Relative preservation of peripheral lung function in smoking-related pulmonary emphysema: assessment with 99mTc-MAA perfusion and dynamic 133Xe SPET

In this study the cross-sectional functional differences between the central and peripheral lung in smokers with pulmonary emphysema were evaluated by lung perfusion and dynamic xenon-133 single-photon emission tomography (SPET). The subjects were 81 patients with a long-term smoking history and relatively advanced emphysema, 17 non-smoker patients with non-obstructive lung diseases and six healthy non-smokers. Regional lung functional difference between the peripheral and central lung was assessed in the upper, middle and lower lung zones by technetium-99m macroaggregated albumin SPET and dynamic 133Xe SPET. The distribution of emphysematous changes was assessed by density-mask computed tomography (CT) images which depicted abnormally low attenuation areas (LAAs) of less than -960 Hounsfield units. Two hundred and eighty-eight (59.2%) lung zones of 63 (77.7%) patients with pulmonary emphysema showed relative preservation of lung function in the peripheral lung, with a curvilinear band of normal perfusion (a stripe sign) and a significantly faster 133Xe half-clearance time (T(1/2)) than in central lung (P<0.0001). Of these lung zones, 256 (88.8%) showed central-dominant LAA distributions on density-mask CT images, but the remaining 32 zones did not show any regional preference in LAA distribution. Conversely, 117 (24.0%) lung zones of 19 (23.4%) patients showed periphery-dominant perfusion defects and LAA distributions, with significantly prolonged T(1/2) in the peripheral lung area (P<0.0001). The remaining 81 lung zones of the patients with pulmonary emphysema and all the lung zones of the healthy subjects and patients with non-obstructive lung diseases did not show a stripe sign, and no differences were observed in T(1/2) values and LAA distributions between the central and peripheral lung. Relative preservation of peripheral lung function seems to be a characteristic feature in smoking-related pulmonary emphysema, and may indicate a lower susceptibility of peripheral parenchyma to the development of this disease.     

Relative preservation of peripheral lung function in smoking-related pulmonary emphysema: assessment with 99mTc-MAA perfusion and dynamic 133Xe SPET

In this study the cross-sectional functional differences between the central and peripheral lung in smokers with pulmonary emphysema were evaluated by lung perfusion and dynamic xenon-133 single-photon emission tomography (SPET). The subjects were 81 patients with a long-term smoking history and relatively advanced emphysema, 17 non-smoker patients with non-obstructive lung diseases and six healthy non-smokers. Regional lung functional difference between the peripheral and central lung was assessed in the upper, middle and lower lung zones by technetium-99m macroaggregated albumin SPET and dynamic ¹³³Xe SPET. The distribution of emphysematous changes was assessed by density-mask computed tomography (CT) images which depicted abnormally low attenuation areas (LAAs) of less than –960 Hounsfield units. Two hundred and eighty-eight (59.2%) lung zones of 63 (77.7%) patients with pulmonary emphysema showed relative preservation of lung function in the peripheral lung, with a curvilinear band of normal perfusion (a stripe sign) and a significantly faster ¹³³Xe half-clearance time (T _1/2) than in central lung (P<0.0001). Of these lung zones, 256 (88.8%) showed central-dominant LAA distributions on density-mask CT images, but the remaining 32 zones did not show any regional preference in LAA distribution. Conversely, 117 (24.0%) lung zones of 19 (23.4%) patients showed periphery-dominant perfusion defects and LAA distributions, with significantly prolonged T _1/2 in the peripheral lung area (P<0.0001). The remaining 81 lung zones of the patients with pulmonary emphysema and all the lung zones of the healthy subjects and patients with non-obstructive lung diseases did not show a stripe sign, and no differences were observed in T _1/2 values and LAA distributions between the central and peripheral lung. Relative preservation of peripheral lung function seems to be a characteristic feature in smoking-related pulmonary emphysema, and may indicate a lower susceptibility of peripheral parenchyma to the development of this disease. Received 8 January and in revised form 13 March 2000     

Evaluation of an integrated 133Xe regional pulmonary-function analyzer.

