Supervision of low-grade gliomas with multiparametric MR imaging: research of radiologic indicators of malignancy transformation

We assessed the contribution of diffusion, perfusion and spectroscopy imaging for the diagnosis and follow-up of intraaxial tumors, suspected to be grade II gliomas. Twenty-four patients were included from April 2005 to July 2006, 17 initially and seven during their follow-up. The diagnosis was reconsidered in a first group of six patients: a high-grade tumor was suspected and confirmed in five. These patients presented a lipid peak; the perfusion results and the CHO/Cr and CHO/NAA ratios were not pathological. The second group included patients with grade II gliomas: these 18 patients had a radiographic work-up, initially, then at three months and every six months. For this group, no evidence of a change of grade were observed. Abnormal findings were noted in seven patients: among these patients, one developed radiographic progression, one other had radiographic progression associated with a spectroscopy lipid peak; only spectroscopy changes were noted in the third patient; the last patient had radiographic progression with perfusion and spectroscopy abnormalities; these four patients were treated. These observations suggest that diffusion, perfusion and spectroscopy can provide supplementary information for diagnosis and follow-up of glial tumors. The presence of a lipid peak is of particular value. The limitations of this work must also be taken into consideration: the follow-up was too short for slow-growing gliomas; the population was small and patients may have undergone surgery during the study, leading to structural modifications which may have compromised comparisons. This work should be continued with new examinations every six months and inclusion of new patients.     

Newly developed mini-endoscope for diagnosis and follow-up of orthotopic bladder transitional-cell carcinoma in vivo

BACKGROUND AND PURPOSE: Orthotopic models of bladder transitional-cell carcinoma (TCC) are indispensable to the development of new intravesical agents for the treatment of non-muscle-invasive disease. Visual inspection of induced tumors and normal urothelium is of crucial interest when evaluating growth patterns and the potential effects of instillation therapies. The aim of our study was to test the practicability of a newly developed mini-endoscope in terms of the benefit and reproducibility of repeated diagnostic cystoscopy in a rat model, thus mimicking standard procedures in patients. MATERIALS AND METHODS: The study group consisted of 24 Foxn(rnu) athymic nude rats. In 18 animals, a suspension of the human TCC cell line UMUC-3 was instilled into the urinary bladder after trypsinization. Six animals underwent bladder trypsinization only and served as a control group. Follow-up cystoscopy was performed weekly. A newly developed semirigid mini-endoscope (Karl Storz, Tuttlingen, Germany), 0.89 mm in diameter, was used. RESULTS: In total, 213 cystoscopies were performed. Each animal underwent at least seven procedures at weekly intervals over a period of 2 months. All tumors were detected by the mini-endoscope within 14 days of tumor-cell implantation. Cystoscopy provided visibility of the entire lower urinary tract (LUT), with the smallest detectable lesion being 0.5 mm in diameter. The regularly performed cystoscopy was tolerated without any significant procedure-related morphologic alterations in the LUT. CONCLUSIONS: The new mini-endoscope constitutes a practicable and reliable tool for diagnosis and regular follow-up cystoscopy in rats. This instrument can contribute to the preclinical development of experimental intravesical antitumor agents when used for regular evaluations of morphologic drug effects in vivo.     

Newly Developed Hybrid Suture without Lubricant: Noninvasive In Vivo Assessment of Biocompatibility with Multiparametric MR Imaging

Magnetic resonance imaging (MRI) and magnetic resonance (MR) relaxometry were used to assess noninvasively the tissue response of a new uncoated hybrid braided suture made from a combination of ultra-high-molecular-weight polyethylene (UHMWPE) and polyester (polyethylene terephthalate) (PET) yarns in comparison to a silicone impregnated braided 100% polyester (PET) control suture (Ticron). Both biomaterials were monitored for a period of 30 days following implantation in both incised and nonincised paravertebral rabbit muscles. In all cases, MR images and relaxometry demonstrated that the hybrid suture elicited either a milder or a similar tissue and cellular response compared to the control suture. These findings were confirmed by conventional histological analysis of the surrounding tissues. They also demonstrated that the hybrid suture promoted faster healing in terms of collagen infiltration between the yarns and individual filaments. This milder inflammatory reaction and improved biocompatibility represent a real advantage in the healing performance of sutures for cardiac and vascular surgery, and support the need for continued research and development of hybrid structures. This study also demonstrated the ability of MRI techniques to noninvasively evaluate the biocompatibility of biomaterials. By extending the capacity of MR diagnostic tools from patients to experimental animals, it is now possible to validate the healing performance of foreign materials with statistical reliability and fewer animals.     

