Can early phase cardiac [123I]mIBG images be used to diagnose Lewy body disease?

Abstract

PURPOSE:

Some studies have suggested that cardiac [123I]metaiodobenzylguanidine images obtained 15-20 min after tracer administration are as accurate for dementia with Lewy bodies (DLB) diagnosis as standard images acquired after a delay of 3-4 h; some suggest delayed imaging is preferable. We compare early and delayed heart-to-mediastinum ratios (HMR) in a well-characterised research dataset and make recommendations for clinical practice.

METHODS:

Images were acquired using a Siemens gamma camera with medium energy collimators. Early images were obtained at 20 min and delayed at 4 h (± 30) min. In total 167 pairs of images were reviewed: 30 controls, 39 people with dementia and 98 with mild cognitive impairment. HMR normal cutoff values derived from control data were ≥2.10 for early imaging and ≥1.85 for delayed.

RESULTS:

HMR tended to drop between early and delayed for abnormal images, but increase for normal images. Histograms of early and delayed HMR showed a slightly better separation of results into two groups for delayed imaging. Accuracy results were slightly higher for delayed imaging than early imaging (73 vs. 77%), sensitivity 63 vs. 65% and specificity 82 vs. 88%. However, this was not statistically significant - in total only 8/167 (5%) of scans changed designation between early and delayed imaging.

CONCLUSION:

We suggest that a delayed image could be acquired only if the early result is borderline. This removes the need for delayed imaging in about 70% of patients. Adopting this protocol in clinical practice would reduce the time most patients have to wait and could free up scanner time.

• Authors: Gemma Roberts, Joseph P M Kane, Jim Lloyd, Michael Firbank, Paul Christopher Donaghy, George S Petrides, John-Paul Taylor, John O'Brien, Alan J Thomas
• Journal: Nuclear medicine communications (Nucl Med Commun) Vol. 43 Issue 7 Pg. 770-777 (Jul 01 2022) ISSN: 1473-5628 [Electronic] England
• PMID: 35603421 (Publication Type: Journal Article)
• Copyright: Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.

Chemical References

• Iodine Radioisotopes
• Radiopharmaceuticals
• 3-Iodobenzylguanidine
• Iodine-123

Topics

• 3-Iodobenzylguanidine
• Diagnosis, Differential
• Heart (diagnostic imaging)
• Humans
• Iodine Radioisotopes
• Lewy Body Disease (diagnostic imaging)
• Radiopharmaceuticals