Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung

Abstract

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean +/- SD: 28.2 +/-6.2 Gy), and 16 patients (group B) had received a higher dose (mean +/- SD: 51.2 +/- 3.5 Gy) at the time of examination. MIBG SPET scans acquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts - delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0. 001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = -0.656; P<0.0001 and r = 0. 387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = -0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes.

Lung-uptake and -washout of MIBG in sarcoidosis

“…6,7,9,22,23 In various conditions, a correlation between I-123 MIBG uptake in the lungs and the development of pulmonary damage has been shown. [24][25][26] In these studies, it was very likely that the damaging process in the lungs was the result of a pathophysiological process that is located in the pulmonary endothelium.…”

Reduced Lung Uptake of Iodine-123 Metaiodobenzylguanidine in Patients with Myeloperoxidase Antineutrophil Cytoplasmic Antibodies-Positive Vasculitis

“…Suga et al [15] found a reduced MIBG lung uptake in irradiated lung fields compared with the uptake in the surrounding area in patients with peripheral types of lung cancer. They speculated that the neuroadrenergic system was impaired in lungs exposed to radiation.…”

“…Slosman et al [11 ]initially evaluated lung uptake of MIBG by using animal models and found a reduction in MIBG lung extraction in bleomycin- and endotoxin [12]-induced endothelial injury. Several clinical studies focusing on the pulmonary uptake of MIBG showed that the lung uptake of MIBG was decreased in patients with chronic obstructive pulmonary disease [14] and patients treated with thoracic radiation [15]. Furthermore, long-term hypoxia as a result of exposure to high altitude caused a significant decrease in lung uptake of MIBG in healthy volunteers [16].…”

Cardiac Autonomic Neuropathy in Patients with Chronic Renal Failure on Hemodialysis

“…The comparison of MIBG with 201 Tl [42]or iodinated human serum albumin [43]demonstrated that pulmonary MIBG uptake may be independent of nonspecific residual lung activity or lung congestion. Moreover, Suga et al [44]have recently reported that MIBG may be a marker of abnormal functional status of the pulmonary neuroadrenergic system produced by irradiation. In patients with CRF, similarly, MIBG may demonstrate pulmonary sympathetic nervous system and/or pulmonary endothelial alterations [45].…”