Gallium-67 citrate scanning in the staging of idiopathic pulmonary fibrosis: Correlation and physiologic and morphologic features and bronchoalveolar lavage

A pilot trial of quantitative Tc-99m HMPAO and Ga-67 citrate lung scans to detect pulmonary vascular endothelial damage and lung inflammation in patients of collagen vascular diseases with active diffuse infiltrative lung disease

Diffuse infiltrative lung disease (ILD) includes a heterogeneous group of disorders predominantly affecting lung parenchyma and sparing the airway. To assess the degree of pulmonary vascular endothelial damage in active ILD, lung/liver uptake ratios (L/L ratio) on technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) lung scan were determined in 30 patients with active ILD. Meanwhile, the gallium-67 citrate (Ga-67) uptake index (GUI) on Ga-67 lung scan was used to evaluate the severity of lung inflammation in active ILD. In this study, high-resolution CT (HRCT) was used to evaluate disease activity in ILD. The results show statistically significant differences between normal controls and patients with active ILD as shown in L/L ratios and GUI. However, when the patients were divided into two groups of 15 patients with normal chest X-ray findings and 15 with abnormal X-ray findings, there was no significant difference in those parameters. In addition, there was no statistically significant difference between the groups in HRCT scoring. No good correlation between the degree of pulmonary vascular endothelial damage and the severity of lung inflammation was found. In addition, there were no good correlations between HRCT scoring vs GUI and HRCT vs L/L ratio in different study subgroups. In conclusion, L/L ratios on Tc-99m HMPAO and GUI on Ga-67 lung scans differ from chest X-ray findings and have the potential to detect the degree of pulmonary vascular endothelial damage and severity of lung inflammation in active IDL. However, the relationships between HRCT scoring, GUI, and L/L ratio in patients with collagen vascular diseases and active ILD are not significant.

Pathogenetic mechanisms in usual interstitial pneumonia/idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, usually fatal, form of interstitial lung disease characterized by failure of alveolar re-epithelialization, persistence of fibroblasts/myofibroblasts, deposition of extracellular matrix, and distortion of lung architecture which ultimately results in respiratory failure. Clinical IPF is associated with a histopathological pattern of usual interstitial pneumonia (UIP) on surgical lung biopsy. Therapy for this disease with glucocorticoids and other immunomodulatory agents is largely ineffective and recent trials of newer anti-fibrotic agents have been disappointing. While the inciting event(s) leading to the initiation of scar formation in UIP remain unknown, recent advances in our understanding of the mechanisms underlying both normal and aberrant wound healing have shed some light on pathogenetic mechanisms that may play significant roles in this disease. Unlike other fibrotic diseases of the lung, such as those associated with collagen vascular disease, occupational exposure, or chemotherapeutic agents, UIP is not associated with a significant inflammatory response; rather, dysregulated epithelial-mesenchymal interactions predominate. Identification of pathways crucial to fibrogenesis might offer potentially novel therapeutic targets to slow or halt the progression of IPF. This review focuses on evolving concepts of cellular and molecular mechanisms in the pathogenesis of UIP/IPF.

Usefulness of quantitative Tc-99m HMPAO and Ga-67 citrate lung scans in detecting pulmonary vascular endothelium damage and lung inflammation in patients with systemic lupus erythematosus: a preliminary report

Pulmonary vascular endothelium damage in 34 patients with systemic lupus erythematosus (SLE) was measured by technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) lung scan. The degree of damage was represented as lung/liver uptake (L/L) ratio. The patients were divided into two subgroups according to the following criteria: (a) clinical features, separated as stable or flare stage and (b) chest X-ray findings separated as positive or negative results. Meanwhile, quantitative gallium-67 citrate (Ga-67) lung scan was performed as Ga-67 uptake index (GUI) to evaluate the severity of inflammation in the SLE lungs. The results show (a) no significant statistical differences in the degree of pulmonary vascular endothelium damage (the L/L ratio on Tc-99m HMPAO lung scan) between the two subgroups according to clinical features or chest X-ray findings and (b) no good correlation between the degree of pulmonary vascular endothelium damage and lung inflammation (GUI on Ga-67 lung scan). In conclusion, the change in pulmonary vascular endothelium damage in SLE may be unrelated to the clinical presentation or chest X-ray findings, and its degree is not related to the severity of pulmonary inflammation.

