Clinical performance and radiation dosimetry of no-carrier-added vs carrier-added 123I-metaiodobenzylguanidine (MIBG) for the assessment of cardiac sympathetic nerve activity

Abstract

PurposeWe hypothesized that assessment of myocardial sympathetic activity with no-carrier-added (nca) 123I-meta-iodobenzylguanidine (MIBG) compared to carrier-added (ca) 123I-MIBG would lead to an improvement of clinical performance without major differences in radiation dosimetry.MethodsIn nine healthy volunteers, 15 min and 4 h planar thoracic scintigrams and conjugate whole-body scans were performed up to 48 h following intravenous injection of 185 MBq 123I-MIBG. The subjects were given both nca and ca 123I-MIBG. Early heart/mediastinal ratios (H/M), late H/M ratios and myocardial washout were calculated. The fraction of administered activity in ten source organs was quantified from the attenuation-corrected geometric mean counts in conjugate views. Radiation-absorbed doses were estimated with OLINDA/EXM software.ResultsBoth early and late H/M were higher for nca 123I-MIBG (ca 123I-MIBG early H/M 2.46 ± 0.15 vs nca 123I-MIBG 2.84 ± 0.15, p = 0.001 and ca 123I-MIBG late H/M 2.69 ± 0.14 vs nca 123I-MIBG 3.34 ± 0.18, p = 0.002). Myocardial washout showed a longer retention time for nca 123I-MIBG (p < 0.001). The effective dose equivalent (adult male model) for nca 123I-MIBG was similar to that for ca 123I-MIBG (0.025 ± 0.002 mSv/MBq vs 0.026 ± 0.002 mSv/MBq, p = 0.055, respectively).ConclusionNo-carrier-added 123I-MIBG yields a higher relative myocardial uptake and is associated with a higher myocardial retention. This difference between nca 123I-MIBG and ca 123I-MIBG in myocardial uptake did not result in major differences in estimated absorbed doses. Therefore, nca 123I-MIBG is to be preferred over ca 123I-MIBG for the assessment of cardiac sympathetic activity.

Vascular time-activity variation in patients undergoing 123I-MIBG myocardial scintigraphy: implications for quantification of cardiac and mediastinal uptake

“…In subjects with normal renal function, intravenously administered 123 I-MIBG is almost exclusively excreted via the kidneys within 24 h after injection, with approximately 35% of administered 123 I-MIBG already excreted by 6 h [ 5 , 6 ]. There are complex interactions between sympathetic regulation of renal function and cardiac function.…”

“…Since the mediastinum contains a relatively large volume of vascular structures, intravascular 123 I-MIBG activity may contribute to total mediastinal activity which may influence the quantification of the H/M ratio. Since the clearance rate of 123 I-MIBG from the blood is largely dependent on renal function [ 5 , 6 ], and renal dysfunction is often present in HF patients, differences in the rate of vascular clearance may also contribute to increased interindividual variation in uptake quantification [ 7 , 8 ].…”

Renal Function in Relation to Cardiac 123I-MIBG Scintigraphy in Patients with Chronic Heart Failure

“…In subjects with a normal kidney function, intravenous administrated 123 I-MIBG is almost exclusively excreted via the kidneys within 24 hours after injection with approximately 35% of administered 123 I-MIBG already excreted by 6 hours [ 17 , 18 ]. As a reduced GFR is associated with a reduced blood clearance of 123 I-MIBG, the excretion of 123 I-MIBG is not only dependent on filtration but also by tubular secretion [ 10 ].…”

Phase 1 Study of No-Carrier Added 177Lu-DOTATATE (SNU-KB-01) in Patients with Somatostatin Receptor–Positive Neuroendocrine Tumors: The First Clinical Trial of Peptide Receptor Radionuclide Therapy in Korea

“…Targeting SSTR in tumors for radiolabeled peptide analogs are low-capacity systems, and high specific activity is necessary for the effective treatment [14]. In the study comparing NCA and carrieradded (CA) 123 I-MIBG for the assessment of cardiac sympathetic nerve activity, NCA 123 I-MIBG yielded a higher myocardial uptake and retention than CA 123 I-MIBG but did not result in a major difference in estimated absorbed dose [15].…”