Signal Intensity Of Tissue Research Articles

MRI thresholds for discrimination between normal and mild temporomandibular joint involvement in juvenile idiopathic arthritis.

BackgroundCurrently there is no consensus agreement on the degree of enhancement in normal temporomandibular joints (TMJ) in children, which makes it difficult for clinicians to distinguish between the presence/absence of mild synovitis. Quantitative measurements of synovial and condylar enhancement may be useful additions to current qualitative methods on early MRI diagnosis and follow up of TMJ involvement in JIA. The purpose of the study is to establish thresholds/tendencies for quantitative measures that enable distinction between mild TMJ involvement and normal TMJ appearance based on the degree of synovial and bone marrow enhancement in JIA patients.MethodsTMJ MRI examinations in 67 children with JIA and in 24 non-rheumatologic children who underwent MRI for neurologic/orbit indications were retrospectively assessed. As a priori determined TMJs of JIA patients were categorized into three groups by experienced staff radiologists based on the degree of synovial and condylar enhancement: no active disease (rheumatologic control), mild and moderate/severe findings. The signal intensity (SI) of the synovial tissue around each condyle and of the bone marrow was measured to calculate the enhancement ratio (ER) and relative SI change. The ER was calculated using signal to noise ratios, while relative SI change was calculated using signal intensities alone. Quantitative measurements of synovial and condylar enhancement of TMJs with mild or moderate/severe findings were compared with the rheumatologic and non-rheumatologic controls.ResultsMean ER values were significantly different between the TMJs without active disease and those with mild and moderate/severe synovial enhancement, with highest values in the moderate/severe group (P < 0.0001). Similar findings were seen for condylar enhancement with P < 0.005. Relative SI change was unable to differentiate TMJs with mild synovitis from the two controls (P > 0.10). 27/60 (45 %) TMJs without active disease had osteochondral changes. 8/40 (20 %) TMJs in the mild group did not demonstrate any synovial thickening.ConclusionsQuantitative signal to noise ratios of TMJ synovial and condylar enhancement generate thresholds/tendencies, which offer additional information to differentiate mild synovitis from normal TMJs in JIA patients. Osteochondral changes and synovial thickening may not be reliable indicators of active TMJ involvement and should be differentiated from synovial enhancement.

Contrast Leakage Patterns from Dynamic Susceptibility Contrast Perfusion MRI in the Grading of Primary Pediatric Brain Tumors.

The pattern of contrast leakage from DSC tissue signal intensity time curves have shown utility in distinguishing adult brain neoplasms, but has limited description in the literature for pediatric brain tumors. The purpose of this study is to evaluate the utility of grading pediatric brain tumors with this technique. A retrospective review of tissue signal-intensity time curves from 63 pediatric brain tumors with preoperative DSC perfusion MR imaging was performed independently by 2 neuroradiologists. Tissue signal-intensity time curves were generated from ROIs placed in the highest perceived tumor relative CBV. The postbolus portion of the curve was independently classified as returning to baseline, continuing above baseline (T1-dominant contrast leakage), or failing to return to baseline (T2*-dominant contrast leakage). Interobserver agreement of curve classification was evaluated by using the Cohen κ. A consensus classification of curve type was obtained in discrepant cases, and the consensus classification was compared with tumor histology and World Health Organization grade. Tissue signal-intensity time curve classification concordance was 0.69 (95% CI, 0.54-0.84) overall and 0.79 (95% CI, 0.59-0.91) for a T1-dominant contrast leakage pattern. Twenty-five of 25 tumors with consensus T1-dominant contrast leakage were low-grade (positive predictive value, 1.0; 95% CI, 0.83-1.00). By comparison, tumors with consensus T2*-dominant contrast leakage or return to baseline were predominantly high-grade (10/15 and 15/23, respectively) with a high negative predictive value (1.0; 95% CI, 0.83-1.0). For pilomyxoid or pilocytic astrocytomas, a T1-dominant leak demonstrated high sensitivity (0.91; 95% CI, 0.70-0.98) and specificity (0.90, 95% CI, 0.75-0.97). There was good interobserver agreement in the classification of DSC perfusion tissue signal-intensity time curves for pediatric brain tumors, particularly for T1-dominant leakage. Among patients with pediatric brain tumors, a T1-dominant leakage pattern is highly specific for a low-grade tumor and demonstrates high sensitivity and specificity for pilocytic or pilomyxoid astrocytomas.

