Analysis of the Amplitude Changes and Baseline Drift of Respiratory Motion during Liver Stereotactic Body Radiation Therapy Based on Intra-Fraction CBCT

Purpose: To evaluate the amplitude changes and baseline drift of respiratory motion in liver stereotactic body radiation therapy based on intra-fraction cone beam CT (CBCT).Materials and methods: Twenty-four liver SBRT patients underwent a four-dimensional computed tomography (4D CT) scan, inter-fraction cone-beam computed tomography (CBCT), and intra-fraction CBCT to evaluate the amplitude changes and baseline drift of respiratory motion. The amplitude changes were defined as the variations between the amplitude measured in the 4D CT and those measured with fluoroscopy in inter- and intra-fraction CBCT. The baseline drifts were defined as the difference between the liver position errors and the setup errors in inter- and intra-fraction CBCT. Manual registration of the liver contour was performed to obtain liver position errors, and bone registration was performed to obtain setup errors. Meanwhile, the correlation among the liver position errors, the relative diaphragm position, and the amplitude changes was evaluated. Results: The systematic and random errors of the baseline drifts for intra-fraction CBCT in the medial-lateral (ML), superior-inferior (SI), and anterior-posterior (AP) views were 0.99 and 1.6 mm, 2.03 and 2.46 mm, and 1.02 and 2.07 mm, respectively. The corresponding PTV margin was 3.61 mm, 6.8 mm, and 4.00 mm, respectively. The amplitude variation ranged from -169.33% to 65.47% in inter-fraction CBCT and from -171.04% to 60.00% in intra-fraction CBCT. Inter-fraction liver position errors were significantly related to the setup errors. The relative diaphragm position was not statistically related to the baseline drifts in the inter-fraction nor in the intra-fraction. Conclusions: Using intra-fraction CBCT, significant amplitude variations and baseline drifts of respiratory motion were found compared with those in 4D CT. The relative diaphragm position in a single breathing cycle cannot reflect the liver position during dose delivery. At least a 6.8 mm PTV margin in the SI direction is recommended to compensate for the baseline drift.

Severe damage of respiratory muscles in polymyositis

Objectives - to present a clinical case of polymyositis in a 55-year-old man. The patient was admitted with a diagnosis "transient ischemic attack", quickly followed by an acute respiratory failure, which required the continuous use of mechanical ventilation. Other clinical symptoms included: a high diaphragm position up to the 4-th ribs, the concurrent purulent endobronchitis, bilateral pneumonia, pleurisy, multiple atelectasis, myocardial dysfunction with a decrease in ejection fraction to 46%, local hypokinesia according to EchoCG data. Despite the severe condition of the patient, there was not registered any distinct impairment of the proximal limb muscles and an increase in creatinphosphokinase blood level. The antinuclear myositis-specific antibodies, the signs of primary muscular damage according to the limb muscles ENMG data were also absent. The paraneoplastic process was excluded. The results of clinical examination made the diagnosis of polymyositis uncertain. To clarify the cause of the respiratory muscles damage, an intercostal muscle biopsy was performed.It revealed expressed changes in the muscle, with massive necrosis areas, and perivascular lymphohistiocytic infiltration. Conclusion. The described case of polymyositis is extremely rare, has a severe course and is complicated for diagnosis and treatment. In this case, the most informative examination method can be a biopsy of the intercostal muscles, which allows to identify the inflammatory origine of the disease and to determine the pathogenetic therapy.

Agreement between chest ultrasonography and chest X-ray in patients who have undergone thoracic surgery: preliminary results

Background: Chest Ultrasonography (chest US) has shown good sensibility in detecting pneumothorax, pleural effusions and peripheral consolidations and it can be performed bedside. Objectives: The aim of the study was to analyze agreement between chest US and chest X-ray in patients who have undergone thoracic surgery and discuss cases of discordance. Methods: Patients undergoing thoracic surgery were retrospectively selected. Patients underwent routinely Chest X-ray (CXR) during the first 48 h after surgery. Chest US have been routinely performed in all selected patients in the same date of CXR. Chest US operators were blind to both reports and images of CXR. Ultrasonographic findings regarding pneumothorax (PNX), subcutaneous emphysema (SCE), lung consolidations (LC), pleural effusions (PE) and hemi-diaphragm position were collected and compared to corresponding CXR findings. Inter-rater agreement between two techniques was determined by Cohen’s kappa-coefficient. Results: Twenty-four patients were selected. Inter-rater agreement showed a moderate magnitude for PNX (Cohen’s Kappa 0.5), a slight/fair magnitude for SCE (Cohen’s Kappa 0.21), a fair magnitude for PE (Cohen’s Kappa 0.39), no agreement for LCs (Cohen’s Kappa 0.06), high levels of agreement for position of hemi-diaphragm (Cohen’s Kappa 0.7). Conclusion: Analysis of agreement between chest X-ray and chest US showed that ultrasonography is able to detect important findings for surgeons. Limitations and advantages have been found for both chest X-ray and chest US. Knowing the limits of each one is important to really justify and optimize the use of ionizing radiations.