Paramagnetic perfluorocarbon-filled albumin-(Gd-DTPA) microbubbles for the induction of focused-ultrasound-induced blood-brain barrier opening and concurrent MR and ultrasound imaging

This paper presents new albumin-shelled Gd-DTPA microbubbles (MBs) that can concurrently serve as a dual-modality contrast agent for ultrasound (US) imaging and magnetic resonance (MR) imaging to assist blood-brain barrier (BBB) opening and detect intracerebral hemorrhage (ICH) during focused ultrasound brain drug delivery. Perfluorocarbon-filled albumin-(Gd-DTPA) MBs were prepared with a mean diameter of 2320 nm and concentration of 2.903×10(9) MBs ml(-1) using albumin-(Gd-DTPA) and by sonication with perfluorocarbon (C(3)F(8)) gas. The albumin-(Gd-DTPA) MBs were then centrifuged and the procedure was repeated until the free Gd(3+) ions were eliminated (which were detected by the xylenol orange sodium salt solution). The albumin-(Gd-DTPA) MBs were also characterized and evaluated both in vitro and in vivo by US and MR imaging. Focused US was used with the albumin-(Gd-DTPA) MBs to induce disruption of the BBB in 18 rats. BBB disruption was confirmed with contrast-enhanced T(1)-weighted turbo-spin-echo sequence MR imaging. Heavy T(2)*-weighted 3D fast low-angle shot sequence MR imaging was used to detect ICH. In vitro US imaging experiments showed that albumin-(Gd-DTPA) MBs can significantly enhance the US contrast in T(1)-, T(2)- and T(2)*-weighted MR images. The r(1) and r(2) relaxivities for Gd-DTPA were 7.69 and 21.35 s(-1)mM(-1), respectively, indicating that the MBs represent a positive contrast agent in T(1)-weighted images. In vivo MR imaging experiments on 18 rats showed that focused US combined with albumin-(Gd-DTPA) MBs can be used to both induce disruption of the BBB and detect ICH. To compare the signal intensity change between pure BBB opening and BBB opening accompanying ICH, albumin-(Gd-DTPA) MB imaging can provide a ratio of 5.14 with significant difference (p = 0.026), whereas Gd-DTPA imaging only provides a ratio of 2.13 and without significant difference (p = 0.108). The results indicate that albumin-(Gd-DTPA) MBs have potential as a US/MR dual-modality contrast agent for BBB opening and differentiating focused-US-induced BBB opening from ICH, and can monitor the focused ultrasound brain drug delivery process.     

Effectiveness of combined GnRH analogue plus raloxifene administration in the treatment of uterine leiomyomas: a prospective,randomized, single-blind,placebo-controlled clinical trial

BACKGROUND: Raloxifene hydrochloride is a synthetic non-steroidal drug used for the prevention and treatment of post-menopausal osteoporosis. Pre-clinical and clinical data have shown that raloxifene may have a beneficial effect on leiomyomas. The aim of this prospective single-blind, randomized, placebo-controlled clinical trial was to evaluate the effectiveness of the addition of raloxifene to GnRH analogues on uterine, leiomyoma, and non-leiomyoma sizes, and on the occurrence of leiomyoma-related symptoms. METHODS: After randomization using a computer-generated list, 100 pre-menopausal women with symptomatic uterine leiomyomas received either leuprolide acetate depot plus raloxifene 60 mg daily (group A) or leuprolide plus placebo tablet (group B) for six cycles of 28 days. At baseline and after treatment, uterine, leiomyoma and non-leiomyoma sizes, and leiomyoma-related symptoms were evaluated for each woman. Analysis was by intention-to-treat method. RESULTS: After six cycles of treatment, a significant decrease in uterine, leiomyoma, and non-leiomyoma sizes was detected in both groups in comparison with baseline. At the same time, no significant difference in uterine and non-leiomyoma sizes was observed between the groups. Leiomyoma sizes were significantly (P < 0.05) lower in group A than in group B. No difference was observed in leiomyoma-related symptoms between groups throughout the study period. CONCLUSIONS: In women treated with GnRH analogue, the raloxifene administration induces a higher reduction of leiomyoma sizes.     

