Design of a short nonuniform acquisition protocol for quantitative analysis in dynamic cardiac SPECT imaging - a retrospective123I-MIBG animal study

Usefulness of 5 Minutes ¹²³I-mIBG Scan in Parkinson's Disease and Heart Failure

BACKGROUND

The use of 123I-mIBG has been approved for decades for Parkinson's disease (PD) diagnosis and as a predictor of mortality and potentially fatal events in patients with Heart Failure (HF). The standardized technique includes an early acquisition (15 minutes from injection), and a late acquisition (240 minutes). Early images mainly represent interstitial uptake, whereas delayed images represent actual neuronal uptake, however, it is reasonable to affirm that different pathological situations, such as PD and HF, imply a different meaning for early and late imaging.

OBJECTIVE

This prospective study aims to investigate the clinical usefulness of an immediate planar 123I-mIBG image acquisition (5 minutes) both in patients with PD and in patients with HF.

METHODS

115 patients referred to 123I-mIBG cardiac imaging in Nuclear Medicine Center have been enrolled (60 patients with PD, absence of diabetes and/or cardiologic pathology, Hoehn e Yahr classification ≤ 1.5; 55 patients with cardiomyopathy, diagnosis of HF, NYHA class I-III). 123I-mIBG planar anterior thoracic acquisitions were performed after 5 (immediate), 15 (early) and 240 (late) minutes from injection and H/M ratios were calculated.

RESULTS

In PD group H/M mean values resulted in 1.58±0.22 for immediate (5 min), 1.61±0.26 for early (15 min) and 1.59±0.37 for late (240 min) acquisitions. In the HF group, H/M mean values resulted in 1.63±0.24 for immediate (5 min), 1.65±0.22 for early (15 min) and 1.57±0.17 for late (240 min) acquisitions, respectively. H/M values obtained at 5 min and 15 min are provided similar results, with no statistical difference (p = ns) regardless of the pathology examined (PD or HF groups). The statistical analyses validated the diagnostic role of immediate acquisition (5 min) and early acquisition (15 min) in PD group as compared to the standardized late acquisition (240 min). On the contrary, in HF group, immediate and early acquisition, as compared to late acquisition (240 min), is not validated as a major cardiac events predictor.

CONCLUSION

Our results indicate the potential role of immediate (5 min) or early (15 min) acquisition in replacement of standardized 240 minutes acquisition in PD patients, but this result is not confirmed in HF patients, in which the acquisition at 240 min is confirmed as the most affordable timing for image interpretation, emphasizing the different pathophysiology that underlies these two pathologies.