Serial Contrast-enhanced Magnetic Resonance Imaging Research Articles

Calvarial diploic venous channels: delineation with maximal intensity projection technique.

To date, very few studies have explored the three-dimensional architecture of calvarial diploic venous channels (CDVCs). This study aimed to characterize the three-dimensional architecture of CDVCs using maximum intensity projection (MIP) images based on contrast-enhanced magnetic resonance imaging (MRI). A total of 77 patients with intact calvarial hemispheres and underlying dura mater and dural sinuses underwent contrast-enhanced MRI. Among them, we extracted the data of 49 with at least a part of the major CDVC pathways identified on the MIP images for analysis. On serial contrast-enhanced MRI images, the CDVCs were commonly detected as curvilinear structures with inhomogeneous diameters and tributaries, while the MIP images delineated the three-dimensional architecture of the developed CDVC pathways. More than such CDVC pathway was entirely delineated on the right in 67.3% and on the left in 71.4%, most frequently in the frontal and temporal regions, with their connecting sites to the sphenoparietal and superior sagittal sinuses. The morphology, distribution, and course of the identified CDVCs were highly variable. In 55.1%, the CDVCs formed fenestrations that were variable in size, shape, and number. The developed CDVC pathways may be characterized by morphological variability and fenestrations. Thin-sliced, contrast-enhanced MRI is useful to depict diploic veins, while MIP images allow for better appreciation of the entire course of the developed CDVC pathways. Traumatic and intraoperative disconnection between the dura mater overlying the dural sinuses and the adjacent inner table of the skull can cause epidural venous bleeding.

C-X-C Motif Chemokine Receptor 4 Blockade Promotes Tissue Repair After Myocardial Infarction by Enhancing Regulatory T Cell Mobilization and Immune-Regulatory Function.

Acute myocardial infarction (MI) elicits an inflammatory response that drives tissue repair and adverse cardiac remodeling. Inflammatory cell trafficking after MI is controlled by C-X-C motif chemokine ligand 12 (CXCL12) and its receptor, C-X-C motif chemokine receptor 4 (CXCR4). CXCR4 antagonists mobilize inflammatory cells and promote infarct repair, but the cellular mechanisms are unclear. We investigated the therapeutic potential and mode of action of the peptidic macrocycle CXCR4 antagonist POL5551 in mice with reperfused MI. We applied cell depletion and adoptive transfer strategies using lymphocyte-deficient Rag1 knockout mice; DEREG mice, which express a diphtheria toxin receptor-enhanced green fluorescent protein fusion protein under the control of the promoter/enhancer region of the regulatory T (Treg) cell-restricted Foxp3 transcription factor; and dendritic cell-depleted CD11c-Cre iDTR mice. Translational potential was explored in a porcine model of reperfused MI using serial contrast-enhanced magnetic resonance imaging. Intraperitoneal POL5551 injections in wild-type mice (8 mg/kg at 2, 4, 6, and 8 days) enhanced angiogenesis in the infarct border zone, reduced scar size, and attenuated left ventricular remodeling and contractile dysfunction at 28 days. Treatment effects were absent in splenectomized wild-type mice, Rag1 knockout mice, and Treg cell-depleted DEREG mice. Conversely, treatment effects could be transferred into infarcted splenectomized wild-type mice by transplanting splenic Treg cells from POL5551-treated infarcted DEREG mice. Instructive cues provided by infarct-primed dendritic cells were required for POL5551 treatment effects. POL5551 injections mobilized Treg cells into the peripheral blood, followed by enhanced Treg cell accumulation in the infarcted region. Neutrophils, monocytes, and lymphocytes displayed similar mobilization kinetics, but their cardiac recruitment was not affected. POL5551, however, attenuated inflammatory gene expression in monocytes and macrophages in the infarcted region via Treg cells. Intravenous infusion of the clinical-stage POL5551 analogue POL6326 (3 mg/kg at 4, 6, 8, and 10 days) decreased infarct volume and improved left ventricular ejection fraction in pigs. These data confirm CXCR4 blockade as a promising treatment strategy after MI. We identify dendritic cell-primed splenic Treg cells as the central arbiters of these therapeutic effects and thereby delineate a pharmacological strategy to promote infarct repair by augmenting Treg cell function in vivo.

