Norwalk Radiology Consultants

Computed tomography, more commonly known as a CT scan, is a medical imaging test. Similar to traditional x-rays, it produces multiple images or pictures of the inside of the body. The images generated during a CT scan can be reformed in multiple ways. They can even generate three-dimensional (3D) images. These images can be viewed on a computer monitor, printed on film or transferred to a CD or DVD. CT images of internal organs, bones, soft tissue and blood vessels provide greater detail than traditional x-rays. Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancer, cardiovascular disease, infectious disease, appendicitis, traumatic injury and skeletal disorders.

CT imaging is one of the fastest and most accurate tools for examining the body because it provides detailed views of all types of organs and tissues. It is used to examine patients with injuries from trauma, such as a motor vehicle accident, and it is performed on patients with acute symptoms such as chest or abdominal pain or difficulty breathing. Often the best method for detecting cancers, CT imaging allows a physician to confirm the presence of a tumor (cancer), measure its size, identify its precise location and determine the extent of its involvement with other nearby organs. It is an examination that plays a significant role in the detection, diagnosis and treatment of vascular diseases that can lead to stroke, heart attacks, kidney failure or even death. Chest CT is used to: • examine abnormalities found on conventional chest x-rays. help diagnose the causes of signs or symptoms of disease of the chest, such as cough, shortness of breath, chest pain, or fever • detect and evaluate the extent of tumors that arise in the chest, or tumors that have spread there from other parts of the body • assess whether tumors are responding to treatment • help plan radiation therapy • evaluate injury to the chest, including the heart, blood vessels, lungs, ribs and spine • investigate benign and malignant tumors • investigate pneumonia • investigate tuberculosis • investigate COPD-chronic lung disease, inflammation, or other diseases of the lung or pleura (the covering of the lungs) • screen asymptomatic people who have smoked a significant amount of cigarettes for the early detection of lung cancer Abdomen CT is used to: • help diagnose the cause of abdominal or pelvic pain and diseases • investigate infections such as appendicitis, kidney infections or infected fluid collections, also known as abscesses • confirm inflammatory bowel disease such as ulcerative colitis or Crohn's disease, pancreatitis or liver cirrhosis • detect cancers of the liver, kidneys, pancreas, ovaries and bladder as well as lymphoma • detect kidney and bladder stones • investigate abdominal aortic aneurysms (AAA), injuries to abdominal organs such as the spleen, liver, kidneys or other internal organs in cases of trauma • guide biopsies and other procedures such as minimally invasive tumor treatments • plan for and assess the results of surgery • stage, plan and properly administer radiation treatments for tumors as well as monitor response to chemotherapy Brain or head CT is used to: • detect bleeding, brain injury and skull fractures • detect bleeding caused by a ruptured or leaking aneurysm in a patient with a severe headache • detect blood clot or bleeding within the brain shortly after a patient exhibits symptoms of a stroke • detect brain tumors • detect enlarged ventricles in patients with hydrocephalus • investigate malformations of the skull • investigate sinus infections • evaluate the extent of damage in patients with facial trauma Spine CT is used to: • assess spine fractures due to injury • evaluate the spine before and after surgery • help diagnose spinal pain • assess for congenital anomalies of the spine or scoliosis • detect various types of tumors in the spinal column, including those that have spread there from another area of the body • guide diagnostic procedures such as the biopsy of a suspicious area to detect cancer, or the removal of fluid from a localized infection (abscess) • provide key information In patients with narrowing (stenosis) of the spine canal, vertebral fracture, infection or degenerative disease such as arthritis CT angiography is used to: • examine blood vessels and the organs supplied by them in various body parts, including the brain, neck, heart, chest, abdomen (such as the kidneys and liver), pelvis, legs and feet, or arms and hands • diagnose and evaluate many diseases of blood vessels and related conditions such as aneurysms, blockages, blood clots, congenital (birth-related) abnormalities of the cardiovascular system including the heart, disorganized blood vessels, such as vascular malformations, injury, tumors, or vessel rupture or tear Cardiac CT scan is used to: • determine if hardening of the arteries (atherosclerosis) is present and to what extent, even if there are no symptoms • investigate patients with risk factors for CAD but no clinical symptoms

If your examination is of the abdomen or pelvis, you may be asked to drink some oral contrast one hour prior to your scheduled appointment. Patients have the option to pick up the oral contrast and instructions before their appointment and begin drinking at home or work. Pickup is available Monday-Friday until 4:30pm. Patients who do not pick-up the oral contrast in advance must arrive at our office one hour prior to their scheduled exam to drink the oral contrast. Otherwise, patients must arrive 15 minutes prior to their scheduled exam. If your examination requires intravenous injection of contrast, one of our staff members will discuss the details with you at the time of your visit.