骨骼肌系统感染的MRI诊断价值

骨骼肌系统感染，于MRI T1 WI上多低信号、T2W1上多高信号。骨髓炎时，T1WI上病灶内低信号，可由纤维化造成。炎性肿块T1WI上高信号可由出血引起，而T2WI上肿块内低信号也可由纤维组织形成产生。STIR成像对显示骨骼肌系统病变有高度敏感性。Gd-DTPA增强后，感染病灶内环状强化是提示脓肿形成或组织坏死液化。骨骼肌系统感染，MRI优于X线平片检查，但类似上述MRI表现也可见于骨骼肌系统的其他良性或恶性病史。因此，必须结合临床资料才能正确诊断。     

MR findings of the spinal paraganglioma : report of three cases

Extraadrenal paragangliomas involving the spine is less common and usually takes the form of intradural compression of the cauda equina. The authors report three cases of spinal paragangliomas resulting in extradural spinal cord compression and their MR findings. The MR imaging revealed a well-demarcated extradural mass with low to intermediate signal intensity on T1-weighted images and intermediate to high signal intensity on T2-weighted images compared to paravertebral muscles. After Gd-DTPA administration, heterogeneous and intense enhancement was found. Multiple punctate and serpiginous structures of signal void due to high-velocity flow were noted around and within the tumors on all sequences. In one case, the signal void structures were well corresponded with feeding arteries on angiography. These may be the characteristic findings of the extraadrenal paraganglioma involving the spine.     

椎间隙感染的MRI诊断

目的：分析椎间隙感染的MRI影像特征，评价椎间隙感染的MRI诊断价值。方法：对15例经临床或手术病理证实的椎间隙感染患者行脊柱MRI检查，扫描序列为矢状面FrFsE-T1WI、FrFSE-T2WI、脂肪抑制T2WI，横断面FrFSE-T2WI，其中5例行Gd-DTPA增强对比扫描。结果：15例患者共发现17个椎间隙感染，其中15个发生于腰椎间隙。椎间隙狭窄(13个)，病变椎间盘呈不同程度破坏、碎裂，呈长T1(17个)长T2(15个)信号，T2上椎间盘髓核内正常裂隙状低信号消失(13个)，上下相邻椎体受累破坏(15个)，椎旁软组织肿胀(8个)。5例行Gd-DT-PA增强对比扫描可见病变椎间盘、相邻椎体及椎旁软组织异常强化。结论：MRI对诊断椎间隙感染具有很高的敏感性和准确性，应作为首选的影像学检查方法：     

Long-term effectiveness and safety of GnRH agonist plus raloxifene administration in women with uterine leiomyomas

BACKGROUND: Our aim was to evaluate the long-term effectiveness and safety of GnRH agonist plus raloxifene administration in women with symptomatic uterine leiomyomas. METHODS: Fifty pre-menopausal women with uterine leiomyomas were treated with leuprolide acetate depot at dose of 3.75 mg/28 days and raloxifene hydrochloride at 60 mg/day for 18 cycles. At admission and after each six cycles of treatment, bone mineral density (BMD), uterine, leiomyoma and non-leiomyoma dimensions, serum bone metabolism markers, lipid, glucose and insulin levels were evaluated. Leiomyoma-related and climacteric-like symptoms were assessed using a daily diary. RESULTS: Throughout the study, no significant change in BMD or in any bone metabolism markers was observed. A significant decrease in uterine, leiomyoma and non-leiomyoma sizes was detected in comparison with baseline already after 6 months. No other significant change was observed at the successive follow-up visits. No significant change in lipid and glucose profile was detected throughout the study. The treatments were well tolerated. All treatment withdrawals (16%, eight out of 50) were due to lack of compliance, and none to drug-related adverse experiences. CONCLUSION: GnRH agonist plus raloxifene administration is an effective and safe treatment for pre-menopausal women with uterine leiomyomas.     

