Factors affecting the sensitivity of Tc-99m methoxyisobutylisonitrile dual-phase parathyroid single photon emission computed tomography in primary hyperparathyroidism

Update in imaging tests used for the localization of parathyroid pathology

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

Semiquantitative assessment of 99mTc-MIBI uptake in parathyroids of secondary hyperparathyroidism patients with chronic renal failure

OBJECTIVE

To explore the valuably influential factors and improve the diagnostic accuracy and efficiency of ^99mTc-methoxyisobutylisonitrile (MIBI) uptake in parathyroids of secondary hyperparathyroidism (SHPT) patients with chronic renal failure (CRF).

METHODS

The correlation analysis was performed between clinical indices related to CRF and ^99mTc-MIBI uptake intensity TBR (the gray value mean ratio between the parathyroid target and the bilateral neck background, semiquantitatively calculated with ImageJ software). All clinical indices and TBRs were compared by a three- or two-level grouping method of MIBI uptake, which was visually qualitatively assessed. The three-level grouping method comprised slight, medium, and high groups with little, faint, and distinct MIBI concentration in parathyroids, respectively. The two-level grouping method comprised insignificant and significant groups with TBR greater than or less than 0.49-0.71, respectively.

RESULTS

MIBI uptake was significantly positively related to patient age, CRF course, hemodialysis vintage, serum parathyroid hormone (PTH), and alkaline phosphatase (AKP) but was significantly negatively related to serum uric acid (UA). MIBI washout was significantly positively related to patient age but was significantly negatively related to serum phosphorus (P) and calcium (Ca) × P. Oral administration of calcitriol and calcium could significantly reduce the MIBI uptake. MIBI uptake tendency might alter. Such seven indices, namely the MIBI uptake, CRF course, hemodialysis vintage, serum AKP, calcium, cysteine proteinase inhibitor C, and PTH, were comparable between the slight and medium groups but were significantly different between the slight and high groups or between the medium and high groups. The above seven indices plus blood urea nitrogen/creatinine were all significantly different between the insignificant and significant groups. All above significances were with P < 0.05.

CONCLUSIONS

Patient age, CRF course, hemodialysis vintage, serum PTH, AKP, UA, phosphorus, Ca × P, oral administration of calcitriol and calcium, and parathyroids themselves can significantly influence MIBI uptake in parathyroids of SHPT patients with CRF. The two-level grouping method of MIBI intensity should be adopted to qualitatively diagnose the MIBI uptake.

[Preoperative diagnostic value of 99mTc- MIBI SPECT/CT imaging combined with semiquantitative analysis in hyperparathyroidism and factors affecting its efficacy]

OBJECTIVE

To evaluate the diagnostic efficacy of technetium-99m methoxyisobutylisonitrile single photon emission/ computed tomography (^99mTc- MIBI SPECT/CT), ^99mTc- MIBI double- phase scintigraphy (DPS) DPS and ultrasound (US) in preoperative localization of hyperparathyroidism (HPT) and explore the factors affecting the diagnostic efficacy of ^99mTc-MIBI SPECT/CT.

METHODS

We retrospectively analyzed the data of 104 patients with HPT undergoing surgical resection between January, 2015 and July, 2019. Preoperative ^99mTc-MIBI imaging was performed in all the patients, and 82 patients also received US examination preoperatively. Semi-quantitative analysis was used to draw the region of interest and calculate the lesion/ ipsilateral deltoid muscle (T/NT) uptake ratio. The sensitivity and detection performance of ^99mTc-MIBI SPECT/CT, DPS and US in the diagnosis of HPT patients were compared, and the correlations of the T/NT ratios of parathyroid adenoma (PA) and parathyroid hyperplasia (PH) with the expression levels of COX-2 and Bcl-2 were analyzed.

RESULTS

The diagnostic sensitivity of ^99mTc- MIBI SPECT/CT, DPS and US for HPT was 95.19% (99/104), 91.3% (95/104) and 81.71% (67/82), respectively, demonstrating a significantly higher diagnostic sensitivity of ^99mTc-MIBI SPECT/CT than US (χ²=9.59, P=0.008). For PH lesions, ^99mTc-MIBI SPECT/CT had the highest diagnostic sensitivity, followed by DPS and then by US (P < 0.05), but their sensitivity did not differ significantly for PA (P>0.05). The T/NT ratio in fatty hyperplastic glands was significantly lower than that in fat-free hyperplastic glands (P=0.009). In PA, Bcl-2 expression was significantly lower in false negative lesions than in true positive lesions (P=0.046), but Cox-2 expression did not show such a difference (P>0.05). In PH lesions, the expressions of Bcl-2 and Cox- 2 did not differ significantly between false negative than true positive lesions (P>0.05).

CONCLUSIONS

^99mTc-MIBI SPECT/CT has a high sensitivity for HPT localization, and the T/NT ratio is positively correlated with the lesion volume. An increased expression of Bcl-2 in PA lesions and a decreased cell fat content in PH lesions can facilitate the detection of HPT glands by ^99mTc-MIBI SPECT/CT.