A specialty-trained board-certified radiologist with expertise in supervising and interpreting radiology examinations will analyze the images and send an official report to your primary care physician or the specialist who referred you for the exam. Once they have reviewed the report and the radiologists' opinions, they will discuss the results with you.

The CT scanner is typically a large, donut-shaped machine with a short tunnel in the center. You will lie on a narrow examination table that slides in and out of this short tunnel. The X-ray tube is rotating around you. The computer workstation that processes the imaging information is located in a separate control room. This is where the technologist operates the scanner and monitors your exam in direct visual contact. The technologist will be able to hear and talk to you using a speaker and microphone.

In many ways, a CT scan works like other x-ray exams. A small amount of radiation is directed through the part of the body being examined. Different body parts absorb x-rays in different amounts . This difference allows the doctor to distinguish body parts from one another on an x-ray or CT image. A detector captures the image. Bones appear white on the x-ray. Soft tissue, such as the heart or liver, shows up in shades of gray. Air appears black. CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the body's interior. Modern CT scanners can scan through large sections of the body in just a few seconds, and even faster in small children. Such speed is beneficial for all patients. It's especially beneficial for children, the elderly and critically ill – anyone who finds it difficult to stay still, even for the brief time necessary to obtain images. For children, the CT scanner technique will be adjusted to their size and the area of interest to reduce the radiation (X-ray) dose. For some CT exams, a contrast material is used to enhance visibility in the area of the body being studied. If contrast material is used, depending on the type of exam, it will be swallowed, or injected through an intravenous line (IV). If you have a known allergy to contrast material, tell your doctor. The CT examination is usually completed within a few minutes. CT exams are generally painless, fast and easy. If an intravenous (IV) contrast material is used, you will feel a pin prick when the needle is inserted into your vein. You may feel warm or flushed while the contrast is injected. You also may have a metallic taste in your mouth. This will pass. You may feel a need to urinate. However, this is a contrast effect and subsides quickly. You will be alone in the exam room during the CT scan. However, the technologist will always be able to see, hear and speak with you through a built-in intercom system. With pediatric patients, a parent may be allowed in the room but will be required to wear a lead apron to minimize radiation exposure.

Because the CT is open at both ends (like a doughnut), most claustrophobic patients find the procedure quite comfortable. If you are severely claustrophobic, you can ask your doctor to prescribe a mild sedative to take prior to the scan.

• CT scanning is painless, noninvasive and accurate. • A major advantage of CT is its ability to image bone, soft tissue and blood vessels all at the same time. • Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue as well as the lungs, bones, and blood vessels. • CT examinations are fast and simple; in emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives. • CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems. • CT is less sensitive to patient movement than MRI. • CT can be performed if you have an implanted medical device of any kind, unlike MRI. • A diagnosis determined by CT scanning may eliminate the need for exploratory surgery and surgical biopsy. • No radiation remains in a patient's body after a CT examination. • X-rays used in CT scans have no immediate side effects.

• There is no conclusive evidence that radiation at small amounts delivered by a CT scan causes cancer. When a CT scan is recommended by your doctor, the expected benefit of this test outweighs the potential risk from radiation. You are encouraged to discuss the risks versus the benefits of your CT scan with your doctor or radiologist, and to explore whether alternative imaging tests may be available to diagnose your condition. • CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the unborn baby. • Because children are more sensitive to radiation, they should have a CT exam only if it is essential for making a diagnosis and should not have repeated CT exams unless absolutely necessary. CT scans in children should always be done with low-dose technique.

The MRI seems to be higher resolution with no radiation; why isn't it a better choice? A doctor may recommend a CT instead of an MRI exam for a number of reasons. CT imaging, in addition to being less expensive, is better than MRI imaging for examining soft tissue.