A comparative study of pre-operative imaging methods in patients with primary hyperparathyroidism: ultrasonography, 99mTc sestamibi, single photon emission computed tomography, and magnetic resonance imaging.

AIM: This study compares the accuracy rates achieved in ultrasonography (US), 99mTc-sestamibi (MIBI), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) as imaging methods used in the pre-operative localization of the enlarged parathyroid glands. SUBJECTS AND METHODS: For the purposes of this study, US, MIBI, SPECT, and MRI were performed on 98 patients with primary hyperparathyroidism (pHPT). All patients underwent parathyroidectomy. RESULTS: Pre-operative localization of an abnormal parathyroid gland was successfully performed in 82 of the cases scanned with US (83.7%), while the result was 66 in the cases scanned with MIBI (67.3%), 71 of the cases were successfully localized with SPECT (72.4%), while MRI revealed the diseased gland in only 60 of the total cases (61.2%). In MIBI-positive and -negative patients there was a statistically significant difference among cases in terms of adenoma volume (1.30±1.51 vs 0.58±0.91, p<0.05). Sensitivity, specificity and diagnostic accuracy values were 87.2%, 25.0%, and 83.0%; 70.2%, 50.0%, and 69.4%; 75.5%, 50.0%, and 74.5%; 63.8%, 50.0%, and 63.3% for US, MIBI, SPECT, and MRI, respectively. The respective values for sensitivity, specificity, and diagnostic accuracy were 94.9%, 25.0%, and 91.1% when US was combined with MIBI. CONCLUSIONS: Combining US and MIBI as imaging methods for pre-operative imaging of pHPT often produces more satisfactory results. While the accuracy of US is relatively low in the ectopic localizations, the size of the lesion can be an important factor in the accuracy achieved with MIBI.

Somatotropin adenoma and resistance to thyroid hormone.

Resistance to thyroid hormone (RTH) is a rare disease characterized by non-suppressed TSH in spite of high free thyroid hormone levels. Up to date, in the literature, there are more than 600 RTH cases, but co-incidental hypophyseal adenoma was reported in only 1 case. In the literature, despite reported cases with thyrotropinoma accompanying RTH, we could not find a case with somatotropinoma accompanying RTH. Here, we report a 34-yr-old male patient, who was admitted to the hospital with complaints of dyspnea, chest pain, and palpitation in 2003. His alpha- subunit value was normal and the alpha-subunit/TSH molar ratio was <1. His response to TRH stimulation test was normal. His TSH level was suppressed in the T3 suppression test. Hypophyseal magnetic resonance imaging showed a 6-mm hypophyseal microadenoma. Levels of all anterior hypophyseal hormones, including GH and IGF-I, were normal. Oral glucose tolerance test (OGTT)-GH suppression test was normal. The patient was followed with the diagnosis of RTH and incidental hypophyseal adenoma. After 3 yr, because of high levels of IGF-I: 901 ng/ml (68-324), the OGTT-GH suppression test was reported and no suppression was detected. Thus, the patient was referred to surgery with the pre-diagnosis of RTH and acromegaly. Immunohistochemistry was showed as strong GH staining with low Ki 67 index while TSH and other anterior hypophyseal hormones stainings were negative. Post-operative thyroid hormones were still high.