Contrast-enhanced MRI of the temporomandibular joint: findings in children without juvenile idiopathic arthritis.

Contrast-enhanced magnetic resonance imaging (MRI) is highly sensitive for assessing temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA), but only sparse data exist on normal TMJ appearance in children. To determine normal MRI appearance and enhancement pattern of pediatric TMJ as basis for diagnosing early arthritis. In 27 children (age range, 1.2-16.8 years) without TMJ pathology undergoing head MRI, fat-saturated T2-weighted (T2W) and postcontrast fat-saturated T1-weighted (T1W) images sagittally aligned to the 54 TMJs, besides standard T1W and T2W images, were assessed for bony and soft tissue signal intensity (SI), the amount of perceptible joint fluid, and contrast enhancement (CE). Bone marrow SI and CE of the mandible were consistent with varying degrees of residual red marrow in 96% of joints. The mandibular condyles were mostly isointense to the ramus, but in 9% showed mild edema-like bone marrow SI and CE. Small amounts of intraarticular fluid were detected in 31% on T2W images without fat saturation and in 83% on T2W images with fat saturation as fine lines in the upper or lower joint compartment or as small dots in an articular recess. Seventy-nine percent of all TMJs showed intense joint enhancement on early images restricted to areas of intraarticular fluid. Small amounts of joint fluid with intense CE are a common MRI finding in TMJs of children without JIA and therefore should not be considered diagnostic for early arthritis.

Abdominal vasculature in dynamic contrast-enhanced liver MRI at 3.0 T: an intraindividual comparative study using gadoxetate disodium and gadofosveset trisodium

ObjectivesTo intraindividually compare gadoxetate disodium and gadofosveset trisodium regarding vessel contrast, image quality and vessel delineation in dynamic contrast-enhanced liver MRI at 3.0T. MethodsTwelve patients underwent 3.0T MRI twice (24 examinations) with a single dose of gadoxetate disodium and gadofosveset trisodium, respectively. Signal intensity in abdominal vessels and tissue was determined. Vessel-to-background ratio (VBR) was calculated for each vessel and dynamic phase. All images were evaluated by two radiologists regarding image quality, vessel delineation and anatomic variants or pathologies with digital subtraction angiography as the standard of reference. ResultsGadofosveset trisodium demonstrated a significantly higher VBR compared to gadoxetate disodium (arterial phase: 0.57±0.12 [SD] vs. 0.46±0.19; portal venous phase: 0.51±0.11 vs. 0.37±0.14; equilibrium phase: 0.48±0.10 vs. 0.31±0.13; p≤0.01). Image quality and vessel delineation were rated equal or better for gadofosveset trisodium in all cases. These differences were not significant for most vessel segments. All anatomic variants were correctly identified by both readers for both contrast agents. ConclusionsAlthough gadofosveset trisodium provides a significantly higher vessel contrast at 3.0T, gadoxetate disodium is equivalent by qualitative measurements. Thus, gadoxetate-enhanced liver MRI at 3.0T enables reliable assessment of the upper abdominal vasculature with the additional benefit of hepatobiliary imaging.

