Magnetic Resonance Imaging Features of Congenital Infantile Fibrosarcoma.

Background Congenital/infantile fibrosarcoma is a rare soft tissue tumor presented in early age of life. It should be considered in the differential diagnosis of the large soft tissue masses especially in the extremities at the age of infancy. These tumors frequently are misdiagnosed at birth as hemangioma. Histologically, they can resemble their adult counterparts and they are characterized by the chromosomal translocation t(12;15) (p13;q25) resulting in the ETV6-NTRK3 gene fusion. Objective A retrospective review of the MRI features of histopathology-proven congenital/infantile fibrosarcoma provides our own institutional experience and supports the limited radiology literature written about this disease. Material and method The list of our patients is obtained after reviewing our radiology and pathology database in the period between June 1st, 2007 and May 31st, 2017 (10 years) at King Faisal Specialist Hospital & Research Center, Riyadh. Phrases used to search in our MRI examinations database are: congenital infantile fibrosarcoma, infantile fibrosarcoma, juvenile fibrosarcoma, soft tissue sarcoma, malignant soft tissue mass, sarcomatous soft tissue mass, fibrosarcoma, spindle cell sarcoma, myomatous sarcoma. Result In our database and picture archiving and communication system (PACS) during the period of the study, the word (fibrosarcoma) was mentioned in the radiology report of 182 patients. Only four cases were histopathologically proven to be a congenital/infantile fibrosarcoma and had completed their own MR exams - three of them were primary/new cases, males with an age range between 0 days and 5 months (median age: 5 months). The fourth case was a female with a history of 1st presentation at the age of one month and proved by histopathology examination but there was no available imaging at that time; however, tumor recurrence in the same patient was at the age of 4 years with available MR imaging and pathology sample. Conclusion Congenital infantile fibrosarcoma is a rare entity that has no specific MRI findings. However, it should be always considered as part of the differential diagnosis of congenital soft tissue masses with aggressive behavior.

Twinkle artifact in renal ultrasound, is it a solid point for the diagnosis of renal stone in children?

Background: Twinkle artifact, also known as color Doppler comet-tail artifact, occurs behind very strong, granular, and irregular reflecting interfaces such as crystals, stones, or calcification. This is visualized as a random mixture of red and blue pixels in the high-frequency shift spectrum located deep to the interface. Study results have suggested that the sonographic twinkling artifact may aid in the detection of renal stones with a variety of reference standard imaging modalities, including abdominal radiography, excretory urography, gray-scale sonography, and CT. Material and methods: Our retrospective observational study included children who had undergone abdomen/renal ultrasound for kidneys stones in our radiology department between 2013 and 2019. Presence of the twinkle artifact, and stone numbers and sizes were documented. CT examinations done <3 months prior to or after US were retrospectively assessed to confirm the presence of kidney stones as a reference standard. Results: Thirty-three abdominal renal US scans of 33 patients (21 males, 12 females) fulfilled the entry criteria. The interval between the US and CT was <3 months for all patients. The median overall age of the patients was 4 years (IQR: 3.125, range: 1- 165 months), The median number of days between the US and CT was 13 (IQR: 26, range: 0-81 days). US detected 33 hyperechoic foci suspected to be stones; 26 were confirmed as true positive (i.e. showed the twinkle artifact and were seen in CT), 4 were false positive (showed the twinkle artifact but were not seen in CT), and 3 were false negative (did not show the twinkle artifact but were seen in CT). The overall median stone size was 2 mm in the right kidney, and 5 mm in the left kidney (IQR: 6,11 mm), respectively. Twinkle artifact sensitivity was found to be 89.7% (95% CI 39.574%-90%). The twinkle artifact was assessed in all true-positive stones, determining a relatively high PPV of 26/29 (86.7%) for the twinkle artifact. The twinkle artifact was not dependent on stone size. Specificity for the twinkle artifact could not be calculated due to a lack of true negatives. Conclusion: The twinkle artifact is a sensitive US tool for detecting pediatric kidney and ureter stones, but with a small risk of false positive findings.

Solitary liver lesions in children: interobserver agreement and accuracy of MRI diagnosis.

PURPOSE: The purpose of the study was to evaluate interobserver agreement (IOA) and accuracy of magnetic resonance imaging (MRI) diagnosis of pediatric solitary liver lesions (PSLLs). METHODS: Fifty consecutive MRIs performed for PSLLs were reviewed to assess IOA and agreement between consensus imaging diagnosis and final diagnosis indicating accuracy using kappa statistics. RESULTS: In 39/50 cases, the MRI diagnosis given by two readers matched with substantial IOA (kappa=0.7294). There was moderate agreement (kappa=0.60784) between consensus imaging diagnosis and the final diagnosis in 10 cases with available pathology. CONCLUSION: Based on the limited available pathology and follow-up, we found that most PSLLs can be noninvasively characterized and accurately diagnosed using MRI.