MR enterography in children with Crohn disease: results from the Belgian pediatric Crohn registry (Belcro)

INTRODUCTION

Magnetic Resonance enterography (MRE) is an imaging modality avoiding ionizing radiation and the discomfort associated with enteroclysis. The results of MRE at diagnosis in the patients of the Belgian pediatric Crohn registry (Belcro) are compared to endoscopical and histological results.

METHODS

Results of MRE, endoscopy and histology were obtained from the medical charts and assigned to one of the following segments: jejunum, ileum, ascending colon, transverse colon, descending colon or rectosigmoid. MRE images were reviewed in a blinded way by 4 radiologists with specific interest in pediatric MRE.

RESULTS

From the Belcro registry, twenty-two patients underwent a MRE during their work-up for Crohn disease. The results of endoscopy, histology and MRE were concordant (either all negative or positive) in the ileum in 16/18 patients and in the rectosigmoid, descending colon, transverse colon and ascending colon in resp 9, 8, 8 and 8/22 patients. In the non-concordant cases (MRE colon negative but endoscopy and/or histology positive), MRE could not reflect the subtle endoscopic or histologic lesions such as erosions that were described.In 4 cases where ileocaecal valve intubation was impossible ileal MRE findings were abnormal. MRE detected ileal stenosis, jejunal lesions and fistula in resp 4/22, 3/22 en 2/22 patients. The 100% and 75% interobserver agreement was resp 50-82% and 773-100% according to the different intestinal segments.

CONCLUSIONS

MRE is a promising imaging modality avoiding radiation in Crohn disease. It should probably become the technique of first choice for the evaluation of extensive small bowel disease in children with Crohn disease.

Grading and characterization of soft tissue tumors on magnetic resonance imaging: the value of an expert second opinion report

Objective

To retrospectively compare the accuracy of the initial MRI (magnetic resonance imaging) report of referring radiologists and the second opinion report.

Material and methods

MRI of 155 patients presenting with a soft tissue tumor (STT) in a single large community center were referred for inclusion in the Belgian Soft Tissue Neoplasm Registry (BSTNR). The initial report and the second opinion report were made independently. Histopathology (gold standard) was obtained in 90 patients (group 1). In 65 patients, the diagnosis was made by the combination of clinical findings and/or follow-up (group 2). In group 1, the concordance in grading and tissue-specific (TS) diagnosis between the referring center (RC) and expert center (EC) was reviewed.

Results

In group 1, MR grading yields a sensitivity of 100% and a specificity of 89% in the EC. The sensitivity was 88% and the specificity 81% in the RC. The accuracy was significantly higher in the EC (92%) compared to the RC (83%) (p = 0.039). The TS diagnosis was correct in 50% versus 38.5% of malignant tumors and in 71.8% versus 51.6% of benign tumors in the EC and RC respectively.

Conclusion

A second opinion report increases the accuracy in the diagnosis of STT on MRI.

Main Messages

• A second opinion MRI report increases the overall accuracy in the diagnosis of soft tissue tumors.

• There is a good overall agreement in MR grading between the referring and expert institution.

• In the expert center, there were fewer false-negative and false-positive diagnoses.

• MRI performs better in the tissue-specific diagnosis of benign versus malignant STT.

Pott's puffy tumour in a 5-year old boy: the role of ultrasound and contrast-enhanced CT imaging; surgical case report

We report a case of Pott's puffy tumour, a subperiosteal abscess of the frontal bone associated with an underlying frontal osteomyelitis, in a 5-year-old boy. Ultrasonography played a crucial role in the diagnosis of our patient, suggesting the presence of a Pott's puffy tumour with epidural abscess by showing a subperiosteal abscess associated with erosion of the frontal bone. Subsequently, the diagnosis of Pott's puffy tumour with epidural abscess was confirmed by contrast-enhanced CT scanning. Prompt neurosurgical intervention with drainage of abscesses and debridement of bone sequestrate, together with prolonged antibiotic therapy, significantly contributes to a favorable outcome.

