Tumor-Szintigraphie mit 123J-markiertem Östradiol beim Mammakarzinom - Rezeptorszintigraphie

Receptor Imaging in Oncology by Means of Nuclear Medicine: Current Status

To date, our understanding of the role of receptors and their cognate ligands in cancer is being successfully translated into the design and development of an arsenal of new, less toxic, and more specific anticancer drugs. Because most of these novel drugs are cytostatic, objective response as measured by morphologic imaging modalities (eg, computed tomography or magnetic resonance imaging) cannot be used as a surrogate marker for drug development or for clinical decision making. Positron emission tomography (PET) can be used to image and quantify the in vivo distribution of positron-emitting radioisotopes such as oxygen-15, carbon-11, and fluorine-18 that can be substituted or added into biologically relevant and specific receptor radioligands. Similarly, single-photon emission computed tomography (SPECT) can be used to image and quantify the in vivo distribution of receptor targeting compounds labeled with indium-111, technetium-99m, and iodine-123. By virtue of their whole-body imaging capacity and the absence of errors of sampling and tissue manipulation as well as preparation, both techniques have the potential to address locoregional receptor status noninvasively and repetitively. This article reviews available data on the in vivo evaluation of receptor systems by means of PET or SPECT for identifying and monitoring patients with sufficient receptor overexpression for tailored therapeutic interventions, and also for depicting tumor tissue and determining the currently largely unknown heterogeneity in receptor expression among different tumor lesions within and between patients.

Thyroid volume measurement in patients prior to radioiodine therapy: comparison between three-dimensional magnetic resonance imaging and ultrasonography

Because of its cost effectiveness, wide availability, and technical ease of application, ultrasonography is the reference method for determining the thyroid volume prior to radioiodine therapy. The goal of the study is a prospective assessment of the deviation between volumetric ultrasonography measurements in comparison to those performed with three-dimensional magnetic resonance imaging (MRI). To that end, 60 consecutive patients with multinodular toxic goiter (n = 28, 46.7%) or Graves' disease (n = 32, 53.3%) were included in the study. Ultrasonographic volumetry according to the well-known ellipsoid formula was performed by three different technicians. In addition, three-dimensional MRI scans of the neck area were acquired and evaluated by the ellipsoid formula as well as by a dedicated region-of-interest technique (MRI-ROI), which was used as standard of reference. While there was no significant difference between the ultrasonographic examinations of the three technicians, a highly significant mean deviation of 22.7% (10.4 mL) was found between the sonographic measurements and the MRI-ROI results (p < 0.01) that were underestimated in 80% of the cases. Correlation coefficients between the various volumetric approaches were highly significant, with values of at least 0.886 (p < 0.01). An additional analysis of volume-dependent subgroups revealed that thyroid volume had no significant influence on the results of ultrasonographic volumetry (p > 0.15). In conclusion, the study showed ultrasonography to be a reliable method of satisfactory accuracy that is appropriate for volumetric thyroid measurements. The findings indicate that the use of a correction factor higher than 0.52 in the ellipsoid formula is recommended to improve accuracy. However, further studies are necessary to confirm these findings.

Estrogen receptor status in primary breast cancer: iodine 123-labeled cis-11beta-methoxy-17alpha-iodovinyl estradiol scintigraphy

PURPOSE

To determine the sensitivity of iodine 123 ((123)I)-labeled cis-11beta-methoxy-17alpha-iodovinyl estradiol (Z-MIVE) scintigraphy for the detection of estrogen receptors in patients with primary breast carcinoma.

MATERIALS AND METHODS

In 22 patients, estrogen receptor status was assessed with planar scintigraphy and single photon emission computed tomography (SPECT) 4 hours after the injection of 185 MBq (123)I-labeled Z-MIVE. For histologic and estrogen receptor immunohistochemical analysis, breast carcinoma tissue was obtained in all patients by means of biopsy or resection of the primary tumor. Two experienced physicians semiquantitatively scored the scintigraphic and immunohistochemical findings. The uptake ratio at scintigraphy and the immunohistologic staining intensity were scored as negative, weak, intermediate, or strong.

RESULTS

All patients had histologically proven breast cancer. Immunohistologic staining for estrogen receptors yielded negative findings in four patients and positive findings in 18 (weak staining, n = 2; intermediate staining, n = 6; strong staining, n = 10). Planar (123)I-labeled Z-MIVE scintigraphic findings were negative in five patients and positive in 17 (weak uptake, n = 2; intermediate uptake, n = 10; strong uptake, n = 5), resulting in one false-negative finding. Findings at (123)I-labeled Z-MIVE SPECT were negative in four patients and positive in 18. The sensitivities of (123)I-labeled Z-MIVE scintigraphy for estrogen receptors were 100% with SPECT and 94% with planar scintigraphy. The correlation between immunohistologic and planar scintigraphic scores of estrogen receptor status was 0.72 (P <.01).

CONCLUSION

(123)I-labeled Z-MIVE scintigraphy is a sensitive noninvasive tool for the detection of estrogen receptors in patients with breast cancer.

Radioiodine therapy in Graves' disease patients with large diffuse goiters treated with or without carbimazole at the time of radioiodine therapy

We sought to ascertain how high the success rates of radioiodine therapy are for Graves' disease patients with large diffuse goiters when aiming for a constant absorbed dose of 250 Gy. Thirty-six patients with a thyroid volume of 50-110 mL were evaluated for changes in thyroid function and appearance 3, 6, and 12 months after radioiodine therapy. Success was defined as definitive elimination of hyperthyroidism following therapy (hypothyroidism corrected with thyroxine on diagnosis); failure as persistent/recurrent hyperthyroidism after 12 months. Overall success rate was 50%. However, a subgroup of 20 patients without simultaneous carbimazole (carbimazole-off) showed a highly significantly larger success rate (85%) than the 16 patients with simultaneous carbimazole (carbimazole-on) at the time of radioiodine therapy (6.3%, p < 0.000005). Successful cases showed a significantly higher volume reduction after radioiodine than failures (75.5% vs. 35.4%, p < 0.00005). Stepwise logistic regression showed that therapy failure was related to administration of carbimazole during radioiodine therapy (p < 0.0250 and absorbed dose (p < 0.05), but not thyroid function (free triiodothyronine [FT3] and free thyroxine [FT4]), initial thyroid volume or thyrotropin-receptor antibody (TRAb) value. However, a significant correlation of therapy success to absorbed dose (r = 0.69, p < 0.005) could be shown only for carbimazole-off patients, but not for the others. Finally, multivariate factor analysis consistently showed that therapy success was correlated only to absorbed dose and antithyroid drugs, not to initial thyroid volume, TRAb value, or thyroid function. Thyroid volume per se is not responsible for the lower success rate in Graves' disease patients with large goiters because even a comparable group of 32 Graves' disease patients with small thyroid glands (< or =20 mL) and without simultaneous carbimazole showed a success rate of 87.5%. The high failure rate in the carbimazole-on patients (absorbed dose comparable to carbimazole-off) is due to the simultaneous administration of carbimazole. Therefore, if clinically feasible, we recommend discontinuing carbimazole at least one day before beginning radioiodine therapy.