Abstract 1479: Investigation of the permeation and retention of biocompatible low-retention superparamagnetic iron oxide nanoclusters in tumors with magnetic resonance imaging

Abstract Superparamagnetic iron oxide (SPIO) nanoclusters assembled with poly-L-lysine (PLL) and hydroxyl starch show a unique bioclearance property with low retention in the liver and spleen and effective renal excretion. In the orthotopic liver tumor model, the assembled low retention biocompatible SPIO nanoclusters exhibit a high contrast enhancing capability in T2-weighted magnetic resonance imaging (MRI) at a low dose. For the orthotopic liver tumor, the T2-weighted MRI with SPIO nanoclusters is a negative imaging method to reduce the signal intensity of the normal liver tissue, whereas the potential of the retention and permeability of SPIO nanoclusters in tumors was not fully assessed. The latter becomes critically important for diagnosis and prognosis of pancreatic and prostate tumors in the non-reticuloendothelial system. Two approaches of tumor targeting were investigated and compared in this study including the passive targeting via the EPR effect of nanoparticles and the active targeting by the tumor-specific ligands such as TAT, iRGD and pH sensitive peptides. The accumulation of SPIO nanoclusters in tumors was assessed in the subcutaneous pancreatic and prostate tumor models with MRI over times, iron levels and pathological assessment. Our results showed that the retention and permeation of SPIO nanoclusters varied with multiple factors of tumors. For example, well developed tumors with large necrosis core tended to have a high level of SPIO accumulation. In contrast, the early stage solid tumor had minimal retention of SPIOs. Similar effects have been observed in both passive and active tumor targeting by SPIO nanoclusters. Moreover, the accumulation of SPIOs in tumor was achieved over a longer time period over 24 to 48 h with long retention as compared with those in the normal liver, lung, and spleen tissue (between 30 min to 3 h) with rapid clearance. Our data suggested that with well-designed tumor targeting, the biocompatible low-retention SPIO nanoclusters could be an effective MRI contrast agent for MRI of pancreatic and prostate tumors. Citation Format: Yushuang Wei, Liang Shan, Paul Wang, Qibing Zhou. Investigation of the permeation and retention of biocompatible low-retention superparamagnetic iron oxide nanoclusters in tumors with magnetic resonance imaging. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1479. doi:10.1158/1538-7445.AM2015-1479

Diagnosis of retrodiscal tissue in painful temporomandibular joint (TMJ) by fluid-attenuated inversion recovery (FLAIR) signal intensity

Aims:The purpose of the present study is to analyze the fluid-attenuated inversion recovery (FLAIR) signal intensity of the retrodiscal tissue in a painful temporomandibular joint (TMJ), and to develop a diagnostic system based on FLAIR data.Methodology:The study was based on 33 joints of 17 patients referred for MR imaging of the TMJ. Regions of interest were placed over retrodiscal tissue and gray matter (GM) on FLAIR images. Using signal intensities of GM as reference points, signal intensity ratios (SIR) of retrodiscal tissue were calculated. SIRs in painful TMJ were compared with those in painless TMJ. Wilcoxon’s Rank Sum Test was used to analyze the difference in SIRs between the painful and painless groups (P<0·05).Results:The SIRs of retrodiscal tissue were significantly higher in painful joints than in painless joints.Conclusion:FLAIR sequences provide a high signal in patients having painful TMJ, and it suggests that retrodiscal tissue in painful TMJ contains elements such as protein.

Ultra-fast Steady-State Free Precession Pulse Sequence for Fourier Decomposition Pulmonary MRI.

To assess whether ultra-fast steady-state free precession (ufSSFP) can improve image quality in Fourier decomposition (FD) MRI of lung ventilation and perfusion. Series of two-dimensional time-resolved lung images were acquired in healthy volunteers at 1.5 Tesla (T) and 3T using an FD adapted ufSSFP. For comparison, the imaging protocol was complemented by a standard implementation of the FD MRI technique using balanced steady-state free precession (bSSFP). Imaging parameters were evaluated to optimize the ufSSFP FD MRI protocol with respect to the signal intensity of the lung parenchyma and the severity of image artifacts. FD MRI with the adapted ufSSFP pulse sequence resulted in increased signal intensity in the lung tissue by 19% and significantly decreased banding artifacts due to shorter repetition times: 1.46 ms for ufSSFP and 1.90 ms for bSSFP. Despite improved image quality FD MRI is still problematic at 3T. MRI of the lung with ufSSFP performs better than bSSFP in terms of signal and banding artifacts, and can be used to either increase resolution or overall image quality of FD images.

