Biodistributions of 201Tl in tumor bearing animals and inflammatory lesion induced animals

The accumulation of 201Tl in tumor and inflammatory tissues were small. However, this nuclide showed a high concentration in viable tumor tissue, less in connective tissue (containing inflammatory tissue), and was not seen in necrotic tumor tissue regardless of the time after administration of 201Tl(I)-chloride. In inflammatory lesions, 201Tl accumulated in subcutaneous tissue infiltrated with neutrophils and macrophages, and quite large amounts of this nuclide were accumulated in subcutaneous tissue and sites where neutrophils were crowded. Most 201Tl existed in a free form in the fluid of tumor and inflammatory tissues regardless of the time after administration. A small amount of this nuclide was localized in the nuclear, mitochondrial and microsomal fractions in these tissues, and the nuclide was bound to protein in these fractions. The distribution of 201Tl(III)-chloride in tumor bearing animals was essentially the same as that of 201Tl(I)-chloride.     

Congenitally corrected transposition of the great arteries associated with the pre-excitation syndrome

A case with congenitally corrected transposition of the great arteries associated with the pre-excitation syndrome is presented. A gated-blood-pool study and Tl-201 myocardial imaging were performed using SPECT. The tomographic gated-blood-pool images showed the shapes of the right ventricle (RV) and left ventricle (LV), i.e., anatomically LV and RV respectively, to be reversed from that of normal patients. The relationships of the great vessels and ventricles also were easily visualized. RV hypertrophy (anatomical LV) was visualized on the Tl-201 images. Phase analysis showed the earliest excitation was in the anteroseptal region near the base of the LV, which was consistent with the site of the accessory conduction pathway. The gated-blood-pool and Tl-201 tomographic studies were helpful for demonstrating the corrected transposition of the great arteries and the pre-excitation syndrome.     

Clinical evaluation of 123I-MIBG for assessment of the sympathetic nervous system in the heart (multi-center clinical trial)

Multi-center clinical trial of 123I-metaiodobenzylguanidine (123I-MIBG) was carried out to assess its utility as a scintigraphic imaging agent reflecting sympathetic neuronal function in cardiovascular field. Studies were performed on patients with heart diseases of three categories, myocardial infarction, angina pectoris and cardiomyopathy. Scintigraphic images, reflecting sympathetic neuronal function were obtained with 123I-MIBG from all of those categories of patients and the efficacy of the imaging was revealed in 781 (95.0%) out of 822 patients. In some patients abnormality was suggested in sympathetic neuronal function with 123I-MIBG imaging, in spite of normal findings with myocardial perfusion scintigraphy by 201TlCl. In all 981 patients studied with 123I-MIBG, there have been no severe adverse reactions, except complaints of burning on injection site of the agent or nausea, etc. from 4 patients. We conclude that 123I-MIBG imaging is one of the effective tools for diagnostic use reflecting topical sympathetic neuronal function in the heart, judging from its safety and efficacy.     

Thallium-201 SPECT depicts radiologically occult lung cancer.

A case of radiologically occult lung cancer is presented in which 201TI SPECT of the chest clearly delineated the involved area. A 66-yr-old man underwent chest screening examinations for asymptomatic smokers and presented a positive sputum cytology for lung cancer. Conventional chest x-ray, tomography of computed radiography, and a CT scan failed to locate the lesion in the lung. Thallium-201 SPECT, however, was successful in depicting the area of the involvement.     

Myocardial perfusion and clearance of 99mTc teboroxime assessed by SPECT]

99mTc teboroxime is a new myocardial imaging agent that has characteristics of high accumulation in the heart and rapid clearance. We performed tomographic teboroxime study and compared the findings with that of 201Tl. Myocardial teboroxime clearance was calculated by dynamic single photon emission computed tomography (SPECT) using continuous repetitive rotation acquisition method. Teboroxime SPECT image was reconstructed by the three-minute data started from 4 minutes after injection. In 45 myocardial regions (15 patients), complete agreement between 201Tl and 99mTc teboroxime was obtained in 33 regions (73%), when the findings were classified as normal, ischemia and infarction. Significant delay in clearance was seen in the region of coronary stenosis (greater than or equal to 75%) compared with that in the control region (p = 0.0087 at rest, and p = 0.0385 at peak exercise by paired T test). Septum-to-lateral ratios of the clearance and myocardial initial count showed positive correlation (r = 0.743). Further clinical application of this radiopharmaceutical is expected as a new myocardial imaging agent.     

Distant metastases in differentiated thyroid carcinomas: a clinical and pathologic study

Of 514 patients with differentiated thyroid carcinoma treated between 1970 and 1987, 34 (6.6%) had distant metastases. Twelve patients died of their distant metastases; eight of these patients died within 5 years from the time of initial diagnosis. Death from cancer was most frequent in the seventh decade. The metastases were most often found in the lungs and bones. In the fatal group, pleural, brain, and pericardial metastases were noted. Local recurrences were found only in 24% of these 34 patients. Histologic types of primary thyroid tumors and metastatic tumors were reexamined and classified using our criteria, which were mainly based on the World Health Organization nomenclature and currently obtained pathologic observations of thyroid tumors. In 31 thyroid tumors, the surgical specimens were available for review. Twenty-four tumors were papillary and seven were follicular. Of the 24 papillary carcinomas, nine were follicular, eight were well-differentiated, and seven were trabecular. On the other hand, the seven follicular carcinomas consisted of four well-differentiated, two solid, and one oxyphilic. The majority of the thyroid tumors showed an extrathyroidal extension; however, two were intrathyroidal carcinomas and two were encapsulated carcinomas, larger than 5 cm in diameter. Distant metastases were confirmed morphologically in 18 patients (11 by surgical or biopsy material, five by autopsy, and two by cytology). The histologic types of metastatic tumors were consistent with those of primary thyroid tumors. Diagnostic 131I uptake was examined in 32 patients and absorption of diagnostic 131I in metastatic tumors was demonstrated in 21 patients. The 10-year survival rate of patients with 131I accumulating metastases (70%) was significantly better than that of patients with metastases lacking such uptake (40%). Immunoreactivity for thyroglobulin in metastatic tumors was correlated with the 131I absorption. This finding indicated that immunostaining of thyroglobulin in metastatic tumors might be useful in the prediction of the effectiveness of 131I therapy.