Differences between 99mTc-sestamibi and 99mTc-tetrofosmin uptake in thyroid and salivary glands: comparison with 99mTc-pertechnetate in 86 subjects.

Tc-tetrofosmin seems to show a prolonged thyroid retention when compared with Tc-sestamibi; this may explain its poorer performance in the dual-phase parathyroid scintigraphy. In order to verify objectively whether and to what extent Tc-sestamibi and Tc-tetrofosmin uptake and retention differ in the thyroid gland, we performed a head-to-head comparison between the tracers in 86 euthyroid subjects enrolled in five centres. Data were compared with those of Tc-pertechnetate obtained from the same subjects. For comparison purposes, quantitative data from the salivary glands were also obtained. Tc-sestamibi showed a higher early thyroid uptake (2.26+/-0.52 vs. 2.01+/-0.49, respectively; P<0.002) and a lower retention (1.4+/-0.37 vs. 1.65+/-0.58, respectively; P<0.002) when compared with Tc-tetrofosmin. This finding provides an objective basis for the poorer results of Tc-tetrofosmin in dual-phase parathyroid scintigraphy. Delayed Tc-tetrofosmin salivary gland uptake was unexpectedly high and approached the Tc-pertechnetate value (2.29+/-0.56 vs. 2.46+/-0.75, respectively; P =not significant). This finding should be kept in mind in order to avoid interpretation pitfalls in thyroid and parathyroid imaging with Tc-tetrofosmin, as well as in other oncological imaging of the neck region. This study definitely establishes that Tc-tetrofosmin and Tc-sestamibi are not twin but rather sibling tracers.

[Carcinoid of the appendix. A case report]. / Il carcinoide dell'appendice. Caso clinico.

A case of a young male operated on for acute appendicitis due to a carcinoid of the base is reported. Since the tumor was infiltrating the resection margin of the appendix, the patient was later treated with a right hemicolectomy. Carcinoid tumor is unusual, but can be encountered several times during the career of a surgeon (1/200-300 appendicectomy). The tumor is more frequent in women (2-4:1), located at the tip of the appendix (62-78%) and has a diameter less than 1 cm in 70-95% of cases. It is more frequently diagnosed incidentally after an operation for acute appendicitis and occasionally during other procedures (colectomy, cholecystectomy, salpingectomy). Liver metastases are rare (< 2%), related to the dimension of the primitive tumor (21-100% when > 2 cm) and can cause a "carcinoid syndrome": flush, diarrhea bronchoconstriction, cardiac valve disease. Diagnosis is made by the pathologist and staging by conventional radiologic procedures (TAC, US), dosage of neuroendocrine mediators such as 24 hours urinary 5-HIAA. Nowadays 111In-octreotide scintigraphy (SRS) has an 86% sensitivity to detect the carcinoid and is useful for staging and for planning a surgical intervention. Simple appendectomy is adequate treatment for appendiceal carcinoids less than 1 cm in diameter. Adequate treatment for tumors greater than 2 cm is right hemicolectomy. A point of controversy is what to do for tumors in the 1 to 2 cm range. It seems that appendectomy alone is sufficient except in those cases when mesoappendiceal invasion is identified. When surgical margins after appendectomy are not free of tumor, additional surgery seems warranted. Carcinoid tumor of the appendix has a good prognosis with a 5-year-survival rate, of 85.9-100%. When liver metastases are encountered octreotide can relieve symptoms and sometimes the progression of the disease.

Quantitative comparison of technetium-99m tetrofosmin and thallium-201 images of the thyroid and abnormal parathyroid glands.

The aim of the study was to quantitatively compare the scintigraphic images of the thyroid and abnormal parathyroid glands obtained with technetium-99m tetrofosmin and thallium-201 in patients with hyperparathyroidism. Forty-six patients with hyperparathyroidism underwent (201)Tl (74 MBq), (99m)Tc-pertechnetate (74 MBq) and (99m)Tc-tetrofosmin (555-740 MBq) scintigraphy in a single session. Image analysis included the computation of the thyroid/background ratio in the whole study population and the parathyroid/background ratio, parathyroid/thyroid ratio and diagnostic sensitivity in 17 patients who underwent parathyroid surgery. The pertechnetate subtraction technique was used. (201)Tl and (99m)Tc-tetrofosmin showed a similar thyroid/background ratio (1.79+/-0.41 and 1.81+/-0. 47, respectively, P=NS); however, (99m)Tc-tetrofosmin showed a higher parathyroid/background ratio than (201)Tl (2.06+/-0.54 vs 1. 79+/- 0.50, P=0.007). Despite the superior quality of (99m)Tc-tetrofosmin images, both tracers showed identical sensitivity in detecting enlarged parathyroid glands in patients with primary hyperparathyroidism (89%) and in those with secondary hyperparathyroidism (50%).

Parathyroid imaging with 99Tcm-tetrofosmin.

The aim of this study was to evaluate whether 99Tcm-tetrofosmin is a suitable agent for parathyroid scintigraphy. Ten patients with hyperparathyroidism and two normal subjects underwent parathyroid scintigraphy with both 99Tcm-tetrofosmin and 201TI. Thyroid image subtraction was performed with 99Tcm-pertechnetate. In the 10 patients with hyperparathyroidism, the scintigraphic results were compared with the surgical findings, which showed seven parathyroid adenomas, two parathyroid adenomas with a co-existing thyroid adenoma, and one thyroid carcinoma. Both 99Tcm-tetrofosmin and 201T1 revealed eight true-positive results, one false-negative results and one false-positive result, with concordance in 8 of 10 patients. The image quality with 99Tcm-tetrofosmin of both the raw and 99Tcm-pertechnetate subtracted images was always superior compared with that with 201T1. On the basis of the diagnostic results and the favourable dosimetric characteristics, we conclude that 99Tcm-tetrofosmin is a suitable agent for parathyroid scintigraphy.