Biomedical subjects
P Karila-Cohen
Publications and source records attributed to P Karila-Cohen.
[Primary retroperitoneal tumors in adults].
Primary retroperitoneal tumors are rare and most of the time malignant. Because of the large space in which they grow, they are often discovered lately as they are large. CT and MR are the imaging techniques of choice for the primary diagnosis and the follow up of these tumors. Multiplanar reconstructions , signal and density resolution help for the nature diagnosis. The examinations allowed to find associated signs that helps also for the right diagnosis. The purpose of this paper is to answer a serie of questions: Is the mass in the retroperitoneal space? Are they imaging signs that helps for the diagnosis of nature? Are they associated signs that helps for the diagnosis of nature? What are the most common diagnosis? Is there any place for percutaneous biopsies? What is the role of imaging in the follow up? Are there any other processes that can mimic retroperitoneal tumors?
[Incisional subcutaneous endometrioma of the abdominal wall: report of two cases].
Endometriosis occurs in up to 15% of menstruating women. Abdominal wall involvement is rare and always secondary to an invasive procedure. The authors report the imaging and clinical findings of two patients with subcutaneous endometrioma following cesarean section.
[Peritoneal sarcoma with retroperitoneal involvement].
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[Pedunculated uterine leiomyoma].
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[Gastric adenocarcinoma].
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[Gastrointestinal stromal tumor].
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Effect of contrast dilution on contrast-enhanced MR angiography of the aorta and renal arteries.
The aim of this study was to investigate the effect of gadolinium chelate dilution on vascular enhancement in contrast-enhanced two-dimensional (2D) MR subtraction angiography of aorta and renal arteries. Twenty patients were prospectively included. 2D subtraction MR angiography consisted of successive multisection breathhold GRE acquisitions of 16 s (2D FLASH, TR/TE 72/4, flip angle 60 degrees) obtained in the coronal plane before and after intravenous bolus administration of 0.1 mmol/kg BW gadolinium chelate. Patients underwent both diluted and undiluted gadolinium chelate administration in a random order. The data were studied both qualitatively and quantitatively on source and maximum intensity projection images. The length of renal arteries opacified was found not to differ significantly according to contrast dilution. The contrast enhancement percentage was not significantly modified according to the dilution used, but the time to peak enhancement was observed to be longer with the diluted contrast. Qualitatively, the best MR images were those obtained when undiluted contrast was injected first (chi2, P = 0.01). At a dosage of gadolinium chelate 0.1 mmol/kg BW, undiluted contrast 2D MR subtraction angiography seems to be more appropriate for studying diseases of the aorta and renal arteries than a similar diluted dose.
[IVU: a test of the past without future?].
IVU has been gradually replaced over recent years as the "gold standard" investigation for the renal parenchyma and urinary tract by two new modalities: ultrasound and computed tomography. Some authors still advocate IVU for the assessment of renal colic, for the following reasons: the excess cost of CT (which is not true for plain CT) and the absence of functional data (there are specific CT signs for increased pressure). However, the advantages of CT are clearly established: contrast resolution allowing the detection of almost all stones except for certain complications of triple combination therapy in HIV seropositive patients, extensive cover facilitating identification of differential diagnoses, rapidity and greater efficacy, and finally the absence of risk related to the injection of iodinated contrast agents in this indication. However, the performance of CT may be more limited in certain situations: thin patients, or when the female genital tract also needs to be investigated, but IVU is not more contributive in this context. The current place of IVU in renal colic is therefore to establish a definitive diagnosis and to guide an urgent procedure (removal of an obstruction in a context of infection) when CT is either unavailable (maintenance...) or really excessively irradiating, as in pregnant women, when ultrasound, or even MRI and MR urography have not been sufficiently contributive. The essential indication remains detailed visualization of the urinary tract (assessment of haematuria, detection of an urothelial tumour), detailed visualization of the entire urinary tract (assessment of certain malformations), or even a gross assessment of renal function in a patient with multiple injuries, which cannot be investigated by CT and in whom the surgeon rightly hesitates before opening the retroperitoneum. However, in the absence of IVU, we may fail to diagnose papillary necrosis or a small caliceal diverticulum, but is that really important in the final analysis? IVU, in countries with adapted equipment, is therefore now only an expert examination. IVU is an examination of the past, without a future indeed, but with a descendant: CT urography.
Hemodynamic effect of iodinated high-viscosity contrast medium in the rat kidney: a diffusion-weighted MRI feasibility study.
RATIONALE AND OBJECTIVES: To assess the abilities of dynamic diffusion-weighted MRI to demonstrate the effects in vivo of a high-viscosity iodinated contrast agent on medullary and cortical blood flow in the rat kidney. METHODS: Dynamic diffusion-weighted, echoplanar MR images obtained from five b-value single-shot acquisitions and their isotropic apparent diffusion coefficient maps were obtained from nine rats anesthetized by pentobarbital sedation, before and after intravenous injection of a high-viscosity, dimeric iso-osmolar iodinated contrast medium (iodixanol), and compared with those obtained from four control rats that received saline. RESULTS: The mean baseline apparent diffusion coefficient values were 1.64 +/- 0.05 x 10(-3) mm2/s for the cortex and 1.75 +/- 0.06 x 10(-3) mm2/s for the medulla. In the iodixanol group, a significant decrease in renal diffusion was observed at 12 minutes and lasted at least until 24 minutes. The decrease in diffusion occurred earlier for the cortex and lasted less than for the medulla. There was no significant modification in diffusion over time in the control group. CONCLUSIONS: This preliminary experience in rats shows that dynamic diffusion-weighted MRI can be used to study noninvasively the in vivo renal hemodynamic response after injection of iodinated contrast.