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Ultrasonography (US) is usually the first imaging examination performed to evaluate palpable or visible superficial soft tissue lesions that are common in children. Although clinical assessments, such as age at presentation, clinical course, and overlying skin discoloration, are important for the differentiation of pediatric soft tissue lesions, US allows a specific diagnosis of some typical benign lesions and helps in guiding further investigation since it provides detailed information about the lesion location, characterization including solid versus cystic, vascularity, and compressibility. Therefore, sufficient knowledge of the normal anatomy, proper ultrasonographic techniques, and the imaging findings of common and uncommon soft tissue lesions in children are crucial for accurate assessment and management of patients. In this article, we review the techniques and imaging findings focusing on the ultrasonographic features of a variety of superficial soft tissue lesions detected in children.

To compare the clinical and radiologic findings between perforated and non-perforated choledochal cysts in children.Fourteen patients (mean age ± standard deviation, 1.7 ± 1.2 years) with perforated choledochal cysts (perforated group) and 204 patients (3.6 ± 3.8 years) with non-perforated choledochal cysts (non-perforated group) were included between 2000 and 2019. All patients underwent choledochal cyst excision after ultrasound, CT, or MR cholangiopancreatography. Relevant data including demographics, clinical symptoms, laboratory findings, imaging findings, and outcomes were analyzed. Statistical differences were compared using the Mann-Whitney U test and Fisher's exact test.Choledochal cyst perforation occurred only in children under the age of 4 years. Acute symptoms, including fever (Children with perforated choledochal cysts have characteristic clinical and radiologic findings compared to those with non-perforated choledochal cysts. In young children with choledochal cysts, perforation should be differentiated in cases with acute symptoms, laboratory abnormalities, and characteristic ascites findings.

Objective To evaluate the value of repeat brain magnetic resonance imaging (MRI) in identifying potential epileptogenic lesions in children with initial MRI-negative focal epilepsy. Materials and methods Our Institutional Review Board approved this retrospective study and waived the requirement for informed consent. During a 15-year period, 257 children (148 boys and 109 girls) with initial MRI-negative focal epilepsy were included. After re-evaluating both initial and repeat MRIs, positive results at repeat MRI were classified into potential epileptogenic lesions (malformation of cortical development and hippocampal sclerosis) and other abnormalities. Contributing factors for improved lesion conspicuity of the initially overlooked potential epileptogenic lesions were analyzed and classified into lesion factors and imaging factors. Results Repeat MRI was positive in 21% (55/257) and negative in 79% cases (202/257). Of the positive results, potential epileptogenic lesions comprised 49% (27/55) and other abnormalities comprised 11% of the cases (28/257). Potential epileptogenic lesions included focal cortical dysplasia (n = 11), hippocampal sclerosis (n = 10), polymicrogyria (n = 2), heterotopic gray matter (n = 2), microlissencephaly (n = 1), and cortical tumor (n = 1). Of these, seven patients underwent surgical resection. Contributing factors for new diagnoses were classified as imaging factors alone (n = 6), lesion factors alone (n = 2), both (n = 18), and neither (n = 1). Conclusion Repeat MRI revealed positive results in 21% of the children with initial MRI-negative focal epilepsy, with 50% of the positive results considered as potential epileptogenic lesions. Enhanced MRI techniques or considering the chronological changes of lesions on MRI may improve the diagnostic yield for identification of potential epileptogenic lesions on repeat MRI.

Objective: To evaluate the radiological and clinical fi ndings of congenital cystic neuroblastomas as compared with those of the cystic presentation of neonatal adrenal hemorrhage. Materials and Methods: We analyzed the US (n = 52), CT (n = 24), and MR (n = 4) images as well as the medical records of 28 patients harboring congenital cystic neuroblastomas (n = 16) and neonatal adrenal hemorrhagic pseudocysts (n = 14). The history of prenatal detection, location, size, presence of outer wall enhancement, internal septations, solid portion, calcifi cation, turbidity, vascular fl ow on a Doppler examination, and evolution patterns were compared in two groups of cystic lesions, by Fischer’s exact test. Results: All (100%) neuroblastomas and three (21%) of the 14 hemorrhagic pseudocysts were detected prenatally. Both groups of cystic lesions occurred more frequently on the right side; 11 of 16 (69%) for neuroblastomas and 11 of 14 (79%) for hemorrhagic pseudocysts. The size, presence of solid portion, septum, enhancement, and turbidity did not differ signifi cantly (p > 0.05) between the two groups of cystic lesions. However, tiny calcifi cations (n = 3) and vascular fl ow on color Doppler US (n = 3) were noted in only neuroblastomas. The cystic neuroblastomas became complex solid and cystic masses, and did not disappear for up to 90 days in the three following cases, whereas 11 of the 14 (79%) hemorrhagic pseudocysts disappeared completely and the three remaining (27%) evolved to calcifi cations only. Conclusion: Although the imaging fi ndings of two groups of cystic lesions were similar, prenatal detection, the presence of calcifi cation on initial images, vascularity on color Doppler US, and evolution to a more complex mass may all favor neuroblastomas.

