Contrast-enhanced magnetic resonance urography at 3T: clinical feasibility.

OBJECTIVE: The objective of this study was to assess the feasibility of performing diagnostic-quality contrast-enhanced excretory magnetic resonance urography (eMRU) at 3T, examining both image quality and diagnostic accuracy for a range of urinary tract abnormalities. METHODS: The diuretic-enhanced 3T eMRUs of 37 patients were reviewed to assess for the diagnostic conspicuity of urinary tract abnormalities, extent of urinary tract visualization on excretory images, and presence and severity of image artifacts. RESULTS: Excretory images allowed greater than 75% visualization in 90.8% of renal collecting systems, 90.8% of ureters, and 82.3% of bladders. Common artifacts included susceptibility (21.3%), contrast mixing (21.3%), patient motion (20.4%), signal inhomogeneity (19.4%), and peristaltic motion (17.6%). Severe artifacts occurred in 21.6% of studies. Five of 8 urothelial neoplasms were detected, with 1 false-positive lesion in the bladder. Urolithiasis was correctly diagnosed in 7 of 9 patients. CONCLUSIONS: Although image artifacts can hamper eMRU at 3T, initial results are promising for evaluation of the urothelium.

MRI of pregnancy-related issues: abnormal placentation.

OBJECTIVE: In this article, we review the clinical significance of abnormal placentation and the role of MRI in diagnosis and management of this potentially morbid condition. We present our clinical perspective on diagnosing this challenging problem with MRI and review the imaging findings that can lead to a correct diagnosis. CONCLUSION: As abnormal placentation becomes more prevalent, in large part due to the markedly rising rates of cesarean delivery, there is a need for accurate antenatal diagnosis of this condition to prevent maternal morbidity and mortality. Maternal and fetal outcomes can be optimized through multidisciplinary planning to achieve accurate diagnosis and anticipation of the extent of abnormal placentation in the antenatal period. Imaging findings of abnormal placentation have been described for both ultrasound and MRI, although limitations exist for each technique. Although ultrasound remains the primary screening modality for the detection of abnormal placentation, MRI is a complementary technique that should be considered when ultrasound is inconclusive or incomplete. Familiarity with MRI techniques to assess the placenta, MRI appearance of normal placenta, and imaging findings that suggest abnormal placentation can help radiologists contribute to a successful maternal outcome.

Magnetic resonance urography.

Excellent contrast resolution and lack of ionizing radiation make magnetic resonance urography (MRU) a promising technique for noninvasively evaluating the entire urinary tract. While MRU currently lags behind CT urography (CTU) in spatial resolution and efficiency, new hardware and sequence developments have contributed to a resurgence of interest in MRU techniques. By combining unenhanced sequences with multiphase contrast-enhanced and excretory phase imaging, a comprehensive assessment of the kidneys, ureters, bladder, and surrounding structures is possible with image quality rivaling that obtained with other techniques. At the same time, formidable challenges remain to be overcome and further clinical validation is necessary before MRU can replace other forms of urography. In this article, we demonstrate the current potential of MRU to demonstrate a spectrum of urologic pathology involving the kidneys, ureters, and bladder while discussing the limitations and current status of this evolving technique.

Acceleration of autoimmunity by organochlorine pesticides in (NZB x NZW)F1 mice.

Systemic lupus erythematosus (SLE) is an autoimmune disorder that affects women more frequently than men. In the (NZB times NZW)F1 mouse, a murine SLE model, the presence or absence of estrogen markedly influences the rate of progression of disease. Three organochlorine pesticides with estrogenic effects were administered chronically to ovariectomized female (NZB times NZW)F1 mice, and we measured the time to development of renal disease, the principal clinical manifestation of lupus in this model. Treatment with chlordecone, methoxychlor, or o,p -dichlorodiphenyltrichloroethane (o,p -DDT) significantly decreased the time to onset of renal impairment, as did treatment with 17ss-estradiol used as a positive control. In an expanded study of chlordecone, we found a dose-related early appearance of elevated anti-double-strand DNA autoantibody titers that corresponded with subsequent development of glomerulonephritis. Immunohistofluorescence confirmed early deposition of immune complexes in kidneys of mice treated with chlordecone. These observations are consistent with an effect of these organochlorine pesticides to accelerate the natural course of SLE in the (NZB times NZW)F1 mouse. Although we originally hypothesized that the effect on progression of autoimmunity was due to estrogenic properties of the pesticides, autoimmune effects and estrogenicity, assessed through measurement of uterine hypertrophy, were not well correlated. This may indicate that uterine hypertrophy is a poor indicator of comparative estrogenic effects of organochlorine pesticides on the immune system, or that the pesticides are influencing autoimmunity through a mode of action unrelated to their estrogenicity.