I-123-MIBG scintigraphy in patients with neuroblastoma

Abstract

Aim: According to German guidelines, I-123-MIBG scintigraphy in neuroblastoma (NB) is preferably performed as early (about 4 h p.i.) and late (24 h p.i.) planar imaging and single- photon emission computed tomography (SPECT) or SPECT/CT 24 h p.i. This study evaluated if the work-up could be reduced to a single timepoint.

Methods: Retrospective analysis of 37 examinations in 26 patients (f:8; m:18; age, 0.5-23.5a) with NB (initial, 15; restaging, 22). All 74 (early + late) pairs of ventral/dorsal planar whole-body images were reviewed by 3 independent readers in random order blinded to clinical data (1, certainly physiological; 2, likely physiological; 3, likely malignant; 4, certainly malignant). CT/MRI or SPECT served as standard of reference if planar images were equivocal.

Results: Two-hundred malignant lesions were rated (1-23 lesions per examination). The lesions' mean score was higher at late vs. early imaging for all readers (3.6 vs. 3.4, 3.7 vs. 3.2, 3.5 vs. 3.2; each p < 0.01). Fifty-one lesions (25.5 %) were considerably underrated at early vs. late imaging (score difference ≥2) by any reader (29/153 skeletal lesions, 12/28 primary tumors [PT], 10/18 abdominal lymph nodes [LN]). Early image did not detect any lesion in 6 patients with PT only. In contrast, 9 lesions (4.5 %) were underrated by late vs. early imaging: 5 skeletal lesions (pelvis, 2; femoral shaft, 3), 1 PT, 3 LN, and 0/1 liver lesions. Tumor spread was underestimated thereby at late vs. early imaging in 1 patient (LN) but SPECT was correct.

Conclusion: The early planar image provided no relevant information over the late image in any patient and may only be performed after weighting of risks (stress) and benefits - especially if SPECT or SPECT/CT is routinely performed. Vice versa, early planar image alone does not suffice.