MR imaging assessment of myocardial edema with T2 mapping

Cardiac magnetic resonance (CMR) provides a high signal-to-noise ratio, high spatial and temporal resolutions, as well as a delayed-enhancement sequence and is therefore considered a reference technique in the field of cardiac imaging. However, currently available sequences are not adequate to assess some pathologic conditions, such as myocardial edema. T2 mapping sequences generate parametric images that are based on the transverse relaxation time (T2) for each voxel. In case of edema, the T2 relaxation time is longer. This review summarizes current knowledge on CMR T2 mapping for assessing myocardial edema.     

Rotator cuff repair with a novel mesh suture: An ex vivo assessment of mechanical properties

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy‐two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques—simple interrupted sutures and two‐row suture bridge—were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull‐out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re‐tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987–992, 2018.

     

3.0T磁共振扩散加权成像技术无创评估肝硬化分级

目的：探讨不同b值表观扩散系数（ADC）值、指数化表观扩散系数（eADC）值以及灌注ADC值和eADC值在肝硬化分级及肝功能损害评估方面的价值。方法：对53例肝硬化患者肝脏进行DWI扫描,并计算低（100 s/mm2、200 s/mm2和300 s/mm2）、中（400 s/mm2和600 s/mm2）和高（800s/mm2、1 000 s/mm2和1 200 s/mm2）b值时肝组织的ADC值和eADC值,然后根据低、高b值时ADC和eADC值的差异计算灌注ADC和eADC值。分析DWI各测量参数与Child-Pugh分级及与临床肝功能血清检测指标之间的关系。结果：低b值ADC值、中b值的ADC和eADC值以及灌注ADC值在Child-Pugh分级之间均见统计学差异（P〈0.05）,其余测量值未见统计学差异（P〉0.05）。低b值ADC值与AST负相关（P=0.040,r=-0.554）,中b值ADC值分别与TP、ALB正相关（P=0.006,r=0.814;P=0.034,r=0.570）,但与GLO负相关（P=0.017,r=-0.601）,灌注ADC值也与AST负相关（P=0.021,r=-0.643）,其余参数之间均未见相关性（P〉0.05）。结论：利用DWI技术可对肝硬化的程度进行分级,ADC值相关参数也可在一定程度上反映肝硬化时肝功能情况。     

Diffusion-weighted MR imaging in the preoperative assessment of brain abscesses

BACKGROUND

Diffusion-weighted MR imaging (DWI) has recently shown promise in differentiating ring-enhancing lesions such as brain abscess and malignant neoplasm. The ability of DWI to strongly suggest brain abscess enables a neurosurgeon to alter stereotactic planning to optimize diagnosis. We report our experience with DWI in 5 patients with lesions on MR imaging and review the literature to assess the usefulness of this technique in the preoperative evaluation of cerebral abscess.

METHODS

The MR images of 5 patients presenting with ring-enhancing lesions that ultimately proved to be brain abscesses were retrospectively reviewed. In addition to standard MR sequences, trace DWI and apparent diffusion coefficient (ADC) calculations were performed on all patients. Additionally, 15 recently published articles or references in press concerning DWI in cerebral abscesses were reviewed.

RESULTS

All lesions were markedly hyperintense on DWI and had diminished ADC. Thirty-eight of 39 previously reported abscesses were hyperintense on DWI with reduced ADC. Of 165 nonpyogenic lesions with DWI findings, 87 were hypointense or isointense, 78 lesions had variable hyperintensities, and few manifested the degree of hyperintensity observed with abscesses. Most of these included chordomas and epidermoids, which are not likely to be confused with abscesses.

CONCLUSIONS

Restricted water diffusion, as indicated by hyperintensity on DWI and low ADC, in ring-enhancing lesions assists in differentiating brain abscess from necrotic tumor. This information facilitates stereotactic surgical planning: abscesses should be preferentially centrally aspirated, whereas necrotic brain tumors should have diagnostic tissue biopsied from cavity walls. Although not definitive for brain abscess, restricted water diffusion is an important MR imaging sign and is useful in neurosurgical treatment strategies for ring-enhancing lesions.     

