Ramiro J. Hernandez

Carpal length in children: A useful measurement in the diagnosis of rheumatoid arthritis and some congenital malformation syndromes

The distance between the midpoint of the distal radial epiphyseal growth plate and the proximal end of the third metacarpal offers a useful measure for determining wrist size. Standards of this distance as compared to intermetacarpal width and second metacarpal length are presented. These measures (or ratios) should be useful in evaluating patients with juvenile rheumatoid arthritis and a number of congenital malformation syndromes, particularly when the carpals are still not fully ossified. Shortening of the carpus occurs in multiple epiphyseal dysplasia, the otopalatodigital syndromes, Turner syndrome, arthrogryposis, and in juvenile rheumatoid arthritis. A relatively large carpus is present in achondroplasia.

MR evaluation of liver iron overload

Children and young adults with hemolytic anemias requiring frequent transfusions develop increased liver iron content. We evaluated 15 chronically transfused children with sickle cell disease to determine whether spin-echo magnetic resonance (MR) imaging was useful in assessing the degree of iron overload. Quantitative MR parameters were correlated with liver biopsy iron determinations and serum ferritin levels. The best predictor of liver iron was the ratio of the intensities between the liver and paraspinal musculature on somewhat T1 weighted sequence (repetition time 0.5 s, echo time 28 ms). R2 = 0.58. Magnetic resonance was able to separate those patients with liver iron levels >100 μg/mg (intensity ratio ∼0.4). from those with levels <100 μg/mg (intensity ratios near I). However. MR was unable to quantitate liver iron in patients with values ranging from 100 to 400 μg/mg since similar intensity ratios were present in this range. Thus. MR provides a qualitative rather than quantitative assessment of liver iron overload.

Magnetic resonance imaging appearance of the muscles in childhood dermatomyositis

Documentation of muscle involvement in a child thought to have dermatomyositis may require the performance of invasive procedures such as electromyography and/or muscle biopsy. We describe four patients with dermatomyositis in whom magnetic resonance imaging (MRI) demonstrated the muscle involvement. The involved muscles had increased signal intensity on the T2-weighted images (SE 2500/80) and normal appearance on the T1-weighted images (SE 600/20). The involvement of the muscles was not uniform. There was good correlation between the distribution of muscle involvement by MRI and functional testing. Follow-up MRI scans in patients with favorable outcome demonstrated that the affected muscles had returned to normal signal intensity. Although the MRI findings are not specific, in the proper clinical context they may be helpful in establishing the diagnosis of dermatomyositis. MRI may also be used in establishing an appropriate muscle biopsy site. In addition, MRI may be used for monitoring the progress of the disease.

Common and uncommon vascular rings and slings: a multi-modality review

Vascular rings and pulmonary slings are congenital anomalies of the aortic arch/great vessels and pulmonary arteries, respectively, that commonly present early during infancy and childhood with respiratory and/or feeding difficulties. The diagnosis of these conditions frequently utilizes a multi-modality radiological approach, commonly utilizing some combination of radiography, esophagography, CT angiography and MR angiography. The purpose of this pictorial review is to illustrate the radiological findings of common and uncommon vascular rings and pulmonary slings in children using a state-of-the-art multi-modality imaging approach.

«Dilatation» of the left renal vein on computed tomography in children : a normal variant

Compression of the left renal vein (LRV) between the superior mesenteric artery and the aorta is thought to be a cause of hematuria, periureteral and gonadal varices, and varicocele (“Nutcracker phenomenon”). Previous investigators have suggested that this diagnosis can be made on computed tomography when the LRV ratio ≥1.5 (the diameter of the LRV proximal to the aorto-mesenteric angle divided by the diameter of the LRV distal to the aorto-mesenteric angle). This study was designed to establish the normal range for the LRV ratio on CT in children. The LRV ratio was measured in thirty-nine consecutive children undergoing intravenously enhanced CT of the abdomen. None of the children had hematuria on urinalysis immediately before or after the CT. Children with any known abnormality involving the kidneys, adrenal glands, IVC, or renal or gonadal veins were excluded. The patients ranged in age from 3.4 to 18.5 years (mean=10.6 years). LRV ratio ranged from 0.78 to 2.00 (mean=1.46; S.D.=0.312). Twenty of the 39 children (51.3%) had a LRV ratio ≥1.50. The conclusion is that the normal range for the LRV ration is too wide for it to be useful in diagnosing LRV entrapment and that a LRV ratio ≥1.5 on CT is normal in children.

The effect of synthetic androgens on the hypothalamic-pituitary-gonadal axis in boys with constitutionally delayed growth.

Serial concentrations of basal serum LH, FSH, testosterone, and LH and FSH responses to intravenous gonadotropin-releasing hormone were measured before and during six months of administration of fluoxymesterone or oxandrolone in 14 boys with constitutionally delayed growth and adolescence, in order to assess the effects of these androgens on maturation of the hypothalamic-pituitary-gonadal axis. Before therapy all boys had normal hormonal responses based on bone age. At the end of six months therapy 10 of the 14 boys had lower LH responses (34 to 89% reduction) to GnRH without consistent changes in FSH responses. With both androgens, there there was significant suppression of both basal serum FSH and testosterone. Eleven boys were restudied six months after completion of therapy; basal serum LH, FSH, and testosterone and responses to GnRH were equal to or greater than pretreatment levels, indicating recovery or progressive maturation of the HPGA. All boys had increased growth velocity and imporved weight gain without excessive bone age advancement; all had improved psychosocial adjustment.

