3D reconstruction of the skeletal anatomy of the normal neonatal foot using 3D ultrasound

Currently imaging plays a limited role in the assessment of the neonate with a foot deformity. The aim of this study was to establish a technique for examining the neonatal foot with three-dimensional ultrasound (3D US). 3D US was attempted on the normal feet of 20 infants (9 male, 11 female) under 6 weeks old (range 35-41 days). The data sets were obtained whilst the infants were feeding or asleep to minimize movement artefact. A high-resolution optically tracked freehand 3D US system (Diasus, 16 MHz transducer) was used with Stradx software to acquire and analyse the data sets. Manual segmentation of the non-ossified tarsi from the data sets was performed. Five infants were too restless to be examined. 107 data sets were recorded from 22 feet of the remaining 15 infants. 21 of the data sets were discarded due to movement artefact. 86 were suitable for manual segmentation. Surface interpolation of the segmented data sets produced surface rendered reconstructions illustrating the complex 3D anatomy of the foot. This new technique may offer a method of examining the deformed foot, e.g. congenital talipes equinovarus.     

Validation of injection parameters for catheter-directed intraarterial gadolinium-enhanced MR angiography

RATIONALE AND OBJECTIVES: Catheter-directed intraarterial (IA) injections of gadolinium contrast agents may be used during endovascular interventions with magnetic resonance (MR) imaging guidance. Injection protocols require further validation. Using a flow phantom and swine, the authors aimed to (a) measure the optimal arterial gadolinium concentration ([Gd]) required for MR angiography and (b) validate a proposed IA injection protocol for gadolinium-enhanced MR angiography. MATERIALS AND METHODS: For in vitro experiments, the authors placed a catheter in the aorta of an aorto-renal-iliac flow phantom. Injected [Gd], injection rates, and aortic blood flow rates were varied independently for 36 separate IA gadolinium injections. The authors performed 2D and 3D MR angiography with a fast spoiled gradient-recalled echo sequence. For subsequent in vivo experiments, they selectively placed catheters within the aorta, renal artery, or common iliac artery of three pigs. Injection rate and injected [Gd] were varied. The authors performed 32 separate IA gadolinium injections for 2D MR angiography. Signal-to-noise ratios (SNRs) were compared for the various combinations of injection rate and injected [Gd]. RESULTS: In vitro, an arterial [Gd] of 2%-4% produced an optimal SNR for 2D MR angiography, and 3%-5% was best for 3D MR angiography. In swine, an arterial [Gd] of 1%-4% produced an optimal SNR. In the phantom and swine experiments, SNR was maintained at higher injection rates by inversely varying the injected [Gd]. CONCLUSION: Dilute arterial [Gd] is required for optimal IA gadolinium-enhanced MR angiography. To maintain an optimal SNR, injection rates and injected [Gd] should be varied inversely. The postulated injection protocol was validated.     

Sentinel lymph node detection in patients with early-stage breast cancer: comparison of periareolar and subdermal/peritumoral injection techniques.

Periareolar (PA) injection offers several potential advantages over other techniques for visualizing sentinel lymph nodes (SLNs) in patients with early breast cancer. However, few studies have been published on this procedure. This study was designed to validate PA injection technique and compare it with the subdermal/peritumoral (SD/PT) injection technique. METHODS: The study included 324 patients in whom 330 breast cancers (T) had been identified by biopsy. This population was divided in 4 groups: (A) 148 patients (150 T) in whom lymphatic mapping was performed by injecting radiotracer with the SD/PT technique; (B) 59 patients (60 T) in whom lymphatic mapping was performed with a combination of blue dye injected with the PA technique and radiotracer injected with the SD/PT technique; (C) 58 patients (60 T) in whom blue dye was injected subdermally and radiotracer was injected periareolarly; and (D) 59 patients (60 T) in whom both blue dye and radiotracer were injected periareolarly. RESULTS: Concordances in the SLN detection rate between blue dye and radiotracer in groups B, C, and D were 98.1%, 100%, and 100%, respectively. The SLN identification rates with the PA technique were 98.3% and 95%, respectively, for radiotracer and blue dye. With the SD/PT technique, these rates were 90.5% and 88.3%, respectively, for radiotracer and blue dye. At lymphoscintigraphy, SLN visualization required the acquisition of late images (3 h after the injection) in 20% of patients who received PA injections and 39.5% of patients who received SD/PT injections. CONCLUSION: These findings validate the PA injection technique and underline some of its reported advantages in comparison with the SD/PT technique.     

