2014 international guidelines favoured anatomical imaging (AI) for phaeochromocytomas and paragangliomas (PPGL) and suggested low incremental value of [123I]-MIBG in most presentations. Contemporary molecular imaging (MI) has potential diagnostic advantages and data suggest MI can have a positive management impact. We assessed the management impact of MI for individuals with possible or suspected PPGL.
We performed retrospective cohort analysis at a site with continuous access to all relevant PPGL imaging modalities including [18F]-FDOPA, [65Ga]-DOTATATE and [123I]-MIBG. We then completed a pseudoprospective study of individuals undergoing MI for possible or suspected PPGL between 2011-19. Three external reviewers with expertise in PPGL independently appraised de-identified datasets and adjudicated the management impact of scans, graded as high, medium or low impact. Analyses examined factors influencing management impact.
Of all initial MI scans, PPGL was excluded in 48% scans; PPGL was confirmed in 47% scans; while 5% scans were inconclusive. Between 2011-15 and 2016-19, there was a four-fold increased use of [68Ga]-DOTATATE, simultaneous with decreased [123I]-MIBG use. Of 128 scans, 44 (34%) were deemed high impact, 31 (24%) were moderate impact and 53 (41%) were low impact. MI had a high or moderate impact when performed for PPGL confirmation (46/51, 90%), restaging (7/8, 88%), and theranostics (6/6, 100%). A high or moderate impact was infrequently reported across other indications: PPGL staging (4/23, 17%), asymptomatic screening (5/23, 22%), and follow-up of previously treated PPGLs (7/17, 41%).
Management impact of MI performed for PPGL is dependent upon scan indication and modality. In most cases where a solitary PPGL is unambiguous on AI, MI provides low incremental value. In contrast, where there is inconclusive evidence for PPGL on the composite of clinical information, MI has a high or moderate management impact in most cases. This study supports the use of targeted MI in PPGL management.