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Colonoscopy is a test that allows your doctor to look at the inner lining of your large intestine (rectum and colon). He or she uses a thin, flexible tube called a colonoscope to look at the colon. A colonoscopy helps find ulcers, colon polyps, tumors, and areas of inflammation or bleeding.
The complex circuitry interconnecting different areas in the brain, known collectively as white matter, is composed of millions of axons organized into fascicles and bundles. Upon macroscopic examination of sections of the brain, it is difficult to discern the orientation of the fibers. The same is true for conventional imaging modalities. However, recent advancements in magnetic resonance imaging (MRI) make such task possible in a live subject. By sensitizing an otherwise typical MRI sequence to the diffusion of water molecules it is possible to measure their diffusion coefficient in a given direction1. Normally, the axonal membrane and myelin sheaths pose barriers to the movement of water molecules and, thus, they diffuse preferentially along the axon2. Therefore, the direction of white matter bundles can be elucidated by determining the principal diffusivity of water. The three-dimensional representation of the diffusion coefficient can be given by a tensor and its mathematical decomposition provides the direction of the tracts3; this MRI technique is known as diffusion tensor imaging (DTI). By connecting the information acquired with DTI, three-dimensional depictions of white matter fascicles are obtained4. The virtual dissection of white matter bundles is rapidly becoming a valuable tool in clinical research.
Our journey begins with a transverse section of tightly packed axons as seen through light microscopy. Although represented as a two-dimensional "slice", we see that these axons in fact resemble tubes. A simulation of water molecules diffusing randomly inside the axons demonstrates how the membranes and myelin hinder their movement across them and shows the preferred diffusion direction --along the axons. The tracts depicted through DTI slowly blend in and we ride along with them. As we zoom out even more, we realize that it is a portion of the corpus callosum connecting the two sides of the brain we were traveling on and the great difference in relative scale of the individual axons becomes evident. The surface of the brain is then shown, as well as the rest of the white matter bundles--a big, apparently chaotic tangle of wires. Finally, the skin covers the brain.
With the exception of the simulated water molecules, all the data presented in the animation is obtained through microscopy and MRI. Computer algorithms for the extraction of the cerebral structures and a custom-built graphics engine make our journey through the brain's anatomy possible in a living person.
Micrograph courtesy of Dr. Christian Beaulieu, University of Alberta.
Music by Mario Mattioli.
References:
1. Stejskal, E.O., et al., J. Chem. Phys., 1965. 42:
2. Beaulieu, C., NMR Biomed., 2002. 15:435-55.
3. Basser, P.J., et al., J. Magn. Reson. B, 1994. 103:247-54.
4. Mori, S., et al., NMR Biomed., 2002. 15:468-80.
De Quervain's tenosynovitis (dih-kwer-VAINS ten-oh-sine-oh-VIE-tis) is a painful condition affecting the tendons on the thumb side of your wrist. If you have de Quervain's tenosynovitis, it will probably hurt when you turn your wrist, grasp anything or make a fist. Although the exact cause of de Quervain's tenosynovitis isn't known, any activity that relies on repetitive hand or wrist movement — such as working in the garden, playing golf or racket sports, or lifting your baby — can make it worse. Symptoms ShareTweet June 13, 2015 References Products and Services Mayo Clinic Sports Medicine Newsletter: Mayo Clinic Health Letter See also Prednisone risks, benefits Prednisone withdrawal: Why taper down slowly? Integrative approaches to treating pain Lifestyle strategies for pain management Nutrition and pain Pain rehabilitation Self-care approaches to treating pain Show more Advertisement Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Advertising & Sponsorship PolicyOpportunitiesAd Choices Mayo Clinic Store Check out these best-sellers and special offers on books and newsletters from Mayo Clinic. NEW! – The Mayo Clinic Diet, Second Edition Healthy Heart for Life! Mayo Clinic on Better Hearing and Balance Treatment Strategies for Arthritis The Mayo Clinic Diet Online
Pregnancy ultrasounds are performed mainly using transabdominal ultrasound. For many women, especially after 8 weeks gestation, sufficient information about the baby may be obtained with transabdominal ultrasound only. However, in the early pregnancy, the developing embryo is very small (at 6 weeks gestation, the baby is only 5-9mm long) and a transvaginal ultrasound may be required to get a better image of the baby. Transvaginal ultrasound is safe and commonly performed during all stages of pregnancy, including the first trimester. It will not harm you or your baby.