Degeneration of Leiomyoma in Patients Referred for Uterine Fibroid Embolization: Incidence,Imaging Features and Clinical Characteristics

Purpose

Imaging features and clinical characteristics of degenerated leiomyoma in patients referred for uterine fibroid embolization (UFE) were analyzed to assess the incidence of degenerated leiomyoma.

Materials and Methods

Patients referred for UFE between 2008 and 2009 were retrospectively analyzed (n=276). Patients ranged in age from 27 to 51 years (mean 38.0 years). All patients underwent screening MRI with contrast enhancement. Medical histories and clinical symptoms were evaluated.

Results

Among the 276 patients who underwent MRI, 14 (5.1%) showed degenerated leiomyomas. Symptoms were abdominal pain (n=4, 26.7%), menorrhagia (n=5, 35.7%) and bulk-related symptoms (n=5, 35.7%) and no symptoms (n=5, 35.7%). Of the 14 patients with degenerated leiomyomas, 5 (42.9%) had a history of pregnancy in the past two years. For T1-weighted imaging (T1WI), a high signal intensity (SI) of the leiomyoma was the most common finding (n=9, 64.3%) and a hyperintense rim (n=4, 28.6%) was the second most common. On T2-weighted imaging (T2WI), a low SI of the leiomyoma was found in six patients (42.9%), a high SI in four (28.6%) and a heterogeneous SI in four (28.6%) patients. Conservative management was performed in 11 (78.6%) patients, surgery in 3 (21.4%) and uterine artery embolization in one (7.1%) patient.

Conclusion

The incidence of degeneration of leiomyoma in patients referred for UFE was 5.1%. Patients presented with variable clinical symptoms with or without a history of pregnancy. MR imaging showed a high SI on T1WI and various SIs on T2WI without contrast enhancement. An understanding of the degeneration of leiomyomata is essential when considering UFE.     

T2-weighted fast spin-echo MR findings of adenocarcinoma of the uterine cervix: comparison with squamous cell carcinoma.

The purpose of this study was to investigate the differences in MR findings of adenocarcinoma (AC) and squamous cell carcinoma (SCC) of the uterine cervix and to compare MR findings with pathologic findings. MR images of 17 patients with pathologically proven AC, using a fast spin-echo (FSE) T2-weighted image (T2WI) with pelvic phased-array coil on a 1.5-T unit, were retrospectively evaluated. After measurement of the signal intensity (SI) ratios of the region of interest between tumors and gluteus maximus muscle, we compared the ratios of AC with those of 16 patients with SCC. AC showed relatively high SI on FSE T2WI with multiseptated lesions in four cases and hydrometrocolpos in three cases. The mean SI ratio was 3.82 +/- 1.68 in AC and 2.35 +/- 0.42 in SCC (p < 0.0001, t-test). Multiple tumorous glands with cytoplasmic and intraglandular mucin or serous fluid were pathologically found in AC, but SCC revealed the compact cellularity of stratified squamous tumor cells. The cervical AC showed higher SI than SCC on FSE T2WI with occasional multiseptated lesions and hydrometrocolpos. If the SI ratio of the tumor was more than 3.0, AC could be diagnosed with a sensitivity of 68.8% and a specificity of 100%.     

Magnetic resonance imaging characteristics of deep endometriosis

The aim of this study was to describe magnetic resonance (MR) imaging findings in histopathologically proven deep endometriosis infiltrating the uterosacral ligaments, the pouch of Douglas, the rectum or the bladder. Twenty patients presenting with a clinical suspicion of deep endometriosis underwent preoperative MR imaging. Sagittal and axial fast T2- and axial T1-weighted spin echo MR sequences were performed. Four patients had post-contrast images. MR results, including morphology and signal intensity of each lesion, were compared to intraoperative gross appearance and histopathology. Histopathology diagnosed 24 lesions of deep endometriosis in the uterosacral ligaments (n = 12), the pouch of Douglas (n = 2), the rectum (n = 3), the bladder (n = 7). Uterosacral ligaments with deep endometriosis were statistically different from normal uterosacral ligaments for proximal nodularity (P = 0.001). There was no difference in signal intensity between normal and abnormal uterosacral ligaments. Contrast-enhanced SE images in four patients with detrusor invasion showed an interruption of the hypointense detrusor by the enhancing bladder endometriosis. Rectal endometriosis was missed in two of three patients and showed non-specific rectal wall thickening in one patient. It is concluded that MR imaging can diagnose deep endometriosis of uterosacral ligaments, the bladder and the pouch of Douglas, but lacks sensitivity in detecting rectal endometriosis without rectal distension.     