OBJECTIVE: We analyzed the diffusion and perfusion characteristics of acute MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) lesions in a large series to investigate the controversial changes of the apparent diffusion coefficient (ADC) that were reported in prior studies. MATERIALS AND METHODS: We analyzed 44 newly appearing lesions during 28 stroke-like episodes in 13 patients with MELAS. We performed a visual assessment of the MR images including the ADC and perfusion maps, comparison of the ADC between the normal and abnormal areas, comparison of % ADC between the 44 MELAS lesions and the 30 acute ischemic infarcts. In addition, the patterns of evolution on follow-up MR images were analyzed. RESULTS: Decreased, increased, and normal ADCs were noted in 16 (36%), 16 (36%), and 12 (27%) lesions, respectively. The mean % ADC was 102 ± 40.9% in the MELAS and 64 ± 17.8% in the acute vascular infarcts (p < 0.001), while perfusion imaging demonstrated hyper-perfusion in six acute MELAS lesions. On follow-up images, resolution, progression, and tissue loss were noted in 10, 4, and 17 lesions, respectively. CONCLUSION: The cytotoxic edema gradually evolves following an acute stroke-like episode in patients with MELAS, and this may overlap with hyper-perfusion and vasogenic edema. The edematous swelling may be reversible or it may evolve to encephalomalacia, suggesting irreversible damage.

Objective: This study was designed to evaluate follow-up results in terms of patient prognosis for malignant pulmonary nodules depicted as pure groundglass opacity (GGO) lesion observed at high-resolution CT (HRCT). Materials and Methods: Surgical removal for malignant GGO nodules was accomplished in 58 patients (26 men, 32 women; mean age, 57 years; age range, 29-78 years). Patient prognoses were assessed by patient clinical status and the presence of changes in nodule size determined after a follow-up HRCT examination. Differences in patient prognoses were compared for nodule number, size, surgical method, change in size before surgical removal, and histopathological diagnosis by use of Fisher’s exact test and Pearson's chisquared test. Results: Of the 58 patients, 40 patients (69%) were confirmed to have a bronchioloalveolar carcinoma (BAC) and 18 patients (31%) were confirmed to have an adenocarcinoma with a predominant BAC component. Irrespective of nodule size, number, treatment method, change in size before surgical removal and histopathological diagnosis, neither local recurrence nor a metastasis occurred in any of these patients as determined at a follow-up period of 24 months (range; 12-65 months). Of 14 patients with multiple GGO nodules, all of the nodules were resected without recurrence in six patients. In the remaining eight patients, the remaining nodules showed no change in size in seven cases and a decrease in size in one case as determined after a follow-up CT examination. Conclusion: Prognoses in patients with pure GGO malignant pulmonary nodules are excellent, and not significantly different in terms of nodule number, size, surgical method, presence of size change before surgical removal and histopathological diagnosis.

The purpose of this article is to provide a current review of the spectrum of multidetector CT (MDCT) and MRI findings for a variety of cardiac neoplasms. In the diagnosis of cardiac tumors, the use of MDCT and MRI can help differentiate benign from malignant masses. Especially, the use of MDCT is advantageous in providing anatomical information and MRI is useful for tissue characterization of cardiac masses. Knowledge of the characteristic MRI findings of benign cardiac tumors or thrombi can be helpful to avoid unnecessary surgical procedures. Presurgical assessment of malignant cardiac tumors with the use of MDCT and MRI may allow determination of the resectability of tumors and planning for the reconstruction of cardiac chambers.