Neoadjuvant chemotherapy adaptation and serial MRI response monitoring in ER-positive HER2-negative breast cancer

Background:Changing the neoadjuvant chemotherapy regimen in insufficiently responding breast cancer is not a standard policy. We analysed a series of patients with ‘luminal'-type breast cancer in whom the second half of neoadjuvant chemotherapy was selected based on the response to the first half.Methods:Patients with oestrogen receptor-positive (ER+) human epidermal growth factor receptor 2-negative (HER2−) breast cancer received three courses of neoadjuvant dose-dense doxorubicin and cyclophosphamide (ddAC). Three further courses of ddAC were administered in case of a ‘favourable response' on the interim magnetic resonance imaging (MRI) and a switch to docetaxel and capecitabine (DC) was made in case of an ‘unfavourable response', using previously published response criteria. The efficacy of this approach was evaluated by tumour size reductions on serial contrast-enhanced MRI, pathologic response and relapse-free survival.Results:Two hundred and forty-six patients received three courses of ddAC. One hundred and sixty-four patients (67%) had a favourable response at the interim MRI, with a mean tumour size reduction of 31% after the first three courses and 34% after the second three courses. Patients with unfavourable responsive tumours had a mean tumour size reduction of 12% after three courses and received three courses of DC rather than ddAC. This led to a mean shrinkage of 27%.Conclusion:The tumour size reduction of initially less responsive tumours after treatment adaptation adds further evidence that a response-adapted strategy may enhance the efficacy of neoadjuvant chemotherapy.

Magnetic Resonance Imaging in Pancreas Transplantation

Magnetic resonance imaging (MRI) plays an important role in the evaluation of pancreas transplantation. Standard MRI, magnetic resonance angiography, and MR cholangiopancreatography can demonstrate the changes of the anatomy after transplantation. Vascular complications are assessed by MR angiography. Magnetic resonance cholangiopancreatography reveals ductal changes resulting from acute and/or chronic rejection and determines leaks with the use of a secretin-stimulated MR cholangiopancreatography. Serial contrast-enhanced MRI may detect the diminished perfusion that is related to the graft rejection or vascular complications. In this paper, we reviewed types of pancreas transplantation procedures, complications that arise in a short and/or a long term after the transplantation, and their assessment by MRI.

The treatment of a large acoustic tumor with fractionated stereotactic radiotherapy.

The treatment of acoustic neuromas (AN) usually involves surgical excision or stereotactic radiosurgery. However, for large AN (mean diameter > 3 cm), stereotactic radiosurgery is rarely used, leaving patients with limited noninvasive treatment options. Recently, the use of fractionated stereotactic radiotherapy (FSRT) has been effective in treating small to medium-sized AN. We present a patient with a large AN treated with FSRT. The patient was a 43-year-old man presenting with imbalance, tinnitus, vertigo, and right-sided hearing decline associated with vomiting and hydrocephalus. Magnetic resonance (MR) imaging revealed a large, 3.8-cm, right cerebellopontine-angle tumor compressing the fourth ventricle. Following right frontal ventriculoperitoneal shunt placement, the patient underwent FSRT for treatment of the tumor. Using the Radionics X-Knife 4.0 3D treatment planning system, a total of 54 Gy was delivered in 1.8-Gy daily fractions with the prescription isodose line of 90%. Treatments were delivered using a dedicated Varian 6/100 linear accelerator, and head immobilization was achieved with the Gill-Thomas-Cosman relocatable stereotactic frame. The patient was subsequently evaluated with serial contrast-enhanced MR imaging. Following FSRT, local control (defined as the absence of tumor progression) was achieved, and treatment was well tolerated. There was no hearing-related, trigeminal, or facial-nerve morbidity following FSRT at 63-month follow-up. Treating a patient with a large AN with FSRT resulted in local tumor control, with no trigeminal nerve, facial nerve, or hearing-related morbidity. These results support FSRT as a potential noninvasive treatment modality for AN some would consider too large for single-fraction stereotactic radiosurgery (SRS).

