Iodine-123-metaiodobenzylguanidine myocardial imaging in patients with right ventricular pressure overload.
Iodine-123-metaiodobenzylguanidine ([123I]MIBG) has been used to evaluate the cardiac sympathetic nervous system, particularly that of the left heart. To clarify whether the right ventricular (RV) sympathetic neuronal function could be evaluated by [123I]MIBG myocardial imaging, we applied the technique in patients with pulmonary hypertension that was associated with either chronic pulmonary diseases or pulmonary vascular diseases.


METHODS
All patients underwent right heart catheterization, and right heart hemodynamics were determined during a clinically stable state. SPECT was performed in the resting state 15 min (early imaging) and 4 hr (delayed imaging) postadministration of [123I]MIBG. Seven regions of interest (ROI) were selected on the delayed short-axis images on the RV free wall, left ventricular (LV) free wall and interventricular septum (IVS). We calculated the IVS-to-LV uptake ratio from the scintillation counts of the ROI. Thallium-201 myocardial imaging was also performed within 1 wk after [123I]MIBG imaging.


RESULTS
Images obtained with these techniques were analyzed for the RV-to-LV uptake ratio. The IVS-to-LV ratio on [123I]MIBG correlated negatively and significantly with the mean pulmonary arterial pressure (PAm). The RV-to-LV uptake ratio on 201Tl images correlated significantly with PAm.


CONCLUSIONS
Our results suggest that the uptake ratio of [123I]MIBG in the IVS is a useful index for evaluating the severity of pulmonary hypertension, and that chronic RV pressure overload contributes to disturbances of the cardiac sympathetic nervous system.
Morimitsu
T
T
Second Department of Internal Medicine, Nagasaki University, School of Medicine, Japan.
Miyahara
Y
Y
Sinboku
H
H
Ikeda
S
S
Naito
T
T
Nishijima
K
K
Takao
M
M
D019797:3-Iodobenzylguanidine; D006328:Cardiac Catheterization; D003287:Contrast Media; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000000981:diagnostic imaging; D017380:Hypertrophy, Right Ventricular / Q000150:complications / Q000000981:diagnostic imaging*; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000503:physiopathology; D013794:Thallium Radioisotopes; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon
D003287:Contrast Media; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D013794:Thallium Radioisotopes; D019797:3-Iodobenzylguanidine