when they did not remove metal objects from their clothes or when metal objects were left in the room by others.
Grainger RC, Allison D, Adam, Dixon AK. Diagnostic Radiology: A Textbook of Medical Imaging. 4th ed. Orlando, Fl: Churchill Livingstone; 2001:101-136. Goldman L, Ausiello D. Cecil Textbook of Medicine, 22nd ed. Philadelphia, Pa: WB Saunders; 2004: 29.
On July 3, 1977, an event took place that would forever alter the landscape of modern medicine. Outside the medical research community, this event made scarcely a ripple at first. This event was the first MRI exam ever performed on a human being.
It took almost five hours to produce one image. The images were, by today's standards, quite ugly. Dr. Raymond Damadian, a physician and scientist, along with colleagues Dr. Larry Minkoff and Dr. Michael Goldsmith, labored tirelessly for seven long years to reach this point. They named their original machine “Indomitable” to capture the spirit of their struggle to do what many said could not be done.
This machine is now in the Smithsonian Institution. As late as 1982, there were but a handful of MRI scanners in the entire United States. Today there are thousands. We can image in seconds what used to take hours. MRI is a very complicated technology not well understood by many. In this article, you'll learn all about how a huge, noisy MRI machine actually works. What is happening to your body while you are in the machine? What can we see with an MRI and why do you have to hold so still during your exam? These questions and many more are answered here, so let's get started!
If you have ever seen an MRI machine, you know that the basic design used in most is a giant cube. The cube in a typical system might be 7 feet tall by 7 feet wide by 10 feet long (2 m by 2 m by 3 m), although new models are rapidly shrinking. There is a horizontal tube running through the magnet from front to back. This tube is known as the bore of the magnet. The patient, lying on his or her back, slides into the bore on a special table. Whether or not the patient goes in head first or feet first, as well as how far in the magnet they will go, is determined by the type of exam to be performed. MRI scanners vary in size and shape, and newer models have some degree of openness around the sides, but the basic design is the same. Once the body part to be scanned is in the exact center or isocenter of the magnetic field, the scan can begin.
In conjunction with radio wave pulses of energy, the MRI scanner can pick out a very small point inside the patient's body and ask it, essentially, “What type of tissue are you?” The point might be a cube that is half a millimeter on each side. The MRI system goes through the patient's body point by point, building up a 2-D or 3-D map of tissue types. It then integrates all of this information together to create 2-D images or 3-D models. MRI provides an unparalleled view inside the human body. The level of detail we can see is extraordinary compared with any other imaging modality. MRI is the method of choice for the diagnosis of many types of injuries and conditions because of the incredible ability to tailor the exam to the particular medical question being asked. By changing exam parameters, the MRI system can cause tissues in the body to take on different appearances. This is very helpful to the radiologist (who reads the MRI) in determining if something seen is normal or not. We know that when we do “A,” normal tissue will look like “B” – if it doesn't, there might be an abnormality. MRI systems can also image flowing blood in virtually any part of the body. This allows us to perform studies that show the arterial system in the body, but not the tissue around it. In many cases, the MRI system can do this without a contrast injection, which is required in vascular radiology.
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Vannelli A, Basilico V, Zanardo M, Caizzone A, Rossi F, Battaglia L, Scaramuzza D.
Division of Gastrointestinal and Surgical Oncology, Ospedale Valduce, Como, Italy. email@example.com.
BACKGROUND: Functional pelvic disorders in patients undergoing conservative surgical approach for rectal cancer are considered a major public health issue and represent one third of cost of colorectal cancer. We investigated the hypothesis that lymphadenectomy, involves the pelvic floor results in a localized hides or silent pelvic lymphedema characterized by symptoms without signs.
PATIENTS AND METHODS: We examined 13 colo-rectal cancer patients: five intra-peritoneal adenocarcinoma: 1 sigmoid and 4 upper third rectal cancer (1 male and 3 female) and 9 extra-peritoneal adenocarcinoma: 3 middle and 5 lower third rectal cancer (4 male and 5 female) using 1.5-T magnetic resonance, one week before and twelve months after discharged from hospital.
RESULTS: Lymphedema was discovered on post-operative magnetic resonance imaging of all 9 patients with extra-pertitoneal cancer, whereas preoperative magnetic resonance imaging as well as a post-operative examination of 4 intra-peritoneal adenocarcinoma, revealed no evidence of lymphedema. Unlike the common clinical skin signs that typify all other sites of lymphedema, pelvic lymphedema is hides or silent, with no skin changes or any single symptom manifested. Magnetic resonance imaging showed that pelvic illness alone is accompanied by lymphedema related exclusively to venous congestion, and accumulation of liquid in adipose tissue or lipedema.
