Comparison of biochemical markers and technetium 99m methoxyisobutylisonitrile imaging in primary and secondary hyperparathyroidism

OBJECTIVE

To investigate the differences in biochemical marker levels and the extent of lesion visualization on technetium 99m methoxyisobutylisonitrile (^99mTc-MIBI) imaging between primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism (SHPT).

METHODS

Nineteen patients with PHPT and 14 patients with SHPT were enrolled in the study, all of whom underwent routine ^99mTc-MIBI dual-phase planar imaging, single-photon emission computed tomography combined with computed tomography (SPECT/CT fusion) imaging, and serum biochemical and hormonal investigations prior to surgery. The target-to-non-target (T/NT) ratios were calculated based on images from the early and delayed phases of ^99mTc-MIBI planar imaging and also based on SPECT/CT fusion imaging. The volume of the parathyroid glands was measured following their excision.

RESULTS

A total of 62 parathyroid glands were removed: 14 parathyroid adenomas and five parathyroid carcinomas in PHPT patients; and 18 parathyroid adenomas, 17 parathyroid hyperplasia lesions, and eight instances of nodular hyperplasia with adenoma in SHPT patients. The median volume of the lesions in PHPT and SHPT was 1.69 cm³ and 0.52 cm³ respectively, and the difference between them was statistically significant (P = 0.001). The median T/NT ratios calculated at the early phase of ^99mTc-MIBI planar imaging, the delayed phase of ^99mTc-MIBI planar imaging, and the subsequent SPECT/CT fusion imaging were 1.51, 1.34, and 2.75, respectively, in PHPT, and 1.46, 1.30, and 1.38, in SHPT, respectively. The T/NT ratio difference between PHPT and SHPT on the SPECT/CT fusion imaging was statistically significant (P = 0.002). The histopathology subtypes of the lesions were associated with significant differences in two areas: the T/NT ratios on the SPECT/CT fusion imaging and the volume of the lesions (P=0.002, P<0.001).

CONCLUSION

The proportion of positive findings on ^99mTc-MIBI dual-phase planar imaging and the T/NT ratios of ^99mTc-MIBI SPECT/CT fusion imaging were higher in PHPT than in SHPT. The volume of parathyroid lesions in SHPT was smaller than in PHPT.

Inter- and Intraobserver Repeatability of Myocardial Flow Reserve Values Determined with SPECT Study Using a Discovery NM530c Camera and Corridor 4DM Software

BACKGROUND

Myocardial blood flow (MBF) and flow reserve (MFR) examination, especially useful in the diagnosis of multivessel coronary artery disease (CAD), can be assessed with a cadmium-zinc-telluride (CZT) SPECT gamma camera, as an alternative to the expensive and less available PET. However, study processing is not free from subjective factors. Therefore, this paper aims to evaluate intra- and interobserver repeatability of MBF and MFR values obtained by the same operator and two independent operators.

METHODS

This study included 57 adult patients. MBF and MFR were assessed using a Discovery NM530c camera in a two-day, rest/dipyridamople protocol, using ^99mTc-MIBI. Data were processed using Corridor4DM software, twice by one operator and once by another operator.

RESULTS

The repeatability of the assessed values was quite good in the whole myocardium, LAD and LCX vascular territories, but was poor in the RCA territory.

CONCLUSIONS

The poor repeatability of MBF and MFR in RCA vascular territory can be explained by poor automatic orientation of the heart axis during post-processing and a so-called "cardiac creep" phenomenon. Better automatic heart orientation and introduction of automatic motion correction is likely to drastically improve this repeatability. In the present state of the software, PET is better for patients requiring assessment of MFR in the RCA territory.

Gestational Primary Hyperparathyroidism Due to Ectopic Parathyroid Adenoma: Case Report and Literature Review

Gestational primary hyperparathyroidism (GPHPT) is a rare condition with fewer than 200 cases reported. We present the case of a 21-year-old woman who presented at 10 weeks’ gestation with severe hypercalcemia. Laboratory investigation was consistent with primary hyperparathyroidism. Neck ultrasound did not reveal any parathyroid enlargement. Due to the persistence of severe hypercalcemia, she was treated with 4 weeks of cinacalcet therapy, which was poorly tolerated due to nausea and vomiting. At 14 weeks’ gestation, she underwent neck exploration with right lower, left upper, and partial right upper parathyroid gland excision. Intra- and postoperative parathyroid hormone (PTH) and calcium levels remained elevated. After a thorough discussion of risks/benefits, the patient requested further treatment. A parathyroid sestamibi scan (PSS) revealed an ectopic adenoma in the left mediastinum. The adenoma was removed via video-assisted thorascopic parathyroidectomy with intraoperative PTH declining to nearly undetectable levels. She ultimately delivered a physically and developmentally normal infant at 37 weeks’ gestation.

Appropriate treatment of severe GPHPT may prevent the maternal and fetal complications of hypercalcemia. This case, in which cinacalcet therapy and PSS were used, adds to the body of literature regarding treatment of severe GPHPT.

The contributions of gamma probe to lesion detectability and surgical safety in recurrent thyroid cancer at risk

In patients, who underwent thyroid surgery or treated with I-131 radioiodine previously for differentiated thyroid cancer, a second surgical intervention carries higher risks due to distortion of the natural anatomy and development of fibrotic/cicatricial tissue. In addition, accurate assessment of current status about extent of the disease is important in terms of success of the surgery. In this case report, we present the positive contribution of intraoperative gamma probe used for lesion detectability and for surgical safety in a patient operated for several times and administered high cumulative dose of radioiodine therapy for diffentiated thyroid carcinoma previously.

Conflict of interest:None declared.

Incidental detection of a benign thymoma on Tc-99m MIBI myocardial perfusion study

Technetium-99m methoxy-isobutylisonitrile (Tc-99m MIBI) is a routinely used radiopharmaceutical for myocardial perfusion scintigraphy (MPS). It is also a tumor seeking agent. Here, we present a case of 51 year old male who underwent Tc-99m MIBI myocardial perfusion study due to permanent chest pain after coronary angiography. Abnormal MIBI uptake in the thorax was detected in the raw images. This single finding led to further investigation and thoracotomy proved that the lesion was benign thymoma. Thymomas are often asymptomatic or have a non-specific presentation. They are often detected coincidentally on images performed for any other reasons. We wanted to emphasize that during of MPS, the raw data should always be reviewed as occasionally valuable additional information on noncardiac pathology could be recognized by extracardiac uptake, as in this case.

Conflict of interest:None declared.