Signal Void Areas Research Articles

In vivo tracking human bone marrow-derived mesenchymal stem cells after genetically modified

Objective To evaluate in vivo magnetic resonance imaging (MRI) for tracking the magnetically labeled human bone marrow-derived mesenchymal stem cells (hBMSCs) which sliencing of cyclooxygenase-2 (COX-2) transplanted into nude rat through tail vein injection. Methods In the present study, we knockdown COX-2 in hBMSCs by lentivirus infection, detected the expression of COX-2 by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. Then labeled with new superparamagnetic iron oxide (SPIO)-Molday ION Rhodamine-B™ (MIRB), Cell viability, proliferation and differentiation capacity were assessed in vitro using appropriate functional assays. Labeled lenti-shCOX2 hBMSCs, hBMSCs, phosphate buffered saline (PBS) were divide into three groups injected into tail vein of nude rat models, respectively. All nude rats underwent GRE T2*-weighted MRI 1 h, 7 and 14 days post-injection. After MRI examination, the animals were sacrificed, the brain and liver were prepared for fluorescence observation and prussian blue staining. Results This study confirmed that we down-regulated COX-2 at mRNA and protein level in hBMSCs cells by lentivirus infection successfully. MIRB positive cells were over 90% for cells labeled with MIRB (10 μg Fe/ml)and more than 98% for cells labeled with MIRB (20-50 μg Fe/ml). The resulte shows that<50 μg Fe/ml MIRB labeling did not affect hBMSC viability or the ability to differentiate into either bone or fat. At the 7 day, the hypointense signal void areas of livers was observed on GRE T2-weighted MR images and intensified and increased over time. At the 14 day after cell transplantation, iron particles were located in liver blood vessel, sinusoids, interlobular septum and capsule. Conclusion The MIRB labeled lenti-shCOX2 hBMSCs transplanted into nude rat through tail vein can be detected and monitored in vivo with a 3.0 T clinical MRI for up to 14 days after cell transplantation. Key words: Cyclooxygenase-2; Lentivirus; Molday ION Rhodamine-B™; Mesenchymal stem cells transplantation; Magnetic resonance imaging

Atrial Fibrillation and Microbleeds.

See releated articles, pp 2653, 2654, 2665, 2671 Atrial fibrillation (AF) is a common cause of cardioembolism and ischemic stroke (IS). Long-term oral anticoagulation (OAC) is the mainstay therapy for IS prevention in patients with AF. However, uncertainties exist about the safety of OAC in AF patients with coexisting cerebral microbleeds (CMBs). Several studies suggest that individuals with CMBs seem to be at increased risk for future stroke, in particular intracerebral hemorrhage (ICH).1–4 Also, the presence and number of CMBs seem to correlate with CHADS2 and CHADS2-VASC scores (congestive heart failure/left ventricular systolic dysfunction, hypertension, age ≥75 years, diabetes mellitus, stroke or TIA or thromboembolism, vascular disease), which are used to estimate IS risk in patients with AF.5,6 As a result, the detection of CMBs often raises the following host of questions and leads to a therapeutic dilemma. 1. Does the detection of CMBs in patients with AF imply high risk for ICH to offset any benefit from OAC? 2. Are predictive scales for the risk of bleeding or IS in patients with AF useful to stratify the risk/benefit and to aid with decision-making? 3. Does the burden and anatomic location of CMBs influence risks for future ICH? We will address these questions in this review and attempt to provide a pragmatic approach to the treatment of AF in patients with CMBs. CMBs represent hemosiderin deposits caused by minor bleeding from microangiopathy.7 They are often seen as small (usually <10 mm) hypointense dark areas of signal void on susceptibility-weighted or gradient-echo T2*-weighted magnetic resonance imaging (MRI). Overall, CMBs are associated with many of the classical risk factors for cerebrovascular disease8 but are most commonly associated with cerebral amyloid angiopathy (CAA) and poorly controlled hypertension. The distribution of CMBs seems …

Metal Artifact Reduction Magnetic Resonance Imaging Around Arthroplasty Implants: The Negative Effect of Long Echo Trains on the Implant-Related Artifact.