Purpose: To compare the diagnostic performance of MRI and integrated PET/CT for the preoperative detection of peritoneal carcinomatosis arising from primary ovarian cancer. Materials and Methods: Twenty-three patients with suspected ovarian tumors underwent a contrast-enhanced 1.5 Tesla MRI and a 18F-fluorodeoxyglucose (FDG) PET/CT prior to surgery. The peritoneal cavity was subdivided into six specific sites for a lesion-based analysis. The imaging findings were compared statistically with the histopathological findings using McNemar’s test with Bonferroni’s adjustment and generalized estimation equations. Results: The histopathological results of all 23 patients were confirmed for primary malignant epithelial ovarian cancer. Of the 23 patients, 19 had a total of 83 sites with peritoneal seedings throughout the abdomen and pelvis. The comparison of the patient-based sensitivity, specificity and accuracy of the use of MRI versus PET/CT for the detection of peritoneal carcinomatosis were 95% versus 84% (p > 0.05; N.S.), 50% versus 50% (p > 0.05; N.S.), and 87% versus 78% (p > 0.05; N.S.), respectively. Moreover, the comparison of the lesion-based sensitivity, specificity and accuracy of MRI versus integrated PET/CT were 86% and 75% (p = 0.004), 76% and 84% (p > 0.05; N.S.), and 82% and 78% (p > 0.05; N.S.), respectively. Conclusion: We found that MRI was more sensitive than integrated PET/CT for the detection of preoperative peritoneal carcinomatosis arising from primary ovarian cancer.

We report CT and MR imaging findings for a case of nasal chondromesenchymal hamartoma occurring in a 19-month-old boy. A nasal chondromesenchymal hamartoma is a rare benign pediatric hamartoma that can simulate malignancy. Although rare, knowledge of this entity is essential to avoid potentially harmful therapies.

Purpose: We assessed the diagnostic performance of multidetector-row computed tomography (MDCT) for preoperatively predicting the T-staging of renal cell carcinoma (RCC). Materials and Methods: All the MDCT studies were performed using a 16- or 40-slice MDCT scanner and the three-phase CT images, including unenhanced, corticomedullary and delayed nephrographic phase images. For the differentiation between T2 disease and T3 disease, a four-point scale was used and a score of more than three was considered indicative of T3 disease. The imaging findings were compared with the surgical specimens with using the 2002 TNM staging system. Statistical analysis was performed using McNemar’s test, statistics and receiver operating characteristic (ROC) analysis. Results: The 144 RCCs consisted of 72 T1a, 31 T1b, 16 T2, 13 T3a and 12 T3b. For all the T-staging, the accuracies of MDCT were excellent ( 87%) for both readers. For predicting T3 disease on MDCT, the area under the receiver operating characteristics curve (Az) for both readers was 0.898 and 0.896, respectively. The interreader agreement was almost perfect (= 0.853). Conclusion: MDCT was accurate for preoperatively predicting the T-staging of RCCs, with almost perfect interreader agreement.

Objective To compare the slot-scan digital radiography (SSDR) of the lower extremity region and the computed radiography (CR) method with respect to the image quality and radiation exposure. Materials and Methods We enrolled 54 patients who underwent both the SSDR and CR of the lower extremities. The study evaluated and statistically compared the image quality of four features (outer cortex, inner cortex, trabeculae and intermuscular fat) at six different levels (pelvis, hip, femur, knee, tibia and ankle) between each method. The image quality was evaluated using a visibility scale, and the entrance skin dose was measured using a dosimeter at three different levels of a phantom (hip, knee, and ankle). Results The mean image visibility scale values for the SSDR method were significantly higher than for the CR method. The entrance skin dose for the SSDR method was 278 µGy at each level, compared to the entrance skin doses of the CR method, which were 3,410 µGy for the hip, 1,152 µGy for the knee, and 580 µGy for the ankle. Conclusion Both the image quality and patient entrance skin dose data suggest that the SSDR method is superior to the CR method for the lower extremity musculoskeletal examination.