Ex vivo magnetic resonance imaging in South African manganese mine workers

BackgroundManganese (Mn) exposure is associated with increased T1-weighted magnetic resonance imaging (MRI) signal in the basal ganglia. T1 signal intensity has been correlated with occupational Mn exposure but not with clinical symptomatology or neuropathology. ObjectivesThis study investigated predictors of ex vivo T1 MRI basal ganglia signal intensity in neuropathologic tissue obtained from deceased South African mine workers. MethodsA 3.0T MRI was performed on ex vivo brain tissue obtained from 19 Mn mine workers and 10 race- and sex-matched mine workers of other commodities. Basal ganglia regions of interest were identified for each subject with T1-weighted intensity indices generated for each region. In a pathology subset, regional T1 indices were compared to neuronal and glial cell density and tissue metal concentrations. ResultsIntensity indices were higher in Mn mine workers than non-Mn mine workers for the globus pallidus, caudate, anterior putamen, and posterior putamen with the highest values in subjects with the longest cumulative Mn exposure. Intensity indices were inversely correlated with the neuronal cell density in the caudate (p=0.040) and putamen (p=0.050). Tissue Mn concentrations were similar in Mn and non-Mn mine workers. Tissue iron (Fe) concentration trended lower across all regions in Mn mine workers. ConclusionsMn mine workers demonstrated elevated basal ganglia T1 indices when compared to non-Mn mine workers. Predictors of ex vivo T1 MRI signal intensity in Mn mine workers include duration of Mn exposure and neuronal density.

No Association Between Fibrosis on Magnetic Resonance Imaging at Return to Play and Hamstring Reinjury Risk

Background: Connective tissue scar (fibrosis) is a common finding on magnetic resonance imaging (MRI) after recovery from acute hamstring injuries. Fibrosis has been suggested as a predisposing factor for reinjury, but evidence from clinical studies is lacking. Purpose/Hypothesis: The aim of this study was to examine the association between the presence of fibrosis on MRI at return to play after an acute hamstring injury and the risk of reinjury. The hypothesis was that fibrous tissue on MRI was associated with an increased reinjury risk. Study Design: Cohort study; Level of evidence, 3. Methods: Magnetic resonance images were obtained from 108 consecutive athletes with modified Peetrons classification grade 1 or 2 hamstring injuries within 5 days of injury and within 7 days of return to play. The presence and extent of abnormally low signal intensity in the intramuscular tissue on MRI, suggestive of fibrosis, were assessed on both T1- and T2-weighted images. Reinjuries were recorded over a 1-year follow-up period. The association between fibrosis and reinjury risk was analyzed with a Cox proportional hazards model. Results: The MRIs of the initial injury showed 45 (43%) grade 1 and 63 (57%) grade 2 injuries. Median time of return to play was 30 days (interquartile range [IQR], 22-42 days). At return to play, 41 athletes (38%) had fibrosis on MRI with a median longitudinal length of 5.8 cm (IQR, 3.3-12.5 cm) and a median volume of 1.5 cm3 (IQR, 1.5-3.9 cm3). In athletes with fibrosis, 24% (10/41) sustained a reinjury, and in the subjects without fibrosis, 24% (16/67) had a reinjury, resulting in a hazard ratio of 0.95 (95% CI, 0.43-2.1; P = .898). Conclusion: Fibrosis is commonly seen on MRI at return to play after grade 1 or 2 hamstring injuries but is not associated with reinjury risk.

A Model of Population and Subject (MOPS) Intensities With Application to Multiple Sclerosis Lesion Segmentation.