Long echo train length (ETL) is an often recommended but unproven technique to decrease metal artifacts on magnetic resonance imaging (MRI) scans. Therefore, we quantitatively and qualitatively assessed the effects of ETL on metal artifact on MRI scans using a cobalt-chromium-containing arthroplasty implant system. Using a total ankle arthroplasty system implanted into a human cadaver ankle and a clinical 1.5 T MRI system, turbo spin echo (TSE) pulse sequences were acquired with ETL ranging from 3 to 23 and receiver bandwidth (BW) from 100 to 750 Hz/pixel, whereas effective echo time and spatial resolution were controlled. A compressed sensing slice encoding for metal artifact correction TSE prototype pulse sequence was used as reference standard. End points included the total implant-related artifact area and implant-related signal void areas. Two raters evaluated the overall image quality and preference across varying BW and ETL. Two-factor analysis of variance, Friedman test, Kruskal-Wallis test, and Pearson correlation were used. P values of less than 0.05 were considered statistically significant. The total implant-related artifact area ranged from 0.119 for compressed sensing slice encoding for metal artifact correction (BW, 600 Hz/pixel; ETL, 3) to 0.265 for TSE (BW, 100 Hz/pixel; ETL, 23). Longer ETL significantly increases the total implant-related artifact area (P = 0.0004), whereas it decreased with increasing BW (P < 0.0001). Implant-related signal void areas were not significantly affected by larger echo train length, but reduced with higher BW (P < 0.0001). Readers had a significant preference for images with high BW and short ETL (P < 0.0001). High receiver BW is the most effective parameter for reduction of arthroplasty implant-induced metal artifact on MRI scans, whereas in contradiction to prevalent notions, long echo trains fail to reduce implant-related metal artifacts, but in fact cause degradation of image quality around the implant with resultant larger appearing total metal artifacts.

New radiological clues in the diagnosis of spindle cell oncocytoma of the adenohypophysis

To present three new cases of spindle cell oncocytoma (SCO) from a single centre and to identify new radiological clues in the diagnosis of SCO according to the information obtained from the cases presented. Three adults with SCO confirmed at histopathology were retrospectively reviewed. The medical records, imaging findings, operative notes, and histopathology findings for each patient were recorded. Magnetic resonance imaging (MRI) findings were evaluated, including tumour localisation, tumour size, signal intensity, imaging features on T1-weighted and T2-weighted images, and contrast enhancement characteristics. The study protocol was approved by the institutional review board. Informed consent was obtained from each patient. T1-weighted imaging (WI) and T2WI demonstrated millimetric hypointense foci and linear signal void areas in all lesions. Consistent with the hypervascular features of the tumour, intense contrast enhancement was observed during the early stages of dynamic contrast enhanced (DCE) MRI. Linear signal void areas showed contrast enhancement, but some of the hypointense millimetric foci remained without contrast enhancement. Although the radiological findings and preoperative diagnosis of SCO have been reported to be non-specific and impossible, respectively, in the literature, the characteristics of MRI and different patterns of contrast enhancement can help in recognising this rare entity. This article represents a single institution case series of SCOs and also includes the first description of a correlation of the histopathological findings with radiological findings and new clues in the differential diagnosis of SCOs. We described these new radiological clues as "Hasiloglu's Signs".

SEMAC-VAT MR Imaging Unravels Peri-instrumentation Lesions in Patients With Attendant Symptoms After Spinal Surgery.

