Radiology Question for the Week of January 26, 2026

Question:

If a nuclear medicine planar scan is performed of the knees for a possible infection, would this be coded as 78300 or 78800? Does it matter which radiopharmaceutical was used? Nuclear medicine technologists are saying it should be coded as an infection scan using 78800. Their point is that an infection radiopharmaceutical is being used, so it should be coded as 78800. However, when I read the heading of the section for 78800, it states “(for specific organ, see appropriate heading),” which would be the musculoskeletal system. Since a limited planar scan is present in that section, I believe 78300 should be used.

Answer:

For a planar nuclear medicine scan of the knees performed to evaluate a possible infection, the correct CPT code is 78300 (Bone and/or joint imaging; limited area).

Rationale:

• Anatomic specificity: 78300 is located under the musculoskeletal section and is specifically intended for limited bone or joint imaging. The CPT descriptor explicitly includes evaluation for pain, inflammation, or infection within a limited skeletal area.
• Planar imaging: The study is planar and limited to a single joint area (knees), which aligns with the 78300 code.
• Radiopharmaceutical: While the radiopharmaceutical used may target infection (e.g., tagged WBCs), CPT guidance directs coders to the specific organ/area headings first. The 78800 code is intended for more generalized or nonspecific localization studies of tumors or inflammatory processes across a single area (head, neck, chest, pelvis), unless otherwise indicated for a specific organ, in which case the organ-specific code takes precedence.
• Limited vs. general scan: 78800 would be appropriate if imaging a single non-skeletal area (head, neck, chest, pelvis) for generalized inflammatory or tumor localization. Since this study is of the knee joint, the musculoskeletal section (78300) is the correct heading.

Even if an infection-targeting radiopharmaceutical is used, the site-specific guidance in CPT favors coding to 78300 for limited bone/joint imaging. 78800 would not typically be used in this scenario.