An integrated system for diagnostic, quantitative, static and dynamic, regional pulmonary-function analysis--both ventilation and perfusion--using 133Xe has recently been developed by Ohio-Nuclear. This paper considers this equipment in a clinical setting and describes the results obtained from 50 normal subjects. Functionally, the analyzer was found to be satisfactory and its operation simple and easy to learn. Patient discomfort is minimal and the complete ventilation-perfusion analysis can be performed and reported in less than 30 min. The results from normal subjects were comparable with published results.     

Characterization of 133Xe gas washout in pulmonary emphysema with dynamic 133Xe SPECT functional images

PURPOSE: To characterize regional ventilation impairment of pulmonary emphysema using dynamic 133Xe single photon emission computed tomography (SPECT) functional images, compared with other forms of chronic obstructive pulmonary disease (COPD). METHODS: Dynamic 133Xe SPECT was performed in 34 patients with emphysema and 15 patients with other forms of COPD. Three-dimensional voxel-based functional images of the half-clearance time (T1/2) mainly reflecting the initial rapid washout of 133Xe gas from the large airways, and of the mean transit time (MTT) reflecting 133Xe gas washout from the entire lungs, including the small airways and alveoli, were created based on an area-over-height method. T1/2 and MTT values were compared with the regional extent of low attenuation areas (%LAA) on density-mask computed tomography images and the diffusing capacity of the lungs for carbon monoxide (DLCO). RESULTS: The MTT/T1/2 ratio in each lung in emphysema was significantly higher than that in other forms of COPD (1.60+/-0.74 vs. 1.21+/-0.26; P<0.01). In the selected unilateral lungs with similar T1/2 values, MTT values were also significantly higher in emphysema. MTT values in each lung showed a significantly closer correlation with the corresponding %LAA values compared with T1/2 values in emphysema (R=0.698, P<0.0001 vs. R=0.338, P<0.01; P<0.05); while only the T1/2 values showed a significant correlation in other forms of COPD (P<0.0001). In correlation with DLCO, MTT values showed a significantly closer correlation compared with T1/2 values in emphysema (R=0.909, P<0.0001 vs. R=0.555, P<0.001; P<0.05); while either value did not show a significant correlation in other forms of COPD. CONCLUSION: MTT values are more critically affected in emphysema compared with other forms of COPD without significant alveolar destruction, and MTT and T1/2 values appear to be differently correlated with the regional extent of LAA between these two disorders. Direct comparison of regional T1/2 and MTT values on functional images may contribute to the demarcation of lung pathology of these two disorders.     

Regional ventilatory evaluation using dynamic SPET imaging of xenon-133 washout in obstructive lung disease: an initial study

Regional ventilatory abnormalities in obstructive lung disease were evaluated by dynamic single-photon emission tomography (SPET) of pulmonary washout of xenon-133 (¹³³Xe) gas. The subjects included seven healthy volunteers. 17 patients with obstructive lung disease, and seven patients with restrictive lung disease. Following 6 min of inhalation of¹³³Xe gas (60–72 MBq/1), equilibrium and subsequent washout SPET images during spontaneous breathing were sequentially acquired every 30 s for 6–7 min, using a triple-head SPET system with the return mode of continuous repetitive rotating acquisition. A gravity-induced gradient of ventilation was demonstrated in the volunteers' lungs. Compared with the normal subjects, all the patients with obstructive disease showed abnormal¹³³Xe retention on the washout SPET images, with or without abnormalities on chest X-ray computed tomography, whereas the patients with restrictive disease did not show any significant delays in washout. This modality may assist in the evaluation of the three-dimensional dynamic process of ventilatory abnormalities in obstructive lung disease.     