The study aimed for evaluating the diagnostic value of a 2D Turbo Spin Echo (TSE) magnetic resonance (MR) imaging sequence implanted slice-encoding metal artifact correction (SEMAC) and view-angle tilting (VAT) in patients with spinal instrumentation.Sixty-seven consecutive patients with an average age of 59.7 ± 17.8 years old (range: 32–75 years) were enrolled in this study. Both sagittal, axial T1-weighted and T2-weighted MRI images were acquired with a standard TSE sequence and a high-bandwidth TSE sequence implemented the SEMAC and VAT techniques. Three continuous sections around the instrumentation in axial and sagittal images were selected for quantitative evaluation. The measurement included cumulative areas of signal void on axial images and the length of spinal canal obscuration on sagittal images. Three radiologists independently evaluated all images blindly. The inter-observer reliability was evaluated with inter-class coefficient. We defined patients with discomfortable symptoms caused by spinal instrumentation as spinal instrumentation adverse reaction.Visualizations of all periprosthetic anatomic structures were significantly better for SEMAC-VAT compared with standard imaging. For axial images, the area of signal void at the level of the instrumentation were statistically reduced with SEMAC-VAT TSE sequences than with standard TSE sequences for T2-weighted images (9.9 ± 2.6 cm2 vs 29.8 ± 14.7 cm2, P < 0.001). For sagittal imaging, the length of spinal canal obscuration at the level of the instrumentation was reduced from 5.2 ± 2.0 cm to 1.2 ± 0.6 cm on T2-weighted images (P < 0.001), and from 4.8 ± 2.1 cm to 1.1 ± 0.5 cm on T1-weighted images with SEMAC-VAT sequences (P < 0.001). Interobserver agreement for visualization of anatomic structures and image quality was good for both SEMAC-VAT (k = 0.77 and 0.68, respectively) and standard (k = 0.74 and 0.80, respectively) imaging. The number of abnormal findings noted on SEMAC images (59 findings) was significantly higher than detected on standard images (40 findings). The incidence rate of spinal instrumentation adverse reaction was 38.81%.MR images with SEMAC-VAT can significantly reduce metal artifacts for spinal instrumentation and improve delineation of the instrumentation and periprosthetic region. Furthermore, SEMAC-VAT technique can improve diagnostic accuracy in patients with post-instrumentation spinal diseases.

Abstract 90: Cerebral Microbleeds in CADASIL: Influence of APOE Genotype and Hypertension

Introduction: CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is a genetic disorder with an important predisposition for development of cerebral microbleeds (CMB). However, the relative impact of the two most common risk factors for CMB, hypertension and cerebral amyloid angiopathy, in CADASIL is uncertain. Hypothesis: We hypothesized that APOE (apolipoprotein E, an important predictor and correlate of cerebral amyloid angiopathy) genotype and hypertension influenced the presence and distribution of CMB in patients with CADASIL. Methods: CMB were identified as small (up to 10 mm) areas of signal void seen on 3.0T MRI susceptibility-weighted images. The locations of CMB were characterized as lobar, deep, and infra-tentorial. Results: In 83 patients with CADASIL (mean age 62.5 years), CMB were observed in 69.9% (58/83) of the total patient population. The most common areas of CMB were deep (57.8%, 48/83), lobar (50.6%, 42/83), and infra-tentorial location (38.4%, 33/83). Hypertension was found in 59% (49/83) of patients. APOE genotype frequencies were: ε2/ε3 9.6% (8/83); ε2/ε4 2.4% (2/83); ε3/ε3 57.8% (48/83); ε3/ε4 30.1% (25/83). Hypertension was associated with presence of CMB in lobar (p&lt;0.001), deep (p=0.035), and infra-tentorial locations (p=0.012). However, no significant associations were found between APOE genotype and presence of CMB in any location. Conclusions: In this cohort of CADASIL patients, hypertension but not APOE genotype predicted presence of CMB in all locations. These findings suggest that hypertension may amplify the arteriopathy of CADASIL in the development of CMB.

Value of real-time sharewave elastography in Achilles tendinopathy: Ultrasound technology of the future?

To determine if the viscoelastic properties of Achilles tendon assessed by real-time sharewave elastography (SWE) are modified in tendinopathy and provide informations for subsequent applications of this technique. Twenty-six abnormal tendons (16 unilateral and 5 bilateral tendinopathy) from 21 patients with Achilles tendinopathy and 176 normal tendons (from 16 patients and 80 healthy volunteers) were prospectively included and compared. Mean sharewave velocity (Vmean) was measured on axial and sagittal SWE images at two degrees of passive ankle flexion (position 1: complete plantar flexion? and position 2: 0 degree flexion). Tendon maximum anteroposterior and lateral diameters, cross sectional area and the presence of tears were also noted. In position 1, the abnormal tendons Vmean was significantly lower than for contralateral normal tendons on sagittal ( Δ = 1.23 m/s, P = 0.004) and axial elastograms ( Δ = 0.68 m/s, P = 0.03)? and significantly lower than for normal tendons only on axial images ( Δ = 0.49 m/s, P = 0.01). In position 2 and on axial elastograms, the abnormal tendons Vmean was 1.14 m/s lower than for contralateral normal tendons however without reaching statistical significance ( P = 0.07). In position 2, the abnormal tendons Vmean was significantly lower than for normal tendons on sagittal ( Δ = 1.26 m/s, P < 0.001) and axial elastograms ( Δ = 0.52 m/s, P = 0.05). In tendon with complete tears Vmean was significantly lower than for normal tendons on both sagittal and axial images and in both positions ( P < 0.001). All tears ( n = 4) appeared as signal void areas. Abnormal Achilles tendons have lower Vmean and are therefore softer than normal tendons. There is no SWE signal into tendon tears. Tendon softening, assessed by realtime SWE, is a new helpful tool in the evaluation of Achilles tendinopathy. SWE may also provide quantitative parameters to assess the severity of tendinopathy to monitor the effect of therapeutics.

