sodium-pertechnetate-tc-99m and Lung-Diseases--Interstitial

99mTc-Technegas (Technegas) scintigraphy, including planar and SPECT images, was reviewed in patients who mainly had pulmonary emphysema. The Technegas images showed different degrees of change, from areas of heterogeneity to hot spots or defects. Comparison of planar and SPECT Technegas images revealed that more detailed findings were shown by SPECT than by planar images in mild cases. In more severe cases, the findings of SPECT and planar images were equivalent. In advanced stages, SPECT images should be excluded in favor of planar images. Technegas SPECT could demonstrate ventilation impairment more easily than 133Xe gas dynamic SPECT. The optical average score of Technegas in whole lung correlated well with forced expiratory volume in one second (FEV1.0) and FEV1.0/forced vital capacity. Technegas could assess ventilation impairment in pulmonary emphysema more easily than CT, especially in the upper lung field. Technegas was useful for the assessment not only of pulmonary emphysema but also of other diseases. For the quantitative evaluation of Technegas, some investigators study three-dimensional fractal analysis or mean voxel values of the lung. These quantitative analyses are useful for classifying clinical stage and comparing cases.

Topics: Asthma; Female; Humans; Lung Diseases, Interstitial; Male; Pulmonary Emphysema; Radiopharmaceuticals; Sodium Pertechnetate Tc 99m; Tomography, Emission-Computed, Single-Photon

Interstitial lung diseases (ILD) are characterized by an acute or chronic inflammation of the alveolar capillary membrane, which affects the permeability of this membrane. A possible way to measure the permeability of the membrane is by radionuclide aerosol imaging. Pertechnegas, a gas composed of technetium-labelled carbon particles, has recently been proposed as a new ventilation agent to measure this lung clearance. The clearance by pertechnegas in the four most common forms of ILD (eight patients with connective tissue disease, 10 with hypersensitivity pneumonitis, nine with idiopathic interstitial pneumonia and 10 with sarcoidosis) was measured and compared with 10 nonactive smoking controls. Because forced vital capacity (FVC), total lung capacity (TLC) and carbon monoxide diffusing capacity of the lung (DL,CO) are used in the assessment of functional severity of the ILD, the pertechnegas clearance was correlated with these lung-function indices. It was found that the time to half clearance of pertechnegas of the lung is significantly decreased in idiopathic interstitial pneumonia (p<0.0001), hypersensitivity pneumonitis (p=0.0005) and connective tissue disease (p=0.002) but not in sarcoidosis when compared with 10 nonsmoking controls. A significant correlation is also found between time to half clearance and FVC (r=0.76; p<0.0001), TLC (r=0.63; p<0.0001) and DL,CO (r=0.75; p<0.0001) for all groups together. For all subjects as a group, the time to half clearance is shorter in the upper lung zones than in the lower zones (p<0.0001) and the ratio between both zones is not significantly different between the different types of disease. These results indicate that pertechnegas clearance is increased in idiopathic interstitial pneumonia, hypersensitivity pneumonitis and connective tissue disease, but not in sarcoidosis and is related to the functional severity of the disease.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alveolitis, Extrinsic Allergic; Cell Membrane Permeability; Connective Tissue Diseases; Humans; Lung Diseases, Interstitial; Middle Aged; Pulmonary Diffusing Capacity; Sarcoidosis, Pulmonary; Sodium Pertechnetate Tc 99m; Total Lung Capacity; Vital Capacity

Interstitial lung disease (ILD) is characterized by inflammation within the alveolar walls and interstitium of the lungs. This causes increased alveolar-capillary membrane permeability. The diagnosis is made by clinical features, chest roentgenography, lung function tests, and high-resolution CT, and it is confirmed by lung biopsy. Radionuclide aerosol tracers such as Tc-99m DTPA show increased lung clearance in ILD. The clearance rate of microaerosol pertechnegas (modified Technegas) from the lungs in the assessment of ILD was evaluated.. Thirty-two patients (22 with ILD and 10 with non-ILD) were evaluated with pertechnegas. Pertechnegas is formed by adding 3% oxygen to technegas, a microaerosol ventilation agent. Regions of interest were then drawn around the lungs, and clearance rates were determined from the best exponential fit.. The mean clearance rate of pertechnegas was significantly increased in ILD and measured 5.78 +/- 2.2 minutes compared with non-ILD, which measured 8.53 +/- 2.42 minutes (P < 0.001). The sensitivity and specificity rates of pertechnegas clearance (less than 8 minutes) in ILD were 90% and 60%, respectively. When combined with chest roentgenography, the sensitivity and specificity rates increased to 100% and 90%, respectively.. Pertechnegas is highly effective in determining the presence of active ILD. It differentiates between active ILD and non-ILD, and it is highly sensitive and specific when combined with chest roentgenography. Its potential role in the management of ILD merits further investigation.

Topics: Adult; Aged; Blood-Air Barrier; Female; Graphite; Humans; Lung; Lung Diseases, Interstitial; Male; Middle Aged; Permeability; Pulmonary Fibrosis; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Sodium Pertechnetate Tc 99m

For quantitative evaluation of the regional lung function in patients with interstitial pulmonary disease (IP) in the sitting position, 99mTc-Technegas and 99mTc-macroaggregated albumin (MAA) single-photon emission tomography (SPET) studies were performed in 12 healthy controls (HC) and 42 IP patients. Four transverse images were prepared from the data obtained and designated as slices no. 1-4 from the top downward. Regions of interest (ROIs) were determined in the anterior and posterior parts of the lung in each slice, and the ratio of the count per voxel in the ROIs to the count in the entire lung was calculated as the regional Technegas index (T). The regional perfusion index (Q) was calculated by a similar procedure using the data of 99mTc-MAA SPET. The ratios between T and Q (T/Q) in the anterior and posterior regions of the lung, and the ratios of T and Q between the anterior and posterior regions of the lung (Tp/Ta and Qp/Qa) were examined. In the HC group, T/Q decreased but Tp/Ta and Qp/Qa increased from the upper to the lower lung fields. When IP patients were classified into (I) those in whom T/Q decreased from the upper to the lower lung fields, (II) those in whom it was similar in all slices, (III) those in whom it increased from slice 3 to slice 4, and (IV) those in whom it increased from slice 2 to slices 3 and 4, this classification was more closely correlated with %VC than with %DLCO or PaO2. When the patients were classified according to Tp/Ta and Qp/Qa into (A) those in whom the values were greater in the lower than the upper lung field, (B) those in whom the values were similar in all slices, and (C) those in whom the values were smaller in lower than in upper lung fields, categories B and C were observed frequently even in patients whose %VC was in the normal range. This method is considered to be an effective means to evaluate the progression and pathology of IP and to detect early impairment of lung function.

Topics: Adult; Aged; Aged, 80 and over; Female; Graphite; Humans; Lung; Lung Diseases, Interstitial; Male; Middle Aged; Radiopharmaceuticals; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Aggregated Albumin; Tomography, Emission-Computed, Single-Photon; Ventilation-Perfusion Ratio