When upper airway obstruction is suspected in pediatric cases, the primary choice for imaging is lateral radiography of the upper airway. While this examination is straightforward, it may not yield useful findings depending on the imaging conditions. Since the lumen of the upper airway can easily change, dynamic assessment through laryngoscopy is valuable for diagnosis. Laryngoscopy requires trained personnel and is limited to certain facilities, but it offers the advantage of being able to be performed without anesthesia and is more convenient compared to CT or MRI.

In this context, we compare lateral upper airway radiography and laryngoscopy in the diagnosis of upper airway obstruction in pediatric patients, and provide an overview of the differences in and characteristics of their roles. In addition, we will present the results of a comparison of the diagnostic rates of both examinations for various conditions.

Advanced imaging technology and new insights in diagnostic imaging are widely applied in pediatric thoracic surgery. Examples include three-dimensional imaging in thoracoscopic and robotic surgery, preoperative assessment of the pulmonary vessels by three-dimensional computed tomography, identification of lung intersegmental borders using infrared thoracoscopy with indocyanine green, optimal window setting on computed tomography to measure the inner diameter of the trachea, simulated slide tracheoplasty for congenital tracheal stenosis using three-dimensional printed models, computational fluid dynamics assessment of congenital tracheal stenosis, and lymphatic imaging techniques in the management of chylothorax.

Computed tomography (CT) is an essential diagnostic tool for pediatric respiratory medicine, and it continues to evolve in terms of hardware performance, imaging techniques, and image reconstruction or post-processing software. This has created many challenges for non-radiology care providers unfamiliar with radiological terms and images. For such care providers, it may not be easy to find the time to review all this information from scratch. This article aims to cover topics related to CT, from general to those specific to pediatric patients, and support independent learning for non-radiology care providers. This article also discusses ultrasound and magnetic resonance imaging, which have been considered less suitable for the imaging of the respiratory tract. Thanks to advancements in technology, however, their use in the airway and lung has now proven to be promising.

Ultrasound for the respiratory tract has been considered useful in various settings of pediatric practice. Important findings include A lines (linear high-echogenicity lines parallel to the pleura), B lines (lines perpendicular to the pleura), and lung sliding (movement of the pleural line in synchrony with breathing).

Appropriate tracheal intubation is confirmed using the snowstorm/bullet signs and the absence of the double tract sign. Pneumothorax is characterized by the disappearance of lung sliding and B lines, and the presence of a lung point.

Even a small amount of pleural fluid is also detectable. Effusion presents as anechoic fluid in the pleural cavity, while in contrast, empyema has higher echogenicity.

Ultrasound further allows for direct observation of pulmonary parenchyma adjacent to the parietal pleura, enabling detection of conditions such as pneumonia, abscess, tumors, and malformations. Indirect findings such as B lines may also be helpful for the diagnosis of bronchiolitis and pulmonary edema. In transient tachypnea of the newborn, delayed absorption of lung fluid is demonstrated as the presence of B lines. In respiratory distress syndrome, an admixture of A lines and B lines is found in mild cases and a white lung pattern without A lines is found in severe cases. These observations can be applied to determination of the need for surfactant administration.

Ultrasound (US) remains the modality of choice for routine antenatal pulmonary imaging. Fetal magnetic resonance imaging (MRI) is a valuable complementary tool when US is inadequate or gives unclear results. The purpose of fetal MRI is to confirm US findings or acquire additional findings.

The primary MRI techniques used are single-shot fast spin echo (SSFSE) or balanced steady state free precession (bSSFP). These rapid pulse sequences can reduce fetal motion artifacts.

MRI is also useful for the evaluation of pulmonary abnormalities. The respiratory function of the newborn is dependent on sufficient lung volume, sufficient fetal lung fluid, and fetal breathing movements. The MRI assessment of fetal pulmonary growth and maturation consists of two diagnostic elements: lung volume and lung signal intensity. Measurement of ADC (apparent diffusion coefficient) in cases with pulmonary abnormalities will be investigated in future work.

Herein, we describe our technique for fetal MRI and illustrate some important and high frequent fetal pulmonary diseases.

Pyogenic spondylodiscitis is a rare disease; methicillin-resistant Staphylococcus aureus (MRSA)-associated cases in children are even rarer. We present a case of pyogenic vertebral osteomyelitis diagnosed using magnetic resonance imaging (MRI) in which MRSA was the suspected causative agent. A 12-year-old girl arrived at our hospital complaining of back pain and fever. Blood tests revealed mild inflammation, with MRI revealing lesions of the L1/L2 vertebrae and intervertebral disks, and she was diagnosed with pyogenic spondylodiscitis. MRSA was found in the patient’s blood culture, and vancomycin hydrochloride was administered to the patient for 6 weeks. Her back pain and fever quickly subsided, and the symptoms did not recur. Although the patient was successfully treated with conservative therapy alone, other adult MRSA-related cases are nonresponsive to conservative treatment and therefore, require surgery. Given that the diagnosis of pyogenic spondylodiscitis can be difficult in some cases due to its nonspecific symptoms and blood test findings, it should be considered in the differential diagnosis for patients who present with fever and back pain.

Ultrasound elastography is a noninvasive method for evaluating tissue elasticity. The application of this technique has expanded to the kidneys. While kidney biopsy is the gold standard method used for assessing disease activity in kidney diseases, the technique is highly invasive. Hence, less invasive evaluating methods are required. In this study, we compared the acute phase and convalescent phase of post-streptococcal acute glomerulonephritis (PSAGN) by shear wave velocity (SWV) to examine whether disease stage and SWV are related. We compared two cases of PSAGN (two boys aged 4 and 6 years) admitted to our hospital due to PSAGN-associated kidney function impairment. We observed that the acute phase SWV values measured during hospitalization were significantly higher than those measured during convalescence (after discharge from the hospital when the urinary findings improved). It is speculated that the fluctuations in SWV values observed in this study can be attributed to kidney hemodynamics and inflammation occurring in the disease’s acute phase. Although further large sample studies are necessary in the future, our results indicate that elastography may enable noninvasive evaluation of the activity of acute glomerulonephritis.