A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging.

PurposeThis study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging.Materials and MethodsA dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images.ResultsStatistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets.ConclusionWith respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

Viscoelasticity in Achilles tendonopathy: quantitative assessment by using real-time shear-wave elastography.

To investigate the differences in viscoelastic properties between normal and pathologic Achilles tendons (ATs) by using real-time shear-wave elastography (SWE). The institutional review board approved this study, and written informed consent was obtained from 25 symptomatic patients and 80 volunteers. One hundred eighty ultrasonographic (US) and SWE studies of ATs without tendonopathy and 30 studies of the middle portion of the AT in patients with tendonopathy were assessed prospectively. Each study included data sets acquired at B-mode US (tendon morphology and cross-sectional area) and SWE (axial and sagittal mean velocity and relative anisotropic coefficient) for two passively mobilized ankle positions. The presence of AT tears at B-mode US and signal-void areas at SWE were noted. Significantly lower mean velocity was shown in tendons with tendonopathy than in normal tendons in the relaxed position at axial SWE (P < .001) and in the stretched position at sagittal (P < .001) and axial (P = .0026) SWE. Tendon softening was a sign of tendonopathy in relaxed ATs when the mean velocity was less than or equal to 4.06 m · sec(-1) at axial SWE (sensitivity, 54.2%; 95% confidence interval [CI]: 32.8, 74.4; specificity, 91.5%; 95% CI: 86.3, 95.1) and less than or equal to 5.70 m · sec(-1) at sagittal SWE (sensitivity, 41.7%; 95% CI: 22.1, 63.3; specificity, 81.8%; 95% CI: 75.3, 87.2) and in stretched ATs, when the mean velocity was less than or equal to 4.86 m · sec(-1) at axial SWE (sensitivity, 66.7%; 95% CI: 44.7, 84.3; specificity, 75.6%; 95% CI: 68.5, 81.7) and less than or equal to 14.58 m · sec(-1) at sagittal SWE (sensitivity, 58.3%; 95% CI: 36.7, 77.9; specificity, 83.5%; 95% CI: 77.2, 88.7). Anisotropic results were not significantly different between normal and pathologic ATs. Six of six (100%) partial-thickness tears appeared as signal-void areas at SWE. Whether the AT was relaxed or stretched, SWE helped to confirm and quantify pathologic tendon softening in patients with tendonopathy in the midportion of the AT and did not reveal modifications of viscoelastic anisotropy in the tendon. Tendon softening assessed by using SWE appeared to be highly specific, but sensitivity was relatively low.

In Vivo Tracking of Novel SPIO-Molday ION Rhodamine-B&amp;#8482;-Labeled Human Bone Marrow-Derived Mesenchymal Stem Cells After Lentivirus- Mediated COX-2 Silencing: A Preliminary Study

