The enhancement pattern in double-phase helical CT was different among the subtypes of RCC, and correlated with microvessel density or the existence of intratumoral necrosis or hemorrhage. However it did not differentiate between RCC and other solid tumors.

Decreased overall phagocytic activity in cirrhotic liver is more likely due to Kupffer cell dysfunction than to Kupffer cell depletion, since magnetic susceptibility effects on T2*-weighted GRE images depend on intracellular SPIO cluster size.

The recent popularity of prenatal magnetic resonance (MR) imaging has been associated with the development of ultrafast MR imaging techniques such as the single-shot fast spin-echo sequence. However, the majority of previous reports have concerned the fetal central nervous system (CNS) and chest disorders. MR imaging can demonstrate non-CNS fetal anatomy and pathologic conditions clearly. With its excellent tissue contrast, MR imaging provides information that supplements that provided by ultrasonography (US), especially in cases of neck, chest, and gastrointestinal lesions. Because of its large field of view, MR imaging allows evaluation of the relationship between a large lesion and adjacent structures. MR imaging should be considered if the diagnosis of a suspected non-CNS lesion is unclear at fetal US. MR imaging plays an important complementary role to US in cases of non-CNS fetal lesions and will be further accepted for fetal imaging in the future.

Becausesonography is nowcapable of achieving increased resolution, ovarian tumors are more fre quently found in early pregnancy. In this case, we describea patientin the secondtrimester with ovarian endometriosis, which enlarged and was accompanied by structural changes inside the tumor. Case ReportA 28-year-old primigravidawas first seen in our antenatal clinic at 5 weeks of gestation. She had a history ofovarian endometriosis and had been treated with a gonadotropin-releasing hormone analogue before the pregnancy. A sonographic examination showed an intrauter me gestationsac and a right ovariantumor.The tumor was a unilocular cyst with fine in ternal echoesand a maximum diameter of 45 mm (Fig. 1A). Because the patient had a his tory of endometriosis, the tumorwasbelieved to represent an endometrial cyst and was treated conservatively.At 16 weeks ofgestation, sonographic exam ination revealeda fetus appropriatefor the ges tational age and showed an increase in size of the ovariancyst, which had reacheda maximum diameter of 85 mm. On transvaginalsonogra phy, irregularhyperechogenicrepresentingpap illary excrescences structures were seen inside the cyst. Color-flow Doppler sonography de picted vascularity within the solid irregular ar eas (Fig. 1B). These sonographic changes became more remarkable at i8 weeks of gesta flon. For further evaluation of a possible malig nancy, MR imaging was performed.The high signalintensityon TI-andT2-weightedimages was in the cystic portion of the tumor, suggest ing blood products. The solid portion was dark on Tl-weighted images and bright on 12-weighted images, suggesting malignancy that may have arisenfrom the endometriosis (Figs. lCand lD).On exploratory laparotomy performed at 20 weeksof gestation,a right ovariantumor adher ingtotheposterior wall ofthe uteruswasfound. A smallamountof asciteswasalsonoted.The tumor, which contained chocolatelike bloody fluid,hadalreadyraptured. After suctioning the fluid from the tumor, a right salpingo-oophorec tomy was performed.Papillaryexcrescences werefoundprotruding intothelumenof thetu mor. Final histopathologicexamination re vealed ovarian endometnosis with marked decidual changes and hemorrhage and without evidenceof malignancy (Fig. 1E). The patient recovered promptly and delivered a 3704-g healthymale infant at 40 weeksof gestation. during human pregnancy;thus, we did not use this contrast material in our patient. The clinical findings were indicative of malig nancy;however,final histopathologic exami nation of the tumor merely revealed solid tissue representing massive decidualization and hemorrhage. To our knowledge, ovarian endometriosisincreasingin size and accom panied by marked decidual bleeding during pregnancyis a rareoccurrence. The malignant transformation of endometri osis has been well documented, and persistent estrogenic stimulation has been implicated as a cause [4,5]. Becauseof this,ovarianendometri osis in pregnant women should be treated with special attention to structural changes that occur during pregnancy. Disc...