Effects of balloon-based distal protection during primary percutaneous coronary intervention on early and late infarct size and left ventricular remodeling: A pilot study using serial contrast-enhanced magnetic resonance imaging

Distal protection devices are effective in preventing distal embolization during primary percutaneous coronary intervention (PCI). We investigated whether balloon-based distal protection could reduce early and late infarct size and left ventricular (LV) remodeling using serial analysis of contrast-enhanced magnetic resonance imaging (CE-MRI). Patients undergoing primary PCI for ST-segment elevation myocardial infarction within 12 hours after symptom onset were randomized to a distal protection group (n = 19) or to a control group (n = 20). The primary end point was infarct size evaluated by the volume of delayed hyperenhancement on CE-MRI at 3 days. The secondary end point included infarct size on CE-MRI at 6 months and LV remodeling assessed by the change between LV end-diastolic volume on CE-MRI at 3 days (baseline) and 6 months (follow-up). Percutaneous coronary intervention procedures were fully protected with balloon-based distal protection in all patients of the protection group. Infarct size was similar in the distal protection group and the control group at baseline (25.9 +/- 7.8% vs 26.1 +/- 8.2%; P = .93) and at follow-up (21.4 +/- 9.1% vs 18.5 +/- 9.1%; P = .51). The change in LV end-diastolic volume was 10.5 +/- 32.2 mL in the distal protection group and 8.9 +/- 40.7 mL in the control group (P = .86). There was no significant difference in the 6-month rate of major adverse cardiac events between groups (none in the distal protection group and 4 patients in the control group; P = .11). Serial CE-MRI showed that the balloon-based distal protection during primary PCI did not reduce early and late infarct size or prevent LV remodeling.

Cardiac Stem Cell Therapy

Cardiovascular disease remains the number one cause of morbidity and mortality in the United States and Europe. In the United States alone, ≈1 million patients suffer a myocardial infarction every year, with an associated mortality of 25% at 3 years.1 A more sobering statistic is the fact that there are ≈5 million Americans with congestive heart failure, with an associated 20% mortality per year. This remains the case despite advances in pharmacotherapy, cardiac resynchronization therapies, and the use of implantable cardioverter-defibrillators.2 Some patients with end-stage congestive heart failure are considered for cardiac transplantation, but the demand for this therapeutic approach greatly outweighs the availability of donor hearts. Over the past few years, several animal studies and a few clinical trials have supported the use of stem cells as a potential therapeutic modality to address this unmet clinical need. Response by Boyle et al p 358 Several different types of cells have been used in both animal studies and patients to promote the repair of damaged myocardium. The 2 main sources of stem cells are adult stem and embryonic stem (ES) cells. ### ES Cells ES cells are derived from the inner mass of developing embryos during the blastocyst stage. Characteristic features of ES cells include their proliferative and self-renewing properties and their ability to differentiate into a wide variety of cell types, including cardiac myocytes.3 The major concerns with their use in human trials include the formation of teratomas when ES cells are injected into immunocompromised animals. This is particularly important because the ES cells currently available for use in humans would be of allogeneic origin and therefore would require immunosuppression. As nuclear transfer techniques improve, they will provide a way of generating an unlimited supply of histocompatible ES cells using the nuclei of cells obtained directly from the recipient …

Endothelial Progenitor Cells at Work

Tissue replacement in the adult organism by cell-specific differentiation of autologous stem/progenitor cells has evolved as a fascinating concept in stem cell biology. After organ damage, bone marrow–derived circulating or tissue-resident progenitor cells are thought to differentiate toward the type of cell needed for repair. According to this concept, maturation of these cells would be expected to result at best in a perfect morphological and functional replacement of the injured tissue. However, in this issue of Arteriosclerosis, Thrombosis, and Vascular Biology , He et al show that endothelial progenitor cells (EPCs) are more than just as capable of in vitro angiogenic tube formation as mature endothelial cells (ECs), but are truly advantageous when it comes to stress tolerance.1 See page 2021 EPCs were originally characterized as cells that are mobilized from the bone marrow and circulate in the peripheral blood and express certain surface membrane markers including the vascular endothelial growth factor receptor (VEGF-R2) KDR and the hematopoietic progenitor cell markers CD34 and CD133.2–4 During ex vivo expansion, these cells develop morphological and functional characteristics typical for ECs, including formation of vascular-like structures in matrigel and other in vitro angiogenesis assays. Most importantly, however, transplanted EPCs exhibit an extraordinary potent in vivo capacity to improve the neovascularization of ischemic tissue in the adult organism.5 In this regard, EPCs were shown to be more effective than mature ECs in animal models of hind limb ischemia,6–8 although mature ECs are well established to exert a potent in vitro angiogenic activity. Thus, the …

