Precision Imaging Triumphs: FCH PET/CT Outshines MIBI SPECT/CT in Parathyroidectomy Outcomes in new study

The study, published in JAMA Otolaryngology – Head & Neck Surgery, revealed that F-18 fluorocholine (FCH) PET/CT could be a first-line technique over technetium-99m sestamibi (Tc-99m MIBI) SPECT/CT for imaging parathyroid tumors before surgery.

“In the diagnostic randomized clinical trial involving 57 evaluable patients, achieving normocalcemia one month after initial positive imaging-guided minimally invasive parathyroidectomy (MIP) was more common following FCH PET/CT imaging as the first-line approach compared to MIBI SPECT/CT imaging,” the researchers reported.

Primary hyperparathyroidism, characterized by excessive production of parathyroid hormone, can lead to elevated calcium levels and various symptoms such as bone pain, kidney stones, and fatigue. Traditionally, surgeons relied on ultrasound and sestamibi scans for preoperative localization of parathyroid adenomas or hyperplasia. However, these methods are not always effective, leading to challenges during surgery.

Against the above background, Elske Quak, Department of Nuclear Medicine and Thyroid Unit, Centre François Baclesse, Caen, France, and colleagues aimed to compare first-line FCH PET/CT vs MIBI SPECT/CT for optimal care in PHPT patients requiring parathyroidectomy. They also compared the proportions of patients in whom the first-line imaging method resulted in successful MIP and normalization of calcemia one month after surgery.

For this purpose, the researchers conducted a French multicenter randomized open diagnostic intervention phase 3 trial; enrolling patients from 2019 to 2022 and participating up to 6 months after surgery. The study enrolled adult patients diagnosed with primary hyperparathyroidism (PHPT) who required surgical intervention. Individuals with a history of prior parathyroid surgery or those diagnosed with multiple endocrine neoplasia type 1 (MEN1) were not eligible to participate.

Patients were randomly assigned in equal numbers to undergo either FCH PET/CT (FCH1) or MIBI SPECT/CT (MIBI1) as their initial imaging modality. If the first-line imaging was negative or inconclusive, they subsequently underwent FCH PET/CT (FCH2) after MIBI1 or MIBI SPECT/CT (MIBI2) after FCH1.

All patients underwent surgery under general anesthesia within 12 weeks after their last imaging session. Clinical and biochemical assessments, including serum calcium and parathyroid hormone levels, were conducted at 1 and 6 months post-surgery.

The primary endpoint was defined as achieving a true-positive result in the first-line imaging-guided minimally invasive parathyroidectomy (MIP), alongside serum calcium levels of 2.55 mmol/l or lower one-month post-surgery, aligned with the local upper limit of normal.

The study led to the following findings:

• 57 patients received FCH1 (n = 29) or MIBI1 (n = 28). The mean age of patients was 62.8 years, with 74% female patients. Baseline patient characteristics were similar between groups.
• Normocalcemia was found one month after positive first-line imaging-guided MIP in 85% of patients in the FCH1 group and 56% of patients in the MIBI1 group.
• Sensitivity was 82% and 63% for FCH1 and MIBI1, respectively.
• Follow-up at six months with biochemical measures was available in 43 patients, confirming that all patients with normocalcemia one month after surgery still had it at six months.
• There were no adverse events related to imaging and four adverse events related to surgery.

“First-line FCH PET/CT is a safe and suitable replacement for MIBI SPECT/CT. FCH PET/CT leads more patients with PHPT to correct imaging-guided MIP and normocalcemia compared to MIBI SPECT/CT thanks to its superior sensitivity,” the researchers concluded.

Reference:

Quak E, Lasne-Cardon A, Cavarec M, et al. F18-Choline PET/CT or MIBI SPECT/CT in the Surgical Management of Primary Hyperparathyroidism: A Diagnostic Randomized Clinical Trial. JAMA Otolaryngol Head Neck Surg. Published online June 20, 2024. doi:10.1001/jamaoto.2024.1421