Successful steroid pulse therapy for brain lesion caused by Shiga toxin 2 in rabbits

Betamethasone sodium phosphate (BSP) is usually used as a steroid therapy for human brain edema. High doses of BSP (36 mg/kg) twice a day for two days statistically reduced the mortality rate and improved the survival period of Stx2 (1.4 μg/kg; 1.6LD₅₀)-toxemic rabbits. We made evaluations on three kinds of magnetic resonance images (MRI) including T1-weighted, T2-weighted, and enhanced MRI using gadopentetate dimeglumine (Gd-DTPA) to detect brain lesion induced by an intravenous injection of Stx2 in rabbits. Enhanced T1-weighted MRI was the most sensitive tool to find leakage of Gd-DTPA suggesting impairment of the blood brain barrier caused by Stx2. Enhanced MRI revealed that BSP treatment inhibited the leakage of Gd-DTPA, as directly evidenced by the protective effect of BSP against brain edema induced by intravenous injection of Stx2. Interleukin 1β was not induced after Stx2 treatment in brain primary mixed cell culture.     

Predictive factors for pelvic magnetic resonance in response to arterial embolization of a uterine leiomyoma

OBJECTIVE:

Minimally invasive methods are used as alternatives to treat leiomyomas and include uterine artery embolization, which has emerged as a safe, effective method. This study aims to evaluate the magnetic resonance imaging predictors for a reduction in leiomyoma volume in patients undergoing uterine artery embolization.

METHODS:

This prospective longitudinal study was performed at a university hospital. We followed 50 symptomatic premenopausal women with uterine leiomyomas who underwent uterine artery embolization. We examined 179 leiomyomas among these patients. Magnetic resonance imaging was performed one month before and six months after uterine artery embolization. Two radiologists who specialized in abdominal imaging independently interpreted the images. Main Outcome Measures: The magnetic resonance imaging parameters were the uterus and leiomyomas volumes, their localizations, contrast perfusion pattern and node-to-muscle ratio.

RESULTS:

Six months after treatment, the average uterine volume reduction was 38.91%, and the leiomyomas were reduced by 55.23%. When the leiomyomas were submucosal and/or had a higher node-to-muscle ratio in the T2 images, the volume reduction was even greater (greater than 50%). Other parameters showed no association.

CONCLUSIONS:

We conclude that symptomatic uterine leiomyomas in patients undergoing uterine artery embolization exhibit volume reductions greater than 50% by magnetic resonance imaging when the leiomyomas are submucosal and/or had a high node-to-muscle ratio in the T2 images.     

Ultra-high b-value diffusion-weighted imaging features of the prostatic leiomyoma-case report

Background

Leiomyoma of the prostate is a rare benign tumor arising from smooth muscle fibers. Most cases are incidental findings observed during pathological examinations after resection of the prostate. To the best of our knowledge, only few studies have reported the conventional magnetic resonance imaging (MRI) findings of such tumors; however, no reports have described the ultra-high b-value diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) findings of prostatic leiomyomas.

Case presentation

We report MR imaging characteristics and surgical pathologic findings of a case of prostatic leiomyoma treated by robot-assisted transperitoneal laparoscopic approach. Typical MR features showed a homogeneous lesion with slightly hypointense signal compared to the skeletal muscle on T2-weighted images, and isointense signal relative to the muscle on T1-weighted images with fat suppression, which collectively demonstrate apparent homogeneous enhancement with a non-enhanced envelope. A slightly hyperintense signal compared to the skeletal muscle was observed on ultra-high b-value DWI, and higher ADC values were observed as compared to the prostate cancer.

Conclusions

Prostatic leiomyoma is a benign tumor. This case indicates that MRI features of prostatic leiomyoma are helpful for the differential diagnosis of prostate cancer.