Causes of false negatives in technetium-99 m methoxyisobutylisonitrile scintigraphy for hyperparathyroidism: influence of size and cysts in parathyroid lesions

OBJECTIVE

The aim of this study was to elucidate the causes of false-negative cases of technetium-99 m methoxyisobutylisonitrile scintigraphy (MIBI) for hyperparathyroidism.

METHODS

Consecutive MIBI examinations performed in 154 patients between April 2011 and March 2017 were retrospectively reviewed. Sensitivities of MIBI, CT and US were calculated. The effects of serum calcium, phosphorus, PTH, weight of parathyroid lesions, use of NSAIDs and Ca-channel blocker (CCB), presence of cyst in parathyroid lesions, and a number of lesions observed by MIBI were investigated.

RESULTS

Seventy-nine patients (21 men and 58 women), ranging from 18 to 88 years of age (mean ± SD: 57.6 ± 15.3 years), who underwent parathyroidectomy, were included. MIBI and preoperative US were performed in the 79 patients and single-phase parenchymal contrast-enhanced CT (CE-CT) was performed in 55 patients. A total of 120 parathyroid proliferative nodules were detected by MIBI and US, and 92 lesions were detected by CE-CT. In the lesion base, MIBI detected 82 out of the 120 lesions (sensitivity = 68.3%), US detected 103 out of the 120 lesions (sensitivity = 85.8%), CE-CT detected 63 out of the 92 lesions (sensitivity = 68.5%), and MIBI plus CE-CT detected 72 of the 92 lesions (sensitivity = 78.3%). A significant difference in the sensitivity was found between US and MIBI (P < 0.01), and between US and CT (P < 0.01). In the patient base, MIBI detected 67 out of the 79 patients (sensitivity = 84.8%), US detected 74 out of the 79 patients (sensitivity = 93.7%), CE-CT detected 45 out of the 55 patients (sensitivity = 81.8%), and MIBI plus CE-CT detected 52 out of the 55 patients (sensitivity = 94.5%). No significant difference was observed in any of the comparisons. A significant difference was observed in lesion weight (P < 0.01), single or multiple lesions (P = 0.02), and presence of cyst (P < 0.01) between the MIBI false-negative (n = 38) and the true-positive groups (n = 82).

CONCLUSION

The presence of cyst in parathyroid proliferative lesions as well as small size and multiple number of parathyroid lesions contribute to false negative in parathyroid MIBI scan.

Parathyroid scintigraphy in primary hyperparathyroidism: comparison between double-phase and subtraction techniques and possible affecting factors

PURPOSE

Parathyroid scintigraphy is superior to other imaging techniques in detecting hyperfunctioning parathyroid glands. It is mainly performed using double-phase or dual-tracer subtraction methods. Neither of the techniques is perfect and different protocols are being used. We aimed to evaluate the accuracy of double-phase and subtraction methods in detecting abnormal gland as well as the potential effects of coexisting thyroid disease and clinical-laboratory data.

METHODS

We considered patients with primary hyperparathyroidism who underwent parathyroid surgery, after a parathyroid scintigraphy between April 2015 and February 2017. Sixty-eight patients were included; in 45 cases (66.2%), a thyroid disease was coexistent. Diagnostic performances of the two techniques were compared. The effect of thyroid disease and clinical-pathological data on examination interpretation was considered.

RESULTS

Double-phase scintigraphy showed higher sensitivity and accuracy in detecting the exact abnormal gland compared to the digital subtraction (90% and 75% vs. 76% and 66%, respectively). For double-phase technique, sensitivity and accuracy were higher in cases with no thyroid disease when compared to those with thyroid disease (92% and 86% vs. 88% and 69%, respectively). Similarly, for digital subtraction, sensitivity and accuracy were higher in the absence of thyroid disease compared to their presence (84% and 79% vs. 70% and 58%, respectively). There was no significant variation in the performance of both techniques, considering clinical-laboratory data.

CONCLUSIONS

Double-phase scintigraphy has been more accurate than digital subtraction. The presence of thyroid disease could be a possible limit, affecting the subtraction more than the double-phase technique. Clinical data did not influence the scintigraphic outcome.

