Absence of hepatic activity in lymphoscintigraphy performed with Tc-99m-Nanoscan. Issue 6 (June 2020)

• Record Type: Journal Article
• Authors: Syed, Adeel; Levart, Danielle; Vadrucci, Manuela; Gibson, Victoria; Peters, A. Michael
• Is Part Of: Nuclear medicine communications. Volume 41:Issue 6(2020)
• Publication Date: 2020-06
• Subjects: lymphoscintigraphy -- lymphoedema -- liver -- Tc-99m-Nanocolloid; Nuclear medicine -- Periodicals; 616.07575
• DOI: 10.1097/MNM.0000000000001181
• Languages: English
• ISSNs: 0143-3636

Abstract

Abstract : Introduction: For assessment of lower extremity swelling using lymphoscintigraphy, several nuclear medicine departments in the UK have recently switched from 99m Tc-Nanocoll to 99m Tc-Nanoscan. The aim of the study was to compare quantitative and semiquantitative features of lymphoscintigraphy between these two tracers. Methods: Twenty patients received 99m Tc-Nanocoll and 20 received 99m Tc-Nanoscan either side of the switch-over in our department. Tracers were compared with respect to visualisation of the liver, para-aortic lymph nodes and urine (all graded by consensus from 0 to 3; invisible-to-very prominent); and with respect to ilio-inguinal nodal quantification and ratio of liver-to-summed bilateral ilio-inguinal nodal activity at 120 min postinjection (L/N120). Scans were deemed abnormal when there was lymph diversion through skin or deep system, no activity in ilio-inguinal nodes at 60 min or negligible ilio-inguinal activity (<5%, left plus right) at 120 min. Results: Liver was visualised in 18/20 99m Tc-Nanocoll but only 3/20 99m Tc-Nanoscan scans. Moreover, para-aortic activity was less prominent after 99m Tc-Nanoscan. Urinary activity was more prominent after 99m Tc-Nanocoll. There were 9/20 patients with stomach activity after 99m Tc-Nanocoll compared with 1/20 after 99m Tc-Nanoscan. Urinary and stomach activities correlated. There was an elevated L/N120, and therefore a suspicion of peripheral lympho-venous communication, in the single 99m Tc-Nanoscan patient who displayed prominent hepatic activity. Conclusion: Hepatic activity is the result of accumulation of colloidal degradation products generated in lymph nodes, rather than intact colloid. 99m Tc-Nanoscan gives less hepatic activity than 99m Tc-Nanocoll because it is more resistant to intranodal degradation. Peripheral lymphovenous communication remains a possible alternative route for activity to reach the liver.