Care must be taken to prevent stenosis at the anastomotic site. If the diameter of the anastomosis is less than 2 cm, the anastomosis should be taken down and resected. A classic end-to-end anastomosis should be performed to ensure adequate diameter to the intestine. If the posterior wall of the colon has been preserved, care should be taken to close the colostomy prior to opening the peritoneal cavity. This will reduce intraperitoneal contamination from the stoma site. Copious irrigation of the wound should be made prior to primary closure. If gross contamination has occurred, delayed closure of the wound should be considered.
Doctors have many options to choose from, including interferon (Avonex, Betaseron, Extavia, and Rebif ), glatiramer acetate (Copaxone), mitoxantrone (Novantrone), teriflunomide (Aubagio), fingolimod (Gilenya), dimethyl fumarate (Tecfidera), and natalizumab (Tysabri).
Diverticula are small, bulging pouches that can form in the lining of your digestive system. They are found most often in the lower part of the large intestine (colon). Diverticula are common, especially after age 40, and seldom cause problems. Sometimes, however, one or more of the pouches become inflamed or infected. That condition is known as diverticulitis (die-vur-tik-yoo-LIE-tis). Diverticulitis can cause severe abdominal pain, fever, nausea and a marked change in your bowel habits. Mild diverticulitis can be treated with rest, changes in your diet and antibiotics. Severe or recurring diverticulitis may require surgery.
A tracheotomy or a tracheostomy is an opening surgically created through the neck into the trachea (windpipe) to allow direct access to the breathing tube and is commonly done in an operating room under general anesthesia. A tube is usually placed through this opening to provide an airway and to remove secretions from the lungs. Breathing is done through the tracheostomy tube rather than through the nose and mouth. The term “tracheotomy” refers to the incision into the trachea (windpipe) that forms a temporary or permanent opening, which is called a “tracheostomy,” however; the terms are sometimes used interchangeably.
Breast abscesses are often linked to mastitis – a condition that causes breast pain and swelling (inflammation), and usually affects women who are breastfeeding. Infections can occur during breastfeeding if bacteria enter your breast tissue, or if the milk ducts (tiny tubes) become blocked. This can cause mastitis which, if not treated, can result in an abscess forming. Women who aren't breastfeeding can also develop mastitis if bacteria enter the milk ducts through a sore or cracked nipple, or a nipple piercing. White blood cells are sent to attack the infection, which causes tissue at the site of the infection to die. This creates a small, hollow area that fills with pus (an abscess).
Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. A variety of organisms, including bacteria, viruses and fungi, can cause pneumonia.
Vasectomy is a minor surgical procedure wherein the vasa deferentia of a man are severed, and then tied or sealed in a manner such to prevent sperm from entering the seminal stream (ejaculate). Typically done in an outpatient setting, a traditional vasectomy involves numbing (local anesthetic) of the scrotum after which 1 (or 2) small incisions are made, allowing a surgeon to gain access to the vas deferens.
Massive bone defects (>8 cm) will not unite without an additional intervention. They require a predictable, durable, and efficient method to regrow bone. The Ilizarov method of tension stress, or distraction osteogenesis, first involves a low-energy osteotomy1 - 5. The bone segments are then pulled apart, most often using an external device at a specific rate and rhythm (distraction phase), after which the newly formed bone (the regenerate) requires time for consolidation. The consolidation phase is variable and usually requires a substantially greater amount of time before the external device can be removed. Our technique of tibial bone transport over an intramedullary nail using cable and pulleys combines internal and external fixation, allowing the external fixator to be removed at the end of the distraction phase. This increases the efficiency of limb reconstruction and decreases the external-fixator-associated complications.
The inflatable penile prosthesis consists of two attached cylinders -- a reservoir and a pump -- which are placed surgically in the body. The two cylinders are inserted in the penis and connected by tubing to a separate reservoir of saline. The reservoir is implanted under the rectus muscles in the lower abdomen. The Coloplast Titan Touch inflatable penile prosthesis is a self-contained, fluid-filled system made from Bioflex and silicone.
Carotid artery stenosis can be caused by cholesterol build-up in the blood vessels (atherosclerosis). Blood clots can form in this area and travel up to the brain. This condition may be present for a long time before symptoms appear. When symptoms do occur, stroke or brief stroke-like attacks are common. If this condition is discovered as a result of a stroke or stroke-like attack, cholesterol lowering medications and blood thinners may be used to improve blood flow to the brain. If the degree of narrowing is severe, surgery may be needed to open the blood vessel.