Infarct remodeling after intracoronary progenitor cell treatment in patients with acute myocardial infarction (TOPCARE-AMI): mechanistic insights from serial contrast-enhanced magnetic resonance imaging

In order to investigate the crust and upper mantle structure of velocity and anisotropy for Dabieshan orogenic belt, a wide-angle reflection/refraction survey from Anyi, Jiangxi province to Zhuangmu, Anhui province, PR China, was undertaken in 1994. We reconstructed initial images of P- and S-wave velocities and two anisotropy factors with Anderson’s notation by using multi-parameter velocity analysis technique in 2D anisotropic media, and fitted the observed traveltimes for P- and S- reflecting waves to that calculated by forward modelling, and produced the final models of P- and S-wave velocity and two Anderson’s anisotropy factors. The structures of two anisotropy factors are very different from the structures of P- and S-wave velocities. The structures of P- and S-wave velocities show the characteristic of layering and blocking, and the structures of Anderson’s anisotropy factors displays the characteristics of ‘chimney’ structure. The thickness of the crust in the studied area varies in the 34–41 km range, with a mountain root beneath the Dabieshan orogenic belt. The average P-wave (and S-wave) velocity in the upper, middle and lower crust are 5.6–6.0 km/s (about 3.4 km/s), 6.2–6.3 km/s (about 3.6 km/s), and 6.4–6.8 km/s (about 4.0 km/s), respectively. The Poisson ratio varies from 0.24 to 0.29. With the polarization analysis to the phase Sg, we find that the fast polarization directions for the Yangtze block, Dabie block and northern China block are about N77°E, N18°W and N53°E, respectively. The seismic anisotropy factors are up to about 5%. The zone with strong anisotropy shows the ‘chimney’ structure, which indicates force direction endured by materials flowed upward. We inferred that the subduction of the Yangtze plate and the mantle flow of materials have played important role in exhuming the ultra-high pressure metamorphic rocks of the Dabieshan orogenic belt.

Serial contrast-enhanced magnetic resonance imaging and spectroscopic imaging of acute multiple sclerosis lesions under high-dose methylprednisolone therapy

To evaluate biochemical changes in contrast-enhancing multiple sclerosis (MS) lesions, we examined 14 patients with relapsing-remitting MS at acute clinical exacerbation with the help of contrast-enhanced magnetic resonance imaging (MRI) and 1H magnetic resonance spectroscopic imaging (1H MRSI). Using a 1.5-tesla MR system (Magnetom Vision, Siemens, Germany), we followed 29 contrast-enhancing and 24 nonenhancing MS lesions as well as normal-appearing white matter (NAWM) before and during high-dose methylprednisolone (HDMP) therapy. Metabolite ratios of N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and lactate (Lac) were calculated. A transient decrease in contrast enhancement under HDMP therapy was observed. Both groups of MS lesions showed significantly decreased NAA to Cr ratios compared to NAWM with no changes in time. Baseline 1H MRSI revealed significantly increased Cho to Cr ratios in the contrast-enhancing MS lesions (1.13 ± 0.25) compared to the nonenhancing MS lesions (0.85 ± 0.26, P < 0.001) and NAWM (0.97 ± 0.22, P = 0.015). Both the contrast-enhancing and the nonenhancing MS lesions exhibited a significant increase in Cho to Cr ratios from the second to the third 1H MRSI. We identified resonances of lactate in both groups of MS lesions and NAWM without any significant group differences or changes over time. 1H MRSI provides additional information that help to estimate macrophages' activity, cell membrane activation, and neuronal impairment within MS lesions. We believe that combined contrast-enhanced MRI and 1H MRSI may help to further investigate inflammatory processes within active MS lesions and should be employed more frequently to the research on therapy effects in MS.

Clinical safety of serial monthly administrations of gadopentetate dimeglumine in patients with multiple sclerosis: implications for natural history and early-phase treatment trials.

