Abdominal lymphatic system visibility, morphology, and abnormalities in children as seen on routine MCRP and its association with immune-mediated diseases.

PURPOSE: (1) To assess the visibility and diameters of the thoracic duct (TD) and cisterna chyli (CC) on MR cholangiopancreatography (MRCP) in children. (2) To evaluate for the presence of any lymphatic abnormalities and assess their association with diseases in which the immune system is implicated in etiopathogenesis. METHODS: This retrospective study included 142 MRCPs performed in children 8-17 years old and without prior surgeries. Two radiologists reviewed all exams for visibility and diameters of the TD and CC, and presence of abnormal lymphatic collaterals. TD and CC diameters in various disease processes were compared using Student's t tests. The association of collaterals with immune-mediated diseases was assessed using Fisher's exact tests. RESULTS: The TD and CC were seen in 134/142 (93.7%) cases with mean diameter of 3.25 ± 1.07 mm and 126/142 (88.7%) cases with mean diameter of 4.55 ± 1.37 mm respectively. The mean diameter of CC was larger in patients with portal hypertension (p = 0.021). There were no significant differences in the TD and CC diameters between immune-mediated and non-immune-mediated diseases. Retroperitoneal collaterals were seen in 41/142 (28.8%) of cases and were associated with both portal hypertension (p = 0.0019) and immune-mediated diseases (p = 0.0083). CONCLUSION: The TD and CC can be visualized in the majority of children on routine MRCP images, and CC has larger diameter in patients with portal hypertension. The association of collaterals with immune-mediated diseases supports a potential role of the lymphatic system in the etiopathogenesis of immune-mediated diseases. KEY POINTS: • The lymphatic system has been increasingly implicated in a number of inflammatory and immune-mediated diseases. • The abdominal lymphatic system can be visualized in the majority of children above 8 years on routine MRCP images. Similar to adult studies, the cisterna chyli is significantly larger in children with portal hypertension. • Retroperitoneal lymphatic collaterals, seen in 29% children, are associated with immune-mediated diseases, which supports the potential role of the lymphatic system in the pathogenesis of immune-mediated diseases.

The role of MRA in pediatric sickle cell disease with normal transcranial Doppler imaging velocities.

PURPOSE: The purpose of this study was to determine the additional information provided by Magnetic Resonance Angiography (MRA) in pediatric sickle cell disease (SCD) patients with normal Transcranial Doppler imaging (TCDI) examinations. METHODS: This cohort study included all pediatric SCD patients over an 18-year period who had no history of stroke and had normal TCDI examinations and subsequently underwent MRA. Routine TCDI inclusive of time-averaged mean of maximum velocities (TAMMV) were assesses and compared with tortuosity on MRA and silent infarct on MRI. RESULTS: 86 children (52.3% female; mean age 8.7 ± 3.5years) were included. There were 77 patients (89.5%) with Hb-SS disease and 9(10.4%) with HB-S beta-thalassemia. All patients had normal TAMMV (<170 cm/s) on TCDI. 76/86 (88.3%) patients also had one or more velocity readings <70 cm/s, albeit none in the middle cerebral arteries. Posterior cerebral arteries had the lowest velocities, <70 cm/s in 51.7% (right) and 60.9% (left). Silent MRI infarcts were seen in 27/86 (31.4%) patients. No new lesions were identified on follow-up MRI. Although mild vascular tortuosity was appreciated in 31/86 (36.0%) of the patients, there were no steno-occlusive lesions in the circle of Willis. CONCLUSIONS: TCDI and MRA are routinely performed for non-invasively evaluating intracranial vascular abnormalities in children with SCD. In SCD children with no history of TIA or stroke, MRA following a normal TCDI examination is unlikely to show vascular abnormality. However, almost a third of these patients show silent infarcts on MRI, unassociated with MRA changes.

Diagnostic Performance of a Sonographic Volume and Solid Vascular Tissue Score (VSVTS) for Preoperative Risk Assessment of Pediatric and Adolescent Adnexal Masses.

STUDY OBJECTIVE: To evaluate the diagnostic performance of a Volume and Solid Vascular Tissue Score (VSVTS) for preoperative risk assessment of pediatric and adolescent adnexal masses. DESIGN: A retrospective cohort study comprised of all female individuals who presented with an adnexal mass that was managed surgically between April 2011 and March 2016. SETTING: The Hospital for Sick Children (Toronto, Ontario, Canada). PARTICIPANTS: Female individuals 1-18 years of age who presented to a large tertiary pediatric hospital with an adnexal mass that was managed surgically. MAIN OUTCOME MEASURES: Main outcome measures included diagnostic performance of the VSVTS for malignancy via sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-), and receiver operating characteristic area-under-the-curve (AUC) analysis. RESULTS: A total of 179 masses in 169 subjects were included. The malignancy rate was 10.6%. The AUC for the VSTVS was 0.919. A VSTVS cut-off value of 4 achieved a sensitivity of 79% (95% CI 0.54-0.93), specificity of 88% (95% CI 0.82-0.93), PPV of 0.44 (95% CI 0.33-0.56), NPV of 0.97 (95% CI 0.94-0.99), LR+ of 6.77 (95% CI 4.18-10.97), and LR- of 0.24 (95% CI 0.10-0.57). CONCLUSIONS: A sonographic scoring system based on the volume and presence of solid vascular tissue improves PPV for preoperative risk stratification of adnexal masses in the pediatric and adolescent population compared to existing ultrasound-only approaches. Further prospective research is needed to determine how best to incorporate components of such scoring systems into clinical management algorithms.