A comparative study of technetium-99m sestamibi and technetium-99m tetrofosmin single-photon tomography in the detection of nasopharyngeal carcinoma

The value of Tc-99m tetrofosmin in the imaging of pituitary adenomas

AIM

Magnetic resonance imaging (MRI) and computerized tomography (CT) are used in the diagnosis and follow-up of pituitary adenoma cases. Sometimes, these methods cannot display the post-operative residual tissue. It has been shown that some radionuclides were taken up by the pituitary adenomas. The aim of this study was to evaluate the uptake of the technetium-99m (Tc-99m) tetrofosmin (TF) in the pituitary adenoma and normal pituitary tissue and assess the ability of Tc-99m TF to predict tumor malignancy in pituitary gland.

METHODS

The patients with pituitary adenoma (7 invasive and 8 non-invasive) were compared with control group (no. 13). Single-photon emission computed tomography (SPECT) imaging of pituitary gland was performed in both groups. Tc-99m uptake indices were evaluated statistically with the use of Mann-Whitney U test.

RESULTS

The average tetrofosmin uptake index of pituitary adenoma is 2.44+/-1.54 for the patients and 1.69+/-0.71 for the control group. Any significant difference was not observed between the groups (p 0.3). The average index was calculated as 3.04+/-2.15 for invasive adenomas and 1.92+/-0.33 for the non-invasive group, and there was no significant difference between the two groups regarding uptake of the agent (p 0.53). Furthermore, it was determined that the invasive and non-invasive adenomas displayed an uptake of Tc-99m TF similar to normal pituitary tissue.

CONCLUSIONS

Since the pituitary adenoma and normal pituitary tissue gave similar results regarding Tc-99m TF uptake, it was concluded that this agent would not be useful in the diagnosis of pituitary adenoma.

Nuclear medicine imaging for the assessment of primary and recurrent head and neck carcinoma using routinely available tracers

This article reviews the literature on the use of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and thallium-201, technetium-99m sestamibi and technetium-99m tetrofosmin single-photon emission tomography (SPET) for the diagnosis and staging of primary and recurrent squamous cell carcinoma of the head and neck (SCCHN). A search of the MEDLINE and CancerLit databases covering articles entered between 1989 and February 2003 was performed. In the case of FDG PET, only full-ring PET studies that included comparison with conventional morphological imaging were considered. Due to the wide variation in methodology, a straightforward meta-analysis of FDG PET literature was impossible. Instead, indicative summary receiver-operating curves of FDG PET and morphological imaging techniques were generated and a paired comparison of the sensitivities and specificities of FDG PET and morphological imaging performed. Compared with conventional morphological imaging, FDG PET proved as sensitive and specific for the detection of primary SCCHN but more sensitive and specific for the detection of cervical lymph node involvement (CLNI) and recurrence of SCCHN. Additional studies addressing the role of FDG PET in screening for distant metastases and synchronous primary tumours are mandatory. Following negative conventional evaluations, FDG PET identifies occult primary tumours in 20-50% of patients presenting with CLNI. As regards the use of 201Tl, 99mTc-sestamibi and 99mTc-tetrofosmin, more studies are required to define whether these imaging agents could form part of the current diagnostic armamentarium in SCCHN patients. It is concluded that FDG PET either is superior to or offers added value when compared with conventional morphological imaging techniques for the purpose of diagnosis and staging of primary and recurrent SCCHN.

Brain tumor imaging with 99mTc-tetrofosmin: comparison with 201Tl, 99mTc-MIBI, and 18F-fluorodeoxyglucose

The purpose of the present study was to assess the ability of technetium-99m-tetrofosmin (99mTc-TF) to predict tumor malignancy and to compare its uptake with that of thallium-201 (201Tl), technetium-99m-hexakis-2-methoxyisobutyl isonitrile (99mTc-MIBI) and fluorine-18-fluorodeoxyglucose (18F-FDG) in brain tumors. 99mTc-TF single-photon emission computed tomography (SPECT) imaging was performed in 22 patients with brain tumors and 3 healthy controls. Some of the patients underwent 201Tl (n = 12) and 99mTc-MIBI SPECT (n = 14) and 18F-FDG positron emission tomography (PET) (n = 12). The radioactivity ratio of tumor to contralateral normal tissue (T/N) and the ratio of tumor to contralateral white matter (T/WM) were calculated in SPECT and PET images, respectively. In healthy controls, 99mTc-TF uptake was seen only in scalp, in the choroid plexus and pituitary gland, but not in normal cerebral parenchyma. TF T/N in low grade gliomas (2.8+/-0.4) was significantly lower than that in high grade gliomas (22.5+/-29.8) and malignant non-gliomas (8.3+/-2.8) without overlap of values (p = 0.003 and p = 0.014, respectively). TF T/N was significantly correlated with MIBI T/N (p = 0.92, p = 0.001), Tl T/N (p = 0.72, p = 0.017), and FDG T/WM (p = 0.65. p = 0.031). There was an excellent agreement between TF T/N and MIBI T/N values on linear regression analysis (MIBI T/N = -0.63+/-0.97 x TF T/N). These preliminary results indicate that SPECT imaging with 99mTc-TF may be useful for the non-invasive grading of brain tumors. They also suggest that 99mTc-TF and 99mTc-MIBI may accumulate in brain tumors by a similar mechanism or in relation to a similar process of tumor cell proliferation.

Uptake of 99mTc-tetrofosmin, 99mTc-MIBI and 201Tl in malignant thymoma

99mTc-tetrofosmin, Thallium-201-chloride (201Tl) and 99mTc-MIBI imagings were performed in a patient with malignant thymoma. Tracer uptake in the primary tumor was demonstrated. The tumor-to-background ratios of planar and SPECT imagings were 1.60 and 1.98 for 99mTc-tetrofosmin, 1.12 and 2.09 for 201Tl, and 1.19 and 1.80 for 99mTc-MIBI, respectively. In another patient 99mTc-tetrofosmin and 201Tl imagings were performed. Not only the primary tumor but also the direct invasions and metastatic lesions (bone metastases) were clearly detected. The tumor-to-background ratios of planar and SPECT imagings were 2.31 and 2.78 for 99mTc-tetrofosmin and 2.45 and 3.58 for 201Tl, respectively. In 99mTc-tetrofosmin scintigraphy we acquired delayed images, and the tumor-to-background ratios of planar and SPECT delayed images were 1.20 and 1.86, the retention ratios were -1.11 and -0.92 and the retention indices were -48.1 and -33.1, respectively. Our preliminary results suggest that 99mTc-tetrofosmin is useful in detecting not only the primary tumor but also metastatic lesions from malignant thymoma.