Validation of computed tomography angiography as a complementary test in the assessment of renal artery stenosis: a comparison with digital subtraction angiography.

BACKGROUND: Renal artery stenosis is an important cause of hypertension in children, accounting for 5-10% of cases. When suspected, noninvasive imaging options include ultrasound (US), computed tomography (CT) angiography and magnetic resonance (MR) angiography. However, digital subtraction angiography (DSA) remains the gold standard. OBJECTIVE: To investigate the accuracy and inter-reader reliability of CT angiography in children with suspected renal artery stenosis. MATERIALS AND METHODS: This is a retrospective study of patients suspected of having renal artery stenosis evaluated by both CT angiography and DSA between 2008 and 2019 at a tertiary pediatric hospital. Only children who underwent CT angiography within 6 months before DSA were included. CT angiography studies were individually reviewed by two pediatric radiologists, blinded to clinical data, other studies and each other's evaluation, to determine the presence of stenosis at the main renal artery and 2nd- and 3rd-order branches. The sensitivity, specificity and accuracy were calculated using DSA as the reference. The effective radiation dose for CT angiography and DSA was also calculated. Kappa statistics were used to assess inter-reader agreement. RESULTS: Seventy-four renal units were evaluated (18 girls, 19 boys). The patients' median age was 8 years (range: 1-21 years). Overall, CT angiography was effective in detecting renal artery stenosis with a sensitivity of 85.7%, specificity of 91.5% and accuracy of 88.9%. There was moderate inter-reader agreement at the main renal artery level (k=0.73) and almost perfect inter-reader agreement at the 2nd/3rd order (k=0.98). However, the sensitivity at the 2nd- and 3rd-order level was lower (14.3%). CT angiography provided excellent negative predictive value for evaluating renal artery stenosis at the main renal artery level (90.1%) and at the 2nd- or 3rd-order branches (82.7%). The median effective dose of CT angiography studies was 2.2 mSv (range: 0.6-6.3) while the effective dose of DSA was 13.7 mSv. CONCLUSION: CT angiography has high sensitivity and specificity at the main renal artery level with a lower radiation dose than previously assumed. Therefore, it can be used as a diagnostic tool in patients with low to medium risk of renal artery stenosis, and as a screening and treatment planning tool in patients at high risk.

Recurrent Metastatic Ewing Sarcoma Involving Only in the Muscles of Extremities Shown on FDG PET/CT.

ABSTRACT: Ewing sarcoma is the second most common osseous malignancy in pediatric patient. Metastasis is common due to its aggressive nature, with 25% of patients with metastasis at diagnosis, commonly to the lungs, bone, or bone marrow. Muscle metastasis is uncommon. We report FDG PET/CT findings of multifocal muscle metastases of recurrent Ewing sarcoma in the extremities without lung and bone involvement in a 6-year-old boy.

FDG PET/CT Findings of Renal Cell Carcinoma Arising From a Transplanted Kidney in a Pediatric Patient.

ABSTRACT: A 12-year-old girl presented with a history of kidney transplant complicated by posttransplant lymphoproliferative disease. A solid mass was found in the lower pole of the transplanted kidney, concerning for posttransplant lymphoproliferative disease. However, biopsy confirmed papillary renal cell carcinoma. FDG PET/CT showed increased activity in the known renal cell carcinoma in the renal allograft.

Cerebellar Metastasis From Thyroid Carcinoma With Prominent 123 I Uptake But Less Impressive MRI Findings in a Pediatric Patient.

ABSTRACT: Papillary thyroid carcinoma in childhood frequently presents with locoregional lymph node metastases. The distant metastases often involve lungs and the bone, whereas brain metastasis is rare. We report a case of classic variant-papillary thyroid carcinoma with right cerebellar metastasis in a 7-year-old girl on a 123 I SPECT/CT study. A brain MRI on the same day shows a tiny millimetric enhancing nodule in the right cerebellum with no perceivable perilesional edema, confirming the 123 I scan findings.