     

GnRH agonist treatment in girls with precocious puberty does not compromise post-pubertal uterine size

BACKGROUND: Prompted by findings of a hypoestrogenic state in girls during prolonged treatment with GnRH agonist and a close association of estradiol serum concentrations with uterine volume in puberty, this study sought to evaluate uterine and ovarian size in girls with precocious puberty (PP) during and after treatment and the effect of age or duration of treatment. METHODS: Patients with idiopathic central PP before (n = 75), during (n = 41) or after (n = 30) treatment with GnRH agonist underwent transabdominal pelvic ultrasound examination. Findings were compared with those in 69 girls with epilepsy and no PP before initiation of anticonvulsant treatment. RESULTS: The girls with PP had significantly greater uterine and ovarian volumes before, during and after treatment with GnRH agonist than the controls, after adjusting for age at examination, weight, height and pubic and breast status. The average interval between the last treatment and the ultrasound examination was 1.3 years. There was no significant correlation between age at first treatment and uterine volume after treatment. Uterine volume decreased during treatment. There was a significant negative correlation between treatment duration and uterine volume after treatment (R(2) = -0.175, P = 0.024). Nevertheless, mean uterine volume was still greater in the treated group than in the control group (P = 0.002). CONCLUSION: The iatrogenic hypoestrogenic state in treated girls with PP does not compromise post-pubertal uterine size.     

Intraosseous leiomyosarcoma arising in the epiphysis of the distal femur

Herein, we present a rare case of intraosseous leiomyosarcoma arising in the epiphysis of the distal femur and showing unusual radiographic features. A 44-year-old man presented with a pain in the left knee joint. Computed tomography revealed an intraosseous lesion with slightly increased attenuation and a thin marginal sclerotic rim in the femoral medial condyle. The signal of the lesion was hypointense on T1-weighted magnetic resonance (MR) images and hyperintense on fat-suppressed T2-weighted MR images. After gadolinium administration, the signal of the lesion was moderately and diffusely enhanced. The histological diagnosis of leiomyosarcoma was made based on a preoperative core biopsy specimen. Microscopic examination of the resected specimen revealed an ill-defined intraosseous tumor composed of proliferated atypical and mildly pleomorphic smooth muscle cells permeating among the bone trabeculae with only focal destruction of the bone trabeculae and low mitotic activity, indicating low grade leiomyosarcoma. The bone trabeculae at the periphery of the tumor were mildly thickened and anastomosed with a rim of an increased number of osteoblasts. Systemic examination showed no tumorous lesions in other anatomical sites. Leiomyosarcomas rarely present in the bone as a diffuse intertrabecular growth, even in low grade tumors.     

Wavelet compression on detection of brain lesions with magnetic resonance imaging

The purpose of this report is to assess clinically acceptable compression ratios on the detection of brain lesions at magnetic resonance imaging (MRI). Four consecutive T2-weighted and the corresponding T1-weighted images obtained in 20 patients were studied for 109 anatomic sites including 50 with lesions and 59 without lesions. The images were obtained on a 1.5-T MR unit with a pixel size of 0.9 to 1.2 x 0.47 mm and a section thickness of 5 mm. The image data were compressed by wavelet-based algorithm at ratios of 20:1, 40:1, and 60:1. Three radiologists reviewed these images on an interactive workstation and rated the presence or absence of a lesion with a 50 point scale for each anatomic site. The authors also evaluated the influence of pixel size on the quality of image compression. At receiver operating characteristic (ROC) analysis, no statistically significant difference was detected at a compression ratio of 20:1. A significant difference was observed with 40:1 compressed images for one reader (P = .023), and with 60:1 for all readers (P = .001 to .012). A root mean squared error (RMSE) was higher in 0.94- x 0.94-mm pixel size images than in 0.94- x 0.47-mm pixel size images at any compression ratio, indicating compression tolerance is lower for the larger pixel size images. The RMSE, subjective image quality, and error images of 10:1 compressed 0.94- x 0.94-mm pixel size images were comparable with those of 20:1 compressed 0.94- x 0.47-mm pixel size images. Wavelet compression can be acceptable clinically at ratios as high as 20:1 for brain MR images when a pixel size at image acquisition is around 1.0 x 0.5 mm, and as high as 10:1 for those with a pixel size around 1.0 x 1.0 mm.     

