A rural perspective on minimally invasive parathyroidectomy: optimal preoperative imaging and patient outcomes

Our retrospective review of prospectively collected data evaluated the efficacy of minimally invasive parathyroidectomy (MIP) and compared preoperative imaging modalities in a rural referral centre.

Patients with a diagnosis of primary hyperparathyroidism underwent surgeon-performed ultrasound (SUS) and technetium-99 m sestamibi (MIBI). Radiologist-performed ultrasound (RUS) was sought when the diagnosis remained in doubt. Four-dimensional computed tomography (4DCT) first replaced RUS in mid-2014, then MIBI as a frontline modality in 2015. MIP was conducted if possible and bilateral neck exploration (BNE) when localization remained doubtful. Treatment was evaluated by histopathology and serum parathyroid hormone and calcium levels at 6 weeks.

A total of 122 of 165 (73.9%) glands were removed by MIP and 43 of 165 (26.1%) by BNE. Of 15 cases with non-localizing preoperative investigations, one patient had a negative BNE. A total of 160 of 165 (97.0%) patients underwent a successful operation, with five (3.0%) suffering persistent post-operative hypercalcaemia. SUS had a sensitivity of 79.4% (131/165) and a positive predictive value (PPV) of 97.0% (131/135). MIBI had a sensitivity of 60.0% (81/135) and a PPV of 95.3% (81/85). RUS produced a sensitivity of 65.5% (76/116) and PPV of 98.7% (76/77). When used as a second-line modality, 4DCT had a sensitivity of 76.9% (10/13) and PPV of 100%. The sensitivity and PPV were 85.7% (18/21) and 94.7% (18/19) after 4DCT's promotion to first-line use.

MIP can be safely performed in rural centres of adequate volume. We recommend that operations be guided by SUS with routine use of an adjunctive modality. Our study has seen 4DCT replace MIBI in this regard.