The 20% rule: A simple, instantaneous radioactivity measurement defines cure and allows elimination of frozen sections and hormone assays during parathyroidectomy

Role of gamma probes in performing minimally invasive parathyroidectomy in patients with primary hyperparathyroidism: optimization of preoperative and intraoperative procedures

“…Interestingly, Jaskowiak et al (27), proposed a four-point scale to define the probe-guided surgery in a group of 54 patients treated by BNE: the probe was judged crucial in only two patients (4%), helpful in 12 (22%), merely confirmatory in 32 (59%) and not helpful in eight (15%). In contrast, in our experience as well as in that of Norman et al (7,26,28) the probe was helpful in the majority of scan-positive patients and very helpful or even crucial in patients with adenomas located in ectopic sites or deep in the para-tracheal/ para-esophageal space. This difference in judging probe utility could be related, at least in part, to the different surgical approaches utilized: a BNE in Jaskowiak's study (27) while a MIRS in our own study and in Norman's studies (7,26,28).…”

“…In contrast, in our experience as well as in that of Norman et al (7,26,28) the probe was helpful in the majority of scan-positive patients and very helpful or even crucial in patients with adenomas located in ectopic sites or deep in the para-tracheal/ para-esophageal space. This difference in judging probe utility could be related, at least in part, to the different surgical approaches utilized: a BNE in Jaskowiak's study (27) while a MIRS in our own study and in Norman's studies (7,26,28). From this view, it appears reasonable to think that it can be relatively easy for an experienced surgeon to detect a parathyroid adenoma located in an orthotopic site during a BNE simply using the 'eyes'; conversely, it can be difficult, even for an experienced surgeon, to detect a parathyroid adenoma through a 2 cm skin incision without the help of a 'gamma probe': thus, following Jaskowiak's criteria (27) what is judged as 'merely confirmatory' during a BNE could be 'helpful' during a MIRS and what is judged as 'helpful' during a BNE could be 'crucial' during a MIRS.…”

“…Using a middle access, MIRS was successfully performed in 98% of patients in our series. However, it is worth noting that other authors reported similarly good results using a lateral neck access (7,24,26,30). Probably this issue strictly depends on the surgeon's own experience and convenience.…”

“…This discrepancy might be explained, at least in part, by considering the relatively lower sensitivity of the preoperative scintigraphy used by Bonjer et al (31) and Jaskowiak et al (27) (dual-phase technique) in comparison with our scintigraphic procedure (double-tracer technique): sensitivity for detection of parathyroid adenomas was 60 -74% vs 95% respectively. It appears surprising that such different and opposite opinions have been reported in the literature on the role of the gamma probe during parathyroidectomy, ranging from enthusiastic considerations (7,26,28), to less favorable results (16,27), to a judgment of uselessness (32). Some explanations can be made.…”

“…Moreover, in our experience the ex vivo radioactivity counting was higher than 40% in all cases of solitary parathyroid adenoma but also in at least one (dominant) of the enlarged parathyroid glands removed in patients with multi-gland disease. One possible explanation for this discrepancy might be the different timing of MIBI injection and probe measurements: 2-3 h in Norman's protocol (7,26) (18), MIBI reaches the maximum concentration in the parathyroid adenoma within a few minutes from injection; then a slow wash-out is usually observed. Thus, it can be concluded that the '20% rule' is strictly dependent on the type of protocol utilized and can probably only be applied to the Murphy & Norman protocol (26).…”