White matter (WM) lesions are thought to play an important role in multiple sclerosis (MS) disease burden. Recent work in the automated segmentation of white matter lesions from magnetic resonance imaging has utilized a model in which lesions are outliers in the distribution of tissue signal intensities across the entire brain of each patient. However, the sensitivity and specificity of lesion detection and segmentation with these approaches have been inadequate. In our analysis, we determined this is due to the substantial overlap between the whole brain signal intensity distribution of lesions and normal tissue. Inspired by the ability of experts to detect lesions based on their local signal intensity characteristics, we propose a new algorithm that achieves lesion and brain tissue segmentation through simultaneous estimation of a spatially global within-the-subject intensity distribution and a spatially local intensity distribution derived from a healthy reference population. We demonstrate that MS lesions can be segmented as outliers from this intensity model of population and subject. We carried out extensive experiments with both synthetic and clinical data, and compared the performance of our new algorithm to those of state-of-the art techniques. We found this new approach leads to a substantial improvement in the sensitivity and specificity of lesion detection and segmentation.

Low-field magnetic resonance anatomic features of the neonatalfoal thorax: an ex vivo study

The purpose of this study was to describe the normal appearance of the bony and soft tissue structures of the thorax of neonatal foals by low-field magnetic resonance imaging (MRI) and the use of anatomical dissections and gross sections. Three purebred Spanish neonatal foals that died for medical reasons unrelated to thoracic disease were used to obtain T1- and T2-weighted MR images using a magnet of 0.2 Tesla. Anatomic structures on the MR images were evaluated according to characteristics of signal intensity of the different organic tissues. The bones, different associated muscles, diaphragm, trachea, main bronchi, lungs, esophagus, heart chambers, and associated great vessels were well-visualized and evaluated with a low magnetic field. MRI provided correct discrimination of thoracic structures, and this information could be used as an initial anatomic reference for the interpretation of MR images of the thoraxes of neonatal foals.

Automatic segmentation of subcutaneous mouse tumors by multiparametric MR analysis based on endogenous contrast.

Contrast-enhanced T1-weighted imaging is usually included in MRI procedures for automatic tumor segmentation. Use of an MR contrast agent may not be appropriate for some applications, however. We assessed the feasability of automatic tumor segmentation by multiparametric cluster analysis that uses intrinsic MRI contrast only. Multiparametric MRI consisting of quantitative T1, T2, and apparent diffusion coefficient (ADC) mapping was performed in mice bearing subcutaneous tumors (n = 21). k-means and fuzzy c-means clustering with all possible combinations of MRI parameters, i.e. feature vectors, and 2-7 clusters were performed on the multiparametric data. Clusters associated with tumor tissue were selected on the basis of the relative signal intensity of tumor tissue in T2-weighted images. The optimum segmentation method was determined by quantitative comparison of automatic segmentation with manual segmentation performed by three observers. In addition, the automatically segmented tumor volumes from seven separate tumor data sets were quantitatively compared with histology-derived tumor volumes. The highest similarity index between manual and automatic segmentation (SI manual,automatic = 0.82 ± 0.06) was observed for k-means clustering with feature vector {T2, ADC} and four clusters. A strong linear correlation between automatically and manually segmented tumor volumes (R (2) = 0.99) was observed for this segmentation method. Automatically segmented tumor volumes also correlated strongly with histology-derived tumor volumes (R (2) = 0.96). Automatic segmentation of mouse subcutaneous tumors can be achieved on the basis of endogenous MR contrast only.

Evaluation of superparamagnetic iron oxide-polymer composite microcapsules for magnetic resonance-guided high-intensity focused ultrasound cancer surgery

BackgroundSuperparamagnetic poly (lactic-co-glycolic acid) (PLGA)-coated Fe3O4 microcapsules are receiving increased attention as potential diagnostic and therapeutic modalities in the field of oncology. In this study, PLGA-coated Fe3O4 microcapsules were combined with a magnetic resonance imaging-guided high-intensity focused ultrasound (MR-guided HIFU) platform, with the objective of investigating the effects of these composite microcapsules regarding MR-guided HIFU liver cancer surgery in vivo.MethodsPLGA-coated Fe3O4 microcapsules consisting of a liquid core and a PLGA-Fe3O4 shell were fabricated using a modified double emulsion evaporation method. Their acute biosafety was confirmed in vitro using MDA cells and in vivo using rabbits. To perform MR-guided HIFU surgery, the microcapsules were intravenously injected into a rabbit liver tumor model before MR-guided HIFU. T2-weighted images and MR signal intensity in normal liver parenchyma and tumor tissue were acquired before and after injection, to assess the MR imaging ability of the microcapsules. After MR-guided HIFU ablation tissue temperature mapping, the coagulative volume and histopathology of the tumor tissue were analyzed to investigate the ablation effects of MR-guided HIFUs.ResultsScanning and transmission electron microscopy showed that the microcapsules displayed a spherical morphology and a shell-core structure (mean diameter, 587 nm). The hysteresis curve displayed the typical superparamagnetic properties of the microcapsules, which are critical to their application in MR-guided HIFU surgery. In MR-guided HIFU surgery, these microcapsules functioned as an MRI contrast agent, induced significant hyperthermal enhancement (P < 0.05) and significantly enhanced the volume of coagulative necrosis (P < 0.05).ConclusionsThe administration of PLGA-coated Fe3O4 microcapsules is a potentially synergistic technique regarding the enhancement of MR-guided HIFU cancer surgery.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-800) contains supplementary material, which is available to authorized users.

Effect of Mesenchymal Stem Cells on the Vascularization of the Artificial Site for Islet Transplantation in Rats

An adequate vascularization of the artificially created cavity is crucial for subsequent transplantation of isolated pancreatic islets. In a reported study, dynamic contrast-enhanced magnetic resonance imaging was used to assess the effect of mesenchymal stem cells on neoangiogenesis within connective tissue surrounding an implantable biocompatible device. The signal increase detected after injection of magnetic resonance contrast agent in each target region was considered to be an effect of contrast agent, which was related to the blood supply. To minimize the influence of variability in contrast agent application, all outcomes measured in the implanted devices were normalized to the signal intensity of kidney tissue. When supported by mesenchymal stem cells, the mean signal increase intra-abdominally was 42%, 41%, and 64% and within subcutaneously implanted devices was 23%, 54%, and 52% of that measured in kidney.

Technical review, types of imaging, part 4--magnetic resonance imaging.

Technical review, types of imaging, part 4--magnetic resonance imaging.

Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR.

White matter hyperintensities (WMH) seen on T2WI are a hallmark of multiple sclerosis (MS) as it indicates inflammation associated with the disease. Automatic detection of the WMH can be valuable in diagnosing and monitoring of treatment effectiveness. T2 fluid attenuated inversion recovery (FLAIR) MR images provided good contrast between the lesions and other tissue; however the signal intensity of gray matter tissue was close to the lesions in FLAIR images that may cause more false positives in the segment result. We developed and evaluated a tool for automated WMH detection only using high resolution 3D T2 fluid attenuated inversion recovery (FLAIR) MR images. We use a high spatial frequency suppression method to reduce the gray matter area signal intensity. We evaluate our method in 26 MS patients and 26 age matched health controls. The data from the automated algorithm showed good agreement with that from the manual segmentation. The linear correlation between these two approaches in comparing WMH volumes was found to be Y = 1.04X + 1.74 (R 2 = 0.96). The automated algorithm estimates the number, volume, and category of WMH.