Magnetic resonance imaging (MRI) has been used to track magnetically labeled human bone marrow-derived mesenchymal stem cells (hBMSCs) in vivo after COX-2 silencing and transplantation into nude rats via tail vein injection. In the present study, we knocked down COX-2 expression in hBMSCs through lentivirus transduction. The COX-2 knockdown was confirmed by real-time PCR and Western blotting analyses. Subsequently, we labeled cells with the novel reagent SPIO-Molday ION Rhodamine-B™ (MIRB). The viability, proliferation and differentiation of these cells were assessed in vitro. Labeled lenti-shCOX2 hBMSCs, unlabeled hBMSCs and phosphate-buffered saline (PBS) were individually injected into the tail veins of nude rat models, forming three treatment groups. All nude rats underwent GRE T2*-weighted MRI at 1 h, 7 days and 14 days post-injection. After MRI examination, the animals were sacrificed, and the brain and liver were examined by fluorescence microscopy and Prussian Blue staining. Our results confirmed the successful down-regulation of COX-2 at the mRNA and protein levels in hBMSCs by lentivirus transduction. The viability and differentiation of hBMSCs were not affected by MIRB labeling. After 7 days, hypointense signal void areas in the rat livers were observed on MRI. After 14 days, iron particles were detected in the blood vessels, sinusoids, interlobular septum and capsule tissues of the liver. The MIRB-labeled lenti-shCOX2 hBMSCs transplanted into nude rat models via tail vein injection can be detected and monitored in vivo using 3.0 T clinical MRI for up to 14 days after cell transplantation.

Shear-Wave Elastographic Features of Breast Cancers

The objective of this study was to compare the quantitative and qualitative shear-wave elastographic (SWE) features of breast cancers with mechanical elasticity and histopathologic characteristics. This prospective study was conducted with institutional review board approval, and written informed consent was obtained. Shear-wave elastography was performed for 30 invasive breast cancers in 30 women before surgery. The mechanical elasticity of a fresh breast tissue section, correlated with the ultrasound image, was measured using an indentation system. Quantitative (maximum, mean, minimum, and standard deviation of elasticity in kilopascals) and qualitative (color heterogeneity and presence of signal void areas in the mass) SWE features were compared with mechanical elasticity and histopathologic characteristics using the Pearson correlation coefficient and the Wilcoxon signed rank test. Maximum SWE values showed a moderate correlation with maximum mechanical elasticity (r = 0.530, P = 0.003). There were no significant differences between SWE values and mechanical elasticity in histologic grade I or II cancers (P = 0.268). However, SWE values were significantly higher than mechanical elasticity in histologic grade III cancers (P < 0.001), which have low amounts of fibrosis, high tumor cellularity, and intratumoral necrosis. In addition, color heterogeneity was correlated with intratumoral heterogeneity of mechanical elasticity (r = 0.469, P = 0.009). Signal void areas in the masses were present in 43% of breast cancers (13 of 30) and were correlated with dense collagen depositions (n = 11) or intratumoral necrosis (n = 2). Quantitative and qualitative SWE features reflect both the mechanical elasticity and histopathologic characteristics of breast cancers.

EVALUATION OF THE WARP‐TURBO SPIN ECHO SEQUENCE FOR 3 TESLA MAGNETIC RESONANCE IMAGING OF STIFLE JOINTS IN DOGS WITH STAINLESS STEEL TIBIAL PLATEAU LEVELING OSTEOTOMY IMPLANTS

Susceptibility artifacts caused by ferromagnetic implants compromise magnetic resonance imaging (MRI) of the canine stifle after tibial plateau leveling osteotomy (TPLO) procedures. The WARP-turbo spin echo sequence is being developed to mitigate artifacts and utilizes slice encoding for metal artifact reduction. The aim of the current study was to evaluate the WARP-turbo spin echo sequence for imaging post TPLO canine stifle joints. Proton density weighted images of 19 canine cadaver limbs were made post TPLO using a 3 Tesla MRI scanner. Susceptibility artifact sizes were recorded and compared for WARP vs. conventional turbo spin echo sequences. Three evaluators graded depiction quality for the tibial tuberosity, medial and lateral menisci, tibial osteotomy, and caudal cruciate ligament as sufficient or insufficient to make a diagnosis. Artifacts were subjectively smaller and local structures were better depicted in WARP-turbo spin echo images. Signal void area was also reduced by 75% (sagittal) and 49% (dorsal) in WARP vs. conventional turbo spin echo images. Evaluators were significantly more likely to grade local anatomy depiction as adequate for making a diagnosis in WARP-turbo spin echo images in the sagittal but not dorsal plane. The proportion of image sets with anatomic structure depiction graded adequate to make a diagnosis ranged from 28 to 68% in sagittal WARP-turbo spin echo images compared to 0-19% in turbo spin echo images. Findings indicated that the WARP-turbo spin echo sequence reduces the severity of susceptibility artifacts in canine stifle joints post TPLO. However, variable depiction of local anatomy warrants further refinement of the technique.