动态增强MRI定量诊断女性垂体泌乳素微腺瘤

目的定量分析动态增强MRI诊断女性垂体泌乳素微腺瘤的各参数指标,探索各参数的最佳阈值。方法分析30例女性垂体泌乳素微腺瘤及30名健康女性腺垂体动态增强MRI,比较泌乳素微腺瘤与正常腺垂体时间-信号强度曲线（TIC）的形态、达峰时间、强化率、强化斜率。采用ROC法确定垂体泌乳素微腺瘤的诊断阈值,并计算诊断敏感度、特异度。结果当以达峰时间66s作为诊断阈值时,其敏感度为76.70%,特异度为84.40%;以强化斜率为2.015作为诊断阈值时,其敏感度为88.50%,特异度为67.10%;达峰时间、强化率、强化斜率联合诊断的诊断点为0.566时,其敏感度92.20%,特异度87.53%。结论可将动态增强MR扫描达峰时间66s、强化斜率2.015及达峰时间、强化率、强化斜率联合诊断点为0.566作为诊断垂体泌乳素微腺瘤的参考阈值。     

Effects of sex and age on bone microstructure at the ultradistal radius: a population-based noninvasive in vivo assessment.

In a population-based cross-sectional study, we examined effects of sex and age on bone microstructure at the wrist using high-resolution 3-D pQCT. Compared with women, men had thicker trabeculae in young adulthood and had less microstructural damage with aging. These findings may contribute to the virtual immunity of men to age-related increases in wrist fractures. INTRODUCTION: Although changes in bone microstructure contribute to fracture risk independently of BMD, it has not heretofore been possible to assess this noninvasively in population-based studies. MATERIALS AND METHODS: We used high-resolution 3-D pQCT imaging (voxel size, 89 mum) to define, in a random sample of women (n = 324) and men (n = 278) 21-97 years of age, sex and age effects on bone microstructure at the wrist. RESULTS: Relative to young women (age, 20-29 years), young men had greater trabecular bone volume/tissue volume (BV/TV; by 26%, p = 0.001) and trabecular thickness (TbTh; by 28%, p < 0.001) but similar values for trabecular number (TbN) and trabecular separation (TbSp). Between ages 20 and 90 years, cross-sectional decreases in BV/TV were similar in women (-27%) and in men (-26%), but whereas women had significant decreases in TbN (-13%) and increases in TbSp (+24%), these parameters had little net change over life in men (+7% and -2% for TbN and TbSp, respectively; p < 0.001 versus women). However, TbTh decreased to a greater extent in men (-24%) than in women (-18%; p = 0.010 versus men). CONCLUSIONS: Whereas decreases with age in trabecular BV/TV are similar in men and women, the structural basis for the decrease in trabecular volume is quite different between the sexes. Thus, over life, women undergo loss of trabeculae with an increase in TbSp, whereas men begin young adult life with thicker trabeculae and primarily sustain trabecular thinning with no net change in TbN or TbSp. Because decreases in TbN have been shown to have a much greater impact on bone strength compared with decreases in TbTh, these findings may help explain the lower life-long risk of fractures in men, and specifically, their virtual immunity to age-related increases in distal forearm fractures.     

Validation of marrow fat assessment using noninvasive imaging with histologic examination of human bone samples

PurposeThe marrow composition throughout the body is heterogeneous and changes with age. Due to heterogeneity, invasive biopsies of the iliac crest do not truly represent the complete physiological status, impeding the clinical effectiveness of this method. Therefore, we aim to provide verification for an in vivo imaging technique using co-registered histologic examinations for assessment of marrow adiposity.MethodsFive recently expired (i.e. < 24 h) human cadavers were scanned with a dual source CT (DECT) scanner in order to measure marrow fat in the lumbar vertebrae. These donors were also imaged using water–fat MRI (wfMRI) which was used to estimate the fraction of yellow marrow. After imaging, lumbar columns were excised and the superior and inferior aspects of 21 vertebrae were removed. The remaining center section was processed for histological examination to find the ratio of adipocyte volume per tissue volume (AV/TV).ResultsResults of DECT and wfMRI had a high correlation (r = 0.88). AV/TV ranged from 0.18 to 0.75 with a mean (SD) of 0.36 (0.18). Inter-evaluator reliability for AV/TV was r > 0.984. There were similar correlations between AV/TV and the imaging modalities, DECT-derived MF and wfMRI (r = 0.802 and 0.772, respectively).ConclusionsA high MF variation was seen among the 25 vertebrae imaged. Both DECT and wfMRI have a good correlation with the histologic adipocyte proportion and can be used to measure MF. This makes longitudinal studies possible without painful, less-effective, invasive biopsies.     

