URO-IRM et uropathies congénitales (mise en place et faisabilité)

Le but de cette étude était de mettre en place et de tester la faisabilité d'un protocole d'IRM morphologique et fonctionnelle urinaire dans le bilan des uropathies congénitales les plus fréquentes (syndrome de la jonction pyélourétérale, méga uretère, duplication urétérale, dysplasie rénale multikystique), et de le comparer à l'UIV et à la scintigraphie rénale au Mag3 Lasilix® pour la détermination de la fonction rénale différentielle et l'évaluation de l'excrétion . Les résultats obtenus à partir d'une série de 13 enfants ont montré que l'URO IRM pouvait se substituer à l'UIV dans l'étude morphologique de ces uropathies. L'analyse IRM de l'excrétion semble fiable, comparable à celle de la scintigraphie rénale. L'étude de la fonction rénale différentielle devrait bénéficier des optimisations de protocole proposées par cette étude, permettant qu'elle devienne aussi fiable et reproductible que la scintigraphie rénale au Mag3-Lasilix®. Le lancement d'une étude prospective à plus grande échelle, validée par le CCPRB semble maintenant possible.ROUEN-BU Médecine-Pharmacie (765402102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Dynamic MR urography in urinary tract obstruction: implementation and preliminary results.

International audienceBACKGROUND: Recent studies have demonstrated magnetic resonance (MR) capabilities in evaluating renal morphology and function in patients with urinary obstruction. The objective of this report is to support the introduction of dynamic MR renography on any MR equipment. METHODS: A custom-made device of vials filled with different concentrations of gadolinium was studied by combinations of T1-weighted gradient-echo sequences and coils. We compared the capabilities of two coils (phased array vs. standard body), the properties of dynamic sequences, and the effects of increasing concentrations of gadolinium on signal intensity. In a second section, we designed MR urography plug-ins of Image J (DICOM image software) for the analysis of dynamic studies. RESULTS: Optimized gradient-echo sequences acquired with a phased array body coil produced acceptable quality images with a linear relation between signal intensity and the lowest concentrations of gadolinium. In vitro measurements showed loss of linearity above 8 mmol/L. CONCLUSION: Theoretical calculation and data from the literature suggest that the gadolinium dose to the patient should not exceed one-fourth of the usual one (0.025 mmol/kg). Postprocessing using Image J software and the specifically designed plug-ins was validated. The collection of plug-ins is now available on the Internet

Does chemotherapy influence the quantification of SUV when contrast-enhanced CT is used in PET/CT in lymphoma?

International audiencePURPOSE: In patients with lymphoma, we investigated the impact of contrast-enhanced CT on PET attenuation correction in lesions and normal tissues, particularly when PET/CT was performed after chemotherapy. METHODS: Fifty patients (51+/-18 years) with Hodgkin's disease (n=17) or non-Hodgkin lymphomas (n=33) were studied before and after chemotherapy. PET/CT scans were performed 60 min after injection of FDG. Iopamiron 300 (iopamidol, 1.5 cc/kg) was injected immediately afterwards, followed 50 s later by a second craniocaudal CT (CT+). PET images were successively reconstructed using the unenhanced CT (PET-) and the CT+ (PET+) for attenuation correction, using iterative reconstruction (4 iterations, 8 subsets, 5 mm post-filtering). HU(mean), SUV(max) and SUV(mean) were measured before and after chemotherapy in ten non-tumoural ROIs [aorta, femur, kidney, lung, iliopsoas muscle, occipital cortex, T12 vertebra, liver, spleen and inferior vena cava (IVC)] and in tumoural lymphadenopathies or malignant tissues (n=397 and 51 VOIs respectively before and after chemotherapy) using a 3D-thresholding method (identical threshold for PET- and PET+). ROIs were defined on the PET- and automatically applied on the unenhanced CT (CT-), the CT+ and the PET+. RESULTS: In the non-tumoural tissues, HU(mean) increased significantly in the CT+ compared with the CT- in the vessels and the highly vascularised organs, and slight increases were observed in the occipital cortex (+11%), the iliopsoas muscle (+6%) and the femur (+3%). SUV(max) increased significantly in the PET+ compared with the PET- in the aorta (+14%), the liver (+10%), the spleen (+10%) and the IVC (+12%). SUV(mean) increased significantly in the PET+ compared with the PET- in the aorta (+15%), the kidney (+13%), the liver (+11%), the spleen (10%) and the IVC (+12%). In the lesions, HU(mean) was not significantly different before and after chemotherapy, whatever the normal region considered. SUV(max) increased significantly after treatment in the T12 vertebra (+12%). SUV(mean) increased significantly after treatment in the T12 vertebra (+13%) and in the liver (+12%). HU(mean) increased significantly in the CT+ compared with the CT- in the lesions (+55%) before chemotherapy. SUV(max) and SUV(mean) increased significantly in the PET+ compared with the PET- in the lesions (+4%) only before chemotherapy. No significant difference was seen in measurements (HU(mean), SUV(max) and SUV(mean)) after chemotherapy. CONCLUSION: Our study demonstrates that use of enhanced CT for attenuation correction has a negligible effect on quantification at staging and after chemotherapy. A "single-shot" enhanced PET/CT may thus be performed in the evaluation of patients with lymphoma at staging, during treatment and at follow-up

Influence of PET/CT on radiologists and contrast-enhanced CT on nuclear medicine physicians in patients with lymphoma.

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