Purpose: To determine whether a localized low-attenuation (LLA) is induced on a thinsection CT (TSCT) during an acute pulmonary arterial occlusion in pigs. Materials and Methods: In eight pigs, 14 sites of the descending pulmonary artery were obstructed using balloon catheters. The lung TSCTs were obtained immediately after pulmonary artery obstruction (n=13), 10 min (n=10), 30 min (n=14) and 60 min (n=14) after pulmonary artery obstruction at the end of expiration. The TSCTs were also obtained after balloon-deflation at the end of expiration (n=11) and with the balloon-reinflation at inspiration (n=6). Results: Of the 14 sites of pulmonary artery obstruction, 11 (79%) showed LLA. However, LLA progressively became fainter or disappeared on a follow-up CT in seven sites. When the balloon was deflated, 10 of the 11 sites measured showed no change in lung attenuation. After full inspiration, LLA disappeared in three of the six sites. The corresponding areas of LLA on the CT showed a statistically significant increase compared to the baseline CT immediately after inflation (p = 0.021) and 30 minutes after inflation (p =0.041), and after balloon deflation (p =0.036). Conclusion: LLA was induced by acute pulmonary artery obstruction. However, LLA, gradually faded over the 60 minutes following obstruction. LLAs were maintained despite the restoration of pulmonary arterial flow, but disappeared as a result of a full inspiration. Thus, LLA might be caused by air trapping.

Although diseases of the parotid gland are relatively uncommon in children, a variety of benign and malignant lesions may occur and the use of imaging is essential for accurate diagnosis and treatment. Ultrasonography (US) is the initial imaging modality utilized for suspected parotid lesions, and its use may suggest a correct diagnosis in an adequate clinical setting. The use of computed tomography (CT) and magnetic resonance imaging (MRI) are useful for the assessment of large and atypical lesions. These modalities also allow the ability to image the deep parotid lobe and to better define the nature of a lesion. CT is the preferred imaging modality for inflammatory processes, including suspected sialolithiasis, abscesses and salivary duct obstructions, whereas MRI is usually used to evaluate tumors due to excellent anatomic resolution and a lack of ionizing radiation exposure, especially in children. This report describes the imaging findings of various parotid gland lesions in children. Familiarity with these findings will aid in lesion characterization and should facilitate optimal clinical management.

Objective: We wanted to evaluate usefulness of uncovered stent in comparison with covered stent for the palliative treatment of malignant colorectal obstruction. Materials and Methods: Covered (n = 52, type 1 and type 2) and uncovered (n = 22, type 3) stents were placed in 74 patients with malignant colorectal obstruction. Stent insertion was performed for palliative treatment in 37 patients (covered stent: n = 23 and uncovered stent: n = 14). In the palliative group, the data on the success of the procedure, the stent patency and the complications between the two groups (covered versus uncovered stents) were compared. Results: The technical success rate was 89% (33/37). Symptomatic improvement was achieved in 86% (18/21) of the covered stent group and in 92% (11/12) of the uncovered stent group patients. The period of follow-up ranged from three to 319 days (mean period: 116 85 days). The mean period of stent patency was 157 33 days in the covered stent group and 165 25 days in the uncovered stent group. In the covered stent group, stent migration (n = 11), stent fracture (n = 2) and poor expansion of the stent (n = 2) were noted. In the uncovered stent group, tumor ingrowth into the stents (n = 3) was noted. Conclusion: Self-expanding metallic stents are effective for relieving malignant colorectal obstruction. The rate of complications is lower in the uncovered stent group than in the covered stent group.

Objective To describe the sonographic (US) and clinical features of spontaneously reduced small bowel intussusception, and to discuss the management options for small bowel intussusception based on US findings with clinical correlation. Materials and Methods During a five years of period, 34 small bowel intussusceptions were diagnosed on US in 32 infants and children. The clinical presentations and imaging findings of the patients were reviewed. Results The clinical presentations included abdominal pain or irritability (n = 25), vomiting (n = 5), diarrhea (n = 3), bloody stool (n = 1), and abdominal distension (n = 1), in combination or alone. US showed multi-layered round masses of small (mean, 1.5±0.3 cm) diameters and with thin (mean, 3.5±1 mm) outer rims along the course of the small bowel. The mean length was 1.8±0.5 cm and peristalsis was seen on the video records. There were no visible lead points. The vascular flow signal appeared on color Doppler images in all 21 patients examined. Spontaneous reduction was confirmed by combinations of US (n = 28), small bowel series (n = 6), CT scan (n = 3), and surgical exploration (n = 2). All patients discharged with improved condition. Conclusion Typical US findings of the transient small bowel intussusception included 1) small size without wall swelling, 2) short segment, 3) preserved wall motion, and 4) absence of the lead point. Conservative management with US monitoring rather than an immediate operation is recommended for those patient with typical transient small bowel intussusceptions. Atypical US findings or clinical deterioration of the patient with persistent intussusception warrant surgical exploration.