An experimental evaluation of central vs. peripheral injection for intravenous digital subtraction angiography (IV-DSA)

At a given radiation dosage and field of view, five variables are under meaningful control for intravenous digital subtraction angiography (IV-DSA): concentration and quantity of contrast media injected, volume of injectate, rate of injection, and site of injection. Some controversy exists regarding the selection of a central vs. a peripheral injection site for IV-DSA. This study determined the influence of the site of injection on the peak and width of the arterial time-concentration curve produced by contrast media. Using a noninvasive, in vivo, quantitative x-ray measurement method, 36 separate injections (10 ml of ioxaglate at 8 ml/sec) were administered into the cephalic vein, subclavian vein, and main pulmonary artery in dogs. Injection sites were varied using a Latin-square experimental design. Cardiac output, central blood volume and the peak and width of the contrast media time-concentration curves were measured. The average peak enhancement was greatest for the pulmonary artery injection site. Normalizing peak and width values to make the pulmonary artery values 100%, the average peak values for injections into the subclavian vein and cephalic vein were 93% and 56%, and the average widths were 141% and 163%, respectively. These data support the use of a more central injection site for optimizing IV-DSA examinations.     

Delivery of systemic chemotherapeutic agent to tumors by using focused ultrasound: study in a murine model

PURPOSE: To quantitatively determine the delivery of systemic liposomal doxorubicin to tumors treated with pulsed high-intensity focused ultrasound and to study the mechanism underlying this delivery in a murine model. MATERIALS AND METHODS: All animal work was performed in compliance with guidelines and approval of institutional animal care committee. C3H mice received subcutaneous injections in the flank of a cell suspension of SCC7, a murine squamous cell carcinoma cell line; mice (n = 32) in drug delivery study received unilateral injections, whereas mice (n = 10) in mechanistic study received bilateral injections. Tumors were treated when they reached 1 cm(3) in volume. In the drug delivery study, doxorubicin hydrochloride liposomes were injected into the tail vein: Mice received therapy with doxorubicin injections and high-intensity focused ultrasound, doxorubicin injections alone, or neither form of therapy (controls). Tumors were removed, and the doxorubicin content was assayed with fluorescent spectrophotometry. In the mechanistic study, all mice received an injection of 500-kDa dextran-fluorescein isothyocyanate into the tail vein, and half of them were exposed to high-intensity focused ultrasound prior to injection. Contralateral tumors served as controls for each group. Extravasation of dextran-fluorescein isothyocyanate was observed by using in vivo confocal microscopy. RESULTS: Mean doxorubicin concentration in tumors treated with pulsed high-intensity focused ultrasound was 9.4 microg . g(-1) +/- 2.1 (standard deviation), and it was significantly higher (124% [9.4 microg . g(-1)/4.2 microg . g(-1)]) than in those that were not treated with high-intensity focused ultrasound (4.2 microg . g(-1) +/- 0.95) (P < .001, unpaired two-tailed Student t test). Extravasation of dextran-fluorescein isothyocyanate was observed in the vasculature of tumors treated with high-intensity focused ultrasound but not in that of untreated tumors. CONCLUSION: Pulsed high-intensity focused ultrasound is an effective method of targeting systemic drug delivery to tumor tissue. Potential mechanisms for producing the observed enhancement are discussed.     

