title: Clinical evaluation of no-carrier-added meta-[123I]iodobenzylguanidine for myocardial scintigraphy.
abstract: In clinical and research studies, images obtained using carrier-added meta-[123I]iodobenzylguanidine (c.a. [123I]MIBG) have shown quite variable quality, with varying levels of uptake in lung, liver and mediastinum; this is a significant problem for quantification of the myocardial uptake by means of region ratios. First experimental and preliminary human data in respect of no-carrier-added (n.c.a.) [123I]MIBG are indicative of improved imaging quality. The aim of the present study was to evaluate the clinical value of myocardial scintigraphy with n.c.a. [123I]MIBG in patients with tachyarrhythmias. The study population comprised 24 patients with tachyarrhythmogenic diseases routinely studied by cardiac single-photon emission tomography (SPET) with [123I]MIBG. Twelve of the 24 patients were studied with c.a. [123I]MIBG (seven females and five males; mean age 42+/-13 years, range 20-60 years), whereas the other 12 were studied with n.c.a. [123I]MIBG (ten females, two males; mean age 41+/-11 years, range 18-60 years, P=NS). For quantification of the specific uptake in the different organs, count ratios were calculated on SPET images acquired 4 h p.i. Visual analysis of all [123I]MIBG scans showed improved image quality (improved contrast between heart and neighbouring organs) in n.c.a. studies as compared with c.a. studies. A significantly higher heart/left atrial blood ratio was found in the n.c.a. studies as compared with the c.a. studies (10.3+/-3.2 vs 5.3+/-1.3, P=0.0003); furthermore, significantly higher heart/lung and heart/liver ratios (2.5+/-0.6 vs 1.5+/-0.3, P=0.0002, and 0.8+/-0.2 vs 0.6+/-0.1, P=0.0006, respectively) were obtained in the c.a. studies, whereas lung/left atrial blood and liver/left atrial blood ratios showed no significant differences (4.2+/-1.3 vs 3.6+/-1.1, P=0.39, and 13.7+/-5.2 vs 9.6+/-2.2, P=0.21, respectively). In conclusion, the use of n.c.a. [123I]MIBG yields a significantly higher myocardial uptake associated with improvement in contrast between the heart and neighbouring organs and is therefore superior to the commercially available c.a. [123I]MIBG for use in clinical and research studies of the myocardial presynaptic sympathetic nervous system. Furthermore, our data indicate that for quantification the use of a left atrial blood reference region of interest, which is only available on SPET studies, is to be recommended.
authors.affiliation: Department of Nuclear Medicine, Münster University, Germany. knickme@uni-muenster.de
authors.forename: M
authors.initials: M
authors.lastname: Knickmeier
authors.forename: P
authors.initials: P
authors.lastname: Matheja
authors.forename: T
authors.initials: T
authors.lastname: Wichter
authors.forename: K P
authors.initials: KP
authors.lastname: Schäfers
authors.forename: P
authors.initials: P
authors.lastname: Kies
authors.forename: G
authors.initials: G
authors.lastname: Breithardt
authors.forename: O
authors.initials: O
authors.lastname: Schober
authors.forename: M
authors.initials: M
authors.lastname: Schäfers
mesh_terms: D019797:3-Iodobenzylguanidine; D000293:Adolescent; D000328:Adult; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D017180:Tachycardia, Ventricular / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine