CPT® Code 0331T

1. Indications

Myocardial sympathetic innervation imaging is indicated for the assessment of various cardiac conditions and to evaluate the sympathetic nervous system's role in heart function. The following conditions may warrant this imaging procedure:

• Heart Disease Assessment of patients with known or suspected heart disease to evaluate sympathetic nerve activity and its implications on cardiac function.
• Heart Failure Identification of sympathetic nerve activity changes in patients with heart failure, which can influence treatment decisions and prognostic evaluations.
• Cardiac Arrhythmias Evaluation of patients experiencing arrhythmias to understand the role of sympathetic innervation in their condition.
• Risk Stratification Assessment of patients at risk for sudden cardiac death or other adverse outcomes related to sympathetic nervous system dysfunction.

2. Procedure

The procedure for myocardial sympathetic innervation imaging involves several key steps to ensure accurate assessment of sympathetic nerve activity in the heart. The following outlines the procedural steps:

• Step 1: Patient Preparation The patient is prepared for the procedure by ensuring they are at rest and have been informed about the imaging process. It is essential to obtain informed consent prior to administering the radiolabeled compound.
• Step 2: Administration of I-mIBG I-mIBG is administered intravenously to the patient. This radiolabeled compound is crucial for visualizing the sympathetic innervation of the heart.
• Step 3: Initial Imaging Radiologic planar views of the chest are obtained 10 to 30 minutes after the administration of I-mIBG. This initial imaging captures the distribution of the radiotracer in the heart and surrounding mediastinal structures.
• Step 4: Delayed Imaging Additional imaging is performed 3 to 4 hours after the initial scan. This delayed imaging allows for a more comprehensive assessment of the uptake and retention of I-mIBG in the heart.
• Step 5: Image Analysis A qualitative assessment of the images is conducted, focusing on the uptake and distribution of mIBG in the heart muscle. This is followed by a quantitative or semi-quantitative assessment, where regions of interest in the heart and mediastinum are identified, and the mIBG uptake is quantified by calculating the heart to mediastinum ratio.
• Step 6: Reporting The physician reviews the images, calculates the heart to mediastinum ratio, and compiles a written report detailing the findings of the imaging study.

3. Post-Procedure

After the myocardial sympathetic innervation imaging procedure, patients are typically monitored for any immediate reactions to the I-mIBG administration. There are generally no specific post-procedure care requirements, but patients may be advised to hydrate adequately to facilitate the clearance of the radiotracer from their system. The physician will review the imaging results and discuss the findings with the patient, including any implications for further management or treatment based on the assessment of sympathetic nerve activity in the heart.