Toluidine blue dye as a breast localization marker

We compared the efficacy of toluidine blue dye vs methylene blue as a visual marker for breast localizations in vitro and in vivo. In phase 1, the dyes were injected into 10 mastectomy specimens and allowed to diffuse for 24-48 hr. In phase 2, the breasts of four premastectomy patients were injected with the dyes and the dyes were allowed to diffuse for 3 3/4, 12, 24, and 47 hr before mastectomy. In phase 3, the breasts of 18 women in whom 20 breast localizations were performed before excisional biopsy were injected with methylene blue or toluidine blue up to 2 hr 10 min before the biopsy. All excised stained breast tissue was evaluated blindly. The amount of pain associated with injections of the dye was recorded. The 22 women in phases 2 and 3 had had mammograms before, and the parenchymal patterns had been classified according to Wolfe. In the patients injected 3 3/4, 12, 24, and 47 hr before mastectomy, more intense staining with less diffusibility was seen with toluidine blue than with methylene blue. In the 20 localization procedures before excisional biopsy, no difference in intensity of staining or radius of diffusion was seen between methylene blue and toluidine blue with maximal diffusion times of 2 hr 10 min. Breast parenchymal pattern did not correlate with stain intensity or diffusibility. The six patients in whom both methylene blue and toluidine blue were injected and the 18 patients in whom either dye was injected felt less discomfort at the time of injection of toluidine blue than of methylene blue. Our results suggest that toluidine blue causes less discomfort and produces a more intense stain with a smaller diffusion radius than methylene blue regardless of breast parenchymal pattern.     

Comparison of different injection sites of radionuclide for sentinel lymph node detection in breast cancer: single institution experience

BACKGROUND: There are still ongoing controversies about several aspects of lymphatic mapping and sentinel lymph node biopsy for breast cancer, including injection site of radioisotope and blue dye. This study aims to evaluate the success rate of different radiocolloid injection techniques in the detection of sentinel lymph nodes (SLN) in early breast cancer. STUDY DESIGN: One hundred ninety-two women with early breast cancer were included. For SLN mapping with lymphoscintigraphy (LSG), 5 different injections were used. Group A (36 patients) had 4 peritumoral (PT), group B (n = 36) had 1 subdermal (SD) injection of Tc-99m rhenium sulfide colloid over the tumor quadrant. Group C (59 patients) had 1 PT and 1 SD combined injections. In group D (56 patients), lymphatic mapping was performed with 2 intradermal periareolar (ID-PA) injections. In group E (n = 41), 2 ID-PA and 1 PT combined injections were performed. Early dynamic and delayed images were obtained. A surgical gamma probe was used to explore the SLNs. Surgical specimens were evaluated histopathologically. The SLN identification rate, false negative rate, and comparison of groups were evaluated by statistical methods. RESULTS: The SLN identification rate by LSG in groups A, B, C, D, and E were 72%; 92%, 93.2%, 98%, and 95%, respectively. The highest detection rates for the axilla (98%) and mammary internal (MI) drainage (22%) were obtained with ID-PA injections and a peritumoral injection, respectively. Seventy of 192 patients (36.4%) had positive axillary lymph nodes. The only statistically significant difference was between the PT and SD injection groups in axillary SLN identification rate by LSG (P = 0.016). CONCLUSION: The success rate was superior with intradermal periareolar injection compared with PT and SD injection to visualize the axillary SLN. However, PT deep injection combined with ID-PA injections may be more favorable to demonstrate the primary internal mammary (IM) lymphatic drainage.     

The use of periareolar intradermal Tc-99m tin colloid and peritumoral intraparenchymal isosulfan blue dye injections for determination of the sentinel lymph node

PURPOSE: The purpose of the present study was to evaluate the use of lymphoscintigraphy, blue dye, and gamma probe detection methods for determination of the sentinel lymph node (SLN) using both periareolar intradermal injection of Tc-99m tin colloid and peritumoral intraparenchymal injection of isosulfan blue dye. METHODS: One hundred patients with T1-2 breast cancer and clinically negative nodes were enrolled in the present study. The study was composed of 2 groups. Backup axillary lymph node dissection (ALND) was mandatory in group 1 (20 patients) regardless of their lymph node status. In group 2 (80 patients), complete ALND was performed when intraoperative frozen section analysis of SLN revealed metastases. Otherwise, only SLN biopsy was performed without ALND. One day before surgery, Tc-99m tin colloid was injected at 4 periareolar sites intradermally. Lymphoscintigraphy was performed 1 to 2 hours after injection of the radiocolloid. Twenty minutes before surgery, isosulfan blue dye was injected into parenchyma surrounding the tumor or the biopsy cavity. RESULTS: The detection rates of SLN and false-negative rate of lymphoscintigraphy, blue dye, and gamma probe detection were 85%, 95% 100%, and 0% in group 1, 91%, 87%, and 95% in group 2, respectively. Detection rate by the combination of blue dye and radio tracer was 98%. CONCLUSIONS: According to the results of our study, we conclude that perioareolar intradermal injection of Tc-99m tin colloid combined with peritumoral intraparenchymal injection of blue dye is an accurate and easy method of locating the sentinel node with very high detection rates. It is recommended that the combination of all methods such as lymphoscintigraphy, blue dye, and gamma probe application will increase the success rate of SLN detection in patients with breast cancer.     

Estimation of intra-operator variability in perfusion parameter measurements using DCE-US

AIM:To investigate intra-operator variability of semiquantitative perfusion parameters using dynamic contrast-enhanced ultrasonography(DCE-US),following bolus injections of SonoVue.METHODS:The in vitro experiments were conducted using three in-house sets up based on pumping a fluid through a phantom placed in a water tank.In the in vivo experiments,B16F10 melanoma cells were xenografted to five nude mice.Both in vitro and in vivo,images were acquired following bolus injections of the ultrasound contrast agent SonoVue(Bracco,Milan,Italy) and using a Toshiba Aplio ultrasound scanner connected to a 2.9-5.8 MHz linear transducer(PZT,PLT 604AT probe)(Toshiba,Japan) allowing harmonic imaging("Vascular Recognition Imaging") involving linear raw data.A mathematical model based on the dye-dilution theory was developed by the Gustave Roussy Institute,Villejuif,France and used to evaluate seven perfusion parameters from time-intensity curves.Intra-operator variability analyses were based on determining perfusion parameter coefficients of variation(CV).RESULTS:In vitro,different volumes of SonoVue were tested with the three phantoms:intra-operator variability was found to range from 2.33% to 23.72%.In vivo,experiments were performed on tumor tissues and perfusion parameters exhibited values ranging from 1.48% to 29.97%.In addition,the area under the curve(AUC) and the area under the wash-out(AUWO) were two of the parameters of great interest since throughout in vitro and in vivo experiments their variability was lower than 15.79%.CONCLUSION:AUC and AUWO appear to be the most reliable parameters for assessing tumor perfusion using DCE-US as they exhibited the lowest CV values.     

Impact of Yttrium-90 Microsphere Density,Flow Dynamics,and Administration Technique on Spatial Distribution: Analysis Using an In Vitro Model

Purpose

To investigate material density, flow, and viscosity effects on microsphere distribution within an in vitro model designed to simulate hepatic arteries.

多层面螺旋CT仿真胆管内窥镜在胆管系统结石的初步临床应用

目的探讨多层面螺旋CT胆道仿真内窥镜（Multi-slicehelicCTvirtualcholangioscopy,MSCTVC)在胆管系统结石诊断中的检查方法和临床应用价值。方法选择38例经B超检查后诊断为胆管系统结石的患者外周静脉滴注50%胆影葡胺20ml行多层面螺旋CT容积扫描,将容积数据薄层重建后传输至工作站,利用Navigator导航软件重建成仿真内窥镜图像,全部病例经B超、CT轴位图像、多层面螺旋CT三维成像（SSD、MIP、Raysum）证实。结果多层面螺旋CT胆道仿真内窥镜可精确显示结石所在部位、结石的形态、大小,与B超、多层面螺旋CT二维（轴、矢、冠状位）图像及三维成像（SSD、MIP、Raysum）具有良好的对应性,尤其对于在轴位CT不能显示的阴性结石通过胆道仿真内窥镜可清晰显示。结论MSCTVC结合CT二维、三维图像对胆管结石的诊断有较高的准确性和临床使用性,提高了胆管系统结石的诊断能力。     