Sequential changes of traumatic vertebral compression fracture on MR imaging.

The purpose of this study was to evaluate the sequential signal intensity changes in post-traumatic vertebral compression fractures of varying ages. Sixty-six patients with 115 post-traumatic vertebral compression fractures underwent MR imaging. The ages of fractures at the time of MR images ranged from 1 day to 6 years. Sequential follow-up MR imagings were obtained in 4 patients for 2 years after initial MR examination. The fracture sites in all 52 fractures with traumatic events less than 3 months prior were hypointense on T1-weighted images and hyperintense on T2-weighted images (type I). A type I fracture could be subdivided into 3 patterns depending on its morphologic appearance: diffuse (type Ia); patchy (type Ib); and bandlike (type Ic). In 12 fractures of 3 to 5 months after trauma, six showed focal hypointensity (type II) in all pulse sequences, and six showed isointensity (type IV). Four of 51 fractures with trauma over 5 months showed focal hyperintensity on T1-weighted images and isointensity on T2-weighted images (type III); and the remaining 47 fractures showed isointensity on all sequences (type IV). In conclusion, MR imaging is useful in predicting the age of known traumatic compression fractures, so familiarity with these sequential MR findings would be helpful in distinguishing benign from malignant fractures.     

MRI monitoring of intratumoral drug delivery and prediction of the therapeutic effect with a multifunctional thermosensitive liposome

Non-invasive in vivo imaging of drug distribution enables real-time monitoring and prediction of therapeutic responses to treatment. We have developed a thermosensitive liposomal formulation (HaT: Hyperthermia-activated-cytoToxic) consisting of DPPC and Brij78, a formulation that enhanced drug delivery compared to the lyso-lipid temperature sensitive liposomes (LTSL). Here we report the development of a multifunctional HaT liposome co-encapsulating Gd-DTPA (an MRI probe) and doxorubicin (DOX), which simultaneously releases and reports on drug delivery in a locally heated tumor. The temperature-dependent release profiles of DOX from HaT were closely related to the change in the MR T(1) relaxation time, in which DOX was 100% released at 40-42 °C in 3 min, accompanied by a 60% reduction in T(1). By T(1) relaxometry analysis, no Gd-DTPA leakage was detected in 30 min at 30-37 °C. In the in vivo study, DOX uptake in the tumor was quantitatively correlated with T(1) response (R(2) = 0.98) and the patterns of the T(1) image and the intratumoral DOX uptake were matched, in which both signals were predominantly detected in the highly perfused tumor periphery. Finally, the extent of T(1) relaxation enhancement in the heated tumor successfully predicted the antitumor efficacy in a standard pharmacological response model (R(2) = 0.98).     

Targeted dual-contrast T1- and T2-weighted magnetic resonance imaging of tumors using multifunctional gadolinium-labeled superparamagnetic iron oxide nanoparticles

Development of a multifunctional nanoparticle (NP) system allowing for dual-contrast T(1)- and T(2)-weighted targeted magnetic resonance (MR) imaging of tumors could significantly improve the diagnosis accuracy. In this study, superparamagnetic silica-coated iron oxide core-shell nanoparticles (Fe(3)O(4)@SiO(2) NPs) with a diameter of approximately 21 nm were synthesized via a thermal decomposition approach and were aminated through silanization. The amine-functionalized Fe(3)O(4)@SiO(2) NPs enabled the covalent conjugation of a paramagnetic gadolinium complex (Gd-DTPA, DTPA: diethylenetriamine pentaacetic acid) and an arginine-glycine-aspartic acid (RGD) peptide as a targeting ligand onto their surface. The formed Fe(3)O(4)@SiO(2)(Gd-DTPA)-RGD NPs are water-dispersible, stable, and biocompatible as confirmed by MTT cell viability assay. Relaxivity measurements show that they have a T(1) relaxivity (r(1)) of 4.2 mM(-1) s(-1) and T(2) relaxivity (r(2)) of 17.4 mM(-1) s(-1) at the Gd/Fe molar ratio of 0.3:1, suggesting a possibility to use them as both T(1) positive and T(2) negative contrast agents. In vitro and in vivo MR imaging experiments show that the developed multifunctional Fe(3)O(4)@SiO(2)(Gd-DTPA)-RGD NPs enable targeted dual-contrast T(1)- and T(2)-weighted MR imaging of tumor cells over-expressing high-affinity α(v)β(3) integrin in vitro and in vivo. Our results clearly indicate that the approach to forming multifunctional Fe(3)O(4)@SiO(2)(Gd-DTPA)-RGD NPs could be extended for fabricating other biologically active NPs for T(1)- and T(2)-weighted MR imaging of other biological systems with high accuracy.     

