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Radiology Coding Alert

Four Tips Help You Breathe Easier When Coding Lung Scans

Published on Fri Mar 01, 2002

Radiology coders specializing in nuclear medicine have long struggled with the complexities of reporting lung scans. A range of factors impacts the choice of codes, including whether blood or air flow is being measured, which agents are used to help determine the diagnosis (e.g., radioactive particles tagged to an agent in an aerosol or a radioactive gas such as Xenon), and whether a combination of procedures is being performed. In addition, nuclear radiologists sometimes use terminology in their reports that differs from CPT verbiage, adding to a coder's confusion.
 
Lung scans are most commonly ordered when patients present with chest pain (e.g., 786.50, Chest pain, unspecified), shortness of breath (786.05, Symptoms involving respiratory system and other chest symptoms, dyspnea and respiratory abnormalities, shortness of breath), painful respiration (786.52, painful respiration) or similar symptoms, according to Stacie L. Buck, RHIA, internal auditor for U.S. Diagnostic Inc., a corporation based in West Palm Beach, Fla. These signs might arise if a disease or condition is interfering with the flow of air or blood to the lungs. Depending on the circumstances, a perfusion or a ventilation scan can help determine precisely what's at fault.

Consider Four Points Before Coding Scans

 1. Determine whether blood or airflow is being measured. When choosing the appropriate code, the most basic consideration is whether the nuclear radiologist is measuring blood or air flow, says April Brazinsky, CCS, coding specialist for the Community Hospital of the Monterey Peninsula in California. "A ventilation study indicates that the physician is measuring the flow of air in and out of the lungs. This is usually done when conditions like bronchopneumonia (514, Pulmonary congestion and hypostasis) are suspected. On the other hand, a perfusion study is ordered when the radiologist believes that the problem may be within the pulmonary circulatory system, and how effectively the blood is flowing to and through the lungs. Symptoms may suggest a pulmonary embolism (415.1, Acute pulmonary heart disease, pulmonary embolism and infarction), for instance."

 2. Perfusion studies rely on radioactive particulate matter. When a simple perfusion study is performed without any additional scans, 78580 (Pulmonary perfusion imaging, particulate) is used. This exam consists of the injection of protein particles tagged with a radioactive material which are carried through the vascular system and trapped by the small arterioles of the pulmonary circulatory system where images are obtained, Buck says. Although commonly conducted by itself, it is also often done in conjunction with ventilation exams.

 3. Ventilation studies use radioactive gas or nebulized aerosol agents. Five codes describe simple ventilation studies, depending on whether radioactive gas or nebulized aerosol agents are used to measure the patient's airflow. Patients inhale one of these substances, Brazinsky notes, and images are then taken to evaluate the ventilation capacity of the lungs. If aerosol ventilation studies are conducted, coders would choose between 78586 (Pulmonary ventilation imaging, aerosol; single projection) when a single projection is assessed and 78587 ( multiple projections [e.g., anterior, posterior, lateral views]) when several different images are made.
 
Three codes describe gaseous ventilation studies. Code 78591 is for Pulmonary ventilation imaging, gaseous, single breath, single projection, while 78593 is for Pulmonary ventilation imaging, gaseous, with rebreathing and washout with or without single breath; single projection. Code 78594 replaces 78593 when multiple projections (e.g., anterior, posterior, lateral views) are taken.
 
Buck explains that "rebreathing" refers to the inhalation of the gasses previously exhaled, while "washout" refers to the elimination of the radioisotope from the lungs. The xenon gas exams typically consist of three phases:

 1) A single breath where the patient takes a single deep inspiration
 2) Patient takes normal tidal respirations while rebreathing a mix of oxygen and xenon
 3) Washout occurs when inhalation is discontinued and the patient breathes room air while exhaling the xenon.

Buck adds that, in a report, the physician will usually mention "air trapping" when a washout has been part of the exam. 

4. Use comprehensive codes when studies are combined. When determining a definitive diagnosis, nuclear radiologists often perform both perfusion and ventilation studies, Buck says. In this case, it is essential for coders to read the complex CPT definitions carefully to ensure the code they assign accurately reflects the service. "The most important factor is determining if the ventilation portion of the scans used gas or aerosol," she says. When perfusion and gaseous ventilation procedures are done, 78584 (Pulmonary perfusion imaging, particulate, with ventilation; single breath) or 78585 ( rebreathing and washout, with or without single breath) are assigned. When the ventilation portion of the combined procedures is performed with a radio-labeled aerosol, 78588 (Pulmonary perfusion imaging, particulate, with ventilation imaging, aerosol, one or multiple projections) is assigned.
 
Because these are comprehensive codes, never assign 78584 or 78585 with 78580, 78591, 78593 or 78594. By the same token, 78588 would never be reported with 78580, 78586 or 78587. Likewise, never assign one of these bundled codes (i.e., 78584, 78585 and 78588) with a -52 modifier (Reduced services) for any procedure that did not entail both the perfusion and ventilation scans. This is unnecessary, since an appropriate code from the respiratory imaging series 78580-78599 may be chosen to accurately describe any of the single procedures.
 
Note: Code 78596 (Pulmonary quantitative differential function [ventilation/perfusion] study) describes a relatively new scan that measures percentages of perfusion and aeration in the various lobes of the lung in an effort to determine how a patient will handle possible removal of a part of the lung. It is performed presurgically and is primarily used in nonembolic disease processes. The result is calculated by comparing lungs, or dividing each lung into thirds and calculating the percentage of total counts in each region.
 
Practices that incur out-of-pocket expenses for procuring the radiopharmaceuticals for any of these studies may also submit claims for the agents. Those radiopharmaceuticals most commonly used are reported with A4641 (Supply of radiopharmaceutical diagnostic imaging agent, not otherwise classified) and include technetium Tc99m (MAA) macroaggregated albumin 3-5mCi dose, which is used with studies defined by 78580-78585 and 78596; technetium Tc99m (DTPA) diethylene triamine pentaacetic acid (Aerosol) 20-40mCi dose, which is used with 78586-78588 and 78596; and xenon gas (Xe-133), which is used with 78591-78594 and 78596.

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