Interstitial magnetic resonance lymphography with gadobutrol in rats: evaluation of contrast kinetics

RATIONALE AND OBJECTIVE: To evaluate the contrast kinetics of gadobutrol for interstitial MR lymphography. MATERIALS AND METHODS: In 11 rats, 0.5 mL undiluted gadobutrol was injected subcutaneously into the hind paw. Contrast kinetics were measured in lymph nodes, kidney, liver, muscle, and blood of six animals using a time-resolved 2D GRE sequence. Additionally, high-resolution 3D T1-weighted data sets were obtained in five animals. RESULTS: Immediately after injection, a pronounced signal intensity loss was observed in popliteal, inguinal and aorto-iliac lymph nodes, followed by a continuous signal intensity increase. From the data peak concentrations of up to 78 mmol/L were estimated for selected lymph nodes. A contrast enhancement was also observed in kidneys, liver, muscle, and blood. Regional lymphatic vessels, the thoracic duct, as well as popliteal, inguinal, aorto-iliac, and axillary lymph node groups could be visualized with the high-resolution 3D MRI. CONCLUSION: Gadobutrol is suitable for interstitial MR lymphography, as it rapidly appears in the lymphatic system. Based on estimates of local tissue concentrations future studies have to assess the optimal contrast agent dosage. Furthermore, the investigation of metastatic lymph nodes is required to evaluate the further potential of gadobutrol for interstitial MR lymphography.     

Areolar-cutaneous "junction" injections to augment sentinel node count activity

PURPOSE: The authors report on a modified lymphoscintigraphy protocol for increasing activity in the sentinel node (SN) through a specific technique (LymphoBoost). It consists of an areolar-cutaneous "junction" injection, using a very shallow, high-volume, high-specific-activity injection of 100% filtered Tc-99m sulfur colloid, as an adjunct to their standard protocol. MATERIALS AND METHODS: Results from a previously optimized protocol (group 1, n = 28) were compared with those from their new protocol (group 2, n = 85), which consisted of two sets of consecutively applied (within 12 to 20 minutes) injections: group 2A composed of perilesional and intradermal injections (similar to the previous group 1) followed by group 2B LymphoBoost injections within 12 to 20 minutes in the same patients. Regions of interest were drawn around the SN and the injection sites (IS) at the end of the studies to calculate the end-of-study SN:IS ratio for both group 1 and group 2 studies. The SN:IS ratio is generally independent of dose and is a measurement of the "efficiency" of getting activity from the IS to the SN. RESULTS: The mean SN:IS ratio in group 2 was 3.34 times greater than that in group 1 studies (P < 0.0005). The median SN:IS ratio was 3.53 times greater in the group 2 studies. Many cases showed a dramatic increase in SN counts before the LymphoBoost injection was even completed, with more than 5% of injected activity reaching nodes at the end of the study in some patients. Multiple different lymphatic pathways were noted, but all led to the same node(s). No significant disagreement between group 2A and group 2B results was noted. CONCLUSIONS: Areolar-cutaneous junction injections, performed under these conditions, augment SN activity dramatically in most patients. Hotter nodes provide several benefits, especially when next-day surgery is contemplated, and should also reduce the extent of dissection needed to remove the sentinel node.     

Defining the medial-lateral axis of an anatomical femur coordinate system using freehand 3D ultrasound imaging

Hip rotation from gait analysis informs clinical decisions regarding correction of femoral torsional deformities. However, it is among the least repeatable due to discrepancies in determining the medial-lateral axis of the femur. Conventional or functional calibration methods may be used to define the axis but there is no benchmark to evaluate these methods. Freehand 3D ultrasound, the coupling of ultrasound with 3D motion capture, may provide such a benchmark.We measured the accuracy in vitro and repeatability in vivo of determining the femur condylar axis from freehand 3D ultrasound. The condylar axis provided the reference medial-lateral axis of the femur and was used to evaluate one conventional method and three functional calibration methods, applied to three calibration movements. Ten healthy subjects (20 limbs) underwent 3D gait analysis and freehand 3D ultrasound. The functional calibration methods were a transformation technique, a geometrical method and a method that minimises variance of knee varus-valgus kinematics (DynaKAD). The conventional method used markers over the femoral epicondyles.The condylar axis determined by 3D ultrasound showed good accuracy in vitro, 1.6° (SD: 0.3°) and good repeatability in vivo, 0.2° (RSMD: 2.3°). The DynaKAD method applied to the walking calibration movement determined the medial-lateral axis closest to the ultrasound reference. The average angular difference in the transverse plane was 3.1° (SD: 6.1°).Freehand 3D ultrasound offers an accurate, non-invasive and relatively fast method to locate the medial-lateral axis of the femur for gait analysis.     