Cotyledonoid dissecting leiomyoma of the uterus: a review of clinical, pathological, and radiological features

Cotyledonoid dissecting leiomyoma is a rare benign uterine tumor whose gross and radiological appearance may raise the possibility of a malignancy. The authors summarize herein the clinical, radiological, and pathological features of the 41 previously reported cases. The patients typically presented with menorrhagia or symptoms that were ultimately relatable to the presence of a pelvic mass. The median patient age was 46 years (range 23-73). The average tumor size was 15.4 cm (range 4-41); most were exophytic, multinodular, occasionally cystic masses with a congested, spleen or placenta-like color, protruding over the uterine serosa and, variably, the broad ligaments and adjacent organs. In most cases, the exophytic component was contiguous with the intramural dissecting leiomyomatous components. Histological features suggestive of malignancy, such as cytological atypia, necrosis, or increased mitotic activity were absent. Intravascular growth, as assessed histologically, was present in 20% of reported cases, and this finding is apparently devoid of clinical significance based on limited data. Reported information on radiological features is limited. However, these lesions are typically isointense to myometrium on T1-weighted MRI and are in general less heterogeneous on T2 and postcontrast-imaging than sarcomatous lesions. The tumor may display extension to but not frank invasion of surrounding organs. Ultrasound features are nonspecific. Follow-up information was available in 25 (61%) of 41 reported patients: none experienced a tumor recurrence or metastases during the follow-up period, which ranged from 1 month to 41 years. This affirms the benign nature of this tumor, its alarming gross appearance and growth patterns notwithstanding.     

Stem cell implantation in ischemic mouse heart: a high-resolution magnetic resonance imaging investigation

Advances in the biology of stem cells have evoked great interest in cell replacement therapies for the regeneration of heart tissue after myocardial infarction. However, results from human trials are controversial, since the destination of the injected cells, their engraftment and their long-term fate have remained unclear. Here we investigate whether transplanted cells can be identified in the intact and lesioned murine myocardium employing high-resolution MRI. Cardiac progenitor cells, expressing the enhanced green fluorescent protein (EGFP), were labeled with ultra-small paramagnetic iron-oxide (USPIO) nanoparticles and transplanted into the intact or injured myocardium of mice. Their precise location was determined with high-resolution MRI and compared with histological tissue sections, stained with Prussian blue for iron content. These experiments showed that iron nanoparticle-loaded cells could be identified at high resolution in the mouse heart. However, ischemic myocardium (after cryoinjury or left coronary artery ligation) was characterized by a signal attenuation similar to that induced by USPIO-labeled cells in T2*-weighted MR images, making detection of labeled stem cells in this area by T2*-sensitive contrast rather difficult. In animals with myocardial injury only, the signal attenuated areas were of the same size in proton density- and T2*-weighted MR images. In injured animals also receiving labeled cells the lesioned area appeared larger in T2*--than in proton density-weighted MR images. This sequence-dependent lesion size change is due to the increased signal loss caused by the iron oxide nanoparticles, most sensitively detectable in the T2*-sensitive images. Thus, using the novel combination of these two parameter weightings, USPIO-labeled cells can be detected at high resolution in ischemic myocardium.