[en] This study was designed to assess the potential of Tl-201 scintigraphy in determining the therapeutic effects. Doses of 20 and 40 Gy were delivered to VX-2 tumors implanted in rabbits. Tumor Tl-uptake was quantitatively evaluated by determining the count ratio of Tl uptake in the tumor to that in the contralateral normal tissue. Tumor shrinkage or disappearance was seen in the 40 Gy group. In the 20 Gy group, however, some tumors were shrinked or disappeared, but the others were enlarged. In the 20 Gy group of tumor shrinkage or disappearance, the Tl-uptake ratio 7 days after irradiation was significantly lowered, as compared with that in the group of tumor enlargement and the non-irradiated group; and after that it was even more lowered. In the 20 Gy group, tumor volume was also slightly larger 7 days after irradiation than that before irradiation. In comparing the group in which Tl-uptake ratio decreased by 30% or more and the group in which it decreased by less than 30% after irradiation, tumor volume was inhibited or disappeared in the former but was increased in the latter. The uptake of BrdU, which is thought to reflect tumor proliferative potentiality, was extremely decreased associated with decreased Tl-uptake ratio in the 40 Gy group in which tumor volume was only inhibited 7 days after irradiation. Tl-201 scintigraphy may have a potential in evaluating tumor proliferation relatively early after radiation therapy, irrspecstive of tumor volume. (N.K.)

[en] Technetium-99m-hexamethylpropylene amineoxime (^99mTc-HMPAO) scintigraphy was performed in 15 malignant tumors in 11 patients and a patient with bronchopneumonia. A high ^99mTc-HMPAO affinity for the tumors was observed on SPECT, however, the mean tumor/contralateral normal lung ratios of ^99mTc-HMPAO activity (1.26) was lower than that of ²⁰¹Tl-chloride (2.29). The ^99mTc-HMPAO uptake was seen not only in the tumors but also in the bronchopneumonia, atelectasis, and irradiated lung (containing radiation fibrosis). Moreover, a diffuse uptake in the lung was seen in a patient received repeated chemotherapy. Therefore, it is emphasized that there is a non-specific ^99mTc-HNPAO uptake in those various pulmonary conditions. (author)

[en] The authors evaluated the ability of ^99mTc-hexamethylpropyleneamine oxime (^99mTc-HMPAO) to serve as a sensitive marker of lung injury. Two experiment rabbit models of minimal lung injury were designed using injections of a low dose (0.05 ml/kg) of oleic acid or 50 Gy of irradiation. In addition, they clinically investigated whether patients who received chemotherapy (n = 14) or radiotherapy (n = 13) for lung cancer showed high uptake of ^99mTc-HMPAO in the lungs. Despite the minimal endothelial lesions visualized by electron microscopy (edematous changes and blebbing), in both animal models, the lungs showed high uptake of ^99mTc-HMPAO, which occurred rapidly within 1 min after injection. Clinically, the mean lung-to-liver ratio of ^99mTc-HMPAO activity in the patients who received chemotherapy (0.649±0.185, p < 0.01) was significantly higher than that of the controls (n = 16; 0.387±0.108), and all 12 patients who received more than 30 Gy of irradiation showed abnormal uptake in the irradiated lungs, despite the lack of abnormal opacities on chest CT. These findings suggest that ^99mTc-HMPAO has the potential to be a sensitive marker of chemical and irradiation lung injury. 53 refs., 5 figs., 3 tabs

[en] A case is presented in whom a new malignant neoplasm developed in fields of prior irradiation. The tumor was histologically diagnosed as osteosarcoma. This case satisfied the criteria of the radiation induced sarcoma proposed by Maehara et al. (author)

[en] Pulmonary dynamic CT densitometry during steady-state breathing was recorded and analyzed using helical CT scan in 14 patients with obstructive disorders involving small and large airways, and 2 with restrictive lung disease. The data set of 7-second, continuous helical scan at constant table position were reconstructed as 35 one-second temporarily overlapping images at 0.2-second intervals over 2-3 respiratory cycles, and regional CT densitometry was displayed. Normal lungs (5 volunteers) showed a regular sinusoidal curve, and maximal lung density change (LDC) was greater independent lungs than in independent lungs, with an average difference of 29.5 HU, indicating the gravitational effect. In contrast, a regular sinusoidal curve was not shown in obstructive disorders, and a significant reduction in maximal LDC (33.7±22.6 HU) compared with the normal lungs (60.8±25.9 HU) (p<0.001) was indicated. In contrast, no marked reduction in maximal LDC (53.7±28.6 HU) was shown in restrictive disorders. This method is fast and easy, and appears useful for the detection of ventilation abnormalities in obstructive lung disorders. (author)

