Lung or liver: An imaging dilemma on Tc-99m macroaggregated albumin lung perfusion scintigraphy

A 10-year-old boy having the bronchiectasis was planned for lung resection surgery. Tc99 m macroaggregated albumin (Tc-99m MAA) lung perfusion scintigraphy was performed to assess his lung function before surgery. The planar lung perfusion scintigraphy in [Figure 1] anterior (a) and posterior (b) views showed almost homogenous tracer uptake in whole of the right lung parenchyma with extension toward left upper hemithorax, giving the appearance of liver uptake resulting in imaging dilemma. Left lung did not show tracer activity. High-resolution computed tomography (HRCT) images (c) of the chest region in lung window revealed reduced volume of the left lung parenchyma with multiple cystic areas communicating with bronchi suggestive of bronchiectasis with compensatory hyperinflation of right lung parenchyma and marked mediastinal shift toward to left side. X-ray chest posterioranterior view (d) showed opaque left hemithorax with cystic lucency, volume loss, and marked mediastinal shift toward the left side.

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Figure 1 Planar Tc-99m macroaggregated albumin lung perfusion scintigraphy anterior (a) and posterior (b) images showed almost homogenous tracer uptake in right lung parenchyma with extension towards left upper hemithorax and left lung did not show tracer activity. High-resolution computed tomography image (c) showed multiple cystic areas communicating with bronchi and reduced volume of the left lung parenchyma with compensatory hyperinflation of right lung parenchyma and left-sided mediastinal shift (lung window). X-ray chest posterioranterior view (d) showed opaque left hemithorax with cystic lucency, volume loss, and marked left-sided mediastinal shift

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Perfusion imaging is frequently performed for detection of pulmonary embolism but is also useful to assess lung function before planning for lung resection surgery.[1] Bronchiectasis is a chronic heterogeneous permanent abnormal dilation of medium sized and central bronchi.[2] Initially, most of the patients are treated medically, but the patients with failed medical treatment can be benefited by surgical management by removing the damaged lung parenchyma.[34] Before performing the lung resection surgery, assessment of functioning lung parenchyma and the impact of lung surgery on the patient's pulmonary status are necessary. Perfusion scintigraphy is well-established imaging modality for assessment of the relative contribution of lobar lung function.[5678] In the present case, the appearance of radiotracer (Tc-99m MAA) in the liver region instead of the lung region was masquerading as liver uptake in the acquired scan. It was unusual unless there were some shunts bypassing the lung uptake or faulty radiopharmaceutical preparation. However, by bringing down the image window, it became clear that radiopharmaceutical distribution was in thorax only correlating with lung uptake, and not in the liver. Corresponding X-ray chest and HRCT thorax demonstrated multiple cystic lesions in left lung parenchyma. The resultant image emphasizes the careful inspection of the image before arriving at the conclusion.