CONCLUSIONS: Alteration of the pelvic lymphatic network during pelvic surgery can lead to lymphedema and, pelvic floor disease. Patients should be routinely examined for the possibility of developing this post-surgical syndrome and further studies are needed to establish diagnosis and to evaluate treatment preferences.
Br J Surg. 2010 Jan 25
Liu NF, Lu Q, Liu PA, Wu XF, Wang BS.
email: N.-F. Liu (firstname.lastname@example.org)
*Correspondence to N.-F. Liu, Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai 200011, China
Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, China.
BACKGROUND: Lymphoscintigraphy is widely used to image the lymphatic system. The aim of this study was to compare lymphoscintigraphy and dynamic magnetic resonance lymphangiography (MRL) in the investigation of extremity lymphoedema.
METHODS: Sixteen patients with primary extremity lymphoedema and two with Klippel-Trenaunay syndrome with lymphoedema were examined by lymphoscintigraphy using the tracer (99)Tc-labelled dextran, and by MRL using gadobenate dimeglumine as contrast agent. Morphological abnormalities and functional state of the lymphatic systems of affected limbs were compared between the two imaging methods.
RESULTS: Lymphatic vessels were imaged in 14 of 18 limbs with lymphoedema using MRL, compared with one of 18 using lymphoscintigraphy. MRL detected the inguinal nodes in 16 of 17 patients, whereas lymphoscintigraphy revealed inguinal nodes in only nine. MRL revealed more precise information about structural and functional abnormalities of lymph vessels and nodes than lymphoscintigraphy by real-time measurement of lymph flow in vessels and nodes.
CONCLUSION: Dynamic MRL was more sensitive and accurate than lymphoscintigraphy in the detection of anatomical and functional abnormalities in the lymphatic system in patients with extremity lymphoedema. British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.
J Vasc Surg. 2005 Jan
u N, Wang C, Sun M. Department of Plastic & Reconstructive Surgery, Shanghai9th People's Hospital, Shanghai Second Medical University, 639 Zhi Zao Ju Rd, Shanghai 200011, China. Liun2002@yahoo.com
BACKGROUND: Visualization of the lymphatic vessels is a challenge in patients with disorders of the lymphatic circulation. In an effort to improve the diagnostic scope of lymphatic imaging, we compared traditional lymphoscintigraphy (LSG) with three-dimensional magnetic resonance imaging (3D MRI).
METHODS: From October 1, 2002, to May 30, 2004, 39 patients (27 males and 12 females) with lower extremity lymphedema and/or skin lymphorrhea in the abdominal wall or the external genitalia underwent LSG and 3D MRI. Patients' ages ranged from 3 to 71 years. Assessment of the imaging studies included the degree and quality of visualization of the malformations of the lymphatic collectors, lymphatic trunk, lymph nodes, and tissue edema.
RESULTS: In patients with lymphedema, chylous reflux syndrome, or both, LSG depicted the enlarged lymphatics and nodes as a fused band or mass. In 3D MRI, the dilated superficial lymphatic collectors and deep lymphatic trunks, as well as the accumulation of chyle and node enlargements, were clearly visualized. In patients with hypoplasia or aplasia of the lymphatics, LSG usually displayed the pattern of dermal backflow in the form of radiotracer filling of the dermal lymphatics or stagnation of the isotope at the injection point. The images obtained by 3D MRI were able to demonstrate the extent of tissue fluid accumulation and distinguish edema fluid from subcutaneous fat.
CONCLUSIONS: In patients with peripheral and central lymphatic malformations, LSG provided images representative of the function of the lymphatic vessels but failed to give detailed information regarding its anatomy. 3D MRI provided extensive information on the anatomy of the lymph stagnated vasculature as well as on the effects of lymphatic dysfunction on local structures and tissue composition.
J Comput Assist Tomogr. 2007 Mar-Apr
Lohrmann C, Foeldi E, Bartholomä JP, Langer M. Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Freiburg, Germany. email@example.com
OBJECTIVE: To assess the feasibility of a time-efficient, high-resolution magnetic resonance lymphangiography (HR MRL) protocol without image subtraction for the detection of lymphatic vessels in patients with primary and secondary lymphedema.
METHODS: Three consecutive patients with lymphedema of the lower extremities (2 primary bilateral, 1 secondary unilateral) underwent HR MRL without image subtraction. An amount of 9 mL of gadodiamide and 1 mL of mepivacaine hydrochloride 1% were subdivided into 5 portions and injected intracutaneously into the dorsal aspect of each foot outside the scanner before image acquisition. Magnetic resonance imaging was performed with a 1.5-T system equipped with high-performance gradients. For HR MRL, a 3-dimensional, spoiled gradient-echo sequence (Volumetric Interpolated Breath-hold Examination) was used. The extent and distribution of the lymphedema was evaluated using a heavily T2-weighted, 3-dimensional turbo-spin echo sequence.