Vacuolar meningioma: a new and rare variant of canine meningioma

A 10-year-old female neutered boxer was presented with a two-month history of progressive ataxia and left-sided head tilt. General physical examination was unremarkable. Neurological evaluation revealed ataxia and hypermetria in...

Identification of Normal Cranial Sutures in Infants on Routine Magnetic Resonance Imaging

There are increasing concerns relating to the ionizing effects of computed tomography imaging in infants with benign conditions. Magnetic resonance imaging (MRI) is a potential alternative to ionizing radiation when determining patency of the cranial sutures; however, there is no documentation in the literature on the appearance of normal cranial sutures in infants on MRI. This study reviews the appearance of the cranial sutures, their widths, and accuracy of identification in the first year of life on MRI.The coronal, sagittal, and lambdoid sutures were evaluated by 5 assessors on 100 anonymized MRI scans in infants aged 1 to 361 days. The sutures were scored on a 3-point scale. The MRI sequences investigated were axial T1, axial T2, coronal fluid attenuated inversion recovery, axial short tau inversion recovery, and sagittal T1. The suture widths were measured in those cases where they were clearly identifiable, and agreement was obtained in the first aspect of the study (n = 38).A κ score of 0.6 was obtained for interrater agreement. An increasing total score for all sutures with advancing age was found (P < 0.05). The mean suture widths for the coronal, sagittal, and lambdoid sutures were 1.2 (SD, 0.4), 1.4 (SD, 0.4), and 1.3 (SD, 0.3) mm, respectively. There was no significant difference in suture width with age.The appearance of cranial sutures on MRI is as an area of signal void, which may be difficult to clearly define, thus making it unreliable as a standard investigation in the diagnosis of craniosynostosis.

In Vivo MRI Tracking of Polyethylenimine-Wrapped Superparamagnetic Iron Oxide Nanoparticle–Labeled BMSCs for Cartilage Repair

Objective:To evaluate the feasibility of tracking polyethylenimine (PEI)-wrapped superparamagnetic iron oxide (SPIO) nanoparticle–labeled, bone marrow–derived mesenchymal stem cells (BMSCs) by in vivo magnetic resonance imaging (MRI) in articular cartilage repair in a minipig model.Methods:Eighteen Guizhou minipigs were randomly divided into three groups (groups A, B, and C). In group A, PEI-wrapped SPIO nanoparticle (PEI/SPIO) and green fluorescent protein (GFP) colabeled, autologous BMSCs seeded in type II collagen gel were transplanted into the articular cartilage defects of the minipig model. In group B, GFP-labeled, autologous BMSCs seeded in type II collagen gel were transplanted. In group C, no treatment was applied for cartilage defects. All minipigs underwent clinical 3.0-T MR imaging at 4, 8, 12, and 24 weeks postsurgery. The findings were compared histologically.Results:Prussian staining and transmission electron microscope showed that BMSCs were efficiently labeled by PEI/SPIO. Cell viability, proliferation, and differentiation were comparable between labeled and unlabeled cells. MRI SET2WI sequence revealed that marked hypointense signal void areas representing the transplanted labeled BMSCs could be observed for at least 24 weeks. Histochemical staining confirmed the presence of Prussian blue–positive cells and GFP-positive cells at the hypointense signal void areas. At 24 weeks postsurgery, both MR signals and histologic staining of minipigs in groups A and B at the cartilage defect were close to the normal cartilage.Conclusions:3.0-T MRI in vivo tracking of PEI/SPIO-labeled BMSCs seeded in type II collagen gel on cartilage repair following transplantation is feasible in minipigs.

In Vivo Tracking of Superparamagnetic Iron Oxide Nanoparticle Labeled Chondrocytes in Large Animal Model

Chondrocytes have been widely used as tissue engineered seed cells for repair of focal cartilage lesions in clinic. However, in vivo behaviors of delivered chondrocytes are still poorly understood. In this study, the feasibility of in vivo tracking of superparamagnetic iron oxide nanoparticle (SPIO)-labeled chondrocytes by magnetic resonance imaging (MRI) for articular cartilage repair in minipig model was investigated. Results showed that chondrocytes were efficiently labeled by SPIO at optimal low dosages while maintaining essential cell properties. MRI SET2WI sequence revealed that marked hypointense signal void areas representing the transplanted labeled chondrocytes could be observed for at least 12weeks. Histochemical staining confirmed the presence of Prussian blue-positive cells and GFP-positive cells at the hypointense signal void areas. These findings provide knowledge on the in vivo tracking of SPIO labeled chondrocytes on cartilage repair following transplantation in minipigs.

