Application of I-MIBG myocardial maximum standardized uptake value to characterize cardiac function in patients with pheochromocytoma: comparison with echocardiography.

Purpose: This study examined the usefulness of the maximum standardized uptake value (SUVmax) of myocardial [I]-metaiodobenzylguanidine ([I]-MIBG) to characterize myocardial function by comparing it with echocardiographic parameters in patients with pheochromocytoma.

Materials And Methods: This study included 18 patients with pheochromocytoma who underwent both planar and [I]-MIBG single-photon emission computed tomography/computed tomography scans and echocardiography before surgery. Myocardial [I]-MIBG visibility and SUVmax were compared with echocardiographic parameters related to systolic and diastolic functions. The Mann-Whitney U test, Fisher exact test, or Spearman rank correlation assessed differences or relationships between two quantitative variables.

Results: On visual analysis, 6 patients showed normal myocardial [I]-MIBG uptake, whereas 12 patients showed decreased myocardial [I]-MIBG uptake. No patients showed systolic dysfunction. A significant difference was observed in the incidence of diastolic dysfunction between the groups with normal and decreased uptake (p = 0.009), and left ventricular (LV) diastolic dysfunction was observed in 9 (75%) of 12 patients with decreased myocardial uptake. The myocardial SUVmax was significantly lower in 9 patients with LV diastolic dysfunction than in 9 patients with normal cardiac function (1.67 ± 0.37 vs. 3.03 ± 1.38, p = 0.047). Myocardial SUVmax was positively correlated with septal e' (early diastolic velocity of septal mitral annulus) (ρ = 0.51, p = 0.031) and negatively correlated with the septal E/e' ratio (early mitral E-velocity to early diastolic velocity of septal mitral annulus; ρ =  - 0.64, p = 0.004), respectively.

Conclusions: LV diastolic dysfunction was inversely related to myocardial [I]-MIBG uptake. Myocardial [I]-MIBG SUVmax may be useful for characterizing cardiac function in patients with pheochromocytoma. Second abstract. The semiquantitative analysis using the myocardial SUVmax in I-MIBG SPECT/CT was found to be potentially useful for characterizing cardiac function in patients with pheochromocytoma.