RESULTS: The HR MRL bilaterally detected the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg in the 2 patients with primary lymphedema. In the patient with left-sided secondary lymphedema, the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg were depicted on the right side. The diameter of the displayed lymphatic vessels varied between 1 and 5 mm. Three-dimensional, maximum-intensity projection images of different angles of view provided detailed outlining of the lymphatic vessels and differentiation from veins, which showed a lower signal intensity.
CONCLUSION: The HR MRL without image subtraction is safe, technically feasible, and has the potential to become a diagnostic imaging tool in daily clinical practice because of its time efficiency.
Acta Trop. 2007 Jul 12
Lohrmann C, Foeldi E, Bartholomä JP, Langer M. Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, D-79106 Freiburg, Germany.
BACKGROUND: To assess the feasibility of interstitial magnetic resonance lymphangiography with intracutaneous injection of a commercially available, non-ionic, extracellular paramagnetic contrast agent, to visualize lymphatic vessels in patients with clinically advanced stages of primary lymphedema.
METHODS: Sixteen lower extremities in 8 patients with clinically advanced stages of primary lymphedema were examined with magnetic resonance lymphangiography. A 18mL of gadodiamide and 2mL of mepivacainhydrochloride 1% were subdivided into 10 portions and injected intracutaneously into the dorsal aspect of both feet. For MRL, a 3D spoiled gradient-echo sequence (Volumetric Interpolated Breathold Examination, VIBE) was performed.
RESULTS: The beaded appearance of lymphatic vessels extending from the injection site was detected in all 16 lower extremities (100%). In 10 lower extremities (63%), lymphatic vessels of the upper leg could be visualized. A contrast enhancement was observed in 10/16 glossary:inguinal nodes|inguinal lymph node]] groups (63%). In 12 lower extremities (75%) collateral vessels with dermal back-flow areas between lymphatic vessels were seen.
CONCLUSION: Magnetic resonance lymphangiography is safe, technically feasible, and assists the clinician in the therapeutic planning of patients with clinically advanced stages of primary lymphedema by imaging the pathologically modified lymphatic vessels and accompanying complications non-invasively.
Int Angiol. 2007 De
Dimakakos E, Koureas A, Koutoulidis V, Skiadas V, Katsenis K, Arkadopoulos N, Gouliamos A, Vlachos L. Vascular Unit, 2nd Department of Surgery, University of Athens firstname.lastname@example.org.
AIM: The aim of this study was to evaluate the method of interstitial magnetic resonance lymphography (MRL) as an examination for the depiction of the lymphatic system in humans in comparison with the method of direct X-ray lymphography.
METHODS: We studied 6 persons, 2 volunteers and 4 patients with clinical suspicion of lymphedema in lower extremities. We administered subcutaneous gadobutrol for the MRL with a volume of 5 mL composed of 4.5 mL of Gadobutrol mixed with 0.5 mL of lidocaine hydrochloride and after 7 days lipiodol in the lymph vessel for the X-ray direct lymphography (in 3 patients) in order to compare the findings of the two
METHODS: We then followed up all individuals for 7 days for any possible side effect of the contrast agents.
RESULTS: Using MRL, we depicted the lymphatic system (lymph vessels and inguinal lymph nodes) of volunteers in 60 min. Moreover, in patients we depicted several abnormalities of the lymphatic system including decreased number of lymph vessels, lymphocele and ectatic lymph vessels. X-ray direct lymphography confirmed the findings of the MRL in all cases. No side effects were observed.
CONCLUSION: In our pilot study, Gadobutrol seems to be a good contrast agent for the painless depiction of the lymphatic system in humans through interstitial MRL. More extensive studies are needed in order to establish the efficacy and the dosage of Gadobutrol. PMID: 18091705
[Article in Chinese]
Liu N, Wang C, Ding Y.
Department of Plastic Surgery, Chang Zheng Hospital, Shanghai 200003.
OBJECTIVE: To investigate the features of chronic lymphedema of the extremity.
METHODS: Magnetic resonance imaging (MRI) and lymphangioscintigraphy (LAS) examinations were performed on 12 patients with peripheral lymphedema.
RESULTS: MRI characteristically showed diffusive subcutaneous edema, reticular lymphangiectasis and “channels” with sequestered lymph. MRI scan clearly displayed the proliferative and extended lymphatic vessels, trunks and chylocyst. LAS showed dermal diffusion (dermal backflow) or retention at the injection site of the tracer with poorly defined lymphatic trunks and delayed or no visualization of regional lymph nodes.
CONCLUSION: MRI can visualise peripheral lymph trunks, lymph nodes and soft tissue. LAS is more helpful in ascertaining the condition of obstruction of lymphatic system. Using these two imaging modalities together is helpful for anatomical diagnosis and delineating the disarranged pattern of lymphedema.
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Updated Nov. 14, 2011