A phantom study: Should ¹²⁴ I-mIBG PET/CT replace ¹²³ I-mIBG SPECT/CT?

Area of Science:

• Nuclear medicine
• Radiopharmaceutical imaging
• Oncology

Background:

• 123I-mIBG SPECT/CT is standard for neuroendocrine tumor imaging (pheochromocytomas, neuroblastomas).
• 124I-mIBG PET/CT is an alternative with potential for superior image quality.
• Current protocols involve SPECT/CT for staging, follow-up, and treatment selection.

Purpose of the Study:

• To compare the image quality of 124I-mIBG PET/CT versus 123I-mIBG SPECT/CT.
• To evaluate performance at an equal effective patient radiation dose (mSv).

Main Methods:

• Phantom measurements using NEMA-2007 phantom.
• SPECT and PET reconstructions with and without time-of-flight (TOF) and point-spread-function (PSF) modeling.
• Image quality assessed by contrast-to-noise ratio (CNR); Contrast Equivalent Activity Ratio (CEAR) determined.

Main Results:

• CEARs ranged from 9.1 to 47.7 for various reconstruction methods and sphere sizes.
• An equal effective dose requires a CEAR of 5-10, considering dose differences (mSv/MBq).
• CEARs significantly exceeded 5-10 for most tested conditions, indicating superior 124I PET/CT performance.

Conclusions:

• 124I-mIBG PET/CT demonstrates superior image quality compared to 123I-mIBG SPECT/CT at equivalent radiation doses.
• The findings suggest 124I-mIBG PET/CT can enhance diagnostic accuracy.
• Potential exists to reduce patient effective dose while maintaining or improving image quality.