Evaluation of lung volumetry using dynamic three-dimensional magnetic resonance imaging

RATIONALE AND OBJECTIVES: We sought to investigate lung volume and surface measurements during the breathing cycle using dynamic three-dimensional magnetic resonance imaging (3D MRI). MATERIALS AND METHODS: Breathing cycles of 20 healthy volunteers were examined using a 2D trueFISP sequence (3 images/second) in combination with a model and segmented 3D FLASH sequence (1 image/second) MR images using view sharing. Segmentation was performed semiautomatically using an interactive region growing technique. Vital capacity (VC) was calculated from MRI using the model (2D) and counting the voxels (3D) and was compared with spirometry. RESULTS: VC from spirometry was 4.9+/-0.9 L, 4.4+/-1.2 L from 2D MRI measurement, and 4.7+/-0.9 L for 3D MRI. Using the 3D technique, correlation to spirometry was higher than using the 2D technique (r>0.95 vs. r>0.83). Using the 3D technique, split lung volumes and lung surface could be calculated. There was a significant difference between the left and right lung volume in expiration (P<0.05). CONCLUSIONS: Dynamic 3D MRI is a noninvasive tool to evaluate split lung volumes and lung surfaces during the breathing cycle with a high correlation to spirometry.     

Effect of bronchodilation on regional lung function measured by 133Xe and gamma camera

Using ¹³³Xe, a gamma camera and off-line data handling the effect of inhaled Salbutamol on regional lung function was measured in six patients with chronic obstructive lung disease and associated bronchospasm.After bronchodilation only minor changes were obtained in regional ventilation or in the arterial hypoxemia, although the overall airways obstruction improved markedly. These findings suggest that the bronchodilating agent had an effect mainly on the larger airways and almost did not influence the function of the more peripheral lung units responsible for gas exchange. Also, a slight but direct effect on the perfusion was demonstrated. The effect on the ¹³³Xe ventilation-perfusion ratio was not correlated with that on the hypoxemia, indicating that the first is not a good representation of the latter.Supported by a grant from the Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

Comparison of 133Xe gas dynamic SPECT and thin-section CT in patients with pulmonary emphysema

PURPOSE: We assessed 133Xe gas dynamic single photon emission computed tomography (SPECT) by comparing washout axial images with thin-section CT (TSCT) in patients with pulmonary emphysema. METHODS: Twenty-three patients were studied. All patients were diagnosed as having pulmonary emphysema on the basis of TSCT. We compared TSCT of upper, middle and lower lung fields with 133Xe gas dynamic SPECT axial images at the corresponding levels during the 3 to 4 minutes of washout phase. If the degree of 133Xe gas retention or TSCT finding of ventral and dorsal parts was not the same, the images were divided into two parts. RESULTS: A total of 174 lesions in 23 cases were examined, but 3 lesions having no retention of 133Xe gas at equilibrium phase were excluded. The results showed that: there were 37 lesions (21.6%) with equivalent severity on both images; there were 42 lesions (24.5%) with more severity on 133Xe gas dynamic SPECT than on TSCT; and there were 92 lesions (53.8%) with more severity on TSCT than on 133Xe gas dynamic SPECT. The severity on 133Xe gas dynamic SPECT and TSCT was not always compatible. One of the reasons for the variable 133Xe gas retention even when the lesion had the same severity on TSCT, may be bronchial stricture which cannot be seen on TSCT. CONCLUSION: By comparison of axial images of 133Xe gas dynamic SPECT with CT images, we could recognize the areas of 133Xe gas retention in detail. Results suggest that 133Xe gas dynamic SPECT can be useful to identify ventilation impairment in pulmonary emphysema.     

Measurement of regional hepatic blood flow with 133Xe per-rectal portal scintigraphy

The hepatic blood flow (HBF) of patients with liver disease was measured by per-rectal portal scintigraphy with the use of 133Xe. To analyze the time-activity curves of the liver and portal vein, washout curves of the liver were plotted, and from those, the HBF and the ratio of the HBF of the right lobe of the liver to that of the left lobe (R/L ratio) were calculated. The HBF were 143 +/- 17 ml/100 g/min in 5 patients with chronic inactive hepatitis, 119 +/- 20 ml/100 g/min in 4 patients with chronic active hepatitis, and 73.2 +/- 23.4 ml/100 g/min in 7 patients with cirrhosis of the liver. All of four patients whose HBF was under 100 ml/100 g/min and whose R/L ratio was under 1.0 had cirrhosis of the liver. Only one of the 9 patients whose HBF was over 100 ml/100 g/min and whose R/L ratio was over 1.0 had cirrhosis of the liver. The results suggested that per-rectal portal scintigraphy is a useful and noninvasive method to measure the hepatic blood flow.     

