Usefulness of 99mTc-ASC lymphoscintigraphy and SPECT/CT in the evaluation of rare lymphatic disorders: Gorham-Stout disease, lymphangioma, and lymphangioleiomyomatosis

Lymphoscintigraphy findings in patients with chylothorax: influence of biochemical parameters

BACKGROUND

Chylothorax is a condition that can be challenging to diagnose due to its nonspecific clinical presentation. Several biochemical parameters of chylous pleural effusion have been identified as important indicators for the diagnosis of chylothorax. Lymphoscintigraphy is utilized to assess chylothorax and determine the location of chyle leakage. The present study aimed to evaluate the correlation between the biochemical parameters of chylous pleural effusion and 99mTc-dextran (99mTc-DX) lymphoscintigraphy in diagnosing chylothorax.

MATERIAL AND METHODS

A total of 120 patients were enrolled in the study, 83 of the patients with unilateral chylothorax, and 37 with bilateral chylothorax. All patients underwent both 99mTc-DX lymphoscintigraphy and pleural effusion laboratory analysis. The 99mTc-DX lymphoscintigraphy images were categorized as positive or negative groups based on the presence or absence of abnormal radioactive tracer accumulation in the thorax, respectively. The biochemical parameters of the two groups were subsequently compared.

RESULTS

Among these patients, 101 (84.17%) had exudative effusions, while 19 (15.83%) had transudative effusions, as determined by the levels of pleural effusion protein, lactate dehydrogenase and cholesterol. Abnormal tracer accumulation in thorax was observed in 82 patients (68.33%). Our findings indicated that lymphoscintigraphy results were not associated with exudative and transudative chylothorax (P = 0.597). The lymphoscintigraphy positive group displayed significantly higher levels of pleural effusion triglyceride and pleural effusion triglyceride/serum triglyceride ratio in all biochemical parameters, compared to the negative group (P = 0.000 and P = 0.005). We identified cutoff values of 2.870 mmol/L for pleural effusion triglycerides and 4.625 for pleural effusion triglyceride/serum triglyceride ratio, respectively, which can facilitate differentiating the positive and negative cases on lymphoscintigraphy.

CONCLUSION

Lymphoscintigraphy technique is a dependable diagnostic tool for the qualitative assessment of chylous pleural effusion. Higher pleural effusion triglyceride level and pleural effusion triglyceride/serum triglyceride ratio indicate a positive result in patients with chylothorax on lymphoscintigraphy, with the cutoff values of 2.870 mmol/L and 4.625 aiding in the diagnosis.

Lymphoscintigraphic Indications in the Diagnosis, Management and Prevention of Secondary Lymphedema

Secondary lymphedema is caused by damage to the lymphatic system, often following an oncological tumor removal intervention, or even by an accident. The diagnosis of lymphedema is not easy, because the disease can also be confused with other clinical manifestations (for example, venous insufficiency edema), though an experienced Lymphologist is usually able to diagnose it with good accuracy. To confirm the diagnosis, it is often necessary to resort to specialist imaging tests for an anatomo-functional definition of the pathology. Among these, lymphoscintigraphy is confirmed as the “gold standard” procedure for the diagnosis of lymphedema. Lymphoscintigraphy has been included in the Italian Guidelines by the Ministry of Health.

Imaging Findings of Thoracic Lymphatic Abnormalities

The lymphatic system plays an important role in balancing fluid compartments in the body. It is disrupted by various disease processes in the thorax, including injury to the thoracic lymphatic duct after surgery, as well as malignancy and heart failure. Because of the small size of lymphatic vessels, imaging of the lymphatics is relatively difficult, and effective imaging methods are still being optimized and developed. The standard of reference for lymphatic imaging has been conventional lymphangiography for several decades. Other modalities such as CT, noncontrast or contrast-enhanced MRI, and lymphoscintigraphy can also demonstrate lymphatic abnormalities and help in treatment planning. Imaging findings associated with lymphatic abnormalities can be seen in the pulmonary parenchyma, pleural space, and mediastinum. In the pulmonary parenchyma, common findings include interlobular septal thickening as well as reversal of lymphatic flow with intravasation of contrast material into pulmonary lymphatics. In the pleural space, findings include chylous pleural effusion and occasionally nonchylous pleural effusion. In the mediastinum, thoracic duct leak, plexiform thoracic duct, lymphatic malformations, and lymphangiectasis may occur. Management of chylothorax includes conservative or medical treatment, surgery, and interventional radiology procedures. The authors discuss thoracic lymphatic anatomy, imaging manifestations of lymphatic abnormalities in the various anatomic compartments, and interventional radiology treatment of chylothorax. Radiologists should be familiar with these imaging findings for diagnosis and to help guide appropriate management. ^©RSNA, 2022.

"A case of vanishing bone disease complicated by chylothorax- diagnosis and treatment"

A 16-year old girl with Gorham-Stout disease is presented. She had progressive replacement of the bones of her left arm and shoulder girdle by fibroadipose tissue and numerous proliferated, non-neoplastic, lymphatic channels. The clinico-pathologic features of this condition are discussed, as are its possible complications and available therapeutic modalities.

The relationship between the drainage function of inguinal lymph nodes and unilateral pelvic cancer-related lymphedema: A retrospective analysis

The aim of this study was to investigate the relationship between iliolumbar lymph nodes (LNs), inguinal LNs, and unilateral pelvic cancer-related lymphedema by retrospective analysis of lymphoscintigraphy data.Ninety-six patients (3 men and 93 women; mean age, 53.3 ± 11.3 years) with pelvic cancer-related lymphedema were enrolled in this retrospective study. Lymphoscintigraphy was performed at 1 hour and 4 to 6 hours after injection. The visualization of inguinal LNs and iliolumbar LNs were recorded.According to statistical analysis, the display of inguinal LNs in lymphoscintigraphy has a significant negative correlation with ipsilateral lower limb lymphedema (P < .01, r = -0.561). However, there is no correlation between the show of iliolumbar LNs and ipsilateral lower extremity lymphedema (P = .056, r = -0.138). When lymphoscintigraphy was performed at 1 hour after injection, there were 13 out of 96 patients without inguinal LNs revealed on imaging, but at 4 to 6 hours after injection, inguinal LNs were seen in lymphoscintigraphy.The drainage function of inguinal LNs has a significant negative correlation with ipsilateral pelvic cancer-related lymphedema. Treatment dedicated to restoring the drainage function of LNs in the inguinal region may effectively relieve lymphedema. The image acquisition at 4 to 6 hours after injection is necessary for significant additional information.