Barry D. Fletcher

Idiopathic infantile arterial calcification: Roentgen diagnosis of a rare cause of coronary artery occlusion

Infantile arterial calcification is a rare disorder of unknown etiology which is usually generalized and leads to death from coronary artery occlusion. The involved arteries show calcification of the internal elastic lamina and marked intimal proliferation. Vascular calcifications were demonstrated radiographically in 9 previously recorded cases. Three new patients are reported who presented with congestive heart failure. The visualization of faint vascular calcifications in the extra-thoracic soft tissues presented an opportunity to establish the diagnosis radiologically.

Hemolytic Uremic Syndrome: A Case Presenting with Acute Colitis

A case of hemolytic uremic syndrome (HUS) in a 3 year old boy, who presented with diffuse rectal bleeding is discussed. On barium enema, there was evidence of acute colitis with submucosal hemorrhage. The probable relationship of these findings to the pathogenetic intravascular coagulopathy and the prodromal stage of HUS is discussed.

EVALUATION OF AV CANAL DEFECTS USING ECG-GATED NMR IMAGING

Preoperative assessment of AV canal defects requires precise delineation of ventricular, septal and valvular morphology. In particular, recognition of ventricular hypoplasia is critical since it may preclude successful surgical correction. This evaluation is difficult even with cineangiography and 2-dimensional echocardiography. Nuclear magnetic resonance imaging (NMRI) is a new technique capable of providing excellent spatial and contrast resolution of cardiovascular structures without the need for contrast agents. We have used ECG-gated NMRI at 0.3T to evaluate 6 children with AV canal defects, including 3 with balanced chamber sizes, 2 with hypoplasia of the left ventricle and 1 hypoplastic right ventricle. All 6 defects were readily imaged and the 3 hypoplastic ventricles identified. AV valve morphology could be determined in 5 patients. Other frequently seen structures included papillary muscles, chordae tendinae and moderator bands. We conclude that gated NMRI is a valuable adjunct to angiography and echocardiography in the preoperative evaluation of children with AV canal defects.

EVALUATION OF PALLIATIVE SYSTEMIC-PULMONARY ARTERIAL SHUNTS USING NMR IMAGING

Palliative systemic-pulmonary artery (SP) shunts are frequently performed on children with cyanotic congenital heart defects which result in decreased pulmonary blood flow. Postoperative assessment of the adequacy of the shunt depends on physical examination, arterial blood gas analysis, chest x-ray and doppler-echocardiography. Direct visualization of the shunt, however, has required angiographic techniques at cardiac catheterization or, more recently, digital subtraction angiography. Nuclear magnetic resonance imaging (NMRI) is a new technique capable of providing high quality resolution of vascular structures without the use of contrast agents or exposure to ionizing radiation. We have used ECG-Gated NMRI at 0.3T to evaluate 6 patients with a total of 8 SP shunts including 4 Glenn shunts and 4 Blalock-Taussig (BT) shunts. 3 of 4 Glenn shunts and 3 of 4 BT shunts could be imaged. The size and course of the shunt could be seen in its entirety. 1 Glenn and 1 BT shunt, both patent, were not imaged. We conclude that NMRI is a safe, effective, non-invasive method for visualizing and evaluating patent palliative SP shunts. In our hands, NMRI has proved superior to echocardiography in visualizing these shunts.

484 CLINICAL DISAGREEMENT IN THE ASSESSMENT OF BPD IN A CLINICAL TRIAL

Disagreement between clinicians in interpreting clinical signs is ubiquitous in medicine. In the interpretation of endpoints in clinical trials, this can be crucial. A randomised clinical trial to test the effectiveness of Vitamin E in LBW babies in the prevention of BPD required the assessment of BPD to be as objective as possible. Three radiologists agreed to interpret the X-rays, independently and blindly. One was a pediatric radiologist; one, a general radiologist, regularly reviews neonatal films; and one was interested in pulmonary disease. The criteria used were those of Northway. X-rays, taken at days 1, 10, 21, 28 and 42 were coded and read. The results of the first batch of 268 films indicated that there was complete agreement in 28% (usually the normal films); agreement between 2 of the 3 in 36% and no agreement in 35%. Possible sources of disagreement included the quality of the films and the comorbidity of the babies as well as reviewing out of context. The decoded films were placed back in order. Agreement was reached on 35% of babies; two agreed on 17% and all 3 agreed on a further 13% but not on the severity of the disease. 35% still had questionable conclusions. Strategies to resolve these differences included adding the complete series of baby films; checking autopsy reports if insufficient films were available and bringing the 3 radiologists together with a neonatologist to resolve interpretative differences.

957 THYMIC RESPONSE TO ENDOGENOUS AND EXOGENOUS STEROIDS IN PREMATURE NEWBORN INFANTS

Thymic response to corticosteroid therapy for RDS was studied by measuring thymic width vs. transverse thoracic diameter on AP chest radiographs of premature newborn infants. Thymic-thoracic ratio (TTR) was evaluated in A)22 normal prematures, B)43 infants with RDS who received hydrocortisone or placebo postnatally (Pediatrics 50:526, 1972) and C)30 infants at risk for RDS treated with maternal betamethasone or placebo. In group A, TTR was unrelated to gestational age and was significantly smaller (mean 0.35) than in patients of group B and C with RDS, P< 0.025. On Day 1, TTR of steroid-and placebo-injected infants in group B were nearly identical (mean 0.42, 0.43) and declined at similar rates during the following 3 days to 63 and 69 percent of their original value respectively. Infants in group C who received betamethasone had a lower incidence of RDS than those given placebo. The TTR was significantly greater in patients who developed RDS(mean 0.42) than in those with normal lungs(mean 0.35),P<0.05.No relationship was observed between TTR and prenatal steroid dose or blood corticosteroid levels. The association of a high TTR and RDS suggest that steroids may have a parallel effect on thymus size and the pathogenesis of RDS. Hence measurement of TTR soon after birth could help identification of infants likely to develop RDS.