Interstitial pulmonary fibrosis with and without associated collagen vascular disease: results of a two year follow up

BACKGROUND

Interstitial pulmonary fibrosis is a disease with a highly variable clinical course. To ascertain if an inadequate selection of patients might explain part of this variability, two different groups of patients with interstitial pulmonary fibrosis, those with the "lone" form of the disease (LIPF) and those with associated collagen vascular disorders (AIPF), were studied separately.

METHODS

Twenty consecutive patients (nine with LIPF and 11 with AIPF) were included. Their clinical and radiographic findings and results of pulmonary function tests, gallium-67 lung scanning, and cellular analysis of bronchoalveolar lavage fluid were compared at diagnosis. Moreover, the evolution of LIPF and AIPF was contrasted after a follow up of two years, both groups having received a similar treatment regimen of corticosteroids.

RESULTS

At enrollment, patients with LIPF and AIPF were of similar age, and had similar symptoms and derangement of lung function, but patients with LIPF presented with finger clubbing, more obvious radiographic abnormalities, and a greater percentage of eosinophils in bronchoalveolar lavage fluid. Two years later, patients with LIPF had significantly decreased FVC, FEV1, TLC, TLCO, and PaO2. By contrast, lung function remained unaltered in patients with AIPF. Similarly, when the percentage change from entry to the study was compared, patients with LIPF showed a significant decrease in FVC, FEV1, and PaO2.

CONCLUSIONS

Unlike the patients with AIPF, those with LIPF showed a deterioration in lung function and developed further restrictive impairment and poorer gas exchange. This has implications in their clinical management.

Successful reintroduction of methotrexate after pneumonitis in two patients with rheumatoid arthritis

Two patients are described with severe and progressive rheumatoid arthritis in whom methotrexate was reintroduced despite previous methotrexate related pneumonitis. In both patients a marked improvement in disease control occurred without a recurrence of the pneumonitis.

Pulmonary uptake in 67-gallium citrate scintigraphy-the 'negative heart' sign

Diffuse pulmonary uptake in 67-gallium citrate (67-Ga) scintigraphy occurs in a large number of neoplastic and inflammatory conditions. Discrimination between normal and abnormal 67-Ga uptake over the chest can be difficult and a simple visual method for identifying abnormal studies is described. A series of 39 gallium scintigrams was retrospectively reviewed by the authors and reported without knowledge of the patients' clinical condition. Subsequent clinical follow up was obtained to establish the accuracy of the scintigram interpretation. Comparison of pulmonary uptake with that over the cardiac area is recommended as a simple and reliable method of confirming that the level of pulmonary activity is abnormal. In highly abnormal cases the cardiac area is seen as a 'negative heart' image due to the considerably increased activity in the lungs. This sign is best seen with abnormal diffuse uptake but is also seen with abnormal focal uptake. Care must be taken, as the sign may be masked, if uptake over the cardiac area itself is increased.

Thoracic imaging with gallium-67

In the past, gallium-67 imaging has undergone several ups and downs related to its clinical importance. After a period of initial enthusiasm, its role and indications are now established. At present, there are two fields of clinical interest for ⁶⁷Ga-imaging: (1) mediastinal staging in bronchogenic carcinoma and the staging of malignant lymphoma; (2) assessment of activity in interstitial lung diseases, especially sarcoidosis and inflammatory lung disorders. The advantage of ⁶⁷Ga-imaging is that it is highly sensitive for the detection of neoplastic and inflammatory processes, independent of anatomical barriers. Particularly with the challenge of AIDS, ⁶⁷Ga-imaging will gain increasing importance in the future. The low specificity of gallium for detecting underlying disorders precludes its use as a primary diagnostic tool. Therefore, and because of the cost and radiation load, the indications for application will have to be selected very carefully.

