Preoperative Scintigraphic and Intraoperative Scintimetric Localization of Parathyroid Adenoma with Cationic Tc-99m Complexes and a Hand-Held Gamma-Probe

Summary

Aim: The aim of our study was to evaluate the possibility of intraoperative scintimetric detection of parathyroid adenomas with Tc-99m labelled tracers for its usefulness in dystopic or ectopic adenomas. Methods: 12 women with biochemically confirmed hyperparathyroidism were included in our study. After injection of 370 MBq Tc-99m tetrofosmin e.g. sestamibi, preoperative scintigraphy (double phase study and SPECT) was performed and T/NT ratios were evaluated for early, delayed and SPECT images. Surgery was performed using a handheld gamma-probe after preoperative injection of 555-925 MBq Tc-99m tetrofosmin e.g. sestamibi. Count rates (cts/10 sec) were measured and used for calculating in situ - and ex situ - T/NT ratios. Results: In 9 out of 12 patients, adenoma could be detected on static images. Mean T/NT ratios for Tc-99m tetrofosmin were 1.29 for early and 1.23 for delayed images, respectively 1.39 and 1.23 for early and delayed Tc-99m sestamibi scan. Three cases could only be detected with SPECT reconstruction. 11 of 12 parathyroid adenomas could be confirmed intra-operatively. Conclusion: SPECT with Tc-99m labelled cationic complexes showed advantages in detection, precise localization and contrast over static scintigraphy and should therefore be performed at least in cases with poor or no uptake on static images to avoid failures in detection of deeply sited, dislocated glands or adenomas with low uptake. Intraoperative localization and confirmation of parathyroid adenoma with Tc-99m-labelled cationic complexes and a gamma probe is possible and may be useful in case of dys- or ectopic adenoma by influencing surgical approach and operating time.

Zusammenfassung

Ziel: Ziel unserer Untersuchung war es, die Möglichkeit des intraoperativen szintimetrischen Nachweises von NSD-Adenomen mit Tc-99m-markierten Komplexverbindungen für den eventuellen Einsatz bei ektopen NSD-Adenomen zu überprüfen. Methoden: 12 Frauen mit biochemisch gesichertem Hyperparathyroidismus (11 primär und 1 sekundär) wurden in unsere Studie aufgenommen. Die präoperative Lokalisations-diagnostik erfolgte mittels Doppelphasenszintigramm und SPECT nach Injektion von 370 MBq Tc-99m-Tetrofosmin bzw. -Sestamibi, mit anschließender Errechnung von T/NT-Ratios. Die intraoperative Szintimetrie erfolgte mittels einer tragbaren Gammasonde (C-TRAK^®, Carewise Inc., Morgan Hill, CA) nach präoperativer Injektion von 555-925 MBq Tc-99m-Tetrofosmin bzw. -Sestamibi. Mittlere Zählraten (cts/10 sec) wurden gemessen und für die Errechnung von ln-situ- und Ex-situ-T/NT-Raten herangezogen. Ergebnisse: In 9 von 12 Patienten konnte der Lo-kalisationsnachweis bereits auf statischen Aufnahmen erbracht werden, 3 Adenome konnten lediglich mittels SPECT-Rekonstruktion nachgewiesen werden. 11 von 12 Adenomen konnten intraoperativ szintime-trisch lokalisiert werden. Schlußfolgerung: Die intraoperative Lokalisation und Bestätigung von NSD-Adenomen mit kationischen Tc-99m-Komplexen mittels Szintimetrie erscheint möglich und kann die Operationszeit bei ektopen Nebenschilddrüsenadenomen reduzieren.

Keywords

Tc-99m sestamibi - Tc-99m tetrofosmin - SPECT - parathyroid adenoma - parathyroid imaging - intraoperative scintimetry - gamma-probe

Schlüsselwörter

Tc-99m-Sestamibi - Tc-99m-Tetrofosmin - SPECT - Nebenschilddrüsen-adenom - intraoperative Szintimetrie - Gammasonde

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