X-Ray Dark-Field Chest Radiography of Lymphangioleiomyomatosis

Introduction:

Lymphangioleiomyomatosis is a condition affecting lung tissue that results in the inability to fully oxygenate the blood, accumulation of fluid in the lungs, and collapsed lungs. The disease cannot be cured completely. The symptomatic management includes improvement of lung function, oxygen therapy, and lung transplantation in individuals with severe disease.

What Is Lymphangioleiomyomatosis?

• It is a lung disease caused by smooth muscle cell growth abnormality in the lungs and lymphatic system.

• The abnormal growth leads to the formation of holes or cysts in the lungs.

• The affected individuals have trouble breathing as it becomes difficult to move air in and out of bronchial tubes.

• Cysts or holes replacing normal lung tissue weakens the ability of the lung to move oxygen into the bloodstream.

• Cysts or holes increase the patient’s risk of developing pneumothorax. A collapsed lung is caused by air or gas build-up.

• There is a risk of developing angiomyolipomas in the kidneys. The condition is harmless but may develop bleeding when enlarged.

• Other regions that are susceptible to benign mass are the retroperitoneum and pelvis.

• Women are predominantly affected by lymphangioleiomyomatosis. The diagnosis happens between 20 to 40 years of life.

• Tuberculosis (TB) is commonly associated with a hereditary form of lymphangioleiomyomatosis.

• Mutation in TSC1 (tuberous sclerosis 1, responsible for hamartin production) and TSC2 (tuberous sclerosis 2, responsible for tuberin production) genes are responsible for disease development.

• In individuals with sporadic forms of lymphangioleiomyomatosis, the inheritance of the disease is not present.

• Lymphangioleiomyomatosis symptoms are known to worsen during the day due to an increase in the size of the benign mass in the afternoon.

What Are the Symptoms of Lymphangioleiomyomatosis?

• Shortness of breath that worsens with time.

• Chest pain.

• Coughs that are associated with phlegm or blood streaks.

• Wheezing.

• Pneumothorax (collapsed lungs).

• Progressive pulmonary cystic changes.

• Pleural effusions (accumulation of fluid in the chest cavity where the lung sites).

• Progressive respiratory failure.

• Abdominal Symptoms:

  • Lymphadenopathy.

  • Cystic lymphatic masses.

  • Chylous ascites are caused by lymphatic obstruction and chylous collection in the thorax.

  • Angiomyolipoma (benign tumor).

  • Nausea.

  • Bloating.

  • Peripheral edema.

  • Urinary symptoms.

How Is Lymphangioleiomyomatosis Diagnosed?

It is important for the accurate detection and treatment of the disease. The diagnostic tests are:

• High-Resolution Computed Tomography (CT) Scans: The scans create a sharp image to look for cysts in the lungs. The scan also helps to look for the presence of fluid in the lungs.

• Plain Radiography: The summation of cystic walls appears as a symmetrical, diffuse, and reticular pattern. Kerley B lines appear due to interstitial edema caused by lymphatic obstruction.

• Lung Function Tests: The test involves breathing into a device called a spirometer. This procedure determines the volume of air inhaled or exhaled and the functioning of the lungs.

• Pulse Oximetry: A small instrument is attached to the finger to analyze oxygen in the blood.

• VEGF-D (Vascular Endothelial Growth Factor D) Blood Test: The test is utilized for measuring VEGF-D hormones in the body. In patients with cyst present in the lungs and a high level of VEGF-D, the disease is confirmed without a need for a biopsy.

• CT Scan or MRI (Magnetic Resonance Imaging) of the Abdomen: An abdominal radiographic image can help in lymphangioleiomyomatosis disease confirmation. The cysts present in lungs appear thin-walled, and air-filled, and are 2 to 50 mm (millimeter) in size. The scan also reveals lymphadenopathy, small pneumothoraces, alveolar hemorrhages, and septal lines. Ground-glass appearance occurs due to the proliferation of smooth muscles.

• Lung Biopsy: A small piece of lung tissue is diagnosed under a microscope. The approach to lung biopsy is of two types:

  • Transbronchial biopsy: A tube known as a bronchoscope is inserted into the lungs through the trachea for obtaining tissue samples. This is an outpatient procedure and does not involve surgery.

  • Video-assisted thoracoscopy: The procedure is conducted under general anesthesia. A small incision is made in the lungs to insert scope for evaluating the lung tissues. The biopsy is also taken for further evaluation.

What Is X-Ray Dark-Field Chest Radiography?

• The dark field chest radiography exhibited standard medical components such as an X-Ray (X radiation) source, collimator, and flat-panel detector, that are combined with an X-ray interferometer.

• The technique can accurately diagnose lung diseases in the early stage using low radiation levels.

• The technique involves recording darker fields. An area scattered or emitted by the object.

• This enables recording minute details in scattered radiation that are often overlooked.

• Patients with respiratory illness are identified with changes in alveolar structure that are detected by increased scattering in regions where tissue and air meet.

• The alveolar integrity is recorded correctly.

• The radiation exposure required is lower due to the requirement of a single X-Ray for imaging.

• The imaging is useful for identifying chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, pneumothorax, lung cancer, and pneumonia.

• Dark-field X-ray has a high sensitivity to microstructural parameters of the lungs.

• X-ray dark-field chest radiography exhibited a low and inhomogeneous signal in patients with lymphangioleiomyomatosis.

• There were focal areas with signal loss in certain areas of lymphangioleiomyomatosis-affected patients.

What Are the Treatment Options for Lymphangioleiomyomatosis?

There is no cure for the disease but the symptoms are managed with the treatment of lymphangioleiomyomatosis.

• mTOR (mammalian target of rapamycin) inhibitors like sirolimus or everolimus are the primary treatment options.

• mTOR inhibitors limit lymphangioleiomyomatosis cell proliferation by inhibiting the activated mTOR pathway. This causes improvement in lung function in the short term by shrinking masses and chylous effusions.

• Sirolimus is also used to shrink large masses of angiomyolipomas in the kidney.

• In patients with rapidly progressing disease progesterone is used.

• Oxygen therapy.

• Inhaled medications for improving airflow in the lungs.

• Several procedures are used to shrink angiomyolipomas and remove fluid from the chest.

• Studies are ongoing for use of rifampicin in the treatment of lymphangioleiomyomatosis.

• A lung transplant is utilized in patients with a severe form of lymphangioleiomyomatosis that requires oxygen support.

• The common complications that occur post-lung transplant are native lung pneumothorax and postoperative chylothorax.

• Angiomyolipomas that are less than 4 cm (centimeter) in diameter are followed up for one to two year intervals with ultrasound.

Conclusion:

X-ray dark-field radiography is newer diagnostic imaging that helps detect various lung conditions by imaging scattered radiation that contains finer details. The amount of radiation required is less as a single image is enough for diagnosis. The procedure enables the identification of lung diseases in the early stage. Therefore, helping with the effective management of the disease.