Use of 99mTc-sestamibi SPECT/CT imaging in predicting the degree of pathological hyperplasia of the parathyroid gland: semi-quantitative analysis.

Background Previous studies have demonstrated that 99mTc-sestamibi (99mTc-MIBI) Single-Photon Emission Computed Tomography/ Computed Tomography (SPECT/CT) imaging is an effective isotopic technique for locating the parathyroid in secondary hyperparathyroidism (SHPT). This study aimed to explore further the correlation between 99mTc-MIBI SPECT/CT imaging and SHPT to demonstrate the value of 99mTc-MIBI SPECT/CT in evaluating the degree of pathological hyperplasia of the parathyroid gland (PG). Methods The demographics, surgical records, and follow-up information of 91 patients were recorded and analyzed. A total of 216 paraffin-embedded PGs of 54 patients were obtained and analyzed. Results Patients with 99mTc-MIBI negative PG(s) had significantly lower preoperative serum phosphorus and higher serum calcium levels at 6 months postoperatively compared to those with 99mTc-MIBI positive PG(s) (P<0.05). We also found a higher total uptake ratio of the region of interest (URRI) and higher URRI max in the hypocalcemia group than in the non-hypocalcemia group. Both URRI total (P=0.003) and URRI max (P=0.028) were independent risk factors for hypocalcemia 6 months postoperatively. The URRI values of the PGs were significantly positively correlated with glandular weight (R2=0.343, P<0.001), glandular volume (R2=0.240, P<0.001), and degree of pathological hyperplasia (P<0.001). However, the URRI value of the PGs exhibited a notably weak correlation with proliferating cell nuclear antigen (PCNA) (R2=0.035, P=0.006). The area under the receiver operating characteristic curve showed a URRI evaluative value of 0.771 for diffuse and nodular types in 216 PGs (P<0.001). We further evaluated 167 nodular-type PGs, distinguishing between nodular hyperplasia and a single nodule; the URRI evaluative value reached 0.819, which was higher than the volume or weight (P<0.001). Conclusions The 99mTc-MIBI SPECT/CT scintigraphy results were related to serum calcium levels at 6 months after total parathyroidectomy with autotransplantation (TPTX+AT), suggesting the occurrence of hypocalcemia (6 months after TPTX+AT). More importantly, this technique effectively evaluated the pathological hyperplasia of PGs preoperatively, and therefore, could assist surgeons in selecting the PGs with the lowest degree of hyperplasia intraoperatively.