PRE-OPERATIVE LOCALIZATION OF PARATHYROID ADENOMA: PERFORMANCE OF 4D MRI PARATHYROID PROTOCOL

Objective: Accurate pre-operative image localization is critical in the selection of minimally invasive parathyroidectomy as a surgical treatment approach in patients with primary hyperparathyroidism (PHPT). Sestamibi scan, ultrasound, computed tomography, and conventional magnetic resonance imaging (MRI) has varying accuracy in localizing parathyroid adenoma (PTA). Our group has previously shown that four-dimensional (4D) MRI is more accurate than conventional imaging in identifying single adenomas. In this study, we set out to determine if it is possible to accurately localize the quadrant of the adenoma using 4D MRI. Methods: We analyzed and matched the quadrants of PTA identified by pre-operative 4D-MRI with the operative findings during parathyroidectomy for PHPT at our institution during the study period. All resections were confirmed to be successful with an adequate decrease in intraoperative parathyroid hormone as defined by the Miami criterion. Results: A total of 26 patients with PHPT underwent pre-operative localization with the 4D MRI parathyroid protocol. Fourteen patients had true single-gland adenoma (SGA) and 12 patients had multi-gland disease (MGD). 4D MRI accurately identified all the SGA. Using this method, we were also able to localize the adenoma in the correct quadrant in 14 of the 18 patients with SGA. All 3 double adenomas were accurately identified using 4D MRI; however, MGD was only accurately identified 67% of the time. The 4D MRI had an overall 85% accuracy in distinguishing SGA from MGD. Conclusion: 4D MRI accurately identified single and double adenomas in their respective quadrants. However, accuracy was lower with MGD. Abbreviations: BNE = bilateral neck exploration; CT = computed tomography; IOPTH = intra-operative parathyroid hormone; MGD = multi-gland disease; MIBI = sestamibi; MIP = minimally invasive parathyroidectomy; MRI = magnetic resonance imaging; PHPT = primary hyperparathyroidism; PTA = parathyroid adenoma; PTH = parathyroid hormone; SGA = single-gland adenoma; SPECT = single photon emission computed tomography; 4D = four-dimensional.

Dual-phase 99mTc-MIBI imaging and the expressions of P-gp, GST-π, and MRP1 in hyperparathyroidism

Objective

The aim of this study was to further elucidate the mechanisms of dual-phase technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) parathyroid imaging by exploring the association between early uptake results (EUR), delayed uptake results (DUR), and the retention index (RI) in dual-phase ^99mTc-MIBI parathyroid imaging and P glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and glutathione S-transferase-π (GST-π) expression in hyperparathyroidism (HPT).

Patients and methods

Preoperative dual-phase (early and delayed) ^99mTc-MIBI imaging was performed on 74 patients undergoing parathyroidectomy for HPT. EUR, DUR, and RI were calculated. P-gp, MRP1, and GST-π expressions were assessed using immunohistochemistry in resected tissue from HPT and control patients. The association between P-gp, MRP1, and GST-π expressions and EUR, DUR, and RI in HPT was evaluated.

Results

The positive rate of dual-phase ^99mT c-MIBI imaging was 91.89% (68/74) and the false-negative rate was 8.11% (6/74). P-gp and GST-π expressions were higher in tissues resected from control compared with HPT patients (47.37 and 81.5%, P<0.05); there was no difference in MRP1. EUR were associated with P-gp and GST-π expressions, and DUR were associated with MRP1 expression. There was a significant difference in MRP1 expression between RI greater than or equal to 0 and RI less than 0. There was no relationship between the sensitivity of dual-phase ^99mTc-MIBI imaging and P-gp, MRP1, and GST-π expressions in resected parathyroid tissue. The six false-negative HPT cases consisted of three P-gp (−)/MRP1 (−) tissues, three P-gp (−)/GST-π (−) tissues, and four MRP1 (−)/GST-π (−) tissues.

Conclusion

As P-gp and GST-π expressions were higher in tissues resected from control compared with HPT patients, ^99mTc-MIBI may wash out faster from normal parathyroid tissue surrounding the lesion compared with the lesion itself, facilitating detection.

Biochemical and pathologic factors affecting technetium-99m-methoxyisobutylisonitrile imaging results in patients with primary hyperparathyroidism

OBJECTIVE

Technetium 99 m methoxyisobutylisonitrile (Tc-99m MIBI) scintigraphy represents the most commonly utilized imaging modality for the detection of the diseased gland in patients with primary hyperparathyroidism (PHPT). In this study, we aimed to identify potential biological factors with an impact on MIBI sensitivity.

METHODS

A total of 147 patients with surgically confirmed parathyroid adenomas were assessed retrospectively. Data including medical history, biochemical and hormonal measurements, cervical US, Tc-99m MIBI scans as well as pathology reports were retrieved and recorded.

RESULTS

Of the 147 patients, there were a total of 77, 39, and 31 cases with a positive, negative, and suspicious parathyroid adenoma on Tc-99m MIBI scan, respectively. Serum calcium (Ca), parathyroid hormone (PTH) and 25 (OH) D levels were comparable among MIBI positive and negative patients [Ca: 11.5 ± 0.9 vs 11.3 ± 0.9 mg/dL (P = 0.42); PTH: 216 (146-347) vs 194 (140-317) pg/mL (P = 0.45); 25(OH)D: 8.4 (5.7-18.2) vs 10.0 (4.7-23.3) ng/mL (P = 0.64), respectively]. P-glycoprotein (P-gp) staining was negative in both groups. Also, pathological examination of tissue preparations revealed no difference in terms of the volume of the adenomas, incidence of cystic adenomas, cell-type dominance (oxyphilic cell), percent fat, and Ki-67 ratio in MIBI positive and negative groups. The rate of hyalinization was 13% in MIBI positive and 28% in MIBI negative subjects, the difference being statistically significant (P = 0.04).

CONCLUSION

Presence of hyalinization in parathyroid adenomas was found to be negatively correlated with MIBI scan results.