High-resolution slice-selective Fourier velocity encoding in congenital heart disease using spiral SENSE with velocity unwrap

Quantification of peak velocity is important in the assessment of stenotic flow jets in patients with congenital heart disease. Phase-contrast magnetic resonance underestimates peak velocities. Hence, clinically Doppler ultrasound is used as the reference standard for assessing stenoses. It is possible to accurately measure peak velocity in MR using Fourier velocity encoding (FVE). In this study, a fast, high-resolution slice-selective FVE sequence was developed with the use of spiral trajectories, parallel imaging, and partial Fourier in the velocity dimension and a novel velocity-unwrap technique. The resulting sequence was acquired within a short breath-hold (more than 15 heartbeats) making this FVE technique clinically achievable. Peak velocities were compared from Doppler ultrasound, phase-contrast magnetic resonance, and FVE. Experiments were carried out in vitro and in vivo in 25 patients with congenital heart disease with stenoses. It was shown that in vitro and in vivo phase-contrast magnetic resonance tended to underestimate peak velocity when compared with Doppler ultrasound, whereas FVE agreed well with Doppler ultrasound.     

Variables influencing tumor uptake of anti-melanoma monoclonal antibodies radioiodinated using para-iodobenzoyl (PIB) conjugate

Tumor uptake was examined with respect to antigen expression, time-dependent biodistribution, dose of Mab injected, tumor size, and tumor site (i.e., subcutaneous versus lung or liver metastases). NR-ML-05, 96.5, and P94 showed significantly greater uptake in subcutaneous tumors than CL207 and 5.1 (p less than 0.05). NR-ML-05 had a significantly higher tumor uptake at 24 hr (11.9 +/- 0.51) than at 72 hr (4.0 +/- 0.37) or 144 hr (2.7 +/- 0.84) after injection (p less than 0.001). The other four Mabs had similar tumor distribution at all three time points. The tumor uptake of four Mabs (96.5, P94, CL207. 5.1) differed with respect to in vitro versus in vivo binding to tumor, tumor type, dose of Mab, and tumor site (subcutaneous versus metastases). In contrast, NR-ML-05 demonstrated consistent uptake in tumors independent of the above parameters. These data suggest that certain host parameters can influence in vivo tumor targeting depending on characteristics of each Mab studied.     

Intramuscular injections into the buttocks: Are they truly intramuscular?

AIM: To radiologically determine if intramuscular (IM) injections into the buttocks are truly intramuscular. MATERIALS AND METHODS: This was a prospective study conducted during a 6 month period beginning in October 2004. Fifty inpatients were recruited from a single tertiary referral hospital. Approval was obtained from the hospital research ethics committee and informed written consent was acquired from all participants. Prior to computerised tomography (CT), each patient received an IM injection of their prescribed medication along with 1 mL of air into the upper outer quadrant of the buttocks. CT images were subsequently analyzed by two radiologists to determine the position of the injected air bubble and to assess whether it was intramuscular or subcutaneous in position. Body mass index (BMI), distance to injection site, subcutaneous fat and muscle thickness were also measured. RESULTS: Overall, only 32% (n=16/50) of patients had intramuscular injections, with the majority of injections (68%, n=34/50) being subcutaneous. When analysed by gender, 56% (n=14/25) of males had intramuscular injections while in females, the efficacy rate was significantly lower at 8% (n=2/25). CONCLUSION: The majority of assumed intramuscular injections are actually subcutaneous.     