Cryptogenic fibrosing alveolitis: pattern of disease in the lung

The distribution of disease has been studied in 10 patients with histologically confirmed cryptogenic fibrosing alveolitis by means of computed tomography of the lungs, gallium 67 uptake scintigraphy, and ventilation and perfusion scintigraphy. The findings of computed tomography and scintigraphy showed no correlation with the UICC/Cincinnati grades of the plain chest radiographs, even when these were supplemented with information from lateral and oblique chest films. Computed tomography showed subpleural shadowing in every patient except one who had responded well to corticosteroid treatment. Subpleural shadowing was commoner in the inferior and posterior parts of the lung lobes and was commonest in the posterior lower subpleural areas. The central lung showed three types of change--firstly, a dense shadowing, which was sometimes associated with much increased gallium uptake; secondly, dilated smaller airways with small bullae, suggesting airway disease; and, thirdly, gross bullous change.

Mechanisms of pulmonary fibrosis. Spontaneous release of the alveolar macrophage-derived growth factor in the interstitial lung disorders

Interstitial lung disorders are characterized both by a chronic inflammation of the lower respiratory tract that includes increased numbers of activated alveolar macrophages and by increased numbers of fibroblasts within the alveolar wall. Since alveolar macrophages from normal individuals can be activated to release a growth factor for lung fibroblasts (alveolar macrophage-derived growth factor [AMDGF]), we hypothesized that the activated alveolar macrophages within the lower respiratory tract of patients with fibrotic lung disorders might be spontaneously releasing AMDGF. To evaluate this hypothesis, alveolar macrophages (suspension culture, 4 h, 37 degrees) from 65 patients with interstitial lung disorders and 30 control subjects were examined for the spontaneous release of fibroblast growth-promoting activity, with human lung fibroblasts as the target. Whereas none of the controls had macrophages spontaneously releasing a growth-promoting activity for fibroblasts, 82% of the patients with interstitial lung disease had alveolar macrophages that were spontaneously releasing a growth-promoting activity for fibroblasts. In common with AMDGF, the fibroblast growth-promoting activity released by these macrophages eluted from DEAE cellulose at 270 mM NaCl, had a partition coefficient of 0.3 by gel filtration on Sephadex G-50, was distinct from other characterized growth factors, and acted as a progression factor for fibroblast replication in a serum-free complementation test. These data suggest that the expansion of fibroblast numbers within the alveolar structures in interstitial lung disorders may result, in part, from the release of AMDGF by alveolar macrophages stimulated in vivo.

Gallium-67 in the evaluation of sarcoidosis: correlations with serum angiotensin-converting enzyme and bronchoalveolar lavage

Gallium-67 (67Ga) scanning was assessed for its usefulness in the evaluation and follow-up of 54 patients with sarcoidosis, both treated and untreated. Scans were repeated in 23 subjects. Serum levels of angiotensin-converting enzyme (ACE) were determined concurrently in all 54 patients and bronchoalveolar lavage was performed in 29 patients. Gallium-67 scan was effective in the detection and assessment of lesions not revealed by traditional methods of investigation, particularly those affecting the mediastinum, spleen, and salivary glands. The scan also enabled fibrotic lesions, which do not show uptake, to be distinguished from granulomatous lesions, which do--an advantage of prognostic interest particularly in patients with pulmonary lesions. Another merit of 67Ga scanning was that it offered a means of following disease progression in each site. In patients showing spontaneous clearing of disease or receiving treatment the scintigraphic method was more sensitive than serum ACE determination. Scan findings showed a rough correlation with serum ACE but not with bronchoalveolar lavage findings. This suggests that the three markers probably reflect different stages of the granulomatous process. On the strength of this study the indications for gallium scanning in sarcoid patients can be defined more clearly than has previously been possible.