Serial contrast magnetic resonance imaging (MRI) has played an increasingly important role in understanding natural-history and early-treatment trials of multiple sclerosis patients. The purpose of this study is to determine whether the serial administration of gadopentetate dimeglumine at the conventional dose has any demonstrable effect on routine hematologic or serum chemistries. This study followed 56 patients with multiple sclerosis in a longitudinal natural-history trial using contrast-enhanced MRI scans over a four-year period between 1988 and 1993. Patients received between 3 and 53 doses of gadopentetate dimeglumine at 0.1 mmol/kg intravenously. A retrospective review of regular blood screening tests over this period identified no significant effect either on routine hematologic studies, as defined by complete blood count (hemoglobin, hematocrit, platelet and white blood cell counts, and mean corpuscular volume); standard serum chemistry studies, including electrolytes (sodium, potassium, chloride) and renal and liver function tests; or serum iron profiles. We conclude, therefore, that serial contrast-enhanced MRIs can be used safely as an outcome measure for Phase I/II evaluations of new therapies for multiple sclerosis.

Can we distinguish between benign versus malignant compression fractures of the spine by magnetic resonance imaging?

The authors investigate the usefulness of magnetic resonance imaging in differentiating benign versus malignant compression fractures by reviewing patients and a fracture model in a canine model. To determine the sensitivity and specificity of magnetic resonance imaging in differentiating benign versus malignant compression fractures of the spine and to obtain distinguishing features in magnetic resonance imaging. The differentiation between benign and abnormal compression fractures of the thoracolumbar spine has important implications regarding patient treatment and prognosis. Plain radiographs, bone scans, and computed tomography are not accurate imaging modalities for this purpose. Magnetic resonance imaging scans of 22 patients with confirmed lesions of the thoracolumbar spine were studied. There were 11 malignant and 11 benign lesions. Two experienced neuroradiologists blindly reviewed the magnetic resonance imaging scans and determined benign or malignant lesions. A canine study was performed to simulate a compression fracture model with a vertebral osteotomy in two dogs, and serial contrast-enhanced magnetic resonance imaging scans were performed 15, 30, 60 and 90 days after surgery. The correct interpretation between two neuroradiologists was 77% and 95%. The combined sensitivity rate was 88.5%, and the specificity rate was 89.5%. Magnetic resonance imaging reliably distinguished benign versus malignant lesions based on the anatomic distribution and intensity of signal changes of bone and adjacent tissues, contrast enhancement characteristics, and changes over time. Only one malignant lesion was misinterpreted by both neuroradiologists as benign, whereas there was one additional missed malignant lesion and three misinterpreted benign lesions by one radiologist. In the canine study, signal changes and enhancement were found 60 days after surgery, but no signal changes or enhancement were noted on the scan 90 days after surgery. Magnetic resonance imaging scans can detect malignant vertebral lesions early, but acute healing compression fractures may mimic the findings of metastatic lesions. The use of contrast-enhanced magnetic resonance imaging scans and serial magnetic resonance imagings are helpful for additional differentiation between benign and malignant compression fractures. In addition to magnetic resonance imaging scans, other diagnostic tests and clinical findings should be correlated before biopsy or surgery of the suspected lesion.

Serial contrast-enhanced magnetic resonance imaging in patients with early relapsing-remitting multiple sclerosis: implications for treatment trials.

Serial monthly contrast-enhanced MRIs were performed in 10 early relapsing-remitting patients with multiple sclerosis and 2 patients with chronic progressive disease for a period of 12 to 55 months. MRI was performed at 1.5 T using contiguous 5-mm slices with pre- and postgadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) T1-weighted and T2-weighted images. New and total number of Gd-DTPA-enhancing lesions were numbered and counted and lesion areas were correlated to an increase of > or = 0.5 in Expanded Disability Status Scale (EDSS) scores. The frequency of enhancing lesions varied from patient to patient; however, there was a correlation between a burst of enhancing lesion number and area above the individual's mean lesion frequency to an increase in EDSS score. A bootstrap analysis of the lesion count was performed to develop a statistical basis for determining population sizes for treatment trials. These results provide a basis for the potential use of contrast-enhanced MRI as a primary outcome measure in phase II treatment trials involving patients with relapsing-remitting MS.