Gadoxetate uptake as a possible marker of hepatocyte damage after liver resection-preliminary data

To determine the feasibility of evaluating surgically induced hepatocyte damage using gadoxetate disodium (Gd-EOB-DTPA) as a marker for viable hepatocytes at magnetic resonance imaging (MRI) after liver resection. Fifteen patients were prospectively enrolled in this institutional review board-approved study prior to elective liver resection after informed consent. Three Tesla MRI was performed 3-7 days after surgery. Three-dimensional (3D) T1-weighted (W) volumetric interpolated breath-hold gradient echo (VIBE) sequences covering the liver were acquired before and 20min after Gd-EOB-DTPA administration. The signal-to-noise ratio (SNR) was used to compare the uptake of Gd-EOB-DTPA in healthy liver tissue and in liver tissue adjacent to the resection border applying paired Student's t-test. Correlations with potential influencing factors (blood loss, duration of intervention, age, pre-existing liver diseases, postoperative change of resection surface) were calculated using Pearson's correlation coefficient. Before Gd-EOB-DTPA administration the SNR did not differ significantly (p=0.052) between healthy liver tissue adjacent to untouched liver borders [59.55±25.46 (SD)] and the liver tissue compartment close to the resection surface (63.31±27.24). During the hepatocyte-specific phase, the surgical site showed a significantly (p=0.04) lower SNR (69.44±24.23) compared to the healthy site (78.45±27.71). Dynamic analyses revealed a significantly lower increase (p=0.008) in signal intensity in the healthy tissue compared to the resection border compartment. EOB-DTPA-enhanced MRI may have the potential to be an effective non-invasive tool for detecting hepatocyte damage after liver resection.

An imaging protocol for dynamic contrast-enhanced breast MRI with 3.0T: using sagittal sequence interleaved between axial sequences

B1 transmission-field inhomogeneity has been reported at 3.0 Tesla (T) breast imaging. Enhancement measurements of breast cancers at 3.0T may be insufficient for some patients and improvements in imaging protocols are needed. To quantify B1 inhomogeneities in normal tissue and malignant masses at 3.0T breast MR imaging and to evaluate effect of an imaging protocol using an interleaved sagittal sequence in dynamic contrast-enhanced MRI (DCE-MRI). A total of 76 patients were included who underwent DCE-MRI of the breast at 3.0T with an imaging protocol consisting of 1st, 2nd, and 4-6th bilateral axial sequences, and 3rd and 7th unilateral sagittal sequences. Signal intensity (SI) of normal breast tissue was measured at nipple level in four bilateral locations (anterior, posterior, medial, and lateral). Mean whole breast and location specific SI were calculated and compared between right and left breast using a paired t-test. All malignant masses were classified into three groups according to tumor size on MRI (≤2 cm, 2-4 cm, >4 cm). SI of malignant masses was measured independently on axial and sagittal sequences. The axial-sagittal SI gap in each mass was calculated and difference between right and left breast was compared using the t test. Size of each malignant mass was compared with pathologic findings to assess performance of the imaging protocol. SI of normal breast tissue were lower for the right breast (R-L difference, -91.9; P < 0.0001) and in all four locations (anterior, P < 0.01; posterior, P < 0.01; medial, P < 0.0001; lateral, P < 0.0001). SI of malignant masses were lower for the right breast among same size of the lesions (P < 0.0001), particularly < 4 cm (P < 0.0001). Decreased right to left difference in SI was produced with an interleaved sagittal sequence, as axial-sagittal gap of malignant masses was significant when tumor locates on the right side (P < 0.001). The concordance rate in predicting size of mass in this imaging protocol was 92.2%. The interleaved sagittal sequence is helpful to adjust reduced SI of malignant masses on right breast at 3.0T. This imaging protocol is clinically applicable by adding a single sequence during DCE-MRI of the breast.