[en] This study retrospectively investigated the good parameters on thallium-201 chloride (²⁰¹Tl) SPECT for early assessment of the therapeutic effects in patients with non-small cell lung cancer. Based on tumor response as determined by chest CT scan about 9 weeks after the end of irradiation with adjuvant chemotherapy, the subjects were divided to the responder group (tumor regression >50%, n=13) and non-responder group (tumor regression <50%, n=13). ²⁰¹Tl SPECT was performed before and at the halfway through the course of therapy (average tumor dose, 27.4 Gy±4.5) in all the patients. SPECT was conducted twice 15 min (early scan) and 120 min (delayed scan) after intravenous injection of 148 MBq (4 mCi) of ²⁰¹Tl. Tumor-to-contralateral normal lung tissue count ratios on both scans were calculated as early and delayed uptake ratios (EUR and DUR), and a retention index (RI) was also derived from these ratios. In the responder group, a significant decrease in DUR and RI halfway through the therapy was observed compared to pretreatment (2.6±0.6 vs. 3.5±1.0; p<0.01, and -2.3%±25.5 vs. 37.4%±17.8; p<0.001, respectively), even though EUR did not change significantly (N.S.). By contrast, in the non-responder group, there were no significant changes in any of these parameters (N.S.). When comparing DUR and RI for the two groups halfway through the therapy, DUR and RI were significantly lower in the responder group (both; p<0.01), but no significant difference was noted in EUR (N.S.), and the percent reduction in tumor size did not correlate with the percent decrease in DUR or RI (N.S.). These results indicate that the extent of decrease in DUR and RI after therapy can be a useful parameter for early assessment of the therapeutic effects in patients with non-small cell lung cancer. (author)

[en] The usefulness of pulmonary dynamic densitometry (PDD) acquired by spiral computed tomography (CT) to detect ventilation abnormalities in obstructive airway disorders was evaluated in comparison with dynamic xenon-133 (Xe-133) SPECT. Eight-second, continuous spiral CT scan was performed over 2-3 respiratory cycles in six healthy volunteers, 19 patients with airways disorder, and six patients with restrictive lung disease. The data set were reconstructed as 36 one-second temporally overlapping images at 0.2-second intervals, and regional PDD curves were displayed. Regional ventilation was assessed by Xe-133 clearance-time on Xe-133 SPECT. Normal lungs showed smooth, sinusoidal PDD curves with maximal amplitude in lung attenuation change (MALAC) of 54.9+24.5 HU; whereas, obstructive airways disorders with prolonged Xe-133 clearance showed significantly diminished MALAC (31.6+20.1 HU, P<0.0001), accompanied by irregularity, asynchronous phase, and deterioration of normal ventral-to-dorsal gradients in MALAC and lung attenuation. Restrictive diseases without prolonged Xe-133 clearance did not show statistically significant reduction in MALAC. In total 251 lung regions, regional MALAC correlated inversely with Xe-133 clearance-time (r=842). PDD acquired by spiral CT is acceptable for detecting ventilation abnormalities in obstructive airways disorder. (author)

[en] Usefulness of dynamic Xe-133 SPECT in detection of ventilation abnormality was examined in lung disease. Subjects were 7 healthy volunteers and 84 patients with lung disease (72 males, 12 females, age 47-78). Dynamic SPECT was performed using triple-head SPECT system with the return mode of continuous repetitive rotating acquisition. One SPECT image (slice thickness 3.2 mm) was reconstructed from the averaged data of the same angle (every 6 degrees). Following inhalation of Xe-133 gas, equilibrium and washout images were acquired by 3-D SPECT and constructed using surface rendering method from 32 transverse system image of the whole lung field. Then, each 3-D images were superposed to one 3-D image. Washout time (T 1/2) of Xe-133 gas delayed significantly in obstructive pulmonary disease compared with those of healthy volunteers and restrictive lung disease. In 10 cases of restrictive lung disease, abnormal shadow was detected with chest CT, but no delay of washout was recognized. In composition of 3-D image, spatial distribution and extent of Xe-133 retention were grasped easily. (K.H.)

[en] We investigated preliminarily the clinical utility of dynamic SPECT in studying pulmonary Xenon-133 gas washout, using the continuous repetitive rotating acquisition method with a triple-headed SPECT system. The subjects included one healthy volunteer and 16 various lung diseases. After obtaining the equilibrium images, the sequential washout images were acquired every 60 sec for 6 min. As the ventilation index, the real half-time of regional activity was evaluated. With or without abnormalities on chest CT, these images allowed us to show effectively the three-dimensional distribution of ventilation abnormalities, such as peripheral or segmental air trapping. Xenon-133 washout SPECT is useful to elucidate the distribution and nature of ventilation abnormalities in various diseases. (author)

[en] Radiation-induced alteration of intra-pulmonary kinetics of ¹²³I-IMP was investigated in 11 rabbits received a 50 Gy dose of radiation to the hemithorax. In all of these rabbits examined during 3-17 weeks following the irradiation, an abnormal accumulation was seen in the irradiated lung on the delayd image obtained 60 minutes after the injection of ¹²³I-IMP. The time-activity curves in the irradiated lung following the injection had shallower downslopes of both the initial fast phase and the following slow phase than those of non-irradiated lung, and finally ¹²³I-IMP uptake of the irradiated lung exceeded that of the normal lung. Chest radiographies all of 11 rabbits showed no abnormal shadow and histological studies in 6 of them revealed a relatively slight change or injury of the irradiated lung during 3-17 weeks. These results indicate that this agent may be useful for detecting and assessing relatively early and slight lung injury induced by irradiation. (author)