Identify the Different Imaging Tests for Suspected Osteomyelitis
Find out which modality is considered the gold standard. One of the most challenging conditions for physicians and radiologists to diagnose is osteomyelitis. This disease affects the bones and can lead to dire complications if it goes undiagnosed and untreated. Keep reading to learn how radiologists use imaging exams to identify and diagnose osteomyelitis, and how you can report the correct CPT® codes for the tests. Get to Know How Osteomyelitis Develops Osteomyelitis is an infection that develops within a bone. The disease can reach the body part either by traveling there through the bloodstream or from infected tissue nearby. Patients who develop osteomyelitis may experience the following symptoms: The condition may develop following an injury, surgery, or via germs in the bloodstream. Early diagnosis is critical to prevent destruction of the bone, long-lasting infection, sepsis, or amputation. Diagnostic radiology coders commonly come across workflows with multiple imaging studies performed on the same patient so the physician can make an accurate diagnosis. Providers use X-rays, MRI, CT scans, and nuclear medicine to diagnose the patient’s condition, monitor its progression (or stability), and to make effective treatment plans. Understanding the purpose of each imaging modality helps coders accurately interpret imaging reports and coding documentation. Examine the Need for X-Rays Physicians first order X-rays when they suspect osteomyelitis in the patient. According to the American College of Radiology (ACR), X-rays or radiography “is usually appropriate for the initial imaging of suspected osteomyelitis, septic arthritis, or soft tissue infections.” The ACR also notes that body structures that are covered for imaging of suspected osteomyelitis include the ankles, chest, elbows, femurs, feet, forearms, hands, hips, humeri, knees, pelvis, shoulders, tibias/fibulas, and wrists. When the radiologist captures X-ray views of the aforementioned areas, you’ll assign the appropriate codes. Examples of these codes include: Coders should also recognize a major limitation: radiographic abnormalities frequently lag behind the actual infection. Some bone changes might not appear until up to two weeks after the infection begins. The American Academy of Family Physicians (AAFP) notes that plain film radiography has relatively low sensitivity in the early stages of disease. Initial X-ray imaging may appear normal or can show: The ACR does note that initial X-rays do “[provide] an excellent overview of the anatomic area of interest” and can help providers rule out fractures and tumors as the source of the patient’s pain or swelling. Furthermore, X-rays can also assist in interpreting future CT, MRI, ultrasound, and nuclear medicine imaging. Recognize the Gold Standard for Osteomyelitis Imaging If the physician is still concerned about osteomyelitis following the initial imaging, MRI is often the next step. Physicians turn to MRI because the equipment is highly sensitive, which allows it to show changes in bones, joints, muscles, tendons, and other soft tissues. The modality offers excellent evaluation of bone marrow edema, abscesses, sinus tracts, the extent of the infection, and soft tissue involvement. According to the ACR, “MRI is highly accurate for detection of acute osteomyelitis.” One of the modality’s strongest features is its ability to detect infection before significant cortical bone erosion is visible on X-rays. MRI codes in the CPT® code book include procedures performed with contrast, without contrast, and without contrast followed by contrast administration and additional images. Examples of these procedure codes include: While MRI is a preferred imaging modality, CT scans are just as vital in evaluating a patient for osteomyelitis. Use CT Imaging for Detailed Bone Analysis The ACR notes that CT scans can serve as an alternative when MRI is contraindicated or limited. Patients who may undergo CT imaging in lieu of MRI include those with pacemakers or other implanted devices, those who experience severe claustrophobia, or patients with an extensive MRI artifact (for example, metallic implants). CT is particularly useful when evaluating cortical bone detail, hardware-related complications, or chronic infection. Administering contrast material during a CT doesn’t improve the sensitivity for acute osteomyelitis, according to the ACR, but the contrast can help in identifying soft tissue infections like abscesses. Similar to MRI coding, you’ll need to examine the documentation to determine whether the provider administered contrast for the CT scan. Examples of CT scan codes performed with contrast, without contrast, and without contrast followed by additional images after contrast administration include: Because CT and MRI may be performed at different stages of the workup, coders should independently verify medical necessity and documentation for each examination rather than assuming one study replaces another. Nail Down Nuclear Medicine In some cases, structural imaging alone cannot help the provider confidently distinguish infection from postsurgical change, trauma, or degenerative disease. Nuclear medicine studies provide functional information that may help clarify the diagnosis. When MRI is contraindicated for certain patients, the following nuclear medicine studies may be needed: In some cases, an FDG-PET/CT scan may be considered. The ACR indicates that when providers use the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) with a positron emission tomography (PET)/CT scan, the tracer provides “high sensitivity (81 to 100 percent) and high specificity (87 to 100 percent) for the detection of osteomyelitis.” Also, PET imaging has a greater resolution to deliver more precise localization of the condition. These nuclear medicine studies can help detect physical changes in the bones before the structural changes are visible on imaging exams. Identifying physiological changes prior to bone destruction can be helpful when evaluating patients with complicated foot cases or in patients with orthopedic hardware. Know What to Look for Before Assigning Codes Between examining the documentation, reviewing code descriptors, and adhering to payer policies, several factors come into play when selecting the correct procedure codes. When you’re reviewing the radiology report for an imaging exam, you should pay attention to the following elements: Takeaways Imaging studies for suspected osteomyelitis aren’t a one-size-fits-all situation. Each imaging modality has its different strengths and weaknesses. X-rays serve well for initial examinations, MRI remains the preferred method for diagnosing and defining an infection, CT scans show bones with excellent osseous detail, and nuclear medicine studies provide valuable information when other imaging tests are inconclusive or limited. Mike Shaughnessy, BA, CPC, Production Editor, AAPC