Evaluation of histopathological differentiation in lung adenocarcinoma patients using 201Tl-chloride and 99Tcm-MIBI SPET

The purpose of this prospective study was to evaluate the relationship between thallium-201 chloride (201Tl) and technetium-99m hexakis 2-methoxyisobutylisonitrile (99Tcm-MIBI) accumulation and histopathological differentiation in primary lung adenocarcinoma. A total of 43 patients with primary lung adenocarcinoma were investigated. The patients were divided into well differentiated (n = 17), moderately differentiated (n = 14) and poorly differentiated (n = 12) carcinoma groups. Simultaneous dual single photon emission tomography (SPET) images with 201Tl and 99Tcm-MIBI were acquired 15 min (early) and 2 h (delayed) after injection. Using a region of interest technique, the tumour-to-normal lung ratio was calculated for both early (early ratio) and delayed (delayed ratio) images. The retention index was calculated using the formula delayed ratio/early ratio. Uptake of the radionuclides was compared with the classification of tumour differentiation grading. The mean (+/- SD) values of the early ratio, delayed ratio and retention index using 201Tl were 2.19+/-0.72, 2.28+/-0.71 and 1.06+/-0.16, respectively, in the well differentiated group, 2.38+/-0.83, 2.48+/-0.84 and 1.08+/-0.23, respectively, in the moderately differentiated group, and 2.87+/-0.75, 3.60+/-1.51 and 1.22+/-0.21, respectively, in the poorly differentiated group. Both the ratios and the retention index using 201Tl were significantly lower in the well differentiated group than in the poorly differentiated group. The delayed ratio using 201Tl in the moderately differentiated group was also significantly lower than that in the poorly differentiated group. There were no significant differences in either ratio or the retention index among the three groups using 99Tcm-MIBI. 201Tl SPET is superior to 99Tcm-MIBI SPET for the grading of histopathological differentiation of primary lung adenocarcinoma.     

Comparison of99mTc-Technegas SPECT with133Xe dynamic SPECT in pulmonary emphysema

This study was undertaken to compare axial images of^99mTc-Technegas SPECT (Technegas) with those of¹³³Xe gas dynamic SPECT in patients with pulmonary emphysema. There were 20 patients, 19 males and 1 female. All patients except one ex-smoker were heavy smokers with a mean age of 68.1 years. For Technegas scintigraphy, the patients inhaled 505 MBq^99mTc-Technegas in several tidal volume breaths in the supine position without breath holding. For¹³³Xe gas scintigraphy, the patients inhaled 370 MBq¹³³Xe gas.¹³³Xe gas dynamic SPECT was performed in the equilibrium phase for the last minute of the 3 minute inhalation in a closed circuit, and in the washout phase for 6 minutes of inhalation in a semi-closed circuit, by means of a gamma camera with dual detectors (Picker model Prism 2000). Abnormal findings included heterogeneity, defects and hot spots on Technegas images and on retention images taken 3 minutes after¹³³Xe gas washout. In 2 of 20 patients, the degree of abnormal findings on Technegas images depended on the area of¹³³Xe gas retention in the washout phase. In 3 patients, the degrees of abnormal findings on both Technegas SPECT and¹³³Xe gas dynamic SPECT images were equivalent. In the remaining 15 patients, more detailed findings and a greater area were shown by Technegas SPECT than¹³³Xe gas dynamic SPECT. We conclude that in patients with pulmonary emphysema Technegas SPECT can demonstrate ventilation impairment more easily than¹³³Xe gas dynamic SPECT.