Reconstruction of Osteochondral Lesions of the Talus With Autologous Spongiosa Grafts and Autologous Matrix-Induced Chondrogenesis

Background: Osteochondral lesions (OCLs) of the talus are a common entity in sports orthopaedics. There are several operative techniques with a good outcome on follow-up examinations. However, limitations such as sacrificing healthy cartilage (osteochondral autograft transfer system [OATS], mosaicplasty), multiple-stage operative procedures (matrix-induced autologous chondrocyte transplantation [MACI], autologous chondrocyte implantation [ACI]), high costs (ACI, allograft), and limited availability (allograft) do remain and reflect potential drawbacks of the currently used techniques. Purpose: To describe a novel operative technique for the treatment of OCLs of the talus in the form of an economically efficient, 1-step procedure combining OCL debridement, spongiosaplasty, and sealing of the OCL area with a collagen matrix. Study Design: Case series; Level of evidence, 4. Methods: Twenty-six patients underwent surgery receiving a modified autologous matrix-induced chondrogenesis (AMIC)–aided repair of OCLs of the talus consisting of debridement, autologous grafting, and sealing of the defect with a collagen scaffold. Ligament repair was performed in 17 of 26 cases. A corrective calcaneal osteotomy was performed in 16 of 26 cases. Clinical and radiological assessment was performed before and a minimum of 24 months after surgery (mean, 31 months; range, 24-54 months). Clinical examination included the American Orthopaedic Foot and Ankle Society (AOFAS) ankle score and the visual analog scale (VAS) for pain. Radiological imaging included single-photon emission computed tomography–computed tomography (SPECT-CT) and magnetic resonance imaging (MRI). The magnetic resonance observation of cartilage repair tissue (MOCART) score was applied, and sport activity was documented. Results: The AOFAS ankle score improved significantly from a mean of 60 points preoperatively (range, 17-79 points) to 89 points (range, 61-100 points) postoperatively (P < .01). The preoperative pain score averaged 5 (range, 2-8), improving to an average of 1.6 (range, 0-7) postoperatively (P < .01). The MOCART score for cartilage repair tissue on postoperative MRI averaged 62 points (range, 20-95 points). Complete filling of the defect at the level of the surrounding cartilage was found in 35%, and complete filling with a hypertrophic cartilage layer was found in 50% of the patients. Normal signal intensity of the repair tissue compared with the adjacent native cartilage was seen in 15%, with nearly normal activity in 69%. Nineteen patients (73%) participated in sports before the onset of symptoms compared with 3 (12%) at the time of surgery. The number increased to 16 patients (62%) at postoperative follow-up. Conclusion: The modified AMIC procedure is safe for the treatment of OCLs in the ankle with overall good clinical and MRI results.

Wireless Amplified Nuclear MR Detector (WAND) for High-Spatial-Resolution MR Imaging of Internal Organs: Preclinical Demonstration in a Rodent Model

To assess the feasibility of imaging deep-lying internal organs at high spatial resolution by imaging kidney glomeruli in a rodent model with use of a newly developed, wireless amplified nuclear magnetic resonance (MR) detector. This study was approved by the Animal Care and Use Committee at the National Institutes of Health/National Institute of Neurologic Disorder and Stroke. As a preclinical demonstration of this new detection technology, five different millimeter-scale wireless amplified nuclear MR detectors configured as double frequency resonators were chronically implanted on the medial surface of the kidney in five Sprague-Dawley rats for MR imaging at 11.7 T. Among these rats, two were administered gadopentetate dimeglumine to visualize renal tubules on T1-weighted gradient-refocused echo (GRE) images, two were administered cationized ferritin to visualize glomeruli on T2*-weighted GRE images, and the remaining rat was administered both gadopentetate dimeglumine and cationized ferritin to visualize the interleaved pattern of renal tubules and glomeruli. The image intensity in each pixel was compared with the local tissue signal intensity average to identify regions of hyper- or hypointensity. T1-weighted images with 70-μm in-plane resolution and 200-μm section thickness were obtained within 3.2 minutes to image renal tubules, and T2*-weighted images of the same resolution were obtained within 5.8 minutes to image the glomeruli. Hyperintensity from gadopentetate dimeglumine enabled visualization of renal tubules, and hypointensity from cationic ferritin enabled visualization of the glomeruli. High-spatial-resolution images have been obtained to observe kidney microstructures in vivo with a wireless amplified nuclear MR detector.