A two-year old boy with recurrent bouts of acute abdominal pain

In a small number of patients with pancreas divisum (with stenotic minor papilla) a relative obstruction to pancreatic exocrine secretory flow results in pancreatitis. We report a 2-year-old boy presenting with recurrent bouts of abdominal pain. The diagnosis of acute pancreatitis was made based on blood biochemistry results. Ultrasound, computed tomography and magnetic resonance imaging showed several abdominal pseudocysts, peritoneal exsudate and confirmed pancreatitis but initially failed to reveal the aetiology. Ascites and cysts contained pancreatic enzymes. After weeks of combined conservative and surgical treatment, a magnetic resonance cholangiopancreaticography with secretin, showed a pancreas divisum with a cyst between the ducts of Santorini and Wirsung. Based on these findings, two endoscopic papillotomies (minor and major papilla) were performed. Three years follow-up was uneventful. In a child with recurrent pancreatitis or pancreatitis with chronic recurrent abdominal pain it is crucial to search aggressively for congenital abnormalities, including pancreas divisum. Secretin-enhanced magnetic resonance cholangiopancreaticography or diffusion-weighted magnetic resonance imaging is a valuable diagnostic tool for visualizing pancreatic duct anatomy.

Characterization of the Saccharomyces cerevisiae ARG7 gene encoding ornithine acetyltransferase, an enzyme also endowed with acetylglutamate synthase activity

We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. While forming ornithine, this enzyme regenerates acetylglutamate, also produced in the first step by the ARG2-encoded acetylglutamate synthase. Interestingly, total deletion of the genomic ARG7 ORF resulted in an arginine-leaky phenotype, indicating that yeast cells possess an alternative route for generating ornithine from acetylornithine. Yeast ornithine acetyltransferase has been purified and characterized previously as a heterodimer of two subunits proposed to derive from a single precursor protein [Liu, Y-S., Van Heeswijck R., Hoj, P. & Hoogenraad, N. (1995) Eur. J. Biochem. 228, 291-296]; those authors further suggested that the internal processing of Arg7p, which is a mitochondrial enzyme, might occur in the matrix, while the leader peptide would be of the non-cleavable-type. The characterization of the gene (a) establishes that Arg7p is indeed encoded by a single gene, (b) demonstrates the existence of a cleaved mitochondrial prepeptide of eight residues, and (c) shows that the predicted internal processing site is unlike the mitochondrial proteolytic peptidase target sequence. Yeast Arg7p shares between 32-43% identity in pairwise comparisons with the ten analogous bacterial ArgJ enzymes characterized. Among these evolutionarily related enzymes, some but not all appear bifunctional, being able to produce acetylglutamate not only from acetylornithine but also from acetyl-CoA, thus catalyzing the same reaction as the apparently unrelated acetylglutamate synthase. We have addressed the question of the bifunctionality of the eucaryotic enzyme, showing that overexpressed ARG7 can complement yeast arg2 and Escherichia coli argA mutations (affecting acetylglutamate synthase). Furthermore, Arg7p-linked acetylglutamate synthase activity was measurable in an assay. The yeast enzyme is thus clearly, albeit modestly, bifunctional. As with several bacterial ornithine acetyltransferases, the activity of Arg7p was practically insensitive to arginine but strongly inhibited by ornithine, which behaved as a competitive inhibitor.

Mycotic pseudo-aneurysm of the extracranial carotid artery

A rare case of mycotic pseudo-aneurysm of the common carotid artery as a complication in an immunosuppressed paediatric patient is presented. Treatment of pseudo-aneurysms of the common carotid artery is generally considered to be an emergency, necessitating quick and accurate diagnosis. In patients with septicemia, angiography has to be avoided. We were able to provide the surgeon with the exact diagnosis and accurate topographical information with helical CT with 3D reformation.