Imaging of the Kidneys
The kidneys are vital to the normal function of the human body, serving to filter toxins from the bloodstream, regulate acid-base balance, and help control blood pressure. In disease and in health, the kidneys lend themselves to a number of different imaging techniques, including x-ray, computed tomography (CT scan), magnetic resonance imaging (MRI), nuclear medicine, and ultrasound. The radiologist is trained to help determine the proper imaging test, interpret the imaging information, consult with the patient’s physician and, in many cases, use imaging to guide treatment.
Recently, newer 3-dimensional techniques have allowed us to image the kidneys in elegant detail. Below are some of the medical conditions for which imaging can play a valuable role in diagnosis and treatment.
North Carolina lies firmly in the center of “The Stone Belt,” a name given to the southern United States for its high incidence of kidney stones.
Each year, urologists, emergency physicians, and other physicians treat thousands of patients suffering from complications of kidney stones. CT scans have become the mainstay in the diagnosis and evaluation of stones, demonstrating their size, number, location, and sometimes even their chemical composition. When a stone is large enough to block the outflow of urine, imaging can guide the placement of a tube to relieve the obstruction. Finally, nuclear medicine scans can show how well each kidney is functioning before and after treatment of kidney stones or obstruction.
In the past, the most common type of kidney cancer, renal cell carcinoma, often came to medical attention only due to its large size or painful spread to the bones or elsewhere within the body, too late for a cure to be possible. Over the last 15-20 years, abdominal CT scans have become much more common in the evaluation of a variety of conditions, leading to the discovery of an ever-increasing number of small, early-stage renal cell carcinomas. At this point, cure can be achieved in up to 60-70% of patients by limited surgery, known as partial nephrectomy. In addition, radiology can now play an important role in the treatment of small kidney tumors using a technology called image- guided ablation. These techniques use radiofrequency (heat) or cryotherapy (cold) to thermally destroy the cancers through a small incision in the skin, often with minimal pain and recovery time.
Chronic kidney failure, infection, and other problems
Unfortunately, high blood pressure, diabetes, and atherosclerosis are increasingly common health conditions facing women today and are major causes of decreased kidney function. Ultrasound can show the effects of these “silent killers,” and CT or MRI angiography can evaluate whether the arteries to the kidneys are narrowed. When kidney failure occurs without an obvious cause, ultrasound and CT scans can detect when the failure is due to a blockage. Imaging can also be used to guide kidney biopsy, which can be analyzed by pathologists and nephrologists to determine a diagnosis. After kidney transplant, ultrasound is often used to ensure normal blood flow to the kidney or rule out an obstruction.
Severe kidney infections, more common in women, can be diagnosed and treated through the use of imaging. Finally, fetal and perinatal ultrasound and MRI can help diagnose kidney disease at the earliest stages of life.
In summary, radiologists and other physicians rely heavily on medical imaging in the management of kidney disease. Each of the imaging tests discussed above is available at one or more of the local Novant-affiliated hospitals, imaging centers or physician’s offices.
By Andrew R. Deibler, MD, Staff Radiologist, Abdominal and Musculoskeletal Imaging Triad Radiology Associates