Optimization of parathyroid 11C-choline PET protocol for localization of parathyroid adenomas in patients with primary hyperparathyroidism

Abstract

Purpose To evaluate the optimal tracer uptake time, the minimal amount of radioactivity and the inter-observer agreement for 11 C-choline positron emission tomography/computed tomography (PET/CT) in patients with primary hyperparathyroidism (pHPT). Methods Twenty-one patients with biochemically proven pHPT were retrospectively studied after injection of 6.3 ± 1.2 MBq/kg 11 C-choline. PET data of the first nine patients, scanned for up to 60 min, were reconstructed in 10-min frames from 10- to 60-min postinjection (p.i.), mimicking varying 11 C-choline uptake times. Parathyroid adenoma to background contrast ratios were calculated and compared, using standardized uptake values (SUVs). Data was reconstructed with varying scan durations (1, 2.5, 5, and 10 min) at 20–30-min p.i. (established optimal uptake time), mimicking less administered radioactivity. To establish the minimal required radioactivity, the SUVs in the shorter scan durations (1, 2.5, and 5 min) were compared to the 10-min scan duration to determine whether increased variability and/or statistical differences were observed. Four observers analyzed the 11 C-choline PET/CT in four randomized rounds for all patients. Results SUVpeak of the adenoma decreased from 30 to 40 p.i. onwards. All adenoma/background contrast ratios did not differ from 20- to 30-min p.i. onwards. The SUVs of adenoma in the scan duration of 1, 2.5, and 5 min all differed significantly from the same SUV in the 10-min scan duration (all p = 0.012). However, the difference in absolute SUV adenoma values was well below 10% and therefore not considered clinically significant. The inter-observer analysis showed that the Fleiss’ kappa of the 1-min scan were classified as “moderate,” while these values were classified as “good” in the 2.5-, 5-, and 10-min scan duration. Observers scored lower certainty scores in the 1- and 2.5-min scans compared to the 5- and 10-min scan durations. Conclusion The optimal time to start PET/CT scanning in patients with pHPT is 20 min after mean injection of 6.3 MBq/kg 11 C-choline, with a recommended scan duration of at least 5 min. Alternatively, the radioactivity dose can be lowered by 50% while keeping a 10-min scan duration without losing the accuracy of 11 C-choline PET/CT interpretation. Electronic supplementary material The online version of this article (10.1186/s13550-019-0534-5) contains supplementary material, which is available to authorized users.

11C-Choline PET/CT vs. 99mTc-MIBI/123Iodide Subtraction SPECT/CT for Preoperative Detection of Abnormal Parathyroid Glands in Primary Hyperparathyroidism: A Prospective, Single-Centre Clinical Trial in 60 Patients

“…Most studies on choline PET in the detection of hyperfunctioning parathyroid glands use fluorine-18 rather than carbon-11 although others have used 11 C-Choline [ 8 , 18 , 19 , 20 , 21 ]. However, there is presumably no difference between the two tracers [ 21 ].…”

A retrospective analysis of the diagnostic performance of 11C-choline PET/CT for detection of hyperfunctioning parathyroid glands after prior negative or discordant imaging in primary hyperparathyroidism

“…11 C-choline PET/CT was performed as described previously by Noltes et al [ 19 ]. In short; patients had to fast for six hours while drinking one liter of water, tea or coffee without milk and sugar prior to the PET/CT procedure.…”

“…In the first five patients, PET/ CT images were taken directly after injection of a median dose of 556 MBq (range 510-635 MBq) 11 C-choline until 40 to 60 min postinjection. After optimizing our imaging protocol [19], all subsequent patients were scanned dynamically 20 min after injection of a median dose of 410 MBq (range 360-440 MBq) for 10 min. All images were iteratively reconstructed using three iterations, 21 subsets with 5 mm FWHM Gaussian filter, including time of flight and resolution modelling.…”

“…Only three studies have investigated the accuracy of 11 C-choline PET/CT showing a sensitivity of 87%, 92% and 99%, of which two studies also included patients with positive 99m Tc-MIBI scans [16][17][18]. Furthermore, we have recently optimized the imaging protocol of 11 C-choline PET/CT for the detection of parathyroid adenomas [19].…”

Diagnostic Value of Choline PET in the Preoperative Localization of Hyperfunctioning Parathyroid Gland(s): A Comprehensive Overview

“…Noltes et al set the optimal tracer uptake time at 20 min post-injection because adenoma choline uptake remains constant from 20 min onwards. Moreover, the same authors suggested a median administered dose of 6.3 MBq/kg and a scanning time for at least 5 min for [ 11 C]Choline PET/CT [34].…”