In vivo MR tracking of mesenchymal stem cells in rat liver after intrasplenic transplantation

PURPOSE: To prospectively track in vivo in rats intrasplenically transplanted stem cells labeled with superparamagnetic particles by using magnetic resonance (MR) imaging. MATERIALS AND METHODS: The study was approved by the institutional Committee on Animal Research. Liver damage in 12 rats was induced with subcutaneous injection of carbon tetrachloride (CCl4). Intrasplenic transplantation of 6x10(6) rodent bone mesenchymal stem cells (BMSCs) with (n=6) and without (n=6) superparamagnetic particle Fe2O3-poly-L-lysine (PLL) labeling was performed via direct puncture. Cell labeling efficiency was assessed in vitro by using Prussian blue stain and an atomic absorption spectrometer. MR examinations were performed immediately before and 3 hours and 3, 7, and 14 days after transplantation. Liver-to-muscle contrast-to-noise ratios (CNRs) on T2*-weighted MR images obtained before and after injection were measured and correlated with histomorphologic studies. Statistical analyses were performed by using repeated-measures analysis of variance. RESULTS: Rat BMSCs could be effectively labeled with approximately 100% efficiency. Migration of transplanted labeled cells to the liver was successfully documented with in vivo MR imaging. CNRs on T2*-weighted images decreased significantly in the liver 3 hours after injection of BMSCs (P<.05) and returned gradually to the level achieved without labeled cell injection in 14 days. Histologic analyses confirmed the presence of BMSCs in the liver. The labeled cells primarily localized in the sinusoids of periportal areas and the foci of CCl4-induced liver damage. Quantitative analysis of Prussian blue-stained cells indicated gradual decrease of dye pigments from 3 hours to 3, 7, and 14 days after injection. No free iron particles were found in the interstitium or within hepatic microvessels. CONCLUSION: The rat BMSCs could be efficiently labeled with Fe2O3-PLL and the relocation of the labeled cells to rat livers after intrasplenic transplantation could be depicted at in vivo MR imaging.     

In vitro echogenicity characterization of poly[lactide-coglycolide] (plga) microparticles and preliminary in vivo ultrasound enhancement study for ultrasound contrast agent application

OBJECTIVES: This work includes (1) the characterization of a reproducible poly[lactide-coglycolide] (PLGA) microparticle preparation with an optimial mean diameter and size distribution and (2) the preliminary in vivo ultrasonographic investigation of PLGA microparticles. METHODS: A first series of PLGA microparticle preparations (1 to 15 mum) was acoustically characterized on a hydrodynamic device to select the most appropriate for ultrasound contrast agent application. Preparations of 3-microm microparticles were selected, characterized at different doses, and then injected into 20 melanoma grafted mice for contrast-enhanced power Doppler ultrasonography evaluation. RESULTS: The 3-microm microparticles (3.26-microm mean diameter with 0.41-microm standard deviation) led to in vitro enhancement of 18.3 dB at 0.62 mg/mL. In vivo experiments showed 47% enhancement of intratumoral vascularization detection after PLGA injection, significantly correlated (P < 0.0001) with preinjection intravascularization and tumoral volume. No toxicity was histologically observed. CONCLUSION: The 3-microm PLGA microparticles provided significant enhancement in vitro and in vivo without any toxicity.     

Volumetric assessment of carotid artery bifurcation using freehand-acquired, compound 3D ultrasound.

The aim of this study was to establish the reproducibility of sequential three-dimensional (3D) ultrasound reconstructions of an identified segment of the carotid artery bifurcation in asymptomatic subjects. A freehand acquisition, compound reconstruction, 3D ultrasound system was used on three occasions, over a period of 1 year. The lumen of the vessel was reconstructed to provide a volume measurement and a rotatable 3D structure representation that could be examined for geometrical correspondence. The four subjects differed significantly in the visualized 3D geometry of the vessel bifurcation. There was good correspondence in the sequential reconstructions for each individual in both the 3D geometry and in the measured lumen volume, with an overall coefficient of variation of 5% and no evidence of deterioration in correlation with time.