[Radiological innovations in the screening and diagnosis of the inborn errors of metabolism].
New metabolic diseases are regularly identified by a genetic or biochemical approach. Indeed, the metabolic diseases result from an enzymatic block with accumulation of a metabolite upstream to the block and deficit of a metabolite downstream. The characterization of these abnormal metabolites by MRI spectroscopy permitted to identify the deficient enzyme in two new groups of diseases, creatine deficiencies and polyol anomalies. Creatine deficiency is implicated in unspecific mental retardation. A low peak of creatine at MRI spectroscopy is evocating of creatine deficiency which is treatable by creatine administration. Deficiency of synthesis of polyols, metabolites on the pentose pathway, represent new described metabolic diseases with variable symptoms including a neurological distress, liver disease, splenomegaly, cutis laxa and renal insufficiency. The deficit of ribose-5-phosphate isomerase, one of the enzymes whose diagnosis is evoked in front of the accumulation of ribitol, arabitol and xylitol leads to a leucodystrophy in adults. This new deficit was highlighted by the identification of an abnormal peak in cerebral MRI-spectroscopy corresponding to the abnormal accumulation of polyols in brain. Congenital hyperinsulinism (HI) is characterized by profound hypoglycaemia related to inappropriate insulin secretion. Focal and diffuse forms of hyperinsulinism share a similar clinical presentation but their treatment is dramatically different. Until recently, preoperative differential diagnosis was based on pancreatic venous sampling, an invasive and technically demanding technique. Positron emission tomography (PET) after injection of [18F]Fluoro-L-DOPA has been evaluated for the preoperative differentiation between focal and diffuse HI, by imaging uptake of radiotracer and the conversion of [18F]Fluoro-L-DOPA into dopamine by DOPA decarboxylase. PET with [18F]Fluoro-L-DOPA has been validated as a reliable test to differentiate diffuse and focal HI and is now a major differential diagnosis tool in infantile hyperinsulinemic hypoglycaemia.
Boddaert
Nathalie
N
Service de radiologie pédiatrique, ERM 0205, Hôpital Necker Enfants-Malades, 149, rue de Sèvres, 75743 Paris Cedex 15, France. nathalie.boddaert@nck.ap-hop-paris.fr
Ribeiro
Maria
M
Touati
Guy
G
Mention
Karine
K
Valayanopoulos
Vassili
V
Nihoul-Fékété
Claire
C
Brunelle
Francis
F
de Lonlay
Pascale
P
D019747:Aldose-Ketose Isomerases / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D000579:Amidinotransferases / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D001923:Brain Chemistry; D044903:Congenital Hyperinsulinism / Q000000981:diagnostic imaging / Q000235:genetics; D003401:Creatine / Q000032:analysis / Q000172:deficiency / Q000627:therapeutic use; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives; D004296:Dopa Decarboxylase / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D005820:Genetic Testing / Q000379:methods* / Q000639:trends; D050937:Guanidinoacetate N-Methyltransferase / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009682:Magnetic Resonance Spectroscopy; D008661:Metabolism, Inborn Errors / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D010179:Pancreas / Q000000981:diagnostic imaging; D010427:Pentose Phosphate Pathway; D010429:Pentoses / Q000378:metabolism; D050480:Plasma Membrane Neurotransmitter Transport Proteins / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D049268:Positron-Emission Tomography; D011859:Radiography; D019275:Radiopharmaceuticals
D009419:Nerve Tissue Proteins; D010429:Pentoses; D050480:Plasma Membrane Neurotransmitter Transport Proteins; D019275:Radiopharmaceuticals; C094770:SLC6A8 protein, human; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; C494506:GAMT protein, human; D050937:Guanidinoacetate N-Methyltransferase; D000579:Amidinotransferases; C020681:glycine amidinotransferase; D004296:Dopa Decarboxylase; D019747:Aldose-Ketose Isomerases; C022548:ribosephosphate isomerase; D003401:Creatine