Percutaneous MR-guided cryoablation of prostate cancer: initial experience

We report our initial experience and the technical feasibility of transperineal prostate cryoablation under MR guidance. Percutaneous MR-guided cryoablation was performed in 11 patients with prostatic adenocarcinoma contraindicated for surgery (mean age: 72 years, mean Gleason score: 6.45, mean prostate-specific antigen (PSA): 6.21 ng/ml, T1-2c/N0/M0, mean: prostate volume 36.44 ml). Free-hand probe positioning was performed under real-time MR imaging. Four to seven cryoprobes were inserted into the prostate, depending on gland volume. The ice ball was monitored using real-time and high-resolution BLADE multi-planar imaging. Patients were followed at 1, 3, 6, 9 and 12 months after the procedure with serum PSA level and post-ablation MRI. Prostate cryoablation was technically feasible in 10/11 patients. The ice ball was clearly and sharply visualised in all cases as a signal-void area. Mean ice-ball volume was 53.3 ml. Mean follow-up was 15 months (range: 1-25). Mean PSA nadir was 0.33 ng/ml (range: 0.02-0.94 ng/ml). Mean hospitalisation was 5 days (range: 3-13). Complications included a urethro-rectal fistula, urinary infection, transient dysuria and scrotal pain. MR-guided prostate cryoablation is feasible and promising, with excellent monitoring of the ice ball. Future perspectives could include the use of MR guidance for focal prostate cancer cryotherapy. • Magnetic resonance allows precise positioning of cryoprobes with real-time imaging. • High-resolution MRI allows excellent monitoring of the developing ice ball. • Cryoablation of prostate cancer under MR guidance is technically feasible. • Further work will refine the procedure and make it even safer.

Epidural capillary hemangioma of the thoracic spine with proximal nerve root involvement and extraforaminal extension

Dear Editor, The occurrence of purely epidural capillary hemangioma is exceedingly rare, with only four reported cases in the English literature [3, 6, 7, 12]. Because of the excessive vascularity of capillary hemangioma, en bloc removal and/ or preoperative embolization of feeding arteries of the lesion should be recommended [8]. However, as consensus magnetic resonance imaging (MRI) study and specific features regarding capillary hemangiomas are not yet available, they are usually misdiagnosed preoperatively [3, 7]. Here, we report a case of a capillary hemangioma of the thoracic epidural region, with particular emphasis on relevant radiological features that could aid in the differential diagnosis of the lesion and therefore allow appropriate management. A 59-year-old woman presented with a 1-year history of back pain and right intercostal neuralgia. Physical examination revealed proprioceptive ataxia that caused difficulties with walking, decrease of the motor strength in lower limbs, and brisk osteotendinous reflexes. MRI (Fig. 1a–d) demonstrated a well-circumscribed, probably epidural, avidly enhancing mass that extended from T5 to T7, with intrathoracic extension through the right foramen at T6–T7, abutting the adjacent pleura. Signal void areas in and around the lesion indicated the presence of draining veins, suggesting the differential diagnosis of vascular pathologies such as hemangioma or hemangioblastoma. A T5–T7 laminectomy was performed with removal of the right T6–T7 facet joint and corresponding costotransverse joint to expose the whole lesion. The spongy, redpurple hemorrhagic epidural mass (Fig. 1e) was clearly originating from the T6 proximal nerve root, easily cleaved from the dura, and excised en bloc (Fig. 1f) as planned preoperatively. Many small feeder branches and vessels draining into the epidural venous system were sacrificed. The estimated intraoperative blood loss was 2 l. Pathologic examination showed innumerable thin-walled capillary vessels, lined by flattened endothelium and embedded within a loose connective tissue stroma (Fig. 1g) consistent with a capillary hemangioma. Unlike cavernous hemangiomas, the lesion was devoid of abnormally hyalinized vascular channels, thromboses, calcifications, or surrounding deposition of hemosiderin pigment. Capillary hemangiomas are considered hamartomatous proliferations of vascular endothelial cells [2]. They are classified by the predominant type of vascular channel (capillary, cavernous, arteriovenous, or venous) observed at histological examination. Epidural hemangiomas are actually considered to be an extension of vertebral lesions [4, 5]. The occurrence of purely spinal epidural hemangiomas is exceedingly rare, and most of the reported cases were a cavernous type [4, 5, 9]. However, as histological differentiation between capillary hemangioma and cavernous hemangioma is not always unequivocal, some epidural capillary hemangiomas may have been published under the designation of cavernous F. Vassal : C. Nuti Department of Neurosurgery, North Hospital, University Hospital of Saint-Etienne, Saint-Etienne, France