In vivo imaging and noninvasive ablation of pyramidal neurons in adult NEX-CreERT2 mice

To study the function of individual neurons that are embedded in a complex neural network is difficult in mice. Conditional mutagenesis permits the spatiotemporal control of gene expression including the ablation of cells by toxins. To direct expression of a tamoxifen-inducible variant of Cre recombinase (CreERT2) selectively to cortical neurons, we replaced the coding region of the murine Nex1 gene by CreERT2 cDNA via homologous recombination in embryonic stem cells. When injected with tamoxifen, adult NEX-CreERT2 mice induced reporter gene expression exclusively in projection neurons of the neocortex and hippocampus. By titrating the tamoxifen dosage, we achieved recombination in single cells, which allowed multiphoton imaging of neocortical neurons in live mice. When hippocampal projection neurons were genetically ablated by induced expression of diphteria toxin, within 20 days the inflammatory response included the infiltration of CD3+ T cells. This marks a striking difference from similar studies, in which dying oligodendrocytes failed to recruit cells of the adaptive immune system.     

The biocompatibility of suture materials used in colon surgery. An experimental study in the rat

BACKGROUND: The aim of this experimental study was to compare the tissue behavior of biofragmentable anastomotic ring (BAR) with other synthetic materials used in colonic surgery. METHODS: Thirty-three rats were divided into four groups: group 1, sham-operated control animals without material implanted; group 2, with fragments of polypropylene monofilament implanted extraperitoneally in abdominal wound, between musculature and peritoneum; group 3, with metal clips implanted extraperitoneally in abdominal wound, between musculature and peritoneum and group 4, with fragments of biofragmentable anastomotic ring implanted extraperitoneally in abdominal wound, between musculature and peritoneum. Animals were sacrificed 30 days after the operation. Macroscopic and histological criteria were used to characterize the resistance of the wound and the tolerance of the host to the foreign material. RESULTS: The inflammatory cell reaction of host tissue was significantly greater in group 4 compared with other groups (p < 0.05). In three cases, in group 4, we observed the adhesion of implanted fragment to epiploa. The enumeration of giant cells and the degree of fibrotic reaction was similar in all groups with material implanted, but no significant difference between the groups was observed. Our findings showed the greater biocompatibility of polypropylene and metallic clips, compared to the biofragmentable ring anastomosis. The strong inflammatory reaction in the host tissue caused by biofragmentable anastomotic ring may explain partially clinical postoperative complications (anastomotic wound infection and/or dehiscence and/or stricture). CONCLUSIONS: In conclusion, the choice of suture materials should be based not only on the mechanical properties, but also on their biological interactions between host and suture materials and on the evaluation of their effective cost/benefit.     

A novel, noninvasive imaging technique for intraoperative assessment of parathyroid glands: confocal reflectance microscopy

BACKGROUND: Successful surgical management of primary hyperparathyroidism requires the ability to identify and distinguish normal from abnormal parathyroid tissue. Microscopic pathologic confirmation often helps with the diagnoses and decisions regarding the extent of parathyroid resection. Confocal reflectance microscopy (CRM) is an optical method of noninvasively imaging tissue without fixation, sectioning, and staining as in standard histopathology. The goal of this study was to determine if CRM imaging could be used to distinguish normal from diseased parathyroid tissue intraoperatively. METHODS: In this study, 44 parathyroid glands from 21 patients undergoing operations for primary hyperparathyroidism were imaged immediately after excision. CRM images were compared with conventional hematoxylin-and-eosin stained sections obtained from the same gland. The percentage area occupied by fat cells was calculated in images of both normal and diseased glands. RESULTS: Characteristic microscopic features of parathyroid glands were distinguishable by CRM and correlated well with histopathology. The stromal fat content of normal and diseased glands could easily be determined. The percentage area occupied by fat cells differed significantly (P <.00001) in normal glands (average, 23.0% +/- 10.9%) and adenomatous glands (average, 0.4% +/- 0.7%). CONCLUSIONS: CRM imaging rapidly revealed microscopic features that reliably differentiated normal and diseased parathyroid glands. The success of this preliminary ex vivo study promotes interest in further development of an in situ probe for in vivo clinical diagnostic use.     