MR findings of endocardial fibroelastosis in children

BackgroundEndocardial fibroelastosis (EFE) is characterized by a diffuse white fibrous tissue lining the endocardium. The diagnosis is difficult to establish because clinical symptoms and electrocardiographic findings are nonspecific. Surgical resection of EFE requires the establishment of the diagnosis and delineation of the extent of the fibrotic changes.ObjectiveTo describe the use of MRI in the assessment of EFE in children.Materials and methodsThree children after surgery for aortic stenosis who were suspected of having EFE were evaluated by echocardiography and MRI. The MR evaluation consisted of black-blood, triple IR, bright-blood, perfusion and myocardial delayed-enhancement sequences. EFE was confirmed at surgery in all patients.ResultsEchocardiograms demonstrated vigorous systolic function but substantial diastolic dysfunction of the left ventricle in all. Mild endocardial brightening of the anterior septum, anterior wall, or papillary muscles was present in two. No study was thought to be diagnostic of endocardial fibrosis. On MRI EFE manifested at the endocardial surface as a rim of hypointense signal in the perfusion sequences and as a rim of hyperintense signal in the myocardial delayed-enhancement sequences. The black-blood, triple IR, and bright-blood sequences were not diagnostic.ConclusionThe diagnosis of EFE is difficult to establish by echocardiography. MRI using perfusion and myocardial delayed enhancement can be useful in establishing the diagnosis.

Congenital tracheal stenosis: Role of CT and high kV films

Congenital tracheal stenosis is an intrinsic narrowing of the tracheal lumen due to complete cartilaginous rings. We evaluated the role of the chest radiograph, high kV films, CT and bronchoscopy in five patients with congenital tracheal stenosis. CT was superior to chest radiography and high kV films in the evaluation of the presence and extent of the stenosis. CT was superior to bronchoscopy in the evaluation of the distal extent of the stenosis in two patients. In addition, CT is useful in ruling out external compression of the trachea by a mass or associated vascular anomaly.

Magnetic resonance imaging of mediastinal vessels

Advances in technology have led to a changing role for MRI in the evaluation of the thoracic vasculature in children. MRI, especially with 3D gadolinium-enhanced MR angiography, can clearly demonstrate the morphology of the aortic and pulmonary vascular supply. In patients with nonvalvar obstructive lesions of the aorta (i.e., coarctation, interruption of the aortic arch, and supravalvar stenosis), MRI can reliably assess the site and extent of the obstruction. Similarly, MRI can depict the morphology of the central pulmonary arteries and aortopulmonary collateral vessels in patients with obstructive lesions of the pulmonary artery. MRI is also useful in assessing the course of the aorta and pulmonary arteries in patients with suspected vascular rings. The result is that MRI can supplement information obtained from echocardiography and angiography and reduce the need for angiography.

The role of ultrasonography in the diagnosis of pyloric stenosis: A decision analysis

BACKGROUND/PURPOSE The appropriate role for ultrasonography (US) as a replacement for the upper gastrointestinal series (UGI) in vomiting infants remains undefined. The authors have used decision analysis techniques to determine whether the use of ultrasonography as an initial screen in vomiting infants is cost effective when compared with the UGI as the only study. METHODS Two diagnostic strategies were compared: 1) UGI alone and 2) ultrasonography followed by an UGI series in 50% of cases when ultrasonography scan was negative for pyloric stenosis. The test sensitivity (US, 0.9; UGI, 1.0) and test specificity (US, 1.0; UGI, 1.0) and the incidence of pyloric stenosis among vomiting infants presenting to the community pediatrician (0.30) or after a negative examination by an experienced examiner (0.02 to 0.18) were obtained from a review of the literature. The relative charges for ultrasonography and UGI were obtained from a national survey from which the cost ratio of US to UGI was estimated to range from 0.67 to 1.81 with a median of 1.06. RESULTS Under these baseline assumptions, UGI only was the preferred strategy. The results of the decision analysis were sensitive to, or dependent on, assumptions made regarding the incidence of pyloric stenosis, the US to UGI cost ratio, the sensitivity of the US, and the proportion of patients that proceed to UGI when the US scan was negative for pyloric stenosis. When at least 50% of patients whose US scan was negative for pyloric stenosis proceeded to a UGI, UGI remained the preferred strategy for all cost ratios examined (0.6 to 1.7). Even when no patients proceeded to UGI, the cost ratio of US to UGI had to be less than 0.7 under the typical incidence (0.30) of pyloric stenosis among vomiting infants presenting to the community pediatrician for US to be cost effective. Finally, only UGI was indicated when an olive was not appreciated by an experienced examiner. CONCLUSION Under assumptions that fit most clinically relevant circumstances, the UGI as the initial study is the most cost-effective radiological diagnostic test in the evaluation of the vomiting infant.