Subthreshold Micropulse Diode Laser and Double Frequency Neodymium: YAG Laser in Treatment of Diabetic Macular Edema: A Prospective, Randomized Study Using Multifocal Electroretinography

The purpose of this study was to compare the efficacy of subthreshold micropulse diode (SDM) laser with double-frequency neodymium YAG (Nd:YAG) laser in treatment of clinically significant diabetic macular edema. Forty-six eyes of 33 patients with clinically significant macular edema (CSME) caused by diabetic retinopathy were randomized to either SDM (810?nm) laser or the conventional double-frequency Nd:YAG (532?nm) laser. Primary outcome measures were: change in the central macular thickness as measured by optical coherence tomography (OCT) and change in macular retinal sensitivity measured using multifocal electroretinography (MfERG). Secondary outcomes were: change in best corrected visual acuity (BCVA) and contrast sensitivity. The group was divided in half, with 23 eyes assigned to SDM laser and 23 eyes assigned to double-frequency Nd:YAG laser. Mean follow-up period was 6 months. No statistically significant difference was noted in either the primary or the secondary outcome measures between the two groups. Macular thickness decreased from the baseline measures of 298.5?49.3 and 312.9?45.8??m to 274.9?62.9 and 286.7?32.8??m in the SDM laser and Nd:YAG laser groups, respectively. On MfERG, P1 implicit wave time delay at baseline changed from 46.27?4.9 to 45.27?3.4?ms in the SDM group and from 46.55?4.9 to 45.27?4.1?ms in the Nd:YAG group. MfERG recordings of 18 of the 23 eyes treated with double-frequency Nd:YAG laser showed areas of signal void as compared to 4 eyes treated with the SDM laser. SDM laser photocoagulation showed an equally good effect on visual acuity, contrast sensitivity, and reduction of diabetic macular edema (DME) as compared to conventional Nd:YAG laser photocoagulation. MfERG recordings, however, suggest that SDM laser results in better preservation of electrophysiological indices.

Low‐intensity pulsed ultrasound increases cellular uptake of superparamagnetic iron oxide nanomaterial: Results from human osteosarcoma cell line U2OS

To determine whether low-intensity pulsed ultrasound (LIPUS) is able to facilitate the uptake of a superparamagnetic iron oxide (SPIO) nanomaterial by cells that do not express high endocytosis capacity. The human osteosarcoma cell line U2OS and a silica-coated SPIO functionalized peripherally with amines groups (overall diameter 8 nm) were used in this study. Adherent U2OS cells were labeled with SPIO by incubating with culture media containing the SPIO at 4.5 microg[Fe]/mL. LIPUS with the same parameters as those used in clinical application to accelerate bone fracture healing (1.5 MHz, duty cycle 1:4, spatial-average temporal-average intensity 30 mW/cm(2)) was applied to the cells at the beginning of the labeling process for 0, 0.5, 1, or 3 hours. The total incubation time with SPIO was 12 hours. SPIO labeling efficiency was evaluated with Prussian blue staining and a blueness measurement method, and magnetic resonance imaging (MRI) of cell pellets via measuring areas of SPIO-induced signal void. Both Prussian blue staining and in vitro MRI demonstrated that LIPUS application increased the SPIO nanomaterial labeling efficiency for U2OS cells in an exposure-duration-dependent manner. This study is a "proof of concept" that LIPUS can facilitate the cellular take-up of SPIO nanomaterial.