201Tl SPECT in the detection of mediastinal lymph node metastases from lung cancer

Delayed Increase in Near-Infrared Fluorescence in Cultured Murine Cancer Cells Labeled with Oxygen-Doped Single-Walled Carbon Nanotubes

The labeling technique for cells with over-thousand-nanometer near-infrared (OTN-NIR) fluorescent probes has attracted much attention for in vivo deep imaging for cell tracking and cancer metastasis, because of low scattering and absorption of OTN-NIR light by biological tissues. However, the intracellular behavior following the uptake of the single-walled carbon nanotubes (SWCNTs), an OTN-NIR fluorophore, remains unknown. The aim of this study is to investigate the time-dependent change in OTN-NIR fluorescence images of cultured murine cancer cells (Colon-26) following treatment with a recently developed OTN-NIR fluorescent probe, epoxide-type oxygen-doped SWCNTs (o-SWCNTs). The o-SWCNTs were synthesized by oxygenation of SWCNTs by ozone under ultraviolet irradiation and were dispersed in an aqueous solution of N-(carbonyl-methoxypolyethyleneglycol 2000)-1,2-distearoyl- sn-glycero-3-phosphoethanolamine to prepare biocompatible o-SWCNTs (o-SWCNT-PEG). OTN-NIR fluorescent o-SWCNT-PEG showed an abnormal behavior following cellular uptake. OTN-NIR fluorescence was not observed in the cells after 24 h incubation with the o-SWCNT-PEG, but clearly increased with longer incubation time from three days after the treatment. This result was further confirmed by Raman microscopy, suggesting that OTN-NIR fluorescence intensity was associated with the cellular uptake of the o-SWCNT-PEG. These results suggest that the Colon-26 cells were successfully labeled by the o-SWCNT-PEG that emit OTN-NIR fluorescence. The o-SWCNT-PEG may aggregate in the cells over time, which could favor their internalization. This delayed concentration followed by a long retention of the o-SWCNT-PEG in cells will facilitate further biotechnological applications of the o-SWCNTs to in vivo deep OTN-NIR fluorescent imaging.

Comparative evaluation of Tc-99m MIBI and Tl-201 chloride SPECT in non-small-cell lung cancer mediastinal lymph node metastases

PURPOSE

To compare the utility of Tc-99m MIBI SPECT and Tl-201 chloride SPECT for presurgical assessment of lung cancer mediastinal lymph node metastases.

METHODS

Forty-one patients with non-small-cell lung cancer underwent dual-isotope imaging with Tl-201 chloride and Tc-99m MIBI and were evaluated for mediastinal lymph node involvement.

RESULTS

The sensitivity rates of early and delayed Tc-99m MIBI SPECT and of early and delayed Tl-201 chloride SPECT for detecting mediastinal nodal metastases were 69%, 69%, 92%, and 92%, respectively. The corresponding specificity rates were 96%, 96%, 93%, and 96%.

CONCLUSION

Tl-201 chloride SPECT is superior to Tc-99m MIBI SPECT when used to detect mediastinal lymph node metastases in patients with non-small-cell lung cancer.

Intense and prolonged Tl-201 accumulation in a slow growing bronchioloalveolar carcinoma

Thallium-201 SPECT was performed to evaluate a pulmonary lesion in a 73-year-old male which had been considered to be an inflammatory lesion for two years. The lesion has slowly increased in size on x-CT. Tl-201 was intensely taken up and retained in the lesion, suggesting a malignant lesion. Histological examination revealed that the lesion was bronchioloalveolar carcinoma. This case suggested that Tl-201 uptake of pulmonary carcinoma would not be necessarily related to cell growth rate.

Evaluation of palpable breast masses with 201Tl scintigraphy

39 female patients (age range: 31-84 years) with palpable breast masses detected by physical examination, underwent 201Tl scintigraphy in order to assess its value in the detection of breast carcinomas and to differentiate them from benign breast masses. Planar images were carried out at 20-30 min and 2-3 h after intravenous administration of 111-185 MBq (3-5 mCi) of 201Tl chloride. In 12 patients single photon emission tomography (SPET) studies were also performed. In 18 patients the scintigraphic studies were positive and in 17 of these cases, breast carcinomas were confirmed. Tumour sizes ranged from 1.3 to 6 cm in diameter. In the remaining patient a false positive result was obtained where there was benign breast change. In three of seven cases, malignant axillary nodes were also detected. All 21 patients with negative scintigraphy had benign breast lesions. There were no differences between images obtained at 20-30 min and 2-3 h or between planar images and SPET studies. In 10 patients there was disagreement between mammography and 201Tl scans. 201Tl scans confirmed the presence of carcinoma in three cases and discarded malignancy in the other six cases. In the remaining case, 201Tl scan was false positive. 201Tl scintigraphy is useful in distinguishing malignant from benign breast masses, even when compared with mammography.

Evaluation of Tl-201 SPECT for monitoring the treatment of pulmonary and mediastinal tumors

Tl-201 single photon emission computed tomography (SPECT) was performed in 88 patients with pulmonary or mediastinal tumors in order to evaluate its usefulness for the detection of disease and for the assessment of the effect of treatment. We also examined mediastinal and hilar lymph node metastasis from lung cancer. Tl-201 SPECT showed abnormal accumulation on delayed images in all lung cancer patients with tumor diameters more than 12 mm. In the 14 operated lung cancer patients, mediastinal and hilar lymph node metastases with diameters of more than 15 mm were imaged, but one with a diameter of 9 mm was missed. The retention index (RI) was 27.52 +/- 31.58 in malignant tumors and -13.67 +/- 8.15 in benign tumors (p < 0.05). The RI was significantly lower after treatment than before treatment. The interval until tumor recurrence or reactivation tended to be longer in patients who showed a significant decrease in the RI after therapy. These findings suggest the usefulness of the RI as an index of therapeutic efficacy.

Pulmonary nuclear medicine

This article reviews the contribution made by nuclear imaging to the assessment, diagnosis and monitoring of patients with respiratory disease. It focuses on several specific areas including the diagnosis of pulmonary embolism, the investigation of intrapulmonary infection and neoplasm and the role of positron emission tomography (PET) scanning.