Evaluation of haemodialysis membrane biocompatibility by parallel assessment in an ex vivo model in health y volunteers

Background. Precise evaluation of the haemocompatibility of prototype membranes, flow configurations and anticoagulant regimens is an essential step in the development of dialysis systems minimizing blood activation. An ex vivo model in humans currently employed in our laboratory has recently been adapted to allow the parallel evaluation of two minimodule dialysers with blood from a single donor, thus eliminating differences due to donor variability in the comparison of test and control dialysis modules. Methods. The ex vivo flow system is designed to reproduce the haemodynamic conditions of clinical dialysis on a 1/50 scale. A blood line from the forearm vein of the volunteer donor is divided at a Y-shaped junction, two roller pumps assure equivalent blood flow (5 ml/min) in the branches leading to two minimodule dialysers and heparin (0.1 IU/ml final concentration) is injected into each branch immediately after the Y junction. Samples for analysis of blood activation markers are collected at the exits of the two minimodules over a test period of 27 min In the present series of tests, a new polyacrylonitirile membrane (PAN) was evaluated relative to standard commercial polysulphone (PS), acrylonitrile copolymer (AN 69) and cuprophan (CUP) membranes. Results. A steady minimal level of anticoagulation corresponding to a slightly less than two-fold prolongation of APTT (activated partial thromboplastin time) was maintained throughout testing in both branches of the ex vivo flow system. Time curves for the accumulation of activation markers (thrombin-antithrombin II complexes, prothrombin fragment 1+2, platelet {beta}-thromboglobulin, and complement fragment C3a) showed all four types of minimodule dialyser to induce comparable low levels of activation of coagulation parameters and platelets, together with similar mild activation of complement for AN 69, PAN, and PS dialysers as compared to stronger activation for CUP modules. Overall results thus confirmed the acceptable haemocompatibility of the prototype polyacrylonitrile (PAN) membrane. Conclusions. Among current methods for evaluation of the biocompatibility of haemodialysis systems, ex vivo flow models in humans avoid problems arising from species differences and may be designed to closely reproduce the conditions of clinical dialysis. A parallel configuration eliminates artefacts due to individual variations in donor response. This not only facilitates the direct comparison of test and control membranes under close to identical experimental conditions, but also provides a model particularly well adapted to studies of the effects of different anticoagulation regimens, flow configurations and dialysates, or alternative methods of sterilization, rinsing and priming of the dialysers.     

Bronchogenic carcinoma staging: CT versus MR imaging. Assessment with surgery

One hundred and twenty patients with bronchogenic carcinoma were prospectively studied by both computed tomography (CT) and magnetic resonance imaging (MRI) during the 2 weeks preceding thoracotomy or mediastinoscopy. MRI scans included contiguous axial and coronal slices. Results of CT and MRI studies were compared with the surgical and pathological findings on the basis of the TNM classification. Although no significant difference was found between the two imaging methods for the evaluation of tumour extent, MRI appears to be a valuable imaging technique for left upper lobe and apical neoplasms. Comparison between the two techniques for mediastinal node evaluation showed that sensitivity of MRI is superior to CT in the left paratracheal, aortopulmonary and subcarinal node areas.     

Graft rejection in the xenogeneic transplantation of mice: diagnosis with in vivo MR imaging using the homing trait of macrophages

Abstract: Background: To evaluate the feasibility of magnetic resonance (MR) imaging to depict the in vivo recruitment of superparamagnetic iron oxide (SPIO)‐labeled macrophages and to diagnose graft rejection in xenogeneic transplantation. Methods: We transplanted the trachea of SD rat (xenogeneic) or C3H/HeN mouse (syngeneic) into the left thighs of six male C3H/HeN mice. The SPIO‐labeled macrophage was administered through the tail vein 2 days (acute) or 14 days (chronic) after transplantation in each group. The left thighs of the mice were imaged on a 4.7‐T MR scanner 24 h after macrophage administration. We evaluated the extent and pattern of the susceptibility effect (macrophage distribution) and compared them in the two groups. The MR findings were then correlated with the histopathologic results. We also measured in both groups the monocyte chemoattractant protein (MCP)‐1 level before and 2 days, 2 weeks, and 4 weeks after transplantation. Results: The band‐shaped lower signal intensity (SI) zone was noted around the graft in the acute and chronic phases of xenogeneic group and in the acute phase of syngeneic group, but it was not noted in the chronic phase of syngeneic transplantation. The lower SI zone corresponded to the distribution of SPIO‐labeled macrophages on histopathological analyses. On histologic examination, the severe inflammation developed around the xenogeneic graft, but only slightly around the syngeneic graft. MCP‐1 was elevated 2 days after transplantation in both groups, but then gradually decreased in the syngeneic group; in xenogenic group, the MCP‐1 value decreased by week 2 but then increased by week 4. Conclusions: This study demonstrates that the homing of intravenously administered SPIO‐labeled macrophages can be monitored on MR imaging and is correlated with the MCP‐1 level and the histopathologic findings of the xenograft rejection.